JP5655504B2 - Heat treatment method for liquid crystal polyester liquid composition - Google Patents

Description

  The present invention relates to a method for heat-treating a liquid composition containing a liquid crystal polyester and a solvent.

  Liquid crystalline polyester has been studied as a material for an insulating layer of a printed wiring board because of its high heat resistance and strength, and low hygroscopicity and dielectric loss. In addition, as a method for producing a liquid crystal polyester film or a liquid crystal polyester impregnated fiber sheet used for the insulating layer, a method using a liquid composition containing a liquid crystal polyester and a solvent has been studied. For example, Patent Document 1 and Patent Document 2 disclose a method for producing a liquid crystal polyester film by casting the liquid composition on a support substrate and then removing the solvent. Patent Document 3 and Patent Document 4 disclose a method for producing a liquid crystal polyester-impregnated fiber sheet by impregnating a fiber sheet with the liquid composition and then removing the solvent.

JP 2004-315678 A JP 2005-342980 A JP 2006-1959 A JP 2007-146139 A

  Liquid compositions containing liquid crystal polyesters and solvents as disclosed in Patent Documents 1 to 4 tend to increase in viscosity when stored at room temperature, and may gel when stored for a long time.

  Therefore, as a result of studying a method for reducing the viscosity of the liquid composition, the present inventor has conducted heat treatment of the liquid composition under predetermined conditions, thereby suppressing decomposition of the liquid crystal polyester, and The present inventors have found that the viscosity can be reduced and have completed the present invention. That is, this invention provides the heat processing method of the liquid composition which heat-processes the liquid composition containing liquid crystalline polyester and a solvent on the conditions which satisfy | fill following formula (1)-(3).

(1) A ≦ 5
(2) 50 ≦ B
(3) A + 0.065B ≦ 10

(A represents the water | moisture content (mass%) of the said liquid composition. B represents the heat processing temperature (degreeC).

  ADVANTAGE OF THE INVENTION According to this invention, the viscosity of the liquid composition containing liquid crystalline polyester and a solvent can be reduced, suppressing decomposition | disassembly of liquid crystalline polyester.

  The liquid crystalline polyester is a liquid crystalline polyester that exhibits liquid crystallinity in a molten state, and is preferably melted at a temperature of 450 ° C. or lower. The liquid crystal polyester may be a liquid crystal polyester amide, a liquid crystal polyester ether, a liquid crystal polyester carbonate, or a liquid crystal polyester imide. The liquid crystal polyester is preferably a wholly aromatic liquid crystal polyester using only an aromatic compound as a raw material monomer.

  A typical example of the liquid crystal polyester is polymerization (polycondensation) of an aromatic hydroxycarboxylic acid, an aromatic dicarboxylic acid, and at least one compound selected from the group consisting of an aromatic diol, an aromatic hydroxyamine, and an aromatic diamine. At least one compound selected from the group consisting of aromatic dicarboxylic acids and aromatic diols, aromatic hydroxyamines and aromatic diamines, And those obtained by polymerizing a polyester such as polyethylene terephthalate and an aromatic hydroxycarboxylic acid. Here, the aromatic hydroxycarboxylic acid, the aromatic dicarboxylic acid, the aromatic diol, the aromatic hydroxyamine, and the aromatic diamine are each independently replaced with a part or all of the polymerizable derivative. Also good.

  Examples of polymerizable derivatives of a compound having a carboxyl group such as aromatic hydroxycarboxylic acid and aromatic dicarboxylic acid include those obtained by converting a carboxyl group into an alkoxycarbonyl group or an aryloxycarbonyl group (ester), carboxyl Examples include those obtained by converting a group into a haloformyl group (acid halide), and those obtained by converting a carboxyl group into an acyloxycarbonyl group (acid anhydride). Examples of polymerizable derivatives of hydroxyl group-containing compounds such as aromatic hydroxycarboxylic acids, aromatic diols and aromatic hydroxyamines include those obtained by acylating hydroxyl groups and converting them to acyloxyl groups (acylated products) ). Examples of polymerizable derivatives of amino group-containing compounds such as aromatic hydroxyamines and aromatic diamines include those obtained by acylating an amino group and converting it to an acylamino group (acylated product).

  The liquid crystalline polyester preferably has a repeating unit represented by the following formula (1) (hereinafter sometimes referred to as “repeating unit (1)”), and the repeating unit (1) and the following formula (2) A repeating unit represented (hereinafter sometimes referred to as “repeating unit (2)”) and a repeating unit represented by the following formula (3) (hereinafter sometimes referred to as “repeating unit (3)”). It is more preferable to have.

(1) —O—Ar ¹ —CO—
(2) —CO—Ar ² —CO—
⁽³⁾ -X-Ar 3 -Y-

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

(4) -Ar ⁴ -Z-Ar ^5-

(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.)

As said halogen atom, a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom are mentioned. Examples of the alkyl group 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, An n-octyl group and n-decyl group are mentioned, The carbon number is 1-10 normally. Examples of the aryl group include a phenyl group, an o-tolyl group, an m-tolyl group, a p-tolyl group, a 1-naphthyl group, and a 2-naphthyl group, and the number of carbon atoms is usually 6 to 20. . When the hydrogen atom is substituted with these groups, the number is usually 2 or less for each group represented by Ar ¹ , Ar ² or Ar ³ , and preferably 1 It is as follows.

  Examples of the alkylidene group include a methylene group, an ethylidene group, an isopropylidene group, an n-butylidene group, and a 2-ethylhexylidene group, and the number of carbon atoms is usually 1 to 10.

The repeating unit (1) is a repeating unit derived from a predetermined aromatic hydroxycarboxylic acid. As the repeating unit (1), Ar ¹ is a p-phenylene group (a repeating unit derived from p-hydroxybenzoic acid), and Ar ¹ is a 2,6-naphthylene group (6-hydroxy-2). -Repeating units derived from naphthoic acid) are preferred.

The repeating unit (2) is a repeating unit derived from a predetermined aromatic dicarboxylic acid. As the repeating unit (2), Ar ² is a p-phenylene group (repeating unit derived from terephthalic acid), Ar ² is an m-phenylene group (repeating unit derived from isophthalic acid), Ar ² Is a 2,6-naphthylene group (repeating unit derived from 6-hydroxy-2-naphthoic acid) and Ar ² is a diphenyl ether-4,4′-diyl group (diphenyl ether) Preferred is a repeating unit derived from -4,4'-dicarboxylic acid.

The repeating unit (3) is a repeating unit derived from a predetermined aromatic diol, aromatic hydroxylamine or aromatic diamine. As the repeating unit (3), Ar ³ is a p-phenylene group (repeating unit derived from hydroquinone, p-aminophenol or p-phenylenediamine), and Ar ³ is a 4,4′-biphenylylene group. Those (4,4′-dihydroxybiphenyl, 4-amino-4′-hydroxybiphenyl or repeating units derived from 4,4′-diaminobiphenyl) are preferred.

  The content of the repeating unit (1) is the total amount of all repeating units (the mass equivalent amount of each repeating unit (moles by dividing the mass of each repeating unit constituting the liquid crystal polyester by the formula amount of each repeating unit). ) And the total value thereof) is usually 30 mol% or more, preferably 30 to 80 mol%, more preferably 30 to 60 mol%, still more preferably 30 to 40 mol%. The content of the repeating unit (2) is usually 35 mol% or less, preferably 10 to 35 mol%, more preferably 20 to 35 mol%, still more preferably 30 to 35 mol, based on the total amount of all repeating units. %. The content of the repeating unit (3) is usually 35 mol% or less, preferably 10 to 35 mol%, more preferably 20 to 35 mol%, still more preferably 30 to 35 mol, based on the total amount of all repeating units. %. As the content of the repeating unit (1) is increased, the heat resistance, strength and rigidity are likely to be improved. However, if the content is too large, the solubility in a solvent is likely to be lowered.

  The ratio between the content of the repeating unit (2) and the content of the repeating unit (3) is expressed as [content of repeating unit (2)] / [content of repeating unit (3)] (mol / mol). The ratio is usually 0.9 / 1 to 1 / 0.9, preferably 0.95 / 1 to 1 / 0.95, and more preferably 0.98 / 1 to 1 / 0.98.

  In addition, liquid crystalline polyester may have 2 or more types of repeating units (1)-(3) each independently. Further, the liquid crystalline polyester may have a repeating unit other than the repeating units (1) to (3), but the content thereof is usually 10 mol% or less with respect to the total amount of all repeating units, preferably 5 mol% or less.

  The liquid crystalline polyester has a repeating unit (3) in which X and / or Y is an imino group, that is, a repeating unit derived from a predetermined aromatic hydroxylamine and / or a repeating unit derived from an aromatic diamine. It is preferable that it has a solubility in a solvent, and it is more preferable that the repeating unit (3) has only those in which X and / or Y is an imino group.

  The liquid crystal polyester is preferably produced by melt polymerization of raw material monomers corresponding to the repeating units constituting the liquid crystal polyester, and solid-phase polymerization of the obtained polymer (prepolymer). Thereby, high molecular weight liquid crystal polyester having high heat resistance, strength and rigidity can be produced with good operability. Melt polymerization may be carried out in the presence of a catalyst. Examples of this catalyst include metal compounds such as magnesium acetate, stannous acetate, tetrabutyl titanate, lead acetate, sodium acetate, potassium acetate, and antimony trioxide, And nitrogen-containing heterocyclic compounds such as 4- (dimethylamino) pyridine and 1-methylimidazole, and nitrogen-containing heterocyclic compounds are preferably used.

  The liquid polyester has a flow initiation temperature of usually 250 ° C. or higher, preferably 250 ° C. to 350 ° C., more preferably 260 ° C. to 330 ° C. As the flow start temperature is higher, the heat resistance, strength, and rigidity are more likely to be improved. However, if the flow start temperature is too high, the solubility in a solvent tends to be low, and the viscosity of the liquid composition tends to be high.

The flow start temperature is also called flow temperature or flow temperature, and the temperature is raised at a rate of 4 ° C./min under a load of 9.8 MPa (100 kg / cm ² ) using a capillary rheometer while the liquid crystalline polyester is used. Is a temperature showing a viscosity of 4800 Pa · s (48000 poise) when extruded from a nozzle having an inner diameter of 1 mm and a length of 10 mm, and is a measure of the molecular weight of the liquid crystalline polyester (Naide Koide, “ “Liquid Crystal Polymer—Synthesis / Molding / Application—”, CMC Co., Ltd., June 5, 1987, p. 95).

  The liquid composition of the present invention contains a liquid crystal polyester, a solvent, and an inorganic filler. As the solvent, a liquid crystal polyester to be used can be dissolved, specifically, a concentration of 1% by mass or more at 50 ° C. Those that are soluble in ([Liquid Crystalline Polyester] / [Liquid Crystalline Polyester + Solvent]) are appropriately selected and used.

  Examples of solvents include halogenated hydrocarbons such as dichloromethane, chloroform, 1,2-dichloroethane, 1,1,2,2-tetrachloroethane, o-dichlorobenzene; p-chlorophenol, pentachlorophenol, pentafluorophenol Halogenated phenols such as diethyl ether, tetrahydrofuran, 1,4-dioxane, etc .; ketones such as acetone and cyclohexanone; esters such as ethyl acetate and γ-butyrolactone; carbonates such as ethylene carbonate and propylene carbonate; amines such as triethylamine Nitrogen-containing heteroaromatic compounds such as pyridine; nitriles such as acetonitrile and succinonitrile; amides such as N, N-dimethylformamide, N, N-dimethylacetamide and N-methylpyrrolidone; Urea compounds such as tramethylurea; nitro compounds such as nitromethane and nitrobenzene; sulfur compounds such as dimethyl sulfoxide and sulfolane; and phosphorus compounds such as hexamethylphosphoric acid amide and tri-n-butylphosphoric acid. It may be used.

  As the solvent, since it is low in corrosivity and easy to handle, an aprotic compound, particularly a solvent mainly comprising an aprotic compound having no halogen atom, is preferred, and the proportion of the aprotic compound in the entire solvent is: Preferably it is 50-100 mass%, More preferably, it is 70-100 mass%, More preferably, it is 90-100 mass%. As the aprotic compound, amides such as N, N-dimethylformamide, N, N-dimethylacetamide and N-methylpyrrolidone are preferably used because the liquid crystalline polyester is easily dissolved.

  Moreover, as a solvent, since it is easy to melt | dissolve liquid crystalline polyester, the solvent which has a compound whose dipole moment is 3-5 as a main component is preferable, and the ratio of the compound whose dipole moment which occupies for the whole solvent is 3-5 Is preferably 50 to 100% by mass, more preferably 70 to 100% by mass, and still more preferably 90 to 100% by mass, and a compound having a dipole moment of 3 to 5 is used as the aprotic compound. Is preferred.

  Moreover, as a solvent, since it is easy to remove, the solvent which has as a main component the compound whose boiling point in 1 atmosphere is 220 degrees C or less is preferable, and the ratio of the compound whose boiling point in 1 atmosphere in the whole solvent is 220 degrees C or less Is preferably 50 to 100% by mass, more preferably 70 to 100% by mass, and still more preferably 90 to 100% by mass, and a compound having a boiling point of 220 ° C. or less at 1 atm is used as the aprotic compound. It is preferable.

  Content of the liquid crystal polyester in a liquid composition is 5-60 mass% normally with respect to the total amount of liquid crystal polyester and a solvent, Preferably it is 10-50 mass%, More preferably, it is 15-45 mass%, desired It adjusts suitably so that the liquid composition of this viscosity may be obtained.

  The liquid composition may contain one or more other components such as a filler, an additive, and a resin other than liquid crystal polyester.

  Examples of fillers include inorganic fillers such as silica, alumina, titanium oxide, barium titanate, strontium titanate, aluminum hydroxide, calcium carbonate; and organic fillers such as cured epoxy resins, crosslinked benzoguanamine resins, and crosslinked acrylic resins A material is mentioned, The content is 0-100 mass parts normally with respect to 100 mass parts of liquid crystalline polyester.

  Examples of additives include leveling agents, antifoaming agents, antioxidants, ultraviolet absorbers, flame retardants, dyes and pigments, and the content thereof is usually 0 with respect to 100 parts by mass of the liquid crystalline polyester. -5 parts by mass.

  Examples of resins other than liquid crystal polyester include polypropylene, polyamide, polyester other than liquid crystal polyester, thermoplastic resin other than liquid crystal polyester such as polyphenylene sulfide, polyether ketone, polycarbonate, polyether sulfone, polyphenylene ether, polyether imide; and Thermosetting resins, such as a phenol resin, an epoxy resin, a polyimide resin, a cyanate resin, are mentioned, The content is 0-20 mass parts normally with respect to 100 mass parts of liquid crystalline polyester.

  The liquid composition can be prepared by mixing the liquid crystal polyester, the solvent, and other components used as necessary, all at once or in an appropriate order. It is preferable to prepare it by dissolving it in a liquid crystal polyester solution and dispersing a filler in the liquid crystal polyester solution.

  The liquid composition thus obtained tends to increase in viscosity when stored at room temperature, and may gel when stored for a long time. Therefore, in the present invention, in order to reduce the viscosity of the liquid composition, the liquid composition is subjected to heat treatment, and the heat treatment conditions satisfy the following formulas (1) to (3). Thereby, the viscosity of a liquid composition can be reduced, suppressing decomposition | disassembly of liquid crystalline polyester. The liquid composition may be gelled.

(1) A ≦ 5
(2) 50 ≦ B
(3) A + 0.065B ≦ 10

(A represents the water | moisture content (mass%) of the said liquid composition. B represents the heat processing temperature (degreeC).

  The moisture A of the liquid composition is preferably 0.05 to 3% by mass, more preferably 0.1 to 1.5% by mass. The lower the moisture A, the higher the upper limit of the heat treatment temperature B for satisfying the formula (3). Even when the heat treatment temperature B is high, the decomposition of the liquid crystalline polyester can be suppressed, and the heat treatment time required for viscosity reduction can be shortened. The preparation of the composition takes time, and the liquid composition needs to be dehydrated.

  The heat treatment temperature B is preferably 60 to 140 ° C, more preferably 70 to 110 ° C. The lower the heat treatment temperature B, the higher the upper limit of the moisture A of the liquid composition for satisfying the formula (3). The upper limit of the heat treatment temperature B is 154 ° C. according to the equation (3) (when A = 0, B ≦ 10 / 0.065≈154 ° C.).

  In order to prepare a liquid composition having a low moisture A, it is preferable to mix a low moisture liquid crystal polyester and a low moisture solvent in a low moisture gas atmosphere. The low moisture liquid crystal polyester can be obtained by drying the liquid crystal polyester in a low moisture atmosphere. Moreover, as a low moisture solvent, a commercially available dehydrating solvent for organic synthesis may be used, or a desiccant or a solvent dehydrated by distillation may be used.

  The heat treatment time is usually 1 to 20 hours, preferably 2 to 10 hours. If the heat treatment time is too long, the liquid crystal polyester is easily decomposed, and if it is too short, it is difficult to reduce the viscosity of the liquid composition.

  The heat treatment method of the present invention is preferably applied to a liquid composition whose viscosity has increased by storage or the like, specifically, a liquid composition whose viscosity at 23 ° C. has increased to 500 cP or more. Can be reduced to 500 cP or less.

  The liquid composition thus heat-treated can be used for the production of a liquid crystal polyester film or a liquid crystal polyester impregnated fiber sheet.

[Measurement of flow start temperature of liquid crystalline polyester]
Using a flow tester (“CFT-500 type” manufactured by Shimadzu Corporation), about 2 g of liquid crystalline polyester was filled into a cylinder attached with a die having a nozzle having an inner diameter of 1 mm and a length of 10 mm, and 9.8 MPa (100 kg). The liquid crystal polyester was melted while being heated at a rate of 4 ° C./min under a load of / cm ² ), extruded from a nozzle, and a temperature showing a viscosity of 4800 Pa · s (48000 P) was measured.

[Measurement of moisture of liquid composition]
It measured by the Karl Fischer method using the trace moisture measuring apparatus ("AQ-2000" of Hiranuma Sangyo Co., Ltd.).

[Measurement of viscosity of liquid composition]
Using a B-type viscometer (“TVL-20” from Toki Sangyo Co., Ltd.) The measurement was performed at a rotation speed of 20 rpm using 21 rotors.

[Measurement of intrinsic viscosity of liquid crystal polyester in liquid composition]
The liquid composition was diluted with N, N-dimethylacetamide to adjust the concentration of liquid crystal polyester to 0.5 g / dl and measured at 25 ° C. using an Ubbelohde type clay meter. This intrinsic viscosity is an indicator of the molecular weight of the liquid crystal polyester in the liquid composition, and the degree of decrease thereof is an indicator of the degree of decomposition of the liquid crystal polyester.

[Production of liquid crystalline polyester]
In a reactor equipped with a stirrer, a torque meter, a nitrogen gas introduction tube, a thermometer and a reflux condenser, 1976 g (10.5 mol) of 6-hydroxy-2-naphthoic acid and 1474 g (9.75 mol) of 4-hydroxyacetanilide were added. ), 1620 g (9.75 mol) of isophthalic acid and 2374 g (23.25 mol) of acetic anhydride, and after replacing the gas in the reactor with nitrogen gas, the mixture was stirred at room temperature to 150 ° C. under a nitrogen gas stream. The mixture was heated up to 15 minutes and refluxed at 150 ° C. for 3 hours. Next, while distilling off by-product acetic acid and unreacted acetic anhydride, the temperature was raised from 150 ° C. to 300 ° C. over 2 hours and 50 minutes, held at 300 ° C. for 1 hour, then the contents were taken out from the reactor, Cooled to room temperature. The obtained solid was pulverized with a pulverizer to obtain a powdery prepolymer. The flow initiation temperature of this prepolymer was 235 ° C. Next, the prepolymer was heated from room temperature to 223 ° C. over 6 hours under a nitrogen atmosphere and held at 223 ° C. for 3 hours to solid-phase polymerize, and then cooled to powdery liquid crystalline polyester Got. The liquid crystal polyester had a flow start temperature of 270 ° C.

(Preparation of liquid composition)
After 2200 g of liquid crystalline polyester was dried in a ventilated oven at 120 ° C. for 2 hours, added to 7800 g of N, N-dimethylacetamide, heated in a nitrogen atmosphere at 100 ° C. for 2 hours, then cooled to form a liquid composition as a solution Obtained. This liquid composition had a moisture A of 0.2% by mass and a viscosity (23 ° C.) of 225 cP. Moreover, the intrinsic viscosity of the liquid crystal polyester in this liquid composition was 0.32.

[Storage of liquid composition]
The obtained liquid composition was stored in a sealed container at 23 ° C. for 1 week. The viscosity (23 ° C.) of the liquid composition after storage was 850 cP.

Examples 1-4
The liquid composition after storage was heat-treated in a closed container for 4 hours at a temperature B shown in Table 1 using a ventilated oven (“SPS-222 type” from Tabai Espec Co., Ltd.), then cooled, The intrinsic viscosity of the liquid crystal polyester was measured. The results are shown in Table 1.

Examples 5-16, Comparative Examples 1-4
To the liquid composition after storage, water was added so as to have the moisture A shown in Table 1, and the mixture was mixed with a stirring deaerator (“AR-500” manufactured by Sinky Corporation). Then, after cooling for 4 hours, the mixture was cooled and the intrinsic viscosity of the liquid crystal polyester in the liquid composition was measured. The results are shown in Table 1.

Claims (7)

A liquid composition containing a liquid crystal polyester and a solvent containing 50% by mass or more of an aprotic compound and having a viscosity at 23 ° C. increased to 500 cP or more by storage under conditions satisfying the following formulas (1) to (3): A heat treatment method for the liquid composition.
(1) A ≦ 5
(2) 50 ≦ B
(3) A + 0.065B ≦ 10
(A represents the water | moisture content (mass%) of the said liquid composition. B represents the heat processing temperature (degreeC). The liquid crystalline polyester is a liquid crystalline polyester having a repeating unit represented by the following formula (1), a repeating unit represented by the following formula (2), and a repeating unit represented by the following formula (3). 2. The heat treatment method according to 1.
(1) —O—Ar ¹ —CO—
(2) —CO—Ar ² —CO—
⁽³⁾ -X-Ar 3 -Y-
(Ar ¹ represents a phenylene group, a naphthylene group, or a biphenylylene group. Ar ² and Ar ³ each independently represent a phenylene group, a naphthylene group, a biphenylylene group, or a group represented by the following formula (4). X And Y each independently represents an oxygen atom or an imino group, and each hydrogen atom in the group represented by Ar ¹ , Ar ² or Ar ³ is independently substituted with a halogen atom, an alkyl group or an aryl group. May be.)
(4) -Ar ⁴ -Z-Ar ^5-
(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.)   The liquid crystal polyester has a repeating unit represented by the formula (1) of 30 to 80 mol% and a repeating unit represented by the formula (2) of 10 with respect to the total amount of all repeating units constituting the liquid crystalline polyester. The heat treatment method according to claim 2, which is a liquid crystal polyester having 35 to 35 mol% and 10 to 35 mol% of the repeating unit represented by the formula (3).   The heat treatment method according to claim 2 or 3, wherein X and / or Y is an imino group.   The heat treatment method according to claim 1, wherein the aprotic compound is an aprotic compound having no halogen atom.   The heat treatment method according to claim 1, wherein the aprotic compound is an amide.   The heat treatment method according to any one of claims 1 to 6, wherein a content of the liquid crystal polyester is 10 to 50% by mass with respect to a total amount of the liquid crystal polyester and the solvent.