JP2012228858A - Stainless steel foil with film and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide stainless steel foil exhibiting heat resistance at 300 to 600°C as a film, having a film thickness of 3 to 10 μm and a resistance of 1×10Ωcmor higher, and a method for manufacturing the same.SOLUTION: The method includes steps of: applying liquid mixed with a siloxane polymer, a metal alkoxide, water and a chemical modifier to a stainless steel film; and after dried, placing it in an oxygen presence atmosphere at temperatures of 260 to 340°C for 0.5 to 2.5 hours and also placing it in an atmosphere containing at least one of argon and nitrogen at temperatures of 360 to 500°C for 0.5 to 2.5 hours, or placing it in an atmosphere containing at least one of argon and nitrogen at temperatures of 360 to 500°C for 0.5 to 2.5 hours after dried.

Description

  The present invention relates to a coated stainless steel foil. The coated stainless steel foil of the present invention can be suitably used for, for example, an IC substrate, a sensor substrate, a solar cell substrate, an electrode substrate, and the like.

  Electrically insulating substrate materials are used for IC substrates, sensor substrates, solar cell substrates, electrode substrates, and the like, and are indispensable materials for the electronic and electrical industries. In recent years, with the reduction in size and weight of final products, there has been a demand for electrically insulating substrate materials that are thin, light, and have good workability.

  The coated stainless steel foil of the present invention can be applied without particular limitation as various electrically insulating substrate materials, but for the sake of convenience of explanation, in the following, an embodiment used for a “solar cell” will be described as an example.

  In order to integrate the cells of a solar battery and connect the unit cells in series, generally, a smooth or uneven insulating film is formed on a stainless steel foil, and a lower electrode is formed thereon, and Cu Lamination of semiconductor films such as -In-Ga-Se series has been performed.

  Due to the demands related to the above manufacturing process, a stainless steel foil having a coating film coated with an insulating material having high heat resistance and a low thermal expansion coefficient is desired for a silicon-based flexible thin film solar cell.

  With respect to the characteristics of the insulating film required here, it is necessary to raise the substrate temperature to about 600 ° C. during vapor deposition or to perform heat treatment at about 600 ° C. after sputtering. High heat resistance is required.

  The organic modified silica film is obtained by introducing an organic group into silica, and is a material having both inorganic heat resistance and organic flexibility. Based on such characteristics, the organically modified silica film has recently attracted attention as a material for forming an insulating film on the stainless steel foil as described above.

As an example of an organically modified silica film formed on a stainless steel foil, for example, Japanese Patent Application Laid-Open No. 2004-291453 discloses a stainless steel foil on which a SiO ₂ film is formed.

JP 2004-291453 A

However, the stainless steel foil on which the SiO ₂ film in the prior art is formed has the following problems.

For example, since the surface of the stainless steel foil as a base material usually has protrusions due to wrinkles and inclusions, it is extremely difficult to ensure insulation with SiO _{2 having} a thickness of 0.2 to 0.3 μm. On the other hand, in order to use a stainless steel foil for electronic paper or an organic EL substrate, an insulating film having a thickness of about 3 to 10 μm is usually required. The stainless steel foil on which the SiO ₂ film is formed can withstand temperatures of 300 ° C. to 600 ° C., but can only achieve a film thickness of about 0.2 to 0.3 μm, and requires an electronic thickness of 3 to 10 μm. It is not suitable for flexible substrates for paper and organic EL displays.

Polydimethylsiloxane is a well-known silicone material, and research has been conducted on the use of it to make films for various purposes. However, if polydimethylsiloxane is used under any conditions (for example, what kind of crosslinking agent is used for polydimethylsiloxane having a molecular weight), suitable physical properties (for example, heat resistance at 300 ° C. to 600 ° C.) No prior art document discloses whether a film having a thickness of 3 to 10 μm and a resistance of 1 × 10 ⁹ Ωcm ² or more can be constructed on a stainless steel foil. Absent.

  An object of the present invention is to provide a coated stainless steel foil having physical properties suitable as an electrically insulating substrate material.

A more specific object of the present invention is to provide a film having an organic film thickness of 3 to 10 μm, heat resistance of 300 ° C. to 600 ° C., and resistance of 1 × 10 ⁹ Ωcm ² or more. It is to provide a stainless steel foil.

  As a result of diligent research, the present inventor provided a specific thickness of a siloxane polymer film crosslinked with a specific type of metal and a metal alkoxide composed of a specific alkoxy group on a stainless steel foil having a specific thickness. Has been found to be extremely effective in achieving the above objective.

The coated stainless steel foil of the present invention is based on the above knowledge. More specifically, a stainless steel foil having a thickness of 20 to 200 μm and a siloxane polymer film having a thickness of 3 to 10 μm disposed on the stainless steel foil are provided. A coated stainless steel foil; and the siloxane polymer film is formed of one metal selected from Mg, Ca, Y, Al, Si, Sn, Ti, Zr, Nb, Ta, and W, and methoxy. Siloxane polymer film cross-linked with a metal alkoxide composed of four groups selected from among alkoxy groups such as ethoxy, ethoxy, propoxy, butoxy, etc., allowing duplication; ** (stainless steel with film) having physical properties as) ** 300 ℃ ~600 ℃ heat resistance foil "whole", and characterized by having a 1 × 10 ⁹ Ωcm ² or more resistors Than is.

  In the present invention, the reason why the above-described effect is obtained is estimated as follows according to the knowledge of the present inventor.

  That is, a siloxane polymer represented by polydimethylsiloxane, polydiphenylsiloxane, and polydimethyldiphenylsiloxane has a linear structure in an aqueous solution and has OH groups at both ends (FIG. 6).

  On the other hand, a metal alkoxide is a substance which is composed of a coordinated metal M and an alkoxy group OR and is described as M (OR) n. In the aqueous solution, the alkoxy group OR of the metal alkoxide is hydrolyzed to a hydroxyl group OH.

  As a result of earnest research and development, the present inventors have obtained the following knowledge.

  For example, in the case of an air atmosphere, when the temperature is 200 ° C. to 340 ° C., the OH group of polydimethylsiloxane and the OH group of metal alkoxide undergo a dehydration condensation reaction, and polydimethylsiloxane is crosslinked by metal alkoxide. (Hereinafter referred to as “cross-linking reaction between polydimethylsiloxane and metal alkoxide”). However, when the temperature of the air atmosphere exceeds 340 ° C., polydimethylsiloxane decomposes in addition to the cross-linking reaction between polydimethylsiloxane and metal alkoxide. Reaction to generate siloxane oligomer (hereinafter referred to as “siloxane oligomer generation reaction”), and further, a cross-linking reaction between polydimethylsiloxane chains accompanying the decomposition of methyl groups, which is a side chain of polydimethylsiloxane, occurs. This causes the coating to harden.

  The present inventor has discovered that the siloxane oligomer generation reaction becomes dominant as the temperature rises, and that the film constructed on the stainless steel foil is cured by crosslinking to cause cracks.

  In the case of an inert atmosphere such as argon, when the temperature is 200 ° C. to 360 ° C., a crosslinking reaction of polydimethylsiloxane and metal alkoxide occurs, but the temperature of the inert atmosphere exceeds 360 ° C. In addition to the cross-linking reaction between polydimethylsiloxane and metal alkoxide, a siloxane oligomer generation reaction occurs, and the siloxane oligomer generation reaction becomes dominant as the temperature rises. The inventor has discovered that curing due to cross-linking of siloxane chains does not occur, and as a result, no cracks occur.

  As a result of further research based on the above findings, the present inventors have made a cross-linking reaction between polydimethylsiloxane and a metal alkoxide by using only an inert atmosphere or by using an air atmosphere and an inert atmosphere in combination. Thus, it was discovered that a film thickness of 3 to 10 μm can be configured.

  Furthermore, the present inventors have removed polydimethylsiloxane that has not been used in the film construction from a polydimethylsiloxane film crosslinked with a metal alkoxide as a siloxane oligomer, thereby eliminating adverse effects on the circuit and polydimethylsiloxane. It was found that the chain of the film can be shortened and the heat resistance of the film is improved.

  Based on the knowledge described above, the present inventor realizes a film thickness of 3 to 10 μm of polydimethylsiloxane crosslinked with metal alkoxide on stainless steel, and removes polydimethylsiloxane that has not been used in the coating composition from the coating. In particular, the present inventors have found a coated stainless steel foil excellent in heat resistance at 300 ° C. to 600 ° C. and a method for producing the same.

In the present invention, “heat resistance” means that a siloxane oligomer is not generated at 300 ° C. to 600 ° C. Thus, in confirming that a siloxane oligomer is not generated at 300 ° C. to 600 ° C., it is a standard that “thermogravimetric change is 5% or less” at 300 to 600 ° C. in an inert atmosphere of Ar, N ₂ or the like. It is said.

Further, the present inventors have not only polydimethylsiloxane but also siloxane polymers such as polydiphenylsiloxane, which have OH groups at both ends when dissolved in water or the like. It has been found that those having a 3 × 10 ^{2 to} 3 × 10 ⁴ Mw (desirably a molecular weight of 8 × 10 ² to 1 × 10 ⁴ Mw) have similar properties. Hereinafter, in this specification, a siloxane polymer having a molecular weight of 3 × 10 ^{2 to} 3 × 10 ⁴ Mw (preferably 8 × 10 ² to 1 × 10 ⁴ Mw) is referred to as a “siloxane polymer”. I will do it. The molecular weight distribution is measured by gel permeation chromatography (GPC) using a differential refractometer using an Alliance HPLC system manufactured by Japan Waters, and the molecular weight in terms of styrene is calculated.

  In the present invention, the reason that the siloxane polymer is limited to those having OH groups at both ends when dissolved in water or the like is to cause the siloxane polymer to undergo a condensation reaction with the hydroxy group of the metal alkoxide. (That is, when the OH group is not dissolved at both ends when dissolved in water or the like, the condensation reaction of the siloxane polymer does not occur).

Further, the present inventors have described that the metal M of the metal alkoxide is Mg, Ca, Y, Al, Si, Sn, Ti, Zr, Nb, Ta, W, etc., and the alkoxy group OR is a methoxy group, an ethoxy group. , Propoxy groups and the like can be used. In addition, it has been discovered that when the metal is Si, Si (OR) ₃ R ′ in which one of the alkoxy groups is substituted with an organic group R ′ can be used in place of the metal alkoxide.

In addition, it has been discovered that when the metal is Si, Si (OR) ₃ R ′ in which one of the alkoxy groups is substituted with an organic group R ′ can be used in place of the metal alkoxide.

  Since metal alkoxide has high reactivity, it is necessary to add ethyl 3-oxobutanoate as a chemical modifier. This is because the reaction does not proceed uniformly unless 3-oxosanbutanesanethyl is added, and the coating solution cannot be synthesized.

The first aspect of the present invention has a siloxane polymer film cross-linked with a metal alkoxide M (OR) n on a 20 to 200 μm thick stainless steel foil, and has a film thickness of 3 to 10 μm, and has a heat resistance of 300 ° C. to 600 ° C. And a coated stainless steel foil characterized by having a resistance of 1 × 10 ⁹ Ωcm ² or more.

  A second aspect of the present invention is a coated stainless steel foil, wherein the siloxane polymer described in the first aspect of the present invention is polydimethylsiloxane.

  A third aspect of the present invention is a coated stainless steel foil, wherein the siloxane polymer described in the first aspect of the present invention is polydiphenylsiloxane.

The fourth aspect of the present invention is a metal selected from Mg, Ca, Y, Al, Si, Sn, Ti, Zr, Nb, Ta, and W, a methoxy group, an ethoxy group, a propoxy group, and a butoxy group. M is the number of moles of a metal alkoxide composed of four groups selected by allowing duplication from among alkoxy groups such as S, and the number of moles of a siloxane polymer having a molecular weight of 3 × 10 ^{2 to} 3 × 10 ⁴ Mw, S The number of moles of water is W, the number of moles of chemical modifier (R ¹ , R ² represents an alkyl group) of β-diketone (R ¹ COCH ₂ COR ² ) to β-ketoester (R ¹ COCH ₂ COOR ² ) Is X, and / represents division,
S / M = 0.05 to 1.5 (Formula 1)
W / (S + M) = 0.1 to 10.0 (Formula 2)
X / M = 1.5 to 2.5 (Formula 3)
The coating solution produced by mixing so as to satisfy the following “A process” and “process”:
(1) After process A is performed, process B is performed one or more times; or
(2) A process for producing a coated stainless steel foil, wherein the B process is performed at least once without performing the A process;
“A Process”:
After being applied to a 20-200 μm thick stainless steel foil, it was dried in the atmosphere at 200 ° C. for 20 minutes,
A process of performing a step of placing in an oxygen-existing atmosphere having a temperature of 260 ° C. to 340 ° C. (preferably 280 ° C. to 320 ° C.) for 0.5 to 2.5 hours;
“B Process”:
A process of performing a step of placing in an atmosphere containing at least one of argon and nitrogen having a temperature of 360 ° C. to 500 ° C. (preferably 380 ° C. to 450 ° C.) for 0.5 hour to 2.5 hours.

  A fifth aspect of the present invention is a method for producing a coated stainless steel foil, wherein the chemical modifier described in the fourth aspect of the present invention is ethyl 3-oxobutanoate.

  A sixth aspect of the present invention is a method for producing a coated stainless steel foil, wherein the siloxane polymer described in the fourth aspect of the present invention is polydimethylsiloxane.

    A seventh aspect of the present invention is a method for producing a coated stainless steel foil, wherein the siloxane polymer described in the fourth aspect of the present invention is polydiphenylsiloxane.

The “coated stainless steel foil” according to the first to third aspects of the present invention has a film thickness of 3 to 10 μm and does not generate siloxane oligomers harmful to the circuit when treated at a high temperature of 300 to 600 ° C. And a coated stainless steel foil having a resistance of 1 × 10 ⁹ Ωcm ² or more. Therefore, the manufactured stainless steel foil with a film has a remarkable effect that it can be suitably used for a cell of a solar battery. The insulation resistance of the film is obtained from the current value when a 1 mmφ Pt electrode is formed on the insulating film by ion sputtering and applied at a voltage of 10 to 100 V between the substrate and the Pt electrode.

The method for producing a coated stainless steel foil according to the fourth to seventh aspects of the present invention has a film thickness of 3 to 10 μm and generates siloxane oligomers that are harmful to the circuit when processed at a high temperature of 300 to 600 ° C. In addition, there is a remarkable effect that a coated stainless steel foil having a resistance of 1 × 10 ⁹ Ωcm ² or more can be produced.

It is a model perspective view which shows an example of the coated stainless steel foil according to the 1st Embodiment of this invention. It is a graph which shows an example of the temperature processing pattern along the 2nd Embodiment of this invention. It is a graph which shows an example of the temperature processing pattern along the 3rd Embodiment of this invention. It is a graph which shows an example of the temperature processing pattern along the 4th Embodiment of this invention. It is a graph which shows an example of the relationship between the process temperature in this invention, and the insulation resistance of a membrane | film | coat. It is a schematic diagram which shows an example of the relationship between the siloxane polymer and metal alkoxide in this invention. It is a schematic diagram which shows an example of the relationship between the polydimethylsiloxane and Ti alkoxide in this invention. It is a schematic diagram which shows an example of the (presumed) mechanism by which polydimethylsiloxane is bridge | crosslinked by the metal alkoxide in this invention. It is a schematic diagram which shows an example of the (presumed) reaction mechanism of the polydimethylsiloxane and metal alkoxide in this invention.

(First embodiment)
On the stainless steel foil having a thickness of 20 to 200 μm, desirably 50 to 100 μm, the film thickness of 3 to 10 μm is formed with a film of a siloxane polymer crosslinked with M—O— derived from metal alkoxide M (OR) _n. It is a stainless steel foil with a film that does not generate an oligomer of siloxane at 300 to 600 ° C. and has a resistance of 1 × 10 ⁹ Ωcm ² or more.

  As specific examples of the siloxane polymer, polydimethylsiloxane and polydiphenylsiloxane can be used.

  FIG. 1 is a schematic cross-sectional view specifically showing an example of the first embodiment.

(Second Embodiment)

In the second embodiment, one metal selected from Mg, Ca, Y, Al, Si, Sn, Ti, Zr, Nb, Ta, W and a methoxy group, an ethoxy group, a propoxy group, a butoxy group, etc. M is the number of moles of metal alkoxide composed of four groups selected to allow duplication from among the alkoxy groups of S, S is the number of moles of siloxane polymer having a molecular weight of 3 × 10 ^{2 to} 3 × 10 ⁴ Mw. The number of moles of is represented by W, the number of moles of the chemical modifier is represented by X, and / means division.

In the second embodiment, the first treatment is preferably a metal alkoxide at 20 to 25 ° C., a siloxane polymer having a molecular weight of 3 × 10 ^{2 to} 3 × 10 ⁴ Mw, water, and a chemical modifier. Are mixed so as to satisfy the following (formula 1) to (formula 3) to prepare a coating solution.
S / M = 0.05 to 1.5 (Formula 1)
W / (S + M) = 0.1 to 10.0 (Formula 2)
X / M = 1.5 to 2.5 (Formula 3)

  Thereafter, the coating solution is applied on a stainless foil having a thickness of 20 to 200 μm (hereinafter referred to as “stained stainless steel foil after coating”) for 20 minutes in an atmosphere of 200 ° C. To dry the coating solution. Then, it is cooled to about 20 ° C.

  By the first treatment, water that is essential for the hydrolysis reaction of the siloxane polymer and the metal alkoxide to have OH groups and the alcohol generated by the hydrolysis are removed after coating.

In (Equation 1), S / M = 0.05 to 1.5 is slightly difficult to achieve a film thickness of 2 μm or more if it is less than 0.05, and film thickness is more than 1.5. This is because tends to be non-uniform.

In (Formula 2), W / (S + M) is set to 0.1 to 10.0. If it is less than 0.1, hydrolysis may occur sufficiently. This is because the siloxane polymer is not sufficiently crosslinked due to the above, and if it exceeds 10.0, the film thickness tends to be difficult to maintain.

The reason why X / M = 1.5 to 2.5 in (Formula 3) is that the metal alkoxide has high reactivity, and therefore β-diketone (R ¹ COCH ₂ COR ² ) or β-keto ester (R ¹ For example, ethyl 3-oxobutanoate is preferably added as a chemical modifier for COCH ₂ COOR ² ) (R ¹ and R ² represent an alkyl group). This is because if X / M is less than 1.5 or more than 2.5, the reactivity of the metal alkoxide may not be sufficiently modified.

  The range of X / M is desirably 1.8 to 2.2, and more desirably 1.9 to 2.1.

  As a 2nd process, Preferably, the stainless steel foil after the coating process obtained by the 1st process is set | placed in the inert atmosphere which consists of at least 1 or more among argon or nitrogen, The said atmosphere is 1-5 degrees C / min. When the temperature reaches a temperature within the range of 360 ° C. to 500 ° C. (preferably 380 ° C. to 450 ° C.), the heating is stopped and the range of 360 ° C. to 500 ° C. (preferably 380 ° C. to 450 ° C.) is reached. After maintaining a constant temperature for 0.5 to 2.5 hours, the atmosphere is lowered from a temperature of 360 ° C. to 500 ° C. (preferably 380 ° C. to 450 ° C.) at a rate of 1 to 5 ° C./min. Let it be at room temperature.

  At a temperature in the range of 360 ° C. to 500 ° C. (preferably 380 ° C. to 450 ° C.), a siloxane polymer film cross-linked with a metal alkoxide is formed, and a siloxane polymer that has not been used in the film structure decomposes to form a siloxane It is presumed that the reaction of volatilizing the oligomers in the atmosphere and the cross-linking of polydimethylsiloxane chains in the film occur in parallel.

(Upper and lower temperature limits)
The upper and lower limits of temperature in the first and second embodiments of the present invention will be described.

  First, the lower limit of temperature will be described.

  If the temperature is less than 360 ° C., the decomposition reaction of the siloxane polymer that was not used in the coating composition does not occur. Therefore, when the temperature of the stainless steel foil with the coating is later raised to 300 ° C. to 600 ° C., it is not used in the coating composition. Since the siloxane polymer is decomposed and the siloxane oligomer volatilizes in the atmosphere and may adversely affect the circuit and the like, the heat resistance of 300 ° C. to 600 ° C. may not be satisfied.

  In consideration of this, the lower limit of the temperature, preferably 360 ° C., promotes the decomposition reaction of siloxane. The lower limit is preferably 380 ° C., considering that the decomposition reaction of siloxane that has not been used for the film formation sufficiently occurs.

  Next, the upper limit value of the temperature will be described.

As shown in the graph of FIG. 5, when the temperature is 500 ° C. or higher, the resistance value does not reach 1 × 10 ⁹ Ωcm ² and the coated stainless steel foil may not be suitable for use. ° C.

  However, if an allowance is considered, 450 degreeC is a desirable upper limit.

  As a specific graph, FIG. 2 specifically shows an example of the transition of the temperature of the second process of the second embodiment.

  As the second treatment, preferably, the stainless steel foil after the coating treatment obtained in the first treatment is placed in an atmosphere containing oxygen at 20 ° C., and the atmosphere is increased at a rate of 3 ° C./min for 2.0 hours. When the temperature reaches 0 ° C., the heating is stopped and the temperature is maintained at 380 ° C. for 0.5 hours, and then the atmosphere is lowered from the temperature of 380 ° C. at a rate of 3 ° C./min for 2.0 hours to 20 ° C.

(Third embodiment)

In the third embodiment, one metal selected from Mg, Ca, Y, Al, Si, Sn, Ti, Zr, Nb, Ta, W and a methoxy group, an ethoxy group, a propoxy group, a butoxy group, etc. M is the number of moles of metal alkoxide composed of four groups selected to allow duplication from among the alkoxy groups of S, S is the number of moles of siloxane polymer having a molecular weight of 3 × 10 ^{2 to} 3 × 10 ⁴ Mw. Is represented by W, and the number of moles of the chemical modifier is represented by X, and the symbol “/” means division.

As the first treatment, preferably, a metal alkoxide, a siloxane polymer having a molecular weight of 3 × 10 ^{2 to} 3 × 10 ⁴ Mw at 20 ° C. to 25 ° C., water, and a chemical modifier are represented by the following (formula 1) to (formula A coating solution is synthesized by mixing so as to satisfy 3).
S / M = 0.05-1.5 ...
W / (S + M) = 0.1 to 10.0 (Formula 2)
X / M = 1.5 to 2.5 (Formula 3)

  Thereafter, the coating solution is applied on a stainless foil having a thickness of 20 to 200 μm (hereinafter referred to as “stained stainless steel foil after coating”) for 20 minutes in an atmosphere of 200 ° C. To dry the coating solution. Then, it is cooled to about 20 ° C.

  By the first treatment, the water required for the hydrolysis of the siloxane polymer and the metal alkoxide to have OH groups and the alcohol generated by the hydrolysis are removed after coating.

  In (Equation 1), S / M = 0.05 to 1.5 is that if it is less than 0.05, a film thickness of 2 μm or more may not be realized. This is because it may be uniform.

  In (Formula 2), W / (S + M) is set to 0.1 to 10.0. If it is less than 0.1, there is a possibility that hydrolysis does not occur sufficiently, and M—O— derived from metal alkoxide. This is because the siloxane polymer may not be sufficiently crosslinked due to the above, and if it exceeds 10.0, the film thickness tends to be difficult to maintain.

The reason why X / M = 1.5 to 2.5 in (Formula 3) is that the metal alkoxide has high reactivity, and therefore β-diketone (R ¹ COCH ₂ COR ² ) or β-keto ester (R ¹ For example, ethyl 3-oxobutanoate is preferably added as a chemical modifier for COCH ₂ COOR ² ) (R ¹ and R ² represent an alkyl group). This is because when “X / M” is less than 1.5, the chemical modification of the metal alkoxide may not be sufficient, and when it exceeds 2.5, there is a possibility that the film cannot be produced uniformly. The range of X / M is desirably 1.8 to 2.2, and more desirably 1.9 to 2.1.

  As a 2nd process, Preferably, the stainless steel foil after the application | coating process obtained by the 1st process is set | placed in oxygen presence atmosphere, the said atmosphere is raised at a speed | rate of 1-5 degree-C / min, 260 degreeC-340 degreeC ( Desirably, when the temperature reaches within the range of 280 ° C. to 320 ° C., the heating is stopped and a constant temperature in the range of 260 ° C. to 340 ° C. (desirably 280 ° C. to 320 ° C.) is maintained for about 50 minutes to 70 minutes. After that, the atmosphere is lowered from a temperature of 260 ° C. to 340 ° C. at a rate of 1 to 5 ° C./minute to obtain a normal temperature.

  This is to cause a reaction in which the siloxane polymer is cross-linked by M—O— derived from a metal alkoxide at a temperature within a range of 260 ° C. to 340 ° C. (desirably, 280 ° C. to 320 ° C.).

(Temperature upper and lower limits)
The upper and lower limit values of the temperature in the oxygen atmosphere in the third embodiment of the present invention will be described.

  First, the lower limit value of temperature will be described.

  Since the siloxane polymer is not sufficiently crosslinked by M—O— derived from metal alkoxide when the temperature is less than 260 ° C., the lower limit is set to 260 ° C. If a margin is considered, 280 ° C. is a desirable lower limit value.

  Next, the upper limit value of the temperature will be described.

  When the oxygen atmosphere is higher than 340 ° C., the film is hardened due to cross-linking of polydimethylsiloxane chains in the film, which may cause cracks in the film. Therefore, 340 ° C. was set as the upper limit. If an allowance is considered, desirably, the upper limit is 320 ° C.

  As the third treatment, preferably, the coated stainless steel foil obtained in the second treatment is placed in an inert atmosphere containing at least one of argon and nitrogen, and the atmosphere is increased at a rate of 1 to 5 ° C./min. The temperature is maintained for 20 to 40 minutes after reaching a temperature within the range of 360 ° C. to 500 ° C. (preferably 380 ° C. to 450 ° C.), and within the range of 360 ° C. to 500 ° C. (preferably 380 ° C. to 450 ° C.). The atmosphere is lowered from the temperature of 1 at a rate of 1 to 5 ° C./second to obtain room temperature.

  The upper and lower limits of the temperature of the inert atmosphere will be described.

  First, the lower limit value will be described.

  At a temperature in the range of 360 ° C. to 500 ° C. (preferably 380 ° C. to 450 ° C.), the siloxane polymer that has not been used for the film formation is decomposed and the siloxane oligomer volatilizes in the atmosphere. If the temperature is less than 360 ° C., decomposition of the siloxane polymer that was not used in the film structure is insufficient, so when the temperature is raised later, polydimethylsiloxane that was not used in the film structure is decomposed and siloxane oligomers are formed. Volatilizes in the atmosphere and adversely affects circuits.

  If a margin is considered, 380 ° C. is desirably the lower limit temperature.

  Next, the upper limit value will be described.

  However, considering the temperature at which decomposition of the siloxane polymer that was not used in the coating composition can occur properly, 500 ° C. is appropriate, and 450 ° C. is desirable if there is a margin. Therefore, the upper limit is 500 ° C., desirably 450 ° C.

  FIG. 3 shows a graph specifically illustrating an example of the transition of the temperature of the second process and the third process of the third embodiment.

  As the second treatment, preferably, the stainless steel foil after the coating treatment obtained in the first treatment is placed in an oxygen-existing atmosphere at 20 ° C., and the atmosphere is increased at a rate of 3 ° C./min for 1.5 hours. When the temperature reaches 0 ° C., the heating is stopped and the temperature is kept at 290 ° C. for 60 minutes, and then the atmosphere is lowered from the temperature of 290 ° C. at a rate of 3 ° C./minute for 1.5 hours to 20 ° C.

As the third treatment, preferably, the stainless steel foil after the coating treatment obtained in the second treatment is placed in an inert atmosphere of 20 ° C. containing at least one of Ar or N ₂ , and the atmosphere is set at a rate of 3 ° C./min. The temperature is increased for 2 hours, and after reaching 380 ° C., the temperature is maintained for 30 minutes, and the temperature is decreased from 380 ° C. at a rate of 3 ° C./second for 2 hours to 20 ° C.

  According to the knowledge of the present inventors, the method of the third embodiment can make the film thickest.

This is because in the third embodiment, after being processed in an oxygen-existing atmosphere, the processing is performed in an inert atmosphere containing at least one of Ar and N ₂ .

(Fourth embodiment)

In the fourth embodiment, one metal selected from Mg, Ca, Y, Al, Si, Sn, Ti, Zr, Nb, Ta, W and a methoxy group, an ethoxy group, a propoxy group, a butoxy group, etc. M is the number of moles of metal alkoxide composed of four groups selected to allow duplication from among the alkoxy groups of S, S is the number of moles of siloxane polymer having a molecular weight of 3 × 10 ^{2 to} 3 × 10 ⁴ Mw. Is represented by W, and the number of moles of the chemical modifier is represented by X, and the symbol “/” means division.

As the first treatment, preferably, a metal alkoxide, a siloxane polymer having a molecular weight of 3 × 10 ^{2 to} 3 × 10 ⁴ Mw at 20 ° C. to 25 ° C., water, and a chemical modifier are represented by the following (formula 1) to ( A coating solution is prepared by mixing so as to satisfy Equation (3).
S / M = 0.05 to 1.5 (Formula 1)
W / (S + M) = 0.1 to 10.0 (Formula 2)
X / M = 1.5 to 2.5 (Formula 3)

  Thereafter, the coating solution is applied on a stainless foil having a thickness of 20 to 200 μm (hereinafter referred to as “stained stainless steel foil after coating”) for 20 minutes in an atmosphere of 200 ° C. To dry the coating solution. Then, it is cooled to about 20 ° C.

  By the first treatment, the water required for causing the siloxane polymer and the metal alkoxide to undergo a hydrolysis reaction to have OH groups and the alcohol produced by the hydrolysis are removed after coating.

In (Equation 1), S / M = 0.05 to 1.5 is that if it is less than 0.05, a film thickness of 2 μm or more may not be realized. This is because it may be uniform.

In (Formula 2), W / (S + M) is set to 0.1 to 10.0. If it is less than 0.1, there is a possibility that hydrolysis does not occur sufficiently, and M—O— derived from metal alkoxide. This is because the siloxane polymer may not be sufficiently crosslinked due to the above, and if it exceeds 10.0, the film thickness tends to be difficult to maintain.

The reason why X / M = 1.5 to 2.5 in (Formula 3) is that the metal alkoxide has high reactivity, and therefore β-diketone (R ¹ COCH ₂ COR ² ) or β-keto ester (R ¹ For example, ethyl 3-oxobutanoate is preferably added as a chemical modifier for COCH ₂ COOR ² ) (R ¹ and R ² represent an alkyl group). This is because when “X / M” is less than 1.5 or more than 2.5, the reactivity of the metal alkoxide tends to be insufficiently modified.

  The range of X / M is desirably 1.8 to 2.2, and more desirably 1.9 to 2.1.

  As the second treatment, preferably, the coated stainless steel foil obtained in the first treatment is placed in an inert atmosphere composed of at least one of argon and nitrogen, and the atmosphere is increased at a rate of 1 to 5 ° C./second. When the temperature reaches a temperature within the range of 260 ° C. to 360 ° C. (desirably 280 ° C. to 340 ° C.), the heating is stopped and the temperature is maintained for 50 to 70 minutes.

  At a temperature in the range of 260 ° C. to 360 ° C. (desirably 280 ° C. to 340 ° C.), a reaction occurs in which polydimethylsiloxane is crosslinked with M—O— derived from metal alkoxide.

  As the third treatment, preferably, the atmosphere is raised from a temperature of 260 ° C. to 320 ° C. (desirably 280 ° C. to 300 ° C.) at a rate of 1 to 5 ° C./second, and a temperature within a range of 360 ° C. to 500 ° C. The temperature is kept for 20 to 40 minutes after reaching the temperature.

  At a temperature in the range of 360 ° C. to 500 ° C. (desirably, 380 ° C. to 450 ° C.), polydimethylsiloxane that has not been used in the coating composition decomposes and dimethylsiloxane oligomers volatilize in the atmosphere. If the temperature is less than 380 ° C., polydimethylsiloxane that was not used in the coating composition may not be sufficiently decomposed. This is because the oligomer of dimethylsiloxane tends to volatilize in the atmosphere and adversely affect the circuit and the like.

Further, at a temperature in the range of 360 ° C. to 500 ° C. (desirably, 380 ° C. to 450 ° C.), the reaction in which polydimethylsiloxane is crosslinked with a metal alkoxide is also performed in an inert atmosphere containing at least one of Ar and N _2. It happens in parallel.

  As the fourth treatment, the ambient temperature is preferably lowered from a temperature within the range of 360 ° C. to 500 ° C. (desirably 380 ° C. to 450 ° C.) at a rate of 1 to 5 ° C./second.

  FIG. 4 is a graph showing an example in which the temperature transition of the second process to the fourth process of the second embodiment is specifically depicted.

As the second treatment, preferably, the stainless steel foil after the coating treatment obtained in the first treatment is placed in an inert atmosphere of 20 ° C. containing at least one of Ar or N ₂ , and the atmosphere is set at a rate of 3 ° C./min. The temperature is raised for 1.5 hours, and when the temperature reaches 290 ° C., the heating is stopped and the temperature is kept at 290 ° C. for 60 minutes.

  As the third treatment, preferably, the atmosphere is further increased at a rate of 3 ° C./min for 0.5 hours, and after reaching 380 ° C., the temperature is maintained for 30 minutes.

  As the fourth treatment, the atmosphere is preferably lowered to 20 ° C. from a temperature of 380 ° C. for 2 hours at a rate of 3 ° C./second.

  Examples in which a film is applied to the stainless steel foil according to the second embodiment are shown in Table 1 described later.

  In the second embodiment, one metal selected from Mg, Ca, Y, Al, Si, Sn, Ti, Zr, Nb, Ta, and W, and a toxi group, an ethoxy group, a propoxy group, a butoxy group, etc. As a metal alkoxide composed of four groups selected by allowing duplication from the alkoxy group, Ti tetraisopropoxide, which is a Ti alkoxide composed of four alkoxy groups, is used with Ti as a metal.

As the siloxane polymer, polydimethylsiloxane having a molecular weight of 3 × 10 ^{2 to} 3 × 10 ⁴ Mw is used.

The number of moles of titanium tetraisopropoxide is M, the number of moles of polydimethylsiloxane having a molecular weight of 3 × 10 ^{2 to} 3 × 10 ⁴ Mw is S, the number of moles of water is W, the number of moles of ethyl 3-oxobutanoate is It is indicated by X, and the symbol “/” means division.

As a first treatment, titanium tetraisopropoxide at 20 ° C., polydimethylsiloxane having a molecular weight of 3 × 10 ^{2 to} 3 × 10 ⁴ Mw, water, and ethyl 3-oxobutanoate are represented by the following (formula 4) to (formula A coating solution prepared by mixing so as to satisfy 6) is applied onto a stainless steel foil having a thickness of 100 μm (hereinafter referred to as “stainless steel foil after coating treatment”) in the atmosphere at 200 ° C. For 20 minutes to dry the coating solution. Then, it is cooled to about 20 ° C.

S / M = 1.0 (Formula 4)
W / (S + M) = 5.0 (Formula 5)
X / M = 2.0 (Formula 6)

  As the second treatment, the stainless steel foil after the coating treatment obtained in the first treatment is placed in an inert atmosphere composed of at least one of argon and nitrogen, and the atmosphere is increased at a rate of 3 ° C./min. After reaching a temperature in the range of 360 ° C. to 500 ° C., heating is stopped and a constant temperature in the range of 360 ° C. to 500 ° C. is maintained for 0.5 hour, and then the atmosphere is changed from a temperature of 360 ° C. to 500 ° C. to 3 ° C. Decrease at a speed of / min.

As for the comparative example, the case where only the temperature is 340 ° C. and 510 ° C. is examined.

The meanings of the symbols “◯” and “x” in the notation of the heat test result are as follows.
Regarding the heat resistance of the film, the powder recovered by peeling off the film from the substrate was TG-DTA (Rigaku Electric Co., Thermo plus TG8120) and heated at a rate of 10 ° C./min up to 600 ° C. in an N ₂ atmosphere. Evaluation is based on weight change when heated.

○: No cracking occurred at 300 to 600 ° C., and the thermogravimetric change at 300 to 600 ° C. in an inert atmosphere of Ar, N ₂ or the like is 5% or less.
×: 300 to 600 or cracks in ° C. occurs, Ar, thermogravimetric change in 300 to 600 ° C. in an inert atmosphere such as _{N 2} is 5% or less.

  The meanings of the symbols “◯” and “x” in the notation of the resistance value test are as follows.

○: 1 × 10 ⁹ Ωcm ² or more.
×: Less than 1 × 10 ⁹ Ωcm ² .

  Table 2 shows examples in which a stainless steel foil is applied to the film according to the third embodiment.

  In the third embodiment, one metal selected from Mg, Ca, Y, Al, Si, Sn, Ti, Zr, Nb, Ta, and W, and a toxi group, an ethoxy group, a propoxy group, a butoxy group, etc. As a metal alkoxide composed of four groups selected by allowing duplication from the alkoxy group, Ti tetraisopropoxide, which is a Ti alkoxide composed of four alkoxy groups, is used with Ti as a metal.

As the siloxane polymer, polydimethylsiloxane having a molecular weight of 3 × 10 ^{2 to} 3 × 10 ⁴ Mw is used.

The number of moles of titanium tetraisopropoxide is M, the number of moles of polydimethylsiloxane having a molecular weight of 3 × 10 ^{2 to} 3 × 10 ⁴ Mw is S, the number of moles of water is W, the number of moles of ethyl 3-oxobutanoate is It is indicated by X, and the symbol “/” means division.

As the first treatment, preferably, titanium tetraisopropoxide at 20 ° C., polydimethylsiloxane having a molecular weight of 3 × 10 ^{2 to} 3 × 10 ⁴ Mw, water, and ethyl 3-oxobutanoate are represented by the following (formula 4): A coating solution prepared by mixing so as to satisfy (Equation 6) and coated on a stainless steel foil having a thickness of 100 μm (hereinafter referred to as “stainless steel foil after coating treatment”) is 200 ° C. The coating solution is dried by placing it in the atmosphere for 20 minutes. Then, it is cooled to about 20 ° C.

S / M = 1.0 (Formula 4)
W / (S + M) = 5.0 (Formula 5)
X / M = 2.0 (Formula 6)

  As a 2nd process, the stainless steel foil after the application | coating process obtained by the 1st process is set | placed in oxygen presence atmosphere, the said atmosphere is raised at a speed | rate of 1-5 degree-C / min, and it exists in the range of 260-340 degreeC When the temperature is reached, the heating is stopped and a constant temperature in the range of 260 ° C. to 340 ° C. is maintained for 0.5 hour, and then the atmosphere is lowered from the temperature of 260 ° C. to 340 ° C. at a rate of 3 ° C./min. Set to room temperature.

  About a comparative example, what considers only temperature as 320 degreeC and 330 degreeC.

As the third treatment, the stainless steel foil after the coating treatment obtained in the second treatment is placed in an inert atmosphere containing at least one of argon and nitrogen, and the atmosphere is increased at a rate of 3 ° C./min. After reaching the temperature within the range of 500 ° C., the temperature is maintained for 0.5 hours, and the atmosphere is lowered from the temperature within the range of 360 ° C. to 500 ° C. at a rate of 3 ° C./second to obtain room temperature.

  In Table 2, the criteria for the symbols “◯” and “x” in the notation of the heat test results are as follows.

◯: There is no occurrence of cracks at 300 to 600 ° C., and the thermogravimetric change at 300 to 600 ° C. in an inert atmosphere such as Ar or N ₂ is 5% or less.
×: 300 to 600 or cracks in ° C. occurs, Ar, thermogravimetric change in 300 to 600 ° C. in an inert atmosphere such as _{N 2} is 5% or more.

The criteria for the symbols “◯” and “x” in the notation of the resistance value test results in Table 2 are as follows.

○: 1 × 10 ⁹ Ωcm ² or more.
×: Less than 1 × 10 ⁹ Ωcm ² .

  As described in Examples 23 to 28, 31 to 36, 39 to 44, and 47 to 52, the coating applied to the stainless steel foil by the method of the present invention was a robust one having a thickness of 4 to 5 μm.

  When treated at 350 ° C. in an inert atmosphere as in Comparative Examples 22, 30, 38, and 46, the siloxane oligomer is not sufficiently detached, and when heated to 300 ° C. to 600 ° C. again, the siloxane Oligomer is generated.

As in Comparative Examples 29, 37, 45, and 52, when placed in an inert atmosphere at 510 ° C. exceeding 500 ° C., the resistance value becomes 1 × 10 ⁹ Ωcm ² or less.

  When the dry air temperature is as high as 350 ° C. as in the comparative example 54, the film is cracked at the stage of the second treatment.

  Table 3 shows the stainless steel foil coated with a film according to the fourth embodiment.

In the fourth embodiment, one metal selected from Mg, Ca, Y, Al, Si, Sn, Ti, Zr, Nb, Ta, W and a methoxy group, an ethoxy group, a propoxy group, a butoxy group, etc. M is the number of moles of metal alkoxide composed of four groups selected to allow duplication from among the alkoxy groups of S, S is the number of moles of siloxane polymer having a molecular weight of 3 × 10 ^{2 to} 3 × 10 ⁴ Mw. The number of moles is represented by W, and the symbol “/” means division.

As the first treatment, preferably, a metal alkoxide at 20 ° C. to 25 ° C., a siloxane polymer having a molecular weight of 3 × 10 ^{2 to} 3 × 10 ⁴ Mw, water, and ethyl 3-oxobutanoate are represented by the following (formula 4) to A liquid mixed so as to satisfy (Equation 6) applied on a stainless steel foil having a thickness of 100 μm (hereinafter referred to as “stainless steel foil after application treatment”) in an atmosphere of 200 ° C. for 20 minutes. The coating solution is dried by placing. Then, it is cooled to about 20 ° C.

S / M = 1.0 (Formula 4)
W / (S + M) = 5.0 (Formula 5)
X / M = 2.0 (Formula 6)

  As the second treatment, the stainless steel foil after the coating treatment obtained in the first treatment is placed in an inert atmosphere composed of at least one of argon and nitrogen, and the atmosphere is increased at a rate of 3 ° C./second. When the temperature reaches within the range of 320 ° C., the heating is stopped and the temperature is maintained for 50 to 70 minutes.

  As the third treatment, the atmosphere is increased from a temperature of 260 ° C. to 320 ° C. at a rate of 1 to 5 ° C./second, and after reaching a temperature in the range of 360 ° C. to 420 ° C., the temperature is maintained for 20 to 40 minutes.

  As the fourth treatment, the ambient temperature is decreased from a temperature in the range of 360 ° C. to 500 ° C. at a rate of 1 to 5 ° C./second.

  FIG. 4 is a graph showing an example in which the temperature transition of the second process to the fourth process of the second embodiment is specifically depicted.

As the second treatment, the coated stainless steel foil obtained in the first treatment is placed in an inert atmosphere at 20 ° C. containing at least one of Ar and N ₂ , and the atmosphere is 1.5 ° C./minute. The temperature is increased, and when the temperature reaches 290 ° C., the heating is stopped and the temperature is kept at 290 ° C. for 60 minutes.

  As the third treatment, the atmosphere is further increased at a rate of 3 ° C./min for 0.5 hours, and after reaching 380 ° C., the temperature is maintained for 30 minutes.

  As a fourth treatment, the atmosphere is lowered from a temperature of 380 ° C. at a rate of 3 ° C./second for 2 hours to 20 ° C.

  In Table 3, the criteria for the symbols “◯” and “x” in the notation of the heat test results are as follows.

○: No cracking occurred at 300 to 600 ° C., and the thermogravimetric change at 300 to 600 ° C. in an inert atmosphere of Ar, N ₂ or the like is 5% or less.
×: 300 to 600 or cracks in ° C. occurs, Ar, thermogravimetric change in 300 to 600 ° C. in an inert atmosphere such as _{N 2} is 5% or less.

  In Table 3, the criteria for the symbols “◯” and “x” in the notation of the resistance value test results are as follows.

○: 1 × 10 ⁹ Ωcm ² or more.
×: Less than 1 × 10 ⁹ Ωcm ² .

  As described in Examples 56 to 61, 64 to 69, 72 to 77, and 80 to 85, the coating applied to the stainless steel foil by the method of the present invention was a robust one having a thickness of 4 to 5 μm.

  When treated at 350 ° C. in an inert atmosphere as in Comparative Examples 55, 63, 71, and 79, the siloxane oligomer is not sufficiently detached, and when heated to 300 ° C. to 600 ° C. again, the siloxane Oligomer is generated.

As in Comparative Examples 62, 70, 78, and 86, when placed in an inert atmosphere at 510 ° C. exceeding 500 ° C., the resistance value is 1 × 10 ⁹ Ωcm ² or less.

1 coating 2 stainless steel foil

Claims (7)

A coated stainless steel foil comprising a stainless steel foil having a thickness of 20 to 200 μm and a siloxane polymer film having a thickness of 3 to 10 μm disposed on the stainless steel foil; and
The siloxane polymer film is composed of one metal selected from Mg, Ca, Y, Al, Si, Sn, Ti, Zr, Nb, Ta, W, methoxy group, ethoxy group, propoxy group, butoxy group, etc. A siloxane polymer film crosslinked with a metal alkoxide composed of four groups selected to allow duplication among the alkoxy groups of
A coated stainless steel foil characterized by having heat resistance of 300 ° C. to 600 ° C. and having a resistance of 1 × 10 ⁹ Ωcm ² or more.   A stainless steel foil with a coating, wherein the siloxane polymer is polydimethylsiloxane.   The coated stainless steel foil, wherein the siloxane polymer is polydiphenylsiloxane. Overlapping one metal selected from Mg, Ca, Y, Al, Si, Sn, Ti, Zr, Nb, Ta, W and alkoxy groups such as methoxy group, ethoxy group, propoxy group, butoxy group The number of moles of a metal alkoxide composed of four groups selected with permission is M, the number of moles of a siloxane polymer having a molecular weight of 3 × 10 ^{2 to} 3 × 10 ⁴ Mw is S, the number of moles of water is W, β- X represents the number of moles of a chemical modifier (R ¹ , R ² represents an alkyl group) of a diketone (R ¹ COCH ₂ COR ² ) or β-ketoester (R ¹ COCH ₂ COOR ² ), and / represents division. sometimes,
S / M = 0.05 to 1.5 (Formula 1)
W / (S + M) = 0.1 to 10.0 (Formula 2)
X / M = 1.5 to 2.5 (Formula 3)
The coating solution produced by mixing so as to satisfy the following “A process” and “process”:
(1) After process A is performed, process B is performed one or more times; or
(2) A process for producing a coated stainless steel foil, wherein the B process is performed at least once without performing the A process;
“A Process”:
After being applied to a stainless steel foil having a thickness of 20 to 200 μm, it is dried in an atmosphere of 200 ° C. for 20 minutes, and 0.5 hours to 260 ° C. to 340 ° C. (preferably 280 ° C. to 320 ° C.) The process of carrying out the step of placing for 2.5 hours;
“B Process”:
A process of performing a step of placing in an atmosphere containing at least one of argon and nitrogen having a temperature of 360 ° C. to 500 ° C. (preferably 380 ° C. to 450 ° C.) for 0.5 hour to 2.5 hours.   The method for producing a coated stainless steel foil according to claim 4, wherein the chemical modifier is ethyl 3-oxobutanoate.   The method for producing a coated stainless steel foil according to claim 4 or 5, wherein the siloxane polymer is polydimethylsiloxane.   The method for producing a coated stainless steel foil according to claim 4 or 5, wherein the siloxane polymer is polydiphenylsiloxane.

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