JPH08267001A - Method for manufacturing coating film - Google Patents

Abstract

PURPOSE: To provide a method for producing a coating film good in uniformity in thickness in the width direction, especially on the edge part, and particularly a releasable coating film uniform in thickness with the edge part of the coated face sharpened and without the width being decreased at the time of providing a releasable layer of silicone resin in stripes at regular intervals in the longitudinal direction. CONSTITUTION: A liq. coating agent is applied on a substrate film. In this case, the critical surface tension A (in dyne/cm) of the substrate film and the critical tension B of the liq. coating agent are limited to conform to 0<=|A-B|<=10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coating film having a highly accurate coating width accuracy by reducing shrinkage in the width direction of a coating film when a liquid coating material is applied. The present invention relates to a coating method which is a coating agent and provides a releasable coating film having a high coating width accuracy without shrinkage in the width direction of the coating film during coating.

[0002]

2. Description of the Related Art Most conventional coating films are prepared by applying a liquid coating agent to a base film such as unstretched, uniaxially stretched and biaxially stretched polyester film, polypropylene film, nylon film by a coating device. Is obtained by.

The liquid coating material includes color pigment coating material, primer, water-based emulsion coating material, solvent-based emulsion coating material, solvent-based resin coating material, water-based resin coating material, etc.
Solvent-based resin type coatings are still the mainstream, and after diluting pigments, resins, etc. to a certain concentration with an organic solvent such as toluene,
It is applied by a direct gravure coater, a micro gravure coater, a reverse gravure coater, a kiss coater, a comma coater, a die coater, a bar / rod type coating device, or the like.

Further, among the coating films, the peelable coating film is a separator for adhesive tape,
It is mainly used as a release film for ceramic sheet process, but especially as a process carrier film when manufacturing ceramic green sheets for laminated ceramic capacitors, it has excellent mechanical strength, dimensional stability, heat resistance, etc. A releasable coating film in which a heat- or ultraviolet-curable silicone resin is provided as a release layer on a biaxially stretched polyester film is generally used. Here, a solvent-based resin coating obtained by diluting a silicone-based resin with an organic solvent is mainly used as the liquid coating used in the production of the release coating film. As a method for producing a coating film coated with an agent, JP-B-53-6
Japanese Patent Laid-Open No. 998 and Japanese Patent Laid-Open No. 63-95285 are known.

The ceramic green sheet is made by adding a polymer binder such as PMMA, PVB or PVA, a plasticizer and a dispersant to an aqueous or organic solvent in which ceramic powder such as barium titanate or alumina is dispersed. Generally produced by mixing and dispersing with a high-speed mixer or ball mill, applying the resulting ceramic slurry on a releasable coating film by the doctor blade method to a thickness of several hundred μm to several tens of μm, and drying and winding it. Has been done.

In recent years, in order to realize a small-sized and high-capacity multilayer ceramic chip capacitor, it has been demanded that the thickness of one ceramic layer be made thinner.
It is necessary to release a very thin ceramic green sheet having a thickness of 0 μm or less from the releasable coating film with high precision and without defects. For this purpose, the uniformity of the thickness of the base film used for the release coating film, the thickness of the release layer, and the uniformity of the release force become important. However,
A polyester film generally used as a base material for the peelable coating film has a poor affinity with a solvent-based resin coating agent obtained by diluting a silicone-based resin or the like with an organic solvent, and is applied with a gravure coater, a reverse gravure coater, or the like. There is a drawback that cissing of the coating material occurs at the edge portion of the substrate film before reaching the post-drying zone, and the film thickness at the edge portion increases as compared with the central portion. In particular, when grooves are formed in the gravure roll and it is attempted to provide a release layer of silicone resin in a stripe shape in the longitudinal direction at regular intervals, the edges of the coating surface become uneven due to cissing at the edges of the coating surface and rise. In addition, there is a problem that the width of the coated surface shrinks and the stripe interval is not constant.

[0007]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned problems and provides a method for producing a coating film having good uniformity of coating thickness in the width direction, particularly in the edge portion, particularly in the longitudinal direction at regular intervals. Provided is a method for producing a releasable coating film for a ceramic green sheet, in which the edge portion of the coated surface is sharp when the release layer of the silicone-based resin is provided in a stripe shape without shrinkage and the coating thickness is uniform. The purpose is to

[0008]

The above-mentioned object of the present invention is to provide a critical surface tension A (unit: dyne / cm) of the substrate film and the liquid coating agent in the step of applying the liquid coating agent on the substrate film. It is achieved by a method for producing a coating film, characterized in that the relationship with the critical surface tension B (unit: dyne / cm) satisfies the following expression (1). 0 ≦ | AB | ≦ 10 (1) Examples of the substrate film of the present invention include synthetic polymer films (including sheets) such as polypropylene film, polyester film, and nylon film. Among them, polyethylene terephthalate, polyethylene-2,6-, which has excellent heat resistance and surface properties, etc.
Naphthalate and polyethylene-α, β-bis (2-chlorophenoxy) ethane-4,4′-dicarboxylate are preferable, and in particular, biaxially stretched polyethylene terephthalate and biaxially stretched polyethylene having excellent mechanical strength and dimensional stability. -2,6-naphthalate, biaxially oriented polyethylene-α, β-bis (2-chlorophenoxy) ethane-4,
4'-dicarboxylate is preferred.

Examples of the liquid coating agent of the present invention include acrylic resin coating agents, epoxy resin coating agents and urethane resin coating agents. Particularly, the liquid coating agent used for the release coating film is hexafluoride. Examples thereof include those obtained by dissolving a fluorine-based resin such as propylene resin, vinyl fluoride resin and vinylidene fluoride resin in an organic solvent, and those obtained by dissolving a silicone resin such as polyorganosiloxane having a siloxane bond in an organic solvent. Of these, for the releasable coating film, a silicone resin-based one having excellent release performance, price and stability is preferable.

As the above-mentioned organic solvent, generally, aromatic hydrocarbons such as benzene, toluene and xylene, aliphatic hydrocarbons such as cyclohexane, n-hexane and n-heptane, halogenated hydrocarbons such as perchloroethylene and acetic acid. Ethyl, methyl vinyl ketone and the like are shown. In this,
As the solvent for the silicone resin coating material, toluene or a mixed solvent of toluene and an aliphatic hydrocarbon is preferable.

The resin content of the liquid coating composition is 0.5 to
When the amount is 25% by weight, preferably 0.5 to 15% by weight, the effect of the present invention is more clearly exhibited.

In the present invention, it is necessary that the critical surface tension A (unit: dyne / cm) of the base film and the critical surface tension B (unit: dyne / cm) of the liquid coating material satisfy the following formula (1). is there. 0 ≤ | AB | ≤ 10 (1) Critical surface tension A of the base film (unit: dyne / c
m) and the critical surface tension B of the liquid coating agent (unit: dyne / c
When m) is out of the range of the above formula (1), the coating film thickness at the edge portion of the coating surface increases during coating, and the edge portion of the coating surface becomes uneven, resulting in width shrinkage, which is not preferable.

In particular, in order to make the release coating film have both the thickness uniformity of the release layer and good release characteristics, the critical surface tension B (unit: dyne / c) of the liquid coating material is required.
m), especially, the critical surface tension B (unit: dyne / cm) of the silicone resin liquid coating material preferably satisfies the following expression (2) at the same time. 29 ≤ B ≤ 40 (2) Further, in the production of a release coating film for a ceramic green sheet, the critical surface tension A (unit: dyne / cm) of the base film and the critical surface tension B of the silicone resin coating agent (Unit: dyne / cm) is the above (1)
When the formula and the formula (2) are satisfied at the same time, the peelability at the edge portion of the film when peeling the ceramic green sheet from the coating film becomes good, and the peeling surface side of the ceramic green sheet at such a portion becomes extremely smooth. Is desirable. In particular, when the silicone resin coating is applied in stripes on the base film using a reverse gravure coater, reverse gravure coater, micro gravure coater, etc., the width of the margin part where the silicone resin coating is not applied The accuracy is extremely good. In addition, a coating material for a ceramic green sheet is applied to the striped coating film applied in a stripe shape, dried, and then slit highly accurately on the boundary between the margin portion and the coating portion of the silicone resin coating material. The ceramic green sheet obtained by peeling the green sheet on the peeled surface has extremely good width width accuracy of the end portion, and is most suitable for a laminated ceramic chip capacitor.

In the present invention, a groove is formed in a gravure roll or the like, and a liquid coating agent, particularly silicone, is formed in a stripe shape in the longitudinal direction with a direct gravure coater, a reverse gravure coater, a kiss direct gravure coater, a reverse gravure coater, or the like. When the base resin coating is applied to the base film, a coating film having a sharp edge portion on the coated surface and no width shrinkage is obtained, which is preferable. In this case, coating with a kiss reverse gravure coater or a micro gravure coater is preferable in terms of improving the smoothness of the coated surface.

As such a silicone resin coating material,
It is desirable that the liquid coating composition contains 1 to 20% by weight, preferably 4 to 12% by weight, of a polyorganosiloxane having a structure represented by the following formula (3). The thickness of the coating film after drying is preferably in the range of 0.05 to 0.5 μm.

[0016]

Embedded image (In the formula, R1 is a methyl group, and R2 is a carbon group having 4 to 4 carbon atoms.
15 is an alkyl group or ester group, a ketone group, a hydroxyl group-containing alkyl group or aralkyl group having 2 to 15 carbon atoms, and Vi is a vinyl group. The drying and curing (heat curing, ultraviolet curing, etc.) of the coating film can be performed individually or simultaneously. When carried out at the same time, it is preferable to heat at a temperature range of 80 ° C. to 200 ° C., preferably 120 ° C. to 180 ° C. for 30 seconds or more, though it depends on the heat resistance (thermal dimensional stability) of the base film.

Further, in the process of applying the liquid coating material on the substrate film and drying it, an inert gas such as air, nitrogen or helium may be blown immediately after the liquid coating material is applied.

[0018]

EXAMPLES The present invention will be described based on examples. In addition,
The characteristics of the coating film were evaluated by the following methods.

1) Releasability A coating film and a polyester adhesive film (Nitto Denko's 31B tape: 50 mm width) are bonded together while being pressed by a 5 kg roller, and the 180 ° peel strength after leaving for 20 hours at 20 ° C. is Tensilon. To measure. Here, it can be said that the peeling force of 20 g or less is good.

2) Uniformity of coating thickness in the width direction The fluorescent x-ray intensity (kcps) of the coated surface was measured,
Assuming that the strength of 5 kcps corresponds to a coating thickness of 0.2 μm, the central portion and the edge portion of the coating film are 30 m.
It was cut into m × 30 mm square and measured. Here, if the difference in thickness between the central portion and the edge portion is 10% or less with respect to the thickness of the central portion, it can be said that the uniformity of the coating film thickness in the width direction is good.

3) Applicability of coating film edge portion The edge portion of the coating portion is visually observed, and when the meandering amount of the coating surface edge is less than 1 mm with respect to the moving average value between peaks, the meandering is indicated. When the amount was 1 mm or more and 2 mm or less, the value was Δ, and when the amount of meandering was more than 2 mm, the value was ×. If it is Δ or more, there is no problem in practical use.

4) Critical surface tension In the case of a substrate film, it was measured with a commercially available wetting tension test liquid based on JIS-K-6768. As the liquid coating material, the coating material was applied to a synthetic resin plate whose wetting tension was known, and the critical surface tension was determined from the degree of cissing.

5) Rub-off property Rub the coated surface with a rub and the coating film is easily dropped off x, rub strongly 5 to 6 times. Roughly rub off 5 to 6 times. The ones that did not drop at all were marked as ○. If it is Δ or more, there is no practical problem.

Example 1 A thermosetting silicone resin coating material A (resin content: 10% by weight) on one side of a biaxially stretched polyester film "Lumirror S27" / width 1300 mm manufactured by Toray Industries, Inc. having a thickness of 50 μm ) Is applied by a reverse kiss roll coater at a running speed of 30 m / min using a gravure roll (# 200, diagonal type) having a total width of 1300 mm in which grooves are provided in stripes so that the application width is 300 mm.
A peelable coating film A having four 00 mm stripes in the longitudinal direction was obtained. At this time, the critical surface tension of the biaxially stretched polyester film was 41 dyne / cm, and the critical surface tension of the liquid coating agent was 37 dyne / cm. The results are shown in Table 1, and all of the releasability, the uniformity of the coating film thickness in the width direction, the coating property of the coating film edge portion, and the rub-off property are good.

The film running distance to the entrance of the drying oven is about 4 m, and the total length of the drying oven is 15 m.
The heating temperature up to a distance of 5 m from the inlet was 80 ° C, and the heating temperature from around 5 m to the outlet was 120 ° C.

“Thermosetting Silicone Resin Coating A” BY24-400 manufactured by Toray Dow Corning Silicone Co., Ltd. 100 parts by weight SRX212CAT manufactured by Toray Dow Corning Silicone Co., Ltd. 1 part by weight Polyvinyl alcohol (average polymerization degree 600, saponification 88 mol%) 0.5 parts by weight Toluene 898.5 parts by weight Example 2 A coating film was obtained in the same manner as in Example 1 except that the running speed of the film was 60 m / min. The results are shown in Table 1, and the releasability, the uniformity of the coating film thickness in the width direction, and the coating property of the coating film edge portion are good.

Comparative Example 1 The following thermosetting silicone resin coating agent B (resin concentration: 1
A coating film was obtained in the same manner as in Example 1 except that the content was 0% by weight.

At this time, the critical surface tension of the biaxially stretched polyester film was 41 dyne / cm, and the critical surface tension of the liquid coating material was 22 dyne / cm. The results are shown in Table 1.
However, the uniformity of the coating thickness in the width direction and the coating property of the coating film edge portion are poor.

“Thermosetting Silicone Resin Coating B” Toray Dow Corning Silicone Co., Ltd. LTC750A 100 parts by weight Toray Dow Corning Silicone Co., Ltd. SRX212CAT 1 part by weight Toluene 899 parts by weight Comparative Example 2 A coating film was obtained by the same method as in Comparative Example 1 except that the coating film was 60 m / min. The results are shown in Table 1, but the uniformity of the thickness of the coating film in the width direction and the coating property of the coating film edge portion are poor.

[0030]

[Table 1]

[0031]

As described above, according to the method for producing a coating film of the present invention, a coating film having a good coating film thickness uniformity in the width direction, particularly in the edge portion, can be obtained. Since the edge of the coated surface of the releasable coating film provided with a release layer of silicone resin in a striped shape in the direction of the edge is extremely sharp, there is no width shrinkage, and the coating thickness is uniform, a ceramic green sheet for laminated ceramic capacitors can be used. 10μ when used as a release film for carrier
It is possible to provide a releasable coating film of a very thin ceramic green sheet having a thickness of m or less with a high degree of accuracy and having very few defects due to peeling failure at the film edge portion.

Claims (6)

[Claims] 1. A critical surface tension A (unit: dy) of a substrate film in a step of applying a liquid coating agent on the substrate film.
ne / cm) and the critical surface tension B (unit: dy) of the liquid coating material
ne / cm) is satisfied with the following expression (1): a method for producing a coating film. 0 ≤ | AB | ≤ 10 (1) 2. A substrate film comprising polyethylene terephthalate, polyethylene-2,6-naphthalate, polyethylene-α, β-bis (2-chlorophenoxy) ethane-
It is at least one selected from 4,4′-dicarboxylate and has a critical surface tension B (unit:
The method for producing a coating film according to claim 1, wherein dyne / cm) satisfies the following expression (2). 29 ≤ B ≤ 40 (2) 3. The method for producing a coating film according to claim 1, wherein the liquid coating material is a silicone resin coating material. 4. The method for producing a coating film according to claim 1, wherein the liquid coating material is applied in stripes in the running direction on the base film. 5. At least one substrate film selected from polyethylene terephthalate, polyethylene-2,6-naphthalate, polyethylene-α, β-bis (2-chlorophenoxy) ethane-4,4′-dicarboxylate. In the step of applying the silicone-based resin coating agent on the above, the critical surface tension A (unit: dyne /
cm) and the critical surface tension B (unit: dyne / cm) of the silicone resin coating material satisfy the above formulas (1) and (2) at the same time. Method. 6. The method for producing a peelable coating film for a ceramic green sheet according to claim 5, wherein the silicone-based resin coating material is applied in a stripe shape in the running direction.