Release film and adhesive

Abstract

To provide a release film which is excellent in adhesion between a polyester film base material and a polyolefin-based release agent layer, and can secure release performance even after friction of the release agent layer surface.SOLUTION: A release film has a polyester film base material, a resin layer and a release agent layer, and has the resin layer between the polyester film base material and the release agent layer, wherein the resin layer is formed of a resin composition (I) containing an aqueous resin dispersion of a polymer (X) containing an olefinic polymer (A), a median diameter of the aqueous resin dispersion measured by a dynamic light scattering method is 300 nm or less, and the release agent layer is formed of a polyolefin-based release agent composition (II).SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a release film and an adhesive having an adhesive layer on a release agent layer of the release film. [Background technology]

[0002] Release films, which have a release layer on at least one side of the base film, are used in a variety of fields, including industrial materials, optical materials, electronic component materials, and battery packaging materials. Polyethylene terephthalate (PET) film, particularly biaxially oriented PET film, is widely used as the base film for release films due to its excellent transparency, mechanical strength, heat resistance, and flexibility.

[0003] Release films are widely used to protect adhesive or bonding surfaces. The most commonly used material for the release surface of release films has been silicone polymers containing siloxane units. However, because silicone-based release agents contain siloxane-based low-molecular-weight substances, when applied to precision applications such as electronic components, these substances can volatilize and oxidize in the air, causing adhesion and problems. Therefore, there was a need for a film that does not contain a siloxane source and has release properties equivalent to those of silicone-based release films. For example, hard disk drives are becoming increasingly high-performance and denser at a remarkable pace, and this trend of increased performance and density is expected to continue in the future. Furthermore, as hard disk drives become more high-performance and denser, it has been pointed out that the deposition of the aforementioned minute silicon compounds could negatively affect the reading and writing performance of the hard disks.

[0004] For example, Patent Document 1 describes a release sheet using a non-silicone release agent, specifically a release sheet composed of a base material and a release agent layer provided on the base material, wherein the release agent layer has a density of at least 0.80 to 0.90 g / cm³. 3A release sheet is disclosed, characterized by being composed of an olefin-based thermoplastic elastomer and a polyethylene resin. However, the release sheet disclosed in Patent Document 1 had insufficient adhesion between the polyolefin-based release agent layer and the base film, resulting in the problem that the release agent layer would detach from the adhesive layer when peeling it off.

[0005] Furthermore, Patent Document 2 discloses a release film in which an antistatic layer and a release layer are sequentially provided on at least one side of a polyester film, which is a release sheet that is excellent in heat resistance, solvent resistance, adhesion between the release layer and the substrate, and antistatic properties, and in which an adhesive layer can be directly coated onto the release layer. In this release film, the release layer is a cured layer of a resin composition containing a non-reactive polyolefin, a reactive polyolefin, and a crosslinking agent, and the surface resistivity of the release layer is 1 × 10⁻⁶ 12 This is a release film with a value of Ω / □ or less.

[0006] Furthermore, Patent Document 3 discloses a process film that improves the adhesion between a substrate and a polypropylene release layer, wherein at least a substrate layer, an adhesive layer, and a release layer are laminated in this order, and the adhesive layer contains an acid-modified polyolefin resin which is a copolymer of an unsaturated carboxylic acid component and an olefin component, the olefin component mainly consists of a propylene component, and the release layer is a polyolefin resin containing 70% by mass or more of the propylene component. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2001-246697 [Patent Document 2] Japanese Patent Publication No. 2019-111748 [Patent Document 3] Japanese Patent Publication No. 2017-065115 [Overview of the project] [Problems that the invention aims to solve]

[0008] However, the inventors' research has revealed that with the release films disclosed in Patent Documents 2 and 3, the release layer detaches after friction on the release layer surface, and release performance cannot be guaranteed. Thus, conventional non-silicone release films still did not provide sufficient adhesion between the polyester film substrate and the polyolefin-based release agent layer.

[0009] Therefore, the object of the present invention is to provide a release film that exhibits excellent adhesion between a polyester film substrate and a polyolefin-based release agent layer, and that can ensure release performance even after friction of the release agent layer surface. [Means for solving the problem]

[0010] The polyester film of the present invention has one of the following embodiments in order to solve the above problems.

[0011] [1] A release film comprising a polyester film substrate, a resin layer and a release agent layer, wherein the resin layer is located between the polyester film substrate and the release agent layer, the resin layer is formed from a resin composition (I) containing an aqueous resin dispersion of a polymer (X) including an olefin polymer (A), the median diameter of the aqueous resin dispersion measured by dynamic light scattering is 300 nm or less, and the release agent layer is formed from a polyolefin-based release agent composition (II).

[0012] [2] The release film according to [1] above, wherein the olefin polymer (A) is a modified olefin polymer having a reactive group.

[0013] [3] The release film according to [2] above, wherein the reactive group is a carboxyl group and its anhydride.

[0014] [4] The aqueous resin dispersion of the polymer (X) is a release film according to any one of [1] to [3] above, in which an olefin-based polymer (A) and a polymer (B) containing a structural unit derived from a radically polymerizable monomer having a reactive functional group are dispersed in an aqueous medium.

[0015] [5] The release film according to any one of [1] to [4] above, wherein the resin composition (I) further contains a curing agent.

[0016] [6] The release film according to [5] above, wherein the curing agent is an oxazoline-based compound.

[0017] [7] The release film according to any one of [1] to [6] above, wherein the polyolefin-based release agent composition (II) contains an α-olefin homopolymer or copolymer.

[0018] [8] The release film according to [7] above, wherein the α-olefin homopolymer or copolymer is an ethylene-α-olefin copolymer.

[0019] [9] The release film according to [7] or [8] above, wherein the polyolefin-based release agent composition (II) further contains a polyolefin polyol.

[0020]

[10] The release film according to [9] above, wherein the polyolefin-based release agent composition (II) further contains an isocyanate compound.

[0021]

[11] An adhesive body having an adhesive layer on the release agent layer of the release film according to any one of [1] to

[10] above.

Advantages of the Invention

[0022] The release film of the present invention has an advantage that by interposing a resin layer containing a specific material between a polyester film substrate and a polyolefin-based release agent layer, the adhesion between the polyester film substrate and the release agent layer is excellent, and the release performance can be ensured even after friction on the release agent layer surface.

Embodiments for Carrying out the Invention

[0023] <Release film> The release film of the present invention (hereinafter referred to as "this release film") comprises a polyester film substrate, a resin layer, and a release agent layer. Furthermore, in this release film, the resin layer is provided between the polyester film substrate and the release agent layer. In this configuration, it is preferable that the resin layer is provided on the polyester film substrate, and it is even more preferable that the release agent layer is provided on the resin layer. Furthermore, other layers may be interposed between the polyester film substrate and the resin layer, and between the resin layer and the mold release agent layer, or the layers may be directly laminated without any other layers interposed.

[0024] <Polyester film substrate> The polyester film of the polyester film substrate may be a single layer or a laminated structure of two or more layers. Furthermore, in the case of a laminated structure, the constituent materials of each layer may be the same or different. For example, it is possible to create a three-layer structure by using different materials for the surface layer and the intermediate layer. The polyester film in this invention may be an unoriented film (sheet) or an oriented film, but it is preferably an oriented film, and more preferably a biaxially oriented film.

[0025] The polyester used in the polyester film substrate may be a homopolyester or a copolymerized polyester. If it is a homopolyester, it is preferably one obtained by polycondensation of an aromatic dicarboxylic acid and an aliphatic glycol. Examples of aromatic dicarboxylic acids include terephthalic acid and 2,6-naphthalenedicarboxylic acid, while examples of aliphatic glycols include ethylene glycol, diethylene glycol, and 1,4-cyclohexanedimethanol. A typical polyester is polyethylene terephthalate. On the other hand, examples of dicarboxylic acid components of copolymerized polyesters include one or more types such as isophthalic acid, phthalic acid, terephthalic acid, 2,6-naphthalenedicarboxylic acid, adipic acid, and sebacic acid, and examples of glycol components of copolymerized polyesters include one or more types such as ethylene glycol, diethylene glycol, propylene glycol, butanediol, 1,4-cyclohexanedimethanol, and neopentyl glycol.

[0026] There are no particular restrictions on the polymerization catalyst for polyester; conventionally known compounds can be used, such as antimony compounds, titanium compounds, germanium compounds, manganese compounds, aluminum compounds, magnesium compounds, and calcium compounds. Among these, antimony compounds have the advantage of being inexpensive and having high catalytic activity. In the polyester film of the present invention, particles may be incorporated primarily for the purpose of providing slipperiness and preventing scratches during each process. When incorporating particles, the type of particles to be incorporated is not particularly limited as long as they can provide slipperiness. Specific examples include inorganic particles such as silica, calcium carbonate, magnesium carbonate, barium carbonate, calcium sulfate, calcium phosphate, magnesium phosphate, kaolin, aluminum oxide, and titanium oxide, and organic particles such as acrylic resin, styrene resin, urea resin, phenolic resin, epoxy resin, and benzoguanamine resin. Furthermore, during the polyester manufacturing process, precipitated particles obtained by precipitating and finely dispersing a portion of metal compounds such as catalysts can also be used.

[0027] On the other hand, there are no particular limitations on the shape of the particles used; spherical, lumpy, rod-shaped, flattened, or any other shape may be used. Furthermore, there are no particular restrictions on their hardness, specific gravity, color, etc. Two or more types of these particles may be used in combination as needed. Furthermore, the average particle size of the particles used is preferably 5 μm or less, and more preferably in the range of 0.1 to 3 μm. By using an average particle size within the above range, the film can be given an appropriate surface roughness, ensuring good slipperiness and smoothness.

[0028] Furthermore, the particle content in the polyester film substrate is preferably 5% by mass or less, more preferably in the range of 0.0003 to 3% by mass. If there are no particles or only a very small amount, the transparency of the film will be high, resulting in a good film. Conversely, by including a certain amount of particles, sufficient slipperiness will be achieved.

[0029] The method for adding particles to the polyester film substrate is not particularly limited, and conventionally known methods can be employed. For example, the particles can be added at any stage in the production of the polyester constituting each layer, but it is preferable to add them after the esterification or transesterification reaction is completed. Alternatively, the particles can be melt-mixed and kneaded into the polyester using an extruder or similar device.

[0030] If the polyester film has a laminated structure of three or more layers, it is also preferable to include particles only in the surface layer. In addition to the particles mentioned above, conventionally known antioxidants, heat stabilizers, lubricants, dyes, pigments, etc., may be added to the polyester film substrate as needed.

[0031] The thickness of the polyester film substrate is not particularly limited as long as it is within the range that allows for film formation, but from the viewpoint of mechanical strength, handling, and productivity, it is preferably in the range of 5 to 300 μm, more preferably 10 to 125 μm.

[0032] <Method for manufacturing polyester film substrate> Next, we will specifically describe examples of the manufacturing of polyester film substrates, but we are not limited to the following examples. A preferred method for manufacturing a polyester film substrate is to extrude dried polyester raw material pellets from a die using an extruder as a molten sheet, and then cool and solidify it with a cooling roll to obtain an unstretched sheet. In this case, it is preferable to improve the adhesion between the sheet and the rotating cooling drum in order to improve the flatness of the sheet, and electrostatic application adhesion and / or liquid coating adhesion methods are preferably employed. Next, the obtained unstretched sheet is stretched in two axial directions. In this case, first, the unstretched sheet is stretched in one direction using a roll or tenter type stretcher. The stretching temperature is usually 70 to 120°C, preferably 80 to 110°C, and the stretching ratio is usually 2.5 to 7 times, preferably 3.0 to 6 times. Next, the material is stretched in a direction perpendicular to the first stretching direction. In this case, the stretching temperature is usually 70 to 170°C, and the stretching ratio is usually 3.0 to 7 times, preferably 3.5 to 6 times. Then, the film is heat-treated at a temperature of 180-270°C under tension or under relaxation of 30% or less to obtain a biaxially oriented film. In the stretching described above, a method can be adopted in which stretching is performed in two or more stages in one direction. In that case, it is preferable to perform the stretching so that the final stretching ratios in both directions fall within the above ranges.

[0033] Furthermore, simultaneous biaxial stretching can also be employed in the manufacture of polyester film substrates. Simultaneous biaxial stretching is a method of simultaneously stretching and oriented the aforementioned unstretched sheet in the machine direction and width direction under temperature control, usually at 70 to 120°C, preferably 80 to 110°C, with a stretching ratio of 4 to 50 times, preferably 7 to 35 times, and more preferably 10 to 25 times in area ratio. Subsequently, heat treatment is performed at a temperature of 170 to 250°C under tension or under relaxation of 30% or less to obtain a stretched and oriented film. Regarding the simultaneous biaxial stretching apparatus employing the above stretching method, conventionally known stretching methods such as screw type, pantograph type, and linear drive type can be employed.

[0034] Furthermore, a so-called in-line coating method can be applied to treat the film surface during the stretching process of the polyester film described above. When a resin layer, as described later, is provided on the polyester film by the coating method, coating can be performed simultaneously with stretching, and the thickness of the resin layer can be reduced according to the stretching ratio, making it possible to manufacture a suitable release film.

[0035] Furthermore, the term "polyester film" in this release film does not refer only to pre-formed films; it simply refers to any release film that contains a polyester layer. In other words, "polyester film" is synonymous with "polyester layer." Therefore, a polyester film can be produced not only by laminating a resin layer and / or a release agent layer onto the surface of a polyester film, but also by co-extruding a polyester layer and a resin layer, or a polyester layer, a resin layer, and a release agent layer.

[0036] <Resin layer> The resin layer in this release film is formed from a resin composition (I) containing an aqueous resin dispersion of an olefin polymer.

[0037] The resin layer can be formed, for example, by coating it onto a polyester film substrate and heat-treating it as needed. The heat treatment is preferably carried out at a temperature of 55 to 300°C, preferably 70 to 290°C. Heat treatment improves the film-forming properties of the resin layer and enhances its adhesion to the substrate. Alternatively, it may be cured using a hardening agent or the like. Furthermore, the resin layer may be formed by, for example, in-line coating, which involves treating the film surface during the film-making process of the polyester film substrate, or by off-line coating, which involves applying the resin layer to the manufactured film outside of the system. More preferably, it is formed by in-line coating.

[0038] In-line coating is a method of coating a polyester film, which is the base material, within the manufacturing process. Specifically, it involves coating at any stage from melt-extruded polyester to stretched, heat-set, and wound up. Typically, coating is applied to an unstretched sheet obtained by melting and rapidly cooling, a stretched uniaxially oriented film, a biaxially oriented film before heat-set, or a film after heat-set but before winding. While not limited to the above, for example, in sequential biaxial stretching, a method in which a uniaxially oriented film stretched in the longitudinal direction (vertical direction) is coated and then stretched in the transverse direction is particularly advantageous. This method offers cost advantages in manufacturing because film formation and resin layer formation can be performed simultaneously. Furthermore, because stretching is performed after coating, the thickness of the resin layer can be varied according to the stretching ratio, making thin-film coating easier compared to offline coating.

[0039] Furthermore, by providing a resin layer on the polyester film before stretching, the resin layer can be stretched together with the base film, thereby allowing the resin layer to adhere firmly to the base film. Furthermore, in the manufacturing of biaxially oriented polyester film, the film can be restrained in both the longitudinal and transverse directions by gripping the film edges with clips or the like while stretching. This allows for high temperatures to be applied during the heat-setting process without wrinkles or other defects, while maintaining flatness. Therefore, the heat treatment applied after coating can reach temperatures that cannot be achieved by other methods, improving the film-forming properties of the resin layer, allowing for stronger adhesion between the resin layer and the substrate film. Moreover, the resin layer itself can be made stronger, improving properties such as moisture and heat resistance.

[0040] As a method for forming the resin layer, conventionally known coating methods such as gravure coating, reverse roll coating, die coating, air doctor coating, blade coating, rod coating, bar coating, curtain coating, knife coating, transfer roll coating, squeeze coating, impregnation coating, kiss coating, spray coating, calender coating, and extrusion coating can be used. Furthermore, to improve the applicability and adhesion to the film, the polyester film substrate may be subjected to chemical treatment, corona discharge treatment, plasma treatment, etc., before application.

[0041] The thickness of the resin layer is typically 0.005 to 1.5 μm, preferably 0.01 to 0.5 μm, and more preferably 0.02 to 0.2 μm. When the resin layer thickness is within this range, adhesion between the polyester film substrate and the resin layer can be ensured, and deterioration of the resin layer's appearance (especially the coated appearance) and blocking can be prevented.

[0042] <Resin composition (I)> The resin composition (I) for forming the resin layer (hereinafter also referred to as "the composition") comprises an aqueous resin dispersion of a polymer (X) containing an olefin polymer (A). The aqueous resin dispersion contains at least particles of an olefin polymer (A) dispersed in an aqueous medium, and may also contain particles of other polymers besides the olefin polymer (A). On the other hand, the aqueous resin dispersion may be an aqueous resin dispersion containing only the olefin polymer (A).

[0043] Furthermore, the median diameter of the aqueous resin dispersion, as measured by dynamic light scattering, is 300 nm or less. Having a median diameter of 300 nm or less in the aqueous resin dispersion allows for good adhesion of the resin layer to the mold release agent layer. From this viewpoint, the median diameter of the aqueous resin dispersion, as measured by dynamic light scattering, is preferably 250 nm or less, more preferably 200 nm or less, even more preferably 150 nm or less, and most preferably 120 nm or less. The median diameter measured here refers to the median diameter of the particles of polymer (X), which includes particles of olefin polymer (A) and polymer (B) containing constituent units derived from radical polymerizable monomers having reactive functional groups, as described later. Furthermore, "median diameter" refers to the particle diameter (d50) at which the cumulative volume distribution corresponds to 50% when the volume distribution is plotted on the horizontal axis with the particle diameter on the vertical axis, based on volume-based data of the filler obtained by particle size distribution measurement. This can be measured by the method described in the examples. The particle size can be adjusted, for example, by the emulsion polymerization conditions during the production of an aqueous resin dispersion containing an olefin polymer (A), or by the polymerization conditions during the production of a polymer other than the olefin polymer (A) described below (B).

[0044] Furthermore, the aqueous medium of the aqueous resin dispersion may contain water and, if necessary, other solvents. Examples of solvents other than water include methyl ethyl ketone, cyclohexanone, n-propanol, isopropanol, n-butanol, isobutanol, t-butanol, cyclohexanol, tetrahydrofuran, 2-methoxyethanol, 2-ethoxyethanol, 2-butoxyethanol, 2-methoxypropanol, and 2-ethoxypropanol. These may be used individually or in combination of two or more types.

[0045] The olefin polymer (A) mentioned above can be a polymer containing 50 mol% or more of olefin-derived structural units relative to the total structural units (100 mol%) constituting the olefin polymer, and may be a homopolymer or a copolymer. Note that when simply referring to a "polymer," it may refer to either a random copolymer or a block copolymer.

[0046] More specifically, the aforementioned olefin polymer (A) includes olefin polymers without reactive groups (A1) (hereinafter also referred to as "polymer (A1)") and modified olefin polymers with reactive groups (A2) (hereinafter also referred to as "polymer (A2)").

[0047] <Polymer (A1)> The polymer (A1) preferably includes olefin polymers having a melting point [Tm] of 125°C or less, more preferably 100°C or less, and even more preferably 90°C or less. The lower limit of Tm is preferably 60°C or higher. More specifically, the polymer (A1) can be a homopolymer of ethylene or propylene, a copolymer of ethylene and propylene, a copolymer of at least one of ethylene and propylene with a monomer copolymerizable with ethylene and propylene, a copolymer consisting of two or more selected from the group consisting of α-olefins having 4 or more carbon atoms (described later), a copolymer of α-olefins having 2 or more carbon atoms with non-aromatic monomers other than α-olefins such as vinyl acetate, acrylic acid esters, and methacrylic acid esters, a copolymer of α-olefins having 2 or more carbon atoms with aromatic monomers such as aromatic vinyl monomers or hydrogenated thereof, a conjugated diene block copolymer or hydrogenated thereof, and the like. Furthermore, examples of monomers copolymerizable with ethylene and propylene include butene-1, pentene-1, hexene-1, heptene-1, octene-1, cyclopentene, cyclohexene, norbornene, and other α-olefins having 4 or more carbon atoms. As the copolymer, a copolymer consisting of at least two α-olefins having 2 to 4 carbon atoms, i.e., ethylene, propylene, and butene-1, is preferred. Furthermore, as the polymer, chlorinated polyolefins, which are obtained by chlorinating the aforementioned polyolefins, may be used.

[0048] More specific examples include polyethylene, polypropylene, ethylene-butene copolymer, ethylene-propylene copolymer, propylene-butene copolymer, propylene-hexene copolymer, chlorinated polyethylene, chlorinated polypropylene, chlorinated ethylene-propylene copolymer, chlorinated propylene-butene copolymer, ethylene-vinyl acetate copolymer, hydrogenated styrene-butadiene-styrene block copolymer (SEBS), hydrogenated styrene-isoprene-styrene block copolymer (SEPS), and the like. These polymers may be used individually or in combination of two or more. The polymers may be linear or branched.

[0049] <Polymer (A2)> The polymer (A2) is a modified olefin polymer having a reactive group. Examples of reactive groups include carboxyl groups and their anhydrides, amino groups, epoxy groups, isocyanate groups, sulfonyl groups, and hydroxyl groups. Among these, carboxyl groups and their anhydrides are preferred.

[0050] Examples of the polymer (A2) include copolymers (A21) obtained by copolymerizing an olefin with a radical polymerizable monomer having a reactive group, and graft polymers (A22) obtained by graft polymerizing a radical polymerizable unsaturated compound having a reactive group onto an olefin-based polymer.

[0051] The copolymer (A21) is obtained by copolymerizing an olefin with a radical polymerizable monomer having a reactive group, and is a copolymer in which structural units derived from the radical polymerizable monomer having a reactive group are inserted into the main chain. Examples of olefins used in copolymer (A21) include ethylene, propylene, butene, and other α-olefins. The olefin may be used alone or in combination of two or more types. Examples of reactive radical polymerizable monomers used in copolymer (A21) include α,β-unsaturated carboxylic acids such as acrylic acid and maleic anhydride, or anhydrides. Reactive radical polymerizable monomers may be used individually or in combination of two or more.

[0052] Specific examples of the copolymer (A21) include, for example, ethylene-acrylic acid copolymer and ethylene-acrylic acid ester-maleic anhydride copolymer. The copolymer (A21) may be used alone or in combination of two or more types.

[0053] The aforementioned graft polymer (A22) is obtained by, for example, graft polymerizing a radically polymerizable unsaturated compound having a reactive group onto an olefin polymer. As the olefin polymer, the polymer (A1) described above can be used.

[0054] Examples of radical polymerizable unsaturated compounds having the aforementioned reactive group include (meth)acrylic acid, fumaric acid, maleic acid or its anhydride, itaconic acid or its anhydride, and crotonic acid. These may be used individually or in combination of two or more types. In this specification, "(meth)acrylic acid" is a general term for acrylic acid and methacrylic acid, and other compounds are treated similarly.

[0055] Furthermore, the graft polymer (A22) is preferably an olefin polymer bonded to a hydrophilic polymer. Specific examples include maleic anhydride-modified polypropylene and its chlorinated product, maleic anhydride-modified ethylene-propylene copolymer and its chlorinated product, maleic anhydride-modified propylene-butene copolymer, acrylic acid-modified polypropylene and its chlorinated product, acrylic acid-modified ethylene-propylene copolymer and its chlorinated product, and acrylic acid-modified propylene-butene copolymer. These may be used individually or in combination of two or more types.

[0056] Radical polymerization initiators used in graft polymerization can be appropriately selected from conventional radical polymerization initiators, such as organic peroxides and azonitriles. Examples of organic peroxides include peroxyketals such as di(t-butylperoxy)cyclohexane; hydroperoxides such as cumene hydroperoxide; dialkyl peroxides such as di(t-butyl)peroxide; diacyl peroxides such as benzoyl peroxide; and peroxyesters such as t-butylperoxyisopropyl monocarbonate. These may be used individually or in combination of two or more. Examples of azonitriles include azobisbutyronitrile and azobisisopropylnitrile. These may be used individually or in combination of two or more. Among the radical polymerization initiators mentioned above, benzoyl peroxide and t-butyl peroxyisopropyl monocarbonate are particularly preferred.

[0057] The content of reactive groups in the graft polymer (A22) is preferably 0.01 to 1 mmol per gram of the olefin polymer used in polymer (A22), i.e., 0.01 to 1 mmol / g. The content of reactive groups in polymer (A22) is more preferably 0.05 mmol / g or more, and even more preferably 0.1 mmol / g or more. Furthermore, the content of reactive groups in the polymer (A22) is preferably 0.5 mmol / g or less, and more preferably 0.3 mmol / g or less. As described above, the content of reactive groups in polymer (A22) is preferably 0.01 mmol / g to 1 mmol / g, more preferably 0.05 mmol / g to 0.5 mmol / g, and even more preferably 0.1 mmol / g to 0.3 mmol / g.

[0058] If the content of reactive groups in the polymer (A22) is above the lower limit, it tends to have sufficient hydrophilicity and a smaller dispersed particle size. Furthermore, if the content of reactive groups in the polymer (A22) is below the aforementioned upper limit, sufficient adhesion to the polyolefin release agent layer tends to be obtained. Furthermore, if the reactive group in the graft polymer (A22) is an acidic group such as a carboxyl group or its anhydride, or a sulfonyl group, neutralizing the acidic group with a basic compound tends to improve the mechanical stability of the aqueous resin dispersion.

[0059] <Polymer (B)> The aqueous resin dispersion described above is also preferably an embodiment in which the olefin-based polymer (A) and a polymer (B) containing constituent units derived from a radically polymerizable monomer having a reactive functional group are dispersed in an aqueous medium. The polymer (B) is a polymer other than the olefin polymer (A) that contains a constituent unit derived from a radical polymerizable monomer (b1) (hereinafter referred to as "radical polymerizable monomer (b1)") containing a reactive functional group (hereinafter referred to as "reactive functional group (i)"). Because polymer (B) contains structural units derived from the radical polymerizable monomer (b1), the olefin polymer (A) and polymer (B) form a crosslinked structure, resulting in high coating strength. Therefore, the coating film formed by the aqueous resin dispersion of the present invention exhibits excellent adhesion to the polyolefin-based release agent layer. The reactive functional group (i) is a functional group that reacts with the reactive group of polymer (A2). Examples of reactive functional groups (i) include carboxyl groups, hydroxyl groups, amino groups, epoxy groups, isocyanate groups, and sulfonyl groups. Hydroxyl groups and epoxy groups are preferred because they exhibit excellent adhesion to polyolefin substrates such as polypropylene substrates.

[0060] Examples of radical polymerizable monomers (b1) include hydroxyl group-containing radical polymerizable monomers such as 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 3-hydroxypropyl acrylate, 2-hydroxypropyl acrylate, 3-hydroxypropyl methacrylate, 2-hydroxypropyl methacrylate, 4-hydroxybutyl acrylate, 2-hydroxybutyl acrylate, 4-hydroxybutyl methacrylate, 2-hydroxybutyl methacrylate, polypropylene glycol acrylate, and polypropylene glycol methacrylate; and epoxy group-containing vinyl monomers such as glycidyl methacrylate and methacrylate glycidyl ether. Among these, radical polymerizable monomers containing epoxy groups are preferred. The radical polymerizable monomer (b1) containing the reactive functional group (i) may be used alone or in combination of two or more types.

[0061] Polymer (B) is preferably polymerizable and has excellent polymerizability, and the stability of the aqueous resin dispersion is improved, and therefore, in addition to the constituent units derived from the radical polymerizable monomer (b1), it is preferable that it has constituent units derived from a radical polymerizable monomer (b2) that does not have a reactive functional group (i) (hereinafter referred to as "radical polymerizable monomer (b2)"). The radical polymerizable monomer (b2) is preferably one that exhibits excellent copolymerization with the radical polymerizable monomer (b1), and more preferably a vinyl monomer that does not have a reactive functional group (i). Examples of radical polymerizable monomers (b2) include (meth)acrylic acid esters that do not have a reactive functional group (i), aromatic monomers, amide monomers, (meth)acrylonitrile, vinyl acetate, vinyl propionate, vinyl versaticate, and the like. These may be used individually or in combination of two or more types.

[0062] Examples of (meth)acrylic acid esters that do not have the reactive functional group (i) include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, hexyl (meth)acrylate, cyclohexyl (meth)acrylate, octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, nonyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, (meth)acrylic acid esters having an aryl or aralkyl group with 6 to 12 carbon atoms, dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, 2-methoxyethyl (meth)acrylate, 3-methoxypropyl (meth)acrylate, polyethylene oxide adducts of (meth)acrylic acid, and (meth)acrylic acid esters having a fluoroalkyl group with 1 to 20 carbon atoms. Examples of (meth)acrylic acid esters having an aryl or aralkyl group with 6 to 12 carbon atoms include benzyl (meth)acrylate. Examples of (meth)acrylic acid esters having a fluoroalkyl group with 1 to 20 carbon atoms include trifluoromethyl (meth)acrylate, 2-trifluoromethyl ethyl (meth)acrylate, and 2-perfluoroethyl ethyl (meth)acrylate.

[0063] Examples of aromatic monomers that do not have the above-mentioned reactive functional group (i) include styrene and α-methylstyrene. Examples of amide monomers that do not have a reactive functional group (i) include (meth)acrylamide and dimethyl(meth)acrylamide.

[0064] As radical polymerizable monomers (b2), (meth)acrylic acid esters and aromatic monomers are preferred from the viewpoint of weather resistance and solvent resistance. Among these, isobutyl methacrylate, t-butyl methacrylate, butyl acrylate, styrene, and cyclohexyl methacrylate are more preferred from the viewpoint of adhesion to polypropylene substrates, and styrene, butyl acrylate, and isobutyl methacrylate are particularly preferred.

[0065] In the aqueous resin dispersion described above, the olefin polymer (A) and the polymer (B) may be dispersed as separate particles, or they may be dispersed as composite particles of the olefin polymer (A) and the polymer (B). From the viewpoint of the stability of the aqueous resin dispersion, it is preferable that the aqueous resin dispersion contains composite particles of the olefin polymer (A) and the polymer (B), and it is preferable that they are dispersed as composite particles.

[0066] The mass ratio of polymer (B) to olefin polymer (A) contained in the aqueous resin dispersion (mass of polymer (B) (solid content) / mass of olefin polymer (A) (solid content), hereinafter referred to as polymer (B) / polymer (A)) is preferably 0.5 to 2. If the ratio of polymer (B) / polymer (A) is above the lower limit, the aqueous resin dispersion is easier to produce stably, and the storage stability of the aqueous resin dispersion tends to improve. If the ratio of polymer (B) / polymer (A) is below the upper limit, the initial adhesion to the polyolefin-based release agent layer tends to be good.

[0067] The total solid content concentration of the olefin polymer (A) and polymer (B) in the aqueous resin dispersion is preferably 10 to 60% by mass, and more preferably 20 to 50% by mass. Within this range, the aqueous resin dispersion can be easily manufactured stably, and there is no risk of poor storage stability of the aqueous resin dispersion.

[0068] The states of the olefin polymer (A) and polymer (B) in the resin layer can be determined by staining ultrathin sections prepared using a general gel embedding method with RuO4 and observing them using a transmission electron microscope.

[0069] In an aqueous resin dispersion in which the olefin polymer (A) and polymer (B) are dispersed in an aqueous medium, there are insoluble components such as insoluble matter derived from the olefin polymer (A), insoluble matter derived from polymer (B), and insoluble matter formed by the bonding of the olefin polymer (A) and polymer (B). Among these, the insoluble product formed by the bonding of the olefin polymer (A) and polymer (B) is preferred because it tends to contribute to improving the water resistance of the coating film. The aforementioned insoluble component is the component insoluble in tetrahydrofuran (hereinafter referred to as "THF") contained in the dried aqueous resin dispersion. In detail, 1 g of aqueous resin dispersion is dried at 23°C for 12 hours to evaporate the dispersion medium in the aqueous medium, and then dried again in a vacuum dryer at 23°C and 10 Torr for 6 hours to obtain the dried product. THF is added to the dried product to a concentration of 1% by mass, and the mixture is allowed to stand at 23°C for 24 hours to dissolve the components soluble in THF. The components are then filtered off using filter paper with a particle size of 1 μm. From the above viewpoint, the content of insoluble components in the dried aqueous resin dispersion (100% by mass) is preferably 1% by mass or more, more preferably 5% by mass or more, and even more preferably 10% by mass or more. If the content of insoluble components in the dried aqueous resin dispersion (100% by mass) is above the above lower limit, the water resistance of the coating film tends to be good.

[0070] <Optional components of aqueous resin dispersions> The aqueous resin dispersion described above may also contain any other components besides those mentioned above. Examples of optional components include surfactants added for purposes such as improving storage stability. Examples of surfactants include various anionic surfactants, cationic surfactants, nonionic surfactants, or polymeric surfactants. Furthermore, so-called reactive surfactants, which have ethylenically unsaturated bonds in their surfactant components, can also be used. Among these, anionic surfactants are preferred from the viewpoint of improving the storage stability of aqueous resin dispersions. The anionic surfactant is not particularly limited, and for example, the reactive surfactant Adekaria® Soap SR (trade name, manufactured by ADEKA Corporation) and the non-reactive surfactant Neocol® SW-C (trade name, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) can be used.

[0071] <Method for producing aqueous resin dispersion> The above aqueous resin dispersion can be manufactured by known methods. For example, when using the polymers (A1) or (A2) described above, they can be produced by emulsion polymerization of the monomer components constituting each polymer, and the median diameter of the aqueous resin dispersion can be adjusted by appropriately changing the concentration of the emulsifier (surfactant). Furthermore, an aqueous resin dispersion may be produced by using a self-emulsifying polymer, such as polymer (A22) above, which has hydrophilic parts (hydrophilic groups) in its molecular structure necessary for stable dispersion in water. Furthermore, a preferred embodiment for producing an aqueous resin dispersion when using the olefin polymer (A) and the polymer (B) will be described in detail below. The aqueous resin dispersion is first obtained by polymerizing a radical polymerizable monomer (b1) having a reactive functional group in an aqueous medium containing an olefin polymer (A) to obtain an aqueous resin dispersion containing a polymer containing a reactive functional group (Step 1). Next, a radical polymerizable monomer (b2) without a reactive functional group is added to the aqueous resin dispersion and polymerized to obtain an aqueous resin dispersion containing a polymer (B) containing constituent units derived from the radical polymerizable monomer (b1) having a reactive functional group (Step 2). Through the above steps, an aqueous resin dispersion is obtained containing an olefin polymer (A) and a polymer (B) having constituent units derived from a radical polymerizable monomer (b1) and a radical polymerizable monomer (b2). If the process is stopped at the first step described above, an aqueous resin dispersion is obtained containing an olefin polymer (A) and a polymer (B) having constituent units derived from a radical polymerizable monomer (b1).

[0072] To improve the coating strength of the resin layer, it is preferable to react the olefin polymer (A) with a radical polymerizable monomer (b1) of polymer (B) to form a crosslinked structure between the olefin polymer (A) and polymer (B). The method for reacting the olefin polymer (A) and radical polymerizable monomer (b1) of the present invention is not particularly limited, but from the viewpoint of the stability of the aqueous dispersion of the olefin polymer (A), a heating method is preferred. The heating temperature is preferably 30°C or higher, more preferably 40°C or higher, and particularly preferably 50°C or higher. Furthermore, the heating temperature is preferably 120°C or lower, and more preferably 100°C or lower. For example, the heating temperature is preferably 30°C to 120°C, more preferably 40°C to 120°C, and even more preferably 50°C to 100°C. If the heating temperature is above the lower limit, sufficient reactivity is easily obtained. If the heating temperature is below the upper limit, the storage stability of the aqueous dispersion is easily improved.

[0073] The reaction between the olefin polymer (A) and the radical polymerizable monomer (b1) of the present invention can be confirmed by measuring the amount of monomer (b1) before and after the reaction using a gas chromatography-mass spectrometer (GC / MS).

[0074] <Optional components of this composition> In addition to the olefin polymer (A) and the optional polymer (B) described above, this composition may also contain dispersed particles of other polymers. Examples of such resins include polyester resins, polyurethane resins, acrylic resins, acrylic urethane resins, acrylic silicone resins, silicone resins, fluororesins, epoxy resins, polyolefin resins, and alkyd resins. Polyurethane resins, acrylic resins, and acrylic urethane resins are preferred because they have excellent adhesion to the polyolefin release agent layer, and polyurethane resins and acrylic urethane resins are further preferred because they have a superior appearance to the resin layer. Among these, acrylic urethane resins are particularly preferred from the viewpoint of adhesion to the polyolefin release agent layer. Furthermore, a curing agent may be included in this composition. Examples of such curing agents include amino resins, polyisocyanate compounds, blocked polyisocyanate compounds, melamine resins, urea resins, carboxyl group-containing compounds, carboxyl group-containing resins, epoxy group-containing resins, epoxy group-containing compounds, carbodiimide group-containing compounds, and oxazoline compounds. Among these, oxazoline compounds are preferred from the viewpoint of adhesion to polyester film substrates. The curing agent content is preferably 10 to 50% by mass, and more preferably in the range of 25 to 40% by mass, based on the total solid content.

[0075] Examples of the oxazoline compounds include compounds having an oxazoline group in the molecule, and polymers containing an oxazoline group are particularly preferred. Such polymers can be produced by polymerization of an addition-polymerizable oxazoline group-containing monomer alone or with other monomers. Examples of the addition-polymerizable oxazoline group-containing monomers include 2-vinyl-2-oxazoline, 2-vinyl-4-methyl-2-oxazoline, 2-vinyl-5-methyl-2-oxazoline, 2-isopropenyl-2-oxazoline, 2-isopropenyl-4-methyl-2-oxazoline, and 2-isopropenyl-5-ethyl-2-oxazoline, and one or more of these can be used. Among these, 2-isopropenyl-2-oxazoline is preferred because it is readily available industrially. Other monomers are not limited to monomers copolymerizable with addition-polymerizable oxazoline group-containing monomers, such as (meth)acrylic acid esters such as alkyl (meth)acrylates (alkyl groups include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, t-butyl, 2-ethylhexyl, and cyclohexyl groups); unsaturated carboxylic acids such as acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid, styrenesulfonic acid and their salts (sodium salt, potassium salt, ammonium salt, tertiary amine salt, etc.); unsaturated nitriles such as acrylonitrile and methacrylonitrile; (meth)acrylamide, N-alkyl Examples include unsaturated amides such as (meth)acrylamide and N,N-dialkyl(meth)acrylamide (alkyl groups include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, t-butyl, 2-ethylhexyl, and cyclohexyl groups); vinyl esters such as vinyl acetate and vinyl propionate; vinyl ethers such as methyl vinyl ether and ethyl vinyl ether; α-olefins such as ethylene and propylene; halogen-containing α,β-unsaturated monomers such as vinyl chloride and vinylidene chloride; and α,β-unsaturated aromatic monomers such as styrene and α-methylstyrene. One or more of these monomers can be used. Furthermore, from the viewpoint of improving adhesion, the amount of oxazoline groups in the oxazoline compound is preferably in the range of 0.5 to 10 mmol / g, more preferably 1 to 9 mmol / g, even more preferably 3 to 8 mmol / g, and particularly preferably 4 to 6 mmol / g.

[0076] In addition, this composition may contain various additives. Examples of additives include pigments, resin beads, defoamers, pigment dispersants, leveling agents, anti-sagging agents, curing catalysts, matting agents, UV absorbers, light stabilizers, antioxidants, heat resistance improvers, slip agents, preservatives, plasticizers, thickeners, wetting agents, and solvents. One or more additives may be used.

[0077] <Release agent layer> The release agent layer of this release film is formed from a polyolefin-based release agent composition (II) (hereinafter also referred to as "this release agent composition"). The thickness of the release agent layer is preferably 30 to 500 nm, more preferably 45 to 400 nm, and most preferably 60 to 300 nm. If the thickness of the release agent layer is 30 nm or more, there is no risk of excessive peeling, and if it is 500 nm or less, there is no risk of blocking or increased peeling force when wound into a roll.

[0078] The method for forming the release agent layer, that is, the method for producing a release film by forming a release agent layer on a resin layer on a polyester film, can be the same as the method for forming the resin layer described above, and is more preferably in-line coating.

[0079] <Polyolefin-based mold release agent composition (II)> The mold release agent composition is not particularly limited as long as it contains a polyolefin-based mold release agent component, and specifically, it can include those containing a polyolefin-based polymer. Examples of the polyolefin polymers include homopolymers and copolymers of α-olefins such as ethylene, propylene, butene, hexene, and octene. Among these, copolymers with ethylene as the main monomer (ethylene-based α-olefin copolymers) and / or copolymers with propylene as the main monomer (propylene-based α-olefin copolymers) are preferred. The α-olefin copolymer may be a random copolymer, a block copolymer, or a graft copolymer. Copolymers of ethylidene norbornene, norbornene, etc., with α-olefins such as ethylene are also examples. Furthermore, hydrocarbon-based elastomers such as diene rubbers obtained by living polymerization, typified by polyisoprene, polymers obtained by hydrogenating them, and elastomers obtained by ring-opening polymerization of cyclic olefins can also be used.

[0080] The density of the polyolefin polymer is not particularly limited, but is 0.92 g / cm³. 3 Preferably, it is 0.90 g / cm³. 3 The following is more preferable. Furthermore, the density of polyolefin polymers is typically 0.85 g / cm³. 3 That concludes the explanation. When the density of the polyolefin polymer is within the above range, it tends to have good mold release properties.

[0081] In addition, polyolefin elastomers, particularly those obtained by polymerization using metallocene catalysts, can also be used. Polymerization using metallocene catalysts yields polyolefin elastomers with a narrow molecular weight distribution and low molecular weight components. Furthermore, using a metallocene catalyst enables uniform copolymerization and suppresses the formation of low molecular weight components whose comonomer content deviates significantly from the average composition. As a result, stickiness when used as a release agent layer (coating) can be reduced, and the introduction of crosslinking groups to impart chemical resistance to the coating can be uniform. Consequently, efficient gelation is possible, resulting in a release agent layer with high chemical resistance, heat resistance, and coating strength.

[0082] The aforementioned polyolefin elastomer may be a modified polyolefin elastomer. Examples of modified polyolefin elastomers include those obtained by reacting a homopolymer or copolymer of olefin monomers with a compound having a functional group such as a hydroxyl group, amino group, carboxyl group, acid anhydride group, epoxy group or other cyclic ether group, or an isocyanate group. Other examples include polymers obtained by copolymerizing olefins as the main component with other reactive monomers. Polar groups can be introduced into the polyolefin chain by copolymerizing a meth(acrylate) monomer having a polar group with the monomer used to produce the polyolefin, or by reacting the above-mentioned polyolefin-based elastomer with a monomer having a polar group in solution, in a molten state, or in a suspension state in the presence of a radical initiator.

[0083] <Preferred polyolefin-based release agent composition (II)> A preferred embodiment of this release agent composition includes a composition comprising a non-reactive polyolefin, a reactive polyolefin, and a curing agent.

[0084] (Non-reactive polyolefin) The aforementioned non-reactive polyolefin is a polyolefin that is substantially non-reactive. More specifically, it means a polyolefin that does not react with the curing agent described later. The non-reactive polyolefin may be used alone or in combination of two or more types. From the viewpoint of mold release properties and heat resistance, it is preferable to use a polyethylene copolymer.

[0085] When using polyethylene copolymers, it is preferable to use those synthesized using transition metal catalysts such as Ziegler-Natta catalysts or metallocene catalysts. In particular, using those synthesized with metallocene catalysts has the advantage of yielding release films with excellent release properties and heat resistance. Specific examples of polyethylene copolymers include copolymers of ethylene and α-olefins, such as ethylene-propylene copolymers, ethylene-hexene copolymers, ethylene-butene copolymers, and ethylene-octene copolymers.

[0086] The ethylene unit content in the non-reactive polyolefin is not particularly limited, but is preferably 50% by mass or more and 80% by mass or less. When the ethylene unit content is 80% by mass or less, gel generation during coating is reduced, which tends to suppress pressure buildup in the filter and deterioration of the appearance of the release film, resulting in good productivity. Furthermore, a ethylene unit content of 50% by mass or more tends to provide sufficient release properties.

[0087] The content of the non-reactive polyolefin in this release agent composition (in the release agent layer) is preferably 80 to 99% by mass, more preferably 90 to 99% by mass. When the content is 80% by mass or more, the release properties are good and the peeling force tends to be low, and when it is 99% by mass or less, the curing component is not reduced too much and sufficient coating film strength tends to be obtained.

[0088] (Reactive polyolefins) Reactive polyolefins are polyolefins that can react with other components, such as curing agents, and can form a three-dimensional network structure when reacting with a curing agent. The formation of a three-dimensional network structure can impart heat resistance and chemical resistance to the release agent layer. Examples of the reactive polyolefins mentioned above include those obtained by modifying polyolefins using compounds that have functional groups in a molten or solution state, or those obtained by copolymerizing compounds that are reactive with ethylene or the like in the presence of a catalyst. The reactive group is not particularly limited, but examples include epoxy groups, hydroxyl groups, carboxyl groups, and acid anhydrides.

[0089] Specifically, there may be mentioned polyolefins having a hydroxyl group, an epoxy group or the like in the molecule, polyolefins modified with acrylic acid, methacrylic acid, maleic acid, maleic anhydride, itaconic acid, itaconic anhydride, aconitic acid, aconitic anhydride, fumaric acid, crotonic acid, citraconic acid, mesaconic acid, allyl succinic acid or the like, those having a half ester or a half amide of an unsaturated dicarboxylic acid, and the like. Among these, from the viewpoints of easy availability and peel strength after heating, a compound having at least one hydroxyl group on average in the molecule, specifically, a polyolefin polyol is preferable. <( From the viewpoint of substrate adhesion, an acid-modified polyolefin modified with maleic anhydride and having at least one group derived therefrom on average in the molecule is preferable.

[0090] In order to achieve both low peel strength and good adhesion to the substrate, the amount of the functional group contained in the reactive polyolefin is preferably 0.01 to 5% by mass, more preferably 0.01 to 1% by mass. Within this range, the peel strength is small and the adhesion between the substrate and the release agent layer tends to be good. Also, from the viewpoint of peel strength, the density of the reactive polyolefin is preferably 3 or less, particularly preferably 3 or less, particularly preferably 3 or less. The lower limit is not particularly limited, but is usually 3 or more.

[0091] Specific examples of reactive polyolefins include hydroxy(meth)acrylate modified ethylene-α-olefin copolymers, hydroxy(meth)acrylate modified polyethylene, hydroxy(meth)acrylate modified polypropylene, polyolefin polyols, (meth)acrylate modified ethylene-α-olefin copolymers having epoxy groups, (meth)acrylate modified polyethylene having epoxy groups, (meth)acrylate modified nuclear hydrogenated styrene-diene copolymers having epoxy groups, (meth)acrylate modified polypropylene having epoxy groups, and acid-modified ethylene-α-olefin copolymers. Among these, polyolefin polyols are preferred because they are readily available commercially. Furthermore, from the viewpoint of adhesion, maleic anhydride-modified ethylene-α-olefin copolymer is preferred.

[0092] Specific examples of polyolefin polyols include PolyTail H (hydroxylated hydrogenated polybutadiene) manufactured by Mitsubishi Chemical Corporation, Poly bd R-45HT (hydroxylated liquid polybutadiene) manufactured by Idemitsu Kosan Co., Ltd., Poly ip (hydroxylated liquid polyisoprene) manufactured by Idemitsu Kosan Co., Ltd., Epol (hydroxylated liquid hydrogenated polyisoprene) manufactured by Idemitsu Kosan Co., Ltd., GI-1000 (hydroxylated liquid hydrogenated polybutadiene) manufactured by Nippon Soda Co., Ltd., GI-2000 (hydroxylated liquid hydrogenated polybutadiene) manufactured by Nippon Soda Co., Ltd., and GI-3000 (hydroxylated liquid hydrogenated polybutadiene) manufactured by Nippon Soda Co., Ltd.

[0093] Examples of commercially available maleic anhydride-modified polyolefins include Mitsubishi Chemical's Modic series and Mitsui Chemicals' Toughmer series, such as MP-0620, MH-7020, and MA-8510. Reactive polyolefins may have multiple different types of functional groups in their molecules. Furthermore, the reactive polyolefin used in the present invention may be a composition comprising multiple reactive polyolefins.

[0094] Furthermore, the content of reactive polyolefin in this release agent composition (in the release agent layer before curing) is 0.2 to 20% by mass, preferably 0.5 to 10% by mass. A content of 0.2% by mass or more tends to result in good heat resistance and solvent resistance. Furthermore, having a composition of 20% by mass or less tends to result in good peelability and a lower peeling force.

[0095] (Hardening agent) Examples of curing agents include compounds that contribute to the crosslinking reaction and / or chain length extension reaction of the reactive polyolefin, thereby curing the release agent composition. Specifically, these include melamine compounds, oxazoline compounds, epoxy compounds, carbodiimide compounds, silane coupling compounds, isocyanate compounds, and the like. Among these, isocyanate compounds are particularly preferred from the viewpoint of reactivity.

[0096] Examples of the isocyanate compounds include tetramethylene diisocyanate, hexamethylene diisocyanate, tolylene diisocyanate, diphenylmethane diisocyanate, 1,5-naphthylene diisocyanate, tolidine diisocyanate, xylylene diisocyanate, tetramethyl xylylene diisocyanate, isophorone diisocyanate, hydrogenated xylylene diisocyanate, hydrogenated diphenylmethane diisocyanate, dimer acid diisocyanate, norbornene diisocyanate, trans-cyclohexane diisocyanate, hydrogenated tolylene diisocyanate, and other polyfunctional isocyanates such as adducts thereof, polyvalent alkylamines, and compositions thereof. Furthermore, from the viewpoint of the strength and heat resistance of the release agent layer, isocyanate compounds having two or more isocyanate groups in one molecule are preferred.

[0097] Furthermore, from the viewpoint of adhesion of the mold release agent layer, epoxy compounds are preferred. Examples of the epoxy compounds include N,N,N',N'-tetraglycidyl-m-xylenediline, diglycidylaniline, 1,3-bis(N,N-glycidylaminomethyl)cyclohexane (manufactured by Mitsubishi Gas Chemical Co., Ltd., trade name "Tetrad C"), 1,6-hexanediol diglycidyl ether (manufactured by Kyoeisha Chemical Co., Ltd., trade name "Epolite 1600"), neopentyl glycol diglycidyl ether (manufactured by Kyoeisha Chemical Co., Ltd., trade name "Epolite 1500NP"), ethylene glycol diglycidyl ether (manufactured by Kyoeisha Chemical Co., Ltd., trade name "Epolite 40E"), propylene glycol diglycidyl ether (manufactured by Kyoeisha Chemical Co., Ltd., trade name "Epolite 70P"), polyethylene glycol diglycidyl ether (manufactured by Nippon Oil & Fats Co., Ltd., trade name "Epiol E-400"), and polypropylene glycol diglycidyl ether (manufactured by Nippon Oil & Fats Co., Ltd.). Examples include: oil and fat company's product name "Epiol P-200", sorbitol polyglycidyl ether (Nagase ChemteX Co., Ltd.'s product name "Denacol EX-611"), glycerol polyglycidyl ether (Nagase ChemteX Co., Ltd.'s product name "Denacol EX-314"), pentaerythritol polyglycidyl ether, polyglycerol polyglycidyl ether (Nagase ChemteX Co., Ltd.'s product name "Denacol EX-512"), sorbitan polyglycidyl ether, trimethylolpropane polyglycidyl ether, diglycidyl adipate ester, diglycidyl o-phthalate ester, triglycidyl-tris(2-hydroxyethyl) isocyanurate, resorcinol diglycidyl ether, bisphenol-S-diglycidyl ether, and epoxy resins having two or more epoxy groups in the molecule.

[0098] Furthermore, melamine compounds are preferred in terms of heat resistance and chemical resistance. Examples of the melamine compounds include so-called melamine (1,3,5-triazine-2,4,6-triamine), in which an amino group is bonded to each of the three carbon atoms of a triazine ring, or compounds obtained by subjecting the amino groups of melamine to various modifications, and also include compounds in which multiple triazine rings are condensed. Modified compounds widely used include those in which some of the hydrogen atoms of the three amino groups are alkylated or methylolated. Generally, methylolated or unsubstituted hydrogen atoms are more reactive than alkylated ones, allowing for the selection of an appropriate type of melamine compound depending on the application. Among these, preferred are those with an average of 3 or fewer triazine ring condensation numbers and at least one or more amino groups being alkylated, as these are superior in terms of dispersibility in solvents and reactivity with resins. Examples of commercially available melamine compounds include Yuban 60R (isobutylated melamine resin) from Mitsui Chemicals, the Cymel series from Nippon Scitec Industries, Sumimar from Sumitomo Chemical, and Amidia from DIC.

[0099] Based on the above, it is preferable that the curing agent be selected from the group consisting of isocyanates having two or more isocyanate groups in one molecule, epoxy compounds, and melamine compounds. The crosslinking agent content in this release agent composition (in the release agent layer before curing) is 0.05 to 20% by mass, with a preferred lower limit of 0.1% by mass, more preferably 0.5% by mass, and a preferred upper limit of 10% by mass. On the other hand, a content of 0.05% by mass or more tends to result in good heat resistance and solvent resistance. Furthermore, having a content of 20% by mass or less tends to result in good peelability and a weaker peeling force.

[0100] (Other ingredients) This release agent composition may also contain, as needed, olefin resins other than the reactive and non-reactive polyolefins, paraffin, paraffin wax, process oil, antioxidants, ultraviolet absorbers, light stabilizers such as hindered amine light stabilizers, antistatic agents, fillers such as carbon black, calcium oxide, magnesium oxide, silica, zinc oxide, and titanium dioxide, pigments, catalysts, etc.

[0101] Furthermore, a catalyst may be added to this release agent composition to accelerate the reaction of the release agent layer. The type of catalyst is not particularly limited, but when an isocyanate is used as a curing agent, it is preferable to use a curing catalyst to accelerate the reaction between it and the reactive polyolefin. When using isocyanates as curing agents, suitable curing catalysts include tertiary amines, carboxylate salts of tertiary amines, metal carboxylate salts (such as potassium acetate, potassium octoate, and stanus octoate), and organometallic compounds (such as dibutyltin dilaurate), with tertiary amines being preferred.

[0102] Examples of the tertiary amines include triethylenediamine, N-ethylmorpholine, N-methylpiperidine, pyrrolidine, quinuclidine, 1,4-diazabicyclo[2.2.2]octane, diethylethanolamine, N,N,N',N'-tetramethylhexamethylenediamine, 1,2-dimethylimidazole, 1-isobutyl-2-methylimidazole, 1,8-diazabicyclo-[5.4.0]-undecene-7 (carboxylate), and bis(dimethylaminoethyl) ether (carboxylate), and two or more of these may be used in combination.

[0103] Furthermore, when epoxy compounds are used as curing agents, suitable curing catalysts include tertiary amines such as benzyldimethylamine, tris(dimethylaminemethyl)phenol, and dimethylcyclohexylamine; imidazoles such as 2-ethyl-4-methylimidazole, 2-methylimidazole, and 1-benzyl-2-methylimidazole; diazabicycloalkenes such as 1,8-diazabicyclo[5.4.0]undecene-7 and 1,4-diazabicyclo[2.2.2]octane, and their salts; organometallic compounds such as zinc octate, tin octate, and aluminum acetylacetone complexes; organophosphine compounds such as triphenylphosphine; and quaternary ammonium compounds.

[0104] The content of the curing catalyst is not particularly limited, but from the viewpoint of promoting the reaction, it is preferably 0.01% by mass or more, more preferably 0.03% by mass or more, and even more preferably 0.05% by mass or more. On the other hand, 5% by mass or less is preferred, 4% by mass or less is more preferred, and 3% by mass or less is even more preferred. Furthermore, when using a melamine compound as a curing agent, it is preferable to use an acid curing catalyst to promote the reaction between the melamine compound and the reactive polyolefin.

[0105] As the acid curing catalyst, for example, phosphoric anhydride or aryl sulfonic anhydride are preferred. Examples of aryl sulfonic anhydride include p-toluenesulfonic acid, xylenesulfonic acid, phenolsulfonic acid, substituted phenolsulfonic acid, xylenolsulfonic acid, substituted xylenolsulfonic acid, dodecylbenzenesulfonic acid, benzenesulfonic acid, naphthalenesulfonic acid, etc., and these may be used individually or in combination of two or more types. Furthermore, resorcinol, cresol, saligenin (o-methylolphenol), p-methylolphenol, etc. may be added as curing aids. The content of the acid curing catalyst in this release agent composition (in the release agent layer before curing) is not particularly limited, but from the viewpoint of promoting the reaction, it is preferably 0.01% by mass or more, more preferably 0.03% by mass or more, and even more preferably 0.05% by mass or more. On the other hand, the upper limit is preferably 5% by mass or less, more preferably 4% by mass or less, and even more preferably 3% by mass or less.

[0106] <Physical properties of release film> The normal peeling force of this release film is preferably 1 mN / cm or more and 75 mN / cm or less, and more preferably 1 mN / cm or more and 70 mN / cm or less. A normal peel strength of 75 mN / cm or less allows for the use of various adhesives when used as an adhesive material. From this viewpoint, a normal peel strength of 75 mN / cm or less is preferable for a light-release film used as an adhesive material.

[0107] <Adhesive material> This release film can be provided as an adhesive body in which an adhesive layer is laminated on a release agent layer. The adhesive used in the adhesive layer of the adhesive body is not particularly limited, but examples include rubber-based, acrylic-based, and polyester-based adhesives. Among these, acrylic-based and polyester-based adhesives are preferred because they provide stable release properties. The aforementioned acrylic adhesive can be prepared by using an acrylic polymer obtained by conventional polymerization methods such as solution polymerization, emulsion polymerization, or UV polymerization as the main component, and adding various additives such as crosslinking agents, tackifiers, softeners, antioxidants, and fillers as needed. As the acrylic polymer, for example, a copolymer of monomer mixtures is used in which alkyl (meth)acrylates such as butyl (meth)acrylate and 2-ethylhexyl (meth)acrylate are mainly components, and other monomers such as hydroxyl group-containing monomers such as 2-hydroxyethyl (meth)acrylate, carboxyl group-containing monomers such as (meth)acrylic acid, styrene monomers such as styrene, and vinyl esters such as vinyl acetate are added as copolymerizable modifier monomers as needed.

[0108] Furthermore, examples of polyester adhesives include adhesives that primarily consist of a polyester polymer in which an aliphatic carbonate diol (for example, a carbonate diol obtained by the reaction of a diol component such as butanediol with a carbonate compound such as ethylene carbonate) is an essential polyol component.

[0109] Furthermore, the adhesive layer can be formed, for example, by applying a solution containing an adhesive onto the release agent layer of the release film and drying it. The thickness of the adhesive layer can be appropriately selected considering tackiness and other factors, and is usually 3 to 100 μm, preferably 5 to 90 μm, and more preferably 10 to 80 μm. [Examples]

[0110] The present invention will be described in more detail below based on examples, but the present invention is not limited in any way by the following examples.

[0111] The measurement methods used in the examples and comparative examples are as follows:

[0112] (1) Measurement of average particle size (d50: μm) The measurements were performed using a zeta potential, particle size, and molecular weight measurement system (ELSZ-2000ZS, manufactured by Otsuka Electronics Co., Ltd.).

[0113] (2) Evaluation of the normal peeling force of the release film After attaching one side of double-sided adhesive tape (Nitto Denko "No. 31B") to the surface of the release agent layer of the sample film, it was cut to a size of 50 mm x 300 mm, and the peel strength was measured after being left at room temperature for 1 hour. The peel strength was measured using a tensile testing machine (Intesco "Intesco Model 2001") at a tensile speed of 300 mm / min and peeled at 180°.

[0114] (3) Evaluation of the adhesion of the release agent layer of the release film The surface of the release agent layer of the sample film immediately after coating was rubbed five times with a hand, and the degree of detachment of the release agent layer and the retention of release properties were evaluated according to the following criteria. "Judgment criteria" ○: No peeling of the paint film is observed, or the paint film turns white but does not peel off, and the release properties are the same as before rubbing. △: The coating turns white, and while the release properties are better than the original material, they are worse than before rubbing. ×: Coating peeling was observed, and the release properties were severely delaminating, similar to the original material.

[0115] (4) Evaluation of the retention of release properties After the adhesion evaluation described above, one side of a double-sided adhesive tape (Nitto Denko Corporation's "No. 31B") was attached to the surface of the release agent layer, and the peeling force was measured in accordance with (2) above after being manually left at room temperature for 1 hour.

[0116] Next, the materials used in the examples and comparative examples are as follows:

[0117] (1) Raw materials for polyester film substrates (i) Polyester P1 • Polyethylene terephthalate homopolymer chips (intrinsic viscosity: 0.66 dl / g) (ii) Polyester P2 • A polyethylene terephthalate homopolymer chip containing 1000 ppm of amorphous silica with an average particle size of 2 μm (intrinsic viscosity: 0.62 dl / g)

[0118] (2) Raw materials for the resin layer (i) Aqueous resin dispersion of olefin polymer (A) • Aptrock® BW-5635 (aqueous dispersion of a modified olefin polymer having a carboxyl group as a reactive group, median diameter 88 nm, solids content 30%), manufactured by Mitsubishi Chemical Corporation. (ii) Hardener • Manufactured by Nippon Shokubai Co., Ltd., Epocross® WS500 (oxazoline compound) (iii) Additives • Spherical silica with an average particle size of 70 nm

[0119] (3) Raw materials for the release agent layer (i) Non-reactive polyolefin (C1) • Ethylene-propylene copolymer Ethylene-propylene random copolymer obtained by metallocene catalyst ( 1 Composition mass ratio determined by H-NMR: Ethylene / Propylene = 72 / 28, MFR (230°C, load 2.16 kg) 2.0 g / 10 min, density 0.86 g / cm³ 3 ). (ii) Reactive polyolefin (C2) • Manufactured by Mitsubishi Chemical Corporation, Polytail H (Hydrogenated polybutadiene with hydroxyl groups, number average molecular weight 2700, hydroxyl group content 1.5% by mass as determined by NMR, density 0.85 g / cm³) 3 ) (iii) Hardener (C3) • Mitsui Chemicals, Ltd., Takenate D160N (Hexamethylene diisocyanate and trimethylolpropane adduct adduct / %NCO 12.8% / Solids content 75%) (iv) Curing catalyst (C4) • 1,4-diazabicyclo[2,2,2]octane, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.

[0120] [Example 1] (1) Preparation of polyester film substrate Polyester P1 was used as the raw material for the intermediate layer, and polyester P2 was used as the raw material for the surface layer. Each raw material was melt-extruded using a separate melt extruder to obtain an amorphous sheet consisting of two types of three layers: surface layer / intermediate layer / surface layer. The resulting amorphous sheet was co-extruded onto a cooled casting drum and cooled and solidified to obtain an unoriented sheet. Next, it was stretched 3.4 times in the machine direction (longitudinal direction) at 90°C.

[0121] (2) Formation of the resin layer A coating solution (total 100% by mass, based on total solids content) consisting of an aqueous resin dispersion of the above-mentioned olefin polymer (A) (hereinafter referred to as "aqueous resin dispersion (A)") (59% by mass), the above-mentioned curing agent (33% by mass), the above-mentioned additives (6% by mass), and other additives (2% by mass) was applied to the polyester film substrate. After this, a preheating process was carried out in a tenter, followed by stretching to 4.3 times its original width (lateral direction) at 110°C, and then heat treatment was performed at 230°C to form a resin layer on the polyester film substrate. The resulting polyester film substrate with a resin layer had a thickness of 50 μm, and the thickness of the resin layer was 0.02 μm.

[0122] (3) Formation of the release agent layer A 2% toluene solution was obtained by heating the ethylene-propylene copolymer, which was the non-reactive polyolefin (C1), and polytail H, which was the reactive polyolefin (C2), together with toluene. A mold release agent solution was obtained by mixing a mold release agent layer forming composition (hereinafter sometimes abbreviated as "mold release agent") such that the composition of the solid content in the composition was ethylene-propylene copolymer (C1) / polytail H (C2) / takenate D160N (C3) / 1,4-diazabicyclo[2,2,2]octane (C4) = 95 / 3 / 1 / 1 (parts by mass). The release agent solution was applied to the resin layer of the resin-coated polyester film obtained above using a Meyer bar, and dried for 30 seconds in a 150°C dryer to obtain a release film having a release agent layer with a thickness of 0.2 μm. The evaluation results for this release film are shown in Table 1.

[0123] [Comparative Example 1] A release film was obtained by manufacturing in the same manner as in Example 1, except that aqueous resin dispersion (A) of Example 1 was replaced with aqueous resin dispersion (A'1). The evaluation results are shown in Table 1.

[0124] (Aqueous resin dispersion (A'1)) • Maleic anhydride-modified polypropylene (aqueous dispersion, median diameter 3590 nm, solids content concentration 30%)

[0125] [Comparative Example 2] A release film was obtained by manufacturing in the same manner as in Example 1, except that aqueous resin dispersion (A) of Example 1 was replaced with aqueous resin dispersion (A'2). The evaluation results are shown in Table 1.

[0126] (Aqueous resin dispersion (A'2)) • Polyester and polyacrylate-based (aqueous dispersion, solid content concentration 30%)

[0127] [Comparative Example 3] A release film was obtained by manufacturing in the same manner as in Example 1, except that the resin layer in Example 1 was omitted. The evaluation results are shown in Table 1.

[0128] [Comparative Example 4] A release film was obtained by manufacturing in the same manner as in Example 1, except that the release agent layer was omitted. The evaluation results are shown in Table 1.

[0129] [Table 1] [Industrial applicability]

[0130] The release film of the present invention uses a non-silicone-based release agent, and because the release agent layer has good adhesion, release performance can be ensured even after friction on the surface of the release agent layer. Therefore, the release film of the present invention can be suitably used in precision applications such as electronic components, for example, hard disk drives.

Claims

1. It comprises a polyester film substrate, a resin layer, and a release agent layer, The resin layer is provided between the polyester film substrate and the release agent layer, The resin layer is formed from a resin composition (I) containing an aqueous resin dispersion of a polymer (X) including an olefin polymer (A), The median diameter of the aqueous resin dispersion, as measured by dynamic light scattering, is 300 nm or less. The aforementioned release agent layer is formed from a polyolefin-based release agent composition (II), The aqueous resin dispersion of the polymer (X) is a release film in which an olefin polymer (A) and a polymer (B) containing constituent units derived from a radically polymerizable monomer having a reactive functional group are dispersed in an aqueous medium.

2. comprising a polyester film substrate, a resin layer and a release agent layer, The resin layer is provided between the polyester film substrate and the release agent layer, The resin layer is formed from a resin composition (I) containing an aqueous resin dispersion of a polymer (X) including an olefin polymer (A), The median diameter of the aqueous resin dispersion, as measured by dynamic light scattering, is 300 nm or less. The aforementioned release agent layer is formed from a polyolefin-based release agent composition (II), The polyolefin-based release agent composition (II) comprises an α-olefin homopolymer or copolymer, The polyolefin-based release agent composition (II) further contains a polyolefin polyol, comprising a release film.

3. The release film according to claim 2, wherein the α-olefin homopolymer or copolymer is an ethylene-α-olefin copolymer or a propylene-α-olefin copolymer.

4. The release film according to claim 2 or 3, wherein the polyolefin-based release agent composition (II) further contains an isocyanate compound.

5. The release film according to any one of claims 1 to 4, wherein the olefin polymer (A) is a modified olefin polymer having a reactive group.

6. The release film according to claim 5, wherein the reactive group is a carboxyl group and its anhydride.

7. The release film according to any one of claims 1 to 6, wherein the resin composition (I) further comprises a curing agent.

8. The release film according to claim 7, wherein the curing agent is an oxazoline compound.

9. An adhesive having an adhesive layer on a release agent layer of a release film according to any one of claims 1 to 8.

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