Liquid crystal resin composition for fan impeller and fan impeller using the same

Abstract

The present application aims to provide a liquid crystalline resin composition for a fan impeller, which is excellent in vibration damping characteristics and fluidity, can be favorably formed into a fan impeller in which noise is suppressed, a fan impeller formed from the aforementioned composition, and a fan provided with the aforementioned fan impeller. The present application is achieved by a liquid crystalline resin composition for a fan impeller, which comprises (A) a specific liquid crystalline resin and (B) a fibrous filler, the content of the aforementioned (B) fibrous filler being 5 to 40 mass% relative to the entire aforementioned liquid crystalline resin composition, and the loss coefficient at a temperature of 23°C and a frequency of 10,000 Hz measured in accordance with JIS G0602 being 0.05 or more.

Description

Technical Field

[0001] This invention relates to a liquid crystal resin composition for a fan impeller and a fan impeller using the same. Background Technology

[0002] Liquid crystal resins, represented by liquid crystal polyester resins, have a good balance of excellent heat resistance, chemical resistance, electrical properties, and excellent dimensional stability, and are therefore widely used in high-performance engineering plastics.

[0003] However, fans are used for cooling electronic devices by forcing the flow of fluids such as air through convection (e.g., Patent Document 1). A fan typically has multiple blades and consists of a fan impeller that generates fluid flow through rotation, a motor that rotates the fan impeller, and a housing that houses the fan impeller and motor. Conventionally, polyamides and polybutylene terephthalate have been used as resins for the fan impeller and housing.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 2005-039253 Summary of the Invention

[0007] The problem the invention aims to solve

[0008] In recent years, with the advent of 5G services, which enable ultra-high speed, ultra-low latency, and multiple simultaneous connections, the increasing heat generated by the high functionality and speed of electronic devices has led to a growing importance of cooling systems. To improve the cooling efficiency of cooling fans, the following strategies have been considered: reducing the thickness of the fan impeller blades (thin-wall construction) and increasing the number of blades; and increasing the fan's rotation speed compared to previous models.

[0009] However, when conventional resins are used in fan impellers, the following problems may occur if the blades are made thin-walled: the resin composition has low flowability and cannot be well molded; and vibration-induced noise occurs when rotating at high speeds.

[0010] The present invention was made in view of this situation, and its object is to provide a liquid crystal resin composition for a fan impeller with excellent vibration damping characteristics and flowability, which can be well molded into a fan impeller with suppressed noise, a fan impeller formed from the aforementioned composition, and a fan having the aforementioned fan impeller.

[0011] Solution for solving the problem

[0012] The inventors have studied fan impeller materials that replace conventional resins and found that using a liquid crystal resin containing a specified amount of a specific structural unit can yield particularly excellent flowability and vibration damping characteristics. Furthermore, they discovered that the aforementioned problems can be solved by creating a liquid crystal resin composition that combines the above-mentioned liquid crystal resin with a specified amount of fibrous filler, and whose loss coefficient, measured at a specified temperature and frequency, falls within a specified range. Specifically, the present invention provides the following.

[0013] (1) A liquid crystal resin composition for use in a fan impeller, comprising (A) a liquid crystal resin and (B) a fibrous filler.

[0014] The aforementioned liquid crystal resin (A) is a fully aromatic polyester that exhibits optical anisotropy when melted, containing the following structural units (I), (III), (IV) and (V), and may or may not contain the following structural unit (II).

[0015] The content of structural unit (I) is 35–75 mol% relative to all structural units.

[0016] The content of structural unit (II) is 0–8 mol% relative to all structural units.

[0017] The content of structural unit (III) is 4.5–30.5 mol% relative to all structural units.

[0018] The content of structural unit (IV) is 2–8 mol% relative to all structural units.

[0019] The content of structural unit (V) is 12.5–32.5 mol% relative to all structural units.

[0020] The total content of structural units (I) to (V) relative to all structural units is 100 mol%.

[0021] The content of the aforementioned fibrous filler (B) is 5-40% by mass relative to the overall liquid crystal resin composition.

[0022] According to JIS G0602, the loss coefficient at a temperature of 23℃ and a frequency of 10000Hz is above 0.05.

[0023] (I)

[0024] (II)

[0025] (III)

[0026] (IV)

[0027] (v)

[0028] (2) The liquid crystal resin composition according to (1), wherein the aforementioned liquid crystal resin (A) is a fully aromatic polyester exhibiting optical anisotropy when melted, and is composed of structural units (I), (II), (III), (IV) and (V).

[0029] The content of structural unit (I) is 35–75 mol% relative to all structural units.

[0030] The content of structural unit (II) is 2–8 mol% relative to all structural units.

[0031] The content of structural unit (III) is 4.5–30.5 mol% relative to all structural units.

[0032] The content of structural unit (IV) is 2–8 mol% relative to all structural units.

[0033] The content of structural unit (V) is 12.5–32.5 mol% relative to all structural units.

[0034] The total content of structural units (I) to (V) relative to all structural units is 100 mol%.

[0035] The content of the aforementioned (B) fibrous filler is 5 to 30% by mass relative to the overall liquid crystal resin composition.

[0036] (3) The liquid crystal resin composition according to (1) or (2), wherein the aforementioned fibrous filler (B) is glass fiber and / or carbon fiber.

[0037] (4) A fan impeller formed from any one of (1) to (3) liquid crystal resin composition.

[0038] (5) The fan impeller according to (4) is a centrifugal fan impeller with a blade length L (mm) to blade thickness t (mm) ratio L / t of 50 or more.

[0039] (6) A fan having the fan impeller described in (4) or (5).

[0040] The effects of the invention

[0041] According to the present invention, a liquid crystal resin composition for a fan impeller with excellent vibration damping characteristics and flowability, capable of being well molded into a fan impeller with suppressed noise, a fan impeller formed from the aforementioned composition, and a fan having the aforementioned fan impeller can be provided. Attached Figure Description

[0042] Figure 1 This is a perspective view of an axial fan in an embodiment of the fan of the present invention.

[0043] Figure 2 This is a perspective view of a centrifugal fan in an embodiment of the fan of the present invention.

[0044] Figure 3 The images show a front view and a side view of the fan impeller of the centrifugal fan fabricated in the embodiment. Detailed Implementation

[0045] The embodiments of the present invention will be described in detail below.

[0046] <Liquid Crystal Resin Composition for Fan Impellers>

[0047] The liquid crystal resin composition for fan impellers of the present invention comprises a specific liquid crystal resin and a predetermined amount of fibrous filler, and has a loss coefficient of 0.05 or higher. By setting the loss coefficient to 0.05 or higher, the liquid crystal resin composition of the present invention exhibits excellent vibration damping characteristics and can provide a fan impeller with suppressed noise. The loss coefficient is preferably 0.055 or higher, more preferably 0.06 or higher. The upper limit of the loss coefficient is not particularly limited, and for example, it can be 0.08.

[0048] In this specification, the loss factor is the value measured according to JIS G0602 at a temperature of 23°C and a frequency of 10000Hz.

[0049] [(A) Liquid crystal resin]

[0050] The liquid crystal resin composition of the present invention contains the above-mentioned fully aromatic polyester, i.e., a liquid crystal resin. The above-mentioned fully aromatic polyester exhibits particularly excellent flowability and vibration damping properties, and can be well molded into a fan impeller with suppressed noise. The liquid crystal resin can be used alone or in combination of two or more types.

[0051] The fully aromatic polyester of the present invention contains the following structural units (I), (III), (IV) and (V), and may or may not contain the following structural unit (II).

[0052] (I)

[0053] (II)

[0054] (III)

[0055] (IV)

[0056] (v)

[0057] Structural unit (I) is derived from 4-hydroxybenzoic acid (hereinafter also referred to as "HBA"). The fully aromatic polyester of the present invention contains 35 to 75 mol% of structural unit (I) relative to all structural units. If the content of structural unit (I) is less than 35 mol% or greater than 75 mol%, at least one of the vibration damping characteristics and flowability tends to become insufficient. From the viewpoint of balancing vibration damping characteristics and flowability, the content of structural unit (I) is preferably 40 to 65 mol%, more preferably 44 to 55 mol%.

[0058] Structural unit (II) is derived from 6-hydroxy-2-naphthoic acid (hereinafter also referred to as "HNA"). The fully aromatic polyester of the present invention contains 0 to 8 mol% of structural unit (II) relative to all structural units; in other words, it contains no structural unit (II) or contains more than 0 mol% and less than 8 mol% of structural unit (II) relative to all structural units. If the content of structural unit (II) is greater than 8 mol%, at least one of the vibration damping characteristics and flowability tends to become insufficient. From the viewpoint of balancing vibration damping characteristics and flowability, the content of structural unit (II) is preferably 2 to 8 mol%, more preferably 2 to 6 mol%.

[0059] Structural unit (III) is derived from 1,4-methylenedicarboxylic acid (hereinafter also referred to as "TA"). The fully aromatic polyester of the present invention contains 4.5 to 30.5 mol% of structural unit (III) relative to all structural units. If the content of structural unit (III) is less than 4.5 mol% or greater than 30.5 mol%, at least one of the vibration damping characteristics and flowability tends to become insufficient. From the viewpoint of balancing vibration damping characteristics and flowability, the content of structural unit (III) is preferably 11 to 27 mol%, more preferably 16 to 24 mol%.

[0060] The structural unit (IV) is derived from 1,3-methylenedicarboxylic acid (hereinafter also referred to as "IA"). The fully aromatic polyester of the present invention contains 2 to 8 mol% of structural unit (IV) relative to all structural units. If the content of structural unit (IV) is less than 2 mol% or more than 8 mol%, at least one of the vibration damping characteristics and flowability tends to become insufficient. From the viewpoint of balancing vibration damping characteristics and flowability, the content of structural unit (IV) is preferably 2 to 7 mol%, more preferably 2.5 to 5 mol%.

[0061] The structural unit (V) is derived from 4,4'-dihydroxybiphenyl (hereinafter also referred to as "BP"). The fully aromatic polyester of the present invention contains 12.5 to 32.5 mol% of structural unit (V) relative to all structural units. If the content of structural unit (V) is less than 12.5 mol% or greater than 32.5 mol%, at least one of the vibration damping characteristics and flowability tends to become insufficient. From the viewpoint of balancing vibration damping characteristics and flowability, the content of structural unit (V) is preferably 17 to 30 mol%, more preferably 21 to 28 mol%.

[0062] As described above, relative to all structural units, the fully aromatic polyester of the present invention contains specific amounts of specific structural units (I) to (V), thus achieving particularly excellent vibration damping characteristics and flowability. It should be noted that, relative to all structural units, the fully aromatic polyester of the present invention contains a total of 100 mol% of structural units (I) to (V).

[0063] Next, the method for manufacturing the fully aromatic polyester of the present invention will be described. The fully aromatic polyester of the present invention is polymerized using direct polymerization, transesterification, or other methods. During polymerization, melt polymerization, solution polymerization, slurry polymerization, solid-state polymerization, or a combination of two or more thereof are used, with melt polymerization or a combination of melt polymerization and solid-state polymerization being preferred.

[0064] In this invention, monomers whose ends are activated by acylation agents or acyl chloride derivatives can be used during polymerization. Examples of acylation agents include fatty acid anhydrides such as acetic anhydride.

[0065] These polymerizations can use a variety of catalysts. Representative catalysts include metal salt catalysts such as potassium acetate, magnesium acetate, stannous acetate, tetrabutyl titanate, lead acetate, sodium acetate, antimony trioxide, and tris(2,4-pentanedione)cobalt(III), as well as organic compound catalysts such as 1-methylimidazole and 4-dimethylaminopyridine.

[0066] For example, reaction conditions include a reaction temperature of 200–380°C and a final pressure of 0.1–760 Torr (i.e., 13–101,080 Pa). In particular, for molten reactions, reaction temperatures are typically 260–380°C, preferably 300–360°C, and final pressures are typically 1–100 Torr (i.e., 133–13,300 Pa), preferably 1–50 Torr (i.e., 133–6,670 Pa).

[0067] For the reaction, all the raw material monomers (HBA, HNA, TA, IA and BP), acylation agents and catalysts can be put into the same reaction vessel and the reaction can be started (one-stage method). Alternatively, the hydroxyl groups of the raw material monomers HBA, HNA and BP can be acylated with acylation agents and then reacted with the carboxyl groups of TA and IA (two-stage method).

[0068] For melt polymerization, after the specified temperature is reached in the reaction system, the pressure is reduced to the specified depressurization level. Once the stirrer torque reaches the specified value, an inactive gas is introduced, and the pressure is increased from the depressurized state to the specified pressurized state, thereby removing the liquid crystal resin from the reaction system.

[0069] The fully aromatic polyester produced by the above polymerization method can further increase its molecular weight through solid-state polymerization under normal or reduced pressure in an inert gas. The preferred conditions for the solid-state polymerization reaction are: a reaction temperature of 230–350°C, preferably 260–330°C, and a final pressure of 10–760 Torr (i.e., 1,330–101,080 Pa).

[0070] Next, the properties of the fully aromatic polyester will be described. The fully aromatic polyester of the present invention exhibits optical anisotropy when melted. This optical anisotropy when melted means that the fully aromatic polyester of the present invention is a liquid crystal resin.

[0071] In this invention, the fact that the fully aromatic polyester is a liquid crystal resin is an indispensable element for the fully aromatic polyester to have both good vibration damping characteristics and flowability. For the fully aromatic polyester composed of the above structural units (I) to (V), depending on the composition and sequence distribution in the polymer, there are also those that do not form an anisotropic molten phase, but the liquid crystal resin of this invention is limited to fully aromatic polyesters that exhibit optical anisotropy when melted.

[0072] The anisotropic nature of the melt can be confirmed using the conventional polarization inspection method with crossed polarizers. More specifically, to confirm melt anisotropy, a polarization microscope manufactured by Olympus Corporation is used. The sample, placed on a heated stage of LINKAM SCIENTIFIC INSTRUMENTS, is melted and observed at 150x magnification under a nitrogen atmosphere. Liquid crystal resins are optically anisotropic, allowing light to pass through when inserted between crossed polarizers. If the sample is optically anisotropic, polarized light will pass through even when it is in a molten, stationary liquid state.

[0073] Nematic liquid crystal resins exhibit a significant decrease in viscosity above their melting point; therefore, liquid crystallinity is typically used as an indicator of processability at or above the melting point. While a high melting point is preferable from a heat resistance perspective, a temperature below 360°C is preferred, considering the thermal degradation of the liquid crystal resin during melt processing and the heating capacity of the molding machine. It should be noted that 300–360°C is more preferred, and 340–358°C is even more preferred.

[0074] The melt viscosity of the aforementioned liquid crystal resin at a temperature 10 to 30°C higher than the melting point of the liquid crystal resin of the present invention, and at a shear rate of 1000 / s, is preferably 500 Pa·s or less, more preferably 0.5 to 300 Pa·s, and even more preferably 1 to 100 Pa·s. If the melt viscosity is within the above range, the aforementioned liquid crystal resin itself, or a composition containing the aforementioned liquid crystal resin, easily ensures fluidity during molding, and the filling pressure is less likely to become excessive. It should be noted that, in this specification, the melt viscosity is the value obtained according to the measurement method of ISO 11443.

[0075] For the liquid crystal resin composition of the present invention, it is preferable to contain 60 to 95% by mass of the above-mentioned liquid crystal resin relative to the total liquid crystal resin composition, more preferably 65 to 95% by mass, further preferably 70 to 95% by mass, and particularly preferably 75 to 92% by mass. If the content of liquid crystal resin relative to the total liquid crystal resin composition is less than 60% by mass, the vibration damping characteristics and flowability of the liquid crystal resin composition may easily deteriorate, and the noise of the fan impeller obtained from the liquid crystal resin composition may deteriorate. If the content of liquid crystal resin relative to the total liquid crystal resin composition is greater than 95% by mass, the strength and rigidity of the fan impeller obtained from the liquid crystal resin composition may decrease.

[0076] [(B) Fibrous filler]

[0077] The liquid crystal resin composition of the present invention, by containing (B) a fibrous filler, can provide sufficient mechanical strength to a fan impeller formed from the liquid crystal resin composition. (B) The fibrous filler can be used alone or in combination of two or more.

[0078] (B) The weight-average fiber length of the fibrous filler is not particularly limited, but can be, for example, 200 μm or more, preferably 300 to 600 μm, and more preferably 400 to 500 μm. If the weight-average fiber length is 600 μm or less, the flowability of the liquid crystal resin composition is easily made sufficient. If the weight-average fiber length is 200 μm or more, the mechanical strength and heat resistance of the molded article obtained from the liquid crystal resin composition of the present invention are easily improved. It should be noted that, in this specification, the weight-average fiber length of (B) the fibrous filler in the liquid crystal resin composition is taken as follows: the average value of the fiber length of the fibrous filler is measured by an image processing method using an image measuring machine after the solid microscope image of the fibrous filler remaining after the liquid crystal resin composition has been ashed at 600°C for 2 hours is imported from a CCD camera into a PC.

[0079] (B) The average fiber diameter of the fibrous filler is not particularly limited, but is, for example, 20 μm or less, preferably 5 to 15 μm. If the average fiber diameter is 20 μm or less, it is easier to suppress fuzzing on the surface of the molded article. It should be noted that, in this specification, the average fiber diameter of the fibrous filler (B) in the liquid crystal resin composition is the average value of the fiber diameter of the fibrous filler remaining after the liquid crystal resin composition has been ashed at 600°C for 2 hours, as observed by an electron microscope (SEM).

[0080] For a fibrous filler that satisfies the above shape, any fiber can be used. However, examples of fibrous fillers for (B) include glass fiber, carbon fiber, ground fiber, asbestos fiber, silica fiber, silica / alumina fiber, zirconium oxide fiber, boron nitride fiber, silicon nitride fiber, boron fiber, potassium titanate fiber, and further examples include inorganic fibrous materials such as stainless steel, aluminum, titanium, copper, and brass. In this invention, from the viewpoint of mechanical strength, glass fiber and / or carbon fiber are preferred as component (B).

[0081] There are no particular limitations on the glass fiber used; any known glass fiber is preferred. Furthermore, there are no particular limitations on the shape of the glass fiber (cylindrical, cocoon-shaped, elliptical cross-section, etc.), the length of chopped filaments or rovings used in manufacturing, or the method of glass cutting. In this invention, the type of glass is also not limited, but E-glass and corrosion-resistant glass containing zirconium are preferred in terms of quality.

[0082] There are no particular limitations on carbon fiber; examples include PAN-based carbon fiber made from polyacrylonitrile and pitch-based carbon fiber made from pitch.

[0083] In the liquid crystal resin composition of the present invention, the content of (B) fibrous filler is 5 to 40% by mass, preferably 5 to 35% by mass, more preferably 5 to 30% by mass, and particularly preferably 8 to 25% by mass. If the content of (B) fibrous filler is within the above range, the fluidity of the liquid crystal resin composition is sufficiently ensured, and good vibration damping characteristics can be obtained, which can easily improve the mechanical strength of the fan impeller obtained from the liquid crystal resin composition and easily suppress noise.

[0084] [Other ingredients]

[0085] Without impairing the effects of the present invention, the liquid crystal resin composition of the present invention may also be appropriately supplemented with other polymers, other fillers, and known substances commonly added to synthetic resins, such as antioxidants, UV absorbers and other stabilizers, antistatic agents, flame retardants, dyes, pigments and other colorants, lubricants, release agents, crystallization promoters, crystallization nucleating agents, and other components, depending on the desired performance. Other components may be used individually or in combination of two or more.

[0086] Other polymers include, for example, liquid crystal resins other than (A). However, from the viewpoint of vibration damping characteristics of the molded body, the liquid crystal resin composition of the present invention preferably does not contain liquid crystal resins other than (A). Other polymers include, for example, copolymers containing epoxy groups. However, since the thermal decomposition of copolymers containing epoxy groups results in gas generation, molded bodies such as fan impellers are difficult to expand due to this, the liquid crystal resin composition of the present invention preferably does not contain copolymers containing epoxy groups.

[0087] Other fillers refer to fillers other than fibrous fillers, such as plate-like fillers (e.g., talc, mica).

[0088] The method for manufacturing the liquid crystal resin composition of the present invention is not particularly limited as long as the components in the liquid crystal resin composition can be uniformly mixed, and can be appropriately selected from conventionally known methods for manufacturing resin compositions. For example, a method in which the components are melt-blended and extruded using a melt-blending apparatus such as a single-screw or twin-screw extruder, and the resulting liquid crystal resin composition is processed into a desired form such as powder, flakes, or granules.

[0089] The liquid crystal resin composition of the present invention has excellent flowability, and therefore can be easily formed into a fan impeller with thin-walled blades.

[0090] From the perspective of easily ensuring the flowability of the liquid crystal resin composition during the molding of the fan impeller and facilitating the molding of the fan impeller with thin-walled blades, it is preferable that the melt viscosity of the liquid crystal resin composition, measured according to ISO 11443, is 500 Pa·s or less (more preferably 5 Pa·s or more and 100 Pa·s or less) at a shear rate of 1000 / s at a temperature 10 to 30°C higher than the melting point of the liquid crystal resin.

[0091] <Fan impeller and fan>

[0092] The fan impeller of the present invention can be obtained by molding the liquid crystal resin composition of the present invention. Furthermore, the fan of the present invention includes the aforementioned fan impeller. Therefore, the fan impeller and the fan of the present invention exhibit excellent vibration damping characteristics and noise suppression.

[0093] The fan of the present invention is not particularly limited and can be a conventional fan having multiple blades, a fan impeller that causes the flow of air or other gases by rotation, a motor that rotates the fan impeller, and a housing that houses the fan impeller and motor. In addition to the fan impeller, motor, and housing, it may also have other components common to conventional fans. The fan impeller of the present invention is partially or entirely formed of the liquid crystal resin composition of the present invention.

[0094] Based on the gas flow pattern, fans can be classified as: axial fans (standard axial fans, double-reverse fans, etc.) where gas passes axially through the fan impeller; centrifugal fans (backward fans, radial fans, multi-blade fans, etc.) where gas passes radially through the fan impeller; and oblique-flow fans where gas passes obliquely through the fan impeller relative to the axial direction; etc. The fan used in this invention is not particularly limited and can be any type of fan, but axial fans and / or centrifugal fans are particularly preferred, and centrifugal fans are more preferred.

[0095] Common uses of fans include ventilation, cooling, and cooling of mechanical / electrical equipment. Among these uses, the fan of the present invention is preferably used as a cooling fan for mechanical / electrical equipment, and more preferably as a cooling fan for electronic devices such as laptops and servers.

[0096] Examples of fan shapes for the present invention include: Figure 1 The axial fan 1 shown Figure 2 Centrifugal fan 2 is shown. Figure 1 The axial fan 1 includes a fan impeller 11, a motor that rotates the fan impeller 11, and a housing 12 that houses the fan impeller 11 and the motor. The motor drives the fan impeller 11, which has multiple blades 111, to rotate, thereby causing air to pass axially through the fan impeller 11 and be directed backward. Figure 2The centrifugal fan 2 includes a fan impeller 21, a motor that rotates the fan impeller 21, and a housing 22 that houses the fan impeller 21 and the motor. The motor drives the fan impeller 21, which has multiple blades 211, to rotate, thereby causing the gas flowing in from the intake port 23 to pass radially through the fan impeller 21 and be directed to the exhaust port 24.

[0097] The blade thickness t of the fan impeller is not particularly limited, but is preferably 0.1 to 0.5 mm, more preferably 0.1 to 0.2 mm. The total blade length L of the fan impeller is not particularly limited, but is preferably 5 to 50 mm, more preferably 10 to 30 mm. The ratio L / t of the total blade length L to the blade thickness t is not particularly limited, but is preferably 50 or more, more preferably 50 to 200. If the values ​​are within the above range, the effects of the present invention are easily achieved when using the liquid crystal resin composition of the present invention. It should be noted that in this specification, the blade thickness t refers to the minimum thickness, and the total blade length L refers to the length of the straight line connecting the base and the tip of the blade in the radial direction.

[0098] The diameter of the fan impeller is not particularly limited, but is preferably 10 to 100 mm, more preferably 20 to 60 mm. The number of blades of the fan impeller is not particularly limited, but is preferably 30 to 80, more preferably 40 to 60. If the numbers are within the above range, the effects of the present invention are easily achieved when using the liquid crystal resin composition of the present invention.

[0099] Example

[0100] The present invention will be specifically described below through examples, but the present invention is not limited thereto.

[0101] <Examples 1-5, Comparative Examples 1-4>

[0102] In the following examples and comparative examples, liquid crystal resins LCP1 to LCP5 were manufactured as follows. During manufacturing, the melting point and melt viscosity of the granules were measured under the following conditions.

[0103] [Determination of melting point]

[0104] Using TA Instruments DSC, after observing the endothermic peak temperature (Tm1) when heating the liquid crystal resin from room temperature at a rate of 20°C / min, the temperature was held at (Tm1+40)°C for 2 minutes, and then cooled to room temperature at a rate of 20°C / min. The temperature of the endothermic peak was then measured again at a rate of 20°C / min.

[0105] [Determination of melt viscosity]

[0106] Using a Capilograph 1B model manufactured by Toyo Seiki Co., Ltd., the melt viscosity of the liquid crystal resin was determined according to ISO 11443 at a temperature 10–20°C higher than the melting point of the liquid crystal resin, through a throttling orifice with an inner diameter of 1 mm and a length of 20 mm, and at a shear rate of 1000 / s. It should be noted that the measurement temperatures were 380°C for LCP1, 350°C for LCP2, 300°C for LCP3, 380°C for LCP4, and 340°C for LCP5.

[0107] (Manufacturing method of LCP1)

[0108] Add the following raw materials—monomer, fatty acid metal salt catalyst, and acylation agent—to a polymerization container equipped with a mixer, reflux column, monomer inlet, nitrogen inlet, and pressure reduction / outlet pipeline, and begin nitrogen purging.

[0109] (I) 4-Hydroxybenzoic acid: 1040g (48 mol%) (HBA)

[0110] (II) 6-Hydroxy-2-naphthoic acid: 89g (3 mol%) (HNA)

[0111] (III) Terephthalic acid: 547g (21 mol%) (TA)

[0112] (IV) Isophthalic acid: 91g (3.5 mol%) (IA)

[0113] (V) 4,4'-Dihydroxybiphenyl: 716g (24.5 mol%) (BP)

[0114] Potassium acetate catalyst: 110 mg

[0115] Acetic anhydride: 1644g

[0116] After adding the raw materials to the polymerization vessel, the temperature of the reaction system was raised to 140°C and reacted at 140°C for 1 hour. Then, the temperature was further increased to 360°C over 5.5 hours, followed by a depressurization to 5 Torr (667 Pa) over 20 minutes, allowing acetic acid, excess acetic anhydride, and other low-boiling components to distill off while melt polymerization continued. Once the stirring torque reached the specified value, nitrogen was introduced, and the pressure was changed from vacuum to atmospheric pressure. The polymer was then discharged from the bottom of the polymerization vessel, granulating the filament. The resulting granules had a melting point of 355°C and a melt viscosity of 10 Pa·s.

[0117] (Manufacturing method of LCP2)

[0118] Add the following raw materials—monomer, fatty acid metal salt catalyst, and acylation agent—to a polymerization container equipped with a mixer, reflux column, monomer inlet, nitrogen inlet, and pressure reduction / outlet pipeline, and begin nitrogen purging.

[0119] (I) 4-Hydroxybenzoic acid 1380g (60 mol%) (HBA)

[0120] (II) 6-Hydroxy-2-naphthoic acid 157g (5 mol%) (HNA)

[0121] (III) Terephthalic acid 484g (17.5 mol%) (TA)

[0122] (V) 4,4'-Dihydroxybiphenyl 388g (12.5 mol%) (BP)

[0123] (VI) N-acetyl-p-aminophenol 126g (5 mol%) (APAP)

[0124] Potassium acetate catalyst 110mg

[0125] 1659g of acetic anhydride

[0126] After adding the raw materials to the polymerization vessel, the temperature of the reaction system was raised to 140°C and reacted at 140°C for 1 hour. Then, the temperature was further increased to 340°C over 4.5 hours, followed by a depressurization to 10 Torr (1330 Pa) over 15 minutes, allowing acetic acid, excess acetic anhydride, and other low-boiling components to distill off while melt polymerization continued. Once the stirring torque reached the specified value, nitrogen was introduced, and the pressure was changed from vacuum to atmospheric pressure. The polymer was then discharged from the bottom of the polymerization vessel, granulating the filament. The resulting granules had a melting point of 336°C and a melt viscosity of 20 Pa·s.

[0127] (Manufacturing method of LCP3)

[0128] Add the following raw materials—monomer, fatty acid metal salt catalyst, and acylation agent—to a polymerization container equipped with a mixer, reflux column, monomer inlet, nitrogen inlet, and pressure reduction / outlet pipeline, and begin nitrogen purging.

[0129] (I) 4-Hydroxybenzoic acid: 1660g (73 mol%) (HBA)

[0130] (II) 6-Hydroxy-2-naphthoic acid: 837g (27 mol%) (HNA)

[0131] Potassium acetate catalyst: 165mg

[0132] Acetic anhydride: 1714g

[0133] After adding the raw materials to the polymerization vessel, the temperature of the reaction system was raised to 140°C and reacted at 140°C for 1 hour. Then, the temperature was further increased to 325°C over 3.5 hours, followed by a depressurization to 5 Torr (667 Pa) over 20 minutes, allowing acetic acid, excess acetic anhydride, and other low-boiling components to distill off while melt polymerization continued. Once the stirring torque reached the specified value, nitrogen was introduced, and the pressure was changed from vacuum to atmospheric pressure. The polymer was then discharged from the bottom of the polymerization vessel, granulating the filament. The resulting granules had a melting point of 280°C and a melt viscosity of 44.0 Pa·s.

[0134] (Manufacturing method of LCP4)

[0135] Add the following raw materials—monomer, fatty acid metal salt catalyst, and acylation agent—to a polymerization container equipped with a mixer, reflux column, monomer inlet, nitrogen inlet, and pressure reduction / outlet pipeline, and begin nitrogen purging.

[0136] (I) 4-Hydroxybenzoic acid: 37g (2 mol%) (HBA)

[0137] (II) 6-Hydroxy-2-naphthoic acid: 1218g (48 mol%) (HNA)

[0138] (III) Terephthalic acid: 560g (25 mol%) (TA)

[0139] (V)4,4'-Dihydroxybiphenyl: 628g (25 mol%) (BP)

[0140] Potassium acetate catalyst: 165mg

[0141] Acetic anhydride: 1432g

[0142] After adding the raw materials to the polymerization vessel, the temperature of the reaction system was raised to 140°C and reacted at 140°C for 1 hour. Then, the temperature was further increased to 360°C over 5.5 hours, followed by a depressurization to 5 Torr (667 Pa) over 30 minutes, allowing acetic acid, excess acetic anhydride, and other low-boiling components to distill off while melt polymerization continued. Once the stirring torque reached the specified value, nitrogen gas was introduced, and the pressure was changed from vacuum to pressurization. The polymer was discharged from the bottom of the polymerization vessel, granulating the filament. The resulting granules were then heat-treated at 300°C for 3 hours under a nitrogen gas flow. The melting point of the granules was 348°C, and the melt viscosity was 9 Pa·s.

[0143] (Manufacturing method of LCP5)

[0144] Add the following raw materials—monomer, fatty acid metal salt catalyst, and acylation agent—to a polymerization container equipped with a mixer, reflux column, monomer inlet, nitrogen inlet, and pressure reduction / outlet pipeline, and begin nitrogen purging.

[0145] (I) 4-Hydroxybenzoic acid: 1347g (60 mol%) (HBA)

[0146] (III) Terephthalic acid: 378g (14 mol%) (TA)

[0147] (IV) Isophthalic acid: 162g (6 mol%) (IA)

[0148] (V)4,4'-Dihydroxybiphenyl: 605g (20 mol%) (BP)

[0149] Potassium acetate catalyst: 110 mg

[0150] Acetic anhydride: 1704g

[0151] After adding the raw materials to the polymerization vessel, the temperature of the reaction system was raised to 140°C and reacted at 140°C for 3 hours. Then, the temperature was further increased to 360°C over 4.5 hours, followed by a depressurization to 10 Torr (1330 Pa) over 15 minutes, allowing acetic acid, excess acetic anhydride, and other low-boiling components to distill off while melt polymerization continued. Once the stirring torque reached the specified value, nitrogen was introduced, and the pressure was changed from vacuum to atmospheric pressure. The polymer was then discharged from the bottom of the polymerization vessel, granulating the filament. The resulting granules had a melting point of 320°C and a melt viscosity of 20 Pa·s.

[0152] (Components other than liquid crystal resin)

[0153] ·Fiber-like filler

[0154] Glass fiber: ECS03T-786H manufactured by Nippon Electric Glass Co., Ltd. (chopped strands with an average fiber diameter of 10μm and a fiber length of 3mm)

[0155] Carbon fiber: HTC432 (PAN-based carbon fiber, chopped filament with an average fiber diameter of 10μm and a fiber length of 6mm) manufactured by Toho Tenex Co., Ltd.

[0156] The liquid crystal resins obtained above, along with components other than those described above, were mixed using a twin-screw extruder to obtain a liquid crystal resin composition. The mixing amounts of each component are shown in Table 1. It should be noted that "%" in the following tables refers to mass percentage. Furthermore, the extrusion conditions for obtaining the liquid crystal resin composition are as follows. Based on the results measured using the testing methods described in this specification, the weight-average fiber length of both the glass fibers and carbon fibers in the obtained liquid crystal resin composition is 450 μm.

[0157] [Extrusion Conditions]

[0158] The barrel temperature at the main feed inlet is set to 250°C, and all other barrel temperatures are set as described below. The liquid crystal resin is supplied entirely through the main feed inlet. The filler is supplied through the side feed inlet. Other barrel temperatures:

[0159] 370℃ (Examples 1-4, Comparative Examples 3 and 4)

[0160] 340℃ (Example 5)

[0161] 350℃ (Comparative Example 1)

[0162] 300℃ (Comparative Example 2)

[0163] (Determination of melt viscosity of liquid crystal resin compositions)

[0164] Using a Capilograph 1B model manufactured by Toyo Seiki Co., Ltd., the melt viscosity of the liquid crystal resin composition was determined according to ISO 11443 at a temperature 10–20°C higher than the melting point of the liquid crystal resin, using a throttling orifice with an inner diameter of 1 mm and a length of 20 mm, and a shear rate of 1000 / s. It should be noted that the measurement temperature was 380°C for the liquid crystal resin composition using LCP1, 350°C for the liquid crystal resin composition using LCP2, 300°C for the liquid crystal resin composition using LCP3, 380°C for the liquid crystal resin composition using LCP4, and 340°C for the liquid crystal resin composition using LCP5. The results are shown in Table 1.

[0165] The physical properties of molded articles formed from liquid crystal resin compositions were determined using the following method. The evaluation results are shown in Table 1.

[0166] (Bending test)

[0167] The liquid crystal resin composition was injection molded under the following molding conditions to obtain ISO test piece A. This test piece was then cut to obtain a test piece for measurement (80mm × 10mm × 4mm). Using this test piece, the flexural strength and flexural modulus were determined according to ISO 178.

[0168] [Forming conditions]

[0169] Forming machine: Sumitomo Heavy Industries, Ltd., SE100DU

[0170] Barrel temperature:

[0171] 370℃ (Examples 1-4, Comparative Examples 3 and 4)

[0172] 340℃ (Example 5)

[0173] 350℃ (Comparative Example 1)

[0174] 300℃ (Comparative Example 2)

[0175] Mold temperature: 90℃

[0176] Injection speed: 33 mm / sec

[0177] (Loss coefficient (vibration attenuation characteristics))

[0178] The liquid crystal resin composition was injection molded under the following molding conditions to obtain a test piece measuring 200 mm × 10 mm × 1.6 mm. The test piece was then mounted centrally on an EMIC Corporation accelerator "512-D," and the loss coefficient (vibration damping characteristics) at 23°C and 10000 Hz was determined using the half-width method according to JIS G0602. The results are shown in Table 1.

[0179] [Forming conditions]

[0180] Forming machine: Sumitomo Heavy Industries, Ltd., SE100DU

[0181] Barrel temperature:

[0182] 370℃ (Examples 1-4, Comparative Examples 3 and 4)

[0183] 340℃ (Example 5)

[0184] 350℃ (Comparative Example 1)

[0185] 300℃ (Comparative Example 2)

[0186] Mold temperature: 90℃

[0187] Injection speed: 33 mm / sec

[0188] (Thin-walled flowability)

[0189] Under the following molding conditions, rod-shaped articles with a width of 5 mm and a thickness of 0.2 mm were formed, and the flow distance was measured. The average value of 5 tests was taken as the flow distance. The results are shown in Table 1.

[0190] [Forming conditions]

[0191] Forming machine: Sumitomo Heavy Industries, Ltd., SE30DUZ

[0192] Barrel temperature:

[0193] 370℃ (Examples 1-4, Comparative Examples 3 and 4)

[0194] 340℃ (Example 5)

[0195] 350℃ (Comparative Example 1)

[0196] 300℃ (Comparative Example 2)

[0197] Mold temperature: 80℃

[0198] Injection speed: 300 mm / sec

[0199] Injection pressure: 100 MPa

[0200] The liquid crystal resin composition was injection molded under the following molding conditions to obtain the following result: Figure 3 The centrifugal fan impeller shown has the following characteristics: blade thickness t: 0.2 mm, blade length L: 15 mm, number of blades: 45, and impeller diameter: 46 mm.

[0201] [Forming conditions]

[0202] Forming machine: Sumitomo Heavy Industries, Ltd., SE100DU

[0203] Barrel temperature:

[0204] 370℃ (Examples 1-4, Comparative Examples 3 and 4)

[0205] 340℃ (Example 5)

[0206] 350℃ (Comparative Example 1)

[0207] 300℃ (Comparative Example 2)

[0208] Mold temperature: 90℃

[0209] Injection speed: 33 mm / sec

[0210] (Noise Suppression)

[0211] The centrifugal fan with the fan impeller obtained above was installed in a laptop computer. In a silent chamber, noise was measured under the following conditions using a precision noise meter (RION Co., Ltd. "NA-60") and an FFT analyzer (Ono Test Instruments Co., Ltd. "CF5220"). The results are shown in Table 1.

[0212] Rotation speed: 15,000 rpm

[0213] Measurement distance: 100mm (above the axis center)

[0214] Rotation direction: forward rotation

[0215] [Table 1]

[0216]

[0217] As shown in Table 1, the vibration damping characteristics, thin-wall flowability, and noise suppression were all rated as good in the embodiments. Therefore, it was confirmed that the liquid crystal resin composition of the present invention exhibits excellent vibration damping characteristics and flowability, and the fan impeller obtained from this liquid crystal resin composition demonstrates excellent vibration damping characteristics and noise suppression. Therefore, the above-described liquid crystal resin composition can be suitably used in the manufacture of fan impellers.

Claims

1. A liquid crystal resin composition for use in the impeller of a cooling fan in electronic devices, comprising (A) a liquid crystal resin and (B) a fibrous filler. The liquid crystal resin composition does not contain plate-shaped fillers. The blade thickness of the fan impeller is 0.1~0.5mm. The liquid crystal resin (A) is a fully aromatic polyester that exhibits optical anisotropy when molten, and it is composed of the following structural units (I), (II), (III), (IV) and (V). The content of structural unit (I) is 35-75 mol% relative to all structural units. The content of structural unit (II) is 2-8 mol% relative to all structural units. The content of structural unit (III) is 4.5–30.5 mol% relative to all structural units. The content of structural unit (IV) is 2-8 mol% relative to all structural units. The content of structural unit (V) is 12.5–32.5 mol% relative to all structural units. The total content of structural units (I) to (V) relative to all structural units is 100 mol%. The fibrous filler (B) is glass fiber and / or carbon fiber. Relative to the total liquid crystal resin composition, the content of (A) liquid crystal resin is 70-95% by mass, and the content of (B) fibrous filler is 5-30% by mass. The weight-average fiber length of the fibrous filler (B) is 200 μm or more and 600 μm or less, and the average fiber diameter of the fibrous filler (B) is 5 to 15 μm. The loss coefficient of the liquid crystal resin composition, as determined by JIS G0602 at a temperature of 23°C and a frequency of 10000Hz, is 0.06~0.

08. 。 2. A fan impeller for a cooling fan in an electronic device, formed from the liquid crystal resin composition of claim 1, wherein the blade thickness is 0.1~0.5 mm.

3. The fan impeller according to claim 2 is a centrifugal fan impeller with a blade total length L (mm) to blade thickness t (mm) ratio L / t of 50 to 200.

4. A cooling fan in an electronic device, comprising the fan impeller as described in claim 2 or 3.

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