Release film and release resin composition

Abstract

To provide a release film and a releasable resin composition which do not contain silicone, and have good easy releasability with respect to various adhesives.SOLUTION: A release film has at least two layers, which are a release layer (A) and a base material layer (B). The release layer (A) contains a polyethylene resin composition containing an ethylene-propylene copolymer having at least the following (c-1) to (c-5): (c-1) the ethylene-propylene copolymer contains 80-98 mol% of ethylene-derived constitutional unit and 2-20 mol% of propylene-derived constitutional unit, and may contain 7 mol% or less of third α-olefin-derived constitutional unit; (c-2) MFR is 1-100 g / 10 min; (c-3) density is 0.88-0.94 g / cm3; (c-4) a total amount of vinyl and vinylidene in the ethylene-propylene copolymer is 0.20 (piece / total 1,000C) or more; and (c-5) the number (Y) of branches formed of a comonomer in the ethylene-propylene copolymer and the density (X) satisfy a specific expression.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This invention relates to a release film and a release resin composition for forming its release layer. In this invention, the term "film" used in "release film" is used to include sheets as well. [Background technology]

[0002] Release films have a release layer on at least one side of the substrate and are widely used to protect adhesive or bonding surfaces. The release resin compositions that constitute the release layer (hereinafter also referred to as "release agents") are broadly classified into silicone-based release agents and non-silicone-based release agents.

[0003] While silicone-based mold release agents offer excellent ease of removal, in the fields of electronic and electrical equipment, the small amount of siloxane-based gases generated can cause corrosion and contact problems.

[0004] Non-silicone mold release agents include mold release agents that reduce surface energy using halogen compounds such as fluorides, and polyvinylcarbamate (PVA and C), which is a long-chain alkyl group-containing polymer. 18 H 37 A release agent consisting of a reaction product with NCO, polyethyleneimine and C 18 H 37 Release agents consisting of reaction products with NCO, release agents consisting of copolymers mainly composed of perfluoroalkyl vinyl, and release agents consisting of polyethylene resin compositions have been proposed.

[0005] Non-silicone release agents have the advantage of not generating siloxane-based gases. However, generally, non-silicone release agents require a greater release force than silicone-based release agents. Furthermore, non-silicone release agents have specific problems depending on the material system used, as described below.

[0006] For example, mold release agents that reduce surface energy using halogen compounds such as fluorides do not align with the current trend of de-halogenation to reduce the environmental burden in waste disposal. Furthermore, mold release agents composed of copolymers primarily made of perfluoroalkyl vinyl have excellent peelability, but their applications are severely limited because they are generally insoluble in organic solvents and only dissolve in special, expensive solvents such as FR thinner.

[0007] Furthermore, release agents made from polyethylene resin compositions include release agents mainly composed of low-density polyethylene resin (see, for example, Patent Document 1) and release agents mainly composed of high-density polyethylene resin (see, for example, Patent Documents 2 and 3). Release agents mainly composed of low-density polyethylene resin require a large peeling force, and when used as a protective film for a pressure-sensitive adhesive layer, they have problems such as a portion of the adhesive layer migrating to the surface of the release layer during peeling, or causing a type of peeling called stick-slip, where the surface shape of the adhesive layer after peeling becomes pulsed. Release agents mainly composed of high-density polyethylene resin have problems such as poor adhesion to the substrate and a large peeling force when a polar polymer is used as the substrate. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] Special Publication No. 11-508958 [Patent Document 2] Japanese Patent Publication No. 2000-239624 [Patent Document 3] Japanese Patent Publication No. 2000-119411 [Overview of the Initiative] [Problems that the invention aims to solve]

[0009] In view of the above-mentioned problems, the object of the present invention is to provide a release film and a release resin composition that do not contain silicone and have good release properties for various adhesives. [Means for solving the problem]

[0010] As a result of diligent research to solve the above problems, the inventors have fabricated an ethylene-propylene copolymer having the new properties in the following new range (c-1) to (c-6). Furthermore, they have found that a laminate formed by creating a release layer on a substrate layer using such an ethylene-propylene copolymer having specific properties, that is, an ethylene-propylene copolymer containing predetermined amounts of ethylene as the main component and propylene as the secondary component, with a density and MFR within a certain range, a large amount of double bonds in the copolymer, and a high number of branches, preferably further containing a specific high-pressure radical polymerization low-density polyethylene, exhibits excellent peelability from adhesive tape, thus completing the present invention. Furthermore, recent research by the applicant has shown that this type of ethylene-propylene copolymer exhibits good adhesion as an adhesive resin between aluminum and other substrates. However, unexpectedly, we have now discovered that it also possesses easy peelability from adhesive surfaces through a different mechanism, and the present invention provides new applications in the form of release films and release resin compositions.

[0011] That is, according to the first invention of the present invention, the material has at least two layers, a release layer (A) and a substrate layer (B), A release layer (A) is formed either directly on the base layer (B) or on another resin layer laminated on the base layer, and a release layer (A) is provided that satisfies the following characteristics. Release layer (A): Contains a polyethylene resin composition (E) containing an ethylene-propylene copolymer (C) having the following properties (c-1) to (c-6). (c-1) Contains 80-98 mol% of constituent units derived from ethylene as the main component, 2-20 mol% of constituent units derived from propylene as an essential minor component, and may also contain 7 mol% or less of constituent units derived from a third α-olefin other than ethylene and propylene as a minor component. (However, when including a structural unit derived from the third α-olefin, the total of the structural unit derived from ethylene, the structural unit derived from propylene, and the structural unit derived from the third α-olefin does not exceed 100 mol%) (c-2) MFR (190 °C, 21.18 N load) is 1 to 100 g / 10 min (c-3) Density is 0.88 to 0.94 g / cm 3 (c-4) The total amount of vinyl and vinylidene in the ethylene-propylene copolymer is 0.20 (per 1000C total) or more (However, the number of vinyl and vinylidene is the number per 1000 carbon atoms in the total of the main chain and side chain measured by NMR.) (c-5) The number of branches (Y) due to the comonomer in the ethylene-propylene copolymer and the density (X) satisfy the relationship of the following formula (1). Formula (1): (Y) ≥ -566 × (X) + 540 (However, Y is the number per 1000 carbon atoms in the total of the main chain and side chain measured by NMR.) (c-6) In the infrared absorption spectrum obtained by Fourier transform infrared spectroscopy using the total reflection measurement method with a diamond prism on the surface of a sample obtained by hot pressing the ethylene-propylene copolymer to a thickness of 1 mm, from a wavelength of 1400 cm -1 to a wavelength of 1290 cm -1 When drawing a baseline in the range, the absorbance (D1368) at a wavelength of 1368 cm -1 For, the absorbance (D1260) at a wavelength of 1260 cm when drawing a baseline in the range from a wavelength of 1280 cm -1 to a wavelength of 1240 cm -1 and the absorbance (D1089) at a wavelength of 1089 cm when drawing a baseline in the range from a wavelength of 1110 cm -1 to a wavelength of 1080 cm -1 and the absorbance (D1019) at a wavelength of 1019 cm when drawing a baseline in the range from a wavelength of 1040 cm -1 to a wavelength of 1000 cm -1 and the absorbance (D1019) at a wavelength of 1019 cm when drawing a baseline in the range from a wavelength of 1040 cm -1 to a wavelength of 1000 cm -1 and the absorbance (D1019) at a wavelength of 1019 cm when drawing a baseline in the range from a wavelength of 1040 cm -1 and the absorbance (D1019) at a wavelength of 1019 cm when drawing a baseline in the range from a wavelength of 1040 cm -1From wavelength 777cm -1 When a baseline is drawn within this range, the wavelength is 797 cm. -1 The ratios of the absorbances (D797) for each element, namely (D1260 / D1368), (D1089 / D1368), (D1019 / D1368), and (D797 / D1368), are all 0.10 or less.

[0012] Furthermore, according to the second invention of the present invention, a release film is provided characterized in that, in the first invention, the ethylene-propylene copolymer (C) further satisfies the following relationship (c-5'). (c-5') The number of branches (Y) and density (X) of comonomers in an ethylene-propylene copolymer satisfy the relationship shown in equation (2) below. Equation (2): (Y) ≥ -1360 × (X) + 1270 (However, Y is the number of carbon atoms per 1000 total carbon atoms in the main chain and side chains as measured by NMR.)

[0013] Furthermore, according to the third invention of the present invention, a release film is provided characterized in that, in the first and second inventions, the polyethylene resin composition (E) further contains high-pressure radical polymerization low-density polyethylene (D) having the following properties (d-1) to (d-2). (d-1) MFR (190℃, 21.18N load) is 0.1~20g / 10min (d-2) Density of 0.915~0.930 g / cm³ 3

[0014] Furthermore, according to the fourth invention of the present invention, a release film is provided, characterized in that, in any of the first to third inventions, the polyethylene resin composition (E) contains 95 to 10% by weight of ethylene-propylene copolymer (C) and 5 to 90% by weight of low-density polyethylene (D) produced by high-pressure radical polymerization.

[0015] Furthermore, according to the fifth invention of the present invention, a release film is provided characterized in that, in any of the first to fourth inventions, the polyethylene resin composition (E) further satisfies the following properties (e-1) to (e-2). (e-1) MFR is 1-100g / 10min (e-2) Density of 0.88~0.94 g / cm³ 3

[0016] Furthermore, according to the sixth invention of the present invention, a release film is provided characterized in that, in any of the first to fifth inventions, the polyethylene resin composition (E) further satisfies the following properties (e-1') to (e-2'). (e-1) MFR of 5-60g / 10 minutes (e-2) Density of 0.88~0.92 g / cm³ 3

[0017] Furthermore, according to the seventh invention of the present invention, a release film is provided, characterized in that, in any of the first to sixth inventions, the release layer (A) is formed on the substrate layer (B) by an extrusion coating method.

[0018] Furthermore, according to the eighth aspect of the present invention, a releaseable resin composition is provided, characterized in that it is a polyethylene resin composition containing an ethylene-propylene copolymer (C) having the following properties (c-1) to (c-6). (c-1) Contains 80-98 mol% of constituent units derived from ethylene as the main component, 2-20 mol% of constituent units derived from propylene as an essential minor component, and may also contain 7 mol% or less of constituent units derived from a third α-olefin other than ethylene and propylene as a minor component. (However, if the material contains constituent units derived from the third α-olefin, the sum of constituent units derived from ethylene, propylene, and the third α-olefin shall not exceed 100 mol%.) (c-2) MFR (190℃, 21.18N load) is 1-100g / 10min (c-3) Density of 0.88~0.94 g / cm³ 3 (c-4) The total amount of vinyl and vinylidene in the ethylene-propylene copolymer is 0.20 (particles / total 1000C) or more. (However, the number of vinyl and vinylidene atoms is the number per 1000 carbon atoms in the main chain and side chains, as measured by NMR.) (c-5) The relationship between the number of branches (Y) and the density (X) of comonomers in an ethylene-propylene copolymer is given by the following equation (1). Equation (1): (Y) ≥ -566 × (X) + 540 (However, Y is the number of carbon atoms per 1000 total carbon atoms in the main chain and side chains as measured by NMR.) (c-6) In the infrared absorption spectrum obtained by Fourier transform infrared spectroscopy analysis using total internal reflection measurement with a diamond prism on the surface of a sample obtained by hot pressing an ethylene-propylene copolymer to a thickness of 1 mm, at a wavelength of 1400 cm -1 From wavelength 1290 cm -1 When a baseline is drawn within this range, the wavelength is 1368 cm. -1 For the absorbance (D1368), at a wavelength of 1280 cm -1 From wavelength 1240cm -1 The wavelength when drawing a baseline within this range is 1260 cm. -1 Absorbance (D1260) and wavelength 1110 cm -1 From wavelength 1080 cm -1 When a baseline is drawn within this range, the wavelength is 1089 cm². -1 Absorbance (D1089), wavelength 1040 cm -1 From wavelength 1000cm -1 When a baseline is drawn within this range, the wavelength is 1019 cm. -1 Absorbance (D1019), wavelength 817 cm -1 From wavelength 777cm -1 When a baseline is drawn within this range, the wavelength is 797 cm. -1 The ratios of the absorbances (D797) of each element, namely (D1260 / D1368), (D1089 / D1368), (D1019 / D1368), and (D797 / D1368), are all less than or equal to 0.10. [Effects of the Invention]

[0019] The release film and release resin composition of the present invention do not contain silicone, yet exhibit excellent release performance from adhesive surfaces, and fully satisfy the inherent requirements for a release agent. [Brief explanation of the drawing]

[0020] [Figure 1] Figure 1 is a schematic diagram showing a cross-section of an example of the laminate of the present invention. [Figure 2] Figure 2 is a schematic diagram showing a cross-section of another example of the laminate of the present invention. [Figure 3] Figure 3 shows the relationship between the density of ethylene-propylene copolymer or other ethylene-α-olefin copolymer and the tape peel strength. [Explanation of symbols]

[0021] 1 Base material layer (B) 2. A different resin layer from the release layer (A) 3. Delamination layer (A) [Modes for carrying out the invention]

[0022] The present invention relates to a laminate characterized by comprising a release layer containing a polyethylene resin composition comprising a specific ethylene-propylene copolymer and preferably a specific high-pressure radical polymerization low-density polyethylene, and a base layer whose surface in contact with the release layer is a film mainly composed of paper, polypropylene resin, polyethylene terephthalate resin, or nylon resin. The following describes in detail each component used in the present invention and the laminates using them.

[0023] 1. Polyethylene resin composition (E) The polyethylene resin composition of the present invention (hereinafter also simply referred to as the resin composition) is characterized by containing ethylene-propylene copolymer (C), and more preferably contains high-pressure radical polymerization low-density polyethylene (D), and more preferably contains 95-10% by weight of ethylene-propylene copolymer (C) and 5-90% by weight of high-pressure radical polymerization low-density polyethylene (D).

[0024] (1) Ethylene-propylene copolymer (C) The ethylene-propylene copolymer (C) used in the present invention has the following properties (c-1) to (c-6). (c-1) Contains 80-98 mol% of constituent units derived from ethylene as the main component, 2-20 mol% of constituent units derived from propylene as an essential minor component, and may also contain 7 mol% or less of constituent units derived from a third α-olefin other than ethylene and propylene as a minor component. (However, if the material contains constituent units derived from the third α-olefin mentioned above, the total amount of constituent units derived from ethylene, propylene, and the third α-olefin shall not exceed 100 mol%.) (c-2) MFR (190℃, 21.18N load) is 1-100g / 10min (c-3) Density of 0.88~0.94 g / cm³ 3 (c-4) The total amount of vinyl and vinylidene in the ethylene-propylene copolymer is 0.20 (particles / total 1000C) or more. (However, the number of vinyl and vinylidene atoms is the number per 1000 carbon atoms in the main chain and side chains, as measured by NMR.) (c-5) The relationship between the number of branches (Y) and the density (X) of comonomers in an ethylene-propylene copolymer is given by the following equation (1). Equation (1): (Y) ≥ -566 × (X) + 540 (However, Y is the number of carbon atoms per 1000 total carbon atoms in the main chain and side chains as measured by NMR.) (c-6) In the infrared absorption spectrum obtained by Fourier transform infrared spectroscopy analysis using total internal reflection measurement with a diamond prism on the surface of a sample obtained by hot pressing an ethylene-propylene copolymer to a thickness of 1 mm, at a wavelength of 1400 cm -1 From wavelength 1290 cm -1 When a baseline is drawn within this range, the wavelength is 1368 cm. -1 For the absorbance (D1368), at a wavelength of 1280 cm -1 From wavelength 1240cm -1 The wavelength when drawing a baseline within this range is 1260 cm. -1 Absorbance (D1260) and wavelength 1110 cm -1 From wavelength 1080 cm -1 When a baseline is drawn within this range, the wavelength is 1089 cm². -1 Absorbance (D1089), wavelength 1040 cm -1 From wavelength 1000cm -1 When a baseline is drawn within this range, the wavelength is 1019 cm. -1 Absorbance (D1019), wavelength 817 cm -1 From wavelength 777cm -1 When a baseline is drawn within this range, the wavelength is 797 cm. -1 The ratios of absorbance (D797) to (D1260 / D1368), (D1089 / D1368), (D1019 / D1368), and (D797 / D1368) are all 0.10 or less.

[0025] Furthermore, a copolymer composed of ethylene and propylene is known as ethylene-propylene rubber (EPM), which contains more than 20 mol% of propylene and has a density of 0.870 g / cm³. 3 While rubbery polymers obtained by the following solution polymerization methods are used in the field of elastomers, the ethylene-propylene copolymer (C) of the present invention is a polymer that differs from these ethylene-propylene rubbers in its density range, the amount of ethylene and propylene it contains, and its physical properties, among other things. Furthermore, while propylene-ethylene copolymers containing a small amount of ethylene components during the manufacturing process are also known, these differ significantly from the ethylene-propylene copolymer (C) of the present invention in terms of their propylene content and other characteristics, and are polymers with completely different physical properties. Furthermore, ethylene-α-olefin copolymers with a typical linear molecular structure (e.g., LLDPE) are mainly developed for film applications. Therefore, they typically use C4 or C6 α-olefins as the main comonomer component to obtain high-strength copolymers. However, this copolymer, composed of ethylene and propylene, uses C3 comonomers as the main minor component, resulting in lower strength, and has a density of 0.88 g / cm³. 3 The copolymers described above have received little attention until now, and have not been commercially available, at least not by the present applicant. In this study, we have newly fabricated an ethylene-propylene copolymer using a C3 comonomer in the aforementioned density range as the main minor component, and after various investigations, we have found that the effects of the present invention can be obtained in a laminate containing a polyethylene resin composition with a release layer made of an ethylene-propylene copolymer having new physical properties in the ranges of (c-1) to (c-6).

[0026] (i) Properties of ethylene-propylene copolymer (C) (c-1) Monomer composition The ethylene-propylene copolymer (C) used in the present invention is an ethylene-propylene copolymer characterized by containing 80 to 98 mol% of constituent units derived from ethylene as the main component and 2 to 20 mol% of constituent units derived from propylene as a minor component. A specific example is a copolymer polymerized by catalytic polymerization, which is a copolymer polymerized in a substantially linear and random manner. A specific example is a random copolymer of ethylene and propylene. Preferably, the constituent units derived from ethylene are 82 to 97 mol%, the constituent units derived from propylene are 3 to 18 mol%, and more preferably, the constituent units derived from ethylene are 85 to 95 mol%, and the constituent units derived from propylene are 5 to 15 mol%. Here, the monomer amounts such as the ethylene content are values ​​measured and calculated by 13C-NMR under the conditions described in the examples described later.

[0027] Furthermore, a composition that does not contain any other α-olefins, particularly α-olefins having 4 to 20 carbon atoms, and other monomer components is preferred, but such components may be included in substantially trace amounts. In this specification, α-olefins other than ethylene and propylene are referred to as third α-olefins. The ethylene-propylene copolymer (C) of the present invention may contain, for example, 7 mol% or less, preferably 7 mol% or less, more preferably 5 mol% or less, even more preferably 1 mol% or less, and most preferably 0.5 mol% or less of constituent units derived from third α-olefins other than ethylene and propylene as minor components. Here, if the ethylene-propylene copolymer (C) of the present invention contains constituent units derived from third α-olefins, the total of constituent units derived from ethylene, constituent units derived from propylene, and constituent units derived from third α-olefins does not exceed 100 mol%. In this case, it is preferable that the content of constituent units derived from propylene is higher than the content of constituent units derived from third α-olefins. Furthermore, if the ethylene-propylene copolymer (C) of the present invention contains a constituent unit derived from a third α-olefin, one or more third α-olefins can be used. Furthermore, the ethylene-propylene copolymer (C) may be one type or a combination of two or more types, as long as it satisfies (c-1) to (c-6).

[0028] When propylene is used as an essential comonomer as a minor component, and especially when a high-pressure ionic polymerization method using a metallocene catalyst, as described later, is employed, it is possible to obtain ethylene-α-olefin copolymers with a particularly high total number of vinyl and vinylidene molecules. This effect is difficult to obtain when α-olefins such as 1-butene, 1-hexene, and 1-octene are used as the main comonomer components during polymerization.

[0029] (c-2) MFR The ethylene-propylene copolymer (C) used in the present invention has a melt flow rate (MFR: 190°C, 21.18N load) of 1 to 100 g / 10 min, preferably 1 to 80 g / 10 min, and more preferably greater than 5 g / 10 min and 60 g / 10 min or less. An MFR of less than 1 g / 10 min is undesirable because it results in poor ductility during lamination molding and increases the motor load in the extruder. On the other hand, an MFR exceeding 100 g / 10 min is undesirable because it makes the state of the molten film unstable during molding. To adjust the MFR of a polymer, methods such as appropriately adjusting the polymerization temperature and comonomer amount are employed. The MFR of ethylene-propylene copolymers is measured in accordance with JIS-K6922-2:1997 Annex (190°C, 21.18N load).

[0030] (c-3) Density The ethylene-propylene copolymer (C) used in this invention has a density of 0.88 to 0.94 g / cm³. 3 The concentration is preferably 0.88 to 0.93 g / cm³. 3 More preferably 0.88~0.92 g / cm³ 3 Its density is 0.88 g / cm³. 3 If the density is less than 0.94 g / cm³, it will result in poor blocking and is therefore undesirable. On the other hand, a density of 0.94 g / cm³ is undesirable. 3 If it exceeds this value, the peeling characteristics will be poor, which is undesirable. To adjust the density of the polymer, methods such as appropriately adjusting the comonomer content, polymerization temperature, and catalyst amount are employed. The density of ethylene-propylene copolymer is measured in accordance with JIS-K6922-2:1997 Annex (for low-density polyethylene) (measurement temperature 23°C).

[0031] (c-4) Total number of vinyl and vinylidene In copolymers formed by copolymerizing ethylene with one or more α-olefins, even without the active addition of diene monomers, various double bonds (vinyl, vinylidene, cis-vinylene, trans-vinylene, trisubstituted olefins) may be formed due to differences in the manufacturing process mechanism, and their quantity and type vary. Conventionally, it was known that a higher number of double bonds in ethylene-α-olefin copolymers leads to better crosslinking properties in solar cell encapsulants. However, in the field of lamination resin compositions, the differences due to the amount and type of double bonds had not been investigated. In this invention, we have discovered that among the various double bonds contained in ethylene-propylene copolymers, vinyl and vinylidene are particularly important in terms of peelability. Furthermore, we have found that the effects of this invention can be achieved by producing an ethylene-propylene copolymer in which the total number of vinyl and vinylidene is greater than that of ordinary ethylene-α-olefin copolymers, and by using this copolymer as an ethylene-propylene copolymer for lamination resin compositions.

[0032] The ethylene-propylene copolymer (C) used in the present invention has a total number of vinyl and vinylidene double bonds per 1000 carbon atoms in the main chain and side chains, as measured by NMR, of 0.20 (bonds / total 1000C) or more, preferably 0.30 to 5.0 (bonds / total 1000C), more preferably 0.35 to 4.5 (bonds / total 1000C), and even more preferably 0.50 to 4.0 (bonds / total 1000C). When the total number of vinyl and vinylidene atoms is within the above range, the resin composition exhibits excellent release properties. If it is less than 0.20 atoms, the release properties will not be sufficient. The total number of vinyl and vinylidene atoms can be controlled within the above range by appropriately adjusting the selection of a suitable metallocene catalyst, polymerization temperature, comonomer species, and comonomer amount. The number of these double bonds is the number per 1000 carbon atoms in the main chain and side chain combined, and is a value calculated using the integrated intensity of characteristic peaks in the 1H-NMR spectrum, measured and calculated under the conditions described in the examples below.

[0033] Furthermore, in the present invention, it is preferable that the number of vinyl atoms in the ethylene-propylene copolymer (C) is in the range of 0.1 (atoms / total 1000C) or more. Furthermore, in the present invention, it is preferable that the number of vinylidene molecules in the ethylene-propylene copolymer (C) is in the range of 0.05 (molecules / total 1000C) or more.

[0034] (c-5) Relationship between the number of branching (Y) and density (X) due to comonomers In the present invention, the ethylene-propylene copolymer (C) preferably satisfies the following formula (1) in terms of the number of branches (Y) and density (X) due to the comonomer. Equation (1): (Y) ≥ -566 × (X) + 540 Furthermore, it is more preferable that the number of branches (Y) and density (X) due to comonomers satisfy the following equation (2). Equation (2): (Y) ≥ -1360 × (X) + 1270 When the density and branching number satisfy the relationship in equation (1) or (2) above, a sufficient number of branches due to the comonomers is ensured, resulting in a resin composition with excellent peeling properties. Here, the branching number due to the comonomer (Y) is the number of branches per 1000 carbon atoms in the total of the main chain and side chains of the ethylene-propylene copolymer (C), as measured by NMR (copies / total 1000C). Furthermore, density (X) is the density of the ethylene-propylene copolymer (C), and is measured as described above.

[0035] The number of comonomer branches (Y) indicates the amount of tertiary carbon contained in the polymer, and is the number per 1000 carbon atoms in the main chain and side chains combined, as measured by NMR. For example, it can be calculated from the 13C-NMR spectrum, referring to EW Hansen, R. Blom, and OM Bade, Polymer, Vol. 36, p. 4295 (1997). The relationship between density and branching can be adjusted by the type and ratio of comonomers copolymerized, polymerization conditions such as polymerization temperature, and other factors.

[0036] (c-6) Infrared absorption spectrum of the surface of a hot-pressed sample of ethylene-propylene copolymer (C) The ethylene-propylene copolymer (C) used in this invention exhibits an infrared absorption spectrum obtained by Fourier transform infrared spectroscopy analysis using total internal reflection measurement with a diamond prism on the surface of a sample obtained by hot pressing to a thickness of 1 mm, at a wavelength of 1400 cm². -1 From wavelength 1290 cm -1 When a baseline is drawn within this range, the wavelength is 1368 cm. -1 For the absorbance (D1368), at a wavelength of 1280 cm -1 From wavelength 1240cm -1 The wavelength when drawing a baseline within this range is 1260 cm. -1 Absorbance (D1260) and wavelength 1110 cm -1 From wavelength 1080 cm -1 When a baseline is drawn within this range, the wavelength is 1089 cm². -1 Absorbance (D1089), wavelength 1040 cm -1 From wavelength 1000cm -1 When a baseline is drawn within this range, the wavelength is 1019 cm. -1 Absorbance (D1019), wavelength 817 cm -1 From wavelength 777cm -1 When a baseline is drawn within this range, the wavelength is 797 cm. -1 The ratios of the absorbances of (D797) to each of the following substances, (D1260 / D1368), (D1089 / D1368), (D1019 / D1368), and (D797 / D1368), are all 0.10 or less.

[0037] In this application, "Fourier transform infrared spectroscopy by total reflection measurement" is also referred to as "ATR-FTIR," and "infrared absorption spectrum obtained by ATR-FTIR analysis of a surface" is sometimes referred to as "ATR-FTIR spectrum."

[0038] Here, the hot pressing conditions for obtaining the sample for acquiring the ATR-FTIR spectrum are not particularly limited, as long as they conform to JIS-K7151 "Plastics - Compression-molded test specimens of thermoplastic materials". In this application, the hot pressing conditions for acquiring the ATR-FTIR spectrum were as follows. Sample thickness: 1mm, mold thickness: 1mm, mold size: width x length = 70mm x 197mm, processing temperature: 230℃, molded product removal temperature: 23℃, preheating time: 4 minutes, pressurizing time: 5 minutes, average cooling rate: 60±30K·min-1, pressurizing pressure: 5MPa.

[0039] In the ATR-FTIR spectrum, D1368 originates from the carbon-hydrogen bond of the methylene group contained in the ethylene-propylene copolymer. On the other hand, D1260 and D797 originate from the silicon-carbon bond contained in the silicone, and D1089 and D1019 originate from the silicon-oxygen bond contained in the silicone. Therefore, it can be said with high probability that (D1260 / D1368), (D1089 / D1368), (D1019 / D1368), and (D797 / D1368) in the ATR-FTIR spectrum of the surface of the ethylene-propylene copolymer hot-pressed sample correspond to the ratio of methylene groups to silicone on the surface of the ethylene-propylene copolymer hot-pressed sample.

[0040] The ethylene-propylene copolymer obtained in this invention has a ratio of 0.10 or less for (D1260 / D1368), (D1089 / D1368), (D1019 / D1368), and (D797 / D1368). Therefore, the ethylene-propylene polymer itself has the advantage of not containing silicone.

[0041] In one embodiment of the present invention, the ATR-FTIR spectrum of the surface of a hot-pressed ethylene-propylene copolymer can be measured by an FTIR device connected to an ATR measuring device. The method for measuring the ATR-FTIR spectrum will be described in detail in the examples described later.

[0042] (ii) Polymerization catalyst and polymerization method for ethylene-propylene copolymer (C) The catalyst used in the production of the ethylene-propylene copolymer (C) used in the present invention is not particularly limited, but a metallocene catalyst is more preferred. While not particularly limited, metallocene catalysts include catalysts in which a metallocene compound, such as a zirconium compound to which a group having a cyclopentadienyl skeleton is coordinated, and a co-catalyst are used as catalytic components. In particular, it is preferable to use a metallocene compound, such as a zirconium compound to which a group having a cyclopentadienyl skeleton is coordinated. As for the manufacturing method, since polymerization at a high temperature of 150 to 330°C is desirable to obtain the ethylene-propylene copolymer (C) with adjusted double bonds according to the present invention, it is preferable to use high-pressure ionic polymerization ("Polyethylene Technology Handbook," Chapter 4, edited by Kazuo Matsuura and Naotaka Mikami, 2001).

[0043] (2) Low-density polyethylene (D) produced by high-pressure radical polymerization. The high-pressure radical polymerization low-density polyethylene (D) used in the present invention (hereinafter also simply referred to as low-density polyethylene (D)) is low-density polyethylene (LDPE) obtained by a high-pressure radical polymerization method having the following characteristics (d-1) to (d-2), and is preferably long-chain branched low-density polyethylene. (d-1) MFR (190℃, 21.18N load) is 0.1~20g / 10min (d-2) Density of 0.915~0.930 g / cm³ 3

[0044] (i) Properties of low-density polyethylene (D) produced by high-pressure radical polymerization (d-1)MFR The melt flow rate (MFR: 190°C, 21.18N load) of the low-density polyethylene (D) used in the present invention is 0.1 to 20 g / 10 min, preferably 0.5 to 15 g / 10 min, and more preferably 1 to 15 g / 10 min. If the MFR is less than 0.1 g / 10 min, the ductility is insufficient, and film breakage occurs during high-speed molding. On the other hand, if the MFR exceeds 20 g / 10 min, the molten film becomes unstable. Here, MFR is a value measured in accordance with JIS-K6922-2:1997 Annex (190°C, 21.18N load).

[0045] (d-2) Density The density of the low-density polyethylene (D) used in this invention is 0.915 to 0.930 g / cm³. 3 The concentration is preferably 0.916 to 0.926 g / cm³. 3 More preferably, 0.917 to 0.925 g / cm³ 3 Its density is 0.915 g / cm³. 3 Below 0.93 g / cm³, stickiness increases. On the other hand, above 0.93 g / cm³, adhesion becomes poor. Here, density is measured in accordance with JIS-K6922-2:1997 Annex (for low-density polyethylene) (measurement temperature 23°C).

[0046] (ii) Polymerization method for low-density polyethylene (D) by high-pressure radical polymerization The low-density polyethylene (D) used in this invention is generally produced using a tank reactor or a tubular reactor in the presence of a radical generator at a polymerization pressure of 1000 to 3000 kg / cm². 2 This process is carried out by polymerizing ethylene under conditions of polymerization temperature of 150-300°C. The molecular weight-free polymer (MFR) can be adjusted by using hydrocarbons such as hydrogen, methane, and ethane as molecular weight modifiers.

[0047] (3) Composition ratio of ethylene-propylene copolymer (C) and low-density polyethylene (D) In the present invention, when the polyethylene resin composition (E) contains ethylene-propylene copolymer (C) and low-density polyethylene (D), the ratio of ethylene-propylene copolymer (C) to high-pressure radical polymerization low-density polyethylene (D) is, for example, 10-95% by weight:5-90% by weight, preferably 20-95% by weight:5-80% by weight, and more preferably 30-95% by weight:5-70% by weight. Even more preferably, it is 40-95% by weight:5-60% by weight. If there is too much ethylene-propylene copolymer (C), the stability of the molten film may decrease, and if there is too much high-pressure radical polymerization low-density polyethylene (D), the tape peel strength may increase. In particular, a ratio (C:D) of ethylene-propylene copolymer (C) to high-pressure radical polymerization low-density polyethylene (D) of 50-95% by weight:5-50% by weight is preferable because it results in lower tape peel strength.

[0048] (4) Properties of polyethylene resin composition (E) (e-1)(e-1')MFR The melt flow rate (MFR: 190°C, 21.18N load) of the polyethylene resin composition (E) used in the present invention is preferably 1 to 100 g / 10 min, more preferably 1 to 80 g / 10 min, and even more preferably 5 to 60 g / 10 min. An MFR of less than 1 g / 10 min is undesirable because it results in poor ductility during molding and increases the motor load in the extruder. On the other hand, an MFR exceeding 100 g / 10 min is undesirable because it makes the state of the molten film unstable during molding. Here, MFR is a value measured in accordance with JIS-K6922-2:1997 Annex (190°C, 21.18N load).

[0049] (e-2)(e-2') density The density of the polyethylene resin composition (E) used in the present invention is preferably 0.88 to 0.94 g / cm³. 3 More preferably 0.88 to 0.93 g / cm³ 3 And more preferably 0.88~0.92 g / cm³3 Its density is 0.88 g / cm³. 3 If the density is less than 0.94 g / cm³, it will result in poor blocking and is therefore undesirable. On the other hand, a density of 0.94 g / cm³ is undesirable. 3 Exceeding this limit is undesirable because it results in poor peelability. Here, density is measured in accordance with JIS-K6922-2:1997 Annex (for low-density polyethylene) (measurement temperature 23°C).

[0050] (5) Other ingredients The polyethylene resin composition (E) or the release layer (A) containing the same used in the present invention may contain additives such as antioxidants commonly used in polyethylene resins, such as phenolic or phosphorus-based agents, stabilizers such as metal soaps, antiblocking agents, lubricants, dispersants, pigments such as organic or inorganic colorants, antifogging agents such as unsaturated fatty acid esters, antistatic agents, ultraviolet absorbers, light stabilizers, and nucleating agents, as needed, provided that the release agent properties are not impaired. For example, a preferred range for the antioxidant is 5000 ppm or less by weight, more preferably 3000 ppm or less, and even more preferably 1000 ppm or less. Furthermore, other thermoplastic resins such as LDPE, C4-LLDPE, HAO-LLDPE, polyethylene-based resins such as ethylene-vinyl acetate copolymer (EVA), ethylene-acrylic acid copolymer (EAA), ethylene-methacrylic acid copolymer (EMAA), ethylene-acrylic acid ester copolymer (EEA, EMA, EMMA, etc.), and high-density polyethylene (HDPE), adhesive resins such as ethylene-maleic anhydride copolymer, polypropylene-based resins, and polystyrene resins may be blended, provided that the properties of the polyethylene resin composition layer are not impaired. Furthermore, it is preferable that the polyethylene resin composition (E) of the present invention does not contain a crosslinking agent.

[0051] 2. Base material layer (B) The base material layer (B) used in the present invention is preferably a film mainly composed of paper, polypropylene resin, polyethylene terephthalate resin, or nylon resin, or a cloth base material made using a stretched yarn base material mainly composed of these. Examples include a single-layer film or a laminated film made of the same or different materials as paper, polypropylene resin, polyethylene terephthalate resin, or nylon resin. Films using polyethylene resin, polyethylene terephthalate resin, or nylon resin are preferably stretched films. If the base material layer (B) contains a resin other than paper, polypropylene resin, polyethylene terephthalate resin, or nylon resin, the resins listed later as examples of other base material layers can be used. The substrate layer may be subjected to printing, vapor deposition, various coatings, etc.

[0052] 3. Laminate The laminate of the present invention has at least two layers, a release layer (A) containing the polyethylene resin composition (E) described above and a base layer (B), wherein the release layer (A) is formed by bonding it directly onto the base layer (B) or onto another resin layer laminated on the base layer. At least one surface of the base layer (B) is formed by bonding the release layer (A) containing the polyethylene resin composition (E) directly or onto another resin layer laminated on the base layer. There are no restrictions on the configuration of the laminate, but examples of laminates with configurations such as the following are given. Release layer (A) containing base layer (B) / resin composition (E), release layer (A) containing base layer (B) / other resin layer / resin composition (E), release layer (A) containing resin composition (E) / base layer (B) / release layer (A) containing resin composition (E), release layer (A) containing resin composition (E) / other resin layer / base layer (B) / release layer (A) containing resin composition (E), release layer (A) containing resin composition (E) / other resin layer / base layer (B) / other resin layer / resin composition (E), release layer (A) containing resin composition (E) / base layer (B) , base layer (B) / other resin layer / resin composition (E) included release layer (A) / base layer (B), resin composition (E) included resin layer (E) included release layer (A) / base layer (B) / resin composition (E) included release layer (A) / base layer (B) / resin composition (E) included release layer (A) / base layer (B), resin composition (E) included release layer (A) / other resin layer / base layer (B) / resin composition (E) included release layer (A) / base layer (B) / resin composition (E) included release layer (A) / other resin layer / base layer (B ) / Other resin layer / Resin composition (E) included release layer (A) / Substrate layer (B) / Resin composition (E) included release layer (A) / Substrate layer (B), Resin composition (E) included release layer (A) / Other resin layer / Substrate layer (B) / Other resin layer / Resin composition (E) included release layer (A) / Other resin layer / Substrate layer (B) / Resin composition (E) included release layer (A) / Other resin layer / Substrate layer (B) / Other resin layer / Resin composition (E) included release layer (A) / Other resin layer / Substrate layer (B) / Other resin layer / Resin composition (E) included release layer (A) / Other resin layer / Substrate layer (B) / Other resin layer / Resin composition (E) Release layer (A) containing layer (A) / substrate layer (B), resin composition (E) / other resin layer / substrate layer (B) / other resin layer / release layer (A) / other resin layer / substrate layer (B) / other resin layer / resin composition (E) / release layer (A) / other resin layer / substrate layer (B), substrate layer (B) / resin composition (E) / release layer (A) / other substrate layer, other resin layer / substrate layer (B) / resin composition (E) / release layer (A), other substrate layer / substrate layer (B) / resin composition (E) / release layer (A), substrate layer (B) / resin composition (E) / release layer (A) / other resin layer Here, the other base material layer is a base material layer different from base material layer (B), and examples include plastic films or sheets such as polyamide resins, polyester resins, ethylene-vinyl acetate copolymer saponified products, polyvinylidene chloride, and polycarbonate; stretched products of the above films or sheets; printed materials; secondarily processed films or sheets such as metal vapor-deposited products; metal foils or metal plates such as aluminum, iron, copper, and alloys mainly composed of these materials; cellophane; paper; woven fabrics; nonwoven fabrics; and the like. Furthermore, other resin layers include resin layers different from the release layer (A), and examples include polyethylene-based resins such as LDPE, C4-LLDPE, HAO-LLDPE, ethylene-vinyl acetate copolymer (EVA), ethylene-acrylic acid copolymer (EAA), ethylene-methacrylic acid copolymer (EMAA), ethylene-acrylic acid ester copolymer (EEA, EMA, EMMA, etc.), high-density polyethylene (HDPE), adhesive resins such as ethylene-maleic anhydride copolymer, polypropylene-based resins, polystyrene resins, and other thermoplastic resins.

[0053] The method for manufacturing the laminate is not particularly limited, but a so-called extrusion coating method is preferred, in which a polyethylene resin composition is melt-extruded onto a base layer and laminated. Furthermore, it is preferable that the extrusion coating is laminated by one or more layers using methods such as single layer, sandwich lamination, co-extrusion lamination, or tandem lamination. The release layer (A) containing the polyethylene resin composition (E) can be used as an adhesive layer and can also be used as a surface sealant.

[0054] Furthermore, there are no particular limitations on the method for ensuring adhesion with the paper substrate layer, but for example, the substrate surface may be treated. Examples of surface treatment methods include corona discharge treatment, ozone treatment, flame treatment, and low-temperature plasma treatment. Another method is to spray ozone onto the molten resin. If a substrate layer other than paper is provided, it is preferable to perform anchor coating treatment as needed.

[0055] The type of adhesive surface to which the release sheet of the present invention is applied is not particularly limited. Examples of materials to which the release agent of the present invention exhibits release properties include adhesive surfaces made of the following adhesives: For example, various commonly known adhesives such as rubber-based adhesives, acrylic-based adhesives, urethane-based adhesives, silicone-based adhesives, and vinyl-based adhesives, and any of one-component, two-component, or emulsion-type adhesives may be used (see, for example, "Dictionary of Adhesion and Adhesion" (supervised by Shozaburo Yamaguchi, published by Asakura Shoten, pp. 118-169, 1993)).

[0056] The laminate of the present invention is formed by a release layer (A) containing the above-mentioned polyethylene resin composition (E), and is a laminate with excellent release properties from adhesive tape.

[0057] The laminate of the present invention exhibits excellent peelability from adhesive tapes. Therefore, it can be used as a release film for adhesive sheets, such as surface protection adhesive sheets or dicing adhesive sheets, when processing silicon wafers used in semiconductor integrated circuits (ICs), etc. [Examples]

[0058] The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. The measurement methods and resins used in the examples and comparative examples are as follows.

[0059] 1.Measurement method (1) Melt flow rate (MFR): The MFR of ethylene-propylene copolymer or other ethylene-α-olefin copolymer, high-pressure radical polymerization low-density polyethylene, and polyethylene resin composition was measured in accordance with JIS-K6922-2:1997 Annex (190°C, 21.18N load). (2) Density: The density of ethylene-propylene copolymer or other ethylene-α-olefin copolymer, high-pressure radical polymerization low-density polyethylene, and polyethylene resin composition was measured in accordance with JIS-K6922-2:1997 Annex (23°C, for low-density polyethylene).

[0060] (3) Monomer amount, number of branches, number of double bonds: <Sample preparation and measurement conditions> 200 mg of the sample was placed in an NMR sample tube with an inner diameter of 10 mmφ together with 2.4 ml of o-dichlorobenzene / deuterated benzene = 4 / 1 (volume ratio) and hexamethyldisiloxane, which is a reference substance for chemical shift, and dissolved. NMR measurement was performed using an AV400M type NMR device of Bruker BioSpin Co., Ltd. equipped with a 10 mmφ cryoprobe. 13 The C-NMR measurement conditions were as follows: the sample temperature was 120°C, the pulse angle was 90°, the pulse interval was 20 seconds, and the number of integrations was 128 times, and the measurement was carried out by the broadband decoupling method. 1 The measurement conditions for H-NMR were as follows: the sample temperature was 120°C, the pulse angle was 4.5°, the pulse interval was 2 seconds, and the number of integrations was 512 times for measurement. <Calculation method> (i) Monomer amount, number of branches by comonomer 13 Using the signal intensity of the C-NMR spectrum, the amounts of propylene, hexene, and ethylene were determined from the following equations. C3 (mol%) = I(P) × 100 / [I(P) + I(H) + I(E)] C6 (mol%) = I(H) × 100 / [I(P) + I(H) + I(E)] C2 (mol%) = I(E) × 100 / [I(P) + I(H) + I(E)] Here, I(P), I(H), and I(H) are the amounts represented by the following equations, respectively. I(P) = 0.5 × (I 37.69~37.20 + I 37.90~37.69 + I 37.97~37.90 + I 43.90~42.68 ) + I 46.60~45.39 I(H) = 0.5 × (I 34.56~34.22 + I 34.94~34.86 + I 43.60~42.68 ) + 0.5 × (I 34.86~34.70 - I 35.80~35.68 ) + I 40.10~39.96 + I 40.80~40.70 I(E) = {0.5 × (I 34.94~34.86 +I 37.90~37.69 I 37.97~37.90 +I 34.56~34.22 +I 37.69~37.20 ) + 0.5 × (I 34.86~34.70 -I 35.80~35.68 )+I 24.90~24.70 +I 24.70~24.52 +I 24.52~24.32 +I 27.28~26.83 +I 27.50~27.28 +I 31.50~28.50 -I(H)} / 2 I represents the integral intensity, and the numerical subscript to I indicates the range of the chemical shift. For example, I 37.69~37.20 This shows the integrated intensity of the 13C signal detected between 37.69 ppm and 37.20 ppm. The chemical shift was set to 1.98 ppm for the 13C signal of hexamethyldisiloxane, and the chemical shifts of other 13C signals were referenced to this value. Furthermore, the number of branches per 1000 carbon atoms in the main chain and side chains was calculated using the following formula. Number of methyl branching molecules (molecules / total 1000C) =C3(mol%)×1000 / {C3(mol%)×3+C6(mol%)×6+ C2 (mol%) × 2 Butyl branching count (number of branches / total 1000C) =C6(mol%)×1000 / {C3(mol%)×3+C6(mol%)×6+ C2 (mol%) × 2

[0061] (ii) Number of double bonds The number of unsaturated bonds per 1000 carbon atoms in the main chain and side chains combined 1 The signal intensity of the H-NMR spectrum was used to determine the following equation. Number of vinylidene particles (particles / total 1000C) = Ivd × 1000 / Itotal Number of vinyl units (units / total 1000C) = Ivi × 1000 / Itotal Number of trisubstituted olefins (units / total 1000C) = Itri × 1000 / Itototal Number of vinylene particles (particles / total 1000C) = Ivnl × 1000 / Itotal I represents the integrated intensity, and the subscript number of I indicates the range of the chemical shift. Here, Ivd 、 Ivi, Itri, Ivnl, and Itotal are each represented by the following formulas: It is a certain amount. Ivd=(I 4.88~4.44 ) / 2 Ivni=( I 5.52~5.30 ) / 2 Ivi=( I 5.05~4.88 +I 5.85~5.70 ) / 3 Itri=I 5.30~5.05 Itotal=( 0.00~5.85 ) / 2 However, for example, I 5.52~5.30 This shows the integrated intensity of the proton signal detected between 5.52 ppm and 5.30 ppm. The chemical shift was set with the proton signal of hexamethyldisiloxane at 0.09 ppm, and the chemical shifts of signals from other protons were based on this value.

[0062] (4) Infrared absorption spectrum of the surface of a hot-pressed sample of ethylene-propylene copolymer (C) (i) Conditions for preparing hot press samples Hot-pressed samples for obtaining the ATR-FTIR spectrum of ethylene-propylene copolymer (C) were obtained in accordance with JIS-K7151 "Plastics - Compression-molded test specimens of thermoplastic materials" under the following conditions. Sample thickness: 1mm, mold thickness: 1mm, mold size: width x length = 70mm x 197mm, processing temperature: 230℃, molded product removal temperature: 23℃, preheating time: 4 minutes, pressurizing time: 5 minutes, average cooling rate: 60±30K·min-1, pressurizing pressure: 5MPa. (ii) ATR-FTIR measurement The surface of the sample obtained in (i) was subjected to ATR-FTIR analysis under the following conditions to obtain an infrared absorption spectrum. The apparatus consists of an FTIR [manufactured by JASCO Corporation, FT / IR-6100] connected to a single-reflection total internal reflection (ATR) measuring device [manufactured by JASCO Corporation, ATR PRO450-S]. ATR Prism (High Refractive Index Crystal Species): Diamond Incident angle: 45° Measurement area: 5000cm -1 ~650cm -1 Detector: TGS Number of reflections: 1 Resolution: 4cm -1 Total number of times: 32 Other: The infrared absorption spectrum, measured without contact with the sample, was used as the background, and processing that did not affect the measured spectrum was performed.

[0063] From the ATR-FTIR spectrum obtained in the manner described above, at a wavelength of 1400 cm⁻¹ -1 From wavelength 1290 cm -1 When a baseline is drawn within this range, the wavelength is 1368 cm. -1 For the absorbance (D1368), at a wavelength of 1280 cm -1 From wavelength 1240cm -1 The wavelength when drawing a baseline within this range is 1260 cm. -1 Absorbance (D1260) and wavelength 1110 cm -1 From wavelength 1080 cm -1 When a baseline is drawn within this range, the wavelength is 1089 cm². -1 Absorbance (D1089), wavelength 1040 cm -1 From wavelength 1000cm -1 When a baseline is drawn within this range, the wavelength is 1019 cm. -1 Absorbance (D1019), wavelength 817 cm -1 From wavelength 777cm -1 When a baseline is drawn within this range, the wavelength is 797 cm. -1 The ratios of absorbance (D797) to (D1260 / D1368), (D1089 / D1368), (D1019 / D1368), and (D797 / D1368) were calculated.

[0064] (5) Melt film stability: The stability of the molten film was visually observed using a 90mm diameter extruder, a 560mm wide T-die, a 0.8mm lip width, a 115mm air gap, a molding temperature of 285°C, and a take-up speed of 100m / min. A "○" indicated that the molten film was stable and could be processed, while a "×" indicated that the molten film was unstable and could not be processed to a uniform thickness.

[0065] (6) Tape peeling force measurement Using a laminator in a 90Φ extruder, 50g / m² of kraft paper material is fed from the feed machine. 2 The material is fed out and used as the base material, and the paper base material surface is subjected to corona treatment at 30W·min / m 2 I applied Novatec LC600A manufactured by Nippon Polyethylene to this paper substrate, and then treated it with ozone at 1.5 Nm. 3 / h-16g / m 3 Extrusion lamination was performed under conditions of a take-up speed of 100 m / min and a thickness of 15 μm with the material under pressure. Furthermore, polyethylene resin composition (E) was laminated to the LC600A layer side under conditions of a take-up speed of 100 m / min and a thickness of 20 μm to obtain a laminate of a kraft layer, an LC600A layer, and a release layer (A) containing polyethylene resin composition (E). This laminate was attached to an acrylic plate measuring 50 mm in width and 300 mm in length, with the craft layer side facing outwards. In accordance with JIS-Z0237-2009, the tape peel strength of a 180° peel was measured after applying Sekisui Chemical Co., Ltd.'s "Fitlight Tape No. 738" to the polyethylene resin composition (C) layer of the laminate.

[0066] 2. Resin materials (1) Ethylene-propylene copolymer (C) or other ethylene-α-olefin copolymers (PE-1) to (PE-6) obtained by the following manufacturing method were used as the ethylene-propylene copolymer or other ethylene-α-olefin copolymer of component (C). Their physical properties are shown in Table 1.

[0067] Manufacturing methods for (PE-1) to (PE-6) (i) Preparation of catalyst A catalyst solution was prepared by adding an equimolar amount of "N,N-dimethylaniliniumtetrakis(pentafluorophenyl)borate" to 0.05 moles of the complex "rac-dimethylsilylenebisindenylhafniumdimethyl," which was prepared by the method described in Japanese Patent Publication No. 10-218921, and diluting it with toluene to 50 liters.

[0068] (ii) Polymerization method A 5.0-liter internal volume agitated autoclave-type continuous reactor was used, and the reactor pressure was maintained at 80 MPa. The raw material gas was continuously supplied at a rate of 40 kg / hour, with the ethylene, propylene, and 1-hexene adjusted as needed. In addition, the catalyst solution described in section (i) "Preparation of Catalyst" above was continuously supplied, and the polymerization temperature was adjusted as needed within the range of 150 to 250°C to obtain an ethylene-α-olefin copolymer. The physical properties of the obtained ethylene-propylene copolymer or other ethylene-α-olefin copolymer are shown in Table 1.

[0069] (2) Low-density polyethylene by high-pressure radical polymerization Low-density polyethylene (PE-7) to (PE-8) produced by high-pressure radical polymerization, having the physical properties shown in Table 1, was used.

[0070] (Example 1) The material consists of 90% by weight of ethylene-propylene copolymer (C) (PE-1) and high-pressure low-density polyethylene (D), with an MFR of 4 g / 10 min and a density of 0.918 g / cm³. 3 A polyethylene resin composition (E) consisting of 10% by weight of long-chain branched low-density polyethylene (PE-7) produced by high-pressure radical polymerization was granulated using a 40 mm single-screw extruder to obtain polyethylene-based composition pellets. Using the pellets obtained above, in order to evaluate (5) melt film stability and (6) tape peel strength, 50 g / m² of kraft substrate was fed from the feed machine into the laminator of a 90Φ extruder. 2 The material is fed out and used as the base material, and the paper base material surface is subjected to corona treatment at 30W·min / m 2 This paper substrate was treated with Novatec LC600A manufactured by Nippon Polyethylene, and then ozone-treated at 1.5 Nm. 3 / h-16g / m 3 Extrusion lamination was performed under conditions of a take-up speed of 100 m / min and a thickness of 15 μm with the material under control. Furthermore, polyethylene resin composition (E) was laminated to the LC600A layer at a take-up speed of 100 m / min and a thickness of 20 μm to obtain a laminate consisting of a kraft layer, an LC600A layer, and a release layer (A) containing polyethylene resin composition (E), and each was evaluated. The evaluation results of the laminate are shown in Table 1.

[0071] (Example 2) Pellets were prepared and evaluated in the same manner as in Example 1, except that (PE-2) was used instead of (PE-1) as the ethylene-propylene copolymer (C). The evaluation results are shown in Table 1.

[0072] (Example 3) Pellets were prepared and evaluated in the same manner as in Example 1, except that ethylene-α-olefin copolymer (PE-3), a copolymer of ethylene, propylene, and 1-hexene, was used instead of ethylene-propylene copolymer (PE-1) used in Example 1. The evaluation results are shown in Table 1.

[0073] (Example 4) Pellets were prepared and evaluated in the same manner as in Example 1, except that ethylene-α-olefin copolymer (PE-4), a copolymer of ethylene, propylene, and 1-hexene, was used instead of ethylene-propylene copolymer (PE-1), which was used in Example 1. The evaluation results are shown in Table 1.

[0074] (Comparative Example 1) Except for using ethylene-α-olefin copolymer (PE-5), a copolymer of ethylene and 1-hexene, instead of ethylene-propylene copolymer (PE-1) used in Example 1, pellets were prepared and evaluated in the same manner as in Example 1. The evaluation results are shown in Table 1.

[0075] (Comparative Example 2) Except for using ethylene-α-olefin copolymer (PE-6), a copolymer of ethylene and 1-hexene, instead of ethylene-propylene copolymer (PE-1) used in Example 1, pellets were prepared and evaluated in the same manner as in Example 1. The evaluation results are shown in Table 1.

[0076] (Comparative Example 3) In Example 1, pellets were prepared and evaluated in the same manner as in Example 1, except that a composition obtained solely from low-density polyethylene (D), PE-8, obtained by high-pressure radical polymerization, was used instead of ethylene-propylene copolymer (C). The evaluation results are shown in Table 1.

[0077] [Table 1]

[0078] Figure 3 shows a graph illustrating the relationship between the density of the ethylene-propylene copolymer (C) or other ethylene-α-olefin copolymers obtained in Examples 1-4 and Comparative Examples 1-3, and the tape peel strength, as shown in Table 1. In the graph, the X-axis (horizontal axis) represents the density of the ethylene-propylene copolymer or other ethylene-α-olefin copolymer used in the study, and the Y-axis (vertical axis) represents the tape peel strength. A smaller value on the Y-axis is preferable. As is clear from the results in Table 1 and Figure 3, the polyethylene resin composition for the release layer according to the embodiment of the present invention and the laminate obtained thereby exhibit excellent melt film stability and excellent low tape peel strength relative to the density. On the other hand, when the value calculated from a specific formula defined by the number of branches due to the comonomer and the density of the ethylene-α-olefin copolymer exceeds the number of branches of the comonomer (Comparative Examples 1 and 2), the tape peel strength relative to the density becomes high, which is undesirable. Furthermore, even when using only low-density polyethylene (D) produced by high-pressure radical polymerization without using ethylene-propylene copolymer (C) (Comparative Example 3), the tape peel strength was high and not satisfactory. [Industrial applicability]

[0079] Laminates using the release resin composition of the present invention as the release layer can be used as release films, release sheets, etc., where easy peeling is required.

Claims

1. It has at least two layers, a release layer (A) and a substrate layer (B), The release layer (A) is formed either directly on the base layer (B) or laminated on another resin layer laminated on the base layer, and the release layer (A) is characterized in that it satisfies the following properties, and is a release film having easy peelability from an adhesive surface. Release layer (A): Contains a polyethylene resin composition (E) containing an ethylene-propylene copolymer (C) having the following properties (c-1) to (c-6). (c-1) It may contain 80 to 98 mol% of constituent units derived from ethylene as the main component, 2 to 20 mol% of constituent units derived from propylene as an essential minor component, and 7 mol% or less of constituent units derived from a third α-olefin other than ethylene and propylene as a minor component. (However, if the material contains constituent units derived from the third α-olefin, the sum of constituent units derived from ethylene, propylene, and the third α-olefin shall not exceed 100 mol%.) (c-2) MFR (190°C, 21.18N load) is 1-100g / 10min (c-3) Density of 0.88–0.94 g / cm³ ３ (c-4) The total amount of vinyl and vinylidene in the ethylene-propylene copolymer is 0.20 (particles / total 1000C) or more. (However, the number of vinyl and vinylidene atoms is the number per 1000 carbon atoms in the main chain and side chains combined, as measured by NMR.) (c-5) The number of branches (Y) and density (X) of comonomers in an ethylene-propylene copolymer satisfy the following relationship (1). Equation (1): (Y) ≥ -566 × (X) + 540 (However, Y is the number of carbon atoms per 1000 total carbon atoms in the main chain and side chains as measured by NMR.) In the infrared absorption spectrum obtained by Fourier transform infrared spectroscopic analysis using the total reflection measurement method with a diamond prism on the surface of a sample obtained by hot pressing a (c-6) ethylene-propylene copolymer to a thickness of 1 mm, the wavelength is 1400 cm －１ to the wavelength of 1290 cm －１ When a baseline is drawn in the range of, the absorbance (D1368) at the wavelength of 1368 cm －１ With respect to, the absorbance (D1260) at the wavelength of 1260 cm when a baseline is drawn in the range from the wavelength of 1280 cm －１ to the wavelength of 1240 cm －１ And the absorbance (D1089) at the wavelength of 1089 cm when a baseline is drawn in the range from the wavelength of 1110 cm －１ to the wavelength of 1080 cm －１ －１ The absorbance (D1019) at the wavelength of 1019 cm when a baseline is drawn in the range from the wavelength of 1040 cm －１ to the wavelength of 1000 cm －１ －１ －１ －１ －１ －１ ３ ３ ３ ３ －１ －１ The respective ratios of (D1260 / D1368), (D1089 / D1368), (D1019 / D1368), and (D797 / D1368) are all 0.10 or less

2. The release film according to claim 1, characterized in that the ethylene-propylene copolymer (C) further satisfies the following relationship (c-5'). (c-5') The number of branches (Y) and density (X) of comonomers in an ethylene-propylene copolymer satisfy the relationship shown in equation (2) below. Equation (2): (Y) ≥ -1360 × (X) + 1270 (However, Y is the number of carbon atoms per 1000 total carbon atoms in the main chain and side chains as measured by NMR.)

3. The release film according to claim 1 or claim 2, characterized in that the polyethylene resin composition (E) further contains high-pressure radical polymerization low-density polyethylene (D) having the following properties (d-1) to (d-2). (d-1) MFR (190°C, 21.18N load) is 0.1-20g / 10min (d-2) Density of 0.915–0.930 g / cm³ ３

4. The release film according to claim 3, characterized in that the polyethylene resin composition (E) contains 95 to 10% by weight of the ethylene-propylene copolymer (C) and 5 to 90% by weight of the high-pressure radical polymerization low-density polyethylene (D).

5. The release film according to any one of claims 1 to 4, characterized in that the polyethylene resin composition (E) further satisfies the following properties (e-1) to (e-2). (e-1) MFR is 1-100g / 10 min (e-2) Density of 0.88–0.94 g / cm³ ３

6. The release film according to any one of claims 1 to 5, characterized in that the polyethylene resin composition (E) further satisfies the following properties (e-1') to (e-2'). (e-1') MFR is 5-60g / 10 min (e-2') Density of 0.88–0.92 g / cm³ ３

7. The release film according to any one of claims 1 to 6, characterized in that the release layer (A) is formed on the substrate layer (B) by an extrusion coating method.

8. A release resin composition containing an ethylene-propylene copolymer (C) having the following properties (c-1) to (c-6), characterized in that it is used to impart easy peelability to an adhesive surface. (c-1) It may contain 80 to 98 mol% of constituent units derived from ethylene as the main component, 2 to 20 mol% of constituent units derived from propylene as an essential minor component, and 7 mol% or less of constituent units derived from a third α-olefin other than ethylene and propylene as a minor component. (However, if the material contains constituent units derived from the third α-olefin, the sum of constituent units derived from ethylene, propylene, and the third α-olefin shall not exceed 100 mol%.) (c-2) MFR (190°C, 21.18N load) is 1-100g / 10min (c-3) Density of 0.88–0.94 g / cm³ ３ (c-4) The total amount of vinyl and vinylidene in the ethylene-propylene copolymer is 0.20 (particles / total 1000C) or more. (However, the number of vinyl and vinylidene atoms is the number per 1000 carbon atoms in the main chain and side chains combined, as measured by NMR.) (c-5) The number of branches (Y) and density (X) of comonomers in an ethylene-propylene copolymer satisfy the following relationship (1). Equation (1): (Y) ≥ -566 × (X) + 540 (However, Y is the number of carbon atoms per 1000 total carbon atoms in the main chain and side chains as measured by NMR.) (c-6) In the infrared absorption spectrum obtained by Fourier transform infrared spectroscopy analysis using total internal reflection measurement with a diamond prism on the surface of a sample obtained by heat-pressing an ethylene-propylene copolymer to a thickness of 1 mm, at a wavelength of 1400 cm² －１ From wavelength 1290 cm －１ When a baseline is drawn within this range, the wavelength is 1368 cm. －１ For the absorbance (D1368), at a wavelength of 1280 cm²... －１ From wavelength 1240 cm －１ The wavelength when drawing the baseline within this range is 1260 cm. －１ Absorbance (D1260), and wavelength 1110 cm －１ From wavelength 1080 cm －１ When a baseline is drawn within this range, the wavelength is 1089 cm. －１ Absorbance (D1089), wavelength 1040 cm －１ From wavelength 1000 cm －１ When a baseline is drawn within this range, the wavelength is 1019 cm. －１ Absorbance (D1019), wavelength 817 cm －１ From wavelength 777 cm －１ When a baseline is drawn within this range, the wavelength is 797 cm. －１ The ratios of the absorbances (D797) for each element, namely (D1260 / D1368), (D1089 / D1368), (D1019 / D1368), and (D797 / D1368), are all less than or equal to 0.10.

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