Release film, and method for producing molded article

Abstract

To provide a release film having excellent releasability and slipperiness, and a method for producing a molded article using the release film. A release film 10 according to the present invention comprises: a first release layer 1 comprising a first thermoplastic resin composition; and a cushion layer laminated on the first release layer 1. The first release layer 1 has an arithmetic average height Sa of more than 2.3 μm, the arithmetic average height Sa being an average of absolute values of differences in height of each point from an average surface of the surface of the first release layer 1.

Description

Release film and manufacturing method for molded products

[0001] The present invention relates to a method for producing a release film and a molded article.

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

[0003] When forming a flexible printed circuit board using such a release film, in other words, a laminate of a flexible circuit board and a coverlay film, the release film has been required to have two properties, namely, excellent releasability and slipperiness.

[0004] First, 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.

[0005] 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.

[0006] Furthermore, by improving the slipperiness, scratches and damage to the flexible circuit board can be prevented. Specifically, when the release film is conveyed by rollers to laminate it on the flexible printed circuit board, the release film exhibits excellent slipperiness, which suppresses the occurrence of wrinkles during conveyance and prevents slippage during conveyance, unwinding, and winding, allowing the laminate to be produced efficiently with a high yield.

[0007] However, conventional release films have not been sufficiently studied with respect to releasability and slipperiness, and therefore have insufficient releasability and slipperiness, which can lead to folding and creases in the flexible printed circuit board, breakage, and transport defects such as wrinkles in the release film during transport.

[0008] JP 2011-88351 A

[0009] The object of the present invention is to provide a release film that can be used to produce molded articles with excellent productivity by preventing or suppressing the formation of wrinkles in the release film during transportation, and by enabling the release film to be peeled off quickly after embedding the release film in a recess, and a method for producing molded articles using such a release film.

[0010] These objects are achieved by the present invention as set forth in the following (1) to (16): (1) A release film having a first release layer made of a first thermoplastic resin composition and a cushion layer laminated on the first release layer, wherein the first release layer has an arithmetic mean height Sa, which is the average of the absolute values ​​of the differences in height at each point with respect to the average plane of its surface, of more than 2.3 μm.

[0011] (2) The first release layer is a release film according to (1) above, in which the relationship Sp + Sv ≧ 27 is satisfied when the maximum peak height, which is the maximum value of the height from the average plane of the surface, is Sp [μm] and the maximum valley depth, which is the absolute value of the minimum value of the height from the average plane, is Sv [μm].

[0012] (3) A release film having a first release layer made of a first thermoplastic resin composition and a cushion layer laminated on the first release layer, wherein the first release layer satisfies the relationship Sp + Sv ≧ 27, where Sp [μm] is the maximum peak height, which is the maximum value of the height from the average plane of its surface, and Sv [μm] is the maximum valley depth, which is the absolute value of the minimum value of the height from the average plane.

[0013] (4) The release film according to any one of (1) to (3), wherein the first release layer has a protruding valley height Svk, which is the average depth of the protruding valleys, of 5 μm or more on the surface thereof.

[0014] (5) A release film having a first release layer made of a first thermoplastic resin composition and a cushion layer laminated on the first release layer, wherein the first release layer has a protruding valley height Svk, which is the average depth of the protruding valleys, of 5 μm or more on its surface.

[0015] (6) The release film according to any one of (1) to (5) above, wherein the area load ratio Smr2 separating the core portion from the protruding valley portion is 75% or more.

[0016] (7) The release film according to any one of (1) to (6) above, wherein the maximum peak height Sp is 10 μm or more.

[0017] (8) The release film according to any one of (1) to (7) above, wherein the maximum valley depth Sv is 10 μm or more.

[0018] (9) The release film according to any one of (1) to (8), wherein the release film has a second release layer made of a second thermoplastic resin composition laminated on the cushion layer on the side opposite to the first release layer.

[0019] (10) The release film according to any one of (1) to (9) above, wherein the first thermoplastic resin composition contains a polyester resin or a poly(4-methyl-1-pentene) resin.

[0020] (11) The release film according to any one of (1) to (10) above, wherein the cushion layer is made of a third thermoplastic resin composition containing a polyester-based resin and a polyolefin-based resin.

[0021] (12) The release film according to any one of (1) to (11) above, wherein the first release layer has an average thickness of 7 μm or more and 38 μm or less.

[0022] (13) The release film according to any one of (1) to (12) above, wherein the cushion layer has an average thickness of 40 μm or more and 110 μm or less.

[0023] (14) The release film according to any one of (1) to (13) above, wherein the release film has an average thickness of 50 μm or more and 180 μm or less.

[0024] (15) The release film according to any one of (1) to (14) above, wherein the release film is used by being superimposed on a surface of an object formed from a material containing a semi-cured thermosetting resin so that the surface on the side of the first release layer is in contact with the surface of the object.

[0025] (16) A method for manufacturing a molded product, comprising: a step of placing the release film on an object so that the first release layer of the release film according to any one of (1) to (15) faces the object; and a step of performing a heat press on the object on which the release film is placed, wherein in the step of placing the release film, the surface of the object on which the release film is placed is formed from a material containing a semi-cured thermosetting resin.

[0026] According to one embodiment of the present invention, the first release layer has an arithmetic mean height Sa, which is the average of the absolute values ​​of the height differences at each point relative to the average plane of its surface, of greater than 2.3 μm. Therefore, when a flexible printed circuit board is obtained using a flexible circuit board and a coverlay film, by using this release film, when the release film is peeled from the flexible printed circuit board, the release film exhibits excellent releasability with respect to the flexible printed circuit board, thereby suppressing the occurrence of creases and breakage in the flexible printed circuit board. Furthermore, the release film exhibits appropriate slip properties, thereby preventing or suppressing the occurrence of wrinkles in the release film during transportation. According to another embodiment of the present invention, the first release layer satisfies the relationship Sp + Sv ≧ 27, where Sp [μm] is the maximum peak height, which is the maximum height from the average plane of its surface, and Sv [μm] is the absolute value of the minimum height from the average plane. Therefore, when a flexible printed circuit board is obtained using a flexible circuit board and a coverlay film, by using this release film, the release film exhibits excellent releasability with respect to the flexible printed circuit board when peeling the release film from the flexible printed circuit board, thereby suppressing the occurrence of creases and breakage in the flexible printed circuit board. Furthermore, by exhibiting appropriate slip properties, the occurrence of wrinkles in the release film during transportation can be prevented or suppressed. According to another aspect of the present invention, the first release layer has, on its surface, a protruding valley height Svk, which is the average depth of the protruding valleys, of 5 μm or more. Therefore, when a flexible printed circuit board is obtained using a flexible circuit board and a coverlay film, by using this release film, the release film exhibits excellent releasability with respect to the flexible printed circuit board when peeling the release film from the flexible printed circuit board, thereby suppressing the occurrence of creases and breakage in the flexible printed circuit board. Furthermore, by exhibiting appropriate slip properties, the occurrence of wrinkles in the release film during transportation can be prevented or suppressed.

[0027] 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 the release film of the present invention. Fig. 5 is a partially enlarged longitudinal sectional view showing part A of the release film shown in Fig. 4.

[0028] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The method for producing a release film and a molded article of the present invention will be described in detail below with reference to preferred embodiments shown in the accompanying drawings.

[0029] In the following, a case where a flexible printed circuit board is produced using a roll-to-roll press machine by using the release film of the present invention will be described as an example. Prior to describing the method for producing the release film and molded article of the present invention, the roll-to-roll press machine used in the production of this flexible printed circuit board will be described.

[0030] <Roll-to-roll press machine> Fig. 1 is a side view showing the main parts of a roll-to-roll press machine used in manufacturing a flexible printed circuit board, Fig. 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 Fig. 1, and Fig. 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 Fig. 1. Note that, for convenience of explanation, the upper side in Figs. 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, the roll-to-roll press machine 100 (RtoR press machine) is equipped with a conveying means (not shown) that conveys the release film 10 (10A, 10B), the flexible printed circuit board 200 (hereinafter also referred to as "FPC"), and the glass cloths 300A, 300B, a heat pressing means 50 that uses the release film 10 to heat-press and bond the CL film 220 to the flexible circuit board 210 and the cover lay film 220 (hereinafter also referred to as "CL film") that the FPC 200 is equipped with, and a releasing means 60 that releases (peels off) the release film 10 from the FPC 200 in which the CL film 220 is bonded to the flexible circuit board 210.

[0032] The conveying means conveys the FPC 200, the release films 10A and 10B, and the glass cloths 300A and 300B, each wound around a different unwinding roller, along their longitudinal directions by the rotation of a tensioner (tension roller), and after processing by the heat pressing means 50 and the releasing means 60, the take-up roller winds them up.

[0033] Each roller is made of a metal material such as stainless steel, etc. The rotation axes (central axes) of these rollers are oriented in the same direction and are spaced apart from each other.

[0034] 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 transported by a transport means and are disposed above and below the overlapping glass cloth 300A, the release film 10A, the FPC 200, the release film 10B, and the glass cloth 300B. When the overlapping glass cloth 300A, the release film 10A, the FPC 200, the release film 10B, and the glass cloth 300B pass between the heat pressing plates 521, the heat pressing plates 521 heat and press the FPC 200 via the glass cloths 300A, 300B and the release films 10A, 10B. Therefore, as shown in FIG. 2( a), the curing reaction of the adhesive layer 222 provided on the CL film 220 progresses due to this heating, and in the FPC 200, the overlapping flexible circuit board 210 and the CL film 220 are bonded via the adhesive layer 222.

[0035] In other words, the coverlay 221 and the flexible circuit board 210 are bonded together via the adhesive layer 222 (see FIG. 2A). When the FPC 200 is heated and pressurized, that is, when the coverlay 221 and the flexible circuit board 210 are bonded together via the adhesive layer 222, the release film 10 is embedded in a recess 223 formed in the coverlay 221. This prevents the adhesive from seeping out of the recess 223 due to the adhesive layer 222 (see FIG. 2B).

[0036] Before being heated and compressed by the heating and compression plate 521, the FPC 200 is in a laminated state by overlapping the flexible circuit board 210 and the CL film 220, 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. Then, by 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, heating by the heating and compression plate 521 causes a curing reaction of the adhesive layer 222 to proceed, thereby bonding the flexible circuit board 210 and the CL film 220 via the adhesive layer 222.

[0037] As shown in FIG. 1 , the release means 60 is disposed downstream of the heat press means 50 in the conveying direction. This release means 60 is configured to separate the FPC 200 from the release films 10A and 10B. Here, in the heat pressing unit 52 provided in the heat press means 50, the release film 10 is embedded in a recess 223 formed in the coverlay 221, as shown in FIG. 2( b). As a result, the release film 10 is bonded to the CL film 220 (FPC 200). The release means 60 is configured to peel (release) the release film 10 from the CL film 220 (FPC 200) (see FIG. 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 has been peeled from the release film 10.

[0038] A flexible printed circuit board 200 (FPC 200) can be manufactured using the roll-to-roll press 100 described above. A method for manufacturing the FPC 200 using this roll-to-roll press will now be described. Note that the method for manufacturing the molded product of the present invention is applied to the method for manufacturing the FPC 200.

[0039] In this embodiment, as shown in Figures 1 to 3, the manufacturing method of the FPC 200 includes a first step of forming a laminate in which glass cloth 300A, release film 10A, FPC 200, release film 10B, and glass cloth 300B, each of which has a sheet-like shape, are stacked in this order; a second step of hot-pressing this laminate to bond a coverlay 221 (CL film 220) to the flexible circuit board 210 in the FPC 200 via an adhesive layer 222; and a third step of releasing the release film 10 (10A, 10B) from the FPC 200 to obtain the FPC 200 in which the CL film 220 is bonded to the flexible circuit board 210.

[0040] Each of these steps will be described below in order. (First Step) First, the glass cloth 300A, the release film 10A, the FPC 200, the release film 10B, and the glass cloth 300B, each of which is in a sheet form and wound around a winding roller, are laminated in this order during transport by a transport means (release film arrangement step, see FIGS. 1, 2(a), and 3).

[0041] The method for laminating each component (film) to the laminate is not particularly limited, and for example, the components may be laminated while being pressed by a roll or a press. The components may also be laminated in any order. For example, all components may be laminated at the same time, or the coverlay film 220 and the flexible circuit board 210 may be laminated in advance, and then the other components may be laminated at the same time.

[0042] Furthermore, the formation of the laminate in this first step constitutes the step of placing the release film 10 on the object (FPC 200) in the method for producing a molded product of the present invention.

[0043] (Second step) Next, the laminate in which the glass cloth 300A, the release film 10A, the FPC 200, the release film 10B, and the glass cloth 300B are stacked in this order is heated (heat-pressed) while being pressurized using the heat press means 50 (heat compression unit 52). As a result, the curing reaction of the adhesive layer 222 progresses while the adhesive layer 222 is in close contact with the flexible circuit board 210, and a bonded body is formed in the FPC 200 in which the coverlay 221 (CL film 220) is bonded to the flexible circuit board 210 via the adhesive layer 222 (heat press step; see FIGS. 1, 2(b), and 3).

[0044] At this time, the release film 10A adheres closely to the coverlay 221, and the release film 10A is embedded in the recess 223 formed in the coverlay 221, thereby suppressing the seepage of adhesive originating from the adhesive layer 222 into the recess 223.

[0045] In this second step (heat pressing step), the temperature to which the FPC 200 is heated is not particularly limited, but is preferably 100°C or higher and 250°C or lower, and more preferably 150°C or higher and 200°C or lower.

[0046] In addition, in the second step, when applying pressure to the FPC 200, the pressure set in the thermocompression bonding unit 52 is not particularly limited, but is preferably set to 1 MPa or more and 14 MPa or less, and more preferably 5 MPa or more and 14 MPa or less.

[0047] Furthermore, the conveying speed for conveying the laminate is preferably set to 40 mm / sec or more and 400 mm / sec or less, more preferably 100 mm / sec or more and 350 mm / sec or less. In other words, in the second step (main step), the laminate is hot-pressed using hot-press means 50, and in the peeling step (next step), the adhesion time until the release film 10 is peeled from the bonded body is preferably set to 1.0 sec or more and 10.0 sec or less, more preferably 4.0 sec or more and 7.0 sec or less.

[0048] The second step constitutes a step of performing a heat press on the object (FPC 200) on which the release film 10 is disposed in the method for manufacturing a molded product of the present invention. Furthermore, when the coverlay 221 (molded product) is made of a material containing a semi-cured thermosetting resin, the coverlay 221 constitutes the surface of the object (FPC 200) on which the release film 10 is disposed. The release film 10 is overlaid on the surface of the coverlay 221 so that the surface on the first release layer 1 side is in contact with the surface of the coverlay 221. Therefore, the release film 10 can maintain the shape of the coverlay 221 with the recesses 223 formed therein while curing the thermosetting resin. Therefore, the coverlay 221 (molded product) can be molded on the flexible circuit board 210 with excellent precision. Furthermore, because the adhesion time is set within the above range, the release film 10 can promote the curing reaction of the thermosetting resin constituting the coverlay 221 while maintaining the shape of the coverlay 221 with the recesses 223 formed therein.

[0049] The method for manufacturing a molded product of the present invention includes a step (first step) of placing a release film 10 on an object (FPC 200) so that the first release layer 1 of the release film 10 faces the object (FPC 200), and a step (second step) of performing a heat press on the object (FPC 200) on which the release film 10 is placed. In the step of placing the release film 10, the surface of the object (FPC 200) on which the release film 10 is placed is formed of a material containing a semi-cured thermosetting resin. This allows the release film 10 to maintain the shape of the coverlay 221 in which the recesses 223 are formed and harden the thermosetting resin, thereby enabling the coverlay 221 (molded product) to be molded with excellent precision on the flexible circuit board 210. Furthermore, because the adhesion time is set within the above range, the release film 10 allows the hardening reaction of the thermosetting resin constituting the coverlay 221 to proceed while maintaining the shape of the coverlay 221 in which the recesses 223 are formed.

[0050] Furthermore, in this embodiment, the heating means is a hot press, but this is not necessarily limited to this method. For example, heating may be performed by infrared rays or by a heating roll.

[0051] (Third Step) Next, in a releasing means 60, the release films 10 (10A, 10B) are released from the FPC 200. That is, the release films 10A and 10B are peeled off from the bonded body of the coverlay film 220 and the flexible circuit board 210. This results in an FPC 200 in which the CL film 220 is bonded to the flexible circuit board 210 (peeling step, see FIGS. 1, 2(c), and 3).

[0052] The release means 60 is not particularly limited, and may be, for example, a means configured to have a vacuum device installed on the outside and to perform peeling by vacuuming, or a means configured to perform peeling by blowing air between the bonded body and the release films 10A, 10B, or a means configured to insert a rod between the bonded body and the release films 10A, 10B and perform peeling.

[0053] Thereafter, the bonded assembly of the coverlay film 220 and the flexible circuit board 210, the glass cloth 300A, the release film 10A, the release film 10B, and the glass cloth 300B are wound up on the respective winding rollers.

[0054] By this winding, the flexible circuit board 210 and the CL film 220 are continuously obtained with the FPC 200 bonded via the adhesive layer 222 provided on the CL film 220 being wound around the winding roller.

[0055] As described above, by applying the method for manufacturing the flexible printed circuit board 200 by the roll-to-roll press machine 100 using the release film 10, the flexible printed circuit board 200 can be manufactured continuously.

[0056] After the third step, the process may include a step of heating the flexible printed circuit board 200 wound around a winding roller, or the wound flexible printed circuit board 200 cut into individual sheets, in an oven or the like, to further promote the curing reaction of the thermosetting resin that makes up the coverlay 221 and harden the coverlay 221.

[0057] The release film of the present invention is applied to the release film 10 used in the production of this flexible printed circuit board 200. Hereinafter, the release film 10 to which the release film of the present invention is applied will be described.

[0058] <Release Film 10> FIG. 4 is a longitudinal cross-sectional view showing an embodiment of the release film of the present invention, and FIG. 5 is a partially enlarged longitudinal cross-sectional view of part A of the release film shown in FIG.

[0059] As shown in Figure 4, in this embodiment, the release film 10 is composed of a laminate in which a first release layer 1, a cushion layer 3, and a second release layer 2 are stacked in this order, and is used by overlapping it with the surface on the first release layer 1 side in contact with the CL film 220 provided on the FPC 200.

[0060] Below, we will explain each layer that makes up this release film 10. <Cushion layer 3> First, we will explain the cushion layer 3. This cushion layer 3 is disposed as an intermediate layer between the first release layer 1 and the second release layer 2, as shown in Figures 4 and 5.

[0061] This cushion layer 3 is made of a third thermoplastic resin composition, and this third thermoplastic resin composition preferably contains a plurality of types of thermoplastic resins while imparting to the release film 10 the ability to fill the recesses 223. This ensures sufficient conformability.

[0062] Examples of combinations of multiple types of thermoplastic resins include a combination of a polyester-based resin and a polyolefin-based resin, a combination of two polyolefin-based resins, and a combination of a polyamide-based resin and a polyolefin-based resin. Of these, the above-mentioned effects can be more reliably achieved by selecting a combination of a polyester-based resin and a polyolefin-based resin.

[0063] The polyester-based resin is not particularly limited, but examples thereof include polyethylene terephthalate (PET), polycyclohexane terephthalate (PCT), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), polycyclohexanedimethylene terephthalate, and polypropylene terephthalate. One or more of these can be used in combination. When two or more of these are used in combination, the polyester-based resin may be a blend or copolymer of these. Among these, polybutylene terephthalate is particularly preferred as the polyester-based resin. This allows the cushion layer 3 to have excellent conformability to the recesses 223. Furthermore, when the first thermoplastic resin composition constituting the first release layer 1 contains polybutylene terephthalate, the cushion layer 3 can exhibit excellent adhesion to the first release layer 1.

[0064] The polyolefin resin is not particularly limited, and examples thereof include α-olefin polymers such as polyethylene (e.g., low-density polyethylene, high-density polyethylene), polypropylene, and α-olefin copolymers having ethylene, propylene, butene, pentene, hexene, octene, or the like as polymer components, such as ethylene-hexene copolymers, ethylene-octene copolymers, α-olefin-(meth)acrylic acid ester copolymers, ethylene-vinyl acetate copolymers, and ethylene-(meth)acrylic acid copolymers. One or more of these may be used in combination. Among these, at least one of ethylene-vinyl acetate copolymers and ethylene-(meth)acrylic acid copolymers is preferred. This allows the cushion layer 3 to have excellent conformability to the recesses 223.

[0065] When a polyester resin and a polyolefin resin are combined, the content of the polyester resin in the third thermoplastic resin composition is preferably 5% by weight or more, and more preferably 8% by weight or more and 40% by weight or less, which allows the release film 10 to have excellent conformability to the recesses 223.

[0066] Furthermore, the third thermoplastic resin composition constituting the cushion layer 3 may contain, in addition to the resin material (thermoplastic resin) described above, additives such as a nucleating agent, an antioxidant, a slip agent, an antiblocking agent, an antistatic agent, a colorant, and a stabilizer.

[0067] Furthermore, the storage modulus E' of the cushion layer 3 at 150°C is preferably 0.1 MPa or more, more preferably 0.5 MPa or more and 150 MPa or less, and even more preferably 1 MPa or more and 100 MPa or less. By setting the storage modulus E' of the cushion layer 3 at 150°C as described above, it is possible to appropriately suppress or prevent a portion of the cushion layer 3 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 in the second step. Therefore, contamination of the FPC 200 can be appropriately suppressed or prevented. Furthermore, it is possible to easily peel off the release film 10 in the third step.

[0068] The storage modulus E' of the cushion layer 3 at 150°C can be obtained, for example, in accordance with JIS K7244-4 by preparing a cushion layer 3 having a width of 4 mm and a length of 20 mm, and measuring the storage modulus E' at 150°C using a dynamic viscoelasticity measuring device (Hitachi High-Tech Science Corporation, "DMA7100") in a tensile mode at a frequency of 1 Hz and a heating rate of 5°C / min.

[0069] Furthermore, the average thickness Tk of the cushion layer 3 is preferably set to be 40 μm or more and 110 μm or less, and more preferably 50 μm or more and 90 μm or less, thereby ensuring sufficient conformability.

[0070] <First Release Layer 1> Next, a description will be given of the first release layer 1. This first release layer 1 is laminated on one surface of the cushion layer 3, as shown in Figs.

[0071] The first release layer 1 is flexible, and in the above-described method for manufacturing a flexible printed circuit board 200 using the release film 10, the release film 10 is superimposed on the CL film 220 of the FPC 200 so that the first release layer 1 comes into contact with the CL film 220. In the second step of this manufacturing method, when the superimposed flexible circuit board 210 and the CL film 220 are bonded via the adhesive layer 222, the first release layer 1 is pressed into the flexible circuit board 210 and the CL film 220, conforming to the shape of the recess 223 formed by the flexible circuit board 210 and the CL film 220, and functions as a protective (buffer) material that prevents the release film 10 from breaking. Furthermore, in the third step, the first release layer 1 functions as a contact layer for exhibiting excellent releasability of the release film 10 from the CL film 220 (FPC 200).

[0072] Therefore, in the second step, the release film 10 can reliably suppress or prevent the adhesive from seeping out of the adhesive layer 222 into the recesses 223 formed in the FPC 200. Furthermore, after the formation of the FPC 200 in the second step in which the flexible circuit board 210 and the CL film 220 are bonded together via the adhesive layer 222 provided on the CL film 220, when the release film 10 is peeled off from the FPC 200 in the third step, the release film 10 can reliably suppress or prevent the FPC 200 from elongating and breaking. Furthermore, when the third thermoplastic resin composition constituting the cushion layer 3 contains a polyester-based resin, the first release layer 1 can exhibit excellent adhesion to the cushion layer 3.

[0073] Furthermore, in the manufacturing method of flexible printed circuit board 200, first release layer 1 is in contact with CL film 220 provided on FPC 200. Therefore, first release layer 1 also has the function of transmitting heat from thermocompression plate 521 to CL film 220 when FPC 200 is hot-pressed in the second step of this manufacturing method.

[0074] The first release layer 1 has an uneven surface as shown in Fig. 5. The release film 10 of this embodiment satisfies at least one of the following conditions [1] to [3].

[0075] [1] In the release film 10 of this embodiment, the first release layer 1 has an arithmetic mean height Sa, which is the average of the absolute values ​​of the height differences at each point relative to the average plane of its surface, of more than 2.3 μm.

[0076] [2] The first release layer 1 satisfies the relationship Sp + Sv ≧ 27, where Sp [μm] is the maximum peak height, which is the maximum value of the height from the average plane of its surface, and Sv [μm] is the maximum valley depth, which is the absolute value of the minimum value of the height from the average plane.

[0077] [3] It is preferable that the protruding valley height Svk, which is the average depth of the protruding valleys on the surface of the first release layer 1, is 5 μm or more.

[0078] By satisfying at least one of the conditions [1] to [3], it is possible to more reliably exhibit the excellent releasability of the release film 10 from the CL film 220 (FPC 200). In addition, it is possible to more reliably improve the slipperiness, and to perform good and smooth transport of the release film 10.

[0079] It is sufficient to satisfy at least one of the conditions [1] to [3], but it is preferable to satisfy two or more of these conditions, and it is even more preferable to satisfy three of these conditions. This makes it possible to more reliably exhibit the releasability of the release film 10 from the CL film 220 (FPC 200), and to more reliably enhance the slipperiness, thereby enabling better and smoother transport of the release film 10.

[0080] <Regarding condition [1]> By having the first release layer 1 that satisfies the condition [1], it is possible to more reliably exhibit excellent releasability of the release film 10 from the CL film 220 (FPC 200). In addition, it is possible to more reliably improve the slipperiness, and to carry out good and smooth transport of the release film 10.

[0081] When the conditions [2] and [3] are not satisfied, if the arithmetic mean height Sa is 2.3 μm or less, the releasability and slipperiness become insufficient, and during the production of the flexible printed circuit board 200, problems such as creases and breakage of the flexible printed circuit board 200 or scratches on the flexible circuit board 210 may occur. Furthermore, the release film 10 cannot be transported well and smoothly.

[0082] The arithmetic mean height Sa is a value representing the average of the absolute values ​​of the heights of the protrusions, i.e., the differences in height at each point, relative to the average plane of the surface of the first release layer 1. The arithmetic mean height Sa can be determined in accordance with ISO 25178. Specifically, the arithmetic mean height Sa can be determined as follows.

[0083] Using a scanning white light interference microscope (Keyence Corporation "Laser Microscope VK-X3000"), four connected images (measurement range: approximately 2000 μm × 1500 μm) are acquired with a 20x objective lens. The obtained images are then subjected to a process for setting an average plane (reference plane). Next, Gaussian filter processing is performed, with the cutoff wavelengths set to 2.5 μm for the S filter and 0.8 mm for the L filter. From the results of this processing, the average of the absolute values ​​of the height differences at each point is calculated.

[0084] Although the above-mentioned effect can be obtained when the arithmetic mean height Sa exceeds 2.3 μm, it is preferable that the arithmetic mean height Sa is 2.5 μm or more and 10.0 μm or less, and more preferably 2.9 μm or more and 9.0 μm or less, which more reliably enables the release film 10 to exhibit excellent releasability from the CL film 220 (FPC 200), and also more reliably enhances the slipperiness, allowing the release film 10 to be transported well and smoothly.

[0085] By setting the value of the arithmetic mean height Sa to be equal to or less than the upper limit, it is possible to ensure embeddability and followability.

[0086] The method for making the arithmetic mean height Sa of the surface of the first release layer 1 greater than 2.3 μm is not particularly limited, and examples thereof include a method of blending a filler such as inorganic particles or organic particles described below into the first release layer 1, a surface treatment method such as plasma treatment, a roll transfer method, etc. The arithmetic mean height Sa can be made greater than 2.3 μm by adjusting the size of the filler or the conditions of the surface treatment.

[0087] <Regarding condition [2]> By having a first release layer 1 that satisfies condition [2], the excellent releasability of the release film 10 from the CL film 220 (FPC 200) can be more reliably exhibited. In addition, the slipperiness can be more reliably improved, allowing the release film 10 to be transported well and smoothly. Sp [μm] and Sv [μm] can be determined in accordance with ISO 25178. Specifically, Sp [μm] and Sv [μm] can be determined as follows.

[0088] Using a scanning white light interference microscope (Keyence Corporation "Laser Microscope VK-X3000"), four connected images (measurement range: approximately 2000 μm × 1500 μm) are acquired with a 20x objective lens. The obtained images are then subjected to a process for setting the mean plane (reference plane). Gaussian filter processing is then performed, with the cutoff wavelengths set to 2.5 μm for the S filter and 0.8 mm for the L filter. From the results of this processing, the maximum peak height, which is the maximum value of the height from the mean plane, is calculated to obtain Sp [μm], and the maximum valley depth, which is the absolute value of the minimum value of the height from the mean plane, is calculated to obtain S [μm].

[0089] When the conditions [1] and [3] are not satisfied, if Sp + Sv < 27, the releasability and slipperiness become insufficient, and during the production of the flexible printed circuit board 200, problems such as creases and breakage of the flexible printed circuit board 200 or scratches on the flexible circuit board 210 may occur. Furthermore, the release film 10 cannot be transported well and smoothly.

[0090] Sp+Sv is preferably 30 μm or more and 90 μm or less, and more preferably 35 μm or more and 80 μm or less, which more reliably enables the release film 10 to exhibit excellent releasability from the CL film 220 (FPC 200), and also more reliably enhances the slipperiness, allowing the release film 10 to be transported well and smoothly.

[0091] The method for making the surface of the first release layer 1 satisfy Sp+Sv≧27 is not particularly limited, and examples thereof include a method of blending a filler such as inorganic particles or organic particles described below into the first release layer 1, a surface treatment method such as plasma treatment, a roll transfer method, etc. Sp+Sv≧27 can be achieved by adjusting the size of the filler or the conditions of the surface treatment.

[0092] <Regarding condition [3]> By having the first release layer 1 that satisfies the condition [3], it is possible to more reliably exhibit excellent releasability of the release film 10 from the CL film 220 (FPC 200). In addition, it is possible to more reliably improve the slipperiness, and to perform good and smooth transport of the release film 10.

[0093] The protruding valley height Svk [μm] can be determined in accordance with ISO 25178. Specifically, the protruding valley height Svk [μm] can be determined as follows.

[0094] Using a scanning white light interference microscope (Keyence Corporation's "Laser Microscope VK-X3000") and setting the objective lens to 20x magnification, four joined images (measurement range: approximately 2000 μm × 1500 μm) are acquired. The obtained images are then subjected to a process for setting an average plane (reference plane). Next, Gaussian filter processing is performed, with the cutoff wavelengths set to 2.5 μm for the S filter and 0.8 mm for the L filter. From the results of this processing, the average depth of the protruding valleys on the surface is calculated to determine the protruding valley height Svk [μm].

[0095] When the conditions [1] and [2] are not satisfied, if the protruding valley height Svk is less than 5 μm, the releasability and slipperiness will be insufficient, and during the production of the flexible printed circuit board 200, problems such as creases and breakage may occur in the flexible printed circuit board 200 or scratches may be caused on the flexible circuit board 210. Furthermore, the release film 10 cannot be transported well and smoothly.

[0096] The protruding valley height Svk is preferably 6 μm or more and 30 μm or less, and more preferably 6 μm or more and 25 μm or less, so that the above-mentioned effects can be more reliably exhibited.

[0097] <Regarding conditions other than [1] to [3]> The maximum peak height Sp of the first release layer 1 is preferably 10 μm or more. This more reliably enables the release film 10 to exhibit excellent releasability from the CL film 220 (FPC 200). In addition, the slipperiness is more reliably improved, allowing the release film 10 to be transported well and smoothly.

[0098] The maximum peak height Sp of the first release layer 1 is preferably 10 μm or more, more preferably 10 μm or more and 60 μm or less, and even more preferably 15 μm or more and 50 μm or less, so that the above-mentioned effects can be more reliably exhibited.

[0099] The maximum valley depth Sv of the first release layer 1 is preferably 10 μm or more. This more reliably enables the release film 10 to exhibit excellent releasability from the CL film 220 (FPC 200). In addition, the slipperiness is more reliably improved, allowing the release film 10 to be transported well and smoothly.

[0100] The maximum valley depth Sv of the first release layer 1 is preferably 10 μm or more, more preferably 10 μm or more and 60 μm or less, and even more preferably 15 μm or more and 50 μm or less. This makes it possible to more reliably exhibit the above-mentioned effects.

[0101] It is preferable that the area load ratio Smr2 separating the core portion from the protruding valley portion is 75% or more. This more reliably enables the release film 10 to exhibit excellent releasability from the CL film 220 (FPC 200). In addition, the slipperiness is more reliably improved, allowing the release film 10 to be transported well and smoothly. The area load ratio Smr2 can be determined in accordance with ISO 25178.

[0102] The areal load ratio Smr2 is preferably 75% or more, and more preferably 80% to 99%. This makes it possible to more reliably achieve the above-mentioned effects.

[0103] This first release layer 1 is made of a first thermoplastic resin composition. Furthermore, this first thermoplastic resin composition preferably contains, for example, mainly a polyester-based resin or a poly-4-methyl-1-pentene resin. This makes it relatively easy to impart the above-mentioned functions to the first release layer 1.

[0104] The polyester-based resin is not particularly limited, but may be, for example, the same as those listed for the third thermoplastic resin composition described above. Among them, polybutylene terephthalate (PBT) is particularly preferred. This allows the effects obtained by using a polyester-based resin to be more pronounced. Furthermore, when the third thermoplastic resin composition constituting the cushion layer 3 contains polybutylene terephthalate, the first release layer 1 can exhibit excellent adhesion to the cushion layer 3.

[0105] Furthermore, when the first thermoplastic resin composition is mainly composed of a polyester-based resin, it may contain a thermoplastic resin other than a polyester-based resin. Examples of such a thermoplastic resin include polyolefin-based resins such as polyethylene, polypropylene, and poly-4-methyl-1-pentene, and polystyrene-based resins such as syndiotactic polystyrene. One or a combination of two or more of these may be used.

[0106] The first thermoplastic resin composition may further contain at least one of inorganic particles and organic particles in addition to the thermoplastic resin described above.

[0107] 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.

[0108] 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.

[0109] 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. This makes it relatively easy to set the surface roughness of the surface of the first release layer 1 opposite to the cushion layer 3 within the above-mentioned range when at least one of the inorganic particles and the organic particles is contained in the first thermoplastic resin composition.

[0110] The average thickness T1 of the first release layer 1 is preferably set to be 7 μm or more and 38 μm or less, and more preferably 10 μm or more and 30 μm or less, so that the average thickness of the first release layer 1 is set within an appropriate range, and the first release layer 1 can be more reliably imparted with the above-described function as the first release layer 1.

[0111] As described above, when the surface of the first release layer 1 opposite the cushion layer 3 has an uneven shape, the average thickness T1 of the first release layer 1 is the average value of the measured values ​​obtained by measuring the thickness at positions including the convex portions in the case of convex portions, and at positions including the concave portions in the case of concave portions.

[0112] In addition, the first thermoplastic resin composition constituting the first release layer 1 may contain, in addition to the resin material, inorganic particles, and organic particles described above, additives similar to those listed in the third thermoplastic resin composition.

[0113] <Second Release Layer 2> Next, the second release layer 2 will be described.

[0114] As shown in Figures 4 and 5, the release film 10 has a second release layer 2 made of a second thermoplastic resin composition laminated on the other side of the cushion layer 3, i.e., the side of the cushion layer 3 opposite the first release layer 1.

[0115] The second release layer 2 has flexibility, and in the above-described method for manufacturing a flexible printed circuit board 200 using the release film 10, the release film 10 is superimposed on the CL film 220 of the FPC 200 so that the first release layer 1 comes into contact with the CL film 220, and in the second step of this manufacturing method, when the superimposed flexible circuit board 210 and the CL film 220 are bonded via the adhesive layer 222, the second release layer 2 functions as a layer that transmits the force from the heat-pressure bonding plate 521 to the cushion layer 3. Furthermore, in the third step, the second release layer 2 functions as a contact layer for achieving excellent releasability between the glass cloth 300 and the release film 10.

[0116] In addition, in the manufacturing method of the flexible printed circuit board 200, the second release layer 2 is in contact with the thermocompression plate 521 via the glass cloth 300. Therefore, in the second step of this manufacturing method, when the FPC 200 is hot-pressed, the second release layer 2 also has the function of transmitting heat from the thermocompression plate 521 to the cushion layer 3.

[0117] The second release layer 2 is made of a second thermoplastic resin composition. Like the first thermoplastic resin composition, this second thermoplastic resin composition preferably contains a polyester-based resin as a main component. This ensures that the second release layer 2 has the aforementioned functions.

[0118] The polyester resin is not particularly limited, but may be, for example, the same as those listed for the third thermoplastic resin composition described above, and among them, polybutylene terephthalate (PBT) is particularly preferred, which allows the effects obtained by using the polyester resin to be more significantly exhibited.

[0119] In addition, when the second thermoplastic resin composition is mainly composed of a polyester-based resin, it may contain a thermoplastic resin other than a polyester-based resin, and as this thermoplastic resin, the same thermoplastic resins as those listed for the first thermoplastic resin composition can be used.

[0120] The second thermoplastic resin composition may further contain at least one of inorganic particles and organic particles in addition to the thermoplastic resin described above.

[0121] The inorganic particles and organic particles are not particularly limited, but the same particles as those listed for the first thermoplastic resin composition can be used.

[0122] The second release layer 2 having such a configuration preferably has a storage modulus E' at 150°C of 50 MPa or more, more preferably 50 MPa or more and 1000 MPa or less, thereby ensuring that the second release layer 2 has the above-mentioned functions.

[0123] The average thickness T2 of the second release layer 2 is preferably set to be 7 μm or more and 38 μm or less, and more preferably 10 μm or more and 30 μm or less, so that the second release layer 2 can be provided with the above-mentioned functions more reliably.

[0124] Furthermore, the second thermoplastic resin composition constituting the second release layer 2 may contain, in addition to the resin materials, inorganic particles, and organic particles described above, additives similar to those listed in the third thermoplastic resin composition.

[0125] In addition, the first thermoplastic resin composition and the second thermoplastic resin composition in the first release layer 1 and the second release layer 2 may be the same or different, but from the viewpoint of substitutability, they are preferably the same or of the same quality. Furthermore, the average thicknesses T1 and T2 of the first release layer 1 and the second release layer 2 may be the same or different.

[0126] In the release film 10 having a laminated structure of the first release layer 1, cushion layer 3, and second release layer 2 as described above, the average thickness Tt is preferably 50 μm or more and 180 μm or less, and more preferably 80 μm or more and 150 μm or less.

[0127] In this embodiment, the release film 10 is composed of a laminate in which a first release layer 1, a cushion layer 3, and a second release layer 2 are laminated in this order, but is not limited to this configuration.For example, the release film 10 may be composed of a laminate having an intermediate layer such as an adhesive layer arranged at least either between the first release layer 1 and the cushion layer 3 or between the second release layer 2 and the cushion layer 3.

[0128] Furthermore, the release film 10 may be one in which the second release layer 2 that comes into contact with the glass cloth 300 is omitted, as long as excellent releasability can be maintained between the glass cloth 300 and the release film 10 in the third step.

[0129] Although the method for producing the release film and molded article of the present invention has been described above, the present invention is not limited thereto.

[0130] 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 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.

[0131] 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 application is not limited thereto, 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.

[0132] The present invention will be described in detail below based on examples, but the present invention is not limited to these examples.

[0133] 1. Preparation of Raw Materials The following raw materials were prepared for producing a release film.

[0134] Thermoplastic resin materials: Ethylene-methyl methacrylate copolymer (EMMA, manufactured by Sumitomo Chemical Co., Ltd., "WD203-1"), Polypropylene (PP, manufactured by Prime Polypro Co., Ltd., "E111G"), Polybutylene terephthalate (PBT, manufactured by Chang Chun Petrochemical Co., Ltd., "1100-630S"), Copolymerized polybutylene terephthalate (PBT, manufactured by Mitsubishi Engineering Plastics Co., Ltd., "5505S")

[0135] 2. Production of Release Film Example 1 First, a first thermoplastic resin composition was prepared, which consisted of 70 wt% polybutylene terephthalate (PBT, 1100-630S) and 30 wt% copolymer polybutylene terephthalate (PBT, 5505S). A second thermoplastic resin composition was prepared, which consisted of 100 wt% polybutylene terephthalate (PBT, 1100-630S). A third thermoplastic resin composition was prepared, which consisted of 55 wt% ethylene-methyl methacrylate copolymer (EMMA, WD203-1), 20 wt% polypropylene (PP, E111G), and 25 wt% polybutylene terephthalate (PBT, 1100-630S).

[0136] Next, the first thermoplastic resin composition, the third thermoplastic resin composition, and the second thermoplastic resin composition were supplied to three extruders and co-extruded from a multi-manifold die to obtain a release film 10 having a first release layer 1, a cushion layer 3, and a second release layer 2 laminated in that order.

[0137] In the obtained release film 10, the average thickness T1 of the first release layer 1 was 20 μm, the average thickness Tk of the cushion layer 3 was 80 μm, and the average thickness T2 of the second release layer 2 was 20 μm.

[0138] At this time, the first release layer 1 was subjected to a roughening treatment for transferring the surface shape using at least one of the first roll and the touch roll.

[0139] The arithmetic mean height Sa, which is the average of the absolute values ​​of the differences in height at each point relative to the average plane of the surface of the first release layer 1, was 3.1 μm.

[0140] Furthermore, when the maximum peak height, which is the maximum value of the height from the average plane of the surface of the first release layer 1, is Sp [μm] and the maximum valley depth, which is the absolute value of the minimum value of the height from the average plane, is Sv [μm], Sp + Sv was 28 μm.

[0141] Furthermore, on the surface of the first release layer 1, the protruding valley height Svk, which is the average depth of the protruding valleys, was 5 μm.

[0142] Furthermore, the surface area bearing ratio Smr2 separating the core portion from the protruding valley portion on the surface of the first release layer 1 was 92%.

[0143] The arithmetic mean height Sa, the maximum peak height Sp+maximum valley depth Sv, the protruding valley height Svk, and the area bearing ratio Smr2 were determined as follows.

[0144] Using a scanning white light interference microscope (Keyence Corporation's "Laser Microscope VK-X3000") and a 20x objective lens, four combined images (measurement range: approximately 2000 μm × 1500 μm) were acquired. The resulting images were then subjected to a process for setting an average plane (reference plane). Gaussian filter processing was then performed, with the cutoff wavelengths set to 2.5 μm for the S filter and 0.8 mm for the L filter. The arithmetic mean height Sa, maximum peak height Sp + maximum valley depth Sv, protruding valley height Svk, and area material ratio Smr2 were then calculated from the processing results. In this case, values ​​were calculated for each of the four regions, from the first quadrant to the fourth quadrant, of the combined images, and the average value was used as the value.

[0145] <Examples 2 to 9, Comparative Examples 1 and 2> The release films 10 of Examples 2 to 9 and Comparative Examples 1 and 2 were obtained in the same manner as in Example 1, except that the conditions for the roughening treatment on the surface of the first release layer 1 were adjusted and the arithmetic mean height Sa, the maximum peak height Sp + maximum valley depth Sv, the protruding valley height Svk, and the area load ratio Smr2 were changed as shown in Table 1.

[0146] 3. Evaluation The release films 10 of the examples and comparative examples were evaluated as follows.

[0147] The release film 10 of each example and comparative example was made to have a width of 270 mm, and a coverlay film 220 (manufactured by Arisawa Manufacturing Co., Ltd., "CMA0525") was attached to a flexible circuit board 210 with the adhesive layer 222 of the coverlay 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.

[0148] [Evaluation Criteria] A: The release film can be peeled off. B: When the release film is peeled off, it is difficult to peel off due to fusion between the cushion layers or stretching or breaking of the release film.

[0149] 3-2. Slipperiness of Release Film (Appearance Wrinkles) The effect of suppressing wrinkles due to good slipperiness was evaluated as follows.

[0150] A test specimen was prepared by temporarily attaching a coverlay having an opening to the surface of an insulating substrate (FPC) on which electrical wiring with an L / S of 100 / 100 μm was formed, so that the adhesive-coated surface was in contact. Next, a release film 10 was pressed and attached to the test specimen using a roll-to-roll press under conditions of 175°C, 11 MPa, and 120 seconds. Immediately after pressing, the test specimen and the release film 10 were peeled off while being transported at 200 mm / s. The surface of the test specimen was measured in accordance with "7.5.7.2 Wrinkles" of the JPCA standard.

[0151] [Evaluation Criteria] A: Wrinkle occurrence rate less than 1.0% B: Wrinkle occurrence rate 1.0% or more but less than 2.0% C: Wrinkle occurrence rate 2.0% or more

[0152] 3-3. Summary Table 1 shows the evaluation results obtained in the above 3-1. Releasability of the release film and the above 3-2. Slipperiness of the release film.

[0153]

[0154] As shown in Table 1, in each example, the first release layer 1 was set to satisfy at least one of the following conditions: the arithmetic mean height Sa was greater than 2.3 μm; the maximum peak height Sp + maximum valley depth Sv was Sp + Sv≧27; and the protruding valley height Svk, which is the average depth of the protruding valley, was 5 μm or more, resulting in excellent release properties and slip resistance.

[0155] In contrast, in each comparative example, the first release layer 1 did not satisfy any of the conditions: the arithmetic mean height Sa was greater than 2.3 μm, the maximum peak height Sp + maximum valley depth Sv was Sp + Sv≧27, and the average depth of the protruding valleys, that is, the protruding valley height Svk, was 5 μm or more.As a result, the results showed that the release properties and slip properties were not excellent.

[0156] According to the present invention, it is possible to provide a release film having excellent releasability and slipperiness, and a method for producing a molded article using such a release film. Therefore, the present invention has industrial applicability.

[0157] 1 First release layer 2 Second release layer 3 Cushion layer 10 Release film 10A Release film 10B Release film 50 Heat press means 52 Heat compression bonding unit 60 Release means 100 Roll-to-roll 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 first release layer T2 Average thickness of second release layer Tk Average thickness of cushion layer Tt Average thickness of release film

Claims

1. A release film having a first release layer made of a first thermoplastic resin composition and a cushion layer laminated on the first release layer, wherein the first release layer has an arithmetic mean height Sa, which is the average of the absolute values ​​of the height differences at each point on its surface relative to the average plane, of more than 2.3 μm.

2. The release film according to claim 1, wherein the first release layer satisfies the relationship Sp + Sv ≧ 27, where Sp [μm] is the maximum peak height, which is the maximum value of the height from the average plane of its surface, and Sv [μm] is the maximum valley depth, which is the absolute value of the minimum value of the height from the average plane.

3. A release film having a first release layer made of a first thermoplastic resin composition and a cushion layer laminated on the first release layer, wherein the first release layer satisfies the relationship Sp + Sv ≥ 27, where Sp [μm] is the maximum peak height, which is the maximum height from the average plane of its surface, and Sv [μm] is the maximum valley depth, which is the absolute value of the minimum height from the average plane.

4. A release film according to any one of claims 1 to 3, wherein the first release layer has a protruding valley height Svk, which is the average depth of the protruding valleys on the surface thereof, of 5 µm or more.

5. A release film having a first release layer made of a first thermoplastic resin composition and a cushion layer laminated on the first release layer, wherein the first release layer has a protruding valley height Svk, which is the average depth of the protruding valleys on its surface, of 5 μm or more.

6. A release film according to any one of claims 1 to 5, wherein the area load ratio Smr2 separating the core portion from the protruding valley portion is 75% or more.

7. A release film according to any one of claims 1 to 6, wherein the maximum peak height Sp is 10 µm or more.

8. A release film according to any one of claims 1 to 7, wherein the maximum valley depth Sv is 10 µm or more.

9. A release film according to any one of claims 1 to 8, wherein the release film has a second release layer made of a second thermoplastic resin composition laminated on the cushion layer on the side opposite the first release layer.

10. A release film according to any one of claims 1 to 9, wherein the first thermoplastic resin composition contains a polyester resin or a poly 4-methyl 1-pentene resin.

11. A release film according to any one of claims 1 to 10, wherein the cushion layer is made of a third thermoplastic resin composition containing a polyester resin and a polyolefin resin.

12. A release film according to any one of claims 1 to 11, wherein the first release layer has an average thickness of 7 μm or more and 38 μm or less.

13. A release film according to any one of claims 1 to 12, wherein the cushion layer has an average thickness of 40 μm or more and 110 μm or less.

14. The release film according to any one of claims 1 to 13, wherein the average thickness of the release film is 50 μm or more and 180 μm or less.

15. A release film according to any one of claims 1 to 14, wherein the release film is used by superimposing the surface of the first release layer on the surface of an object formed from a material containing a semi-cured thermosetting resin.

16. A method for manufacturing a molded product, comprising the steps of: placing a release film on an object so that the first release layer of the release film according to any one of claims 1 to 15 faces the object; and performing a heat press on the object on which the release film is placed, wherein in the step of placing the release film, the surface of the object on which the release film is placed is formed from a material containing a semi-cured thermosetting resin.

Images