TWI414554B - A film and a release film - Google Patents

Abstract

A film that has a layer of specified 4-methyl-1-pentene copolymer and has a specified thickness buildup and thermal shrinkage coefficient. There is provided a film excelling in heat resistance and mold release properties, especially a film suitable for use as a mold release film applied in producing of a laminate according to pressure molding. When this film is used as a mold release film in the heating and pressurization steps for manufacturing of flexible printed boards, there can be prevented sticking of coverlay to metal sheet and outflow of adhesive leading to sticking to other members. Moreover, there can be avoided generation of voids in non-printed portions on the board, and contamination of exposed portions, such as terminal portions, of electric circuit by melting outflow of adhesive. Still further, wrinkling of the mold release film can be avoided, so that generation of voids due to follow failure of the mold release film can be avoided and that thus flexible printed boards with good appearance can be obtained.

Description

Film and release film

The present invention relates to a film which is excellent in heat resistance and release property of a layer formed of a 4-methyl-1-pentene-based copolymer, and a laminate which is formed into a film or a sheet by press molding. A release film suitable for use in the case of a material. More specifically, a circuit is formed by adhering a cover layer of a protective layer to a flexible printed circuit board (hereinafter also referred to as "FPC") by heating and pressurizing with an adhesive (hereinafter also referred to as "FPC"). A release film suitable for use on the surface of copper foil).

When a plurality of raw material films or sheets are held by a metal plate or the like, and a laminate is formed by press molding, in order to prevent adhesion between a metal plate or the like and the obtained laminate, a release film is generally used. Moreover, since heating is often accompanied by press molding, high heat resistance and excellent release property are required for the release film.

The release film is a release film for manufacturing a flexible printed circuit board (hereinafter also referred to as "FPC"), a release film for ACM materials used for aircraft parts, a release film for producing a rigid printed circuit board, and a semiconductor seal. A release film for a material, a release film for FRP molding, a release film for curing a rubber sheet, and a release film for a special adhesive tape.

In FPC, the substrate on which the circuit is formed and the cover layer are usually adhered by a thermosetting adhesive. In the case where only a circuit is formed on one side of the substrate, the cover layer adheres only to one side of the substrate on which the circuit is formed; in the case where two or more layers of the substrate are provided with circuits, the cover layer is adhered to both sides of the substrate. on. Further, at the time of the adhesion, the substrate and the coating layer coated with the thermosetting adhesive are usually held in a metal plate to be heated and pressurized. Then, in order to prevent adhesion between the cover layer and the metal plate, the FPC manufacturing release film is held between the metal plate and the cover layer.

Conventionally, as a release film for FPC production, a film of a polytetrafluoroethylene, a tetrafluoroethylene-hexafluoropropylene copolymer, and a fluorine-based polymer such as polyvinyl fluoride; a film of polymethylpentene; Wait.

On the surface on which the circuit of the FPC is formed, the printed portion on which the circuit is formed differs from the height of the non-printed portion in which the circuit is not formed. Therefore, when coating with a film-like cover layer, voids are formed in the non-printing portion, and the residual air enclosed in the gap oxidizes the circuit, which causes a problem that the life of the circuit is remarkably lowered.

In the FPC, in order to electrically connect with other parts, a terminal portion of the circuit is formed, and the terminal portion is exposed without being covered by the cover layer. Further, in order to coat the portion other than the terminal portion and apply the adhesive to the coating layer, it is melted when it is adhered by heating and pressurization, and often flows out to the terminal portion of the circuit to form a coating layer of the adhesive. However, it becomes a cause of poor electrical connection. Further, since the conventional cover layer has a large coefficient of thermal expansion with respect to the substrate, the cover layer, and the metal plate, wrinkles are formed on the surface of the release film when it is heated and pressed to adhere the cover layer. Therefore, in the wrinkle-forming portion, there is a problem that a gap occurs between the circuit and the release film due to the tracking failure of the release film, and further, the wrinkle is transferred to the FPC, and the wrinkle cannot be obtained. The appearance of the FPC problem.

Patent Document 1 and Patent Document 2 disclose a release film for the purpose of solving the above problems. However, in the step of heating and pressurizing the release film on the circuit for adhering the cover layer to the surface of the substrate, the effect of preventing wrinkles on the film is not necessarily sufficient, and there is no possibility of obtaining a satisfactory appearance. FPC problem.

Patent Document 1: Japanese Patent Laid-Open No. Hei 2-175247. Patent Document 2: Japanese Patent Laid-Open No. 2003-211602

The invention provides a film suitable for a release film, in particular, a heating and pressing step suitable for manufacturing an FPC, which prevents the adhesion of the cover layer and the metal plate, and the adhesive flows out and adheres to other parts. The printed portion does not form a void, and the exposed portion of the terminal portion of the circuit is not contaminated by the melt flow of the adhesive, and the film of the release film which does not cause wrinkles is formed.

The inventors of the present invention have intensively studied to solve the above problems, and as a result, have found that a film comprising a layer formed of a specific 4-methyl-1-pentene-based copolymer and having a specific thickness and a heat shrinkage ratio can To solve the above problems, the present invention has been completed.

That is, the present invention provides the following: [1] A film having at least one layer (A) formed of a 4-methyl-1-pentene copolymer, the 4-methyl group The 1-pentene-based copolymerization system has a constituent unit derived from 4-methyl-1-pentene of from 95.5 mass% to 99.5% by mass and from 0.5% by mass to 4.5% by mass of 4-methyl-1-pentene. The constituent unit of the olefin having 3 to 20 carbon atoms; the overall thickness of the layer (A) is 40 μm to 90 μm; and the thermal contraction rate of the entire film is 1% to 5%.

[2] The film according to the above [1], which is a single layer film of the above layer (A).

[3] The film according to the above [1], which comprises a plurality of layers, in addition to the above layer (A), further having a layer formed of a soft polyolefin having a domain softening temperature of 50 ° C to 150 ° C according to ASTM D1525. (B), and at least one of the above layers (A) is the outermost layer.

[4] The film according to the above [1], comprising a plurality of layers having a layer (B) formed of a soft polyolefin having a domain softening temperature of 50 ° C to 150 ° C according to ASTM D1525, and at least two layers of the above Layer (A); and the two layers of the above layer (A) are the outermost layers on both sides of the film.

[5] The film according to any one of the above [1] to [3] wherein the olefin having 3 to 20 carbon atoms other than 4-methyl-1-pentene is selected from the group consisting of 1-octene, 1 At least one of terpene, 1-tetradecene and 1-octadecene.

[6] The film of the above [3] or [4] wherein the soft polyolefin is one or more olefins selected from the group consisting of ethylene, propylene, butene, pentene, hexene, and methylpentene (total a polymer obtained by polymerization.

[7] The film according to the above [3] or [4] wherein the soft polyolefin is selected from the group consisting of a copolymer of ethylene and acrylate, a copolymer of ethylene and methacrylate, a copolymer of ethylene and acrylic acid, and ethylene. a copolymer of a copolymer of methacrylic acid and a portion of its ionic crosslinks.

[8] The film according to any one of [3] to [7] wherein the thickness of the layer (A) is 25% to 80% of the entire thickness of the film.

[9] The film according to any one of [2] to [8] wherein at least one of the surfaces of the film formed by the layer (A) is embossed.

[10] The film according to any one of the above [1] to [9], which is obtained by an extrusion molding method or a coextrusion molding method.

[11] A release film obtained by the film according to any one of the above [1] to [10].

The film containing a layer formed of a specific 4-methyl-1-pentene copolymer, having a specific thickness and a heat shrinkage ratio, is excellent in heat resistance and release property, and is therefore suitable for use as a separation. Type film. In particular, since the FPC is used as a release film, it is possible to prevent the adhesion between the metal plate and the cover layer when the substrate and the cover layer are heated and pressurized, and the adhesive flows out and adheres to other parts. At the time of molding, no void is formed in the non-printing portion, and the exposed portion of the terminal portion of the circuit is not contaminated by the melted and discharged of the adhesive.

Further, when the coating layer is adhered by heat and pressure, no wrinkles are formed in the release film, so that voids are not formed due to the tracking failure, and the FPC having improved appearance defects due to wrinkle transfer can be efficiently obtained. Formed, and extremely valuable in industry.

Further, the layer containing the specific soft polyolefin imparts a good cushioning property for causing the release film to follow the unevenness of the surface of the substrate on which the circuit is formed, and the overflow during heating and pressurization is less, so that it does not adhere to it. The substrate surface of the circuit and the metal plate used for heating and pressurization have problems such as a decrease in the yield of the FPC product and a decrease in workability.

The film of the present invention has at least one layer (A) composed of a 4-methyl-1-pentene copolymer, and the layer (A) has an overall thickness of 40 μm to 90 μm, and the overall heat shrinkage rate of the film. It is 1% to 5%.

[4-methyl-1-pentene copolymer]

The 4-methyl-1-pentene copolymer used in the present invention means a constituent unit derived from 4-methyl-1-pentene and having a mass ratio of from 0.55% by mass to 4.55% by mass, and from 0.5% by mass to 4.5% by mass. A crystalline copolymer of a constituent unit derived from an olefin having 3 to 20 carbon atoms other than 4-methyl-1-pentene. Preferably, the constituent unit derived from 4-methyl-1-pentene is 96% by mass to 99% by mass, and the constituent unit of the olefin having 3 to 20 carbon atoms other than 4-methyl-1-pentene is 1 % by mass to 4% by mass; more preferably, the constituent unit derived from 4-methyl-1-pentene is 97% by mass to 98% by mass, and the number of carbon atoms other than 4-methyl-1-pentene is 3 to 20%. The constituent unit of the olefin is 2% by mass to 3% by mass.

When the film of the present invention is used as a release film in the production of FPC, if the constituent unit of the olefin having 3 to 20 carbon atoms other than 4-methyl-1-pentene is at most the above upper limit value, When the wrinkle of the release film is prevented, the cushioning property of the release film is good, and the release film can be deformed following the irregularities caused by the printed portion and the non-printed portion of the circuit surface.

The olefin having 3 to 20 carbon atoms other than 4-methyl-1-pentene used in the present invention may, for example, be selected from the group consisting of propylene, 1-butene, 1-hexene, 1-octene, and 1-oxime. At least one olefin of an alkene, 1-tetradecene and 1-octadecene. Among these, from the viewpoint of good copolymerizability with 4-methyl-1-pentene and good toughness, 1-decene, 1-tetradecene and 1-octadecene are preferred.

In the 4-methyl-1-pentene copolymer used in the present invention, the melt flow rate according to ASTM D1238 (temperature: 260 ° C, weight: 5.0 kg) is from 0.5 g/10 min to 200 g/10 min, preferably 5g/10 points ~ 100g/10 points, more preferably 10g/10 points ~ 50g / l0 points. When the melt flow rate is 200 g/10 minutes or less, sufficient mechanical strength can be obtained. On the other hand, when the melt flow rate is 0.5 g/10 minutes or more, good moldability can be obtained, which is preferable.

The melting point (Tm) of the 4-methyl-1-pentene copolymer used in the present invention measured by DSC is preferably in the range of from 220 ° C to 240 ° C, more preferably in the range of from 225 ° C to 240 ° C. Further, the domain softening temperature measured according to ASTM D1525 is preferably in the range of 160 ° C to 200 ° C, more preferably in the range of 170 ° C to 200 ° C.

The 4-methyl-1-pentene copolymer used in the present invention can be produced by a known method, and the polymerization catalyst and the polymerization method are also not particularly limited.

Examples of the catalyst include a Ziegler type catalyst (according to a combination of a halogen-containing titanium compound and an aluminum compound), a Phillips type catalyst (based on a chromium oxide-supporting person), and a card. Minsky type catalyst (according to the combination of a supported or unsupported metallocene type compound with an organoaluminum compound, especially with alumoxane).

The polymerization method may, for example, be a slurry polymerization method, a vapor phase fluidized bed polymerization method, a solution polymerization method in the presence of the above catalyst, or a high pressure bulk polymerization method having a pressure of 20 MPa or more and a polymerization temperature of 100 ° C or higher.

More specifically, in the presence of a catalyst, 4-methyl group can be used as described in JP-A-59-206418, JP-A-61-113604, and JP-A-2003-105022. 1-pentene is copolymerized with an olefin having 3 to 20 carbon atoms other than the above, and a 4-methyl-1-pentene copolymer which is used in the present invention is obtained.

The film of the present invention may also be a single layer film of the above layer (A).

Further, the film of the present invention may be a multilayer film which, in addition to the above layer (A), further has a layer formed of a soft polyolefin having a domain softening temperature of 50 ° C to 150 ° C according to ASTM D1525 (B). And at least one of the above layers (A) is the outermost layer.

[Soft polyolefin]

The soft polyolefin refers to a property of imparting flexibility to a release film when the film of the present invention is used as a release film for heating and pressurization.

The soft polyolefin has a softening temperature according to ASTM D1525 of 50 ° C to 150 ° C, preferably 60 ° C to 150 ° C, more preferably 70 ° C to 150 ° C; according to ASTM D1238 (temperature 260 ° C, weight 5.0 kg) The melt flow rate is from 0.5 g/10 min to 200 g/10 min, preferably from 5 g/10 min to 100 g/10 min; the melting point (Tm) measured by DSC is from 80 ° C to 240 ° C, more preferably 100 ° C. ~240 °C.

When the multilayer film of the present invention is used as a release film for FPC production, the soft polyolefin is used to impart so-called cushioning properties to the release film.

Therefore, in the production of the FPC, the soft polyolefin improves the unevenness of the surface of the substrate on which the circuit is formed on the surface, and prevents the adhesive from flowing out from the end surface of the cover layer to the circuit.

Specific examples of the soft polyolefin satisfying the above conditions include a monomer or a copolymer of one or more olefins selected from the group consisting of ethylene, propylene, butene, pentene, hexene, and methylpentene; ethylene and acrylic acid; a copolymer of an ester, a copolymer of ethylene and methacrylate, a copolymer of ethylene and acrylic acid, a copolymer of ethylene and methacrylic acid, and a partial ionomer thereof, and a copolymer of a plurality of ethylene and acrylic acid or acrylate A blend of a compound or the like, which is disclosed in Japanese Laid-Open Patent Publication No. 2-175247, and the like. These may be used alone or in combination of two or more.

Among these, from the viewpoint of moderate flexibility and cushioning, such as propylene. Butene-1 copolymer, ethylene. The ethyl acrylate copolymer is particularly suitable for use. Further, these soft polyolefins may be used in one layer or in a plurality of layers of two or more layers.

These soft polyolefins are also easily available from the market, and are commercially available under the trade names of TAFMER XR and Mitsui DU PONT POLYCHEMICAL (trade name): EVEFLEX.

[Film of the invention]

The film of the present invention has at least one layer (A) formed of a 4-methyl-1-pentene copolymer having a mass ratio of 95.5 mass% to 99.5. % of a constituent unit derived from 4-methyl-1-pentene and 0.5% by mass to 4.5% by mass of a constituent unit of an olefin having 3 to 20 carbon atoms other than 4-methyl-1-pentene; A) The overall thickness is 40 μm~90 μm; and the overall thermal shrinkage of the film is 1% to 5%.

The film of the present invention is characterized by having the above layer (A). Therefore, the film of the present invention is a single layer film formed only of the above layer (A), and a multilayer film having at least one layer (A).

When the above-mentioned multilayer film is used as the release film, since the release property of the layer (A) is excellent, it is preferable that at least one of the layers (A) is the outermost layer.

The layer (A) may contain, for example, a fluorine-based resin such as polytetrafluoroethylene, polyphenylene sulfide, polyester or the like as a 4-methyl-1-pentene-based copolymer, without impairing the object of the present invention. The polymer (B) preferably contains 90% by mass to 100% by mass of a 4-methyl-1-pentene copolymer, more preferably 95% by mass to 100% by mass, particularly preferably 100% by mass. .

When the multilayer film of the present invention is used as a release film for FPC production, in particular, when the surface of the substrate on which the circuit is formed has a large undulation difference and a better cushioning property is required, it is preferable to further have a soft film. The multilayer film of the layer (B) formed of the polyolefin, and the layer (B) may be a multilayer of two or more layers.

The layer (B) may contain, for example, polymethacrylic acid, polyethylene terephthalate (PET), polybutylene terephthalate (PBT), etc., within the range not impairing the object of the present invention. Polyamide, polyamido-6, polyamide-6,6, polyamide 11, polyamine 12, etc., but layer (B) preferably contains 90% to 100% by mass of soft The polyolefin is more preferably 95% by mass to 100% by mass, particularly preferably 100% by mass.

The multilayer film of the present invention may have a layer (C) other than the layer (A) and the layer (B) without impairing the object of the present invention.

As the resin which can be used for the layer (C), a thermoplastic resin having high heat resistance is preferable. For example, polyolefins such as polypropylene; polyesters such as polyethylene terephthalate (PET) and polybutylene terephthalate (PBT); and polyamine-6, polyamine- 6,6, polyamine, polyamine, and the like. These resins are readily available from the market. For example, PRIMEPOLYPRO manufactured by PRIME POLYMER Co., Ltd., NOVAPET manufactured by Mitsubishi Engineering Plastics Co., Ltd., and AMILANE manufactured by Toray Industries Co., Ltd., etc., may be mentioned. Further, these resins may be used singly or in combination of two or more.

Specific examples of the multilayer film of the present invention include a layered structure of a layer (A)/layer (B) and a layer (A)/layer (C); a layer (A)/layer (B)/layer (C), Layer (A) / Layer (C) / Layer (A) and Layer (A) / Layer (B) / Layer (A) three-layer structure.

In order to use the step of omitting the identification of the front and back when using the release film, it is preferred to have at least two or more layers (A), and the two layers of the layer (A) are the outermost layers on both sides of the film, in order to A good cushioning property is obtained, and it is preferable to contain the above layer (B). A three-layer film of layer (A) / layer (B) / layer (A) is particularly preferred.

In the multilayer film of the present invention, the layer (A) functions as a release layer, and the layer (B) functions as a buffer layer. Further, since the layer (B) has a moderate cushioning property, in the process of manufacturing the FPC, the coating of the cover layer to the non-printing portion is surely performed, and the formation of the FPC which is completely void-free and integrated can be achieved.

In the film of the present invention, when the layer (A) is one layer, the thickness of the layer (A) is preferably from 40 μm to 90 μm, more preferably from 40 μm to 80 μm.

Further, in the multilayer film of the present invention, when the layer (A) is two or more layers, the thickness of the layer (A) as a whole is preferably 40 μm to 90 μm, more preferably 40 μm to 80 μm.

When the layer (A) is the outermost layer on both sides, if the thickness of the layers (A) is the same, the multilayer film is preferably not warped, that is, it is not bent into a bow shape, which is preferable.

When the thickness of the layer (A) is at least the above lower limit value, wrinkles can be prevented from occurring, and if it is at most the above upper limit value, cushioning properties can be maintained, which is preferable.

The layer (B) has a thickness of 30 to 100 μm, preferably 40 to 90 μm.

When the thickness of the layer (B) is at least the above lower limit value, the cushioning property can be maintained. Therefore, when the thickness is equal to or less than the above upper limit value, the amount of the layer (B) at the time of heating and pressure treatment is excessive. It can be reduced, so it is better.

In the multilayer film of the present invention, the ratio of the overall thickness of the layer (A) to the entire thickness of the film is 25% to 80%, preferably 30% to 60%, more preferably 30% to 50%.

In the case of the multilayer film containing the layer (B), if the ratio of the thickness of the entire layer (A) to the entire thickness of the film is at least the above lower limit, wrinkles can be prevented, and the upper limit is Hereinafter, the cushioning property can be maintained, which is preferable.

The heat shrinkage of the film of the present invention as a whole is 1% to 5%, preferably 1% to 3%, more preferably 1.5% to 2.5%. If the heat shrinkage rate is 1% or more, in particular, when the film of the present invention is used as a release film when the cover layer is adhered to the FPC, wrinkles are not caused on the surface of the film, which is preferable. Further, when the heat shrinkage ratio is 5% or less, it is preferable that no gap is formed between the circuit surface and the release film when the cover layer is adhered.

The heat shrinkage ratio of the film of the present invention means the ratio at which the film shrinks with respect to the length of the film before heating when the film of the present invention is heated to shrink. That is, the film length L1 measured at room temperature before heating is taken out after being left in a gas atmosphere at 170 ° C for 30 minutes, and after cooling at room temperature for 30 minutes, the portion relative to the above L1 is determined. The length L2 is determined by the value obtained by the following formula (1) as the heat shrinkage rate.

Heat shrinkage ratio (%) = (L1 - L2) / L1 × 100 (1) (wherein L1: film length before heating, cm; L2: length of the portion corresponding to L1 after heating, cm)

The heat shrinkage rate of the film of the present invention is a value in the direction in which the film is stretched. That is, the film length at the time of measuring the heat shrinkage rate is a length parallel to the direction in which the film extends.

For example, immediately after the film of the present invention is subjected to extrusion molding or co-extrusion molding, the MD direction in the stretching direction, that is, the length in the extrusion direction, is directly and continuously used. Alternatively, the film of the present invention may be biaxially stretched, and the biaxial extension may be a sequential or simultaneous biaxial extension. The heat shrinkage rate when biaxially stretched is the value of each extending direction. Further, the direction of extrusion is parallel to the direction of the die line which occurs on the surface of the film, and can be easily determined from the die line.

Further, the film of the present invention is preferably embossed by at least one of the surfaces of the film formed by the layer (A). The surface roughness of the surface layer of the embossed film according to JIS B0601 is 0.01 to 20 μm, preferably 0.1 to 10 μm, more preferably 0.1 to 5 μm, and particularly preferably 0.1 to 2 μm. When the surface roughness of the surface layer of the film is within the above range, good release property can be obtained.

Further, in the film of the present invention, the modulus of elasticity (E') at a temperature of 150 ° C is preferably in the range of 1.5 × 10 ⁷ to 8.5 × 10 ⁷ MPa. Here, the elastic modulus (E') at a temperature of 150 ° C indicates the dynamic storage elastic modulus at a temperature of 150 ° C in the extending direction. Specifically, a sample having a length of 0.13 mm in the extending direction and a direction of 5 mm in the direction of the vertical extending direction can be used for the film of the present invention, and a dynamic storage elastic modulus measuring device, for example, a TA company (RSA-II) is used. According to the measurement temperature -150 to 200 ° C, the temperature increase rate of 3 ° C / min, and the measurement mode: tensile and measurement frequency 1 Hz, the elastic modulus (E') at a temperature of 150 ° C can be obtained.

When the film of the present invention is used as a release film for FPC production, the temperature of the release film used for heating the cover layer to the FPC is close to 150 °C. Therefore, when the modulus of elasticity at a temperature of 150 ° C is at least the above lower limit value, wrinkles can be prevented from occurring in the release film, and if it is at most the above upper limit value, the release film can have good cushioning properties.

[Method for Producing Film of the Present Invention]

The film of the present invention has at least one layer (A) formed of a 4-methyl-1-pentene copolymer having a mass ratio of 95.5 mass% to 99.5. % of a constituent unit derived from 4-methyl-1-pentene and 0.5% by mass to 4.5% by mass of a constituent unit of an olefin having 3 to 20 carbon atoms other than 4-methyl-1-pentene; A) The overall thickness is 40 μm~90 μm; and the overall thermal shrinkage of the film is 1% to 5%.

The film of the present invention can be produced by a known method such as extrusion molding, coextrusion molding, hot pressing, and solvent casting using a T-die device, and forming a film by a single layer. . In particular, the extrusion molding method or the coextrusion molding method using the T-die device can easily and uniformly control the thickness of each layer of the film by adjusting the interval of the die orifices of the slit portion of the mold, and can be broadened. Therefore, it is better. Further, after a wide film is manufactured, since the slit can be easily used to match the width of various FPC widths, the extrusion molding method or the coextrusion molding method using the T-die device is suitable as a release for FPC production. A method of manufacturing a film. Further, in the case of the coextrusion molding method, since the mixing in the molten state can be favorably performed at the adhesion interface between the respective resins, a laminated film excellent in adhesion strength can be obtained.

Specifically, in the case of producing a single-layer film formed only of the layer (A), for example, an extruder having a single-layer T-die can be used, and the temperature of the extruder and the T-die is set to 260 to 330 ° C. And extrusion molding is carried out.

Specifically, in the production of the above-described three-layer film formed of the layer (A) / layer (B) / layer (A), for example, two types of extrusion molding machines with three layers of T-shaped molds can be used for extrusion. The temperature of the machine and the T-die was set to 230 to 330 ° C to carry out extrusion molding.

Further, the multilayer film can be integrated into a multilayer film by an adhesive, and an urethane-based, isocyanate-based or epoxy-based adhesive can be applied to the film between the layers, and if necessary, These are formed by pressure bonding.

Further, as another method, a maleic anhydride-grafted polyethylene or a maleic anhydride-grafted polypropylene-like adhesive resin may be simultaneously extruded between the respective resin layers in a film form and each resin layer. Out, lamination. Further, a method of forming a film or a sheet in advance by thermal compression bonding or hot rolling in the above-described order may be employed.

Further, in the case of a single-layer film, the film having a heat shrinkage ratio of 1% to 5% of the present invention can be obtained by stretching the film after the single layer film of the layer (A) is produced; In the case of a multilayer film, the film can be stretched by manufacturing a multilayer film having the layer (B) formed of the above soft polyolefin and at least one layer of the layer (A) as the outermost layer. And get.

Further, as the stretching method, a conventional method can be suitably employed, and the stretching can be carried out by a method such as a tenter method or a roll stretching method. For example, when the multilayer film formed of the layer (A) / layer (B) / layer (A) is stretched, heating in the extension is performed so that the heat shrinkage ratio in the extending direction is 1% to 5%. The temperature is in the range of 50 ° C to 200 ° C, preferably 100 ° C to 150 ° C. In addition, it is necessary to extend at a slight extension ratio, and the stretching ratio is usually from 1% to 5%, preferably from 2% to 4%. Further, the extension may be performed by uniaxial stretching or biaxial stretching, and the biaxial stretching may be performed sequentially or simultaneously.

Specifically, the film of the present invention can be stretched by a roll using a raw material film obtained by an extrusion molding method or a co-extrusion molding method. When the raw material film obtained by the extrusion molding method or the co-extrusion molding method is contacted and passed through the surface of the roller having different circumferential speeds of at least two independent rotations, the peripheral speed of the raw material film is contacted at the subsequent contact roller (m/min) is faster than the peripheral speed (m/min) of the roller which is first contacted with the raw material film. That is, the film stretching method of the present invention controls the peripheral speed of the roll according to the speed of the raw material film passing through the surface of the roll which is subsequently contacted, which is faster than the speed of the surface of the roll which is first contacted, thereby allowing the film to pass through the film. The extension is carried out between two or more rolls.

The roller surface used for the extension is a mirrored roller, or an embossing roller may be used. In the case of an embossing roll, the embossing depth is preferably a roll processed to have an average thickness (Ra) of from 1 μm to 200 μm, preferably from 2 μm to 100 μm.

Next, a case where the above-described film formed of the layer (A) / layer (B) / layer (A) is produced will be exemplified. In Fig. 4 showing an example of the apparatus for producing a film of the present invention, a 4-methyl-1-pentene copolymer and a soft polyolefin which are respectively melted by three extruders 20 are passed through a multi-manifold type. The three layers were coextruded from the T-die 21 and extruded, and temporarily cooled to 50 ° C to 150 ° C by a cooling roll 22 to form a film. Next, the film is heated by a heating roller 23 having a temperature of 50 ° C to 200 ° C, and then embossed by a first embossing roll 24 having a temperature of 50 ° C to 200 ° C and a second embossing roll 25, and simultaneously The circumferential speed of the second embossing roller is faster than the peripheral speed of the first embossing roller, that is, the speed between the second pressing roller 27 and the second embossing roller 25 is faster than that passing through the first pressing roller 26 The speed between the first embossing rolls 24 is such that the film is stretched between the first embossing roll and the second embossing roll, whereby the film 8 of the present invention can be obtained, in order to obtain a heat shrinkage rate of 1%. The film of 5% is preferably about 1.01 to 1.05 times, more preferably 1.02 to 1.04, of the circumferential speed of the roller which the film is contacted with when the film is stretched. Times. Further, the roll temperature at this time is in the range of 50 ° C to 200 ° C, preferably 100 ° C to 150 ° C. Further, the peripheral speed of the surface of the roll which the film is later contacted, that is, the processing speed is 5 m/min to 100 m/min, preferably 10 m/min to 70 m/min. Further, in the case where the heat shrinkage ratio is not less than 1%, in order to prevent natural shrinkage during storage of the release film, tempering may be performed at a temperature less than the melting point of the resin after the stretching treatment.

Further, the step of forming the film and the step of extending the film can be carried out in two steps.

When the film forming step and the stretching step are separately performed, in order to prevent natural shrinkage of the formed film, it may be further tempered after being subjected to tempering at a temperature not exceeding the melting point of the resin. In addition, it is of course also possible to continuously carry out the forming step and the stretching step of the film. The apparatus used to carry out such steps is generally marketed.

[release film]

The film of the present invention is excellent in heat resistance and release property, and can be suitably used as a release film. Specifically, for example, a release film for FPC production, a release film for ACM materials used for aircraft parts, a release film for producing a rigid printed circuit board, a release film for a semiconductor sealing material, and a release film for FRP molding, Release film for rubber sheet hardening, release film for special adhesive tape, etc.

Among these, the film of the present invention can be suitably used for a release film for FPC production.

In the production of FPC, a step of holding a substrate and a cover layer of a circuit on a metal plate and heating and pressurizing it is carried out by using a thermosetting type adhesive. In this step, in order to avoid the occurrence of adhesion between the cover layer and the metal sheet during heating and pressurization, the release film of the present invention is used in the middle.

Figure 1 is a cross-sectional view showing a multilayer film of the present invention. Moreover, Fig. 2 is a cross-sectional view showing a state in which the release film of the present invention is used for pressing at the time of forming an FPC. By using the release film of the present invention, the voids of the non-printing portion are completely adhered by the cover layer and integrated. In Fig. 2, 8 is a film of the present invention, and 9 is an FPC.

The release film of the present invention is deformed by a coating layer before press-forming of the applied thermosetting adhesive by heating, and due to the cushioning property and the outermost layer of the intermediate layer (B). A) is excellent in release property, so as shown in FIG. 3, the film 8 of the present invention of the release film is adhered to the end face of the cover layer 6 and the copper foil face 10 of the circuit, so that the adhesive does not flow out, but FPC molding is performed in a state in which the boundary between the exposed portion and the cover layer portion is clearly defined.

Further, in the release film of the present invention, when the cover layer is subjected to heating and pressure molding, the release film is less likely to wrinkle, so that the release film does not follow the unevenness of the circuit surface of the wrinkled portion. The voids caused by the defects are generated, and the wrinkles are not transferred to the FPC, so that an FPC having an excellent appearance can be obtained.

Further, when the cover layer is subjected to adhesion heating and press molding, since the layer (B) is less likely to overflow, the layer (B) does not adhere to the surface of the substrate on which the circuit is formed, and is heated and pressurized. The yield of the FPC product caused by the metal sheet used for forming is lowered and the workability is lowered.

(Example)

Hereinafter, the present invention will be described in more detail by way of examples, but the invention is not limited thereto.

[Measurement of Resin]

(1) Resin for measurement (4-methyl-1-pentene copolymer, soft polyolefin)

(2) The MFR of the melt flow rate (MFR) resin was measured in accordance with ASTM D1238, with a load of 5.0 kg and a temperature of 260 °C.

(3) Density The density of the resin was measured by a density gradient tube method in accordance with ASTM D1505.

(4) The melting point of the melting point resin was measured by a DSC apparatus (manufactured by Seiko Instruments Co., Ltd.).

Using a DSC apparatus (manufactured by Seiko Instruments Co., Ltd.), the temperature was raised to 10 ° C higher than the melting point of each resin in air at 10 ° C / min. At this time, the endothermic peak temperature of the melting was taken as the melting point of the resin. Thereafter, it was kept at a temperature 30 ° C higher than the melting point of each resin for 3 minutes, and then cooled to room temperature at 10 ° C / minute.

(5) Domain softening temperature The softening temperature of the resin is measured by using a flat plate of 1/6 inch thickness of each resin obtained by injection molding according to ASTM D1525.

[Measurement of film]

(1) Heat Shrinkage Rate When manufacturing a film, an extrusion molding machine or a co-extrusion molding machine with a T-die is used. The set temperature of the extruder and the set temperature of the T-die were set to 290 °C. The film obtained by extrusion molding has a width of 600 mm. From the arbitrary position of the film, a film having a length of 30 cm in the extrusion direction (hereinafter referred to as MD direction) and a length of 30 cm perpendicular to the MD direction (hereinafter referred to as TD direction) was cut out as a test film. The length in the MD direction at room temperature of the test film before heating described later was set to L1 (cm). The test film was heated in an air oven at 170 ° C for 30 minutes, taken out, and cooled at room temperature for 30 minutes. The length of the test film at the time of cooling in the MD direction at room temperature was set to L2 (cm). The value obtained by the following formula (1) was taken as the heat shrinkage ratio of the film.

Heat shrinkage rate (%) = (L1-L2) / L1 × 100 (1)

(2) Appearance wrinkles In the production of a film, an extrusion molding machine or a co-extrusion molding machine with a T-shaped mold is used. The set temperature of the extruder and the set temperature of the T-die were set to 290 °C. The film obtained by extrusion molding has a width of 600 mm. A total of 10 films each having a length of 30 cm in the MD direction and a length of 21 cm in the TD direction were cut out every 5 m, and this was used as a test film. This test film was placed at the position of 8 shown in Fig. 2 to perform a heating and pressurizing step. The conditions of this step were a temperature of 160 ° C, a pressure of 2 MPa, and a heating and pressurization time of 30 minutes. An epoxy-based adhesive having a flow start temperature of 80 ° C was applied to the cover layer at a thickness of 30 μm. A cover layer (thickness 25 μm) formed of a polyimide film was adhered to the circuit surface formed on the substrate. Thereafter, the test film was taken out, and the occurrence of wrinkles of the film was evaluated by visual observation as follows.

The case where wrinkles were not observed on all of the 10 test films was visually observed: ○When the wrinkles were observed on 1 to 4 of all the 10 test films, Δ was confirmed by visually observing 5 to 10 of all 10 test films. To the case of wrinkles: ×

(3) Overflow amount An extrusion molding machine or a co-extrusion molding machine with a T-shaped mold was used in the production of a film. The set temperature of the extruder and the set temperature of the T-die were set to 290 °C. The film obtained by extrusion molding has a width of 600 mm. From the arbitrary position of the film, a total of four films having a length of 10 cm in the MD direction and a length of 10 cm in the TD direction were cut out, and this was made into a test thin [S1].

A stainless steel plate (32 cm × 32 cm × thickness 5 mm) was designated as [A], 10 sheets (30 cm × 30 cm) of the buffer material were designated as [B], and an aluminum plate (30 cm × 30 cm × thickness 0.1 mm) was designated as [C].

As the sample for measuring the overflow amount, the ones [A]/[B]/[C]/[S1]/[C]/[B]/[A] are sequentially superimposed from the bottom. Here, the test film [S1] superimposed on [C] was arranged side by side so as not to overlap each other.

Next, the sample was heated and pressurized at a temperature of 180 ° C and a pressure of 8 MPa for 10 minutes, and then held at a pressure of 5 MPa, and cooled to room temperature for 3 minutes, and then four test films [S1] were taken out. The length of the layer (B) overflowing from the end of the layer (A) of the four test films [S1] taken out was measured, and the maximum value thereof was taken as the overflow amount.

(4) Surface roughness (Ry) An extrusion molding machine or a co-extrusion molding machine with a T-shaped mold was used in the production of a film. The set temperature of the extruder and the set temperature of the T-die were set to 290 °C. The film obtained by extrusion molding has a width of 600 mm. From the arbitrary position of the film, a film having a length of 10 cm in the MD direction and a length of 10 cm in the TD direction was cut out, and this was used as a test film. From the center of the test film, the surface roughness of the surface layer of the film was determined in accordance with JIS B0601 by using 5 cm as the reference length in any direction.

(5) The elastic modulus (E') of the elastic modulus (E') film was evaluated by measuring the dynamic storage elastic modulus at a temperature of 150 ° C in the MD direction of the film.

An extrusion molding machine or a co-extrusion molding machine with a T-shaped mold is used in the production of the film. The set temperature of the extruder and the set temperature of the T-die were set to 290 °C. The film obtained by extrusion molding has a width of 600 mm. From the arbitrary position of the film, a film having a length of 0.13 mm in the MD direction and a length of 5 mm in the TD direction was cut out, and this was designated as a test film. The dynamic storage elastic modulus at a temperature of 150 ° C in the MD direction of the test film was measured by a dynamic storage elastic modulus measuring device (RSA-II, manufactured by TA Corporation). The measurement conditions were a measurement temperature of -150 to 200 ° C, a temperature increase rate of 3 ° C / min, and a measurement mode: stretching, and a measurement frequency of 1 Hz. From the above measurement results, the elastic modulus (E') of the film at a temperature of 150 ° C was obtained.

[Example 1]

A multi-manifold type 3-layer co-extruded extruder with a T-shaped mold was used in the production of the film. (A1) 4-methyl-1-pentene-based copolymer (1-decene content: 2.4% by mass, MFR: 25 g/10 min, melting point: 233 ° C) in a first extruder and a third extruder Plasticization was carried out at a temperature of 300 °C. In addition, the second extruder will be (B1) propylene. The 1-butene copolymer (density 0.89 g/cm ³ , MFR: 30 g/10 min, melting point 110 ° C, domain softening temperature 78 ° C, 1-butene content 20 mol %) was plasticized at a temperature of 300 ° C.

A1 was used as the layer (A) and B1 was used as the layer (B), and co-extrusion was carried out, and the layer (A) / layer (B) / layer (A) was combined in a T-type mold. Further, the composite (20 m/min) was taken up by a roll to produce a multilayer film comprising three layers.

Next, the surface of the obtained multilayer film was embossed by two embossing rolls having an average thickness (Ra) of 25 μm. The roll temperature was 130 ° C and the embossing speed was 20 m/min. The peripheral speed of the second embossing roll to which the multilayer film was subsequently contacted was set to 1.03 times with respect to the peripheral speed of the first embossing roll which was first contacted by the multilayer film. By setting the ratio of the two circumferential speeds to 1.03 times, the configuration of A1/B1/A1=25/70/25 μm, the total thickness of 120 μm, and the elastic modulus (E') in the MD direction (extension direction) are obtained. A multilayer film of 5 × 10 ⁷ MPa and a heat shrinkage ratio of 2.1%.

Next, the obtained multilayer film was placed in the heating and pressurizing step shown in Fig. 2, and the cover layer was adhered to the circuit surface formed on the substrate to form an FPC. The conditions were set at a temperature of 160 ° C, a pressure of 2 MPa, and a heating and pressurization time of 30 minutes. The cover layer is formed of a polyimide film having a thickness of 25 μm. Further, an epoxy-based adhesive having a flow start temperature of 80 ° C was applied to the cover layer at a thickness of 30 μm.

In the FPC made, the cover layer is completely in close contact with the substrate body, and no air remains.

Further, by visual evaluation, wrinkles did not occur on the multilayer film (three-layer film) used when the cover layer was adhered, and the obtained flexible printed circuit board also had a good appearance. The evaluation results are shown in Table 1.

[Embodiment 2]

Except for the use of (B2) ethylene. acrylate ethyl ester copolymer (MFR: 27 g/10 min, melting point 90 ° C, domain softening temperature 70 ° C, ethyl acrylate content 15 mol%) in place of B1, the others are shown in Table 1. Conditions A multilayer film was produced in the same order as in Example 1.

Next, the cover film was adhered to the circuit surface formed on the substrate by heating and pressurizing the multilayer film under the same conditions as in Example 1.

Evaluation was carried out as in Example 1, and the results are shown in Table 1.

[Example 3]

In addition to replacing B1, use (B3) propylene. 1-butene. 4-methyl-1-pentene copolymer (propylene content 36 mol%, 1-butene content 14 mol%, 4-methyl-1-pentene content 50 mol%, density 0.880 g/cm ³ , MFR: 27g/10 minutes, domain softening temperature 80 ° C) 50% by mass and linear low density polyethylene (density 0.92g / cm ³ , MFR: 15g / 10 minutes, domain softening temperature 100 ° C) 50 mass A multilayer film was produced in the same manner as in Example 1 except for the blend of % (MFR: 20 g/10 minutes, domain softening temperature: 85 ° C).

Next, the cover film was adhered to the circuit surface formed on the substrate by heating and pressurizing the multilayer film under the same conditions as in Example 1.

Evaluation was carried out as in Example 1, and the results are shown in Table 1.

[Example 4]

A multilayer film was produced in the same manner as in Example 1 except that the thickness of the layer (A) was changed to 20 μm by changing the extrusion amount of the first extruder and the third extruder.

Next, the cover film was adhered to the circuit surface formed on the substrate by heating and pressurizing the multilayer film under the same conditions as in Example 1.

Evaluation was carried out as in Example 1, and the results are shown in Table 1.

[Example 5]

A multilayer film was produced in the same manner as in Example 1 except that the thickness of the layer (A) was changed to 35 μm by changing the extrusion amount of the first extruder and the third extruder.

Next, the cover film was adhered to the circuit surface formed on the substrate by heating and pressurizing the multilayer film under the same conditions as in Example 1.

Evaluation was carried out as in Example 1, and the results are shown in Table 1.

[Embodiment 6]

A multilayer film was produced in the same manner as in Example 1 except that the first extruder was used, and the thickness of the layer (A) was 50 μm.

Next, the cover film was adhered to the circuit surface formed on the substrate by heating and pressurizing the multilayer film under the same conditions as in Example 1.

Evaluation was carried out as in Example 1, and the results are shown in Table 1.

[Embodiment 7]

Except for the substitution of A1, the (A2) 4-methyl-1-pentene copolymer (1-decene content 1.0% by mass, MFR: 25 g/10 minutes, melting point 238 ° C) was used, except for the conditions shown in Table 1. A multilayer film was produced in the same order as in Example 1.

Next, the cover film was adhered to the circuit surface formed on the substrate by heating and pressurizing the multilayer film under the same conditions as in Example 1.

Evaluation was carried out as in Example 1, and the results are shown in Table 1.

[Embodiment 8]

Except for the substitution of A1, the (A3) 4-methyl-1-pentene copolymer (1-decene content 4.0% by mass, MFR: 27 g/10 minutes, melting point 229 ° C) was used, except for the conditions shown in Table 1. A multilayer film was produced in the same order as in Example 1.

Next, the cover film was adhered to the circuit surface formed on the substrate by heating and pressurizing the multilayer film under the same conditions as in Example 1.

Evaluation was carried out as in Example 1, and the results are shown in Table 1.

[Embodiment 9]

Except for the substitution of Al, (A4) A4: 4-methyl-1-pentene-based copolymer (1-tetradecene content 2% by mass, MFR: 22 g/10 minutes, melting point 232 ° C), A multilayer film was produced in the same order as in Example 1 under the conditions shown.

Next, the cover film was adhered to the circuit surface formed on the substrate by heating and pressurizing the multilayer film under the same conditions as in Example 1.

Evaluation was carried out as in Example 1, and the results are shown in Table 1.

[Comparative Example 1]

A multilayer film was produced in the same manner as in Example 1 except that the thickness of the layer (A) was changed to 5 μm by changing the extrusion amount of the first extruder and the third extruder.

Next, the cover film was adhered to the circuit surface formed on the substrate by heating and pressurizing the multilayer film under the same conditions as in Example 1.

Evaluation was carried out as in Example 1, and the results are shown in Table 2.

[Comparative Example 2]

A multilayer film was produced in the same manner as in Example 1 except that the thickness of the layer (A) was changed to 50 μm by changing the extrusion amount of the first extruder and the third extruder.

Next, the cover film was adhered to the circuit surface formed on the substrate by heating and pressurizing the multilayer film under the same conditions as in Example 1.

Evaluation was carried out as in Example 1, and the results are shown in Table 2.

[Comparative Example 3]

Except for the substitution of A1 using (A5) 4-methyl-1-pentene copolymer (1-nonene content 5.0% by mass, MFR: 24 g/10 minutes, melting point 226 ° C), the conditions shown in Table 2 were A multilayer film was produced in the same order as in Example 1.

Next, the cover film was adhered to the circuit surface formed on the substrate by heating and pressurizing the multilayer film under the same conditions as in Example 1.

Evaluation was carried out as in Example 1, and the results are shown in Table 2.

[Comparative Example 4]

In addition to the substitution A1, the (A5) 4-methyl-1-pentene copolymer (1-nonene content 5.0% by mass, MFR: 24 g/10 minutes, melting point 226 ° C) was used, and B1 was used instead of B1. The conditions shown in Table 2 were carried out in the same order as in Example 1 to produce a multilayer film.

Next, the cover film was adhered to the circuit surface formed on the substrate by heating and pressurizing the multilayer film under the same conditions as in Example 1.

Evaluation was carried out as in Example 1, and the results are shown in Table 2.

[Comparative Example 5]

In addition to the substitution A1, the (A5) 4-methyl-1-pentene copolymer (1-nonene content 5.0% by mass, MFR: 24 g/10 minutes, melting point 226 ° C) was used, and B1 was used instead of B1. The conditions shown in Table 2 were carried out in the same order as in Example 1 to produce a multilayer film.

Next, the cover film was adhered to the circuit surface formed on the substrate by heating and pressurizing the multilayer film under the same conditions as in Example 1.

Evaluation was carried out as in Example 1, and the results are shown in Table 2.

[Comparative Example 6]

In addition to the substitution of A1, the (A6) 4-methyl-1-pentene copolymer (1-decene content 0.2% by mass, MFR: 25 g/10 minutes, melting point 241 ° C) was used, except for the conditions shown in Table 2 A multilayer film was produced in the same order as in Example 1.

Next, the cover film was adhered to the circuit surface formed on the substrate by heating and pressurizing the multilayer film under the same conditions as in Example 1.

Evaluation was carried out as in Example 1, and the results are shown in Table 2.

[Comparative Example 7]

Except for the substitution of A1, (A7) 4-methyl-1-pentene-based copolymer (1-decene content: 10% by mass, MFR: 22 g/10 minutes, melting point: 221 ° C), the conditions shown in Table 2 were A multilayer film was produced in the same order as in Example 1.

Next, the cover film was adhered to the circuit surface formed on the substrate by heating and pressurizing the multilayer film under the same conditions as in Example 1.

Evaluation was carried out as in Example 1, and the results are shown in Table 2.

[Comparative Example 8]

The conditions shown in Table 2 were compared with the examples except that the (A8) 4-methyl-1-pentene copolymer (A8 content: ethylene content: 2% by mass, MFR: 26 g/10 minutes, melting point: 241 ° C) was used instead of A1. 1 A multilayer film was produced in the same order.

Next, the cover film was adhered to the circuit surface formed on the substrate by heating and pressurizing the multilayer film under the same conditions as in Example 1.

Evaluation was carried out as in Example 1, and the results are shown in Table 2.

[Comparative Example 9]

An unstretched multilayer film was produced in the same manner as in Example 1 except that the peripheral speeds of the first embossing roll and the second embossing roll were the same.

Next, the film was adhered to the circuit surface formed on the substrate by heating and pressurizing the film under the same conditions as in Example 1.

The evaluation was carried out by visual observation, and wrinkles were formed on the release film used for the adhesion of the cover layer, and the wrinkles were transferred onto the flexible printed circuit board to form a flexible printed circuit board having a problem in appearance. The evaluation results are shown in Table 2.

[Comparative Example 10]

A multilayer film was produced in the same manner as in Example 1 except that the peripheral speed of the second embossing roll was 1.15 times the circumferential speed of the first embossing roll and 15% in the MD direction.

Next, the cover film was adhered to the circuit surface formed on the substrate by heating and pressurizing the multilayer film under the same conditions as in Example 1.

The adhesive layer of the completed flexible printed circuit board is inferior in adhesion to the substrate body, and an air is present. Further, the pattern which is unevenly extended is transferred onto the flexible printed circuit board, and the appearance of the flexible printed circuit board is poor. The evaluation results are shown in Table 2.

[Comparative Example 11]

A multilayer film was produced in the same manner as in Example 1 except that the first extruder was used and a single layer film having a layer (A) thickness of 20 μm was formed.

Next, the cover film was adhered to the circuit surface formed on the substrate by heating and pressurizing the multilayer film under the same conditions as in Example 1.

Evaluation was carried out as in Example 1, and the results are shown in Table 2.

[Comparative Example 12]

A multilayer film was produced in the same manner as in Example 1 except that the first extruder was used, and the single layer film having the thickness of the layer (A) of 150 μm was formed.

Next, the cover film was adhered to the circuit surface formed on the substrate by heating and pressurizing the multilayer film under the same conditions as in Example 1.

Evaluation was carried out as in Example 1, and the results are shown in Table 2.

(industrial availability)

The film of the present invention containing a layer formed of a specific 4-methyl-1-pentene copolymer, having a specific thickness and a heat shrinkage ratio, is excellent in heat resistance and release property, and is therefore suitable for use as a separation. Type film. In particular, when FPC is produced, by using as a release film, adhesion between the metal plate and the cover layer, and adhesion of the adhesive to the other parts can be prevented, and the non-printed portion is not formed during molding. The exposed portion of the gap, the circuit terminal portion, and the like is not contaminated by the melted out of the adhesive.

When the cover layer is adhered by heat and pressure, wrinkles are not formed on the release film, so that the gap formed by the release film on the surface of the substrate on which the circuit is formed is not generated at the portion where wrinkles occur. Since FPC molding which is improved in appearance due to wrinkle transfer is efficiently formed, a release film which is used for FPC production can be suitably used.

Further, in the case where a release film is used as a film having a layer containing a specific soft polyolefin at the time of FPC production, the release film has good cushioning properties and can follow the unevenness of the surface of the FPC, and is heated and pressurized. In the case where the adhesive is less likely to overflow, there is no problem that the FPC product yield is lowered and the workability is lowered due to adhesion of the adhesive to the FPC and the metal plate used for heating and pressurization.

1. . . Layer formed by 4-methyl-1-pentene copolymer (A)

2. . . Layer formed of soft polyolefin (B)

3. . . Metal plate for heating and pressurization

4. . . Stainless steel plate

5. . . Release film (single layer)

6. . . Cover layer

7. . . Thermosetting adhesive applied to the cover layer

8. . . Film of the invention

9. . . Flexible printed circuit board

10. . . Circuit copper foil

11. . . Circuit part of flexible printed circuit board

20. . . Extruder

twenty one. . . Multi-manifold type 3-layer co-extruded T-die

twenty two. . . Cooling roller

twenty three. . . Heating roller

twenty four. . . First embossing roller

25. . . Second embossing roller

26. . . First pressing roll

27. . . Second pressing roll

Figure 1 is a cross-sectional view of a film of the present invention.

2 is a cross-sectional view showing an example of a state in which a flexible printed circuit board is molded by using the film of the present invention.

3 is a cross-sectional view showing an example of a terminal exposed portion of a flexible printed circuit board formed by using the film of the present invention.

Fig. 4 is a view showing an example of a manufacturing apparatus of a film of the present invention.

1. . . Layer formed by 4-methyl-1-pentene copolymer (A)

2. . . Layer formed of soft polyolefin (B)

Claims (11)

A film characterized by having at least one layer (A) formed of a 4-methyl-1-pentene copolymer, and the 4-methyl-1-pentene copolymerization system has a mass of 95.5 mass%. 99.5 mass% of a constituent unit derived from 4-methyl-1-pentene and 0.5% by mass to 4.5% by mass of a constituent unit of an olefin having 3 to 20 carbon atoms other than 4-methyl-1-pentene; The overall thickness of the layer (A) is 40 μm to 90 μm; and the overall heat shrinkage of the film is 1% to 5%. A film according to claim 1 which is a single layer film of the above layer (A). The film of claim 1, which comprises a plurality of layers further comprising, in addition to the layer (A), a soft polyolefin having a domain softening temperature of 50 ° C to 150 ° C according to ASTM D1525. Layer (B), and at least one of the above layers (A) is the outermost layer. The film of claim 1, which comprises a plurality of layers having a layer (B) formed of a soft polyolefin having a softening temperature of 50 ° C to 150 ° C according to ASTM D1525, and at least 2 layers The above layer (A); and the two layers of the above layer (A) are the outermost layers on both sides of the film. The film of any one of claims 1 to 3, wherein the olefin having 3 to 20 carbon atoms other than 4-methyl-1-pentene is selected from the group consisting of 1-octene and 1-decene. At least one of 1-tetradecene and 1-octadecene. Such as the film of claim 3 or 4, wherein the soft polyolefin The hydrocarbon is a polymer obtained by (co)polymerizing one or more kinds of olefins selected from the group consisting of ethylene, propylene, butene, pentene, hexene and methylpentene. The film of claim 3, wherein the soft polyolefin is selected from the group consisting of a copolymer of ethylene and acrylate, a copolymer of ethylene and methacrylate, a copolymer of ethylene and acrylic acid, ethylene and methacrylic acid. a copolymer of a copolymer and a portion of its ionic crosslinks. The film of claim 3, wherein the overall thickness of the layer (A) is from 25% to 80% of the overall thickness of the film. The film according to any one of claims 2 to 4, wherein at least one of the surfaces of the film formed by the layer (A) is embossed. A film according to any one of claims 1 to 4, which is obtained by an extrusion molding method or a coextrusion molding method. A release film obtained by the film of any one of claims 1 to 10.