JP2001064498A - Vibration-damping liquid crystalline resin composition and molded product composed of the same composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a vibration-damping liquid crystalline resin composition excellent in vibration-damping property and moldability and processability and a molded product composed of the above resin composition. SOLUTION: This vibration-damping liquid crystalline resin composition comprises 100 pts.wt. liquid crystalline resin and 20-200 pts.wt. carbon fiber having 100-500 μm weight average length and 20-70 average aspect ratio and has >=0.03 loss factor at 23 deg.C. This molded product is composed of the above resin composition.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vibration-damping liquid crystal resin composition having excellent vibration-damping properties and excellent moldability and mechanical properties, and a molded article comprising the same.

[0002]

2. Description of the Related Art In recent years, there has been an increasing demand for higher performance of plastics, and a number of polymers having various new properties have been developed and marketed. Among them, optics characterized by a parallel arrangement of molecular chains. Anisotropic liquid crystalline polymers have attracted attention because of their excellent fluidity, heat resistance, and mechanical properties.

[0003] Polymers forming an anisotropic molten phase include:
For example, a liquid crystalline polymer obtained by copolymerizing p-hydroxybenzoic acid with polyethylene terephthalate (JP-A-49-723)
No. 93), a liquid crystalline polymer obtained by copolymerizing p-hydroxybenzoic acid and 6-hydroxy-2-naphthoic acid (JP-A-54-77691), and p-hydroxybenzoic acid is 4,4′- Liquid crystalline polymer obtained by copolymerizing dihydroxybiphenyl with terephthalic acid and isophthalic acid
7-24407), a liquid crystalline polymer produced from 6-hydroxy-2-naphthoic acid, p-aminophenol and terephthalic acid (JP-A-57-172921),
There are disclosed liquid crystalline polymers formed from p-hydroxybenzoic acid, 4,4'-dihydroxybiphenyl, terephthalic acid, p-aminobenzoic acid and polyethylene terephthalate (JP-A-64-33123).

[0004] These liquid crystalline polymers have a drawback that mechanical anisotropy and dimensional anisotropy are extremely large. For example, a method of adding a fibrous material to a liquid crystal polymer (Rubber Digest Vol. 27, No. 8, No. 7- 14 (1975)), the mechanical strength, heat resistance,
The moldability and dimensional stability are further improved, and it can be used as an engineering plastic for structures of functional parts such as automobiles, electric / electronics, precision machines, and office machines.

However, such machines are often required to have high performance and high precision, and the structure vibrates due to the propagation of vibrations generated inside the machine such as a drive motor, and the amplitude sometimes increases. A so-called resonance phenomenon occurs. If so, the product may malfunction due to vibration, and improvement is required.

As these methods, a method of adding aluminum borate whiskers to a liquid crystalline resin to increase the elastic modulus of the material used for the structure and reduce the amplitude (Japanese Unexamined Patent Publication No.
No. 80517) and a method of dispersing and orienting a liquid crystalline resin in another thermoplastic resin (Japanese Patent Application Laid-Open No. 9-143379) has been proposed.

However, in the method of reducing the amplitude by increasing the elastic modulus of the material used for the structure, the elastic modulus required only for reducing the amplitude is small although the elastic modulus originally required for the structure is small. Therefore, there has been a problem that the structure becomes heavy and the moldability deteriorates. Further, the method of dispersing and orienting a liquid crystalline resin in another thermoplastic resin has a problem in that the original properties of the liquid crystalline resin are lost.

[0008] On the other hand, a method of adding carbon fiber to a liquid crystal polymer has been proposed (Japanese Patent No. 2579742), but there is no description at all for use in applications requiring vibration damping properties.

[0009]

Accordingly, in order to solve the above-mentioned problems, the present invention provides a vibration-damping liquid crystal resin which can impart excellent vibration-damping properties to a molded article, and has excellent molding workability and mechanical properties. It is an object to obtain a composition and a molded article comprising the composition.

[0010]

Means for Solving the Problems The inventors of the present invention have made intensive studies to solve the above-mentioned problems, and as a result, a specific type of liquid crystalline resin has been developed.
By adding a filler in the range, since the vibration damping property is dramatically improved while maintaining the moldability and mechanical properties, it has been found that it can be used exclusively for molded article applications where vibration damping is required, Finally, the present invention has been completed.

That is, an object of the present invention is to provide "(A) one or more liquid crystalline resins selected from liquid crystalline polyesters and liquid crystalline polyesteramides which form an anisotropic molten phase.
(B) weight average length of 100 to 5
A carbon fiber having an average aspect ratio of 20 to 70 μm and a carbon fiber content of 20 to 200 parts by weight;
Wherein the loss coefficient is 0.03 or more. Can be achieved.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The liquid crystalline polyester and the liquid crystalline polyesteramide which form an anisotropic molten phase in the liquid crystalline resin (A) used in the present invention include an aromatic oxycarbonyl unit, an aromatic dioxy unit and an aromatic dioxy unit. Dicarbonyl unit, a liquid crystalline polyester forming an anisotropic molten phase consisting of structural units selected from ethylenedioxy units and the like, and the above structural units and aromatic iminocarbonyl units, aromatic diimino units, aromatic And liquid crystalline polyesteramides that form an anisotropic molten phase composed of structural units selected from aromatic iminooxy units.

As examples of the liquid crystalline polyester forming the anisotropic molten phase, a liquid crystalline polyester preferably having the following structural units (I), (II) and (IV):
And liquid crystalline polyesters comprising the structural units (I), (II), (III) and (IV), and liquid crystalline polyesters comprising the structural units (I), (III) and (IV).

[0014]

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(Where R 1 in the formula is

[0016]

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At least one group selected from the group consisting of R2
Is

[0018]

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And represents one or more groups selected from Also,
In the formula, X represents a hydrogen atom or a chlorine atom, and the structural unit (I
The sum of (I) and (III) and the structural unit (IV) are substantially equimolar. The structural unit (I) is a structural unit of a polyester formed from p-hydroxybenzoic acid, and the structural unit (II) is 4,4′-dihydroxybiphenyl, 3,3 ′, 5,
5'-tetramethyl-4,4'-dihydroxybiphenyl, hydroquinone, t-butylhydroquinone, phenylhydroquinone, 2,6-dihydroxynaphthalene, 2,7-dihydroxynaphthalene, 2,2-bis (4-hydroxyphenyl) propane And 4,4'-
A structural unit formed from one or more aromatic dihydroxy compounds selected from dihydroxydiphenyl ether,
The structural unit (III) is a structural unit formed from ethylene glycol, and the structural unit (IV) is terephthalic acid, isophthalic acid, 4,4′-diphenyldicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 1,2-bis ( At least one aromatic dicarboxylic acid selected from phenoxy) ethane-4,4′-dicarboxylic acid, 1,2-bis (2-chlorophenoxy) ethane-4,4′-dicarboxylic acid and 4,4 ′ diphenyl ether dicarboxylic acid The structural units generated from the acid are shown below.

Examples of the liquid crystalline polyesteramide include 6-hydroxy-2-naphthoic acid, a liquid crystalline polyesteramide formed from p-aminophenol and terephthalic acid, p-hydroxybenzoic acid, 4,4′-dihydroxy acid. Liquid crystalline polyesteramide formed from biphenyl and terephthalic acid, p-aminobenzoic acid and polyethylene terephthalate (Japanese Patent Application Laid-Open No. 64-33123)
And the like.

The liquid crystalline polyester which can be preferably used in the present invention is a copolymer comprising the above structural units (I), (II) and (IV), or (I), (II), (III) and (IV) And the copolymerization amount of the above structural units (I), (II), (III) and (IV) is arbitrary. However, the following copolymerization amount is preferred from the viewpoint of fluidity.

That is, when the above-mentioned structural unit (III) is contained, the sum of the above-mentioned structural units (I) and (II) is determined from the viewpoint of heat resistance, flame retardancy and mechanical properties.
It is preferably from 60 to 95 mol%, more preferably from 75 to 93 mol%, based on the total of (II) and (III). Further, the structural unit (III) is preferably 40 to 5 mol%, more preferably 25 to 7 mol%, based on the total of (I), (II) and (III). Further, the molar ratio [(I) / (II)] of the structural unit (I) to (II) is preferably from 75/25 to 95/5, more preferably 78 from the viewpoint of the balance between heat resistance and fluidity. / 22 to 93/7. The structural unit (IV) is substantially equimolar to the sum of the structural units (II) and (III).

On the other hand, when the above-mentioned structural unit (III) is not contained, the structural unit (I) is preferably 40 to 90 mol% with respect to the total of (I) and (II) from the viewpoint of fluidity. , 60 to 88 mol%.
The structural unit (IV) is substantially equimolar to the structural unit (II).

In the polycondensation of the liquid crystalline polyester preferably used in the present invention, in addition to the components constituting the structural units (I) to (IV), 3,3'-diphenyldicarboxylic acid, 2,2 Aromatic dicarboxylic acids such as' -diphenyldicarboxylic acid, aliphatic dicarboxylic acids such as adipic acid, azelaic acid, sebacic acid and dodecandioic acid; alicyclic dicarboxylic acids such as hexahydroterephthalic acid; chlorohydroquinone, methylhydroquinone, 4,4'-dihydroxydiphenyl sulfone, 4,
4'-dihydroxydiphenyl sulfide, 4,4'-
Aromatic diols such as dihydroxybenzophenone,
Aliphatics such as 4-butanediol, 1,6-hexanediol, neopentyl glycol, 1,4-cyclohexanediol, and 1,4-cyclohexanedimethanol;
Alicyclic diols and m-hydroxybenzoic acid, 2,6
Aromatic hydroxycarboxylic acids such as -hydroxynaphthoic acid and p-aminophenol, p-aminobenzoic acid and the like can be further copolymerized in a small proportion that does not impair the object of the present invention.

The method for producing the liquid crystalline resin (A) in the present invention is not particularly limited, and it can be produced according to a known polyester polycondensation method.

For example, in the production of the above-mentioned preferably used liquid crystalline polyester, the production of (1) and (2) when the above-mentioned structural unit (III) is not contained, and the production of (3) when the above-mentioned structural unit (III) is contained. A method is preferably mentioned. (1) Deacetic acid polycondensation reaction from a diacylated product of an aromatic dihydroxy compound such as p-acetoxybenzoic acid and 4,4′-diacetoxybiphenyl or 4,4′-diacetoxybenzene with an aromatic dicarboxylic acid such as terephthalic acid Method for producing liquid crystal polyester by (2) After reacting acetic anhydride with p-hydroxybenzoic acid and an aromatic dihydroxy compound such as 4,4′-dihydroxybiphenyl and hydroquinone, and an aromatic dicarboxylic acid such as terephthalic acid to acylate a phenolic hydroxyl group, A method for producing a liquid crystal polyester by a deacetic acid polycondensation reaction. (3) Polyester polymers such as polyethylene terephthalate, oligomers or aromatic dicarboxylic acids such as bis (β-hydroxyethyl) terephthalate bis (β
(Hydroxyethyl) ester in the presence of (1) or (2) to produce a liquid crystalline polyester.

Although these polycondensation reactions proceed without a catalyst, it is sometimes preferable to add a metal compound such as stannous acetate, tetrabutyl titanate, potassium acetate and sodium acetate, antimony trioxide, and metallic magnesium. .

As the liquid crystalline resin (A) in the present invention, there is a liquid crystal resin whose logarithmic viscosity can be measured in pentafluorophenol.
It is preferably at least 0.5 dl / g as measured at 0 ° C., and particularly when the above structural unit (III) is contained, it is 1.0 to 3.0 dl.
/ G is preferred, and when the above structural unit (III) is not contained, the content is preferably 2.0 to 10.0 dl / g.

The melt viscosity of the liquid crystalline resin (A) in the present invention is preferably from 10 to 20,000 poise, more preferably from 20 to 10,000 poise.

Note that the above melt viscosity is equal to the melting point (Tm) +1.
It is a value measured by a Koka type flow tester under a condition of 0 ° C. and a shear rate of 1,000 (1 / second).

Here, the melting point (Tm) means the endothermic peak temperature Tm1 observed when the polymer is measured from room temperature under a heating condition of 20 ° C./min by differential calorimetry.
The temperature was raised to a temperature of + 20 ° C., kept at the same temperature for 5 minutes, and then cooled to room temperature once at a temperature lowering condition of 20 ° C./min.
It refers to the endothermic peak temperature that is observed when the measurement is performed again under the heating condition of 20 ° C./min.

The carbon fiber (B) in the present invention is PAN
System, pitch system, rayon system, etc.
The PAN type is excellent in balance between vibration damping property and mechanical strength, and is preferably used in the present invention.

The carbon fiber (B) in the present invention preferably has its surface oxidized, and more preferably has been treated with a sizing agent such as epoxy, urethane or acrylic. As the sizing agent, an epoxy type is particularly preferable, and a silane type, a titanate type coupling agent or the like which has been treated with a surface treating agent can be preferably used. In this case, an epoxy silane or aminosilane type coupling agent is particularly preferable.

The carbon fiber (B) in the present invention is 100
It has a weight average length of ５００500 μm and an average aspect ratio of 20 to 70. If the weight average length is too small, the vibration damping properties are poor. If the weight average length is too large, the appearance and molding processability of the molded body surface are poor, which is not preferred.
５００500 μm. Also, the average aspect ratio is a value obtained by dividing the weight average length of the carbon fiber by the average diameter.If the average aspect ratio is too small, the vibration damping property is inferior. , More preferably 30 to 60.

In the present invention, (B) the carbon fiber is (A)
It is used in an amount of 20 to 200 parts by weight, preferably 30 to 180 parts by weight, more preferably 40 to 170 parts by weight, based on 100 parts by weight of the liquid crystalline resin. If the amount of the carbon fiber is too small, the vibration damping property is inferior.

The vibration-damping liquid crystal resin composition of the present invention comprises (C)
By adding the flaky filler, the vibration damping property is further improved,
(C) scaly fillers include mica, glass flake,
Mica and the like can be mentioned. Among them, those having a ratio of average diameter to average thickness of 25 or more are preferable, and mica is preferable among the fillers.

The flaky filler (C) of the present invention is used in an amount of 0 to 100 parts by weight, more preferably 5 to 90 parts by weight, based on 100 parts by weight of the liquid crystal resin (A). If the amount of the filler is too large, molding processability and mechanical properties are inferior, which is not preferable.

The vibration damping liquid crystal resin composition of the present invention has a temperature of 23 ° C.
Is required to be 0.03 or more. If the loss coefficient is too small, the damping property of the damping liquid crystal resin composition is significantly reduced, which is not preferable. Among them, 0.04 or more is particularly preferable.

In the vibration damping liquid crystal resin composition of the present invention, glass fibers, aromatic polyamide fibers, potassium titanate fibers, gypsum fibers, brass fibers, stainless steel fibers, steel fibers, and the like, as long as the object of the present invention is not impaired. Ceramic fiber,
Fillers such as boron whisker fiber, asbestos fiber, talc, silica, calcium carbonate, glass beads, molybdenum disulfide, wollastenite, titanium oxide, calcium polyphosphate, and graphite can be used.
Further, to the extent that the object of the present invention is not impaired, antioxidants and heat stabilizers (eg, hindered phenol, hydroquinone, phosphites and their substituted products), ultraviolet absorbers (eg, resorcinol, salicylate, Benzotriazole, benzophenone, etc.), lubricants and release agents (montanic acid and its salts, its esters, its half esters, stearyl alcohol, stearamide and polyethylene wax, etc.),
Common additives such as colorants, dyes (eg, nigrosine) and pigments (eg, cadmium sulfide, phthalocyanine, carbon black), plasticizers, flame retardants, flame retardant auxiliaries, antistatic agents, and other thermoplastic resins (Fluorine resin or the like) can be added to impart predetermined characteristics.

The vibration-damping liquid crystal resin composition of the present invention is preferably produced by melt-kneading, and a known method can be used for melt-kneading. For example, a Banbury mixer, a rubber roll machine, a kneader, a single screw or twin screw extruder can be used. Since the melt-kneading method needs to have carbon fibers having a specific range of a weight average length and an average aspect ratio, (A) the carbon fibers are supplied while the liquid crystal resin is in a molten state in a twin screw extruder. It is preferable to obtain a carbon fiber having a weight average length and an average aspect ratio in a specific range by changing the screw arrangement and the screw rotation speed and controlling the extrusion temperature.

The thus obtained vibration damping liquid crystal resin composition of the present invention has excellent vibration damping properties, moldability and mechanical properties by ordinary molding methods such as injection molding, extrusion molding, blow molding and the like. It can be processed into three-dimensional molded products, sheets, containers, pipes and the like having low mechanical properties. Therefore, since there is a problem of vibration, noise, etc., when this vibration-damping liquid crystal resin composition is used for a molded article requiring vibration-damping properties, an excellent effect is exhibited. Further, among the applications requiring vibration damping properties, it can be preferably used for applications having a structure of a thin-walled molded product or a molded product having a complicated shape by using a feature having excellent moldability.

For example, in the case of automobile use, it prevents the engine sound and vibration from propagating and resonating in the room, and also in the air-conditioning-related and control systems such as air conditioners and fans, the vibration and resonance due to the rotation of the motor and the malfunction due to it. It is effective in suppressing wind noise at the outlet and preventing vibration and resonance due to road noise and wind noise during traveling, etc., and precision machinery related parts (alternator terminal, alternator connector, IC regulator, light regulator) Valves, exhaust valves, etc., various pipes related to fuel, exhaust system, intake system, intake manifold, fuel pump, engine cooling water joint, carburetor main body, carburetor spacer, exhaust gas sensor, cooling water sensor, Oil temperature sensor, brake Wear sensor, throttle position sensor, crankshaft position sensor, air flow meter, brake butt wear sensor, thermostat base for air conditioner, heating hot air flow control valve, brush holder for radiator motor, water pump impeller, turbine vane, wiper Motor related parts, Distributor, Starter switch, Starter relay, Transmission wire harness, Window washer nozzle, Air conditioner panel switch board, Fuel related electromagnetic valve coil, Fuse connector, Horn terminal, Electrical component insulating plate, Step motor rotor , Lamp socket, lamp reflector, lamp housing,
Examples include a brake piston, a solenoid bobbin, an engine oil filter, and an ignition device case.

For electric and electronic applications, vibration due to rotation of the motor, especially malfunction due to this vibration, may be effective for drive system parts, control system parts, precision parts, and various gears, sensors, connectors, Resistor,
Relay case switch, coil bobbin, condenser,
Variable condenser case, oscillator, various terminal boards, plug, printed wiring board, small motor, magnetic head base, power module, housing, FDD carriage, FDD chassis, HDD actuator, HDD motor core, motor brush holder, computer related parts,
Home appliances such as VTR parts, television parts, dryers, rice cooker parts, microwave parts, trays such as audio / laser discs / compact discs, lighting parts, refrigerator parts, air conditioner parts, word processor parts, and facsimile-related parts.

In addition, noise, vibration,
This is useful for applications in which resonance can be suppressed and malfunction can be prevented.

[0045]

The present invention will be described in more detail with reference to the following examples.

Reference Example 1 994 parts by weight of p-hydroxybenzoic acid, 126 parts by weight of 4,4'-dihydroxybiphenyl, 112 terephthalic acid
Parts by weight, 216 parts by weight of polyethylene terephthalate having an intrinsic viscosity of about 0.6 dl / g and 960 parts by weight of acetic anhydride are charged into a reaction vessel equipped with a stirring blade and a distilling tube, and polycondensation is performed to complete the polycondensation. (A1) was obtained. The melting point (Tm) of this resin is 314 ° C., 324 ° C., shear rate 1
The melt viscosity at 000 / sec was 400 poise.

REFERENCE EXAMPLE 2 994 parts by weight of p-hydroxybenzoic acid, 222 parts by weight of 4,4'-dihydroxybiphenyl, 147 parts by weight of 2,6-diacetoxynaphthalene, 1078 parts by weight of acetic anhydride and 299 parts by weight of terephthalic acid were stirred. It was charged into a reaction vessel equipped with blades and a distilling tube and subjected to polycondensation to complete the polycondensation, thereby obtaining a resin (A2). The melting point (Tm) of this resin is 336
° C, and the melt viscosity at 346 ° C and a shear rate of 1000 / sec was 520 poise.

Reference Example 3 According to JP-A-54-77691, 921 parts by weight of p-acetoxybenzoic acid and 435 parts by weight of 6-acetoxynaphthoic acid were charged into a reaction vessel equipped with a stirring blade and a distilling tube. Condensation was performed to obtain a resin (A3). The melting point (Tm) of this resin is 283 ° C., 293 ° C., shear rate 10
The melt viscosity at 00 / sec was 2,000 poise.

Examples 1 to 4 and Comparative Examples 1 to 6 100 parts by weight of the vibration-damping liquid crystal resin composition obtained in Reference Examples 1 to 3 were extruded using a 30 mmφ twin screw extruder as shown in Table 1. Then, (B) carbon fiber (6 μm diameter, 6 mm length cut, using epoxy sizing agent) and (C) flaky filler (mica, average diameter 8 μm, average thickness 0.2 μm) were melt-kneaded to obtain pellets. The pellets were added to a 3N aqueous sodium hydroxide solution and heated at 150 ° C. for 20 hours or more to dissolve and remove the resin, and the weight average length of the remaining carbon fibers was measured. Further, if necessary, the molded product was supplied to a Nissei PS60E9ASE injection molding machine (manufactured by Nissei Plastic Industry Co., Ltd.) under the conditions of a cylinder temperature of + 10 ° C. and a mold temperature of 90 ° C.

[Method for Measuring Physical Properties] The method for measuring the properties of the liquid crystal resin composition of the present invention will be described below. For general properties such as vibration damping properties and mechanical properties, test pieces were prepared by injection molding and measured according to the following test methods. (1) Vibration control: Loss coefficient: JIS according to the half width method using a test piece having a length of 130 mm, a width of 10 mm and a thickness of 3 mm
The loss coefficient at 23 ° C. was measured according to G0602. (2) Formability: Maximum filling time: A cylindrical molded product (outer diameter 25 mm, inner diameter 20 mm, height 30 mm) can be molded under the conditions of an injection pressure of 300 kgf / cm ² to obtain a complete molded product. The maximum possible filling time was determined. The longer the maximum filling time, the better the moldability. (3) Mechanical properties: Flexural modulus ASTM D790 (specimen thickness 6.4 mm, measurement temperature 23 ° C.). (4) Appearance of molded article: The appearance of the molded article obtained by injection molding was visually judged, and the molded article surface was smooth and good (あ り), slightly smooth (も の), and not smooth but uneven. Are indicated by (x).

The results are shown in Table 1.

[0052]

[Table 1]

From the above results, it can be seen that the vibration-damping liquid crystal resin composition of the present invention has a better balance of vibration-damping properties, moldability and mechanical properties than the resin composition of the comparative example. .

[0054]

EFFECTS OF THE INVENTION The vibration-damping liquid crystal resin composition of the present invention has improved vibration damping properties without impairing the excellent heat resistance, fluidity and mechanical properties of the liquid crystal resin. It is suitable for applications requiring vibration damping, such as electrical / electronic related equipment, precision machine related equipment, office equipment, and automobile / vehicle related parts.

Continued on the front page F term (reference) 4F071 AA43 AA57 AB03 AD01 AD05 AD06 AE17 AF13Y AF53 AH17 BA01 BB06 BC01 4J002 CF161 CF181 CL081 DA036 DJ057 DL007 FA017 FA046 FD010 FD016 FD017 FD050 FD060 FD070 FD090 FD160 FD170

Claims (3)

[Claims] 1. A weight average length (B) of 100 parts by weight of at least one kind of liquid crystalline resin selected from (A) a liquid crystalline polyester and a liquid crystalline polyester amide forming an anisotropic molten phase. A vibration-damping liquid crystal resin composition containing 20 to 200 parts by weight of carbon fibers having an average aspect ratio of 20 to 70 and a loss coefficient at 23 ° C of 0.03 or more. 2. The vibration damping liquid crystal resin composition according to claim 1, further comprising (C) a flaky filler. 3. A vibration-damping molded article obtained by molding the vibration-damping liquid crystal resin composition according to claim 1 or 2.