Laminate and method for producing laminate

Abstract

A laminate which is characterized by having a conductive layer, a non-porous layer, and a dielectric porous layer, the dielectric porous layer containing a liquid crystal polymer, and the non-porous layer being formed from a liquid composition containing a soluble liquid crystal polymer.

Description

Technical Field

[0001] The present invention relates to a laminate and a method for manufacturing the laminate. Background Art

[0002] Conventionally, a laminate in which a conductive layer is provided on at least one surface of a porous polymer film has been known.

[0003] For example, Patent Document 1 describes a porous low-dielectric polymer film useful as a sheet for a millimeter-wave antenna, and describes a laminate including the low-dielectric polymer film and a conductive layer. In the low-dielectric polymer film, fine pores are dispersed and formed in a film containing a polymer material. The low-dielectric polymer film has pores with a given average pore diameter and a given porosity. The porous structure in the low-dielectric polymer film is a closed-cell structure. The porous low-dielectric polymer film is produced as follows: a porogen such as polyoxyethylene dimethyl ether is insolubilized in a polyimide precursor, and after extracting the porogen using supercritical carbon dioxide, the polyimide precursor is converted (imidized) into polyimide.

[0004] Prior Art Documents Patent Documents Patent Document 1: Japanese Unexamined Patent Application Publication No. 2019-123851 Summary of the Invention Problems to be Solved by the Invention However, in the laminate as described above, a non-porous layer serving as a substantially smooth surface layer is usually formed on the surface of the dielectric porous layer which is a porous low-dielectric polymer film. The surface layer is formed, for example, when the dielectric porous layer is pressed against the conductive layer. However, the formation of such a surface layer mostly requires high temperature and a long time, which places a large burden on the manufacture of the laminate.

[0005] An object of the present invention is to provide a laminate in which a non-porous layer can be disposed on the surface of a dielectric porous layer at a lower temperature, and a method for manufacturing the laminate.

[0006] Means for Solving the Problems That is, the present invention includes the following.

[0007] [1] A laminate, characterized by having a conductive layer, a non-porous layer, and a dielectric porous layer, the dielectric porous layer contains a liquid crystal polymer, the non-porous layer is formed of a liquid composition containing a soluble liquid crystal polymer.

[0008] [2] The laminate according to [1], wherein the proportion of the thickness of the non-porous layer in the laminate is 0.5% to 7%.

[0009] [3] The laminate according to [1] or [2], wherein the relative dielectric constant of the laminate is 2.3 or less.

[0010] [4] The laminate according to any one of [1] to [3], wherein the dielectric porous layer has a continuous bubble structure.

[0011] [5] The laminate according to any one of [1] to [4], wherein the melting point of the liquid crystal polymer contained in the dielectric porous layer is 280 °C or higher.

[0012] [6] The laminate according to any one of [1] to [5], wherein the soluble liquid crystal polymer is a polymer containing a structural unit represented by the following formula (1), a structural unit represented by the following formula (2), and a structural unit represented by the following formula (3).

[0013] [Chemical formula 1] (In formula (1), Ar 1 represents 1,4-phenylene, 2,6-naphthylene or 4,4'-biphenylene.

[0014] In formula (2), Ar 2 represents 1,4-phenylene, 1,3-phenylene, 4,4'-biphenylene, 2,6-naphthylene or a group represented by the following formula (Q).

[0015] In formula (3), Ar 3 represents 1,4-phenylene, 1,3-phenylene, 2,6-naphthylene or a group represented by the following formula (Q), X represents -NH- or -O-, and Y represents -NH- or -O-.

[0016] represents a bonding bond.) [Chemical formula 2] (In formula (Q), Ar 11 and Ar 12 each independently represent phenylene or naphthylene, and Q represents -O-, -C(=O)- or -S(=O) 2 -. represents a bonding bond.) [7] The laminate according to [6], wherein the soluble liquid crystal polymer has at least any one of a polymerizable unsaturated group, a structure after reaction of the polymerizable unsaturated group, and an imide bond.

[0017] [8] The laminate according to any one of [1] to [7], wherein the laminate has the non-porous layer between the conductive layer and the dielectric porous layer.

[0018] [9] The laminate according to [8], wherein the laminate further has a second non-porous layer on a side of the dielectric porous layer opposite to the non-porous layer side.

[0019]

[10] The laminate according to [9], wherein the laminate further has a second conductive layer on a side of the second non-porous layer opposite to the dielectric porous layer side.

[0020]

[11] A method for manufacturing a laminate, which is a method for manufacturing the laminate according to any one of [1] to

[10] , the method includes a step of coating a liquid composition containing the soluble liquid crystal polymer on the conductive layer to form the non-porous layer.

[0021] Advantageous Effects of the Invention According to the present invention, it is possible to provide a laminate capable of disposing a non-porous layer on the surface of a dielectric porous layer at a lower temperature, and a method for manufacturing the laminate. Description of the Drawings

[0022] Figure 1A is a diagram (part 1) for explaining an embodiment of a method for manufacturing a dielectric porous layer.

[0023] Figure 1B is a diagram (part 2) for explaining an embodiment of a method for manufacturing a dielectric porous layer.

[0024] Figure 1C is a diagram (part 3) for explaining an embodiment of a method for manufacturing a dielectric porous layer.

[0025] Figure 1D is a diagram (part 4) for explaining an embodiment of a method for manufacturing a dielectric porous layer.

[0026] Figure 2 is a diagram for explaining the degree of orientation.

[0027] Figure 3 is a schematic cross-sectional view of an embodiment of the laminate of the present invention.

[0028] Figure 4 is a schematic cross-sectional view of another embodiment of the laminate of the present invention.

[0029] Figure 5 is a schematic cross-sectional view of another embodiment of the laminate of the present invention.

[0030] Figure 6 It is a schematic cross-sectional view of another embodiment of the laminate of the present invention.

[0031] Figure 7A It is a view (part 1) for explaining an embodiment of the manufacturing method of the laminate of the present invention.

[0032] Figure 7B It is a view (part 2) for explaining an embodiment of the manufacturing method of the laminate of the present invention.

[0033] Figure 7C It is a view (part 3) for explaining an embodiment of the manufacturing method of the laminate of the present invention.

[0034] Figure 7D It is a view (part 4) for explaining an embodiment of the manufacturing method of the laminate of the present invention. Detailed Embodiments

[0035] (Laminate) The laminate of the present invention has a conductive layer, a non-porous layer, and a dielectric porous layer.

[0036] The laminate may further have a second non-porous layer, a second conductive layer, etc.

[0037] The dielectric porous layer contains a liquid crystal polymer.

[0038] The non-porous layer contains a soluble liquid crystal polymer.

[0039] <Conductive Layer> The conductive layer (sometimes referred to as the "first conductive layer") is not limited to a specific layer as long as it has conductivity.

[0040] The conductive layer contains, for example, a metal. The metal contained in the conductive layer is not limited to a specific metal. The conductive layer contains, for example, copper, iron, silver, gold, aluminum, nickel, their alloys (stainless steel, bronze), etc.

[0041] The conductive layer can be a metal foil, a plated layer, a vapor deposition layer, or a sputtered layer.

[0042] Regarding the thickness of the conductive layer, there is no particular limitation. The thickness of the conductive layer is, for example, 0.1 μ m or more, preferably 1 μ m or more, and, for example, 100 μ m or less, preferably 50 μ m or less.

[0043] <Dielectric Porous Layer> The dielectric porous layer has a large number of fine pores (air holes). In addition, as the bubble structure of the dielectric porous layer, for example, an independent bubble structure (single bubble structure) and a continuous bubble structure (connected bubble structure) can be cited.

[0044] The independent bubble structure means that there are no holes or the like that connect the air holes in the resin part between the air holes, and the gas does not flow between adjacent air holes. In contrast, the continuous bubble structure means that adjacent air holes are connected by holes and the gas flows between the air holes.

[0045] In the case where the dielectric porous layer has a continuous bubble structure, if the dielectric porous layer does not have a surface layer on the surface, the dielectric porous layer is easily compressed due to the hot pressing during the manufacture of the laminate. The compression of the dielectric porous layer causes an increase in the relative dielectric constant of the dielectric porous layer. To prevent compression, it is effective to form a surface layer on the surface of the dielectric porous layer. However, in the case of forming a surface layer by melting the surface of the dielectric porous layer, it is necessary to heat the dielectric porous layer to a temperature exceeding the melting point of the polymer constituting the dielectric porous layer, which requires a high temperature and a long time. This becomes significant when the dielectric porous layer mainly contains a high melting point polymer.

[0046] In contrast, in the case of the laminate of the present invention, by forming a non-porous layer from a liquid composition, the non-porous layer can be disposed on the surface of the dielectric porous layer at a lower temperature.

[0047] Therefore, in terms of the manufacturing process, it is possible to manufacture a laminate having a dielectric porous layer with a continuous bubble structure without increasing the load and without significantly compressing the dielectric porous layer in the manufacture of the laminate.

[0048] From the above aspects, the present invention is particularly useful in the case where the dielectric porous layer contains a high melting point liquid crystal polymer (for example, a liquid crystal polymer having a melting point of 280 °C or higher).

[0049] In addition, when forming a surface layer on the surface of the dielectric porous layer during the hot pressing of the conductive layer and the dielectric porous layer, it is necessary to set the temperature of the hot pressing to a temperature exceeding the melting point of the polymer constituting the dielectric porous layer.

[0050] On the other hand, in the case of the laminate of the present invention, a non-porous layer can be formed from a liquid composition on the conductive layer, and the formed non-porous layer can be bonded to the dielectric porous layer by hot pressing to manufacture the laminate. In this case, the temperature of the hot pressing can be carried out at a temperature lower than the melting point of the polymer constituting the dielectric porous layer. Thereby, it is possible to prevent the air holes of the dielectric porous layer from being crushed during the hot pressing.

[0051] The dielectric porous layer contains, for example, a liquid crystal polymer.

[0052] The dielectric porous layer is, for example, a porous layer mainly composed of a liquid crystal polymer.

[0053] The porosity of the dielectric porous layer is not limited to a specific value. The porosity of the dielectric porous layer is, for example, 50% to 74%, may also be 51% to 65%, and may also be 55% to 60%.

[0054] The size of the pores in the dielectric porous layer is not limited to a specific value. The pores have, for example, a pore diameter of 1 to 20 μ m. In this specification, the pore diameter refers to the maximum diameter. The pore diameter of the pores can be 2 μ m or more, may also be 3 μ m or more, and may also be 5 μ m or more. The pore diameter of the pores can be 18 μ m or less, may also be 16 μ m or less, and may also be 14 μ m or less. The pore diameter of the pores in the dielectric porous layer can be determined, for example, by observing the cross-section of the dielectric porous layer using a microscope such as an optical microscope, a metallurgical microscope, and an electron microscope. In this cross-section, the maximum diameter of the pores does not necessarily appear. Therefore, for example, among 50 or more pores randomly selected from the pores that can be observed as a whole, the pore diameters that are included in the top 10% in terms of the number of pores are considered.

[0055] The relative dielectric constant of the dielectric porous layer at 10 GHz is not limited to a specific value. The relative dielectric constant of the dielectric porous layer at 10 GHz is, for example, 2.5 or less, may also be 2.2 or less, may also be 2.0 or less, may also be 1.9 or less, and may also be 1.8 or less. The relative dielectric constant of the dielectric porous layer at 10 GHz is, for example, 1.2 or more, may also be 1.3 or more, and may also be 1.4 or more.

[0056] The relative dielectric constant of the dielectric porous layer at 10 GHz after the high-temperature and high-humidity test is not limited to a specific value. The relative dielectric constant of the dielectric porous layer at 10 GHz after the high-temperature and high-humidity test is, for example, 2.5 or less, may also be 2.3 or less, may also be 2.0 or less, may also be 1.9 or less, and may also be 1.8 or less. The relative dielectric constant of the dielectric porous layer at 10 GHz after the high-temperature and high-humidity test is, for example, 1.2 or more, may also be 1.3 or more, and may also be 1.4 or more. The high-temperature and high-humidity test is performed, for example, by maintaining the environment around the dielectric porous layer at a temperature of 85 °C and a relative humidity of 85% for 168 hours.

[0057] The dielectric loss tangent of the dielectric porous layer at 10 GHz is not limited to a specific value. For example, the dielectric loss tangent is 0.0020 or less, may be 0.0018 or less, and may also be less than 0.0015.

[0058] The dielectric loss tangent of the dielectric porous layer after the high-temperature and high-humidity test at 10 GHz is not limited to a specific value. For example, the dielectric loss tangent is 0.0020 or less, may be 0.0018 or less, and may also be 0.0016 or less.

[0059] In one embodiment of the dielectric porous layer, the liquid crystal polymer as the main component is not limited to a specific polymer as long as it exhibits liquid crystallinity. The liquid crystal polymer is, for example, a thermoplastic polymer that exhibits liquid crystallinity. The liquid crystal polymer is, for example, an aromatic liquid crystal polyester. As the liquid crystal polymer, for example, the liquid crystal polymers described in Japanese Patent Application Laid-Open No. 2020-147670 and Japanese Patent Application Laid-Open No. 2004-189867 can be used. Commercially available products can be used as the liquid crystal polymer. Examples of commercially available products are the UENOLCP8100 series (low melting point type) and UENOLCP5000 series (high melting point type) manufactured by Ueno Pharmaceutical Co., Ltd. "UENOLCP" is a registered trademark of Ueno Pharmaceutical Co., Ltd. It is preferable to use the UENOLCP8100 series.

[0060] The melting point of the liquid crystal polymer is not limited to a specific value. The melting point of the liquid crystal polymer is, for example, 170 °C or higher, may be 180 °C or higher, may also be 200 °C or higher, may also be 250 °C or higher, may also be 280 °C or higher, and may also be 300 °C or higher. The melting point of the liquid crystal polymer is, for example, 350 °C or lower. The melting point of the liquid crystal polymer can be determined, for example, based on the results of differential scanning calorimetry (DSC).

[0061] The thickness of the dielectric porous layer can be 60 μ μm or more, may be 80 μ μm or more, may also be 100 μ μm or more. The thickness of the dielectric porous layer can be 800 μ μm or less, may be 600 μ μm or less, may also be 400 μ μm or less, may also be 200 μ μm or less.

[0062] <<Manufacturing method of dielectric porous layer>> As the manufacturing method of the dielectric porous layer, there is no particular limitation, and extraction methods, foaming methods, etc. can be cited. They can be carried out alone or in combination.

[0063] The dielectric porous layer can be manufactured by an extraction method including a first step, a second step, and a third step described in Japanese Unexamined Patent Application Publication No. 2022-156865.

[0064] The dielectric porous layer can be manufactured by a foaming method including a fourth step, a fifth step, a sixth step, and a seventh step described in Japanese Unexamined Patent Application Publication No. 2022-156865.

[0065] Moreover, the dielectric porous layer can be manufactured, for example, by a method for manufacturing a porous liquid crystal polymer described in detail below.

[0066] An example of the method for manufacturing a porous liquid crystal polymer is as follows: the method includes a step of extracting the inorganic salt from a composition obtained by kneading a liquid crystal polymer and an inorganic salt into a solvent having a given temperature, the given temperature is in the range of 50°C to 150°C, the inorganic salt satisfies at least one of the following conditions (I) and (II).

[0067] (I) The solubility of the inorganic salt in the solvent at the given temperature is 20 g / 100 ml or more.

[0068] (II) When 20 g of the inorganic salt is brought into contact with 100 ml of the solvent at the given temperature, the amount of the inorganic salt remaining in the solvent in solid form is 2 g or less.

[0069] Hereinafter, Figures 1A to 1D this embodiment will be described.

[0070] As Figures 1A to 1D shown, the porous liquid crystal polymer 1001 (dielectric porous layer) can be manufactured by extracting the inorganic salt 1020 from a composition 1002 obtained by kneading a liquid crystal polymer 1010 and an inorganic salt 1020 into a solvent S having a given temperature Tp. The given temperature Tp is in the range of 50°C to 150°C. In addition, the inorganic salt 1020 satisfies at least one of the following conditions (I) and (II). Thereby, the amount of the inorganic salt 1020 remaining in the porous liquid crystal polymer 1001 is small, and the porosity of the porous liquid crystal polymer 1001 can be easily adjusted to a desired state.

[0071] (I) The solubility of the inorganic salt 1020 in the solvent S at the given temperature Tp is 20 grams per 100 milliliters (g / 100 ml) or more.

[0072] (II) When 20 g of the inorganic salt 1020 is brought into contact with 100 ml of the solvent S at the given temperature Tp, the amount of the inorganic salt remaining in the solvent S in solid form is 2 g or less.

[0073] In this manufacturing method, the inorganic salt 1020 functions as a porogen. As Figure 1A and Figure 1B shown, the composition 1002 is obtained, for example, by mixing the particles of the liquid crystal polymer 1010 with the granular form of the inorganic salt 1020 and kneading the liquid crystal polymer 1010 and the inorganic salt 1020 in a state where the liquid crystal polymer 1010 has been melted. In this case, it is necessary to knead the liquid crystal polymer 1010 and the inorganic salt 1020 under temperature conditions above the melting point of the liquid crystal polymer 1010. By using the inorganic salt 1020 as a porogen, even under such temperature conditions, the porogen is not easily lost due to thermal decomposition, and it is easy to adjust the porosity of the porous liquid crystal polymer 1001 to a desired state. Assuming that an oligosaccharide is used as a porogen, above the melting point of the liquid crystal polymer, the porogen is easily lost due to thermal decomposition, and it is difficult to adjust the porosity of the porous liquid crystal polymer to a desired state. For example, it is difficult for the porous liquid crystal polymer to have a desired porosity.

[0074] When kneading the liquid crystal polymer 1010 and the inorganic salt 1020 in a state where the liquid crystal polymer 1010 has been melted, the temperature of the liquid crystal polymer 1010 is not limited to a specific value as long as it is above its melting point. Its temperature is, for example, 250 °C or higher, and can also be 280 °C or higher, can also be 300 °C or higher, can also be 320 °C or higher, can also be 350 °C or higher. Its temperature is, for example, 450 °C or lower, and can also be 400 °C or lower.

[0075] As Figure 1C shown, when dissolving the inorganic salt 1020 from the composition 1002 into the solvent S, by the solvent S having a given temperature Tp, for example, not only the inorganic salt 1020 near the surface of the composition 1002 is easily extracted into the solvent S, but also the inorganic salt 1020 inside the composition 1002 is easily extracted into the solvent S. Therefore, the porosity of the porous liquid crystal polymer 1001 is easily adjusted to a desired state. On the other hand, assuming that the temperature of the solvent S is lower than 50 °C, the amount of the inorganic salt remaining in the porous liquid crystal polymer tends to be large, and it is difficult to adjust the porosity of the porous liquid crystal polymer to a desired state.

[0076] The pressure P around the composition 1002 when extracting the inorganic salt 1020 from the composition 1002 into the solvent S A is not limited to a specific value. The pressure P A is, for example, above atmospheric pressure. In this case, the amount of the inorganic salt 1020 remaining in the porous liquid crystal polymer 1001 is less, and the porosity of the porous liquid crystal polymer 1001 is more easily adjusted to a desired state.

[0077] The pressure PA For example, the gauge pressure can be 0.5 MPa or more, 1 MPa or more, 2 MPa or more, 5 MPa or more, 10 MPa or more, 20 MPa or more, or 30 MPa or more. The pressure P A For example, the gauge pressure is 50 MPa or less.

[0078] The inorganic salt 1020 is not limited to a specific inorganic salt as long as it can be extracted into the solvent S. The inorganic salt 1020 has a mass reduction rate R of 10% by mass or less, for example. M . The mass reduction rate R M is the ratio (W1 - W2) / W1 of the difference (W1 - W2) obtained by subtracting the weight W2 of the sample at 350 °C from the initial weight W1 of the sample in thermogravimetric analysis (TGA) with respect to the initial weight W1. By the inorganic salt 1020 having a mass reduction rate R of 10% by mass or less M , in the case of melting the liquid crystal polymer 1010 and kneading the liquid crystal polymer 1010 with the inorganic salt 1020, the mass of the inorganic salt 1020 is not easily reduced. Therefore, the porosity of the porous liquid crystal polymer 1001 can be more easily adjusted to a desired state.

[0079] The mass reduction rate R of the inorganic salt 1020 M is preferably 8% or less, more preferably 5% or less, still more preferably 3% or less, and particularly preferably 1% or less.

[0080] The inorganic salt 1020 can be a sulfate, a chloride, or a carbonate. In this case, the porosity of the porous liquid crystal polymer 1001 can be more easily adjusted to a desired state. In addition, the manufacturing cost of the porous liquid crystal polymer 1001 is easily reduced, and the environmental load is also easily reduced. Examples of sulfates are sodium sulfate, potassium sulfate, lithium sulfate, magnesium sulfate, and calcium sulfate. Examples of chlorides are sodium chloride, potassium chloride, lithium chloride, magnesium chloride, and calcium chloride. Examples of carbonates are sodium carbonate, potassium carbonate, lithium carbonate, magnesium carbonate, and calcium carbonate.

[0081] The solvent S is not limited to a specific solvent as long as it satisfies at least one of the above conditions (I) and (II). The solvent S is, for example, water. In this case, the porosity of the porous liquid crystal polymer 1001 can be more easily adjusted to a desired state. In addition, the manufacturing cost of the porous liquid crystal polymer 1001 is easily reduced, and the environmental load is also easily reduced.

[0082] The solvent S can be an acidic solvent or a basic solvent. Examples of acidic solvents are hydrochloric acid, sulfuric acid, and nitric acid.

[0083] When extracting the inorganic salt 1020 from the composition 1002 into the solvent S, the solvent S is, for example, supplied around the composition 1002. Alternatively, the composition 1002 is immersed in the solvent S. A flow of the solvent S that moves along the surface may also be generated in the composition 1002. The solvent S can circulate between the space around the composition 1002 and the space away from the space around the composition 1002.

[0084] As Figure 1B shown, the composition 1002 is, for example, formed into a sheet shape. In this case, by extracting the inorganic salt 1020 from the sheet-shaped composition 1002 into the solvent S, a sheet-shaped porous liquid crystal polymer 1001 can be produced. The composition 1002 is formed into a sheet shape, for example, by subjecting a kneaded product containing the liquid crystal polymer 1010 and the inorganic salt 1020 to at least one treatment selected from pressing, rolling, and stretching. The composition 1002 may also be formed into a shape other than a sheet shape.

[0085] When the composition 1002 is in a sheet shape, the composition 1002 has, for example, a thickness of 50 μ μm to 1000 μ μm. When the composition 1002 has such a thickness, by having the solvent S at a given temperature Tp and satisfying at least one of the conditions (I) and (II) above when dissolving the inorganic salt 1020 from the composition 1002 into the solvent S, the inorganic salt 1020 present inside the composition 1002 is also easily extracted into the solvent S. As a result, the porous liquid crystal polymer 1001 has a desired thickness, and the porosity of the porous liquid crystal polymer 1001 can be easily adjusted to a desired state.

[0086] The thickness of the composition 1002 may be 60 μ μm or more, may be 80 μ μm or more, may also be 100 μ μm or more. The thickness of the composition 1002 may be 800 μ μm or less, may be 600 μ μm or less, may also be 400 μ μm or less, may also be 200 μ μm or less.

[0087] The particle size of the inorganic salt 1020 in the composition 1002 is not limited to a specific value. The inorganic salt 1020 has, for example, a particle size of 1 to 20 μ μm in the composition 1002. In this specification, the particle size refers to the maximum diameter. As described above, the inorganic salt 1020 functions as a pore-forming agent. Therefore, as Figure 1DAs shown, pores 1025 are formed in the porous liquid crystal polymer 1001, and the pores 1025 have dimensions corresponding to the particle size of the inorganic salt 1020 in the composition 1002. If the inorganic salt 1020 has a particle size of 1 to 20 μ m in the composition 1002, the dimensions of the pores 1025 in the porous liquid crystal polymer 1001 can be easily adjusted to the desired range. Thus, the porosity of the porous liquid crystal polymer 1001 can be more easily adjusted to the desired state. For example, when the composition 1002 is in the form of a sheet having a thickness of 25 μ m to 500 μ m, it is difficult to form large-sized pores that do not intersect with the liquid crystal polymer 1010 in the direction perpendicular to the main surface of the composition 1002, and the strength of the porous liquid crystal polymer 1001 tends to be high. The particle size of the inorganic salt 1020 in the composition 1002 can be determined, for example, by observing the cross-section of the composition 2 using a microscope such as an optical microscope, a metal microscope, and an electron microscope. In this cross-section, the maximum diameter of the inorganic salt 1020 may not appear. Therefore, for example, among the particle sizes of 50 or more particles randomly selected from the particles of the inorganic salt 1020 that can be observed as a whole, the particles with a particle size that is included in the top 10% in terms of the number basis.

[0088] The particle size of the inorganic salt 1020 in the composition 1002 can be 2 μ m or more, or can be 5 μ m or more, or can also be 7 μ m or more. The particle size of the inorganic salt 1020 in the composition 1002 can be 18 μ m or less, or can be 16 μ m or less, or can also be 14 μ m or less. For example, in terms of the number basis, the particle size of 50% or more of the inorganic salt 1020 is in the range of 1 to 20 μ m.

[0089] The state of the inorganic salt 1020 kneaded with the liquid crystal polymer 1010 is not limited to a specific state. Before the inorganic salt 1020 is kneaded with the liquid crystal polymer 1010, the inorganic salt 1020 exists, for example, in a form including primary particles having a particle size of 1 to 10 μ m and secondary particles having a particle size of 10 to 50 μ m. By kneading the inorganic salt 1020 in such a state with the liquid crystal polymer 1010, the particle size of the inorganic salt 1020 in the composition 1002 can be easily adjusted to the desired range, and further, the adjustment of the dimensions of the pores 1025 in the porous liquid crystal polymer 1001 can be easily adjusted to the desired range.

[0090] The particle size of the primary particles of the inorganic salt 1020 before kneading with the liquid crystal polymer 1010 can be 2 μ μm or more, and can also be 3 μ μm or more, and can also be 4 μ μm or more. The particle size of the primary particles of the inorganic salt 1020 can be 9 μ μm or less, and can also be 8 μ μm or less, and can also be 7 μ μm or less. The particle size of the secondary particles of the inorganic salt 1020 before kneading with the liquid crystal polymer 1010 can be 15 μ μm or more, and can also be 20 μ μm or more, and can also be 25 μ μm or more. The particle size of the secondary particles of the inorganic salt 1020 can be 45 μ μm or less, and can also be 40 μ μm or less, and can also be 35 μ μm or less.

[0091] The volume V of the inorganic salt 1020 20 relative to the volume V of the composition 1002 C The ratio V 20 / V C is not limited to a specific value. The ratio V 20 / V C For example, it is 50% to 74%. In this case, the porous liquid crystal polymer 1001 is likely to have the desired porosity, and the porosity of the porous liquid crystal polymer 1001 is more easily adjusted to the desired state. The ratio V 20 / V C can be 51% or more, and can also be 53% or more, and can also be 55% or more. The ratio V 20 / V C can be 70% or less, and can also be 65% or less, and can also be 60% or less.

[0092] <Non-porous layer> The non-porous layer (sometimes referred to as the "first non-porous layer") is formed from a liquid composition containing a soluble liquid crystal polymer.

[0093] The soluble liquid crystal polymer has solvent solubility, and thus a liquid composition containing the soluble liquid crystal polymer can be prepared.

[0094] Moreover, by forming the non-porous layer from the liquid composition, the non-porous layer can be disposed on the surface of the dielectric porous layer at a lower temperature.

[0095] The case of forming the non-porous layer by melt-molding the liquid crystal polymer will be described.

[0096] The melt forming method refers to a method of forming a film by extruding a kneaded product from an extruder. Regarding the film formed by the melt forming method, molecular chains are more likely to be oriented in the extrusion direction (MD, Machine Direction) than in the transverse direction with respect to the extrusion direction (the direction perpendicular to both the extrusion direction and the film thickness direction, TD, Transverse Direction). Therefore, the physical properties of the non-porous layer obtained by melting and forming a liquid crystal polymer are different in the MD and TD. For example, the difference in mechanical strength between the TD and MD of the non-porous layer manufactured by the melt forming method is large.

[0097] On the other hand, in the case where the non-porous layer is a layer formed from a liquid composition containing a soluble liquid crystal polymer, the soluble liquid crystal polymer is isotropic rather than oriented in one direction.

[0098] Therefore, in the case where the non-porous layer is a layer formed from a liquid composition containing a soluble liquid crystal polymer, when the first degree of orientation is the degree of orientation with respect to the first direction parallel to the main plane of the non-porous layer and the second degree of orientation is the degree of orientation with respect to the second direction parallel to the main plane of the non-porous layer and orthogonal to the first direction, the ratio of the first degree of orientation to the second degree of orientation, that is, the first degree of orientation / the second degree of orientation, is, for example, 0.95 or more and 1.06 or less.

[0099] As Figure 2 shown, in the non-porous layer 20, the first direction x is parallel to the main plane 20A of the non-porous layer 20. The second direction y is perpendicular to the first direction x and parallel to the main plane 20A of the non-porous layer 20. The third direction z is perpendicular to the first direction x and the second direction y. It should be noted that the first direction may be parallel to the casting direction of the liquid composition when manufacturing the non-porous layer 20.

[0100] The first degree of orientation and the second degree of orientation are measured using a microwave molecular orientation meter (for example, manufactured by Oji Scientific Instruments Co., Ltd., MOA-5012A). The microwave molecular orientation meter is a device that utilizes the fact that the transmission intensity of microwaves is different in the orientation direction and the perpendicular direction according to the orientation of molecules. Specifically, while rotating the sample, microwaves with a certain frequency (generally 4 GHz or 12 GHz) are irradiated, and the intensity of the transmitted microwaves that changes according to the orientation of molecules is measured. The interaction between the microwave electric field with a certain frequency and the dipole constituting the molecule is related to the inner product of the two vectors. Due to the anisotropy of the dielectric constant of the sample, the intensity of the microwaves changes according to the angle at which the sample is arranged, so the degree of orientation can be obtained.

[0101] <<Liquid Composition>> The liquid composition may contain only a soluble liquid crystal polymer, or may contain other components in addition to the soluble liquid crystal polymer.

[0102] <<Soluble Liquid Crystal Polymer>> The soluble liquid crystal polymer contains, for example, a structural unit represented by the following formula (1), a structural unit represented by the following formula (2), and a structural unit represented by the following formula (3).

[0103] In one embodiment, the soluble liquid crystal polymer has a polymerizable unsaturated group. Alternatively, in other embodiments, the soluble liquid crystal polymer has a structure after reaction of the polymerizable unsaturated group. Alternatively, in other embodiments, the soluble liquid crystal polymer has an imide bond. The soluble liquid crystal polymer may have two or more of a polymerizable unsaturated group, a structure after reaction of the polymerizable unsaturated group, and an imide bond.

[0104] [Chemical Formula 3] (In formula (1), Ar 1 represents 1,4-phenylene, 2,6-naphthylene or 4,4'-biphenylene.

[0105] In formula (2), Ar 2 represents 1,4-phenylene, 1,3-phenylene, 4,4'-biphenylene, 2,6-naphthylene or a group represented by the following formula (Q).

[0106] In formula (3), Ar 3 represents 1,4-phenylene, 1,3-phenylene, 2,6-naphthylene or a group represented by the following formula (Q), X represents -NH- or -O-, and Y represents -NH- or -O-.

[0107] (represents a bonding bond.) [Chemical Formula 4] (In formula (Q), Ar 11 and Ar 12 each independently represent phenylene or naphthylene, and Q represents -O-, -C(=O)- or -S(=O) 2 -. (represents a bonding bond.) As the phenylene in Ar 11 and Ar 12 , 1,4-phenylene and 1,3-phenylene are preferred.

[0108] As the naphthylene in Ar 11 and Ar 12 , 2,6-naphthylene is preferred.

[0109] The structural unit represented by formula (1) (hereinafter sometimes referred to as "structural unit (1)") is a structural unit derived from a given aromatic hydroxycarboxylic acid.

[0110] As the structural unit (1), Ar is preferably 1 a structural unit of p-phenylene (1,4-phenylene) (a structural unit derived from p-hydroxybenzoic acid), and Ar 1 is a structural unit of 2,6-naphthylene (a structural unit derived from 6-hydroxy-2-naphthoic acid).

[0111] The structural unit represented by formula (2) (hereinafter sometimes referred to as "structural unit (2)") is a structural unit derived from a given aromatic dicarboxylic acid.

[0112] As the structural unit (2), Ar is preferably 2 a structural unit of p-phenylene (1,4-phenylene) (a structural unit derived from terephthalic acid), Ar 2 is a structural unit of m-phenylene (1,3-phenylene) (a structural unit derived from isophthalic acid), and Ar 2 is a structural unit of 2,6-naphthylene (a structural unit derived from 2,6-naphthalenedicarboxylic acid).

[0113] In addition, as the structural unit (2), Ar is also preferably 2 a group represented by formula (Q) and Ar 11 and Ar 12 are each 1,4-phenylene and Q is -O- (a structural unit derived from 4,4'-dicarboxydiphenyl ether).

[0114] The structural unit represented by formula (3) (hereinafter sometimes referred to as "structural unit (3)") is a structural unit derived from a given aromatic diol, aromatic hydroxylamine or aromatic diamine.

[0115] As the structural unit (3), Ar is preferably 3 a structural unit of p-phenylene (1,4-phenylene) (a structural unit derived from hydroquinone (1,4-dihydroxybenzene), p-aminophenol or p-phenylenediamine). As Ar 3 is a structural unit of p-phenylene (1,4-phenylene), examples in formula (3) include the case where X represents -NH- and Y represents -O-, and the case where X and Y represent -O-.

[0116] By the structure of the soluble liquid crystal polymer having a polymerizable unsaturated group or after the reaction of the polymerizable unsaturated group, the soluble liquid crystal polymer is imparted with structural flexibility, and the film-forming property of the non-porous layer is improved as compared with the case of the structure of the soluble liquid crystal polymer not having a polymerizable unsaturated group and after the reaction of the polymerizable unsaturated group.

[0117] In addition, due to the structure after the reaction of the soluble liquid crystal polymer having a polymerizable unsaturated group or polymerizable unsaturated groups, the polarity of the soluble liquid crystal polymer decreases. Therefore, compared with the case where the soluble liquid crystal polymer does not have a polymerizable unsaturated group and the structure after the reaction of polymerizable unsaturated groups, the dielectric constant of the non-porous layer decreases.

[0118] Examples of the polymerizable unsaturated group include vinyl, vinylphenyl, acryloyl, methacryloyl, etc. Among them, from the aspect of imparting better film-forming properties and lower dielectric constant to the soluble liquid crystal polymer, acryloyl and methacryloyl are preferred.

[0119] The soluble liquid crystal polymer may have a polymerizable unsaturated group in the side chain of the molecular chain or may have a polymerizable unsaturated group at the end of the molecular chain. However, the soluble liquid crystal polymer preferably has a polymerizable unsaturated group at the end of the molecular chain.

[0120] The structure after the reaction of the polymerizable unsaturated group refers to the structure after the addition reaction of the polymerizable unsaturated bond possessed by the polymerizable unsaturated group. As such a structure, in the case where the polymerizable unsaturated group is methacryloyl, it can be represented by the following structure. As the addition reaction, for example, radical addition polymerization can be cited.

[0121] [Chemical formula 5] (In the structure, represents a bonding bond.) Due to the soluble liquid crystal polymer having an imide bond, due to the strong intermolecular force of the imide bond, the soluble liquid crystal polymer is imparted rigidity, and the film-forming property of the non-porous layer is improved compared with the case where the soluble liquid crystal polymer does not have an imide bond.

[0122] In addition, due to the soluble liquid crystal polymer having an imide bond, dipoles are fixed. Therefore, compared with the case where the soluble liquid crystal polymer does not have an imide bond, the dielectric constant of the non-porous layer decreases.

[0123] The soluble liquid crystal polymer may have an imide bond in the middle of the molecular chain or may have an imide bond at the end of the molecular chain.

[0124] As a mode of having an imide bond in the middle of the molecular chain, a mode of having an imide bond in the main chain or a mode of having an imide bond in the side chain can be cited.

[0125] In the case where the soluble liquid crystal polymer has an imide bond, the soluble liquid crystal polymer preferably further has a structural unit represented by the following formula (4).

[0126] [Chemical Formula 6] (In formula (4), Ar 3 is synonymous with Ar in formula (3). Y represents -NH- or -O-. 3 1 represents a bonding bond bonded to the nitrogen atom of the imide bond. represents a bonding bond. ) The soluble liquid crystal polymer preferably has a structural unit represented by the following formula (5A) (hereinafter, sometimes referred to as "structural unit (5A)") as a structure having a polymerizable unsaturated group.

[0127] [Chemical Formula 7] (In formula (5A), Z 1 represents a polymerizable unsaturated group. represents a bonding bond. ) In the soluble liquid crystal polymer, the bonding bond in formula (5A) is bonded to the oxygen atom of "-O-" in formula (1), for example.

[0128] As Z 1 , for example, vinyl, vinylphenyl, acryloyl, methacryloyl, etc. can be cited. Among them, acryloyl and methacryloyl are preferred.

[0129] The soluble liquid crystal polymer preferably has a structural unit represented by the following formula (5B) (hereinafter, sometimes referred to as "structural unit (5B)") as a structure of the structure after reaction having a polymerizable unsaturated group.

[0130] [Chemical Formula 8] (In formula (5B), Z 11 represents the structure after reaction of the polymerizable unsaturated group. 1 and represent bonding bonds. ) In the soluble liquid crystal polymer, the bonding bond in formula (5B) 1 is bonded to the oxygen atom of "-O-" in formula (1), for example.

[0131] As Z 11 , for example, the structure after an addition reaction of the polymerizable unsaturated bond possessed by Z in formula (5A) can be cited. 1

[0132] ​​The soluble liquid crystal polymer preferably has a structural unit represented by the following formula (6-1) (hereinafter sometimes referred to as "structural unit (6-1)"), a structural unit represented by the following formula (6-2) (hereinafter sometimes referred to as "structural unit (6-2)"), a structural unit represented by the following formula (6-3) (hereinafter sometimes referred to as "structural unit (6-3)"), and a structural unit represented by the following formula (6-4) (hereinafter sometimes referred to as "structural unit (6-4)") as a structure having an imide bond.

[0133] [Chemical formula 9] (In formula (6-1), R 1 ~R 4 each independently represents a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, or an aryl group having 6 to 20 carbon atoms. represents a bonding bond.

[0134] In formula (6-2), R 5 ~R 8 each independently represents a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, or an aryl group having 6 to 20 carbon atoms. represents a bonding bond.

[0135] In formula (6-3) and formula (6-4), represents a bonding bond.) The maleimide group represented by formula (6-3) is a structure having an imide bond and is also a polymerizable unsaturated group.

[0136] The structural unit represented by formula (6-4) represents the structure after the reaction of the maleimide group.

[0137] As R 1 ~R 4 in formula (6-1), a hydrogen atom is preferred.

[0138] As R 5 ~R 8 in formula (6-2), a hydrogen atom is preferred.

[0139] In the soluble liquid crystal polymer, the bonding bond in formula (6-1) is bonded to, for example, Ar 3 in formula (4).

[0140] In the soluble liquid crystal polymer, the bonding bond in formula (6-2) is bonded to, for example, Ar 3 in formula (4).

[0141] In the soluble liquid crystal polymer, the bonding bond in formula (6-3) is combined with, for example, Ar 3 in formula (4).

[0142] In the soluble liquid crystal polymer, the bonding bond bonded to the nitrogen atom in the formula (6-4) is, for example, bonded to Ar in the formula (4). 3 Bonded.

[0143] The soluble liquid crystal polymer preferably has a structural unit represented by the following formula (7) (hereinafter, sometimes referred to as "structural unit (7)") as a structure having an imide bond.

[0144] [Chemical formula 10] (In the formula (7), Z 2 represents a tetravalent organic group represented by the following formula (X3-1) to (X3-2)). Represents a bonding bond.) [Chemical formula 11] (In the formula (X3-1) and the formula (X3-2), x and y each independently represent a single bond, -O-, -C(=O)-, -COO-, 1,4-phenylene, -SO 2 -, or -CONH-. j and k each independently represent 0 or 1. Represents a bonding bond.) In the soluble liquid crystal polymer, the bonding bonds in the formula (7) are each bonded to, for example, Ar in the formula (4). 3 Bonded.

[0145] The content of the structural unit (1) in the soluble liquid crystal polymer is not particularly limited, and relative to the total amount of all the structural units constituting the soluble liquid crystal polymer (by dividing the mass of each structural unit constituting the soluble liquid crystal polymer by the formula weight of each structural unit to obtain the amount of substance equivalent (mole) of each structural unit, and summing them up), it is preferably 30 mol% or more, more preferably 30 to 70 mol%, further preferably 35 to 65 mol%, and particularly preferably 40 to 60 mol%.

[0146] The content of the structural unit (2) in the soluble liquid crystal polymer is not particularly limited, and relative to the total amount of all the structural units constituting the soluble liquid crystal polymer, it is preferably 35 mol% or less, more preferably 5 to 35 mol%, further preferably 10 to 35 mol%, and particularly preferably 20 to 30 mol%.

[0147] The content of the structural unit (3) in the soluble liquid crystal polymer is not particularly limited, and relative to the total amount of all the structural units constituting the soluble liquid crystal polymer, it is preferably 35 mol% or less, more preferably 5 to 35 mol%, further preferably 10 to 35 mol%, and particularly preferably 20 to 30 mol%.

[0148] The ratio of the content of structural unit (1) to the content of structural unit (2) in the soluble liquid crystal polymer is not particularly limited, and is represented by [content of structural unit (1)] / [content of structural unit (2)] (mol / mol), preferably 1.1 to 3, more preferably 1.4 to 2.6, and particularly preferably 1.7 to 2.3.

[0149] The ratio of the content of structural unit (1) to the content of structural unit (3) in the soluble liquid crystal polymer is not particularly limited, and is represented by [content of structural unit (1)] / [content of structural unit (3)] (mol / mol), preferably 1.1 to 3, more preferably 1.4 to 2.6, and particularly preferably 1.7 to 2.3.

[0150] The ratio of the content of structural unit (2) to the content of structural unit (3) in the soluble liquid crystal polymer is not particularly limited, and is represented by [content of structural unit (2)] / [content of structural unit (3)] (mol / mol), preferably 0.7 / 1 to 1 / 0.7, more preferably 0.8 / 1 to 1 / 0.8.

[0151] The ratio of the content of structural unit (1) to the total content of structural unit (2) and structural unit (3) in the soluble liquid crystal polymer is not particularly limited, and is represented by [content of structural unit (1)] / [content of structural unit (2) + content of structural unit (3)] (mol / mol), preferably 0.7 / 1 to 1 / 0.7, more preferably 0.8 / 1 to 1 / 0.8, and particularly preferably 0.9 / 1 to 1 / 0.9.

[0152] The content of structural unit (4) in the soluble liquid crystal polymer is not particularly limited, and is preferably 15 mol% or less, more preferably 0.5 to 15 mol%, further preferably 1 to 10 mol%, and particularly preferably 1.5 to 6 mol% relative to the total amount of all structural units constituting the soluble liquid crystal polymer.

[0153] The ratio of the content of structural unit (4) to the content of structural unit (3) in the soluble liquid crystal polymer is not particularly limited, and is represented by [content of structural unit (4)] / [content of structural unit (3)] (mol / mol), preferably 0.01 / 1 to 0.5 / 1, more preferably 0.05 / 1 to 0.3 / 1.

[0154] The total content of structural unit (5A) and structural unit (5B) in the soluble liquid crystal polymer is not particularly limited, and is preferably 20 mol% or less, more preferably 0.5 to 20 mol%, further preferably 1 to 15 mol%, and particularly preferably 5 to 15 mol% relative to the total amount of all structural units constituting the soluble liquid crystal polymer.

[0155] The content of at least any one of structural units (6-1) to structural units (6-4) in the soluble liquid crystal polymer is not particularly limited, and is preferably 15 mol% or less, more preferably 0.5 to 15 mol%, still more preferably 1 to 10 mol%, and particularly preferably 1.5 to 6 mol% based on the total amount of all structural units constituting the soluble liquid crystal polymer.

[0156] The content of structural unit (7) in the soluble liquid crystal polymer is not particularly limited, and is preferably 15 mol% or less, more preferably 0.5 to 15 mol%, still more preferably 1 to 10 mol%, and particularly preferably 1.5 to 6 mol% based on the total amount of all structural units constituting the soluble liquid crystal polymer.

[0157] <<<Method for producing soluble liquid crystal polymer>>> In the production of the soluble liquid crystal polymer, for example, a compound represented by the following formula (1A), a compound represented by the following formula (2A), and a compound represented by the following formula (3A) are used.

[0158] [Chemical formula 12] (In formula (1A), Ar 1 represents 1,4-phenylene, 2,6-naphthylene or 4,4'-biphenylene.

[0159] In formula (2A), Ar 2 represents 1,4-phenylene, 1,3-phenylene, 4,4'-biphenylene, 2,6-naphthylene or a group represented by formula (Q).

[0160] In formula (3A), Ar 3 represents 1,4-phenylene, 1,3-phenylene, 2,6-naphthylene or a group represented by the following formula (Q), X represents -NH- or -O-, and Y represents -NH- or -O-.) First, a method for producing the soluble liquid crystal polymer in the case where the soluble liquid crystal polymer does not have a polymerizable unsaturated group, the structure after the reaction of the polymerizable unsaturated group, and an imide bond will be described. This production method is, for example, the production method of a liquid crystalline polyester described in Japanese Patent Laid-Open No. 2004-315678. This production method is as follows: A method in which the phenolic hydroxyl groups and amino groups of the compound represented by formula (1A) and the compound represented by formula (3A) are acylated with an excessive amount of fatty acid anhydride to obtain an acyl compound, and the obtained acyl compound is subjected to transesterification (polycondensation) with the acylated compound represented by formula (1A) and the compound represented by formula (2A) for melt polymerization (hereinafter, this method may sometimes be referred to as the "basic production method"). As the acyl compound, a fatty acid ester obtained by pre-acylation can be used.

[0161] The addition amount of the fatty acid anhydride in the acylation reaction is preferably 1.0 to 1.2 times equivalent, more preferably 1.05 to 1.1 times equivalent, relative to the total of the phenolic hydroxyl group and the amino group.

[0162] The acylation reaction is preferably carried out at 130 to 180 °C for 5 minutes to 10 hours, more preferably at 140 to 160 °C for 10 minutes to 3 hours.

[0163] The fatty acid anhydride used in the acylation reaction is not particularly limited, and examples thereof include acetic anhydride, propionic anhydride, butyric anhydride, isobutyric anhydride, valeric anhydride, pivalic anhydride, 2-ethylhexanoic anhydride, monochloroacetic anhydride, dichloroacetic anhydride, trichloroacetic anhydride, monobromoacetic anhydride, dibromoacetic anhydride, tribromoacetic anhydride, monofluoroacetic anhydride, difluoroacetic anhydride, trifluoroacetic anhydride, glutaric anhydride, maleic anhydride, succinic anhydride, β-bromopropionic anhydride, etc.

[0164] Two or more of them can be used in combination.

[0165] From the viewpoints of price and operability, acetic anhydride, propionic anhydride, butyric anhydride, and isobutyric anhydride are preferred, and acetic anhydride is more preferred.

[0166] In the transesterification, the acyl group of the acyl compound is preferably 0.8 to 1.2 times equivalent to the carboxyl group.

[0167] The transesterification is preferably carried out while heating at a rate of 0.1 to 50 °C / minute at 130 to 400 °C, more preferably while heating at a rate of 0.3 to 5 °C / minute at 150 to 350 °C.

[0168] When carrying out the transesterification of the fatty acid ester obtained by acylation with a carboxylic acid, in order to shift the equilibrium, it is preferred to distill and remove the by-produced fatty acid and the unreacted fatty acid anhydride out of the system, such as by evaporation.

[0169] It should be noted that the acylation reaction and the transesterification can be carried out in the presence of a catalyst.

[0170] In the aforementioned basic manufacturing method, for example, the compound represented by formula (1A), the compound represented by formula (2A), the compound represented by formula (3A), and the fatty acid anhydride are mixed, and heated to carry out the acylation reaction. Then, the transesterification reaction is carried out while distilling and removing the distilled by-products and the unreacted fatty acid anhydride. As a specific example, Reference Synthesis Example 1 described in the following examples can be cited.

[0171] In one embodiment of the production of the soluble liquid crystal polymer used in the present invention, in addition to the compound represented by formula (1A), the compound represented by formula (2A), and the compound represented by formula (3A), a compound that imparts at least one of a polymerizable unsaturated group and the structure after the reaction of the polymerizable unsaturated group to the soluble liquid crystal polymer, and any one of the compounds that impart an imide bond to the soluble liquid crystal polymer are also used.

[0172] Examples of the compound that imparts at least one of a polymerizable unsaturated group and the structure after the reaction of the polymerizable unsaturated group to the soluble liquid crystal polymer include acid anhydrides having a polymerizable unsaturated group. Examples of the acid anhydrides having a polymerizable unsaturated group include acrylic anhydride and methacrylic anhydride.

[0173] Examples of the method for producing a soluble liquid crystal polymer having at least one of a polymerizable unsaturated group and the structure after the reaction of the polymerizable unsaturated group include the following method: mixing the compound represented by formula (1A), the compound represented by formula (2A), the compound represented by formula (3A), an acid anhydride having a polymerizable unsaturated group, and a fatty acid anhydride, heating to carry out an acylation reaction, and then carrying out a transesterification reaction while distilling off the by-products and unreacted fatty acid anhydride. As a specific example, Synthesis Example 1 described in the Examples below can be cited.

[0174] Examples of the compound that imparts an imide bond to the soluble liquid crystal polymer include dicarboxylic anhydrides and tetracarboxylic dianhydrides.

[0175] Examples of the dicarboxylic anhydride include aromatic dicarboxylic anhydrides. Examples of the aromatic dicarboxylic anhydrides preferably include the compound represented by the following formula (6A-1). Examples of other dicarboxylic anhydrides preferably include the compound represented by the following formula (6A-2) and the compound represented by the following formula (6A-3).

[0176] [Chemical formula 13] (In formula (6A-1), R 1 ~R 4 are respectively synonymous with R 1 ~R 4 in formula (6-1).

[0177] In formula (6A-2), R 5 ~R 8 are respectively synonymous with R 5 ~R 8 in formula (6-2).) Examples of the compound represented by formula (6A-1) include phthalic anhydride.

[0178] As the tetracarboxylic dianhydride, for example, aromatic tetracarboxylic dianhydrides can be mentioned. Here, the aromatic tetracarboxylic dianhydride refers to an acid dianhydride obtained by intramolecular dehydration of carboxyl groups bonded to an aromatic ring such as a benzene ring or a naphthalene ring.

[0179] As the aromatic tetracarboxylic dianhydride, for example, a compound represented by the following formula (7A) can be mentioned.

[0180] [Chemical formula 14] (In formula (7A), Z 2 is synonymous with Z in formula (7). 2 ) In the production of the soluble liquid crystal polymer, by using a dicarboxylic dianhydride and a compound represented by formula (3A) (wherein one of X and Y represents -NH-, and the other represents -O-), an imide bond can be introduced at the end of the soluble liquid crystal polymer.

[0181] In the production of the soluble liquid crystal polymer, by using a tetracarboxylic dianhydride and a compound represented by formula (3A) (wherein one of X and Y represents -NH-, and the other represents -O-), an imide bond can be introduced in the middle of the main chain of the soluble liquid crystal polymer.

[0182] As a method for producing a soluble liquid crystal polymer having an imide bond at the end of the molecular chain of the soluble liquid crystal polymer, for example, the following method can be mentioned: After reacting a dicarboxylic dianhydride with an excessive amount of a compound represented by formula (3A) (wherein one of X and Y represents -NH-, and the other represents -O-), a compound represented by formula (1A), a compound represented by formula (2A), and a fatty acid anhydride are mixed, and an acylation reaction is carried out by heating. Then, while distilling off the distilled by-products and the unreacted fatty acid anhydride, a transesterification reaction is carried out. As a specific example, Reference Synthesis Example 3 described in the following Examples can be mentioned.

[0183] As a method for producing a soluble liquid crystal polymer having an imide bond in the middle of the main chain of the soluble liquid crystal polymer, for example, the following method can be mentioned: After reacting a tetracarboxylic dianhydride with an excessive amount of a compound represented by formula (3A) (wherein one of X and Y represents -NH-, and the other represents -O-), a compound represented by formula (1A), a compound represented by formula (2A), and a fatty acid anhydride are mixed, and an acylation reaction is carried out by heating. Then, while distilling off the distilled by-products and the unreacted fatty acid anhydride, a transesterification reaction is carried out. As a specific example, Reference Synthesis Example 2 described in the following Examples can be mentioned.

[0184] The content of the soluble liquid crystal polymer in the composition is not particularly limited, preferably 5.0% by mass or more, more preferably 8.0 to 30.0% by mass, and particularly preferably 10.0 to 25.0% by mass.

[0185] The content of the soluble liquid crystal polymer in the non-porous layer is not particularly limited, and is preferably 70% by mass or more, more preferably 80% by mass or more, relative to the non-porous layer.

[0186] <<<Other components>>> Examples of other components include filler materials, additives, resins other than the soluble liquid crystal polymer, and the like.

[0187] Examples of the filler material include inorganic filler materials such as silica, alumina, titanium oxide, barium titanate, strontium titanate, aluminum hydroxide, and calcium carbonate; and organic filler materials such as cured epoxy resins, crosslinked benzoguanamine resins, and crosslinked acrylic resins.

[0188] The content of the filler material in the non-porous layer is not particularly limited, and is preferably 0 to 100 parts by mass relative to 100 parts by mass of the soluble liquid crystal polymer.

[0189] Examples of the additive include a leveling agent, an antifoaming agent, an antioxidant, an ultraviolet absorber, a flame retardant, a colorant, and the like.

[0190] The content of the additive in the non-porous layer is not particularly limited, and is preferably 0 to 5 parts by mass relative to 100 parts by mass of the soluble liquid crystal polymer.

[0191] Examples of the resin other than the soluble liquid crystal polymer include thermoplastic resins such as polypropylene, polyamide, amorphous polyester, polyphenylene sulfide, polyether ketone, polycarbonate, polyethersulfone, polyphenylene ether, and polyetherimide; and thermosetting resins such as phenolic resins, epoxy resins, polyimide resins, and cyanate ester resins.

[0192] The content of the resin other than the soluble liquid crystal polymer in the non-porous layer is not particularly limited, and is preferably 0 to 20 parts by mass relative to 100 parts by mass of the soluble liquid crystal polymer.

[0193] <<Manufacturing method of the non-porous layer>> The non-porous layer is obtained from the above composition.

[0194] As the manufacturing method of the non-porous layer, there is no particular limitation, and examples thereof include a method of coating a liquid composition containing a soluble liquid crystal polymer, a solvent, and optional other components and drying the same.

[0195] The content of the soluble liquid crystal polymer in the liquid composition is not particularly limited, preferably 5.0% by mass or more, more preferably 8.0 - 30.0% by mass, and particularly preferably 10.0 - 25.0% by mass.

[0196] Examples of the solvent include halogenated hydrocarbons such as dichloromethane, chloroform, 1,2-dichloroethane, 1,1,2,2-tetrachloroethane, and o-dichlorobenzene; halogenated phenols such as p-chlorophenol, pentachlorophenol, and pentafluorophenol; ethers such as diethyl ether, tetrahydrofuran, and 1,4-dioxane; ketones such as acetone and cyclohexanone; esters such as ethyl acetate and γ-butyrolactone; carbonates such as ethylene carbonate and propylene carbonate; amines such as triethylamine; nitrogen-containing heteroaromatic compounds such as pyridine; nitriles such as acetonitrile and succinonitrile; amide compounds (compounds having an amide bond) such as N-methyl-2-pyrrolidone, N,N-dimethylformamide, and N,N-dimethylacetamide; urea compounds such as tetramethylurea; nitro compounds such as nitromethane and nitrobenzene; sulfur compounds such as dimethyl sulfoxide and sulfolane; and phosphorus compounds such as hexamethylphosphoric triamide and tributyl phosphate.

[0197] These solvents can be used alone or in combination of two or more.

[0198] Among them, N-methyl-2-pyrrolidone is preferred.

[0199] The content of the solvent in the liquid composition is not particularly limited, preferably 95.0% by mass or less, more preferably 70.0 - 92.0% by mass, and particularly preferably 75.0 - 90.0% by mass.

[0200] The coating method is not particularly limited, and examples thereof include spin coating, roll coating, bar coating, screen printing, die coating, comma coating, etc.

[0201] In addition, the coating can be continuous or single-plate.

[0202] The drying method, that is, the method for removing the solvent of the liquid composition, is not particularly limited, and a method of removing the solvent by evaporation is preferred. It should be noted that here, "removing the solvent" does not necessarily mean "removing all the solvent", and for example, it includes removing the solvent sufficiently until there is no obvious weight change in the object.

[0203] The removal of the solvent is preferably carried out while heating, and the heating temperature (drying temperature) at this time is preferably 50 - 180°C.

[0204] After drying, heating can be carried out. The heating is carried out, for example, for the purpose of removing residual components and promoting crystallization.

[0205] The heating temperature is not particularly limited, and examples thereof include 300°C - 400°C.

[0206] There is no particular limitation on the heating time, and for example, it may be cited as 1 hour to 24 hours.

[0207] It should be noted that when a non-porous layer is obtained from a composition containing a soluble liquid crystal polymer, the soluble liquid crystal polymer may or may not react. As the reaction, for example, in the case where the soluble liquid crystal polymer has a polymerizable unsaturated group, an addition reaction using the polymerizable unsaturated bond can be cited.

[0208] There is no particular limitation on the relative dielectric constant of the non-porous layer, and it is preferably 3.6 or less. There is no particular limitation on the lower limit value of the relative dielectric constant, and the relative dielectric constant is, for example, 2.5 or more.

[0209] There is no particular limitation on the dielectric loss tangent of the non-porous layer, and it is preferably 0.005 or less. There is no particular limitation on the lower limit value of the dielectric loss tangent, and the dielectric loss tangent is, for example, 0.0015 or more.

[0210] The relative dielectric constant and the dielectric loss tangent can be measured, for example, by the SPDR method (split dielectric resonator method) based on ASTM D150, using a "10 GHz SPDR resonator" manufactured by QWED Corporation, at 10 GHz.

[0211] There is no particular limitation on the thickness of the non-porous layer. From the aspects of suppressing the intrusion of the liquid into the porous layer and the peeling strength of the non-porous layer, it is preferably 0.5 μ m or more, more preferably 1 μ m or more. In addition, there is no particular limitation on the upper limit value of the thickness of the non-porous layer. From the aspect of electrical properties (dielectric properties), it is preferably 10 μ m or less, more preferably 7 μ m or less.

[0212] There is no particular limitation on the proportion of the thickness of the non-porous layer in the laminate. From the aspect of electrical properties (dielectric properties), it is preferably 0.3% to 10%, more preferably 0.5% to 7%.

[0213] The film thickness of the non-porous layer can be measured, for example, using a contact type film thickness meter (model R1-205) manufactured by Peacock Corporation.

[0214] <Second non-porous layer> There is no particular limitation on the second non-porous layer.

[0215] The second non-porous layer may have the same material, structure, and thickness as the first non-porous layer, or may have a different material, structure, and thickness from the first non-porous layer.

[0216] As a specific example and a preferred example of the second non-porous layer, for example, the specific examples and preferred examples cited in the description of the first non-porous layer can be cited.

[0217] For example, the laminate has a second non-porous layer on the side of the dielectric porous layer opposite to the first non-porous layer side.

[0218] When the laminate has a second non-porous layer, there is no particular limitation on the ratio of the total thickness of the first non-porous layer and the second non-porous layer in the laminate. From the aspect of electrical properties (dielectric properties), it is preferably 0.6% to 20%, more preferably 1% to 14%.

[0219] <Second Conductive Layer> There is no particular limitation on the second conductive layer.

[0220] The second conductive layer may have the same material, structure, and thickness as the first conductive layer, or may have a different material, structure, and thickness from the first conductive layer.

[0221] As a specific example and a preferred example of the second conductive layer, for example, the specific examples and preferred examples cited in the description of the first conductive layer can be cited.

[0222] For example, the laminate has a second conductive layer on the side of the dielectric porous layer opposite to the first non-porous layer side.

[0223] For example, the laminate has a second non-porous layer on the side of the dielectric porous layer opposite to the first non-porous layer side, and further has a second conductive layer on the side of the second non-porous layer opposite to the dielectric porous layer side.

[0224] There is no particular limitation on the relative dielectric constant of the laminate, and it is preferably 2.3 or less. There is no particular limitation on the lower limit value of the relative dielectric constant. For example, the relative dielectric constant is 1.5 or more.

[0225] The relative dielectric constant of the laminate is a value measured in a state where the conductive layers (first conductive layer, second conductive layer) are not included.

[0226] For example, when the laminate has a first conductive layer, a first non-porous layer, a dielectric porous layer, a second non-porous layer, and a second dielectric layer, the relative dielectric constant of the laminate is the relative dielectric constant of the laminate of the first non-porous layer, the dielectric porous layer, and the second non-porous layer.

[0227] The embodiments of the laminate will be described with reference to the drawings.

[0228] Figure 3 It is a schematic cross-sectional view of an embodiment of the laminate.

[0229] Figure 3The stacked body 100 shown successively has a first conductive layer 1, a first non-porous layer 2, a dielectric porous layer 3, a second non-porous layer 5, and a second conductive layer 4.

[0230] The first conductive layer 1 is in contact with the first non-porous layer 2.

[0231] The first non-porous layer 2 is in contact with the dielectric porous layer 3.

[0232] The dielectric porous layer 3 is in contact with the second non-porous layer 5.

[0233] The second non-porous layer 5 is in contact with the second conductive layer 4.

[0234] Figure 4 It is a schematic cross-sectional view of another embodiment of the stacked body.

[0235] Figure 4 The stacked body 100 shown successively has a first conductive layer 1, a first non-porous layer 2, a dielectric porous layer 3, and a second non-porous layer 5.

[0236] The first conductive layer 1 is in contact with the first non-porous layer 2.

[0237] The first non-porous layer 2 is in contact with the dielectric porous layer 3.

[0238] The dielectric porous layer 3 is in contact with the second non-porous layer 5.

[0239] Figure 5 It is a schematic cross-sectional view of another embodiment of the stacked body.

[0240] Figure 5 The stacked body 100 shown successively has a first conductive layer 1, a first non-porous layer 2, a dielectric porous layer 3, and a second conductive layer 4.

[0241] The first conductive layer 1 is in contact with the first non-porous layer 2.

[0242] The first non-porous layer 2 is in contact with the dielectric porous layer 3.

[0243] The dielectric porous layer 3 is in contact with the second conductive layer 4.

[0244] Figure 6 It is a schematic cross-sectional view of another embodiment of the stacked body.

[0245] Figure 6 The stacked body 100 shown successively has a first conductive layer 1, a first non-porous layer 2, and a dielectric porous layer 3.

[0246] The first conductive layer 1 is in contact with the first non-porous layer 2.

[0247] The first non-porous layer 2 is in contact with the dielectric porous layer 3.

[0248] As a method for manufacturing the laminate of the present invention, there is no particular limitation, and the following manufacturing method of the laminate of the present invention is preferred.

[0249] (Manufacturing method of laminate) The manufacturing method of the laminate of the present invention includes a step of forming a non-porous layer.

[0250] <Step of forming non-porous layer> In the step of forming a non-porous layer, a liquid composition containing a soluble liquid crystal polymer is coated on the conductive layer to form a non-porous layer.

[0251] As specific examples and preferred examples of the liquid composition, for example, the specific examples and preferred examples of the liquid composition described in the above-mentioned manufacturing method of the non-porous layer can be cited.

[0252] As the coating method, there is no particular limitation, and for example, spin coating method, roll coating method, bar coating method, screen printing method, die coating method, comma coating method, etc. can be cited.

[0253] In addition, the coating can be continuous or single-plate.

[0254] As the drying method, that is, the method for removing the solvent of the liquid composition, there is no particular limitation, and a method of removing the solvent by evaporation is preferred. It should be noted that here, "removing the solvent" does not necessarily mean "removing all the solvent", and for example, it can be cited that the solvent is sufficiently removed until there is no obvious weight change in the object.

[0255] The removal of the solvent is preferably carried out while heating, and the heating temperature (drying temperature) at this time is preferably 50 to 180 °C.

[0256] After drying, heating can be carried out.

[0257] As the heating temperature, there is no particular limitation, and for example, 300 °C to 400 °C can be cited.

[0258] As the heating time, there is no particular limitation, and for example, 1 hour to 24 hours can be cited.

[0259] The embodiments of the manufacturing method of the laminate of the present invention will be described with reference to the drawings.

[0260] Figures 7A to 7D is a diagram for explaining an embodiment of the manufacturing method of the laminate of the present invention. It should be noted that in this embodiment, the Figure 3 shown laminate is obtained.

[0261] First, a liquid composition containing a soluble liquid crystal polymer is coated on the first conductive layer to form a first non-porous layer. A liquid composition containing a soluble liquid crystal polymer is coated on the second conductive layer to form a second non-porous layer.

[0262] Next, a first conductive layer 1 on which the first non-porous layer 2 is formed is prepared ( Figure 7A ).

[0263] Next, a dielectric porous layer 3 is placed on the first non-porous layer 2 ( Figure 7B ).

[0264] Next, a second conductive layer 4 on which the second non-porous layer 5 is formed is placed on the dielectric porous layer 3 such that the dielectric porous layer 3 is in contact with the second non-porous layer 5 ( Figure 7C ).

[0265] Then, they are clamped with a first pressing plate 51 and a second pressing plate 52 and hot-pressed.

[0266] As the heating temperature during hot pressing, there is no particular limitation, and for example, 100°C to 300°C can be cited.

[0267] As the pressure during hot pressing, there is no particular limitation, and for example, 1 MPa to 10 MPa can be cited.

[0268] As the time of hot pressing, there is no particular limitation, and for example, 50 seconds to 1000 seconds can be cited.

[0269] Thus, the Figure 3 shown laminate is obtained.

[0270] The laminate of the present invention can be suitably used as a laminated sheet for a millimeter-wave antenna, for example.

[0271] [Examples] Hereinafter, examples and comparative examples are shown to further specifically illustrate the present invention. It should be noted that the present invention is not limited to any examples and comparative examples.

[0272] <Synthesis Example 1> In a reactor equipped with a stirring device, a nitrogen inlet tube, a thermometer, and a reflux condenser, 6-hydroxy-2-naphthoic acid (17.1 g, 0.091 mol), 4-aminophenol (4.96 g, 0.045 mol), isophthalic acid (7.55 g, 0.045 mol), acetic anhydride (22.3 g, 0.22 mol), and methacrylic anhydride (1.40 g, 0.0091 mol) were added. After replacing the gas in the reactor with nitrogen, while stirring under a nitrogen stream, the temperature was raised from room temperature to 150 °C over 15 minutes, and this temperature (150 °C) was maintained while refluxing for 3 hours. Subsequently, while distilling off the by-product acetic acid and unreacted acetic anhydride that distilled out, the temperature was raised to 300 °C over 2 hours and 30 minutes, and after maintaining at 300 °C for 30 minutes, the contents were taken out from the reactor. The contents were cooled to room temperature, and the resulting solid was pulverized with a pulverizer to obtain a powdery liquid crystal polyester.

[0273] <Reference Synthesis Example 1> In a reactor equipped with a stirring device, a nitrogen inlet tube, a thermometer, and a reflux condenser, 6-hydroxy-2-naphthoic acid (11.6 g, 0.062 mol), 4-aminophenol (3.37 g, 0.031 mol), isophthalic acid (5.13 g, 0.031 mol), and acetic anhydride (15.1 g, 0.15 mol) were added. After replacing the gas in the reactor with nitrogen, while stirring under a nitrogen stream, the temperature was raised from room temperature to 150 °C over 15 minutes, and this temperature (150 °C) was maintained while refluxing for 3 hours. Subsequently, while distilling off the by-product acetic acid and unreacted acetic anhydride that distilled out, the temperature was raised to 300 °C over 2 hours and 30 minutes, and after maintaining at 300 °C for 30 minutes, the contents were taken out from the reactor. The contents were cooled to room temperature, and the resulting solid was pulverized with a pulverizer to obtain a powdery liquid crystal polyester.

[0274] <Reference Synthesis Example 2> In a reactor equipped with a stirring device, a nitrogen inlet tube, a thermometer, and a reflux condenser, 4-aminophenol (4.20 g, 0.038 mol) and N-methyl-2-pyrrolidone (9.01 g) were added. After replacing the gas in the reactor with nitrogen, stirring was carried out under a nitrogen stream. After 4-aminophenol was dissolved, TAHQ (1,4-phenylene bis(1,3-dioxo-1,3-dihydroisobenzofuran-5-carboxylate), 1.76 g, 0.0038 mol) was added. After stirring at room temperature for 2 hours, 6-hydroxy-2-naphthoic acid (14.5 g, 0.077 mol), isophthalic acid (6.39 g, 0.038 mol), and acetic anhydride (18.9 g, 0.18 mol) were added, and the temperature was raised from room temperature to 150 °C in 15 minutes and maintained at this temperature (150 °C) with reflux for 3 hours. Then, while distilling off the by-product acetic acid, unreacted acetic anhydride, and N-methyl-2-pyrrolidone that distilled out, the temperature was raised to 300 °C in 2 hours and 30 minutes, and after maintaining at 300 °C for 30 minutes, the content was taken out from the reactor. The content was cooled to room temperature, and the obtained solid was pulverized with a pulverizer to obtain a powdery liquid crystal polyester.

[0275] <Reference Synthesis Example 3> In a reactor equipped with a stirring device, a nitrogen inlet tube, a thermometer, and a reflux condenser, 4-aminophenol (5.46 g, 0.050 mol) and N-methyl-2-pyrrolidone (12.0 g) were added. After replacing the gas in the reactor with nitrogen, stirring was carried out under a nitrogen stream. After 4-aminophenol was dissolved, phthalic anhydride (0.74 g, 0.0050 mol) was added. After stirring at room temperature for 2 hours, 6-hydroxy-2-naphthoic acid (18.8 g, 0.10 mol), isophthalic acid (8.31 g, 0.050 mol), and acetic anhydride (24.5 g, 0.24 mol) were added, and the temperature was raised from room temperature to 150 °C in 15 minutes and maintained at this temperature (150 °C) with reflux for 3 hours. Then, while distilling off the by-product acetic acid, unreacted acetic anhydride, and N-methyl-2-pyrrolidone that distilled out, the temperature was raised to 300 °C in 2 hours and 30 minutes, and after maintaining at 300 °C for 30 minutes, the content was taken out from the reactor. The content was cooled to room temperature, and the obtained solid was pulverized with a pulverizer to obtain a powdery liquid crystal polyester.

[0276] <Reference Synthesis Example 4> In a reactor equipped with a stirring device, a nitrogen inlet tube, a thermometer, and a reflux condenser, 6-hydroxy-2-naphthoic acid (10.5 g, 0.056 mol), 4,4'-dicarboxydiphenyl ether (7.17 g, 0.028 mol), 1,4-dihydroxybenzene (3.06 g, 0.028 mol), and acetic anhydride (13.6 g, 0.13 mol) were added. After replacing the gas in the reactor with nitrogen, while stirring under a nitrogen stream, the temperature was raised from room temperature to 150 °C over 15 minutes, and this temperature (150 °C) was maintained while refluxing for 3 hours. Then, while distilling off the by-product acetic acid and unreacted acetic anhydride that distilled out, the temperature was raised to 300 °C over 2 hours and 30 minutes, and after maintaining at 300 °C for 30 minutes, the contents were taken out from the reactor. The contents were cooled to room temperature, and the resulting solid was pulverized with a pulverizer to obtain a powdery liquid crystal polyester.

[0277] <Reference Synthesis Example 5> In a reactor equipped with a stirring device, a nitrogen inlet tube, a thermometer, and a reflux condenser, 6-hydroxy-2-naphthoic acid (10.5 g, 0.056 mol), 4,4'-dicarboxydiphenyl ether (7.17 g, 0.028 mol), 1,4-dihydroxybenzene (3.06 g, 0.028 mol), acetic anhydride (13.6 g, 0.13 mol), and methacrylic anhydride (0.82 g, 0.0056 mol) were added. After replacing the gas in the reactor with nitrogen, while stirring under a nitrogen stream, the temperature was raised from room temperature to 150 °C over 15 minutes, and this temperature (150 °C) was maintained while refluxing for 3 hours. Then, while distilling off the by-product acetic acid and unreacted acetic anhydride that distilled out, the temperature was raised to 300 °C over 2 hours and 30 minutes, and after maintaining at 300 °C for 30 minutes, the contents were taken out from the reactor. The contents were cooled to room temperature, and the resulting solid was pulverized with a pulverizer to obtain a powdery liquid crystal polyester.

[0278] <Reference Example 1> 2.0 g of the liquid crystal polyester produced in Synthesis Example 1 was added to 18.0 g of N-methyl-2-pyrrolidone and heated to 160 °C to obtain a liquid crystal polyester solution.

[0279] The obtained liquid crystal polyester solution was applied to a copper foil by a bar coating method to a thickness of 20 - 35 μ μm after drying.

[0280] The temperature was raised from 40 °C to 80 °C over 2 hours and dried at 80 °C for 1 hour to obtain a dried sheet.

[0281] Furthermore, the obtained dried sheet was subjected to the following heating process under vacuum to promote the removal of residual components and crystallization, thereby obtaining a liquid crystal polymer sheet on the copper foil.

[0282] Heating processes (1) to (3): (1) Heat from room temperature to 350 °C over 10 hours (2) Hold at 350 °C for 3 hours (3) Cool to room temperature <Reference Example 2> Change the liquid crystal polyester used in Reference Example 1 to the liquid crystal polyester manufactured in Reference Synthesis Example 1, and form a liquid crystal polymer sheet on a copper foil in the same manner as in Reference Example 1, except for this change.

[0283] <Reference Example 3> Change the liquid crystal polyester used in Reference Example 1 to the liquid crystal polyester manufactured in Reference Synthesis Example 2, and form a liquid crystal polymer sheet on a copper foil in the same manner as in Reference Example 1, except for this change.

[0284] <Reference Example 4> Change the liquid crystal polyester used in Reference Example 1 to the liquid crystal polyester manufactured in Reference Synthesis Example 3, and form a liquid crystal polymer sheet on a copper foil in the same manner as in Reference Example 1, except for this change.

[0285] <Reference Example 5> Change the liquid crystal polyester used in Reference Example 1 to the liquid crystal polyester manufactured in Reference Synthesis Example 4, and form a liquid crystal polymer sheet on a copper foil in the same manner as in Reference Example 1, except for this change.

[0286] <Reference Example 6> Change the liquid crystal polyester used in Reference Example 1 to the liquid crystal polyester manufactured in Reference Synthesis Example 5, and form a liquid crystal polymer sheet on a copper foil in the same manner as in Reference Example 1, except for this change.

[0287] <Film Thickness> Use a contact type film thickness gauge (model R1-205) manufactured by Peacock Co., Ltd. to measure the thickness of the liquid crystal polymer sheet. The results are shown in Table 1.

[0288] <Dielectric Constant> Using the SPDR method (split dielectric resonator method) based on ASTM D150 and a "10 GHz SPDR resonator" manufactured by QWED Co., Ltd., measure the relative dielectric constant (Dk) and dielectric loss tangent (Df) of the liquid crystal polymer sheet at 10 GHz. The results are shown in Table 1.

[0289] <Measurement of the Ratio of the Second Orientation Degree to the First Orientation Degree (Orientation Degree Ratio)> Using a microwave molecular orientation meter (manufactured by Oji Keisoku Kikai Co., Ltd., model MOA-5012A), microwaves with a frequency of 12.5 to 12.6 GHz were irradiated to measure the ratio of the second orientation degree to the first orientation degree (orientation degree ratio) of the liquid crystal polymer sheet.

[0290] [Table 1] <Manufacture of the dielectric porous layer 1> The liquid crystal polymer UENO LCP A5000 manufactured by Ueno Pharmaceutical Co., Ltd. and sodium sulfate were kneaded using a kneading device Labo Plastomill 4C150 manufactured by Toyo Seiki Co., Ltd. The melting point of this liquid crystal polymer is 280 °C. This melting point was measured by differential scanning calorimetry using a differential scanning calorimeter SDT650 manufactured by TA Instruments Japan Co., Ltd. In differential scanning calorimetry, the heating rate was 10 °C / min, and the liquid crystal polymer was heated in a nitrogen atmosphere. Before kneading, sodium sulfate existed in the form of secondary particles formed by the aggregation of primary particles. The particle size of the primary particles of sodium sulfate was 1 to 10 μ m, and the particle size of the secondary particles of sodium sulfate was 10 to 50 μ m. Labo Plastomill is a registered trademark of Toyo Seiki Co., Ltd. The ratio of the volume of sodium sulfate to the sum of the volume of the kneaded liquid crystal polymer and the volume of sodium sulfate was 0.6. The temperature inside the kneading device during the kneading of the liquid crystal polymer and sodium sulfate was 350 °C. The rotational speed of the screw in the kneading device was adjusted to 30 rpm (revolutions per minute).

[0291] Using a manual hydraulic vacuum press 11FD manufactured by Imoto Seisakusho Co., Ltd., the kneaded product of the liquid crystal polymer and sodium sulfate was formed into a sheet to obtain a non-porous sheet. The thickness of the non-porous sheet was about 200 μ m to about 250 μ m. The temperature during the pressing of the kneaded product was 350 °C, and the pressing pressure was 4 to 10 MPa.

[0292] Using an experimental device MSE224S-0000-DI of Sartorius company, sodium sulfate was extracted from the non-porous sheet into ultrapure water as a solvent. The temperature of the ultrapure water was adjusted to 150 °C. The pressure around the non-porous sheet when the ultrapure water was transported to the periphery of the non-porous sheet was adjusted to 36 MPa with a manometer. The extraction time, which is the time for the non-porous sheet to be infiltrated into the ultrapure water, was 50 minutes. Then, the sheet obtained by extracting sodium sulfate in ultrapure water was dried to obtain a porous sheet (dielectric porous layer 1).

[0293] The obtained dielectric porous layer 1 had a continuous bubble structure.

[0294] The porosity calculated by the following formula is 60%.

[0295] Porosity [%] = 100 × { ( M i - M p ) / M s} { V s / ( V s + V L )} ·M i : Mass of the non-porous sheet ·M p : Mass of the porous sheet ·M s : Mass of the inorganic salt in the raw material ·V s : Volume of the inorganic salt in the raw material ·V L : Volume of the liquid crystal polymer in the raw material <Example 1> 2.0 g of the liquid crystal polyester produced in Synthesis Example 1 was added to 18.0 g of N-methyl-2-pyrrolidone and heated to 160 °C to obtain a liquid crystal polyester solution.

[0296] The obtained liquid crystal polyester solution was applied onto an 18 μ m copper foil by spin coating so that the thickness after drying was 2.0 μ m.

[0297] It was dried at 120 °C for 10 minutes. Then, it was left to cool to room temperature.

[0298] Next, it was heated from room temperature to 350 °C over 10 hours. Then, it was maintained at 350 °C for 3 hours. Then, it was cooled to room temperature.

[0299] Through the above steps, a laminated sheet 1 having a liquid crystal polymer sheet (non-porous layer) formed on a copper foil was obtained. Two pieces of this laminated sheet 1 were prepared.

[0300] The degree of orientation ratio of the non-porous layer was measured, and the result was 1.026.

[0301] The laminate was manufactured by the same method as the method Figures 7A to 7D shown.

[0302] First, the first laminated sheet 1 was placed with the copper foil facing down. A dielectric porous layer 1 (film thickness 216 μm). A second laminated sheet 1 is placed thereon in such a manner that the non-porous layer is in contact with the dielectric porous layer 1. Then, they are clamped between two press plates and hot-pressed under the conditions of 5.2 MPa, 220 °C, and 300 seconds to obtain a laminate. The layer structure of the laminate is the same as that of Figure 3 the layer structure.

[0303] <Example 2> 2.0 g of the liquid crystal polyester produced in Synthesis Example 1 was added to 18.0 g of N-methyl-2-pyrrolidone and heated to 160 °C to obtain a liquid crystal polyester solution.

[0304] The obtained liquid crystal polyester solution was applied to an 18 μ m copper foil by spin coating so that the thickness after drying was 5.0 μ m.

[0305] It was dried at 120 °C for 10 minutes. Then, it was left to cool to room temperature.

[0306] Next, it was heated from room temperature to 350 °C over 10 hours. Then, it was held at 350 °C for 3 hours. Then, it was cooled to room temperature.

[0307] Through the above steps, a laminated sheet 2 having a liquid crystal polymer sheet (non-porous layer) formed on a copper foil was obtained.

[0308] The degree of orientation ratio of the non-porous layer was measured, and the result was 1.026.

[0309] In Example 1, the laminated sheet 1 was replaced with the laminated sheet 2, and the dielectric porous layer 1 (film thickness 216 μ m) was replaced with the dielectric porous layer 1 (film thickness 255 μ m). Otherwise, the laminate was manufactured in the same manner as in Example 1.

[0310] <Comparative Example 1> In Example 1, the laminated sheet 1 was replaced with an 18 μ m copper foil, and the dielectric porous layer 1 (film thickness 216 μ m) was replaced with the dielectric porous layer 1 (film thickness 207 μ m). Otherwise, the laminate was manufactured in the same manner as in Example 1.

[0311] The various properties of the laminates manufactured in Example 1, Example 2, and Comparative Example 1 are shown in Table 2.

[0312] The relative dielectric constant of (B) + (C) + (D) was measured by removing the first conductive layer and the second conductive layer from the laminate.

[0313] The change in film thickness before and after hot pressing was determined as follows.

[0314] Film thickness change (%) = 100 × A 1 / A 0 A 0 : Total thickness of (B) to (D) before hot pressing A 1 : Total thickness of (B) to (D) before hot pressing [Table 2] The thickness, relative permittivity, and tangent of the dielectric loss angle of each layer of (B) to (D) are the thickness, relative permittivity, and tangent of the dielectric loss angle before hot pressing, respectively.

[0315] The relative permittivity (Dk) of (B) + (C) + (D) is the relative permittivity after hot pressing.

[0316] (Note 1): In Comparative Example 1, the "relative permittivity (Dk) of (B) + (C) + (D)" is the relative permittivity of the dielectric porous layer (C) after hot pressing.

[0317] In Comparative Example 1, the thickness of the dielectric porous layer becomes smaller by hot pressing, so the relative permittivity of the dielectric porous layer after hot pressing becomes larger.

[0318] <Example 3> 2.0 g of the liquid crystal polyester produced in Synthesis Example 1 was added to 18.0 g of N-methyl-2-pyrrolidone and heated to 160 °C to obtain a liquid crystal polyester solution.

[0319] The above liquid crystal polyester solution was coated on the dielectric porous layer 1 produced in <Manufacture of dielectric porous layer 1> by the bar coating method. Then, it was dried at 120 °C for 10 minutes. Then, it was left to cool to room temperature to form a first non-porous layer (2.0 μ μm) on one side. Similarly, the above liquid crystal polyester solution was coated on the opposite side by the bar coating method and dried at 120 °C for 10 minutes, thereby forming a second non-porous layer (2.0 μ μm) on the surface layer.

[0320] The laminate having the first non-porous layer, the dielectric porous layer 1, and the second non-porous layer was clamped between two copper foils, and further clamped between two press plates, and hot pressed under the conditions of 5.2 MPa, 220 °C, and 300 seconds to obtain a laminate.

[0321] A laminate with little change in film thickness before and after hot pressing was obtained in the same manner as in Examples 1 and 2.

[0322] Symbol description 1: First conductive layer 2: First non-porous layer 3: Dielectric porous layer 4: Second conductive layer 5: Second non-porous layer 20: Non-porous layer 20A: Main surface 51: First pressing plate 52: Second pressing plate 100: Laminate 1001: Porous liquid crystal polymer 1002: Composition 1010: Liquid crystal polymer 1020: Inorganic salt 1025: Pore S: Solvent.

Claims

1. A laminate, characterized in that, it has a conductive layer, a non-porous layer, and a dielectric porous layer, the dielectric porous layer contains a liquid crystal polymer, the non-porous layer is formed from a liquid composition containing a soluble liquid crystal polymer.

2. The laminate according to claim 1, wherein, the proportion of the thickness of the non-porous layer in the laminate is 0.5% to 7%.

3. The laminate according to claim 1, wherein, the relative dielectric constant of the laminate is 2.3 or less.

4. The laminate according to claim 1, wherein, the dielectric porous layer has a continuous bubble structure.

5. The laminate according to claim 1, wherein, the melting point of the liquid crystal polymer contained in the dielectric porous layer is 280 °C or higher.

6. The laminate according to claim 1, wherein, the soluble liquid crystal polymer is a polymer containing a structural unit represented by the following formula (1), a structural unit represented by the following formula (2), and a structural unit represented by the following formula (3), In formula (1), Ar 1 represents 1,4-phenylene, 2,6-naphthylene, or 4,4'-biphenylene, In formula (2), Ar 2 represents 1,4-phenylene, 1,3-phenylene, 4,4'-biphenylene, 2,6-naphthylene, or a group represented by the following formula (Q). In formula (3), Ar 3 represents 1,4-phenylene, 1,3-phenylene, 2,6-naphthylene, or a group represented by the following formula (Q), X represents -NH- or -O-, and Y represents -NH- or -O- Indicates a binding key, In formula (Q), Ar 11 and Ar 12 each independently represents phenylene or naphthylene, Q represents -O-, -C(=O)- or -S(=O) 2 -, represents a bonding site.

7. The laminate according to claim 6, wherein, the soluble liquid crystal polymer has at least any one of a polymerizable unsaturated group, a structure after reaction of the polymerizable unsaturated group, and an imide bond.

8. The laminate according to claim 1, wherein, the laminate has the non-porous layer between the conductive layer and the dielectric porous layer.

9. The laminate according to claim 8, wherein, the laminate further has a second non-porous layer on the side of the dielectric porous layer opposite to the non-porous layer side.

10. The laminate according to claim 9, wherein, the laminate further has a second conductive layer on the side of the second non-porous layer opposite to the dielectric porous layer side.

11. A method for manufacturing the laminate according to any one of claims 1 to 10, characterized in that, it includes a step of coating a liquid composition containing the soluble liquid crystal polymer on the conductive layer to form the non-porous layer.

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