Insulating material and method for producing same

Abstract

This insulating material includes a cross-linked polyethylene oxide that has a mesogen-containing side chain in each repeating unit. The cross-linked polyethylene oxide satisfies formulae (I) and (II). The symbols a, b and c are the storage moduli of the cross-linked polyethylene oxide at 30°C, 100°C, and 260°C, respectively. The insulating material may comprise a cross-linked polyethylene oxide.

Description

Insulating materials and their manufacturing methods

[0001] One embodiment of the present invention relates to an insulating material and a method for manufacturing the same.

[0002] In various electrical and electronic circuit boards, such as those exemplified by semiconductor integrated circuits, a metal substrate is used to function as a heat sink to dissipate the heat generated in the circuit, and the circuit is formed on this substrate via an adhesive containing an insulating material. For example, in the circuit boards disclosed in Patent Documents 1 and 2, an adhesive containing epoxy resin as an insulating material is provided between the metal substrate and the circuit.

[0003] International Publication No. 2021 / 125258, International Publication No. 2020 / 179693

[0004] One embodiment of the present invention aims to provide an insulating material having a novel structure. Alternatively, one embodiment of the present invention aims to provide a highly thermally conductive insulating material having high thermal conductivity and high heat resistance.

[0005] One embodiment of the present invention is an insulating material. This insulating material comprises a crosslinked polyethylene oxide having mesogen-containing side chains in each repeating unit. The crosslinked polyethylene oxide satisfies the following formulas (I) and (II), where a, b, and c are the storage moduli of the crosslinked polyethylene oxide at 30°C, 100°C, and 260°C, respectively.

[0006]

[0007] One embodiment of the present invention is a method for producing an insulating material containing crosslinked polyethylene oxide. This production method involves ring-opening copolymerization of a trifunctional or more epoxy compound containing a mesogen and a bifunctional epoxy compound. The crosslinked polyethylene oxide satisfies the following formulas (I) and (II). a, b, and c are the storage moduli of the crosslinked polyethylene oxide at 30°C, 100°C, and 260°C, respectively.

[0008]

[0009] A schematic end view showing the method for manufacturing the insulating material of the example. A schematic end view showing the method for manufacturing the insulating material of the example. A schematic end view showing the method for manufacturing the insulating material of the example. A schematic end view showing the method for manufacturing the insulating material of the example. A schematic end view showing the method for manufacturing the insulating material of the example. Scanning electron microscope (SEM) image of the cross-section of the insulating material of the example. SEM image of the cross-section of the insulating material of the comparative example.

[0010] The following describes an insulating material (hereinafter sometimes referred to as "the insulating material") and a method for manufacturing the same according to an embodiment of the present invention. The present invention can be implemented in various forms without departing from its essence, and is not limited to the descriptions of the embodiments exemplified below.

[0011] 1. Insulating Material (1) Structure This insulating material is manufactured by ring-opening copolymerization of a trifunctional or higher epoxy compound and a difunctional epoxy compound. Specifically, the trifunctional or higher epoxy compound can be selected from trifunctional epoxy compounds and tetrafunctional epoxy compounds. Therefore, this insulating material contains crosslinked polyethylene oxide, which has polyethylene oxide formed by chain polymerization of epoxy groups as its basic backbone. Furthermore, both the trifunctional or higher epoxy compound and the difunctional epoxy compound have one or more mesogens in their molecules. For this reason, each repeating unit of polyethylene oxide has a side chain containing a mesogen. This insulating material may further contain fillers as an optional component. Here, ring-opening polymerization is a mode of polymerization different from sequential polymerization such as addition polymerization and polycondensation, and is a chain-type polymerization in which cyclic compounds open their rings and add to each other to give a linear polymer.

[0012] Mesogens are rigid skeletons, and examples of mesogens include naphthalene, biphenyl, phenoxycarbonyl, azobenzene, stilbene, and tetrahydronaphthalene skeletons. However, mesogens introduced into trifunctional or more functional epoxy compounds and bifunctional epoxy compounds are not limited to the above skeletons, and various rigid skeletons may be used as mesogens. For example, condensed aromatic ring skeletons such as anthracene, tetracene, perylene, pyrene, phenanthrene, triphenylene, and coronene skeletons may also be used. Alternatively, heteroaromatic ring skeletons in which one or more carbons forming these condensed aromatic rings are substituted with heteroatoms such as nitrogen, oxygen, or sulfur may also be used. For example, mesogens may be condensed heteroaromatic ring skeletons such as quinoline, isoquinoline, phenanthroline, acridine, naftazine, and phenazine skeletons.

[0013] The mesogens introduced into the trifunctional or higher epoxy compound and the difunctional epoxy compound may be different from or the same as each other. When the trifunctional or higher epoxy compound and the difunctional epoxy compound have the same mesogen, intramolecular π-π stacking acts more strongly between the mesogen of the trifunctional or higher epoxy compound and the mesogen of the difunctional epoxy compound in this insulating material. This allows the insulating material to be given high heat resistance and thermal conductivity.

[0014] Trifunctional epoxy compounds are generally solid at room temperature and pressure. Difunctional epoxy compounds are preferably structured to exist as liquids at room temperature and pressure. Trifunctional epoxy compounds, tetrafunctional epoxy compounds, and difunctional epoxy compounds can be described as monomers 1a, 1b, and 2, respectively, as shown below.

[0015]

[0016] Here, M １ M ２ M is the mesogen described above. In the example above, monomers 1a and 1b, which are epoxy compounds with three or more functions, are two mesogens M. １ M ２The difunctional epoxy compound contains one mesogen M. M １ , M ２ , M may be identical to each other, or at least one may be different from the other two. M １ , M ２ , when M is identical, M １ and M ２ , M １ and M, and / or M ２ Since the intermolecular force due to π-π stacking acts strongly between M, higher heat resistance and thermal conductivity can be imparted to this insulating material.

[0017] L represents a single bond or a divalent linking group. L is, for example, an alkylene group having 1 to 7 carbon atoms, for example, an alkylene group having 1 to 5 carbon atoms, an alkylene group having 1 to 3 carbon atoms, or a methylene group.

[0018] This insulating material is produced by the ring-opening polymerization of three or more epoxy groups contained in a trifunctional or higher-functional epoxy compound and two epoxy groups contained in a difunctional epoxy compound. Further, the polyethylene oxide skeleton obtained by the ring-opening polymerization of the epoxy group is cross-linked via the mesogen M １ , M ２ , M, and an oxymethylene group to form a complex three-dimensional network. Therefore, although this insulating material cannot be described by a general formula, this insulating material contains at least the following structure in part. Note that a part of the trifunctional or higher-functional epoxy compound may have at least one epoxy group that does not react in the ring-opening polymerization and may remain as an epoxy group in this insulating material. Similarly, a part of the difunctional epoxy compound may have one of the two epoxy groups that does not react in the ring-opening polymerization and may remain as an epoxy group in this insulating material.

[0019]

[0020] The trifunctional epoxy compound, the tetrafunctional epoxy compound, and the difunctional epoxy compound may be monomers 3, 4, 5 represented by the following structural formulas, respectively. Here, R １ from R ３R is a substituent introduced into the naphthalene skeleton, and each can be independently selected from hydrogen, alkyl groups, alkoxy groups, hydroxyl groups, halogens, cyano groups, amino groups, nitro groups, alkylcarbonyl groups, arylcarbonyl groups, alkyloxycarbonyl groups, and aryloxycarbonyl groups. There are no restrictions on the number of carbon atoms in the alkyl group of the alkylcarbonyl group and alkyloxycarbonyl group, for example, 1 to 6. There are also no restrictions on the number of carbon atoms in the arylcarbonyl group and aryloxycarbonyl group, for example, 5 to 12. １ From R ３ There are no restrictions on the substitution position, and sp is already used in bonding. ２ R １ From R ３ It can be implemented.

[0021]

[0022] As fillers of any composition, inorganic materials with high thermal conductivity are preferred. Examples include silicon dioxide, aluminum oxide, aluminum nitride, boron nitride, silicon carbide, and silicon nitride. The fillers are included in the insulating material as powder. There are no restrictions on the shape, particle size, or particle size distribution of the fillers. There are also no restrictions on the filler content, but for example, it should be 70% or more by volume, or 80% or more by volume, relative to the insulating material. The upper limit for filler content is 95% or less by volume. By using fillers, the thermal conductivity of the insulating material can be further improved. Furthermore, the insulating material may contain additives such as surfactants, silane coupling agents, and ion scavenging agents.

[0023] (2) Characteristics The insulating material having the structure described above exhibits high heat resistance and thermal conductivity, and shows little change in flexibility over a wide temperature range. Flexibility can be evaluated by the storage modulus, and this insulating material shows relatively little change in storage modulus over a wide temperature range. This characteristic is in contrast to insulating materials, including general epoxy resins formed from polymers, in which flexibility increases with increasing temperature, i.e., the storage modulus decreases significantly. More specifically, this insulating material satisfies the following equations (I) and (II). Here, a, b, and c are the storage moduli of this insulating material at 30°C, 100°C, and 260°C, respectively. The storage modulus can be measured by the DMA method (dynamic viscoelasticity measurement) in accordance with JIS C6481.

[0024]

[0025] As can be understood from the above equations (I) and (II), although the storage modulus of this insulating material decreases with increasing temperature, the rate of decrease decreases as the temperature rises. From this, it can be seen that this insulating material can maintain a relatively high storage modulus even at high temperatures. In other words, by maintaining high rigidity even at high temperatures, it possesses both high heat resistance and high thermal conductivity (i.e., high rigidity). Therefore, when this insulating material is used as an insulating material between a metal substrate and a circuit, it is possible to maintain high adhesion between the circuit and the metal substrate even at high temperatures. Furthermore, since both the trifunctional or higher epoxy compound and the bifunctional epoxy compound that give rise to this insulating material contain mesogens, one or more mesogens are contained in the repeating units of ethylene oxide. For this reason, this insulating material exhibits excellent thermal conductivity and high rigidity due to π-π stacking between mesogens. Therefore, by using this insulating material, it is possible to provide a circuit board with high heat resistance and high thermal conductivity.

[0026] 2. Method for Manufacturing Insulating Material As described above, this insulating material can be manufactured by ring-opening copolymerization of a trifunctional or higher epoxy compound and a bifunctional epoxy compound. An initiator (sometimes referred to as a curing catalyst) may be used to effectively promote the ring-opening copolymerization. Specifically, the insulating material can be manufactured by adding an initiator to a trifunctional or higher epoxy compound and a bifunctional epoxy compound and heating as necessary. The heating temperature may be selected from the range of 80°C or higher and 300°C or lower, or 150°C or higher and 200°C or lower, and the heating time may also be appropriately selected from 1 second or longer and 600 minutes or shorter, or 1 minute or longer and 5 minutes or shorter. At this time, a filler may be further added. The amount of the initiator may be, for example, 0.1% by weight or more and 10% by weight or less, or 1% by weight or more and 4% by weight or less based on the total mass of the trifunctional or higher epoxy compound and the bifunctional epoxy compound. Since the initiator binds to the end of polyethylene oxide in this insulating material, when no filler is used, it can be said that this insulating material consists of crosslinked polyethylene oxide obtained by ring-opening copolymerization of a trifunctional or higher epoxy compound and a bifunctional epoxy compound.

[0027] There are no restrictions on the initiators that can be used, and examples include alkoxides of alkali metals and alkaline earth metals, imidazoles, tertiary amines such as benzyldimethylamine, diazabicyclo compounds, phosphines such as triphenylphosphine, and initiators such as phosphonium salts. Among them, imidazoles are preferred because termination reactions and chain transfer are less likely to occur and epoxy compounds can be polymerized at a high degree of polymerization. Examples of imidazoles include imidazole compounds having a cyano group. Specifically, 1-(2-cyanoethyl)-2-methylimidazole, 1-(2-cyanoethyl)-2-ethyl-4-methylimidazole, 1-(2-cyanoethyl)-2-undecylimidazole, 1-(2-cyanoethyl)-2-isopropylimidazole, 1-(2-cyanoethyl)-2-phenylimidazole, 1-(2-cyanoethyl)-2-phenyl-5-(2-cyanoethoxy)methylimidazole, etc. can be mentioned.

[0028] Alternatively, a complex of boron trifluoride and an amine, a salt with an aromatic diazonium compound and BF ４ , PF ６ , SbF ６ , AsF ６ , SnCl ６ , FeCl ４ , BiCl ５ , or SbCl ６ etc., a diallyl iodonium salt, a triallyl sulfonium salt, a triallyl selenium salt, etc. may be used as an initiator. Alternatively, salts of carboxylic acids such as naphthenic acid, stearic acid, and caprylic acid with zinc, manganese, cobalt, tin, etc. may be used as an initiator.

[0029] In a typical production method, first, a polyfunctional epoxy compound having three or more functional groups, a bifunctional epoxy compound, and an initiator are mixed. When the polyfunctional epoxy compound having three or more functional groups and / or the bifunctional epoxy compound is liquid, a paste-like mixture is obtained by mixing, and this is molded into a desired shape. In order to improve the moldability of the above mixture, a solvent may be added. Examples of the solvent include aromatic hydrocarbon solvents such as toluene, xylene, and tetrahydronaphthalene, ether solvents such as tetrahydrofuran and dioxane, alcohols such as ethanol and isopropanol, amide solvents such as N-methylpyrrolidone, N,N-dimethylformamide, and N,N-dimethylacetamide, ester solvents such as ethyl acetate, butyl acetate, hexyl acetate, ethyl 3-methoxypropionate, and propylene glycol monomethyl ether acetate, and ketone solvents such as methyl ethyl ketone, methyl isobutyl ketone, cyclopentanone, and cyclohexanone. When the insulating material contains a filler, the filler may be further added to the above mixture. After removing the solvent from the obtained mixture as necessary, ring-opening polymerization of the epoxy group proceeds by heating at room temperature or the above-mentioned temperature for the above-mentioned heating time, and the insulating material can be produced.

[0030] To obtain the insulating material of the present invention in thin film form, the above mixture with the added solvent is coated to a desired thickness onto a support such as a polyethylene terephthalate (PET) film, and then the solvent is removed by distillation to obtain a precursor of the insulating material. Subsequently, the precursor is heated at the above temperature for the above heating time. During at least a portion of this heating time, a pressure of 1 MPa to 30 MPa, preferably 5 MPa to 20 MPa, may be applied.

[0031] When this insulating material is used as an insulating layer in a circuit board consisting of a metal substrate and circuits, an adhesive may be used to further improve the adhesion between this insulating material and the metal substrate or circuits. Examples of adhesives include thermosetting resin adhesives such as acrylic resin adhesives, urethane resin adhesives, and epoxy resin adhesives, with epoxy resin adhesives being preferred. When using epoxy resin adhesives, it is desirable that they contain a basic polymerization initiator. It is more preferable that the adhesive penetrates the insulating material or its precursor. Here, penetration of the adhesive refers to the phenomenon in which a portion of the adhesive diffuses into the insulating material or its precursor, while simultaneously forming a discontinuous adhesive layer between the metal substrate or circuits and the insulating material.

[0032] A method for bonding the insulating material to a metal substrate or circuit using an adhesive can be illustrated as follows: A mixture containing a trifunctional or higher epoxy compound, a bifunctional epoxy compound, a filler, and a solvent is applied to a support such as a PET film, and then the solvent is removed to obtain a precursor. After applying the adhesive to this precursor, the metal substrate is placed facing the surface to which the adhesive has been applied, and the insulating material and the metal substrate can be effectively bonded by heating at the temperature and time described above. At this time, a pressure of 1 MPa to 30 MPa or 5 MPa to 20 MPa may be applied. Subsequently, the support is peeled off, the adhesive is applied to the surface exposed by the peeling, the circuit is placed on the adhesive, and then the insulating material and the circuit can be effectively bonded by heating at the temperature and time described above. At this time, a pressure of 1 MPa to 30 MPa or 5 MPa to 20 MPa may be applied.

[0033] In the manufacturing of this insulating material, no curing agents such as polyfunctional alcohols or polyfunctional phenols (for example, curing agents having multiple phenol groups) are used. Therefore, as shown in the examples, the mesogens efficiently stack in a π-π configuration, and the presence of flexible polyethylene oxide chains around the mesogens forms a structure similar to a liquid crystal. As a result, this insulating material is thought to exhibit a relatively high storage modulus even at high temperatures. Therefore, this insulating material is thought to have high heat resistance along with high thermal conductivity.

[0034] In this example, we describe the results of fabricating an insulating material according to an embodiment of the present invention and evaluating its properties.

[0035] (1) Preparation of the sample 10 parts by mass of the following tetrafunctional epoxy compound 6 (manufactured by DIC Corporation), 5 parts by mass of the bifunctional epoxy compound 7 (manufactured by DIC Corporation), and 0.3 parts by mass of initiator 8 (manufactured by Dissolution Technology Co., Ltd.) are dissolved in 100 parts by mass of cyclohexanone, and boron nitride powder (HP-4012W, median diameter (D) manufactured by JFE Minerals Co., Ltd.) is added as a filler. ５０ ) 12 μm) 23 parts by mass and boron nitride powder (P-40MH100) manufactured by JFE Mineral Co., Ltd., median diameter (D ５０ A 18 μm particle was added. The resulting mixture was ground using a ball mill. As shown in Figure 1, this mixture 102a was coated onto a PET film 100 and heated at 120°C for 10 minutes.

[0036]

[0037] As shown in Figure 2, a 0.5 mm thick copper foil 104 was placed on the mixture 102a via an adhesive obtained by mixing 2.5 parts by mass of the bifunctional epoxy resin 9 (manufactured by DIC Corporation) and 0.1 parts by mass of the initiator 8. Then, the mixture 102a was cured into the insulating material 102 and the insulating material 102 and copper foil 104 were bonded together by hot pressing with a hot press machine at a temperature of 170°C and a pressure of 25 MPa for 3 minutes. After that, the PET film 100 was peeled off to obtain a bonded body 106 containing the copper foil 104 and the insulating material 102 (see Figure 3). Two bonded bodies 106 were prepared.

[0038]

[0039] Next, the two bonded bodies 106 were joined so that the insulating material 102 was sandwiched between the two copper foils 104. A hot press was used to maintain a temperature of 170°C for 1.5 minutes, and then hot-pressed at a pressure of 12 MPa for another 1.5 minutes (Figure 4). After that, the copper foils 104 were dissolved using an etching solution (H-20L, manufactured by Sunhayato Co., Ltd.), and the remaining insulating material 102 was washed with water and dried to obtain the sample of the example (thickness 0.24 mm) (Figure 5).

[0040] As a comparative example, a comparative sample was obtained by using the following bifunctional epoxy compound 10 instead of the above-mentioned tetrafunctional epoxy compound 6, and by performing the same procedure as in the example, except that the bifunctional epoxy compound 10 was used in the preparation of the adhesive.

[0041]

[0042] (2) The thermal conductivity, storage modulus, and heat resistance of the samples of the evaluation examples and comparative examples were evaluated. Thermal conductivity was obtained by measuring the thermal conductivity in the thickness direction using the laser flash method. Storage modulus was measured by the DMA method using a dynamic viscoelastic analyzer (manufactured by TA Instruments Japan Co., Ltd.) in accordance with JIS C6481 (tensile mode, load 100g, frequency 1Hz). The storage modulus was measured at temperatures of 30°C, 100°C, and 260°C. Heat resistance was evaluated by cross-sectional observation of the sample after heating. Specifically, the sample before peeling off the copper foil 104 was treated in a solder bath at 300°C for 5 minutes, and then the copper foil 104 was removed using the method described above. Heat resistance was evaluated by observing the cross-sectional SEM image of the obtained sample. The results are shown in Table 1.

[0043]

[0044] As can be seen from Table 1, the storage modulus at 100°C (a / b) relative to the storage modulus at 30°C (c / b) and the storage modulus at 260°C (c / b) relative to the storage modulus at 100°C (c / b) of the insulating material in the example are 0.530 and 0.574, respectively, confirming that equations (I) and (II) are satisfied. Furthermore, the a / b and c / b of the insulating material in the example are larger than those of the comparative example. This indicates that the insulating material in the example maintains a high storage modulus over a wide temperature range. In addition, the thermal conductivity of the insulating material in the example is higher than that of the comparative example, which indicates that the material has high stability even at high temperatures.

[0045] Figures 6 and 7 show SEM images obtained from the heat resistance evaluation of the example and comparative example samples, respectively. As can be seen from Figure 6, no cracks were observed in the example sample. In contrast, as shown in Figure 7, numerous cracks (see arrows in the figure) were observed in the comparative example sample. This result indicates that the insulating material of the example has high heat resistance.

[0046] The above results indicate that this insulating material can be suitably used as an insulator for metal substrates having circuits that generate a large amount of heat when driven, for example.

[0047] As embodiments of the present invention, any additions, deletions, or design modifications of components, or additions, omissions, or changes in conditions of processes, based on the embodiments described above, made by those skilled in the art, are also included within the scope of the present invention, as long as they retain the essence of the present invention. Any other effects or benefits, different from those brought about by the embodiments described above, that are clear from the description herein or easily predictable to those skilled in the art, are naturally considered to be brought about by the present invention.

[0048] 100: Film, 102: Main insulating material, 102a: Mixture, 104: Copper foil, 106: Bonding body

Claims

1. Containing crosslinked polyethylene oxide having a mesogen-containing side chain in each repeating unit, wherein the crosslinked polyethylene oxide satisfies the following formulas (I) and (II). An insulating material, where a, b, and c are the storage elastic moduli of the crosslinked polyethylene oxide at 30 °C, 100 °C, and 260 °C, respectively.

2. The insulating material according to claim 1, comprising the crosslinked polyethylene oxide.

3. The insulating material according to claim 1, wherein the mesogen comprises a skeleton selected from a naphthalene skeleton, a biphenyl skeleton, a phenoxycarbonyl skeleton, an azobenzene skeleton, a stilbene skeleton, and a tetrahydronaphthalene skeleton.

4. The insulating material according to claim 3, wherein the skeleton has substituents selected from alkyl groups, alkoxy groups, hydroxyl groups, halogens, cyano groups, amino groups, nitro groups, alkylcarbonyl groups, arylcarbonyl groups, alkyloxycarbonyl groups, and aryloxycarbonyl groups.

5. The crosslinked polyethylene oxide is produced by ring-opening copolymerization of monomer 1a and monomer 2, or monomer 1b and monomer 2, represented by the following general formula. M １ M ２ The insulating material according to claim 1, wherein M is the mesogen, and L is a linking group selected from an alkylene group, an oxyalkylene group, a carbonyl group, and an ester group.

6. The insulating material according to claim 5, wherein the blending mass ratio of monomer 1a or monomer 1b to monomer 2 is 0.25 or more and 3 or less.

7. The monomer 1b and the monomer 2 are monomer 3 and monomer 4, respectively, represented by the following general formulas: R １ From R ３ The insulating material according to claim 5, wherein each is independently selected from hydrogen, alkyl group, alkoxy group, hydroxy group, halogen, cyano group, amino group, nitro group, alkylcarbonyl group, arylcarbonyl group, alkyloxycarbonyl group, and aryloxycarbonyl group.

8. The insulating material according to claim 1, further comprising a filler.

9. A method for producing an insulating material containing crosslinked polyethylene oxide, comprising ring-opening copolymerization of a trifunctional epoxy compound or tetrafunctional epoxy compound containing a mesogen, and a difunctional epoxy compound, wherein the crosslinked polyethylene oxide satisfies the following formulas (I) and (II): A method for producing the crosslinked polyethylene oxide, wherein a, b, and c are the storage moduli of the crosslinked polyethylene oxide at 30°C, 100°C, and 260°C, respectively.

10. The manufacturing method according to claim 9, wherein the mesogen comprises a skeleton selected from a naphthalene skeleton, a biphenyl skeleton, a phenoxycarbonyl skeleton, an azobenzene skeleton, a stilbene skeleton, and a tetrahydronaphthalene skeleton.

11. The manufacturing method according to claim 10, wherein the skeleton has substituents selected from alkyl groups, alkoxy groups, hydroxyl groups, halogens, cyano groups, amino groups, nitro groups, alkylcarbonyl groups, arylcarbonyl groups, alkyloxycarbonyl groups, and aryloxycarbonyl groups.

12. The trifunctional epoxy compound, the tetrafunctional epoxy compound, and the bifunctional epoxy compound are monomers 1a, 1b, and 2, respectively, represented by the following general formulas: M １ M ２ The manufacturing method according to claim 9, wherein M is the mesogen, and L is a linking group selected from an alkylene group, an oxyalkylene group, a carbonyl group, and an ester group.

13. The manufacturing method according to claim 12, wherein the ring-opening copolymerization is carried out under conditions in which the mass ratio of monomer 1a or monomer 1b to monomer 2 is 0.25 or more and 3 or less.

14. The monomer 1b and the monomer 2 are monomer 3 and monomer 4, respectively, represented by the following general formulas: R １ From R ３ The manufacturing method according to claim 12, wherein each is independently selected from hydrogen, alkyl group, alkoxy group, hydroxy group, halogen, cyano group, amino group, nitro group, alkylcarbonyl group, arylcarbonyl group, alkyloxycarbonyl group, and aryloxycarbonyl group.

15. The manufacturing method according to claim 9, wherein the ring-opening copolymerization is carried out in the presence of a filler.

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