Release film

Abstract

The present invention provides an inexpensive release film having excellent release properties. A release film according to the present invention has a release layer that contains a polyester resin, said release film being characterized in that the release layer satisfies the following conditions: the water contact angle is 80-130°; and the hydrogen bond component σh of the surface free energy, measured in accordance with ISO 19403, is 2.4 mN / m or less. In addition, the release layer preferably satisfies the condition that the storage modulus at 180°C, measured in accordance with JIS K7244, is no less than 10 MPa but no greater than 200 MPa.

Description

Release film

[0001] This invention relates to a release film.

[0002] For example, as shown in Patent Document 1, a release film is generally used when forming a flexible printed circuit board by bonding a coverlay film to a flexible circuit board having an exposed circuit by hot pressing, via an adhesive layer provided on the coverlay film.

[0003] After laminating the coverlay film onto the flexible circuit board, the release film is required to be peeled off from the formed flexible printed circuit board with excellent releasability.

[0004] More specifically, when the release film is peeled off from the flexible printed circuit board, it is required that the release film exhibits excellent releasability with respect to the flexible printed circuit board, thereby suppressing the occurrence of creases and breaks in the flexible printed circuit board.

[0005] To achieve excellent releasability, polymethylpentene is often used as a constituent material of the release film. However, polymethylpentene is relatively expensive and disadvantageous in terms of cost. However, if a release film made of an inexpensive and relatively easily available material (e.g., polyester resin) is used, the release property may be insufficient, and conveyance problems such as creases and breakage may occur in the flexible printed circuit board. In particular, when the release film comes into contact with the adhesive layer of the coverlay film, partial bonding between them may result in a decrease in releasability. This issue has not been sufficiently addressed in the past.

[0006] Patent No. 6470461

[0007] The object of the present invention is to provide a release film that is inexpensive and has excellent release properties.

[0008] These objectives are achieved by the present invention as described in (1) to (16) below. (1) A release film having a release layer containing a polyester resin, wherein the release layer satisfies the condition that the water contact angle is 80° or more and 130° or less, and the hydrogen bonding component σ of the surface free energy measured in accordance with ISO 19403 ｈ A release film characterized by satisfying the condition that the density is 2.4 mN / m or less.

[0009] (2) The release film according to (1), wherein the release layer satisfies the condition that the storage modulus at 180° C. measured in accordance with JIS K7244 is 10 MPa or more and 200 MPa or less.

[0010] (3) The release film according to (1) or (2) above, wherein the release layer satisfies the condition that the contact angle of diiodomethane is 20° or more and 50° or less.

[0011] (4) The release film according to any one of (1) to (3) above, wherein the release layer satisfies the condition that the arithmetic mean roughness measured in accordance with JIS B0601 is 0.1 μm or more and 5.0 μm or less.

[0012] (5) The release layer has a surface free energy component σ measured in accordance with ISO 19403. ｄ A release film according to any of (1) to (4) above, which satisfies the condition of being 30 mN / m or more and 50 mN / m or less.

[0013] (6) The release film according to any one of (1) to (5) above, wherein the release layer has an average thickness of 5 μm or more and 35 μm or less.

[0014] (7) The release film according to any one of (1) to (6) above, wherein the release film is used by being superimposed on the surface of an object having an adhesive layer so that the surface on the release layer side is in contact with the surface of the object.

[0015] (8) The release film according to (7) above, having a cushion layer provided on one side of the release layer.

[0016] (9) The release film according to (8), wherein the cushion layer has a storage modulus at 150° C. measured in accordance with JIS K7244-4 of 0.1 MPa or more and 200 MPa or less.

[0017] (10) The release film according to (8) or (9) above, wherein the cushion layer has an average thickness of 10 μm or more and 200 μm or less.

[0018] (11) A release film having a resin layer containing a polyester resin, the release film being used in contact with an object, wherein the resin layer has a first layer and a second layer that is provided in contact with the first layer and is in contact with the object, and the first layer has an intensity I at 284 eV when measured by X-ray photoelectron spectroscopy. Ａ２８４ And, the intensity I at 288 eV measured by the aforementioned X-ray photoelectron spectroscopy analysis. Ａ２８８ Relative to I Ａ２８８ / I Ａ２８４ is 0.2 or more and less than 0.5, and the second layer has an average thickness of 10 nm or more and 500 nm or less, and an intensity I at 284 eV when measured by the X-ray photoelectron spectroscopy Ｂ２８４ and the intensity I at 288 eV when measured by the X-ray photoelectron spectroscopy. Ｂ２８８ Relative to I Ｂ２８８ / I Ｂ２８４ A release film characterized by satisfying the condition that the ratio is 0.14 or more and less than 0.3.

[0019] (12) The first layer has an intensity I at 284 eV when measured by the X-ray photoelectron spectroscopy. Ａ２８４ and the intensity I at 532 eV when measured by the X-ray photoelectron spectroscopy. Ａ５３２ Relative to I Ａ５３２ / I Ａ２８４ The release film described in (11) above, wherein the value is 0.5 or more and less than 1.0.

[0020] (13) The second layer has an intensity I at 284 eV when measured by the X-ray photoelectron spectroscopy. Ｂ２８４ and the intensity I at 532 eV when measured by the X-ray photoelectron spectroscopy. Ｂ５３２Relative to I Ｂ５３２ / I Ｂ２８４ The release film according to (11) or (12) above, which satisfies the condition that the value is 0.5 or more and less than 1.0.

[0021] (14) The release film according to any one of (11) to (13) above, wherein the polyester resin is polybutylene terephthalate or a copolymer thereof.

[0022] (15) The release film according to any one of (11) to (14) above, wherein the crystallinity of the first layer is 20% or more and 70% or less, and the crystallinity of the second layer is 40% or more and 80% or less.

[0023] (16) The object has an epoxy adhesive layer, and when the release film is brought into contact with the object and then removed, at least a portion of the second layer is in contact with the epoxy adhesive layer when it is removed from the first layer, according to any one of (11) to (15) above.

[0024] According to the present invention, it is possible to provide an inexpensive release film having excellent releasability.

[0025] FIG. 1 is a side view showing the main parts of a roll-to-roll press used in the production of flexible printed circuit boards. FIG. 2 is a longitudinal sectional view showing each step in a method for producing a flexible printed circuit board using the roll-to-roll press shown in FIG. 1. FIG. 3 is a longitudinal sectional view showing a heat pressing step in a method for producing a flexible printed circuit board using the roll-to-roll press shown in FIG. 1. FIG. 4 is a longitudinal sectional view showing an embodiment of a release film of present invention A. FIG. 5 is a partially enlarged longitudinal sectional view in which part A of the release film shown in FIG. 4 is partially enlarged. FIG. 6 is a longitudinal sectional view showing each step in a method for producing a flexible printed circuit board using the roll-to-roll press shown in FIG. 1. FIG. 7 is a longitudinal sectional view showing an embodiment of a release film of present invention B. FIG. 8 is a partially enlarged longitudinal sectional view in which part B of the release film shown in FIG. 7 is partially enlarged.

[0026] The release film of the present invention will be described in detail below based on preferred embodiments shown in the accompanying drawings.

[0027] 1A. Outline of Invention A The release film of Invention A is a release film having a release layer containing polyester resin, wherein the release layer satisfies the condition that the water contact angle is 80° or more and 130° or less, and the hydrogen bonding component σ of the surface free energy measured in accordance with ISO 19403 ｈ The condition that the strength is 2.4 mN / m or less is satisfied.

[0028] In the present invention A, since polyester resin is used, a release film can be obtained at low cost. Furthermore, because the release layer has the above-mentioned properties, it exhibits particularly excellent release properties for materials having hydrophilic groups. These details will be described later.

[0029] 2A. Method of Using the Release Film First, a method of using the release film of Invention A will be described. Note that, hereinafter, an example of the production of a flexible printed circuit board using the release film of Invention A and a roll-to-roll press will be described. Furthermore, prior to describing the release film of Invention A, the roll-to-roll press used in the production of this flexible printed circuit board will be described.

[0030] 2A.1. Roll-to-Roll Press Machine Figure 1 is a side view showing the main components of a roll-to-roll press machine used in the manufacture of flexible printed circuit boards, Figure 2 is a vertical cross-sectional view showing each step in a method for manufacturing a flexible printed circuit board using the roll-to-roll press machine shown in Figure 1, and Figure 3 is a vertical cross-sectional view showing a heat pressing step in the method for manufacturing a flexible printed circuit board using the roll-to-roll press machine shown in Figure 1. Note that, hereinafter, for convenience of explanation, the upper side in Figures 1 to 3 will be referred to as "top" or "upper," the lower side will be referred to as "bottom" or "lower," the left side will be referred to as "left," and the right side will be referred to as "right."

[0031] As shown in Figures 1 to 3, a roll-to-roll press (RtoR press) 100 is equipped with a conveying means (not shown) that conveys release films 10 (10A, 10B), a flexible printed circuit board (FPC) 200, and glass cloths 300A, 300B, a heat pressing means 50 that uses the release film 10 to heat-press a flexible circuit board 210 and a cover lay film (CL film) 220 that the FPC 200 is equipped with to bond the CL film 220 to the flexible circuit board 210, and a releasing means 60 that releases (peels) the release film 10 from the FPC 200 in which the CL film 220 is bonded to the flexible circuit board 210.

[0032] The CL film 220 comprises a coverlay 221 and an adhesive layer 222. The coverlay 221 is a protective layer made of, for example, polyimide.

[0033] The adhesive layer 222 has the function of adhering the coverlay 221 of the CL film 220 to the flexible circuit board 210. The adhesive constituting the adhesive layer 222 is not particularly limited, and examples thereof include an epoxy adhesive and an acrylic adhesive. In particular, when the adhesive layer 222 is composed of an epoxy adhesive, the effect of present invention A can be more significantly exhibited, as described below.

[0034] The conveying means (not shown) conveys the FPC 200, the release films 10A and 10B, and the glass cloths 300A and 300B, which are wound around different unwinding rollers, along their respective longitudinal directions by the rotation of tensioners (tension rollers), and after processing by the heat pressing means 50 and the releasing means 60, the take-up roller winds them up.

[0035] Each roller is made of a metal material, such as stainless steel. Furthermore, the pivot axes (central axes) of these rollers are aligned in the same direction and are spaced apart from one another.

[0036] 1, the heat pressing means 50 has a heat pressing unit 52. The heat pressing unit 52 has a pair of heat pressing plates 521. The heat pressing plates 521 are arranged above and below a laminate transported by a transport means, in which the glass cloth 300A, the release film 10A, the FPC 200, the release film 10B, and the glass cloth 300B are stacked. When the laminate passes between the heat pressing plates 521, the heat pressing plates 521 heat and press the FPC 200 via the glass cloths 300A and 300B and the release films 10A and 10B.

[0037] At this time, the coverlay 221 and the flexible circuit board 210 are bonded via the adhesive layer 222 (see FIG. 2( a)). Furthermore, when the FPC 200 is heated and pressurized, that is, when the coverlay 221 and the flexible circuit board 210 are bonded via the adhesive layer 222, the release film 10 is embedded in the recesses 223 formed in the coverlay 221. Therefore, the exudation (squeezing) of the adhesive originating from the adhesive layer 222 into the recesses 223 is suppressed (see FIG. 2( b)). In present invention A, even if the adhesive originating from the adhesive layer 222 squeezes (squeezes) out, the release film 10 can exhibit excellent releasability.

[0038] Before being heated and compressed by the heating and compression plate 521, the FPC 200 is in a laminated state with the flexible circuit board 210 and the CL film 220 superimposed on each other, but the flexible circuit board 210 and the CL film 220 are not bonded via the adhesive layer 222 provided on the CL film 220. That is, by the compression bonding using the heating and compression plate 521, the adhesive layer 222 provided on the CL film 220 is brought into close contact with the flexible circuit board 210, and further, in this state, by heating using the heating and compression plate 521, a curing reaction of the adhesive layer 222 progresses, and the flexible circuit board 210 and the CL film 220 are bonded via the adhesive layer 222.

[0039] 1, the release means 60 is disposed downstream in the conveying direction relative to the heat press means 50. This release means 60 is configured to separate the FPC 200 from the release films 10A and 10B.

[0040] In the heating and pressing section 52 of the heating and pressing means 50, as shown in Figure 2(b), the release film 10 is embedded in the recess 223 formed in the coverlay 221. As a result, the release film 10 is bonded to the CL film 220 (FPC 200), but the release means 60 is configured to allow the release film 10 to be peeled (released) from the CL film 220 (FPC 200) (see Figure 2(c)). Therefore, based on the action of the release means 60, the FPC 200, in which the flexible circuit board 210 and the CL film 220 are bonded via the adhesive layer 222, is obtained in a state where it is peeled from the release film 10.

[0041] A flexible printed circuit board 200 (FPC 200) can be manufactured using the roll-to-roll press machine 100 described above. A method for manufacturing an FPC 200 using this roll-to-roll press machine will now be described.

[0042] In this embodiment, the manufacturing method for the FPC 200 includes, as shown in Figures 1 to 3, a first step of creating a laminate in which a glass cloth 300A, a release film 10A, an FPC 200, a release film 10B, and a glass cloth 300B, each in the form of a sheet, are stacked in this order; a second step of bonding the coverlay 221 (CL film 220) to the flexible circuit board 210 in the FPC 200 via an adhesive layer 222 by heating and pressing the laminate; and a third step of releasing the release films 10 (10A, 10B) from the FPC 200 to obtain an FPC 200 in which the CL film 220 is bonded to the flexible circuit board 210.

[0043] The following describes each of these processes in order. 2A. 2. First Process First, the glass cloth 300A, release film 10A, FPC 200, release film 10B, and glass cloth 300B, each in sheet form and wound around an unwinding roller, are stacked in this order during transport by the transport means to form a laminate (release film placement process, see Figures 1, 2(a), and 3).

[0044] The method of laminating each component (film) to form a laminate is not particularly limited; for example, they may be laminated while being pressed with a roll, or while being pressed with a plate-shaped component. The order in which each component is laminated can also be arbitrary. For example, all components may be laminated simultaneously, or the coverlay film 220 and the flexible circuit board 210 may be laminated in advance, and then the other components may be laminated simultaneously.

[0045] Furthermore, the formation of the laminate in this first step constitutes a step of placing the release film 10 on the object (FPC 200).

[0046] 2A. 3. In the second step, the laminate, in which the glass cloth 300A, release film 10A, FPC 200, release film 10B, and glass cloth 300B are stacked in this order, is heated (heated and pressed) under pressure using a heating and pressing means 50 (heating and pressing unit 52). As the adhesive layer 222 adheres tightly to the flexible circuit board 210, the curing reaction of the adhesive layer 222 proceeds, and in the FPC 200, a bond is formed in which the coverlay 221 (CL film 220) is bonded to the flexible circuit board 210 via the adhesive layer 222 (see heating and pressing step, Figures 1, 2(b), and 3).

[0047] Furthermore, as the release film 10A adheres closely to the coverlay 221 and is embedded in the recess 223 formed in the coverlay 221, the seepage (overflow) of adhesive originating from the adhesive layer 222 within the recess 223 is suppressed. In this invention A, even if there is seepage (overflow) of adhesive originating from the adhesive layer 222, the release film 10 can exhibit excellent release properties.

[0048] In this second step, the temperature at which the FPC 200 is heated is not particularly limited, but is preferably 100°C to 250°C, and more preferably 150°C to 200°C.

[0049] Furthermore, in the second step, when pressurizing the FPC 200, the pressure set in the heating and crimping section 52 is not particularly limited, but is preferably set to 1 MPa or more and 14 MPa or less, and more preferably to 5 MPa or more and 14 MPa or less.

[0050] Furthermore, the transport speed for transporting the laminate is preferably set to 40 mm / sec or more and 400 mm / sec or less, and more preferably to 100 mm / sec or more and 350 mm / sec or less. In other words, in the second step (this step), the laminate is heated and pressed using the heating press means 50, and in the third step (next step), the adhesion time until the release film 10 is peeled off the bonded body is preferably set to 1.0 sec or more and 10.0 sec or less, and more preferably to 4.0 sec or more and 7.0 sec or less.

[0051] The second step constitutes a step of performing a heat press on the object (FPC 200) on which the release film 10 is placed.

[0052] Furthermore, although this embodiment shows a means of heating by a heating press using a plate-shaped member, it is not necessarily limited to this method. For example, heating may be performed by infrared radiation or by heating rolls.

[0053] 2A. 4. Third Step Next, the release means 60 releases the release films 10 (10A, 10B) from the FPC 200. That is, the release films 10A and 10B are peeled off from the bond between the coverlay film 220 and the flexible circuit board 210. This results in an FPC 200 with the CL film 220 bonded to the flexible circuit board 210 (peeling step, see Figures 1 and 2(c)).

[0054] The release means 60 is not particularly limited and may be configured to release by installing a vacuum device and creating a vacuum, or by sending air between the bonded body and the release films 10A and 10B, or by inserting a rod between the bonded body and the release films 10A and 10B.

[0055] Subsequently, the FPC 200, in which the coverlay film 220 and the flexible circuit board 210 are joined, along with the glass cloth 300A, release film 10A, release film 10B, and glass cloth 300B, are wound up using their respective winding rollers.

[0056] Through this winding process, the flexible circuit board 210 and the CL film 220 are obtained continuously as the FPC 200, which is bonded via the adhesive layer 222 of the CL film 220, is wound onto the winding roller.

[0057] As described above, by applying the manufacturing method of the flexible printed circuit board 200 using a roll-to-roll press machine 100 with a release film 10, the flexible printed circuit board 200 can be manufactured continuously.

[0058] The release film according to Invention A is applied to the release film 10 used in the manufacture of this flexible printed circuit board 200. The release film 10 to which the release film according to Invention A is applied will be described below.

[0059] 3A. Release Film 10 Figure 4 is a longitudinal cross-sectional view showing an embodiment of the release film of the present invention A, and Figure 5 is a partially enlarged longitudinal cross-sectional view showing a portion A of the release film shown in Figure 4.

[0060] As described above, the release film 10 is used by overlapping it with the surface of the CL film 220, which is an example of an object having an adhesive layer 222, so that the surface on the release layer 11 side is in contact with it. This makes it possible to more reliably exert the effects of the present invention A, as will be described later.

[0061] As shown in Figures 4 and 5, the release film 10 has a release layer 11 and a cushion layer 12, which are laminated together so that they are in contact with each other. An intermediate layer, such as an adhesive layer, may be provided between the release layer 11 and the cushion layer 12.

[0062] 3A. 1. Release layer 11 The release layer 11 contains polyester resin.

[0063] 3A.1.1. Polyester Resin Polyester resin is a polymeric compound (e.g., having a weight average molecular weight Mw of 1,000 or more and 1,000,000 or less) having a structure formed by polycondensation of a diol component and a dicarboxylic acid component. Specific examples of polyester resins include, but are not limited to, polyethylene terephthalate (PET), polycyclohexane terephthalate (PCT), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), polycyclohexane dimethylene terephthalate, polypropylene terephthalate, and copolymers thereof. These may be used alone or in combination of two or more.

[0064] Among these, the polyester resin is preferably polybutylene terephthalate or a copolymer thereof. This provides the release layer 11 with excellent conformability to the recesses 223 and excellent release properties.

[0065] Polybutylene terephthalate has a structure in which terephthalic acid, as a dicarboxylic acid component, and 1,4-butanediol, as a diol component, are polycondensed.

[0066] Examples of the copolymer of polybutylene terephthalate include copolymers in which terephthalic acid is partially substituted with another dicarboxylic acid component, copolymers in which 1,4-butanediol is partially substituted with another diol component, copolymers in which terephthalic acid is partially substituted with another dicarboxylic acid component and 1,4-butanediol is partially substituted with another diol component, and the like.

[0067] Examples of dicarboxylic acid components other than terephthalic acid (other dicarboxylic acid components) include naphthalenedicarboxylic acid.

[0068] In this case, the substitution ratio (the ratio of other dicarboxylic acid components to all dicarboxylic acid components constituting the polybutylene terephthalate copolymer) is preferably 2 mol % or more and 50 mol % or less, and more preferably 5 mol % or more and 30 mol % or less, which can effectively improve the releasability of the release layer 11.

[0069] Examples of components other than 1,4-butanediol (other diol components) include polytetramethylene ether glycol and 1,6-hexanediol.

[0070] In this case, the substitution ratio (the ratio of other dicarboxylic acid components to all diol components constituting the polyester resin) is preferably 2 mol % or more and 50 mol % or less, and more preferably 5 mol % or more and 30 mol % or less, which can effectively improve the releasability of the release layer 11.

[0071] The content of the polyester resin in the obtained release layer 11 is not particularly limited, but is preferably 30% by weight or more, and more preferably 50% by weight or more, so that the above-mentioned effects can be more significantly exhibited.

[0072] 3A.1.2. Materials Other Than Polyester Resin The release layer 11 may contain materials other than polyester resin. Examples of materials other than polyester resin include resin materials other than polyester resin, additives such as crosslinking agents, nucleating agents, antioxidants, slip agents, antiblocking agents, antistatic agents, colorants, and stabilizers, and fillers such as inorganic or organic particles.

[0073] Resin materials other than polyester resins (other resin materials) include, but are not limited to, polyolefin resins. Examples of polyolefin resins include, but are not limited to, α-olefin polymers such as polyethylenes such as low-density polyethylene and high-density polyethylene, and polypropylene, and α-olefin copolymers such as copolymers of ethylene and hexene, copolymers of ethylene and octene, copolymers of α-olefins and (meth)acrylic acid esters, copolymers of ethylene and vinyl acetate, and copolymers of ethylene and (meth)acrylic acid, and these may be used alone or in combination of two or more.

[0074] The inorganic particles are not particularly limited, but examples thereof include aluminum hydroxide, magnesium hydroxide, calcium carbonate, magnesium carbonate, calcium silicate, magnesium silicate, calcium oxide, magnesium oxide, alumina, aluminum nitride, aluminum borate whiskers, boron nitride, crystalline silica, amorphous silica, antimony oxide, E-glass, D-glass, S-glass, and the like, and these can be used alone or in combination of two or more.

[0075] The organic particles are not particularly limited, but examples thereof include polystyrene particles, acrylic particles, polyimide particles, polyester particles, silicone particles, polypropylene particles, polyethylene particles, fluororesin particles, and core-shell particles, and one or more of these may be used in combination.

[0076] Furthermore, the inorganic particles and organic particles preferably have an average particle size of 3 μm or more and 40 μm or less, and more preferably 5 μm or more and 30 μm or less, which can more reliably improve the releasability of the release film 10. In addition, the surface roughness (arithmetic mean roughness) of the release layer 11 can be set to a value as described below.

[0077] When the release layer 11 contains a filler, the filler content in the release layer 11 is not particularly limited, but is preferably 1% by weight or more and 30% by weight or less, and more preferably 2% by weight or more and 20% by weight or less. This allows the above effects to be exhibited more significantly.

[0078] When the release layer 11 contains other resin materials, the content of the other resin materials in the release layer 11 is not particularly limited, but is preferably 0.1% by weight or more and 30% by weight or less, and more preferably 1% by weight or more and 20% by weight or less. This allows the effect of present invention A to be exhibited more significantly.

[0079] The total content of materials other than the polyester resin in the release layer 11 is preferably 70% by weight or less, and more preferably 50% by weight or less, so that the content of the polyester resin in the release layer 11 can be sufficiently ensured, and the effect of present invention A can be more significantly obtained.

[0080] 3A. 1.3. Release properties: The release layer 11 satisfies the condition that the water contact angle is 80° or more and 130° or less, and the hydrogen bonding component σ of the surface free energy measured in accordance with ISO 19403. ｈ The condition that the strength is 2.4 mN / m or less is satisfied.

[0081] 2(b), when the FPC 200 using the release film 10 is heated and pressurized, i.e., when the coverlay 221 and the flexible circuit board 210 are bonded via the adhesive layer 222, the release film 10 is embedded in a recess 223 formed in the coverlay 221. At this time, the adhesive layer 222 may protrude, causing partial contact between the release layer 11 of the release film 10 and the adhesive layer 222. When a conventional release film comes into contact with the adhesive layer 222, bonding may occur, resulting in a decrease in releasability.

[0082] In contrast, in the present invention A, the release layer 11 satisfies the condition that the water contact angle is 80° or more and 130° or less, and the hydrogen bonding component σ of the surface free energy measured in accordance with ISO 19403 ｈThe condition that the surface tension of the adhesive layer 222 satisfies is 2.4 mN / m or less. This allows excellent releasability to be exhibited for the adhesive layer 222, which tends to have a relatively large number of hydrophilic groups. Therefore, even when the release layer 11 comes into contact with the adhesive layer 222, excellent releasability can be exhibited. Note that the effect of present invention A can be obtained whether the adhesive layer 222, which comes into contact with the release layer 11, is in a pre-cured state or a semi-cured state. Furthermore, the effect of present invention A can be obtained even when the adhesive layer 222 is cured while in contact with the release layer 11.

[0083] If the contact angle of water in the release layer 11 is less than 80°, the affinity with the hydrophilic group will be too high, resulting in insufficient releasability of the release film 10. On the other hand, if the contact angle of water in the release layer 11 is more than 130°, it will be difficult to select such a material for the polyester resin. The contact angle of water in the release layer 11 can be measured in accordance with ISO 19403.

[0084] In addition, in the release layer 11, the hydrogen bond component σ of the surface free energy ｈ When the surface free energy exceeds 2.4 mN / m, the hydrogen bond component σ ｈ If the value is too high, the bonding strength with the hydrophilic group will be too high, and the adhesive layer 222 will not exhibit excellent releasability.

[0085] The contact angle of water on the release layer 11 may be any angle that satisfies the condition of 80° or more and 130° or less, but it is preferable that the contact angle of water satisfies the condition of 85° or more and 120° or less, and more preferably the condition of 88° or more and 108° or less. This makes it possible to more significantly exhibit the effects of present invention A.

[0086] In addition, in the release layer 11, the hydrogen bond component σ of the surface free energy measured in accordance with ISO 19403 ｈ is sufficient as long as it satisfies the condition of 2.4 mN / m or less, but the hydrogen bond component σ ｈis preferably 0.1 mN / m or more and 2.2 mN / m or less, more preferably 0.2 mN / m or more and 2.0 mN / m or less, and even more preferably 0.3 mN / m or more and 1.8 mN / m or less. This makes it possible to more significantly exhibit the effects of present invention A.

[0087] It has been confirmed that even if the adhesive layer 222 does not protrude, the release layer 11 can exhibit excellent releasability with respect to the CL film 220 .

[0088] Furthermore, it has been confirmed that the adhesive layer 222 exhibits excellent release properties even when it does not have hydrophilic groups.

[0089] The hydrogen bonding component σ of the surface free energy, measured in accordance with ISO 19403, satisfies the condition that the water contact angle is between 80° and 130°. ｈ Methods for obtaining a release layer 11 that satisfies the condition of 2.4 mN / m or less include, for example, selecting a polyester resin material or irradiating the release layer 11 with energy rays such as ultraviolet rays under specified conditions.

[0090] Specifically, a release layer 11 having the above characteristics can be obtained by irradiating the release layer 11 with ultraviolet light under the following conditions.

[0091] Ultraviolet light can be obtained from light sources such as LED lamps, high-pressure mercury lamps, electrodeless lamps, metal halide lamps, and xenon lamps.

[0092] The peak irradiance of the ultraviolet light is 10 mW / cm ２ More than 1000mW / cm ２ Preferably, it is 20 mW / cm². ２ More than 500mW / cm ２ The following is more preferable.

[0093] Furthermore, the cumulative amount of ultraviolet light is 50 mJ / cm². ２ More than 1000mJ / cm ２ Preferably, it is 100 mJ / cm² ２ More than 700mJ / cm ２ The following is more preferable.

[0094] Furthermore, by adjusting the peak illuminance of ultraviolet light, the cumulative light intensity, etc., the hydrogen bonding component σ of the water contact angle and surface free energy can be determined. ｈ In addition, the following parameters, namely the contact angle of diiodomethane and the surface free energy component σ, are also considered. ｄ Parameters such as these can be set to any desired value as appropriate.

[0095] The release layer 11 preferably satisfies the condition that the contact angle of diiodomethane is 20° or more and 50° or less, and more preferably 25° or more and 45° or less. Since the polar component of the surface tension of diiodomethane is 0 mN / m, the dispersive component (for example, the component σ ｄ ) is relatively large. Therefore, by satisfying the condition that the contact angle of diiodomethane is 20° or more and 50° or less, it is possible to sufficiently ensure the non-polarity of release layer 11, and the releasability of release layer 11 can be further improved.

[0096] The contact angle of diiodomethane in the release layer 11 can be measured, for example, in accordance with ISO 19403.

[0097] The release layer 11 has a surface free energy component σ measured in accordance with ISO 19403. ｄ The force (the force generated by the momentary charge imbalance occurring between all molecules) preferably satisfies the condition of 30 mN / m or more and 50 mN / m or less, and more preferably 34 mN / m or more and 45 mN / m or less. This makes it possible to sufficiently ensure the non-polarity of the release layer 11, and further improve the releasability of the release layer 11.

[0098] The release layer 11 preferably has a storage modulus at 180°C of 10 MPa or more and 200 MPa or less, and more preferably 20 MPa or more and 160 MPa or less, as measured in accordance with JIS K 7244. This allows the release layer 11 to have excellent conformability to the recesses 223 and also has excellent releasability.

[0099] Furthermore, the release layer 11 preferably has an arithmetic mean roughness measured in accordance with JIS B0601 of 0.1 μm or more and 5.0 μm or less, and more preferably 0.2 μm or more and 4.0 μm or less. This allows the release properties of the release layer 11 to be further improved.

[0100] Methods for setting the arithmetic mean roughness of the release layer 11 within the above range include, for example, when the release layer 11 contains the filler described above, adjusting the average particle diameter and content of the filler, or pressing a member (e.g., a roller) having the desired surface roughness onto the release layer 11 to transfer the surface shape.

[0101] Furthermore, the inorganic particles and organic particles preferably have an average particle size of 3 μm or more and 40 μm or less, and more preferably 5 μm or more and 30 μm or less, which can more reliably improve the releasability of the release film 10. In addition, the surface roughness (arithmetic mean roughness) of the release layer 11 can be set to the above-mentioned value.

[0102] The degree of crystallinity of the release layer 11 is preferably 20% or more and 70% or less, and more preferably 25% or more and 65% or less, so that the releasability of the release film 10 can be more effectively improved.

[0103] The crystallinity of the release layer 11 can be measured by wide-angle X-ray diffraction analysis using a horizontal sample X-ray diffractometer for thin film evaluation (manufactured by Rigaku Corporation, "Smart Lab"). Specifically, a linear baseline is drawn within the range of 2θ = 12.0 ° to 28.18 ° on a diffraction measurement plot measured using the horizontal sample X-ray diffractometer for thin film evaluation, and then Gaussian functions are fitted to the crystalline phase and the amorphous phase, respectively. Based on the total peak area of ​​the crystalline phase and the total peak area of ​​the amorphous phase obtained thereby, the crystallinity of the release layer 11 is calculated using the following formula (A).

[0104] Crystallinity (%) = total peak area of ​​crystalline phase / (total peak area of ​​crystalline phase + total peak area of ​​amorphous phase) × 100 (A)

[0105] The release layer 11 preferably has an average thickness T1 of 5 μm or more and 35 μm or less, and more preferably 10 μm or more and 25 μm or less, so that the above-mentioned effects can be more significantly exhibited.

[0106] 3A.2. Cushion Layer 12 The release film 10 has a cushion layer 12 provided on one side of the release layer 11. This provides the release film 10 with the ability to conform to and embed into the recesses 223.

[0107] Although there are no particular limitations on the material that constitutes the cushion layer 12, it is preferably a thermoplastic resin. Examples of the thermoplastic resin include polyester resin and polyolefin resin, and one of these may be used alone or two of them may be used in combination.

[0108] By selecting a combination of polyester resin and polyolefin resin as the constituent material of the cushion layer 12, it is possible to more reliably improve the conformability and embeddability of the release film 10 to the recesses 223.

[0109] The storage modulus of the cushion layer 12 at 150°C is preferably 0.1 MPa to 200 MPa, more preferably 0.5 MPa to 150 MPa, and even more preferably 1 MPa to 100 MPa. This effectively suppresses or prevents a portion of the cushion layer 12 from protruding from the edge of the release film 10 and adhering to the FPC 200 when the release film 10 is embedded in the recess 223. Therefore, the release film 10 can be easily peeled off.

[0110] The storage modulus of the cushion layer 12 at 150°C can be obtained, for example, by preparing a cushion layer 12 with a width of 4 mm and a length of 20 mm in accordance with JIS K7244-4, and measuring it using a dynamic viscoelasticity measuring device (Hitachi High-Tech Science Corporation, "DMA7100") in tensile mode, with a frequency of 1 Hz and a heating rate of 5°C / min.

[0111] Thus, the cushion layer 12 has a storage modulus of 0.1 MPa or more and 200 MPa or less at 150° C. as measured in accordance with JIS K7244-4, which makes it possible to easily peel off the release film 10.

[0112] The cushion layer 12 preferably has an average thickness T2 of 10 μm or more and 200 μm or less, and more preferably 30 μm or more and 100 μm or less, so that the cushion layer 12 can more significantly function.

[0113] The average thickness T of such a release film 10 is preferably 20 μm or more and 300 μm or less, and more preferably 40 μm or more and 200 μm or less, so that the above-mentioned effects can be more significantly exhibited.

[0114] Although the release film of Invention A has been described above, Invention A is not limited thereto.

[0115] In this embodiment, the release layer 11 is provided on one side of the cushion layer 12, but the present invention A is not limited to this and may be provided on both sides of the cushion layer 12. Furthermore, the cushion layer 12 may be omitted.

[0116] For example, in the above embodiment, the case where the release film of present invention A is applied to a press molding method in which flexible printed circuit boards arranged between thermocompression plates are laminated in one layer to produce the film has been described. However, the number of laminated flexible printed circuit boards is not limited to one layer, and may be two or more layers.

[0117] Furthermore, although the release film of present invention A is applied to a case where it is pressed against a flexible printed circuit board arranged between thermocompression plates using a roll-to-roll press, the present invention is not limited to this, and the pressurization of the flexible printed circuit board can also be carried out using, for example, a press molding method, or even a vacuum pressure molding method.

[0118] The present invention A will be described in detail below based on examples, but the present invention A is not limited thereto.

[0119] 4A. Preparation of raw materials The following materials were prepared as raw materials for manufacturing the release film.

[0120] - Polybutylene terephthalate (manufactured by Mitsubishi Chemical Corporation, "Novaduran 5020") (hereinafter referred to as "hPBT") - Polybutylene terephthalate copolymer (manufactured by Mitsubishi Chemical Corporation, "Novaduran 5505S") (hereinafter referred to as "coPBT") - Polybutylene terephthalate copolymer (manufactured by Bell Polyester Products, Inc., "P02220") (hereinafter referred to as "C-coPBT") - Ethylene-methyl methacrylate copolymer (manufactured by Sumitomo Chemical Co., Ltd., "WD203-1") (hereinafter referred to as "EMMA") - Polypropylene (manufactured by Prime Polypropylene, Inc., "E111G") (hereinafter referred to as "PP")

[0121] 5A. Production of Release Film Example 1A First, 70 parts by weight of hPBT and 30 parts by weight of coPBT were mixed to obtain a material for forming the release layer 11.

[0122] Also, 55 parts by weight of EMMA, 20 parts by weight of PP, and 25 parts by weight of hPBT were mixed together to obtain a cushion layer forming material for forming the cushion layer 12 .

[0123] Next, two extruders were prepared, and the material for forming the release layer was supplied to one extruder and the material for forming the cushion layer was supplied to the other extruder. They were co-extruded from a multi-manifold die to obtain a release film 10 in which the release layer 11 and the cushion layer 12 were laminated in this order. In the obtained release film 10, the thickness of the release layer 11 was 20 μm.

[0124] Furthermore, the thickness of the cushion layer 12 was 80 μm. The thickness of the release film 10 was 100 μm.

[0125] <Examples 2A to 7A, Comparative Examples 1A and 2A> Except for changing the constituent materials and content of the release layer forming material as shown in Table 1, the release films 10 of Examples 2A to 7A and Comparative Examples 1A and 2A were obtained in the same manner as in Example 1A.

[0126] 6A. Evaluation The release film 10 of each example and each comparative example was evaluated as follows.

[0127] 6A. 1. Releasability (1) Release film 10 of each example and comparative example was made to have a width of 270 mm. Coverlay film 220 (manufactured by Arisawa Manufacturing Co., Ltd., "CMA0525") was laminated on flexible circuit board 210 with adhesive layer 222 of coverlay film 220 facing flexible circuit board 210 to form FPC 200 (laminate) having irregularities with a pitch of 50 μm, a width of 50 μm, and a height of 18 μm. Release film 10 was then applied to FPC 200 laminated as shown in FIG. 3 using a R-to-R press (manufactured by TRM, "RR Q-CURE 100TON CONTINUOUS LAMINATOR") at 180°C and 110 kg / cm. ２ , and pressed in under set conditions of 150 seconds. Thereafter, a configuration in which a rod is sandwiched between the FPC 200 and the release film 10 to separate them was applied as the releasing means 60, and the release film 10 was peeled off at a conveying speed of 200 mm / sec, a feed amount of 500 mm, and a distance from the heating and pressing plate 521 to the releasing means 60 of 50 mm. The ease of peeling (releasability) of the release film 10 at this time was evaluated according to the following criteria.

[0128] [Evaluation Criteria] ○: The release film can be peeled off. ×: The release film is difficult to peel off due to stretching or tearing.

[0129] 6A. 2. Release properties (2) The peel strength of the release film was evaluated as follows.

[0130] For the release film 10 of each example and each comparative example, the release layer 11 was placed on the coverlay film 220 (manufactured by Nikkan Industries Co., Ltd., "CISV2535") so that the release layer 11 was in contact with the adhesive layer 222 provided on the coverlay film 220, and the release film 10 was pressed under vacuum conditions of 185°C and 20 kg / cm using a quick press machine (manufactured by TRM Co., Ltd., "HH46 LAMINATOR"). ２ The pressing was performed under the set conditions of a vacuuming time of 10 seconds and a molding time of 100 seconds. The film was cut to a width of 25 mm, and a peel test was performed by pulling the coverlay film 220 at a test speed of 300 mm / min and a peel angle of 90°, and the film was evaluated according to the following evaluation criteria.

[0131] [Evaluation Criteria] A value of less than 3.0 N / 25 mm was considered a pass, and a value of 3.0 N / 25 mm or more was considered a fail.

[0132] 6A. 3. Summary Table 1 shows the composition of each example and each comparative example, along with the evaluation results obtained for release properties (1) and (2).

[0133]

[0134] As shown in Table 1, the release layer satisfies the condition that the contact angle of water is 80° or more and 130° or less, and the hydrogen bond component σ of the surface free energy measured in accordance with ISO 19403 is ｈ Each example that met the condition of having a release factor of 2.4 mN / m or less showed excellent release properties.

[0135] In contrast, as shown in Table 1, the release layer is formed under the condition that the contact angle of water is 80° or more and 130° or less, and the hydrogen bond component σ of the surface free energy measured in accordance with ISO 19403 is σ ｈ Each comparative example that did not satisfy at least one of the conditions of 2.4 mN / m or less showed results that could not be said to have excellent mold release properties.

[0136] 1B. Summary of Invention B The release film of Invention B is a release film that includes a resin layer containing a polyester resin and is used by contacting an object, the resin layer having a first layer and a second layer that is provided in contact with the first layer and contacts the object, and the first layer has an intensity I at 284 eV when measured by X-ray photoelectron spectroscopy. Ａ２８４And, when measured by X-ray photoelectron spectroscopy, the intensity I at 288 eV Ａ２８８ Relative to I Ａ２８８ / I Ａ２８４ is 0.2 or more and less than 0.5, and the second layer has an average thickness of 10 nm or more and 500 nm or less, and an intensity I at 284 eV when measured by X-ray photoelectron spectroscopy. Ｂ２８４ And, when measured by X-ray photoelectron spectroscopy, the intensity I at 288 eV Ｂ２８８ Relative to I Ｂ２８８ / I Ｂ２８４ The value must satisfy the condition of being 0.14 or greater and less than 0.3.

[0137] In Invention B, because polyester is used, a release film can be obtained inexpensively. Furthermore, when the release film is pressed against an object so that the second layer contacts it, and then peeled off from the object, the object and the release film may adhere to each other and be partially bonded. In such cases, by having the first and second layers with the characteristics and thicknesses described above, a portion of the second layer can be separated from the first layer so that a portion of the second layer remains on the object side (this will be described in detail later). Therefore, when the release film is peeled off from the object, the operation can be performed smoothly and satisfactorily with excellent releasability.

[0138] Furthermore, even if the release film and the adhesive layer do not come into contact, excellent release properties can still be achieved.

[0139] Based on the above, the release film of the present invention B can be used to obtain an inexpensive release film with excellent release properties.

[0140] Furthermore, if the first and second layers do not satisfy the above conditions, the effects of the present invention B cannot be obtained. This will be explained in detail later.

[0141] 2B. Method of Using the Release Film The method of using the release film of present invention B is substantially the same as the method explained in "2A. Method of Using the Release Film," and therefore, the explanation thereof will be omitted.

[0142] 3B. Release Film 10 Fig. 7 is a longitudinal sectional view showing an embodiment of the release film of invention B. Fig. 8 is a partially enlarged longitudinal sectional view showing part B of the release film shown in Fig. 7.

[0143] 7, as described above, the release film 10 is used by being brought into contact with the CL film 220, which is an example of an object, and has a resin layer 1 containing a polyester resin. Although not shown, the release film 10 may have other functional layers such as a cushion layer. When the release film 10 has a cushion layer, it can be provided with the ability to embed recesses 223 into the release film 10.

[0144] 3B.1. Resin Layer 1 As shown in FIGS. 7 and 8, the resin layer 1 includes a first layer 110, which will be described in detail later, and a second layer 120 that is provided in contact with the first layer 110 and abuts the CL film 220.

[0145] The resin layer 1 contains a polyester resin, which allows the resin layer 1 to be inexpensive and have excellent release properties. The resin layer 1 can be produced from a resin layer-forming material containing a polyester resin.

[0146] For example, a resin film that will become the resin layer 1 can be obtained by supplying a resin layer-forming material to an extruder, extruding it through a manifold die, and cooling it. Alternatively, one side of the resin film can be irradiated with energy rays to modify the surface, thereby obtaining the resin layer 1 having the first layer 110 and the second layer 120. The second layer 120 is a layer that is formed by modification through energy ray irradiation.

[0147] Examples of the type of energy beam include ultraviolet light and electron beams. Among these, electron beams are preferred. This allows the second layer 120 to be formed effectively. When electron beams are used as the energy beams, the intensity thereof is preferably 1 keV or more and 100 keV or less, and more preferably 5 keV or more and 50 keV or less. This allows the first layer 110 and the second layer 120 to be formed more effectively.

[0148] When an electron beam is used as the energy beam, the irradiation time is preferably 5 seconds or more and 60 seconds or less, and more preferably 10 seconds or more and 40 seconds or less, so that the first layer 110 and the second layer 120 can be formed more effectively.

[0149] 3B. 1.1. Materials for forming resin layers The materials for forming resin layers include polyester resin.

[0150] 3B. 1.1.1. Polyester Resin A polyester resin is a polymer compound having a structure in which a diol component and a dicarboxylic acid component are polycondensed (for example, a weight-average molecular weight Mw of 1,000 to 1,000,000). Specifically, there are no particular limitations on the polyester resin, but examples include polyethylene terephthalate (PET), polycyclohexane terephthalate (PCT), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), polycyclohexane dimethylene terephthalate, polypropylene terephthalate, and copolymers thereof, and one or more of these can be used in combination.

[0151] Among these, the polyester resin is preferably polybutylene terephthalate or a copolymer thereof, which can provide the resin layer 1 with excellent conformability to the recesses 223 and excellent releasability.

[0152] Polybutylene terephthalate has a structure obtained by polycondensation of terephthalic acid as a dicarboxylic acid component and 1,4-butanediol as a diol component.

[0153] Examples of copolymers of polybutylene terephthalate include those in which a portion of terephthalic acid is substituted with another dicarboxylic acid component, those in which a portion of 1,4-butanediol is substituted with another diol component, and those in which a portion of terephthalic acid is substituted with another dicarboxylic acid component and a portion of 1,4-butanediol is substituted with another diol component.

[0154] Other dicarboxylic acid components besides terephthalic acid include naphthalenedicarboxylic acid, among others.

[0155] In this case, the substitution ratio (the ratio of other dicarboxylic acid components to all dicarboxylic acid components constituting the polybutylene terephthalate copolymer) is preferably 2 mol % to 50 mol %, more preferably 5 mol % to 30 mol %, which allows the first layer 110 and the second layer 120 that satisfy the above-mentioned conditions to be easily and accurately formed.

[0156] Examples of diol components other than 1,4-butanediol include polytetramethylene ether glycol and 1,6-hexanediol.

[0157] In this case, the substitution ratio (the ratio of other dicarboxylic acid components to all diol components constituting the polyester resin) is preferably 2 mol % or more and 50 mol % or less, and more preferably 5 mol % or more and 30 mol % or less, which allows the first layer 110 and the second layer 120 that satisfy the above-mentioned conditions to be easily and accurately formed.

[0158] The content of the polyester resin in the obtained resin layer 1 is not particularly limited, but is preferably 30% by weight or more, and more preferably 50% by weight or more, so that the above-mentioned effects can be more significantly exhibited.

[0159] 3B.1.1.2. Materials Other Than Polyester Resin The resin layer forming material may contain materials other than polyester resin. Examples of materials other than polyester resin include resin materials other than polyester resin, additives such as crosslinking agents, crystal nucleating agents, antioxidants, slip agents, antiblocking agents, antistatic agents, colorants, and stabilizers, and fillers such as inorganic or organic particles.

[0160] Resin materials other than polyester resins (other resin materials) include, but are not limited to, polyolefin resins. Examples of polyolefin resins include, but are not limited to, α-olefin polymers such as polyethylenes such as low-density polyethylene and high-density polyethylene, polypropylene, and α-olefin copolymers such as copolymers of ethylene and hexene, copolymers of ethylene and octene, copolymers of α-olefins and (meth)acrylic acid esters, copolymers of ethylene and vinyl acetate, and copolymers of ethylene and (meth)acrylic acid. These copolymers may be used alone or in combination of two or more.

[0161] The inorganic particles are not particularly limited, but examples thereof include those described in Invention A.

[0162] The organic particles are not particularly limited, but examples thereof include polystyrene particles, acrylic particles, polyimide particles, polyester particles, silicone particles, polypropylene particles, polyethylene particles, fluororesin particles, and core-shell particles, and one or more of these may be used in combination.

[0163] Furthermore, the inorganic and organic particles preferably have an average particle diameter of 3 μm to 40 μm, and more preferably 5 μm to 30 μm. This makes it easier for the second layer 120 to separate from the first layer 110, and more reliably improves the release properties of the release film 10.

[0164] When the resin layer forming material contains a filler, the filler content in the resin layer 1 is not particularly limited, but is preferably 1% by weight or more and 30% by weight or less, and more preferably 2% by weight or more and 20% by weight or less. This allows the above effects to be exhibited more significantly.

[0165] When the resin layer-forming material contains other resin materials, the content of the other resin materials in the resin layer 1 is not particularly limited, but is preferably 0.1% by weight or more and 30% by weight or less, and more preferably 1% by weight or more and 20% by weight or less, thereby enabling the effects of the present invention to be more significantly exhibited.

[0166] The total content of materials other than the polyester resin in the resin layer 1 is preferably 70% by weight or less, and more preferably 50% by weight or less, which ensures a sufficient content of the polyester resin in the resin layer 1 and allows the effects of the present invention to be more pronounced.

[0167] 3B.1.2. First Layer 110 and Second Layer 120 As described above, the resin layer 1 has a first layer 110 and a second layer 120. As shown in FIG. 6B , when the FPC 200 using the release film 10 is heated and pressurized, i.e., when the coverlay 221 and the flexible circuit board 210 are bonded via the adhesive layer 222, the release film 10 is embedded in a recess 223 formed in the coverlay 221. At this time, the adhesive layer 222 may protrude, causing partial contact between the second layer 120 of the release film 10 and the adhesive layer 222. In this case, for example, a hydrogen bond is formed between a hydroxyl group (OH group) or the like contained in the constituent material of the adhesive layer 222 and an oxygen atom contained in a carbonyl group (C═O) or ether group contained in the constituent material of the second layer 120. This bonding force is stronger than the bonding force between the first layer 110 and the second layer 120, and when the release film 10 is detached from the CL film 220, it can be detached from the first layer 110 with at least a portion of the second layer 120 in contact with the adhesive layer 222. In other words, by preferentially detaching the portion of the second layer 120 bonded to the adhesive layer 222 from the first layer 110, as shown in Figure 6(c), a portion of the second layer 120 remains on the CL film 220 side, and as a result, the release film 10 can be easily detached from the CL film 220. In other words, the releasability of the release film 10 can be improved.

[0168] Furthermore, even if the adhesive layer 222 does not protrude, i.e., even if the second layer 120 does not remain on the CL film 220 side, the second layer 120 can exhibit excellent releasability with respect to the CL film 220.

[0169] The adhesive constituting the adhesive layer 222 is not particularly limited, and examples thereof include an epoxy-based adhesive, an acrylic-based adhesive, etc. In particular, when the adhesive layer 222 is made of an epoxy-based adhesive, the above-mentioned effect can be more significantly exhibited.

[0170] In this way, the CL film 220, which is the target object, has the adhesive layer 222, which is an epoxy adhesive layer, and when the release film 10 is brought into contact with the CL film 220 and then removed, the second layer 120 is removed from the first layer 110 with at least a portion of the second layer 120 in contact with the adhesive layer 222. This makes it possible to more effectively improve the releasability of the release film 10.

[0171] Furthermore, the same effect as above has been confirmed even when the functional group of the constituent material of the second layer 120 is bonded to a functional group other than a hydroxyl group (OH group), such as an amino group or a carboxyl group (COOH).

[0172] The boundary between the first layer 110 and the second layer 120 may be clear or unclear.

[0173] The present inventors have conducted extensive research and discovered that the above-described effects can be achieved by making the first layer 110 and the second layer 120 satisfy the following conditions, thereby completing the present invention.

[0174] The first layer 110 has an intensity I at 284 eV when measured by X-ray photoelectron spectroscopy. Ａ２８４ And, when measured by X-ray photoelectron spectroscopy, the intensity I at 288 eV Ａ２８８ Relative to I Ａ２８８ / I Ａ２８４ satisfies the condition of being equal to or greater than 0.2 and less than 0.5.

[0175] Furthermore, the second layer 120 has an average thickness T1 of 10 nm or more and 500 nm or less, and the intensity I at 284 eV when measured by X-ray photoelectron spectroscopy is Ｂ２８４ And, when measured by X-ray photoelectron spectroscopy, the intensity I at 288 eV Ｂ２８８ Relative to I Ｂ２８８ / I Ｂ２８４ The value must satisfy the condition of being 0.14 or greater and less than 0.3.

[0176] X-ray photoelectron spectroscopy (ESCA) is an analytical method that obtains information about the elemental composition and chemical state of a sample by observing the kinetic energy of photoelectrons emitted from the sample surface into the vacuum due to the photoelectric effect when the sample surface is irradiated with soft X-rays (wavelength: 0.1 nm to 10 nm) under ultra-high vacuum.

[0177] Strength I Ａ２８４ This is the kinetic energy of photoelectrons emitted when soft X-rays with an intensity of 284 eV are irradiated onto the first layer 110. Ａ２８４ This value fluctuates primarily due to the content of CH groups (tertiary carbon atoms) and C groups (quaternary carbon atoms).

[0178] Strength I Ｂ２８４ This is the kinetic energy of photoelectrons emitted when soft X-rays with an intensity of 284 eV are irradiated onto the second layer 120. Ｂ２８４ This value is primarily determined by the content of CH and C groups.

[0179] Strength I Ａ２８８ This is the kinetic energy of photoelectrons emitted when soft X-rays with an intensity of 288 eV are irradiated onto the first layer 110. Ａ２８８ This value is primarily determined by the amount of C=O groups present.

[0180] Strength I Ｂ２８８ This is the kinetic energy of photoelectrons emitted when soft X-rays with an intensity of 288 eV are irradiated onto the second layer 120. Ｂ２８８ This value is primarily determined by the amount of C=O groups present.

[0181] In the first layer 110 and the second layer 120, ratio I Ａ２８８ / I Ａ２８４ , Relative I Ｂ２８８ / I Ｂ２８４ By setting each of these values ​​within the above ranges, even if the second layer 120 of the release film 10 and the adhesive layer 222 are in partial contact, a portion of the second layer 120 can be separated from the first layer 110 so that a portion of the second layer 120 remains on the CL film 220 side. Therefore, when the release film 10 is to be separated from the CL film 220, the operation can be performed smoothly and satisfactorily with excellent releasability.

[0182] In contrast, if the above numerical range is not met, the effects of the present invention cannot be obtained. Specifically, in the first layer 110, ratio I Ａ２８８ / I Ａ２８４ If the ratio I is less than 0.2, the content of C═O groups in the first layer 110 is too small, resulting in poor adhesion at the interface between the first layer 110 and the second layer 120, and the second layer 120 cannot be easily separated from the first layer 110. Ａ２８８ / I Ａ２８４ If the ratio is 0.5 or more, the content of C═O groups in the first layer 110 is too high, resulting in poor interfacial adhesion, and the second layer 120 cannot be separated from the first layer 110 well.

[0183] In addition, in the second layer 120, the ratio I Ｂ２８８ / I Ｂ２８４ If the ratio I is less than 0.14, the content of C=O groups in the second layer 120 is too low, which weakens the adhesion between the second layer 120 and the object, making it difficult for the second layer to be separated from the first layer. Ｂ２８８ / I Ｂ２８４ If the ratio is 0.3 or more, the content of CH groups and C groups in the second layer is too small, resulting in poor interfacial adhesion between the first layer 110 and the second layer 120, and preventing the second layer from separating from the first layer.

[0184] Furthermore, if the average thickness T1 of the second layer 120 is less than 10 nm, a portion of the second layer 120 is unlikely to remain on the CL film 220 side, and the effect of the present invention cannot be sufficiently obtained.

[0185] Furthermore, if the average thickness T1 of the second layer 120 exceeds 500 nm, the second layer 120 cannot be properly separated from the first layer 110, and the effects of the present invention cannot be fully obtained.

[0186] In the first layer 110, ratio I Ａ２８８ / I Ａ２８４ While a value of 0.2 or more and less than 0.5 is acceptable, it is preferably 0.25 or more and 0.45 or less, and more preferably 0.3 or more and 0.4 or less. This allows the above effects to be exhibited more significantly.

[0187] In the second layer 120, ratio I Ｂ２８８ / I Ｂ２８４ While it is acceptable for the value to be between 0.14 and less than 0.3, it is preferable that it be between 0.18 and 0.28, and more preferably between 0.2 and 0.25. This allows the above effects to be exhibited more significantly.

[0188] The second layer 120 may have an average thickness T1 of 10 nm or more and 500 nm or less, but it is preferably 15 nm or more and 450 nm or less, and more preferably 20 nm or more and 400 nm or less. This allows the above effects to be exhibited more significantly.

[0189] Furthermore, the first layer 110 showed an intensity of I at 284 eV when measured by X-ray photoelectron spectroscopy. Ａ２８４ And, when measured by X-ray photoelectron spectroscopy, the intensity I at 532 eV Ａ５３２ Relative to I Ａ５３２ / I Ａ２８４ However, it is preferable that the value is between 0.5 and less than 1.0, and more preferably that it is between 0.6 and less than 0.9. This makes it possible to more effectively improve the release properties of the release film 10.

[0190] Furthermore, the second layer 120 showed an intensity of I at 284 eV when measured by X-ray photoelectron spectroscopy. Ｂ２８４ And, when measured by X-ray photoelectron spectroscopy, the intensity I at 532 eV Ｂ５３２ Relative to I Ｂ５３２ / I Ｂ２８４However, it is preferable that the value is between 0.5 and less than 1.0, and more preferably that it is between 0.6 and less than 0.9. This makes it possible to more effectively improve the release properties of the release film 10.

[0191] The crystallinity of the first layer 110 is preferably 20% or more and 70% or less, and more preferably 25% or more and 65% or less, so that the releasability of the release film 10 can be more effectively improved.

[0192] The crystallinity of the second layer 120 is preferably 40% or more and 80% or less, and more preferably 45% or more and 65% or less, so that the releasability of the release film 10 can be more effectively improved.

[0193] It is preferable that the crystallinity of the first layer 110 is 20% or more and 70% or less, and the crystallinity of the second layer 120 is 40% or more and 80% or less. This makes it possible to more effectively improve the releasability of the release film 10.

[0194] The crystallinity of the first layer 110 and the second layer 120 can be measured by analyzing them using wide-angle X-ray diffraction with a horizontal X-ray diffractometer for thin film evaluation (Rigaku Corporation, "Smart Lab"). Specifically, a linear baseline is drawn on the diffraction measurement plot measured by the horizontal X-ray diffractometer for thin film evaluation within the range of 2θ = 12.0° to 28.18°, and then Gaussian functions are fitted to the crystalline and amorphous phases, respectively. Based on the total peak area of ​​the crystalline phase and the total peak area of ​​the amorphous phase obtained in this way, the crystallinity of the first layer 110 and the second layer 120 is calculated using the following formula A.

[0195] Crystallinity (%) = Total peak area of ​​crystalline phase / (Total peak area of ​​crystalline phase + Total peak area of ​​amorphous phase) × 100 ... Equation (A)

[0196] The first layer 110 and the second layer 120 having the above-mentioned properties can be obtained by appropriately adjusting various conditions such as the composition of the polyester resin and the conditions for irradiating the energy rays during production.

[0197] Although the release film of the present invention has been described above, the present invention is not limited thereto.

[0198] For example, in the above embodiment, the case where the release film of the present invention is applied to a press molding method in which flexible printed circuit boards arranged between thermocompression plates are stacked in one layer to produce the film has been described. However, the number of stacked flexible printed circuit boards is not limited to one layer, and may be two or more layers.

[0199] Furthermore, although the release film of the present invention is applied to a case where it is pressed against a flexible printed circuit board arranged between thermocompression plates using a roll-to-roll press, the present invention is not limited to this, and the pressurization of the flexible printed circuit board can be carried out, for example, by a press molding method, or further by a vacuum pressure molding method.

[0200] Hereinafter, the present invention B will be described in detail based on examples, but the present invention B is not limited to these examples.

[0201] 4B. Preparation of Raw Materials The following raw materials were prepared for producing the release film.

[0202] - Polybutylene terephthalate (manufactured by Mitsubishi Chemical Corporation, "Novaduran 5020") (hereinafter referred to as "hPBT") - Polybutylene terephthalate copolymer (manufactured by Mitsubishi Chemical Corporation, "Novaduran 5505S") (hereinafter referred to as "coPBT") - Polybutylene terephthalate copolymer (manufactured by Bell Polyester Products, Inc., "P02220") (hereinafter referred to as "C-coPBT")

[0203] 5B. Production of Release Film Example 1B First, 70% by weight of hPBT and 30% by weight of coPBT were mixed to obtain a material for forming a resin layer.

[0204] Next, this resin layer forming material was fed into an extruder and extruded through a manifold die to obtain a resin film that would become the resin layer 1 .

[0205] Next, an electron beam was irradiated from one side of the resin film to obtain a release film 10 of Example 1B having a resin layer 1 including a first layer 110 that is an unmodified portion and a second layer 120 that is a portion modified by electron beam irradiation. The electron beam irradiation time was 10 seconds, and the electron beam intensity was 10 keV.

[0206] Furthermore, in the obtained release film 10, ratio I Ａ２８８ / I Ａ２８４ It is 0.213, and ratio I Ｂ２８８ / I Ｂ２８４ The value was 0.181. In addition, the thickness of the second layer 120 in the obtained release film 10 was 10 nm.

[0207] <Examples 2B to 6B, Comparative Examples 1B to 5B> Except for changing the constituent materials, content, and electron beam irradiation amount of the release layer forming material as shown in Table 2, release films 10 of Examples 2B to 6B and Comparative Examples 1B to 5B were obtained in the same manner as in Example 1B.

[0208] 6B. Evaluation The release film 10 of each example and each comparative example was evaluated as follows.

[0209] 6B-1. Releasability of Release Film (1) The release film 10 of each example and comparative example was set to a width of 270 mm, and a cover lay film 220 (manufactured by Arisawa Manufacturing Co., Ltd., "CMA0525") was attached to a flexible circuit board 210 with the adhesive layer 222 of the cover lay film 220 facing the flexible circuit board 210 to form an FPC 200 (laminate) having irregularities with a pitch of 50 μm, a width of 50 μm, and a height of 18 μm. The release film 10 was then applied to the laminated FPC 200 as shown in FIG. 3 using a R-to-R press (manufactured by TRM, "RR Q-CURE 100TON CONTINUOUS LAMINATOR") at 180°C and 110 kg / cm. ２, and pressed in under set conditions of 150 seconds. Thereafter, a configuration in which a rod is sandwiched between the FPC 200 and the release film 10 to separate them was applied as the releasing means 60, and the release film 10 was peeled off at a conveying speed of 200 mm / s, a feed amount of 500 mm, and a distance from the heating and pressing plate 521 to the releasing means 60 of 50 mm. The ease of peeling (releasability) of the release film 10 at this time was evaluated according to the following criteria.

[0210] [Evaluation Criteria] ◯: The release film can be peeled off. ×: When the release film is peeled off, it is difficult to peel off due to stretching or breaking of the release film.

[0211] 6B. 2. Releasability of Release Film (2) The peel strength of the release film was evaluated as follows.

[0212] The release film 10 of each example and each comparative example was laminated so that the second layer 120 was in contact with the adhesive layer 222 of the coverlay film 220 (manufactured by Nikkan Industries Co., Ltd., "CISV2535"), and the laminate was pressed under vacuum conditions of 185°C and 20 kg / cm using a quick press machine (manufactured by TRM Co., Ltd., "HH46 LAMINATOR"). ２ The pressing was performed under the set conditions of a vacuuming time of 10 seconds and a molding time of 100 seconds. The film was cut to a width of 25 mm, and a peel test was performed by pulling the coverlay film 220 at a test speed of 300 mm / min and a peel angle of 90°, and the film was evaluated according to the following evaluation criteria.

[0213] [Evaluation Criteria] A value of less than 3.0 N / 25 mm was considered a pass, and a value of 3.0 N / 25 mm or more was considered a fail.

[0214] 6B-3. Summary Table 2 shows the evaluation results obtained in the above 6B-1. Releasability of release film (1) and the above 6B-2. Releasability of release film (2).

[0215]

[0216] As shown in Table 2, in each example, the first layer had an intensity I at 284 eV when measured by X-ray photoelectron spectroscopy. Ａ２８４ And, when measured by X-ray photoelectron spectroscopy, the intensity I at 288 eV Ａ２８８ Relative to IＡ２８８ / I Ａ２８４ is 0.2 or more and less than 0.5, and the second layer has an average thickness of 10 nm or more and 500 nm or less, and an intensity I at 284 eV when measured by X-ray photoelectron spectroscopy. Ｂ２８４ And, when measured by X-ray photoelectron spectroscopy, the intensity I at 288 eV Ｂ２８８ Relative to I Ｂ２８８ / I Ｂ２８４ Since the condition of 0.14 or more and less than 0.3 is satisfied, the results showed excellent releasability.

[0217] In contrast, in each comparative example, the first layer had an intensity I at 284 eV when measured by X-ray photoelectron spectroscopy. Ａ２８４ And, when measured by X-ray photoelectron spectroscopy, the intensity I at 288 eV Ａ２８８ Relative to I Ａ２８８ / I Ａ２８４ is 0.2 or more and less than 0.5, and the second layer has an average thickness of 10 nm or more and 500 nm or less, and an intensity I at 284 eV when measured by X-ray photoelectron spectroscopy. Ｂ２８４ And, when measured by X-ray photoelectron spectroscopy, the intensity I at 288 eV Ｂ２８８ Relative to I Ｂ２８８ / I Ｂ２８４ The condition of 0.14 or more and less than 0.3 was not satisfied, and as a result, the results showed that the releasability was not excellent.

[0218] According to the present invention, it is possible to provide a release film that is inexpensive and has excellent release properties. Therefore, the present invention has industrial applicability.

[0219] DESCRIPTION OF SYMBOLS 10 Release film 10A Release film 10B Release film 11 Release layer 12 Cushion layer 110 First layer 120 Second layer 50 Heat press means 52 Heat compression bonding unit 60 Release means 100 Roll-to-roll press machine (RtoR press machine) 200 Flexible printed circuit board (FPC) 210 Flexible circuit board 220 Coverlay film (CL film) 221 Coverlay 222 Adhesive layer 223 Recess 300A Glass cloth 300B Glass cloth 521 Heat compression bonding plate T1 Average thickness of release layer T2 Average thickness of cushion layer T Average thickness of release film

Claims

1. A release film having a release layer containing a polyester resin, wherein the release layer satisfies the condition that the water contact angle is 80° or more and 130° or less, and the hydrogen bond component σ of the surface free energy measured in accordance with ISO 19403 ｈ A release film characterized in that it satisfies the condition that the surface tension is 2.4 mN / m or less.

2. The release film according to claim 1, wherein the release layer satisfies the condition that the storage modulus at 180° C. measured in accordance with JIS K7244 is 10 MPa or more and 200 MPa or less.

3. The release film according to claim 1 or 2, wherein the release layer satisfies the condition that the contact angle of diiodomethane is 20° or more and 50° or less.

4. The release film according to claim 1 or 2, wherein the release layer satisfies the condition that the arithmetic mean roughness measured in accordance with JIS B0601 is 0.1 μm or more and 5.0 μm or less.

5. The release layer has a surface free energy component σ measured in accordance with ISO 19403 ｄ 3. The release film according to claim 1, wherein the surface tension satisfies the condition of 30 mN / m or more and 50 mN / m or less.

6. The release film according to claim 1 or 2, wherein the release layer has an average thickness of 5 μm or more and 35 μm or less.

7. The release film according to claim 1 or 2, wherein the release film is used by superimposing the surface of the release layer on the surface of an object having an adhesive layer so that the surface on the release layer side is in contact with the surface.

8. The release film according to claim 6, further comprising a cushion layer provided on one side of said release layer.

9. The release film according to claim 8, wherein the cushion layer has a storage modulus at 150° C. measured in accordance with JIS K7244-4 of 0.1 MPa or more and 200 MPa or less.

10. The release film according to claim 8, wherein the cushion layer has an average thickness of 10 μm or more and 200 μm or less.

11. A release film having a resin layer containing a polyester resin and used in contact with an object, wherein the resin layer has a first layer and a second layer that is provided in contact with the first layer and contacts the object, and the first layer has an intensity I at 284 eV when measured by X-ray photoelectron spectroscopy. Ａ２８４ and the intensity I at 288 eV when measured by the X-ray photoelectron spectroscopy. Ａ２８８ Relative to I Ａ２８８ / I Ａ２８４ is 0.2 or more and less than 0.5, and the second layer has an average thickness of 10 nm or more and 500 nm or less, and an intensity I at 284 eV when measured by the X-ray photoelectron spectroscopy Ｂ２８４ and the intensity I at 288 eV when measured by the X-ray photoelectron spectroscopy. Ｂ２８８ Relative to I Ｂ２８８ / I Ｂ２８４ A release film characterized in that it satisfies the condition that the viscosity is 0.14 or more and less than 0.

3.

12. The first layer has an intensity I at 284 eV when measured by the X-ray photoelectron spectroscopy. Ａ２８４ and the intensity I at 532 eV when measured by the X-ray photoelectron spectroscopy. Ａ５３２ Relative to I Ａ５３２ / I Ａ２８４ The release film according to claim 11, wherein the value satisfies the condition that the value is 0.5 or more and less than 1.

0.

13. The second layer has an intensity I at 284 eV when measured by the X-ray photoelectron spectroscopy. Ｂ２８４ and the intensity I at 532 eV when measured by the X-ray photoelectron spectroscopy. Ｂ５３２ Relative to I Ｂ５３２ / I Ｂ２８４ The release film according to claim 11, wherein the value satisfies the condition that the value is 0.5 or more and less than 1.

0.

14. The release film according to any one of claims 11 to 13, wherein the polyester resin is polybutylene terephthalate or a copolymer thereof.

15. A release film according to any one of claims 11 to 13, wherein the crystallinity of the first layer is 20% or more and 70% or less, and the crystallinity of the second layer is 40% or more and 80% or less.

16. A release film according to any one of claims 11 to 13, wherein the object has an epoxy adhesive layer, and when the release film is brought into contact with the object and then removed, at least a portion of the second layer detaches from the first layer while remaining in contact with the epoxy adhesive layer.

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