Molded product manufacturing method

Abstract

To provide a method for producing a molded article capable of achieving both good releasability of a release film and suppression of the amount of oozing adhesive.SOLUTION: A release film 10 includes a release layer 1 constituting a release surface 11, and a cushion layer 3 laminated on the release layer 1. The thickness of the release layer 1 is 1-10 μm. The cushion layer 3 contains a substance having a melting point measured by differential scanning calorimetry (DSC) of 80°C or lower. The method for producing a molded article using the release film 10 comprises the steps of: arranging the release film 10 on an object so that the release surface 11 of the release film 10 is on the object side; and hot-pressing the object on which the release film 10 is arranged, at 140-155°C. In the step of arranging the release film 10, that surface of the object on which the release film 10 is arranged is formed of a material containing a thermosetting resin.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing a molded article. [Background technology]

[0002] Release films are generally used when producing molded products or laminates made by bonding different materials. For example, when producing a flexible printed circuit board (hereinafter also referred to as "FPC") by placing a coverlay film (hereinafter also referred to as "CL film") via an adhesive on the circuit surface of a flexible film with exposed circuits (hereinafter also referred to as "circuit-exposed film") and then heat-pressing, a release film is placed between the coverlay film and the heat-press plate.

[0003] During the heat press, the adhesive flows to fill in the minute irregularities on the circuit surface, thereby adhering the flexible film and the coverlay film together. If the conformability of the release film is insufficient, the adhesive may flow out without filling the minute irregularities.

[0004] For example, Patent Document 1 discloses a method for manufacturing a printed circuit board by bonding a circuit board and a coverlay film together using a release film and then hot pressing the laminate. It also discloses that the temperature during hot pressing is preferably 160°C to 200°C. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2020-167354 Summary of the Invention [Problem to be solved by the invention]

[0006] In recent years, circuit boards have become increasingly miniaturized, and the technical standards required for various properties of release films have become increasingly higher. The present inventors have focused on a new method of heat pressing at low temperatures in order to obtain good releasability while reducing the amount of adhesive seeping out, and have conducted extensive research into the development of a release film. As a result, they have discovered that while conventional release films are heated to high temperatures during heat pressing to obtain flexibility and exhibit effects such as embeddability and conformability, by using a new release film that includes a cushion layer made of a material with a low melting point, it is possible to maintain releasability while ensuring conformability at low temperatures and suppressing adhesive seepage, thereby obtaining good embeddability, and have completed the present invention. [Means for solving the problem]

[0007] According to the present invention, A method for manufacturing a molded product using a release film, The release film has a release layer that constitutes a release surface and a cushion layer laminated on the release layer, the release layer has a thickness of 1 to 10 μm, and the cushion layer contains a material having a melting point of 80° C. or less as measured by differential scanning calorimetry (DSC); placing the release film on the object so that the release surface of the release film faces the object; A step of hot pressing the object on which the release film is placed at 140 to 155 ° C.; Including, There is provided a method for manufacturing a molded product, wherein in the step of placing the release film, the surface of the object on which the release film is placed is formed from a material containing a thermosetting resin. [Effects of the Invention]

[0008] According to the present invention, a method for producing a molded article can be provided that can achieve both good releasability of the release film and suppression of the amount of adhesive seeping out. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 2 is a longitudinal cross-sectional view of the release film according to the present embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In all drawings, similar components are denoted by similar reference numerals, and their description will be omitted where appropriate. Furthermore, in this specification, the notation "a to b" in the description of a numerical range means a to b, unless otherwise specified. For example, "1 to 5 mass %" means "1 mass % to 5 mass %."

[0011] <Release film> FIG. 1 is a cross-sectional view of a release film according to this embodiment. 1, the release film 10 has a laminated structure in which a release layer 1, a cushion layer 3, and a release layer 2 are laminated in this order in the thickness direction. The release layer 1 is disposed on one side of the release film 10 and constitutes a release surface 11, and the release layer 2 is disposed on the other side of the release film 10 and constitutes a release surface 21. Although the example in which the release film 10 has release layers on both sides has been described with reference to FIG. 1, the release film is not limited to this.

[0012] In this embodiment, the release film 10 is placed so that the release layer 1 side is in contact with the object to be molded, which has circuits, etc. In other words, the surface that is in contact with the object to be molded is the release surface 11 of the release film 10, and the surface opposite to the surface that is in contact with the object to be molded is the release surface 21 of the release film 10.

[0013] Furthermore, the surface of the object to be molded before the release film 10 is placed is usually made of a material containing a thermosetting resin in a semi-cured state. The release film 10 is used by being placed on the surface of an object to be molded that is formed from a material containing the semi-cured thermosetting resin. Then, with the release film 10 placed on the surface of the object to be molded, a desired molded product can be obtained by performing a heat press. Examples of the object according to this embodiment include a coverlay film, a copper-clad laminate, etc. Examples of the thermosetting resin include an epoxy resin, an acrylic resin, a polyester resin, and a polyimide resin.

[0014] [Elastic modulus, etc.] In this embodiment, the release film 10 preferably has a storage modulus at 150°C measured with a dynamic viscoelasticity measuring device (tensile mode, frequency 1 Hz, temperature rise rate 5°C / min) of 30 MPa or more and 70 MPa or less, and more preferably 40 MPa or more and 60 MPa or less. By setting the storage modulus at 150°C to the above lower limit or more, good hardness and rigidity can be obtained throughout the release film even when low-temperature hot pressing is performed using the release film 10, thereby improving the releasability. In addition, a molded product with good appearance can be obtained. On the other hand, by setting the storage modulus at 150°C to the above upper limit or less, embeddability can be easily obtained while maintaining good releasability when performing low-temperature hot pressing using the release film 10. In addition, good appearance of the molded product can be maintained.

[0015] In this embodiment, the release film 10 preferably has a loss modulus at 150°C measured with a dynamic viscoelasticity measuring device (tensile mode, frequency 1 Hz, temperature rise rate 5°C / min) of 4 MPa or more and 20 MPa or less, more preferably 5 MPa or more and 15 MPa or less. By setting the loss modulus at 150°C to be equal to or greater than the lower limit, even when low-temperature hot pressing is performed using the release film 10, good viscosity is obtained throughout the release film, resulting in embeddability while maintaining releasability. On the other hand, by making the loss modulus at 150°C equal to or less than the upper limit, good embedding properties during hot pressing can be maintained while mold releasability can be easily obtained.

[0016] In this embodiment, the release film 10 preferably has a tan δ at 150°C measured with a dynamic viscoelasticity measuring device (tensile mode, frequency 1 Hz, temperature rise rate 5°C / min) of 0.05 or more and 0.3 or less, more preferably 0.1 or more and 0.2 or less. By setting the tan δ at 150°C to be equal to or greater than the above lower limit, even when low-temperature hot pressing is performed using the release film 10, appropriate viscoelasticity is obtained throughout the release film, thereby improving the balance between releasability and embeddability.

[0017] The storage modulus and loss modulus of the release film 10 of this embodiment can be adjusted by known methods, for example, by controlling the overall thickness of the release film 10, the thicknesses of the release layer 1 and the cushion layer 3, the combination of materials constituting the release layer 1 and the cushion layer 3, etc.

[0018] Thickness The overall thickness of the release film 10 is preferably 50 μm or more and 250 μm or less, more preferably 80 μm or more and 200 μm or less, and even more preferably 100 μm or more and 160 μm or less, which makes it possible to apply a press pressure to the release film 10 evenly and without unevenness when producing a molded product.

[0019] [Surface roughness] The ten-point average roughness Rz of the release surface 11 of the release film 10 is preferably 2 μm or more and 20 μm or less, more preferably 3 μm or more and 10 μm or less, and even more preferably 8 μm or less. By setting the ten-point average roughness Rz to the above lower limit or more, the releasability can be improved. On the other hand, by setting the ten-point average roughness Rz to the above upper limit or less, the followability can be maintained well. Furthermore, when the amount of inorganic particles is increased to increase the Rz, the strength of the release film 10 tends to decrease. Therefore, by setting the amount to the above upper limit or less, the balance between the strength and releasability of the release film can be improved.

[0020] The arithmetic mean roughness Ra of the release surface 11 of the release film 10 is preferably 0.1 μm or more and 5 μm or less, more preferably 0.2 μm or more and 2 μm or less, and even more preferably 1 μm or less. By setting the arithmetic mean roughness Ra to the above lower limit or more, good releasability can be stably obtained. On the other hand, by setting the arithmetic mean roughness Ra to the above upper limit or less, appropriate conformability can be maintained well. Furthermore, when the amount of inorganic particles is increased to increase the RRa, the strength of the release film 10 tends to decrease. Therefore, by setting the amount to the above upper limit or less, the balance between the strength and releasability of the release film can be improved.

[0021] The average spacing Sm of the irregularities on the release surface 11 of the release film 10 is preferably 200 μm or more and 800 μm or less, more preferably 300 μm or more and 700 μm or less, and even more preferably 600 μm or less. By setting the average spacing Sm of the irregularities to be equal to or greater than the above lower limit, it is possible to improve the releasability of the entire release surface 11. On the other hand, by setting the average spacing Sm of the irregularities to be equal to or less than the above upper limit, it is possible to maintain good conformability of the entire release surface 11.

[0022] The surface roughness of the release surface 11 can be measured in accordance with JIS B 0601 (1994).

[0023] The surface roughness of the release surface 11 of the release film 10 can be adjusted by controlling the thicknesses of the release film 10 and the release layer 1, the manufacturing method of the release film 10, the particle size of the particles contained in the release layer 1 described below, the particle content, etc. That is, for example, if the particle size is larger than the thickness of the release layer 1, the unevenness caused by the particles tends to be more pronounced on the release surface 11 of the release film 10, and also, if the particle content is large, the unevenness caused by the particles tends to be more pronounced on the release surface 11 of the release film 10.

[0024] Each layer will be described in detail below.

[0025] Release layer 1 (first release layer) The release layer 1 is a layer that forms the surface (release surface 11) that comes into contact with the object to be molded when hot pressing is performed using the release film .

[0026] The release layer 1 is formed using a thermoplastic resin composition. Examples of thermoplastic resins include polyalkylene terephthalate resins such as polyethylene terephthalate resin (PET), polybutylene terephthalate resin (PBT), polytrimethylene terephthalate resin (PTT), and polyhexamethylene terephthalate resin (PHT); poly-4-methyl-1-pentene resin (TPX (registered trademark): hereinafter also referred to as polymethylpentene resin); syndiotactic polystyrene resin (SPS); polypropylene resin (PP); and copolymer resins copolymerized with other components. These may be used alone or in combination of two or more. Among these, from the viewpoint of improving the release properties of the release layer 1, it is preferable to use one or more selected from the group consisting of polymethylpentene resin, polybutylene terephthalate resin, syndiotactic polystyrene resin, and polypropylene resin. From the viewpoint of maintaining rigidity and obtaining good release properties even when the thickness of the release layer 1 is thin, polymethylpentene resin is more preferable.

[0027] The thermoplastic resin composition of the release layer 1 may contain, in addition to the above-mentioned thermoplastic resin, additives such as antioxidants, slip agents, antiblocking agents, antistatic agents, colorants such as dyes and pigments, stabilizers, impact resistance agents such as fluororesins and silicone rubber, and inorganic fillers such as titanium oxide, calcium carbonate, and talc.

[0028] In this embodiment, the release layer 1 may contain particles, which provides releasability and appropriate strength, and also prevents wrinkles and bubbles from forming in the release film 10, resulting in a good appearance. The average particle size d50 of the particles is preferably 3 μm or more, more preferably 5 μm or more, and even more preferably 8 μm or more, while the average particle size d50 of the particles is preferably 35 μm or less, more preferably 25 μm or less, and even more preferably 18 μm or less. By setting the average particle size d50 of the particles to the above lower limit or more, it is possible to improve the rigidity of the release film 10 and also improve the releasability from a surface-roughened FPC. On the other hand, by setting the average particle size d50 of the particles to the above upper limit or less, it is possible to achieve a good balance between releasability and conformability, and to produce a molded product with a good finished appearance.

[0029] From the viewpoint of improving the rigidity of the release film 10, the particles are preferably inorganic particles. Examples of inorganic particles include particles made of one or more of the following: silica (e.g., crystalline silica, amorphous silica, and fused silica), aluminum hydroxide, magnesium hydroxide, calcium carbonate, magnesium carbonate, calcium silicate, magnesium silicate, calcium oxide, magnesium oxide, zinc oxide, alumina, aluminum nitride, aluminum borate whisker, boron nitride, antimony oxide, E-glass, D-glass, S-glass, and zeolite. One type of inorganic particle may be used alone, or different types of particles may be used in combination. The inorganic particles may be surface-treated with a silane coupling agent or the like to improve adhesion to resins, or core-shell particles may be used, in which inorganic particles are treated with an organic coating to improve dispersibility. From the viewpoint of improving the rigidity of the release film, silica such as crystalline silica, amorphous silica, and fused silica is preferred, and spherical fused silica is more preferred.

[0030] The content of particles in the total amount of the release layer 1 is preferably 0.1% by mass to 30% by mass, more preferably 1% by mass to 20% by mass, and even more preferably 5% by mass to 15% by mass. By making the particle content of the release layer 1 equal to or greater than the above-mentioned lower limit, it becomes easier to obtain good release properties. On the other hand, by making the particle content of the release layer 1 equal to or less than the above-mentioned upper limit, it is possible to ensure appropriate strength of the release film 10, maintain good release properties, and reduce costs.

[0031] The thickness of the release layer 1 is 1 to 10 μm, and from the viewpoint of obtaining a suitable strength, it is preferably 2 μm or more, more preferably 3 μm or more, and particularly preferably 4 μm or more. On the other hand, from the viewpoint of ensuring releasability and improving embeddability in a molded product, the thickness of the release layer 1 is preferably 9 μm or less, more preferably 8 μm or less. Furthermore, by making the thickness of the release layer 1 equal to or greater than the above-mentioned lower limit, it becomes easier to obtain good release properties, while by making the thickness of the release layer 1 equal to or less than the above-mentioned upper limit, it becomes easier to obtain good embeddability and conformability, and costs can be reduced.

[0032] The thickness (μm) of the release layer 1 is 15% or less, preferably 12% or less, and more preferably 10% or less, of the total thickness (μm) of the release film 10. This facilitates heat transfer to the cushion layer 3 described below, facilitates rapid conformability by the cushion layer 3, and highly suppresses adhesive outflow. On the other hand, the thickness (μm) of the release layer 1 is preferably 4% or more, more preferably 5% or more, of the total thickness of the release film 10. This allows the release film 10 to maintain good releasability.

[0033] ·Release layer 2 The release layer 2 is a layer that forms the surface (release surface 21) that comes into contact with the press hot plate when hot pressing is performed using the release film 10.

[0034] The release layer 2 is formed using a thermoplastic resin composition. The thermoplastic resin used in release layer 2 can be the same as that described above for release layer 1. The thermoplastic resins used in release layer 1 and release layer 2 may be the same or different. Furthermore, release layer 2 may be formed using the same material as release layer 1, or a different material.

[0035] In this embodiment, the release layer 2 may contain particles. The average particle size d50 of the particles is preferably 3 μm or more, more preferably 5 μm or more, and even more preferably 8 μm or more. On the other hand, the average particle size d50 of the particles is preferably 35 μm or less, more preferably 25 μm or less, and even more preferably 18 μm or less. By setting the average particle size d50 of the particles to the above lower limit or more, it is possible to improve the rigidity of the release film 10 and also improve the releasability from the hot plate during hot pressing. On the other hand, by setting the average particle size d50 of the particles to the above upper limit or less, it is possible to achieve a good balance between releasability and conformability, and to produce a molded product with a good finished appearance.

[0036] The content of particles in the total amount of the release layer 2 is preferably 0.1% by mass to 30% by mass, more preferably 1% by mass to 20% by mass, and even more preferably 5% by mass to 15% by mass. By setting the particle content of the release layer 2 to above the above lower limit, it becomes easier to obtain good release properties from the hot plate during heat pressing. On the other hand, by setting the particle content of the release layer 2 to below the above upper limit, it is possible to reduce costs while maintaining good release properties.

[0037] The particles contained in release layer 2 can be the same as the particles contained in release layer 1. The particles contained in release layer 1 and the particles contained in release layer 2 may be made of the same material or have the same particle size, or may be made of different materials or have different particle sizes.

[0038] From the viewpoint of obtaining a suitable strength, the thickness of the release layer 2 is preferably 10 μm or more, more preferably 15 μm or more. On the other hand, from the viewpoint of improving embeddability in a molded product, the thickness of the release layer 2 is preferably 60 μm or less, more preferably 50 μm or less.

[0039] Cushion layer 3 The cushion layer 3 is an intermediate layer interposed between the release layer 1 and the release layer 2. The cushion layer 3 imparts good conformability and also provides the entire release film 10 with appropriate stiffness.

[0040] The cushion layer 3 contains at least an ethylene copolymer having a melting point of 80°C or less as measured by differential scanning calorimetry (DSC). This allows the release film 10 to quickly conform to and be pressed against the circuit-exposing film, even when low-temperature heat pressing is performed using the release film 10. As a result, the release film 10 is pressed against the circuit-exposing film before the adhesive placed between the release film 10 and the circuit-exposing film flows and spreads due to the heat pressing, thereby preventing the adhesive from flowing out.

[0041] Examples of the ethylene copolymer include one or more selected from ethylene-vinyl acetate copolymer (EVA), ethylene-vinyl alcohol copolymer (EVOH), ethylene-methyl methacrylate copolymer (EMMA), ethylene-ethyl acrylate copolymer (EEA), ethylene-methyl acrylate copolymer (EMA), ethylene-ethyl acrylate-maleic anhydride copolymer (E-EA-MAH), ethylene-acrylate copolymer (EAA), ethylene-methacrylic acid copolymer (EMAA), ethylene cycloolefin copolymer (COC), and ionomer resin (ION). These may be used alone or in combination.

[0042] The cushion layer 3 may also contain a resin other than the above-mentioned ethylene-based copolymer. In this case, the content of the ethylene-based copolymer relative to the total amount of the cushion layer 3 is preferably 40% by mass or more and 80% by mass or less, and more preferably 50% by mass or more and 70% by mass or less. By setting the content of the ethylene-based copolymer to the above-mentioned lower limit or more, even when low-temperature heat pressing is performed using the release film 10, the release film 10 can quickly follow the circuit-exposing film, and the outflow of the adhesive can be suppressed. On the other hand, by setting the content of the ethylene copolymer to the above upper limit or less, the cushion layer 3 itself is prevented from flowing out during hot pressing, and an appropriate strength can be maintained.

[0043] Examples of resins other than the above-mentioned ethylene copolymers include α-olefin polymers such as polyethylene and polypropylene, α-olefin copolymers having propylene, butene, pentene, hexene, methylpentene, etc. as polymer components, engineering plastic resins such as polyethersulfone (PES) and polyphenylene sulfide (PPS), polymethylpentene resins, etc. These may be used alone or in combination of two or more. Among these, it is preferable that the cushion layer 3 contains polypropylene or polymethylpentene resin, from the viewpoint of imparting appropriate strength and elasticity to the cushion layer 3 and maintaining good releasability.

[0044] Examples of mixtures that may be used to form the cushion layer 3 include a mixture of ethylene and ethylene-methyl methacrylate copolymer (EMMA), a mixture of polypropylene (PP) and ethylene-methyl methacrylate copolymer (EMMA), a mixture of polybutylene terephthalate (PBT), polypropylene (PP) and ethylene-methyl methacrylate copolymer (EMMA), a mixture of polypropylene (PP), ethylene-methyl acrylate copolymer (EMA) and polymethylpentene resin, and a mixture of polypropylene (PP), ethylene-methacrylic acid copolymer (EMAA) and polymethylpentene resin. Among these, from the viewpoint of imparting appropriate strength and elasticity to the cushion layer 3 and maintaining good releasability, a mixture containing at least polypropylene, poly-4-methyl-1-pentene resin, or polybutylene terephthalate (PBT) is preferred.

[0045] The cushion layer 3 may further contain a rubber component. Examples of the rubber component include thermoplastic elastomer materials such as styrene-based thermoplastic elastomers such as styrene-butadiene copolymer and styrene-isoprene copolymer, olefin-based thermoplastic elastomers, amide-based elastomers, and polyester-based elastomers, as well as rubber materials such as natural rubber, isoprene rubber, chloroprene rubber, and silicone rubber.

[0046] The cushion layer 3 may contain additives such as antioxidants, slip agents, antiblocking agents, antistatic agents, colorants such as dyes and pigments, stabilizers, impact resistance agents such as fluororesins and silicone rubber, and inorganic fillers such as titanium oxide, calcium carbonate, and talc.

[0047] The thickness (μm) of the cushion layer 3 is preferably 3 to 10 times, and more preferably 5 to 9 times, the thickness (μm) of the release layer 1. By setting the thickness of the cushion layer 3 to be equal to or greater than the above lower limit, good cushioning properties of the release film 10 can be quickly obtained, the adhesive can be prevented from flowing out, and the conformability can be improved. On the other hand, by setting the thickness of the cushion layer 3 to be equal to or less than the above upper limit, good releasability can be maintained and the cushion layer 3 itself can be prevented from flowing out due to hot pressing.

[0048] The thickness of the cushion layer 3 is preferably 30 μm or more and 180 μm or less, more preferably 50 μm or more and 140 μm or less, even more preferably 65 μm or more and 120 μm or less, and particularly preferably 70 μm or more and 115 μm or less. By setting the thickness of the cushion layer 3 to be equal to or greater than the above lower limit, the cushioning properties of the release film 10 can be quickly obtained, the adhesive can be prevented from flowing out, and the followability can be improved. On the other hand, by setting the thickness of the cushion layer 3 to be equal to or less than the above upper limit, the releasability can be maintained at a good level.

[0049] Examples of methods for forming the cushion layer 3 include known methods such as air-cooled or water-cooled inflation extrusion and T-die extrusion.

[0050] <Method of manufacturing the release film 10> The release film 10 can be produced using known methods such as coextrusion, extrusion lamination, dry lamination, and inflation. The release film 10 may be produced by separately producing the release layer 1, the cushion layer 3, and the release layer 2 and then bonding them together using a laminator or the like. However, it is preferable to form the film by an air-cooled or water-cooled coextrusion inflation method or a coextrusion T-die method. Of these, the coextrusion T-die method is particularly preferable because it provides excellent control over the thickness of each layer. The release layer 1, the cushion layer 3, and the release layer 2 may be bonded together directly or via an adhesive layer.

[0051] <Molded product manufacturing method> Next, a method for manufacturing the molded product of this embodiment will be described. The method for manufacturing a molded product of this embodiment uses the release film 10, A step (step 1) of placing a release film 10 on an object so that the release surface 11 of the release film 19 faces the object; and a step (step 2) of performing heat pressing at 140 to 155°C on the object on which the release film 10 is placed, In step 1 of placing the release film 10, the surface of the object on which the release film 10 is to be placed is made of a material containing a thermosetting resin.

[0052] Furthermore, after step 1 of placing release film 10, a step (step 3) of placing a material on the release surface of the second release layer of release film 10 (the release surface of release layer 2) may be further included.

[0053] In this embodiment, the heat pressing temperature in step 2 is 140 to 155° C. This allows the release film 10 to maintain its releasability even when pressed at a low temperature, while providing good embedding properties and making it possible to obtain a molded product with a good appearance. The heat press temperature refers to the temperature set for the heat press hot plate that is placed on the object on which the release film 10 is placed.

[0054] Furthermore, a known method can be used for step 1. For example, a molded product may be produced by conveying the release film 10 using a roll-to-roll method. In the roll-to-roll method, the release film 10 is unwound from a roll and conveyed between an object and a heat-press plate, and then heat-pressed to form a molded product. The film is then peeled off and rewound onto the roll. In this case, the angle at which the release film 10 is peeled off from the molded product tends to be low. Therefore, a greater force is applied to the release film 10, and therefore higher releasability is required. In contrast, in the present embodiment, the release film 10 is used for heat pressing at 140 to 155°C, thereby exhibiting higher releasability. Even when using the roll-to-roll method, the balance between releasability and embeddability can be improved, and a molded product with a good appearance can be obtained.

[0055] An example of using the method for manufacturing a molded product of this embodiment when manufacturing a flexible printed circuit board will be described. In this case, the release film 10 is used by being interposed between the coverlay and the press when the coverlay film is heated and pressed to adhere to the circuit formed on the flexible film in order to protect the circuit. Specifically, the release film 10 is used, for example, in a coverlay press lamination process, which is one of the manufacturing processes for flexible printed wiring boards. More specifically, the release film 10 is arranged to encase the coverlay film so that the coverlay film adheres closely to the uneven portions of the circuit pattern when the coverlay film is bonded to the circuit-exposed film, and is heated and pressed together with the circuit-exposed film and the coverlay film by a press. As the coverlay film, for example, a film in which an adhesive is applied to one side of a polyimide film and a separator is attached to protect the adhesive surface is used. At this time, in order to improve cushioning properties, materials such as paper, rubber, a fluororesin sheet, glass paper, or a combination of these may be inserted between the release film 10 and the press, and then heated and pressed.

[0056] The release film 10 of this embodiment may also be used in the following manner to produce the above-mentioned molded article. First, the release surface 11 of the release layer 1 of the release film 10 according to the present embodiment is placed on the surface of an object formed of a material containing a thermosetting resin. Next, paper, rubber, a fluororesin sheet, glass paper, or a combination of these materials is placed on the release surface 21 of the release layer 2 of the release film 10. Thereafter, the object on which the release film 10 is placed is subjected to a press process in a mold. Here, the thermosetting resin may be in a semi-cured state or a cured state, but if it is in a semi-cured state, the effect of the release film 10 becomes even more pronounced. In particular, when the thermosetting resin is a resin composition containing an epoxy resin, it is preferable that the epoxy resin is in an intermediate stage of the curing reaction, i.e., in a B-stage state.

[0057] Although the embodiments of the present invention have been described above, these are merely examples of the present invention, and various other configurations can also be adopted.

[0058] In this embodiment, the release film 10 has been described as having a laminated structure in which the release layer 1, the cushion layer 3, and the release layer 2 are laminated in this order in the thickness direction, but is not limited to this. For example, the release film may have a structure of four or more layers, such as four or five layers, including an adhesive layer, a gas barrier layer, etc. In this case, the adhesive layer and the gas barrier layer are not particularly limited, and known layers can be used. Below, examples of reference forms are added. 1. A method for manufacturing a molded product using a release film, The release film has a release layer that constitutes a release surface and a cushion layer laminated on the release layer, the release layer has a thickness of 1 to 10 μm, and the cushion layer contains a material having a melting point of 80° C. or less as measured by differential scanning calorimetry (DSC); placing the release film on the object so that the release surface of the release film faces the object; A step of hot pressing the object on which the release film is placed at 140 to 155 ° C.; Including, A method for manufacturing a molded product, wherein in the step of placing the release film, the surface of the object on which the release film is placed is formed from a material containing a thermosetting resin. 2. A method for producing the molded product described in 1., A method for producing a molded product, wherein the release film has a storage modulus at 150°C measured using a dynamic viscoelasticity measuring device (tensile mode, frequency 1 Hz, temperature rise rate 5°C / min) of 30 MPa or more and 70 MPa or less. 3. A method for producing a molded product according to 1. or 2., A method for producing a molded product, wherein the release film has a loss modulus at 150°C measured using a dynamic viscoelasticity measuring device (tensile mode, frequency 1 Hz, temperature rise rate 5°C / min) of 4 MPa or more and 20 MPa or less. 4. A method for producing a molded product according to any one of 1. to 3., The release film has a tan δ of 0.05 or more and 0.3 or less at 150°C as measured with a dynamic viscoelasticity measuring device (tensile mode, frequency 1 Hz, temperature rise rate 5°C / min). 5. A method for producing a molded product according to any one of 1. to 4., The method for producing a molded product, wherein the release surface has a surface roughness Rz of 2 μm to 20 μm. 6. A method for producing a molded product according to any one of 1. to 5., A method for producing a molded product, wherein the release layer is made of a thermoplastic resin composition containing one or more resins selected from polyester resin, poly-4-methyl-1-pentene resin, polyamide resin, and polypropylene resin. 7. A method for producing a molded product according to any one of 1. to 6., A method for producing a molded product, wherein the cushion layer is made of a resin composition for a cushion layer, which contains one or more resins selected from an ethylene copolymer, an α-olefin polymer, an α-olefin copolymer, an engineering plastic resin, and a polymethylpentene resin. 8. A method for producing a molded product according to any one of 1. to 7., In the step of placing the release film, the release film is transported by a roll-to-roll method. 9. A method for producing a molded product according to any one of 1. to 8., The method for manufacturing a molded article, wherein the molded article is a flexible circuit board. [Example]

[0059] EXAMPLES The present invention will be described below with reference to examples and comparative examples, but the present invention is not limited to these.

[0060] <Material> The following materials were used for the release film. (Release layer) TPX: Polymethylpentene resin "DX231", manufactured by Mitsui Chemicals PBT: Polybutylene terephthalate "1100-630S", manufactured by Chang Chun Petrochemical Co., Ltd. Fused silica: spherical, average particle size d50 is 11.7 μm, "SC10-32F", manufactured by Nippon Steel & Sumikin Materials Co., Ltd. (Cushion layer) Modified polyethylene resin: Ethylene-methyl acrylate copolymer (EMA) resin, "EB140F", manufactured by Japan Polyethylene Co., Ltd., melting point 73°C Polypropylene resin: "E111G", manufactured by Prime Polymer, melting point 160°C TPX: Polymethylpentene resin "RT31", manufactured by Mitsui Chemicals, melting point 232°C

[0061] Example 1 1) Preparation of release film As the thermoplastic resin composition for forming the first release layer, 90 parts by weight of TPX and 10 parts by weight of fused silica were used. For the cushion layer, a resin composition containing 60 parts by weight of modified polyethylene resin, 20 parts by weight of polypropylene resin, and 20 parts by weight of TPX was used. The thermoplastic resin composition used to form the second release layer (sub-release layer) was the same as that used to form the first release layer. Using each material, a first release layer, a cushion layer, and a second release layer were laminated in that order in the thickness direction using the extrusion T-die method, and each layer was molded to have the thickness (μm) shown in Table 1 to obtain a release film. The resulting release film was used so as to be placed on the polyimide film side of the coverlay. 2) Production of molded products Next, a test specimen was prepared by temporarily attaching a coverlay (CM type coverlay manufactured by Arisawa Manufacturing Co., Ltd.) with an opening to the surface of an insulating substrate (FPC) with 100 / 100 μm L / S electrical wiring so that the adhesive-coated surface was in contact with the surface using a release film. The release film was then pressed and attached to the test specimen using a roll-to-roll press under conditions of 150°C, 11 MPa, and 150 seconds, and immediately after pressing, the test specimen and the release film were peeled off while being transported at 200 mm / s, yielding a molded product.

[0062] <Example 2> A release film was obtained in the same manner as in Example 1, except that PBT was used instead of TPX for the release layer and cushion layer. Using the obtained release film, a molded article was obtained in the same manner as in Example 1.

[0063] Example 3 In the same manner as in Example 1, a release film was obtained. Using the obtained release film, a molded article was obtained in the same manner as in Example 1, except that the heat press temperature was changed to 140°C.

[0064] Example 4 A release film was obtained in the same manner as in Example 1, except that the thickness of the cushion layer was changed to the thickness (μm) shown in Table 1. Using the obtained release film, a molded article was obtained in the same manner as in Example 1.

[0065] <Comparative Example 1> In the same manner as in Example 1, a release film was obtained. Using the obtained release film, a molded article was obtained in the same manner as in Example 1, except that the heat press temperature was changed to 160°C.

[0066] <Comparative Example 2> In the same manner as in Example 1, a release film was obtained. Using the obtained release film, a molded article was obtained in the same manner as in Example 1, except that the heat press temperature was changed to 130°C.

[0067] <Comparative Example 3> A release film was obtained in the same manner as in Example 1, except that EMA (EB140F) was changed to LDPE (R500, manufactured by Ube Maruzen Polyethylene) for the cushion layer. Using the obtained release film, a molded article was obtained in the same manner as in Example 1.

[0068] <Comparative Example 4> A release film was obtained in the same manner as in Example 1, except that the thickness of the release layer was changed to the thickness (μm) shown in Table 1. Using the obtained release film, a molded article was obtained in the same manner as in Example 1.

[0069] The release films and molded articles obtained in the examples and comparative examples were subjected to the following measurements and evaluations. The results are shown in Table 1.

[0070] <Measurement> Measurement of melting point by differential scanning calorimetry (DSC): The temperature of the endothermic peak in the DSC curve obtained using a DSC (differential scanning calorimeter, SII DSC6220) was taken as the melting point.

[0071] Average particle size d50 of particles (fused silica): Using a laser diffraction particle size analyzer (Malvern, Mastersizer 2000), particles were dispersed in water as the solvent and the particle size was measured. From the results, the particle size value at which the cumulative frequency was 50% was calculated as the average particle size d50. The unit is μm.

[0072] Surface roughness of the release surface of the first release layer: Rz, Ra, and Sm were measured in accordance with JIS B 0601 (1994), with units of μm.

[0073] Storage modulus, loss modulus, Tanδ: A release film molded to a width of 4 mm and a length of 20 mm in the MD direction was measured using a dynamic viscoelasticity measuring device in tensile mode at a frequency of 1 Hz and a heating rate of 5°C / min, and the storage modulus (MPa), loss modulus (MPa), and Tan δ at 150°C were determined.

[0074] <Evaluation> Embeddability (adhesive seepage): First, a 1 mm square opening was created in a coverlay (CEAM0515) manufactured by Arisawa Manufacturing Co., Ltd. Next, a test specimen was prepared by temporarily attaching the coverlay with the opening to the surface of a copper-clad laminate for flexible wiring boards so that the adhesive-coated side was in contact with the surface. Next, the release film and the test specimen were overlapped so that the first release surface of the first release layer of the release film faced the coverlay-containing side of the test specimen. Then, a heat press treatment was performed under vacuum conditions of 150°C, 2 MPa, vacuuming for 20 seconds, and 2 minutes to obtain a molded product. The molded product thus obtained was observed for the shape of the adhesive coated on the surface of the cover tape oozing out from the outer edge of the opening (adhesive oozing shape) into the opening formed in the coverlay, and the embeddability was evaluated based on the following criteria. ◯: The difference in unevenness of the adhesive seeping out shape was less than 40 μm. ×: The difference in unevenness of the adhesive seeping out shape was 40 μm or more.

[0075] Releasability (releasability of the release surface 11 of the first release layer): A test specimen was prepared by temporarily attaching a coverlay having an opening to the surface of an insulating substrate (FPC) on which electrical wiring with an L / S of 100 / 100 μm was formed, so that the adhesive-coated surface was in contact with the surface. Next, the release film and the test specimen were overlapped so that the first release surface of the first release layer of the release film faced the coverlay-containing surface of the test specimen. After that, a heat press treatment was performed under vacuum conditions at 150°C, 2 MPa, and vacuuming for 20 seconds and 2 minutes to obtain a molded product. Using a tensile tester (Force gauge AD-4932A-50N manufactured by A&D Corporation), the peel force between the release surface and the sample was measured in a 180° direction at a speed of approximately 1000 mm / min. The measurement was carried out immediately after pressing, and the releasability was evaluated based on the following criteria. The evaluation results are shown in Table 1. ◎: 0.5N or less ○: Over 0.5N and less than 1.0N ×: 1.0N or more

[0076] FPC appearance (wrinkles in molded product): Regarding the appearance of the FPC, the wrinkle occurrence rate per unit area was measured according to the method in accordance with the JPCA standard "7.5.7.2 Wrinkles." The obtained measurements were evaluated according to the following criteria. ◎: Wrinkle occurrence rate less than 1.0% ○: Wrinkle occurrence rate 1.0% or more, less than 2.0% ×: Wrinkle occurrence rate 2.0% or more

[0077] [Table 1] [Explanation of symbols]

[0078] 10 Release film 1 First release layer 2 Second release layer 3 Cushion layer 11 Release surface 21 Release surface

Claims

1. A method for manufacturing a molded product using a release film, comprising: The release film has a release layer that constitutes a release surface and a cushion layer laminated on the release layer, the release layer has a thickness of 1 to 10 μm, and the cushion layer contains a material having a melting point of 80° C. or less as measured by differential scanning calorimetry (DSC); placing the release film on the object so that the release surface of the release film faces the object; A step of performing a heat press at 140 to 155 ° C. on the object on which the release film is placed; Including, In the step of placing the release film, a surface of the object on which the release film is placed is formed of a material containing a thermosetting resin, The release film has a storage modulus of 30 MPa or more and 70 MPa or less at 150°C as measured with a dynamic viscoelasticity measuring device (tensile mode, frequency 1 Hz, temperature rise rate 5°C / min).

2. A method for manufacturing a molded product using a release film, comprising: The release film has a release layer that constitutes a release surface and a cushion layer laminated on the release layer, the release layer has a thickness of 1 to 10 μm, and the cushion layer contains a material having a melting point of 80° C. or less as measured by differential scanning calorimetry (DSC); placing the release film on the object so that the release surface of the release film faces the object; A step of performing a heat press at 140 to 155 ° C. on the object on which the release film is placed; Including, In the step of placing the release film, a surface of the object on which the release film is placed is formed of a material containing a thermosetting resin, The release film has a loss modulus of 4 MPa or more and 20 MPa or less at 150°C measured with a dynamic viscoelasticity measuring device (tensile mode, frequency 1 Hz, temperature rise rate 5°C / min).

3. A method for manufacturing a molded product using a release film, comprising: The release film has a release layer that constitutes a release surface and a cushion layer laminated on the release layer, the release layer has a thickness of 1 to 10 μm, and the cushion layer contains a material having a melting point of 80° C. or less as measured by differential scanning calorimetry (DSC); placing the release film on the object so that the release surface of the release film faces the object; A step of performing a heat press at 140 to 155 ° C. on the object on which the release film is placed; Including, In the step of placing the release film, a surface of the object on which the release film is placed is formed of a material containing a thermosetting resin, The method for producing a molded product, wherein the release film has a tan δ at 150°C measured with a dynamic viscoelasticity measuring device (tensile mode, frequency 1 Hz, temperature rise rate 5°C / min) of 0.05 or more and 0.3 or less.

4. A method for manufacturing a molded product according to claim 2 or 3, comprising: The release film has a storage modulus of 30 MPa or more and 70 MPa or less at 150°C as measured with a dynamic viscoelasticity measuring device (tensile mode, frequency 1 Hz, temperature rise rate 5°C / min).

5. A method for manufacturing a molded product according to claim 1 or 3, comprising: The release film has a loss modulus of 4 MPa or more and 20 MPa or less at 150°C measured with a dynamic viscoelasticity measuring device (tensile mode, frequency 1 Hz, temperature rise rate 5°C / min).

6. A method for manufacturing a molded product according to claim 1 or 2, comprising: The method for producing a molded product, wherein the release film has a tan δ at 150°C measured with a dynamic viscoelasticity measuring device (tensile mode, frequency 1 Hz, temperature rise rate 5°C / min) of 0.05 or more and 0.3 or less.

7. A method for manufacturing a molded product according to any one of claims 1 to 6, The method for producing a molded product, wherein the surface roughness Rz of the release surface is 2 μm to 20 μm.

8. A method for manufacturing a molded product according to any one of claims 1 to 7, The method for producing a molded article, wherein the release layer is made of a thermoplastic resin composition containing one or more resins selected from polyester resin, poly(4-methyl-1-pentene) resin, and polypropylene resin.

9. A method for manufacturing a molded product according to any one of claims 1 to 8, comprising: The cushion layer is made of a resin composition for a cushion layer, the resin composition including one or more resins selected from an ethylene copolymer, an α-olefin polymer, an α-olefin copolymer, an engineering plastic resin, and a polymethylpentene resin.

10. A method for manufacturing a molded product according to any one of claims 1 to 9, In the step of placing the release film, the release film is transported by a roll-to-roll method.

11. A method for manufacturing a molded product according to any one of claims 1 to 10, The method for manufacturing a molded article, wherein the molded article is a flexible circuit board.

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