Thermosetting release coating composition and laminate

Abstract

One aspect of the present invention is a heat-curable release coating agent composition including an alkyl etherified melamine resin (A) and an acid catalyst (B), wherein an ethyl ether group is included as an alkyl ether group that is included in the alkyl etherified melamine resin (A), and the weight average molecular weight of the alkyl etherified melamine resin (A) is 500-1,100.

Description

[Technical Field]

[0001] One aspect of the present invention relates to a thermosetting release coating composition containing an alkyl-etherified melamine resin (A), and a laminate comprising a cured product layer formed from the thermosetting release coating composition. [Background technology]

[0002] Among release coating agents, melamine resins have been used as one of the components in applications requiring heat resistance, such as release films for ceramic green sheets, because of their excellent heat resistance, curability and cost. Melamine resins are often used as alkyl etherified melamine resins, which are prepared by modifying melamine with various alcohols after adding formaldehyde to the melamine, in order to control polarity, storage stability, reactivity, and the like. For example, a release film for use in the production process of a ceramic green sheet, which has a release layer containing a methyl-etherified melamine resin (methylated melamine resin) as the melamine resin, has been studied (see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2019-166706 Summary of the Invention [Problem to be solved by the invention]

[0004] As mentioned above, methyl-etherified melamine resins modified with methanol have excellent curing properties and have therefore been widely used as the main component of release coating agents. However, due to the high polarity of the methyl ether group, they can absorb moisture from the air during coating under high humidity conditions, which can lead to poor coating appearance, such as whitening of the coating film (cured coating film) obtained by curing the coating layer. In particular, in recent years, with the globalization of release film manufacturing bases, there has been an increase in production opportunities in regions with high humidity (temperature), and the decline in productivity caused by the above-mentioned problems has become an urgent issue, creating a demand for release coating agents with low humidity dependency. Furthermore, methyl etherified melamine resins require curing at relatively high temperatures (e.g., 120°C) to demonstrate their properties. However, in light of social conditions such as global warming, there is an increasing demand every year for lower temperature curing to reduce carbon dioxide emissions. This has led to a demand for melamine resins to be able to demonstrate the various properties required of them even when cured at temperatures lower than the conventional curing temperatures (e.g., 120°C) (e.g., 80°C).

[0005] One aspect of the present invention is a thermosetting release coating composition containing an alkyl etherified melamine resin, which when cured inhibits coating film appearance defects such as whitening, has excellent properties such as adhesion and solvent resistance even when cured at low temperatures, and also has excellent storage stability. Things The objective is to provide [Means for solving the problem]

[0006] As a result of investigations, the present inventors have found that the above problems can be solved by a thermosetting release coating composition containing a specific alkyl etherified melamine resin and an acid catalyst.

[0007] That is, one aspect of the present invention includes the following. [1] A thermosetting release coating composition comprising an alkyl etherified melamine resin (A) and an acid catalyst (B), A thermosetting release coating composition, wherein the alkyl etherified melamine resin (A) contains an ethyl ether group as the alkyl ether group, and the weight average molecular weight of the alkyl etherified melamine resin (A) is 500 to 1,100. [2] The alkyl ether group contained in the alkyl etherified melamine resin (A) further contains a methyl ether group, The thermosetting release coating composition according to [1], wherein the molar ratio of methyl ether groups to ethyl ether groups, (methyl ether groups) / (ethyl ether groups), is 90 / 10 or less. [3] The thermosetting release coating composition according to [1] or [2], wherein the alkyl etherified melamine resin (A) has an average molar ratio of alkyl ether groups to 1 mole of triazine rings of 3 to 6. [4] The thermosetting release coating composition according to any one of [1] to [3], wherein the acid catalyst (B) is paratoluenesulfonic acid. [5] The thermosetting release coating composition according to any one of [1] to [4], further comprising a release component (C). [6] The thermosetting release coating composition according to any one of [1] to [5], wherein the concentration of biomass-derived carbon (C14) in the total organic carbon contained in the alkyl etherified melamine resin (A) is 20 to 100%. [7] Archi Rue TEL transformation The thermosetting release coating composition according to any one of [1] to [6], wherein the content of the melamine resin (A) is 10 to 99 parts by weight per 100 parts by weight of the solid content contained in the thermosetting release coating composition. [8] A laminate having a cured material layer on at least one surface of a substrate, the cured material layer being formed from the thermosetting release coating composition according to any one of [1] to [7]. [9] The laminate according to [8], wherein the substrate is polyethylene terephthalate.

[10] The laminate according to [9], wherein the substrate is untreated polyethylene terephthalate. [Effects of the Invention]

[0008] A thermosetting release coating agent containing an alkyl etherified melamine resin according to one aspect of the present invention composition The coating film obtained by applying and curing the agent is inhibited from exhibiting poor appearance such as whitening, and has excellent properties such as adhesion and solvent resistance even when cured at low temperatures. composition It also has excellent storage stability. DETAILED DESCRIPTION OF THE INVENTION

[0009] [Thermosetting Release Coating Composition] A thermosetting release coating composition according to one embodiment of the present invention contains an alkyl etherified melamine resin (A) and an acid catalyst (B).

[0010] <Alkyl etherified melamine resin (A)> The thermosetting release coating composition according to one embodiment of the present invention contains an alkyl-etherified melamine resin (A). Here, the melamine resin is a resin obtained from raw materials containing melamine and formaldehyde, and an example of such a resin is an alkyl-etherified melamine resin, which is a resin obtained from raw materials containing melamine, formaldehyde, and an alcohol used in the alkyl-etherification.

[0011] The alkyl etherified melamine resin (A) contains an ethyl ether group as the alkyl ether group contained in the resin. By containing an ethyl ether group as the alkyl ether group in the alkyl etherified melamine resin, appearance defects of the coating film (cured coating film) obtained by applying and curing a thermosetting release coating composition containing the alkyl etherified melamine resin (A) are suppressed, and adhesion to the substrate and storage stability at low temperatures are improved.

[0012] From the viewpoint of suppressing the appearance defects of the coating film (cured coating film) obtained from the thermosetting release coating composition according to one embodiment of the present invention and further improving the solvent resistance, it is preferred that the alkyl-etherified melamine resin (A) further contains a methyl ether group.

[0013] When the alkyl etherified melamine resin (A) contains ethyl ether groups and methyl ether groups, the molar ratio of methyl ether groups to ethyl ether groups (methyl ether groups) / (ethyl ether groups) is preferably 90 / 10 or less, more preferably 50 / 50 or less, and even more preferably 30 / 70 or less, in order to improve solvent resistance. When an ethyl ether group and a methyl ether group are contained, the molar ratio (methyl ether group) / (ethyl ether group) is usually 5 / 95 or more.

[0014] From the viewpoint of more significantly exhibiting the effects of the present invention, the total content of ethyl ether groups and, if necessary, methyl ether groups relative to all alkyl ether groups contained in the alkyl etherified melamine resin (A) is preferably 80 to 100 mol%, more preferably 90 to 100 mol%. From the same viewpoint, it is preferable that all alkyl ether groups consist of only ethyl ether groups or only ethyl ether groups and methyl ether groups, and more preferably only ethyl ether groups and methyl ether groups.

[0015] The type of alkyl ether group contained in the alkyl etherified melamine resin (A), and when multiple alkyl ether groups are contained, their contents and molar ratios can be determined by gas chromatography mass spectrometry (GC). The alcohol (e.g., ethanol or methanol) detected by the measurement is derived from the alkyl ether groups of the alkyl-etherified melamine resin (A), and therefore the number (moles) of alkyl ether groups contained in the alkyl-etherified melamine resin (A) can be determined from the calculated amount of alcohol generated.

[0016] The alkyl-etherified melamine resin (A) has a weight-average molecular weight (Mw) of 500 to 1,100, preferably 600 to 1,100, as measured by GPC (gel permeation chromatography) in terms of polystyrene. Having a weight-average molecular weight within this range not only improves solvent resistance but also suppresses the appearance defects of a coating film (cured coating film) obtained from the thermosetting release coating composition, and provides excellent adhesion between the coating film obtained from the thermosetting release coating composition and a substrate, even when cured at relatively low temperatures. Furthermore, the storage stability of the thermosetting release coating agent at low temperatures is excellent.

[0017] From the viewpoint of improving the solvent resistance of the coating film (cured coating film) obtained from the thermosetting release coating composition of the present invention, the average molar ratio of alkyl ether groups contained in the alkyl-etherified melamine resin (A) to 1 mole of triazine rings, which are the melamine skeleton components, is preferably 3 to 6, and more preferably 4 to 6. If the average molar ratio of alkyl ether groups to 1 mole of triazine rings is less than 3, the crosslink density will be insufficient, and there is a concern that the solvent resistance will decrease.

[0018] The molar number of the alkyl ether group and the triazine ring of the alkyl etherified melamine resin (A) can be determined by the nuclear magnetic resonance spectrum ( 13 It can be determined by C-NMR.

[0019] From the viewpoint of reducing the use of raw materials derived from fossil fuels and producing a resin that can contribute to environmental conservation, the concentration of biomass-derived carbon (C14) in the total organic carbon of the alkyl etherified melamine resin (A) is preferably 20 to 100%, more preferably 30 to 100%.

[0020] The concentration of biomass-derived carbon (C14) in the alkyl etherified melamine resin (A) was determined based on the American Standard for Testing Materials (ASTM D6866 Method B). The calculation method will be described in detail in the Examples below.

[0021] The content of the alkyl etherified melamine resin (A) in the thermosetting release coating composition according to one embodiment of the present invention is preferably 10 to 99 parts by weight, more preferably 50 to 98 parts by weight, per 100 parts by weight of the solid content of the composition.

[0022] The method for producing the alkyl-etherified melamine resin (A) is not particularly limited as long as it can produce a resin that satisfies the requirements. The method for producing the alkyl-etherified melamine resin (A) preferably includes, for example, a step of first carrying out a methylolation reaction using melamine and formaldehyde, followed by an alkyl-etherification reaction, and more preferably includes a step of charging melamine, formaldehyde, and an alcohol into a reaction vessel, heating the mixture to a reflux temperature, and then carrying out a condensation reaction of the three components using an acid as a catalyst.

[0023] 〔melamine〕 The melamine is not particularly limited, and may be obtained by synthesis using a conventionally known method, or may be a commercially available product.

[0024] [Formaldehyde] The formaldehyde may be in the form of an aqueous solution or solid paraformaldehyde. From the viewpoint of economic efficiency, paraformaldehyde having a formaldehyde concentration of 80% or more is preferred.

[0025] The amount of formaldehyde used is preferably 3 to 12 moles, more preferably 4 to 10 moles, per mole of melamine used. When the amount of formaldehyde used is within the above range, the alkyl-etherified melamine resin (A) used in the present invention can be produced efficiently.

[0026] 〔alcohol〕 In the above step, ethanol can be used as the alcohol to produce an ethyl-etherified melamine resin. The use of this ethyl-etherified melamine resin prevents the coating film (cured coating film) obtained from the thermosetting release coating composition from having poor appearance, and the coating film obtained from the thermosetting release coating composition has excellent adhesion to the substrate, even when cured at a relatively low temperature.

[0027] Here, if methanol is used as the alcohol, a methyl-etherified melamine resin can be obtained, but this tends to lead to poor appearance of the coating film (cured coating film).On the other hand, if butanol is used as the alcohol, a butyl-etherified melamine resin can be obtained, which is less likely to lead to poor appearance of the coating film (cured coating film), but the crosslinking reaction is slow, which is thought to tend to reduce the solvent resistance of the resulting cured product.

[0028] The amount of ethanol used is preferably 3 to 20 moles, more preferably 5 to 12 moles, relative to 1 mole of the melamine used. When the amount of ethanol used is within the above range, the alkyl etherified melamine resin (A) used in the present invention can be produced efficiently and inexpensively.

[0029] In addition, as long as it does not impair the object of the present invention, ethanol and a small amount of C n H 2n+1 A mixture with other alcohols represented by OH (n is 1 or an integer of 3 to 8) may also be used. From the viewpoint of economic efficiency and coating film (cured coating film) performance, n is preferably 1, 3 or 4.

[0030] <Acid catalyst (B)> The thermosetting release coating composition of the present invention further contains an acid catalyst (B), which allows the above-mentioned condensation (crosslinking) reaction of the melamine resin to proceed efficiently.

[0031] As the acid catalyst (B), either an organic acid or an inorganic acid can be used. Examples of organic acids include formic acid, oxalic acid, methanesulfonic acid, paratoluenesulfonic acid, dodecylbenzenesulfonic acid, and alkylphosphoric acid. Examples of inorganic acids include phosphoric acid, phosphorous acid, hydrochloric acid, sulfuric acid, nitric acid, and hydrobromic acid.

[0032] Among the acid catalysts (B), organic acids are preferred, with paratoluenesulfonic acid, methanesulfonic acid, and dodecylbenzenesulfonic acid being more preferred, and paratoluenesulfonic acid being particularly preferred. These have high acidity and excellent reactivity, allowing the release layer to be processed at lower temperatures. This can prevent the film from losing flatness due to heat during processing and the appearance of the film after winding from being deteriorated.

[0033] The content of the acid catalyst (B) in the thermosetting release coating composition of the present invention is preferably 1 to 10 parts by weight, more preferably 3 to 8 parts by weight, per 100 parts by weight of the alkyl etherified melamine resin (A). When the content of the acid catalyst (B) is within this range, the curing reaction proceeds efficiently, and there is no risk of the acid catalyst migrating to an object (e.g., a ceramic green sheet described below) that is laminated with the cured layer (typically a release layer) obtained by curing the composition, resulting in excellent durability.

[0034] <Exfoliating component (C)> The thermosetting release coating composition according to one embodiment of the present invention preferably contains a release component (C). The release component (C) is not particularly limited as long as it can impart the desired release properties to the cured layer (release layer), and examples thereof include release polymer components such as polyorganosiloxane, silicone-modified acrylic resin, fluororesin, and acrylic resin. Among these, polyorganosiloxane is preferred. The release polymer components may be used alone or in combination or as a mixture.

[0035] In the thermosetting release coating composition according to one embodiment of the present invention, the release component (C) is preferably a release polymer component having one or more functional groups per molecule capable of chemically bonding with the alkyl-etherified melamine resin (A). Examples of such functional groups include alkoxy groups such as methoxy groups, hydroxy groups, amino groups, carboxyl groups, epoxy groups, thiol groups, and isocyanate groups. The release component (C) having such functional groups allows the release polymer component (e.g., polyorganosiloxane) to be fixed to the cured melamine product by a condensation reaction with the melamine resin. This prevents migration of components derived from the release component (C) to an object (e.g., a ceramic green sheet) laminated to the cured product layer (release layer) obtained by curing the thermosetting release coating composition. This prevents the tape from becoming too hard to release during storage and from losing its adhesive strength during use.

[0036] When the release component (C) is a polyorganosiloxane, its weight-average molecular weight (Mw) is preferably 1,000 or more and 10,000 or less, more preferably 9,000 or less, and particularly preferably 3,000 or more and 8,000 or less. When the weight-average molecular weight of the polyorganosiloxane is within the above range, the compatibility between the polyorganosiloxane and the melamine resin is improved, making it easier to form a release layer with excellent surface condition. It also makes it easier to adjust the surface free energy of the release surface within an appropriate range. As a result, it becomes easier to achieve both excellent release properties and excellent slurry coatability in the laminate (e.g., release film) according to one embodiment of the present invention.

[0037] Examples of the release component (C) include hydroxyl group-containing polyorganosiloxanes such as BYK-370, BYK-375, BYK-377, and BYK-SILCLEAN manufactured by BYK-Chemie Japan, x-22-4952 manufactured by Shin-Etsu Chemical Co., Ltd., and FM-4425 manufactured by JNC Corporation; and carboxyl group-containing polyorganosiloxanes such as x-22-162C and x-22-370 manufactured by Shin-Etsu Chemical Co., Ltd. 1E, x-22-3710, BY16-750, BY16-880 manufactured by Toray Dow Corning Co., Ltd.; mercapto group-containing polyorganosiloxanes such as x-22-167B manufactured by Shin-Etsu Chemical Co., Ltd.; amino group-containing polyorganosiloxanes such as x-22-161B manufactured by Shin-Etsu Chemical Co., Ltd.; and epoxy group-containing polyorganosiloxanes such as x-22-163B manufactured by Shin-Etsu Chemical Co., Ltd.

[0038] The content of the release component (C) in the thermosetting release coating composition according to one embodiment of the present invention is preferably 0.1 to 20 parts by weight, more preferably 0.5 to 10 parts by weight, per 100 parts by weight of the alkyl-etherified melamine resin (A). By having the content of the release component (C) within this range, it is easy to achieve the desired releasability for an object (e.g., a ceramic green sheet) on which a cured layer (release layer) obtained by curing the thermosetting release coating composition is laminated, and migration of polyorganosiloxane from the release layer to the object can be effectively suppressed.

[0039] <Solvent> The thermosetting release coating composition according to one embodiment of the present invention usually contains a solvent in consideration of its coatability, etc. Even when the thermosetting release coating composition contains a solvent, it has excellent storage stability even when stored at low temperatures, provided that it contains the alkyl etherified melamine resin (A) as the melamine resin.

[0040] The solvent is not particularly limited as long as it can dissolve the above-mentioned components. Examples of the solvent include hydrocarbon compounds such as toluene, xylene, hexane, and heptane; alcohol compounds such as methanol, ethanol, 1-butanol, isopropyl alcohol, and isobutyl alcohol; ketone compounds such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; ester compounds such as ethyl acetate and butyl acetate; and ether compounds such as diisopropyl ether and 4-dioxane. These may be used alone or in appropriate combinations of two or more. In one embodiment of the present invention, from the viewpoint of dissolving the release component (C), it is preferable to use toluene or methyl ethyl ketone, and it is more preferable to use toluene.

[0041] When the thermosetting release coating composition according to one embodiment of the present invention contains a solvent, the amount of the solvent added is preferably 420 to 1995 parts by weight, more preferably 595 to 1395 parts by weight, per 100 parts by weight of the alkyl etherified melamine resin (A), from the viewpoint of coatability.

[0042] <Other ingredients> The thermosetting release coating composition according to one embodiment of the present invention may contain other components within a range that does not impair the effects of the present invention. Examples of other components include additives such as binders, crosslinking agents, reaction inhibitors, adhesion improvers, slipping agents, antistatic agents, antioxidants, leveling agents, fillers, antifoaming agents, and pigments.

[0043] 〔binder〕 The binder is not particularly limited as long as it is a compound having two or more hydroxyl groups in one molecule (excluding the alkyl etherified melamine resin (A)), and various known binders can be used. Specific examples include aliphatic diols such as ethylene glycol, 2-methyl-1,3-propanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, neopentyl glycol, 2-methyl-1,5-pentanediol, 2,2-diethyl-1,3-propanediol, 1,9-nonanediol, 1,10-decanediol, butylethylpropanediol, and butylethylpentanediol; alicyclic diols such as 1,4-cyclohexanedimethanol; trimethylolpropane, pentaerythritol, ditrimethylolpropane, dipentaerythritol, dimerdiol, hydrogenated dimerdiol, trimertriol, hydrogenated trimertriol, castor oil, castor oil-based modified polyols, and alkylene oxide adducts of bisphenol compounds or derivatives thereof. Further examples include polymer polyols such as polyether polyols, polyester polyols, polycarbonate polyols, acrylic polyols, and polyolefin polyols, which may be used alone or in combination of two or more.

[0044] [Crosslinking agent] The crosslinking agent is not particularly limited as long as it is a compound having a functional group capable of bonding with a hydroxyl group, and various known crosslinking agents can be used. Specific examples include isocyanate-based curing agents, epoxy-based curing agents, aziridine-based curing agents, carbodiimide-based curing agents, oxazoline-based curing agents, etc. These may be used alone or in combination of two or more.

[0045] The binder and crosslinking agent can both be used to improve the curability of the thermosetting release coating composition of the present invention. There are no particular restrictions on the contents of the binder and crosslinking agent, as long as they are within a range that does not impair the effects of the present invention, as described above.

[0046] [Laminate, release film] The thermosetting release coating composition according to one embodiment of the present invention thus obtained is applied to a substrate to form a coating layer, and this coating layer is typically heated and cured to form a laminate comprising a cured layer (typically a release layer) which is a coating film obtained from the thermosetting release coating composition and a substrate. The laminate according to one embodiment of the present invention is suitably used as a release film.

[0047] <Base material> Examples of the substrate of the laminate (e.g., release film) include films made of polyesters such as polyethylene terephthalate (PET) and polyethylene naphthalate, polyolefins such as polypropylene and polymethylpentene, polycarbonate, polyvinyl acetate, and other plastics, and may be single-layer or multi-layered, consisting of two or more layers of the same or different materials. Among these, polyester films are preferred, and polyethylene terephthalate films are particularly preferred.

[0048] PET film is less likely to generate dust during processing and use, and can effectively prevent, for example, ceramic slurry coating defects due to dust. Furthermore, antistatic treatment of PET film can prevent ignition due to static electricity when applying ceramic slurries that use organic solvents, and can enhance the effectiveness of preventing coating defects. To improve adhesion between these substrates and the cured product layer (release layer), the substrate surface may be corona-treated, etched, or plasma-treated, or may be roughened by adding organic or inorganic particles, or may be coated with urethane or polyester. In this specification, substrates that have not undergone these treatments are referred to as "untreated" substrates. The substrate may be untreated, and the thermosetting release coating composition of the present invention has excellent adhesion to, for example, untreated PET film.

[0049] <Cured material layer, release layer> The cured layer (typically a release layer) of the laminate (e.g., a release film) can be formed by applying the thermosetting release coating composition according to one embodiment of the present invention to one side of a substrate and curing it, typically by heating. Because the cured layer (release layer) of this laminate is formed from the thermosetting release coating composition according to one embodiment of the present invention, it has excellent adhesion to the substrate (e.g., a PET film) even when cured at a relatively low temperature.

[0050] The thickness of the cured product layer (release layer) is preferably 0.01 μm or more, more preferably 0.03 μm or more, even more preferably 0.05 μm or more, and particularly preferably 0.1 μm or more. Furthermore, the thickness is preferably 2.0 μm or less, more preferably 1.0 μm or less, and even more preferably 0.5 μm or less. For example, when the laminate is used as a release film, a release layer having a thickness of 0.01 μm or more exhibits sufficient release properties from an object (e.g., a ceramic green sheet) to be laminated on the cured product layer (release layer). Furthermore, a cured product layer having a thickness of 2.0 μm or less can prevent blocking from occurring when the release film is wound into a roll. For example, when the release film is used to mold a ceramic green sheet, the curing time can be shortened, the flatness of the release film is maintained, and thickness unevenness of the resulting ceramic green sheet can be reduced.

[0051] Cured layer obtained from the thermosetting release coating composition according to one embodiment of the present invention surface It is desirable that the cured product layer (release layer surface) is flat. For example, when a laminate obtained from the composition is used as a release film to mold a ceramic green sheet, a flat cured product layer surface (release layer surface) can suppress defects such as pinholes and uneven thickness in the ceramic green sheet that is coated and molded on the cured product layer surface (release layer surface). When the cured product layer (release layer) is formed from a release agent composition containing a dispersant, the compatibility between the components contained in the release agent composition is improved, making it easier to satisfy the requirements.

[0052] <Preparation of laminate and release film> The method for applying the thermosetting release coating composition of the present invention to a substrate to produce a laminate (e.g., a release film) is not particularly limited as long as it is possible to form a layer of the coating on the substrate, and the laminate can be produced by known methods such as gravure coating, bar coating, spray coating, spin coating, knife coating, roll coating, and die coating.

[0053] A coating formed from the thermosetting release coating composition according to one embodiment of the present invention applied to a substrate is cured by removing volatile components (e.g., solvents) from the coating, and the solid components contained in the coating are formed into a cured layer (typically a release layer) of a laminate (release film). The coating amount is 0.01 to 100 g / m 2 is preferable, and 0.03 to 50 g / m 2 When forming a cured product layer (release layer) on both sides of the substrate, it is preferable to perform the operation of forming the cured product layer (release layer) as a cured product film on each side of the substrate.

[0054] The solid content of this thermosetting release coating composition is usually cured by heating. When the thermosetting release coating composition according to one embodiment of the present invention is used, the heating conditions for this curing can be lower than conventional ones. The heating temperature for curing the thermosetting release coating composition is preferably 60°C or higher and 140°C or lower, more preferably 80°C or higher and 120°C or lower. When curing at a relatively low temperature is desired, the temperature range of 70°C or higher and 90°C or lower can be selected for curing. The heating time for curing is preferably 0.5 minutes or higher and 5 minutes or lower, more preferably 1 minute or higher and 3 minutes or lower. As described above, the present invention allows for curing at a relatively low temperature, which is expected to reduce the amount of carbon dioxide generated during heating.

[0055] [Ceramic green sheet] The laminate thus obtained is suitable for use as a release film, which is suitable for use in the production process of ceramic green sheet films, which are used as raw materials for multilayer ceramic capacitor films, for example.

[0056] Multilayer ceramic capacitor films generally have the following configuration. A multilayer ceramic capacitor film has a rectangular parallelepiped ceramic body. In a multilayer ceramic capacitor film, first internal electrodes and second internal electrodes are typically provided alternately within the ceramic body along the thickness direction. The first internal electrodes are exposed at a first end face of the ceramic body, and a first external electrode is provided on the first end face of the ceramic body. The first internal electrodes are electrically connected to the first external electrode at the first end face. The second internal electrode is exposed at a second end face of the ceramic body. A second external electrode is provided on the second end face. The second internal electrode is electrically connected to the second external electrode at the second end face.

[0057] The ceramic green sheets that are the raw materials for such multilayer ceramic capacitor films can be produced using the release film as follows. First, a ceramic slurry containing a ceramic material such as barium titanate or titanium oxide is applied to the release surface of the release film. This application can be performed using, for example, a slot die coating method or a doctor blade method. Examples of binder components contained in the ceramic slurry include butyral resins and acrylic resins. Examples of solvents contained in the ceramic slurry include organic solvents and aqueous solvents. After the slurry is applied to the release surface, the applied ceramic slurry is dried to form a ceramic green sheet. Ultra-thin ceramic green sheets, typically with a thickness of 0.2 to 1.0 μm, are in demand.

[0058] The produced ceramic green sheets are printed with conductive layers for forming the first and second internal electrodes, and are used as the raw material for multilayer ceramic capacitor films. The multilayer ceramic capacitor can be manufactured by appropriately stacking and pressing these sheets to obtain a laminate, dividing it into multiple pieces, and firing it to obtain a ceramic element, and then forming the first and second external electrodes.

[0059] [Transfer foil sheet] The release film thus obtained is also suitable for use in the production of transfer foil sheets, such as a release film for transfer foils or a decorative release film, such as a transfer film. A transfer foil sheet using this film generally has a release layer on one side of a polyester film substrate, and transfer layers such as a pattern printing layer, a coloring layer, and an adhesive layer are laminated on the release layer in this order. Depending on the purpose, a hard coat layer, a metal vapor deposition layer, or the like is laminated on the transfer layer. Furthermore, functional agents such as antistatic agents and antibacterial agents are added to these release layers and transfer layers to impart their transfer foil functionality.

[0060] Commonly known methods for transferring transfer foils using the above-mentioned release film include thermal transfer (hot stamping) and simultaneous molding transfer (in-mold molding). The material of the object to which the transfer layer is transferred is not particularly limited, and includes molded products made of glass, metal, ceramics, resin, paper, fabric, etc. Furthermore, the shape of the object to be transferred is not particularly limited, and can be plate-like, film-like, sheet-like, or pre-molded into the desired shape. In this way, transfer foils are used in a wide range of applications for the purpose of applying surface treatments such as decoration and surface protection to the surface of the object to be transferred. [Example]

[0061] The present invention will be described in more detail below based on examples, but the present invention is not limited to the descriptions of these examples.

[0062] The methods for measuring the physical properties of the materials used in the examples and comparative examples are as follows. <Weight average molecular weight> The weight average molecular weight of the alkyl etherified melamine resin (A) was measured by GPC under the following conditions. Apparatus: Showa Denko Shodex GPC-101 Detector: RI-71S Column: Showa Denko GPCKF804L (Φ8.0 mm x 300 mm) x 3 Measurement temperature: 40℃ Eluent: THF (tetrahydrofuran) Flow rate: 1.0ml / min

[0063] <Alkyl ether group content> The alkyl ether group content ratio of the alkyl etherified melamine resin (A) was measured by placing 20 mg (or 10 mg) of the sample (melamine resin) in a 20 ml vial, sealing it, and heating it at 150°C for 30 minutes using a headspace sampler (Agilent G1888), and measuring the headspace gas by gas chromatography-mass spectrometry (GC) using a gas chromatograph (Agilent 6890GC / 5973MSD).

[0064] Here, for example, as alcohol workman When measuring the ethanol content, the amount generated was determined by the absolute calibration curve method using the peak area at the retention time obtained by extracted ion chromatogram processing using fragment ions characteristic of the ethanol mass spectrum. When measuring the methanol content, the amount generated was determined by the absolute calibration curve method using the peak area at the retention time. The molar ratio of methyl ether groups to ethyl ether groups was calculated from this amount generated.

[0065] <Average molar ratio of alkyl ether groups to 1 mole of triazine rings> The average molar ratio of alkyl ether groups to 1 mole of triazine rings in alkyl etherified melamine resin (A) was determined by dissolving the sample (melamine resin) in deuterated DMSO after volatilizing the dilution solvent under the following conditions: 13 C-NMR measurements were carried out. Equipment: AVANCE NEO manufactured by Bruker BioSpin cryo-500 type nuclear magnetic resonance spectrometer Measurement nucleus: 13C (125MHz) Measurement mode: Single pulse inverse gated proton decoupling Pulse width: 90 degrees (10.0 μs) Number of points: 64 Observation range: 250 ppm (-25 to 225 ppm) Repeat time: 20.0s Accumulation count: 64 times Measurement temperature: 25℃ Window function: exponential (BF: 1.0 Hz)

[0066] The integral ratio was calculated based on the following assignments to determine the molar ratio of alkyl ether groups to triazine rings. Triazine ring: 164 to 169 ppm Methyl ether group: 54 to 58 ppm Ethyl ether group: 61 to 63 ppm Butyl ether group: 30 to 34 ppm

[0067] <Concentration of biomass-derived carbon (C14)> The concentration of biomass-derived carbon (C14) in alkyl etherified melamine resin (A) was determined by combusting a sample to produce CO2, and then feeding the accurately quantified CO2 gas into an accelerated mass spectrometry (AMS) device to measure the amount of carbon with mass number 14, and mass number 12 or mass number 13, as described in ASTM (American Standard Test Method) D6866 04 (Standard Test Method for Determining the Biobased Content of Natural Range Materials Using Radiocarbon and Isotope Ratio Mass Spectrometry Analysis). This was done by comparing the amount of carbon with mass number 14 in the atmosphere and petrochemical products.

[0068] [Manufacturing Example 1] A four-neck flask equipped with a stirrer, thermometer, reflux condenser, and nitrogen inlet tube was charged with 126 g (1 mol) of melamine, 294 g (9 mol) of paraformaldehyde with a formaldehyde concentration of 92%, 460 g (10 mol) of ethanol, and 0.04 g (1 mmol) of sodium hydroxide, and the mixture was heated to reflux. 1 g (5.8 mmol) of paratoluenesulfonic acid was added and the first alkyl etherification reaction was carried out at reflux temperature. The mixture was then neutralized with 0.8 g (0.02 mol) of sodium hydroxide, and the ethanol was then distilled off under reduced pressure. Again, 1 g (5.8 mmol) of paratoluenesulfonic acid and 460 g (10 mol) of ethanol were added to complete the second alkyl etherification reaction, and then the mixture was neutralized with 0.8 g (0.02 mol) of sodium hydroxide. The ethanol was then distilled off under reduced pressure, and the mixture was diluted with isobutanol until the nonvolatile content reached 60% by weight, yielding melamine resin (A-1). The average molar ratio of alkyl ether groups to 1 mole of triazine rings in the resulting melamine resin (A-1) was 4.5, and Mw was 1,000.

[0069] [Manufacturing Examples 2 to 5] Melamine resins (A-2) to (A-4) and (A'-1) were obtained in the same manner as for melamine resin (A-1), except that the type and amount of alcohol used were changed as shown in Table 1. The physical properties of the obtained resins are shown in Table 2.

[0070] [Table 1]

[0071] [Manufacturing Example 6] A four-neck flask equipped with a stirrer, thermometer, reflux condenser, and nitrogen inlet tube was charged with 126 g (1 mol) of melamine, 163 g (5 mol) of paraformaldehyde with a formaldehyde concentration of 92%, and 368 g (8 mol) of ethanol, and the mixture was heated to reflux. After 1 hour of methylolation at reflux, 0.2 g (1.2 mmol) of paratoluenesulfonic acid was added and alkyl etherification was carried out at reflux for 3 hours. The reaction product was then neutralized with triethanolamine, and the ethanol was distilled off under reduced pressure. The mixture was then diluted with isobutanol to a nonvolatile content of 60 wt% to obtain melamine resin (A'-2). The average molar ratio of alkyl ether groups to 1 mole of triazine rings in the resulting melamine resin (A'-2) was 1.8, and the Mw was 1,200.

[0072] [Manufacturing Example 7] A four-neck flask equipped with a stirrer, thermometer, reflux condenser, and nitrogen inlet tube was charged with 126 g (1 mol) of melamine, 163 g (5 mol) of paraformaldehyde with a formaldehyde concentration of 92%, 593 g (8 mol) of butanol, and 0.2 g (1.2 mmol) of paratoluenesulfonic acid, and the mixture was heated to reflux. After 1 hour of methylolation at reflux, the mixture was subjected to alkyl etherification under reflux for 3 hours while dehydrating. The reaction product was then neutralized with triethanolamine. The butanol was then distilled off under reduced pressure, and the mixture was diluted with isobutanol to a nonvolatile content of 60 wt% to obtain melamine resin (A'-3). The average molar ratio of alkyl ether groups to 1 mole of triazine rings in the resulting melamine resin (A'-3) was 2.2, and the Mw was 3,800.

[0073] [Table 2]

[0074] [Example 1] 100 parts by weight (solid content equivalent, same below) of melamine resin (A-1) and 5 parts by weight of paratoluenesulfonic acid as acid catalyst (B) were mixed in toluene to obtain a formulation liquid of a release coating composition with a solid content of 10% by weight. The resulting mixture was uniformly applied to one side of an untreated PET film (thickness: 38 μm) as a substrate using a bar coater at 25° C. / 80% RH. The resulting coating layer (uncured coating film) was then cured by heating and drying at 80° C. for 1 minute, yielding a release film in which a 1.0 μm-thick cured layer (release layer) was laminated on the substrate.

[0075] [Examples 2 to 7, Comparative Examples 1 to 4] A formulation liquid and a release film were obtained in the same manner as in Example 1, except that the type of melamine resin, release component (C) (polyester-modified hydroxyl group-containing polyorganosiloxane (manufactured by BYK Japan, trade name: BYK-370, weight average molecular weight: 5000)), or other components (trimethylolpropane as a binder) were used in the amounts shown in Table 3.

[0076] The physical properties of the liquid mixtures and release films obtained in the above Examples and Comparative Examples were measured as follows.

[0077] <Storage stability (Low temperature stability of compounded solution)> The low-temperature stability of the liquid mixtures obtained in Examples 1 to 7 and Comparative Examples 1 to 4 was evaluated visually based on the following criteria. The results are shown in Table 3. ◯: After standing at 0°C for 24 hours, the ingredients did not precipitate. ×: After standing at 0°C for 24 hours, the compounded ingredients precipitated.

[0078] <Appearance of the coating film (cured coating film)> The coating appearance of the release films obtained in Examples 1 to 7 and Comparative Examples 1 to 4 was visually evaluated according to the following criteria. The results are shown in Table 3. ⊚: No whitening was observed on the film. ◯: Whitening was observed in part of the film, although it was at a level that would not cause any practical problems. ×: Whitening was observed over the entire film.

[0079] <Adhesion (adhesion to untreated PET)> The release films obtained in Examples 1 to 7 and Comparative Examples 1 to 4 were subjected to a cross-cut peel test in accordance with JIS K 5600-5-6 and evaluated based on the following criteria. The results are shown in Table 3. When no peeled portions were found in 100 squares, the score was recorded as 100 / 100, and when all peeled portions were found, the score was recorded as 0 / 100. Good: The number of areas where the substrate and the coating film were in close contact after peeling was 100 / 100. ×: The number of adhered portions between the substrate and the coating film after peeling was 0 / 100 to 99 / 100.

[0080] <Solvent resistance> The release films obtained in Examples 1 to 7 and Comparative Examples 1 to 4 were rubbed with gauze soaked in methyl ethyl ketone, and the number of times the rub was repeated until the substrate was exposed was evaluated based on the following criteria. The results are shown in Table 3. ⊚: The substrate was not exposed even after rubbing 80 times or more. ○: The substrate was exposed when rubbed 50 to 79 times. ×: The substrate was exposed when rubbed 0 to 49 times.

[0081] <Peeling force> A polyester adhesive tape (31B / manufactured by Nitto Denko Corporation) was attached to the test piece while being pressed with a load of 2 kg onto the release layer surface of the release films obtained in Examples 1 to 7 and Comparative Examples 1 to 4, and then the tensile peel strength (N / 25 mm) was calculated at an angle of 180 degrees and a peeling speed of 0.3 m / min. The results are shown in Table 3.

[0082] [Table 3] [Industrial Applicability]

[0083] The thermosetting release coating composition containing the alkyl etherified melamine resin obtained by the present invention not only provides a layer (cured layer) formed by applying and curing the composition with excellent release properties, but also suppresses poor appearance of the coating film (cured coating film), and exhibits excellent properties such as adhesion and solvent resistance even when cured at low temperatures. Therefore, for example, a release film comprising a substrate and a release layer, which is a cured layer obtained from the thermosetting release coating composition according to one embodiment of the present invention, is useful for producing ceramic green sheets that are raw materials for multilayer ceramic capacitors, etc., and for producing transfer foil sheets for processing the surface of a transfer target. Furthermore, the thermosetting release coating composition also has excellent storage stability, making it useful in this respect as well.

Claims

1. A thermosetting release coating composition comprising an alkyl etherified melamine resin (A) and an acid catalyst (B), the alkyl etherified melamine resin (A) contains an ethyl ether group as an alkyl ether group, and the alkyl etherified melamine resin (A) has a weight average molecular weight of 500 to 1,100; the total content of ethyl ether groups and, if necessary, methyl ether groups, relative to all alkyl ether groups contained in the alkyl-etherified melamine resin (A) is 80 to 100 mass%; A thermosetting release coating composition, wherein the alkyl-etherified melamine resin (A) has an average molar ratio of alkyl ether groups to 1 mole of triazine rings of 3 to 6.

2. The alkyl ether group contained in the alkyl etherified melamine resin (A) further contains a methyl ether group, 2. The thermosetting release coating composition of claim 1, wherein the molar ratio of methyl ether groups to ethyl ether groups, (methyl ether groups) / (ethyl ether groups), is 90 / 10 or less.

3. 2. The thermosetting release coating composition of claim 1, wherein the acid catalyst (B) is paratoluenesulfonic acid.

4. 2. The thermosetting release coating composition of claim 1, further comprising a release component (C).

5. 2. The thermosetting release coating composition according to claim 1, wherein the alkyl etherified melamine resin (A) contains 20 to 100% of biomass-derived carbon (C14) in the total organic carbon.

6. 2. The thermosetting release coating composition according to claim 1, wherein the content of the alkyl etherified melamine resin (A) is 10 to 99 parts by weight per 100 parts by weight of the solid content of the thermosetting release coating composition.

7. A laminate having a cured material layer on at least one surface of a substrate, the cured material layer being formed from the thermosetting release coating composition according to any one of claims 1 to 6.

8. The laminate of claim 7 wherein the substrate is polyethylene terephthalate.

9. The laminate of claim 8 wherein the substrate is untreated polyethylene terephthalate.

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