Laminate

Abstract

To provide a laminate having a silicone layer, which has little dimensional change even when used in a high temperature environment.SOLUTION: There is provided a laminate having a silicone layer and a polyimide layer, including at least one polyimide layer arranged closer to an outermost surface than the silicone layer, in which a tensile storage elastic modulus of the polyimide layer at 300°C is 2 GPa or more.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a laminate having at least two resin layers, which can be used, for example, as a release agent, cushioning material, or anti-slip material, and which has a silicone layer and a polyimide layer. [Background technology]

[0002] Traditionally, silicones, such as silicone rubber and silicone resin, and especially millable-type silicone rubber, have been widely used as release agents, cushioning materials, and anti-slip materials due to their excellent heat resistance and electrical properties. For example, they are known to be used as release agents or cushioning materials in press molding and other processes in the manufacturing of flexible printed circuit boards (FPCs), solid-state batteries, and semiconductors. They are also sometimes used as anti-slip materials for transport carriers in reflow processes.

[0003] When silicone consisting solely of a silicone layer, such as silicone rubber, is used as a release agent in press molding, deformation occurs, leading to poor assembly dimensional accuracy and wrinkles, resulting in workability problems. Therefore, silicone is known to be used as a laminate by integrating it with a plastic film. In this case, the plastic film used is, for example, a polyester resin film, as disclosed in Patent Document 1. Furthermore, to improve adhesion, silicone is often laminated to the polyester resin film via an undercoat layer or the like. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 11-20082 [Overview of the project] [Problems that the invention aims to solve]

[0005] In recent years, press molding used in solid-state batteries, semiconductors, and other applications has tended to involve higher molding temperatures and pressures. For example, press molding may be performed at temperatures of around 100-300°C and pressures of around 50-1000 MPa. Furthermore, silicone film is being considered for use as a release agent or cushioning material in the manufacturing process of flexible printed circuits (FPCs), but the press molding temperature in FPC manufacturing also tends to be high. As a result, even when silicone film (silicone layer) is integrated with other plastic films such as polyester film to form a laminate, its heat resistance is insufficient, and when used in press molding during the manufacturing of FPCs, significant dimensional deformation may occur due to the pressure.

[0006] Furthermore, when used as a transport carrier in the reflow process, a laminate of silicone film on a metal plate is often used. However, from the perspective of weight reduction, the use of a resin sheet instead of a metal plate is also being considered. However, in the reflow process, the transport carrier is also heated to high temperatures, and the laminate of silicone film and polyester film mentioned above has insufficient heat resistance, resulting in large dimensional deformation, making practical application difficult.

[0007] Therefore, the objective of the present invention is to provide a laminate having a silicone layer that exhibits minimal dimensional change even when used in a high-temperature environment. Furthermore, the present invention aims to provide a laminate having a resin layer (A) that exhibits minimal dimensional change even when used in high-temperature environments and is suitable for use in specific applications. [Means for solving the problem]

[0008] As a result of diligent research, the inventors have found that the above problems can be solved by applying, for example, a polyimide layer as the resin layer to be integrated with a silicone layer or a resin layer (A) having a tensile storage modulus of 100 MPa or less at 23°C, which is suitably used in a specific application, and by setting the tensile storage modulus of the resin layer (B), such as the polyimide layer, at 300°C to a certain value or higher, and have completed the present invention as follows. That is, the present invention provides the following [1] to

[20] . [1] A laminate comprising a silicone layer and a polyimide layer, having at least one polyimide layer disposed closer to the outermost surface than the silicone layer, The laminate, wherein the storage modulus in tension at 300 ° C of the polyimide layer is 2 GPa or more. [2] The laminate according to [1] above, wherein at least one outermost surface is the polyimide layer. [3] The laminate according to [1] or [2] above, wherein the temperature at which the weight loss is 2% by thermogravimetric measurement of the polyimide layer is 260 ° C or higher. [4] The laminate according to any one of [1] to [3] above, wherein the storage modulus in tension at 23 ° C of the polyimide layer is 3.7 GPa or more. [5] The laminate according to any one of [1] to [4] above, wherein the linear expansion coefficient of the polyimide layer is 33 × 10 -6 / ° C or less. [6] The laminate according to any one of [1] to [5] above, wherein the arithmetic mean roughness (Ra) of the outermost surface of the laminate composed of the polyimide layer is 26 nm or less. [7] The laminate according to any one of [1] to [6] above, wherein the silicone layer contains a silicone elastomer resin. [8] The laminate according to any one of [1] to [7] above, wherein the polyimide layer contains a polyimide represented by the following general formula (1). [Chemical formula] (In formula (1), R 1 is a tetravalent organic group containing an aromatic ring, R 2 is a divalent organic group containing an aromatic ring, m is an integer of 1 or more, and at least a part of R 2 in formula (1) is a functional group represented by the following formula (2)) [Chemical formula] (In formula (2), R 3 and R 4 are each independently a hydrogen atom, a methyl group, and a halogen atom.) [9] A laminate according to any of [1] to [8] above, wherein the thickness ratio of the silicone layer to the polyimide layer is 99:1 to 20:80.

[10] A laminate according to any of [1] to [9] above, which has a polyimide layer / silicone layer laminated structure.

[11] A laminate according to any of [1] to [9] above, having a laminated structure of a polyimide layer / silicone layer / polyimide layer.

[12] A laminate according to any of [1] to

[11] above, used as a release agent, a cushioning material, or an anti-slip material.

[13] A laminate according to any of [1] to

[12] above, used for press forming, vacuum forming, and pressure forming.

[14] A laminate according to any of the above [1] to

[12] used as a carrier film.

[15] A laminate comprising a resin layer (A) having a tensile storage modulus of 100 MPa or less at 23°C and a resin layer (B), The tensile storage modulus of the resin layer (B) at 300°C is 2 GPa or more. A laminate used as a release agent, cushioning material, or anti-slip material.

[16] A laminate comprising a resin layer (A) having a tensile storage modulus of 100 MPa or less at 23°C and a resin layer (B), The tensile storage modulus of the resin layer (B) at 300°C is 2 GPa or more. A laminate used in press forming, vacuum forming, or pressure forming.

[17] A laminate comprising a resin layer (A) having a tensile storage modulus of 100 MPa or less at 23°C and a resin layer (B), The tensile storage modulus of the resin layer (B) at 300°C is 2 GPa or more. A laminate used as a carrier film.

[18] A method of using the laminate described in

[10] above, wherein when used as a release agent or cushioning material during molding, the polyimide layer is placed on the mold side and the silicone layer is placed on the molded body side.

[19] A method of using the laminate described in

[10] above, wherein when used as a release agent or cushioning material during molding, the polyimide layer is placed on the molded body side and the silicone layer is placed on the mold side.

[20] A method of using the laminate described in

[11] above as a release agent or cushioning material during molding. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide a laminate having a silicone layer that exhibits minimal dimensional change even when used in a high-temperature environment. Furthermore, according to the present invention, it is possible to provide a laminate having a resin layer (A) that exhibits little dimensional change even when used in a high-temperature environment and is suitable for use in specific applications. [Modes for carrying out the invention]

[0010] The present invention will be described in detail below, but the present invention is not limited to the embodiments described below. In the present invention, when the term "main component" is used, unless otherwise specified, it implies that other components may be included to the extent that they do not interfere with the function of the main component. In this case, the proportion of the main component is not specified, but the main component accounts for 50% by mass or more, preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, and particularly preferably 90% by mass or more (including 100%) of the composition.

[0011] Furthermore, in this invention, when expressed as "X~Y" (where X and Y are any numbers), unless otherwise specified, it encompasses the meaning of "greater than or equal to X and less than or equal to Y," as well as "preferably greater than X" and "preferably less than Y." Furthermore, in this invention, when expressed as "X or greater" (where X is any number), unless otherwise specified, it includes the meaning of "preferably greater than X," and when expressed as "Y or less" (where Y is any number), unless otherwise specified, it includes the meaning of "preferably less than Y."

[0012] <Laminate> The laminate of the present invention is a laminate comprising a silicone layer and a polyimide layer. The laminate has at least one polyimide layer positioned closer to the outermost surface than the silicone layer. That is, in the laminate of the present invention, when viewed from either of the outermost surfaces of the laminate, at least one polyimide layer is preferably located closer to the outermost surface than either of the silicone layers. In this invention, by having the above-mentioned polyimide layer in addition to the silicone layer, wrinkles and folds are less likely to occur, and heat resistance is also improved. Therefore, the productivity of molded products is improved when used as a release agent or cushioning material in processes such as press molding, vacuum forming, and pressure forming. Furthermore, when used as a carrier film for transport, for example, it is possible to transport workpieces appropriately even when used in high-temperature environments. Moreover, the laminate can be used repeatedly over a long period of time in high-temperature environments.

[0013] [Polyimide layer] The polyimide layer of the present invention has a tensile storage modulus of 2 GPa or more at 300°C. If the tensile storage modulus at 300°C is less than 2 GPa, when pressure is applied to the laminate by press molding or the like at high temperatures, dimensional changes such as stretching in the planar direction occur in the laminate. As a result, strain occurs between the layer and the silicone layer, making it prone to delamination, making it difficult to repeatedly use the laminate in a high-temperature environment, and reducing its durability. From the viewpoint of minimizing dimensional changes even when pressure is applied in a high-temperature environment, the tensile storage modulus at 300°C is preferably 2.3 GPa or more, more preferably 2.6 GPa or more, even more preferably 3 GPa or more, and particularly preferably 3.5 GPa or more. The tensile storage modulus at 300°C mentioned above is not limited in terms of its upper limit; for example, it may be 10 GPa or less, 7 GPa or less, or 6 GPa or less.

[0014] Furthermore, the polyimide layer preferably has a tensile storage modulus of 3.7 GPa or higher at 23°C. A high tensile storage modulus of the polyimide layer at room temperature results in good handling properties, making it easier to set the polyimide layer in the molded body during molding, for example. Additionally, when manufacturing laminates by lamination or other methods, tension is easily applied even to thin layers, simplifying manufacturing, and resulting laminates tend to have fewer wrinkles and other defects. From the viewpoint of handling and ease of manufacture, the tensile storage modulus at 23°C is preferably 4 GPa or higher, more preferably 4.5 GPa or higher, even more preferably 5 GPa or higher, particularly preferably 6 GPa or higher, and most preferably 7 GPa or higher. The tensile storage modulus at 23°C is not limited in terms of its upper limit; for example, it may be 15 GPa or less, 13 GPa or less, or 11 GPa or less. The tensile storage modulus of the polyimide layer at 23°C and 300°C can be determined by measuring the tensile storage modulus of the polyimide layer alone using a viscoelastic spectrometer. While the tensile storage modulus measured in the resin flow direction (MD) should be used, if the MD is unknown, the value obtained in the direction with the highest tensile storage modulus should be used.

[0015] Furthermore, it is preferable that the polyimide layer has a thermogravimetric 2% weight loss temperature of 260°C or higher. A temperature of 260°C or higher tends to improve the heat resistance of the polyimide layer. Therefore, for example, it can be repeatedly used in various applications that are used in high-temperature environments, and tends to have good durability. From the viewpoint of heat resistance and durability, the thermogravimetric 2% weight loss temperature is more preferably 275°C or higher, more preferably 350°C or higher, even more preferably 400°C or higher, even more preferably 450°C or higher, particularly preferably 500°C or higher, and most preferably 540°C or higher. The temperature at which the 2% weight loss of the polyimide layer is determined by thermogravimetric analysis is not particularly limited, but may be, for example, 750°C or lower, or 700°C or lower. The temperature at which a 2% weight loss occurs by thermogravimetric measurement is the temperature at which a sample taken from the polyimide layer is heated in air and the weight loss relative to the initial weight reaches 2%, and specifically, it can be measured by the method described in the examples.

[0016] The polyimide layer preferably has a linear expansion coefficient of 33×10 -6 / °C or less. When the linear expansion coefficient of the polyimide layer is 33×10 -6 / °C or less, dimensional changes are reduced even after repeated use with temperature changes from low to high temperatures, and dimensional stability is increased. Therefore, it can be suitably used for various applications used in high-temperature environments. The linear expansion coefficient of the polyimide layer is preferably 27×10 -6 / °C or less, more preferably 22×10 -6 / °C or less, even more preferably 18×10 -6 / °C or less, and particularly preferably 14×10 -6 / °C or less. The linear expansion coefficient of the polyimide layer is not particularly limited, but for example, it is 5×10 -6 / °C or more, and may be 8×10 -6 / °C or more.

[0017] The outermost surface of the laminate composed of the polyimide layer preferably has an arithmetic mean roughness (Ra) of 26 nm or less. The polyimide layer, for example, contacts the mold side such as a press plate in press molding. When the arithmetic mean roughness (Ra) is 26 nm or less, it is less likely to deviate from the mold such as a press plate when an initial pressure is applied, and the moldability when used as a release material, buffer material, etc. tends to be good. Also, as described later, when polyimide layers are provided on both sides of the silicone layer and both outermost surfaces of the laminate are polyimide layers, it is preferable that the arithmetic mean roughness (Ra) of both outermost surfaces is 26 nm or less. When both outermost surfaces of the laminate are polyimide layers, for example, one contacts the mold such as a press plate and the other contacts the molded body. Therefore, when the arithmetic mean roughness of both outermost surfaces is small, not only the mold such as a press plate but also the molded body is less likely to deviate, and the moldability when used as a release material, buffer material, etc. tends to be even better. From the viewpoint of preventing misalignment of the molded body or press plate with respect to the molding die, the arithmetic mean roughness (Ra) is more preferably 20 nm or less, even more preferably 17 nm or less, even more preferably 13 nm or less, and particularly preferably 10 nm or less. Furthermore, the lower limit of the arithmetic mean roughness (Ra) is not particularly limited, but is preferably 0.5 nm, more preferably 1 nm, more preferably 1.5 nm, and even more preferably 2 nm. When the arithmetic mean roughness is 0.5 nm or higher, when the laminates of the present invention are stacked, the protrusions make point contact, suppressing adhesion between the laminates, and making it easier to obtain laminates with excellent peelability. It also tends to be easier to handle when removing the laminates one by one. In addition, when the mold is opened after press molding to remove the molded body, the problem of the laminate adhering to the molded body is also improved, and productivity tends to increase. Furthermore, when both outermost surfaces of the laminate are polyimide layers, it is possible to make the contact state with the molded body appropriately good, which has the advantage of making it easier to align on the molded body. The arithmetic mean roughness (Ra) was measured using a three-dimensional non-contact surface shape measuring instrument, and it is preferable that it be measured under the measurement conditions described in the examples.

[0018] The method for adjusting the arithmetic mean roughness is not particularly limited, but for example, in a casting process in which a polyimide layer is applied to a support, dried, and heat-treated, a preferred method is to appropriately adjust the surface roughness of the support, such as a mirror-polished metal roll, an endless metal belt, or a polymer film.

[0019] The polyimide layer of the present invention contains polyimide as its main component. The polyimide contained in the polyimide layer of the present invention may be any polyimide obtained by polymerizing a tetracarboxylic acid or tetracarboxylic dianhydride with a diamine, and preferably one obtained by polymerizing an aromatic tetracarboxylic acid or aromatic tetracarboxylic dianhydride with an aromatic diamine and / or an aliphatic diamine. The aliphatic diamine includes alicyclic diamines. More preferably, a polyimide represented by the following general formula (1) is used. By using a polyimide represented by the following general formula (1), the heat resistance is increased, the tensile storage modulus at 300°C is increased, and the temperature at which 2% weight loss occurs tends to be higher. In addition, it becomes easier to lower the coefficient of linear expansion of the polyimide layer. [ka] (Note that in equation (1), R 1 is a tetravalent organic group containing an aromatic ring, R 2 is a divalent organic group containing an aromatic ring, m is an integer greater than or equal to 1, and R in formula (1) 2 At least a portion of these is a functional group represented by the following formula (2). [ka] (Note that in equation (2), R 3 and R 4 Each of these is independently either a hydrogen atom, a methyl group, or a halogen atom.

[0020] R 1 The tetravalent organic group may have an aromatic ring, for example, an organic group having 6 to 24 carbon atoms, preferably 6 to 18 carbon atoms, and more preferably 6 to 12 carbon atoms. 1 Examples include aromatic tetracarboxylic acid residues, specifically those represented by the following formulas (3-1) to (3-5).

[0021] [ka]

[0022] Of the above, either formula (3-1) or (3-2) is preferred, and among them, the organic group represented by either (3-1') or (3-2') below is preferred. [ka]

[0023] Polyimides represented by general formula (1) are R 1 Of these, the organic group represented by either (3-1') or (3-2') above is contained in, for example, 50 mol% or more, preferably 70 mol% or more, more preferably 90 mol% or more, and most preferably 100 mol%.

[0024] In equation (1), the above equation (2) is preferably such that the bond position is at positions 1 and 4 from the viewpoint of heat resistance, low coefficient of linear expansion, and rigidity, and R 3 , R 4 It is preferable that all of them are hydrogen atoms. Therefore, in formula (1), R 2 Preferably, at least a portion of these is a functional group represented by the following formula (2-1). [ka]

[0025] Polyimides represented by general formula (1) are R 2 Of these, the organic group represented in (2-1) above is contained in a proportion of, for example, 10 mol% or more, preferably 30 mol% or more, more preferably 50 mol% or more, and may also be contained in a proportion of 70 mol% or more, or 100 mol%.

[0026] As described above, in equation (1), R 2 At least a portion of R is a functional group represented by the above formula (2) (preferably formula (2-1)), 2 A portion of the above formula (2) may be an organic group having an aromatic ring other than the above formula (2). 2 Examples include divalent organic groups having 12 to 24 carbon atoms, preferably 12 to 18 carbon atoms, and more preferably 12 to 15 carbon atoms. Specifically, examples include organic groups represented by the following formula (4).

[0027] [ka]

[0028] In formula (4) above, the group represented by X is one of the following: a single bond, an oxygen atom, a sulfur atom, C=O, -CH2-, -CH(CH3)-, -C(CH3)2-, -SO2-, and -C(CF3)2-. 5 , R 6 , R 7 , and R 8 Each of these is independently either a hydrogen atom, a methyl group, or a halogen atom. In formula (4), X is preferably an oxygen atom, and R 5 , R 6 , R 7 , and R 8 Hydrogen atoms are preferred in all cases. Furthermore, the bond position in formula (4) is preferably at the 4,4' position. Therefore, R other than in formula (2) above 2 It is more preferable that the organic group is represented by the following formula (4-1).

[0029] [ka]

[0030] The polyimide is preferably a polyimide obtained by polymerizing 3,3',4,4'-biphenyltetracarboxylic acid or its dianhydride with 1,4-phenylenediamine, and more specifically, a polyimide represented by the following formula (5) is preferred. By using the polyimide represented by the following formula (5), it is easier to obtain a polyimide layer with good heat resistance, a low coefficient of linear expansion, and a high tensile storage modulus at 300°C. The polyimide represented by formula (5) can also be a commercially available product, and a specific example is "UPIREX-S" manufactured by Ube Industries, Ltd.

[0031] [ka] In equation (5), m is the same as above.

[0032] Furthermore, polyimides obtained by copolymerizing pyromellitic acid or its dianhydride with paraphenylenediamine and 4,4'-diaminodiphenyl ether are also preferred, specifically in formula (1) above, R 1 is a functional group of formula (3-2'), and R 2 It is preferable that the copolymer polyimide has a functional group of formula (2-1) in part and a functional group of formula (4-1) in the remainder. By controlling the combination of monomers (sequence control), this copolymer polyimide can be made to have a low coefficient of thermal expansion while exhibiting relatively good heat resistance. Specifically, by first reacting 4,4'-diaminodiphenyl ether with pyromellitic dianhydride, and then adding paraphenylenediamine, a polyimide with a low coefficient of thermal expansion and excellent heat resistance can be obtained. As a result, the tensile storage modulus of the polyimide layer at 300°C can also be increased. Commercially available copolymer polyimides can be used, such as "Apical NPI" manufactured by Kaneka Corporation.

[0033] The polyimide layer of the present invention may contain, in addition to polyimide, other resins, fillers, and various additives, such as heat stabilizers, ultraviolet absorbers, light stabilizers, nucleating agents, colorants, lubricants, and flame retardants, as appropriate, within the scope not exceeding the spirit of the present invention. The content of other resins is not particularly limited, but may be, for example, about 50 parts by mass or less, 30 parts by mass or less, or 10 parts by mass or less, per 100 parts by mass of polyimide. However, it is preferable that the resin in the polyimide layer is polyimide.

[0034] The thickness of the polyimide layer can be appropriately selected depending on the application, but from the viewpoint of providing the laminate with the desired heat resistance and dimensional stability without impairing the cushioning properties provided by the silicone layer, it is preferably 150 μm or less, more preferably 130 μm or less, even more preferably 100 μm or less, particularly preferably 80 μm or less, particularly preferably 60 μm or less, and also preferably 3 μm or more, more preferably 5 μm or more, even more preferably 10 μm or more, and particularly preferably 15 μm or more. Note that the thickness of the polyimide layer refers to the thickness of each polyimide layer provided on each side of the silicone layer when polyimide layers are provided on both sides of the silicone layer.

[0035] [Silicone layer] The silicone layer of the present invention is a layer containing silicone as its main component. Preferably, the silicone contains a silicone having a siloxane skeleton represented by the following formula (6). In formula (6), in addition to polydimethylsiloxane in which all of the R groups are methyl groups, various polydimethylsiloxanes can be appropriately selected in which some of the methyl groups (for example, about 30 mol% or less, preferably about 20 mol% or less) are substituted with one or more other alkyl groups, vinyl groups, phenyl groups, fluoroalkyl groups, etc. Also, n in the formula is a positive integer of 1 or more, preferably 3 to 5000.

[0036] [ka]

[0037] The above-mentioned silicone is preferably a silicone elastomer resin. Therefore, the silicone layer preferably contains a silicone elastomer resin, and more preferably contains a silicone elastomer resin as its main component. A preferred example of a silicone elastomer resin is a silicone elastomer resin mainly composed of polydimethylsiloxane.

[0038] The above-mentioned silicone elastomer resin, particularly polydimethylsiloxane, preferably contains vinyl groups. The inclusion of vinyl groups reduces the compression set, making it less prone to changes in thickness even after repeated use during press molding, thus maintaining sufficient cushioning properties and resulting in superior durability. When vinyl groups are present, the content of vinyl groups relative to the total amount of silicone elastomer resin is preferably 0.05 to 5 mol%, more preferably 0.5 to 4 mol%, and even more preferably 1 to 3 mol%. If the content of vinyl groups is above the lower limit, it becomes easier to adjust the crosslinking density of the silicone elastomer resin, and it tends to be easier to obtain a silicone elastomer resin with the desired compression set. On the other hand, if it is below the upper limit, it is preferable because the silicone elastomer resin will not be excessively crosslinked.

[0039] Furthermore, the silicone elastomer resin may contain a silicone elastomer resin that does not contain vinyl groups, from the viewpoint of adjusting the crosslinking point, and a silicone elastomer resin containing vinyl groups and a silicone elastomer resin that does not contain vinyl groups may be used in combination.

[0040] The silicone elastomer resin is preferably of the millable type. While the millable type silicone elastomer resin is non-liquid (for example, solid or paste-like) and does not self-flow at room temperature (25°C) in its uncrosslinked state, it can be mixed with other components in a kneader and can be uniformly mixed with additives described later. Furthermore, the millable type of silicone elastomer resin offers good productivity.

[0041] Furthermore, it is preferable that the silicone elastomer resin in the silicone layer is crosslinked. Crosslinking the silicone elastomer layer makes it easier to impart cushioning properties and improves compression set, making it suitable for use as a release agent or cushioning material during press molding. Moreover, as will be described later, it is even more preferable that the silicone layer is a radiation-crosslinked body that has been crosslinked by radiation.

[0042] The silicone layer may contain reinforcing fillers such as fumed silica, precipitated silica, diatomaceous earth, and quartz powder, as well as various processing aids, heat resistance improvers, and various additives that give functionality to the elastomer. These can be used individually or in combination of two or more. Examples of additives include flame retardants, heat dissipation fillers, and conductive fillers.

[0043] The silicone layer preferably has a Type A durometer hardness of 3 or higher, more preferably 5 or higher, even more preferably 15 or higher, particularly preferably 25 or higher, especially preferably 35 or higher, and most preferably 45 or higher. Furthermore, the Type A durometer hardness is preferably 90 or lower, more preferably 80 or lower, even more preferably 70 or lower, and particularly preferably 60 or lower. Setting the Type A durometer hardness above the lower limit tends to reduce the thickness of the silicone molded body even with repeated use, such as during press molding, thus maintaining sufficient cushioning and excellent durability. Additionally, the tackiness of the silicone molded body surface is moderately suppressed, improving handling ease. On the other hand, setting the Type A durometer hardness below the upper limit tends to improve conformability and adhesion to the press-formed product during press molding. Type A durometer hardness can be measured in accordance with JIS K6253-3:2012. Methods for adjusting the Type A durometer hardness include, for example, adjusting the amount of filler such as silica that is added as a filler to the silicone layer, and appropriately selecting the type of silicone used as the raw material.

[0044] Commercially available silicone elastomer resins can also be used. Examples of commercially available products include Mirable-type silicone compound from Shin-Etsu Chemical Co., Ltd. and Mirable-type silicone rubber from Momentive Performance Materials Inc.

[0045] The thickness of the silicone layer can be appropriately selected depending on the application, but is preferably 3 mm or less, more preferably 1 mm or less, even more preferably 800 μm or less, particularly preferably 600 μm or less, and especially preferably 400 μm or less. Furthermore, from the viewpoint of appropriate elasticity, long-term use, and repeated use, the lower limit is preferably 10 μm, more preferably 20 μm, even more preferably 30 μm, and particularly preferably 50 μm.

[0046] Furthermore, in the laminate of the present invention, the thickness ratio of the silicone layer to the polyimide layer is preferably 99:1 to 20:80. When the thickness ratio of the laminate is within the above range, the heat resistance is good and dimensional changes are suppressed, while appropriate elasticity is obtained, making it suitable for use as a release agent and cushioning material. From these viewpoints, the thickness ratio is more preferably 95:5 to 30:70, even more preferably 90:10 to 40:60, and particularly preferably 85:15 to 50:50. The thickness of the polyimide layer referred to here means the thickness of the polyimide layer provided on one side of the silicone layer. If polyimide layers are provided on both sides of the silicone layer, the thickness of each polyimide layer provided on each side of the silicone layer should be within the above range.

[0047] [Laminated structure] The laminate of the present invention comprises a polyimide layer and a silicone layer, and has at least one polyimide layer positioned closer to the outermost surface than the silicone layer. The laminate of the present invention may have a laminated structure in which, for example, the polyimide layer is provided on only one side of the silicone layer. That is, the laminate of the present invention may have a polyimide layer / silicone layer laminated structure. In this laminated structure, the polyimide layer may constitute one of the outermost surfaces (outermost surface) of the laminate. Alternatively, the silicone layer may constitute the other outermost surface. In this laminated structure, when the laminate is used as a release agent or cushioning material during molding such as press molding, it is preferable to place the polyimide layer on the mold side, such as a press plate, and the silicone layer on the molded body side. With this arrangement, the laminate is less likely to shift relative to the mold due to the polyimide layer, while the silicone layer provides good release properties from the molded body.

[0048] Furthermore, the laminate of the present invention may have a laminated structure in which polyimide layers are provided on both sides of the silicone layer. That is, the laminate of the present invention may have a laminated structure of polyimide layer / silicone layer / polyimide layer. In this laminated structure, it is preferable that the polyimide layers constitute both outermost surfaces of the laminate. With such a laminated structure, when the laminate is used as a release agent or cushioning material during molding such as press molding, the polyimide layer makes it less likely for the mold and molded product to shift, making it easier to obtain a molded product with a highly smooth surface. In addition, when the silicone layer is heated, low molecular weight siloxane components may precipitate and adhere to the mold and the resulting molded product, causing contamination. However, by providing polyimide layers on both sides, the precipitation of low molecular weight siloxane components can be prevented, making it easier to suppress contamination by low molecular weight siloxane components. Furthermore, when the silicone film is used as a release agent or cushioning material, heat treatment may be performed to remove low molecular weight siloxane components that adhere to the mold. However, by providing polyimide layers on both sides, the frequency of heat treatment can be reduced.

[0049] As a method to suppress contamination of the molded body due to the precipitation of low molecular weight siloxane components as described above and to easily obtain a molded body with a high surface smoothness, a laminate in which a polyimide layer is provided on only one side of the silicone layer may be used, with the silicone layer side placed on the mold side such as a press plate and the polyimide layer side placed on the molded body side.

[0050] (Primer layer) Furthermore, in each laminated structure, the polyimide layer may be laminated directly onto the silicone layer, or it may be laminated via a primer layer. From the viewpoint of ensuring adhesion to the silicone layer, the primer layer preferably contains a silicone resin, and more preferably contains a silicone resin as its main component. Examples of silicone resins that can be used in the primer layer include addition-type silicone resins, condensation-type silicone resins, and UV-curing silicone resins, with addition-type silicone resins being preferred. These can be used individually or in combination of two or more types.

[0051] Examples of addition-type silicone resins include those obtained by using polydimethylsiloxane containing vinyl groups as the base polymer, compounding it with polymethylhydrogensiloxane as a crosslinking agent, and curing it in the presence of a platinum catalyst. Examples of condensation-type silicone resins include those obtained by using polydimethylsiloxane containing silanol groups at the ends as the base polymer, blending it with polymethylhydrogensiloxane as a crosslinking agent, and heat curing it in the presence of an organotin catalyst. Examples of UV-curable silicone resins include those based on polydimethylsiloxane containing acryloyl or methacryloyl groups, those based on polydimethylsiloxane containing mercapto and vinyl groups, the aforementioned addition-type silicone resins, or those based on polydimethylsiloxane containing epoxy groups that cure by a cationic curing mechanism. These resins are then combined with a photopolymerization initiator and cured by irradiation with UV light. Furthermore, the primer layer may contain silane coupling agents, adhesion promoters, etc., as needed.

[0052] Examples of silane coupling agents include compounds represented by the general formula ZSiX3. In the above general formula, Z is an organic group having about 1 to 20 carbon atoms and possessing functional groups such as vinyl, epoxy, amino, and mercapto groups, and X is a hydrolyzable functional group such as a methoxy or ethoxy group, or an alkyl group. Furthermore, the silane coupling agent is preferably a compound represented by the general formula YRSiX3, where Y is a functional group such as a vinyl group, epoxy group, amino group, or mercapto group, R is an alkylene group such as methylene, ethylene, or propylene, and X is a hydrolyzable functional group such as a methoxy group or ethoxy group, or an alkyl group.

[0053] Examples of silane coupling agents include vinyltriethoxysilane, vinyltrimethoxysilane, γ-glycidylpropyltrimethoxysilane, γ-glycidylpropyltriethoxysilane, N-β(aminoethyl)-γ-aminopropyltrimethoxysilane, N-β(aminoethyl)-γ-aminopropylmethyldimethoxysilane, and γ-mercaptopropyltrimethoxysilane. These can be used individually or in combination of two or more.

[0054] Preferred adhesion enhancers include siloxanes having epoxy groups at the molecular chain ends or side chains.

[0055] The thickness of the primer layer is preferably 0.01 to 1 μm, more preferably 0.03 to 0.7 μm, and even more preferably 0.05 to 0.5 μm. If the thickness is above the lower limit, a cured film of uniform thickness can be obtained, and sufficient adhesion to the silicone layer tends to be achieved. Although the silicone resin constituting the primer layer generally does not have very high film strength, if the thickness is below the upper limit, cohesive failure of the primer layer is suppressed, and the strength of the laminate tends to be increased.

[0056] (Cover film) In the case of a laminated structure in which a polyimide layer is provided on only one side of a silicone layer, a cover film may be attached to the surface of the silicone layer on which the polyimide layer is not provided. The cover film may consist of a resin film other than the polyimide layer and the silicone layer. The material of the cover film is not particularly limited, but examples include polyolefin resins, styrene resins, polyester resins, polycarbonate resins, polyamide resins, polyphenylene sulfide resins, polyphenylene ether resins, polyaryl ether ketone resins, and liquid crystal polymer resins. Among these, it is preferable to include polyester resin from the viewpoint of heat resistance and mechanical strength, and it is more preferable to include polyester resin as the main component.

[0057] Among polyester resins, crystalline polyester resins are preferred, and examples of crystalline polyester resins include polyethylene terephthalate and polyethylene naphthalate. Of these, polyethylene terephthalate is preferred from the viewpoint of heat resistance, film stiffness, smoothness, and commercial availability. These can be used individually or in combination of two or more.

[0058] Furthermore, the cover film may contain additives such as ultraviolet absorbers, light stabilizers, antioxidants, plasticizers, nucleating agents, lubricants, pigments, and dyes, to the extent that they do not impair the effects of the present invention. From the viewpoint of mechanical strength, it is preferable that the film is stretched at least uniaxially, and more preferably biaxially. The cover film may be a process film used to form the silicone layer during manufacturing, or a protective film that protects the silicone layer during transportation, storage, etc. The cover film may be removed from the laminate before the laminate is used as a release agent, cushioning material, anti-slip material, carrier film, etc.

[0059] The thickness of the cover film is not particularly limited, but is preferably 10 to 350 μm, more preferably 15 to 300 μm, and even more preferably 20 to 250 μm.

[0060] <Method for manufacturing laminates> The method for manufacturing the laminate of the present invention is not particularly limited as long as it is a method that can laminate a polyimide layer on at least one surface of a silicone layer, and known lamination methods can be used.

[0061] For example, a polyimide layer may be fabricated, a separate silicone layer may be fabricated, and these may be laminated together; or a polyimide layer may be fabricated, a silicone layer may be fabricated on this polyimide layer, and these may be laminated together; or conversely, a silicone layer may be fabricated, a polyimide layer may be fabricated on this silicone layer, and these may be laminated together; or a polyimide layer and a silicone layer may be fabricated and laminated together. Furthermore, if the polyimide layer is provided on one side of the silicone layer, a cover film may be appropriately laminated on the side of the silicone layer that does not have the polyimide layer.

[0062] It is preferable to laminate the polyimide layer and the silicone layer without crosslinking the silicone layer first, and then crosslink the silicone layer after the laminate is formed. When the silicone layer is crosslinked after the silicone layer and polyimide layer are laminated together, the polyimide layer can be laminated and integrated with the silicone layer with high adhesive strength.

[0063] The polyimide layer and the silicone layer can be laminated by co-extrusion, lamination, or other methods. In co-extrusion, the polyimide layer and the silicone layer are preferably kneaded and co-extruded simultaneously using a feed block system or a multi-manifold system to laminate them. Another lamination method involves separately fabricating the polyimide layer and the silicone layer, obtaining the polyimide layer and the silicone layer, and then laminating them together. Alternatively, the silicone layer may be formed on a pre-fabricated polyimide layer while laminating.

[0064] Furthermore, a primer layer may be provided between the polyimide layer and the silicone layer as described above. In this case, the primer layer is formed by applying a primer agent to the polyimide layer, drying the primer agent as appropriate, and curing it. Then, the silicone layer is laminated on top of the polyimide layer on which the primer layer has been formed. The primer agent comprises a base polymer for forming the primer layer, and optionally added crosslinking agents, photopolymerization initiators, catalysts, silane coupling agents, adhesion enhancers, etc., and is preferably diluted with a solvent. To improve the leveling and adhesion of the primer agent, the surface of the primer agent coated on the silicone layer and / or polyimide layer may be pre-treated with a surface treatment such as corona treatment. The primer agent is not particularly limited, but is preferably cured by heating at a temperature of about 50 to 150°C.

[0065] The laminate of the present invention is preferably manufactured by a lamination method. In the lamination method, silicone, preferably silicone elastomer resin, which has been mixed with additives as needed in a kneader or the like, is preferably introduced in an uncrosslinked state into a pair of polyimide films, each of which will be a polyimide layer, or between a polyimide film and a cover film, which are fed out from two directions. Here, the silicone may be introduced between the films by extruding it from a T-die or the like using an extruder. After that, the thickness is adjusted in the gap between the rolls as needed to obtain a laminate in which a silicone layer, preferably an uncrosslinked silicone layer, is formed between the films. However, the cover film may be omitted as appropriate.

[0066] Furthermore, while it is preferable to crosslink uncrosslinked silicone, it is preferable to perform the crosslinking after laminating the silicone layer and the polyimide layer as described above. Methods for crosslinking include adding a crosslinking agent to the silicone in advance and crosslinking by heat, ultraviolet light, moisture in the air, etc., or by radiation irradiation.

[0067] In particular, the silicone layer is preferably crosslinked by radiation irradiation. Crosslinking by radiation irradiation is preferable because there is no concern about impairing heat resistance due to residue of the crosslinking agent, and unlike crosslinking by heating, wrinkles do not occur during crosslinking. It is also preferable in order to ensure adhesion between the silicone layer and the polyimide layer. Examples of radiation include electron beams, X-rays, and gamma rays. These types of radiation are widely used industrially, are easily available, and are energy-efficient methods. Among these, gamma rays are preferable because they have almost no absorption loss and high penetration.

[0068] The gamma ray irradiation dose can be appropriately selected and determined depending on the type of resin, the amount of crosslinking groups, and the type of radiation source. For example, the gamma ray irradiation dose is preferably 20 to 150 kGy, more preferably 30 to 120 kGy, even more preferably 40 to 110 kGy, and particularly preferably 50 to 100 kGy. If the irradiation dose is above the lower limit, the silicone layer can be sufficiently crosslinked, and as a result, the desired compression set and durometer hardness tend to be easily obtained. On the other hand, if the irradiation dose is below the upper limit, decomposition reactions do not occur, and the increase in low molecular weight siloxane components can be suppressed.

[0069] <Application> The laminate of the present invention can be used in a variety of applications by taking advantage of the properties of silicone, such as the appropriate adhesion and conformability to various parts in the case of silicone elastomer resin. The laminate of the present invention is preferably used in the manufacturing process of various molded articles, particularly in press molding, vacuum molding, and pressure molding, and in such cases it can be used as a release agent, cushioning material, anti-slip material (sealing material), etc. Furthermore, the laminate can also be used as a carrier film for transporting workpieces, a protective film for protecting workpieces, and the like.

[0070] Among the above, the laminate is preferably used as a release agent or cushioning material in various molding processes such as press molding, vacuum molding, and pressure molding. Specifically, it is suitable for use as a cushioning material placed between the mold (die) and the molded body in the molding process to evenly distribute the pressure acting on the molded body, or to ensure the release of the molded body from the mold. Furthermore, among the above, the laminate is more preferably used as a cushioning material or release agent in press molding. In press molding, the laminate is preferably placed between the workpiece and the press plate when the molded body (workpiece) is pressed with the press plate. In this case, for example, if the polyimide layer is provided on only one side of the silicone layer, the polyimide layer is preferably placed on the press plate side and the silicone layer is preferably placed on the workpiece side, however, the arrangement of the polyimide layer and the silicone layer may be reversed as described above. The temperature during press forming is not particularly limited, but is, for example, 50 to 350°C, preferably 100 to 350°C, more preferably 200 to 350°C, and even more preferably 250 to 320°C. Examples of press forming methods include hydraulic press forming, roll press forming, and belt press forming.

[0071] Furthermore, the laminate of the present invention is preferably used when forming circuit boards, semiconductors, other electronic components, etc., as molded bodies to be incorporated into electrical or electronic products. The press molding is not particularly limited, but is preferably a process performed in the manufacturing of, for example, FPCs, or components constituting all-solid-state batteries, and is also preferably a process performed when pressing an ACF (anisotropic conductive film) onto a circuit board.

[0072] The laminate of the present invention, having a polyimide layer, is less prone to wrinkles and folds and has high heat resistance, thus improving the productivity of molded products when used in various molding processes. Furthermore, even when used in high-temperature molding processes, dimensional changes in the planar direction due to pressure are suppressed, so strain is less likely to occur between the polyimide layer and the silicone layer, and the laminate can be repeatedly used as a release agent, cushioning material, etc.

[0073] The laminate of the present invention is also preferably used as a carrier film. When used as a carrier film, the laminate preferably has a laminated structure of a silicone layer / polyimide layer, and the object to be transported is placed on the silicone layer that constitutes the outermost surface and the object is transported. The silicone layer, in particular if the silicone is a silicone elastomer resin, has slight tackiness, so it can be used as an anti-slip material when used as the outermost surface of the carrier film. The laminate (carrier film) is not particularly limited, but can be transported, for example, by a belt conveyor.

[0074] In carrier films, the polyimide layer is suitable for use as a support for the silicone layer. Carrier films with a silicone layer as the outermost surface generally use a metal plate as a support, but by using a polyimide layer instead of a metal plate, the weight of the transport carrier can be reduced. Furthermore, the polyimide layer of the present invention has high rigidity, so it can be appropriately used as a support instead of a metal plate. Moreover, as described above, the polyimide layer of the present invention has high heat resistance, is less prone to deformation due to heating, and has a low coefficient of linear expansion. Therefore, even when used in high-temperature environments (for example, around 200 to 350°C, preferably around 250 to 320°C), it is less prone to thermal degradation, and problems such as the silicone layer peeling off from the polyimide layer are less likely to occur, allowing for repeated use.

[0075] The transported materials include, but are not particularly limited to, circuit boards, semiconductors, and other electronic components that are incorporated into electrical or electronic products. Furthermore, it is preferable that the carrier film is a reflow carrier that performs the reflow process with the transported materials (workpieces) placed on it. In the reflow process, temperatures may be heated to, for example, 200°C or higher, but as described above, the laminate of the present invention can be used repeatedly even in high-temperature environments and is particularly suitable for use as a reflow carrier.

[0076] [Release agent, cushioning material, anti-slip material] In another aspect, the present invention provides a laminate (X1) to be used as a release agent, a cushioning material, and an anti-slip material. The laminate (X1) comprises a resin layer (A) having a tensile storage modulus of 100 MPa or less at 23°C and a resin layer (B), wherein the tensile storage modulus of resin layer (B) at 300°C is 2 GPa or more.

[0077] In this laminate (X1), the resin layer (A) has a tensile storage modulus of 100 MPa or less at 23°C, resulting in good conformability, adhesion, and surface tackiness to molded articles during press molding, making it suitable for use as a release agent, cushioning material, and anti-slip material. Details of the release agent, cushioning material, and anti-slip material are as described above, and it is preferable to use resin layer (A) instead of the silicone layer and resin layer (B) instead of the polyimide layer. Furthermore, having a resin layer (B) with a tensile storage modulus of 2 GPa or more at 300°C provides high heat resistance, making it less likely for the laminate to undergo dimensional changes such as stretching in the planar direction even when pressure is applied to it. This prevents distortion and delamination between the resin layer (A) and the laminate (X1), allowing the laminate (X1) to be repeatedly used as a release agent, cushioning material, or anti-slip material in high-temperature environments, thereby improving durability. From the above viewpoint, the tensile storage modulus at 300°C is preferably 2.3 GPa or higher, more preferably 2.6 GPa or higher, even more preferably 3 GPa or higher, and particularly preferably 3.5 GPa or higher. Furthermore, the tensile storage modulus at 300°C is not limited to an upper limit; for example, it may be 10 GPa or less, 7 GPa or less, or 6 GPa or less.

[0078] From the viewpoint of conformability to the molded body during press molding, adhesion, and surface tackiness of the resin layer (A), the tensile storage modulus of the resin layer (A) at 23°C is preferably 70 MPa or less, more preferably 50 MPa or less, even more preferably 30 MPa or less, and particularly preferably 10 MPa or less. Furthermore, it is preferably 0.1 MPa or more, more preferably 0.5 MPa or more, and even more preferably 1 MPa or more.

[0079] The resin constituting the resin layer (A) is not particularly limited, and for example, silicone, olefin-based elastomer, styrene-based elastomer, polyester-based elastomer, urethane-based resin, epoxy-based resin, fluorine-based elastomer, etc. can be used. However, it is preferable to use silicone as the main component in the resin layer (A) because it has excellent heat resistance, electrical properties such as insulation, and mold release properties. When using silicone, it is best to use the type of silicone described above, and the resin layer (A) is the same as the silicone layer described above.

[0080] The resin constituting the resin layer (B) is not particularly limited and includes curable resins such as polyimide, bismaleimide, and benzoxazine; amorphous thermoplastic resins with a glass transition temperature (Tg) of 300°C or higher, such as thermoplastic polyimide and polyamideimide; polyetherketone-based resins such as polyetheretherketone; and crystalline thermoplastic resins with a crystal melting temperature (Tm) of 300°C or higher, such as polytetrafluoroethylene resin (PTFE), tetrafluoroethylene-perfluoroalkoxyethylene copolymer resin (PFA), and liquid crystal polymer. Among these, polyimide is preferably used as the main component of the resin layer (B) due to its excellent heat resistance and rigidity. Note that Tg and Tm are values ​​obtained from the DSC curve during reheating measured by a differential scanning calorimeter in accordance with JIS K7121:2012. When using polyimide, it is best to use the type of polyimide described above, and the resin layer (B) is the same as the polyimide layer described above.

[0081] Furthermore, the tensile storage modulus at 23°C, the temperature of 2% weight loss by thermogravimetric analysis, the coefficient of linear expansion, the arithmetic mean roughness (Ra) of the outermost surface of the laminate composed of resin layer (B), and the thickness of the resin layer (B) are the same as those of the polyimide layer described above, and their explanation is omitted. In addition, the type A durometer hardness, thickness, and other properties of resin layer (A) are the same as those of the silicone layer described above, and the thickness ratio of resin layer (A) to resin layer (B) is the same as the thickness ratio of the silicone layer to the polyimide layer, so these explanations are also omitted.

[0082] Furthermore, the resin layer (B) may be laminated directly onto the resin layer (A), or it may be laminated via another layer such as a primer layer. When the resin layer (A) is a silicone layer, the primer layer preferably contains silicone resin, and more preferably contains silicone resin as its main component, from the viewpoint of ensuring adhesion to the primer layer (A). Details of the primer layer containing silicone resin are as described above. The laminate (X1) may also have at least one resin layer (B) positioned closer to the outermost surface than the resin layer (A). That is, in the laminate of the present invention, when viewed from either of the outermost surfaces of the laminate, at least one resin layer (B) is positioned closer to the outermost surface than any of the resin layers (A). It is preferable that at least one outermost surface of the laminate is composed of the resin layer (B). In the laminate (X1), the resin layer (B) may be provided on only one side of the resin layer (A), or on both sides. If the resin layer (B) is provided on only one side of the resin layer (A), the cover film described above may be provided on the other side.

[0083] [Laminates for press forming, vacuum forming, and pressure forming] In yet another aspect, the present invention provides a laminate (X2) for use in press molding, vacuum molding, and pressure molding. The laminate (X2) comprises a resin layer (A) having a tensile storage modulus of 100 MPa or less at 23°C and a resin layer (B), wherein the tensile storage modulus of layer (B) at 300°C is 2 GPa or more.

[0084] In this laminate (X2), the resin layer (A) has a tensile storage modulus of 100 MPa or less at 23°C, resulting in good conformability, adhesion, and surface tackiness to the molded body during press molding, vacuum molding, or pressure molding. Therefore, it can be suitably used as a release agent or cushioning material in each of these molding processes. Details of press molding, vacuum molding, or pressure molding, as well as the release agent or cushioning material, are as described above. It is preferable to use resin layer (A) instead of the silicone layer and resin layer (B) instead of the polyimide layer. Furthermore, having a resin layer (B) with a tensile storage modulus of 2 GPa or more at 300°C provides high heat resistance. For example, when pressure is applied to the laminate, dimensional changes such as stretching in the planar direction of the laminate (X2) are less likely to occur. This prevents distortion and delamination between the resin layer (A) and the laminate (X2), allowing the laminate (X2) to be repeatedly used in press molding, vacuum molding, or pressure molding in high-temperature environments, thereby improving durability. The configuration of the laminate (X2) in this embodiment is as described above for the laminate (X1), and a detailed explanation thereof is omitted.

[0085] [Career Film] In yet another aspect, the present invention provides a laminate (X3) for use as a carrier film. The laminate (X3) comprises a resin layer (A) having a tensile storage modulus of 100 MPa or less at 23°C and a resin layer (B), wherein the tensile storage modulus of layer (B) at 300°C is 2 GPa or more.

[0086] In this laminate (X3), the resin layer (A) has a tensile storage modulus of 100 MPa or less at 23°C, resulting in good surface tackiness, making it suitable for use as the outermost surface of the carrier film. The details of the carrier film are as described above, and it is preferable to use resin layer (A) instead of the silicone layer and resin layer (B) instead of the polyimide layer. Furthermore, the presence of a resin layer (B) with a tensile storage modulus of 2 GPa or more at 300°C provides high heat resistance. Therefore, even when used in high-temperature environments (for example, around 200-350°C, preferably around 250-320°C), the laminate (X3) is less susceptible to thermal degradation and less prone to problems such as the resin layer (B) peeling off from the resin layer (A), allowing for repeated use. The configuration of the laminate (X3) in this embodiment is as described in the description of the laminate (X1) above, and a detailed explanation is omitted. [Examples]

[0087] The present invention will be further explained in the following examples, but these examples do not limit the present invention in any way.

[0088] In this example and comparative example, the evaluation was performed as follows. (1) Tensile storage modulus For a film (100 μm thick) consisting of a polyimide film forming a polyimide layer or a silicone resin raw material forming a silicone layer, the tensile storage modulus at 23°C and 300°C was measured using a viscoelastic spectrometer under the following conditions, in accordance with JIS K7244-4:1999. Measurement device name: "DVA-200", manufactured by IT Measurement & Control Co., Ltd. Chuck spacing: 25mm, Distortion: 0.07%, Width: approx. 4mm Temperature: -50 to 350°C Frequency: 1Hz Measurement method: Tensile; Heating rate: 3°C / min Measurement direction: MD

[0089] (2) Thermogravimetry For thermogravimetric analysis, a sample taken from the polyimide layer was heated using a differential thermogravimetric analyzer (TG-DSC) under the following conditions, and the temperature at which the weight loss relative to the initial weight was 2% was recorded. Measurement device: "STA200RV", manufactured by Hitachi High-Tech Science Co., Ltd. Measurement conditions: Measurements were taken after increasing the temperature from 35°C at a rate of 20°C / min. The measurements were taken in an atmospheric environment.

[0090] (3) Coefficient of linear expansion The polyimide film forming the polyimide layer was measured using a thermomechanical analyzer under the following measurement conditions. Measurement device: "TMA / SS7100", manufactured by Hitachi High-Tech Science Co., Ltd. Specimen width: 6 mm, Chuck distance: 10 mm Mode: Tensile Measurement direction: MD Temperature conditions: The sample was heated from 15 to 330°C at a rate of 5°C / min, and then cooled down to 15°C at a rate of 5°C / min. The sample lengths at 300°C and 30°C during the cooling process were measured, and the coefficient of linear expansion (1 / °C) was calculated. The measurement direction was MD.

[0091] (4) Arithmetic mean roughness (Ra) of the polyimide layer The arithmetic mean roughness (Ra) of the polyimide layer constituting the outermost surface of the laminate was measured using a three-dimensional non-contact surface shape measuring instrument (product name "VertScan2.0 R5200G" manufactured by Ryoka Systems Co., Ltd.) with a 5x objective lens and a measurement range of 948.76 μm × 711.61 μm.

[0092] (5) Dimensional changes For each example and comparative example, a laminate in which a polyimide layer was laminated on top of the silicone layer was used as the analytical model by dividing the laminate into finite elements. The silicone layer was 20 mm square and 100 μm thick, with a tensile storage modulus of 3 MPa and a Poisson's ratio of 0.49 at 300°C. The tensile storage modulus of the silicone layer was also obtained by measuring it using the same method as described above. The polyimide layer was 20 mm square and 25 μm thick, with a Poisson's ratio of 0.3, and its tensile storage modulus was the same as measured for each example and comparative example. As boundary conditions, the bottom surface of the silicone layer is completely fixed, and as a load condition, 100 kgf / cm² is applied to the top surface of the polyimide layer. 2 A uniform pressure was applied. Under these model conditions, the elongation of the polyimide layer over a 10 mm width from the center to the edge was calculated using finite element analysis software. The calculated values ​​are shown in Table 1.

[0093] (6) Amount of transcription of low molecular weight cyclic siloxane components (Press forming) Clean paper was placed on top of the laminates obtained in Examples 1 and 3, and pressed in a press machine for 10 minutes at a temperature of 100°C and a pressure of 10 MPa to evaluate the amount of low molecular weight cyclic siloxane transferred to the clean paper. In the case of a single-sided polyimide laminate, the clean paper was placed on the silicone layer side, and in the case of a double-sided polyimide laminate, the clean paper was placed on one side of the polyimide layer.

[0094] (Quantitative determination of low molecular weight cyclic siloxanes) As the internal standard solution, 5 mg of decamethylcyclopentasiloxane (cyclic siloxane pentamer (D5 siloxane)) was accurately weighed, placed in a 100 mL volumetric flask, and made up with acetone. 25cm of clean paper after pressing 2 The sample was cut out, accurately weighed, and placed in a sample bottle. 10 mL of the internal standard solution was then weighed into the bottle. After capping the sample bottle, Parafilm was wrapped around it, and the extraction process was performed by immersion at room temperature for 16 hours. Subsequently, the content of low molecular weight cyclic siloxanes in the acetone solution in the sample bottle was measured by gas chromatography (GC) under the following measurement conditions. The column temperature was held at 70°C for 1 minute, then increased at a rate of 25°C / min to 320°C, held for 5 minutes, and then measured.

[0095] (Measurement conditions) • Measuring device: GC-2010Plus (manufactured by Shimadzu Corporation) • Column: Ultra ALLOY Capillary Column-UA1 (MS / HT) (100% dimethylpolysiloxane, length 30m, inner diameter 0.25mm, film thickness 0.1μm) • Carrier gas: Helium ·Flow rate: 1mL / min • Detector: FID

[0096] (Method for calculating cyclic siloxane content) Based on the internal standard D5 siloxane content and GC peak area, each cyclic siloxane D4-D20 (where Dn is D4-D20 siloxane, a cyclic siloxane containing dimethylsiloxane units) was quantified from its respective peak area, and its total content was evaluated. For D5 siloxane, the internal standard D5 siloxane content was subtracted before quantification. Furthermore, a content of less than 30 ppm by mass was defined as "ND" (Not Detectable).

[0097] Example 1 A polyimide film (Ube Industries, Ltd.'s "UPIREX-S", thickness: 25 μm) was coated with a primer containing an addition-type silicone resin, an adhesion improver, and a curing catalyst, diluted with toluene as a solvent, using a roll-coating method to achieve a thickness of 0.3 μm after drying. The film was then heat-treated by drying at 120°C for 30 seconds to obtain a polyimide film having a primer layer on one side. As the raw material for the silicone layer, a millable-type silicone elastomer resin (TSE2571-5U, manufactured by Momentive Performance Materials, Inc., with a tensile storage modulus of 3.5 MPa (23°C)) was used. The silicone elastomer resin was supplied between the primer layer of the polyimide film, which was fed along two 100 mm diameter calenders, and a biaxially oriented PET film ("Diafoil T-100," manufactured by Mitsubishi Chemical Corporation, with a thickness of 100 μm) as the cover film. A bank was formed on the rolls under conditions of a roll temperature of 80°C, and a laminate consisting of a polyimide layer and a silicone layer was fabricated. A cover film was attached to the silicone layer. The resulting laminate with a cover film was irradiated with gamma rays to an absorbed dose of 50 kGy, causing the silicone elastomer resin to crosslink, and a laminate in which the polyimide layer and the silicone layer were integrated was obtained. The thickness of the silicone layer was 100 μm, and the Type A durometer hardness was 55. The cover film was peeled off from this laminate to obtain a laminate for evaluation. The results of the evaluation of the obtained laminate using the method described above are shown in Table 1.

[0098] Example 2 A laminate was fabricated in the same manner as in Example 1, except that the polyimide film was changed to Kaneka's "Apical NPI" (thickness: 25 μm).

[0099] Example 3 The procedure was carried out in the same manner as in Example 1, except that instead of a cover film, a polyimide film (Ube Industries, Ltd. "UPIREX-S", thickness: 25 μm) having a primer layer formed on one side in the same manner as in Example 1 was used, and a silicone layer was formed between the primer layers of the two polyimide films to obtain a laminate consisting of a polyimide layer / silicone layer / polyimide layer.

[0100] Example 4 The procedure was carried out in the same manner as in Example 2, except that instead of a cover film, a polyimide film (Kaneka Corporation's "Apical NPI", thickness: 25 μm) having a primer layer formed on one side in the same manner as in Example 2 was used, and a silicone layer was formed between the primer layers of the two polyimide films to obtain a laminate consisting of a polyimide layer / silicone layer / polyimide layer.

[0101] Comparative Example 1 A laminate was fabricated in the same manner as in Example 1, except that the polyimide film was changed to Kaneka's "Apical AH" (thickness: 25 μm).

[0102] Comparative Example 2 A laminate was fabricated in the same manner as in Example 1, except that the polyimide film was changed to "Kapton 100H" (thickness: 25 μm) manufactured by Toray DuPont.

[0103] [Table 1] *In Examples 3 and 4, the arithmetic mean roughness of both outermost surfaces was the same.

[0104] As shown in Table 1, in Examples 1 to 4, the tensile storage modulus at 300°C was high, which suppressed dimensional changes in the laminate when pressing under high-temperature heating. Therefore, even when repeatedly used in high-temperature environments as a release agent or cushioning material, problems such as the polyimide layer peeling off from the silicone layer are less likely to occur. From the perspective of repeated use, there is a great demand in the process to reduce the dimensional change of the laminate by even 1 μm, and the significance of the present invention lies in finding that dimensional changes can be suppressed simply by increasing the tensile storage modulus at 300°C of the polyimide layer in a laminate comprising a silicone layer and a polyimide layer. Furthermore, its low coefficient of thermal expansion and high 2% weight loss temperature made it suitable for various applications in high-temperature environments. Its high tensile storage modulus at 23°C also resulted in excellent handling properties, allowing for easy production of laminates by lamination. Additionally, its low arithmetic mean roughness reduces the likelihood of misalignment with molds such as press plates, or with molds and molded products. Furthermore, as shown in Example 3, when polyimide layers are provided on both sides, the amount of cyclic siloxane transferred to the clean paper is small, and the molded product and mold are less likely to be contaminated even when used in a high-temperature environment.

[0105] On the other hand, in Comparative Examples 1 and 2, the tensile storage modulus at 300°C is low, resulting in large dimensional changes in the laminate when pressed under high-temperature heating. When repeatedly used in high-temperature environments as a release agent or cushioning material, problems such as the polyimide layer peeling off from the silicone layer are likely to occur. Furthermore, the coefficient of linear expansion is high and dimensional stability under heating is low, making it unsuitable for use in high-temperature environments. In addition, the tensile storage modulus at 23°C is low, resulting in insufficient handling and reduced processability in lamination methods. Moreover, Comparative Example 1 has a large arithmetic mean roughness, making it prone to misalignment with molds such as press plates, and its low 2% weight loss temperature means that thermal degradation is also likely to occur.

Claims

1. A laminate comprising a silicone layer and a polyimide layer, It has at least one polyimide layer positioned closer to the outermost surface than the silicone layer, The thickness of the silicone layer is 20 μm or more and 3 mm or less, and the thickness ratio of the silicone layer to the polyimide layer is 99:1 to 20:

80. The tensile storage modulus of the polyimide layer at 300°C is 2 GPa or more. The silicone layer is a laminate containing 50% by mass or more of a silicone elastomer resin, and the silicone elastomer resin does not have hydroxyl groups.

2. The laminate according to claim 1, wherein at least one of the outermost surfaces is the polyimide layer.

3. The laminate according to claim 1 or 2, wherein the temperature at which the polyimide layer exhibits a 2% weight loss by thermogravimetric measurement is 260°C or higher.

4. The laminate according to any one of claims 1 to 3, wherein the tensile storage modulus of the polyimide layer at 23°C is 3.7 GPa or more.

5. The coefficient of linear expansion of the polyimide layer is 33 × 10 －６ The laminate according to any one of claims 1 to 4, wherein the temperature is less than or equal to / ℃.

6. The laminate according to any one of claims 1 to 5, wherein the arithmetic mean roughness (Ra) of the outermost surface of the laminate composed of the polyimide layer is 26 nm or less.

7. The laminate according to any one of claims 1 to 6, wherein the silicone elastomer resin is of the millable type.

8. The laminate according to any one of claims 1 to 7, wherein the polyimide layer contains a polyimide represented by the following general formula (1). 【Chemistry 1】 (Note that in equation (1), R １ R is a tetravalent organic group containing an aromatic ring. ２ is a divalent organic group containing an aromatic ring, m is an integer of 1 or more, and R in formula (1) ２ At least a portion of these is a functional group represented by the following formula (2). 【Chemistry 2】 (Note that in equation (2), R ３ and R ４ These are, independently, a hydrogen atom, a methyl group, and a halogen atom.

9. The laminate according to any one of claims 1 to 8, wherein the thickness ratio of the silicone layer to the polyimide layer is 85:15 to 50:

50.

10. A laminate according to any one of claims 1 to 9, wherein the laminate has a polyimide layer / silicone layer laminate structure.

11. A laminate according to any one of claims 1 to 9, having a laminated structure of polyimide layer / silicone layer / polyimide layer.

12. A laminate according to any one of claims 1 to 11, used as a release agent, a cushioning material, and an anti-slip material.

13. A laminate according to any one of claims 1 to 12, used for press forming, vacuum forming, and pressure forming.

14. A laminate according to any one of claims 1 to 12, used as a carrier film.

15. A method for using the laminate according to claim 10, wherein when used as a release agent or cushioning material during molding, the polyimide layer is placed on the mold side and the silicone layer is placed on the molded body side.

16. A method for using the laminate according to claim 10, wherein when used as a release agent or cushioning material during molding, the polyimide layer is placed on the molded body side and the silicone layer is placed on the mold side.

17. A method for using the laminate according to claim 11, as a release agent or cushioning material during molding.

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