JP7762214B2 - Release film - Google Patents

Description

This disclosure relates to release films.

Release films are typically coated with an adhesive and used as a protective film to protect the adhesive components from foreign matter in the air or unwanted adherends, and typically consist of a polyester base film with a release layer on top.

Release films are generally attached to adhesive films or tapes as protective films, preventing adhesion to unintended substrates and preventing contamination by dust and foreign matter before the adhesive is used. Other uses include preventing adhesion between molds and molded objects during heat and pressure molding processes, such as in printed wiring boards and in-mold molding; as a coating substrate for coating various resin materials, such as ceramic slurries, on the release surface of the release film; and as an intermediate material used as a laminate to protect various resin layers coated on other substrates. In particular, release films are used as carrier films for applying a thin, uniform coating of ceramic slurries to green sheets that make up MLCCs (Multi-Layer Ceramic Capacitors). MLCCs are a type of capacitor used to store electricity and stabilize current. Due to their small size and large capacitance, they are widely used in portable electronic devices, and demand has increased significantly recently due to the popularity of smartphones and tablet PCs. MLCCs are completed by alternately stacking tens or hundreds of layers of green sheets and internal metal electrodes, and then connecting external electrodes, and their sizes vary from less than 1 mm to several nanometers.

The green sheets used in MLCCs are formed by uniformly applying ceramic slurry to a carrier film support and then firing it. The carrier film used to form the green sheets is made from a biaxially oriented polyester film base, which offers excellent mechanical strength, dimensional stability, heat resistance, and price competitiveness. One side of the film is covered with a release film coated with a polymeric silicone release layer.

Recent trends toward smaller MLCCs and higher capacity have led to demands for thinner green sheets and for ceramic slurries to be laminated in even more layers. However, if the peel strength of the release film used in manufacturing MLCCs is too low, the ceramic slurry may peel off the release film first. Conversely, if the release strength of the release film is too high, cracks or breaks may occur in the green sheet when the release film is removed from the ceramic green sheet. Therefore, the release film used in MLCCs must have physical properties that allow it to be peeled off with an appropriate peel force.

Furthermore, if the organic solvent used in producing the ceramic slurry does not volatilize sufficiently and remains on the release layer, orange peel-like stains appear on the surface of the green sheet. This problem, which is not only due to roughness but also occurs when the release layer has low solvent resistance and the ceramic slurry solvent remains in the release layer, required improvement. Preventing defects in green sheets such as those described above leads to improved MLCC reliability, so the functionality of the release film can be said to be extremely important in MLCC production.

This disclosure provides technology for release films. The purpose of this disclosure is to provide release films that can achieve a wide range of peel forces and exhibit excellent stability over time.

The present disclosure aims to provide a release film that can be formed by low-temperature curing using a water-based system.

In one aspect, the present disclosure can provide a release film.

In one aspect, a release film includes a substrate film; and a release layer formed by applying a release coating composition to at least one surface of the substrate film. In a depth profile measured from the surface of the release layer in a thickness direction using a time-of-flight secondary ion mass spectrometer (TOF-SIMS), the maximum NH -ion count in an NH ^-ion intensity curve, the ^{NH -ion count} at the surface of the release layer, and the NH ^-ion count at the interface between the release layer and the substrate film are defined as I _{NH_max} , I _{NH_t} , and I _{NH_b,} respectively. The ratio of I _{NH_t} /I _{NH_max} may be 0.90 or less, and I _{NH_t} > I _{NH_b} .

In one aspect, the NH 3 ^- ionic strength curve may include an inflection point.

In one aspect, the NH 3 ^- ionic strength curve may have a concave shape.

In one aspect, the release layer can further include one or more of Si ⁻ , S ⁻ , C ₇ H ₅ O ₂ ⁻ , and C ₃ H ₅ N ₅ ⁻ ions.

In one aspect, the release layer contains Si ^- ions and C ₇ H ₅ O ₂ ^- ions, and in a depth profile measured using TOF-SIMS from the surface of the release layer in the thickness direction, the ion intensity of Si ^- decreases and the ion intensity of C ₇ H ₅ O ₂ ^- increases, and the release layer may include a point where the ion intensity of the Si ^- ions and the ion intensity of the C ₇ H ₅ O ₂ ^- ions are the same.

In one aspect, the release layer contains S ² -ions, and in a depth profile measured using TOF-SIMS from the surface of the release layer in the thickness direction, the S ^{2 -ion} intensity curve may include an inflection point.

In one aspect, the S 2 ⁻ ionic strength curve may have a concave shape.

In one aspect, the release layer contains C ₃ H ₅ N ₅ ^- ions, and in a depth profile measured using TOF-SIMS from the surface of the release layer in the thickness direction, the ion intensity of C ₃ H ₅ N ₅ ^- may decrease at a position adjacent to the surface of the release layer.

In one aspect, the release film may exhibit a tape instant peel force of 5 to 32 gf/in.

In one aspect, the release film may exhibit a tape peel strength of 3 to 1000 gf/in after one day at room temperature.

In one aspect, the release film may exhibit a green sheet peel force of 1 to 3 gf/in.

In one aspect, the release layer can have a silicone content of 0.001 to 0.2 g/m ² as measured using an X-ray fluorescence analyzer (XRF).

In one aspect, the surface energy of the release layer may be 19 to 30 dyne/cm.

In one aspect, the release film may be formed by curing the release coating composition at a temperature of 150°C or less.

In one aspect, the release coating composition may be an aqueous release coating composition that includes a silicone emulsion component (A) containing polydimethylsiloxane (PDMS) as a composition curable at a temperature of 150°C or less; a component (B) containing two or more functional groups in one molecule that can undergo a condensation reaction with the silicone emulsion component; and an acid catalyst.

The release film according to one aspect of the present disclosure can achieve a wide range of release forces during production into a release film and exhibit excellent stability over time, an effect that is even superior when compared to release films produced using a silicone-based release coating composition.

Although the release film according to one aspect of the present disclosure is a silicone-based film, it can be formed by low-temperature curing using a water-based system, which is superior to conventional silicone-based films formed by high-temperature curing.

1 shows the results of TOF-SIMS depth profile measurement of a release film according to an embodiment of the present invention.

1 is a schematic diagram showing a conventional silicone-based release film and a release film according to an embodiment of the present invention.

1 is a graph showing the FT-IR spectrum measurement results of a release film according to an embodiment of the present invention.

The various aspects or examples described in this document are provided for the purpose of clearly explaining the technical idea of the present disclosure and are not intended to limit it to specific embodiments. The technical idea of the present disclosure includes various modifications, equivalents, and alternatives of each aspect or example described in this document, as well as aspects or examples that are selectively combined in whole or in part. Furthermore, the scope of the technical idea of the present disclosure is not limited to the various aspects or examples presented below or the specific descriptions thereof.

Unless otherwise defined, terms used in this document, including technical and scientific terms, may have the meaning commonly understood by a person of ordinary skill in the art to which this disclosure belongs.

1. Release film

In one aspect of the present disclosure, the release film may include a substrate film; and a release layer formed by applying a release coating composition to at least one surface of the substrate film.

In one aspect, the release film may have a ratio of I NH_t /I NH_max of 0.90 or less, and I ^NH_t >I NH_b, where I NH_max, I NH_t, and I NH_b are the maximum NH ^{-ion count in an NH -ion intensity} curve in a depth profile measured from the surface of the release layer in a thickness direction using a time-of-flight secondary ion mass spectrometer _(TOF - _{SIMS )} , the NH ^-ion count at the surface of the release layer, and the NH _-ion count at the boundary between the _release layer and the substrate _{film ,} respectively.

Figure 1 shows the results of a TOF-SIMS depth profile measurement of a release film according to one embodiment of the present invention.

1 , the ratio of I _{NH_t} /I _{NH_max} is 0.90 or less, and I _{NH_t} >I _{NH_b} . For example, the ratio of I _{NH_t} /I _{NH_max} may be 0.80 or less, or 0.70 or less, or 0.60 or less , or 0.50 or less, or 0.40 or less, or 0.30 or less, or 0.20 or less, or 0.10 or less, or 0.05 or more, or 0.07 or more, or 0.09 or more.

For example, when the ratio of I _{NH_t} /I _{NH_max} is 0.90 or less, a large amount of non-silicone components (e.g., melamine components) may be present as a major component on the surface of the release layer. For example, when the ratio of I _{NH_t} /I _{NH_max} is 0.50 or less, a non-silicone component (e.g., melamine component), surfactants, and other components (e.g., components that do not sufficiently phase separate from the melamine component) may be present on the surface of the release layer. For example, when the ratio of I _{NH_t} /I _{NH_max} is 0.10 or less, a small amount of non-silicone components (e.g., melamine components) may be present on the surface of the release layer, and a large amount of other components (e.g., components that sufficiently phase separate from the melamine component) may be present on the surface of the release layer.

1, the NH ⁻ ionic strength curve includes an inflection point. Here, the inflection point refers to a point where the slope of the tangent line changes as the NH ⁻ ionic strength increases or decreases, and there may be one or more of an inflection point where the rate of increase in the NH ⁻ ionic strength decreases between a point corresponding to I _{NH_t} and a point corresponding to I _{NH_max} on the ionic strength curve, and an inflection point where the rate of decrease in the NH ⁻ ionic strength decreases between a point corresponding to I _{NH_max} and a point corresponding to I _{NH_b} on the ionic strength curve.

For example, the inflection point where the rate of increase in the NH 3 ⁻ ion intensity decreases between a point corresponding to I _{NH_t} and a point corresponding to I _{NH_max} in the ion intensity curve may be the point where the Si content in the release layer begins to decrease.

Referring to FIG. 1, the NH 3 ^- ionic strength curve may have a concave shape.

The concave shape of the NH- ^ion intensity curve means that the distribution of the silicone component from the entire surface of the release film to the substrate film has a concave shape. That is, it may mean that the proportion of the silicone component is high at the entire surface of the release film, and the content of the silicone component decreases in the middle portion of the release film, with a non-silicone component (e.g., _melamine component) as the main component, ^and the substrate film is present underneath. In one aspect, the release layer may further include one or more of _Si- ^, _S- ^, _C7H5O2- ^, and _{C3H5N5- ions} .

For example, the release layer can include a combination of any two or more of Si ⁻ , S ⁻ , C ₇ H ₅ O ₂ ⁻ , and C ₃ H ₅ N ₅ ⁻ ions. For example, the release layer can include Si ⁻ , S ⁻ , C ₇ H ₅ O ₂ ⁻ , and C ₃ H ₅ N ₅ ⁻ ions.

Referring to FIG. 1, the release layer includes Si ⁻ ions and C ₇ H ₅ O ₂ ⁻ ions, and in a depth profile measured using TOF-SIMS from the surface of the release layer in the thickness direction, the ion intensity of Si ⁻ decreases and the ion intensity of C ₇ H ₅ O ₂ ⁻ increases, and the release layer may include a point where the ion intensity of the Si ⁻ ions and the ion intensity of the C ₇ H ₅ O ₂ ⁻ ions are the same.

For example, the point in the release layer where the ionic strength of the Si ^- ions and C ₇ H ₅ O ₂ ^- ions is the same may be the point where a region where non-silicone components (e.g., melamine components) begin to be substantially contained relative to silicone components begins to be formed.

For example, the point where the ionic strengths of the Si ^-ions and C ₇ H ₅ O ₂ ^-ions are the same may be closer to the point corresponding to I _{NH_t} than to the point corresponding to I _{NH_b} , or may be closer to the point corresponding to I _{NH_max} than to the point corresponding to I _{NH_t} .

For example, the point where the ionic strengths of the Si ^- ion and _C7H5O2 ^- _ion are the same may be the point where the non-silicone component region begins in a release film having _a silicone component-non-silicone component (e.g., melamine component) region-substrate film structure. This point may be closer to the point corresponding to _{INH_t} than to the point corresponding to _{INH_b} , or closer to the point corresponding to _{INH_max} than to the point corresponding to _{INH_t} , which may indicate a smoother concentration change rather than a sharp change in the concentration of the silicone component and non-silicone component. This may be due to the manufacturing process in which a release coating composition containing a silicone component and a non-silicone component is applied once to form the release layer.

1, the release layer contains S ^ions , and in a depth profile measured using TOF-SIMS from the surface of the release layer in a thickness direction, an S ^ion intensity curve may include an inflection point. An inflection point where the rate of increase in S ion intensity decreases may exist between a point corresponding to I _{NH_t} and a point corresponding to I _{NH_max} in the ion intensity curve, and an inflection point where the rate of decrease in ^S ion intensity decreases may exist between a point corresponding to I _{NH_max} and a point corresponding to I _{NH_b} in the ^ion intensity curve.

Referring to FIG. 1, the ionic strength curve of the S 2 ⁻ may have a concave shape.

Referring to FIG. 1, the release layer contains C ₃ H ₅ N ₅ ^- ions, and in a depth profile measured using TOF-SIMS from the surface of the release layer in the thickness direction, the ion intensity of C ₃ H ₅ N ₅ ^- may decrease at a position adjacent to the surface of the release layer.

In one aspect of the present disclosure, a release film can be manufactured by applying a release coating composition to at least one surface of a substrate film to form a release layer, and the release film manufactured in this manner can have the following physical properties. The following physical properties can be measured by the methods described in the experimental examples.

In one aspect, the release film may exhibit a tape instant peel strength of 5 to 32 gf/in, or a peel strength between the upper and lower limits described above, for example, 7 gf/in or more, 9 gf/in or more, 11 gf/in or more, 13 gf/in or more, 15 gf/in or more, 17 gf/in or more, 19 gf/in or more, 21 gf/in or more, 23 gf/in or more, 25 gf/in or more /in or more, 27 gf/in or more, 29 gf/in or more, or 31 gf/in or more, or 31 gf/in or less, 29 gf/in or less, 27 gf/in or less, 25 gf/in or less, 23 gf/in or less, 21 gf/in or less, 19 gf/in or less, 17 gf/in or less, 15 gf/in or less, 13 gf/in or less, 11 gf/in or less, 9 gf/in or less, or 7 gf/in or less.

In one aspect, the release film may exhibit a tape peel strength at room temperature after 1 day of 3 to 1000 gf/in, or a peel strength between the upper and lower limits described above, for example, 10 gf/in or more, 50 gf/in or more, 100 gf/in or more, 200 gf/in or more, 300 gf/in or more, 400 gf/in or more, 500 gf/in or more, 600 gf/in or more. The release strength may be 900 gf/in or more, 700 gf/in or more, 800 gf/in or more, or 900 gf/in or more, or 900 gf/in or less, 800 gf/in or less, 700 gf/in or less, 600 gf/in or less, 500 gf/in or less, 400 gf/in or less, 300 gf/in or less, 200 gf/in or less, 100 gf/in or less, 50 gf/in or less, or 20 gf/in or less. Such a release film satisfies the release strength of a light, heavy, or ultra-heavy release film and can be used in a variety of fields requiring such a release strength. In one aspect, the release film exhibits a wide range of tape room temperature 1-day release strength, a range that is unattainable with conventional silicone release films.

In one aspect, the release film may exhibit a green sheet peel strength of 1 to 3 gf/in, or a peel strength between the upper and lower limits described above. The green sheet peel strength may be measured using the method described in Experimental Example 1 and may represent the peel strength for a 3 μm thick green sheet.

Therefore, the release film according to one aspect of the present disclosure has the advantage of being able to achieve a variety of room temperature one-day tape peel strength levels (grades) while at the same time achieving a certain range of light peel strength based on the immediate tape peel strength or green sheet peel strength. As a result, a single release film can be used in a variety of industrial fields that require room temperature one-day tape peel strength for various purposes, and can also be used in industrial fields that require a light peel strength based on the immediate tape peel strength or green sheet peel strength, making it suitable for a variety of purposes.

In one aspect, the release film can have a silicone content of the release layer of from about 0.001 to about 0.2 g/m ² as measured using an X-ray fluorescence analyzer.

In one aspect, the release film may exhibit a residual adhesion rate of about 94%, about 95%, or about 96% or more, and the residual adhesion rate may be measured using the method described in Experimental Example 4. Generally, in the process of peeling off the release film, an adhesive such as a pressure-sensitive adhesive (PSA) or an optically clear adhesive (OCA) is applied to the release film, and then the release film is peeled off. However, during this peeling process, uncured components present in the release layer of the release film may transfer, which can cause problems and interfere with the adhesive properties of the adhesive. The release film of the present disclosure has a residual adhesion rate of about 95% or more, making it advantageous for use in fields requiring high standards.

In one aspect, the release film may have a surface energy of about 19 to about 30 dyne/cm or about 19.5 to about 27 dyne/cm, or may have a surface energy value between the upper and lower limits recited above. The surface energy of the release layer may be measured by the method described in Experimental Example 5.

In one aspect, the release film may have a residual amount of volatile organic compounds of approximately 5 ppm or less, making it suitable for use as an environmentally friendly material.

2. Release film manufacturing method

In one aspect of the present disclosure, the method for producing a release film is not particularly limited, as long as it forms a release layer using a release coating composition. For example, a release coating composition is applied to at least one surface of a substrate film, and the coating is then heated and dried to cure component (B) and the silicone emulsion component contained in the release coating composition, thereby forming a release layer, thereby obtaining a release film.

In one aspect, the method for applying the release coating composition may be a known method widely used in the field of release films, such as, but not limited to, gravure coating, bar coating, spray coating, spin coating, knife coating, roll coating, die coating, in-line coating, and off-line coating.

In one aspect, the applied release coating composition can be thermally cured by heating and drying. At this time, the heating temperature can be 110°C to 160°C, 120°C to 160°C, 130°C to 160°C, 140°C to 160°C, 150°C to 160°C, 145°C to 155°C, or 150°C to 155°C, and can be within the ranges described above. In another aspect, the heating time can be 5 seconds to 60 seconds, 10 seconds to 40 seconds, 15 seconds to 30 seconds, or 20 seconds to 25 seconds, and can be within the ranges described above.

In one aspect, a post-curing process may be included to cure any uncured components after the heat drying of the release coating composition. For example, the post-curing process may involve rolling the release film produced by heat drying into a roll and then treating it at 40°C to 60°C for 1 to 5 days. The treatment temperature may be 40°C to 60°C, 45°C to 55°C, 47°C to 53°C, 49°C to 53°C, 50°C to 53°C, or 50°C to 51°C, and the treatment time may be 1 to 5 days, 1.5 to 4.5 days, 2 to 4 days, 2.5 to 3.5 days, or 3 to 3.5 days. Performing a post-curing process may improve the stability over time of the physical properties of the release film (e.g., peel strength, residual adhesion, or rub-off characteristics).

In one aspect, the release layer of the release film can be formed with a dry thickness of 0.01 to 2 μm, or 50 nm to 500 nm.

In one aspect, the release film may be used in pressure-sensitive adhesives, semi-curing adhesives, protective films, coating substrates, interleaf liner, ceramic sheets for multilayer ceramic capacitors, semi-curing resins for printed circuits, or prepregs. The present disclosure will become more clear through the above-mentioned aspects and the experimental examples and examples described below. Hereinafter, the present disclosure will be described in detail through examples described with reference to the accompanying tables so that those skilled in the art can easily understand and implement the present disclosure. However, these experimental examples and examples are intended to exemplify the present disclosure, and the scope of the present disclosure is not limited to these experimental examples and examples.

3. Base film

In one aspect of the present disclosure, the base film constituting the release film can be any known film that has been widely used in the field of release films, but is not limited to this.

In one aspect, the substrate film may be formed from a polyester-based polymer, but the substrate film to which the release coating composition is applied is not limited to a polyester-based film. Specifically, the polyester-based polymer may be, but is not limited to, polyethylene terephthalate polymer, polybutylene terephthalate polymer, polyethylene naphthalate polymer, polyphenylene sulfide polymer, polyether ether ketone polymer, polyphthalamide polymer, polyimide polymer, polysulfone polymer, polyethersulfone polymer, polyetherimide polymer, or a combination thereof.

In one aspect, the polyester polymer may be a polyester obtained from the condensation reaction of an aromatic dicarboxylic acid and an aliphatic glycol. In one aspect, the aromatic dicarboxylic acid may be, but is not limited to, isophthalic acid, phthalic acid, terephthalic acid, 2,6-naphthalenedicarboxylic acid, adipic acid, sebacic acid, an oxycarboxylic acid (e.g., p-oxybenzoic acid), or a combination thereof. In one aspect, the aliphatic glycol may be, but is not limited to, ethylene glycol, diethylene glycol, propylene glycol, butanediol, 1,4-cyclohexanedimethanol, neopentyl glycol, or a combination thereof.

In one aspect, the polyester polymer can be a combination of two or more of the above-mentioned aromatic dicarboxylic acids and aliphatic glycols, and a copolymer containing a third component can also be used. However, when considering heat resistance, chemical resistance, mechanical strength, and economy, it may be preferable to use polyethylene terephthalate. In another aspect, it may be preferable to use a biaxially stretched polyethylene terephthalate film as the substrate film.

In one aspect, the substrate film may have a thickness of 10 to 200 μm, but is not limited to this.

In one aspect, the release coating composition can be applied to at least one surface of the substrate film to form a release layer.

4. Ingredient (B)

A release coating composition according to one aspect of the present disclosure uses component (B) as the main chain component that forms the release layer after curing. When component (B) is used, a hard release layer coating can be obtained due to the high crosslink density, achieving a level of curing that exceeds that of existing silicone-based release coating compositions. This is because, in the case of release films used in the ceramic green sheet manufacturing process for producing MLCCs, it is effective to harden the release layer coating in order to adjust the release force to the desired level.

Existing silicone-based release coating compositions generally contain only silicone-based materials such as silicone emulsions. However, silicone emulsions are difficult to cure at low temperatures and cure well at high temperatures of approximately 230°C or higher, making it difficult to use compositions containing only silicone emulsions at temperatures of approximately 150°C. Figure 2 is a schematic diagram showing film formation by low-temperature curing at temperatures below 150°C for a conventional silicone-based release coating composition and a water-based release coating composition according to one embodiment of the present invention. Referring to Figure 2, it can be seen that when using an existing silicone-based release coating composition at temperatures below 150°C, the bonding strength with the substrate film (e.g., PET film) is low (see the diagram on the left).

For example, the film manufacturing process can be divided into an offline process, in which the finished film fabric is unwound, coated, and then rewinded to produce a film, and an inline process, in which the polymer is extruded to form a sheet and then coated to produce a film. The drying temperature in the offline process is a maximum of approximately 150°C, while the inline process can have a drying temperature of approximately 210-240°C during the film stretching process. Therefore, the offline process has traditionally used only non-aqueous solvents (i.e., solvent-based solvents) for curing at temperatures below 150°C.

However, due to environmental friendliness and other requirements, when using a water-based solvent for the composition, curing must be carried out at temperatures below approximately 150°C (e.g., below approximately 130°C). Emulsion is a suitable formulation for use in water-based systems, but as mentioned above, when using a silicone emulsion, curing at temperatures below 150°C is difficult. Furthermore, even after curing, the release film's rub-off properties and substrate adhesion decrease, and when a surfactant is added to solve this problem, curing is inhibited.

As described above, the release coating composition according to one aspect of the present disclosure includes component (B) containing two or more functional groups capable of condensation reaction with the silicone emulsion component, thereby achieving a high degree of cure at temperatures of 150°C or less while also realizing excellent physical properties such as rub-off characteristics. Therefore, it may be possible to use aqueous emulsions in offline processes. Referring to Figure 2, it can be seen that by utilizing component (B) (e.g., a melamine component), a phase separation curing reaction is induced, resulting in a film with excellent adhesion and a high degree of cure (see the diagram on the right).

In one aspect, component (B) can form a Si-O-R-N bond structure (where R is an alkyl group having 1 to 4 carbon atoms) through a silicone emulsion component condensation reaction.

For example, R can be —CH ₂ —, —CH ₂ CH ₂ —, —CH ₂ CH ₂ CH ₂ —, or —CH ₂ CH ₂ CH ₂ CH ₂ —.

In one aspect, the functional group contained in component (B) may be an amine group or an amine-derived functional group.

In one aspect, component (B) is not particularly limited as long as it contains two or more functional groups in one molecule that can undergo a condensation reaction with the silicone emulsion component, but it can be a melamine component, generally produced by reacting melamine with formaldehyde, and can be an alkyl etherified melamine compound obtained by reacting the methylol melamine thus produced with an alcohol having an appropriate carbon number under acid catalyzed conditions.

In one aspect, component (B) may refer to a melamine compound having the structure of the following chemical formula 1, its oligomer, its polymer, and/or a combination thereof.

[Chemical formula 1]

Here, X represents a hydrogen atom, —CH ₂ OH, or —CH ₂ —O—R, and may be the same or different. R represents an alkyl group having 1 to 8 carbon atoms, and may be the same or different. At least one X may be —CH ₂ —O—CH ₃ .

In one aspect, each of the X's may be —CH ₂ —O—CH ₃ , and the melamine compound may be a full ether type methylated melamine, a melamine oligomer, and/or a melamine polymer.

In one aspect, component (B) can be any of a variety of commercially available and widely used products, including, but not limited to, Cymel 300, Cymel 301, Cymel 303LF, Cymel 350, and Cymel 370N (all products of Allnex). Commercially available products can be used alone or in combination of two or more.

In one aspect, the content of component (B) may be about 0.2 to about 1.0 wt %, specifically about 0.2 to about 0.8 wt %, about 0.3 to about 0.7 wt %, about 0.4 to about 0.6 wt %, or about 0.5 to about 0.6 wt %, based on the total weight of the entire composition. If component (B) is used in an amount that is too small, below the minimum value, the desired curing effect, i.e., the effect of maintaining the hardness of the release layer and reducing the green sheet peel strength of the release film, may be weakened, and the peel strength may not be adjusted as desired. Furthermore, if component (B) is not cured sufficiently, the stability of the release film over time may decrease. Therefore, it is recommended that the content of component (B) satisfy the content ratio with the acid catalyst described below.

In one aspect, the total acid number of component (B) may be 390 to 780 mg KOH/g, specifically 400 KOH/g or more, 450 KOH/g or more, 500 KOH/g or more, 550 KOH/g or more, 600 KOH/g or more, 650 KOH/g or more, 700 KOH/g or more, or 750 KOH/g or more, or 730 KOH/g or less, 680 KOH/g or less, 630 KOH/g or less, 580 KOH/g or less, 530 KOH/g or less, 480 KOH/g or less, or 430 KOH/g or less, but is not limited thereto.

5. Silicone emulsion ingredients

In one aspect of the present disclosure, a silicone emulsion component may be used as a binder or release force modifier in a release coating composition. Because component (B) has a low molecular weight monomer, it forms a dense crosslinked structure after curing, resulting in a high crosslink density. This increases the hardness of the release layer during coating, but the higher the hardness of the release layer, the lower the release force of the green sheet. To address this issue, a silicone emulsion component having soft properties and containing a functional group with release properties, such as Si— _CH3, may be co-cured to reduce the hardness and increase the softness of the release layer. As described above, increasing the softness of the release layer increases the release force of the release film. The present disclosure provides the effect of achieving a wide range of release forces, particularly a wide range of tape release forces at room temperature for one day, by combining component (B) and the silicone emulsion component.

The silicone emulsion component can form an Si-O-N bond structure through a condensation reaction with component (B). The resulting component (B)-silicone emulsion component copolymer and this structure can increase the softness of the release layer and its stability over time.

For example, the melamine component of Formula 1 may have a maximum of six functional groups. In this case, the _NX2 group of the melamine component may form an Si—O—N bond structure through a condensation reaction with the silicone emulsion component.

Typically, silicone-based release films increase their release strength by adding a silicone polymer component. However, if the content of the silicone polymer component exceeds 50 wt % based on the total weight of the entire composition, serious problems with stability over time occur. This is because, over time, the silicone polymer component that should be present on the surface of the release layer impregnates into the interior of the release layer. Unlike conventional silicone-based release films, the release coating composition of the present disclosure, as described above, copolymerizes component (B) and the silicone emulsion component to form a crosslinked network structure. This allows the functional groups that exhibit release properties to remain on the surface of the release layer without impregnating the interior, thereby demonstrating excellent stability over time.

In one aspect, the silicone emulsion component is not particularly limited, as long as it can combine with component (B) to form a crosslinked network structure and impart softness. For example, the silicone emulsion component may not contain any side chains other than the main chain, although this is not particularly limited.

In one embodiment, the silicone emulsion component may be free of polyalkylene glycol (e.g., polyethylene glycol, PEG).

In one embodiment, the silicone emulsion component may be free of hydroxyl groups, polyether groups, and polyester groups.

In one embodiment, the silicone emulsion component may be free of alkenyl groups.

When using a silicone emulsion containing a side chain, the release properties must be limited to heavy release (200 g or more based on TESA 7475 tape), and films using compositions containing this may be limited to use in heavy release areas such as MLCC. However, as described above, the silicone emulsion component in this disclosure does not contain side chains such as polyalkylene glycol, hydroxyl groups, polyether groups, polyester groups, or alkenyl groups other than the main chain. Therefore, even when cured with component (B), the surface of the release layer can be formed with the Si- _CH3 component, just as when using existing silicone-based curing. Therefore, it can be used not only for heavy release applications such as MLCC, but also for a variety of applications such as light release areas.

For example, the silicone emulsion component may be, but is not limited to, polydimethylsiloxane (PDMS). For example, the silicone emulsion component may be, but is not limited to, branched polydimethylsiloxane.

In one embodiment, the ratio of Si-Vi to Si-H in the silicone emulsion components may be 1:1.5 to 1:2.5. For example, the ratio of Si-Vi to Si-H in the silicone emulsion components may be 1:1.6 to 1:2.3. Here, "Si-Vi" refers to a silicone-vinyl group bond, and "Si-H" refers to a silicone-hydrogen bond. If the Si-Vi:Si-Hi ratio in the silicone emulsion components is less than 1:1.5, the composition may not cure sufficiently during curing, resulting in poor residual adhesion and poor substrate adhesion. If the Si-Vi:Si-Hi ratio in the silicone emulsion components exceeds 1:2.5, resulting in an excessively high Si-H content, the Si-H may react with other components (e.g., hydroxyl groups), increasing release force over time and reducing stability over time.

In one embodiment, the content of the silicone emulsion component may be 0.02 to 9 wt %, 0.02 to 8 wt %, 0.03 to 7 wt %, 0.04 to 6 wt %, or 0.05 to 6 wt %, based on the total weight of the entire composition. If the silicone emulsion component is used in an excessive amount exceeding the maximum value, component (B) may not cure sufficiently, and the uncured silicone emulsion component or component (B) may rise to the surface of the release layer, resulting in poor rub-off characteristics of the release film (i.e., the adhesive strength or cohesion of the release layer to the substrate film). If the silicone emulsion component is used too little, below the minimum value, a crosslinked network structure may not be sufficiently formed by the curing reaction, and the desired release strength or stability over time may not be achieved.

In one embodiment, the silicone emulsion component may further include a metal catalyst. For example, the metal catalyst may be, but is not limited to, an alkali metal catalyst, an alkaline earth metal catalyst, or a rare earth metal catalyst. For example, the metal catalyst may be, but is not limited to, a platinum catalyst.

In one aspect, the weight ratio of component (B) to the silicone emulsion may be 100:10 to 100:900 on a solids basis, and may be a weight ratio between the upper and lower limits described above.

6. Acid Catalyst

In one aspect, the acid catalyst is not limited as long as it is known to catalyze the crosslinking reaction of component (B) or the crosslinking reaction between component (B) and a silicone emulsion component, and can be appropriately selected and used. For example, the acid catalyst can be inorganic acids such as hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, etc.; oxalic acid, acetic acid, formic acid, methanesulfonic acid, trifluoromethanesulfonic acid, isoprene sulfonic acid, camphorsulfonic acid, hexanesulfonic acid, octanesulfonic acid, nonanesulfonic acid, decane sulfonic acid, hexadecanesulfonic acid, dinonylnaphthalenesulfonic acid, dinonylnaphthalenedisulfonic acid, benzenesulfonic acid, alkylbenzenesulfonic acid, paratoluenesulfonic acid, melamine zinc iodide (melamine ZnI ₂ ), melamine trisulfonic acid (melamine trisulfonic acid), methyl ... acid; MTSA), cumenesulfonic acid, dodecylbenzenesulfonic acid, naphthalenesulfonic acid, nonylnaphthalenesulfonic acid, methyl acid phosphate, ethyl acid phosphate, propyl acid phosphate, isopropyl acid phosphate, butyl acid phosphate, butoxyethyl acid phosphate, octyl acid phosphate, 2-ethylhexyl acid phosphate, decyl acid phosphate, lauryl acid phosphate, stearyl acid phosphate, oleyl acid phosphate, behenyl acid phosphate, phenyl acid phosphate, nonylphenyl acid phosphate, cyclohexyl acid phosphate, phenoxyethyl Examples of suitable acid catalyst components include, but are not limited to, organic acids such as bisphenol A acid phosphate, alkoxypolyethylene glycol acid phosphate, bisphenol A acid phosphate, dimethyl acid phosphate, diethyl acid phosphate, dipropyl acid phosphate, diisopropyl acid phosphate, dibutyl acid phosphate, dioctyl acid phosphate, di-2-ethylhexyl acid phosphate, dilauryl acid phosphate, distearyl acid phosphate, diphenyl acid phosphate, and bisnonylphenyl acid phosphate; and thermal acid generators such as sulfonium salts, benzothiazolium salts, ammonium salts, and phosphonium salts. The acid catalyst components may be used singly or in combination of two or more.

In one aspect, the weight ratio of component (B) to acid catalyst may be 100:5 to 100:30, 100:10 to 100:20, or 100:10 to 100:15, or may be a weight ratio between the upper and lower limits recited above. If the amount of acid catalyst used is too low below the minimum weight ratio, the curing reaction will not occur sufficiently. If an excessive amount is used above the maximum weight ratio, over-curing will occur. In both cases, poor stability over time may result. Therefore, to achieve excellent stability over time, it is best for the weight ratio of component (B) to acid catalyst to satisfy the above range.

7. Solvents

In one aspect, the release coating composition may be a water-based release coating composition. In one aspect, water-based may refer to an aqueous solution or dispersion, and may refer to a composition in which the solvent component is water alone or a combination of water and an organic solvent, as described below.

In one aspect, because the aqueous release coating composition is water-based, it can drastically reduce volatile organic compound (VOC) emissions when forming a release layer, thereby meeting environmentally friendly requirements. It can also be easily used by mixing with aqueous additives such as aqueous antistatic agents, and has the advantage of being able to achieve both antistatic properties and releasability in the release film with a one-component formulation.

In one aspect, the release coating composition may further comprise an aqueous solvent. The aqueous solvent may be water or a combination of water and an organic solvent. The weight ratio of water to organic solvent may be 50:50 or more, 60:40 or more, 70:30 or more, 80:20 or more, 85:15 or more, 90:10 or more, 95:5 or more, or 99:1 or more.

In one aspect, the organic solvent may be a known organic solvent widely used in the field of release films, and is not particularly limited as long as it is a solvent that is compatible with water. For example, the organic solvent may be one or more selected from the group consisting of isopropyl alcohol, isobutyl alcohol, hexane, acetone, ethyl acetate, ethylene glycol, propylene glycol, butyl glycol, dipropylene glycol, polyethylene glycol, gamma-butyrolactone, and combinations thereof, but is not limited thereto.

8. Other ingredients

In one aspect, the release coating composition may further include one or more of an antistatic agent, a conductivity enhancer, a pH adjuster, a surfactant, and an antifouling agent, provided that the desired physical properties (e.g., frame) of the release layer are not altered.

(1) Antistatic agents and conductivity enhancers

In one aspect of the present disclosure, the antistatic agent not only imparts antistatic properties to the release layer, but also has the effect of preventing the adsorption of foreign matter. The ceramic green sheet manufacturing process includes a step of cutting and shredding the ceramic green sheet. During this step, the ceramic green sheet is in the form of a collection of beads like particle particles, so the beads fall off during the cutting process. Therefore, the antistatic property can prevent the beads from falling off due to static electricity during the process of cutting the release film together with the ceramic green sheet, thereby contributing to the processability of the ceramic green sheet manufacturing process.

In one aspect, the antistatic agent may be a known antistatic agent widely used in the field of release films, and is not particularly limited. For example, the antistatic agent may be selected from the group consisting of PEDOT (Poly(3,4-ethylenedioxythiophene)), PEDOT:PSS (poly(3,4-ethylenedioxythiophene) polystyrene sulfonate), polyaniline, polypyrrole, quaternary ammonium salts, sulfonates, and phosphates, but is not limited thereto.

In one aspect, the antistatic agent may be included in the release coating composition in the form of an aqueous solution containing the antistatic agent component as a solid (the solid content may be 1.0% to 2.0%, or 1.5% to 2.0%). In this case, the content of the aqueous solution containing the antistatic agent may be about 0.1 to about 30 wt %, about 1 to about 25 wt %, or about 5 to about 20 wt %, based on the total weight of the entire composition, and may be a content between the upper and lower limits recited above. If the content of the antistatic agent is used in an excessive amount exceeding the maximum value, it may cause defects in the appearance of the release layer, and such defects may be seen as blue spots.

In one aspect, the antistatic agent is present in the above amount, and can impart a surface resistivity of about 10 ⁴ to 10 ¹⁰ ohm/sq to the release layer.

In one aspect, the release coating composition can further include a conductivity enhancer to achieve the desired level of surface resistance, i.e., antistatic performance. Such a conductivity enhancer can complement the performance of the antistatic agent, and by using a conductivity enhancer, the desired level of surface resistance of the release layer can be achieved even with a smaller amount of antistatic agent.

In one aspect, the content of the conductivity enhancer may be about 1 to 20 wt %, about 1 to 15 wt %, about 1 to 10 wt %, about 1 to 8 wt %, about 1.5 to 8 wt %, about 1.5 to 6 wt %, about 2 to 6 wt %, about 2.5 to 6 wt %, about 3 to 6 wt %, or about 4 to 6 wt %, based on the total weight of the entire composition. If the content of the conductivity enhancer is used in an excessive amount exceeding the maximum value, it may hinder curing of the release layer, and the appearance and rub-off characteristics of the release layer may not be achieved to the desired level. If the content of the conductivity enhancer is used too little, below the minimum value, the effect may be insufficient.

In one aspect, the conductivity enhancer may be a known conductivity enhancer that has been widely used in the field of release films, and is not particularly limited. For example, the conductivity enhancer may be selected from the group consisting of ethylene glycol, dimethyl sulfoxide, N-methyl-2-pyrrolidone, propylene glycol, butyl glycol, dipropylene glycol dimethyl ether, gamma-butyrolactone, sulfolane, dimethyl carbonate, and sorbitol, but is not limited thereto.

(2) pH adjuster

In one aspect of the present disclosure, the pH adjuster can adjust the pH of the entire composition to a desired level. The release coating composition may contain an acidic antistatic agent. When the composition becomes acidic, neutral or basic components such as surfactants or silicone emulsion components may not function properly, making pH adjustment necessary. If the pH of the entire release coating composition is not adjusted, the stability of the composition over time may rapidly deteriorate, and the appearance of the release layer may deteriorate over time after preparation. For example, if a release coating composition is prepared and immediately applied to a substrate film to form a release layer, the appearance may be good. However, if the release layer is formed approximately four hours after preparation, the appearance of the release layer may become mottled.

In one aspect, the pH adjuster may be a known pH adjuster widely known in the field of release films, and is not particularly limited. For example, the pH adjuster may be one or more selected from the group consisting of sodium hydroxide, potassium hydroxide, calcium hydroxide, and aqueous ammonia, but is not limited thereto. The pH adjuster may be a basic pH adjuster.

In one aspect, the content of the pH adjuster may be 0.05 to 0.3 wt %, 0.1 to 0.3 wt %, or 0.15 to 0.25 wt %, based on the total weight of the entire composition, and may be a content between the upper and lower limits recited above. If the pH adjuster is used in an excessive amount exceeding the maximum value, it may interfere with curing of the release layer.

(3) Surfactants

In one aspect of the present disclosure, the surfactant can improve the wetting properties of the release coating composition or its applicability to a substrate film, and can also improve the compatibility between component (B) and the silicone emulsion component. In one aspect, when water is used as the sole solvent in the aqueous release coating composition, two or more different surfactants can be used.

In one aspect, the surfactant may be a component capable of lowering surface tension, such as a known surfactant widely known in the field of release films, and is not particularly limited. For example, the surfactant may be, but is not limited to, a cationic surfactant, an anionic surfactant, an amphoteric surfactant, a nonionic surfactant, a silicone surfactant, a modified silicone surfactant, a fluorine-containing surfactant, or a combination thereof.

In one aspect, the cationic surfactant may be, for example, but not limited to, an alkyltrimethylammonium salt, a dialkyldimethylammonium salt, or an alkylbenzyldimethylammonium salt.

In one aspect, the anionic surfactant may be, for example, but not limited to, a fatty acid salt, an alkylbenzene sulfonate, an alkyl sulfonate, an alkyl ether sulfonate ester salt, an alkyl polyoxyethylene sulfonate, or a monoalkyl phosphate.

In one aspect, the amphoteric surfactant may be, for example, but not limited to, alkyldimethylamine oxide or alkylcarboxybetaine.

In one aspect, the nonionic surfactant may be, for example, fatty acid ethanolamide, polyoxyethylene alkyl ether, polyoxyethylene alkylphenyl ether, sorbitol, sorbitan, sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene fatty acid ester, glycerin fatty acid ester, propylene glycol fatty acid ester, or polyoxyalkylene-modified silicone, but is not limited to these.

In one aspect, the silicone surfactant may be, for example, a polyether-modified silicone or a polyglycerin-modified silicone, but is not limited to these. The structure of such modified silicones may be classified into side chain modified type, both end modified type (ABA type), one end modified type (AB type), both end side chain modified type, linear block type (ABn type), branched type, etc., and modified silicones of any of these structures may be used.

In one aspect, the fluorosurfactant may be one or more selected from the group consisting of fluorine, fluorine-containing silane compounds, and fluorine-containing organic compounds, but is not limited to these.

In one aspect, the surfactant content may be 0.05 to 0.2 wt %, 0.1 to 0.2 wt %, or 0.15 to 0.2 wt %, based on the total weight of the entire composition, and may be a content between the upper and lower limits recited above.

(4) Antifouling agent

In one aspect of the present disclosure, the antifouling agent can adjust the surface energy of the release layer and impart antifouling properties. If the difference in surface energy between the substrate film and the release layer is small, the wettability and peelability of the release layer relative to the substrate film may decrease; however, the antifouling agent can prevent this by lowering the surface energy of the release layer. Furthermore, because component (B) contained in the release coating composition of the present disclosure has almost no slip properties (sliding characteristics), the antifouling agent can impart slip properties to the release layer.

In one aspect, the antifouling agent may be one or more selected from the group consisting of fluorine, fluorine-containing silane compounds, and fluorine-containing organic compounds, but is not limited to these.

For example, the antifouling agent may not contain self-emulsifying silicone. Because self-emulsifying silicone is not sufficiently soluble in water, if it contains such a compound, it may be difficult to use it as a water-based solvent. Therefore, the release coating composition according to the present disclosure may contain a silicone emulsion component but may not contain self-emulsifying silicone.

In one aspect, the content of the antifouling agent may be 0.1 to 0.3 wt %, 0.15 to 0.25 wt %, or 0.2 to 0.25 wt %, based on the total weight of the entire composition, and may be a content between the upper and lower limits recited above. If the amount of antifouling agent is used in an amount that is excessively less than the minimum value, problems may occur in which stains remain when the release film is peeled off, and problems may occur in which green sheet slurry particles remain on the release layer after the release film is peeled off from the green sheet.

[Example]

1. Preparation of release coating composition

The following components were mixed to prepare a release coating composition. However, the content of the silicone emulsion component was varied relative to 100 parts by weight of component (B) as shown in Table 1.

- Component (B) (melamine component) (Manufacturer: SANWA CHEMICAL, Product Name: NIKALAC MW12LF) 0.1-3.0% by weight

- Silicone emulsion component (PDMS, manufacturer: DOW Chemical, product name: Sol-off 7946 Emulsion) 0.01 to 26.4% by weight

- Acid catalyst (melamine catalyst) (Manufacturer: Allnex, Product name: Cymel® 4040 Catalyst) 0.1 to 3.0% by weight

- Platinum catalyst (manufacturer: DOW Chemical, product name: Syl-off 7924) 0.01 to 24.0% by weight

- PEDOT aqueous solution (manufacturer: Heraus, product name: Clevios PT2) 0.5 to 20% by weight

- 9% aqueous ammonia (manufacturer: Tokusan Pharmaceutical Co., Ltd.) 0.1-0.5% by weight

- Surfactant (manufacturer: BYK, product name: BYK348) 0.01 to 0.3% by weight

- Distilled water remaining

2. Release film manufacturing

The release coating composition thus produced was applied to at least one side of a 50 μm thick polyethylene terephthalate substrate film (manufacturer: Toray Advanced Materials, product name: XD500) using a bar coater, and then cured by heating and drying in a hot air dryer at 150°C for 30 seconds, producing a release film with a release layer provided on the substrate.

[Comparative Example]

1. Preparation of release coating composition

The release coating compositions were prepared in the same manner as in the Examples, except that in Comparative Example 1 the silicone emulsion component was omitted, and in Comparative Examples 2 to 5 the silicone emulsion component was included in the same amount as in Examples 1, 4, 6, and 7, respectively, but the melamine component was omitted. In Comparative Examples 6 and 7, instead of including the silicone emulsion component, a PEG-based silicone emulsion component (manufacturer: Silicone DNA, product name: SD-3667) was included in different amounts per 100 parts by weight of the melamine component, as shown in Table 1.

2. Release film manufacturing

A release film provided with a release layer was prepared using the comparative release coating composition in the same manner as in the previous example.

[Experimental Example 1] Measurement of green sheet peel strength and stability over time

50 parts by mass of barium titanate (BaTiO ₃ ; manufactured by Sakai Chemical Industry Co., Ltd., product name: BT-03), 5 parts by mass of polyvinyl butyral (manufactured by Sekisui Chemical Co., Ltd., product name: S-LEC B·KBM-2), and 2 parts by mass of dioctyl phthalate (manufactured by Kanto Chemical Co., Ltd., product name: Dioctyl Phthalate Grade 1) were added to 69 parts by mass of toluene and 46 parts by mass of ethanol, and the mixture was mixed and dispersed in a ball mill to produce a ceramic slurry.

In the examples and comparative examples, the release films were stored at room temperature for 48 hours after production, and the ceramic slurry was then uniformly applied to the surface of the release layer using an applicator. The films were then dried in a dryer at 80°C for 1 minute. Finally, a ceramic green sheet with a thickness of 3 μm was obtained on the release film, and a release film with a ceramic green sheet attached was manufactured.

The release film with the ceramic green sheet attached was stored at a room temperature of 23°C and a humidity of 50% for 24 hours and 90 days. After that, acrylic adhesive tape (manufactured by Nitto Denko Corporation, product name: 31B tape) was adhered to the side of the ceramic green sheet opposite the release film, and the sheet was cut to a width of 25 mm to prepare the measurement sample.

The adhesive tape side of such a measurement sample was fixed to a flat plate, and then the release film was peeled off from the ceramic green sheet using a tensile tester (ChemInstrument's AR-1000) at a 90° peel angle and a peel rate of 500 mm/min to measure the peel force (gf/25 mm). The average value of the results of five measurements is shown in Table 1.

[Experimental Example 2] Tape Peel Force Measurement

The release strength of the release films prepared by applying the release coating compositions prepared in the examples and comparative examples was evaluated using TESA 7475 tape (manufactured by TESA, Germany), a standard tape widely used in the technical field of the present disclosure.

Standard TESA 7475 tape was applied to the release coating surface of the release layer using a 2 kg roller, and the peel force was measured after 20 minutes at room temperature or after 24 hours at room temperature. The peel force was measured five times using a ChemInstrument AR-1000 device at a 180° peel angle and a peel speed of 12 in/min, and the average value was calculated.

[Experimental Example 3] Silicone content measurement

The silicone content in the release layers of the release films produced in the above examples and comparative examples was measured using an X-ray fluorescence analyzer (XRF) (manufactured by OXFORD, product name: LAB X-3500).

[Experimental Example 4] Measurement of residual adhesion rate

The release film measurement samples prepared in the examples and comparative examples were stored at 25°C and 65% RH for 24 hours, and then a standard Nitto 31B tape was attached to the release coating surface and the sample was pressed at room temperature with a load of 20 g/ ^cm for 24 hours. The tape attached to the release coating surface was recovered without contamination and then attached to a polyethylene terephthalate (PET) film surface with a flat and clean surface. The tape was pressed back and forth once with a 2 kg tape roller, and the peel force was measured.

For comparison, a new Nitto 31B tape was adhered to a flat, clean PET film surface, and then pressed back and forth once with a 2 kg tape roller, after which the peel force was measured.

The peel force was measured as follows, and the residual adhesion rate was calculated using Equation 1.

Measuring equipment: ChemInstrument AR-1000 instrument

Measurement method: 180° peel angle, peel speed 30 mm/min

<Math 1>

Residual adhesion rate (%) = [peel strength of adhesive tape adhered to the surface of a release layer and then peeled off / peel strength of adhesive tape not in contact with the surface of a release layer] x 100

[Experimental Example 5] Surface Energy Measurement

Distilled water and methylene iodide were dropped onto the release coating surface of the release films prepared in the examples and comparative examples using a contact angle measuring device (manufactured by KRUSS, product name: DSA-100) to measure the contact angle for each. The measured contact angle values were then substituted into the Owens-Wendt model to calculate the surface energy.

[Experimental Example 6] Rub-off test

The release layers of the release films manufactured in the above examples and comparative examples were rubbed back and forth with a thumb 10 times, and the degree of change in the surface of the release layer was then observed with the naked eye. As a result, the rub-off characteristics were evaluated as follows:

◎: No change after evaluation

○: There is slight rubbing, but no problems with use.

△: The release layer surface has turned white.

X: If the release layer peels off

The results obtained from the above experimental example are listed in Table 1 below.

As shown in Table 1, the release film obtained using the release coating composition according to one aspect of the present disclosure exhibited superior residual adhesion and rub-off properties compared to the comparative example, while also achieving a wide range of room temperature one-day tape peel strength. Therefore, it has the advantage of being useful in a variety of industrial fields. Furthermore, its excellent residual adhesion and rub-off properties confirm that low-temperature curing is possible. Comparative Examples 2 to 5, which are release films containing silicone-based release coating compositions conventionally used in the art, exhibited poor residual adhesion and surface energy, and very poor rub-off properties. In other words, silicone emulsion alone exhibited low residual adhesion and poor rub-off properties, making low-temperature curing difficult. Meanwhile, in the examples, the combination of melamine and silicone emulsion components improves insufficient curing power while enhancing release properties through the silicone emulsion. This is because silicone emulsions have a large molecular weight and typically have two to three reactive sites, one at each end of the molecule, making low-temperature curing difficult. Meanwhile, melamine has a low molecular weight monomer and can have up to six reactive sites, making it highly reactive. This allows for excellent rub-off properties that were difficult to achieve with existing silicone-based release coating compositions.

When the peel strength of a green sheet according to one aspect of the present disclosure was measured 90 days after production, it exhibited a peel strength that was nearly the same as that measured on the first day after production, demonstrating excellent stability over time.

Furthermore, it was confirmed that examples according to one aspect of the present disclosure exhibit a residual adhesion rate of at least 94% or more.

[Experimental Example 7] FT-IR Spectroscopy

FT-IR spectra were measured for release layers prepared using the release coating composition of Example 1 and a conventional silicone-based release coating composition containing a self-emulsifying silicone. Specifically, using a Bruker VERTEX 70 device, the release coating compositions of the example and comparative examples were applied to a glass plate and cured by heating and drying in a hot air oven at 150°C for 30 seconds. 0.1 g of the coating layer was then sampled with a ceramic knife and the spectrum was measured using the ATR method on the measuring device. The FT-IR spectrum measurement results are shown in Figure 3.

3, the release layer of the present disclosure exhibits high absorption peak intensities in these regions due to the influence of the Si—O stretching absorption bands at about 1020 cm ⁻¹ and about 1090 cm ⁻¹ and the Si—C stretching absorption band at about 800 cm ⁻¹ . These peak intensities can be interpreted as indicating the presence of components derived from PDMS in the release layer.

Claims (15)

a base film; and a release layer formed by applying a release coating composition to at least one surface of the base film;
the release coating composition comprises a melamine component and a silicone emulsion component, the silicone emulsion component does not comprise a side chain;
In a depth profile measured from the surface of the release layer in the thickness direction using a time-of-flight secondary ion mass spectrometer (TOF-SIMS), the maximum count number of NH ^- ions in the NH ^- ion intensity curve, the count number of NH ^- ions at the surface of the release layer, and the count number of NH ^- ions at the boundary between the release layer and the substrate film are defined as I _{NH_max} , I _{NH_t} , and I _{NH_b} , respectively.
A release film, wherein the ratio of I _{NH_t} /I _{NH_max} is 0.90 or less, and I _{NH_t} >I _{NH_b} . 2. The release film according to claim 1, wherein the NH 3 ^- ionic strength curve includes an inflection point. 2. The release film according to claim 1, wherein the NH 3 ^- ionic strength curve has a concave shape. 10. The release film of claim 1, wherein the substrate film comprises polyethylene terephthalate polymer and the release layer further comprises one or more of Si ⁻ , S ⁻ , C ₇ H ₅ O ₂ ⁻ , and C ₃ H ₅ N ₅ ⁻ ions. the release layer comprises Si ^- ions and _C7H5O2 ^- _{ions ;}
In a depth profile measured by TOF-SIMS from the surface of the release layer in the thickness direction, the ion intensity of Si ⁻ decreased and the ion intensity of C ₇ H ₅ O ₂ ⁻ increased.
5. The release film according to claim 4, wherein the release layer includes a portion where the ionic strength of the Si ^ions and the ionic strength of the C ₇ H ₅ O ₂ ^ions are the same. the release layer contains S ^- ions,
5. The release film according to claim 4, wherein in a depth profile measured using TOF-SIMS from the surface of the release layer in the thickness direction, an S ⁻ ion intensity curve includes an inflection point. 7. The release film according to claim 6, wherein the ^S.sub.2- ionic strength curve has a concave shape. the release layer contains C ₃ H ₅ N ₅ ^- ions;
5. The release film according to claim 4, wherein in a depth profile measured using TOF-SIMS from the surface of the release layer in the thickness direction, the ionic strength of C ₃ H ₅ N ₅ ^- decreases at a position adjacent to the surface of the release layer. The release film according to claim 1, which exhibits an instant tape peel strength of 5 to 32 gf/in. The release film according to claim 1, which exhibits a tape peel strength of 3 to 1000 gf/in after one day at room temperature. The release film according to claim 1, which exhibits a green sheet peel strength of 1 to 3 gf/in. 2. The release film according to claim 1, wherein the release layer has a silicone content of 0.001 to 0.2 g/ ^m2 as measured using an X-ray fluorescence analyzer (XRF). The release film according to claim 1, wherein the surface energy of the release layer is 19 to 30 dyne/cm. The release film according to claim 1, comprising a release layer formed by curing the release coating composition at a temperature of 150°C or less. a silicone emulsion component (A) containing polydimethylsiloxane (PDMS);
2. The release film according to claim 1, which is an aqueous release coating composition comprising: a component (B) containing, in one molecule, two or more functional groups capable of undergoing a condensation reaction with the silicone emulsion component; and an acid catalyst.