Recycled liquid crystal polyester resin composition and method for producing the same

Abstract

To provide a recycled liquid crystal polyester resin composition which has high maintenance rates of flowability and mechanical strength, and suppresses appearance defects of an obtained molding.SOLUTION: A recycled liquid crystal polyester resin composition is obtained by melting and kneading a waste liquid crystal polyester resin composition (W) containing 50 to 95 mass% of a liquid crystal polyester resin (WA), 2.5 to 30 mass% of a plate-like filler (WB) and 2.5 to 20 mass% of a spherical filler (WC), an unused liquid crystal polyester resin (VA), an unused plate-like filler (VB) and an unused spherical filler (VC). The total percentage content of the unused liquid crystal polyester resin (VA) and the liquid crystal polyester resin (WA) in the recycled liquid crystal polyester resin composition is 50 to 95 mass%, the total percentage content of the unused plate-like filler (VB) and the plate-like filler (WB) is 2.5 to 30 mass%, the total percentage content of the unused spherical filler (VC) and the spherical filler (WC) is 2.5 to 20 mass%, and the percentage content of the waste liquid crystal polyester resin composition (W) is 50 to 85 mass%.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a recycled liquid crystal polyester resin composition and a method for producing the same. In particular, the present invention is suitable for recycling waste liquid crystal polyester resin compositions discharged during the molding of small electronic products such as connectors with a high waste rate during molding. However, the scope of application of the present invention is not limited thereto.

Background Art

[0002] Liquid crystal polyester resin (hereinafter sometimes referred to as "LCP") takes advantage of its excellent balance of heat resistance, mechanical strength, insulation, and flame retardancy, and its ease of molding processing, and is applied to various uses such as electrical and electronic parts and optical device parts. In such applications, in order to meet the required characteristics (for example, flexural strength) in various applications, reinforced LCP compositions in which fillers such as glass fibers and talc are blended are often used in liquid crystal polyester resins (Patent Documents 1 to 8).

[0003] Patent Document 1 proposes a reinforced LCP composition in which glass fibers and glass fine powder obtained by pulverizing the glass fibers are blended as fillers. Patent Document 2 proposes a reinforced LCP composition in which glass fibers are blended as fillers. Patent Documents 1 and 2 list talc and glass beads among many examples of plate-shaped and granular fillers other than glass fibers, but there are no specific examples of blending fillers other than glass fibers, and their content ratios, etc. have not been studied at all. Patent Document 3 describes that an inorganic filler can be blended in a liquid crystal polyester resin, and among many examples of inorganic fillers, glass beads and talc are exemplified, but there are no specific examples of blending fillers, and their content ratios, etc. have not been studied at all. Patent Document 4 describes that glass fibers and plate-shaped fillers such as talc are used in combination as fillers, but there is no description of spherical fillers. Patent Document 5 describes that fibrous, granular, or plate-like fillers may be blended as fillers, and it also describes that the combined use of fibrous fillers and granular or plate-like fillers is preferable, but specifically only chopped glass fibers or milled glass fibers are used. Patent Documents 6 and 7 describe a reinforced LCP composition containing talc and glass fibers as fillers, and there is also an example of glass beads as other fillers, but there is no specific description of the use of other fillers, and no consideration has been given to their content ratio. Patent Document 8 describes a liquid crystal polymer composition using talc and glass beads in combination as fillers. Patent Document 8 has a wide range of descriptions regarding the blending ratio of talc and glass beads, but Patent Document 8 has no description or suggestion regarding the recycling of the liquid crystal polymer composition, and no consideration has been given to the blending ratio for that purpose.

[0004] On the other hand, in recent years, the formation of a recycling-oriented society aimed at reducing the environmental impact has been promoted, and material recycling, which is expected to reduce greenhouse gas emissions and the final amount of waste, has been emphasized.

[0005] Since LCP has high fluidity and insulation compared to other resins, it has a lot of adoption records in small electronic products such as connectors. In the molding process of small electronic products, the proportion of sprues and runners to the product part is as high as 90%, and the waste rate is high, so material recycling is strongly desired. However, conventionally, in LCP, especially in reinforced LCP compositions containing fillers, the development of recycling technologies that can maintain high required quality has not advanced sufficiently. For example, in the field of electronic components, in recent years, due to the lead-freeization of solder, the reflow temperature has been increasing. However, when an electronic component made of a liquid crystal polyester molded product is subjected to reflow processing at a high temperature, swelling (hereinafter sometimes referred to as blistering) occurs on the surface of the molded product. The causes of this blistering are considered to be decomposition gases encapsulated in the resin and the volatilization of air and moisture entrained during melt plasticization in the molding machine. Therefore, when melt molding is repeated by recycling, blisters are more likely to occur. Since blisters cause appearance defects and dimensional defects in the product, it is necessary to prevent blisters as much as possible. However, conventional recycling technologies have not been able to suppress appearance defects such as blisters.

[0006] In Patent Document 1, the recycling of reinforced LCP compositions is an issue. However, in a reinforced LCP composition using glass fiber as a filler as in Patent Document 1, as shown in Comparative Example 2 below, there are problems such as a decrease in fluidity, mechanical strength, and the appearance of the resulting molded product due to recycling. Patent Document 8 describes the combined use of talc and glass beads as fillers. However, as described above, Patent Document 8 does not have the issue of recycling reinforced LCP compositions, and no consideration has been given to the ratio of waste LCP compositions to unused LCP compositions for recycling, nor has any consideration been given to its recycling method. Note that Patent Document 9 describes a recycled resin composition, but it is not related to a liquid crystal polyester resin composition, and only glass fiber is used as a filler.

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

[0008] As described above, the conventionally proposed reinforced LCP compositions are not suitable for recycling. When waste materials of the waste reinforced LCP compositions are recovered and recycled into recycled reinforced LCP compositions, there are problems that the fluidity, mechanical strength, and appearance of the obtained molded products are significantly impaired. The reason for this is that in the conventionally proposed reinforced LCP compositions, due to crushing of the filler and deterioration of the resin caused by the heat history and shear force in the melt kneading and subsequent molding processes, etc., it causes a significant decrease in quality such as mechanical strength, fluidity, and molded product appearance during recycling. Therefore, in the LCP industry, high-quality recycled reinforced LCP compositions utilizing recycled materials have not yet been provided.

[0009] For these reasons, there is a strong demand for the development of a recycled reinforced LCP composition that can maintain good quality even when repeatedly manufactured by blending recycled materials.

[0010] The present invention has been made in view of the above-described conventional situation, and is a recycled liquid crystal polyester resin composition obtained by blending a recycled material, which has a high retention rate of fluidity and a high retention rate of the flexural stress of the resulting molded product, and also suppresses appearance defects such as blisters and poor surface smoothness when the resulting molded product is heated. An object of the present invention is to provide a recycled liquid crystal polyester resin composition and a method for producing the same.

Means for Solving the Problems

[0011] The present inventors melted and kneaded an unused liquid crystal polyester resin, an unused plate-shaped filler, and an unused spherical filler with a recycled material, that is, a waste liquid crystal polyester resin composition containing a plate-shaped filler and a spherical filler as fillers, to produce a recycled liquid crystal polyester resin composition. At that time, it was found that the above problems can be solved by controlling the quantitative ratios of the liquid crystal polyester resin, the plate-shaped filler, and the spherical filler derived from the waste liquid crystal polyester resin composition and the unused liquid crystal polyester resin, plate-shaped filler, and spherical filler to be melt-kneaded therewith. The present invention has been achieved based on such findings, and the gist thereof is as follows.

[0012] [1] A recycled liquid crystal polyester resin composition obtained by melt-kneading a waste liquid crystal polyester resin composition (W), an unused liquid crystal polyester resin (VA), an unused plate-shaped filler (VB), and an unused spherical filler (VC), wherein the waste liquid crystal polyester resin composition (W) is a liquid crystal polyester resin composition containing 50 to 95% by mass of a liquid crystal polyester resin (WA), 2.5 to 30% by mass of a plate-shaped filler (WB), and 2.5 to 20% by mass of a spherical filler (WC), the total content of the unused liquid crystal polyester resin (VA) and the liquid crystal polyester resin (WA) contained in the recycled liquid crystal polyester resin composition is 50 to 95% by mass, the total content of the unused plate-shaped filler (VB) and the plate-shaped filler (WB) contained in the recycled liquid crystal polyester resin composition is 2.5 to 30% by mass, The total content of the unused spherical filler (VC) and the spherical filler (WC) contained in the recycled liquid crystal polyester resin composition is 2.5 to 20% by mass, and The recycled liquid crystal polyester resin composition is characterized in that the content of the waste liquid crystal polyester resin composition (W) contained in the recycled liquid crystal polyester resin composition is 50 to 85% by mass.

[0013] [2] The recycled liquid crystal polyester resin composition according to [1], wherein the unused plate-shaped filler (VB) is talc.

[0014] [3] The recycled liquid crystal polyester resin composition according to [1] or [2], wherein the plate-shaped filler (WB) is talc.

[0015] [4] The recycled liquid crystal polyester resin composition according to any one of [1] to [3], wherein the average particle diameters of the unused plate-shaped filler (VB) and the plate-shaped filler (WB) are 1 to 100 μm.

[0016] [5] The recycled liquid crystal polyester resin composition according to any one of [1] to [4], wherein the unused spherical filler (VC) is glass beads.

[0017] [6] The recycled liquid crystal polyester resin composition according to any one of [1] to [5], wherein the spherical filler (WC) is glass beads.

[0018] [7] The recycled liquid crystal polyester resin composition according to any one of [1] to [6], wherein the average particle diameters of the unused spherical filler (VC) and the spherical filler (WC) are 3 to 80 μm.

[0019] [8] The recycled liquid crystal polyester resin composition according to any one of [1] to [7], wherein the retention rate of the flexural stress obtained by the following formula is 90% or more. Retention rate of flexural stress (%) = (S5 / S0) × 100 However, S5 and S0 are as follows. S0: Bending stress (MPa) measured in accordance with ISO 178 for the recycled liquid crystal polyester resin composition using the unregenerated waste liquid crystal polyester resin composition (W) as the waste liquid crystal polyester resin composition (W). S5: Bending stress (MPa) measured in accordance with ISO 178 for the recycled liquid crystal polyester resin composition obtained using the waste liquid crystal polyester resin composition (W) that has been recycled 5 times as the waste liquid crystal polyester resin composition (W).

[0020] [9] A method for producing a recycled liquid crystal polyester resin composition by melt-kneading a waste liquid crystal polyester resin composition (W), an unused liquid crystal polyester resin (VA), an unused plate-shaped filler (VB), and an unused spherical filler (VC), wherein the waste liquid crystal polyester resin composition (W) is a liquid crystal polyester resin composition containing 50 to 95% by mass of a liquid crystal polyester resin (WA), 2.5 to 30% by mass of a plate-shaped filler (WB), and 2.5 to 20% by mass of a spherical filler (WC), using the unused liquid crystal polyester resin (VA) such that the total content of the unused liquid crystal polyester resin (VA) and the liquid crystal polyester resin (WA) contained in the recycled liquid crystal polyester resin composition is 50 to 95% by mass, using the unused plate-shaped filler (VB) such that the total content of the unused plate-shaped filler (VB) and the plate-shaped filler (WB) contained in the recycled liquid crystal polyester resin composition is 2.5 to 30% by mass, using the unused spherical filler (VC) such that the total content of the unused spherical filler (VC) and the spherical filler (WC) contained in the recycled liquid crystal polyester resin composition is 2.5 to 20% by mass, and using the waste liquid crystal polyester resin composition (W) such that the content of the waste liquid crystal polyester resin composition (W) contained in the recycled liquid crystal polyester resin composition is 50 to 85% by mass. A method for producing a recycled liquid crystal polyester resin composition characterized by this. [Advantages of the Invention]

[0021] According to the present invention, there is provided a recycled liquid crystal polyester resin composition obtained by blending a waste liquid crystal polyester resin composition as a recycled material, which has a high retention rate of fluidity and a high retention rate of mechanical strength such as bending stress, and also suppresses appearance defects such as blisters and poor surface smoothness when the obtained molded product is heated.

Embodiments for Carrying Out the Invention

[0022] Hereinafter, the present invention will be described in detail. However, the description of the constituent elements described below is a representative example of the embodiments of the present invention, and the present invention is not limited to these contents.

[0023] 〔Recycled Liquid Crystal Polyester Resin Composition〕 In the present invention, the recycled liquid crystal polyester resin composition is obtained by melt-kneading a waste liquid crystal polyester resin composition (W), an unused liquid crystal polyester (VA), an unused plate-shaped filler (VB), and an unused spherical filler (VC) using an extruder or the like, extruding them into strands, and pelletizing them. In the present invention, the unused liquid crystal polyester resin (VA), the unused plate-shaped filler (VB), and the unused spherical filler (VC) are the unused liquid crystal polyester resin (VA), the unused plate-shaped filler (VB), and the unused spherical filler (VC) as raw materials for the liquid crystal polyester resin composition without being melt-kneaded and pelletized in advance, and in the present invention, these are directly melt-kneaded with the waste liquid crystal polyester resin composition (W).

[0024] In the present invention, the waste liquid crystal polyester resin composition (W) (hereinafter, may be referred to as "the waste liquid crystal polyester resin composition (W) of the present invention") is a molded product of a liquid crystal polyester resin composition recovered from sprues and runners other than the product use when obtaining a molded product of the liquid crystal polyester resin composition, a non-standard product of the product, or a crushed product of waste of the product recovered from the market, which has received a heat history by at least one melt-kneading and subsequent molding, and is preferably pulverized to a pellet size suitable for melt-kneading, for example, a particle size of 2 to 5 mm, particularly 3 to 4 mm. As described above, since the waste liquid crystal polyester resin composition (W) has received a heat history through melt kneading and subsequent molding, the liquid crystal polyester resin (WA), plate-shaped filler (WB), and spherical filler (WC) in the waste liquid crystal polyester resin composition (W) have also all received a heat history through melt kneading and subsequent molding.

[0025] <Liquid crystal polyester resin (WA)> In the present invention, the liquid crystal polyester resin (WA) is a liquid crystal polyester resin or a liquid crystal polyester amide resin that is contained in the waste liquid crystal polyester resin composition (W) and forms an anisotropic molten phase called a thermotropic liquid crystal polymer. As the liquid crystal polyester resin, a liquid crystal polyester resin composed of repeating units derived from 4-hydroxybenzoic acid, 1,4-phenylenedicarboxylic acid, 1,3-phenylenedicarboxylic acid, and 4,4'-dihydroxybiphenyl is preferable from the viewpoint of heat resistance.

[0026] <Plate-shaped filler (WB)> In the present invention, the plate-shaped filler (WB) is a substantially plate-shaped filler contained in the waste liquid crystal polyester resin composition (W), and is usually an inorganic filler. The plate-shaped filler functions to improve mechanical properties such as the rigidity of the obtained molded product.

[0027] Examples of the plate-shaped inorganic filler (WB) include talc, mica, graphite, wollastonite, glass flakes, barium sulfate, calcium carbonate, etc., and one or more selected from these can be used. Among them, talc and / or mica are preferable, and talc is more preferable.

[0028] If the average particle size of the plate-shaped filler (WB) such as talc is too small, a sufficient reinforcing effect cannot be obtained, and if it is too large, the obtained molded product becomes brittle or the appearance is impaired. Therefore, 1 to 100 μm is preferable, and 3 to 50 μm is more preferable. Here, the average particle diameter of the plate-shaped filler (WB) and the unused plate-shaped filler (VB) described later is the median diameter measured by the laser diffraction method, but for commercially available products, catalog values can be adopted. Note that the particle diameter of the plate-shaped filler refers to the diameter of the part where the distance between two parallel plates is the largest when the plate-shaped filler is sandwiched between two parallel plates, and the average particle diameter represents the average value of the particle diameters of about 100 to 300 plate-shaped fillers.

[0029] <Spherical filler (WC)> In the present invention, the spherical filler (WC) is a substantially spherical filler contained in the waste liquid crystal polyester resin composition (W), and is usually an inorganic filler. In the present invention, the spherical filler does not necessarily have to be a perfect sphere, and may be an ellipsoid with a ratio of the major axis to the minor axis of 1 to 1.5. The spherical filler functions to improve the blister resistance and the like of the obtained molded product.

[0030] Examples of the spherical filler (WC) include glass beads, silica, alumina, etc., and one or more selected from these can be used. Among them, glass beads and / or silica are preferable, and glass beads are more preferable.

[0031] If the average particle diameter of the spherical filler (WC) such as glass beads is too small, a sufficient blister resistance effect cannot be obtained, and if it is too large, the obtained molded product becomes brittle or the appearance is impaired. Therefore, 3 to 80 μm is preferable, and 10 to 50 μm is more preferable. Here, the average particle diameter of the spherical filler (WC) and the unused spherical filler (VC) described later is the median diameter measured by the laser diffraction method, but for commercially available products, catalog values can be adopted. Note that the particle diameter of the spherical filler refers to the diameter of the part where the distance between two parallel plates is the largest when the spherical filler is sandwiched between two parallel plates, and the average particle diameter represents the average value of the particle diameters of about 100 to 300 spherical fillers.

[0032] <Content ratio of each component> The waste liquid crystal polyester resin composition (W) of the present invention contains 50 to 95% by mass of a liquid crystal polyester resin (WA), 2.5 to 30% by mass of a plate-like filler (WB), and 2.5 to 20% by mass of a spherical filler (WC).

[0033] If the content ratio of the liquid crystal polyester resin (WA) in the waste liquid crystal polyester resin composition (W) of the present invention is 50% by mass or more, it is excellent in the original characteristics of the liquid crystal polyester resin. If the content ratio of the liquid crystal polyester resin (WA) in the waste liquid crystal polyester resin composition (W) of the present invention is 95% by mass or less, a liquid crystal polyester resin composition excellent in rigidity, blister resistance, etc. can be obtained by ensuring the content ratios of the plate-like filler (WB) and the spherical filler (WC). The content ratio of the liquid crystal polyester resin (WA) in the waste liquid crystal polyester resin composition (W) of the present invention is preferably 50 to 85% by mass, more preferably 60 to 75% by mass.

[0034] If the content ratio of the plate-like filler (WB) in the waste liquid crystal polyester resin composition (W) of the present invention is 2.5% by mass or more, it is excellent in the reinforcing effect such as bending stress by the plate-like filler (WB). If the content ratio of the plate-like filler (WB) in the waste liquid crystal polyester resin composition (W) of the present invention is 30% by mass or less, a liquid crystal polyester resin composition excellent in the original characteristics of the liquid crystal polyester resin (WA) and the compounding effect of the spherical filler (WC) can be obtained by ensuring the content ratios of the liquid crystal polyester resin (WA) and the spherical filler (WC). The content ratio of the plate-like filler (WB) in the waste liquid crystal polyester resin composition (W) of the present invention is preferably 10 to 28% by mass, more preferably 16 to 24% by mass.

[0035] If the content ratio of the spherical filler (WC) in the waste liquid crystal polyester resin composition (W) of the present invention is 2.5% by mass or more, it is excellent in the effect of improving blister resistance by the spherical filler (WC). If the content ratio of the spherical filler (WC) in the waste liquid crystal polyester resin composition (W) of the present invention is 20% by mass or less, the content ratios of the liquid crystal polyester resin (WA) and the plate-like filler (WB) are ensured, and the liquid crystal polyester resin composition excellent in the original characteristics of the liquid crystal polyester resin and the compounding effect of the plate-like filler (WB) is obtained. The content ratio of the spherical filler (WC) in the waste liquid crystal polyester resin composition (W) of the present invention is preferably 4 to 16% by mass, more preferably 6 to 14% by mass.

[0036] The content ratio (mass ratio of the plate-like filler (WB) / spherical filler (WC)) of the plate-like filler (WB) and the spherical filler (WC) in the waste liquid crystal polyester resin composition (W) of the present invention is preferably 1.0 to 3.0, particularly preferably 1.5 to 2.5, from the viewpoint of obtaining a well-balanced compounding effect of these fillers.

[0037] From the viewpoint of the original characteristics of the liquid crystal polyester resin, the total content ratio of the liquid crystal polyester resin (WA), the plate-like filler (WB), and the spherical filler (WC) in the waste liquid crystal polyester resin composition (W) of the present invention is preferably 50% by mass or more, more preferably 80 to 100% by mass.

[0038] <Other components> The waste liquid crystal polyester resin composition (W) of the present invention may contain one or more selected from other additives other than the above liquid crystal polyester resin (WA), plate-like filler (WB), and spherical filler (WC), for example, mold release improvers such as higher fatty acids, higher fatty acid esters, higher fatty acid amides, higher fatty acid metal salts (where the higher fatty acid means those having 10 to 25 carbon atoms), polysiloxanes, and fluororesins; colorants such as dyes and pigments; antioxidants; heat stabilizers; ultraviolet absorbers; antistatic agents; surfactants; fillers other than the above-mentioned plate-like filler (WB) and spherical filler (WC) as long as the effects of the present invention are not impaired. However, fibrous fillers such as glass fibers are preferably not compounded because they may have an adverse effect on the fluidity, mechanical strength, appearance of the obtained molded product, etc. of the obtained recycled liquid crystal polyester resin composition.

[0039] When these other additives are contained, the content is usually 10 parts by mass or less, for example, 0.1 to 10 parts by mass, preferably 0.5 to 5 parts by mass, based on 100 parts by mass of the liquid crystal polyester resin (WA). When the content of these other additives exceeds 10 parts by mass, the moldability tends to decrease and the thermal stability tends to deteriorate.

[0040] Regarding those having an external lubricant effect such as higher fatty acids, higher fatty acid esters, higher fatty acid metal salts, and fluorocarbon surfactants, when using the waste liquid crystal polyester resin composition (W), they may be adhered to the surface of the pulverized product of the waste liquid crystal polyester resin composition (W).

[0041] Further, the waste liquid crystal polyester resin composition (W) of the present invention may further contain other resin components as long as the object of the present invention is not impaired. Examples of other resin components include thermoplastic resins such as polyamide, polyester, polyacetal, polyphenylene ether, polysulfone, polyethersulfone, polyetherimide, polyamideimide, and modified products thereof, and thermosetting resins such as phenol resin, epoxy resin, and polyimide resin.

[0042] Other resin components can be contained alone or in combination of two or more. When other resin components are contained, the content of other resin components is not particularly limited and can be appropriately determined. Preferably, the total content of other resin components with respect to 100 parts by mass of the liquid crystal polyester resin (WA) is 100 parts by mass or less, for example, 0.1 to 100 parts by mass, particularly 0.1 to 80 parts by mass.

[0043] [Unused liquid crystal polyester resin (VA)] In the present invention, the virgin liquid crystal polyester resin (also referred to as "non-recycled liquid crystal polyester resin") (VA) used in the production of the recycled liquid crystal polyester resin composition is a liquid crystal polyester resin or a liquid crystal polyester amide resin that forms an anisotropic molten phase called a thermotropic liquid crystal polymer, and is not subjected to a heat history by melt kneading or further molding like the liquid crystal polyester resin (WA).

[0044] As the liquid crystal polyester resin, a liquid crystal polyester resin composed of repeating units derived from 4-hydroxybenzoic acid, 1,4-phenylenedicarboxylic acid, 1,3-phenylenedicarboxylic acid, and 4,4'-dihydroxybiphenyl is preferable from the viewpoint of heat resistance.

[0045] The liquid crystal polyester resin (WA) and the virgin liquid crystal polyester resin (VA) may be composed of the same liquid crystal polyester resin or different liquid crystal polyester resins. However, from the viewpoints of compatibility, appearance of the molded product, etc., those composed of the same components (here, the same components mean that the monomers constituting the liquid crystal polyester resin are the same) are preferable, and those having the same monomer composition composed of the same components are more preferable.

[0046] [Virgin plate-shaped filler (VB)] In the present invention, the virgin plate-shaped filler (also referred to as "non-recycled plate-shaped filler") (VB) used in the production of the recycled liquid crystal polyester resin composition is usually an inorganic filler and has not been subjected to a heat history by melt kneading or further molding like the plate-shaped filler (WB). As described above, the plate-shaped filler functions to improve mechanical properties such as rigidity.

[0047] Examples of the plate-shaped inorganic filler (VB) include talc, mica, graphite, wollastonite, glass flake, barium sulfate, calcium carbonate, etc., and one or more selected from these can be used. Among them, talc and / or mica are preferable, and talc is more preferable. For the same reason as in the liquid crystal polyester resin, the unused plate-shaped filler (VB) is preferably composed of the same components as the plate-shaped filler (WB).

[0048] For the same reason as in the case of the plate-shaped filler (WB), the average particle size of the unused plate-shaped filler (VB) such as talc is preferably 1 to 100 μm, more preferably 3 to 50 μm.

[0049] The average particle size of the plate-shaped filler (WB) and the average particle size of the unused plate-shaped filler (VB) may be the same or different within the above ranges.

[0050] [Unused spherical filler (VC)] The unused spherical filler (VC) (also referred to as "non-recycled spherical filler") used in the production of the recycled liquid crystal polyester resin composition is usually an inorganic filler and has not undergone the heat history by melt kneading such as the spherical filler (WC), and further by molding. As described above, the spherical filler functions to improve blister resistance and the like.

[0051] Examples of the spherical inorganic filler (VC) include glass beads, silica, alumina, etc., and one or more selected from these can be used. Among them, from the viewpoint of improving the metering stability during injection molding of the liquid crystal polyester resin composition, glass beads and / or silica are preferable, and glass beads are more preferable.

[0052] The unused spherical filler (VC) is also preferably composed of the same components as the spherical filler (WC).

[0053] For the same reason as in the case of the spherical filler (WC), the average particle size of the unused spherical filler (VC) such as glass beads is preferably 3 to 80 μm, more preferably 10 to 50 μm.

[0054] The average particle size of the spherical filler (WC) and the average particle size of the unused spherical filler (VC) may be the same or different within the above ranges.

[0055] [Other components] In the recycled liquid crystal polyester resin composition of the present invention, within a range not impairing the effects of the present invention, other additives other than the waste liquid crystal polyester resin composition (W), unused liquid crystal polyester resin (VA), unused plate-shaped filler (VB), and unused spherical filler (VC), for example, higher fatty acids, higher fatty acid esters, higher fatty acid amides, higher fatty acid metal salts (where the higher fatty acid means those having 10 to 25 carbon atoms), release improvers such as polysiloxanes and fluororesins; colorants such as dyes and pigments; antioxidants; heat stabilizers; ultraviolet absorbers; antistatic agents; surfactants; fillers other than the unused plate-shaped filler (VB) and unused spherical filler (VC), etc. may be blended in combination of one or more selected therefrom. That is, these additives may be melt-kneaded together with the waste liquid crystal polyester resin composition (W), unused liquid crystal polyester resin (VA), unused plate-shaped filler (VB), and unused spherical filler (VC) during the production of the recycled liquid crystal polyester resin composition of the present invention. However, fibrous fillers such as glass fibers may, as described above, have an adverse effect on fluidity, mechanical strength, the appearance of the resulting molded product, etc. when the obtained recycled liquid crystal polyester resin composition is recycled again. Therefore, the content of the fibrous filler in the recycled liquid crystal polyester resin composition is preferably 1.0% by mass or less, more preferably 0.5% by mass or less, and even more preferably not blended.

[0056] When using these other additives, the blending amount is usually 10 parts by mass or less, for example, 0.1 to 10 parts by mass, preferably 0.5 to 5 parts by mass, based on 100 parts by mass in total of the liquid crystal polyester resin, that is, the liquid crystal polyester resin (WA) and the unused liquid crystal polyester resin (VA) in the recycled liquid crystal polyester resin composition. When the blending amount of these other additives exceeds 10 parts by mass, the molding processability tends to decrease and the thermal stability tends to deteriorate.

[0057] For those having an external lubricant effect such as higher fatty acids, higher fatty acid esters, higher fatty acid metal salts, fluorocarbon surfactants, etc., when molding the recycled liquid crystal polyester resin composition, they may be adhered to the surface of the pellets of the recycled liquid crystal polyester resin composition.

[0058] Further, in the recycled liquid crystal polyester resin composition of the present invention, other resin components may be further blended within a range not impairing the object of the present invention. That is, when manufacturing the recycled liquid crystal polyester resin composition of the present invention, other resin components may be melt-kneaded together with the waste liquid crystal polyester resin composition (W), unused liquid crystal polyester resin (VA), unused plate-like filler (VB), and unused spherical filler (VC).

[0059] Examples of other resin components include thermoplastic resins such as polyamide, polyester, polyacetal, polyphenylene ether, polysulfone, polyethersulfone, polyetherimide, polyamideimide, and modified products thereof, and thermosetting resins such as phenol resin, epoxy resin, and polyimide resin.

[0060] Other resin components can be blended alone or in combination of two or more. When blending other resin components, the blending amount is not particularly limited and may be appropriately determined according to the use and purpose of the recycled liquid crystal polyester resin composition. Typically, for the total 100 parts by mass of the liquid crystal polyester resin, that is, the liquid crystal polyester resin (WA) and the unused liquid crystal polyester resin (VA) in the recycled liquid crystal polyester resin composition, the total blending amount of other resin components is added in the range of 100 parts by mass or less, for example, 0.1 to 100 parts by mass, particularly 0.1 to 80 parts by mass.

[0061] [Contents of each component in the recycled liquid crystal polyester resin composition] In the present invention, the total content of the unused liquid crystal polyester resin (VA) and the liquid crystal polyester resin (WA) corresponding to all the liquid crystal polyester resins contained in the recycled liquid crystal polyester resin composition (hereinafter sometimes referred to as "(VA + WA)") is 50 to 95% by mass, preferably 55 to 90% by mass, and more preferably 65 to 80% by mass. If (VA + WA) is not less than the above lower limit, the properties as a liquid crystal polyester resin are excellent, and if it is not more than the above upper limit, the content of the filler can be ensured and a molded product excellent in mechanical properties and the like can be obtained.

[0062] In the present invention, the total content of the unused plate-like filler (VB) and the plate-like filler (WB) corresponding to all the plate-like fillers contained in the recycled liquid crystal polyester resin composition (hereinafter sometimes referred to as "(VB + WB)") is 2.5 to 30% by mass, preferably 5.5 to 27% by mass, and more preferably 7.5 to 25% by mass. If (VB + WB) is not less than the above lower limit, the reinforcing effect by the plate-like filler is excellent, and if it is not more than the above upper limit, the contents of the liquid crystal polyester resin and the spherical filler can be ensured and the respective compounding effects can be sufficiently obtained.

[0063] In the present invention, the total content of the unused spherical filler (VC) and the spherical filler (WC) corresponding to all the spherical fillers contained in the recycled liquid crystal polyester resin composition (hereinafter sometimes referred to as "(VC + WC)") is 2.5 to 20% by mass, preferably 4.5 to 18% by mass, and more preferably 7.5 to 15% by mass. If (VC + WC) is not less than the above lower limit, the effect of improving blister resistance by the spherical filler is excellent, and if it is not more than the above upper limit, the contents of the liquid crystal polyester resin and the plate-like filler can be ensured and the respective compounding effects can be sufficiently obtained.

[0064] In the present invention, the content of the waste liquid crystal polyester resin composition (W) contained in the recycled liquid crystal polyester resin composition is 50 to 85% by mass, preferably 55 to 80% by mass, and more preferably 60 to 75% by mass. If the content rate of the waste liquid crystal polyester resin composition (W) is at least the above lower limit, the recycling efficiency is excellent. If it is at most the above upper limit, the fluidity of the recycled liquid crystal polyester resin composition, the maintenance rate of mechanical strength, and the appearance such as suppression of blister generation in the obtained molded product are excellent. Even when the ratio of the waste liquid crystal polyester resin composition (W) in the recycled liquid crystal polyester resin composition is increased to 85% by mass, the maintenance rate of fluidity and the maintenance rate of mechanical strength are high, and also, it is a great effect of the present invention that a recycled liquid crystal polyester resin composition in which appearance defects such as blisters when the obtained molded product is heated are suppressed can be provided.

[0065] In the present invention, the mass ratio of the unused liquid crystal polyester resin (VA) to the total of the liquid crystal polyester resin (WA) and the unused liquid crystal polyester resin (VA) contained in the recycled liquid crystal polyester resin composition (hereinafter sometimes referred to as "VA / (WA + VA)") is preferably 0.15 or more, more preferably 0.2 or more. If VA / (WA + VA) is at least the above lower limit, it is preferable in terms of the quality of the obtained molded product. VA / (WA + VA) is preferably 0.5 or less from the viewpoint of recycling efficiency.

[0066] In the present invention, the mass ratio of the unused plate-like filler (VB) to the total of the plate-like filler (WB) and the unused plate-like filler (VB) contained in the recycled liquid crystal polyester resin composition (hereinafter sometimes referred to as "VB / (WB + VB)") is preferably 0.15 or more, more preferably 0.2 or more. If VB / (WB + VB) is at least the above lower limit, it is preferable in terms of the quality of the obtained molded product. VB / (WB + VB) is preferably 0.5 or less from the viewpoint of recycling efficiency.

[0067] In the present invention, the mass ratio of the unused spherical filler (VC) to the total of the spherical filler (WC) and the unused spherical filler (VC) contained in the recycled liquid crystal polyester resin composition (hereinafter sometimes referred to as "VC / (WC + VC)") is preferably 0.15 or more, and more preferably 0.2 or more. If VC / (WC + VC) is at least the above lower limit, it is preferable in terms of the quality of the obtained molded article. VC / (WC + VC) is preferably 0.5 or less from the viewpoint of recycling efficiency.

[0068] [Method for producing recycled liquid crystal polyester resin composition] The recycled liquid crystal polyester resin composition of the present invention is produced by melt-kneading the waste liquid crystal polyester resin composition (W) of the present invention, the unused liquid crystal polyester resin (VA), the unused plate-like filler (VB), and the unused spherical filler (VC) of the present invention, and other additives and resin components used as necessary so as to have the above-described component composition. At this time, there is no particular limitation on the mixing order of the respective components, and it is sufficient that the respective components are uniformly melt-kneaded.

[0069] For melt-kneading the respective components, a Banbury mixer, a kneader, a single-screw or twin-screw extruder, etc. are used. The melt-kneading can usually be carried out under temperature conditions in the vicinity of the crystal melting temperature of the liquid crystal polyester resin to the crystal melting temperature + 20°C.

[0070] In the present invention, it is an extremely important constituent requirement that the unused liquid crystal polyester resin (VA), the unused plate-like filler (VB), and the unused spherical filler (VC) as raw materials of the liquid crystal polyester resin composition are mixed with the crushed material of the waste liquid crystal polyester resin composition (W) and melt-kneaded. Conventionally, when recycling waste materials such as various resin molded articles, generally, a mixture of pellets of a new resin composition (unused resin composition) and the crushed material of the waste resin composition is reused for molding without melt-kneading. However, since the crushed material of the waste resin composition to be mixed with the pellets of the new resin composition (unused resin composition) generally has non-uniform shapes and sizes, when the mixing amount exceeds about 50%, the metering stability during molding is likely to be impaired, and also, appearance defects such as blisters and poor surface smoothness increase when the obtained molded product is heated, and the object of the present invention cannot be achieved by the conventional methods.

[0071] In the present invention, by melt-kneading an unused liquid crystal polyester resin (VA), an unused plate-shaped filler (VB), and an unused spherical filler (VC), which are raw materials of the liquid crystal polyester resin composition, with the crushed material of the waste liquid crystal polyester resin composition (W), even when the kneading amount of the crushed material of the waste liquid crystal polyester resin composition (W) is large, and also when the melt-kneaded product is further pelletized, the stability and uniformity of the shape and size of the obtained pellets are excellent, the maintenance rate of fluidity and the maintenance rate of mechanical strength are high, and the present invention can solve the problem of providing a recycled liquid crystal polyester resin composition in which appearance defects such as blisters and poor surface smoothness are suppressed when the obtained molded product is heated.

[0072] For example, Patent Document 8 mentioned above describes a reinforced LCP composition using talc and glass beads as fillers. However, when attempting to recycle this waste reinforced LCP composition, generally, since the crushed material of the waste reinforced LCP composition and the pellets of the new reinforced LCP composition are mixed and molded, as described above, the shapes and sizes of the crushed material and the pellets are non-uniform, so the configuration of the present invention is not reached, and thus the effects of the present invention cannot be obtained. Conventionally, the reason for mixing (dry blending) and molding the crushed material of the waste reinforced LCP composition and the pellets of the new reinforced LCP composition in this way is to prevent quality degradation by minimizing the thermal history applied to the pellets and the crushed material. On the other hand, according to the specific component composition of the recycled liquid crystal polyester resin composition of the present invention, it is possible to provide a high-quality recycled liquid crystal polyester resin composition by suppressing quality degradation due to thermal deterioration during extrusion kneading.

[0073] That is, in the present invention, a significant feature is that, contrary to such conventional recycling methods, the crushed waste liquid crystal polyester resin composition (W) is melt-kneaded without pelletizing the unused liquid crystal polyester resin (VA), the unused plate-shaped filler (VB), and the unused spherical filler (VC).

[0074] [Molding of the recycled liquid crystal polyester resin composition] The recycled liquid crystal polyester resin composition of the present invention thus obtained has a high maintenance rate of fluidity and a high maintenance rate of the mechanical strength of the molded article obtained by molding it, and appearance defects such as blisters are suppressed when the obtained molded article is heated. It is processed into molded articles, films, sheets, non-woven fabrics, etc. by known molding methods using an injection molding machine, an extruder, etc.

[0075] [Maintenance rate of flexural stress of the recycled liquid crystal polyester resin composition] By adopting the specific component composition of the present invention, the recycled liquid crystal polyester resin composition of the present invention can preferably have a maintenance rate of flexural stress obtained by the following formula of 90% or more. This maintenance rate of flexural stress is more preferably 95% or more, and particularly preferably 98% or more. Maintenance rate of flexural stress (%) = (S5 / S0) × 100 However, S5 and S0 are as follows. S0: Flexural stress (MPa) measured in accordance with ISO 178 for the recycled liquid crystal polyester resin composition using the waste liquid crystal polyester resin composition (W) before regeneration as the waste liquid crystal polyester resin composition (W). S5: Flexural stress (MPa) measured in accordance with ISO 178 for the recycled liquid crystal polyester resin composition obtained using the waste liquid crystal polyester resin composition (W) after being recycled 5 times as the waste liquid crystal polyester resin composition (W). That is, the recycled liquid crystal polyester resin composition of the present invention can suppress the decrease in bending stress when recycling is repeated. As described above, even for the recycled liquid crystal polyester resin composition that has been recycled five times, the bending stress can be maintained at a high level. The specific method for measuring the bending stress is as shown in the Examples section below.

[0076] [Use] The recycled liquid crystal polyester resin composition of the present invention is excellent in flow stability during recycling and is less likely to cause appearance defects such as blisters at high temperatures. Therefore, it is preferably used as a molding material for switches, relays, connectors, chips, optical pickups, inverter transformers, coil bobbins, antennas, substrates, etc. that are processed at high temperatures such as reflow.

Examples

[0077] Hereinafter, the present invention will be described more specifically with reference to Examples. However, the present invention is not limited to the following Examples and can be arbitrarily modified and implemented without departing from the gist of the present invention.

[0078] [Raw Materials] Hereinafter, the raw materials used in Examples and Comparative Examples are shown.

[0079] <Liquid Crystal Polyester Resin> Unused liquid crystal polyester resin (VA) Manufactured by L20 NANJING GINGYAN Tm (melting point): 340 - 346 °C Liquid crystal polyester resin (WA) contained in the waste liquid crystal polyester resin composition (W) Manufactured by L20 NANJING GINGYAN Tm (melting point): 340 - 346 °C

[0080] <Plate - like Filler> Unused plate - like filler (VB) Talc manufactured by Hayashi Kasei Co., Ltd., 5000S Average particle size: 4.75 μm Plate-shaped filler (WB) contained in waste liquid crystal polyester resin composition (W) Talc manufactured by Hayashi Kasei Co., Ltd., 5000S Average particle size: 4.75 μm

[0081] <Spherical filler> Unused spherical filler (VC) Glass beads manufactured by Potters Ballotini Co., Ltd., EGB731 Average particle size: 20 μm Spherical filler (WC) contained in waste liquid crystal polyester resin composition (W) Glass beads manufactured by Potters Ballotini Co., Ltd., EGB731 Average particle size: 20 μm

[0082] <Fibrous filler> Unused fibrous filler (VX) Glass fiber manufactured by Nippon Electric Glass Co., Ltd., ECS03 T-786H Average diameter: 10 μm Fibrous filler (WX) contained in waste liquid crystal polyester resin composition (W) Glass fiber manufactured by Nippon Electric Glass Co., Ltd., ECS03 T-786H Average diameter: 10 μm

[0083] [Evaluation method] The evaluation methods for various physical properties and qualities in the following examples and comparative examples are as follows.

[0084] <Bending stress> Using the pellets of the resin composition, a test piece of ISO multipurpose dumbbell (1A) prepared under the molding conditions of a molding temperature of 350 °C, a mold temperature of 90 °C, and an injection speed of 45 mm / second with a molding machine J75EII (manufactured by Japan Steel Works, Ltd.) was used, and the measurement was carried out in accordance with ISO178.

[0085] <Flowability> The melt flow rate (Q value) of the pellets of the resin composition was evaluated by the method described in Appendix C of JIS K7210. For the measurement of the melt flow rate (Q value), a flow tester CFT-500EX manufactured by Shimadzu Corporation was used. Specifically, a die with a hole diameter of 0.3 mm and a length of 1 mm was used, and the test temperature was 350 °C, the test force was 160 kg / cm 2 , and the amount of molten resin discharged under the conditions of a preheating time of 420 seconds was used for the measurement of the melt flow rate (×0.01 cc / sec).

[0086] <Blister> The pellets of the resin composition were dried at 140 °C for 8 hours, and using the dried pellets, with an injection molding machine C, Mobile-0813 (manufactured by Epson Technoform Co., Ltd., plunger type), at a cylinder temperature of 390 °C, a mold temperature of 110 °C, an injection / cooling time of 20 seconds, and an injection speed of 30 mm / sec, a square plate (film gate) with a thickness of 25 mm × 25 mm × 3 mm was injection molded. The test piece obtained by injection molding was left standing in a hot air oven at 285 °C for 5 minutes. Then, the test piece was taken out from the hot air oven, and the presence (number) of blisters (visible bulges) was examined.

[0087] <Appearance> The surface state of the test piece prepared above was visually confirmed, and the smoothness was evaluated as good (○) or poor (×).

[0088] [Example 1] 70% by mass of a liquid crystal polyester resin (VA), 20% by mass of a plate-shaped filler (VB), and 10% by mass of a spherical filler (VC) were melt-kneaded at 350 °C using a twin-screw extruder (manufactured by Technovel Corporation, KZW15TW-15 / 30MG-NH(-700)) to obtain virgin pellets. Regarding the obtained virgin pellets, using a molding machine J75EII (manufactured by Nippon Steel Works, Ltd.), the sprue and runner of an ISO multi-purpose dumbbell (1A) produced under the molding conditions of a molding temperature of 350 °C and a mold temperature of 90 °C were ground into pellets of a size of approximately 3 mm (the same hereinafter) using a grinder to obtain a ground product of a waste liquid crystal polyester resin composition (W-1).

[0089] 60% by mass of the ground product of the obtained waste liquid crystal polyester resin composition (W-1) and 40% by mass of an unused liquid crystal polyester resin composition composed of 70% by mass of a liquid crystal polyester resin (VA), 20% by mass of a plate-like filler (VB), and 10% by mass of a spherical filler (VC) were melt-kneaded at 350 °C using a twin-screw extruder and pelletized to obtain a first recycled liquid crystal polyester resin composition (L-1).

[0090] Regarding the pellets of the first recycled liquid crystal polyester resin composition (L-1), through the same molding process and grinding process as the virgin pellets, a ground product of the waste liquid crystal polyester resin composition (W-2) was obtained. 60% by mass of the ground product of the obtained waste liquid crystal polyester resin composition (W-2) and 40% by mass of an unused liquid crystal polyester resin composition composed of 70% by mass of a liquid crystal polyester resin (VA), 20% by mass of a plate-like filler (VB), and 10% by mass of a spherical filler (VC) were melt-kneaded at 350 °C using a twin-screw extruder and pelletized to obtain a second recycled liquid crystal polyester resin composition (L-2).

[0091] The same molding process, grinding, and melt extrusion as for the pellets of the first recycled liquid crystal polyester resin composition (L-1) described above were also carried out for the second recycled liquid crystal polyester resin composition (L-2) to obtain a third recycled liquid crystal polyester resin composition (L-3).

[0092] The above-described molding process, grinding, and melt extrusion were also carried out for the third and fourth recycled liquid crystal polyester resin compositions (L-3) and (L-4) to obtain a fifth recycled liquid crystal polyester resin composition (L-5).

[0093] [Example 2] 70% by mass of a liquid crystal polyester resin (VA), 20% by mass of a plate-like filler (VB), and 10% by mass of a spherical filler (VC) were melt-kneaded at 350 °C using the same twin-screw extruder as used in Example 1 to obtain virgin pellets. Regarding the obtained virgin pellets, the sprue and runner of the ISO multipurpose dumbbell (1A) produced under the same molding conditions as in Example 1, with a molding temperature of 350 °C and a mold temperature of 90 °C, were ground into pellet size using a grinder to obtain a ground product of the waste liquid crystal polyester resin composition (W-1).

[0094] 80% by mass of the ground product of the obtained waste liquid crystal polyester resin composition (W-1) and 20% by mass of an unused liquid crystal polyester resin composition composed of 70% by mass of a liquid crystal polyester resin (VA), 20% by mass of a plate-shaped filler (VB), and 10% by mass of a spherical filler (VC) were melt-kneaded at 350 °C using a twin-screw extruder and pelletized to obtain the first recycled liquid crystal polyester resin composition (L-1).

[0095] Regarding the pellets of the first recycled liquid crystal polyester resin composition (L-1), through the same molding process and grinding process as described above, a ground product of the waste liquid crystal polyester resin composition (W-2) was obtained. 80% by mass of the ground product of the obtained waste liquid crystal polyester resin composition (W-2) and 20% by mass of an unused liquid crystal polyester resin composition composed of 70% by mass of a liquid crystal polyester resin (VA), 20% by mass of a plate-shaped filler (VB), and 10% by mass of a spherical filler (VC) were melt-kneaded at 350 °C using a twin-screw extruder and pelletized to obtain the second recycled liquid crystal polyester resin composition (L-2).

[0096] The same molding process, grinding, and melt extrusion as those of the above-described first recycled liquid crystal polyester resin composition (L-1) pellets were also performed on the second recycled liquid crystal polyester resin composition (L-2) to obtain the third recycled liquid crystal polyester resin composition (L-3).

[0097] The above-described molding process, grinding, and melt extrusion were also performed on the third and fourth recycled liquid crystal polyester resin compositions (L-3) and (L-4) to obtain the fifth recycled liquid crystal polyester resin composition (L-5).

[0098] [Comparative Example 1] 70% by mass of liquid crystal polyester resin (VA), 20% by mass of plate-shaped filler (VB), and 10% by mass of spherical filler (VC) were melt-kneaded at 350 °C using the same twin-screw extruder as in Example 1 to obtain virgin pellets. Regarding the obtained virgin pellets, the sprue and runner of an ISO multipurpose dumbbell (1A) produced under the molding conditions of a molding temperature of 350 °C and a mold temperature of 90 °C using the same molding machine as in Example 1 were ground into pellet size using a grinder to obtain a ground material of waste liquid crystal polyester resin composition (W-1).

[0099] 90% by mass of the ground material of the obtained waste liquid crystal polyester resin composition (W-1) and 10% by mass of an unused liquid crystal polyester resin composition composed of 70% by mass of liquid crystal polyester resin (VA), 20% by mass of plate-shaped filler (VB), and 10% by mass of spherical filler (VC) were melt-kneaded at 350 °C using a twin-screw extruder and pelletized to obtain the first recycled liquid crystal polyester resin composition (L-1).

[0100] Regarding the pellets of the first recycled liquid crystal polyester resin composition (L-1), through the same molding process and grinding process as described above, a ground material of waste liquid crystal polyester resin composition (W-2) was obtained. 90% by mass of the ground material of the obtained waste liquid crystal polyester resin composition (W-2) and 10% by mass of an unused liquid crystal polyester resin composition composed of 70% by mass of liquid crystal polyester resin (VA), 20% by mass of plate-shaped filler (VB), and 10% by mass of spherical filler (VC) were melt-kneaded at 350 °C using a twin-screw extruder and pelletized to obtain the second recycled liquid crystal polyester resin composition (L-2).

[0101] The above-described molding process, grinding, and melt extrusion were also performed on the third and fourth recycled liquid crystal polyester resin compositions (L-3) and (L-4) to obtain the fifth recycled liquid crystal polyester resin composition (L-5).

[0102] The above-described molding process, grinding, and melt extrusion were also performed on the third and fourth recycled liquid crystal polyester resin compositions (L-3) and (L-4) to obtain the fifth recycled liquid crystal polyester resin composition (L-5).

[0103] [Comparative Example 2] 70% by mass of liquid crystal polyester resin (VA), 20% by mass of plate-shaped filler (VB), and 10% by mass of fibrous filler (VX) were melt-kneaded at 350 °C using the same twin-screw extruder as in Example 1 to obtain virgin pellets. Regarding the obtained virgin pellets, the sprue and runner of ISO multipurpose dumbbell (1A) produced under the molding conditions of a molding temperature of 350 °C and a mold temperature of 90 °C using the same molding machine as in Example 1 were pulverized to the pellet size using a pulverizer to obtain a pulverized product of waste liquid crystal polyester resin composition (W-1).

[0104] 60% by mass of the pulverized product of the obtained waste liquid crystal polyester resin composition (W-1) and 40% by mass of an unused liquid crystal polyester resin composition composed of 70% by mass of liquid crystal polyester resin (VA), 20% by mass of plate-shaped filler (VB), and 10% by mass of fibrous filler (VX) were melt-kneaded at 350 °C using a twin-screw extruder and pelletized to obtain the first recycled liquid crystal polyester resin composition (L-1).

[0105] Regarding the pellets of the first recycled liquid crystal polyester resin composition (L-1), through the same molding process and pulverization process as described above, a pulverized product of waste liquid crystal polyester resin composition (W-2) was obtained. 60% by mass of the pulverized product of the obtained waste liquid crystal polyester resin composition (W-2) and 60% by mass of an unused liquid crystal polyester resin composition composed of 70% by mass of liquid crystal polyester resin (VA), 20% by mass of plate-shaped filler (VB), and 10% by mass of fibrous filler (VX) were melt-kneaded at 350 °C using a twin-screw extruder and pelletized to obtain the second recycled liquid crystal polyester resin composition (L-2).

[0106] The same molding process, pulverization, and melt extrusion as for the pellets of the first recycled liquid crystal polyester resin composition (L-1) described above were also performed on the second recycled liquid crystal polyester resin composition (L-2) to obtain the third recycled liquid crystal polyester resin composition (L-3).

[0107] The above-mentioned molding, pulverization, and melt extrusion were also performed on the third and fourth recycled liquid crystal polyester resin compositions (L-3) and (L-4) to obtain the fifth recycled liquid crystal polyester resin composition (L-5).

[0108] For each of the virgin pellets of Examples 1 to 2 and Comparative Examples 1 to 2, the retention rate of flexural stress and the change rate of fluidity of the fifth recycled liquid crystal polyester resin composition (L-5), and the number of blisters generated and the appearance of the fifth recycled liquid crystal polyester resin composition (L-5) were evaluated. The results are shown in Table 1.

[0109]

Table 1

[0110] From Table 1, it can be seen that the recycled liquid crystal polyester resin composition of the present invention has a high retention rate of fluidity and mechanical strength, excellent appearance of the molded product, and suppression of blister generation during heating even when repeated recycling is performed multiple times. On the other hand, in Comparative Example 1, since the amount of the waste liquid crystal polyester resin composition (W) used is large, the change rate of fluidity is particularly large, and the blister generation rate during heating is also high. In Comparative Example 2, since fibrous fillers (WX) and (VX) were used instead of the spherical fillers (WC) and (VC), the retention rate of mechanical strength is low, and the change rate of fluidity is also large. Moreover, it is inferior in terms of the appearance of the molded product and the blister generation rate during heating.

Claims

1. A recycled liquid crystal polyester resin composition obtained by melt-kneading a waste liquid crystal polyester resin composition (W), an unused liquid crystal polyester resin (VA), an unused plate-shaped filler (VB), and an unused spherical filler (VC), wherein the waste liquid crystal polyester resin composition (W) is a liquid crystal polyester resin composition containing 50 to 95% by mass of a liquid crystal polyester resin (WA), 2.5 to 30% by mass of a plate-shaped filler (WB), and 2.5 to 20% by mass of a spherical filler (WC), the total content of the unused liquid crystal polyester resin (VA) and the liquid crystal polyester resin (WA) contained in the recycled liquid crystal polyester resin composition is 50 to 95% by mass, the total content of the unused plate-shaped filler (VB) and the plate-shaped filler (WB) contained in the recycled liquid crystal polyester resin composition is 2.5 to 30% by mass, the total content of the unused spherical filler (VC) and the spherical filler (WC) contained in the recycled liquid crystal polyester resin composition is 2.5 to 20% by mass, and the content of the waste liquid crystal polyester resin composition (W) contained in the recycled liquid crystal polyester resin composition is 50 to 85% by mass. A recycled liquid crystal polyester resin composition characterized by the above.

2. The recycled liquid crystal polyester resin composition according to claim 1, wherein the unused plate-shaped filler (VB) is talc.

3. The recycled liquid crystal polyester resin composition according to claim 1 or 2, wherein the plate-shaped filler (WB) is talc.

4. The recycled liquid crystal polyester resin composition according to claim 1 or 2, wherein the average particle diameter of the unused plate-shaped filler (VB) and the plate-shaped filler (WB) is 1 to 100 μm.

5. The recycled liquid crystal polyester resin composition according to claim 1 or 2, wherein the unused spherical filler (VC) is glass beads.

6. The recycled liquid crystal polyester resin composition according to claim 1 or 2, wherein the spherical filler (WC) is glass beads.

7. The recycled liquid crystal polyester resin composition according to claim 1 or 2, wherein the average particle diameters of the unused spherical filler (VC) and the spherical filler (WC) are 3 to 80 μm.

8. The recycled liquid crystal polyester resin composition according to claim 1 or 2, wherein the retention rate of the flexural stress obtained by the following formula is 90% or more. Retention rate of flexural stress (%) = (S ５ / S ０ ) × 100 However, S ５ , S ０ are as follows. S ０ : The flexural stress (MPa) measured in accordance with ISO 178 for the recycled liquid crystal polyester resin composition using the unregenerated waste liquid crystal polyester resin composition (W) as the waste liquid crystal polyester resin composition (W). S ５ : The flexural stress (MPa) measured in accordance with ISO 178 for the recycled liquid crystal polyester resin composition obtained using the waste liquid crystal polyester resin composition (W) that has been recycled five times as the waste liquid crystal polyester resin composition (W).

9. A method for producing a recycled liquid crystal polyester resin composition by melt-kneading a waste liquid crystal polyester resin composition (W), an unused liquid crystal polyester resin (VA), an unused plate-shaped filler (VB), and an unused spherical filler (VC), The waste liquid crystal polyester resin composition (W) is a liquid crystal polyester resin composition containing 50 to 95% by mass of a liquid crystal polyester resin (WA), 2.5 to 30% by mass of a plate-shaped filler (WB), and 2.5 to 20% by mass of a spherical filler (WC), The unused liquid crystal polyester resin (VA) is used so that the total content of the unused liquid crystal polyester resin (VA) and the liquid crystal polyester resin (WA) contained in the recycled liquid crystal polyester resin composition is 50 to 95% by mass. The unused plate-like filler (VB) is used such that the total content of the unused plate-like filler (VB) and the plate-like filler (WB) contained in the recycled liquid crystal polyester resin composition is 2.5 to 30% by mass. The unused spherical filler (VC) is used such that the total content of the unused spherical filler (VC) and the spherical filler (WC) contained in the recycled liquid crystal polyester resin composition is 2.5 to 20% by mass, and The waste liquid crystal polyester resin composition (W) is used such that the content of the waste liquid crystal polyester resin composition (W) contained in the recycled liquid crystal polyester resin composition is 50 to 85% by mass. A method for producing a recycled liquid crystal polyester resin composition, characterized by the above.

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