Laminate

Abstract

To provide a laminate having a silicone layer, which can be used for a long time even in a high temperature environment while the embrittlement of the silicone layer is suppressed.SOLUTION: A laminate comprises a silicone layer and a polyimide layer, wherein the weight reduction rate of the silicone layer at 380°C, measured by thermogravimetry, is 9 mass% or less.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a laminate having at least two resin layers, including a silicone layer and a polyimide layer, which is used, for example, as a release material, a buffer material, or an anti-slip material. [Background technology]

[0002] Silicones, such as silicone rubber and silicone resin, especially millable silicone rubber, have been widely used as release agents, buffer 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 buffer materials in press molding in the manufacture of flexible printed circuit boards (FPCs), all-solid-state batteries, and semiconductors. They are also sometimes used as anti-slip materials for transport carriers in reflow processes.

[0003] When silicone consisting of a single silicone layer such as silicone rubber is used as a release agent for press molding, deformation occurs, resulting in poor dimensional accuracy during assembly and wrinkles, resulting in workability problems. For this reason, it is known that silicone is used as a laminate by combining it with a plastic film. In this case, a polyester resin film or the like is used as the plastic film, as disclosed in Patent Document 1, for example. Furthermore, silicone is often laminated onto a polyester resin film via a primer layer or the like to improve adhesion. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 11-20082 Summary of the Invention [Problem to be solved by the invention]

[0005] In recent years, the press molding used in all-solid-state batteries, semiconductors, etc. has tended to require higher molding temperatures and pressures, with press processing sometimes being performed at temperatures of around 100 to 300°C and pressures of around 50 to 1000 MPa. Silicone films are also being considered for use as release agents in the FPC manufacturing process, but the press molding temperatures also tend to be higher in the FPC manufacturing process.

[0006] However, even when a silicone film (silicone layer) is integrated with another plastic film such as a polyester film to form a laminate, if the silicone film is used repeatedly in a high-temperature environment by press molding or the like, the silicone film itself becomes brittle and loses its cushioning properties, resulting in problems such as the inability to use the film repeatedly over a long period of time.

[0007] Furthermore, when used as a transport carrier in the reflow process, a silicone film laminated on a metal plate is often used, but from the perspective of weight reduction, the use of a resin sheet instead of a metal plate is also being considered. For example, the use of a laminate of the above-mentioned silicone film and polyester film is also being considered. However, in the reflow process, the transport carrier is also heated to high temperatures, which can cause the silicone film to become brittle and the polyester film to undergo dimensional changes, making it difficult to use over the long term and making it difficult to put into practical use.

[0008] Therefore, an object of the present invention is to provide a laminate having a silicone layer in which embrittlement of the silicone layer is suppressed even when used in a high-temperature environment, and which can be used for a long period of time. Another object of the present invention is to provide a laminate that is suppressed from becoming embrittled even when used in a high-temperature environment, can be used for a long period of time, and is suitable for specific applications. [Means for solving the problem]

[0009] As a result of extensive research, the present inventors have found that the above problems can be solved by using a polyimide layer as a resin layer integrated with a silicone layer, or by using resin layers (A) and (B) having a tensile storage modulus suitable for specific applications, and by using a silicone layer or resin layer (A) that exhibits a low rate of weight loss even when heated at high temperatures, and have completed the present invention as described below. That is, the present invention provides the following [1] to

[16] . [1] A laminate comprising a silicone layer and a polyimide layer, A laminate in which the weight loss rate of the silicone layer at 380°C as measured by thermogravimetry is 9% by mass or less. [2] The laminate according to the above [1], wherein a polyimide layer is provided on both sides of the silicone layer. [3] The laminate according to the above [1], which comprises the polyimide layer on only one side of the silicone layer and a cover film on the other side of the silicone layer. [4] The laminate according to any one of the above [1] to [3], wherein the silicone layer contains 0.1 to 10% by mass of titanium oxide. [5] The laminate according to any one of the above [1] to [4], wherein the tensile storage modulus at 23°C of the polyimide layer is greater than the tensile storage modulus at 23°C of the silicone layer. [6] The laminate according to any one of the above [1] to [5], wherein the silicone layer has a tensile stress at break retention rate of 10% or more after heat treatment at 300°C for 3 hours. [7] The laminate according to any one of the above [1] to [6], wherein the silicone layer has a tensile strain retention at break of 10% or more after heat treatment at 300°C for 3 hours. [8] The laminate according to any one of the above [1] to [7], wherein the thickness ratio of the silicone layer:polyimide layer is 99:1 to 20:80. [9] The laminate according to any one of the above [1] to [8], which is used as a release material, a cushioning material, or an anti-slip material.

[10] The laminate according to any one of the above [1] to [8], which is used for press molding, vacuum molding, or pressure molding.

[11] The laminate according to any one of the above [1] to [8], which is used as a carrier film.

[12] 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) having a tensile storage modulus of 1 GPa or more at 23°C, The laminate has a weight loss rate of the resin layer (A) at 380°C as measured by thermogravimetry of 9% by mass or less, and is used as any one of a release material, a cushioning material, and an anti-slip material.

[13] 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) having a tensile storage modulus of 1 GPa or more at 23°C, The resin layer (A) has a weight loss rate of 9% by mass or less at 380°C as measured by thermogravimetry, and the laminate is suitable for use in any one of press molding, vacuum molding, and pressure molding.

[14] 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) having a tensile storage modulus of 1 GPa or more at 23°C, The laminate used as a carrier film has a weight loss rate of the resin layer (A) at 380°C as measured by thermogravimetry of 9% by mass or less.

[15] A method for using the laminate according to any one of the above [1] to [8], which is used as a release material during molding or a cushioning material.

[16] A method for using the laminate according to any one of the above [3] to [8], wherein when using the laminate as a release material or a cushioning material during molding, the cover film is peeled off, and the polyimide layer side is placed on the molding die side and the silicone layer side is placed on the molded product side. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide a laminate having a silicone layer in which embrittlement of the silicone layer is suppressed even when used in a high-temperature environment, and which can be used for a long period of time. Furthermore, according to the present invention, it is possible to provide a laminate that is suppressed from becoming embrittled even when used in a high-temperature environment, can be used for a long period of time, and is suitable for specific applications. DETAILED DESCRIPTION OF THE INVENTION

[0011] The present invention will be described in detail below, but is not limited to the embodiments described below. In the present invention, the term "main component" includes the inclusion of other components within the scope of not interfering with the function of the main component, unless otherwise specified. While the content of the main component is not specified, 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.

[0012] Furthermore, in the present invention, when an expression "X to Y" (X and Y are any numbers) is used, unless otherwise specified, it includes the meaning of "X or more and Y or less", as well as "preferably larger than X" and "preferably smaller than Y". Furthermore, in the present invention, when it is expressed as "X or more" (X is any number), it includes the meaning of "preferably larger than X" unless otherwise specified, and when it is expressed as "Y or less" (Y is any number), it includes the meaning of "preferably smaller than Y" unless otherwise specified.

[0013] <Laminate> The laminate of the present invention is a laminate comprising a silicone layer and a polyimide layer. In the present invention, the inclusion of a polyimide layer in addition to the silicone layer reduces wrinkles and folds and improves heat resistance. Therefore, for example, when used as a release material or a cushioning material in press molding, vacuum molding, pressure molding, etc., the productivity of molded articles is improved. Furthermore, when used as a carrier film for transportation, for example, it is possible to properly transport workpieces even in high-temperature environments. Furthermore, the laminate can be used repeatedly over long periods of time in high-temperature environments.

[0014] [Silicone layer] The silicone layer of the present invention has a weight loss rate of 9% by mass or less at 380°C as measured by thermogravimetry. If the weight loss rate at 380°C exceeds 9% by mass, the silicone layer becomes brittle when the laminate is used in a high-temperature environment, making it impossible to maintain performance such as cushioning, and dimensional changes are likely to occur. This can lead to problems such as the laminate being unable to be used repeatedly over long periods in high-temperature environments. From the perspective of suppressing the brittleness of the silicone layer in high-temperature environments and enabling the laminate to be used for a longer period, the weight loss rate at 380°C is preferably 7% by mass or less, more preferably 6% by mass or less, and even more preferably 5% by mass or less. The lower the weight loss rate at 380°C, the better; 0% by mass or more is sufficient. However, considering the properties of the silicone that forms the silicone layer, a certain value or more is required, for example, 1% by mass or more. The weight loss rate at 380°C measured by thermogravimetry is determined by heating a sample taken from the silicone layer at a constant temperature increase rate in the atmosphere, and expressing the ratio of the weight loss at 380°C to the initial weight as a percentage. More specifically, this can be measured by the method described in the Examples.

[0015] The silicone layer preferably has a tensile stress retention at break of 10% or more after heat treatment at 300°C for 3 hours, more preferably 20% or more, even more preferably 30% or more, even more preferably 35%, particularly preferably 40% or more, and most preferably 45% or more. When the tensile stress retention at high temperature is as high as described above, embrittlement of the silicone layer when heated at high temperature for a long period of time is suppressed, and the laminate can be used for a long period of time. The higher the tensile stress retention at break, the better; it is sufficient if it is 100% or less, but it is usually about 70% or less.

[0016] Furthermore, the silicone layer preferably has a tensile fracture strain retention of 10% or more after heat treatment at 300°C for 3 hours, more preferably 30% or more, even more preferably 40% or more, even more preferably 50% or more, particularly preferably 60% or more, and most preferably 70% or more. When the tensile fracture strain retention during high-temperature heating is as high as described above, the cushioning properties of the silicone layer are maintained even after heating at high temperatures for a long period of time, allowing the laminate to be used for a long period of time. The higher the tensile fracture strain retention, the better, and it is sufficient if it is 100% or less, but it is usually about 95% or less.

[0017] The tensile stress retention rate and tensile strain retention rate were determined by conducting tensile tests at the initial stage before heat treatment and after heat treatment at 300°C for 3 hours, measuring the stress and elongation at tensile failure before and after heat treatment, and expressing the percentage of the fracture stress and fracture strain after heat treatment relative to the initial fracture stress and initial fracture strain before heat treatment. The tensile direction can be the direction of flow (MD) of the resin. However, if the MD is unknown, the fracture stress and fracture strain can be measured by pulling in the direction in which the initial fracture stress is highest. Measurements can be performed on test pieces cut from the silicone layer of the laminate. If cutting is difficult, measurements can also be performed on samples (with the same thickness as the silicone layer of the laminate) prepared using a method similar to the molding method for the silicone layer in the laminate. Similar measurements can also be performed on the tensile storage modulus, as described below.

[0018] The initial fracture stress of the silicone layer is not particularly limited, but is preferably 3 MPa or more, more preferably 5 MPa or more, and even more preferably 8 MPa or more, and is, for example, 25 MPa or less, preferably 20 MPa or less, and more preferably 15 MPa or less. Furthermore, the initial fracture strain of the silicone layer is not particularly limited, but is preferably 200% or more, more preferably 250% or more, even more preferably 300% or more, particularly preferably 350% or more, and is, for example, 1400% or less, preferably 1300% or less. When the silicone layer has an initial breaking stress and an initial breaking strain equal to or greater than a certain value, it can ensure good cushioning properties and also has excellent mechanical strength.

[0019] The silicone layer of the present invention is a layer containing silicone as a main component. The silicone preferably contains a silicone having a siloxane skeleton represented by the following formula (1): In formula (1), in addition to polydimethylsiloxane in which all R are methyl groups, various polydimethylsiloxanes in which a portion of the methyl groups (for example, about 30 mol % or less, preferably about 20 mol % or less) are substituted with one or more of other alkyl groups, vinyl groups, phenyl groups, fluoroalkyl groups, etc. may also be appropriately selected. Furthermore, n in the formula is a positive integer of 1 or more, preferably 3 to 5,000.

[0020] [ka]

[0021] The 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 a main component. A preferred example of the silicone elastomer resin is a silicone elastomer resin containing polydimethylsiloxane as a main component.

[0022] The silicone elastomer resin, particularly polydimethylsiloxane, preferably contains a vinyl group, which reduces compression set and tends to reduce thickness changes even with repeated use, such as during press molding, thereby maintaining sufficient cushioning properties and improving durability. When vinyl groups are contained, 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 equal to or greater than the lower limit, it becomes easier to adjust the crosslink 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 the content is equal to or less than the upper limit, the silicone elastomer resin is not excessively crosslinked, which is preferable.

[0023] Furthermore, from the viewpoint of adjusting the crosslinking points, the silicone elastomer resin may contain a silicone elastomer resin that does not contain a vinyl group, or a silicone elastomer resin that contains a vinyl group may be used in combination with a silicone elastomer resin that does not contain a vinyl group.

[0024] The silicone elastomer resin is preferably a millable type. Millable type silicone elastomer resins are non-liquid (e.g., solid or paste-like) with no self-flowability at room temperature (25°C) in an uncrosslinked state, but can be mixed with other components in a kneader or the like, and can be uniformly mixed with additives, etc., as described below. Furthermore, being a millable type silicone elastomer resin improves productivity.

[0025] Furthermore, in the silicone layer, the silicone elastomer resin is preferably crosslinked. By being crosslinked, the silicone elastomer layer is likely to be imparted with cushioning properties and has improved compression set, making it suitable for use as a release material during press molding, a buffer material, etc. Furthermore, as will be described later, the silicone layer is more preferably a radiation-crosslinked product crosslinked by radiation.

[0026] The silicone layer of the present invention preferably contains a metal oxide. By containing a metal oxide, the silicone layer has improved heat resistance and the weight loss rate at 380°C described above is reduced. Furthermore, the tensile stress retention at break and the tensile strain retention at break after the heat treatment described above can be increased. Examples of metal oxides include titanium oxide, iron oxide, and cerium oxide, and among these, titanium oxide and iron oxide are preferred. Furthermore, iron oxide is more preferred from the viewpoint of maintaining a high tensile strain at break retention rate, and titanium oxide is more preferred from the viewpoint of appearance such as coloring. The metal oxides may be used alone or in combination of two or more.

[0027] The metal oxide content in the silicone layer is preferably 0.1 to 10% by mass, more preferably 0.3 to 7% by mass, even more preferably 0.5 to 5% by mass, and particularly preferably 0.7 to 3% by mass. By ensuring that the metal oxide content is equal to or greater than the lower limit, heat resistance is appropriately improved, and the weight loss rate at 380°C is sufficiently reduced. On the other hand, by ensuring that the metal oxide content is equal to or less than the upper limit, heat resistance can be improved without impairing the cushioning properties and other performance of the silicone layer.

[0028] Furthermore, it is also preferable that the silicone layer of the present invention contains carbon black. By containing carbon black, the silicone layer has improved heat resistance and the above-mentioned weight loss rate at 380°C is reduced. Furthermore, the above-mentioned tensile stress retention rate and tensile strain retention rate at break after heat treatment can be increased. Furthermore, flame resistance can also be improved. Examples of carbon black include graphitized carbon, furnace black, acetylene black, and ketjen black. Of these, furnace black is preferred in terms of availability and price. Carbon black may be used alone or in combination of two or more types.

[0029] The carbon black content in the silicone layer is preferably 0.05 to 10% by mass, more preferably 0.1 to 5% by mass, even more preferably 0.2 to 3% by mass, and particularly preferably 0.3 to 2% by mass. By ensuring that the carbon black content is equal to or greater than the lower limit, heat resistance is appropriately improved and the weight loss rate at 380°C is sufficiently reduced. On the other hand, by ensuring that the carbon black content is equal to or less than the upper limit, heat resistance and flame resistance can be improved without impairing the cushioning and other performance properties of the silicone layer.

[0030] The silicone layer may also contain various additives that impart functionality to the elastomer, such as reinforcing fillers (e.g., fumed silica, precipitated silica, diatomaceous earth, and quartz powder), various processing aids, and heat resistance improvers. These may be used alone or in combination. Examples of additives include flame retardants, heat dissipating fillers, and conductive fillers.

[0031] The silicone layer preferably has a Type A durometer hardness of 3 or more, more preferably 5 or more, even more preferably 15 or more, particularly preferably 25 or more, especially preferably 35 or more, and most preferably 45 or more. The Type A durometer hardness is preferably 90 or less, more preferably 80 or less, even more preferably 70 or less, and especially preferably 60 or less. By setting the Type A durometer hardness at or above the lower limit, the thickness of the silicone molded article tends to be less likely to change even with repeated use, for example, during press molding, maintaining sufficient cushioning properties and excellent durability. Furthermore, the tackiness of the surface of the silicone molded article tends to be moderately suppressed, tending to improve handleability. On the other hand, by setting the Type A durometer hardness at or below the upper limit, the conformability and adhesion to pressed products during press molding, etc., tend to be improved. The 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 blended into the silicone layer as a filler, and appropriately selecting the type of silicone raw material. From the viewpoints of conformability and adhesion to a molded body during press molding, and also surface tackiness of the silicone layer, the tensile storage modulus of the silicone layer at 23°C is, for example, 100 MPa or less, 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. Also, it is preferably 0.1 MPa or more, more preferably 0.5 MPa or more, and even more preferably 1 MPa or more.

[0032] Commercially available silicone elastomer resins containing metal oxides as heat resistance enhancers can also be used. Examples of commercially available silicone elastomer resins include "X-30-3888-U" manufactured by Shin-Etsu Chemical Co., Ltd., which contains 1 to 3% by mass of iron oxide as a metal oxide, "TSE2323-5U" manufactured by Momentive Performance Materials, Inc., which contains 1 to 10% by mass of titanium oxide as a metal oxide, and "TSE2323-7U" manufactured by Momentive Performance Materials, Inc., which contains 0.1 to 1% by mass of titanium oxide as a metal oxide.

[0033] The thickness of the silicone layer may 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. From the viewpoints 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.

[0034] [Polyimide layer] The polyimide layer of the present invention contains polyimide as a main component. The polyimide layer of the present invention preferably has a temperature at which 2% weight loss occurs by thermogravimetry of 260°C or higher. A temperature of 260°C or higher improves the heat resistance of the polyimide layer, and when used in combination with the silicone layer described above, the heat resistance of the laminate is further improved. Therefore, in various applications where the laminate is used in high-temperature environments, the laminate can be repeatedly used for a long period of time without deteriorating in performance. From the viewpoints of heat resistance, durability, etc., the temperature at which 2% weight loss occurs by thermogravimetry is more preferably 275°C or higher, even 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 polyimide layer loses 2% weight by thermogravimetry is not particularly limited, but may be, for example, 750°C or lower, or 700°C or lower. The temperature at which a weight loss of 2% occurs by thermogravimetry is the temperature at which a sample taken from the polyimide layer is heated in the atmosphere and the weight loss is 2% relative to the initial weight. Specifically, this can be measured by the method described in the Examples.

[0035] The polyimide layer of the present invention preferably has a tensile storage modulus of 2 GPa or more at 300°C. When the tensile storage modulus at 300°C is 2 GPa or more, dimensional changes such as in-plane stretching of the laminate are suppressed even when pressure is applied to the laminate at high temperatures by press molding or the like. Therefore, even if strain occurs between the silicone layer and the laminate, peeling does not occur, making the laminate easier to use repeatedly in high-temperature environments. From the viewpoint of reducing dimensional changes even when pressure is applied in high-temperature environments, 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 upper limit of the tensile storage modulus at 300° C. is not limited, and may be, for example, 10 GPa or less, 7 GPa or less, or 6 GPa or less.

[0036] The polyimide layer preferably has a tensile storage modulus at 23°C greater than that of the silicone layer at 23°C. The polyimide layer preferably has a tensile storage modulus at 23°C of 3.7 GPa or greater. When the polyimide layer has a high tensile storage modulus at room temperature, it has good handleability, making it easier to set on a molded body during molding, for example. Furthermore, when a laminate is produced by a lamination method or the like, tension is easily applied even though the polyimide layer is thin, facilitating production, and the resulting laminate is likely to have fewer wrinkles. From the viewpoint of ease of handling and ease of production, the tensile storage modulus at 23°C is preferably 4 GPa or more, more preferably 4.5 GPa or more, even more preferably 5 GPa or more, particularly preferably 6 GPa or more, and most preferably 7 GPa or more. The upper limit of the tensile storage modulus at 23° C. is not limited, and may be, for example, 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 measured using a viscoelasticity spectrometer for the polyimide layer alone. The tensile storage modulus of the silicone layer at 23°C can also be measured using a viscoelasticity spectrometer for the silicone layer alone. The tensile storage modulus can be measured in the resin flow direction (MD: Machine Direction). However, if the MD is unknown, the value in the direction in which the tensile storage modulus is highest can be used.

[0037] The polyimide layer has a linear expansion coefficient of 33 x 10 -6 / °C or less. The linear expansion coefficient of the polyimide layer is preferably 33×10 -6 / °C or less, the dimensional change is small even after repeated use at temperatures changed from low to high, and the dimensional stability is high. Therefore, it can be used suitably for various applications in high temperature environments. The linear expansion coefficient of the polyimide layer is 27 x 10 -6 / ℃ or less is preferable, and 22 × 10 -6 / °C or less is more preferable, and 18 × 10 -6 / °C or less is even more preferable, and 14×10 -6 The linear expansion coefficient of the polyimide layer is particularly preferably, but is not particularly limited to, for example, 5×10 -6 / ℃ or more, 8 × 10 -6 / °C or more.

[0038] 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 comes into contact with a mold such as a press plate during press molding, and if the arithmetic mean roughness (Ra) is 26 nm or less, the polyimide layer is less likely to slip relative to the mold such as a press plate when an initial pressure is applied, resulting in good moldability when used as a mold release material, cushioning material, etc. Furthermore, as described below, 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 a molding die such as a press plate, and the other contacts a molded body. Therefore, when the arithmetic mean roughness of both outermost surfaces is small, the laminate is less likely to slip not only against a molding die such as a press plate, but also against a molded body, and the moldability is further improved when used as a release agent, a cushioning material, etc. From the viewpoint of preventing displacement of the molded body or the press plate or the like relative to the mold, the arithmetic mean roughness (Ra) is more preferably 20 nm or less, even more preferably 17 nm or less, still more preferably 13 nm or less, and particularly preferably 10 nm or less. The lower limit of the arithmetic mean roughness (Ra) is not particularly limited, but is, for example, 0.5 nm, preferably 1 nm, more preferably 1.5 nm, and even more preferably 2 nm. When the arithmetic mean roughness is 0.5 nm or more, when the laminates of the present invention are stacked together, the protrusions come into point contact, suppressing adhesion between the laminates, making it easier to obtain a laminate with excellent peelability. The laminates also tend to be easier to handle, for example, when they are removed one by one. Furthermore, when the mold, such as a press plate, is opened after press molding to remove the molded product, the problem of the laminate adhering to the mold, such as a press plate, is alleviated, and productivity also tends to improve. Furthermore, when both outermost surfaces of the laminate are polyimide layers, there is the advantage that the contact state with the molded product can be suitably good, making it easier to align the molded product. The surface roughness (Ra) is measured by a three-dimensional non-contact surface profiler under the measurement conditions described in the examples.

[0039] The method for adjusting the arithmetic mean roughness is not particularly limited. 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 a mirror-polished metal roll, an endless metal belt, a polymer film, or the like used as the support.

[0040] The polyimide contained in the polyimide layer of the present invention may be any polyimide obtained by polymerizing a tetracarboxylic acid or a tetracarboxylic dianhydride with a diamine, and is preferably an aromatic polyimide, specifically, one obtained by polymerizing an aromatic tetracarboxylic acid or an aromatic tetracarboxylic dianhydride with an aromatic diamine and / or an aliphatic diamine. The aliphatic diamine includes an alicyclic diamine.

[0041] As the polyimide contained in the polyimide layer of the present invention, for example, a polyimide represented by the following general formula (2) is used. [ka] (Note that in formula (2), R1 is a tetravalent organic group containing an aromatic ring, R 2 is a divalent organic group containing an aromatic ring, and m is an integer of 1 or greater.

[0042] R 1 The tetravalent organic group R may have an aromatic ring, and examples thereof include organic groups having 6 to 24 carbon atoms, preferably 6 to 18 carbon atoms, and more preferably 6 to 12 carbon atoms. 1 Examples of the tetracarboxylic acid residue include aromatic tetracarboxylic acid residues, and specific examples include the following formulae (3-1) to (3-5).

[0043] [ka]

[0044] Among the above, either of formulas (3-1) or (3-2) is preferred, and among these, an organic group represented by either of the following (3-1') or (3-2') is preferred, and an organic group represented by the following (3-1') is more preferred. [ka]

[0045] The polyimide represented by general formula (2) is R 1 Among these, the organic group represented by either (3-1') or (3-2') is contained in an amount of, for example, 50 mol % or more, preferably 70 mol % or more, more preferably 90 mol % or more, and most preferably 100 mol %.

[0046] R 2 The divalent organic group R may have an aromatic ring, and examples thereof include organic groups having 6 to 24 carbon atoms, preferably 6 to 18 carbon atoms, and more preferably 6 to 15 carbon atoms. 2 The divalent organic group is preferably an organic group represented by either of the following formulas (4) and (5).

[0047] [ka] (Note that in formula (4), R 3 and R 4 are each independently a hydrogen atom, a methyl group, or a halogen atom. In formula (5), the group represented by X is a single bond, an oxygen atom, a sulfur atom, C=O, -CH2-, -CH(CH3)-, -C(CH3)2-, -SO2-, or -C(CF3)2-. R 5 , R 6 , R 7 , and R 8 are each independently a hydrogen atom, a methyl group, or a halogen atom.

[0048] The polyimide represented by general formula (2) is R 2 It is preferable that at least a part of the R 2 When at least a part of the organic groups is represented by formula (4), the heat resistance is improved, the temperature at which 2% weight loss occurs is also increased, the tensile storage modulus at 300°C is also increased, and the linear expansion coefficient of the polyimide layer is easily reduced. In the formula (2), the bonding positions of the formula (4) are preferably 1 and 4 from the viewpoint of heat resistance and a low coefficient of linear expansion. 3 , R 4 are preferably hydrogen atoms. 2 It is more preferable that at least a part of the groups is an organic group represented by the following formula (4-1). [ka]

[0049] The polyimide represented by general formula (2) is R 2 Among these, the organic group represented by the above formula (4-1) 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 %.

[0050] In equation (2), R 2At least a part of the organic group represented by the formula (4) (preferably the formula (4-1)) is R 2 A part of R may be an organic group having an aromatic ring other than that of the above formula (4). 2 is, for example, a divalent organic group having 12 to 24 carbon atoms, preferably 12 to 18 carbon atoms, more preferably 12 to 15 carbon atoms. Specifically, an organic group represented by the above formula (5) is preferred.

[0051] In formula (5), X is preferably an oxygen atom, and R 5 , R 6 , R 7 , and R 8 are preferably hydrogen atoms. Furthermore, the bonding positions in formula (5) are preferably the 4,4' positions. Therefore, the organic group represented by formula (5) is more preferably an organic group represented by the following formula (5-1). A preferred embodiment of the compound of formula (2) is R 2 At least a part of these is an organic group represented by the above formula (4) (preferably formula (4-1)), and the remainder is an organic group represented by the following formula (5-1).

[0052] [ka]

[0053] The polyimide is preferably a polyimide obtained by polymerizing 3,3',4,4'-biphenyltetracarboxylic acid or its dianhydride with 1,4-phenylenediamine, and specifically, a polyimide represented by the following formula (6) is preferred. Use of the polyimide represented by the following formula (6) provides good heat resistance and a high temperature at which the polyimide layer loses 2% weight. It also facilitates the production of a polyimide layer with a low linear expansion coefficient and a high tensile storage modulus at 300°C. Commercially available polyimides represented by formula (6) can be used, and a specific example is "Upilex-S" manufactured by Ube Industries, Ltd.

[0054] [ka] In the formula (6), m is the same as above.

[0055] Further, the polyimide is preferably a polyamide obtained by copolymerizing pyromellitic acid or its dianhydride with paraphenylenediamine and 4,4'-diaminodiphenyl ether. Specifically, in the above formula (2), R 1 is an organic group of formula (3-2'), and R 2 It is preferable that the polyimide is a copolymer in which a part of the organic group of formula (4-1) and the remainder of the organic group of formula (5-1) is used. By controlling the combination of monomers (sequence control), the copolymer polyimide can be made to have a low linear expansion coefficient while exhibiting relatively good heat resistance. Specifically, by reacting 4,4'-diaminodiphenyl ether with pyromellitic dianhydride in advance and then adding paraphenylenediamine, a polyimide with a low linear expansion coefficient and excellent heat resistance can be obtained. This makes it easier to increase the tensile storage modulus of the polyimide layer at 300°C and the temperature at which it exhibits a 2% weight loss. Commercially available copolymer polyimides can also be used, such as "Apical NPI" manufactured by Kaneka Corporation.

[0056] Polyimide is also 2 At least a part of R does not need to be the organic group represented by the above formula (4), 2 may be a polyimide represented by the above formula (5), preferably the above formula (5-1), in which case R 1 It is more preferable that the formula is (3-2'). Such polyimides may be commercially available products, and specific examples include "Apical AH" manufactured by Kaneka Corporation and "Kapton" manufactured by Toray DuPont Co., Ltd.

[0057] In addition to polyimide, the polyimide layer of the present invention may contain other resins, fillers, and various additives, such as heat stabilizers, ultraviolet absorbers, light stabilizers, nucleating agents, colorants, lubricants, and flame retardants, as appropriate, without departing from the spirit of the present invention. The content of other resins is not particularly limited, and may be, for example, about 50 parts by mass or less, 30 parts by mass or less, or 10 parts by mass or less, relative to 100 parts by mass of polyimide. However, it is preferable that the resin in the polyimide layer consists of polyimide.

[0058] The thickness of the polyimide layer may be appropriately selected depending on the application, but from the viewpoint of imparting the desired heat resistance and dimensional stability to the laminate without impairing the cushioning properties imparted 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, particularly preferably 15 μm or more. Note that, when polyimide layers are provided on both sides of the silicone layer, the thickness of the polyimide layer refers to the thickness of each polyimide layer provided on both sides of the silicone layer.

[0059] 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. With the thickness ratio within the above range, the laminate has good heat resistance and moderate elasticity, making it suitable for use as a release material or a cushioning material. From these perspectives, 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. When polyimide layers are provided on both sides of the silicone layer, it is preferable that the thickness of each polyimide layer provided on each side of the silicone layer be within the above-mentioned range.

[0060] [Laminated structure] The laminate of the present invention may include a polyimide layer and a silicone layer, or may have a laminate structure in which 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 laminate structure. In this laminate structure, the polyimide layer may constitute one outermost surface of the laminate, and the silicone layer may constitute the other outermost surface. More specifically, the laminate may have a two-type two-layer structure, or may have a two-type two-layer structure plus a primer layer (described below) between the polyimide layer and the silicone layer. In the above laminate structure, when the laminate is used as a release material or cushioning material during molding by press molding or the like, the polyimide layer side may be placed on the mold side, such as a press plate, and the silicone layer side may be placed on the molded body side. With this arrangement, the polyimide layer makes the laminate less likely to slip relative to the mold, while the silicone layer provides good releasability from the molded body.

[0061] The laminate of the present invention may also have a laminate structure in which polyimide layers are provided on both sides of a silicone layer. That is, the laminate of the present invention may have a polyimide layer / silicone layer / polyimide layer laminate structure. In this laminate structure, the polyimide layers may constitute both outermost surfaces of the laminate. More specifically, the laminate may have a two-kind three-layer structure, or in addition to the two-kind three-layer structure, a primer layer (described below) may be provided between either or both of the polyimide layer and the silicone layer. With such a laminate structure, when the laminate is used as a release material or buffer material during molding, such as press molding, the polyimide layer reduces slippage relative to the mold and molded article, making it easier to obtain molded articles with high surface smoothness. Furthermore, when the silicone layer is heated, low-molecular-weight siloxane components, such as low-molecular-weight cyclic siloxanes, may precipitate and adhere to the mold and the resulting molded article, causing contamination. However, providing polyimide layers on both sides prevents the precipitation of low-molecular-weight siloxane components and suppresses contamination by low-molecular-weight siloxane components. Furthermore, when a silicone film is used as a mold release material or cushioning material, it may be subjected to heat treatment or the like to remove low-molecular-weight siloxane components adhering to the molding die, but by providing polyimide layers on both sides, the frequency of heat treatment can be reduced.

[0062] As a method for preventing contamination of the molded body due to precipitation of the low-molecular-weight siloxane component as described above and for easily obtaining a molded body with high surface smoothness, a method may be employed in which a laminate having a polyimide layer provided on only one side of a silicone layer is used, with the silicone layer side positioned on the mold side such as a press plate, and the polyimide layer side positioned on the molded body side.

[0063] (primer layer) In each laminate structure, the polyimide layer may be laminated directly onto the silicone layer, or 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 a 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-curable silicone resins, among which addition type silicone resins are preferred. These can be used alone or in combination of two or more.

[0064] Examples of addition-type silicone resins include those obtained by compounding polymethylhydrogensiloxane as a crosslinking agent with polydimethylsiloxane containing vinyl groups as a base polymer, and then reacting and curing the resulting mixture in the presence of a platinum catalyst. Condensation type silicone resins include those obtained by blending polydimethylsiloxane containing silanol groups at the terminals as the base polymer with polymethylhydrogensiloxane as the crosslinking agent, and then heat curing in the presence of an organotin catalyst. Examples of UV-curable silicone resins include those that use polydimethylsiloxane containing acryloyl groups or methacryloyl groups as the base polymer, those that use polydimethylsiloxane containing mercapto groups and vinyl groups as the base polymer, the aforementioned addition-type silicone resins, or those that use polydimethylsiloxane containing epoxy groups that cure by a cationic curing mechanism as the base polymer, and are compounded with a photopolymerization initiator and cured by irradiation with UV light. Furthermore, the primer layer may contain a silane coupling agent, an adhesion improver, and the like, as needed.

[0065] The silane coupling agent may be, for example, a compound represented by the general formula ZSiX3. In the above general formula, Z is an organic group having about 1 to 20 carbon atoms and having a functional group such as a vinyl group, an epoxy group, an amino group, or a mercapto group, and X is a hydrolyzable functional group such as a methoxy group or an ethoxy group, or an alkyl group. 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, an epoxy group, an amino group, or a 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 an ethoxy group, or an alkyl group.

[0066] Examples of silane coupling agents include vinyltriethoxysilane, vinyltrimethoxysilane, γ-glycidylpropyltrimethoxysilane, γ-glycidylpropyltriethoxysilane, N-β(aminoethyl)-γ-aminopropyltrimethoxysilane, N-β(aminoethyl)-γ-aminopropylmethyldimethoxysilane, γ-mercaptopropyltrimethoxysilane, etc. These may be used alone or in combination of two or more.

[0067] A preferred example of the adhesion improver is a siloxane having an epoxy group at the molecular chain terminal or in the side chain.

[0068] 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. A thickness equal to or greater than the lower limit mentioned above tends to provide a cured coating of uniform thickness and sufficient adhesion to the silicone layer. Furthermore, although the silicone resin constituting the primer layer generally does not have very high film strength, a thickness equal to or less than the upper limit mentioned above tends to suppress cohesive failure of the primer layer and increase the strength of the laminate.

[0069] (cover film) When the laminate of the present invention has a laminate structure in which a polyimide layer is provided on only one side of the 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 be made of a resin film other than a polyimide layer or a silicone layer. The material for 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, from the viewpoints of heat resistance and mechanical strength, it is preferable to contain a polyester resin, and it is more preferable to contain a polyester resin as the main component.

[0070] Among polyester resins, it is preferable to use crystalline polyester resins, and examples of crystalline polyester resins include polyethylene terephthalate and polyethylene naphthalate. Among them, polyethylene terephthalate is preferable from the viewpoints of heat resistance, film stiffness, smoothness, ease of commercial availability, etc. These may be used alone or in combination of two or more.

[0071] The cover film may also contain additives such as ultraviolet absorbers, light stabilizers, antioxidants, plasticizers, nucleating agents, lubricants, pigments, dyes, etc., within the scope of not impairing the effects of the present invention. From the viewpoint of mechanical strength, it is preferably stretched at least uniaxially, and more preferably biaxially. The cover film may be a process film used when forming 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 material, cushioning material, anti-slip material, carrier film, etc.

[0072] 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.

[0073] <Method of manufacturing laminate> The method for producing 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 methods can be used for the lamination method.

[0074] For example, a polyimide layer may be prepared, a silicone layer may be prepared separately, and the two may be laminated together, a polyimide layer may be prepared, a silicone layer may be prepared on the polyimide layer, and the two may be laminated together, or conversely, a silicone layer may be prepared, a polyimide layer may be prepared on the silicone layer, and the two may be laminated together, or a polyimide layer and a silicone layer may be prepared and then laminated together. Also, when a 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 where the polyimide layer is not provided.

[0075] The polyimide layer and the silicone layer are preferably laminated together while the silicone layer is not crosslinked, and then the silicone layer is crosslinked after forming a laminate. If the silicone layer is crosslinked after laminating the silicone layer and the polyimide layer, the polyimide layer can be laminated and integrated with the silicone layer with high adhesive strength.

[0076] The polyimide layer and the silicone layer can be laminated by a co-extrusion method, a lamination method, etc. In the co-extrusion method, the polyimide layer and the silicone layer may be simultaneously kneaded and co-extruded and laminated by a feed block method or a multi-manifold method, etc. The lamination method may include a method in which a polyimide layer and a silicone layer are separately prepared to obtain a polyimide layer and a silicone layer, and then laminating the obtained layers. Alternatively, a silicone layer may be formed on a pre-prepared polyimide layer and then laminated.

[0077] A primer layer may be provided between the polyimide layer and the silicone layer as described above. In this case, the primer layer may be formed by applying a primer agent to the polyimide layer and then appropriately drying and curing the primer agent. Then, a silicone layer may be laminated on the polyimide layer on which the primer layer has been formed. The primer agent contains a base polymer for forming the primer layer and, if necessary, a crosslinking agent, a photopolymerization initiator, a catalyst, a silane coupling agent, an adhesion improver, etc., and is preferably diluted with a solvent. To improve the leveling and adhesion of the primer agent, the surface of the silicone layer and / or polyimide layer to which the primer agent is applied may be subjected to a surface treatment such as corona treatment in advance. Furthermore, the primer agent is preferably cured by heating at a temperature of, for example, about 50 to 150°C, although this is not particularly limited.

[0078] The laminate of the present invention is preferably produced by a lamination method. In the lamination method, silicone, preferably a silicone elastomer resin, mixed with metal oxides and other additives as needed using a kneader or the like, is introduced, preferably in an uncrosslinked state, into a pair of polyimide films, each of which forms a polyimide layer, drawn out from two directions, or between a polyimide film and a cover film. Here, the silicone may be introduced between the films by extruding it from a T-die or the like using an extruder or the like. Thereafter, the thickness is adjusted as needed using the gap between the rolls to obtain a laminate in which a silicone layer, preferably an uncrosslinked silicone layer, is formed between the films. However, in this case, the cover film may be omitted as appropriate.

[0079] Furthermore, it is preferable to crosslink the silicone when it is in an uncrosslinked state, but the crosslinking is preferably carried out after laminating the silicone layer and the polyimide layer as described above. Examples of the crosslinking method include a method in which a crosslinking agent or the like is added to the silicone in advance, and crosslinking is carried out by heat, light such as ultraviolet light, moisture in the air, or the like, and a method in which crosslinking is carried out by irradiation with radiation.

[0080] In particular, it is preferable to crosslink the silicone layer by irradiation with radiation. Crosslinking by irradiation with radiation is preferable because it does not involve concerns about impairing heat resistance due to crosslinking agent residues, and it does not cause wrinkles during crosslinking, as occurs in crosslinking by heating. It is also preferable for ensuring adhesion between the silicone layer and the polyimide layer. Examples of radiation include electron beams, X-rays, and gamma rays. These radiations are widely used industrially, are readily available, and are energy-efficient. Among these, gamma rays are preferably used because they have almost no absorption loss and are highly transparent.

[0081] The dose of gamma rays 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 dose of gamma rays 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 dose is equal to or greater than 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 dose is equal to or less than the upper limit, no decomposition reaction occurs, and an increase in low-molecular-weight siloxane components can be suppressed.

[0082] <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, in the case of a silicone elastomer resin, suitable adhesion and conformability to various parts. The laminate of the present invention is preferably used, for example, in the manufacturing process of various molded products, particularly in press molding, vacuum molding, pressure molding, etc., and in such cases, it may be used as a mold release material, cushioning material, anti-slip material (sealing material), etc. The laminate can also be used as a carrier film for transporting a workpiece, a protective film for protecting a workpiece, etc.

[0083] Among the above, the laminate is preferably used as a mold release material or a cushioning material in various molding processes such as press molding, vacuum molding, pressure molding, etc. Specifically, it is preferably used as a cushioning material that is placed between a molding die (metal mold) and a molded body in a molding process to evenly distribute the pressure acting on the molded body, or to ensure the mold releasability of the molded body from the molding die. Among the above, the laminate is more preferably used as a cushioning material or release material for press molding. In press molding, the laminate is preferably placed between a workpiece and a press plate when pressing the molded body (workpiece) with the press plate. In this case, for example, when a polyimide layer is provided on only one side of the silicone layer, the polyimide layer side is preferably placed on the press plate side, and the silicone layer side is preferably placed on the workpiece side. The temperature during press molding 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 molding include water / hydraulic press molding, roll press molding, and belt press molding.

[0084] The laminate of the present invention is preferably used when molding circuit boards, semiconductors, other electronic components, etc., which are incorporated into electric or electronic products. The press molding is not particularly limited, but is preferably a process carried out in the process of manufacturing components of, for example, FPCs and solid-state batteries, and is also preferably a process carried out when pressure-bonding an ACF (anisotropic conductive film) to a circuit board.

[0085] The laminate of the present invention has a polyimide layer, which makes it less prone to wrinkling and bending and has high heat resistance, thereby improving the productivity of molded articles when used in various molding processes. Furthermore, the silicone layer has high heat resistance and is less susceptible to embrittlement, allowing it to maintain good cushioning properties and suppress dimensional changes over long periods of time even under high-temperature heating. Therefore, the laminate of the present invention can be used repeatedly over long periods of time as a release material, a cushioning material, etc.

[0086] 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 laminate structure of a silicone layer / a polyimide layer, and the article to be transported is preferably placed on the silicone layer constituting the outermost surface and transported. The silicone layer, particularly when the silicone is a silicone elastomer resin, has slight adhesion, so that 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 is transported, for example, by a belt conveyor.

[0087] In the carrier film, the polyimide layer may be used 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 using a polyimide layer instead of a metal plate can reduce the weight of the transport carrier. Furthermore, because the polyimide layer has high rigidity, it can be appropriately used as a support instead of a metal plate. Furthermore, if the polyimide layer of the present invention is one that has high heat resistance, is less likely to deform when heated, and has a low linear expansion coefficient, as described above, it will be less susceptible to thermal degradation even when used in a high-temperature environment (e.g., about 200 to 350°C, preferably about 250 to 320°C), and problems such as peeling of the silicone layer from the polyimide layer will be less likely to occur, allowing for repeated use over a longer period of time.

[0088] The transported object may be, but is not limited to, a circuit board, a semiconductor, or other electronic components incorporated into an electrical or electronic product. The carrier film is preferably a reflow carrier that carries the transported object (workpiece) on it. The reflow process may involve heating to, for example, 200°C or higher. As described above, the laminate of the present invention can be repeatedly used even in a high-temperature environment, making it particularly suitable for use as a reflow carrier.

[0089] [Release material, cushioning material, anti-slip material] In another aspect, the present invention provides a laminate (X1) for use as any one of a release material, a cushioning material, and an anti-slip material. The laminate (X1) is 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) having a tensile storage modulus of 1 GPa or more at 23°C, and the weight loss rate of the resin layer (A) at 380°C measured by thermogravimetry is 9% by mass or less.

[0090] In the present laminate (X1), the resin layer (A) has a tensile storage modulus of 100 MPa or less at 23°C, which results in good conformability to molded articles, adhesion, and surface tackiness during press molding, etc. Furthermore, the resin layer (B) has a tensile storage modulus of 1 GPa or more at 23°C, which results in good handleability. Therefore, the present laminate (X1) can be suitably used as a release material, a buffer material, and an anti-slip material. Details of the release material, buffer material, and anti-slip material are as described above, and it is preferable to use the resin layer (A) instead of the silicone layer and the resin layer (B) instead of the polyimide layer. In the present laminate (X1), the weight loss rate of the resin layer (A) at 380°C is 9% by mass or less, which prevents the resin layer (A) from becoming embrittled, and allows the laminate (X1) to be used repeatedly over a long period of time in a high-temperature environment in each of the above-mentioned applications. The weight loss rate of the resin layer (A) at 380°C is preferably 7% by mass or less, more preferably 6% by mass or less, and even more preferably 5% by mass or less. The lower the weight loss rate at 380°C, the better; it is sufficient if it is 0% by mass or more, for example, 1% by mass or more.

[0091] From the viewpoints of conformability and adhesion to a molded body during press molding, etc., and surface tackiness of the resin layer (A), the resin layer (A) has a tensile storage modulus at 23°C of 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. Also, the resin layer (A) has a tensile storage modulus of preferably 0.1 MPa or more, more preferably 0.5 MPa or more, and even more preferably 1 MPa or more.

[0092] 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, in terms of excellent heat resistance, electrical properties such as insulating properties, mold releasability, etc., it is preferable to use silicone as the main component in the resin layer (A). When silicone is used, the silicone may be as described above, and the resin layer (A) is the same as the silicone layer described above.

[0093] From the viewpoint of improving handleability and dimensional accuracy, such as suppressing deformation of the laminate during press molding when used as a release agent, the resin layer (B) has a tensile storage modulus at 23°C of preferably 3 GPa or more, more preferably 3.7 GPa or more, even more preferably 4.5 GPa or more, particularly preferably 5 GPa or more, particularly preferably 6 GPa or more, and most preferably 7 GPa or more. Also, it is preferably 15 GPa or less, more preferably 13 GPa or less, and even more preferably 11 GPa or less.

[0094] The resin constituting the resin layer (B) is not particularly limited, and examples thereof include curable resins such as polyimide, bismaleimide, and benzoxazine; thermoplastic resins such as thermoplastic polyimide, polyamideimide, olefin resin, styrene resin, polyester resin, polycarbonate resin, polyamide resin, polyetherimide resin, polyphenylene sulfide resin, polyphenylene ether resin, and polyether ketone resins such as polyether ether ketone; polytetrafluoroethylene resin (PTFE), tetrafluoroethylene-perfluoroalkoxyethylene copolymer resin (PFA), and liquid crystal polymer. Among these, from the viewpoint of heat resistance and mechanical strength, preferred are 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; and crystalline thermoplastic resins with a crystalline melting temperature (Tm) of 300°C or higher, such as polyether ether ketone-based resins, polytetrafluoroethylene resin (PTFE), tetrafluoroethylene-perfluoroalkoxyethylene copolymer resin (PFA), and liquid crystal polymers. Among these, it is more preferred to use polyimide as the main resin because of its excellent heat resistance, rigidity, etc. Note that Tg and Tm refer to values ​​determined from a DSC curve measured during reheating using a differential scanning calorimeter in accordance with JIS K7121:2012. When polyimide is used, the polyimide may be as described above, and the resin layer (B) is the same as the polyimide layer described above.

[0095] The various properties of the resin layer (B), such as the temperature at which 2% weight loss is measured by thermogravimetry, the tensile storage modulus at 23°C and 300°C, the coefficient of linear expansion, the arithmetic mean roughness (Ra) of the outermost surface of the laminate formed by the resin layer (B), and the thickness, are the same as those of the polyimide layer described above, and therefore a detailed description thereof is omitted. The various properties of the resin layer (A), such as the tensile stress retention at break after heat treatment for 3 hours at 300°C, the tensile strain retention at break after heat treatment for 3 hours at 300°C, the initial stress at break, the initial strain at break, the type A durometer hardness, and the thickness, are the same as those of the silicone layer described above, and the thickness ratio of the resin layer (A):resin layer (B) is the same as that of the silicone layer:polyimide layer, and therefore a detailed description thereof is omitted.

[0096] The resin layer (B) may be laminated directly onto the resin layer (A), or 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 a silicone resin, more preferably contains a silicone resin as a main component, in order to ensure adhesion to the primer layer (A). Details of the primer layer containing a silicone resin are as described above. In the laminate (X1), the resin layer (B) may be provided on only one surface of the resin layer (A) or on both surfaces. When the resin layer (B) is provided on only one surface of the resin layer (A), the aforementioned cover film may be provided on the other surface.

[0097] [Laminates for press molding, vacuum molding, and pressure molding] In yet another aspect, the present invention provides a laminate (X2) for use in any one of 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) having a tensile storage modulus of 1 GPa or more at 23°C, and the weight loss rate of the resin layer (A) at 380°C measured by thermogravimetry is 9% by mass or less.

[0098] In the present laminate (X2), the resin layer (A) has a tensile storage modulus of 100 MPa or less at 23°C, which results in good conformability, adhesion, and surface tackiness to molded articles in press molding, vacuum molding, and pressure molding. Furthermore, the resin layer (B) has a tensile storage modulus of 1 GPa or more at 23°C, which results in good handleability and makes it suitable for use as a release material or buffer material in these molding processes. Details of the press molding, vacuum molding, or pressure molding, and the release material or buffer material are as described above, and it is preferable to use the resin layer (A) instead of the silicone layer and the resin layer (B) instead of the polyimide layer. In the present laminate (X2), the weight loss rate of the resin layer (A) at 380°C as measured by thermogravimetry is 9% by mass or less, which prevents the resin layer (A) from becoming embrittled, and allows the laminate to be used repeatedly over a long period of time in a high-temperature environment. The structure of the laminate (X2) in this embodiment is the same as that of the laminate (X1) described above, and detailed description thereof will be omitted.

[0099] [Carrier film] In yet another aspect, the present invention provides a laminate (X3) for use in a carrier film, which comprises a resin layer (A) having a tensile storage modulus of 100 MPa or less at 23°C and a resin layer (B) having a tensile storage modulus of 1 GPa or more at 23°C, and the weight loss rate of the resin layer (A) at 380°C measured by thermogravimetry is 9% by mass or less.

[0100] In the laminate (X3), the resin layer (A) has a tensile storage modulus of 100 MPa or less at 23°C, which improves the surface tackiness of the resin layer (A), and the resin layer (B) has a tensile storage modulus of 1 GPa or more, which ensures a certain level of strength, making it suitable for use as a carrier film. The details of the carrier film are as described above, and it is preferable to use the resin layer (A) instead of the silicone layer and the resin layer (B) instead of the polyimide layer. Furthermore, in this laminate (X3), the weight loss rate of the resin layer (A) at 380°C as measured by thermogravimetry is 9% by mass or less, which prevents the resin layer (A) from becoming embrittled, and allows the laminate (X) to be used repeatedly over a long period of time in a high-temperature environment, making it suitable for use as a reflow carrier, etc. The structure of the laminate (X3) in this embodiment is the same as that of the laminate (X1) described above, and detailed description thereof will be omitted. [Example]

[0101] The present invention will be explained in more detail below with reference to examples, but the present invention is not limited by these examples in any way.

[0102] In the present examples and comparative examples, the evaluation was carried out as follows.

[0103] (1) Weight loss rate at 380℃ A sample taken from the silicone layer was heated using a thermogravimetric and differential scanning calorimeter (TG-DSC) under the following conditions, and the weight loss at 380°C was measured, and the ratio of the weight loss at 380°C to the initial weight was calculated. Measuring device: "STA200RV", manufactured by Hitachi High-Tech Science Corporation Measurement conditions: Measurement was performed by raising the temperature from 35°C to 800°C at a rate of 20°C / min. Conducted in an air atmosphere.

[0104] (2) Tensile fracture stress retention rate and tensile fracture strain retention rate For the film made from the silicone raw material that forms the silicone layer of the laminate produced by the method described below, a 10 mm wide strip-shaped test piece was fixed with a distance of 20 mm between the grippers, and pulled at a pulling rate of 500 mm / min in a tensile testing machine (Shimadzu Corporation, Autograph AGS-X) in an environment of 23°C and 50% RH, and the initial tensile stress at break and the tensile strain at break were measured, in accordance with JIS K7127:1999. Similarly, the test piece was heat-treated by heating for 3 hours in a thermostatic chamber controlled at 300°C, and the tensile stress at break and the tensile strain at break of the heat-treated test piece were similarly measured to obtain the tensile stress at break and the tensile strain at break after heat treatment. The measurements were carried out in the MD. The ratio of the tensile fracture stress after heat treatment to the initial tensile fracture stress was defined as the tensile fracture stress retention rate after heat treatment at 300°C for 3 hours. The ratio of the tensile fracture strain after heat treatment to the initial tensile fracture strain was defined as the tensile fracture strain retention rate after heat treatment at 300°C for 3 hours.

[0105] (3) Transfer amount of low molecular weight cyclic siloxane component (press molding) The resulting laminates of Examples 1 and 4 were overlaid with clean paper and pressed for 10 minutes at a temperature of 100°C and a pressure of 10 MPa in a press to evaluate the amount of low-molecular-weight cyclic siloxane transferred to the clean paper. In the case of laminates with a single polyimide layer, the clean paper was overlaid on the silicone layer surface, and in the case of laminates with double polyimide layers, the clean paper was overlaid on one of the polyimide layers.

[0106] (Quantitative determination of low molecular weight cyclic siloxanes) The internal standard solution was prepared by precisely weighing 5 mg of decamethylcyclopentasiloxane (cyclic siloxane pentamer (D5 siloxane)), placing it in a 100 mL measuring flask, and diluting it with acetone. 25cm of clean paper after pressing 2 A sample was cut out, weighed precisely, and placed in a sample bottle. 10 mL of the above internal standard solution was then weighed into the bottle. The sample bottle was then capped, wrapped in parafilm, and left to immerse at room temperature for 16 hours for extraction. The acetone solution in the sample bottle was then measured for low-molecular-weight cyclic siloxane content using gas chromatography (GC) under the following measurement conditions. The column temperature was maintained at 70°C for 1 minute, then increased to 320°C at a rate of 25°C / min, and maintained there for 5 minutes before measurement.

[0107] (Measurement conditions) Measurement device: GC-2010Plus (Shimadzu Corporation) Column: Ultra ALLOY Capillary Column-UA1 (MS / HT) (100% dimethylpolysiloxane, length 30 m, inner diameter 0.25 mm, film thickness 0.1 μm) Carrier gas: Helium ·Flow rate: 1mL / min Detector: FID

[0108] (Calculation method for cyclic siloxane content) Using the amount of D5 siloxane as the internal standard and the GC peak area as the standard, each of the cyclic siloxanes D4 to D20 was quantified from the peak area derived from each cyclic siloxane Dn (Dn is a D4 to D20 siloxane, a cyclic siloxane having a dimethylsiloxane unit), and the total content was evaluated. Regarding D5 siloxane, quantification was performed by subtracting the amount of D5 siloxane as the internal standard. A content of less than 30 ppm by mass was designated as the detection limit "ND."

[0109] (4) Thickness change after pressing Test pieces measuring 10 cm x 10 cm were cut out from the obtained laminates of Example 1 and Comparative Example 1, and pressed in a vacuum at a temperature of 300°C and a pressure of 100 kg / cm using a high-temperature vacuum press (manufactured by Kitagawa Seiki Co., Ltd.). 2 The press molding was performed under the condition of a holding time of 10 minutes, and the thickness before pressing and the thickness after pressing were measured at five arbitrary points, and the thickness change was calculated using the average value of the five points.

[0110] (5) Tensile storage modulus The tensile storage modulus of a polyimide film forming a polyimide layer or a film (thickness 100 μm) made of a silicone resin raw material forming a silicone layer prepared by the method described below was measured at 23°C and 300°C using a viscoelasticity spectrometer in accordance with JIS K7244-4:1999 under the following conditions. Measurement device name: "DVA-200", manufactured by IT Instrument & Control Co., Ltd. Distance between chucks: 25mm Distortion: 0.07% Width: approx. 4mm Temperature: -50 to 350°C Frequency: 1Hz Measurement method: Tensile Heating rate: 3℃ / min Measurement direction: MD

[0111] (6) Thermogravimetry (temperature of 2% weight loss) For the thermogravimetric measurement, a sample taken from the polyimide layer was heated using a thermogravimetric differential scanning calorimeter (TG-DSC) under the following conditions, and the temperature at which the weight loss relative to the initial weight was 2% was read. Measuring device: "STA200RV", manufactured by Hitachi High-Tech Science Corporation Measurement conditions: Measurement was performed by raising the temperature from 35°C to 800°C at a rate of 20°C / min. Conducted in an air atmosphere.

[0112] (7) Linear expansion coefficient The polyimide film forming the polyimide layer was measured using a thermomechanical analyzer under the following measurement conditions. Measuring device: "TMA / SS7100", manufactured by Hitachi High-Tech Science Corporation Test piece width: 3 mm Chuck distance: 10 mm Mode: Tensile Measurement direction: MD Temperature conditions: The temperature was raised from 15 to 330°C at a rate of 5°C / min, and then lowered to 15°C at a rate of 5°C / min. The sample lengths were measured at 300°C and 30°C during the temperature drop, and the linear expansion coefficient (1 / °C) was calculated. The measurement direction was MD.

[0113] (8) 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 profiler (manufactured by Ryoka Systems Co., Ltd. under the trade name "VertScan2.0 R5200G") with a 5x objective lens and a measurement range of 948.76 μm × 711.61 μm.

[0114] (Method for preparing silicone films for evaluating tensile fracture stress retention, tensile fracture strain, and tensile storage modulus) The raw materials for the silicone resin layer listed in Table 1 were supplied between two cover films (biaxially oriented PET film, Mitsubishi Chemical Corporation's "Diafoil T-100", thickness: 100 μm) supplied along two 100 mm diameter calendars, and a bank was formed on the roll at a roll temperature of 80°C to produce a laminate consisting of cover film / silicone layer / cover film. The resulting laminate with cover film was irradiated with gamma rays to an absorbed dose of 50 kGy to crosslink the silicone elastomer resin in the silicone layer, and the cover film was peeled off from the crosslinked laminate to obtain a silicone film for evaluation.

[0115] Example 1 A primer agent containing an addition-type silicone resin, an adhesion promoter, and a curing catalyst, diluted with a toluene solvent, was applied to a polyimide film (Ube Industries, Ltd., "Upilex-S," thickness: 25 μm) using a roll coating method so that the thickness after drying would be 0.3 μm. The film was then dried at 120°C for 30 seconds and heat-treated to obtain a polyimide film with a primer layer on one side.

[0116] The silicone resin layer was prepared using millable silicone elastomer resin (Momentive Performance Materials, Inc., "TSE2323-5U"; titanium dioxide (1.1% by mass) metal oxide content, tensile storage modulus 2.6 MPa (23°C), Type A durometer hardness 50 (manufacturer's nominal value)). The silicone elastomer resin was applied between a primer layer of polyimide film and a biaxially oriented PET film (Mitsubishi Chemical Corporation, "Diafoil T-100"; thickness 100 μm) as a cover film along two 100 mm diameter calendars. A bank was formed on the roll at 80°C to produce a polyimide / silicone laminate. A cover film was attached to the silicone layer.

[0117] The resulting laminate with cover film was irradiated with gamma rays to an absorbed dose of 50 kGy, crosslinking the silicone elastomer resin and obtaining a laminate in which the polyimide layer and the silicone layer were integrated. The silicone layer had a thickness of 100 μm. The cover film was peeled off from the resulting laminate to prepare a laminate for evaluation. The laminate was evaluated for weight loss at 380°C, and for tensile stress retention and tensile strain retention after heat treatment at 300°C for 3 hours. The results are shown in Table 1. Furthermore, when the polyimide layer was evaluated, the tensile storage modulus at 300°C was 4.0 GPa, the tensile storage modulus at 23°C was 9.7 GPa, the temperature at which 2% weight loss occurred was 588°C, and the linear expansion coefficient was 11 × 10 -6 / ° C. The arithmetic mean roughness (Ra) of the outermost surface of the laminate, which was made up of the polyimide layer, was 2.6 nm.

[0118] Example 2 A laminate was prepared in the same manner as in Example 1, except that a millable silicone elastomer resin ("TSE2323-7U" manufactured by Momentive Performance Materials, Inc., containing titanium oxide as a metal oxide (0.8% by mass), tensile storage modulus of 5.7 MPa (23°C), and Type A durometer hardness of 70 (manufacturer's nominal value)) was used as the raw material for the silicone resin layer.

[0119] Example 3 A laminate was produced in the same manner as in Example 1, except that a millable silicone elastomer resin ("X-30-3888-U" manufactured by Shin-Etsu Chemical Co., Ltd., containing iron oxide (2.4% by mass) and carbon black (0.3 to 1% by mass) as metal oxides, with a tensile storage modulus of 5.2 MPa (23°C) and a Type A durometer hardness of 60 (manufacturer's nominal value)) was used as the raw material for the silicone resin layer.

[0120] Example 4 The same procedure as in Example 1 was carried out, except that instead of a cover film, a polyimide film 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.

[0121] Example 5 A laminate was prepared in the same manner as in Example 4, except that a millable silicone elastomer resin ("TSE2323-7U" manufactured by Momentive Performance Materials, Inc., containing 0.8% by mass of titanium oxide) was used as the raw material for the silicone resin layer.

[0122] Example 6 A laminate was produced in the same manner as in Example 4, except that a millable silicone elastomer resin ("X-30-3888-U" manufactured by Shin-Etsu Chemical Co., Ltd., containing 2.4% by mass of iron oxide and 0.3 to 1% by mass of carbon black) was used as the raw material for the silicone resin layer.

[0123] Comparative Example 1 A laminate was prepared in the same manner as in Example 1, except that a millable silicone elastomer resin ("TSE2571-5U" manufactured by Momentive Performance Materials, Inc., without metal oxide) was used as the raw material for the silicone resin layer.

[0124] [Table 1] *In Comparative Example 1, "-" indicates that measurement was not possible.

[0125] As shown in Table 1, in Examples 1 to 6, the silicone layer had a low weight loss rate at 380°C and high heat resistance, resulting in high fracture stress retention and fracture strain retention after heat treatment, and high performance was maintained even after repeated use over a long period of time in a high-temperature environment. Therefore, even when the laminate was repeatedly used in a high-temperature environment as a release material, buffer material, carrier film, etc., the cushioning properties of the silicone layer were not lost and embrittlement was prevented. Furthermore, as shown in Examples 4 to 6, when polyimide layers are provided on both sides, the amount of low-molecular-weight siloxane adhering to the press machine in the press test is reduced, and it can be seen that the molded body and mold are less likely to be contaminated. Furthermore, thickness changes (dimensional changes) due to press molding are suppressed, and it can be seen that the thickness is less likely to change even when used repeatedly during press molding, etc., and that sufficient cushioning properties are maintained and the product has excellent durability. On the other hand, in Comparative Example 1, the silicone layer had a high weight loss rate at 380°C and low heat resistance, resulting in embrittlement after heat treatment, making it impossible to measure the fracture stress and fracture strain. Furthermore, the thickness (dimensional change) due to press molding was larger than in the Examples. Therefore, it is difficult to use the silicone layer repeatedly over a long period of time in a high-temperature environment as a release material, cushioning material, carrier film, etc.

Claims

1. A laminate comprising a silicone layer and a polyimide layer, A laminate in which the weight loss rate of the silicone layer at 380°C as measured by thermogravimetry is 9% by mass or less.

2. The laminate according to claim 1 , wherein a polyimide layer is provided on both sides of the silicone layer.

3. 2. The laminate according to claim 1, wherein the polyimide layer is provided on only one side of the silicone layer, and a cover film is provided on the other side of the silicone layer.

4. The laminate according to any one of claims 1 to 3, wherein the silicone layer contains 0.1 to 10% by mass of titanium oxide.

5. 5. The laminate according to claim 1, wherein the tensile storage modulus at 23° C. of the polyimide layer is greater than the tensile storage modulus at 23° C. of the silicone layer.

6. 6. The laminate according to claim 1, wherein the silicone layer has a tensile stress at break retention rate of 10% or more after heat treatment at 300° C. for 3 hours.

7. 7. The laminate according to claim 1, wherein the silicone layer has a tensile strain retention at break of 10% or more after heat treatment at 300° C. for 3 hours.

8. 8. The laminate according to claim 1, wherein the thickness ratio of the silicone layer to the polyimide layer is 99:1 to 20:

80.

9. The laminate according to any one of claims 1 to 8, which is used as a release material, a cushioning material, or an anti-slip material.

10. The laminate according to any one of claims 1 to 8, which is used in any one of press forming, vacuum forming, and pressure forming.

11. The laminate according to any one of claims 1 to 8, which is used as a carrier film.

12. A laminate comprising a resin layer (A) having a tensile storage modulus at 23°C of 100 MPa or less and a resin layer (B) having a tensile storage modulus at 23°C of 1 GPa or more, the weight loss rate of the resin layer (A) at 380°C as determined by thermogravimetry is 9% by mass or less, A laminate used as any one of a release material, a cushioning material, and an anti-slip material.

13. A laminate comprising a resin layer (A) having a tensile storage modulus at 23°C of 100 MPa or less and a resin layer (B) having a tensile storage modulus at 23°C of 1 GPa or more, the weight loss rate of the resin layer (A) at 380°C as determined by thermogravimetry is 9% by mass or less, A laminate used in press molding, vacuum molding, or pressure molding.

14. A laminate comprising a resin layer (A) having a tensile storage modulus at 23°C of 100 MPa or less and a resin layer (B) having a tensile storage modulus at 23°C of 1 GPa or more, the weight loss rate of the resin layer (A) at 380°C as determined by thermogravimetry is 9% by mass or less, Laminate used as a carrier film.

15. 9. A method for using the laminate according to claim 1, wherein the laminate is used as a release agent or a cushioning material during molding.

16. A method for using the laminate according to any one of claims 3 to 8, wherein when the laminate is used as a release material or a cushioning material during molding, the cover film is peeled off, and the polyimide layer side is placed on a molding mold side and the silicone layer side is placed on a molded product side.

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