Composition, thermoplastic liquid crystal polymer film and methods for producing same

Abstract

A composition containing a polymer capable of forming an optically anisotropic melt phase, wherein, when the melt shear viscosity of the composition is measured using a parallel plate-equipped rotary rheometer at a temperature that is the melting point of the composition +15°C while increasing the frequency from 0.01 rad / s, in the frequency range from 0.01 rad / s-100 rad / s the composition exhibits a melt viscosity characteristic region in which the differential value dη / df for the change in the melt shear viscosity η with respect to the increase in the measurement frequency f is equal to or greater than 0.

Description

Compositions, thermoplastic liquid crystal polymer films, and methods for producing the same. Related applications

[0001] This application claims priority to Japanese Patent Application No. 2024-179985, filed on 15 October 2024, which is incorporated herein by reference as forming part of this application.

[0002] This invention relates to compositions, thermoplastic liquid crystal polymer films, and methods for producing the same.

[0003] Thermoplastic liquid crystal polymers possess high strength and high heat resistance, and have been widely used as engineering plastics in recent years. In the main applications of thermoplastic liquid crystal polymers, products are manufactured by injection molding, and generally, those with low melt viscosity are preferred. For example, Patent Document 1 discloses a liquid crystal polyester composition containing a liquid crystal polyester and a fatty acid metal salt that has the effect of shortening the plasticization time during injection molding, and the same document discloses adjusting the molecular weight by solid-phase polymerization in order to adjust the flow initiation temperature of the liquid crystal polyester.

[0004] On the other hand, relatively high viscosity is required for melt-forming thermoplastic liquid crystal polymers. For example, in inflation film formation, the molten resin is stretched and molded into a cylindrical shape, so a certain viscosity is necessary in the molten state. It is also known that in melt film formation, the viscosity of the thermoplastic liquid crystal polymer at a specific shear rate has a significant impact on moldability due to the structure of the extruder. For example, Patent Document 2 describes that because the melt viscosity of liquid crystal polymers is highly dependent on the shear rate, when liquid crystal polymers are melt-extruded from a die during inflation film formation, if the clearance of the die land, which receives the strongest shear force, fluctuates in the circumferential direction, the melt viscosity increases or decreases significantly in the circumferential direction, resulting in fluctuations in the thickness and mechanical properties of the molded film.

[0005] International Publication No. 2022 / 153945 JP 11-309776 Publication

[0006] However, in conventional melt deposition of thermoplastic liquid crystal polymers, even if methods such as controlling the melt viscosity by solid-phase polymerization are used, it is difficult to obtain films with minimal variation in thickness and mechanical properties in the TD direction (circumferential direction during inflation deposition). Therefore, further improvements in film thickness uniformity, stability during deposition, and reduction of defects are required.

[0007] For example, while many methods have been investigated to increase the viscosity of liquid crystal polymers by raising their molecular weight in powder or solid form through conventional melt polymerization or solid-phase polymerization, excessively high viscosity can lead to molding defects such as uneven film thickness and other flaws during film formation. Furthermore, if there are inconsistencies in the adjustment by solid-phase polymerization, unmelted resin with a high melting point can result in surface defects on the film, significantly degrading its appearance, thus presenting many challenges in film formation.

[0008] Another approach is to lower the film formation temperature and form the film in a temperature range where viscosity is high. However, at lower temperatures, the frost line before inflation is difficult to stabilize, and the melt tension is also unstable. This presents problems such as uneven film thickness and other drawbacks, similar to high-viscosity resins.

[0009] The present invention aims to provide a composition that exhibits excellent film formation stability, improves film thickness uniformity in the resulting film, and reduces defects, as well as a thermoplastic liquid crystal polymer film formed using the same.

[0010] The inventors of the present invention, through diligent research to achieve the above objectives, discovered that by using a composition that exhibits melt viscosity behavior in the low shear rate region of melt viscosity, where viscosity does not increase with decreasing shear rate, or where viscosity decreases with decreasing shear rate, the stretchability during blow molding, particularly in inflation film formation, is improved, and film thickness uniformity is reduced. Furthermore, by adjusting the composition of solid-phase polymerization and thermoplastic liquid crystal polymers, the domain formation of the resulting composition during melting is optimized, and by achieving a specific viscosity behavior, the viscosity during stretching is stabilized and film thickness uniformity is improved, leading to the completion of the present invention.

[0011] In other words, the present invention may be configured in the following embodiments. [Embodiment 1] A composition comprising a polymer capable of forming an optically anisotropic molten phase (hereinafter referred to as a thermoplastic liquid crystal polymer), wherein when the molten shear viscosity of the composition is measured at a temperature of the melting point + 15°C using a rotating rheometer equipped with a parallel plate while increasing the frequency from 0.01 rad / s, the composition exhibits a molten viscosity characteristic region in which the differential value dη / df of the change in molten shear viscosity η with respect to an increase in the measurement frequency f is 0 or greater in the frequency range from 0.01 rad / s to 100 rad / s. [Embodiment 2] The composition according to Embodiment 1, wherein when the molten shear viscosity of the composition is measured at a temperature of the melting point + 15°C using a rotating rheometer equipped with a parallel plate while increasing the frequency from 0.01 rad / s, the composition exhibits a molten viscosity characteristic in which the molten shear viscosity rises to a peak value as the measurement frequency increases from 0.01 rad / s, and then declines thereafter.

[0012] [Aspect 3] The composition according to aspect 1 or 2, wherein the melt shear viscosity of the composition, measured using a rotational rheometer equipped with a parallel plate at a temperature of the melting point of the composition + 15°C, satisfies the following conditions: at a frequency of 0.01 rad / s, it is 7,000 Pa·s or more and 60,000 Pa·s or less (preferably 8,000 Pa·s or more and 40,000 Pa·s or less), and at a frequency of 100 rad / s, it is 100 Pa·s or more (preferably 200 Pa·s or more and 500 Pa·s or less). [Aspect 4] The composition according to any one of aspects 1 to 3, wherein the melt shear viscosity of the composition, measured using a rotational rheometer equipped with a parallel plate at a temperature of the melting point of the composition + 15°C, is 6000 Pa·s or more (preferably 9000 Pa·s or more and 60000 Pa·s or less) at a frequency of 0.1 rad / s, and 600 Pa·s or less (preferably 200 Pa·s or more and 500 Pa·s or less) at a frequency of 100 rad / s.

[0013] [Aspect 5] The composition according to any one aspect of aspects 1 to 4, wherein the melting point of the composition is 315°C or higher. [Aspect 6] The composition according to any one aspect of aspects 1 to 5, wherein the inorganic content is 1% by mass or less. [Aspect 7] The composition according to any one aspect of aspects 1 to 6, comprising a thermoplastic liquid crystal polymer (I) having a melt viscosity of 40 Pa·s or less and a thermoplastic liquid crystal polymer (II) having a melt viscosity greater than 40 Pa·s. [Aspect 8] The composition according to aspect 7, wherein the mass ratio of the thermoplastic liquid crystal polymer (I) to the thermoplastic liquid crystal polymer (II) is (I) / (II) = 10 / 90 to 90 / 10. [Aspect 9] A thermoplastic liquid crystal polymer film comprising the composition according to any one aspect of aspects 1 to 8. [Aspect 10] A metal-clad laminate comprising the thermoplastic liquid crystal polymer film according to aspect 9 and a metal layer laminated on at least one surface of the thermoplastic liquid crystal polymer film.

[0014] [Aspect 11] A method for producing a composition according to any one of aspects 1 to 8, comprising the steps of: preparing at least two thermoplastic liquid crystal polymers with different melt viscosities; and melt-kneading the at least two thermoplastic liquid crystal polymers with different melt viscosities. [Aspect 12] A method for producing a composition according to aspect 11, wherein the at least two thermoplastic liquid crystal polymers with different melt viscosities have the same composition and the polymerization process is different. [Aspect 13] A method for producing a thermoplastic liquid crystal polymer film according to aspect 9, wherein the composition according to any one of aspects 1 to 8 is extruded.

[0015] Furthermore, any combination of at least two components disclosed in the claims and / or specification is included in the present invention. In particular, any combination of two or more claims described in the claims is included in the present invention.

[0016] The composition of the present invention exhibits excellent film formation stability, improves film thickness uniformity in the resulting film, and reduces defects.

[0017] This graph shows the behavior of the change in melt viscosity in response to a change in the measurement frequency of a rotational rheometer for compositions according to the examples and comparative examples of the present invention.

[0018] One embodiment of the present invention is a composition comprising a polymer capable of forming an optically anisotropic molten phase (hereinafter referred to as a thermoplastic liquid crystal polymer), wherein when the molten shear viscosity of the composition is measured at a temperature of the melting point + 15°C using a rotational rheometer equipped with a parallel plate while increasing the frequency from 0.01 rad / s, the composition exhibits a molten viscosity characteristic region in which the differential value dη / df of the change in molten shear viscosity η with respect to an increase in the measurement frequency f is 0 or greater in the frequency range from 0.01 rad / s to 100 rad / s.

[0019] Another embodiment of the present invention is a composition comprising a thermoplastic liquid crystal polymer, wherein the melt shear viscosity of the composition, measured using a rotational rheometer equipped with a parallel plate at a temperature of the melting point of the composition + 15°C, is preferably 7,000 Pa·s or more and 60,000 Pa·s or less at a frequency of 0.01 rad / s, and 100 Pa·s or more at a frequency of 100 rad / s. The composition of the present invention may also combine the features of the two embodiments described above.

[0020] (Thermoplastic Liquid Crystal Polymer) The thermoplastic liquid crystal polymer included in the composition of the present invention is composed of a polymer capable of forming an optically anisotropic molten phase, and its chemical composition is not particularly limited as long as it does not impair the spirit of the present invention, but examples include thermoplastic liquid crystal polyester, or thermoplastic liquid crystal polyesteramide in which an amide bond is introduced thereto.

[0021] Furthermore, the ability to form an optically anisotropic molten phase as referred to in this invention can be determined, for example, by placing the sample on a hot stage, heating it in a nitrogen atmosphere, and observing the transmitted light of the sample.

[0022] Furthermore, the thermoplastic liquid crystal polymer may be a polymer in which an aromatic polyester or aromatic polyesteramide is further modified by introducing isocyanate-derived bonds such as imide bonds, carbonate bonds, carbodiimide bonds, or isocyanurate bonds.

[0023] Specific examples of the thermoplastic liquid crystal polymers used in the present invention include known thermoplastic liquid crystal polyesters and thermoplastic liquid crystal polyester amides derived from the compounds classified into (1) to (4) exemplified below and their derivatives. However, it is needless to say that there is an appropriate range for combinations of various raw material compounds in order to form a polymer capable of forming an optically anisotropic molten phase.

[0024] (1) Aromatic or aliphatic diols (see Table 1 for representative examples)

[0025] (2) Aromatic or aliphatic dicarboxylic acids (see Table 2 for representative examples)

[0026] (3) Aromatic hydroxycarboxylic acids (see Table 3 for representative examples)

[0027] (4) Aromatic diamines, aromatic hydroxyamines or aromatic aminocarboxylic acids (see Table 4 for representative examples)

[0028] Representative examples of the thermoplastic liquid crystal polymers obtained from these raw material compounds include copolymers having the repeating units shown in Tables 5 and 6.

[0029]

[0030] Among these copolymers, copolymers containing p-hydroxybenzoic acid and / or 6-hydroxy-2-naphthoic acid as at least repeating units are preferred. In particular, (i) a copolymer containing repeating units of p-hydroxybenzoic acid and 6-hydroxy-2-naphthoic acid, or (ii) 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 are preferred.

[0031] For example, in copolymer (i), if the thermoplastic liquid crystal polymer contains repeating units of at least p-hydroxybenzoic acid and 6-hydroxy-2-naphthoic acid, the molar ratio (A) / (B) of p-hydroxybenzoic acid of repeating unit (A) to 6-hydroxy-2-naphthoic acid of repeating unit (B) is preferably about 10 / 90 to 90 / 10 in the thermoplastic liquid crystal polymer, more preferably about 15 / 85 to 85 / 15, and even more preferably about 20 / 80 to 80 / 20. Furthermore, (A) / (B) = 75 / 25 to 99 / 1 is preferable, more preferably (A) / (B) = 76 / 24 to 95 / 5, even more preferably (A) / (B) = 77 / 23 to 90 / 10, and even more preferably (A) / (B) = 77 / 23 to 85 / 15, with (A) / (B) = 80 / 20 being particularly preferable. By using a thermoplastic liquid crystal polymer containing 25 mol% or less of 6-hydroxy-2-naphthoic acid, the melt viscosity characteristics are improved, the film thickness unevenness of the film obtained by film formation is improved, and defects tend to be reduced.

[0032] In the case of copolymer (i), in addition to the repeating units of p-hydroxybenzoic acid and 6-hydroxy-2-naphthoic acid, repeating units composed of aromatic diols or aromatic dicarboxylic acids (e.g., terephthalic acid) may be included, from the viewpoint of adjusting the molecular weight, etc.

[0033] Also, in the case of the copolymer of (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 in the thermoplastic liquid crystal polymer may be about (30 to 80):(35 to 10):(35 to 10) for the aromatic hydroxycarboxylic acid (C):the aromatic diol (D):the aromatic dicarboxylic acid (E), more preferably about (35 to 75):(32.5 to 12.5):(32.5 to 12.5), and even more preferably about (40 to 70):(30 to 15):(30 to 15).

[0034] Also, the molar ratio of the repeating unit derived from 6-hydroxy-2-naphthoic acid among the aromatic hydroxycarboxylic acids (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 the repeating unit derived from 2,6-naphthalenedicarboxylic acid among the aromatic dicarboxylic acids (E) may be, for example, 85 mol% or more, preferably 90 mol% or more, and more preferably 95 mol% or more.

[0035] Also, 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 that case, the molar ratio of the two aromatic diols may be (D1) / (D2) = 23 / 77 to 77 / 23, more preferably 25 / 75 to 75 / 25, and even more preferably 30 / 70 to 70 / 30.

[0036] Furthermore, the molar ratio of repeating structural units derived from aromatic diols to repeating structural units derived from aromatic dicarboxylic acids is preferably (D) / (E) = 95 / 100 to 100 / 95. If the ratio deviates from this range, the degree of polymerization does not increase and the mechanical strength tends to decrease.

[0037] Melting point (Tm) of thermoplastic liquid crystal polymers ０ The melting point of the thermoplastic liquid crystal polymer is preferably in the range of 250 to 380°C, more preferably in the range of 280 to 360°C, and even more preferably in the range of 300 to 350°C. The melting point of the thermoplastic liquid crystal polymer can be obtained by observing the thermal behavior of the thermoplastic liquid crystal polymer sample using a differential scanning calorimeter.

[0038] The melt viscosity of the thermoplastic liquid crystal polymer is not particularly limited, but at a temperature of the melting point of the thermoplastic liquid crystal polymer + 15°C, the melt viscosity is preferably 25 to 100 Pa·s, more preferably 35 to 80 Pa·s, and even more preferably 40 to 60 Pa·s.

[0039] The melt viscosity of the thermoplastic liquid crystal polymer in this invention can be measured using a capillograph. In this invention, the melt viscosity is measured using a Gottfert Rheograph 20 capillograph (with an umlaut over the 'o'), with a capillary size of 1 mm in diameter and 10 mm in length, a measurement temperature of the melting point of the thermoplastic liquid crystal polymer + 15°C, and a shear rate of 1000 s. －１ It is measured under these conditions.

[0040] (Method for producing thermoplastic liquid crystal polymers) Thermoplastic liquid crystal polymers can be synthesized by known polycondensation methods. Various aromatic diols, aromatic dicarboxylic acids, aromatic hydroxycarboxylic acids, aromatic hydroxyamines, etc., may be used as monomers for polycondensation, or carboxylic acid derivatives such as acylated hydroxyl groups with activated monomer ends, esterified carboxyl groups, acid halides, and acid anhydrides may be used.

[0041] The monomer derivatives may be synthesized by derivatizing (e.g., acylation) the monomer beforehand, or they can be generated in the reaction system by adding a derivatizing agent (e.g., an acyling agent) to the monomer during the production of the thermoplastic liquid crystal polymer. Examples of acyling agents include acid anhydrides such as acetic anhydride.

[0042] Polycondensation may be carried out in the presence of various catalysts, for example, organotin catalysts (dialkyltin oxides, etc.), antimony catalysts (antimony trioxide, etc.), titanium catalysts (titanium dioxide, etc.), alkali metal salts or alkaline earth metal salts of carboxylic acids (potassium acetate, etc.), Lewis salts (BF ３ Examples include organic compound catalysts (such as N,N-dimethylaminopyridine and 1-methylimidazole).

[0043] Polycondensation may be performed by melt polymerization, followed by solid-phase polymerization. Solid-phase polymerization is carried out by methods such as extracting the polymer obtained in the melt polymerization step, crushing it into a powder or flake, and then heat-treating it in a solid state under vacuum or an inert atmosphere such as nitrogen.

[0044] (Composition) The composition of the present invention comprises the thermoplastic liquid crystal polymer described above. When the melt shear viscosity of the composition is measured at a temperature of the melting point of the composition + 15°C using a rotational rheometer equipped with a parallel plate, while increasing the frequency from 0.01 rad / s, the composition exhibits a melt viscosity characteristic region in which the differential value dη / df of the change in melt shear viscosity η with respect to an increase in the measurement frequency f is 0 or greater, in the frequency range from 0.01 rad / s to 100 rad / s.

[0045] Furthermore, it is preferable that when the melt shear viscosity of the composition of the present invention is measured at a temperature of the melting point of the composition + 15°C using a rotational rheometer equipped with a parallel plate, while increasing the frequency from 0.01 rad / s, the melt shear viscosity rises to a peak value as the measurement frequency increases from 0.01 rad / s, and then declines thereafter.

[0046] Furthermore, it is preferable that the composition of the present invention has a melt shear viscosity at a frequency of 0.1 rad / s that is greater than the melt shear viscosity at a frequency of 0.01 rad / s.

[0047] Furthermore, in another embodiment of the present invention, the molten shear viscosity of the composition, measured using a rotational rheometer equipped with a parallel plate at a temperature of the melting point of the composition + 15°C, is preferably as follows: At a frequency of 0.01 rad / s, the molten shear viscosity is preferably 7,000 Pa·s or more and 60,000 Pa·s or less, and more preferably 8,000 Pa·s or more and 40,000 Pa·s or less. At a frequency of 0.1 rad / s, the molten shear viscosity is preferably 6,000 Pa·s or more, and more preferably 9,000 Pa·s or more and 60,000 Pa·s or less. At a frequency of 100 rad / s, the molten shear viscosity is preferably 100 Pa·s or more, even more preferably 600 Pa·s or less, and more preferably 200 Pa·s or more and 500 Pa·s or less.

[0048] The melt shear viscosity of the composition in the present invention is measured using a rotational viscoelasticity measuring rheometer (ARES-G2) manufactured by TA Instruments, in Dynamic Frequency Sweep Test mode, using a parallel plate with a diameter of φ25 mm, a gap of 1.00 mm, an initial strain of 10%, a frequency of 0.01 to 500 rad / s, in an air atmosphere, at a temperature of the melting point of the composition + 15°C, and a Transducer detection torque of 0.02 to 200 g·cm. The frequency is measured from the low frequency side. As a sample, it can be measured using pellets made from the composition of the present invention. Alternatively, it is also possible to measure a 1.00 mm thick sample by laminating multiple layers of thermoplastic liquid crystal polymer film made using the composition of the present invention (for example, laminating 20 layers of thermoplastic liquid crystal polymer film with a thickness of 50 μm). In the method for measuring the melt shear viscosity of a composition according to the present invention, the sample is measured in a completely molten state, so either pellets or films may be used as the sample.

[0049] In inflation film formation, the viscosity of liquid crystal polymers generally decreases as the shear rate increases drastically. Inflation film formation consists of three main processes: melt extrusion, longitudinal stretching, and transverse stretching. The shear rate and temperature decrease with each process. In this case, the transverse stretching process has the lowest shear rate and temperature, but if the viscosity increases, stretching becomes difficult, leading to problems such as uneven film thickness. By forming an inflation film with the composition of the present invention, stable stretching becomes possible without a rapid increase in viscosity even when the processing temperature decreases during the stretching process in the width direction.

[0050] In particular, in melt deposition for orientation control, extremely high viscosity makes orientation control difficult due to stretching, making it difficult to achieve the desired orientation.

[0051] Furthermore, the composition of the present invention preferably contains at least two types of thermoplastic liquid crystal polymers, and it is even more preferable that the melt viscosities of each thermoplastic liquid crystal polymer are different. The at least two types of thermoplastic liquid crystal polymers may have the same composition or different compositions. In this specification, the composition of a thermoplastic liquid crystal polymer means the combination of repeating units and their content.

[0052] Furthermore, it is preferable that at least two of the thermoplastic liquid crystal polymers have different polymerization processes. In this specification, different polymerization processes mean, for example, differences in the presence or absence of processes such as solid-phase polymerization and melt polymerization.

[0053] In particular, the composition of the present invention preferably contains at least two types of thermoplastic liquid crystal polymers having the same composition but different polymerization processes and melt viscosities. For example, by preparing two thermoplastic liquid crystal polymers with the same combination and content of repeating units and performing solid-phase polymerization on one of them, the molecular weight increases, and two types of thermoplastic liquid crystal polymers with different melt viscosities can be obtained.

[0054] In such a combination of thermoplastic liquid crystal polymers, it is preferable that molecules with large molecular weights and molecules with small molecular weights are present. As a result, in the high shear rate region, it exhibits the conventional liquid crystal polymer properties where viscosity decreases with increasing shear rate, resulting in excellent melt-kneadability. However, from the high shear rate region to the low shear rate region, it has a peak where viscosity increases with decreasing shear rate, and in the region with even lower shear rates than the shear rate region where the peak viscosity is observed, the viscosity decreases, resulting in a tendency for excellent film stretchability in the film stretching process performed at low shear rates.

[0055] For example, when the composition of the present invention contains two types of thermoplastic liquid crystal polymers, the mass ratio of the thermoplastic liquid crystal polymer (I) with lower melt viscosity to the thermoplastic liquid crystal polymer (II) with higher melt viscosity is preferably (I) / (II) = 10 / 90 to 90 / 10, more preferably 20 / 80 to 90 / 10, even more preferably 40 / 60 to 90 / 10, and particularly preferably 50 / 50 to 90 / 10. By mixing within the above range, the composition has the characteristic of having a peak viscosity from the high shear rate region to the low shear rate region, and the viscosity decreases in the region where the shear rate is even lower than the shear rate at which the peak value is observed, resulting in a composition with excellent film-forming properties.

[0056] The melt viscosity of the thermoplastic liquid crystal polymer (I) with the lower melt viscosity is preferably 40 Pa·s or less, for example 25 Pa·s or more and 40 Pa·s or less, at a temperature of melting point + 15°C, based on the melting point of thermoplastic liquid crystal polymer (I). The melt viscosity of the thermoplastic liquid crystal polymer (II) with the higher melt viscosity is preferably greater than 40 Pa·s, for example greater than 40 Pa·s and 100 Pa·s or less, at a temperature of melting point + 15°C, based on the melting point of thermoplastic liquid crystal polymer (II).

[0057] The melt viscosity of the composition of the present invention is not particularly limited, but at a temperature of melting point + 15°C, the melt viscosity is preferably 25 to 100 Pa·s, more preferably 35 to 80 Pa·s, and even more preferably 40 to 60 Pa·s.

[0058] The melt viscosity of the composition in this invention can be measured using a capillograph. In this invention, the melt viscosity is measured using a Gottfert Rheograph 20, with a capillary size of 1 mm in diameter and 10 mm in length, a measurement temperature of the melting point of the composition + 15°C, and a shear rate of 1000 s. －１ It is measured under these conditions.

[0059] Since the melt viscosity measured by a capillograph can be used as a guideline viscosity during processing, it can also be measured at a constant temperature above the melting point and used as an indicator of the processability of the synthesized thermoplastic liquid crystal polymer.

[0060] In this invention, the melting point of the composition is defined as the melting point of a film prepared from the composition as described later, measured using a differential scanning calorimeter (DSC, Shimadzu Corporation). As described in the examples below, the film is heated at a rate of 10°C / min until it is completely melted at 400°C, then the molten material is cooled to 50°C at a rate of 10°C / min, and the position of the endothermic peak that appears when the temperature is raised again at a rate of 10°C / min is defined as the melting point of the composition. If multiple endothermic peaks originating from the thermoplastic liquid crystal polymer are observed, the position of the endothermic peak that appears at the highest temperature is defined as the melting point of the composition.

[0061] While there are no particular limitations on the melting point, when used in communication equipment, the melting point of the composition is preferably 270°C or higher, more preferably 280°C or higher, more preferably 300°C or higher, more preferably 310°C or higher, more preferably 315°C or higher, more preferably 320°C or higher, and more preferably 325°C or higher.

[0062] The composition may consist solely of a thermoplastic liquid crystal polymer, but in addition 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, as well as various additives and fillers, may be added to the composition, provided that the effects of the present invention are not impaired. Adding inorganic substances as fillers is also permitted, but the amount added is preferably 1% by mass or less. The content of the thermoplastic liquid crystal polymer in the composition may be 90% by mass or more, preferably 95% by mass or more, and more preferably 98% by mass or more.

[0063] (Method for producing the composition) The method for producing the composition of the present invention preferably includes the steps of preparing at least two thermoplastic liquid crystal polymers with different melt viscosities and melt-kneading the at least two thermoplastic liquid crystal polymers with different melt viscosities. The at least two thermoplastic liquid crystal polymers with different melt viscosities preferably include the thermoplastic liquid crystal polymers (I) and (II) described above.

[0064] Furthermore, it is preferable that at least two thermoplastic liquid crystal polymers with different melt viscosities have the same composition and undergo different polymerization processes. In this specification, different polymerization processes refer to differences such as the presence or absence of processes like solid-phase polymerization and melt polymerization. By using different polymerization processes, it is possible to have molecules with large molecular weights and molecules with small molecular weights in the composition.

[0065] Known methods can be used for melt-kneading thermoplastic liquid crystal polymers. For example, continuous kneading extruders such as twin-screw kneading extruders or single-screw kneading extruders can be used.

[0066] (Thermoplastic Liquid Crystal Polymer Film) The thermoplastic liquid crystal polymer film of the present invention consists of the above-described composition.

[0067] The melting point (Tm) of the thermoplastic liquid crystal polymer film may be, for example, 315°C or higher, preferably 315 to 380°C, more preferably 318 to 370°C, and even more preferably 320 to 360°C. The melting point (Tm) of the thermoplastic liquid crystal polymer film can be obtained by observing the thermal behavior of the thermoplastic liquid crystal polymer sample using a differential scanning calorimeter. Specifically, the thermoplastic liquid crystal polymer sample can be heated from room temperature (e.g., 25°C) at a rate of 10°C / min until it is completely melted at 400°C, then the molten material is cooled to 50°C at a rate of 10°C / min, and the position of the endothermic peak that appears when the temperature is raised again at a rate of 10°C / min can be determined as the melting point (Tm) of the thermoplastic liquid crystal polymer film.

[0068] The thickness of the thermoplastic liquid crystal polymer film can be set appropriately depending on the application. For example, when considering its use as a material for the insulating layer of a circuit board, it may be 10 to 500 μm, preferably 15 to 250 μm, more preferably 20 to 200 μm, and even more preferably 25 to 150 μm.

[0069] (Method for manufacturing thermoplastic liquid crystal polymer film) Any extrusion molding method can be used when forming thermoplastic liquid crystal polymer film, but the well-known T-die film formation stretching method, laminate stretching method, and inflation method are industrially advantageous. In particular, with the inflation method, stress is applied not only in the mechanical axis direction of the thermoplastic liquid crystal polymer film (hereinafter abbreviated as the MD direction) but also in the direction perpendicular to it (hereinafter abbreviated as the TD direction), allowing for uniform stretching in both the MD and TD directions. As a result, a thermoplastic liquid crystal polymer film with controlled molecular orientation and dielectric properties in the MD and TD directions can be obtained.

[0070] Furthermore, thermoplastic liquid crystal polymer films may be stretched after extrusion molding as needed. The stretching method itself is well known, and either biaxial stretching or uniaxial stretching may be used, but biaxial stretching is preferred because it is easier to control the degree of molecular orientation. In addition, known uniaxial stretchers, simultaneous biaxial stretchers, sequential biaxial stretchers, etc., can be used for stretching.

[0071] In extrusion molding, in order to control orientation, a stretching process may be involved. For example, in extrusion molding by the T-die method, the melt sheet extruded from the T-die may be stretched simultaneously in both the MD direction and the TD direction with respect to the thermoplastic liquid crystal polymer film to form a film, or the melt sheet extruded from the T-die may be stretched first in the MD direction and then in the TD direction to form a film.

[0072] Also, in extrusion molding by the inflation method, the cylindrical sheet melt-extruded from the ring die may be stretched at a predetermined draw ratio (corresponding to the stretching magnification in the MD direction) and blow ratio (corresponding to the stretching magnification in the TD direction) to form a film.

[0073] Also, if necessary, known or conventional heat treatment may be performed to adjust the melting point and / or thermal expansion coefficient of the thermoplastic liquid crystal polymer. The heat treatment conditions can be appropriately set according to the purpose. For example, with respect to the melting point (Tm ０ ) of the thermoplastic liquid crystal polymer, by heating at (Tm ０ - 10) °C or higher (for example, about (Tm ０ - 10) °C to (Tm ０ + 30) °C, preferably about (Tm ０ ) °C to (Tm ０ + 20) °C) for several hours, the melting point (Tm) of the thermoplastic liquid crystal polymer may be increased. Note that depending on the composition of the thermoplastic liquid crystal polymer, the melting point can also be increased with a shorter heating time, for example, 1 hour or less. Also, for example, with respect to the melting point (Tm ０ ) of the thermoplastic liquid crystal polymer, by heating at a temperature of (Tm ０ - 15) °C or higher and less than (Tm ０ ) °C for 5 to 60 seconds (for example, 10 to 30 seconds), the thermal expansion coefficient may be increased.

[0074] (Metal-clad laminate) One embodiment of the present invention is a metal-clad laminate comprising the thermoplastic liquid crystal polymer film described above and a metal layer laminated on at least one surface of the thermoplastic liquid crystal polymer film. The metal-clad laminate may be a double-sided metal-clad laminate in which metal sheets are laminated on both sides of the thermoplastic liquid crystal polymer film, or a single-sided metal-clad laminate in which a metal sheet is laminated on one side of the thermoplastic liquid crystal polymer film. In the case of a double-sided metal-clad laminate, the two metal sheets laminated on the thermoplastic liquid crystal polymer film may be the same or different. In the case of a single-sided metal-clad laminate, a separate metal layer may be provided on the side of the thermoplastic liquid crystal polymer film that does not have a metal sheet (e.g., metal foil) laminated on it. In this case, another metal foil may be laminated on the side of the thermoplastic liquid crystal polymer film that does not have a metal foil laminated on it, or the metal layer may be formed by sputtering, vapor deposition or plating.

[0075] There are no particular restrictions on the metal that forms the metal layer; for example, it may be gold, silver, copper, iron, tin, nickel, aluminum, chromium, or alloys thereof. These metals may contain other metal species in amounts of 2000 ppm by mass or less, and unavoidable impurities may be present.

[0076] When using metal foil as the metal layer, for example, it may be a metal foil formed from the above-mentioned metals, and copper foil or stainless steel foil is preferred from the viewpoint of conductivity, ease of handling, and cost. Copper foil can be manufactured by rolling or electrolytic methods. Furthermore, the metal foil may be subjected to surface treatments such as roughening treatments that are normally applied, as long as they do not impair the high-frequency characteristics of the metal-clad laminate of the present invention.

[0077] In sputtering or vapor deposition, a process is carried out to bring metal parts into contact and bond them together by sputtering or vapor deposition of metal. Sputtering and vapor deposition are well-known methods in the field of circuit board manufacturing. Examples of metals used for sputtering or vapor deposition include copper, aluminum, gold, tin, and chromium.

[0078] A circuit board can be manufactured by processing a metal sheet of a metal-clad laminate into a wiring circuit. Known methods can be used for circuit processing; for example, circuits may be formed by etching a metal sheet on a thermoplastic liquid crystal polymer film using a subtractive method.

[0079] The metal-clad laminate manufactured according to the present invention can be effectively used as a component in the electrical and electronic fields, office equipment and precision equipment fields, power semiconductor fields, etc., for example, as a circuit board material, and is suitable for applications such as high-frequency circuit boards, automotive sensors, mobile device circuit boards, and antennas.

[0080] The present invention will be described in more detail below with reference to examples, but the present invention is not limited in any way by these examples. In the following examples and comparative examples, various physical properties were measured by the methods described below.

[0081] [Melting Point] The melting points of the thermoplastic liquid crystal polymer as a precursor to the composition obtained in the production example, and the compositions (thermoplastic liquid crystal polymer films formed from the compositions) obtained in the examples and comparative examples were determined using a differential scanning calorimeter (DSC, Shimadzu Corporation). The thermoplastic liquid crystal polymer or thermoplastic liquid crystal polymer film was heated at a rate of 10°C / min until completely melted at 400°C, then the molten material was cooled to 50°C at a rate of 10°C / min, and the position of the endothermic peak that appeared when the temperature was raised again at a rate of 10°C / min was defined as the melting point of the thermoplastic liquid crystal polymer or composition (thermoplastic liquid crystal polymer film).

[0082] [Melting Viscosity] The melting viscosity of the thermoplastic liquid crystal polymer obtained in the production example and the compositions obtained in the examples and comparative examples was measured using a capillary graph (Gottfert Rheograph 20) with a capillary size of 1 mm in diameter and 10 mm in length, a measurement temperature of the melting point of the thermoplastic liquid crystal polymer or composition + 15°C, and a shear rate of 1000 s. －１ The melt viscosity was measured.

[0083] [Melting Shear Viscosity] A 1.00 mm thick sample was prepared by laminating 20 layers of thermoplastic liquid crystal polymer films with a thickness of 50 μm obtained in the examples and comparative examples. Using a rotational viscoelasticity measuring rheometer (ARES-G2) manufactured by TA Instruments, the measurement mode was set to Dynamic Frequency Sweep Test, a φ25 mm parallel plate was used, with a gap of 1.00 mm, an initial strain of 10%, a frequency of 0.01 to 500 rad / s, and in an air atmosphere. The temperature condition was set to the melting point of the composition + 15°C, and after melting for 5 minutes, the sample was relaxed for 5 minutes after reaching the measurement position. The Transducer detection torque was set to 0.02 to 200 g·cm and the measurement was performed. The frequency was measured from the low frequency side. The maximum viscosity in the frequency range of 0.01 to 500 rad / s and the shear rate at which that maximum viscosity was observed were measured.

[0084] <Melting Viscosity Characteristic Region α> In the frequency range from 0.01 rad / s to 100 rad / s, the melting viscosity characteristic region α was defined as the region in which the differential value dη / df of the change in melting shear viscosity η with respect to an increase in the measurement frequency f is 0 or greater, and its presence or absence was confirmed.

[0085] <Melting Viscosity Characteristic Region β> As the measurement frequency increases from 0.01 rad / s, the melting shear viscosity rises to its peak value and then declines. This melting viscosity characteristic region β was defined as the melting viscosity characteristic region β, and its presence or absence was confirmed. Furthermore, if melting viscosity characteristic region β exists, the frequency at which the melting shear viscosity peaks was confirmed.

[0086] [Method for Determining Film Forming Abnormalities] Film formation abnormalities were determined by checking for abnormalities in the extrusion molding process. In inflation film formation, the condition of the frost line and the amount of deposit buildup were checked, while in T-die melt extrusion, the amount of deposit buildup was mainly checked. If there were no particular problems, it was marked as "none," and if there were problems, the condition such as deposit buildup and unstable frost was described.

[0087] [Film Thickness Measurement] A film cut from an arbitrary point in the MD (longitudinal direction) of the base film in the TD (width direction) direction was measured every 0.1 mm in the TD direction of the film using a contact-type web thickness gauge (RC-101 manufactured by Meisan Co., Ltd.), and the arithmetic mean of the measured values ​​was taken as the reference film thickness (μm).

[0088] [Film Thickness Unevenness] After measuring the film thickness at an arbitrary location and determining the average film thickness, areas suspected of being uneven were selected based on the film's density using transmitted light, and localized film thickness measurements were performed using a micrometer (Mitutoyo Corporation high-precision digital micrometer MDH-25MB). With transmitted light, areas with locally thicker film thickness appear darker due to less transmitted light, while thinner areas appear white. Particularly dark and thin areas were selected. A: A thickness difference of less than ±10% from the average film thickness was considered good film thickness unevenness. B: A thickness difference of ±10% or more from the average film thickness was considered poor film thickness unevenness.

[0089] [Method for evaluating the number of defects] 10m of film at any given location ２ The samples were removed, and areas suspected to be defective on both the front and back surfaces were selected. Detailed size measurements were then performed using a digital microscope (Olympus Corporation's "LEXT® OLS5100"). Foreign objects and scratches with a diameter of 250 μm or more were judged to be defective, and 10 m ２ The number of defective items per unit was defined as the defect count.

[0090] [Production Example 1] (Preparation of Thermoplastic Liquid Crystal Polymer A) A 6-liter reactor equipped with a torque meter-equipped stirrer, temperature control indicator, nitrogen gas inlet tube, reflux column, monomer inlet, and vacuum / outlet line was used to add 1326 g (80 mol%) of p-hydroxybenzoic acid, 452 g (20 mol%) of 6-hydroxy-2-naphthoic acid, 1246 g (1.02 times the hydroxyl group equivalent) of acetic anhydride, and 0.24 g (K) of potassium acetate as a catalyst (relative to the amount of the resulting resin). ＋A concentration of 60 ppm by mass was charged. After purging the system with nitrogen gas, acetylation was carried out (160°C, reflux for approximately 2 hours). Then, while removing the by-product acetic acid by distillation under reduced pressure of 1000 Pa, the temperature was raised to 340°C at a rate of approximately 4°C per minute and maintained at that state for 4 hours. After that, nitrogen purging was performed to obtain aromatic liquid crystal polyester. Subsequently, the aromatic liquid crystal polyester was processed into cylindrical pellets with a length of 6 mm and a diameter of 2 mm. The melting point of the obtained thermoplastic liquid crystal polymer was 325°C and the melt viscosity was 35 Pa·s.

[0091] [Production Example 2] (Preparation of Thermoplastic Liquid Crystal Polymer B) A 6-liter reactor equipped with a torque meter-equipped stirrer, temperature control indicator, nitrogen gas inlet tube, reflux column, monomer inlet, and vacuum / outlet line was used to add 1326 g (80 mol%) of p-hydroxybenzoic acid, 452 g (20 mol%) of 6-hydroxy-2-naphthoic acid, 1246 g (1.02 times the hydroxyl group equivalent) of acetic anhydride, and 0.24 g of potassium acetate as a catalyst (relative to the amount of the resulting resin). ＋ A concentration of 60 ppm by mass was charged. After purging the system with nitrogen gas, acetylation was carried out (160°C, reflux for approximately 2 hours). Then, while removing the by-product acetic acid by distillation under reduced pressure of 1000 Pa, the temperature was raised to 340°C at a rate of approximately 2°C per minute and maintained at that state for 1 hour. After that, nitrogen purging was performed to obtain aromatic liquid crystal polyester. Subsequently, the aromatic liquid crystal polyester was processed into cylindrical pellets with a length of 6 mm and a diameter of 2 mm. The melting point of the obtained prepolymer was 320°C and the melt viscosity was 40 Pa·s.

[0092] Subsequently, the pelletized prepolymer was pulverized using a freeze-milling machine, and the powdered prepolymer was placed in a hopper-type solid-phase polymerization apparatus. The temperature was raised from room temperature to 290°C for 3 hours in a heated nitrogen gas flow of 12 liters per minute, and then the solid-phase polymerization reaction was carried out at 300°C until a thermoplastic liquid crystal polymer with a high degree of polymerization was produced, with a melting point of 321°C and a melt viscosity of 55 Pa·s.

[0093] [Production Example 3] (Preparation of Thermoplastic Liquid Crystal Polymer C) A 6-liter reactor equipped with a torque meter-equipped stirrer, temperature control indicator, nitrogen gas inlet tube, reflux column, monomer inlet, and vacuum / outlet line was used to add 1326 g (80 mol%) of p-hydroxybenzoic acid, 452 g (20 mol%) of 6-hydroxy-2-naphthoic acid, 1246 g (1.02 times the hydroxyl group equivalent) of acetic anhydride, and 0.24 g of potassium acetate as a catalyst (relative to the amount of the resulting resin). ＋ A concentration of 60 ppm by mass was charged. After purging the system with nitrogen gas, acetylation was carried out (160°C, reflux for approximately 2 hours). Then, the by-product acetic acid was removed by distillation under reduced pressure of 1000 Pa while the temperature was raised to 340°C at a rate of approximately 2°C per minute, and this state was maintained for 2 hours. After that, nitrogen purging was performed to obtain aromatic liquid crystal polyester. Subsequently, the aromatic liquid crystal polyester was processed into cylindrical pellets with a length of 6 mm and a diameter of 2 mm. The melting point of the obtained prepolymer was 325°C and the melt viscosity was 40 Pa·s.

[0094] Subsequently, the pelletized prepolymer was placed in a hopper-type solid-phase polymerization apparatus and heated from room temperature to 290°C for 3 hours in a heated nitrogen gas flow of 12 liters per minute. Solid-phase polymerization was then carried out at 300°C to produce a thermoplastic liquid crystal polymer with a melting point of 326°C and a melt viscosity of 75 Pa·s.

[0095] [Production Example 4] (Preparation of Thermoplastic Liquid Crystal Polymer D) A 6-liter reactor equipped with a torque meter-equipped stirrer, temperature control indicator, nitrogen gas inlet tube, reflux column, monomer inlet, and vacuum / outlet line was used to add 1109 g (73 mol%) of p-hydroxybenzoic acid, 559 g (27 mol%) of 6-hydroxy-2-naphthoic acid, 1125 g (1.02 times the hydroxyl group equivalent) of acetic anhydride, and 0.22 g of potassium acetate as a catalyst (relative to the amount of the resulting resin). ＋A concentration of 60 ppm by mass was charged. After purging the system with nitrogen gas, acetylation was carried out (160°C, reflux for approximately 2 hours). Subsequently, the by-product acetic acid was removed by distillation under reduced pressure of 1000 Pa while the temperature was raised to 300°C at a rate of approximately 2°C per minute, and this state was maintained for 1 hour. After that, nitrogen purging was performed to obtain an aromatic liquid crystal polyester. The melting point of the thermoplastic liquid crystal polymer was 280°C and the melt viscosity was 30 Pa·s.

[0096] [Production Example 5] (Preparation of Thermoplastic Liquid Crystal Polymer E) A 6-liter reactor equipped with a torque meter-equipped stirrer, temperature control indicator, nitrogen gas inlet tube, reflux column, monomer inlet, and vacuum / outlet line was used to add 1139 g (75 mol%) of p-hydroxybenzoic acid, 517 g (25 mol%) of 6-hydroxy-2-naphthoic acid, 1145 g (1.02 times the hydroxyl group equivalent) of acetic anhydride, and 0.22 g of potassium acetate as a catalyst (relative to the amount of the resulting resin). ＋ A concentration of 60 ppm by mass was charged. After purging the system with nitrogen gas, acetylation was carried out (160°C, reflux for approximately 2 hours). Then, the by-product acetic acid was removed by distillation under reduced pressure of 1000 Pa while the temperature was raised to 335°C at a rate of approximately 2°C per minute, and this state was maintained for 1 hour. After that, nitrogen purging was performed to obtain aromatic liquid crystal polyester. Subsequently, the aromatic liquid crystal polyester was processed into cylindrical pellets with a length of 6 mm and a diameter of 2 mm. The melting point of the obtained thermoplastic liquid crystal polymer was 315°C and the melt viscosity was 30 Pa·s.

[0097] [Production Example 6] (Preparation of Thermoplastic Liquid Crystal Polymer F) A 6-liter reactor equipped with a torque meter-equipped stirrer, temperature control indicator, nitrogen gas inlet tube, reflux column, monomer inlet, and vacuum / outlet line was used to add 1326 g (80 mol%) of parahydroxybenzoic acid, 452 g (20 mol%) of 6-hydroxy-2-naphthoic acid, 1246 g (1.02 times the hydroxyl group equivalent) of acetic anhydride, and 0.24 g of potassium acetate as a catalyst (relative to the amount of the resulting resin). ＋A concentration of 60 ppm by mass was charged. After purging the system with nitrogen gas, acetylation was carried out (160°C, reflux for approximately 2 hours). Subsequently, the by-product acetic acid was removed by distillation under reduced pressure of 1000 Pa while the temperature was raised to 340°C at a rate of approximately 2°C per minute, and this state was maintained for 1.5 hours. After that, nitrogen purging was performed to obtain aromatic liquid crystal polyester. The aromatic liquid crystal polyester was then processed into cylindrical pellets with a length of 6 mm and a diameter of 2 mm. The obtained thermoplastic liquid crystal polymer had a melting point of 325°C and a melt viscosity of 40 Pa·s.

[0098] [Production Example 7] (Preparation of Thermoplastic Liquid Crystal Polymer G) A 6-liter reactor equipped with a torque meter-equipped stirrer, temperature control indicator, nitrogen gas inlet tube, reflux column, monomer inlet, and vacuum / outlet line was used to add 1326 g (80 mol%) of parahydroxybenzoic acid, 452 g (20 mol%) of 6-hydroxy-2-naphthoic acid, 1246 g (1.02 times the hydroxyl group equivalent) of acetic anhydride, and 0.24 g of potassium acetate as a catalyst (relative to the amount of the resulting resin). ＋ A concentration of 60 ppm by mass was charged. After purging the system with nitrogen gas, acetylation was carried out (160°C, reflux for approximately 2 hours). Then, while removing the by-product acetic acid by distillation under reduced pressure of 1000 Pa, the temperature was raised to 340°C at a rate of approximately 2°C per minute and maintained at that state for 1 hour. After that, nitrogen purging was performed to obtain aromatic liquid crystal polyester. Subsequently, the aromatic liquid crystal polyester was processed into cylindrical pellets with a length of 6 mm and a diameter of 2 mm. The melting point of the obtained prepolymer was 325°C and the melt viscosity was 40 Pa·s.

[0099] Subsequently, the pelletized prepolymer was placed in a hopper-type solid-phase polymerization apparatus and heated from a greenhouse to 290°C for 3 hours in a heated nitrogen gas flow of 12 liters per minute. Solid-phase polymerization was then carried out at 300°C to produce a thermoplastic liquid crystal polymer with a melting point of 325°C and a melt viscosity of 50 Pa·s, resulting in a high degree of polymerization thermoplastic liquid crystal polymer.

[0100]

[0101] [Example 1] Pellets of thermoplastic liquid crystal polymers A and B prepared in Production Examples 1 and 2 were placed in a hopper in the mass ratio shown in Table 7, kneaded at 280 to 350°C, and then pelletized again to obtain a composition containing thermoplastic liquid crystal polymers. Next, the obtained pelletized thermoplastic liquid crystal polymer composition was heated and kneaded at 280 to 340°C using an extruder, and then extruded through an inflation die with a diameter of 40 mm and a slit spacing of 0.6 mm to obtain a thermoplastic liquid crystal polymer film with a thickness of 50 μm.

[0102] [Examples 2-4] Thermoplastic liquid crystal polymer films of Examples 2-4 were obtained in the same manner as in Example 1, except that the mass ratio of the thermoplastic liquid crystal polymer pellets was changed as shown in Table 8.

[0103] [Example 5] A pelletized thermoplastic liquid crystal polymer composition was obtained by mixing the thermoplastic liquid crystal polymer pellets in the same ratio as in Example 4. Next, the obtained pelletized thermoplastic liquid crystal polymer composition was formed by T-die casting to obtain a thermoplastic liquid crystal polymer film with a thickness of 50 μm.

[0104] [Comparative Examples 1-4] Thermoplastic liquid crystal polymer films of Comparative Examples 1-4 were obtained in the same manner as in Example 1, except that the mass ratio of the thermoplastic liquid crystal polymer pellets was changed as shown in Table 8.

[0105]

[0106] The shear rate dependence of the melting point and melt shear viscosity was evaluated for the thermoplastic liquid crystal polymer films obtained in Examples 1-5 and Comparative Examples 1-4 using the method described above. The film-forming properties during film formation and the results are shown in Table 9.

[0107]

[0108] As shown in Table 9, melt viscosity characteristic regions α and β were observed in Examples 1 to 5 of the present invention. That is, when the melt shear viscosity of the composition was measured while increasing the frequency from 0.01 rad / s, the melt shear viscosity continuously increased up to the maximum viscosity measured at a predetermined frequency (shear rate), and then decreased as the frequency was further increased. In contrast, in the compositions of Comparative Examples 1 to 4, the melt shear viscosity took its maximum value at a measurement frequency of 0.01 rad / s, and as the frequency increased, the melt shear viscosity continuously decreased, so neither melt viscosity characteristic regions α nor β were observed. As an example, Figure 1 shows the results of measuring the change in melt shear viscosity with respect to the change in measurement frequency for Example 2 and Comparative Example 1. In the composition of Comparative Example 1, the viscosity decreased with increasing measurement frequency, similar to conventional thermoplastic liquid crystal polymers, but in the composition of Example 2 of the present invention, as the measurement frequency increased from 0.01 rad / s, the melt viscosity increased to a peak value (this period is region α), and then decreased. As shown in Table 9, in Examples 1 to 5, no abnormalities occurred during film formation, and thermoplastic liquid crystal polymer films with minimal film thickness variations and few defects were obtained. In contrast, in Comparative Examples 1 to 3, films with greater film thickness variations and more defects were produced than the films obtained in the examples. In Comparative Example 2, grease (adhesion to the die lip) occurred during film formation, in Comparative Examples 3 and 4, the frost line was unstable, and in Comparative Example 4, no film could be formed. From these results, it can be seen that compositions exhibiting a melt viscosity characteristic region α in which the differential value dη / df of the change in melt shear viscosity η with respect to an increase in the measurement frequency f is 0 or greater in the frequency range of 0.01 rad / s to 100 rad / s have preferable film-forming properties.

[0109] Thermoplastic liquid crystal polymers having melt viscoelastic properties as described in the present invention are easily melt-molded and can be effectively used as thermoplastic liquid crystal polymer films, including those with orientation control.

[0110] As described above, preferred embodiments of the present invention have been explained, but those skilled in the art will readily anticipate various changes and modifications within the obvious scope upon reviewing this specification. Therefore, such changes and modifications will be interpreted as falling within the scope of the invention as defined by the claims.

Claims

1. A composition comprising a polymer capable of forming an optically anisotropic molten phase (hereinafter referred to as a thermoplastic liquid crystal polymer), wherein when the molten shear viscosity of the composition is measured at a temperature of the melting point + 15°C using a rotational rheometer equipped with a parallel plate while increasing the frequency from 0.01 rad / s, the composition exhibits a molten viscosity characteristic region in which the differential value dη / df of the change in molten shear viscosity η with respect to an increase in the measurement frequency f is 0 or greater in the frequency range from 0.01 rad / s to 100 rad / s.

2. The composition according to claim 1, wherein when the melt shear viscosity of the composition is measured at a temperature of the melting point + 15°C using a rotational rheometer equipped with a parallel plate, while increasing the frequency from 0.01 rad / s, the melt shear viscosity rises to a peak value as the measurement frequency increases from 0.01 rad / s, and then declines thereafter.

3. The composition according to claim 1, wherein the melt shear viscosity of the composition, measured using a rotational rheometer equipped with parallel plates at a temperature of the melting point of the composition + 15°C, satisfies the following conditions: at a frequency of 0.01 rad / s, it is 7,000 Pa·s or more and 60,000 Pa·s or less; and at a frequency of 100 rad / s, it is 100 Pa·s or more.

4. The composition according to claim 1, wherein the melt shear viscosity of the composition, measured using a rotational rheometer equipped with parallel plates at a temperature of the melting point of the composition + 15°C, is 6000 Pa·s or more at a frequency of 0.1 rad / s and 600 Pa·s or less at a frequency of 100 rad / s.

5. The composition according to claim 1, wherein the melting point of the composition is 315°C or higher.

6. The composition according to claim 1, wherein the inorganic content is 1% by mass or less.

7. The composition according to claim 1, comprising a thermoplastic liquid crystal polymer (I) having a melt viscosity of 40 Pa·s or less, and a thermoplastic liquid crystal polymer (II) having a melt viscosity greater than 40 Pa·s.

8. The composition according to claim 7, wherein the mass ratio of the thermoplastic liquid crystal polymer (I) to the thermoplastic liquid crystal polymer (II) is (I) / (II) = 10 / 90 to 90 / 10.

9. A thermoplastic liquid crystal polymer film comprising the composition described in any one of claims 1 to 8.

10. A metal-clad laminate comprising a thermoplastic liquid crystal polymer film according to claim 9 and a metal layer laminated on at least one surface of the thermoplastic liquid crystal polymer film.

11. A method for producing the composition according to any one of claims 1 to 8, comprising the steps of: preparing at least two thermoplastic liquid crystal polymers having different melt viscosities; and melt-kneading the at least two thermoplastic liquid crystal polymers having different melt viscosities.

12. A method for producing the composition according to claim 11, wherein the at least two thermoplastic liquid crystal polymers with different melt viscosities have the same composition and undergo different polymerization processes.

13. A method for producing a thermoplastic liquid crystal polymer film, comprising extruding a composition according to any one of claims 1 to 8.

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