KR20000059814A - Method for processing release film for aquaeous slurry coatings - Google Patents

Abstract

PURPOSE: A method for preparing the release film for water-based slurry is provided, to improve the adhesion between a release layer and water slurry and the size stability land to lower the delamination. CONSTITUTION: The method comprises the steps of mixing 100 parts by weight of a silicone resin, a curing agent, 2-20 parts by weight of colloidal silica, 0-20 parts by weight of a silane coupling agent for improving the dispersity of the silica and a solvent to prepare a silicone coating solution; coating a polyester film with a silane coupling agent or the mixture of a 100 parts by weight of silane coupling agent and 75 parts by weight of polyester copolymer or less, to form primer coating layer; coating the film with the silicone coating solution; and curing the film to obtain a release film.

Description

Method for manufacturing release film for aqueous slurry {METHOD FOR PROCESSING RELEASE FILM FOR AQUAEOUS SLURRY COATINGS}

The present invention relates to a method for producing a release film for aqueous slurry, and more particularly, to a method for producing a release film for aqueous slurry, which is used as a carrier film in a process requiring coating of a ceramic slurry when molding various ceramic products.

Ceramic products are used as very important parts in various electronic products such as capacitors, resistors, piezoelectric materials, magnetic materials, etc., and their usage is increasing with the development of the electric and electronic industries.

Among ceramic products, products such as multi-layer ceramic condenser (MLCC), ferrite beads, resistors, etc. are used to release the release film during molding of products due to the simplification of process and efficiency. It is manufactured by the supply used as a carrier film. Recently, as the demand for high-capacity and integrated parts is increased in accordance with the trend of lighter and smaller electronic products, the demand for MLCC is also increasing in capacitors. As a result, the demand for release films for carrier films is also increasing.

It is a trend to thin the ceramic sheet layer by realizing the miniaturization and high capacity of the laminated ceramic chip capacitor. For this purpose, it is necessary to coat the release film having excellent surface properties with defects and precision of the ceramic sheet when coating the thin film ceramic having a thickness of 20 μm or less.

The ceramic slurry is a polymer binder and a plasticizer such as polymethyl methacrylate (PMMA), polyvinyl acetal, polyvinyl butyral (PVB), polyvinyl alcohol, etc. in an organic solvent or water system in which ceramic powders such as barium titanic acid and alumina are dispersed. And it is prepared by mixing and dispersing with a high speed mixer and a ball mill by adding a dispersant. Until recently, many organic solvents have been used, but due to environmental problems, they are gradually being converted to water, and in Japan, where most ceramic products are produced, almost all aqueous ceramic slurries are used.

The biggest problem when using an aqueous ceramic slurry is that the release film used in the organic solvent system is not suitable for coating the aqueous ceramic slurry. That is, until recently, release films that are used for coating organic solvent-based ceramic slurries and require low peeling force are coated with curable silicone on PET films, and the surface tension of the release layer (silicon layer) is very low at 30 dyne / cm or less. Therefore, in such a release film, the wettability and coating property of the aqueous ceramic slurry having a very high surface tension are significantly worsened, and the dimensional stability of the ceramic sheet before and after drying is also greatly reduced.

In order to improve this, a method of increasing the critical surface tension by adjusting the silicone coating composition (Japanese Patent No. Hei 8-276539) or introducing a phenyl group into the silicon main chain to increase the surface tension of the release layer (Japanese Patent Hei 9-52319). And a method of increasing the affinity between the release layer and the aqueous slurry by incorporating colloidal silica and a peeling force control agent into a silicone resin (Japanese Patent No. Hei 9-11424). In particular, in the case of a release film incorporating and coating colloidal silica, the wettability and coating property of the aqueous slurry are improved, and the friction resistance and the antistatic property of the ceramic sheet and the roughness of the release layer are expected. . However, as pointed out in Japanese Patent No. 9-11424, as the amount of colloidal silica added increases, the peeling force increases, and the adhesion between the release layer and the PET film is remarkably degraded, which may cause defects in the ceramic manufacturing process. have. In order to increase the adhesion between the release layer and the PET film, a method of adding an additive capable of increasing the adhesion with PET to the silicone resin may be considered, but when colloidal silica is blended together, it is difficult to expect a great effect.

Accordingly, the present invention has been made in view of the above-described conventional problems, and it is possible to improve the adhesion between the release layer and the aqueous slurry, achieve good dimensional stability, and provide a release film having low peeling force. The purpose.

In order to achieve the above object, the release film production method for an aqueous slurry according to the present invention, a silicone resin, a curing agent, colloidal silica, a silane coupling agent and a solvent for improving the dispersibility of the silica in order to obtain an excellent release force The mixed silicone coating liquid is applied to a polyester film primed with a silane coupling agent to produce a release film for an aqueous slurry.

In general, the silane coupling agent is widely used in various glass fiber reinforced composite materials and engineering plastics because of its excellent reactivity with glass, and is also widely used as an additive such as a binder, a coating material, a paint, etc., in which silica particles are used. The silane coupling agent also exhibits excellent compatibility with silicone resins, in particular silicone resins cured with hydrogensilane.

In the present invention, a polyester film primed with a silane coupling agent was used to improve the adhesion between the release layer and the polyester film as described above in consideration of the characteristics of the silane coupling agent. Primer treatment is preferred to in-line coating in consideration of process and economic problems.

The release film requires physical properties such as peeling force, adhesion, surface roughness and heat resistance. That is, low peel force is required because the ceramic sheet should fall off during the manufacturing process of the capacitor. At this time, the silicon should not be transferred to the ceramic sheet, but should be in close contact with the polymer film. Heat shrinkage should not occur.

However, in general, the adhesion between the silicon and the general polymer film is not good, and because of this, condenser defects due to silicon transfer tend to come out, and in the present invention, PET film coated with a silane coupling agent instead of a general polymer film to improve this problem. By using, the adhesiveness of a release layer was improved. That is, not only the silica in the release layer but also the curing agent of the silicone resin reacts with the silane coupling agent constituting the primer layer, thereby making it possible to prepare a release film not only excellent in adhesion and peelability but also suitable for coating a water-based ceramic slurry. Therefore, by using the release film, the adhesion between the silicon and the release film is improved while maintaining the release force due to silicon as it is, and thus the problem of silicon transfer can be solved, whereby a high quality capacitor can be manufactured.

Other features and advantages of the present invention will become more apparent from the following detailed description.

The release film for aqueous slurry produced by the method according to the present invention is a silicone coated release film used for molding a ceramic slurry during a ceramic product process used in electrical and electronic parts, and is coated with a primer to improve adhesion between the silicon coating layer and the film. It is made using a polyester film.

The composition of the primer coated on the polyester film is preferably made of only a silane coupling agent, but a mixture of a silane coupling agent and a polyester copolymer (Co-PET) may be used if necessary.

The structure of the silane coupling agent has a form of X ₃ -Si-Y, where X mainly represents a chlorine atom or an alkoxy group, and Y represents an organic functional group. Silane coupling agents commonly used for dispersing silica particles in coating materials and as surface treatment materials for films are Υ-glycidoxypropyltrimethoxysilane and 메탄 -methacryloxypropyltrimethoxysilane. ), And specific examples are KBM403 and KBM503 of Shin-Etsu Corporation (Japan). The polymerization recipe of the polyester copolymer is 50-90 mol% of phthalic acid and its derivatives, 0-30 mol% of aliphatic dihydrochloric acid and its derivatives as an acid component, at least two or more glycols, and trifunctional abnormal monomers 0 It is 0.01-2 weight% of ester forming monomer obtained by reaction of -2 weight% and a sulfone benzoic acid metal salt with a trifunctional or more than primary functional alcohol. As for the mixing ratio of the polyester copolymer with respect to 100 weight part of silane coupling agents, 0-75 weight part is preferable.

The silicone resin for forming the release layer is a thermosetting silicone resin, and there are two types of condensation reaction type and addition reaction type depending on the curing reaction. In the condensation type, polysiloxane containing a silanol group at its terminal is used as a base polymer, and polymethylhydrogensiloxane is mixed as a crosslinking agent to perform condensation reaction under an organotin acylate catalyst. As shown in Scheme 1 below, dehydrogen condensation is caused by heating to form siloxane bonds.

The characteristic of the condensation reaction type is the peeling property, in particular, light peeling at low peeling speed (low peeling speed), and no exposure phenomenon (phenomena which becomes very difficult when the silicon-treated surface is exposed to the outside air) does not occur. In addition, the addition reaction type is to make polysiloxane containing a vinyl group as a base polymer, mix | blend polymethylhydrogensiloxane as a crosslinking agent, and make it react in presence of a platinum catalyst. As shown in the following reaction formula 2, the reactor port is characterized by the addition reaction by heating and the formation of ethylene bonds, and does not generate by-products such as condensation reaction type. Products are largely divided into three types: solvent type, emulsion type, and solventless type. Among them, the solvent type is the one most used in consideration of surface smoothness and coating property of silicon coating layer.

The characteristic of the addition reaction type is that the peeling property is adjustable, in particular, those having excellent high-speed peelability. In addition, since the pot life is longer than the condensation reaction type, the curing speed is very fast during production, and there is almost no problem of sticking together the xylocones, the addition reaction type silicone is used more recently than the condensation reaction type.

Meanwhile, as colloidal silica used in the present invention, colloidal silica in a form in which ultrafine anhydrous silica is previously dispersed in an organic solvent and in a form in which only silica particles are present is used. In addition to improving the wettability of the water-based coating solution of the ground layer, by providing a certain level of roughness to the silicone resin layer, it plays a role of film formation in water-based ceramic coating. The colloidal silica particle size is appropriately in the range of 0.05 to 5 μm, more preferably in the range of 0.05 to 1 μm. The content of colloidal silica is preferably in the range of 2 to 20 parts by weight based on 100 parts by weight of the silicone resin. A silane coupling agent may be used to improve the dispersibility of colloidal silica particles. The content of the silane coupling agent is preferably in the range of 0 to 2 parts by weight based on 100 parts by weight of the silicone resin.

Silane coupling agents include Υ-glycidoxy propyltrimethoxysilane and Υ-methane chloropropylpropyl methoxysilane, of which Υ-methane chloropropylpropyl methoxysilane has a vinyl group at one end. Therefore, not only the dispersibility of silica particles in the silicone resin curing reaction but also the interface adhesion between the particles and the resin are greatly improved.

The solvent in the mixing is used by mixing toluene and methyl ethyl ketone, and the mixing ratio is preferably 5: 5.

In the present invention, the coating uses a conventional method. In other words, gravure (Gravure) or reverse (Reverse) method and hot air drying. The higher the curing temperature can be cured in a shorter time, but the appropriate curing time and curing temperature is set in consideration of the temperature and productivity that the film does not deform.

The evaluation method for the performance of the release film made as described above is performed by the following method.

1. Peelability Evaluation Method

The standard adhesive tape is pressed onto the silicone-coated film under certain conditions and aged under certain conditions to measure the strength (peel strength) required to peel off the adhesive tape.

2. Residual adhesion rate

As the pressure-sensitive adhesive comes into contact with the siliconized surface for release paper, the silicone may shift to change the adhesive force of the adhesive. As a method for evaluating this, a standard adhesive tape is attached to a siliconized surface for release paper, aged under certain conditions, and the adhesive force (A1) after peeling off from the siliconized surface and the adhesive force (A2) of the adhesive tape not in contact with the silicon surface are measured. Residual adhesion rate is represented by the following equation (1).

Residual Adhesion Rate (%) = (A1 / A2) × 100

3. Adhesiveness

As a method of measuring the adhesion between the silicone release layer and the PET film, after rubbing strongly 5-10 times with a finger, the degree of detachment of the silicon layer is visually confirmed. If there is no change on the surface of the release layer at the time of confirmation, it is regarded as defective if it turns out to be good or cloudy or if the detachment of the silicon layer is visible.

4. Aqueous Ceramic Slurry Coating Properties

The composition of the aqueous ceramic slurry is 20 parts of water dispersible polyurethane resin, 10 parts of water dispersible acrylic resin, 10 parts of butylbenzyl phthalate, and 10 parts of H ₂ O based on 100 parts of BaTiO ₃ (barium titanic acid). The slurry is coated by dry roll, gravure, die coater or the like and dried to obtain a 10 탆 thick ceramic sheet. At this time, the coating width shrinks after drying, and the wettability is good, and there is no defect on the coated surface.The shrinkage occurs on the coated surface after drying, and when the wettability is poor or when there are defects such as pin holes on the coated surface. Judging by.

<Example 1>

The silicone coating solution was coated on a general polyester film in an amount of 0.5 to 1.0 g / m using a silicone solid having the following composition. After the coating, the air was dried for 1 minute in a 120 ° C. oven.

Composition of Silicone Coating Liquid

Silicone resin (KS 3703 from Shin-Etsu, Japan): 0.6kg

-Heavy release control agent (Shin-Etsu Co., Ltd. KS3800): 0.2kg

-Pt based silicone curing catalyst (PL-50 from Shin-Etsu, Japan): 10g

-Colloidal Silica (Aerosil 200, Japan's Arerozil): 40g

-Silane Coupling Agent (KBM 503 from Shin-Etsu, Japan): 5g

Toluene: 2.5kg

-Methyl ethyl ketone: 2.5 kg

<Example 2>

The silicone coating liquid having the same composition as in Example 1 was coated on a polyester film treated with a silane coupling agent.

<Example 3>

The silicone coating liquid having the same composition as in Example 1 was coated on a primer-coated polyester film by a mixture of a silane coupling agent and a polyester copolymer in a component ratio of 5: 5.

<Example 4>

The amount of colloidal silica in the silicon coating liquid having the same composition as in Example 1 was 200g and coated on a general polyester film.

<Comparative Example 1>

The silicone coating liquid which excluded colloidal silica in the composition of Example 1 was coated on the general polyester film.

<Comparative Example 2>

The silicone coating liquid, which was obtained by removing colloidal silica in the composition of Example 1, was coated on a polyester film treated with a silane coupling agent.

<Comparative Example 3>

A silicone coating liquid having the same composition as in Example 1 was coated on a PET film treated with a primer copolymer only.

Table 1 below shows the measured physical properties of the release film obtained through Examples 1 to 4 and Comparative Examples 1 to 3.

division Peeling force (g / 25mm) Residual Adhesion Rate (%) Adhesion Ceramic Slurry Coating Example 1 39 83 Bad Good Example 2 52 97 Good Good Example 3 43 90 Good Good Example 4 97 80 Bad Good Comparative Example 1 25 85 Bad Bad Comparative Example 2 27 98 Good Bad Comparative Example 3 45 92 Bad Good

As can be seen in Table 1, in the case of the release film according to Example 2 and Example 3 shows the most excellent physical properties. That is, by forming a silicone coating solution containing an appropriate amount of colloidal silica, a mixture of a silane coupling agent alone or a mixture of a silane coupling agent and a polyester copolymer is coated by coating the silicone coating solution on a polyester film coated with a primer It can be seen that the release film exhibits excellent physical properties. Therefore, when manufacturing a ceramic product using the release film according to the present invention can lower the defective rate can increase the productivity.

Claims (3)

Forming a silicone coating solution comprising a silicone resin, a curing agent, colloidal silica, a silane coupling agent and a solvent for improving the dispersibility of the silica; Primer coating the polyester film with the silane coupling agent alone or a mixture of the silane coupling agent and the polyester copolymer; The silicone coating solution is applied to a primer-coated polyester film, the step of curing the release film manufacturing method for a water-based slurry comprising the step of making a release film by curing. The content ratio of the mixture of the silane coupling agent and the polyester copolymer is in the range of 0 to 75 parts by weight of the polyester copolymer with respect to 100 parts by weight of the silane coupling agent, the component of the polyester copolymer Phosphoric acid and its derivatives are 50-90 mole parts, aliphatic dibasic acid and its derivatives 0-30 mole%, at least two or more glycols and tri-functional monomers 0-2% by weight, and sulfone benzoic acid metal salts. Method for producing a release film for an aqueous slurry, characterized in that 0.01 to 2% by weight of ester-forming monomer obtained by reaction with at least primary alcohol. The silicone resin of claim 1, wherein the silicone resin for forming the silicone coating solution is a condensation reaction type or an addition reaction type thermosetting resin, and the colloidal silica is 2 to 20 parts by weight of the silicone resin as a component of the release layer of the silicone coating solution. A weight part is contained, The silane coupling agent contains 0-2 weight part with respect to 100 weight part of silicone resins. The release film manufacturing method for aqueous slurries characterized by the above-mentioned.