JP2024108735A - Liquid Crystal Polyester Resin - Google Patents

Abstract

To provide a liquid crystal polyester resin which is excellent in toughness.SOLUTION: A liquid crystal polyester resin includes repeating units represented by formulae [I] to [V] (wherein, p, q, r, s and t are composition ratios (mol%) in liquid crystal polyester resins of the respective repeating units, and satisfy the following conditions: 9≤p≤25, 17≤q≤25, 17≤r≤25, 17≤s≤25, 17≤t≤25, and p+q+r+s+t=100), wherein tensile strain measured according to JIS K 7161 is 7.0% or more.SELECTED DRAWING: None

Description

The present invention relates to a liquid crystal polyester resin with excellent toughness.

Liquid crystal polyester has good fluidity and is less likely to produce burrs. It also has excellent mechanical properties such as heat resistance and rigidity, chemical resistance, and dimensional accuracy, so its use is increasing in electrical and electronic parts with complex shapes.

In recent years, electrical and electronic parts have become thinner and more complex in shape as they become smaller and lighter. This calls for high product strength in molded products made from liquid crystal polyester. However, applications such as motors in particular require not only strength but also the tenacity to be able to appropriately deform in response to external forces, i.e. toughness.

It is generally known that the toughness of liquid crystal polyester can be improved by blending it with a filler or other resin. For example, a liquid crystal polyester resin composition containing mica with a volume average particle size of 10 to 50 μm and an aspect ratio of 50 to 100 (Patent Document 1) and a resin composition characterized by blending a polycarbonate resin and a liquid crystal resin (Patent Document 2) have been proposed.

International Publication No. WO 2013/128887 JP 2002-363395 A

However, adding a large amount of filler to further improve toughness has a negative effect on the resin's physical properties, such as flexibility, so there is a limit to the amount of filler that can be added. In addition, if a blending process is required, there is also the issue of increased costs. For this reason, there has been a demand for improving the toughness of the liquid crystal polyester resin itself.

The object of the present invention is to provide a liquid crystal polyester resin with excellent toughness.

In view of the above problems, the inventors conducted intensive research and discovered that liquid crystal polyester resins with excellent toughness can be obtained by using specific repeating units as constituent components, leading to the completion of the present invention.

［式中、ｐ、ｑ、ｒ、ｓおよびｔは、それぞれ各繰返し単位の液晶ポリエステル樹脂中での組成比（モル％）であり、以下の条件を満たす：
９≦ｐ≦２５、
１７≦ｑ≦２５、
１７≦ｒ≦２５、
１７≦ｓ≦２５、
１７≦ｔ≦２５、
ｐ＋ｑ＋ｒ＋ｓ＋ｔ＝１００］
で表される繰返し単位を含んで構成され、ＪＩＳ Ｋ７１６１に準拠して測定した引張ひずみが７．０％以上である液晶ポリエステル樹脂。
［２］ｒ／ｑ＝０．６～１．４を満たす、［１］に記載の液晶ポリエステル樹脂。
［３］ｒ≦ｑを満たす、［１］または［２］に記載の液晶ポリエステル樹脂。
［４］ｓ／ｔ＝０．６～１．４を満たす、［１］～［３］のいずれかに記載の液晶ポリエステル樹脂。
［５］［１］～［４］のいずれかに記載の液晶ポリエステル樹脂と無機充填材および／または有機充填材を含む、液晶ポリエステル樹脂組成物。
［６］無機充填材および／または有機充填材は、ガラス繊維、シリカアルミナ繊維、アルミナ繊維、炭素繊維、チタン酸カリウム繊維、ホウ酸アルミニウム繊維、アラミド繊維、タルク、マイカ、グラファイト、ウォラストナイト、ドロマイト、クレイ、ガラスフレーク、ガラスビーズ、ガラスバルーン、炭酸カルシウム、硫酸バリウム、および酸化チタンからなる群から選択される１種以上である、［５］に記載の液晶ポリエステル樹脂組成物。
［７］［１］～［４］のいずれかに記載の液晶ポリエステル樹脂あるいは［５］または［６］に記載の液晶ポリエステル樹脂組成物から構成される、成形品、フィルムまたは繊維からなる物品。 That is, the present invention includes the following preferred embodiments.
[1] Formulas [I] to [V]

[In the formula, p, q, r, s and t each represent a composition ratio (mol %) of each repeating unit in the liquid crystal polyester resin, and satisfy the following conditions:
9≦p≦25,
17≦q≦25,
17≦r≦25,
17≦s≦25,
17≦t≦25,
p+q+r+s+t=100]
and having a tensile strain of 7.0% or more as measured in accordance with JIS K7161.
[2] The liquid crystal polyester resin according to [1], wherein r/q is 0.6 to 1.4.
[3] The liquid crystal polyester resin according to [1] or [2], wherein r≦q is satisfied.
[4] The liquid crystal polyester resin according to any one of [1] to [3], wherein s/t is 0.6 to 1.4.
[5] A liquid crystal polyester resin composition comprising the liquid crystal polyester resin according to any one of [1] to [4] and an inorganic filler and/or an organic filler.
[6] The liquid crystal polyester resin composition according to [5], wherein the inorganic filler and/or organic filler is at least one selected from the group consisting of glass fiber, silica alumina fiber, alumina fiber, carbon fiber, potassium titanate fiber, aluminum borate fiber, aramid fiber, talc, mica, graphite, wollastonite, dolomite, clay, glass flakes, glass beads, glass balloons, calcium carbonate, barium sulfate, and titanium oxide.
[7] An article made of a molded article, a film or a fiber, which is composed of the liquid crystal polyester resin according to any one of [1] to [4] or the liquid crystal polyester resin composition according to [5] or [6].

According to the present invention, a liquid crystal polyester resin with excellent toughness can be obtained.

FIG. 2 is a schematic diagram of a dumbbell-shaped test piece used in the tensile strain tests of the examples and comparative examples.

The liquid crystal polyester resin of the present invention is a liquid crystal polyester resin that forms an anisotropic molten phase, which is known to those skilled in the art as a thermotropic liquid crystal polyester resin.

The properties of the anisotropic molten phase of liquid crystal polyester resin can be confirmed by the conventional deflection inspection method using cross polarizers, i.e., by observing a sample placed on a hot stage under a nitrogen atmosphere.

［式中、ｐ、ｑ、ｒ、ｓおよびｔは、それぞれ各繰返し単位の液晶ポリエステル樹脂中での組成比（モル％）であり、以下の条件を満たす：
９≦ｐ≦２５、
１７≦ｑ≦２５、
１７≦ｒ≦２５、
１７≦ｓ≦２５、
１７≦ｔ≦２５、
ｐ＋ｑ＋ｒ＋ｓ＋ｔ＝１００］ The liquid crystal polyester resin of the present invention is constituted by containing repeating units represented by the formulae [I] to [V].

[In the formula, p, q, r, s and t each represent a composition ratio (mol %) of each repeating unit in the liquid crystal polyester resin, and satisfy the following conditions:
9≦p≦25,
17≦q≦25,
17≦r≦25,
17≦s≦25,
17≦t≦25,
p+q+r+s+t=100]

The composition ratio p in formula [I] is 9 to 25 mol%, preferably 9.5 to 22 mol%, more preferably 10 to 19 mol%, even more preferably 10.5 to 16 mol%, and particularly preferably 11 to 14 mol%.

If the repeating unit represented by formula [I] is less than 9 mol%, the impact strength will be low, and if it exceeds 25 mol%, the melting point will be low and heat resistance will be low.

Specific examples of monomers that provide the repeating unit represented by formula [I] include, for example, 4-hydroxybenzoic acid and its acylation products, ester derivatives, acid halides, and other ester-forming derivatives.

The composition ratio q in formula [II] is 17 to 25 mol%, preferably 18 to 24.5 mol%, more preferably 19 to 24 mol%, even more preferably 20 to 23.5 mol%, particularly preferably 21 to 23 mol%, and more particularly preferably 21.5 to 22.5 mol%.

Specific examples of monomers that provide the repeating unit represented by formula [II] include hydroquinone and its acylated and other ester-forming derivatives.

The composition ratio r in formula [III] is 17 to 25 mol%, preferably 18 to 24.5 mol%, more preferably 19 to 24 mol%, even more preferably 20 to 23.5 mol%, particularly preferably 21 to 23 mol%, and more particularly preferably 21.5 to 22.5 mol%.

Specific examples of monomers that give the repeating unit represented by formula [III] include 4,4'-dihydroxybiphenyl and its acylated and other ester-forming derivatives.

The composition ratio s of formula [IV] is 17 to 25 mol%, preferably 18 to 24.5 mol%, more preferably 19 to 24 mol%, even more preferably 20 to 23.5 mol%, particularly preferably 21 to 23 mol%, and more particularly preferably 21.5 to 22.5 mol%.

Specific examples of monomers that provide the repeating unit represented by formula [IV] include terephthalic acid, as well as its ester derivatives and ester-forming derivatives such as acid halides.

The composition ratio t in formula [V] is 17 to 25 mol%, preferably 18 to 24.5 mol%, more preferably 19 to 24 mol%, even more preferably 20 to 23.5 mol%, particularly preferably 21 to 23 mol%, and more particularly preferably 21.5 to 22.5 mol%.

Specific examples of monomers that give the repeating unit represented by formula [V] include 2,6-naphthalenedicarboxylic acid, as well as its ester derivatives and ester-forming derivatives such as acid halides.

The composition ratio q in formula [II] and the composition ratio r in formula [III] are preferably r/q 0.6 to 1.4, more preferably r/q 0.8 to 1.2, and even more preferably r/q 0.9 to 1.1. It is also preferable that r≦q, i.e., r/q is 1 or less, and it is particularly preferable that they are equimolar.

The composition ratio s in formula [IV] and the composition ratio t in formula [V] are preferably s/t in the range of 0.6 to 1.4, more preferably 0.8 to 1.2, even more preferably 0.9 to 1.1, and are particularly preferably equimolar.

The total composition ratio of the repeating units in the liquid crystal polyester resin of the present invention [p+q+r+s+t] is preferably 100 mol %, but other repeating units may also be contained within a range that does not impair the object of the present invention.

Examples of monomers that provide other repeating units include other aromatic hydroxycarboxylic acids, aromatic diols, aromatic dicarboxylic acids, aromatic hydroxyamines, aromatic diamines, aromatic aminocarboxylic acids, aromatic hydroxydicarboxylic acids, aliphatic diols, aliphatic dicarboxylic acids, aromatic mercaptocarboxylic acids, aromatic dithiols, aromatic mercaptophenols, and combinations of these.

The total composition ratio of the repeating units provided by these other monomer components is preferably 10 mol % or less of the total repeating units.

The method for producing the liquid crystal polyester resin of the present invention will be described below.
The method for producing the liquid crystal polyester resin of the present invention is not particularly limited, and any known polycondensation method for forming an ester bond from the above-mentioned monomer components, such as a melt acidolysis method or a slurry polymerization method, can be used.

The molten acidolysis method is a method suitable for producing the liquid crystal polyester resin of the present invention, in which the monomers are first heated to form a molten liquid of the reactants, and the reaction is continued to obtain a molten polyester. A vacuum may be applied to facilitate the removal of volatile by-products (e.g., acetic acid, water, etc.) produced in the final stage of condensation.

Slurry polymerization is a process in which the reaction is carried out in the presence of a heat exchange fluid, and the solid product is obtained in a state suspended in the heat exchange medium.

In both the molten acidolysis method and the slurry polymerization method, the polymerizable monomer components used in producing the liquid crystal polyester resin can be subjected to the reaction at room temperature in a modified form in which the hydroxyl groups are acylated, i.e., as lower acylated products. The lower acyl groups preferably have 2 to 5 carbon atoms, and more preferably have 2 or 3 carbon atoms. Particularly preferred is a method in which an acetylated product of the monomer component is used in the reaction.

The lower acylated monomer may be synthesized in advance by separate acylation, or may be produced in the reaction system by adding an acylating agent such as acetic anhydride to the monomer during the production of the liquid crystal polyester resin.

In either the molten acidolysis method or the slurry polymerization method, a catalyst may be used during the reaction, if necessary.

Specific examples of the catalyst include, for example, organic tin compounds (dialkyl tin oxides such as dibutyltin oxide, diaryl tin oxides, etc.), titanium dioxide, antimony trioxide, organic titanium compounds (alkoxy titanium silicates, titanium alkoxides, etc.), alkali and alkaline earth metal salts of carboxylic acids (potassium acetate, sodium acetate, etc.), Lewis acids ( _BF3 , etc.), gaseous acid catalysts such as hydrogen halides (HCl, etc.), and the like.

The amount of catalyst used is preferably 10 to 1000 ppm, more preferably 20 to 200 ppm, based on the mass of monomer.

The liquid crystal polyester resin obtained by such a polycondensation reaction is extracted in a molten state from the polymerization reaction tank, processed into pellets, flakes, or powder, and then subjected to molding processing or melt kneading.

Liquid crystal polyester resin in pellet, flake, or powder form may be heat-treated in a substantially solid state under reduced pressure, vacuum, or in an atmosphere of an inert gas such as nitrogen or helium in order to increase the molecular weight and improve heat resistance.

The heat treatment temperature is not particularly limited as long as the liquid crystal polyester resin does not melt, but is preferably 260 to 350°C, and more preferably 280 to 320°C.

The liquid crystal polyester resin of the present invention preferably has a melt viscosity of 10 to 100 Pa·s, more preferably 12 to 60 Pa·s, measured using a capillary rheometer (Capillograph 1D manufactured by Toyo Seiki Co., Ltd.) with a capillary of 0.7 mmφ×10 mm under a shear rate of 1000 s ⁻¹ at a crystal melting temperature of +20° C.

The tensile strain of the liquid crystal polyester resin of the present invention is 7.0% or more, preferably 7.1% or more, and more preferably 7.2% or more. The measured values of tensile strain in this specification are values measured in accordance with JIS K7161 by the measurement method described in the examples below.

The average elongation of the liquid crystal polyester resin of the present invention is preferably 15% or more, more preferably 17% or more, and even more preferably 20% or more.

The elongation (maximum) of the liquid crystal polyester resin of the present invention is preferably 36% or more, more preferably 38% or more, and even more preferably 40% or more. The measured elongation values in this specification are values measured by the measurement method described in the examples below.

The larger the tensile strain and elongation, the better the toughness. It is preferable that the measured values of the tensile strain and elongation of the liquid crystal polyester resin of the present invention are within the above ranges, since the resin has excellent toughness.

The liquid crystal polyester resin of the present invention obtained as described above can be made into a liquid crystal polyester resin composition containing inorganic fillers and/or organic fillers, additives, other resin components, etc.

Specific examples of inorganic and/or organic fillers that may be contained in the liquid crystal polyester resin composition of the present invention include glass fibers, silica alumina fibers, alumina fibers, carbon fibers, potassium titanate fibers, aluminum borate fibers, aramid fibers, talc, mica, graphite, wollastonite, dolomite, clay, glass flakes, glass beads, glass balloons, calcium carbonate, barium sulfate, titanium oxide, etc. These fillers may be used alone or in combination of two or more.

Among these, talc and glass fiber are preferred because they offer an excellent balance between mechanical properties and cost.

When an inorganic filler and/or an organic filler is contained, the content is preferably 1 to 150 parts by mass, and more preferably 10 to 100 parts by mass, per 100 parts by mass of the liquid crystal polyester resin.

When the content of inorganic filler and/or organic filler is 1 part by mass or more, the liquid crystal polyester resin composition is likely to have an improved mechanical strength. When the content of inorganic filler and/or organic filler exceeds 150 parts by mass, flexibility tends to decrease.

Specific examples of other additives that may be contained in the liquid crystal polyester resin composition of the present invention include lubricants such as higher fatty acids, higher fatty acid esters, higher fatty acid amides, and higher fatty acid metal salts (here, higher fatty acids refer to those having 10 to 25 carbon atoms), release agents such as polysiloxanes and fluororesins, colorants such as dyes, pigments, and carbon black, flame retardants, antistatic agents, surfactants, antioxidants such as phosphorus-based antioxidants, phenolic antioxidants, and sulfur-based antioxidants, weather resistance agents, heat stabilizers, and neutralizing agents. These additives may be used alone or in combination of two or more.

When these additives are contained, the total content is preferably 0.01 to 10 parts by mass, and more preferably 0.1 to 3 parts by mass, per 100 parts by mass of the liquid crystal polyester resin.

When a function is expressed by adding an additive, if the content is less than 0.01 parts by mass, the function of the additive tends to be difficult to realize, and if the content exceeds 10 parts by mass, the thermal stability of the liquid crystal polyester resin composition during molding processing tends to deteriorate.

When additives such as lubricants and release agents are used among the other additives, they may be added when preparing the liquid crystal polyester resin composition, or may be attached to the surface of the liquid crystal polyester resin pellets during molding.

Specific examples of other resin components that may be contained in the liquid crystal polyester resin composition of the present invention include thermoplastic resins such as polyamide, polyester, polyacetal, polyphenylene ether and modified products thereof, polysulfone, polyethersulfone, polyetherimide, and polyamideimide, and thermosetting resins such as phenolic resin, epoxy resin, and polyimide resin. These resin components may be used alone or in combination of two or more.

When the above-mentioned other resin components are contained, the content is preferably 0.1 to 100 parts by mass, and more preferably 0.5 to 80 parts by mass, per 100 parts by mass of the liquid crystal polyester resin.

The liquid crystal polyester resin composition can be obtained by mixing the liquid crystal polyester resin with inorganic fillers and/or fillers, additives or other resin components, and melt-kneading the mixture at temperatures ranging from the crystalline melting temperature of the liquid crystal polyester resin to the crystalline melting temperature + 50°C using a Banbury mixer, kneader, single-screw or twin-screw extruder, or the like.

The liquid crystal polyester resin or liquid crystal polyester resin composition of the present invention thus obtained is processed into articles such as molded articles, films, or fibers by known processing methods such as injection molding, compression molding, extrusion molding, and blow molding.

The liquid crystal polyester resin or liquid crystal polyester resin composition of the present invention has excellent toughness and can be suitably used for motor applications, film applications, etc.

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

The physical properties in the examples were measured using the following methods.

<Crystal Melting Temperature>
The measurement was carried out using a differential scanning calorimeter (DSC) Exstar 6000 manufactured by Seiko Instruments Inc. The liquid crystal polymer sample was heated from 40°C to 375°C under a temperature increase condition of 20°C/min, and then held for 10 minutes. Next, the sample was cooled to 50°C under a temperature decrease condition of 20°C/min, and then measured again under a temperature increase condition of 20°C/min up to 375°C. The endothermic peak was observed, and the temperature showing the peak top was taken as the crystalline melting temperature of the liquid crystal polymer. In addition, when multiple peaks were observed, the side with the larger peak area (the side with the larger melting enthalpy) was taken as the crystalline melting temperature.

<Melt Viscosity>
The melt viscosity was measured at the measurement temperature shown in Table 1 (crystal melting temperature + 20° C.) using a melt viscosity measuring device (Capillograph 1D, manufactured by Toyo Seiki Seisakusho Co., Ltd.) and a capillary of 0.7 mmφ×10 mm under the condition of a shear rate of 1000 sec ⁻¹ .

Tensile strain
Using an injection molding machine (MINIMAT M26/15 manufactured by Sumitomo Heavy Industries, Ltd.) with a clamping pressure of 15 t, injection molding was performed at a cylinder temperature shown in Table 1 and a mold temperature of 70° C. to obtain dumbbell-shaped test pieces having a thickness of 2.0 mm as shown in Figure 1. Tensile tests were performed using an INSTRON 5567 (a universal testing machine manufactured by Instron Japan Co., Ltd.) with a span distance of 25.4 mm and a tensile speed of 5.0 mm/min.

<Flexural strength and flexural modulus>
Using an injection molding machine (MINIMAT M26/15 manufactured by Sumitomo Heavy Industries, Ltd.) with a clamping pressure of 15 t, injection molding was performed at a cylinder temperature of the molding temperature shown in Table 1 and a mold temperature of 70° C. to prepare rectangular test pieces (length 65 mm × width 12.7 mm × thickness 2.0 mm). The bending test was a three-point bending test using an INSTRON 5567 (a universal testing machine manufactured by Instron Japan Co., Ltd.) in accordance with ASTM D790, with a span distance of 40.0 mm and a compression speed of 1.3 mm/min.

<stretch>
Using a vacuum press (IMC1A36 manufactured by Imoto Manufacturing Co., Ltd.), press molding was performed at a pressure of 50 MPa for 3 minutes at the molding temperature shown in Table 1 to prepare rectangular test pieces (length 80 mm x width 10 mm x thickness 0.13 mm). Elongation was measured five times using an autograph (Universal testing machine AG-Xplus manufactured by Shimadzu Corporation) at a span distance of 40.0 mm and a tensile speed of 5.0 mm/min, and the maximum and average elongation (%) of the rectangular test pieces were calculated.

<Izod impact strength>
Using an injection molding machine (MINIMAT M26/15 manufactured by Sumitomo Heavy Industries, Ltd.) with a mold clamping pressure of 15 t, injection molding was performed at a cylinder temperature of the molding temperature shown in Table 1 and a mold temperature of 70°C. Strip-shaped test pieces (length 65 mm x width 12.7 mm x thickness 2.0 mm) were prepared and notched, and then measured in accordance with ASTM D256.

In the examples, the following abbreviations represent the following compounds.
LCP: Liquid crystal polymer POB: 4-hydroxybenzoic acid BON6: 6-hydroxy-2-naphthoic acid HQ: Hydroquinone BP: 4,4'-dihydroxybiphenyl TPA: Terephthalic acid NDA: 2,6-naphthalenedicarboxylic acid

[Example 1]
In a reaction vessel equipped with a torque meter-equipped stirrer and a distillation tube, POB, HQ, BP, TPA and NDA were charged in a total amount of 6.5 moles in the composition ratio shown below, and acetic anhydride was further charged in an amount 1.05 times the moles of hydroxyl groups (moles) of all monomers, and deacetic acid polymerization was performed under the following conditions. The temperature was raised from room temperature to 150°C over 1 hour in a nitrogen gas atmosphere, and the temperature was maintained at the same temperature for 30 minutes. Next, the temperature was quickly raised to 240°C while distilling off the by-product acetic acid, and the temperature was maintained at the same temperature for 30 minutes. After that, the temperature was raised to 350°C over 5 hours, and the pressure was reduced to 20 mmHg over 30 minutes. The polymerization reaction was terminated when a predetermined torque was indicated, the contents were removed from the reaction vessel, and pellets of liquid crystal polymer 1 were obtained using a pulverizer. The amount of acetic acid distilled during polymerization was almost the theoretical value. The physical properties of the obtained LCP were measured. The results are shown in Table 1.
POB: 107.9 g (12 mol%)
HQ: 157.8 g (22 mol%)
BP: 266.8 g (22 mol%)
TPA: 237.7 g (22 mol%)
NDA: 309.3 g (22 mol%)

[Examples 2 to 4, Comparative Examples 1 to 4]
LCPs were obtained in the same manner as in Example 1, except that the raw material monomers were charged in the mole percentages shown in Table 1. The physical properties of each of the obtained LCPs were measured. The results are shown in Table 1.

As is clear from Table 1, it is understood that the liquid crystal polyester resins obtained in Examples 1 to 4 are excellent in toughness (tensile strain and elongation).

Claims (7)

Formulas [I] to [V]

[In the formula, p, q, r, s and t each represent a composition ratio (mol %) of each repeating unit in the liquid crystal polyester resin, and satisfy the following conditions:
9≦p≦25,
17≦q≦25,
17≦r≦25,
17≦s≦25,
17≦t≦25,
p+q+r+s+t=100]
and having a tensile strain of 7.0% or more as measured in accordance with JIS K7161. The liquid crystal polyester resin according to claim 1, which satisfies r/q = 0.6 to 1.4. The liquid crystal polyester resin according to claim 1, which satisfies r≦q. The liquid crystal polyester resin according to claim 1, which satisfies s/t = 0.6 to 1.4. A liquid crystal polyester resin composition comprising the liquid crystal polyester resin according to claim 1 and an inorganic filler and/or an organic filler. The liquid crystal polyester resin composition according to claim 5, wherein the inorganic filler and/or the organic filler is at least one selected from the group consisting of glass fiber, silica alumina fiber, alumina fiber, carbon fiber, potassium titanate fiber, aluminum borate fiber, aramid fiber, talc, mica, graphite, wollastonite, dolomite, clay, glass flakes, glass beads, glass balloons, calcium carbonate, barium sulfate, and titanium oxide. An article consisting of a molded article, a film or a fiber, which is composed of the liquid crystal polyester resin according to any one of claims 1 to 4 or the liquid crystal polyester resin composition according to claim 5 or 6.

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