Liquid crystal polyester pellets and foamed molded products

Abstract

To provide a liquid crystal polyester pellet that is useful as a master batch for chemical foam molding, and a foamed molding product prepared using the liquid crystal polyester pellet.SOLUTION: A liquid crystal polyester pellet contains liquid crystal polyester (A) and a foamer (B), the foamer (B) containing a bistetrazole compound (B1).SELECTED DRAWING: None

Description

[Technical Field]

[0001] This invention relates to liquid crystal polyester pellets and foamed molded articles. [Background technology]

[0002] Liquid crystal polyester is known for its high fluidity, heat resistance, and dimensional accuracy. Liquid crystal polyester is rarely used on its own; instead, it is used as a liquid crystal polyester composition containing fillers or other materials to meet the required properties (e.g., bending properties, impact resistance) for various applications. Molded articles made from such liquid crystal polyester compositions are known to be lightweight yet strong. Such liquid crystal polyester compositions are seeing increasing use as molding materials in a variety of applications. In particular, in the field of transportation equipment, including automobiles and aircraft, there is a growing demand for lightweight molded products to improve fuel efficiency.

[0003] In response to this, foam molding of liquid crystal polyester compositions is being considered with the aim of reducing the weight of molded products while taking advantage of the properties of liquid crystal polyester.

[0004] Foam molding methods are broadly classified into chemical foam molding, which uses chemical foaming agents such as ADCA (azodicarbonamide) and sodium bicarbonate mixed with resin materials, and physical foam molding, which injects inert gases such as nitrogen and carbon dioxide (physical foaming agents) through cylinders or nozzles.

[0005] For example, Patent Document 1 discloses a method for manufacturing a foam-molded product that continuously molds a foam-molded product, including a step 1 of melting a resin composition containing a liquid crystal polyester, and a step of melting a resin composition containing a liquid crystal polyester. A foaming agent composed of a supercritical fluid that is non-reactive with the liquid crystal polyester in a supercritical state of 0.1 part by mass or more and 0.3 part by mass or less with respect to 100 parts by mass of the liquid crystal polyester and is a gas at normal temperature and pressure is introduced using an introduction device and melt-kneaded in step 2, a step 3 of injecting the melt-kneaded resin composition into a mold, and a step 4 of foaming by reducing at least one of the pressure and temperature of the foaming agent below the critical point of the foaming agent. A method for manufacturing a foam-molded product by physical foam molding is disclosed.

[0006] Further, Patent Document 2 discloses a liquid crystal polyester resin foam-molded product obtained by introducing a liquid crystal polyester resin having a specific structure and a supercritical fluid into an injection molding machine and performing injection molding.

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0008] However, when using physical foam molding as described in Patent Document 1 or using a supercritical fluid as described in Patent Document 2, it is necessary to introduce special equipment, and the cost tends to be high.

[0009] On the other hand, when attempting chemical foam molding of a liquid crystal polyester composition, there are the following problems. For example, if one attempts to perform chemical foam molding using a material obtained by dry-blending a pellet containing liquid crystal polyester and a foaming agent as described in the comparative example of Patent Document 2, the chemical foaming agent does not disperse well in the liquid crystal polyester, making it difficult to foam the liquid crystal polyester finely and uniformly. Furthermore, because liquid crystal polyester has a higher flow initiation temperature compared to other thermoplastic resins, even if one attempts to perform chemical foam molding by adapting a general chemical foaming agent used for other thermoplastic resins to liquid crystal polyester, the chemical foaming agent will decompose due to thermal degradation.

[0010] This invention has been made in view of these circumstances, and aims to provide liquid crystal polyester pellets useful as masterbatches for chemical foam molding, and foam molded articles made using the liquid crystal polyester pellets. [Means for solving the problem]

[0011] The inventors of the present invention investigated liquid crystal polyester pellets that can be used as masterbatches for chemical foam molding. As a result, they found that liquid crystal polyester pellets containing a chemical blowing agent having a specific structure can be used as masterbatches, and that when such masterbatches are mixed with natural pellets to create foamed molded products, the chemical blowing agent disperses well in the liquid crystal polyester, allowing the molded products to foam. This led to the completion of the present invention. To solve the above problems, the present invention encompasses the following embodiments.

[0012] [1] A liquid crystal polyester pellet containing liquid crystal polyester (A) and a blowing agent (B), wherein the blowing agent (B) contains a bistetrazole compound (B1). [2] The liquid crystal polyester (A) comprises repeating units having a naphthalene skeleton, as described in [1]. [3] The liquid crystal polyester pellet according to [1] or [2], wherein the liquid crystal polyester (A) has a flow start temperature of 280°C or less. [4] The liquid crystal polyester pellet according to any one of [1] to [4], wherein the content of the bistetrazole compound (B1) is 1 part by mass or more and 150 parts by mass or less per 100 parts by mass of the liquid crystal polyester (A). A foamed molded product made using liquid crystal polyester pellets as described in any one of the items [5][1] to [4]. [Effects of the Invention]

[0013] According to the present invention, it is possible to provide liquid crystal polyester pellets that are useful as masterbatches for chemical foam molding. [Modes for carrying out the invention]

[0014] (Liquid crystal polyester pellets) A liquid crystal polyester pellet according to one aspect of the present invention contains a liquid crystal polyester (A) and a foaming agent (B). In this specification, a liquid crystal polyester pellet containing a liquid crystal polyester (A) and a blowing agent (B) is a pellet (molten compound) obtained by melt-kneading a liquid crystal polyester resin composition containing a liquid crystal polyester (A) and a blowing agent (B). Typically, it is a pellet obtained by melt-kneading a liquid crystal polyester resin composition containing a liquid crystal polyester (A) and a blowing agent (B) in a twin-screw extruder and cutting the extruded strand. Therefore, in this specification, liquid crystal polyester pellets do not include dry blends in which a foaming agent (B) is added to pellets containing liquid crystal polyester (A), nor microcapsules containing liquid crystal polyester (A) and foaming agent (B).

[0015] One embodiment of liquid crystal polyester pellets is a masterbatch for chemical foam molding.

[0016] <Liquid crystal polyester (A)> The liquid crystal polyester (A) contained in the liquid crystal polyester pellets of this embodiment is not particularly limited as long as it is a polyester resin that exhibits liquid crystal properties in a molten state. The liquid crystal polyester (A) of this embodiment may also be liquid crystal polyester amide, liquid crystal polyester ether, liquid crystal polyester carbonate, liquid crystal polyester imide, etc.

[0017] The flow initiation temperature of the liquid crystal polyester (A) in this embodiment is preferably 220°C or higher, more preferably 230°C or higher, and even more preferably 240°C or higher. Furthermore, the flow initiation temperature of the liquid crystal polyester (A) in this embodiment is preferably 400°C or lower, more preferably 280°C or lower, and even more preferably 275°C or lower.

[0018] If the flow initiation temperature of the liquid crystal polyester (A) in this embodiment is above the above preferred lower limit, the heat resistance of the foamed molded product made from liquid crystal polyester pellets containing the liquid crystal polyester (A) can be further improved. Furthermore, if the flow initiation temperature of the liquid crystal polyester (A) in this embodiment is below the above preferred upper limit, the dispersibility of the foaming agent (B), described later, can be further improved.

[0019] For example, the flow start temperature of the liquid crystal polyester (A) in this embodiment is preferably 220°C or higher and 400°C or lower, more preferably 230°C or higher and 280°C or lower, and even more preferably 240°C or higher and 275°C or lower.

[0020] In this specification, the flow start temperature is also called the flow temperature or fluid temperature, and is a temperature that serves as an indicator of the molecular weight of liquid crystal polyester (A) (see Naoyuki Koide (ed.), "Liquid Crystal Polymers - Synthesis, Molding, and Applications," CMC Corporation, June 5, 1987, p. 95).

[0021] Specifically, as a method for measuring the flow initiation temperature, a capillary rheometer is used to measure liquid crystal polyester (A) at 9.8 MPa (100 kg / cm²).2 This is the temperature at which the viscosity is 4800 Pa·s (48000 poise) when melted while increasing the temperature at a rate of 4°C / min under a load and extruded from a nozzle with an inner diameter of 1 mm and a length of 10 mm.

[0022] In this embodiment, the liquid crystal polyester (A) is preferably a fully aromatic liquid crystal polyester made using only aromatic compounds as raw material monomers.

[0023] Typical examples of the liquid crystal polyester (A) of this embodiment include those obtained by polymerizing (polycondensing) an aromatic hydroxycarboxylic acid, an aromatic dicarboxylic acid, and at least one compound selected from the group consisting of aromatic diols, aromatic hydroxyamines, and aromatic diamines; those obtained by polymerizing multiple aromatic hydroxycarboxylic acids; those obtained by polymerizing an aromatic dicarboxylic acid and at least one compound selected from the group consisting of aromatic diols, aromatic hydroxyamines, and aromatic diamines; and those obtained by polymerizing a polyester such as polyethylene terephthalate with an aromatic hydroxycarboxylic acid. Here, aromatic hydroxycarboxylic acids, aromatic dicarboxylic acids, aromatic diols, aromatic hydroxyamines, and aromatic diamines may each be independently replaced in part or in whole by polymerizable derivatives thereof.

[0024] Examples of polymerizable derivatives of compounds having a carboxyl group, such as aromatic hydroxycarboxylic acids and aromatic dicarboxylic acids, include those obtained by converting the carboxyl group to an alkoxycarbonyl group or an aryloxycarbonyl group (esters); those obtained by converting the carboxyl group to a haloformyl group (acid halides); and those obtained by converting the carboxyl group to an acyloxycarbonyl group (acid anhydrides).

[0025] Examples of polymerizable derivatives of compounds having a hydroxyl group, such as aromatic hydroxycarboxylic acids, aromatic diols, and aromatic hydroxyamines, include those obtained by acyling the hydroxyl group to convert it into an acyloxyl group (acylated compounds). Examples of polymerizable derivatives of compounds having an amino group, such as aromatic hydroxyamines and aromatic diamines, include those obtained by acyling the amino group to convert it into an acylamino group (acylated compounds).

[0026] In this embodiment, the liquid crystal polyester (A) is preferably a liquid crystal polyester containing repeating units having a naphthalene skeleton, and more preferably a liquid crystal polyester containing repeating units having a 2,6-naphthylene group.

[0027] In this embodiment, if the liquid crystal polyester (A) is a liquid crystal polyester containing repeating units having a naphthalene skeleton, the number of repeating units having a naphthalene skeleton is preferably 10% or more, more preferably 15% or more, even more preferably 20% or more, and particularly preferably 25% or more, based on the total number of repeating units (100%) of the liquid crystal polyester (A). Furthermore, the number of repeating units having a naphthalene skeleton is preferably 50% or less, more preferably 45% or less, even more preferably 40% or less, and particularly preferably 35% or less, relative to the total number of repeating units of the liquid crystal polyester.

[0028] If the number of repeating units having a naphthalene skeleton in the liquid crystal polyester (A) is within the above preferred range, the mechanical strength of the foamed molded product made from liquid crystal polyester pellets containing liquid crystal polyester (A) can be further improved.

[0029] For example, the number of repeating units having a naphthalene skeleton in the liquid crystal polyester (A) is preferably 10% to 50%, more preferably 15% to 45%, even more preferably 20% to 40%, and particularly preferably 25% to 35% of the total number of repeating units in the liquid crystal polyester (A).

[0030] In this specification, the number of repeating units means a value obtained by the analysis method described in JP-A-2000-19168. Specifically, the liquid crystal polyester resin is reacted with a lower alcohol (alcohol having 1 to 3 carbon atoms) in a supercritical state to depolymerize the liquid crystal polyester resin to monomers that induce its repeating units, and each monomer that induces a repeating unit obtained as a depolymerization product is quantified by liquid chromatography, whereby the number of each repeating unit can be calculated.

[0031] The liquid crystal polyester (A) of the present embodiment is preferably a liquid crystal polyester having a repeating unit represented by the following formula (1) (hereinafter also referred to as "repeating unit (1)"). Further, the liquid crystal polyester (A) of the present embodiment may be a liquid crystal polyester having the repeating unit (1), a repeating unit represented by the following formula (2) (hereinafter also referred to as "repeating unit (2)"), and a repeating unit represented by the following formula (3) (hereinafter also referred to as "repeating unit (3)").

[0032] (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 each independently represents a phenylene group, a naphthylene group, a biphenylylene group or a group represented by the following formula (4). X and Y each independently represent an oxygen atom or an imino group (-NH-). The hydrogen atom in the group represented by Ar 1 , Ar 2 or Ar 3 may each independently be substituted with a halogen atom, an alkyl group or an aryl group.]

[0033] (4) -Ar 4-Z-Ar 5 - [In the formula, Ar 4 and Ar 5 Each of these independently represents either 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.

[0034] Ar 1 Ar 2 Or Ar 3 Examples of halogen atoms that can be substituted for one or more hydrogen atoms in the group represented by the above include fluorine atoms, chlorine atoms, bromine atoms, and iodine atoms.

[0035] Ar 1 Ar 2 Or Ar 3 Examples of alkyl groups that can be substituted for one or more hydrogen atoms in the group represented by the above include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, s-butyl group, t-butyl group, n-hexyl group, 2-ethylhexyl group, n-octyl group, n-decyl group, and the number of carbon atoms is preferably 1 to 10.

[0036] Ar 1 Ar 2 Or Ar 3 Examples of aryl groups that can be substituted for one or more hydrogen atoms in the group represented by the above include phenyl group, o-tolyl group, m-tolyl group, p-tolyl group, 1-naphthyl group, 2-naphthyl group, and the number of carbon atoms is preferably 6 to 20.

[0037] Ar 1 Ar 2 Or Ar 3 When the hydrogen atoms in the group represented by are substituted with the group described above, the number of substitutions is preferably one or two, and more preferably one.

[0038] Examples of alkylidene groups in formula (4) include methylene group, ethylidene group, isopropylidene group, n-butylidene group, and 2-ethylhexylidene group, and the number of carbon atoms is preferably 1 to 10.

[0039] The repeating unit (1) is a repeating unit derived from a predetermined aromatic hydroxycarboxylic acid. The repeating unit (1) is Ar 1 Those in which is a 1,4-phenylene group (a repeating unit derived from p-hydroxybenzoic acid), and Ar 1 Preferably, the group is a 2,6-naphthylene group (a repeating unit derived from 6-hydroxy-2-naphthoic acid), and Ar 1 It is more preferable that the group is a 2,6-naphthylene group.

[0040] In this specification, "derived from" means that, in order for the raw material monomer to polymerize, the chemical structure of the functional group contributing to polymerization changes, but no other structural changes occur.

[0041] The repeating unit (2) is a repeating unit derived from a predetermined aromatic dicarboxylic acid. The repeating unit (2) is Ar 2 Those in which the group is a 1,4-phenylene group (a repeating unit derived from terephthalic acid), Ar 2 Those in which the group is a 1,3-phenylene group (a repeating unit derived from isophthalic acid), Ar 2 Those in which are 2,6-naphthylene groups (repeating units derived from 2,6-naphthalenedicarboxylic acid), and Ar 2 Preferably, the group is a diphenyl ether-4,4'-diyl group (a repeating unit derived from diphenyl ether-4,4'-dicarboxylic acid), and Ar 2 Those in which the group is a 1,4-phenylene group, Ar 2 It is more preferable that the group is a 1,3-phenylene group.

[0042] The repeating unit (3) is a repeating unit derived from a predetermined aromatic diol, aromatic hydroxylamine, or aromatic diamine. The repeating unit (3) is Ar 3 The group is a 1,4-phenylene group (a repeating unit derived from hydroquinone, p-aminophenol, or p-phenylenediamine), and Ar 3Preferably, the group is a 4,4'-biphenylylene group (a repeating unit derived from 4,4'-dihydroxybiphenyl, 4-amino-4'-hydroxybiphenyl, or 4,4'-diaminobiphenyl), and Ar 3 It is more preferable that the group is a 4,4'-biphenylylene group.

[0043] Specifically, the liquid crystal polyester (A) of this embodiment includes a liquid crystal polyester consisting only of repeating units (1) (hereinafter also referred to as "LCPA"), and a liquid crystal polyester having repeating units (1), repeating units (2), and repeating units (3) (hereinafter also referred to as "LCPB").

[0044] If the liquid crystal polyester (A) in this embodiment is LCPA, then Ar 1 The repeating unit (1) is a 1,4-phenylene group, and Ar 1 It is preferable that the liquid crystal polyester has repeating units (1) in which the group is a 2,6-naphthylene group.

[0045] In LCPA, Ar 1 The number of repeating units (1) that are 2,6-naphthylene groups is preferably 10% or more, more preferably 15% or more, even more preferably 20% or more, and particularly preferably 25% or more, based on the total number of repeating units (100%) of the LCPA. Also, Ar 1 The number of repeating units (1) that are 2,6-naphthylene groups is preferably 50% or less, more preferably 45% or less, even more preferably 40% or less, and particularly preferably 35% or less, of the total number of repeating units of LCPA.

[0046] For example, in LCPA, Ar 1 The number of repeating units (1) containing a 2,6-naphthylene group is preferably 10% to 50%, more preferably 15% to 45%, even more preferably 20% to 40%, and particularly preferably 25% to 35% of the total number of repeating units of the liquid crystal polyester (A).

[0047] In LCPA, Ar 1 The number of repeating units (1) that are 1,4-phenylene groups is preferably 50% or more, more preferably 55% or more, even more preferably 60% or more, and particularly preferably 65% ​​or more, based on the total number of repeating units (100%) of the LCPA. Also, Ar 1 The number of repeating units (1) in which is a 2,6-naphthylene group is preferably 90% or less, more preferably 85% or less, even more preferably 80% or less, and particularly preferably 75% or less, based on the total number of repeating units in the LCPA.

[0048] For example, in LCPA, Ar 1 The number of repeating units (1) in which the group is a 1,4-phenylene group is preferably 10% to 50%, more preferably 15% to 45%, even more preferably 20% to 40%, and particularly preferably 25% to 35%, relative to the total number of repeating units of the liquid crystal polyester (A).

[0049] In this embodiment, if the liquid crystal polyester (A) is LCPB, the number of repeating units (1) is preferably 30% to 80%, more preferably 40% to 70%, and even more preferably 45% to 70%, of the total number of repeating units (100%).

[0050] In this embodiment, if the liquid crystal polyester (A) is LCPB, the number of repeating units (2) is preferably 35% or less, more preferably 10% to 35%, and even more preferably 15% to 30% of the total number of repeating units (100%).

[0051] In this embodiment, if the liquid crystal polyester (A) is LCPB, the number of repeating units (3) is preferably 35% or less, more preferably 10% to 35%, and even more preferably 15% to 30% of the total number of repeating units (100%).

[0052] In this embodiment, if the liquid crystal polyester (A) is LCPB, the ratio of the number of repeating units (2) to the number of repeating units (3) is expressed as [number of repeating units (2)] / [number of repeating units (3)], and is preferably 0.9 / 1 to 1 / 0.9, more preferably 0.95 / 1 to 1 / 0.95, and even more preferably 0.98 / 1 to 1 / 0.98.

[0053] In this embodiment, if the liquid crystal polyester (A) is LCPB, each of the repeating units (1) to (3) may have two or more types. Furthermore, LCPB may have repeating units other than (1) to (3), but the number of such units is preferably 10% or less, and more preferably 5% or less, of the total number of repeating units (100%).

[0054] In this embodiment, the liquid crystal polyester (A) is preferably a liquid crystal polyester consisting only of repeating units (1) among the above.

[0055] The liquid crystal polyester (A) of this embodiment may be used alone or in combination of two or more types.

[0056] The content of liquid crystal polyester (A) is preferably 40% by mass or more, more preferably 50% by mass or more, even more preferably 90% by mass or more, and particularly preferably 95% by mass or more, based on 100% by mass of the total amount of liquid crystal polyester pellets. Furthermore, the content of liquid crystal polyester (A) is preferably 99% by mass or less, more preferably 98% by mass or less, and even more preferably 97% by mass or less, based on 100% by mass of the total amount of liquid crystal polyester pellets.

[0057] For example, the content of liquid crystal polyester (A) is preferably 40% to 99% by mass, more preferably 50% to 98% by mass, even more preferably 90% to 97% by mass, and particularly preferably 95% to 97% by mass, based on 100% by mass of the total amount of liquid crystal polyester pellets.

[0058] <Foaming agent (B)> The liquid crystal polyester pellets of this embodiment contain a foaming agent (B). The foaming agent (B) contains a bistetrazole compound (B1).

[0059] The content of bistetrazole compound (B1) in the blowing agent (B) is preferably 60% by mass or more, more preferably 80% by mass or more, even more preferably 90% by mass or more, and particularly preferably 100% by mass, i.e., the blowing agent (B) consists solely of bistetrazole compound (B1), based on 100% by mass of the total amount of blowing agent (B).

[0060] ≪Bistetrazole compound (B1)≫ Bistetrazole compounds (B1) are compounds that have two tetrazole skeletons in a single compound. Specifically, the bistetrazole compounds (B1) include 5,5'-bi(1H-tetrazole), 5,5'-methylenebis(2H-tetrazole), 5,5'-azobis(1H-tetrazole), 5,5'-diazoaminobis(1H-tetrazole), 5,5'-(2-butene-1,4-diyl)bis(1H-tetrazole), 5,5'-(1,4-phenylene)bis(2H-tetrazole), and 5,5'-(1,3-phenylene Examples include bis(2H-tetrazole), 5,5'-tetramethylenebis(2H-tetrazole), 1,2-bis(1H-tetrazole-5-yl)hydrazine, 5,5'-(oxybisethylene)bis(1H-tetrazole), 4,5-bis(1H-tetrazole-5-yl)-2H-imidazole, and bis(1H-tetrazole-5-yl)amine (hereinafter collectively referred to as "bistetrazole compounds (B10)"). Furthermore, the bistetrazole compound (B1) may be a derivative of the bistetrazole compound (B10) (such as an alkali metal salt of the bistetrazole compound (B10) or an amine salt of the bistetrazole compound (B10)).

[0061] Among the above, the bistetrazole compound (B1) is preferably an amine salt of the bistetrazole compound (B10), and more preferably an amine salt of a compound having a 5,5'-bi(1H-tetrazole) skeleton. The fact that bistetrazole compound (B1) is an amine salt of bistetrazole compound (B10) further improves the stability of the liquid crystal polyester (A) used in combination.

[0062] Amine salts of bistetrazole compounds (B10) are salts obtained by the reaction of bistetrazole compounds (B10) with known basic amine compounds such as ammonia, aliphatic amines, heterocyclic amines, and aromatic amines.

[0063] Aliphatic amines include primary aliphatic amines, secondary aliphatic amines, and tertiary aliphatic amines. Examples of aliphatic primary amines include methylamine, ethylamine, n-propylamine, isopropylamine, n-butylamine, isobutylamine, sec-butylamine, tert-butylamine, pentylamine, tert-amylamine, cyclopentylamine, hexylamine, cyclohexylamine, heptylamine, octylamine, nonylamine, decylamine, dodecylamine, cetylamine, methylenediamine, ethylenediamine, tetraethylenepentamine, and others.

[0064] Examples of aliphatic secondary amines include dimethylamine, diethylamine, di-n-propylamine, diisopropylamine, di-n-butylamine, diisobutylamine, di-sec-butylamine, dipentylamine, dicyclopentylamine, dihexylamine, dicyclohexylamine, diheptylamine, dioctylamine, dinonylamine, didecylamine, didodecylamine, dicetylamine, N,N-dimethylmethylenediamine, N,N-dimethylethylenediamine, and N,N-dimethyltetraethylenepentamine.

[0065] Examples of aliphatic tertiary amines include trimethylamine, triethylamine, tri-n-propylamine, triisopropylamine, tri-n-butylamine, triisobutylamine, tri-sec-butylamine, tripentylamine, tricyclopentylamine, trihexylamine, tricyclohexylamine, triheptylamine, trioctylamine, trinonylamine, tridecylamine, tridodecylamine, tricetylamine, N,N,N',N'-tetramethylmethylenediamine, N,N,N',N'-tetramethylethylenediamine, and N,N,N',N'-tetramethyltetraethylenepentamine.

[0066] Examples of aromatic amines and heterocyclic amines include aniline and its derivatives, pyrrole and its derivatives, imidazole and its derivatives, pyrazole and its derivatives, piperidine and its derivatives, piperazine and its derivatives, and the like.

[0067] Among the above, the basic amine compound is preferably ammonia, a heterocyclic amine, or an aromatic amine, and more preferably ammonia or a heterocyclic amine.

[0068] In the liquid crystal polyester pellets of this embodiment, the bistetrazole compound (B1) is preferably 5,5'-bi(1H-tetrazole)diammonium or 5,5'-bi(1H-tetrazole)piperazine, and more preferably 5,5'-bi(1H-tetrazole)piperazine.

[0069] The bistetrazole compound (B1) of this embodiment may be used alone or in combination of two or more types.

[0070] The content of the bistetrazole compound (B1) is preferably 1% by mass or more, more preferably 2% by mass or more, and even more preferably 3% by mass or more, based on 100% by mass of the total amount of liquid crystal polyester pellets. Furthermore, the content of the bistetrazole compound (B1) is preferably 60% by mass or less, more preferably 50% by mass or less, even more preferably 10% by mass or less, and particularly preferably 5% by mass or less, based on 100% by mass of the total amount of liquid crystal polyester pellets.

[0071] If the content of the bistetrazole compound (B1) is equal to or greater than the above preferred value, the amount of the liquid crystal polyester pellets of this embodiment can be reduced when used as a masterbatch, and the amount of masterbatch to be stored can be reduced. If the content of the bistetrazole compound (B1) is below the above-mentioned preferred value, the moldability of the foamed molded product made using the liquid crystal polyester pellets of this embodiment will be further improved.

[0072] For example, the content of the bistetrazole compound (B1) is preferably 1% to 60% by mass, more preferably 2% to 50% by mass, even more preferably 3% to 10% by mass, and particularly preferably 3% to 5% by mass, based on 100% by mass of the total amount of liquid crystal polyester pellets.

[0073] The content of the bistetrazole compound (B1) is preferably 1 part by mass or more, more preferably 2 parts by mass or more, and even more preferably 3 parts by mass or more, per 100 parts by mass of liquid crystal polyester (A). Furthermore, the content of the bistetrazole compound (B1) is preferably 150 parts by mass or less, more preferably 100 parts by mass or less, even more preferably 10 parts by mass or less, and particularly preferably 6 parts by mass or less, per 100 parts by mass of liquid crystal polyester (A).

[0074] For example, the content of the bistetrazole compound (B1) is preferably 1 to 150 parts by mass, more preferably 2 to 100 parts by mass, even more preferably 3 to 10 parts by mass, and particularly preferably 3 to 6 parts by mass, per 100 parts by mass of liquid crystal polyester (A).

[0075] The bistetrazole compound (B1) preferably has a decomposition temperature of 260°C or higher, more preferably 280°C or higher, even more preferably 300°C or higher, and particularly preferably 320°C or higher.

[0076] If the decomposition temperature of the bistetrazole compound (B1) is above the preferred lower limit mentioned above, the bistetrazole compound (B1) will be less likely to decompose even when melt-kneaded with the liquid crystal polyester (A) described above, making it easier to produce the liquid crystal polyester pellets of this embodiment.

[0077] The upper limit of the decomposition temperature of the bistetrazole compound (B1) is not particularly limited, but is preferably 500°C or lower, more preferably 400°C or lower, and even more preferably 350°C or lower.

[0078] For example, the decomposition temperature of the bistetrazole compound (B1) is preferably 260°C to 500°C, more preferably 280°C to 400°C, even more preferably 300°C to 350°C, and particularly preferably 320°C to 350°C.

[0079] In this embodiment, the difference between the decomposition temperature of the bistetrazole compound (B1) and the flow initiation temperature of the liquid crystal polyester (A) in the liquid crystal polyester pellets (decomposition temperature of bistetrazole compound (B1) - flow initiation temperature of liquid crystal polyester (A)) is preferably 5°C or higher, more preferably 10°C or higher, even more preferably 50°C or higher, and particularly preferably 70°C or higher.

[0080] If the difference between the decomposition temperature of the bistetrazole compound (B1) and the flow initiation temperature of the liquid crystal polyester (A) is greater than or equal to the above preferred lower limit, then even if the bistetrazole compound (B1) and the liquid crystal polyester (A) described above are melt-kneaded together, the bistetrazole compound (B1) will be less likely to decompose, making it easier to produce the liquid crystal polyester pellets of this embodiment.

[0081] The upper limit of the difference between the decomposition temperature of the bistetrazole compound (B1) and the flow initiation temperature of the liquid crystal polyester (A) is not particularly limited, but is preferably 150°C or less, and more preferably 100°C or less.

[0082] For example, the difference between the decomposition temperature of the bistetrazole compound (B1) and the flow initiation temperature of the liquid crystal polyester (A) is preferably 5°C or more and 150°C or less, more preferably 10°C or more and 100°C or less, even more preferably 50°C or more and 100°C or less, and particularly preferably 70°C or more and 100°C or less.

[0083] In this specification, the decomposition temperature of the bistetrazole compound (B1) can be measured using DSC (differential scanning calorimetry) or DTA (differential thermal analysis).

[0084] The theoretical gas generation amount of the bistetrazole compound (B1) is preferably 340 mL / g or more, more preferably 360 mL / g or more, and even more preferably 380 mL / g or more. Furthermore, the theoretical gas generation amount of the bistetrazole compound (B1) is preferably 600 mL / g or less, more preferably 550 mL / g or less, and even more preferably 520 mL / g or less.

[0085] For example, the theoretical gas generation amount of the bistetrazole compound (B1) is preferably 340 mL / g or more and 600 mL / g or less, more preferably 360 mL / g or more and 550 mL / g or less, and even more preferably 380 mL / g or more and 520 mL / g or less.

[0086] In this specification, the theoretical amount of gas produced by the bistetrazole compound (B1) can be calculated by dividing the amount of nitrogen gas produced, assuming that the bistetrazole compound (B1) decomposes and one nitrogen molecule is produced for each tetrazole ring, by the molecular weight of the compound.

[0087] The foaming agent (B) in the liquid crystal polyester pellets of this embodiment may contain a foaming agent other than the bistetrazole compound (B1) described above (hereinafter referred to as "foaming agent (B2)"). The foaming agent (B2) is dinitropentamerylenetetramine or azodicarbonamide. Examples include organic chemical blowing agents such as 4,4'-oxybisbenzenesulfonyl hydrazide and inorganic chemical blowing agents such as sodium bicarbonate.

[0088] The foaming agent (B) in this embodiment may be used alone or in combination of two or more types.

[0089] The content of the foaming agent (B) is preferably 1% by mass or more, more preferably 2% by mass or more, and even more preferably 3% by mass or more, based on 100% by mass of the total amount of liquid crystal polyester pellets. Furthermore, the content of the foaming agent (B) is preferably 60% by mass or less, more preferably 50% by mass or less, even more preferably 10% by mass or less, and particularly preferably 5% by mass or less, based on 100% by mass of the total amount of liquid crystal polyester pellets.

[0090] If the content of the foaming agent (B) is equal to or greater than the above preferred value, the amount of the masterbatch can be reduced when using the liquid crystal polyester pellets of this embodiment as a masterbatch, and the amount of the masterbatch to be stored can be reduced. If the content of the foaming agent (B) is below the above-mentioned preferred value, the moldability of the foamed molded product made using the liquid crystal polyester pellets of this embodiment will be further improved.

[0091] For example, the content of the foaming agent (B) is preferably 1% to 60% by mass, more preferably 2% to 50% by mass, even more preferably 3% to 10% by mass, and particularly preferably 3% to 5% by mass, based on 100% by mass of the total amount of liquid crystal polyester pellets.

[0092] <Optional ingredients> The liquid crystal polyester pellets of this embodiment may contain any components other than the liquid crystal polyester (A) and the foaming agent (B) described above. Optional components include fillers, resins other than liquid crystal polyester, and additives well known in this art.

[0093] Filler The filler can be either an inorganic or organic filler, and the choice is made appropriately depending on the application. Inorganic fillers are preferred because they provide mechanical strength.

[0094] [Inorganic filler] The inorganic filler may be a fibrous filler, a plate-shaped filler, or a granular filler.

[0095] Examples of fibrous fillers include glass fibers; carbon fibers such as pan-carbon fibers and pitch-carbon fibers; ceramic fibers such as silica fibers, alumina fibers, and silica-alumina fibers; and metal fibers such as stainless steel fibers. Whiskers such as potassium titanate whiskers, barium titanate whiskers, wollastonite whiskers, aluminum borate whiskers, silicon nitride whiskers, and silicon carbide whiskers are also used. Among these, glass fibers are preferred.

[0096] Examples of plate-shaped fillers include talc, mica, graphite, wollastonite, glass flakes, barium sulfate, and calcium carbonate. The mica may be muscovite, phlogopite, fluorphlogopite, or tetrasiliconite.

[0097] Examples of granular fillers include silica, alumina, titanium oxide, glass beads, glass balloons, boron nitride, silicon carbide, and calcium carbonate.

[0098] Below, we will describe glass fibers as a fibrous filler.

[0099] Examples of glass fibers include long-fiber chopped glass fibers and short-fiber milled glass fibers, which are manufactured using various methods. In this embodiment, two or more of these types can be used in combination.

[0100] Examples of the glass fibers mentioned above include E-glass, A-glass, C-glass, D-glass, AR-glass, R-glass, S-glass, or mixtures thereof. Among these, E-glass is preferred because it has excellent strength and is readily available.

[0101] As the glass fibers mentioned above, weakly alkaline fibers are preferable because they have superior mechanical strength (tensile strength and Izod impact strength). In particular, glass fibers with a silicon dioxide content of 50% to 80% by mass relative to the total mass of the glass fibers are preferred, and glass fibers with a silicon dioxide content of 65% to 77% by mass are more preferred.

[0102] The glass fibers mentioned above may be fibers treated with a coupling agent such as a silane-based coupling agent or a titanium-based coupling agent, if necessary.

[0103] The glass fibers may be coated with thermoplastic resins such as urethane resin, acrylic resin, or ethylene / vinyl acetate copolymer, or with thermosetting resins such as epoxy resin. Furthermore, the glass fibers may be treated with a consolidating agent.

[0104] [Organic filler] The organic filler may be a fibrous filler, a plate-shaped filler, or a granular filler. Examples of fibrous fillers include polyester fibers, aramid fibers, and cellulose fibers. Examples of granular fillers include insoluble and infusible polymers such as homopolymers of parahydroxybenzoic acid.

[0105] <<Resins other than liquid crystal polyester>> Examples of resins other than liquid crystal polyester include thermoplastic resins such as polypropylene, polyamide, polyesters other than liquid crystal polyester, polyphenylene sulfide, polyethersulfone, polyetherketone, polycarbonate, polyphenylene ether, and polyetherimide; and thermosetting resins such as phenolic resins, epoxy resins, polyimide resins, and cyanate resins.

[0106] ≪Additives well known in this field≫ Examples of additives well known in this field include mold release agents such as fluorocarbons, higher fatty acids, higher fatty acid esters, higher alcohols, and metal soaps; colorants; antioxidants, heat stabilizers, ultraviolet absorbers, antistatic agents, surfactants, flame retardants, flame retardant enhancers, and plasticizers.

[0107] The liquid crystal polyester pellets of this embodiment described above contain the liquid crystal polyester (A) and the blowing agent (B), wherein the blowing agent (B) contains a bistetrazole compound (B1). Because the bistetrazole compound (B1) has a specific structure called the bistetrazole skeleton, its decomposition temperature is higher than that of conventional general-purpose chemical blowing agents, and it is less susceptible to thermal decomposition even when melt-kneaded together with liquid crystal polyester (A). In addition, because the bistetrazole compound (B1) has this specific structure, it can be well dispersed in the liquid crystal polyester (A) during melt-kneading. Furthermore, since the tetrazole skeleton is a relatively low basicity skeleton, even when liquid crystal polyester (A) and bistetrazole compound (B1) are used together, it is possible to suppress the decomposition of liquid crystal polyester (A) by the bistetrazole compound (B1). Therefore, the liquid crystal polyester pellets of this embodiment have good granulation properties even when liquid crystal polyester (A) and a foaming agent (B) are used in combination. Therefore, the liquid crystal polyester pellets of this embodiment are particularly useful as a masterbatch for chemical foam molding.

[0108] The present invention has the following aspects.

[0109] "1" A masterbatch for chemical foam molding, comprising a liquid crystal polyester (A) and a foaming agent (B), wherein the foaming agent (B) contains a bistetrazole compound (B1). "2" The liquid crystal polyester (A) comprises repeating units having a naphthalene skeleton, as described in "1", a masterbatch for chemical foam molding. "3" The masterbatch for chemical foam molding according to "1" or "2", wherein the flow start temperature of the liquid crystal polyester (A) is 280°C or lower. "4" The masterbatch for chemical foam molding according to any one of "1" to "3", wherein the decomposition temperature of the bistetrazole compound (B1) is 300°C or higher.

[0110] "5" The content of the liquid crystal polyester (A) is preferably 40% by mass or more and 99% by mass or less, more preferably 50% by mass or more and 98% by mass or less, even more preferably 90% by mass or more and 97% by mass or less, and particularly preferably 95% by mass or less and 97% by mass or less, according to any one of "1" to "4" of the total amount of the masterbatch for chemical foam molding.

[0111] "6" The content of the bistetrazole compound (B1) is preferably 1% by mass or more and 60% by mass or less, more preferably 2% by mass or more and 50% by mass or less, even more preferably 3% by mass or more and 10% by mass or less, and particularly preferably 3% by mass or more and 5% by mass or less, based on 100% by mass of the total amount of the masterbatch for chemical foam molding, as described in any one of "1" to "5".

[0112] "7" The liquid crystal polyester (A) is a liquid crystal polyester having repeating units represented by the following formula (1'), the masterbatch for chemical foam molding according to any one of "1" to "6". (1')-O-Ar 1 '-CO- [In the formula, Ar 1 ' represents a naphthylene group.

[0113] The masterbatch for chemical foam molding according to "7", wherein the number of repeating units represented by formula (1') is preferably 10% to 50%, more preferably 15% to 45%, even more preferably 20% to 40%, and particularly preferably 25% to 35%, with respect to the total number of repeating units of the liquid crystal polyester (A).

[0114] "9" The masterbatch for chemical foam molding according to any one of "1" to "8", wherein the masterbatch for chemical foam molding contains only a bistetrazole compound (B1) and no other foaming agent.

[0115] "10" The masterbatch for chemical foam molding according to any one of "1" to "9", wherein the bistetrazole compound (B1) is one or more bistetrazole compounds selected from the group consisting of 5,5'-bi(1H-tetrazole)diammonium and 5,5'-bi(1H-tetrazole)piperazine.

[0116] (Method of manufacturing liquid crystal polyester pellets) The liquid crystal polyester pellets according to one aspect of the present invention described above can be manufactured by known methods. For example, liquid crystal polyester pellets according to one aspect of the present invention can be manufactured by feeding liquid crystal polyester (A) and foaming agent (B) from a feeder using a twin-screw extruder (e.g., Ikegai Co., Ltd.'s "PCM-30HS") and a water-sealed vacuum pump (e.g., Shinko Seiki Co., Ltd.'s "SW-25"), melting and kneading the mixture with a screw fitted with a kneading block while degassing through a vacuum vent, and then cutting the discharged strand.

[0117] The cylinder temperature of the twin-screw extruder is set appropriately so that it is above the flow initiation temperature of the liquid crystal polyester (A) and below the decomposition temperature of the foaming agent (B). The cylinder temperature of the twin-screw extruder is preferably, for example, 200 to 300°C, and more preferably 240 to 280°C.

[0118] (Liquid crystal polyester pellet mixture) A liquid crystal polyester pellet mixture according to one aspect of the present invention contains the liquid crystal polyester pellets of the above-described embodiment and pellets other than the liquid crystal polyester pellets. Typically, the liquid crystal polyester pellets in the above-described embodiment are the masterbatch, and the pellets other than the liquid crystal polyester pellets are the natural pellets.

[0119] One embodiment of the liquid crystal polyester pellet mixture contains liquid crystal polyester (A) and a blowing agent (B), wherein the blowing agent (B) contains a masterbatch for chemical foam molding containing a bistetrazole compound (B1), and natural pellets containing liquid crystal polyester and filler, but not containing the blowing agent (B).

[0120] The mass ratio of the masterbatch to the natural pellets in the liquid crystal polyester pellet mixture (masterbatch:natural pellets) is preferably 1:100 to 30:100, and more preferably 5:100 to 20:100.

[0121] The content of the foaming agent (B) in the liquid crystal polyester pellet mixture is preferably 0.1% to 10% by mass, more preferably 0.1% to 7% by mass, even more preferably 0.1% to 6% by mass, and particularly preferably 0.3% to 0.7% by mass, based on 100% by mass of the total amount of the liquid crystal polyester pellet mixture.

[0122] If the content of the foaming agent (B) in the liquid crystal polyester pellet mixture is within the above preferred range, the moldability of the foamed molded product made using the liquid crystal polyester pellet mixture of this embodiment will be further improved.

[0123] Specifically, examples of liquid crystal polyester in natural pellets include those similar to the liquid crystal polyester described in the liquid crystal polyester pellets of the above-described embodiment. The liquid crystal polyester (A) in the masterbatch and the liquid crystal polyester in the natural pellets may be the same or different, but it is preferable that they be the same.

[0124] Examples of fillers in natural pellets include those similar to those described for liquid crystal polyester pellets in the above-described embodiment. Among these, fibrous fillers are preferred, and glass fibers are more preferred.

[0125] The filler content in the natural pellets is preferably 5% to 60% by mass, more preferably 10% to 50% by mass, and even more preferably 20% to 40% by mass, based on 100% by mass of the total amount of natural pellets.

[0126] The natural pellets may contain liquid crystal polyester and optional components other than fillers. Specifically, these optional components are the same as those described for the liquid crystal polyester pellets in the embodiments described above.

[0127] More specifically, examples of liquid crystal polyester pellet mixtures include a masterbatch for chemical foam molding containing liquid crystal polyester (A) and a blowing agent (B), wherein the blowing agent (B) contains a bistetrazole compound (B1) and does not contain fillers, and natural pellets containing liquid crystal polyester and fillers but not containing the blowing agent (B).

[0128] As described above, the liquid crystal polyester pellet mixture of this embodiment uses the liquid crystal polyester pellets according to one aspect of the present invention described above as a masterbatch, making it possible to easily manufacture foamed molded products with good moldability.

[0129] (Foam molded product) A foamed molded product according to one aspect of the present invention is manufactured using liquid crystal polyester pellets according to the above-described aspect of the present invention.

[0130] The molding method for foamed molded products is not particularly limited and includes, for example, compound molding, calendering, extrusion molding, and injection molding. In the case of injection molding, the method is not particularly limited and includes the short-short method, in which a portion of the resin material is placed in the mold and foamed, and the core-back method, in which the mold is fully filled with the resin material and then opened to the desired foaming point.

[0131] It is preferable to set the cylinder temperature of the injection molding machine to a temperature 40 to 10°C higher than the flow start temperature of the liquid crystal polyester used. The cylinder temperature of the injection molding machine is preferably, for example, 320 to 400°C, and more preferably 320 to 360°C.

[0132] Since the foamed molded product of this embodiment described above is made using liquid crystal polyester pellets according to one aspect of the present invention as described above, it does not require special equipment and can be easily manufactured.

[0133] A foamed molded article according to one aspect of the present invention can be used in any application where liquid crystal polyester can be applied. Examples include interior components for housings in various electrical and electronic equipment, automobile parts, home appliance parts, industrial machinery parts, daily necessities, building materials, and the like. In particular, a foamed molded product according to one aspect of the present invention is useful as an automobile part and a building material. [Examples]

[0134] The present invention will be described below with reference to examples, but the present invention is not limited to these examples.

[0135] [Flow initiation temperature of liquid crystal polyester] In this embodiment, the flow initiation temperature of the liquid crystal polyester was measured as follows. Using a flow tester (Shimadzu Corporation's "CFT-500EX" model), approximately 2g of liquid crystal polyester was filled into a cylinder fitted with a die having a nozzle with an inner diameter of 1mm and a length of 10mm. Under a load of 9.8MPa, the liquid crystal polyester was melted while the temperature was increased at a rate of 4°C / min, and extruded from the nozzle. The temperature at which a viscosity of 4800 Pa·s was observed was measured and defined as the flow initiation temperature.

[0136] <Raw materials used> The liquid crystal polyester and foaming agent used in this embodiment are shown below.

[0137] • Liquid crystal polyester Liquid crystal polyesters (1) and (2) obtained in the following manufacturing examples 1 and 2 were used.

[0138] [Manufacturing Example 1 (Manufacturing of Liquid Crystal Polyester (1))] A reactor equipped with a stirrer, torque meter, nitrogen gas inlet tube, thermometer, and reflux condenser was charged with 1078.7 g (7.81 mol) of p-hydroxybenzoic acid, 600.3 g (3.29 mol) of 2-hydroxy-6-naphthoic acid, 1235.3 g (12.1 mol) of acetic anhydride, and 0.17 g of 1-methylimidazole. After thoroughly purging the reactor with nitrogen gas, the temperature was raised to 140°C over 15 minutes under a nitrogen gas flow, and the temperature was maintained at 140°C and refluxed for 1 hour. Subsequently, the temperature was raised to 280°C over 3 hours and 40 minutes while distilling off the distilled by-product acetic acid. The reaction was considered complete when an increase in torque was observed, and the contents were removed. The temperature at which the solids began to flow was 235°C. The obtained solid was cooled to room temperature, ground in a coarse grinder, and then heated under a nitrogen atmosphere from room temperature (25°C) to 235°C over 1 hour, then heated from 235°C to 240°C over 4 hours and 10 minutes, and held at 240°C for 5 hours to carry out solid-phase polymerization. The obtained solid-phase polymer was cooled to room temperature to obtain powdered liquid crystal polyester (1) (hereinafter referred to as LCP1). The flow initiation temperature of the obtained LCP1 was 270°C. Observation of LCP1 with a polarizing microscope revealed that it exhibited optical anisotropy during melting.

[0139] LCP1 is based on the total number of repeating units, 100%, with Ar 1 70% of the repeating unit (1) is a 1,4-phenylene group (i.e., a repeating unit derived from p-hydroxybenzoic acid), and Ar 1 It contained 30% of a repeating unit (1) which is a 2,6-naphthylene group (i.e., a repeating unit derived from 6-hydroxy-2-naphthoic acid). Furthermore, the proportion of constituent units having a naphthalene skeleton (2,6-naphthylene group) in the liquid crystal polyester (1) is 30% of the total number of repeating units.

[0140] [Manufacturing Example 2 (Manufacturing of Liquid Crystal Polyester (2))] A reactor equipped with a stirring device, a torque meter, a nitrogen gas inlet pipe, a thermometer, and a reflux condenser, 994.5 g (7.2 mol) of p-hydroxybenzoic acid, 239.2 g (1.44 mol) of terephthalic acid, 159.5 g (0.96 mol) of isophthalic acid, 446.9 g (2.4 mol) of 4,4'-dihydroxybiphenyl, and 1347.6 g (13.2 mol) of acetic anhydride were added. After replacing the gas in the reactor with nitrogen gas, 0.18 g of 1-methylimidazole was added, and the mixture was heated from room temperature to 150°C over 30 minutes with stirring under a nitrogen gas stream, and refluxed at 150°C for 30 minutes. Next, 2.4 g of 1-methylimidazole was added, and the mixture was heated from 150°C to 320°C over 2 hours and 50 minutes while distilling off the by-product acetic acid and unreacted acetic anhydride. When an increase in torque was observed, the contents were removed from the reactor and cooled to room temperature.

[0141] The obtained solid was pulverized in a pulverizer, and under a nitrogen gas atmosphere, the temperature was raised from room temperature to 220°C over 1 hour, then raised from 220°C to 240°C over 30 minutes, and held at 240°C for 10 hours to induce solid-phase polymerization. After cooling, powdered liquid crystal polyester (2) (hereinafter referred to as LCP2) was obtained. The flow initiation temperature of LCP2 was 286°C.

[0142] LCP2 is based on the total number of repeating units, 100%, with Ar 160% of the repeating unit (1) is a 1,4-phenylene group (i.e., a repeating unit derived from p-hydroxybenzoic acid), Ar 2 12% of the repeating unit (2) is a 1,4-phenylene group (i.e., a repeating unit derived from terephthalic acid), Ar 2 8% of the repeating unit (2) which is a 1,3-phenylene group (i.e., a repeating unit derived from isophthalic acid), and Ar 3 It contained 20% of a repeating unit (3) which is a 4,4'-biphenylylene group (i.e., a repeating unit derived from 4,4'-dihydroxybiphenyl).

[0143] • Foaming agent B1-1: 5,5'-bi(1H-tetrazole)diammonium (molecular weight 172.15, decomposition temperature 263°C, theoretical gas generation 520 mL / g). B1-2: 5,5'-bi(1H-tetrazole)piperazine (molecular weight 224.23, decomposition temperature 330°C, theoretical gas generation 400 mL / g). B2-1: A compound represented by the following chemical formula (b2-1) (molecular weight 127.11, decomposition temperature 308°C, theoretical gas generation 352 mL / g).

[0144] [ka]

[0145] <Examples of liquid crystal polyester pellet manufacturing> (Examples 1-10, Comparative Example 1) The liquid crystal polyester pellets of Examples 1 to 10 and Comparative Example 1 were manufactured by mixing LCP1 and a foaming agent in the proportions shown in Table 1. Specifically, LCP1 and a foaming agent were fed from a feeder in the proportions shown in Table 1 using a twin-screw extruder (Ikegai Co., Ltd., "PCM-30HS") and a water-sealed vacuum pump (Shinko Seiki Co., Ltd., "SW-25") at a cylinder temperature of 250°C. The liquid crystal polyester and foaming agent were then melt-kneaded using a screw with a kneading block inserted, while degassing was performed with a vacuum vent. The extruded strands were cut to obtain liquid crystal polyester pellets for Examples 1-10 and Comparative Example 1.

[0146] (Examples 11, 12, Comparative Example 2) The liquid crystal polyester pellets of Examples 11 and 12 and Comparative Example 2 were manufactured by mixing LCP2 and a blowing agent in the proportions shown in Table 1. Specifically, the liquid crystal polyester pellets of Examples 11, 12, and Comparative Example 2 were obtained using the same method as in Examples 1 to 10 and Comparative Example 1, except that the cylinder temperature was changed from 250°C to 265°C.

[0147] [Evaluation of granulation properties] The granulation properties of each example of liquid crystal polyester pellet produced using the method described in <Examples of Liquid Crystal Polyester Pellet Production> above were evaluated according to the following criteria. A: It was possible to granulate the strands without them breaking midway. B: Occasionally, strands would break, but granulation was still possible. C: The strands were brittle, making it difficult to granulate them without the strands breaking midway.

[0148] [Table 1]

[0149] [Table 2]

[0150] The values ​​in Tables 1 and 2 represent the amount of each ingredient (mass %). As shown in Table 1, the liquid crystal polyester pellets of the example exhibited better granulation properties compared to the liquid crystal polyester pellets of the comparative example.

[0151] <Examples of foamed molded product manufacturing> The liquid crystal polyester pellets of each of the above examples were used as masterbatches, and the foamed molded products of each example were manufactured using the masterbatches and natural pellets containing LCP1 (hereinafter referred to as "natural pellet 1") or natural pellets containing LCP2 (hereinafter referred to as "natural pellet 2").

[0152] Natural Pellet 1 is a pellet obtained by melting and kneading LCP1 and chopped glass fiber (manufactured by Nitto Boseki Co., Ltd., product name "CS3J-260S") as raw materials. As the raw material for Natural Pellet 1, 30 parts by mass of the chopped glass fiber was used per 100 parts by mass of LCP1.

[0153] Natural Pellet 2 is a pellet obtained by melting and kneading LCP2 and the chopped glass fibers used as raw materials. As the raw material for Natural Pellet 2, 30 parts by mass of the chopped glass fiber was used per 100 parts by mass of LCP2.

[0154] (Examples 1-4, 6-8) One of the liquid crystal polyester pellets from Examples 1-4 and 6-8, along with Natural Pellet 1, was heated in a cylinder set to 330°C using a fully electric molding machine "J450AD" manufactured by Japan Steel Works. The pellets and Natural Pellet 1 were weighed so that the mass ratio of the pellets and Natural Pellet 1 (one of the liquid crystal polyester pellets from Examples 1-4 and 6-8: Natural Pellet 1) was 15:100. The molten resin was injected at a set temperature of 100°C into a mold with a cavity shape of 200mm x 250mm x 1.5mm thickness, and a flat foamed molded product (200mm x 250mm x 3.0mm thickness) was produced by the core-back method.

[0155] (Example 9) A flat foamed molded product (200 mm × 250 mm × 3.0 mm thick) was manufactured using the same manufacturing method as described above, except that one of the liquid crystal polyester pellets from Examples 1-4 and 6-8 was replaced with the liquid crystal polyester pellet from Example 9, and the mass ratio of liquid crystal polyester pellet to natural pellet 1 was changed from 15:100 to 7.5:100.

[0156] (Examples 11 and 12) A flat foamed molded product (200 mm × 250 mm × 3.0 mm thick) was manufactured using the same manufacturing method as described above, except that one of the liquid crystal polyester pellets from Examples 1-4 and 6-8 was replaced with the liquid crystal polyester pellet from Example 11 or 12, Natural Pellet 1 was replaced with Natural Pellet 2, and the cylinder setting temperature was changed from 330°C to 350°C.

[0157] [Evaluation of moldability of foamed molded products] The moldability of each foamed molded product manufactured using the method described in <Examples of Foamed Molded Product Manufacturing> above was evaluated according to the following criteria. A: The entire foamed molded product was foamed to a thickness of 3.0 mm. B: Some of the foamed molded products became thinner than 3.0 mm in thickness.

[0158] [Table 3]

[0159] [Table 4]

[0160] As shown in Tables 3 and 4, the foamed molded articles produced using the polyester pellets of the above-described examples as a masterbatch exhibited good moldability.

Claims

1. It contains liquid crystal polyester (A) and a foaming agent (B), The foaming agent (B) comprises a bistetrazole compound (B1), The bistetrazole compound (B1) is an amine salt of the bistetrazole compound, A liquid crystal polyester pellet in which the bistetrazole compound (B1) is a compound having a 5,5'-bi(1H-tetrazole) skeleton.

2. The liquid crystal polyester pellet according to claim 1, wherein the liquid crystal polyester (A) includes repeating units having a naphthalene skeleton.

3. The liquid crystal polyester pellet according to claim 1 or 2, wherein the flow initiation temperature of the liquid crystal polyester (A) is 280°C or lower.

4. The liquid crystal polyester pellet according to any one of claims 1 to 3, wherein the content of the bistetrazole compound (B1) is 1 part by mass or more and 150 parts by mass or less per 100 parts by mass of the liquid crystal polyester (A).

5. A foamed molded article made using liquid crystal polyester pellets as described in any one of claims 1 to 4.

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