Method for manufacturing release film and molded product

Abstract

To provide a release film having excellent embedding properties, and a method for manufacturing a molded product using such a release film. [Solution] The release film of the present invention is a release film used in contact with an object having a conductor with a thickness of 50 μm or more, and comprises a first release layer made of a first thermoplastic resin composition and a cushion layer laminated on the first release layer, wherein the average thickness of the cushion layer is 60% to 80% of the average thickness of the release film. Furthermore, it is preferable that the release film has a storage modulus E' of 10 MPa to 25 MPa at 180°C. Furthermore, it is preferable that the release film has a second release layer made of a second thermoplastic resin composition laminated on the side of the cushion layer opposite to the first release layer.

Description

Technical Field

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

Background Art

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

[0003] Such release films have been required to have excellent embedding properties. Specifically, first, when a coverlay film is adhered to a flexible circuit board, recesses are formed due to the adhesion of the coverlay film to the flexible circuit board. The release film is required to exhibit excellent embedding properties with respect to these recesses.

[0004] More specifically, the adhesion of the coverlay film to the flexible circuit board is performed through the adhesive layer provided on the coverlay film. During this adhesion, it is required that the release film exhibits excellent embedding properties with respect to the recesses and suppresses the bleeding of the adhesive within the recesses.

[0005] The thickness of the conductor, which is the exposed circuit portion of the flexible circuit board, is usually 35 μm or less. However, in recent years, the use in in-vehicle applications and the like has increased, and since more current is required to flow, substrates with an increased conductor thickness may be used. However, when the conductor thickness of the substrate increases, heat conduction to the adhesive layer during heat pressing becomes difficult, resulting in a problem that the curing of the adhesive takes time and the bleeding of the adhesive within the recesses increases. Therefore, in order to solve such problems, a release film that exhibits excellent embedding properties with respect to the recesses and can suppress the bleeding of the adhesive is required.

[0006] Furthermore, similar problems arise when a release film is applied to an object formed from a material containing a semi-cured thermosetting resin, and the curing reaction of the thermosetting resin is allowed to proceed in this state, thereby manufacturing molded products using the object. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Patent No. 6470461 [Overview of the project] [Problems that the invention aims to solve]

[0008] The object of the present invention is to provide a release film having excellent embedding properties, and a method for manufacturing a molded product using such a release film. [Means for solving the problem]

[0009] The purpose of this is as follows (1) ~ (5) This is achieved by the present invention as described above. (1) A release film used in contact with an object having a conductor with a thickness of 50 μm or more, The release film comprises a first release layer made of a first thermoplastic resin composition and a cushion layer laminated on the first release layer. The average thickness of the cushion layer is 60% to 80% of the average thickness of the release film. the law of nature, The storage modulus E' of the cushion layer at 180°C is between 1 MPa and 20 MPa. The storage modulus E' of the first release layer at 180°C is between 5 MPa and 30 MPa. The first thermoplastic resin composition comprises poly-4-methyl-1-pentene resin, The cushion layer is made of a third thermoplastic resin composition containing a polyolefin resin. The first release layer has an average thickness of 15 μm or more and 30 μm or less. The cushion layer has an average thickness of 90 μm or more and 120 μm or less. The release film has an average thickness of 120 μm or more and 180 μm or less. Release film.

[0010] (2) The release film is the release film according to (1) above, having a storage elastic modulus E’ at 180°C of 10 MPa or more and 25 MPa or less.

[0011] (3) The release film is the release film according to (1) or (2) above, having a second release layer made of a second thermoplastic resin composition, laminated on the side opposite to the first release layer of the cushion layer.

[0012] (4) The poly-4-methyl-1-pentene resin is a release film according to (1) or (3) above, wherein the melt flow rate (MFR) measured at 260°C and a 5.0 kg load is 5 g / 10 min or more and 21 g / 10 min or less.

[0017] (5) A method for manufacturing a molded product, including a step of disposing the release film on the object such that the first release layer of the release film according to (1) or (4) above faces the object side, and a step of performing a hot press on the object on which the release film is disposed. In the step of disposing the release film, the surface of the object on which the release film is to be disposed is formed of a material containing a semi-cured thermosetting resin.

Advantages of the Invention

[0018] According to the present invention, it is possible to provide a release film having excellent embedding properties and a method for manufacturing a molded product using such a release film.

Brief Description of the Drawings

[0019] [Figure 1] It is a side view showing a main part of a roll-to-roll press machine used for manufacturing a flexible printed circuit board. [Figure 2] It is a longitudinal 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. [Figure 3] It is a longitudinal sectional view showing a hot press step in a method for manufacturing a flexible printed circuit board using the roll-to-roll press machine shown in FIG. 1. [Figure 4]It is a longitudinal sectional view showing an embodiment of the release film of the present invention.

Embodiments for Carrying out the Invention

[0020] Hereinafter, preferred embodiments of the present invention will be described in detail. In the following, as an example, the case where the flexible printed circuit board is manufactured using a roll-to-roll press machine will be described with respect to the manufacturing of the flexible printed circuit board using the release film of the present invention. Also, prior to describing the manufacturing method of the release film and the molded product of the present invention, first, the roll-to-roll press machine used for manufacturing this flexible printed circuit board will be described.

[0021] [1] Roll-to-roll press machine FIG. 1 is a side view showing the main part of a roll-to-roll press machine used for manufacturing a flexible printed circuit board, FIG. 2 is a longitudinal sectional view showing each process in the manufacturing method of a flexible printed circuit board using the roll-to-roll press machine shown in FIG. 1, and FIG. 3 is a longitudinal sectional view showing the heating press process in the manufacturing method of a flexible printed circuit board using the roll-to-roll press machine shown in FIG. 1. In the following, for convenience of explanation, the upper side in FIGS. 1 to 3 is referred to as "upper" or "above", the lower side as "lower" or "below", the left side as "left", and the right side as "right".

[0022] As shown in Figures 1 to 3, the roll-to-roll press (RtoR press) 100 includes a transport means (not shown) for transporting release films 10 (10A, 10B), a flexible printed circuit board (FPC) 200, and glass cloths 300A, 300B; a heating press means 50 for joining the flexible circuit board 210 and the coverlay film (CL film) 220 of the FPC 200 by heating and pressing the CL film 220 against the flexible circuit board 210 using the release film 10; and a release means 60 for releasing (peeling off) the release film 10 from the FPC 200 with the CL film 220 joined to the flexible circuit board 210. The CL film 220 comprises a coverlay 221 and an adhesive layer 222. The flexible circuit board 210 has a base material 212 and a conductor 211 laminated on one side of the base material 212. The conductor 211 is an exposed circuit portion located on the side of the flexible circuit board 210 to which the CL film 220 is bonded.

[0023] The conveying means conveys the FPC 200, release films 10A and 10B, and glass cloths 300A and 300B, each wound on different unwinding rollers, along their respective longitudinal directions by the rotation of tensioners (tension rollers), and after processing by the heating press means 50 and the release means 60, the winding rollers wind them.

[0024] Each roller is made of a metal material, such as stainless steel. Furthermore, the pivot axes (central axes) of these rollers are aligned in the same direction and are spaced apart from one another.

[0025] As shown in Figure 1, the heating press means 50 has a heating and pressing section 52. The heating and pressing section 52 has a pair of heating and pressing plates 521. The heating and pressing plates 521 are transported by a transport means and are positioned one above and one below a laminate in which glass cloth 300A, release film 10A, FPC 200, release film 10B, and glass cloth 300B are stacked. As the laminate passes between the heating and pressing plates 521, the heating and pressing plates 521 heat and pressurize the FPC 200 through the glass cloth 300A, 300B and the release films 10A, 10B. Therefore, as shown in Figure 2(a), the curing reaction of the adhesive layer 222 of the CL film 220 proceeds due to this heating, and in the FPC 200, the stacked flexible circuit board 210 and the CL film 220 are joined via the adhesive layer 222.

[0026] In other words, the coverlay 221 and the flexible circuit board 210 are joined via the adhesive layer 222 (see Figure 2(a)). Furthermore, when the FPC 200 is heated and pressurized, that is, when the coverlay 221 and the flexible circuit board 210 are joined via the adhesive layer 222, the release film 10 is embedded in the recess 223 formed in the coverlay 221. As a result, seepage (overflow) of adhesive originating from the adhesive layer 222 within the recess 223 is suppressed (see Figure 2(b)). In addition, by having a release layer as described later, even if there is seepage (overflow) of adhesive originating from the adhesive layer 222, the release film 10 can exhibit excellent release properties.

[0027] Before being heat-pressed by the heat-pressure plate 521, the FPC 200 is in a laminated state with the flexible circuit board 210 and the CL film 220 stacked on top of each other, but the flexible circuit board 210 and the CL film 220 are not joined via the adhesive layer 222 of the CL film 220. Then, when pressed by the heat-pressure plate 521, the adhesive layer 222 of the CL film 220 adheres closely to the flexible circuit board 210, and in this state, the curing reaction of the adhesive layer 222 proceeds due to heating by the heat-pressure plate 521, so that the flexible circuit board 210 and the CL film 220 are joined via the adhesive layer 222.

[0028] As shown in Figure 1, the release mechanism 60 is positioned downstream of the heating press mechanism 50 in the transport direction. This release mechanism 60 is configured to separate the FPC 200 from the release films 10A and 10B.

[0029] Here, in the heating and pressing section 52 of the heating and pressing means 50, as shown in Figure 2(b), the release film 10 is embedded in the recess 223 formed in the coverlay 221. As a result, the release film 10 is bonded to the CL film 220 (FPC 200), but the release means 60 is configured to allow the release film 10 to be peeled (released) from the CL film 220 (FPC 200) (see Figure 2(c)). Therefore, based on the action of the release means 60, the FPC 200, in which the flexible circuit board 210 and the CL film 220 are bonded via the adhesive layer 222, is obtained in a state where it is peeled from the release film 10.

[0030] [2] Method for manufacturing flexible printed circuit boards (method for using release film) A flexible printed circuit board (FPC200) can be manufactured using the roll-to-roll press machine 100 described above. The manufacturing method for the FPC200 using this roll-to-roll press machine 100 will be described below.

[0031] The method for manufacturing the FPC200 in this embodiment is the method for manufacturing a molded product of the present invention. That is, the method for manufacturing the FPC200 in this embodiment includes the steps of: placing the release film 10 on an object so that the first release layer 1 of the release film 10, which will be described later, faces the object; and performing a heat press on the object on which the release film 10 is placed. The method is characterized in that, in the step of placing the release film 10, the surface of the object on which the release film 10 is placed is formed of a material containing a semi-cured thermosetting resin.

[0032] More specifically, the manufacturing method of the FPC200 in this embodiment, as shown in Figures 1 to 3, comprises a first step (arrangement step) of stacking glass cloth 300A, release film 10A, FPC200, release film 10B, and glass cloth 300B, each in the form of a sheet, in this order; a second step (heat pressing step) of heat pressing the laminate to bond the coverlay 221 (CL film 220) to the flexible circuit board 210 in the FPC200 via an adhesive layer 222; and a third step of peeling off the release films 10 (10A, 10B) from the FPC200 to obtain an FPC200 in which the CL film 220 is bonded to the flexible circuit board 210. The following explains each of these steps in order.

[0033] [2-1] First step First, the glass cloth 300A, release film 10A, FPC 200, release film 10B, and glass cloth 300B, each in a sheet form and wound around an unwinding roller, are stacked in this order during transport by the transport means to form a laminate (see release film placement process, Figures 1 and 2(a)).

[0034] The method of laminating each component (film) into the laminate is not particularly limited; for example, they may be laminated while being pressed by a roll, or while being pressed by a plate-shaped component. The order in which each component is laminated can also be arbitrary. For example, all components may be laminated simultaneously, or the coverlay film 220 and the flexible circuit board 210 may be laminated in advance, and then the other components may be laminated simultaneously.

[0035] Furthermore, the formation of the laminate in this first step constitutes the step of placing the release film 10 on the object (FPC200) in the method for manufacturing a molded product of the present invention.

[0036] [2-2] Second step Next, the laminate, in which the glass cloth 300A, release film 10A, FPC 200, release film 10B, and glass cloth 300B are stacked in this order, is heated and pressed using a heating press means 50 (heating and pressing unit 52). As the adhesive layer 222 adheres tightly to the flexible circuit board 210, the curing reaction of the adhesive layer 222 proceeds, and in the FPC 200, a bond is formed in which the coverlay 221 (CL film 220) is bonded to the flexible circuit board 210 via the adhesive layer 222 (see heating and pressing process, Figures 1, 2(b), and 3).

[0037] Furthermore, as the release film 10A adheres closely to the coverlay 221 and is embedded in the recess 223 formed in the coverlay 221, the seepage (overflow) of adhesive originating from the adhesive layer 222 within the recess 223 is suppressed. In addition, by having a release layer as described later, even if there is seepage (overflow) of adhesive originating from the adhesive layer 222, the release film 10 can exhibit excellent release properties.

[0038] In this second step (heating and pressing step), the temperature at which the FPC200 is heated is not particularly limited, but is preferably 100°C or more and 250°C or less, and more preferably 150°C or more and 200°C or less.

[0039] As the thickness of the conductor 211 increases, heat is less easily conducted to the adhesive layer 222 during heating and pressing. However, by keeping the heating temperature within the aforementioned range, sufficient heat can be conducted to the adhesive layer 222, allowing the adhesive to harden.

[0040] Furthermore, in the second step, when pressurizing the FPC200, the pressure set in the heating and crimping section 52 is not particularly limited, but is preferably 0.1 MPa or more and 14 MPa or less, and more preferably 1 MPa or more and 14 MPa or less.

[0041] Furthermore, the transport speed for transporting the laminate is preferably 10 mm / sec to 400 mm / sec, and more preferably 20 mm / sec to 350 mm / sec. In other words, the adhesion time from the second step (this step) in which the laminate is heated and pressed using the heating press means 50, until the release film 10 is peeled off the bonded body in the peeling step (next step), is preferably 1.0 sec to 250.0 sec, and more preferably 4.0 sec to 200.0 sec.

[0042] By keeping the adhesion time within the aforementioned range, even if the thickness of the conductor 211 of the FPC 200 increases, sufficient heat can be conducted to the adhesive layer 222, allowing the adhesive to harden.

[0043] Furthermore, the second step constitutes a step in the manufacturing method of the molded product of the present invention in which a heat press is performed on the object (FPC200) on which the release film 10 is placed.

[0044] Furthermore, although this embodiment shows a means of heating by a heating press using a plate-shaped member, it is not necessarily limited to this method. For example, heating may be performed by infrared radiation or by heating rolls.

[0045] [2-3] Third step Next, the release means 60 peels the release films 10 (10A, 10B) from the FPC 200. That is, the release films 10A and 10B are peeled off from the bond between the coverlay film 220 and the flexible circuit board 210. This results in an FPC 200 with the CL film 220 bonded to the flexible circuit board 210 (peeling process, see Figures 1 and 2(c)).

[0046] The release means 60 is not particularly limited and may be configured to release by installing a vacuum device on the outside and creating a vacuum, or by sending air between the bonded body and the release films 10A and 10B, or by inserting a rod between the bonded body and the release films 10A and 10B.

[0047] Subsequently, the bonded assembly of the coverlay film 220 and the flexible circuit board 210, along with the glass cloth 300A, release film 10A, release film 10B, and glass cloth 300B, are wound up using their respective winding rollers.

[0048] Through this winding process, the FPC 200, in which the flexible circuit board 210 and the CL film 220 are joined via the adhesive layer 222 of the CL film 220, is continuously obtained in a state where it is wound onto a winding roller.

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

[0050] Furthermore, after the third step described above, the process may include a step in which the flexible printed circuit board 200, which is wound onto a winding roller, or the individual sheets obtained by cutting the wound flexible printed circuit board 200 into separate pieces, is heated in an oven or the like to further advance the curing reaction of the thermosetting resin constituting the coverlay 221, thereby curing the coverlay 221.

[0051] The release film of the present invention is applied to the release film 10 used in the manufacture of this flexible printed circuit board 200. The release film 10 to which the release film of the present invention is applied will be described below.

[0052] [3] Release film The release film 10 of the present invention is a release film used in contact with an object having a conductor 211 with a thickness of 50 μm or more. The release film 10 has a first release layer 1 made of a first thermoplastic resin composition and a cushion layer 3 laminated on the first release layer 1, wherein the average thickness of the cushion layer 3 is 60% to 80% of the average thickness of the release film 10.

[0053] This makes it possible to provide a release film 10 with excellent embedding properties. More specifically, for example, when bonding a coverlay film 220 to a flexible circuit board 210, the release film 10 exhibits excellent embedding properties in the recesses 223, thereby suppressing the leakage of adhesive within the recesses 223.

[0054] More specifically, if the thickness of the conductor 211 of the flexible circuit board 210 is large, such as 50 μm or more, the curing of the adhesive takes time, and the leakage of adhesive into the recesses during that time increases. However, because the release film 10 has excellent embedding properties, the leakage of adhesive into the recesses 223 can be suppressed.

[0055] The excellent effects of the present invention are obtained when the release film 10 satisfies the above-mentioned conditions, and cannot be obtained when the above-mentioned conditions are not met.

[0056] For example, if the release film 10 does not have a cushion layer 3, the embedding ability of the release film 10 into the recess 223 will decrease, and the seepage of adhesive within the recess 223 will not be sufficiently suppressed.

[0057] Furthermore, if the average thickness of the cushion layer 3 is less than 60% of the average thickness of the release film 10, the conformability and flexibility of the release film 10 will decrease. Consequently, the embedding ability of the release film 10 into the recess 223 will decrease, and the leakage of adhesive within the recess 223 will not be sufficiently suppressed.

[0058] Furthermore, if the average thickness of the cushion layer 3 exceeds 80% of the average thickness of the release film 10, the release properties of the release film 10 will decrease. More specifically, after the coverlay film 220 is bonded to the flexible circuit board 210, the release film 10 cannot be peeled off the formed flexible printed circuit board 200 with good release properties.

[0059] The average thickness of the cushion layer 3 is 60% to 80% of the average thickness of the release film 10, but is preferably 62% to 75%, and more preferably 64% to 70%. This makes the aforementioned effects more pronounced.

[0060] The thickness of the conductor 211 of the flexible circuit board 210 is 50 μm or more, but is preferably 120 μm or less, and more preferably 110 μm or less. This allows heat to be more efficiently conducted to the adhesive layer 222, enabling the adhesive to cure, and thus improving the productivity of the release film 10.

[0061] The flexible circuit board 210 has a conductor 211 which is an exposed circuit portion on at least the side to which the CL film 220 is bonded, but it may also have a conductor on the side opposite to the side to which the CL film 220 is bonded.

[0062] For example, copper, aluminum, silver, nickel, etc., can be used as the conductor 211 of the flexible circuit board 210.

[0063] Figure 4 is a longitudinal cross-sectional view showing an embodiment of the release film of the present invention. In this embodiment, the release film 10 is composed of a laminate in which a first release layer 1 made of a first thermoplastic resin composition, a cushion layer 3, and a second release layer 2 are laminated in this order.

[0064] The following describes each layer that makes up this release film 10. [3-1] Cushion layer First, let's explain the cushion layer 3. The release film 10 has a cushion layer 3 laminated on the first release layer 1. The cushion layer 3 is the part that contributes to the embedding properties.

[0065] As shown in Figure 4, in this embodiment, the cushion layer 3 is positioned as an intermediate layer between the first release layer 1 and the second release layer 2.

[0066] This cushion layer 3 is more preferably made of a thermoplastic resin, with the aim of providing the release film 10 with suitable embedding properties for the recesses 223.

[0067] In particular, the cushion layer 3 is preferably made of a third thermoplastic resin composition containing a polyolefin resin. This makes it possible to improve the embedding properties of the release film 10.

[0068] The polyolefin resin included in the third thermoplastic resin composition is not particularly limited and includes, for example, polyethylene such as low-density polyethylene and high-density polyethylene, α-olefin polymers such as polypropylene, ethylene-α-olefin copolymers which are copolymers of ethylene and α-olefins other than ethylene such as propylene, 1-butene, 1-pentene, 1-hexene, and 1-octene, copolymers of ethylene and (meth)acrylic acid (ethylene-(meth)acrylic acid copolymer), copolymers of ethylene and (meth)acrylic acid ester (ethylene-(meth)acrylic acid ester copolymer), copolymers of ethylene and vinyl acetate (ethylene-vinyl acetate copolymer), and one or more of these can be used in combination.

[0069] In particular, it is preferable that it be at least one of the following: ethylene-methyl methacrylate copolymer (a copolymer of ethylene and methyl methacrylate), ethylene-vinyl acetate copolymer, ethylene-methyl acrylate copolymer (a copolymer of ethylene and methyl acrylate), and ethylene-α-olefin copolymer.

[0070] This makes it easier to further improve the cushioning properties of the cushioning layer 3 and to further improve its ability to conform to the recesses 223.

[0071] Examples of thermoplastic resins other than polyolefin resins include polyester resins and polyamide resins, but it is preferable to include polyester resins.

[0072] This makes it easier to further improve the cushioning properties of the cushioning layer 3 and to further improve its ability to conform to the recesses 223.

[0073] Examples of polyester resins include polyethylene terephthalate (PET), polycyclohexane terephthalate (PCT), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), polycyclohexanedimethylene terephthalate, polypropylene terephthalate, and copolymers thereof. One or more of these can be used in combination.

[0074] Among these, polybutylene terephthalate-based resins (polybutylene terephthalate or copolymers containing polybutylene terephthalate) are preferred.

[0075] This makes the aforementioned effects even more pronounced. In particular, when the release layer (at least one of the first release layer 1 and the second release layer 2) is made of a material containing a polybutylene terephthalate resin (polybutylene terephthalate or a copolymer containing polybutylene terephthalate), these effects are even more pronounced.

[0076] The cushion layer 3 preferably contains at least one type of thermoplastic resin, but more preferably contains multiple types of thermoplastic resins. This makes it possible to improve the embedding properties of the release film 10.

[0077] The cushion layer 3 may contain components other than those listed above. Hereinafter, in this section, such components will also be referred to as "other components." Examples of such components include crystal nucleating agents, antioxidants, slip agents, antiblocking agents, antistatic agents, colorants, stabilizers, and the like.

[0078] However, the content of other components in the cushion layer 3 is preferably 10% by mass or less, more preferably 5% by mass or less, and even more preferably 3% by mass or less.

[0079] The storage modulus E' of the cushion layer 3 at 180°C is preferably 1 MPa or more and 20 MPa or less, more preferably 2 MPa or more and 15 MPa or less, and even more preferably 5 MPa or more and 10 MPa or less.

[0080] As a result, in the second step, when embedding the release film 10 into the recess 223, the release film 10 exhibits better embedding properties, and the leakage of adhesive into the recess 223 can be more accurately suppressed or prevented. In addition, in the third step, the release film 10 can be peeled off more easily.

[0081] The storage modulus E' of the cushion layer 3 at 180°C can be determined, for example, by preparing a cushion layer 3 with a width of 4 mm and a length of 20 mm in accordance with JIS K7244-4, and measuring it using a dynamic viscoelasticity measuring device (Hitachi High-Tech Science Corporation, "DMA7100") in tensile mode, with a frequency of 1 Hz and a heating rate of 5°C / min.

[0082] The average thickness Tk of the cushion layer 3 is preferably 90 μm or more and 120 μm or less, and more preferably 95 μm or more and 105 μm or less.

[0083] This prevents the release film 10 from becoming excessively thick, while making it easier to improve the cushioning properties of the cushion layer 3 and improve its ability to conform to the recesses 223.

[0084] [3-2] First release layer The first release layer 1 is made of the first thermoplastic resin composition and is laminated on one side of the cushion layer 3. The first release layer 1 constitutes one surface of the release film 10.

[0085] The first release layer 1 is flexible, and in the manufacturing method of the flexible printed circuit board 200 using the release film 10 described above, the release film 10 is superimposed on the CL film 220 of the FPC 200 so that the first release layer 1 is in contact with it. Then, in the second step, when the superimposed flexible circuit board 210 and CL film 220 are joined via the adhesive layer 222, the first release layer 1 is pressed in to conform to the shape of the recess 223 formed by the flexible circuit board 210 and CL film 220, and functions as a protective (cushioning) material to prevent the release film 10 from tearing. Furthermore, in the third step, the first release layer 1 functions as a contact layer to enable the release film 10 to exhibit excellent release properties from the CL film 220 (FPC 200).

[0086] Therefore, when embedding the release film 10 into the recess 223 formed in the FPC 200 in the second step, it is possible to effectively suppress or prevent the adhesive originating from the adhesive layer 222 from seeping out. Furthermore, after the formation of the FPC 200 in which the flexible circuit board 210 and the CL film 220 are joined via the adhesive layer 222 of the CL film 220 in the second step, when peeling the release film 10 from the FPC 200 in the third step, it is possible to effectively suppress or prevent stretching and breakage of the FPC 200.

[0087] Furthermore, the first thermoplastic resin composition preferably contains poly-4-methyl-1-pentene resin. This makes it possible to improve the release properties of the release film 10, as well as the flexibility and conformability of the release film 10, and to improve the embedding properties of the release film 10.

[0088] Furthermore, the poly-4-methyl-1-pentene resin preferably has a melt flow rate (MFR) of 5 g / 10 min to 250 g / 10 min, measured at 260°C and a 5.0 kg load, more preferably 30 g / 10 min to 200 g / 10 min, and even more preferably 40 g / 10 min to 160 g / 10 min. This allows the effects obtained by using poly-4-methyl-1-pentene resin to be exhibited more significantly.

[0089] The first thermoplastic resin composition may also contain resin materials other than poly-4-methyl-1-pentene resin. Examples of such resin materials include polyester resins such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate; polyolefin resins other than poly-4-methyl-1-pentene, such as polyethylene and polypropylene; and polystyrene resins such as syndiotactic polystyrene. One or more of these can be used in combination.

[0090] The content of the first thermoplastic resin composition in the first release layer 1 is preferably 80% by mass or more, more preferably 85% by mass or more, and even more preferably 90% by mass or more. This makes the aforementioned effects even more pronounced.

[0091] Furthermore, the first release layer 1 may also contain at least one of inorganic particles and organic particles in addition to the thermoplastic resin.

[0092] Inorganic particles are not particularly limited, but examples 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, etc., and one or more of these can be used in combination.

[0093] Furthermore, while the organic particles are not particularly limited, examples 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 can be used in combination.

[0094] Furthermore, the inorganic and organic particles preferably have an average particle diameter of 3 μm or more and 20 μm or less, and more preferably 5 μm or more and 20 μm or less.

[0095] Furthermore, as the average particle size of inorganic and organic particles, the median diameter (D50), which is determined by measuring the particle size distribution on a volume basis using a laser diffraction particle size distribution analyzer (e.g., HORIBA LA-500), can be used.

[0096] The first release layer 1 may contain components other than those listed above. Hereinafter, in this section, such components will also be referred to as "other components." Examples of such components include crystal nucleating agents, antioxidants, slip agents, antiblocking agents, antistatic agents, colorants, stabilizers, and the like.

[0097] However, the content of other components in the first release layer 1 is preferably 10% by mass or less, more preferably 5% by mass or less, and even more preferably 3% by mass or less.

[0098] The storage modulus E' of the first release layer 1 at 180°C is preferably 5 MPa or more and 30 MPa or less, more preferably 10 MPa or more and 27 MPa or less, and even more preferably 15 MPa or more and 24 MPa or less.

[0099] As a result, in the second step, when embedding the release film 10 into the recess 223, the release film 10 exhibits better embedding properties, and the leakage of adhesive into the recess 223 can be more accurately suppressed or prevented. In addition, in the third step, the release film 10 can be peeled off more easily.

[0100] The storage modulus E' of the first release layer 1 at 180°C can be determined in accordance with JIS K7244-4 by preparing a first release layer 1 with a width of 4 mm and a length of 20 mm, and measuring it using a dynamic viscoelasticity measuring device (Hitachi High-Tech Science Corporation, "DMA7100") in tensile mode, with a frequency of 1 Hz and a heating rate of 5°C / min.

[0101] The average thickness T1 of the first release layer 1 is preferably 15 μm or more and 30 μm or less, and more preferably 20.0 μm or more and 28 μm or less. This makes the aforementioned effects even more pronounced.

[0102] Furthermore, as described above, if the surface of the first release layer 1 opposite the cushion layer 3 has an uneven shape, the thickness of the first release layer 1 shall be measured at the position including the convex portion and at the position including the concave portion.

[0103] If the first release layer 1 has an uneven surface, it is preferable that the 10-point average roughness (Rz) on the surface is 0.1 μm or more and 20.0 μm or less, and more preferably 1.0 μm or more and 10.0 μm or less. This makes it possible to improve the embedding properties of the release film 10. Furthermore, when releasing the release film 10 from the FPC 200 (flexible circuit board 210), this release can be performed with better release properties. The 10-point average roughness (Rz) can be measured in accordance with JIS B 0601-1994.

[0104] [3-3]Second release layer The release film 10 preferably has a second release layer 2 made of a second thermoplastic resin composition, which is laminated on the side of the cushion layer 3 opposite to the first release layer 1, as shown in Figure 4. The second release layer 2 constitutes the other surface of the release film 10 (the surface opposite to the surface formed by the outer surface of the first release layer 1).

[0105] As described above, by providing release layers on both sides of the cushion layer 3, the above-mentioned effects can be obtained, and it is also possible to more effectively prevent the release film 10 (release films 10A, 10B) from being unintentionally bonded to the glass cloth 300A, 300B, etc., by adhesive that has seeped out from the adhesive layer 222. Furthermore, the above-mentioned effects can also be obtained when, for example, the orientation of the release film 10 is changed during use.

[0106] The second release layer 2 is flexible and, in the manufacturing method of the flexible printed circuit board 200 using the release film 10 described above, the release film 10 is superimposed on the CL film 220 of the FPC 200 so that the first release layer 1 is in contact with it, and in the second step of this manufacturing method, when the superimposed flexible circuit board 210 and CL film 220 are joined via the adhesive layer 222, the second release layer 2 functions as a layer that transmits force from the heat-pressure plate 521 to the cushion layer 3. Furthermore, in the third step, the second release layer 2 functions as a contact layer to provide excellent release properties between the glass cloths 300A and 300B and the release film 10.

[0107] Furthermore, in the manufacturing method of the flexible printed circuit board 200, the second release layer 2 is in contact with the heat-pressing plate 521 via the glass cloths 300A and 300B. Therefore, in the second step of this manufacturing method, when the FPC 200 is heated and pressed, the second release layer 2 also has the function of transferring heat from the heat-pressing plate 521 to the cushion layer 3.

[0108] For the second release layer 2, it is preferable to satisfy the same conditions as in [3-2] above. This will yield the same effects as described above.

[0109] [3-4] Others The average thickness Tt of the release film 10 described above is preferably 120 μm or more and 180 μm or less, and more preferably 135 μm or more and 170 μm or less. This further enhances the aforementioned effects.

[0110] Furthermore, the release film 10 preferably has a storage modulus E' of 10 MPa or more and 25 MPa or less at 180°C, and more preferably 13 MPa or more and 22 MPa or less.

[0111] This makes it possible to improve the flexibility and conformability of the release film 10, and to improve the embedding ability of the release film 10.

[0112] The storage modulus E' of the release film 10 at 180°C can be determined in accordance with JIS K7244-4 by preparing a release film 10 with a width of 4 mm and a length of 20 mm, and measuring it using a dynamic viscoelasticity measuring device (Hitachi High-Tech Science Corporation, "DMA7100") in tensile mode, with a frequency of 1 Hz and a heating rate of 5°C / min.

[0113] The storage modulus E' of the release film 10 can be controlled, for example, by adjusting the thickness of the cushion layer 3. The thicker the cushion layer 3, the lower the storage modulus E' of the release film 10, and the more flexible it becomes.

[0114] Furthermore, the embedding properties of the release film 10 can be more favorably controlled by adjusting the raw materials contained in the release film 10.

[0115] Furthermore, the release film 10 may be subjected to surface treatment such as rubbing or annealing. By applying surface treatment to the release film 10, the embedding properties of the release film 10 can be more favorably controlled.

[0116] 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. However, it is not limited to this configuration, and may be composed of a laminate having an intermediate layer, such as an adhesive layer, disposed between the first release layer 1 and the cushion layer 3, and between the second release layer 2 and the cushion layer 3.

[0117] Furthermore, in the third step, if the release film 10 can maintain excellent release properties between the glass cloths 300A and 300B and the release film 10, the second release layer 2 that comes into contact with the glass cloths 300A and 300B may be omitted.

[0118] The methods for manufacturing the release film and molded articles of the present invention have been described above, but the present invention is not limited thereto.

[0119] For example, the present invention is intended to be applied when applying pressure to a flexible printed circuit board placed between heat-sealing plates using a roll-to-roll press. However, it is not limited to this, and the pressure applied to the flexible printed circuit board can also be carried out using, for example, a press molding method, or even a vacuum pressure forming method.

[0120] Furthermore, for example, the object to which the release film of the present invention is made contact may be any conductor with a thickness of 50 μm or more, and may be something other than a flexible printed circuit board. [Examples]

[0121] The present invention will be described in detail below based on examples, but the present invention is not limited thereto.

[0122] [4] Preparation of raw materials The following materials were prepared as raw materials for manufacturing the release film.

[0123] • Poly-4-methyl-1-pentene resin I (4-methyl-1-pentene, hexadecene, octadecene copolymer, manufactured by Mitsui Chemicals, "MX002O", MFR: 21g / 10min) (hereinafter referred to as "PMP1"). • Poly-4-methyl-1-pentene resin II (4-methyl-1-pentene-decene-1 copolymer, manufactured by Mitsui Chemicals, "RT31", MFR: 21g / 10min) (hereinafter referred to as "PMP2"). Low-density polyethylene (manufactured by Ube Maruzen Polyethylene Co., Ltd., "R300") (hereinafter referred to as "LDPE"). • Polypropylene (manufactured by Sumitomo Chemical Co., Ltd., "FH1016") (hereinafter referred to as "PP").

[0124] [5] Manufacturing of release film <Example 1> First, poly-4-methyl-1-pentene resin I was prepared as the first thermoplastic resin composition and the second thermoplastic resin composition, respectively. Furthermore, a third thermoplastic resin composition was prepared, consisting of 40 parts by weight of low-density polyethylene, 30 parts by weight of polypropylene, and 30 parts by weight of poly-4-methyl-1-pentene resin I.

[0125] Next, the first release layer was obtained by forming a film using the first thermoplastic resin composition by an extrusion T-die method.

[0126] Next, the first release layer was sequentially subjected to an extrusion T-die method using the third thermoplastic resin composition and the second thermoplastic resin composition to form films, thereby creating a laminate in which the cushion layer and the second release layer were laminated on the first release layer in that order.

[0127] The average thickness of the obtained release film was 150 μm. In the obtained release film, the average thickness of the first release layer was 27.5 μm, the average thickness of the cushion layer was 95 μm, and the average thickness of the second release layer was 27.5 μm. Therefore, the average thickness of the cushion layer relative to the average thickness of the release film was 63%.

[0128] Furthermore, the storage modulus E' of the obtained release film at 180°C was measured using a dynamic viscoelasticity measuring device (Hitachi High-Tech Science Corporation, "DMA7100") in tensile mode, with a frequency of 1 Hz and a heating rate of 5°C / min, and was found to be 19.7 MPa.

[0129] <Example 2, Comparative Examples 1-3> The release films for Example 2 and Comparative Examples 1-3 were manufactured in the same manner as in Example 1, except that various modifications were made to achieve the configuration shown in Table 1. In each of the above examples, the 10-point average surface roughness (Rz) was between 1.0 μm and 10.0 μm.

[0130] [Table 1]

[0131] [6] Rating The release films for each of the above examples and comparative examples were evaluated as follows.

[0132] As the roll-to-roll device, we used the RR Q-CURE 100TON CONTINUOUS LAMINATOR (manufactured by TRM, RtoR press machine). As shown in Figure 1, glass cloth, release film (width 270 mm), and a flexible printed circuit board (test piece) were unwound from the roll, overlapped between heat-pressure plates, and heat-pressed. Subsequently, the materials were transported from the exit of the heat-pressure plates towards the release rod, passing the release rod through to peel the release film from the flexible printed circuit board (test piece), and the following evaluation was performed.

[0133] [6-1] Embedding properties of release film 1 The release film used in each of the above examples and comparative examples was 270 mm wide. A copper flexible printed circuit board (manufactured by Nippon Steel Chemical & Material Co., Ltd., ESPANEX MC70-25-00VRM, wiring thickness 70 μm) with electrical wiring of 250 mm roll width and L / S ratio of 100 / 100 μm was prepared. Multiple 1 mm square openings were made in a coverlay (manufactured by Arisawa Seisakusho, CMA1050KA). Two of these coverlays were prepared, and test pieces were made by attaching the adhesive-coated side of the coverlay to both sides of the flexible printed circuit board and temporarily fixing them in place.

[0134] Next, the evaluation was performed using the RtoR press machine described above. During this process, the release film was positioned between the heated pressure plates such that the release surface of the first release layer faced the test piece on both sides of the test piece, and the glass cloth was positioned to sandwich the outer release film. Subsequently, the following conditions were met: temperature: 180°C, time: 140 sec, pressure: 110 kg / cm². 2 After hot pressing under the specified conditions, the product was conveyed in the direction of the release rod under the conditions of conveying speed: 60 mm / s, feed amount: 500 mm, and distance from the exit of the heated pressure plate to the release rod: 200 mm, to obtain a molded product.

[0135] For the molded products obtained in this manner, the maximum amount of adhesive coating on the surface of the coverlay that flowed out from the outer edge of the opening formed in the coverlay was observed using an optical microscope and evaluated according to the following criteria. A smaller maximum amount of leakage indicates better embedding performance.

[0136] [Evaluation Criteria] A: The maximum amount of leakage is less than 55 mm. B: The maximum amount of leakage is 55 mm or more but less than 65 mm. C: The maximum amount of leakage is 65 mm or more.

[0137] [6-2] Embedability of release film 2 The embedding performance was evaluated in the same manner as in the previous example, except that the flexible printed circuit board (ESPANEX MC70-25-00VRM, manufactured by Nippon Steel Chemical & Material Co., Ltd.) was replaced with copper foil (GTS-STD, 105 μm thick, manufactured by Furukawa Electric Co., Ltd.). The smaller the maximum amount of leakage, the better the embedding performance.

[0138] [Evaluation Criteria] A: The maximum amount of leakage is less than 65 mm. B: The maximum amount of leakage is 65 mm or more but less than 75 mm. C: The maximum amount of leakage is 75 mm or more.

[0139] [6-3] Release properties of release film Similarly to the above, the release films for each of the above examples and comparative examples were 270 mm wide. Then, using the same RtoR press machine as above, the ease of peeling the release film off with a release rod (release properties) was evaluated according to the following criteria.

[0140] [Evaluation Criteria] A: It can be peeled off when removing the release film. C: When peeling off the release film, it is difficult to remove due to fusion between the cushion layers or stretching and tearing of the release film. The evaluation results described above are summarized in Table 2.

[0141] [Table 2]

[0142] As shown in Table 2, excellent results were obtained in each of the above embodiments. In particular, Embodiment 2 showed superior embedding performance. On the other hand, satisfactory results were not obtained in any of the above comparative examples.

[0143] Furthermore, in the manufacturing of the release film, the release film was manufactured in the same manner as in the above-described examples, except that the average thickness of the first release layer was varied within the range of 15 μm to 30 μm. When these release films were evaluated in the same manner as described above, the same results as described above were obtained.

[0144] Furthermore, in the manufacturing of the release film, the release film was manufactured in the same manner as in the above examples, except that the average thickness of the cushion layer was varied within the range of 90 μm to 120 μm. When these release films were evaluated in the same manner as above, the same results as above were obtained.

[0145] Furthermore, in the manufacturing of the release film, the release film was manufactured in the same manner as in the above-described examples, except that the average thickness of the release film was varied within the range of 120 μm to 180 μm. When these release films were evaluated in the same manner as described above, the same results were obtained.

[0146] Furthermore, release films were manufactured in the same manner as in the above-described examples, except that various raw materials were changed so that the storage modulus E' of the release film was within the range of 10 MPa to 25 MPa. When these release films were evaluated in the same manner as described above, the same results were obtained. [Explanation of Symbols]

[0147] 1 First release layer 2 Second release layer 3. Cushioning layer 10 Release film 10A Release film 10B Release film 50 Heating press means 52 Heat-sealed section 60 Release means 100 Roll-to-Roll Press Machine 200 Flexible Printed Circuit Boards (FPCs) 210 Flexible Circuit Boards 211 Conductor 212 Base material 220 Coverlay Film (CL Film) 221 Coverlay 222 Adhesive layer 223 Recess 300A glass cloth 300B Glass Cloth 521 Heat-sealed crimping 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 used in contact with an object having a conductor with a thickness of 50 μm or more, The release film comprises a first release layer made of a first thermoplastic resin composition and a cushion layer laminated on the first release layer. The average thickness of the cushion layer is 60% or more and 80% or less of the average thickness of the release film. The storage modulus E' of the cushion layer at 180°C is 1 MPa or more and 20 MPa or less. The storage modulus E' of the first release layer at 180°C is 5 MPa or more and 30 MPa or less. The first thermoplastic resin composition comprises poly-4-methyl-1-pentene resin, The cushion layer is made of a third thermoplastic resin composition containing a polyolefin resin. The first release layer has an average thickness of 15 μm or more and 30 μm or less. The cushion layer has an average thickness of 90 μm or more and 120 μm or less. The aforementioned release film is a release film having an average thickness of 120 μm or more and 180 μm or less.

2. The release film according to claim 1, wherein the release film has a storage modulus E' of 10 MPa or more and 25 MPa or less at 180°C.

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

4. The release film according to claim 1 or 2, wherein the poly-4-methyl-1-pentene resin has a melt flow rate (MFR) of 5 g / 10 min or more and 21 g / 10 min or less, measured at 260°C and a 5.0 kg load.

5. The first release layer of the release film according to claim 1 or 2 is positioned on the object side, A method for manufacturing a molded product, comprising the steps of placing the release film on 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 side of the object on which the release film is placed is formed of a material containing a semi-cured thermosetting resin.

Images