Method for manufacturing release film and molded product

Abstract

To provide a release film that has excellent release and embedding properties even when heated and pressed at relatively low temperatures, and a method for manufacturing molded products using such a release film. [Solution] The release film of the present invention is a release film used for heat pressing at 156°C to 165°C, and comprises a first release layer made of a first thermoplastic resin composition and a cushion layer made of a third thermoplastic resin composition laminated on the first release layer, wherein the average thickness of the cushion layer is 30% to 80% of the average thickness of the release film, and the third thermoplastic resin composition includes a low-melting-point resin whose melting point by differential scanning calorimetry (DSC) is 140°C or less. Furthermore, it is preferable that the release film has a storage modulus E' of 15 MPa to 55 MPa at 160°C.

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 in the coverlay film, a release film is generally used.

[0003] Such release films have been required to have two characteristics, namely, excellent embedding property and releasability.

[0004] 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 property with respect to these recesses.

[0005] More specifically, the adhesion of the coverlay film to the flexible circuit board is performed through the adhesive layer provided in the coverlay film. During this adhesion, it is required that the release film exhibits excellent embedding property with respect to the recesses and suppresses the bleeding of the adhesive within the recesses.

[0006] Also, after the adhesion of the coverlay film to the flexible circuit board, it is required that the release film be peeled off from the formed flexible printed circuit board with excellent releasability.

[0007] More specifically, when peeling the release film from the flexible printed circuit board, it is required that the release film exhibits excellent releasability with respect to the flexible printed circuit board and suppresses the occurrence of folding wrinkles and breakage in the flexible printed circuit board.

[0008] Furthermore, while the temperature during heat pressing is usually 180°C or higher, pressing may be performed at lower temperatures, for example, to suppress the seepage of adhesive. Therefore, there is a need for release films that can exhibit excellent release and embedding properties even during heat pressing at low temperatures. [Prior art documents] [Patent Documents]

[0009] [Patent Document 1] Patent No. 6470461 [Overview of the project] [Problems that the invention aims to solve]

[0010] The object of the present invention is to provide a release film that has excellent release and embedding properties even when heated and pressed at relatively low temperatures, and a method for manufacturing molded products using such a release film. [Means for solving the problem]

[0011] The purpose of this is as follows (1) ~ (4) This is achieved by the present invention as described above.

[0012] (1) A release film used for heat pressing at temperatures between 156°C and 165°C, The release film comprises a first release layer made of a first thermoplastic resin composition and a cushion layer made of a third thermoplastic resin composition laminated on the first release layer. The average thickness of the cushion layer is 30% to 80% of the average thickness of the release film. The third thermoplastic resin composition contains a low-melting-point resin whose melting point is 140°C or lower, as determined by differential scanning calorimetry (DSC). fruit, The storage modulus E' of the cushion layer at 160°C is between 1 MPa and 40 MPa. The storage modulus E' of the first release layer at 160°C is between 10 MPa and 60 MPa. The first thermoplastic resin composition comprises poly-4-methyl-1-pentene resin, The low-melting-point resin includes a polyolefin resin. The polyolefin resin is at least one selected from the group consisting of α-olefin polymers, ethylene-α-olefin copolymers, ethylene-(meth)acrylic acid copolymers, ethylene-(meth)acrylic acid ester copolymers, and ethylene-vinyl acetate copolymers. The third thermoplastic resin composition includes a high-melting-point resin having a melting point of 200°C or higher as determined by differential scanning calorimetry (DSC). The first release layer has an average thickness of 10 μm or more and 60 μm or less. The cushion layer has an average thickness of 20 μm or more and 140 μm or less. The aforementioned release film has an average thickness of 40 μm or more and 180 μm or less. Release film.

[0013] (2) The release film according to (1) above, wherein the storage elastic modulus E' at 160 °C is 15 MPa or more and 55 MPa or less.

[0014] (3) The release film according to (1) or (2) above, which has 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.

[0021] (4) The above (1) or (3) A method for manufacturing a molded product, comprising: arranging the release film on the object such that the first release layer of the release film according to the above (1) or is on the object side; and performing a heat press on the object on which the release film is arranged. In the step of arranging the release film, the surface of the object on which the release film is to be arranged is formed of a material containing a semi-cured thermosetting resin. [Advantages of the Invention]

[0022] According to the present invention, it is possible to provide a release film having excellent releasability and embedability even in a heat press at a relatively low temperature, and a method for manufacturing a molded product using such a release film. [Brief Description of the Drawings]

[0023] [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]Figure 1 is a longitudinal cross-sectional view showing each step in the manufacturing method of a flexible printed circuit board using a roll-to-roll press machine. [Figure 3] Figure 1 is a longitudinal cross-sectional view showing the heating and pressing process in a manufacturing method for a flexible printed circuit board using a roll-to-roll press machine. [Figure 4] This is a longitudinal cross-sectional view showing an embodiment of the release film of the present invention. [Modes for carrying out the invention]

[0024] Preferred embodiments of the present invention will be described in detail below. In the following, the manufacturing of 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. Furthermore, before describing the manufacturing method of the release film and molded product of the present invention, the roll-to-roll press used in the manufacturing of this flexible printed circuit board will first be described.

[0025] [1] Roll-to-roll press Figure 1 is a side view showing the main part of a roll-to-roll press machine used in the manufacture of flexible printed circuit boards. Figure 2 is a longitudinal cross-sectional view showing each step in the manufacturing method of flexible printed circuit boards using the roll-to-roll press machine shown in Figure 1. Figure 3 is a longitudinal cross-sectional view showing the heating press step in the manufacturing method of flexible printed circuit boards using the roll-to-roll press machine shown in Figure 1. For the sake of explanation, in the following, the upper side in Figures 1 to 3 will be referred to as "up" or "upper," the lower side as "down" or "downward," the left side as "left," and the right side as "right."

[0026] 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. Aluminum is used for the circuit portion of the flexible circuit board 210.

[0027] 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.

[0028] 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.

[0029] 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.

[0030] 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.

[0031] 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.

[0032] 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.

[0033] 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 peeled from the release film 10.

[0034] [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 of the FPC200 using this roll-to-roll press machine will be described below.

[0035] The method for manufacturing the FPC200 in this embodiment is the method for manufacturing a molded product of the present invention. Specifically, 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 at a temperature of 156°C to 165°C. 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.

[0036] More specifically, the manufacturing method of the FPC200 in this embodiment, as shown in Figures 1 to 3, comprises a first step (a step of arranging the release film) 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 (a step of performing a heat press) of bonding the coverlay 221 (CL film 220) to the flexible circuit board 210 in the FPC200 via an adhesive layer 222 by heating and pressing the laminate; and a third step of peeling off 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.

[0037] The following explains each of these steps in order. [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)).

[0038] 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.

[0039] 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.

[0040] [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).

[0041] 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.

[0042] In this second step (heating and pressing step), the temperature at which the FPC200 is heated is 156°C or higher and 165°C or lower, but is preferably 158°C or higher and 163°C or lower, and more preferably 160°C or higher and 162°C or lower.

[0043] This more effectively suppresses the seepage of adhesive from the adhesive layer 222 within the recess 223. Furthermore, it is possible to improve the release properties of the release film 10 in the third step described later. In addition, by pressing at a relatively low temperature, more energy is saved during pressing, and the time required for cooling after heating and pressing is shortened, thereby improving productivity.

[0044] 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.

[0045] Furthermore, the transport speed for transporting the laminate is preferably 10 mm / sec to 400 mm / sec, and more preferably 30 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 300.0 sec, and more preferably 4.0 sec to 200.0 sec.

[0046] By keeping the adhesion time within the aforementioned range, the adhesive layer 222 can be cured more favorably even if the temperature at which the FPC 200 is heated is relatively low, as described above.

[0047] 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.

[0048] 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.

[0049] [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)).

[0050] 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.

[0051] 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.

[0052] 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.

[0053] 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.

[0054] 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.

[0055] 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.

[0056] [3] Release film The release film 10 of the present invention is a release film used for heat pressing at temperatures between 156°C and 165°C. It comprises a first release layer 1 made of a first thermoplastic resin composition and a cushion layer 3 made of a third thermoplastic resin composition laminated on the first release layer 1, wherein the average thickness of the cushion layer 3 is 30% to 80% of the average thickness of the release film 10, and the third thermoplastic resin composition includes a low-melting-point resin whose melting point by differential scanning calorimetry (DSC) is 140°C or lower.

[0057] By heating the FPC200 at a temperature between 156°C and 165°C, the seepage of adhesive originating from the adhesive layer 222 within the recesses 223 is effectively suppressed. Furthermore, after bonding the coverlay film 220 to the flexible circuit board 210, the release film 10 can be peeled off the flexible printed circuit board 200 with excellent release properties.

[0058] Furthermore, the release film 10 of the present invention, having the above-described structure, can exhibit excellent release properties and embedding properties.

[0059] More specifically, for example, when bonding the coverlay film 220 to the 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.

[0060] Furthermore, for example, after the coverlay film 220 is bonded to the flexible circuit board 210, the release film 10 can be peeled off the formed flexible printed circuit board 200 with excellent release properties. As a result, it is possible to effectively prevent any part of the release film 10 from remaining on the flexible printed circuit board 200 (for example, on the coverlay film 220 on the flexible circuit board 210).

[0061] 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.

[0062] 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.

[0063] Furthermore, if the average thickness of the cushion layer 3 is less than 30% 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.

[0064] 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.

[0065] Furthermore, if the third thermoplastic resin composition does not contain a low-melting-point resin whose melting point is 140°C or lower according to differential scanning calorimetry (DSC), the cushion layer 3 cannot exhibit excellent embedding properties at the heating press temperature of 156°C to 165°C. Therefore, the release film 10 cannot be made to have excellent embedding properties.

[0066] The average thickness of the cushion layer 3 is 30% to 80% of the average thickness of the release film 10, but is preferably 40% to 70%, and more preferably 45% to 65%. This makes the aforementioned effects more pronounced.

[0067] The low-melting-point resin contained in the third thermoplastic resin composition has a melting point of 140°C or lower, determined by differential scanning calorimetry (DSC), but is preferably 138°C or lower, more preferably 135°C or lower, and even more preferably 132°C or lower. This makes the aforementioned effects more pronounced.

[0068] The melting point obtained by differential scanning calorimetry (DSC) can be determined, for example, as the temperature of the endothermic peak in the DSC curve obtained using a differential scanning calorimeter. While there are no particular limitations on the differential scanning calorimeter, for example, the DSC6220 manufactured by SII can be used.

[0069] 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.

[0070] 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.

[0071] 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.

[0072] This cushion layer 3 is made of a third thermoplastic resin composition. Because the cushion layer 3 contains a thermoplastic resin, the release film 10 can exhibit good embedding properties in the recesses 223.

[0073] Furthermore, the third thermoplastic resin composition of the cushion layer 3 includes a low-melting-point resin whose melting point, determined by differential scanning calorimetry (DSC), is 140°C or lower. This allows the cushion layer 3 to exhibit excellent embedding properties even at relatively low temperatures during heating and pressing, thereby improving the embedding properties of the release film 10.

[0074] The low-melting-point resin is not particularly limited, but it is preferable to include a polyolefin resin. This makes it possible to improve the embedding properties of the release film 10.

[0075] Polyolefin resins are not particularly limited and include, 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 with 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.

[0076] In particular, the low-melting-point resin preferably contains polypropylene resin. This makes it easier to improve the cushioning properties of the cushion layer 3 and improve its ability to conform to the recesses 223.

[0077] Furthermore, it is preferable that the polypropylene resin includes random polypropylene resin. This allows for a lower melting point as determined by differential scanning calorimetry (DSC), making it easier to further improve the cushioning properties of the cushion layer 3. Thus, the conformability to the recesses 223 can be further improved.

[0078] Furthermore, it is preferable that the third thermoplastic resin composition includes a high-melting-point resin whose melting point, determined by differential scanning calorimetry (DSC), is 200°C or higher. This allows for a better balance between the cushioning and release properties of the cushion layer 3.

[0079] Examples of high-melting-point resins include polyester resins, polyamide resins, and polyolefin resins.

[0080] Examples of polyester resins used as high-melting-point 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.

[0081] Among these, polybutylene terephthalate-based resins (polybutylene terephthalate or copolymers containing polybutylene terephthalate) are preferred. This allows the aforementioned effects to be exhibited more significantly.

[0082] In particular, if 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), the adhesion between the cushion layer 3 and the release layer can be improved.

[0083] Furthermore, it is preferable that the polyolefin resin used as the high-melting-point resin includes poly-4-methyl-1-pentene resin. This allows the aforementioned effects to be exhibited more significantly.

[0084] 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 polyolefin resin (for example, poly-4-methyl-1-pentene resin, etc.), the adhesion between the cushion layer 3 and the release layer can be made even better.

[0085] The high-melting-point resin contained in the third thermoplastic resin composition preferably has a melting point of 200°C or higher, more preferably 205°C or higher, and even more preferably 210°C or higher, as determined by differential scanning calorimetry (DSC). This makes the aforementioned effects more pronounced.

[0086] In the third thermoplastic resin composition, the content of the low-melting-point resin per 100 parts by mass of the third thermoplastic resin composition is preferably 10 parts by mass or more and 90 parts by mass or less, and more preferably 30 parts by mass or more and 70 parts by mass or less. This allows the aforementioned effects to be exhibited more significantly.

[0087] 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.

[0088] 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.

[0089] 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.

[0090] The storage modulus E' of the cushion layer 3 at 160°C is preferably 1 MPa or more and 40 MPa or less, more preferably 2 MPa or more and 30 MPa or less, and even more preferably 5 MPa or more and 15 MPa or less.

[0091] 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.

[0092] The storage modulus E' of the cushion layer 3 at 160°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.

[0093] The average thickness Tk of the cushion layer 3 is preferably 20 μm or more and 140 μm or less, more preferably 25 μm or more and 135 μm or less, and even more preferably 30 μm or more and 130 μm or less.

[0094] 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.

[0095] [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.

[0096] 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).

[0097] 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.

[0098] 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.

[0099] 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.

[0100] 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.

[0101] 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.

[0102] Furthermore, the first release layer 1 may also contain at least one of inorganic particles and organic particles in addition to the thermoplastic resin.

[0103] 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.

[0104] 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.

[0105] 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.

[0106] 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.

[0107] 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.

[0108] 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.

[0109] The storage modulus E' of the first release layer 1 at 160°C is preferably 10 MPa or more and 60 MPa or less, more preferably 30 MPa or more and 55 MPa or less, and even more preferably 40 MPa or more and 50 MPa or less.

[0110] 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.

[0111] The storage modulus E' of the first release layer 1 at 160°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.

[0112] The average thickness T1 of the first release layer 1 is preferably 10.0 μm or more and 60.0 μm or less, and more preferably 20.0 μm or more and 40.0 μm or less. This makes the aforementioned effects even more pronounced.

[0113] 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.

[0114] 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, 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.

[0115] [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).

[0116] 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.

[0117] 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 (release films 10A and 10B).

[0118] 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.

[0119] 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.

[0120] [3-4] Others The average thickness Tt of the release film 10 described above is preferably 40 μm or more and 180 μm or less, and more preferably 45 μm or more and 170 μm or less. This further enhances the aforementioned effects.

[0121] Furthermore, the release film 10 preferably has a storage modulus E' of 15 MPa or more and 55 MPa or less at 160°C, and more preferably 20 MPa or more and 50 MPa or less.

[0122] This makes it possible to improve the flexibility and conformability of the release film 10, and to improve the embedding and release properties of the release film 10.

[0123] The storage modulus E' of the release film 10 at 160°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.

[0124] 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.

[0125] Furthermore, by adjusting the raw materials contained in the release film 10, the embedding and release properties of the release film 10 can be more effectively controlled.

[0126] 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 and release properties of the release film 10 can be more effectively controlled.

[0127] In this embodiment, the release film 10 is composed of a laminate in which a first release layer 1, a cushion layer 3, and a second release layer 2 are laminated in this order. 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.

[0128] 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.

[0129] 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.

[0130] 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. [Examples]

[0131] The present invention will be described in detail below based on examples, but the present invention is not limited thereto.

[0132] [4] Preparation of raw materials The following materials were prepared as raw materials for manufacturing the release film. The melting point was defined as the temperature of the endothermic peak in the DSC curve obtained using a DSC (Differential Scanning Calorimeter, SII DSC6220).

[0133] • Poly-4-methyl-1-pentene resin I (4-methyl-1-pentene, hexadecene, octadecene copolymer, manufactured by Mitsui Chemicals, "MX002O", melting point: 224°C) (hereinafter referred to as "PMP1"). • Poly-4-methyl-1-pentene resin II (4-methyl-1-pentene-decene-1 copolymer, manufactured by Mitsui Chemicals, "RT31", melting point: 232°C) (hereinafter referred to as "PMP2"). Low-density polyethylene (manufactured by Ube Maruzen Polyethylene Co., Ltd., "R300", melting point: 109°C) (hereinafter referred to as "LDPE"). Random polypropylene (manufactured by Sumitomo Chemical Co., Ltd., "S131", melting point: 132°C) (hereinafter referred to as "PP1"). • Polypropylene (manufactured by Sumitomo Chemical Co., Ltd., "FH1016", melting point: 163℃) (hereinafter referred to as "PP2").

[0134] [5] Manufacturing of release film <Example 1> First, a first thermoplastic resin composition and a second thermoplastic resin composition were prepared, each consisting of 50 parts by mass of poly-4-methyl-1-pentene resin I and 50 parts by mass of poly-4-methyl-1-pentene resin II. A third thermoplastic resin composition was also prepared, consisting of 20 parts by mass of low-density polyethylene, 30 parts by mass of random polypropylene, and 50 parts by mass of poly-4-methyl-1-pentene resin II.

[0135] Next, the first release layer was obtained by forming a film using the first thermoplastic resin composition by an extrusion T-die method.

[0136] 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, and each was formed into a film. This created a laminate in which the cushion layer and the second release layer were laminated in this order on the first release layer, thereby obtaining the release film of Example 1.

[0137] The average thickness of the obtained release film was 120 μm. In the obtained release film, the average thickness of the first release layer was 14 μm, the average thickness of the cushion layer was 92 μm, and the average thickness of the second release layer was 14 μm. Therefore, the average thickness of the cushion layer (ratio of the cushion layer) to the average thickness of the release film was 77%.

[0138] Furthermore, the storage modulus E' of the obtained release film at 160°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 18.0 MPa.

[0139] <Examples 2-8, Comparative Examples 1-6> Release films for Examples 2-8 and Comparative Examples 1-6 were manufactured in the same manner as in Example 1, except for various modifications 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.

[0140] [Table 1]

[0141] [6] Rating The release films for each of the above examples and comparative examples were evaluated as follows.

[0142] 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.

[0143] [6-1] Embedability of release film The release film used in each of the above examples and comparative examples was 270 mm wide. A copper flexible printed circuit board (ESPANEX MB18-25-18CEG, manufactured by Nippon Steel Chemical & Material Co., Ltd.) 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 (CMA1050KA, manufactured by Arisawa Seisakusho). 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.

[0144] Next, 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 specimen on both sides of the specimen. Furthermore, the glass cloth was positioned so as to sandwich the outer release film. Subsequently, the following conditions were met: temperature: 160°C, time: 150 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.

[0145] 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.

[0146] [Evaluation Criteria] A: The maximum amount of leakage is less than 50 mm. B: The maximum amount of leakage is 50 mm or more but less than 100 mm. C: The maximum amount of leakage is 100 mm or more.

[0147] [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.

[0148] [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.

[0149] [Table 2]

[0150] As shown in Table 2, excellent results were obtained in each of the above examples. In particular, Example 2 showed superior release properties and embedding properties. On the other hand, satisfactory results were not obtained in any of the above comparative examples.

[0151] 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 cushion layer was varied within the range of 20 μm to 140 μm. When these release films were evaluated in the same manner as described above, the same results as described above were obtained.

[0152] 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 40 μm to 180 μm. When these release films were evaluated in the same manner as described above, the same results were obtained.

[0153] Furthermore, release films were manufactured in the same manner as in the above examples, except that various raw materials were changed so that the storage modulus E' of the release film at 160°C was within the range of 15 MPa to 55 MPa. When these release films were evaluated in the same manner as above, the same results as above were obtained. [Explanation of symbols]

[0154] 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 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 for heat pressing at temperatures between 156°C and 165°C, The release film comprises a first release layer made of a first thermoplastic resin composition and a cushion layer made of a third thermoplastic resin composition laminated on the first release layer. The average thickness of the cushion layer is 30% to 80% of the average thickness of the release film. The third thermoplastic resin composition includes a low-melting-point resin having a melting point of 140°C or lower as determined by differential scanning calorimetry (DSC). The storage modulus E' of the cushion layer at 160°C is 1 MPa or more and 40 MPa or less. The storage modulus E' of the first release layer at 160°C is 10 MPa or more and 60 MPa or less. The first thermoplastic resin composition comprises poly-4-methyl-1-pentene resin, The low-melting-point resin includes a polyolefin resin. The polyolefin resin is at least one selected from the group consisting of α-olefin polymers, ethylene-α-olefin copolymers, ethylene-(meth)acrylic acid copolymers, ethylene-(meth)acrylic acid ester copolymers, and ethylene-vinyl acetate copolymers. The third thermoplastic resin composition includes a high-melting-point resin having a melting point of 200°C or higher as determined by differential scanning calorimetry (DSC). The first release layer has an average thickness of 10 μm or more and 60 μm or less. The cushion layer has an average thickness of 20 μm or more and 140 μm or less. The aforementioned release film is a release film having an average thickness of 40 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 15 MPa or more and 55 MPa or less at 160°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 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 at a temperature of 156°C to 165°C, 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.

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