Organic / inorganic cladding material

Abstract

An organic / inorganic cladding material equipped with a thermoplastic liquid crystal polymer film which has a first thermal expansion coefficient in one direction, and an inorganic layer which has a second thermal expansion coefficient in a direction parallel to the one direction, and is joined to the thermoplastic liquid crystal polymer film, wherein the first thermal expansion coefficient is lower than the second thermal expansion coefficient, and the difference between the first thermal expansion coefficient and the second thermal expansion coefficient is 10ppm / K or greater.

Description

Organic / inorganic clad materials Related Applications

[0001] This application claims priority from Japanese Patent Application No. 2022-031777, filed on March 2, 2022, the entire contents of which are incorporated herein by reference.

[0002] The present invention relates to a clad material containing an organic material and an inorganic material (hereinafter referred to as an organic-inorganic clad material).

[0003] Two or more metals with different thermal expansion coefficients laminated and bonded by rolling are called bimetals. Because bimetals undergo mechanical deformation in response to temperature changes, they can be used to control contacts in power supplies, etc., and are used in fields such as thermostats, starter tubes, and thermal relays, and their use as thermomechanical actuators is also being considered. In bimetals, copper, nickel, Ni-Mo-Fe alloys, etc. are generally used as materials with large thermal expansion coefficients, while Fe-Ni alloys are used as materials with small thermal expansion coefficients.

[0004] The thermal expansion coefficient of Fe-Ni36 alloy Invar (registered trademark), a typical low thermal expansion alloy, is 1.1 ppm / K, and to obtain a lower thermal expansion coefficient, the alloy composition must be made more complex. For example, Patent Document 1 limits the contents of manganese, silicon, calcium, magnesium, aluminum, sulfur, oxygen, nitrogen, and phosphorus in an Fe-Ni alloy containing 35.5 to 37% nickel by weight, and in an alloy that satisfies the relation: S≦0.02×Mn+0.8×Ca+0.6×Mg, the thermal expansion coefficient is 0.81×10 －６ The thermal expansion coefficient of 1 / K is measured.

[0005] Technologies for thinning bimetals are also being considered. For example, Patent Document 2 describes a technology in which a first material layer and a second material layer having different thermal expansion coefficients are formed on a substrate by electrolytic plating, and then the substrate is removed. An example of the second material layer having a low thermal expansion coefficient is a layer made of Invar (registered trademark).

[0006] JP 08-209306 A JP 2017-008377 A

[0007] In order to obtain a bimetal that is sensitive to temperature changes, it is preferable to maximize the difference in thermal expansion coefficient between the different metals. However, as mentioned above, the thermal expansion coefficient of an Fe-Ni alloy, which is generally used as a low-thermal expansion material in bimetals, is 1.1 ppm / °C, and even if the alloy composition is strictly adjusted as in Patent Document 1, it is difficult to significantly reduce the thermal expansion coefficient. In particular, in the case of alloys, in order to obtain a material with a desired thermal expansion coefficient, it is necessary to adjust the alloy composition to each numerical value, and it is difficult to obtain materials with different thermal expansion coefficients from a single raw material.

[0008] Bimetals are expected to be used as components for sensors and actuators in the field of MEMS (microelectromechanical systems), and there is a demand for thinner bimetals, but there is a limit to how thin they can be achieved by joining dissimilar metals by rolling. Patent Document 2 describes that thin bimetal elements can be manufactured by electrolytic plating, but describes a conventional Fe-Ni alloy as an alloy with low thermal expansion.

[0009] In recent years, research and development of MEMS implanted in living organisms, known as BiO-MEMS, has progressed, creating a demand for miniaturized, thin components that can be used in biological environments. However, because bimetals involve contact between two or more metals, galvanic corrosion cannot be avoided when thin-film bimetals are placed in a corrosive environment. In particular, nickel contained in low-thermal expansion alloys is a highly bioinvasive element, so there is a demand for non-invasive, low-thermal expansion materials that can replace Fe-Ni alloys.

[0010] Furthermore, due to the current social demand for the reduction of carbon dioxide emissions, there is a need to reduce energy consumption in the field of industrial engineering. However, to obtain a bimetallic low thermal expansion alloy, in addition to melting the alloy, heat treatment is required to adjust the metal structure, which consumes a lot of energy.

[0011] The present invention aims to provide an organic-inorganic clad material that reduces energy consumption by using a polymeric material instead of a bimetallic metal material with a low thermal expansion coefficient, and that can control the thermal expansion coefficient to a desired value lower than conventional values ​​and can be easily made into a thin film.

[0012] The present invention can be configured in the following aspects. [Aspect 1] An organic / inorganic clad material comprising a thermoplastic liquid crystal polymer film having a first thermal expansion coefficient in one in-plane direction, and an inorganic layer bonded to the thermoplastic liquid crystal polymer film and having a second thermal expansion coefficient in a direction parallel to the one direction, wherein the first thermal expansion coefficient is smaller than the second thermal expansion coefficient, and the difference between the first and second thermal expansion coefficients is 10 ppm / K or more. [Aspect 2] The organic / inorganic clad material according to Aspect 1, wherein the first thermal expansion coefficient is -16 ppm / K or more and 10 ppm / K or less. [Aspect 3] The organic / inorganic clad material according to Aspect 2, wherein the first thermal expansion coefficient is -16 ppm / K or more and less than -10 ppm / K. [Embodiment 4] The organic / inorganic clad material according to any one of embodiments 1 to 3, wherein the liquid crystal polymer film is a stretched film made of a thermoplastic liquid crystal polymer.

[0013] [Aspect 5] The organic / inorganic clad material according to any one of Aspects 1 to 4, wherein the second thermal expansion coefficient is 15 ppm / K or more. [Aspect 6] The organic / inorganic clad material according to any one of Aspects 1 to 4, wherein the second thermal expansion coefficient is 5 ppm / K or more and 10 ppm / K or less. [Aspect 7] The organic / inorganic clad material according to any one of Aspects 1 to 6, wherein the organic / inorganic clad material has a sheet-like shape composed of the thermoplastic liquid crystal polymer film and the inorganic layer bonded to one surface of the thermoplastic liquid crystal polymer film, and wherein the curvature of the sheet surface reversibly changes with temperature changes in the range of 25°C to 250°C. [Aspect 8] A temperature sensor comprising the organic / inorganic clad material according to any one of Aspects 1 to 7. [Aspect 9] An actuator comprising the organic / inorganic clad material according to any one of Aspects 1 to 7.

[0014] It should be noted that any combination of at least two elements disclosed in the claims and / or the specification and / or the drawings is included in the present invention, and in particular any combination of two or more of the claims set forth in the claims is included in the present invention.

[0015] According to the present invention, it is possible to provide an organic-inorganic clad material that can exhibit the same functions as bimetals of the prior art, responds sensitively to temperature changes, and can also suppress galvanic corrosion.

[0016] The present invention will be more clearly understood from the following description of preferred embodiments with reference to the accompanying drawings. However, the embodiments and drawings are merely for illustration and explanation and should not be used to define the scope of the present invention. The scope of the present invention is defined by the accompanying claims. In the accompanying drawings, the drawings are not necessarily drawn to scale and are exaggerated to illustrate the principles of the present invention. A schematic cross-sectional view illustrating the behavior of an organic-inorganic clad material according to one embodiment of the present invention with respect to temperature changes is shown.

[0017] [Organic-inorganic clad material] The organic-inorganic clad material (a clad material containing an organic material and an inorganic material) of the present invention comprises a liquid crystal polymer film having a first thermal expansion coefficient in one direction, and an inorganic layer bonded to the liquid crystal polymer film and having a second thermal expansion coefficient in a direction parallel to the one direction, wherein the first thermal expansion coefficient is smaller than the second thermal expansion coefficient, and the difference between the first thermal expansion coefficient and the second thermal expansion coefficient is 10 ppm / K or more.

[0018] In recent years, in fields such as MEMS, there has been a demand for thin bimetallic materials that are highly sensitive to temperature changes. To achieve a highly sensitive bimetal, the metallic material used must have as low a thermal expansion coefficient as possible. However, it is difficult to reduce the thermal expansion coefficient while suppressing the decrease in corrosion resistance that occurs when the material is thinned and maintaining the ductility required for thinning. Furthermore, even with conventional materials such as Fe-Ni alloys, heat treatment to control the metal structure is required to achieve a low thermal expansion coefficient, and there is a demand for the development of materials that consume less energy.

[0019] Organic-inorganic clad materials, which are composites of metal and resin by compression bonding or vapor deposition, have been known for some time. However, no resin material was known that exhibits the heat resistance, low moisture absorption, and oxidation resistance required for bimetallic materials, as well as an appropriate volumetric resistance, is easily formed into a thin film, and has a thermal expansion coefficient equal to or lower than that of conventional low-thermal-expansion alloys.

[0020] The inventors of the present invention have noticed that thermoplastic polymers (thermoplastic liquid crystal polymers) that can form an optically anisotropic molten phase have the potential to be used as an alternative to low-thermal expansion materials for bimetals, as they have relatively high heat resistance as resins, excellent oxidation resistance, and low moisture absorption. As a result of continued research and development efforts, they have noticed that it is possible to impart a low thermal expansion coefficient to thermoplastic liquid crystal polymers in the form of a thin film. Furthermore, they have discovered that even when an inorganic layer with a large thermal expansion coefficient is bonded to this thermoplastic liquid crystal polymer film, it is possible to repeat temperature change cycles while avoiding peeling of the inorganic layer at the operating temperatures of typical bimetals, and have completed the present invention.

[0021] FIG. 1 is a schematic cross-sectional view illustrating the behavior of an organic-inorganic clad material according to one embodiment of the present invention in response to temperature changes. The organic-inorganic clad material 10 comprises a thermoplastic liquid crystal polymer film 1 and an inorganic layer 2. Figure A shows the state at room temperature. When the temperature is increased, the difference in thermal expansion coefficients causes the surface of the inorganic layer 2 to bend and become convex, as shown in Figure B. This effect is particularly pronounced when the thermoplastic liquid crystal polymer film 1 has a negative thermal expansion coefficient. Furthermore, in this case, when the temperature is decreased, the thermoplastic liquid crystal polymer film 1 expands, causing the surface of the inorganic layer 2 to become concave, as shown in Figure C. Due to this behavior, the organic-inorganic clad material can be used as a replacement for conventional bimetal materials. In this invention, an organic-inorganic composite material in which an inorganic layer 2 is bonded (clad) to an organic layer made of a thermoplastic liquid crystal polymer film 1 is referred to as an organic-inorganic clad material.

[0022] Thermoplastic liquid crystal polymers have traditionally been used as circuit board materials, and commercially available materials have a thermal expansion coefficient adjusted to be approximately the same as that of copper (used as a high thermal expansion material in bimetals). However, this time, by adjusting the conditions during film production, it has been found that by imparting a thermal expansion coefficient significantly lower than that of the inorganic layer, a film can be obtained that can replace the low thermal expansion material of bimetals. Even when such a film is bonded to a high thermal expansion material such as copper or aluminum, peeling of the thermoplastic liquid crystal polymer film due to the difference in thermal expansion coefficients at temperatures used for general low thermal expansion materials is suppressed, and it can withstand repeated use as a bimetal replacement. Furthermore, by using a thermoplastic polymer film with a low thermal expansion coefficient, it is possible to obtain an organic / inorganic clad material that functions as a bimetal replacement and is non-invasive, even for titanium, which has a relatively low thermal expansion coefficient but is highly biocompatible. Furthermore, it has been found that by using a thermoplastic polymer film with a low thermal expansion coefficient, it is possible to obtain an organic / inorganic clad material that functions similarly to a bimetal for inorganic materials other than metals, such as glass and ceramics. The shape of the organic / inorganic clad material is not particularly limited, but may be, for example, a sheet-like (plate-like) material, or a sheet-like material rolled into a cylindrical shape.

[0023] The organic-inorganic clad material 10 may be a thermoplastic liquid crystal polymer film 1 with an inorganic layer 2 laminated on one side thereof. The organic-inorganic clad material 10 may be a sheet-like (plate-like) material whose curvature changes reversibly with temperature changes. For example, the curvature of the sheet surface (plate surface) may change reversibly when the temperature is changed between -10°C and room temperature (e.g., 25°C) and / or between room temperature (e.g., 25°C) and 250°C, preferably between -10°C and 250°C.

[0024] In the organic-inorganic clad material 10, the difference between the first thermal expansion coefficient and the second thermal expansion coefficient (hereinafter referred to as difference D) is 10 ppm / K or more. This difference D may be greater than 20 ppm / K or may be 25 ppm / K or more. There is no particular upper limit, but the difference D may be less than 40 ppm / K or 35 ppm / K or less.

[0025] The organic-inorganic clad material 10 of the present invention can be configured so that the inorganic layer 2 comes into contact with a conductive material such as a conductive wire, conductive tape, or conductive sheet, and the contact is released as the temperature changes, and therefore can be used as a temperature sensor in a thermostat, thermal relay, etc. Furthermore, because the organic-inorganic clad material 10 changes shape in response to a temperature change, it can also be used as a thermally driven actuator, and by forming the inorganic layer from a non-invasive (biocompatible) material such as Ti, it can also be used in fields such as Bio-MEMS.

[0026] [Inorganic Layer] In the organic-inorganic clad material, the inorganic layer may be a metal layer. The metal constituting the metal layer is not particularly limited as long as it has a thermal expansion coefficient greater than that of the thermoplastic liquid crystal polymer film. For example, copper, copper alloy, stainless steel, aluminum, etc. can be used. The inorganic material constituting the inorganic layer may be a material other than metal, such as glass or ceramic. The thermal expansion coefficient (second thermal expansion coefficient) of the inorganic layer may be 15 ppm / K or more and 25 ppm / K or less. When using a thermoplastic liquid crystal polymer film with a negative thermal expansion coefficient, the inorganic layer may be a metal layer such as titanium having a thermal expansion coefficient of approximately 5 ppm / K or more and 10 ppm / K or less. The inorganic layer may also be made of ceramic having a thermal expansion coefficient of approximately 0 ppm / K or more and 10 ppm / K or less.

[0027] In the organic-inorganic clad material, the inorganic layer may be a metal foil or an inorganic material plate directly bonded to the thermoplastic liquid crystal polymer film by a batch press, a roll-to-roll press, a double belt press, or the like, or a metal foil or an inorganic material plate may be bonded via a thin adhesive layer (not shown), or may be plated on the surface of the thermoplastic liquid crystal polymer film by a wet or dry method, but it is preferable that the inorganic layer is formed directly on the surface of the thermoplastic liquid crystal polymer film by compression or plating. The thickness of the inorganic layer is not particularly limited, but may be, for example, 3 μm to 200 μm, 5 μm to 100 μm, or 5 μm to 50 μm.

[0028] Inorganic layer thickness T ｍ and the thickness T of the thermoplastic liquid crystal polymer film ＬＣＰ The ratio of T ｍ / T ＬＣＰ It may be 0.05 or more and 10 or less, 0.25 or more and 6 or less, or 0.4 or more and 2 or less.

[0029] [Thermoplastic Liquid Crystal Polymer Film] In the organic / inorganic clad material described above, the thermoplastic liquid crystal polymer film preferably has a thermal expansion coefficient (first thermal expansion coefficient) of -16 ppm / K or more and 10 ppm / K or less in at least one direction in the plane of the film, more preferably -15 ppm / K or more and 10 ppm / K or less, even more preferably -12 ppm / K or more and less than 5 ppm / K, and even more preferably -10 ppm / K or more and less than 0 ppm / K. For example, the thermoplastic liquid crystal polymer film may have a thermal expansion coefficient of -7 ppm / K or more and -3 ppm / K or less in at least one direction in the plane of the film. Furthermore, in order to be combined with an inorganic material having a relatively low thermal expansion coefficient, the thermal expansion coefficient of the thermoplastic liquid crystal polymer film in at least one direction may be less than -10 ppm / K. For example, the thermal expansion coefficient may be −16 ppm / K or more and less than −10 ppm / K, or may be −16 ppm / K or more and −11 ppm / K or less, or may be −13 ppm / K or less.

[0030] The thermoplastic liquid crystal polymer film can be obtained, for example, by extrusion molding a melt-kneaded mixture of the thermoplastic liquid crystal polymer described below. Any extrusion molding method can be used, but the well-known T-die method, inflation method, etc. are industrially advantageous. In particular, the inflation method applies stress not only to the mechanical axis direction (hereinafter abbreviated as MD) of the thermoplastic liquid crystal polymer film, but also to the direction perpendicular thereto (hereinafter abbreviated as TD), allowing for uniform stretching in the MD and TD directions, resulting in a thermoplastic liquid crystal polymer film with controlled molecular orientation, dielectric properties, etc. in the MD and TD directions. In the organic / inorganic clad material of the present invention, the liquid crystal polymer film may have a thermal expansion coefficient within the above range in the MD or TD direction, or may have a thermal expansion coefficient within the above range in both the MD and TD directions.

[0031] For example, in extrusion molding by the inflation method, the thermal expansion coefficient of the film can be controlled by adjusting the ratio of the stretch ratio in the TD direction (Bl: blow ratio) to the stretch ratio in the MD direction (Dr: draft ratio) of a cylindrical sheet melt-extruded from a ring die: Bl / Dr. The Bl / Dr ratio may be about 0.1 to 10, but is preferably about 0.2 to 0.7, and more preferably about 0.3 to 0.6.

[0032] The thermal expansion coefficient can be determined as a value measured using a thermomechanical analyzer (TMA) between 30°C and 150°C when the temperature is increased from 25°C to 200°C at a rate of 5°C / min, then cooled to 30°C at a rate of 20°C / min, and then increased again at a rate of 5°C / min.

[0033] The thickness of the thermoplastic liquid crystal polymer film is not particularly limited, but may be 1 μm or more and 1 mm or less, 5 μm or more and 200 μm or less, or 20 μm or more and 100 μm or less.

[0034] [Thermoplastic Liquid Crystal Polymer] The thermoplastic liquid crystal polymer may be a polymer in which an isocyanate-derived bond such as an imide bond, a carbonate bond, a carbodiimide bond, or an isocyanurate bond is further introduced into an aromatic polyester or an aromatic polyester amide.

[0035] Specific examples of the thermoplastic liquid crystal polymer used in the present invention include known thermoplastic liquid crystal polyesters and thermoplastic liquid crystal polyester amides derived from the compounds classified as (1) to (4) shown below and their derivatives. However, it goes without saying that there is an appropriate range for the combination of various raw material compounds in order to form a polymer that can form an optically anisotropic molten phase.

[0036] (1) Aromatic or aliphatic dihydroxy compounds (see Table 1 for representative examples)

[0037] (2) Aromatic or aliphatic dicarboxylic acids (see Table 2 for representative examples)

[0038] (3) Aromatic hydroxycarboxylic acids (see Table 3 for representative examples)

[0039] (4) Aromatic diamines, aromatic hydroxyamines, or aromatic aminocarboxylic acids (see Table 4 for representative examples)

[0040] Representative examples of thermoplastic liquid crystal polymers obtained from these raw material compounds include copolymers having structural units shown in Tables 5 and 6.

[0041]

[0042]

[0043] Among these copolymers, polymers containing at least p-hydroxybenzoic acid and / or 6-hydroxy-2-naphthoic acid as repeating units are preferred, and particularly preferred are (i) polymers containing repeating units of p-hydroxybenzoic acid and 6-hydroxy-2-naphthoic acid, or (ii) copolymers containing repeating units of at least one aromatic hydroxycarboxylic acid selected from the group consisting of p-hydroxybenzoic acid and 6-hydroxy-2-naphthoic acid, at least one aromatic diol and / or aromatic hydroxyamine, and at least one aromatic dicarboxylic acid.

[0044] For example, in the case of polymer (i), when the thermoplastic liquid crystal polymer contains at least repeating units of p-hydroxybenzoic acid and 6-hydroxy-2-naphthoic acid, the molar ratio (A) / (B) of the p-hydroxybenzoic acid in the repeating unit (A) to the 6-hydroxy-2-naphthoic acid in the repeating unit (B) in the thermoplastic liquid crystal polymer is preferably about (A) / (B) = 10 / 90 to 90 / 10, more preferably about (A) / (B) = 15 / 85 to 85 / 15, and even more preferably about (A) / (B) = 20 / 80 to 80 / 20.

[0045] In the case of the polymer (ii), at least one aromatic hydroxycarboxylic acid (C) selected from the group consisting of p-hydroxybenzoic acid and 6-hydroxy-2-naphthoic acid, at least one aromatic diol (D) selected from the group consisting of 4,4'-dihydroxybiphenyl, hydroquinone, phenylhydroquinone, and 4,4'-dihydroxydiphenyl ether, and at least one aromatic dicarboxylic acid (E) selected from the group consisting of terephthalic acid, isophthalic acid, and 2,6-naphthalenedicarboxylic acid. The molar ratio of each repeating unit of the aromatic hydroxycarboxylic acid (C): the aromatic diol (D): the aromatic dicarboxylic acid (E) in the thermoplastic liquid crystal polymer may be about (30 to 80): (35 to 10): (35 to 10), more preferably about (C): (D): (E) = (35 to 75): (32.5 to 12.5): (32.5 to 12.5), and even more preferably about (C): (D): (E) = (40 to 70): (30 to 15): (30 to 15).

[0046] The molar ratio of repeating units derived from 6-hydroxy-2-naphthoic acid in the aromatic hydroxycarboxylic acid (C) may be, for example, 85 mol % or more, preferably 90 mol % or more, and more preferably 95 mol % or more. The molar ratio of repeating units derived from 2,6-naphthalenedicarboxylic acid in the aromatic dicarboxylic acid (E) may be, for example, 85 mol % or more, preferably 90 mol % or more, and more preferably 95 mol % or more.

[0047] Alternatively, the aromatic diol (D) may be repeating units (D1) and (D2) derived from two different aromatic diols selected from the group consisting of hydroquinone, 4,4'-dihydroxybiphenyl, phenylhydroquinone, and 4,4'-dihydroxydiphenyl ether. In this case, the molar ratio of the two aromatic diols (D1) / (D2) may be 23 / 77 to 77 / 23, more preferably 25 / 75 to 75 / 25, and even more preferably 30 / 70 to 70 / 30.

[0048] Furthermore, the molar ratio of the repeating structural units derived from the aromatic diol to the repeating structural units derived from the aromatic dicarboxylic acid, (D) / (E), is preferably 95 / 100 to 100 / 95. If the ratio is outside this range, the degree of polymerization does not increase and the mechanical strength tends to decrease.

[0049] The ability to form an optically anisotropic molten phase in the present invention can be confirmed, for example, by placing a sample on a hot stage, heating it in a nitrogen atmosphere, and observing the light transmitted through the sample.

[0050] The thermoplastic liquid crystal polymer has a melting point (hereinafter referred to as Tm ０ The Tm ０ The Tm ０ The melting point of the thermoplastic liquid crystal polymer sample is determined by measuring the temperature at which the main endothermic peak appears using a differential scanning calorimeter (Shimadzu DSC). That is, the thermoplastic liquid crystal polymer sample is heated at a rate of 10°C / min until it is completely melted, then cooled to 50°C at a rate of 10°C / min, and heated again at a rate of 10°C / min. The position of the endothermic peak that appears after this is determined as the melting point of the thermoplastic liquid crystal polymer sample.

[0051] To the thermoplastic liquid crystal polymer, thermoplastic polymers such as polyethylene terephthalate, modified polyethylene terephthalate, polyolefin, polycarbonate, polyarylate, polyamide, polyphenylene sulfide, polyether ether ketone, and fluororesin, various additives, fillers, and the like may be added within a range that does not impair the effects of the present invention.

[0052] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. [Method for measuring coefficient of thermal expansion (CTE)] The coefficient of thermal expansion of a film was measured using a thermomechanical analyzer (TMA) by applying a tensile load of 1 g to both ends of a thermoplastic polymer film 5 mm wide and 20 mm long, heating the film from room temperature to 200°C at a rate of 5°C / min, cooling it to 30°C at a rate of 20°C / min, and then heating it again to 150°C at a rate of 5°C / min, and measuring the value between 30°C and 150°C.

[0053] Example 1 A copolymer of p-hydroxybenzoic acid and 6-hydroxy-2-naphthoic acid (molar ratio: 73 / 27) was heated and kneaded in a single-screw extruder, and extruded through an annular inflation die having a die diameter of 33.5 mm and a die slit gap of 200 μm at a die shear rate of 900 s －１ A thermoplastic liquid crystal polymer (LCP) film was produced by melt-extrusion (first step) at 100°C, followed by stretching (second step) so that the ratio of the stretch ratio in the TD direction (or Bl) to the stretch ratio in the MD direction (or Dr) (Bl / Dr) was 0.2, resulting in a film thickness of 25 μm. Subsequently, the film was laminated with copper foil (manufactured by Fukuda Metal Foil & Powder Co., Ltd.: CF-H9A-DS-HD2 foil, thickness 12 μm) using a roll-to-roll method at a lamination temperature of 230°C and a linear pressure of 6 MPa.

[0054] [Examples 2 to 6] Thermoplastic liquid crystal polymer films with a thickness of 25 μm were produced by the inflation film forming method in the same manner as in Example 1. The Bl / Dr ratio was adjusted to the value shown in Table 7 below. Then, lamination was performed using a roll-to-roll method with the metal foils shown in Table 7. The stainless steel foil used was SUS304-H (0.010 mm thick) manufactured by Takeuchi Metal Foil & Powder Co., Ltd., the titanium foil used was TR270C-H (0.012 mm thick) manufactured by Takeuchi Metal Foil & Powder Co., Ltd., the brass foil used was C2680R-EH (0.030 mm thick) manufactured by Takeuchi Metal Foil & Powder Co., Ltd., and the aluminum foil used was A1N30H-O (0.012 mm thick) manufactured by Takeuchi Metal Foil & Powder Co., Ltd.

[0055] [Example 7] A thermoplastic liquid crystal polymer film having a thickness of 25 μm was produced by the inflation film forming method in the same manner as in Example 1. The Bl / Dr ratio was adjusted to the values ​​shown in Table 7 below. Then, 2 to 10 μm of copper was vapor-deposited onto the film in a copper foil vapor deposition apparatus, and the film was plated up to 12 μm.

[0056] [Example 8] A 25 μm thick thermoplastic liquid crystal polymer film was produced by the inflation film forming method in the same manner as in Example 1. The Bl / Dr ratio was adjusted to the values ​​shown in Table 7 below. Then, a glass plate (G-leaf, manufactured by Nippon Electric Glass Co., Ltd., 35 μm thick) was laminated to the thermoplastic liquid crystal polymer film using a batch press. A vacuum press was used for batch pressing, and lamination was performed at 300°C, 1.0 MPa, and 30 minutes.

[0057] [Example 9] A thermoplastic liquid crystal polymer film was produced by inflation film formation in the same manner as in Example 1, with a predetermined Bl / Dr ratio and a film thickness of 50 μm. The Bl / Dr ratio was adjusted to the values ​​shown in Table 7 below. A ceramic plate (Ceraflex-A 50 μm, manufactured by Japan Fine Ceramics Co., Ltd.) was then laminated to the thermoplastic liquid crystal polymer film using a batch press. A vacuum press was used for batch pressing, and the lamination was performed at 300°C, 1.0 MPa, and 30 minutes.

[0058] [Example 10] A thermoplastic liquid crystal polymer film was produced by inflation film formation in the same manner as in Example 1, so as to have a predetermined Bl / Dr ratio, and so as to have a film thickness of 150 μm. Then, in the same manner as in Example 1, lamination was performed with the metal foil shown in Table 7 by a roll-to-roll method.

[0059] Comparative Example 1 A liquid crystal polymer film for circuit boards, Vecstar (registered trademark) CTQ-25 (thickness: 25 μm), manufactured by Kuraray Co., Ltd., was laminated in the order of copper foil / liquid crystal polymer film / polyimide using a vacuum press, and after lamination, the polyimide was peeled off to produce a single-sided metal-clad laminate.

[0060] Comparative Example 2 A copper foil and a polyimide (PI) were laminated in this order using a vacuum press to prepare a polyimide metal-clad laminate. Kapton (registered trademark) 100H manufactured by DuPont-Toray Co., Ltd. was used as the polyimide.

[0061] Comparative Example 3 A copper foil and polytetrafluoroethylene (PTFE) were laminated in this order using a vacuum press to produce a metal-clad PTFE laminate. PTFE used was Nitoflon (registered trademark) manufactured by Nitto Denko Corporation.

[0062] [Evaluation of Clad Materials] For each Example and Comparative Example, a 1.0 cm x 5.0 cm sample was taken, clipped, and hung in a thermo-hygrostat (FX710N, manufactured by ETAC). The sample was cooled from room temperature (approximately 25°C) with 40% humidity to -10°C, and then visually observed to see whether the curvature of the sample changed and returned to normal when returned to normal. Furthermore, a sample of the same size was heated in a hot air dryer (DKN612, manufactured by Yamato Co., Ltd.) from room temperature (approximately 25°C) to 250°C, and then visually observed to see whether the curvature changed and returned to normal when returned to normal from 25°C to 250°C. A rating of A was given for cases where the curvature changed and returned to normal, a rating of B for cases where the curvature changed but did not return to normal, and a rating of C for cases where no change in curvature was observed. The change and return of curvature were confirmed by repeating the temperature change cycle three times. The conditions and evaluation results for Examples 1 to 10 and Comparative Examples 1 to 3 are shown in Table 7.

[0063]

[0064] The results of the above examples and comparative examples reveal the following points. (1) As shown in Examples 1 to 10, by adjusting the film formation conditions of the thermoplastic liquid crystal polymer, it was possible to obtain a thermoplastic liquid crystal polymer film with a large difference in thermal expansion coefficient with the inorganic layer, which is lower than that of commercially available thermoplastic liquid crystal polymer films, polyimide, polytetrafluoroethylene, etc. (2) With the organic / inorganic clad materials of Examples 1 to 10, organic / inorganic clad materials exhibiting bimetal-like behavior at temperatures below 250°C were obtained, and their resilience to shape changes due to expansion and contraction suggests high practical utility. (3) As shown in Example 3, even with titanium, which has a relatively low thermal expansion coefficient for a metal, by combining it with a thermoplastic liquid crystal polymer film exhibiting a negative thermal expansion coefficient, a difference in thermal expansion coefficient of 10 ppm / K or more was achieved, resulting in an organic / inorganic clad material exhibiting bimetal-like behavior. Both titanium and thermoplastic liquid crystal polymer are highly biocompatible materials, and therefore are expected to be applicable in fields such as Bio-MEMS. (4) As shown in Examples 8 and 9, even when a glass plate or a ceramic plate was combined with a thermoplastic liquid crystal polymer film, an organic / inorganic clad material exhibiting the same behavior as a bimetal was obtained, so it can be expected to be used in fields where insulation is required.

[0065] The present invention provides a bimetal substitute that allows for control of the difference in thermal expansion coefficient, has high corrosion resistance, and can be easily thinned. Such a material is expected to be highly useful in fields such as temperature sensors, thermal relays, actuators, and BiO-MEMS.

[0066] While the preferred embodiments of the present invention have been described above with reference to the drawings, those skilled in the art will readily recognize various changes and modifications within the scope of the present invention upon reading the specification. Accordingly, such changes and modifications are to be interpreted as falling within the scope of the invention as defined by the claims.

[0067] 1 Organic / inorganic clad material 2 Thermoplastic liquid crystal polymer 3 Inorganic layer

Claims

1. An organic-inorganic clad material comprising: a liquid crystal polymer film having a first thermal expansion coefficient in one direction; and an inorganic layer bonded to the liquid crystal polymer film and having a second thermal expansion coefficient in a direction parallel to the one direction, wherein the first thermal expansion coefficient is smaller than the second thermal expansion coefficient, and the difference between the first thermal expansion coefficient and the second thermal expansion coefficient is 10 ppm / K or more.

2. 2. The organic-inorganic clad material according to claim 1, wherein the first thermal expansion coefficient is not less than -16 ppm / K and not more than 10 ppm / K.

3. 3. The organic-inorganic clad material according to claim 2, wherein the first thermal expansion coefficient is not less than -16 ppm / K and less than -10 ppm / K.

4. 3. The organic / inorganic clad material according to claim 1, wherein the liquid crystal polymer film is a stretched film made of a thermoplastic liquid crystal polymer.

5. 3. The organic-inorganic clad material according to claim 1, wherein the second thermal expansion coefficient is 15 ppm / K or more.

6. 3. The organic-inorganic clad material according to claim 1, wherein the second thermal expansion coefficient is 5 ppm / K or more and 10 ppm / K or less.

7. 3. The organic / inorganic clad material according to claim 1 or 2, having a sheet-like shape consisting of the thermoplastic liquid crystal polymer film and the inorganic layer bonded to one surface of the thermoplastic liquid crystal polymer film, wherein the curvature of the sheet surface changes reversibly with temperature changes in the range of 25°C to 250°C.

8. A temperature sensor comprising the organic-inorganic clad material according to claim 1 or 2.

9. An actuator comprising the organic-inorganic clad material according to claim 1 or 2.