JP2021175564A - Method for producing resin sheet and method for producing film capacitor - Google Patents

Abstract

To provide a method for producing a resin sheet that can achieve both of high adhesion to a support and easy peeling from the support, and also has high processing yield.SOLUTION: A method for producing a resin sheet 4 has a coating step for applying a coating liquid 2 containing a resin composition and a solvent onto a support 1, and a drying step for drying the coating liquid 2 on the support 1 to form a resin layer 3. In the coating step, a contact angle of the coating liquid 2 to the support 1 by a sessile drop method is 50° or more and 80° or less.SELECTED DRAWING: Figure 1

Description

The present invention relates to a method for manufacturing a resin sheet and a method for manufacturing a film capacitor.

As an example of a method for producing a resin sheet, Patent Document 1 describes (A) a step of applying a resin varnish containing a resin composition and a solvent onto a support, and (B) drying the resin varnish to form a resin layer. Including the step of forming, in the step (A), the contact angle of the resin varnish with respect to the support by the droplet method is 0.1 ° to 20 °, and in the step (B), the thickness of the resin layer. A method for producing a resin sheet having a thickness of 5 μm or less is described.

Japanese Patent No. 6582807 (Japanese Unexamined Patent Publication No. 2017-60927)

In the method for producing a resin sheet described in Patent Document 1, since the contact angle of the coating liquid with respect to the support is 0.1 ° to 20 °, the wettability of the resin sheet with respect to the support is very good. On the other hand, there is a concern that the resin sheet is difficult to peel off from the support and the processing yield is lowered. In particular, depending on the type of resin constituting the resin sheet, if the contact angle of the coating liquid with the support is 0.1 ° to 20 °, it may not be possible to produce a resin sheet having a good processing yield.

An object of the present invention is to provide a method for producing a resin sheet, which has both adhesion to a support and peelability from the support and has a good processing yield. A further object of the present invention is to provide a method for manufacturing a film capacitor using the resin sheet as a dielectric resin film.

In the method for producing a resin sheet of the present invention, a resin layer is formed by a coating step of applying a coating liquid containing a resin composition and a solvent on a support and drying the coating liquid on the support. In the coating step, the contact angle of the coating liquid with respect to the support by the sessile drop method is 50 ° or more and 80 ° or less.

The film capacitor manufacturing method of the present invention comprises a coating step of applying a coating liquid containing a resin composition and a solvent onto a support, and drying the coating liquid on the support to obtain a dielectric resin film. A drying step of forming a metal layer and a metal layer forming step of forming a metal layer on at least one surface of the dielectric resin film are provided. The contact angle of is 50 ° or more and 80 ° or less.

According to the present invention, it is possible to provide a method for producing a resin sheet having both adhesion to a support and peelability from the support and a good processing yield.

FIG. 1 is a cross-sectional view schematically showing an example of a coating process. FIG. 2 is a cross-sectional view schematically showing an example of a drying process. FIG. 3 is a cross-sectional view schematically showing an example of the peeling step. FIG. 4 is a perspective view schematically showing an example of a film capacitor. FIG. 5 is a sectional view taken along line VV of the film capacitor shown in FIG. FIG. 6 is a perspective view schematically showing an example of a wound body of a metallized film constituting the film capacitors shown in FIGS. 4 and 5. FIG. 7 is a cross-sectional view schematically showing an example of the metal layer forming step.

Hereinafter, a method for producing a resin sheet and a method for producing a film capacitor of the present invention will be described.
However, the present invention is not limited to the following configurations, and can be appropriately modified and applied without changing the gist of the present invention.
A combination of two or more of the individual desirable configurations of the invention described below is also the invention.

[Manufacturing method of resin sheet]
The method for producing a resin sheet of the present invention includes a coating step of applying a coating liquid on a support and a drying step of forming a resin layer by drying the coating liquid on the support.

(Coating process)
FIG. 1 is a cross-sectional view schematically showing an example of a coating process.
In the coating process, as shown in FIG. 1, the coating liquid 2 is applied onto the support 1. The coating liquid 2 contains a resin composition and a solvent. The coating liquid 2 may be a resin solution in which the resin composition is dissolved in a solvent, or a resin dispersion liquid in which the resin composition is dispersed in the solvent. The thicknesses of the support 1 and the coating liquid 2 shown in FIG. 1 have been appropriately changed for the purpose of clarifying and simplifying the drawings, and do not represent the relationship between the actual thicknesses. The same applies to other drawings.

The method for producing a resin sheet of the present invention is characterized in that, in the coating process, the contact angle of the coating liquid with respect to the support by the sessile drop method is 50 ° or more and 80 ° or less.
By setting the contact angle to 50 ° or more, both the adhesion between the resin sheet and the support and the peelability of the resin sheet from the support can be achieved, and the processing yield can be improved.
Further, by setting the contact angle to 80 ° or less, repelling of the coating liquid can be suppressed, and the coating width and the film thickness can be satisfactorily controlled.

The contact angle of the coating liquid on the support by the sessile drop method can be measured using an automatic contact angle meter (DropMaster DMs-401 manufactured by Kyowa Interface Science Co., Ltd.).

The coating method of the coating liquid is not particularly limited, and a known coating method or printing method can be used. Spin coater, bar coater, doctor blade coater, air knife coater, roll coater, rotary coater, flow coater, die coater, lip coater, comma coater, play coat, flow coat, depending on the viscosity of the coating liquid and the desired film thickness. Dip coating, brush coating, screen printing, gravure printing and the like can be appropriately selected and used.

As the support, for example, a film made of resin can be used. Alternatively, a metal foil, a paper pattern, or the like may be used as the support.

When a film made of a resin is used as a support, examples of the resin constituting the film include polyolefins such as polyethylene (PE) and polypropylene (PP), and polyesters such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN). , Polypropylene (PC), acrylics such as polymethylmethacrylate (PMMA), cyclic polyolefins, triacetylcellulose (TAC), polyethersulfide (PES), polyetherketones, polyimides and the like. A release layer may be provided on the surface of the film used as these supports in order to improve the peelability of the coated product.

Examples of the metal foil used as the support include copper foil and aluminum foil. The metal constituting the metal foil may be an alloy.

The thickness of the support is not particularly limited, and is, for example, 5 μm or more and 75 μm or less.

The resin composition contained in the coating liquid is not particularly limited, and includes, for example, a first organic material having a plurality of hydroxyl groups (OH groups) and a second organic material having a plurality of isocyanate groups (NCO groups). With this composition, by setting the contact angle to 50 ° or more and 80 ° or less, a resin sheet having a good processing yield can be produced.

The first organic material is a polyol having a plurality of hydroxyl groups in the molecule. Examples of the polyol include polyether polyols, polyester polyols, polyvinyl acetals, and the like. As the first organic material, two or more kinds of organic materials may be used in combination.

The first organic material preferably has an epoxy group. In particular, the first organic material is preferably a phenoxy resin, and more preferably a high molecular weight bisphenol A type epoxy resin having an epoxy group at the terminal.

The second organic material is a polyisocyanate having a plurality of isocyanate groups in the molecule. The second organic material functions as a curing agent for curing the film by reacting with the hydroxyl groups of the first organic material to form a crosslinked structure.

Examples of the polyisocyanate include aromatic polyisocyanates such as diphenylmethane diisocyanate (MDI) and tolylene diisocyanate (TDI), and aliphatic polyisocyanates such as hexamethylene diisocyanate (HDI). A modified product of these polyisocyanates, for example, a modified product having carbodiimide, urethane, or the like may be used. Among them, aromatic polyisocyanate is preferable, MDI or TDI is more preferable, and MDI is further preferable. As the MDI, a typical polypeptide MDI or a monomer type MDI can be used. Further, MDI may be a mixture type. As the second organic material, two or more kinds of organic materials may be used in combination.

The weight ratio of the first organic material to the second organic material (first organic material / second organic material) is not particularly limited, but is preferably 10/90 or more, more preferably 20/80 or more, and 30/70 or more. More preferably, 90/10 or less is preferable, 80/20 or less is more preferable, and 70/30 or less is further preferable. In particular, the weight ratio of the first organic material to the second organic material (first organic material / second organic material) preferably exceeds 50/50.

The resin composition containing the first organic material and the second organic material may contain additives for adding other functions. For example, smoothness can be imparted by adding a leveling agent. More preferably, the additive is a material that has a functional group that reacts with a hydroxyl group and / or an isocyanate group and forms a part of the crosslinked structure of the cured product. Examples of such a material include a resin having at least one functional group selected from the group consisting of an epoxy group, a silanol group and a carboxyl group.

The solvent contained in the coating liquid is not particularly limited, and is not particularly limited, and cyclic ethers such as tetrahydrofuran, ketones such as acetone, methyl ethyl ketone (MEK) and cyclohexanone, ethyl acetate, butyl acetate, cellosolve acetate, propylene glycol monomethyl ether acetate and carbi. Acetate esters such as tall acetate, carbitols such as cellosolve and butyl carbitol, aromatic hydrocarbons such as toluene, xylene and ethylbenzene, amide solvents such as dimethylformamide, dimethylacetamide (DMAc) and N-methylpyrrolidone. And so on. These solvents may be used alone or in combination of two or more.

(Drying process)
FIG. 2 is a cross-sectional view schematically showing an example of a drying process.
In the drying step, the coating liquid 2 on the support 1 is dried. As a result, as shown in FIG. 2, the resin layer 3 is formed on the support 1.

The thickness of the resin layer is not particularly limited, and is, for example, 1 μm or more and 10 μm or less.

The method for drying the coating liquid is not particularly limited, and known drying methods such as heating and hot air blowing can be used. The drying conditions may be determined according to the boiling point of the solvent contained in the coating liquid and the like.

The drying treatment may be carried out only once or may be carried out a plurality of times. When the drying treatment is carried out a plurality of times, the drying conditions may be the same or different. For example, the second and subsequent drying treatments may be performed at a higher temperature than the first drying treatment.

(Peeling process)
FIG. 3 is a cross-sectional view schematically showing an example of the peeling step.
Depending on the use and purpose of the resin sheet, a peeling step of peeling the resin layer 3 from the support 1 is required after the drying step. As a result, as shown in FIG. 3, the resin sheet 4 is obtained.

The peeling step can be carried out, for example, after the drying step and then cooling to room temperature (20 ° C.) to about 50 ° C. At this time, in order to facilitate the peeling, the peeling agent may be applied in advance to the support before the coating liquid is applied.

The resin sheet obtained by the production method of the present invention can be used, for example, as a dielectric resin film for a film capacitor. The use of the resin sheet is not limited to the dielectric resin film of the film capacitor.

Hereinafter, as an embodiment of a film capacitor, a state in which a first dielectric resin film provided with a first metal layer and a second dielectric resin film provided with a second metal layer are laminated. A winding type film capacitor, which is wound in, will be described as an example.
The film capacitor is a laminated film in which a first dielectric resin film provided with a first metal layer and a second dielectric resin film provided with a second metal layer are laminated. It may be a capacitor or the like.

FIG. 4 is a perspective view schematically showing an example of a film capacitor. FIG. 5 is a sectional view taken along line VV of the film capacitor shown in FIG.
The film capacitor 10 shown in FIGS. 4 and 5 is a winding type film capacitor. The film capacitor 10 is formed by winding a metallized film winding body 40 in which a first metallized film 11 and a second metallized film 12 are laminated, and a metallized film winding body 40. It includes a first external terminal electrode 41 connected to one end and a second external terminal electrode 42 connected to the other end of the metallized film winding body 40. As shown in FIG. 5, the first metallized film 11 is a first metal layer (counter electrode) provided on one surface of a first dielectric resin film 13 and a first dielectric resin film 13. ) 15, and the second metallized film 12 is a second metal layer (counter electrode) provided on one surface of the second dielectric resin film 14 and the second dielectric resin film 14. It has 16.

As shown in FIG. 5, the first metal layer 15 and the second metal layer 16 face each other with the first dielectric resin film 13 or the second dielectric resin film 14 interposed therebetween. Further, the first metal layer 15 is electrically connected to the first external terminal electrode 41, and the second metal layer 16 is electrically connected to the second external terminal electrode 42.

The first dielectric resin film 13 and the second dielectric resin film 14 may have different configurations, but it is desirable that they have the same configuration.

The first metal layer 15 is formed so as to reach one side edge on one surface of the first dielectric resin film 13 but not to the other side edge. On the other hand, the second metal layer 16 is formed so as not to reach one side edge on one surface of the second dielectric resin film 14, but to reach the other side edge. The first metal layer 15 and the second metal layer 16 are composed of, for example, an aluminum layer.

FIG. 6 is a perspective view schematically showing an example of a wound body of a metallized film constituting the film capacitors shown in FIGS. 4 and 5.
As shown in FIGS. 5 and 6, the end of the first metal layer 15 on the side reaching the side edge of the first dielectric resin film 13 and the second end of the second metal layer 16 The width of the first dielectric resin film 13 and the width of the second dielectric resin film 14 are such that the end portions on the side reaching the side edge of the dielectric resin film 14 are exposed from the laminated film. The layers are stacked so as to be shifted in the direction (left-right direction in FIG. 5). The first dielectric resin film 13 and the second dielectric resin film 14 are wound in a laminated state to form a metallized film winding body 40, and the first metal layer 15 and the second metal are formed. The layers 16 are held in a state of being exposed at the ends and are in a stacked state.

In FIGS. 5 and 6, the second dielectric resin film 14 is located outside the first dielectric resin film 13, and the first dielectric resin film 13 and the second dielectric resin film 14 are formed. Each of the first metal layer 15 and the second metal layer 16 is wound so as to face inward.

The first external terminal electrode 41 and the second external terminal electrode 42 are formed by spraying, for example, zinc or the like onto each end face of the wound body 40 of the metallized film obtained as described above. .. The first external terminal electrode 41 comes into contact with the exposed end of the first metal layer 15 and is thereby electrically connected to the first metal layer 15. On the other hand, the second external terminal electrode 42 comes into contact with the exposed end of the second metal layer 16 and is thereby electrically connected to the second metal layer 16.

It is preferable that the wound body of the metallized film is pressed into a flat shape such as an ellipse or an oval, and has a more compact shape than when the cross-sectional shape is a perfect circle. The film capacitor may have a cylindrical winding shaft. The winding shaft is arranged on the central axis of the metallized film in the wound state, and serves as a winding shaft when the metallized film is wound.

Examples of the metal contained in the metal layer include aluminum (Al), titanium (Ti), zinc (Zn), magnesium (Mg), tin (Sn), nickel (Ni) and the like.

The thickness of the metal layer is not particularly limited, but is, for example, 5 nm or more and 40 nm or less.
The thickness of the metal layer is specified by observing a cross section of a dielectric resin film provided with the metal layer cut in the thickness direction using an electron microscope such as a field emission scanning electron microscope (FE-SEM). can do.

The dielectric resin film is made of, for example, a cured product of the first organic material and the second organic material described above. In this case, the dielectric resin film is made of a cured product obtained by reacting the hydroxyl group of the first organic material with the isocyanate group of the second organic material.

When a cured product is obtained by the above reaction, an uncured portion of the starting material may remain in the film. For example, the dielectric resin film may contain at least one of a hydroxyl group and an isocyanate group. In this case, the dielectric resin film may contain either a hydroxyl group or an isocyanate group, or may contain both a hydroxyl group and an isocyanate group.
The presence of hydroxyl groups and / or isocyanate groups can be confirmed using a Fourier transform infrared spectrophotometer (FT-IR).

[Manufacturing method of film capacitors]
The method for manufacturing a film capacitor of the present invention includes a coating step of applying a coating liquid on a support, a drying step of forming a dielectric resin film by drying the coating liquid on the support, and a dielectric material. It includes a metal layer forming step of forming a metal layer on at least one surface of the resin film.

(Coating process)
In the coating step, a coating liquid containing a resin composition and a solvent is applied onto the support in the same manner as in the method for producing a resin sheet of the present invention. The coating liquid is preferably a resin solution in which the resin composition is dissolved in a solvent.

For example, using a doctor blade coater, a resin solution containing the above-mentioned first organic material and second organic material is formed into a film on a support such as a PET film.

The method for manufacturing a film capacitor of the present invention is characterized in that, in the coating process, the contact angle of the coating liquid with respect to the support by the sessile drop method is 50 ° or more and 80 ° or less.
By setting the contact angle to 50 ° or more, both the adhesion between the dielectric resin film and the support and the peelability of the dielectric resin film from the support can be achieved, and the processing yield can be improved.
Further, by setting the contact angle to 80 ° or less, repelling of the coating liquid can be suppressed, and the coating width and the film thickness can be satisfactorily controlled.

(Drying process)
In the drying step, the coating liquid on the support is dried in the same manner as in the method for producing the resin sheet of the present invention. As a result, a dielectric resin film is formed on the support.

The thickness of the dielectric resin film is not particularly limited, and is, for example, 1 μm or more and 10 μm or less.

(Metal layer forming process)
In the metal layer forming step, a metal layer is formed on at least one surface of the dielectric resin film. The metal layer may be formed on only one surface of the dielectric resin film, or may be formed on both surfaces of the dielectric resin film. Examples of the method for forming the metal layer include a method such as thin film deposition.

FIG. 7 is a cross-sectional view schematically showing an example of the metal layer forming step.
For example, as shown in FIG. 7, a metal layer 5 is formed on one surface of the dielectric resin film 3 on the support 1. In this case, after forming the metal layer 5, the dielectric resin film 3 is peeled off from the support 1. Alternatively, the metal layer 5 may be formed on one surface of the dielectric resin film 3 after the dielectric resin film 3 is peeled off from the support 1.

Two metallized films having a metal layer formed on one surface of a dielectric resin film are stacked in a state of being shifted by a predetermined distance in the width direction, and then wound to form a wound body of the metallized film. can get. If necessary, the wound body of the metallized film may be sandwiched from a direction perpendicular to the width direction and pressed into an elliptical cylindrical shape. Subsequently, the film capacitor 10 shown in FIG. 4 is obtained by forming an external terminal electrode on each end surface of the wound body of the metallized film. Examples of the method of forming the external terminal electrode on the end face of the wound body of the metallized film include thermal spraying.

Hereinafter, an example in which the method for producing a resin sheet and the method for producing a film capacitor of the present invention are more specifically disclosed will be shown. The present invention is not limited to these examples.

A phenoxy resin having a plurality of hydroxyl groups was prepared as the first organic material, and MDI (diphenylmethane diisocyanate) was prepared as the second organic material.

As the phenoxy resin, a phenoxy resin which is a high molecular weight bisphenol A type epoxy resin having an epoxy group at the terminal was used.

As the above MDI, a typical polypeptide MDI or a monomer type MDI was used.

The first organic material and the second organic material were mixed at a weight ratio of 7: 3 and dissolved in methyl ethyl ketone (MEK) to obtain a resin solution as a coating liquid.

When preparing the resin solution, the resin concentration was changed as shown in Table 1. The resin concentration here means the solid content concentration (% by weight) which is the ratio of the total weight of the first organic material and the second organic material to the weight of the resin solution.

The obtained resin solution was uniformly molded on a PET film as a support using a doctor blade coater, and dried at 70 ° C. to 80 ° C. for 3 minutes to form a resin layer on the PET film. As a result, a resin sheet to be a dielectric resin film of the film capacitor was produced.

The contact angle of each resin solution with respect to the support by the sessile drop method was measured using an automatic contact angle meter (DropMaster DMs-401 manufactured by Kyowa Interface Science Co., Ltd.). The results are shown in Table 1.

Next, an aluminum vapor deposition electrode was formed on one main surface of the dielectric resin film, and then the resin sheet was peeled off from the PET film. A wound capacitor is formed by winding a first dielectric resin film having a vapor-deposited electrode formed on one main surface and a second dielectric resin film having a vapor-deposited electrode formed on one main surface. Made. Subsequently, heat treatment was performed at 150 ° C. for 2 hours. Film capacitors of Samples 1 to 10 were prepared by forming metallikons (external terminal electrodes) at both ends of the wound capacitor after the heat treatment, attaching lead wires, and covering with an exterior resin.

When any trouble occurs in the manufacturing process of the above-mentioned film capacitor, the case is described in [Manufacturing Yield] of Table 1. If there is no problem, it is stated that there is no problem.

In Sample 4 and Sample 8, a film capacitor was produced using a resin sheet formed on a PP (polypropylene) film instead of the PET film.

In Table 1, the resin sheet in which * is added to the sample number is a comparative example outside the scope of the present invention.

As shown in Table 1, in Sample 1 in which the contact angle of the resin solution with respect to the support is smaller than 50 °, there is a problem that the resin sheet cannot be peeled off from the PET film which is the support. On the other hand, in the sample 10 in which the contact angle of the resin solution with respect to the support is larger than 80 °, the resin solution is repelled, and there is a problem that the sheet cannot be formed (coated).

On the other hand, in Samples 2 to 9 in which the contact angle of the resin solution with respect to the support was 50 ° or more and 80 ° or less, these problems did not occur.

1 Support 2 Coating liquid 3 Resin layer (dielectric resin film)
4 Resin sheet 5 Metal layer 10 Film capacitor 11 First metallized film 12 Second metallized film 13 First dielectric resin film 14 Second dielectric resin film 15 First metal layer 16 Second metal Layer 40 Winder of metallized film 41 First external terminal electrode 42 Second external terminal electrode

Claims (7)

A coating process in which a coating liquid containing a resin composition and a solvent is applied onto a support, and
A drying step of forming a resin layer by drying the coating liquid on the support, and
With
A method for producing a resin sheet, wherein in the coating step, the contact angle of the coating liquid with respect to the support by the sessile drop method is 50 ° or more and 80 ° or less. The method for producing a resin sheet according to claim 1, wherein the support is a base film made of a resin. The method for producing a resin sheet according to claim 1 or 2, wherein the resin composition comprises a first organic material having a plurality of hydroxyl groups and a second organic material having a plurality of isocyanate groups. The method for producing a resin sheet according to any one of claims 1 to 3, wherein the resin sheet is a dielectric resin film of a film capacitor. A coating process in which a coating liquid containing a resin composition and a solvent is applied onto a support, and
A drying step of forming a dielectric resin film by drying the coating liquid on the support, and
A metal layer forming step of forming a metal layer on at least one surface of the dielectric resin film, and
With
A method for manufacturing a film capacitor, wherein in the coating step, the contact angle of the coating liquid with respect to the support by the sessile drop method is 50 ° or more and 80 ° or less. The method for manufacturing a film capacitor according to claim 5, wherein the support is a film made of a resin. The method for producing a film capacitor according to claim 5 or 6, wherein the resin composition comprises a first organic material having a plurality of hydroxyl groups and a second organic material having a plurality of isocyanate groups.

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