WO2021131473A1 - Soundproofing member and method for manufacturing soundproofing member - Google Patents

Abstract

A soundproofing member that is a molded body having liquid crystal polyester as a forming material, the soundproofing member having a core layer formed as the inner layer of the molded body, and an orientation layer formed as a surface layer of the molded body, and being such that the liquid crystal polyester forming the orientation layer is oriented to a greater extent than the liquid crystal polyester forming the core layer, and the ratio of the elasticity of the core layer to the elasticity of the molded body is 0.60-0.95 (inclusive).

Description

Sound insulation member and manufacturing method of sound insulation member

The present invention relates to a sound insulating member and a method for manufacturing the sound insulating member.
This application claims priority based on Japanese Patent Application No. 2019-234798 filed on December 25, 2019, the contents of which are incorporated herein by reference.

A molded product made of liquid crystal polyester has high strength, high heat resistance, and high dimensional accuracy. Therefore, liquid crystal polyester is used as a material for forming relatively small electronic parts such as connectors and relay parts (see, for example, Patent Document 1). Such a molded body is molded by injection molding.

Japanese Unexamined Patent Publication No. 07-126383

In recent years, in the automobile field, consideration has been given to weight reduction for the purpose of improving fuel efficiency. For example, in order to reduce the weight, various parts such as parts called outer panels such as bonnets and roofs, as well as parts in interiors and engine rooms are being studied to be replaced with resin parts. Resin parts may be simply referred to as "resin parts" below.

When metal parts are replaced with resin parts, the weight can be reduced, but the sound transmitted through the resin parts can be felt loudly, which may cause a problem. For example, if the roof of an automobile is replaced with a resin part, the weight can be reduced, but the passengers of the automobile may feel a loud rain noise generated on the roof in rainy weather, which may impair the environment inside the automobile.

For such problems, it is conceivable to take measures to ensure the sound insulation inside the vehicle by forming a composite molded body in which a soundproofing material such as felt is usually attached to resin parts. However, when the soundproofing material is attached, the volume of the member is increased and the weight is further increased, which impairs the advantages of the resin part.

In the present specification, "sound insulation" means that when a sound emitted from one side of a resin part reaches the other side of the resin part via the resin part, the resin part blocks the sound. Is shown. "Sound insulation" indicates the degree of sound insulation, and is evaluated using "volume insulation" which is the difference between the sound pressure of the sound incident on the resin component and the sound pressure of the sound transmitted through the resin component.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide a sound insulating member which uses liquid crystal polyester as a forming material and exhibits excellent sound insulating properties. Another object of the present invention is to provide a method for manufacturing a sound insulating member, which makes it possible to easily manufacture the above-mentioned sound insulating member.

In order to solve the above problems, the present invention includes the following aspects.

[1] A molded body made of liquid crystal polyester as a forming material, which has a core layer formed in an inner layer of the molded body and an orientation layer formed on the surface of the molded body to form the alignment layer. The liquid crystal polyester is more oriented than the liquid crystal polyester forming the core layer, and the ratio of the elastic modulus of the core layer to the elastic modulus of the molded body is 0.60 or more and 0.95 or less.

[2] The sound insulating member according to [1], which is a vehicle component.

[3] A method for manufacturing a sound insulating member, which comprises a step of injection molding a molten resin of a liquid crystal polyester composition containing a liquid crystal polyester, and an average resin speed in a mold of the molten resin is 100 mm / sec or more and 500 mm / sec or less. ..

According to the present invention, it is possible to provide a sound insulation member exhibiting excellent sound insulation using liquid crystal polyester as a forming material. Further, the present invention can provide a method for manufacturing a sound insulating member, which makes it possible to easily manufacture the above-mentioned sound insulating member.

FIG. 1 is a schematic view showing an example of the sound insulation member 1. FIG. 2 is a schematic view showing a cross section of the sound insulating member 1. FIG. 3 is a schematic view showing a method for evaluating sound insulation.

Hereinafter, the sound insulating member and the manufacturing method of the sound insulating member according to the present embodiment will be described with reference to the drawings. In all the drawings below, the dimensions and ratios of the components are appropriately different in order to make the drawings easier to see.

[Sound insulation member]
FIG. 1 is a schematic view showing an example of the sound insulation member 1 of the present embodiment. The sound insulating member 1 is a case in which the sound source X is housed inside. In such a sound insulating member 1, when the sound S1 emitted from the sound source X housed inside the sound insulating member 1 reaches the outside of the sound insulating member 1 via the sound insulating member 1, the sound insulating member 1 blocks the sound. .. Therefore, the sound S2 leaking to the outside of the sound insulating member 1 is attenuated more than the sound S1 emitted from the sound source X.

For example, examples of the sound insulation member 1 include a motor cover that houses a motor as a sound source X, a gearbox that houses a gear as a sound source X, and the like.

The sound insulation member 1 is a molded body made of liquid crystal polyester as a forming material.

[Liquid crystal polyester]
The liquid crystal polyester, which is the material of the sound insulating member 1, is one of the thermotropic liquid crystal polymers, and can form a melt exhibiting optical anisotropy at a temperature of 450 ° C. or lower.

The liquid crystal polyester preferably has a repeating unit represented by the following general formula (1), and the repeating unit (1), the repeating unit represented by the following general formula (2), and the following general formula (3). It is more preferable to have a repeating unit represented by.
Hereinafter, the repeating unit represented by the following general formula (1) may be referred to as a “repeating unit (1)”.
The repeating unit represented by the following general formula (2) may be referred to as a "repeating unit (2)".
The repeating unit represented by the following general formula (3) may be referred to as a “repeating unit (3)”.

(1) -O-Ar ^1- CO-
(2) -CO-Ar ^2- CO-
(3) -X-Ar ^3- Y-
(In the formula, Ar ¹ represents a phenylene group, a naphthylene group or a biphenylylene group. ^{Ar 2} and Ar ³ are independently a phenylene group, a naphthylene group, a biphenylylene group or a group represented by the following general formula (4). X and Y each independently represent an oxygen atom or an imino group (-NH-). One or more hydrogen atoms in the group represented by ^{Ar 1} , Ar ² or Ar ^{3, respectively.} It may be independently substituted with a halogen atom, an alkyl group or an aryl group.)

(4) -Ar ^4- Z-Ar ^5-
(In the formula, Ar ⁴ and Ar ⁵ each independently represent a phenylene group or a naphthylene group.
Z represents an oxygen atom, a sulfur atom, a carbonyl group, a sulfonyl group or an alkylidene group. )

Specifically, as a liquid crystal polyester,
(1) A polymer obtained by polymerizing a combination of an aromatic hydroxycarboxylic acid, an aromatic dicarboxylic acid, and an aromatic diol.
(2) A polymer obtained by polymerizing a plurality of types of aromatic hydroxycarboxylic acids,
(3) A polymer obtained by polymerizing a combination of an aromatic dicarboxylic acid and an aromatic diol.
(4) Examples thereof include a polymer obtained by reacting a crystalline polyester such as polyethylene terephthalate with an aromatic hydroxycarboxylic acid.

In the production of the liquid crystal polyester, a part or all of the aromatic hydroxycarboxylic acid, the aromatic dicarboxylic acid and the aromatic diol used as the raw material monomer can be made into a derivative which easily forms an ester bond in advance and subjected to polymerization. .. By using such a derivative, there is an advantage that the liquid crystal polyester can be produced more easily.

The following compounds are exemplified as the above derivatives.

Examples of the aromatic hydroxycarboxylic acid and the derivative of the aromatic dicarboxylic acid include the carboxy group of the aromatic hydroxycarboxylic acid and the aromatic dicarboxylic acid, such as a haloformyl group (acid halide) and an acyloxycarbonyl group (acid anhydride). Examples include compounds converted to the highly reactive group of.

Further, as another example of the aromatic hydroxycarboxylic acid and the derivative of the aromatic dicarboxylic acid, the carboxy group of the aromatic hydroxycarboxylic acid and the aromatic dicarboxylic acid is a monohydric alcohol or a polyhydric alcohol such as ethylene glycol. Examples thereof include compounds in which an ester is formed with a class, a phenol, and the like. Such esters produce polyester by transesterification.

Examples of derivatives of aromatic hydroxycarboxylic acids and aromatic diols include compounds in which the phenolic hydroxyl groups of the aromatic hydroxycarboxylic acids and aromatic diols form esters with lower carboxylic acids. Such esters produce polyester by transesterification.

Further, as long as it does not inhibit ester formation, the above-mentioned aromatic hydroxycarboxylic acid, aromatic dicarboxylic acid or aromatic diol has a halogen atom such as a chlorine atom or a fluorine atom in its aromatic ring; a methyl group or an ethyl group. , An alkyl group having 1 to 10 carbon atoms such as a butyl group; an aryl group having 6 to 20 carbon atoms such as a phenyl group may be used as a substituent.

Examples of the aromatic hydroxycarboxylic acid include p-hydroxybenzoic acid, m-hydroxybenzoic acid, 6-hydroxy-2-naphthoic acid, 3-hydroxy-2-naphthoic acid, 5-hydroxy-1-naphthoic acid, and 4 -Hydroxy-4'-carboxydiphenyl ether can be mentioned. Further, an aromatic hydroxycarboxylic acid in which a part of hydrogen atoms in the aromatic ring of these aromatic hydroxycarboxylic acids is substituted with one or more substituents selected from the group consisting of an alkyl group, an aryl group and a halogen atom. Can be mentioned.

The p-hydroxybenzoic acid is an aromatic hydroxycarboxylic acid that induces _{(A 1) described later.}

6-Hydroxy-2-naphthoic acid is an aromatic hydroxycarboxylic acid that induces _{(A 2) described later.}

The above-mentioned aromatic hydroxycarboxylic acid may be used alone or in combination of two or more in the production of liquid crystal polyester.

The above-mentioned repeating unit (1) is a repeating unit derived from a predetermined aromatic hydroxycarboxylic acid. Examples of the repeating unit derived from the aromatic hydroxycarboxylic acid include the repeating units shown below. In the repeating unit derived from an aromatic hydroxycarboxylic acid, a part of the hydrogen atom in the aromatic ring is substituted with one or more substituents selected from the group consisting of a halogen atom, an alkyl group and an aryl group. You may.

In addition, in this specification, "origin" means that the chemical structure is changed due to the polymerization of the raw material monomer, and no other structural change occurs.

Examples of the aromatic dicarboxylic acid include terephthalic acid, isophthalic acid, biphenyl-4,4'-dicarboxylic acid, 2,6-naphthalenedicarboxylic acid, diphenyl ether-4,4'-dicarboxylic acid, and diphenylthioether-4,4'. -Dicarboxylic acid is mentioned. Further, an aromatic dicarboxylic acid in which a part of hydrogen atoms in the aromatic ring of these aromatic dicarboxylic acids is substituted with one or more substituents selected from the group consisting of an alkyl group, an aryl group and a halogen atom can be mentioned. Be done.

Terephthalic acid is an aromatic dicarboxylic acid that induces _{(B 1) described later.}

Isophthalic acid is an aromatic dicarboxylic acid that induces _{(B 2) described later.}

2,6-naphthalene dicarboxylic acid are aromatic dicarboxylic acids to induce the described later _{(B 3).}

The above-mentioned aromatic dicarboxylic acid may be used alone or in combination of two or more in the production of liquid crystal polyester.

The above-mentioned repeating unit (2) is a repeating unit derived from a predetermined aromatic dicarboxylic acid. Examples of the repeating unit derived from the aromatic dicarboxylic acid include the repeating units shown below. In the repeating unit derived from an aromatic dicarboxylic acid, a part of a hydrogen atom in the aromatic ring is substituted with one or more substituents selected from the group consisting of a halogen atom, an alkyl group and an aryl group. May be good.

Examples of the aromatic diol include 4,4'-dihydroxybiphenyl, hydroquinone, resorcin, 4,4'-dihydroxydiphenyl ketone, 4,4'-dihydroxydiphenyl ether, bis (4-hydroxyphenyl) methane, 1,2-. Examples thereof include bis (4-hydroxyphenyl) ethane, 4,4'-dihydroxydiphenylsulfone, 4,4'-dihydroxydiphenylthioether, 2,6-dihydroxynaphthalene and 1,5-dihydroxynaphthalene. In addition, an aromatic diol in which a part of hydrogen atoms in the aromatic ring of these aromatic diols is substituted with one or more substituents selected from the group consisting of an alkyl group, an aryl group and a halogen atom can be mentioned.

4,4'-Dihydroxybiphenyl is an aromatic diol that induces _{(C 1) described later.}

Hydroquinone is an aromatic diol that induces _{(C 2), which will be described later.}

Resorcin is an aromatic diol that induces _{(C 3) described below.}

The above-mentioned aromatic diol may be used alone or in combination of two or more in the production of liquid crystal polyester.

The repeating unit (3) described above includes a repeating unit derived from a predetermined aromatic diol. Examples of the repeating unit derived from the aromatic diol include the repeating unit shown below. In the repeating unit derived from an aromatic diol, even if a part of the hydrogen atom in the aromatic ring is substituted with one or more substituents selected from the group consisting of a halogen atom, an alkyl group and an aryl group. Good.

Substituents that the repeating unit derived from the aromatic hydroxycarboxylic acid, the repeating unit derived from the aromatic dicarboxylic acid, and the repeating unit derived from the aromatic diol may optionally have include the following substituents.
Examples of halogen atoms include fluorine atoms, chlorine atoms and bromine atoms.
Examples of the alkyl group include lower alkyl groups having 1 to 4 carbon atoms such as a methyl group, an ethyl group and a butyl group.
Examples of aryl groups include phenyl groups.

A particularly suitable liquid crystal polyester will be described.
As the repeating unit derived from the aromatic hydroxycarboxylic acid, the repeating unit derived from parahydroxybenzoic acid ((A ₁ )) and / or the repeating unit derived from 2-hydroxy-6-naphthoic acid ((A ₂ )). ) Is preferable.

The repeating unit derived from aromatic dicarboxylic acid includes a repeating unit derived from terephthalic acid ((B ₁ )), a repeating unit derived from isophthalic acid ((B ₂ )), and 2,6-naphthalenedicarboxylic acid ((B 1)). It is preferable to have a repeating unit selected from the group consisting of repeating units derived from _3)).

The repeating unit derived from the aromatic diol includes a repeating unit derived from hydroquinone ((C ₂ )) and a repeating unit derived from 4,4'-dihydroxybiphenyl or both ((C ₁ )). Is preferable.

And, as these combinations, the combinations represented by the following (a) to (h) are preferable. A liquid crystal polyester having good electrical insulation can be obtained by combining the repeating units of (a) to (h).

(A): A _{combination consisting of (A 1} ), (B ₁ ) and (C ₁ ), or a combination consisting of (A ₁ ), (B ₁ ), (B ₂ ) and (C ₁ ).
(B): A _{combination consisting of (A 2} ), (B ₃ ) and (C ₂ ), or a combination consisting of (A ₂ ), (B ₁ ), (B ₃ ) and (C ₂ ).
(C): A combination consisting of _{(A 1} ) and (A _2).
(D) in a combination of the repeating units of :( a), combinations replaced with _{(A 1)} of part or all _{(A 2).}
In combination with the repeating units of (e) :( a), combinations replaced with _{(B 1)} of part or all _{(B 3).}
In combination with the repeating units of (f) :( a), the combination obtained by replacing a part or all of _{(C 1)} with _{(C 3).}
(G) the combination of the repeating units of :( b), combinations replaced by (a part or all of the _{A 2) (A 1).}
(H): A combination in which (B ₁ ) and (C ₂ ) are added to the combination of the repeating units in (c).

As a particularly preferable liquid crystal polyester, the total number of repeating units derived from aromatic hydroxycarboxylic acid is 30 to 80 mol%, and the total number of repeating units derived from aromatic diol is 10 to 35 mol%, based on the total number of repeating units. %, Liquid polyesters in which the total number of repeating units derived from aromatic dicarboxylic acids is 10-35 mol%.

As a method for producing the liquid crystal polyester, for example, a known method such as the method described in JP-A-2002-146003 can be applied. That is, the above-mentioned raw material monomers (aromatic hydroxycarboxylic acid, aromatic dicarboxylic acid, aromatic diol or derivative for forming an ester thereof) are melt-polymerized (polycondensed) to have a relatively low molecular weight aromatic polyester (hereinafter referred to as). (Abbreviated as "prepolymer")) is then obtained, and the obtained prepolymer is powdered and subjected to solid phase polymerization by heating. By solid-phase polymerization in this way, the polymerization proceeds further, and a liquid crystal polyester having a higher molecular weight can be obtained.

In addition, regarding the method for producing a liquid crystal polyester having the combination of the repeating units of (a) and (b), which is the most basic structure, also published in Japanese Patent Publication No. 47-478870 and Japanese Patent Publication No. 63-3888. Are listed.

Melt polymerization may be performed in the presence of a catalyst. Examples of catalysts include metal compounds such as magnesium acetate, stannous acetate, tetrabutyl titanate, lead acetate, sodium acetate, potassium acetate and antimony trioxide, and 4- (dimethylamino) pyridine and 1-methylimidazole. Examples thereof include nitrogen-containing heterocyclic compounds. Of these, nitrogen-containing heterocyclic compounds are preferably used.

The liquid crystal polyester used for the sound insulation member is preferably a liquid crystal polyester having a flow start temperature of 280 ° C. or higher, which is obtained by the following method. As described above, when solid phase polymerization is used in the production of the liquid crystal polyester, the flow start temperature of the liquid crystal polyester can be set to 280 ° C. or higher in a relatively short time. Then, by using the liquid crystal polyester having such a flow start temperature, the obtained molded product becomes a molded product having a high degree of heat resistance. On the other hand, in terms of molding the molded product in a practical temperature range, the flow start temperature of the liquid crystal polyester used for the sound insulating member is preferably 420 ° C. or lower, and more preferably 390 ° C. or lower.

Here, the flow start temperature is a liquid crystal polyester at a heating rate of 4 ° C./min under a load of ^{9.8 MPa (100 kg / cm 2} ) using a capillary rheometer equipped with a die having an inner diameter of 1 mm and a length of 10 mm. Is a temperature at which the melt viscosity shows 4800 Pa · s (48,000 poise) when extruded from the nozzle. The flow start temperature is an index showing the molecular weight of liquid crystal polyester, which is well known in the art (edited by Naoyuki Koide, "Liquid Crystal Polymer Synthesis / Molding / Application-", pp. 95-105, 1987, June 1987. See issue on the 5th). As an apparatus for measuring the flow start temperature, for example, a flow characteristic evaluation apparatus “Flow Tester CFT-500D” manufactured by Shimadzu Corporation can be used.

[Filler]
The sound insulating member may contain a filler. When the sound insulating member contains a filler, sufficient strength can be imparted to the sound insulating member.

The filler may be an inorganic filler or an organic filler. Further, it may be a fibrous filler, a plate-shaped filler, or a granular filler.

Examples of fibrous fillers include glass fibers; carbon fibers such as pan-based carbon fibers and pitch-based carbon fibers; ceramic fibers such as silica fibers, alumina fibers and silica-alumina fibers; and metal fibers such as stainless steel fibers. .. Further, whiskers such as potassium titanate whiskers, barium titanate whiskers, wollast night whiskers, aluminum borate whiskers, silicon nitride whiskers, and silicon carbide whiskers can also be mentioned.

Examples of plate-shaped fillers include talc, mica, graphite, wollastonite, barium sulfate, calcium carbonate and the like. The mica may be muscovite, phlogopite, fluorine phlogopite, or tetrasilicon mica.

Examples of granular fillers include silica, alumina, titanium oxide, boron nitride, silicon carbide and calcium carbonate.

[Other ingredients]
The sound insulating member may contain other components that do not correspond to either the liquid crystal polyester or the filler as long as the effects of the present invention are not impaired.

Examples of the above other components include mold release improvers such as fluororesins and metal soaps; colorants such as dyes and pigments; antioxidants; heat stabilizers; ultraviolet absorbers; antistatic agents; surfactants and the like. Examples thereof include additives generally used for resin molded products.

Further, examples of the above other components include compounds having an external lubricant effect such as higher fatty acids, higher fatty acid esters, higher fatty acid metal salts, and fluorocarbon-based surfactants.

Further, examples of the above other components include thermosetting resins such as phenol resin, epoxy resin, and polyimide resin.

As the material of the sound insulation member, a mixture of liquid crystal polyester, a filler, and other components used as necessary, collectively or in an appropriate order, is used.

As the material of the sound insulation member, it is preferable to pelletize the liquid crystal polyester, the filler, and other components used as necessary by melting and kneading them using an extruder.

FIG. 2 is a schematic view showing a cross section of the sound insulation member 1. As shown in the figure, the sound insulating member 1 has a core layer 11 formed on the inner layer of the molded body and an orientation layer 12 formed on the surface of the molded body in the thickness direction of the molded body.

The alignment layer 12 is formed on both sides of the molded body in the thickness direction with respect to the core layer 11. The liquid crystal polyester forming the alignment layer 12 is more oriented than the liquid crystal polyester forming the core layer 11.

(Method of distinguishing core layer and orientation layer)
The core layer 11 and the orientation layer 12 are distinguished as follows.

First, the molded body is cut to prepare a cross section in a direction parallel to the MD, with the resin flow direction as MD and the resin flow direction as TD.

(Discrimination of MD)
The direction parallel to MD in the molded body can be determined by, for example, analyzing the surface of the molded body by an Attenuated Total Reflection (ATR method) and analyzing the orientation of the molecular chains of the liquid crystal polyester. A Fourier transform infrared spectroscopic analyzer (for example, FastImageIR, manufactured by Agilent Technologies) can be used for the measurement of the molded product.

Specifically, first, the surface of the molded body is irradiated with polarized light, and ^{the absorbance corresponding to the ester group (infrared absorption: 1732 cm -1} ) in a posture perpendicular to the surface of the molded body and the posture parallel to the surface of the molded body are obtained. The absorbance corresponding to the ether group (infrared absorption: 1152 cm ^{-1) is measured.}

Next, the ratio of the absorbance of the ether group to the absorbance of the ester group (absorbance ratio = (absorbance of the ether group) / (absorbance of the ester group)) is determined. The surface of the molded body is irradiated with polarized light in a plurality of polarization directions, the absorbance ratio is obtained for each polarization direction, and the polarization direction at which the absorbance ratio is maximized is determined to be MD. According to the judgment result, the molded body is cut to prepare a cross section in a direction parallel to the MD.

(Discrimination of core layer and orientation layer)
Next, the prepared cross section is analyzed by the ATR method, and the orientation of the molecular chains of the liquid crystal polyester is analyzed. For the measurement of the molded body, a Fourier transform infrared spectroscopic analyzer (for example, FastImageIR, manufactured by Agilent Technologies) used for discriminating the direction parallel to the MD can be used.

Specifically, a plurality of locations of the prepared cross section are irradiated with polarization in a direction parallel to the MD, and the absorbance corresponding to the ester group having a posture perpendicular to the prepared cross section and the ether group having a posture parallel to the cross section are supported. Measure the absorptiometry.

Next, determine the absorbance ratio = (absorbance of ether group) / (absorbance of ester group) for each measured location. The region having a constant width from the surface of the molded product and having an absorbance ratio of 1.05 or more is defined as the alignment layer 12. Further, the remaining region is designated as the core layer 11. The core layer 11 has the above-mentioned absorbance ratio of less than 1.05.

As a result of studies to improve the sound insulation performance of the sound insulation member, the inventors have found that the elastic modulus of the core layer 11 and the elastic modulus of the alignment layer 12 of the sound insulation member 1 showing high sound insulation performance show an optimum relationship. I found out.

That is, in the sound insulating member 1, the ratio of the elastic modulus of the core layer 11 to the elastic modulus of the molded body constituting the sound insulating member 1 is 0.60 or more and 0.95 or less.

The "molded body constituting the sound insulating member 1" has a core layer 11 and an orientation layer 12. The oriented layer 12 is more oriented than the core layer 11 and exhibits a relatively higher elastic modulus than the core layer 11. Therefore, the elastic modulus of the molded body (= sound insulating member 1) having the core layer 11 and the alignment layer 12 is higher than the elastic modulus of the core layer 11 alone. In other words, in the molded body constituting the sound insulating member 1, it can be said that the core layer 11 which is relatively softer than the oriented layer 12 is formed in the hard oriented layer 12.

The sound insulation member 1 exhibits higher sound insulation than the sound insulation member 1 that does not satisfy this requirement because the elastic modulus ratio is 0.60 or more and 0.95 or less.

The elastic modulus ratio is preferably 0.65 or more, and more preferably 0.70 or more. The elastic modulus ratio is preferably 0.945 or less, more preferably 0.94 or less, and even more preferably 0.90 or less.

The upper limit value and the lower limit value of the elastic modulus ratio can be arbitrarily combined.
For example, the elastic modulus ratio may be 0.60 or more and 0.945 or less, 0.60 or more and 0.94 or less, or 0.60 or more and 0.90 or less. ..

The elastic modulus ratio may be 0.65 or more and 0.95 or less, 0.65 or more and 0.945 or less, or 0.65 or more and 0.94 or less. , 0.65 or more and 0.90 or less.

The elastic modulus ratio may be 0.70 or more and 0.95 or less, 0.70 or more and 0.945 or less, or 0.70 or more and 0.94 or less. , 0.70 or more and 0.90 or less.

The elastic modulus ratio may be 0.80 or more and 0.95 or less, 0.80 or more and 0.945 or less, or 0.80 or more and 0.94 or less. , 0.80 or more and 0.90 or less.

For example, it is preferably 0.65 or more and 0.945 or less, more preferably 0.70 or more and 0.94 or less, and further preferably 0.70 or more and 0.90 or less.

The elastic modulus of the sound insulating member 1 can be measured by, for example, the following method.

For the sound insulation member 1, MD is determined by the above method. A test piece having a width of 10 mm and a length exceeding [thickness of sound insulating member 1 (unit: mm)] × 15.6 is cut out from the sound insulating member 1 by matching the long sides with MD and TD, respectively.

The length of the test piece shall exceed the inter-span distance described later. For example, the test piece has a width of 10 mm, a length of 100 mm, and a thickness of 1.6 mm. The cut out test pieces are used as a test piece for evaluating the elastic modulus in the MD direction and a test piece for evaluating the elastic modulus in the TD direction for the sound insulation member 1.

In the following description, the elastic modulus in the MD direction may be referred to as "MD elastic modulus", and the elastic modulus in the TD direction may be referred to as "TD elastic modulus".

Also, the sound insulation member 1 is cut to create a cross section in the direction parallel to the MD. The prepared cross section is analyzed by the method described above to determine the thickness of the alignment layer.

Based on the obtained thickness of the alignment layer, the alignment layer of the above-mentioned test piece for elastic modulus evaluation is removed by polishing with sandpaper to prepare a test piece for evaluation of elastic modulus of the core layer. The test piece is prepared by roughly removing the alignment layer using sandpaper having an abrasive having a particle size of 320, and then polishing using sandpaper having an abrasive having a particle size of 1000 or 1500 in order. There are two types of test pieces for evaluating the elastic modulus of the core layer: a test piece for evaluating the elastic modulus of MD whose long side matches MD and TD, and a test piece for evaluating the elastic modulus of TD.

(Measuring method of elastic modulus)
The elastic modulus is determined by a three-point bending test.
The elastic modulus for evaluating the elastic modulus is measured three times using a universal testing machine (for example, Tencilon RTG-1250, manufactured by A & D Co., Ltd.) to obtain the arithmetic mean value of the measured values. To do.

Using the test piece described above, the MD elastic modulus of the sound insulation member 1 and the TD elastic modulus of the sound insulation member 1 are obtained. The arithmetic mean value of the MD elastic modulus and the TD elastic modulus is defined as the elastic modulus of the sound insulating member 1.

Similarly, using the test piece described above, the MD elastic modulus for the core layer and the TD elastic modulus for the core layer are obtained. The arithmetic mean value of the MD elastic modulus and the TD elastic modulus is defined as the elastic modulus of the core layer.

The measurement conditions for elastic modulus are the distance between spans = [test piece thickness (unit: mm)] x 15.6, and the test speed = 1 mm / min.

From the elastic modulus of the sound insulating member 1 obtained as described above and the elastic modulus of the core layer, the ratio of the elastic modulus of the core layer to the elastic modulus of the molded body is obtained.

The sound insulation of the sound insulation member 1 can be evaluated by, for example, the following method.

FIG. 3 is a schematic view showing a method for evaluating the sound insulation property of the sound insulation member 1. FIG. 3 shows a case where the sound insulation member 1 is a flat plate as an example of the sound insulation member 1. When the sound insulating member 1 has the same structure as the flat plate used in this evaluation method, the same sound insulating property can be expected for the sound insulating member 1.

First, the same resin composition as the material for forming the sound insulating member 1 is injection-molded using pellets obtained by melt-kneading to form a flat plate (molded body A) having a size of 100 mm × 100 mm × 1.6 mm. At the time of molding, the average resin speed described later is controlled. The obtained flat plate is evaluated as a model of the sound insulation member 1.

Two rectangular parallelepiped simple silent chambers 100 and 110 are used for the evaluation of sound insulation. The simple silent chambers 100 and 110 have the same outer shape and the same volume of the internal spaces 100x and 110x.

As a simple silent room, for example, a speaker box (model number: P650-E) manufactured by FOSTEX is used. Urethane soundproofing material will be installed on the inner wall of the simple silent room.

A circular through hole 100a having a diameter of 60 mm is provided at the center of one wall 101 of the simple silent chamber 100. Further, a speaker 200 is attached to the center of the wall 102 facing the wall 101.

A circular through hole 110a having a diameter of 60 mm is provided at the center of one wall 111 of the simple silent chamber 110. A microphone 300 is attached to the center of the wall 112 facing the wall 111.

The simple silence chamber 100 and the simple silence chamber 110 are arranged so that the through hole 100a and the through hole 110a face each other. Further, the simple silent chamber 100, the molded body A, and the simple silent chamber 110 are arranged in this order, and the molded body is formed by the simple silent chamber 100 and the simple silent chamber 110 at a height position where the through hole 100a and the through hole 110a face each other. Hold A in between.

Next, the sound S1 of 100 Hz to 10000 Hz is irradiated from the speaker 200 inside the simple silent room 100. The microphone 300 inside the simple silent chamber 110 collects the sound S2 that is irradiated from the speaker 200 and transmitted to the simple silent chamber 110 via the molded body A. Using the measurement results, the sound insulation (dB), which is the difference between the sound pressure level (dB) of the sound S1 incident on the molded body A and the sound pressure level (dB) of the sound S2 transmitted through the molded body A, is obtained. Evaluate sound insulation.

In the sound insulation evaluation, the sound insulation member 1 may evaluate the sound insulation of a desired frequency mainly according to the frequency of the sound to be insulated. For example, when the main purpose of the sound insulation member 1 is to insulate metal sound, the sound insulation property of the molded body is evaluated by measuring the sound S2 at 2000 Hz when the sound S1 at 2000 Hz is irradiated, and obtaining the sound insulation. To do.

Note that the above "2000 Hz" is an example, and when the frequency of the metal sound to be sound-insulated is known, it is advisable to obtain the sound insulation of the sound of the target frequency and evaluate the sound insulation.

In evaluating the sound insulation, a flat plate with a higher volume than the steel plate is evaluated as a good product, and a flat plate with a volume equal to or lower than that of the steel plate is evaluated as a defective product based on the sound insulation volume "10 dB" of the steel plate separately evaluated as a reference value. .. The dimensions of the steel plate used are 100 mm × 100 mm × 0.8 mm thick.

The sound insulating member 1 preferably has an elastic modulus of 3000 or more as a whole.
Further, in the sound insulating member 1, the elastic modulus of the core layer 11 is preferably 1000 or more. Usually, the elastic modulus of the molded product and the core layer 11 is 30,000 or less.

That is, the elastic modulus of the sound insulating member 1 is preferably 3000 or more and 30,000 or less.
Further, the elastic modulus of the core layer of the sound insulation member 1 is preferably 1000 or more and 30,000 or less.

The elastic modulus ratio can be adjusted by changing the type of filler to be added, the blending amount of the filler, and one or more of the molding conditions described later.

Among the above-mentioned fillers, the fibrous filler such as glass filler is more likely to be dispersed in the core layer 11 than the alignment layer 12. Therefore, when the amount of the fibrous filler contained in the sound insulating member 1 is increased, the elastic modulus of the core layer 11 tends to increase, and as a result, the ratio of the elastic modulus tends to increase.

Further, among the above-mentioned fillers, the plate-shaped filler such as mica is more easily dispersed in the alignment layer 12 than the core layer 11. Therefore, if the amount of the plate-shaped filler contained in the sound insulating member 1 is increased, the elastic modulus of the alignment layer 12 tends to increase. As a result, the elastic modulus ratio tends to be small.

Further, among the above-mentioned fillers, a granular filler such as alumina is equally likely to be dispersed in the core layer 11 and the alignment layer 12. On the other hand, the granular filler has a smaller effect of increasing the elastic modulus of the sound insulating member 1 even if the amount is increased, as compared with the fibrous filler and the plate-shaped filler. When the amount of the granular filler contained in the sound insulating member 1 is increased, the ratio of the elastic moduli tends to be small.

The thickness of the sound insulating member 1 is preferably 1.0 mm or more, more preferably 1.5 mm or more, in order to enhance mechanical properties such as sound insulation and strength as a structural material. Usually, the thickness of the sound insulating member 1 is 5.0 mm or less.

[Manufacturing method of sound insulation member]
The method for manufacturing the sound insulating member 1 includes a step of injection molding a molten resin of a liquid crystal polyester composition containing a liquid crystal polyester. Further, in the method for manufacturing the sound insulating member 1, the average resin speed in the mold when the molten resin of the liquid crystal polyester composition is injected into the mold is controlled to 100 mm / sec or more and 500 mm / sec or less. That is, the average resin velocity in the mold of the molten resin is 100 mm / sec or more and 500 mm / sec or less.

The above-mentioned "average resin rate in the mold" is the injection speed when the molten resin is filled in the mold, the temperature of the mold, and the size of the cavity of the mold (= the size of the molded product to be molded). Is required from.

When injection molding is performed using a specific mold, the size of the mold cavity is a fixed value. Therefore, the average resin rate in the mold can be adjusted by controlling one or both of the injection speed and the temperature of the mold.

Increasing the injection speed tends to increase the average resin speed in the mold, and decreasing the injection speed tends to decrease the average resin speed in the mold.

When the temperature of the mold is raised, the average resin speed in the mold tends to increase, and when the temperature of the mold is lowered, the average resin speed in the mold tends to decrease. The temperature of the mold tends to affect the cooling (solidification) of the resin. The higher the temperature of the mold, the more the solidification of the molten resin flowing into the cavity can be delayed, and the average resin speed of the molten resin in the cavity can be increased.

^{"Average resin speed" is the filling speed (mm 3} / sec) of molten resin calculated from "injection speed of injection molding machine" and "cylinder diameter of injection molding machine" in terms of the cross-sectional area of the cavity (mm ² ). It can be calculated by dividing.

The faster the average resin velocity in the mold, the smaller the ratio of the elastic moduli tends to be. When the average resin rate is high, the liquid crystal polyester is likely to be oriented, and as a result, the difference in elastic modulus between the oriented layer and the core layer is large, that is, the ratio of the elastic modulus is small.

When the average resin speed in the mold is 100 mm / sec or more, the resin and the filler are appropriately oriented, and the elastic modulus of the molded product tends to be difficult to become excessively high.
Further, when the average resin speed in the mold is 500 mm / sec or less, the alignment layer does not become too thin, and a molded product having an appropriate elastic modulus is obtained.

The average resin speed in the mold is preferably 100 mm / sec or more, more preferably 110 mm / sec or more, further preferably 120 mm / sec or more, further preferably 180 mm / sec or more, and particularly preferably 240 mm / sec or more. The average resin speed in the mold is preferably 500 mm / sec or less, more preferably 480 mm / sec or less, and even more preferably 400 mm / sec or less.

The upper and lower limits of the average resin speed in the mold can be combined arbitrarily.

The average resin speed in the mold may be 100 mm / sec or more and 500 mm / sec or less, 100 mm / sec or more and 480 mm / sec or less, or 100 mm / sec or more and 400 mm / sec or less. ..

The average resin speed in the mold may be 110 mm / sec or more and 500 mm / sec or less, 110 mm / sec or more and 480 mm / sec or less, or 110 mm / sec or more and 400 mm / sec or less. May be good.

The average resin speed in the mold may be 120 mm / sec or more and 500 mm / sec or less, 120 mm / sec or more and 480 mm / sec or less, or 120 mm / sec or more and 400 mm / sec or less. May be good.

The average resin speed in the mold may be 180 mm / sec or more and 500 mm / sec or less, 180 mm / sec or more and 480 mm / sec or less, or 180 mm / sec or more and 400 mm / sec or less. May be good.

The average resin speed in the mold may be 240 mm / sec or more and 500 mm / sec or less, 240 mm / sec or more and 480 mm / sec or less, or 240 mm / sec or more and 400 mm / sec or less. May be good.

The average resin velocity in the mold is, for example, preferably 100 mm / sec or more and 500 mm / sec or less, more preferably 110 mm / sec or more and 500 mm / sec or less, more preferably 120 mm / sec or more and 480 mm / sec or less, and 180 mm / sec or more. It is more preferably 480 mm / sec or less, and further preferably 240 mm / sec or more and 400 mm / sec or less.

Further, the injection speed may be changed between the initial stage of molding and the latter stage of molding. By changing the injection speed between the early stage and the late stage of molding, it becomes easy to control the ratio of the elastic modulus of the core layer 11 to the elastic modulus of the molded body constituting the obtained sound insulation member 1 within a suitable range.

Even when the injection speed is changed as described above, the average resin speed in the mold is controlled to 100 mm / sec or more and 500 mm / sec or less in the entire injection molding.

Further, by controlling the average resin speed in the mold, the sound insulation member 1 can be easily manufactured.

According to the sound insulation member 1 having the above configuration, the liquid crystal polyester is used as a forming material, and the sound insulation member exhibits excellent sound insulation.

Further, according to the above-mentioned manufacturing method of the sound insulating member, the above-mentioned sound insulating member can be easily manufactured.

Although the motor cover and gear box have already been exemplified as the sound insulation member 1, the sound insulation member 1 is not limited to this.

The sound insulation member 1 is applied to vehicle parts, and is suitable for use in blocking sounds transmitted from a sound source to a driver or a passenger (for example, metal sounds from an engine or a gearbox, typically sounds having a frequency of around 2000 Hz). Used. Examples of such a sound insulating member 1 include an engine cover that mainly uses an engine as a sound source.

Further, as the sound insulating member 1 which is a vehicle component, an outer plate for blocking the sound transmitted from the outside of the vehicle to the riding space can be mentioned. Examples of the outer panel include roofs and doors.

When the sound insulation member 1 is applied to these members, it is possible to achieve both weight reduction due to being a resin molded body and high sound insulation.

In addition, examples of the sound insulation member 1 include an acoustic member such as a speaker and a building member having high sound insulation.

Although the preferred embodiment of the present invention has been described above with reference to the accompanying drawings, the present invention is not limited to such an example. The various shapes and combinations of the constituent members shown in the above examples are examples, and can be variously changed based on the product design, product specifications, etc. within the range not deviating from the gist of the present invention.

The present invention will be described below with reference to examples, but the present invention is not limited to these examples.

<Evaluation 1>
(Examples 1 to 8, Comparative Examples 1 and 2)
(Manufacturing of liquid crystal polyester)
994.5 g (7.2 mol) of parahydroxybenzoic acid, 446.9 g (2) of 4,4'-dihydroxybiphenyl in a reactor equipped with a stirrer, torque meter, nitrogen gas introduction tube, thermometer and reflux condenser. .4 mol), 299.0 g (1.8 mol) of terephthalic acid, 99.7 g (0.6 mol) of isophthalic acid and 1347.6 g (13.2 mol) of anhydrous acetic acid were added.

After replacing the inside of the reactor with nitrogen gas, 0.18 g of 1-methylimidazole was added under a nitrogen gas stream, the temperature was raised to 150 ° C. over 30 minutes, and the mixture was refluxed for 30 minutes while maintaining that temperature.

Next, after adding 2.4 g of 1-methylimidazole, the mixture in the reactor was heated to 320 ° C. over 2 hours and 50 minutes while distilling off distillate by-product acetic acid and unreacted acetic anhydride. The time when an increase in torque was observed was regarded as the end of the reaction, and the contents were taken out.

The obtained solid content was cooled to room temperature and crushed with a coarse crusher. Then, the crushed solid content is heated in a nitrogen atmosphere from room temperature to 250 ° C. over 1 hour, further heated from 250 ° C. to 295 ° C. over 5 hours, and then held at 295 ° C. for 3 hours to solidify. Phase polymerization proceeded. The reaction product was then cooled to give a liquid crystal polyester.

(Manufacturing of liquid crystal polyester resin composition)
The liquid crystal polyester and the filler are mixed at the ratios shown in Table 1 below, and the obtained mixture is melt-kneaded using a twin-screw extruder (model number: PCM-30, manufactured by Ikegai Co., Ltd.). , A pellet of a liquid crystal polyester composition was produced.

Each numerical value in Table 1 shows the mass% of each composition with respect to the whole composition. The materials used are as follows.
PES: Sumika Excel 3601GL30 (manufactured by Sumitomo Chemical Co., Ltd.)
Glass filler: CS03JAPX-1 (manufactured by Owens Corning)
Mica: A-41S (manufactured by Yamaguchi Mica)
Al ₂ O ₃ : ALM-41 (manufactured by Sumitomo Chemical Co., Ltd.)

The melt-kneading conditions were that the cylinder set temperature of the twin-screw extruder was 340 ° C and the screw rotation speed was 150 rpm. The "cylinder set temperature" means the arithmetic mean value of the set temperature of the heating device (cylinder heater) provided from the downstream side of the cylinder to the portion of about 2/3 of the cylinder length.

(Molding of test piece)
The obtained pellets were molded using an injection molding machine (model number: UH1000, manufactured by Nissei Resin Industry Co., Ltd.) under the conditions of a molding temperature of 340 ° C. and a mold temperature of 130 ° C., and a flat plate (100 mm × 100 mm × 1.6 mm) (100 mm × 100 mm × 1.6 mm). Molded body) was molded. The side of the molded flat plate having a length of 100 mm coincided with MD and TD, respectively.
The average resin rate was 240 mm / sec.

(Measurement of elastic modulus)
(1) Method for producing test piece 1
From the two molded flat plates, a test piece of 10 mm × 100 mm × 1.6 mm was cut out with the long sides matching the MD and TD, respectively, and the test piece for evaluating the MD elastic modulus of the flat plate (molded body) and the flat plate (molding) A test piece for evaluating the TD elastic modulus of the body) was prepared.

(2) Method for producing test piece 2
A flat plate was cut to prepare a cross section in a direction parallel to the MD.

Next, the prepared cross section was analyzed by the microscopic total reflection measurement method (Attenuated Total Reflection, ATR method), and the orientation of the molecular chains of the liquid crystal polyester was analyzed. A Fourier transform infrared spectroscopic analyzer (for example, FastImageIR, manufactured by Agilent Technologies) was used for the measurement.

Specifically, first, a plurality of places of the prepared cross section were irradiated with polarized light parallel to the cross section (MD) and spectroscopically analyzed. In the analysis, the absorbance corresponding to the ester group (infrared absorption: 1732 cm ^-1 ) perpendicular to the irradiated polarized light and the ether group corresponding to the ether group parallel to the irradiated polarized light (infrared absorption: 1152 cm ^-1 ) are supported. The absorbance was measured.

The ester group having a posture perpendicular to the polarized light is perpendicular to the prepared cross section. Further, the ether group having a posture parallel to the polarized light is parallel to the prepared cross section.

Next, the absorbance ratio = (absorbance of ether group) / (absorbance of ester group) was determined for each measurement location. The region having a constant width from the surface of the molded product and having an absorbance ratio of 1.05 or more was defined as the alignment layer, and the thickness of the alignment layer was determined.

Based on the obtained thickness of the alignment layer, the alignment layer of the above-mentioned test piece for elastic modulus evaluation was removed by polishing with sandpaper to prepare a test piece for evaluation of elastic modulus of the core layer. There are two types of test pieces for evaluating the elastic modulus of the core layer: a test piece for evaluating the MD elastic modulus of the core layer and a test piece for evaluating the TD elastic modulus of the core layer. The test piece for evaluating the MD elastic modulus of the core layer has a long side that matches MD, and the test piece for evaluating the TD elastic modulus of the core layer has a long side that matches TD.

(3) Measurement of elastic modulus The elastic modulus was determined according to the above description (method for measuring elastic modulus).

(Ratio of the elastic modulus of the core layer to the elastic modulus of the molded product)
From the elastic modulus of the flat plate obtained as described above and the elastic modulus of the core layer, the ratio of the elastic modulus of the core layer to the elastic modulus of the flat plate (molded body) was determined.

(Sound insulation evaluation)
FIG. 3 is a schematic view showing a method for evaluating sound insulation. In this example, the sound insulation was evaluated using a flat plate (molded body A) of 100 mm × 100 mm × 1.6 mm produced by the above method.

Two rectangular parallelepiped simple silent chambers 100 and 110 were used for the evaluation of sound insulation. The simple silent chambers 100 and 110 have the same outer shape and the same volume of the internal spaces 100x and 110x.

A speaker box (model number: P650-E) manufactured by FOSTEX was used as a simple silent room. Urethane soundproofing material was installed on the inner wall of the simple silent room.

The simple silent chamber 100 was provided with a circular through hole 100a having a diameter of 60 mm at the center of one wall 101 of the simple silent chamber 100. Further, a speaker 200 was attached to the center of the wall 102 facing the wall 101.

The simple silent chamber 110 was provided with a circular through hole 110a having a diameter of 60 mm at the center of one wall 111 of the simple silent chamber 110. A microphone 300 was attached to the center of the wall 112 facing the wall 111.

In the simple silence chamber 100 and the simple silence chamber 110, the through hole 100a and the through hole 110a are arranged so as to face each other. Further, the simple silent chamber 100, the molded body A, and the simple silent chamber 110 are arranged in this order, and the molded body is formed by the simple silent chamber 100 and the simple silent chamber 110 at a height position where the through hole 100a and the through hole 110a face each other. I sandwiched A.

The sound S1 of 100 Hz to 10000 Hz was irradiated from the speaker 200, and the sound S2 transmitted to the simple silent chamber 110 via the molded body A was collected by the microphone 300. The sound insulation (dB), which is the difference between the sound pressure level (dB) of the sound S1 incident on the molded body A and the sound pressure level (dB) of the sound S2 transmitted through the molded body A, was obtained and the sound insulation was evaluated. In this embodiment, the sound insulation of the molded product was evaluated by measuring the sound S2 at 2000 Hz when the sound S1 at 2000 Hz was irradiated, and determining the sound insulation.

In the evaluation of sound insulation, a flat plate with a higher volume than the steel plate was evaluated as a good product, and a flat plate with a volume equal to or less than that of the steel plate was evaluated as a defective product based on the sound insulation volume "10 dB" of the steel plate separately evaluated as a reference value. .. The dimensions of the steel plate used were 100 mm × 100 mm × 0.8 mm thick.

Table 2 shows the elastic modulus of each molded product used for the evaluation.
Further, Table 3 shows the evaluation results of sound insulation.

It was found that the flat plates of Examples 1 to 8 had clearly better sound insulation than the steel plate and were useful as a substitute for metal parts. On the other hand, it was found that the flat plates of Comparative Examples 1 and 2 had low sound insulation.

<Evaluation 2>
(Examples 9 and 10, Comparative Example 3)
Using the same pellets as those used in Example 3 of Evaluation 1 above, flat plates with different injection molding conditions were prepared. The obtained flat plate was evaluated in the same manner as in Evaluation 1.

(Comparative Example 4)
A flat plate was prepared by hot pressing using the same pellets as those used in Example 3 of Evaluation 1 above. The obtained flat plate was evaluated in the same manner as in Evaluation 1.

The evaluation results are shown in Table 4.

As a result of the evaluation, the flat plates of Examples 9 and 10 having an average resin speed of 100 mm / sec or more and 500 mm / sec or less showed good sound insulation.

On the other hand, the flat plate of Comparative Example 3 having an average resin speed of 950 mm / sec had the same sound insulation as the steel plate.

Further, the flat plate of Comparative Example 4 which was not injection-molded had the same sound insulation as the steel plate.

<Evaluation 3>
(Examples 11 to 16)
Using the same pellets used in Example 3 of Evaluation 1 above, the injection speed was set to 50 mm / sec at the initial stage of molding and changed to 150 mm / sec during molding to prepare a flat plate. The average resin rate was maintained at 240 mm / sec for the entire injection molding. The obtained flat plate was evaluated in the same manner as in Evaluation 1.

The evaluation results are shown in Table 5.

As a result of the evaluation, since the flat plates of Examples 11 to 16 satisfy the average resin speed of 100 mm / sec or more and 500 mm / sec or less, they showed good sound insulation even if the injection speed was changed during molding.

From the above results, it was found that the present invention is useful.

1 ... Sound insulation member, 11 ... Core layer, 12 ... Alignment layer, 100 ... Simple silent chamber, 100a ... Through hole, 100x ... Internal space, 101 ... Wall, 102 ... Wall, 110 ... Simple silent chamber, 110a ... Through hole, 110x ... internal space, 111 ... wall, 112 ... wall, 200 ... speaker, 300 ... microphone, A ... molded body, S1 ... sound, S2 ... sound, X ... sound source

Claims (3)

1. A molded product made of liquid crystal polyester as a forming material.
   A core layer formed in the inner layer of the molded body and
   It has an orientation layer formed on the surface of the molded product, and has
   The liquid crystal polyester forming the alignment layer is more oriented than the liquid crystal polyester forming the core layer.
   A sound insulating member in which the ratio of the elastic modulus of the core layer to the elastic modulus of the molded product is 0.60 or more and 0.95 or less.
2. The sound insulation member according to claim 1, which is a vehicle component.
3. Including the step of injection molding the molten resin of the liquid crystal polyester composition containing the liquid crystal polyester,
   A method for manufacturing a sound insulating member, wherein the average resin speed in the mold of the molten resin is 100 mm / sec or more and 500 mm / sec or less.

Images