Films, films with release films, diaphragms, laminates, molded products and acoustic transducers

Abstract

To provide a film that can prevent delamination of multilayer films when the release film is peeled off before molding, while maintaining high shape retention before molding, and high formability and mold-following property during molding.SOLUTION: A film of the present invention is a film which has a curable silicone layer (A) with another silicone layer (B) on at least one side and the following (a) viscoelastic properties, and in which the arithmetic mean height (Sa) of at least one side between the layers of the silicone layer (A) and the silicone layer (B) is 500 to 4000 nm. (a) The storage modulus E'(10 Hz) at a measurement temperature of 20°C and a frequency of 10 Hz is 0.1 MPa to 500 MPa.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a film used to obtain molded articles such as acoustic members, a film with a release film, and a diaphragm, a laminate, a molded article, and an acoustic transducer obtained from these. [Background technology]

[0002] For example, the widespread use of small electronic devices such as smartphones, PDAs, notebook computers, DVD players, LCD TVs, digital cameras, and portable music players has led to an increasing demand for small speakers (usually called microspeakers) and receivers used in these electronic devices, as well as small electroacoustic transducers such as microphones and earphones. Polyetherimide (PEI) resin, polyether ether ketone (PEEK) resin, and the like are widely used for the diaphragms used in these electroacoustic transducers.

[0003] In recent years, the use of silicone resins in the above-mentioned diaphragms has also been considered. For example, Patent Document 1 discloses a diaphragm sheet formed by sequentially laminating a release sheet, a first layer made of an uncured liquid silicone composition, and a second layer mainly containing thermoplastic polyurethane, and a method for manufacturing a diaphragm using this diaphragm sheet. In Patent Document 1, the diaphragm sheet is set in a mold and shaped, and then the release sheet is peeled off from the molded product to manufacture a diaphragm. The diaphragm sheet described in Patent Document 1 uses an uncured liquid silicone composition, which allows for high shaping during molding and also allows for high mold conformability. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2018-152817 Summary of the Invention [Problem to be solved by the invention]

[0005] As described above, in Patent Document 1, the diaphragm sheet is formed by setting the first layer made of an uncured liquid silicone composition with the release film laminated on it in a mold. Therefore, it is necessary to peel off the release film after molding, but the heat and pressure applied during molding often make it difficult to peel the release film from the first layer, which reduces work efficiency and poses a problem when it comes to mass production.

[0006] Therefore, it is desirable to peel off the release film from the diaphragm sheet before setting it in a mold such as a metal mold. However, without the release film, the first layer made of the uncured liquid silicone composition will stick to the mold, causing problems such as making it difficult to remove the molded product from the mold. Furthermore, without the release film, the diaphragm sheet of Patent Document 1 will have poor shape retention before shaping. On the other hand, even if a hardened layer is provided on the surface of the sheet that comes into contact with the mold in consideration of releasability from the mold, there is a problem that peeling may occur between the hardened layer and the sheet when the release film is peeled off before molding.

[0007] Therefore, the present invention aims to provide a film that can prevent delamination of the multilayer film when the release film is peeled off before molding, while improving shape retention before molding, and shapeability and mold conformability during molding. [Means for solving the problem]

[0008] As a result of extensive investigations, the present inventors have found that the above-mentioned problems can be solved by setting the arithmetic mean height (Sa) of at least one interlayer surface between the silicone layer (A) and the silicone layer (B) in a specific range, or by setting the interlayer peel strength in a specific range, and by setting the storage modulus E' at 20°C and 10 Hz in a specific range in a film having a curable silicone layer (A) and a silicone layer (B), and have completed the present invention as described below.

[0009] That is, the present invention provides the following [1] to

[18] . [1] A film comprising a curable silicone layer (A) and another silicone layer (B) on at least one side thereof, the film having the viscoelastic property (a) below, and the arithmetic mean height (Sa) of at least one surface between the silicone layer (A) and the silicone layer (B) being 500 to 4000 nm. (a) The storage modulus E' is 0.1 MPa to 500 MPa at a measurement temperature of 20°C and a frequency of 10 Hz. [2] A film comprising a curable silicone layer (A) and another silicone layer (B) on at least one side thereof, the film having the viscoelastic properties described below in (a), and the interlayer peel strength between the silicone layer (A) and the silicone layer (B) being 0.5 N / 5 cm or more. (a) The storage modulus E' is 0.1 MPa to 500 MPa at a measurement temperature of 20°C and a frequency of 10 Hz. [3] The film according to claim 1 or 2, having a gel fraction of 90% or less. [4] The film according to any one of the above [1] to [3], wherein the silicone layer (B) has a gel fraction of 80% or more. [5] The film according to any one of the above [1] to [4], wherein the silicone layer (B) has the following viscoelastic property (b): (b) The storage modulus E' (1 Hz) at a measurement temperature of 20°C and a frequency of 10 Hz is 0.1 MPa to 500 MPa. [6] The film according to any one of the above items [1] to [5], which has thermosetting properties. [7] The film according to any one of the above items [1] to [6], which has a crosslinked structure. [8] The film according to any one of the above [1] to [7], which comprises the silicone layer (B) on both sides of the silicone layer (A). [9] The film according to any one of the above items [1] to [8], which has the following viscoelastic properties (c) to (e) after curing: (c) Storage modulus E' at a measurement temperature of 20°C and a frequency of 10 Hz 20 is 0.1MPa or more and 500MPa or less. (d) Storage modulus E' at a measurement temperature of 100°C and a frequency of 10 Hz 100 is 0.1MPa or more and 500MPa or less. (e) the storage elastic modulus E'20 The storage modulus E' 100 The ratio (E' 100 / E' 20 ) is between 0.4 and 1.0.

[10] The film according to any one of the above [1] to [9], which is a film for a diaphragm.

[11] A film with a release film, comprising the film according to any one of the above [1] to

[10] and a release film provided on at least one surface of the film.

[12] A diaphragm obtained by curing the film according to any one of the above items [1] to

[10] .

[13] A laminate obtained by placing the film according to any one of the above [1] to

[10] in a mold and thermoforming it.

[14] A molded article obtained by peeling the laminate according to

[13] above from a mold.

[15] A diaphragm made of the molded product described in

[14] above.

[16] An acoustic transducer comprising the diaphragm described in

[12] or

[15] above.

[17] A method for producing a film having the following viscoelastic property (a), which is obtained by laminating a curable silicone layer (A) on at least one surface of a silicone layer (B) having an arithmetic mean height (Sa) of 500 to 4000 nm: (a) The storage modulus E' is 0.1 MPa to 500 MPa at a measurement temperature of 20°C and a frequency of 10 Hz.

[18] A method for producing a film having the following viscoelastic property (a) by laminating a curable silicone layer (A) on each of the two surfaces of a silicone layer (B) having an arithmetic mean height (Sa) of 500 to 4000 nm: (a) The storage modulus E' is 0.1 MPa to 500 MPa at a measurement temperature of 20°C and a frequency of 10 Hz. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide a film that has high shape retention before molding, and high formability and mold conformability during molding, while preventing interlayer delamination of the multilayer film when the release film is peeled off before molding. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a cross-sectional view showing the structure of a micro speaker diaphragm 1 according to one embodiment of the present invention. [Figure 2] FIG. 10 is a cross-sectional view showing the structure of a micro-speaker diaphragm 11 according to another embodiment of the present invention. [Figure 3] FIG. 10 is a plan view showing the structure of a micro-speaker diaphragm 21 according to another embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to the embodiments described below as long as they do not depart from the gist of the present invention. The boundary between a film and a sheet is not clear, and therefore, in the present invention, the term "film" encompasses "sheet."

[0013] [film] One embodiment of the film of the present invention (hereinafter also referred to as the present film) comprises a silicone layer (B) on at least one side of a curable silicone layer (A), and has viscoelastic properties with a storage modulus E' of 0.1 MPa to 500 MPa measured at a temperature of 20°C and a frequency of 10 Hz. The arithmetic mean height (Sa) of at least one interlayer surface between the silicone layer (A) and the silicone layer (B) is 500 to 4000 nm. An arithmetic mean height (Sa) of 500 nm or more can prevent delamination between the silicone layer (A) and the silicone layer (B). On the other hand, an arithmetic mean height of 4000 nm or less can prevent deterioration of the film's appearance. From these viewpoints, the arithmetic mean height of at least one interlayer surface is preferably in the range of 600 to 3500 nm, more preferably in the range of 700 to 3000 nm, and particularly preferably in the range of 800 to 2500 nm. Here, "at least one surface between the silicone layer (A) and the silicone layer (B)" refers to the surface of the silicone layer (A) facing the silicone layer (B) or the surface of the silicone layer (B) facing the silicone layer (A). The film of the present invention is formed by laminating silicone layers of the same type, and as described above, the arithmetic mean height (Sa) is within the above range, thereby achieving extremely good interlayer adhesion between the silicone layer (A) and the silicone layer (B). In the present invention, it is sufficient that at least one surface between the silicone layer (A) and the silicone layer (B) is within the above range. However, since the silicone layer (A) is curable and the shape of its surface is easily changed, it is preferable that the surface of the silicone layer (B) be within the above range.

[0014] The present film may have a silicone layer (B) on both sides of the silicone layer (A), or the silicone layer (A) may be an intermediate layer, with the two silicone layers (B) forming the front and back layers. In this case, it is sufficient that the arithmetic mean height (Sa) of either surface between at least one of the layers is within the above range, but it is preferable that the arithmetic mean height (Sa) of either surface between both layers is within the above range. The curable silicone layer (A) may consist of one layer or two or more layers, but preferably consists of one layer. Therefore, the present film may have a three-layer structure of outermost layer / middle layer / innermost layer, or a four-layer or greater structure with two or more middle layers between the outermost and innermost layers, such as outermost layer / middle layer / middle layer / innermost layer. Furthermore, the present film may have another layer, such as an adhesive layer, between the silicone layer (A) and the silicone layer (B) to improve the adhesion between these layers, provided that the effect of the arithmetic mean height (Sa) is not impaired. Furthermore, in the case of the four-layer structure described above, another layer, such as an adhesive layer, may also be provided between the intermediate layers (between the silicone layer (A) and the silicone layer (A)).

[0015] For the above-mentioned surface between the silicone layer (A) and the silicone layer (B) having an arithmetic mean height (Sa) of 500 to 4000 nm, the root mean square height (Sq) is preferably 500 to 5000 nm. When the root mean square height (Sq) is 500 nm or more, delamination between the silicone layer (A) and the silicone layer (B) can be more effectively prevented. On the other hand, when it is 5000 nm or less, the appearance of the film is not impaired. From the above viewpoints, the arithmetic mean height of at least one interlayer surface is more preferably in the range of 600 to 4500 nm, even more preferably in the range of 800 to 4000 nm, and particularly preferably in the range of 1000 to 3500 nm.

[0016] The silicone layer (A) of the present invention is a curable silicone layer, and the film has a certain degree of flexibility before molding, and is sufficiently cured during molding, resulting in good formability and conformability to the mold. Furthermore, the present film has a relatively hard silicone layer (B) and preferably has viscoelastic properties with a storage modulus E' of 0.1 MPa to 500 MPa when measured at a temperature of 20°C and a frequency of 10 Hz. This allows the flexible silicone layer to be properly maintained, and the film exhibits good shape retention before molding and good handleability, even without laminating a release film or the like on the film. In particular, an embodiment in which the silicone layer (A) is used as an intermediate layer and relatively hard outer and inner layers (silicone layer (B)) are provided on both surfaces is even more suitable, and this film can be easily set in a mold and shaped without laminating a release film, thereby eliminating the step of peeling off the release film after shaping.

[0017] Another silicone layer (B) of the present invention is a silicone layer on one side of the curable silicone layer (A). The silicone layer (B) is a curable or cured silicone layer. As described above, the silicone layer (A) is curable and its surface shape is more easily changed than the silicone layer (B). Therefore, it is preferable that the arithmetic mean height (Sa) of the silicone layer (B) is 500 to 4000 nm.

[0018] The arithmetic mean height (Sa) of the outermost surface of the present film is preferably 500 to 4000 nm. If the arithmetic mean height (Sa) of the outermost surface of the present film is 500 nm or more, the present film does not stick to the mold when it is pressed between the molds and then removed from the mold, making it easier to remove. On the other hand, if it is 4000 nm or less, the appearance of the film is not impaired. From the above viewpoints, the arithmetic mean height of the silicone layer (B) on the outermost surface of the present film is preferably in the range of 600 to 3500 nm, more preferably in the range of 700 to 3000 nm, and particularly preferably in the range of 800 to 2500 nm.

[0019] (gel fraction) The present film preferably has a gel fraction of 90% or less. When the present film has a gel fraction of 90% or less, it becomes easy to make the film flexible before molding, and the film hardens sufficiently during molding, resulting in sufficient shapeability and moldability, and improved formability. From the viewpoint of shaping and molding properties, the gel fraction of the present film is preferably 80% or less, more preferably 75% or less, and even more preferably 70% or less. The gel fraction of the silicone layer (A) is not particularly limited as long as it is 0% or more, but may also be, for example, 10% or more, or 20% or more.

[0020] In the present film, the gel fraction of the silicone layer (B) is preferably 80% or more. When the gel fraction of the silicone layer (B) is 80% or more, the silicone layer (B) can be made relatively hard even before the film hardens, which can further improve the shape retention before molding and also make it easier to prevent sticking to the mold. From the above viewpoints, the gel fraction of the silicone layer (B) is more preferably 85% or more, and even more preferably 90% or more. There are no particular upper limits on the gel fraction of the silicone layer (B) as long as it is 100% or less, but it may generally be lower than 100%, for example, 99% or less. In the case of a three-layer film in which the silicone layer (A) is the middle layer and the silicone layer (B) is the outermost and innermost layers (i.e., the outermost and innermost layers), the gel fractions of the outermost and innermost layers may be the same or different.

[0021] The gel fraction can be measured as follows. 1) Approximately 100 mg of samples are taken from the entire film, silicone layer (A) of the film, and silicone layer (B) of the film, and the sample mass (a) is measured. 2) The collected sample is immersed in chloroform at 23°C for 24 hours. 3) Remove the solid content from the chloroform and dry it in vacuum at 50°C for 7 hours. 4) Measure the mass (b) of the solid content after drying. 5) Using the masses (a) and (b), calculate the gel fraction based on the following formula (i).

[0022]

number

[0023] As is clear from the above measurement method, the gel fraction is calculated by including not only the crosslinked components contained in the film but also insoluble components other than the crosslinked components, such as fillers, as gel components. However, for the intermediate layer of the present film before curing, the gel fraction is calculated from the ratio of the gel fraction to the layer thickness of the entire present film and the outermost and innermost layers before curing.

[0024] (viscoelastic properties) The film has the following viscoelastic property (a): (a) The storage modulus E' is 0.1 MPa to 500 MPa at a measurement temperature of 20°C and a frequency of 10 Hz. When the storage modulus E' is 0.1 MPa or more, the film has a consistent hardness throughout, making it easy to peel from the release film and reducing the risk of tearing during peeling. Furthermore, even without a release film, it is easy to improve shape retention before molding and prevent sticking to the mold after molding. Furthermore, by setting the storage modulus E' to 500 MPa or less, the film can ensure a consistent flexibility and improve mold conformability and shaping during molding. From these perspectives, the storage modulus E' of the film is more preferably 0.5 MPa or more, even more preferably 0.8 MPa or more, and even more preferably 1 MPa or more. Furthermore, it is more preferably 300 MPa or less, even more preferably 200 MPa or less, even more preferably 100 MPa or less, and particularly preferably 50 MPa or less.

[0025] Furthermore, the silicone layer (B) in the present film preferably has the following viscoelastic property (b). (b) The storage modulus E' is 0.1 MPa to 500 MPa at a measurement temperature of 20°C and a frequency of 10 Hz. When the storage modulus E' of the silicone layer (B) is 0.1 MPa or more, shape retention can be improved even without a release film. Furthermore, by setting the storage modulus E' to 500 MPa or less, a certain level of flexibility can be ensured, and good mold-following and shaping properties can be achieved during molding. From these perspectives, the storage modulus E' of the present film is more preferably 0.5 MPa or more, even more preferably 0.8 MPa or more, and even more preferably 1 MPa or more. Furthermore, it is more preferably 300 MPa or less, even more preferably 200 MPa or less, even more preferably 100 MPa or less, and particularly preferably 50 MPa or less.

[0026] Furthermore, the present film preferably has the following viscoelastic properties (c) to (e) after curing. (c) Storage modulus E' at a measurement temperature of 20°C and a frequency of 10 Hz 20 is 0.1MPa or more and 500MPa or less. (d) Storage modulus E' at a measurement temperature of 100°C and a frequency of 10 Hz 100 is 0.1MPa or more and 500MPa or less. (e) the storage elastic modulus E' 20 The storage modulus E' 100 The ratio (E' 100 / E' 20 ) is between 0.4 and 1.0.

[0027] By having the viscoelastic property (c) above, the present film tends to have excellent acoustic properties such as sound quality and reproducibility when used in acoustic components such as vibration films. From the viewpoint of acoustic properties and handling properties after curing, the storage modulus E' at 20°C after curing is 20 is more preferably 1 MPa or more, even more preferably 2 MPa or more, even more preferably 4 MPa or more, and is more preferably 400 MPa or less, even more preferably 300 MPa or less, even more preferably 200 MPa or less, particularly preferably 100 MPa or less, and most preferably 50 MPa or less.

[0028] The present film has the viscoelastic property (d) above, which gives it good heat resistance, and it is expected to provide excellent acoustic properties even in high-temperature environments. Storage modulus E' 100 is more preferably 1 MPa or more, even more preferably 1.5 MPa or more, even more preferably 2.5 MPa or more, and is more preferably 400 MPa or less, even more preferably 300 MPa or less, even more preferably 200 MPa or less, particularly preferably 100 MPa or less, and most preferably 50 MPa or less.

[0029] Furthermore, the film has the viscoelastic property (e) described above, which tends to reduce the change in elastic modulus with temperature and improve heat resistance. Furthermore, because the change in elastic modulus upon heating is small, sound quality is less likely to deteriorate in high-temperature environments, and sound reproduction is likely to be excellent from low to high temperatures. The above ratio (E' 100 / E' 20) is more preferably 0.5 or more, even more preferably 0.6 or more, and even more preferably 0.65 or more. Also, it is more preferably 0.99 or less, even more preferably 0.97 or less, even more preferably 0.95 or less, and particularly preferably 0.93 or less.

[0030] (peeling resistance) Another embodiment of the film of the present invention comprises a silicone layer (B) on at least one side of a curable silicone layer (A), and has viscoelastic properties with a storage modulus E' of 0.1 MPa to 500 MPa measured at a temperature of 20°C and a frequency of 10 Hz, and an interlayer peel strength between the silicone layer (A) and the silicone layer (B) of 0.5 N / 5 cm or more. This film has good interlayer peel resistance because the interlayer surfaces of the silicone layer (A) and the silicone layer (B) have a specific uneven structure. Specifically, the interlayer peel strength between the silicone layer (A) and the silicone layer (B) is preferably 0.5 N / 5 cm or more, more preferably 1 N / 5 cm or more, and even more preferably 2 N / 5 cm or more. When the interlayer peel strength is 0.5 N / 5 cm or more, delamination between the silicone layer (A) and the silicone layer (B) does not occur, improving handleability. In particular, delamination of the multilayer film can be prevented when the release film is peeled off before molding. There is no upper limit. Cohesive failure rather than delamination may occur during peeling. The interlayer peel strength can be measured by the method described in the examples.

[0031] The present film is curable due to the presence of a curable silicone layer (A). The present film may be photocurable, moisture-curable, or thermosetting, but is preferably thermosetting. The present film is thermosetting, which allows it to be cured when heated and shaped, thereby improving its formability. When the present film is thermosetting, its gel fraction increases when heated. In addition, it is sufficient that at least the middle layer of the present film is thermosetting, but the outermost and inner layers may also be thermosetting as appropriate.

[0032] In the present film, it is preferable that the silicone layer (B) has a crosslinked structure. When the silicone layer (B) has a crosslinked structure, shape retention before curing (i.e., before molding) is easily improved. Furthermore, it is preferable that the silicone layer (B) constitutes the outermost and innermost layers of the present film, and therefore it is preferable that the outermost and innermost layers have a crosslinked structure. When the outermost and innermost layers have a crosslinked structure, it is easy to improve shape retention without significantly impairing the flexibility of the film before curing. Furthermore, when the outermost and innermost layers have a crosslinked structure, it is easy to adjust the gel fraction of the outermost and innermost layers to within the desired range described above.

[0033] The thickness of the present film is not particularly limited, but is preferably from 5 μm to 500 μm, more preferably from 15 μm to 400 μm, and even more preferably from 30 μm to 300 μm. If the film thickness is within this range, it is possible to produce a molded product with a thickness suitable for acoustic components, particularly diaphragms.

[0034] When the present film is a multilayer film having three or more layers, the thickness of the intermediate layer is not particularly limited, but is preferably 3 μm to 300 μm, more preferably 5 μm to 200 μm, and even more preferably 20 μm to 150 μm. By setting the thickness of the intermediate layer at or above the lower limit, an uncured portion having a certain thickness and high flexibility is provided in the present film, thereby improving formability and conformability to the mold during molding. Furthermore, by setting the thickness at or below the upper limit, the highly flexible portion is prevented from becoming unnecessarily thick, which makes it easier to improve shape retention before molding. The thickness of the intermediate layer refers to the total thickness of the intermediate layer when there are two or more intermediate layers.

[0035] Furthermore, the ratio of the thickness of the intermediate layer to the thickness of the entire film (intermediate layer / entire film) is preferably 4 / 10 or more, more preferably 5 / 10 or more, and even more preferably 6 / 10 or more. By setting the thickness ratio (intermediate layer / entire film) at or above the above lower limit, a certain proportion of highly flexible portions is provided in the film, which makes it easier to improve formability and moldability during molding. Furthermore, the thickness ratio (intermediate layer / entire film) is preferably 9.8 / 10 or less. By setting the thickness ratio (intermediate layer / entire film) at or below the above upper limit, it makes it easier to make the outermost and innermost layers at or above a certain thickness.

[0036] The thickness of each of the outermost and innermost layers is not particularly limited, but is preferably 1 μm or more and 150 μm or less, more preferably 1 μm or more and 60 μm or less, and even more preferably 1 μm or more and 30 μm or less. By making the thickness of each of the outermost and innermost layers equal to or greater than the above-mentioned lower limit, the shape retention before molding can be improved and sticking to the mold can be prevented. Furthermore, by making the thickness equal to or less than the above-mentioned upper limit, it is possible to prevent the part having a certain hardness or more from becoming thicker than necessary, which makes it easier to improve the shapeability and conformability to the mold during molding.

[0037] The thickness of each of the outermost and innermost layers should be smaller than the thickness of the intermediate layer, and the ratio of the thickness of each of the outermost and innermost layers to the thickness of the intermediate layer (each outermost and innermost layer / intermediate layer) is preferably 1 / 50 or more and less than 1. If the thickness of each of the outermost and innermost layers is smaller than the thickness of the intermediate layer, a highly flexible portion of the film will be contained at a certain thickness ratio, which will make it easier to improve formability and mold-following ability during molding. Furthermore, if the ratio (each outermost and innermost layer / intermediate layer) is equal to or greater than the above lower limit, shape retention before molding can be improved. From these viewpoints, the ratio (each of the outermost and innermost layers / intermediate layer) is more preferably 1 / 50 or more and 3 / 5 or less, and even more preferably 1 / 5 or more and 2 / 5 or less.

[0038] The intermediate layer and the outermost and innermost layers of the present film are silicone layers, each composed of a silicone resin. The silicone resin may also be used in combination with other resins, provided that the effects of the present invention are not impaired. The other resins are preferably curable resins, more preferably thermosetting resins. Specific examples of preferred resins include epoxy resins, urethane resins, acrylic resins, phenolic resins, unsaturated polyester resins, polyimide resins, and melamine resins. In each layer of the present film, one or more of these resins may be used in combination with the silicone resin.

[0039] Because the film is made of a silicone film, it has good heat resistance, mechanical strength, etc., and is more likely to satisfy the viscoelastic properties (a) to (e) described above. In addition, the interlayer peel strength can be easily adjusted to fall within the desired range.

[0040] (organopolysiloxane) The silicone resin used in the silicone layers (A) and (B) includes organopolysiloxane. The organopolysiloxane has, for example, a structure represented by the following formula (ii). R n SiO (4-n) / 2 (ii) Here, R may be the same or different, and are substituted or unsubstituted monovalent hydrocarbon groups, preferably monovalent hydrocarbon groups having 1 to 12 carbon atoms, more preferably 1 to 8 carbon atoms, and n is a positive number of 1.95 to 2.05.

[0041] Examples of R include alkyl groups such as a methyl group, ethyl group, propyl group, butyl group, hexyl group, and dodecyl group; cycloalkyl groups such as a cyclohexyl group; alkenyl groups such as a vinyl group, allyl group, butenyl group, and hexenyl group; allyl groups such as a phenyl group and tolyl group; aralkyl groups such as a β-phenylpropyl group; and groups in which some or all of the hydrogen atoms bonded to the carbon atoms of these groups have been substituted with halogen atoms, cyano groups, or the like, such as a chloromethyl group, a trifluoropropyl group, and a cyanoethyl group.

[0042] The organopolysiloxane preferably has its molecular chain terminals blocked with trimethylsilyl groups, dimethylvinyl groups, dimethylhydroxysilyl groups, trivinylsilyl groups, or the like. The organopolysiloxane preferably has at least two alkenyl groups in the molecule. Specifically, it is preferred that the alkenyl groups account for 0.001 mol % to 5 mol %, preferably 0.005 mol % to 3 mol %, more preferably 0.01 mol % to 1 mol %, and particularly preferably 0.02 mol % to 0.5 mol % of the R groups, and it is particularly preferred that the organopolysiloxane contains vinyl groups. The organopolysiloxane is basically a linear diorganopolysiloxane, but may be partially branched. It may also be a mixture of two or more different molecular structures.

[0043] In the outermost and innermost layers (silicone layer (B)), the organopolysiloxane is preferably crosslinked with a crosslinking agent, preferably an organic peroxide. Therefore, each of the outermost and innermost layers is preferably a cured product obtained by curing a resin composition comprising an organopolysiloxane and a crosslinking agent such as an organic peroxide. In this case, the outermost and innermost layers are preferably cured so that the gel fraction falls within the desired range described above. Therefore, the organic peroxide incorporated into the outermost and innermost layers is mostly decomposed, and either no organic peroxide is contained in each of the outermost and innermost layers, or only a small amount is contained.

[0044] On the other hand, in the intermediate layer (silicone layer (A)), the organopolysiloxane is preferably in an uncrosslinked state or, if crosslinked, in a partially crosslinked state. Therefore, the intermediate layer is preferably made of a resin composition containing an organopolysiloxane and a crosslinking agent such as an organic peroxide. In this case, the intermediate layer is preferably in an uncured state or, if cured, in a semi-cured state so that the gel fraction falls within the desired range. Therefore, the organic peroxide blended into the intermediate layer is preferably contained in the intermediate layer in the organic peroxide state with almost no decomposition.

[0045] Examples of organic peroxides include alkyl peroxides such as di-t-butyl peroxide, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane, and 2,5-dimethyl-2,5-bis(t-butylperoxy)hexane, and aralkyl peroxides such as 2,4-dicumyl peroxide. From the viewpoints of crosslinking rate and safety, alkyl peroxides, particularly 2,5-dimethyl-2,5-di(t-butylperoxy)hexane, are preferred.

[0046] The amount of organic peroxide in the resin composition forming each of the silicone layers (A) and (B) is preferably 0.01% by mass to 10% by mass, more preferably 0.03% by mass to 5% by mass, even more preferably 0.05% by mass to 4% by mass, particularly preferably 0.1% by mass to 3% by mass, and particularly preferably 0.3% by mass to 2% by mass. Within this range, a composition with a sufficient curing rate tends to be obtained safely. As mentioned above, the organic peroxide contained in the resin composition is almost completely decomposed and hardly present in the outermost and innermost layers, but it is preferable that the organic peroxide be present in the intermediate layer within the above-mentioned range.

[0047] The resin composition is preferably a millable type containing an organopolysiloxane. Millable type resin compositions are non-liquid (e.g., solid or paste-like) and lack self-flowing properties at room temperature (25°C) in an uncured state, but can be uniformly mixed using a kneader described below. The use of a millable type resin composition in this film improves productivity when the resin composition is processed into an intermediate layer or an outermost or outermost layer, as described below.

[0048] Furthermore, as described above, the resin compositions used in the intermediate layer and the outermost and innermost layers may contain resins other than silicone resins (organopolysiloxanes), and in this case, the outermost and innermost layers may be layers formed by curing a resin composition containing a resin and a crosslinking agent so that the gel fraction falls within a desired range. Similarly, the intermediate layer may be formed from a resin composition containing a resin and a crosslinking agent, but in this case, the resin composition may be uncured or semi-cured so that the gel fraction falls within the above-mentioned predetermined range.

[0049] The silicone layer (A) and the silicone layer (B) of the present invention may each contain a filler such as a silica-based filler. By incorporating a filler into each layer of the present film, the film's storage modulus, peel resistance, and other mechanical properties can be more easily adjusted to an appropriate range. Furthermore, the use of a filler makes it easier to adjust the viscosity and hardness of the resin composition, and also makes it easier to optimize the balance between the flowability and secondary processability of the resin composition. Another advantage is that the hardness can be more easily adjusted to suit the design and acoustic characteristics of the acoustic component. In addition, the filler constitutes a part of the gel fraction in the measurement of the gel fraction, and the gel fraction of each layer increases by including the filler. Even if the gel fraction increases by including the filler, the hardness of each layer can be increased, just as in the case where the gel fraction increases due to crosslinking.

[0050] Examples of silica-based fillers include fumed silica and precipitated silica, and may be silica-based fillers whose surfaces have been treated with a silane coupling agent. The content of the filler in each layer is, for example, 10% by mass to 50% by mass, preferably 15% by mass to 40% by mass, and more preferably 20% by mass to 35% by mass, based on the total amount of the resin composition constituting each layer. The average particle size of the filler is, for example, 0.01 μm to 20 μm, preferably 0.1 μm to 10 μm, and more preferably 0.5 μm to 5 μm. The average particle size of the filler can be measured as the median diameter (D50) using a particle size distribution analyzer using a laser diffraction method or the like.

[0051] In the present invention, the resin composition for forming each layer may contain various additives such as a heat stabilizer, an antioxidant, an ultraviolet absorber, a light stabilizer, an antibacterial / antifungal agent, an antistatic agent, a lubricant, a pigment, a dye, a flame retardant, and an impact resistance modifier, within a range that does not impair the effects of the present invention.

[0052] In the present film, the silicone resin compositions for forming the outermost layer and the innermost layer may have the same composition, or may have different compositions.Similarly, the silicone resin composition for forming the intermediate layer may have the same composition as the resin compositions for forming the outermost layer and the innermost layer, or may have different compositions.Note that the composition of the silicone resin composition here means the composition of the resin composition before it is cured.

[0053] In the present invention, commercially available organopolysiloxanes can be used. Alternatively, commercially available mixtures containing an additive such as a silica-based filler in addition to the organopolysiloxane can be used. Specifically, products under the trade names "KE-597-U" and "KE-594-U" manufactured by Shin-Etsu Chemical Co., Ltd. can also be used.

[0054] [Film with release film] The present film described above may be provided with a release film and used as a film with a release film. The film with a release film includes the present film described above and a release film provided on at least one side of the present film. In the case of a film with a release film, it is preferable that a release film is provided on both sides of the film. The release film is laminated on the outermost layer, the innermost layer, or both of the outermost and innermost layers of the film.

[0055] The release film may be a resin film or a resin film having a release layer on at least one side of which release treatment has been performed. When the release film has a release layer, it is preferable that the release layer be laminated on the present film so that the release layer is in contact with the outermost surface and the inner surface of the present film. Examples of resins used for the resin film include polyolefin resins such as polypropylene, acrylic resins, polystyrene resins, polyacetal resins, polyamide resins, polyester resins, polycarbonate resins, ABS resins, polyether ether ketone resins, etc. Among these, polyester resins are preferred, and polyethylene terephthalate resins are particularly preferred. The thickness of the release film is not particularly limited, but is preferably 5 μm or more and 100 μm or less, more preferably 7 μm or more and 80 μm or less, and even more preferably 10 μm or more and 50 μm or less.

[0056] The present film is protected by the release film attached thereto. This prevents the film from being scratched during transportation, etc. As described below, the release film may be the release film laminated on the outermost and innermost layers when the present film is manufactured, or may be laminated separately on the manufactured present film. Furthermore, this film is molded, for example, by extrusion molding as described below, and the release film is preferably peeled off from the film during molding and then set in a mold such as a die. Even without a release film, this film has good shape retention even before curing because it has the specified outermost and innermost layers as described above. Furthermore, as described above, this film prevents delamination between the silicone layer (A) and the silicone layer (B) when the release film is peeled off. As will be described later, by using a release film having an uneven surface, when a silicone layer is laminated on the release film, the uneven surface of the release film can be transferred to the silicone layer.

[0057] [Manufacturing method of this film] The method for producing the present film is described below, but the method for producing the present film is not limited to the method described below. One embodiment of the method for producing the present film is a method for producing a film in which the arithmetic mean height (Sa) of at least one surface of the silicone layer (B) is 500 to 4000 nm, and a curable silicone layer (A) is laminated on said one surface, and the film has viscoelastic properties such that the storage modulus E' is 0.1 MPa to 500 MPa at a measurement temperature of 20°C and a frequency of 10 Hz. Another embodiment of the method for producing the present film is a method for producing a film in which the arithmetic mean height (Sa) of both sides of the silicone layer (B) is 500 to 4000 nm, and a curable silicone layer (A) is laminated on each of the two sides, and the film has viscoelastic properties such that the storage modulus E' is 0.1 MPa to 500 MPa at a measurement temperature of 20°C and a frequency of 10 Hz. The present film can be formed by a general forming method, for example, lamination forming, extrusion forming such as co-extrusion, coating, or a combination of these. Among these, lamination forming is preferred in consideration of the ease of forming a multilayer structure with an outermost layer, a back layer, and an intermediate layer. As a method for forming the irregularities, a method is mentioned in which a silicone layer (B) having irregularities formed thereon so that the arithmetic mean height (Sa) is in a specific range of 500 to 4000 nm is prepared, and then a silicone layer (A) is laminated on this. Still another method is mentioned in which a silicone layer (A) having irregularities formed thereon so that the arithmetic mean height (Sa) is in a specific range is prepared, and then a silicone layer (B) is laminated on this, and the irregularities of the silicone layer (A) are transferred to the silicone layer (B) to form the irregularities. The method for forming the unevenness is not particularly limited, and the unevenness may be formed by embossing or the like, or a silicone layer may be formed on a release film having unevenness and the unevenness of the release film may be transferred to the silicone layer. An example of a film manufacturing method using lamination molding will be specifically described below. In the following, a method will be described in which, in a film having a three-layer structure of an outermost layer / an intermediate layer / an innermost layer, the unevenness of a release film is transferred to the silicone layer (B) (outermost / innermost layer) to form an uneven silicone layer (B), and then the silicone layer (A) is laminated on this, but the method is not limited to the following.

[0058] When lamination molding is used, it is preferable to first prepare the outermost layer and the innermost layer, and then laminate an intermediate layer between these outermost layer and the innermost layer. More specifically, first, a resin composition for obtaining the outermost layer and the innermost layer (resin composition for the outermost layer or the innermost layer), and a resin composition for obtaining the intermediate layer (resin composition for the intermediate layer) are prepared.

[0059] Each resin composition is not particularly limited, but can be obtained, for example, by kneading the materials that constitute the resin composition. As a kneader used for kneading, a known kneader such as an extruder such as a single-screw or twin-screw extruder, a calendar roll such as a two-roller or three-roller calender roll, a roll mill, a plastomill, a Banbury mixer, a kneader, or a planetary mixer can be used. The kneading temperature is adjusted as appropriate depending on the type and mixing ratio of the resin, and the presence and type of additives. In order to facilitate kneading by appropriately lowering the viscosity of the resin while suppressing crosslinking (curing), the kneading temperature is preferably 20°C or higher and 150°C or lower, more preferably 30°C or higher and 140°C or lower, even more preferably 40°C or higher and 130°C or lower, particularly preferably 50°C or higher and 120°C or lower, and especially preferably 60°C or higher and 110°C or lower. The kneading time may be long enough to uniformly mix the materials constituting the resin composition, and may be, for example, several minutes to several hours, and preferably 5 minutes to 1 hour.

[0060] The resin composition for the outermost or innermost layer prepared as described above may be laminated on a release film by a conventional method to obtain a laminate, and then the laminate may be heated or otherwise cured to cure the resin composition. This results in a laminate (hereinafter also referred to as a "laminated film") in which the outermost or innermost layer is laminated on the release film. In the laminate film, the outermost or innermost layer preferably forms a crosslinked structure upon curing, and the gel fraction is preferably 80% or more as described above. When the release film has a release-treated surface, the resin composition for the outermost layer may be laminated on the release-treated surface of the release film. In addition, in this manufacturing method, as described above, by laminating the resin composition for the outermost and innermost layers on a release film and curing it, the surface of the obtained outermost and innermost layers has a shape corresponding to the surface shape of the release film. Therefore, by forming an uneven shape on the surface of the release film in advance, unevenness is imparted to the surface of the outermost and innermost layers (silicone layer (B)).

[0061] Next, an intermediate layer formed from the intermediate layer resin composition is laminated between the laminate films to obtain the present film. Specifically, the intermediate layer resin composition is introduced in an uncured or semi-cured state between laminate films unwound from two directions, for example, between a pair of rolls. Here, the intermediate layer resin composition is introduced between the laminate films by extruding it from a T-die using an extruder or the like. Furthermore, each laminate film is preferably unwound so that the outermost layer and the innermost layer face each other. Then, the thickness is adjusted by the gap between the rolls as necessary to obtain a laminate in which an uncured or semi-cured intermediate layer is formed between the laminate films. The laminate preferably has a laminate structure of release film / outermost layer / intermediate layer / innermost layer / laminate film, and becomes the above-mentioned film with release film.

[0062] The resin compositions for the silicone layer (A) and the silicone layer (B) can be obtained, for example, by kneading the materials that make up the resin composition. The kneading machine used can be a known kneader such as an extruder such as a single-screw or twin-screw extruder, a calendar roll such as a two-roller or three-roller calendar roll, a roll mill, a plastomill, a Banbury mixer, a kneader, or a planetary mixer. The kneading temperature is adjusted as appropriate depending on the type and mixing ratio of the resin, and the presence and type of additives. In order to facilitate kneading by appropriately lowering the viscosity of the resin while suppressing crosslinking (curing), the kneading temperature is preferably 20°C or higher and 150°C or lower, more preferably 30°C or higher and 140°C or lower, even more preferably 40°C or higher and 130°C or lower, particularly preferably 50°C or higher and 120°C or lower, and especially preferably 60°C or higher and 110°C or lower. The kneading time may be long enough to uniformly mix the materials constituting the resin composition, and may be, for example, several minutes to several hours, and preferably 5 minutes to 1 hour.

[0063] [Molded products] The film can be molded into various articles by being shaped in a mold such as a die and cured. Typically, the film is molded into various articles by being shaped in a mold. Curing can be performed according to the film's properties, and can be performed by heating, light irradiation, moisture application, or a combination of these, but is preferably performed by heating. The molded article is preferably an acoustic component, more preferably a diaphragm. When a molded article is to be obtained from the present film, it is preferable to carry out at least the following steps 1 and 2. Step 1: Heating the film, forming it into a mold, and curing the film Step 2: Peeling the molded and cured film (i.e., molded product) from the mold

[0064] Each step will be described in more detail below. (Process 1) In step 1, the film is heated and molded in a mold, and the film is cured to form a molded article. The molded article is preferably formed into a desired shape using a mold. The molding in step 1 is not particularly limited and may be performed by any molding method such as vacuum molding, pressure molding, or press molding. Among these, press molding is preferred because it is easier to form.

[0065] A mold may be prepared according to the molding method, and the mold may have projections and recesses corresponding to the shape of the molded product to be manufactured. A metal mold (metal die) is typically used as the mold, but a resin mold may also be used. For example, as described below, if the molded product (acoustic component) has at least one of a dome shape and a cone shape, the mold may have projections and recesses corresponding to the dome shape or the cone shape. Furthermore, if the molded product (acoustic component) has a tangential edge on its surface, the mold may have projections and recesses corresponding to the tangential edge.

[0066] As described above, a release film may be attached to the film, and the film may be set in the mold after the release film has been peeled off as described above.

[0067] In step 1, the heated film may be shaped in a mold. For example, the film may be placed on a mold and shaped in the mold while being heated, or the film may be preheated and placed on a mold and then shaped in the mold, or a combination of these may be used. The film may be heated by any method. For example, when heating a film placed on a mold, the mold may be heated and the film may be heated by heat transfer, or other methods may be used.

[0068] The heating temperature during shaping or curing is preferably 180° C. or higher and 260° C. or lower, more preferably 190° C. or higher and 250° C. or lower, and even more preferably 200° C. or higher and 240° C. If the temperature during shaping or curing is within this range, the film tends to be able to cure at a sufficient rate without melting or deforming due to heat.

[0069] The shaping time is preferably 1 second to 5 minutes, more preferably 5 seconds to 4 minutes, even more preferably 10 seconds to 3 minutes, and particularly preferably 20 seconds to 2 minutes. If the heat treatment time during shaping is within this range, sufficient curing tends to be achieved while maintaining productivity. The film is preferably cured while being shaped, but may be cured after shaping without any particular limitation. The shaping time refers to the time during which the film is shaped or cured in the mold, and does not include the time required for mold movement before and after shaping, or the time required for releasing the laminate from the mold.

[0070] (Process 2) In step 2, the film formed and cured in step 1 is peeled from the mold to obtain a molded article. In the present invention, the gel fraction of the silicone layer (A) is below a certain value, which results in high shapability and high conformability of the film to the mold. As a result, molded articles can be produced with high molding precision. Furthermore, the provision of the silicone layer (B) gives the film excellent shape retention, good handling even without a release film, and the film can be easily set in a mold while maintaining its shape even without a release film. Furthermore, because no release film is laminated, the step of peeling the release film from the molded product can be omitted, making mass production easier. Furthermore, in this film, the arithmetic mean height (Sa) of at least one interlayer surface between the silicone layer (A) and the silicone layer (B) is 500 to 4000 nm, and therefore the adhesion between the silicone layer (A) and the silicone layer (B) is high, and no peeling occurs between the layers in the above steps 1 and 2.

[0071] In the present invention, the gel fraction of the molded article obtained from the film may be 80% or more. A gel fraction of 80% or more makes it easier to obtain a molded article having a storage modulus and mechanical strength suitable for an acoustic component. The gel fraction of the molded article is more preferably 85% or more, and even more preferably 90% or more. The upper limit of the gel fraction of the molded article is not particularly limited, and it may be 100% or less, but it may generally be lower than 100%, for example, 99% or less. The gel fraction of the molded article refers to the gel fraction of the entire molded article, and may be measured by cutting the molded article in a direction parallel to the thickness direction and sampling it. Details of the method for measuring the gel fraction are as described above.

[0072] [Film uses] As described above, the film of the present invention is preferably used for acoustic components, and is particularly suitable for use as a diaphragm. The acoustic component of the present invention is obtained by curing the film, and specifically may be the molded product described above. The diaphragm is more preferably a speaker diaphragm, and is particularly suitable for use as a micro-speaker diaphragm for mobile phones and the like.

[0073] This film can be formed into various acoustic components such as diaphragms by being appropriately shaped. The acoustic member may have, for example, at least a portion thereof in a dome or cone shape. The acoustic member may also have a tangential edge on its surface. When the acoustic member has a dome or cone shape or a tangential edge, it is preferably used as a diaphragm, more preferably as a speaker diaphragm.

[0074] (diaphragm) To explain the diaphragm in more detail, the shape of the diaphragm is not particularly limited and can be any shape, such as a circle, an ellipse, or an oval. A diaphragm generally has a body that vibrates in response to an electrical signal and an edge surrounding the body. The body of the diaphragm is usually supported by the edge. The shape of the diaphragm may be a dome or a cone, as described above, or a combination of these shapes, or any other shape commonly used for diaphragms.

[0075] The present film may form at least a portion of the diaphragm, and for example, the body or edge of the diaphragm may be formed by the present film, and the edge or body of the diaphragm may be formed by another member. Of course, both the body and the edge may be integrally formed by the present film, or the entire diaphragm may be formed by the present film.

[0076] 1 is a diagram showing the structure of a diaphragm 1 according to one embodiment of the present invention, and is a cross-sectional view of the diaphragm 1, which is circular in plan view, cut along a plane passing through the center line of the circle. The diaphragm 1 is a diaphragm for a micro speaker. As shown in FIG. 1, the diaphragm 1 has a dome portion (body) 1a at the center, a recessed portion 1b to be attached to a voice coil 2, a peripheral portion (edge) 1c, and an external attachment portion 1d on the outer periphery to be attached to a frame or the like.

[0077] FIG. 2 is a diagram showing the structure of diaphragm 11 according to another embodiment of the present invention, and is a cross-sectional view of diaphragm 11, which is circular in plan view, cut along a plane passing through the center line of the circle. Diaphragm 11 is a diaphragm for a micro-speaker. As shown in FIG. 2, diaphragm 11 has a dome-shaped dome portion (body) 11a at its center, a recessed portion 11b attached to voice coil 2, a cone portion 11j machined into a cone shape, and a peripheral portion (edge) 11c. As shown in diaphragm 11, the diaphragm may have a portion machined into a dome shape and the remaining portion machined into a cone shape. Note that diaphragm 11 may have peripheral portions 11c attached directly to a frame or the like, or may be attached to a frame or the like via another member.

[0078] As described above, a tangential edge may be provided on the surface of the diaphragm. The tangential edge may be, for example, a groove having a V-shaped cross section. FIG. 3 shows a plan view of diaphragm 21 according to another embodiment of the present invention. Diaphragm 21 has tangential edge portion 21g, in which multiple tangential edges 21e are provided on the outer periphery of circular dome portion (body) 21a, and tangential edge portion 21h, in which multiple tangential edges 21f are provided around tangential edge portion 21g. Note that while FIG. 3 shows an example in which two tangential edge portions are provided along the radial direction, only one tangential edge portion or three or more tangential edge portions may be provided along the radial direction.

[0079] As mentioned above, the diaphragm is preferably a speaker diaphragm, particularly a micro speaker diaphragm. From the viewpoint of suitable use as a micro speaker diaphragm, the size of the diaphragm is such that the maximum diameter is 25 mm or less, preferably 20 mm or less, and the maximum diameter is preferably 5 mm or more. Note that the maximum diameter refers to the diameter when the diaphragm is circular, and refers to the major axis when the diaphragm is elliptical or oval.

[0080] The diaphragm may be formed from the present film alone, or may be formed from a composite material of the present film and another material. For example, as described above, either the edge or the body may be formed from another material.

[0081] Furthermore, in order to improve the suitability for secondary processing of the diaphragm, its dust resistance, or to adjust its acoustic characteristics and improve its design, the surface of the diaphragm may be further treated as appropriate by coating it with an antistatic agent, vapor-depositing a metal, sputtering it, coloring it (black, white, etc.), etc. Furthermore, it may be appropriately laminated with a metal such as aluminum, or combined with a nonwoven fabric, etc.

[0082] (acoustic transducer) The acoustic transducer of the present invention is an acoustic transducer comprising the above-mentioned acoustic member, preferably a diaphragm. The acoustic transducer is typically an electro-acoustic transducer, and examples thereof include a speaker, a receiver, a microphone, and an earphone. Of these, the acoustic transducer is preferably a speaker, and a micro-speaker for a mobile phone or the like is suitable. [Example]

[0083] The present invention will be described in more detail below with reference to examples, but the present invention is not limited thereto.

[0084] [Evaluation and measurement methods] In this example, various physical properties were measured and the film was evaluated as follows.

[0085] (1) Measurement of gel fraction According to the method described in the specification, the gel fractions of the entire film before curing, the outermost and innermost layers of the film before curing, and the entire film after curing were measured. The gel fraction of the entire film was measured by cutting a sample parallel to the thickness direction of the film. The gel fraction of the middle layer of the film before curing was calculated from the ratio of the gel fraction of the entire film and the outermost and innermost layers to the layer thickness.

[0086] (2) Storage modulus E' Test pieces measuring 4 mm x 8 cm were cut from the pre-cured and cured films obtained in each Example and Comparative Example to obtain measurement samples. Using these test samples, a viscoelasticity spectrometer "DVA-200 (manufactured by IT Measurement & Control Co., Ltd.)" was used in accordance with JIS K7244-4:1999. The measurement mode was tension, the frequency was 10 Hz, the strain was 0.1%, the temperature range was -100 to 300°C, and the temperature was raised at a heating rate of 3°C / min. The storage modulus of the pre-cured film was measured at 20°C. The storage modulus of the cured film was also measured at 20°C and 100°C. The measurements were performed for the TD.

[0087] (3) Surface roughness (arithmetic mean height: Sa, root mean square height: Sq) The arithmetic mean height (Sa) and root mean square height (Sq) of the silicone layer (B) used in each example and comparative example were measured using a 3D white light interference microscope, "Contour2.0" (manufactured by Bruker Japan), under the conditions of an eyepiece magnification of 1.0, an objective lens magnification of 20, and a measurement area of ​​235 μm length x 313 μm width. After smoothing with a Gaussian function, the arithmetic mean height and root mean square height of the surface were measured. The observation mode was "Wave mode."

[0088] (4) Shape retention The shape retention of the pre-cured films obtained in each Example and Comparative Example was evaluated. When the film was peeled from the release film and used for various evaluations and measurements, the film was evaluated as "good" if it could be easily handled because it maintained its shape, and evaluated as "poor" if it could not maintain its shape and bent during handling, causing the film to become tangled or break.

[0089] (5) Whether there are any tears or not In each example and comparative example, when the present film was produced, evaluation was performed in a state in which a release film was laminated on the outermost and innermost layers. The presence or absence of tearing was evaluated in the process of manually peeling the outermost and innermost release films from the obtained pre-cured present film. Films in which the release films could be peeled off without tearing were evaluated as "Good", and films in which a part of the film was torn due to being caught by the release films were evaluated as "Poor". In addition, when various evaluations and measurements were performed other than for the presence or absence of tear, the film was used with the release film removed.

[0090] (6) Peel resistance (interlaminar peel strength) A 5 cm x 10 cm test piece was cut from the uncured film obtained in each Example and Comparative Example to obtain a measurement sample. The interlayer peel strength between the silicone layer (A) and the silicone layer (B) of each measurement sample was measured using a universal testing machine (Shimadzu Corporation). Measurements were performed using a 180° peel test at 200 mm / min with a chuck distance of 25 mm and at 23°C.

[0091] (7) Moldability / formability A test piece measuring approximately 7 cm x 10 cm was cut out from the film obtained in each example and comparative example to serve as an evaluation sample. The evaluation sample was sandwiched between a dome-shaped diaphragm mold with a tangential edge that had been preheated to 240°C and pressed at a pressure of 0.6 MPa. The pressurized state was maintained for 30 seconds, and the sample was then removed from the mold. If the moldability and formability are good, mark it as "Good", and if not, mark it as "Poor". (8) Adhesion to the mold As in the evaluation of moldability and shapability described above, test pieces of approximately 7 cm x 10 cm were cut out from the films obtained in each Example and Comparative Example to serve as evaluation samples. The evaluation samples were sandwiched between a diaphragm mold preheated to 240°C and pressed at a pressure of 0.6 MPa. The pressurized state was maintained for 30 seconds, and the samples were then removed from the mold.

[0092] Example 1 A 20μm thick silicone rubber (TSE2571-5U) was laminated between a pair of PET films with an arithmetic mean height (Sa) of 1600nm for the top and bottom layers, and the cured laminated film was prepared. One side of the PET film was peeled off to expose the cured silicone. At this point, the arithmetic mean height of the PET film was transferred to the silicone, and the arithmetic mean height (Sa) of the silicone became 1600nm.

[0093] 100 parts by mass of a mixture containing organopolysiloxane and silica (trade name "KE-597-U", manufactured by Shin-Etsu Chemical Co., Ltd.) and 1 part by mass of an organic peroxide (trade name "C-8B", manufactured by Shin-Etsu Chemical Co., Ltd., 2,5-dimethyl-2,5-di(t-butylperoxy)hexane, containing approximately 40% by mass of organic peroxide) were kneaded using a planetary mixer at a temperature of 90°C for 10 minutes to obtain a millable type resin composition (1). The two laminated films obtained above were fed along two 100 mm diameter calendar rolls with the exposed cured silicone facing inward. Resin composition (1) was added between the laminated films between the calendar rolls, and a bank was formed on the rolls at room temperature of 25 °C and a roll temperature of 90 °C. A film with release films was obtained consisting of release film / outermost layer / intermediate layer / innermost layer / release film so that the thickness of the intermediate layer was 100 μm. The two release films were peeled off from the resulting film with release films to obtain this film. The gel fractions of the outermost and innermost layers and intermediate layer of this film, the storage modulus of this film at 20 °C, and the interlayer peel strength between the intermediate layer (silicone layer (A)) and the outermost and innermost layer (silicone layer (B)) were measured. The measurement results are shown in Table 1.

[0094] Assuming the production of molded articles by extrusion molding, the film obtained above was cured using a simple press molding method in which it was heated at 220°C for 2 minutes and press-molded using two flat plates at a pressure of 0.2 MPa. The gel fraction (whole film) and storage modulus of the cured film were measured.

[0095] Example 2 and Comparative Example 1 Films were prepared in the same manner as in Example 1, except that for the outermost and innermost layers, in Example 2 a PET film having an arithmetic mean height (Sa) of 2200 nm was used, and in Comparative Example 1 a PET film with a smooth surface was used. The gel fraction of the outermost and innermost layers and the middle layer of this film, the storage modulus of this film at 20°C, and the interlayer peel strength between the middle layer (silicone layer (A)) and the outermost and innermost layers (silicone layer (B)) were measured. The measurement results are shown in Table 1.

[0096] Assuming the production of molded articles by extrusion molding, the film obtained above was cured by a simple press molding method using two flat plates at a pressure of 0.2 MPa while heating at 220°C for 2 minutes. The gel fraction (whole film), storage modulus, and interlayer peel strength of the cured film were measured.

[0097] [Table 1]

[0098] It is clear that the films of the above examples have high peel strength between the silicone layer (A) and the silicone layer (B) and good peel resistance. On the other hand, the film of Comparative Example 1, which has no unevenness between the layers, has low peel strength and poor peel resistance. In fact, when the release film was peeled off from the film with release film obtained in Comparative Example 1, peeling occurred between the silicone layer (A) and the silicone layer (B). Furthermore, when the adhesion to the mold was evaluated using the above method, the films of Examples 1 and 2 were easier to remove from the mold without sticking to the mold than the film of Comparative Example 1 when removing the evaluation sample from the mold.

Claims

1. A curable silicone layer (A) is provided on at least one side thereof with another silicone layer (B), It has the following viscoelastic property (a): The film has an arithmetic mean height (Sa) of the surface of the silicone layer (B) facing the silicone layer (A) of 500 to 4000 nm. (a) The storage modulus E' at a measurement temperature of 20°C and a frequency of 10 Hz is 0.1 MPa to 500 MPa.

2. 2. The film of claim 1, having a gel fraction of 90% or less.

3. 3. The film according to claim 1, wherein the silicone layer (B) has a gel fraction of 80% or more.

4. The film according to any one of claims 1 to 3, wherein the silicone layer (B) has the following viscoelastic property (b): (b) The storage modulus E' is 0.1 MPa to 500 MPa at a measurement temperature of 20°C and a frequency of 10 Hz.

5. The film according to any one of claims 1 to 4, which has thermosetting properties.

6. The film according to any one of claims 1 to 5, which has a crosslinked structure.

7. The film according to any one of claims 1 to 6, comprising the silicone layer (B) on both sides of the silicone layer (A).

8. The film according to any one of claims 1 to 7, which has the following viscoelastic properties (c) to (e) after curing: (c) Storage modulus E′ at a measurement temperature of 20° C. and a frequency of 10 Hz ２０ is 0.1 MPa or more and 500 MPa or less. (d) Storage modulus E′ at a measurement temperature of 100° C. and a frequency of 10 Hz １００ is 0.1 MPa or more and 500 MPa or less. (e) the storage modulus E′ ２０ The storage modulus E' １００ The ratio (E' １００ / E' ２０ ) is 0.4 or more and 1.0 or less.

9. The film according to any one of claims 1 to 8, which is a film for a diaphragm.

10. A film with a release film, comprising: the film according to any one of claims 1 to 9; and a release film provided on at least one surface of the film.

11. A diaphragm obtained by curing the film according to any one of claims 1 to 9.

12. A laminate obtained by placing the film according to any one of claims 1 to 9 in a mold and thermoforming it.

13. A molded article obtained by peeling the laminate according to claim 12 from a mold.

14. A diaphragm comprising the molded article according to claim 13.

15. An acoustic transducer comprising the diaphragm according to claim 11 or 14.

16. A method for producing a film having the following viscoelastic property (a), which is obtained by laminating a curable silicone layer (A) on at least one surface of a silicone layer (B) having an arithmetic mean height (Sa) of 500 to 4000 nm: (a) The storage modulus E' at a measurement temperature of 20°C and a frequency of 10 Hz is 0.1 MPa to 500 MPa.

17. A method for producing a film having the following viscoelastic property (a), which is obtained by laminating a curable silicone layer (A) on each of both sides of a silicone layer (B) having an arithmetic mean height (Sa) of 500 to 4000 nm: (a) The storage modulus E' at a measurement temperature of 20°C and a frequency of 10 Hz is 0.1 MPa to 500 MPa.

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