Manufacturing method of release film and molded product

Abstract

The present invention provides a release film having excellent releasability and slipperiness, and a method for producing a molded product using such a release film. [Solution] The release film 10 of the present invention is a release film having a first release layer 1 made of a first thermoplastic resin composition and a cushion layer 3 laminated on the first release layer 1, and the protruding valley height Svk, which is the average depth of the protruding valleys, is 5 μm or more on the surface of the first release layer 1. In addition, it is preferable that the load area ratio Smr2 separating the core portion and the protruding valleys is 80% or more.

Description

[Technical field]

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

[0002] For example, as shown in Patent Document 1, a release film is generally used when a coverlay film is adhered 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 breakage in the flexible printed circuit board.

[0006] In addition, by improving the slipperiness, scratches and damage to the flexible circuit board are prevented. Specifically, when the release film is transported with rollers in order to laminate the release film on the flexible printed circuit board, the release film exhibits excellent slipperiness, which suppresses the occurrence of wrinkles during transport and prevents the occurrence of misalignment during transport, unwinding, and winding, thereby enabling the laminate to be produced effectively with a high yield.

[0007] However, in conventional release films, the releasability and slipperiness have not been sufficiently studied, and the releasability and slipperiness are insufficient, which may cause folding wrinkles and breakage in the flexible printed circuit board, or wrinkles in the release film during transportation, resulting in transportation defects. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] JP 2011-88351 A Summary of the Invention [Problem to be solved by the invention]

[0009] The object of the present invention is to provide a release film that can produce molded articles with excellent productivity by preventing or suppressing the generation of wrinkles in the release film during transportation while allowing 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. [Means for solving the problem]

[0010] Such objectives are as follows: 9 This is achieved by the present invention described in (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, The first release layer has a protruding valley height Svk, which is an average depth of the protruding valleys, of 5 μm or more on its surface. 30μm or less Yes The area-bearing ratio Smr2 separating the core portion from the protruding valley portion is 75% or more and 99% or less. A release film characterized by:

[0012] ( 2 The release film is the above-mentioned (1) having 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. ) The release film described herein.

[0013] ( 3 The first thermoplastic resin composition is the above-mentioned (1) containing a polyester resin or a poly(4-methyl-1-pentene) resin. Or (2) The release film according to claim 1.

[0014] ( 4 The cushion layer is made of a third thermoplastic resin composition containing a polyester resin and a polyolefin resin. 3 ) The release film according to any one of the preceding claims.

[0015] ( 5 The first release layer has an average thickness of 7 μm or more and 38 μm or less according to any one of (1) to ( 4 ) The release film according to any one of the preceding claims.

[0016] ( 6 The cushion layer has an average thickness of 40 μm or more and 110 μm or less. 5 ) The release film according to any one of the preceding claims.

[0017] ( 7 The release film has an average thickness of 50 μm or more and 180 μm or less. 6 ) The release film according to any one of the preceding claims.

[0018] ( 8 The release film is applied to a surface of an object formed of a material containing a semi-cured thermosetting resin. The above-mentioned (1) to ( 7 ) The release film according to any one of the preceding claims.

[0019] ( 9 ) (1) or ( 8 ) so that the first release layer of the release film according to any one of the preceding claims faces the object. A method for manufacturing a molded product, comprising: a step of placing the release film on 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 thermosetting resin in a semi-cured state. Effect of the Invention

[0020] According to the present invention, the first release layer has a protruding valley height Svk, which is the average depth of the protruding valley, of 5 μm or more on its surface. Therefore, by using this release film when obtaining a flexible printed circuit board using a flexible circuit board and a coverlay film, when the release film is peeled off from the flexible printed circuit board, the release film exhibits excellent releasability with respect to the flexible printed circuit board, and the occurrence of creases and breakage in the flexible printed circuit board can be suppressed. In addition, the release film exhibits appropriate slip properties, and the occurrence of creases in the release film during transportation can be prevented or suppressed. [Brief description of the drawings]

[0021] [Figure 1] FIG. 1 is a side view showing a main part of a roll-to-roll press machine used in manufacturing flexible printed circuit boards. [Diagram 2] 2A to 2C are vertical cross-sectional views showing steps in a method for producing a flexible printed circuit board using the roll-to-roll press machine shown in FIG. [Diagram 3] 2 is a vertical cross-sectional view showing a heat pressing step in a method for producing a flexible printed circuit board using the roll-to-roll press machine shown in FIG. 1. [Figure 4] 1 is a longitudinal sectional view showing an embodiment of a release film of the present invention. [Diagram 5] 5 is a partially enlarged longitudinal sectional view of a portion A of the release film shown in FIG. 4. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The method for producing a release film and a molded product of the present invention will be described in detail below with reference to preferred embodiments shown in the accompanying drawings.

[0023] In the following, a method for producing a flexible printed circuit board using the release film of the present invention will be described as an example using a roll-to-roll press machine. Prior to describing the method for producing the release film and molded product of the present invention, the roll-to-roll press machine used in the production of the flexible printed circuit board will be described first.

[0024] <Roll-to-roll press machine> Fig. 1 is a side view showing a main part 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 manufacturing method for 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 press step in a manufacturing method for a flexible printed circuit board using the roll-to-roll press machine shown in Fig. 1. Note that, for convenience of explanation, in the following, the upper side in Figs. 1 to 3 will be referred to as "upper" or "upper side", the lower side will be referred to as "lower" or "lower", the left side will be referred to as "left", and the right side will be referred to as "right".

[0025] As shown in Figures 1 to 3, a roll-to-roll press machine 100 (RtoR press machine) is equipped with a conveying means (not shown) for conveying a release film 10 (10A, 10B), a flexible printed circuit board 200 (hereinafter also referred to as "FPC"), and glass cloths 300A, 300B, a heat press means 50 for bonding a flexible circuit board 210 and a coverlay film 220 (hereinafter also referred to as "CL film") provided in the FPC 200 by heat pressing the CL film 220 to the flexible circuit board 210 using the release film 10, and a releasing means 60 for releasing (peeling) the release film 10 from the FPC 200 in which the CL film 220 is bonded to the flexible circuit board 210.

[0026] The conveying means conveys the FPC 200, the release films 10A, 10B, and the glass cloths 300A, 300B, each of which is wound around a different unwinding roller, along their respective longitudinal directions by the rotation of a tensioner (tension roller), and after processing by the heating press means 50 and the releasing means 60, the take-up roller winds them up.

[0027] Each roller is made of a metal material such as stainless steel, etc. Furthermore, the rotation axes (central axes) of these rollers face in the same direction and are disposed apart from each other.

[0028] As shown in FIG. 1, the heat pressing means 50 has a heat pressing section 52 . The thermocompression unit 52 has a pair of thermocompression plates 521. The thermocompression plates 521 are transported by a transport means, and are disposed above and below the glass cloth 300A, the release film 10A, the FPC 200, the release film 10B, and the glass cloth 300B, which are in a superposed state. When the glass cloth 300A, the release film 10A, the FPC 200, the release film 10B, and the glass cloth 300B, which are in a superposed state, pass between the thermocompression plates 521, the thermocompression plates 521 heat and press the FPC 200 through the glass cloths 300A and 300B and the release films 10A and 10B. Therefore, as shown in FIG. 2(a), the curing reaction of the adhesive layer 222 of the CL film 220 progresses due to this heating, so that the overlapping flexible circuit board 210 and the CL film 220 in the FPC 200 are bonded via the adhesive layer 222.

[0029] In other words, the coverlay 221 and the flexible circuit board 210 are bonded together via the adhesive layer 222 (see FIG. 2(a)). 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. Therefore, seepage of the adhesive from the adhesive layer 222 into the recess 223 is suppressed (see FIG. 2(b)).

[0030] 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 overlapping 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. Then, by compression by 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 by the heating and compression plate 521, a curing reaction of the adhesive layer 222 progresses, so that the flexible circuit board 210 and the CL film 220 are bonded via the adhesive layer 222.

[0031] As shown in FIG. 1, the releasing means 60 is disposed downstream in the conveying direction with respect to the hot press means 50. The releasing means 60 is configured to separate the FPC 200 from the release films 10A and 10B. In this case, in the hot pressing section 52 of the hot press means 50, the release film 10 is embedded in the 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), and the releasing means 60 is configured to peel (release) the release film 10 from the CL film 220 (FPC 200) by the action of the releasing means 60 (see FIG. 2(c)). Therefore, based on the action of the releasing 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 of being peeled off from the release film 10.

[0032] A flexible printed circuit board 200 (FPC200) can be manufactured using the above-described roll-to-roll press machine 100. Hereinafter, a method for manufacturing the FPC200 using this roll-to-roll press machine will be described. Note that the method for manufacturing the molded product of the present invention is applied to the method for manufacturing the FPC200.

[0033] In this embodiment, the manufacturing method of the FPC200 includes a first step of forming a laminate in which a glass cloth 300A, a release film 10A, the FPC200, a release film 10B, and a glass cloth 300B, each of which has a sheet-like shape, are stacked in this order, as shown in Figures 1 to 3; a second step of hot-pressing the laminate to bond a coverlay 221 (CL film 220) to the flexible circuit board 210 in the FPC200 via an adhesive layer 222; and a third step of releasing the release film 10 (10A, 10B) from the FPC200 to obtain an FPC200 in which the CL film 220 is bonded to the flexible circuit board 210.

[0034] Each of these steps will be described in turn below. (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 sheet form and wound around a winding roller, are laminated in this order during transport by a transport means (release film arrangement process, see Figures 1, 2(a), and 3).

[0035] The method of laminating each member (film) to the laminate is not particularly limited, and for example, the members may be laminated while being pressed by a roll, or may be laminated while being pressed by a press. The order in which the members are laminated can also be arbitrary. For example, all the members 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 members may be laminated at the same time.

[0036] Furthermore, the formation of the laminate in this first step constitutes a step of arranging the release film 10 on the target object (FPC 200) in the method for producing a molded product of the present invention.

[0037] (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 layered in this order is heated (heat-pressed) while being pressurized using a heat press means 50 (heat compression section 52). As a result, a curing reaction of the adhesive layer 222 progresses with the adhesive layer 222 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 process, see Figures 1, 2(b), and 3).

[0038] At this time, release film 10A is adhered to coverlay 221 and embedded in recesses 223 formed in coverlay 221, so that seepage of adhesive originating from adhesive layer 222 into recesses 223 is suppressed.

[0039] In this second step (hot pressing step), the temperature to which the FPC 200 is heated is not particularly limited, but is preferably, for example, 100° C. or higher and 250° C. or lower, and more preferably 150° C. or higher and 200° C. or lower.

[0040] In the second step, the pressure set in the thermocompression unit 52 when pressing the FPC 200 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.

[0041] 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 set to 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 the hot-press means 50, and in the peeling step (next step), the adhesion time until the release film 10 is peeled off from the bonded body is preferably set to 1.0 sec or more and 10.0 sec or less, more preferably set to 4.0 sec or more and 7.0 sec or less.

[0042] The second step constitutes a step of performing a heat press on the target object (FPC200) on which the release film 10 is arranged in the manufacturing method of the molded product of the present invention. 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 target object (FPC200) on which the release film 10 is arranged. Since the release film 10 is used overlapping 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, the release film 10 can maintain the shape of the coverlay 221 in which the recesses 223 are formed and the thermosetting resin can be cured, so that the coverlay 221 (molded product) can be molded with excellent accuracy on the flexible circuit board 210. Furthermore, since the adhesion time is set within the above range, the release film 10 can advance the curing reaction of the thermosetting resin constituting the coverlay 221 while maintaining the shape of the coverlay 221 in which the recesses 223 are formed.

[0043] The method for manufacturing a molded product of the present invention includes a step (first step) of placing the release film 10 on the target (FPC 200) so that the first release layer 1 of the release film 10 faces the target (FPC 200), and a step (second step) of performing a heat press on the target (FPC 200) on which the release film 10 is placed. In the step of placing the release film 10, the surface of the target (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, so that the coverlay 221 (molded product) can be molded with excellent accuracy on the flexible circuit board 210. In addition, since 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.

[0044] 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.

[0045] (Third step) Next, in a releasing means 60, the release film 10 (10A, 10B) is released from the FPC 200. That is, the release film 10A and the release film 10B are peeled off from the bonded body of the coverlay film 220 and the flexible circuit board 210. In this way, the FPC 200 in which the CL film 220 is bonded to the flexible circuit board 210 is obtained (peeling process, see Fig. 1, Fig. 2(c), and Fig. 3).

[0046] The release means 60 is not particularly limited, and may be, for example, a means configured to perform peeling by installing a vacuum device on the outside and drawing a vacuum, 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 perform peeling by inserting a rod between the bonded body and the release films 10A, 10B.

[0047] 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 their respective winding rollers.

[0048] By such winding, the flexible circuit board 210 and the CL film 220 are continuously obtained in a state where the FPC 200 bonded via the adhesive layer 222 provided on the CL film 220 is wound up on the winding roller.

[0049] As described above, by applying the manufacturing method of the flexible printed circuit boards 200 by the roll-to-roll press machine 100 using the release film 10, the flexible printed circuit boards 200 are manufactured continuously.

[0050] In addition, 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 constitutes the coverlay 221, thereby hardening the coverlay 221.

[0051] 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.

[0052] <Release film 10> FIG. 4 is a longitudinal sectional view showing an embodiment of the release film of the present invention, and FIG. 5 is a partially enlarged longitudinal sectional view showing part A of the release film shown in FIG.

[0053] As shown in FIG. 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 laminated in this order, and is used by overlapping it so that the surface on the first release layer 1 side is in contact with the CL film 220 provided on the FPC 200.

[0054] Each layer constituting this release film 10 will now be described. <Cushion layer 3> First, a description will be given of 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 Figs.

[0055] This cushion layer 3 is made of a third thermoplastic resin composition, and it is preferable to use a third thermoplastic resin composition that contains a plurality of types of thermoplastic resins while imparting embedding properties to the recesses 223 in the release film 10. This ensures sufficient conformability.

[0056] 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 polyolefin-based resins, and a combination of a polyamide-based resin and a polyolefin-based resin. Among these, by selecting a combination of a polyester-based resin and a polyolefin-based resin, the above-mentioned effects can be more reliably achieved.

[0057] The polyester resin is not particularly limited, and examples thereof include polyethylene terephthalate (PET), polycyclohexane terephthalate (PCT), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), polycyclohexane dimethylene terephthalate, polypropylene terephthalate, etc., and one or more of these can be used in combination. When two or more of these are used in combination, the polyester resin may be a blend or copolymer of these. Among these, the polyester resin is particularly preferably polybutylene terephthalate. This can provide the cushion layer 3 with excellent conformability to the recesses 223. In addition, 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.

[0058] In addition, the polyolefin resin is not particularly limited, and examples thereof include 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, which have ethylene, propylene, butene, pentene, hexene, octene, and the like as polymer components, and one or more of these can be used in combination. Among these, at least one of copolymers of ethylene and vinyl acetate (ethylene-vinyl acetate copolymer) and copolymers of ethylene and (meth)acrylic acid (ethylene-(meth)acrylic acid copolymer) is preferable. This allows the cushion layer 3 to have excellent conformability to the recesses 223.

[0059] In the case of a combination of a polyester resin and a polyolefin resin, 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 can provide the release film 10 with excellent conformability to the recesses 223.

[0060] In addition, the third thermoplastic resin composition constituting the cushion layer 3 may contain, in addition to the above-mentioned resin material (thermoplastic resin), additives such as a crystal nucleating agent, an antioxidant, a slip agent, an antiblocking agent, an antistatic agent, a colorant, and a stabilizer.

[0061] 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 part 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, it is possible to appropriately suppress or prevent contamination of the FPC 200. In addition, it is possible to easily peel off the release film 10 in the third step.

[0062] 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 elasticity using a dynamic viscoelasticity measuring device (Hitachi High-Tech Science Corporation, "DMA7100") in tensile mode, at a frequency of 1 Hz, and at a heating rate of 5°C / min.

[0063] Furthermore, the average thickness Tk of the cushion layer 3 is preferably set to 40 μm or more and 110 μm or less, and more preferably set to 50 μm or more and 90 μm or less, so that sufficient conformability can be ensured.

[0064] <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 side of the cushion layer 3, as shown in Figs.

[0065] The first release layer 1 has flexibility, and in the above-mentioned manufacturing method of the 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 a layer that is pressed in conformity with 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, 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) in the third step.

[0066] Therefore, in the second step, the release film 10 can appropriately suppress or prevent the adhesive from seeping out from the adhesive layer 222 into the recess 223 formed in the FPC 200. In addition, after the formation of the FPC 200 in which the flexible circuit board 210 and the CL film 220 are bonded via the adhesive layer 222 of the CL film 220 in the second step, when the release film 10 is peeled off from the FPC 200 in the third step, the occurrence of elongation and breakage in the FPC 200 can be appropriately suppressed or prevented. In addition, when the third thermoplastic resin composition constituting the cushion layer 3 contains a polyester resin, the first release layer 1 can exhibit excellent adhesion to the cushion layer 3.

[0067] Moreover, in the manufacturing method of the flexible printed circuit board 200, the first release layer 1 is in contact with the CL film 220 provided in the FPC 200. Therefore, in the second step of this manufacturing method, the first release layer 1 also has a function of transmitting heat from the heat bonding plate 521 to the CL film 220 when the FPC 200 is hot-pressed.

[0068] The first release layer 1 has an uneven surface. It is preferable that the protruding valley height Svk, which is the average depth of the protruding valleys, is 5 μm or more on the surface of the first release layer 1. By having the first release layer 1 with such surface roughness, 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 increased, and the release film 10 can be transported well and smoothly.

[0069] The protruding valley height Svk [μm] can be obtained in accordance with ISO 25178. Specifically, the protruding valley height Svk [μm] can be obtained as follows.

[0070] Using a scanning white light interference microscope (Keyence Corporation's "Laser Microscope VK-X3000"), with the objective lens set at 20x, four connected images (measurement range: approximately 2000 μm × 1500 μm) are obtained. The obtained images are then processed to set the average plane (reference plane). Next, Gaussian filter processing is performed, and the cutoff wavelengths are set to S filter: 2.5 μm and L filter: 8 mm. From the results of this processing, the average value of the protruding valley depth on the surface is calculated to determine the protruding valley height Svk [μm].

[0071] If the protruding valley height Svk is less than 5 μm, the releasability and slipperiness will be insufficient, and during the manufacture of the flexible printed circuit board 200, problems such as creases and breakage may occur in the flexible printed circuit board 200, or the flexible circuit board 210 may be scratched. Furthermore, the release film 10 cannot be transported well and smoothly.

[0072] 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, whereby the above-mentioned effects can be more reliably exhibited.

[0073] It is preferable that the area load ratio Smr2 separating the core portion and the protruding valley portion is 75% or more. This allows the release film 10 to more reliably exhibit excellent releasability from the CL film 220 (FPC 200). In addition, the slipperiness is more reliably improved, and the release film 10 can be transported well and smoothly. The area load ratio Smr2 can be determined in accordance with ISO 25178.

[0074] The areal load ratio Smr2 is preferably 80% or more and 99% or less, so that the above-mentioned effects can be more reliably achieved.

[0075] In addition, the first release layer 1 preferably 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 surface of the surface, and Sv [μm] is the maximum valley depth, which is the absolute value of the minimum value of the height from the average surface. By having the first release layer 1 with such surface roughness, 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, and the conveyance of the release film 10 can be performed 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.

[0076] Using a scanning white light interference microscope (Keyence Corporation's "Laser Microscope VK-X3000"), four connected images (measurement range: approximately 2000 μm × 1500 μm) are obtained with an objective lens at 20x magnification. The obtained images are then processed to set the average plane (reference plane). Next, Gaussian filter processing is performed, and the cutoff wavelengths are set to S filter: 2.5 μm and L filter: 8 mm. From the results of this processing, the maximum peak height, which is the maximum value of the height from the average 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 average plane, is calculated to obtain Sv [μm].

[0077] 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 allows the release film 10 to more reliably exhibit excellent releasability from the CL film 220 (FPC 200), and also allows the release film 10 to be more reliably improved in slipperiness and to be transported well and smoothly.

[0078] The method for making the surface of the first release layer 1 satisfy Sp+Sv≧27 is not particularly limited, but 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.

[0079] The maximum peak height Sp is preferably 10 μm or more. This makes it possible to more reliably exhibit excellent releasability of the release film 10 from the CL film 220 (FPC 200). In addition, the slipperiness is more reliably improved, and the release film 10 can be transported well and smoothly.

[0080] The maximum peak height Sp is preferably 10 μm or more and 60 μm or less, and more preferably 15 μm or more and 50 μm or less, so that the above-mentioned effects can be more reliably exhibited.

[0081] The maximum valley depth Sv is preferably 10 μm or more. This makes it possible to more reliably exhibit excellent releasability of the release film 10 from the CL film 220 (FPC 200). In addition, the slipperiness is more reliably improved, and the release film 10 can be transported well and smoothly.

[0082] The maximum valley depth Sv is preferably 10 μm or more and 60 μm or less, and more preferably 15 μm or more and 50 μm or less, so that the above-mentioned effects can be more reliably exhibited.

[0083] Moreover, the first release layer 1 preferably has an arithmetic mean height Sa, which is the average of the absolute values ​​of the height differences at each point with respect to the average plane of its surface, of more than 2.3 μm. By having the first release layer 1 with such surface roughness, the release film 10 can more reliably exhibit excellent releasability from the CL film 220 (FPC 200). In addition, the slipperiness can be more reliably increased, allowing the release film 10 to be transported well and smoothly.

[0084] The arithmetic mean height Sa is a value that represents the average of the absolute values ​​of the height differences of each protrusion, i.e., the heights of each point, with respect 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.

[0085] Using a scanning white light interference microscope (Keyence Corporation's "Laser Microscope VK-X3000"), the objective lens is set at 20x magnification to obtain four connected images (measurement range: approximately 2000 μm x 1500 μm). The obtained images are then processed to set the average plane (reference plane). Next, Gaussian filter processing is performed, and the cutoff wavelengths are set to S filter: 2.5 μm and L filter: 0.8 mm. From the results of this processing, the average of the absolute values ​​of the height differences at each point is calculated.

[0086] The arithmetic mean height Sa is preferably 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 allows the release film 10 to more reliably exhibit excellent releasability from the CL film 220 (FPC 200), and also allows the release film 10 to be more reliably improved in slipperiness and to be transported well and smoothly.

[0087] The method for making the arithmetic mean height Sa of the surface of the first release layer 1 exceed 2.3 μm is not particularly limited, but 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 to exceed 2.3 μm by adjusting the size of the filler or the conditions of the surface treatment.

[0088] This first release layer 1 is made of a first thermoplastic resin composition. In addition, this first thermoplastic resin composition preferably contains, for example, a polyester 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.

[0089] The polyester resin is not particularly limited, but may be, for example, the same as those listed in the third thermoplastic resin composition described above, and among them, polybutylene terephthalate (PBT) is particularly preferable. This allows the effect obtained by using the polyester resin to be more prominently exhibited. In addition, 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.

[0090] In addition, 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.

[0091] The first thermoplastic resin composition may further contain at least one of inorganic particles and organic particles in addition to the above-mentioned thermoplastic resin.

[0092] Examples of inorganic particles include, but are not limited to, 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. These particles may be used alone or in combination of two or more.

[0093] In addition, 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.

[0094] Furthermore, the inorganic particles and organic particles preferably have an average particle size of 3 μm to 40 μm, more preferably 5 μm to 30 μm. 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.

[0095] The average thickness T1 of the first release layer 1 is preferably set to 7 μm or more and 38 μm or less, 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 provided with the above-mentioned function as the first release layer 1 more reliably.

[0096] In addition, 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 convex portions and at positions including the concave portions in the concave portions.

[0097] In addition, the first thermoplastic resin composition constituting the first release layer 1 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.

[0098] <Second release layer 2> Next, the second release layer 2 will be described.

[0099] 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.

[0100] The second release layer 2 has flexibility, and in the above-mentioned manufacturing method of the 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 pressing plate 521 to the cushion layer 3. Furthermore, the second release layer 2 functions as a contact layer for exerting excellent releasability between the glass cloth 300 and the release film 10 in the third step.

[0101] 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 a function of transmitting heat from the thermocompression plate 521 to the cushion layer 3.

[0102] The second release layer 2 is made of a second thermoplastic resin composition. In addition, like the first thermoplastic resin composition, this second thermoplastic resin composition preferably contains mainly a polyester-based resin. This ensures that the second release layer 2 has the above-mentioned functions.

[0103] The polyester resin is not particularly limited, but may be, for example, the same as those listed in 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.

[0104] 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 ones as those listed for the first thermoplastic resin composition can be used.

[0105] The second thermoplastic resin composition may further contain at least one of inorganic particles and organic particles in addition to the above-mentioned thermoplastic resin.

[0106] The inorganic particles and organic particles are not particularly limited, but the same particles as those exemplified for the first thermoplastic resin composition can be used.

[0107] The second release layer 2 having such a configuration preferably has a storage modulus E' of 50 MPa or more, more preferably 50 MPa or more and 1000 MPa or less, at 150° C. This ensures that the second release layer 2 has the above-mentioned functions.

[0108] The average thickness T2 of the second release layer 2 is preferably set to 7 μm or more and 38 μm or less, 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.

[0109] 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.

[0110] 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.

[0111] In the release film 10 having a laminated structure of the first release layer 1, the cushion layer 3, and the 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.

[0112] 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 disposed 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.

[0113] Furthermore, in the release film 10, the second release layer 2 that comes into contact with the glass cloth 300 may be omitted as long as excellent releasability can be maintained between the glass cloth 300 and the release film 10 in the third step.

[0114] Although the method for producing the release film and the molded article of the present invention has been described above, the present invention is not limited thereto.

[0115] For example, in the above embodiment, the release film of the present invention is described as being applied to a press molding method in which flexible printed circuit boards arranged between thermocompression plates are stacked in one layer, but the number of stacked flexible printed circuit boards is not limited to one layer and may be two or more layers.

[0116] Further, although the release film of the present invention is applied to a case where a flexible printed circuit board arranged between thermocompression plates is pressed using a roll-to-roll press, the present invention is not limited thereto, and the pressurization of the flexible printed circuit board can be carried out, for example, using a press molding method, or further, can be carried out using a vacuum pressure molding method. EXAMPLES

[0117] The present invention will be described in detail below based on examples, but the present invention is not limited to these.

[0118] 1. Preparation of raw materials The following raw materials were prepared for producing the release film:

[0119] Thermoplastic resin materials Ethylene-methyl methacrylate copolymer (EMMA, Sumitomo Chemical Co., Ltd., "WD203-1") Polypropylene (PP, Prime Polypro, "E111G") Polybutylene terephthalate (PBT, Chang Chun Petrochemical Co., Ltd., "1100-630S") Copolymerized polybutylene terephthalate (PBT, Mitsubishi Engineering Plastics Corporation, "5505S")

[0120] 2.Production of release film <Example 1> First, a first thermoplastic resin composition was prepared that was composed of 70% by weight of polybutylene terephthalate (PBT, 1100-630S) and 30% by weight of copolymerized polybutylene terephthalate (PBT, 5505S). A second thermoplastic resin composition was prepared that was composed of 100% by weight of polybutylene terephthalate (PBT, 1100-630S). A third thermoplastic resin composition was prepared that was composed of 55% by weight of ethylene-methyl methacrylate copolymer (EMMA, WD203-1), 20% by weight of polypropylene (PP, E111G), and 25% by weight of polybutylene terephthalate (PBT, 1100-630S).

[0121] 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 in which the first release layer 1, the cushion layer 3, and the second release layer 2 were laminated in that order.

[0122] 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.

[0123] At this time, the first release layer 1 was subjected to a roughening treatment for transferring the surface shape by using at least one of the first roll and the touch roll.

[0124] Moreover, 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.

[0125] Moreover, on the surface of the first release layer 1, the surface area load ratio Smr2 separating the core portion and the protruding valley portion was 92%.

[0126] Moreover, the 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 the surface of the first release layer 1, was 3.1 μm.

[0127] 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 defined as Sp [μm], and the maximum valley depth, which is the absolute value of the minimum value of the height from the average plane, is defined as Sv [μm], Sp + Sv was 28 μm.

[0128] The protruding valley height Svk, areal load ratio Smr2, arithmetic mean height Sa, and maximum peak height Sp+maximum valley depth Sv were determined as follows.

[0129] Using a scanning white light interference microscope (Keyence Corporation's "Laser Microscope VK-X3000"), four connected images (measurement range: approximately 2000 μm × 1500 μm) are obtained with a 20x objective lens. The obtained images are subjected to a process of setting the average plane (reference plane). Next, Gaussian filter processing is performed, and the cutoff wavelengths are set to S filter: 2.5 μm and L filter: 0.8 mm. From the processing results, the protruding valley height Svk, the areal area ratio Smr2, the arithmetic mean height Sa, and the maximum peak height Sp + maximum valley depth Sv are obtained. At this time, the values ​​of the four regions from the first quadrant to the fourth quadrant of the connected images are obtained, and the average value is used as the value.

[0130] <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 Example 1, except that the conditions of the roughening treatment on the surface of the first release layer 1 were adjusted and the protruding valley height Svk, the load area ratio Smr2, the arithmetic mean height Sa, and the maximum peak height Sp + maximum valley depth Sv were changed as shown in Table 1.

[0131] 3. Evaluation The release films 10 of each of the Examples and Comparative Examples were evaluated as follows.

[0132] 3-1.Release properties of release film The release film 10 of each of the examples and comparative examples was made to have a width of 270 mm. 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 projections and recesses with a pitch of 50 μm, a width of 50 μm, and a height of 18 μm. The release film 10 was then pressed against the laminated FPC 200 as shown in FIG. 3 using a RtoR press machine (manufactured by TRM, "RR Q-CURE 100TON CONTINUOUS LAMINATOR") at 180° C. and 110 kg / cm. 2 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 off the release film 10 (releasability) was evaluated according to the following criteria.

[0133] [Evaluation Criteria] ⊚: The release film was peelable. ×: When peeling off the release film, peeling is difficult due to fusion between the cushion layers or stretching or breaking of the release film.

[0134] 3-2. Slipperiness of release film (Exterior wrinkles) The effect of preventing wrinkles due to good slipperiness was evaluated as follows.

[0135] A test piece 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 surface coated with an adhesive was in contact with the surface. Next, a release film 10 was pressed and attached to the test piece using a roll-to-roll press under conditions of 175° C., 11 MPa, and 120 sec, and immediately after pressing, the test piece and the release film 10 were peeled off while being transported at 200 mm / s. The surface of the test piece was measured in accordance with “7.5.7.2 Wrinkles” of the JPCA standard.

[0136] [Evaluation Criteria] ◎: Wrinkle occurrence rate less than 1.0% ○: Wrinkle occurrence rate 1.0% or more, less than 2.0% ×: Wrinkle occurrence rate 2.0% or more

[0137] 3-3. Summary The evaluation results obtained in the above 3-1. Releasability of release film and 3-2. Slipperiness of release film are shown in Table 1.

[0138] [Table 1]

[0139] As shown in Table 1, in each embodiment, the first release layer 1 has a protruding valley height Svk, which is the average depth of the protruding valley on its surface, set to 5 μm or more, and as a result, it exhibits excellent release properties and slip resistance.

[0140] In contrast, in each of the comparative examples, the protruding valley height Svk was not set to 5 μm or more, and as a result, the results showed that the releasability and slipperiness were not excellent. [Explanation of symbols]

[0141] 1 First release layer 2 Second release layer 3 Cushioning layer 10 Release film 10A Release film 10B Release film 50 Heat press means 52 Heat-pressing section 60 Demolding Method 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-pressing plate T1 Average thickness of the first release layer T2 Average thickness of the 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, The first release layer is a release film characterized in that, on its surface, the protruding valley height Svk, which is the average depth of the protruding valleys, is 5 μm or more and 30 μm or less, and the load area ratio Smr2 separating the core portion and the protruding valleys is 75% or more and 99% or less.

2. The release film according to claim 1 , further comprising a second release layer made of a second thermoplastic resin composition laminated on the cushion layer on the side opposite the first release layer.

3. The release film according to claim 1 , wherein the first thermoplastic resin composition comprises a polyester resin or a poly-4-methyl-1-pentene resin.

4. The release film according to claim 1 , wherein the cushion layer is made of a third thermoplastic resin composition containing a polyester-based resin and a polyolefin-based resin.

5. The release film according to claim 1 , wherein the first release layer has an average thickness of 7 μm or more and 38 μm or less.

6. The release film according to claim 1 , wherein the cushion layer has an average thickness of 40 μm or more and 110 μm or less.

7. The release film according to claim 1 , wherein the average thickness of the release film is 50 μm or more and 180 μm or less.

8. The release film is applied to a surface of an object formed of a material containing a semi-cured thermosetting resin. The release film according to claim 1 , wherein the first release layer is placed on the second release layer and the first release layer is placed on the first release layer.

9. The release film according to claim 1 is attached to the object side so that the first release layer of the release film faces the object side. A method for manufacturing a molded product, comprising: a step of placing the release film on 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 thermosetting resin in a semi-cured state.

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