JP2016147963A - Resin for hydrogen gas tank liner and resin liner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resin which can be blow molded and has excellent hydrogen gas barrier properties even under hygroscopic conditions.SOLUTION: There is provided a resin for a hydrogen gas tank liner which comprises a polyethylene terephthalate (A component) in which (A) a dicarboxylic acid component (A-1 component) is composed of 80 to 100 mol% of (A-1-1 component) naphthalene dicarboxylic acid or an ester derivative thereof and 0 to 20 mol% of (A-1-2 component) at least one selected from the group consisting of terephthalic acid, isophthalic acid and an ester derivative thereof and a diol component (A-2 component) is composed of ethylene glycol.SELECTED DRAWING: None

Description

  The present invention relates to a resin for a liner of a hydrogen gas tank made of polyethylene naphthalate.

In recent years, fuel cell vehicles using hydrogen as a fuel have been actively developed, and a high pressure gas tank is used as a fuel supply source in a fuel cell system used there. As the liner for the high-pressure gas tank, metals and resins such as aluminum and stainless steel are selected, but the metal liner has a heavy specific gravity, and further, small hydrogen gas penetrates into the metal crystal lattice, embrittles the metal, It has a problem that causes so-called hydrogen embrittlement.
On the other hand, resin liners have a lower specific gravity than metals, but have a problem of poor gas barrier properties. Therefore, Patent Document 1 discloses using polyamide as a resin having a high gas barrier property. However, polyamide has a problem that the gas barrier property is lowered by moisture absorption.

  Patent Document 2 proposes a liquid crystal polyester resin for high-pressure hydrogen gas storage. Liquid crystal polyester has a high level of gas barrier properties against all gases, but has a problem that when molding a container, it cannot be blow-molded due to high crystallinity. Therefore, after half of the container is injection-molded, it is necessary to form the container by heat welding or the like, which is complicated in the process.

JP 2010-19315 A JP 2005-126651 A

  An object of the present invention is to provide a resin that can be blow-molded and has excellent hydrogen gas barrier properties even under moisture absorption.

  As a result of intensive research aimed at achieving the above object, the present inventors have found that polyethylene naphthalate can be blow-molded and have excellent hydrogen gas barrier properties even under moisture absorption, leading to the solution of the above problems. .

  That is, the above problem is that (A) the dicarboxylic acid component (A-1 component) is naphthalenedicarboxylic acid or an ester derivative thereof (A-1-1 component) of 80 to 100 mol% and terephthalic acid, isophthalic acid and ester derivatives. It is achieved by a resin for a hydrogen gas tank liner comprising at least one selected from the group (A-1-2 component) 0 to 20 mol%, and the diol component (A-2 component) comprising polyethylene naphthalate comprising ethylene glycol. The

  The resin described in the present invention has an excellent hydrogen gas barrier property even under moisture absorption, and can be easily formed into a container shape by blow molding. Therefore, it is suitable for a resin liner for a hydrogen gas tank and is extremely useful industrially. .

It is sectional drawing of the preform created by this invention. It is sectional drawing of the blow molded object created by this invention.

Hereinafter, the preparation method and molding processing method of the resin used in the present invention will be sequentially described.
<Polyethylene naphthalate>
In the polyethylene naphthalate of the present invention, the dicarboxylic acid component (A-1 component) is naphthalenedicarboxylic acid or an ester derivative thereof (A-1-1 component) 80 to 100 mol%, and terephthalic acid, isophthalic acid, and ester derivatives thereof. It is polyethylene naphthalate which consists of 1 type (A-1-2 component) chosen from the group which consists of 0-20 mol%, and a diol component (A-2 component) consists of ethylene glycol.

  The copolymerization ratio of the A-1-1 component and the A-1-2 component is preferably 85 to 100 mol% for the A-1-1 component, 0 to 15 mol% for the A-1-2 component, and more preferably The A-1-1 component is 90 to 98 mol%, and the A-1-2 component is 2 to 10 mol%. If the A-1-2 component exceeds 20 mol%, the crystallinity is lowered, the container body becomes thin during blow molding, and the gas barrier property is rapidly deteriorated, so that the gas barrier property as a container cannot be maintained. In addition, the thickness of the shoulder portion and the bottom portion is conversely increased by reducing the thickness of the trunk portion. In addition, the polyethylene naphthalate of this invention can contain another dicarboxylic acid component and a diol component in the range of 10 mol% or less in the range which is not contrary to the meaning of this invention.

  The intrinsic viscosity (IV) of polyethylene naphthalate is preferably 0.5 to 1.0 dl / g, more preferably 0.55 to 0.90 dl / g, still more preferably 0.6 to 0.85 dl / g. g. If the intrinsic viscosity is greater than 1.0 dl / g, the appearance of the gate portion (bottom of the container) may be whitened due to an increase in resin pressure applied during injection molding. An intrinsic viscosity of less than 0.5 dl / g is not preferable because the crystallinity of polyethylene naphthalate is high and crystallizes when the preform is molded, and the blow molded product may become cloudy. The intrinsic viscosity is 0.6 g of the resin heated and melted in 50 ml of a phenol / tetrachloroethane = 3/2 (weight ratio) mixed solvent, cooled to room temperature, and the viscosity of the obtained resin solution is the Ostwald viscosity. It measured on the temperature conditions of 35 degreeC using the pipe | tube, and calculated | required from the data of the obtained solution viscosity.

  Polyethylene naphthalate can be produced by a conventionally known production method. That is, the dicarboxylic acid and diol are directly reacted to distill off water and esterify, and then the direct esterification method in which polycondensation is performed under reduced pressure, or the dicarboxylic acid dimethyl ester and diol are reacted to distill off methyl alcohol and esterify. After the exchange, it is produced by a transesterification method in which polycondensation is performed under reduced pressure. Further, solid state polymerization can be performed to increase the intrinsic viscosity number.

In the transesterification reaction, esterification reaction and polycondensation reaction, it is preferable to use a catalyst and a stabilizer. As the transesterification catalyst, magnesium compounds, manganese compounds, calcium compounds, zinc compounds and the like are used, and examples thereof include acetates, monocarboxylates, alcoholates, and oxides thereof. Further, the esterification reaction can be carried out only with dicarboxylic acid and diol without adding a catalyst, but can also be carried out in the presence of a polycondensation catalyst. As the polycondensation catalyst, germanium compounds, titanium compounds, antimony compounds, and the like can be used. Examples thereof include germanium dioxide, germanium hydroxide, germanium alcoholate, titanium tetrabutoxide, titanium tetraisopropoxide, and titanium oxalate. . As the stabilizer, a phosphorus compound is preferably used. Preferable phosphorus compounds include phosphoric acid and its ester, phosphorous acid and its ester, hypophosphorous acid and its ester, and the like. In addition, in the esterification reaction, a tertiary amine such as triethylamine, a quaternary ammonium hydroxide such as tetraethylammonium hydroxide, and a basic compound such as sodium carbonate can be added to suppress diethylene glycol by-product.
In addition, the polyethylene naphthalate of this invention can contain each additive, such as a heating adjuvant, antioxidant, a mold release agent, and other resin in the range which is not contrary to the meaning of this invention.

<Heating aid>
The polyethylene naphthalate of the present invention can contain a heating aid for the purpose of improving the heating efficiency by an infrared (IR) heater during blow molding and shortening the heating time. Such heating aids include phthalocyanine-based near-infrared absorbers, metal oxide-based near-infrared absorbers such as ATO, ITO, iridium oxide, ruthenium oxide and imonium oxide, metals such as lanthanum boride, cerium boride and tungsten boride. Preferable examples include various metal compounds having excellent near-infrared absorption ability, such as boride-based and tungsten oxide-based near-infrared absorbers, and carbon fillers. As such a phthalocyanine-based near infrared absorber, for example, MIR-362 manufactured by Mitsui Chemicals, Inc. is commercially available and easily available. Examples of the carbon filler include carbon black, graphite (including both natural and artificial) and fullerene, and carbon black and graphite are preferable. These can be used alone or in combination of two or more. The content of the phthalocyanine-based near infrared absorber is preferably 0.0005 to 0.2 parts by weight, more preferably 0.0008 to 0.1 parts by weight, and more preferably 0.001 to 0 parts by weight based on 100 parts by weight of polyethylene naphthalate. 0.07 part by weight is more preferable. If the content is less than 0.0005 parts by weight, the effect as a heating aid may not be sufficiently obtained, and it may take a long time to heat the preform during blow molding. Moreover, when this content is more than 0.2 parts by weight, the heating aid may bleed out during blow molding overheating. The content of the metal oxide near-infrared absorber, metal boride-based near infrared absorber, tungsten oxide-based infrared absorber and carbon filler is preferably in the range of 0.1 to 500 ppm (weight ratio) in the resin. The range of 5 to 300 ppm is more preferable. If the content is less than 0.1 ppm, the effect as a heating aid may not be sufficiently obtained, and it may take a long time to heat the preform during blow molding. In addition, when the content is more than 500 ppm, the resin component may be greatly decomposed.

<Antioxidant>
The polyethylene naphthalate of the present invention can contain at least one antioxidant selected from the group consisting of hindered phenol compounds, phosphite compounds, phosphonite compounds, and thioether compounds as an antioxidant. By blending an antioxidant, not only is the hue and fluidity at the time of molding stabilized, it is also effective in improving hydrolysis resistance.

  Examples of the hindered phenol compound include α-tocopherol, butylhydroxytoluene, sinapyl alcohol, vitamin E, n-octadecyl-β- (4′-hydroxy-3 ′, 5′-di-tert-butylfel) propionate. 2-tert-butyl-6- (3′-tert-butyl-5′-methyl-2′-hydroxybenzyl) -4-methylphenyl acrylate, 2,6-di-tert-butyl-4- (N, N-dimethylaminomethyl) phenol, 3,5-di-tert-butyl-4-hydroxybenzylphosphonate diethyl ester, 2,2′-methylenebis (4-methyl-6-tert-butylphenol), 2,2′-methylenebis (4-ethyl-6-tert-butylphenol), 4,4′-methylenebi (2,6-di-tert-butylphenol), 2,2′-methylenebis (4-methyl-6-cyclohexylphenol), 2,2′-dimethylene-bis (6-α-methyl-benzyl-p-cresol) ) 2,2′-ethylidene-bis (4,6-di-tert-butylphenol), 2,2′-butylidene-bis (4-methyl-6-tert-butylphenol), 4,4′-butylidenebis (3- Methyl-6-tert-butylphenol), triethylene glycol-N-bis-3- (3-tert-butyl-4-hydroxy-5-methylphenyl) propionate, 1,6-hexanediol bis [3- (3 , 5-di-tert-butyl-4-hydroxyphenyl) propionate], bis [2-tert-butyl-4-methyl 6- ( -Tert-butyl-5-methyl-2-hydroxybenzyl) phenyl] terephthalate, 3,9-bis {2- [3- (3-tert-butyl-4-hydroxy-5-methylphenyl) propionyloxy] -1 , 1, -dimethylethyl} -2,4,8,10-tetraoxaspiro [5,5] undecane, 4,4′-thiobis (6-tert-butyl-m-cresol), 4,4′-thiobis (3-methyl-6-tert-butylphenol), 2,2′-thiobis (4-methyl-6-tert-butylphenol), bis (3,5-di-tert-butyl-4-hydroxybenzyl) sulfide, 4 , 4′-di-thiobis (2,6-di-tert-butylphenol), 4,4′-tri-thiobis (2,6-di-tert-butylphenol) ), 2,2-thiodiethylenebis- [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], 2,4-bis (n-octylthio) -6- (4-hydroxy -3 ′, 5′-di-tert-butylanilino) -1,3,5-triazine, N, N′-hexamethylenebis- (3,5-di-tert-butyl-4-hydroxyhydrocinnamide), N, N′-bis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionyl] hydrazine, 1,1,3-tris (2-methyl-4-hydroxy-5-tert-butyl Phenyl) butane, 1,3,5-trimethyl-2,4,6-tris (3,5-di-tert-butyl-4-hydroxybenzyl) benzene, tris (3,5-di-tert-butyl) 4-hydroxyphenyl) isocyanurate, tris (3,5-di-tert-butyl-4-hydroxybenzyl) isocyanurate, 1,3,5-tris (4-tert-butyl-3-hydroxy-2,6- Dimethylbenzyl) isocyanurate, 1,3,5-tris 2 [3 (3,5-di-tert-butyl-4-hydroxyphenyl) propionyloxy] ethyl isocyanurate, and tetrakis [methylene-3- (3 ′, 5′-di-tert-butyl-4-hydroxyphenyl) propionate] methane and the like. Among the above compounds, tetrakis [methylene-3- (3-tert-butyl-4-hydroxy-5-methylphenyl) propionate] methane, octadecyl-3- (3,5-di-tert-butyl-4-hydroxyphenyl) ) Propionate and 3,9-bis [2- {3- (3-tert-butyl-4-hydroxy-5-methylphenyl) propionyloxy} -1,1-dimethylethyl] -2,4,8,10 -Tetraoxaspiro [5,5] undecane is preferably used. Particularly preferred is octadecyl-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate. All of these are readily available. The said hindered phenol type compound can be used individually or in combination of 2 or more types.

  Phosphite compounds include triphenyl phosphite, tris (nonylphenyl) phosphite, tridecyl phosphite, trioctyl phosphite, trioctadecyl phosphite, didecyl monophenyl phosphite, dioctyl monophenyl phosphite, diisopropyl mono Phenyl phosphite, monobutyl diphenyl phosphite, monodecyl diphenyl phosphite, monooctyl diphenyl phosphite, tris (diethylphenyl) phosphite, tris (di-iso-propylphenyl) phosphite, tris (di-n-butylphenyl) ) Phosphite, tris (2,4-di-tert-butylphenyl) phosphite, tris (2,6-di-tert-butylphenyl) phosphite, distearyl pentae Thritol diphosphite, bis (2,4-di-tert-butylphenyl) pentaerythritol diphosphite, bis (2,6-di-tert-butyl-4-methylphenyl) pentaerythritol diphosphite, bis ( 2,6-di-tert-butyl-4-ethylphenyl) pentaerythritol diphosphite, bis {2,4-bis (1-methyl-1-phenylethyl) phenyl} pentaerythritol diphosphite, phenylbisphenol A penta Examples include erythritol diphosphite, bis (nonylphenyl) pentaerythritol diphosphite, and dicyclohexylpentaerythritol diphosphite. Furthermore, as other phosphite compounds, those that react with dihydric phenols and have a cyclic structure can be used. For example, 2,2′-methylenebis (4,6-di-tert-butylphenyl) (2,4-di-tert-butylphenyl) phosphite, 2,2′-methylenebis (4,6-di-tert- Butylphenyl) (2-tert-butyl-4-methylphenyl) phosphite, 2,2-methylenebis (4,6-di-tert-butylphenyl) octyl phosphite, and the like. Suitable phosphite compounds are distearyl pentaerythritol diphosphite, bis (2,4-di-tert-butylphenyl) pentaerythritol diphosphite, bis (2,6-di-tert-butyl-4-methyl). Phenyl) pentaerythritol diphosphite, and bis {2,4-bis (1-methyl-1-phenylethyl) phenyl} pentaerythritol diphosphite.

  Also, for example, 2,4,8,10-tetra-t-butyl-6- [3- (3-methyl-4-hydroxy-5-t-butylphenyl) propoxy] dibenzo [d, f] [1,3 , 2] dioxaphosphine [commercially available as “Sumilyzer GP” (manufactured by Sumitomo Chemical Co., Ltd.). 2,10-dimethyl-4,8-di-t-butyl-6- [3- (3,5-di-t-butyl-4-hydroxyphenyl) propoxy] -12H-dibenzo [d, g] [1,3,2] dioxaphosphocin, 2,4,8,10-tetra-t-butyl-6- [3- (3,5-di-t-butyl-4-hydroxyphenyl) propoxy] dibenzo [D, f] [1,3,2] dioxaphosphine, 2,4,8,10-tetra-t-pentyl-6- [3- (3,5-di-t-butyl-4- Hydroxyphenyl) propoxy] -12-methyl-12H-dibenzo [d, g] [1,3,2] dioxaphosphocin, 2,10-dimethyl-4,8-di-t-butyl-6- [3 -(3,5-di-tert-butyl-4-hydroxyphenyl) propionyloxy] -12H Dibenzo [d, g] [1,3,2] dioxaphosphocine, 2,4,8,10-tetra-t-pentyl-6- [3- (3,5-di-t-butyl-4- Hydroxyphenyl) propionyloxy] -12-methyl-12H-dibenzo [d, g] [1,3,2] dioxaphosphocin, 2,4,8,10-tetra-t-butyl-6- [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyloxy] -dibenzo [d, f] [1,3,2] dioxaphosphine, 2,10-dimethyl-4,8-di -T-butyl-6- (3,5-di-t-butyl-4-hydroxybenzoyloxy) -12H-dibenzo [d, g] [1,3,2] dioxaphosphocin, 2,4,8 , 10-Tetra-t-butyl-6- (3,5-di-t-butyl-4- Roxybenzoyloxy) -12-methyl-12H-dibenzo [d, g] [1,3,2] dioxaphosphocin, 2,10-dimethyl-4,8-di-t-butyl-6- [3- (3-Methyl-4-hydroxy-5-t-butylphenyl) propoxy] -12H-dibenzo [d, g] [1,3,2] dioxaphosphocine, 2,4,8,10-tetra-t -Butyl-6- [3- (3,5-di-t-butyl-4-hydroxyphenyl) propoxy] -12H-dibenzo [d, g] [1,3,2] dioxaphosphocine, 2,10 -Diethyl-4,8-di-t-butyl-6- [3- (3,5-di-t-butyl-4-hydroxyphenyl) propoxy] -12H-dibenzo [d, g] [1,3 2] Dioxaphosphocin, 2,4,8,10-tetra-t-butyl Ru-6- [2,2-dimethyl-3- (3-t-butyl-4-hydroxy-5-methylphenyl) propoxy] -dibenzo [d, f] [1,3,2] dioxaphosphine And so on. All of these are readily available. The above phosphite compounds can be used alone or in combination of two or more.

  Examples of the phosphonite compound include tetrakis (2,4-di-tert-butylphenyl) -4,4′-biphenylenediphosphonite, tetrakis (2,4-di-tert-butylphenyl) -4,3′-biphenyl. Range phosphonite, tetrakis (2,4-di-tert-butylphenyl) -3,3'-biphenylene diphosphonite, tetrakis (2,6-di-tert-butylphenyl) -4,4'-biphenylene diphospho Knight, tetrakis (2,6-di-tert-butylphenyl) -4,3′-biphenylene diphosphonite, tetrakis (2,6-di-tert-butylphenyl) -3,3′-biphenylene diphosphonite, Bis (2,4-di-tert-butylphenyl) -4-phenyl-phenylphosphonite, bis (2,4- -Tert-butylphenyl) -3-phenyl-phenylphosphonite, bis (2,6-di-n-butylphenyl) -3-phenyl-phenylphosphonite, bis (2,6-di-tert-butylphenyl) Examples include -4-phenyl-phenyl phosphonite, bis (2,6-di-tert-butylphenyl) -3-phenyl-phenyl phosphonite. Tetrakis (di-tert-butylphenyl) -biphenylenediphosphonite, bis (di-tert-butylphenyl) -phenyl-phenylphosphonite are preferred, and tetrakis (2,4-di-tert-butylphenyl) -biphenylenediphosphonite Knight and bis (2,4-di-tert-butylphenyl) -phenyl-phenylphosphonite are more preferred. Such a phosphonite compound is preferable because it can be used in combination with a phosphite compound having an aryl group in which two or more alkyl groups are substituted. The phosphonite compound is preferably tetrakis (2,4-di-tert-butylphenyl) -biphenylenediphosphonite, and stabilizers based on the phosphonite are Sandostab P-EPQ (trademark, manufactured by Clariant) and Irgafos. P-EPQ (trademark, manufactured by CIBA SPECIALTY CHEMICALS) is commercially available and any of them can be used. The said phosphonite type compound can be used individually or in combination of 2 or more types.

  Specific examples of thioether compounds include dilauryl thiodipropionate, ditridecyl thiodipropionate, dimyristyl thiodipropionate, distearyl thiodipropionate, pentaerythritol-tetrakis (3-lauryl thiopropionate), Pentaerythritol-tetrakis (3-dodecylthiopropionate), pentaerythritol-tetrakis (3-octadecylthiopropionate), pentaerythritol tetrakis (3-myristylthiopropionate), pentaerythritol-tetrakis (3-stearylthio) Propionate) and the like. The said thioether type compound can be used individually or in combination of 2 or more types.

  The content of the antioxidant is preferably 0.01 to 2 parts by weight, more preferably 0.03 to 1 part by weight, and still more preferably 0.05 to 0.5 parts by weight with respect to 100 parts by weight of polyethylene naphthalate. It is. When the content of the antioxidant is less than 0.01 parts by weight, the antioxidant effect is insufficient, and not only the hue and fluidity at the time of molding become unstable, but also the hydrolysis resistance may deteriorate. . In addition, when the content is more than 2 parts by weight, the reaction component derived from the antioxidant may be deteriorated and the hydrolysis resistance may be deteriorated.

  Further, it is preferable to use a combination of one or more of the hindered phenol compounds and phosphite compounds, phosphonite compounds, and thioether compounds. By using a combination of one or more of hindered phenol compounds and phosphite compounds, phosphonite compounds, and thioether compounds, a synergistic effect as a stabilizer is exhibited, and hue and flow during molding are further improved. It is effective in stabilizing the properties and improving the hydrolysis resistance.

<Release agent>
The polyethylene naphthalate of the present invention can contain a release agent. Specific examples of release agents include fatty acids, fatty acid metal salts, oxy fatty acids, paraffins, low molecular weight polyolefins, fatty acid amides, alkylene bis fatty acid amides, aliphatic ketones, fatty acid partial saponified esters, fatty acid lower alcohol esters, fatty acid polyvalents. Examples thereof include alcohol esters, fatty acid polyglycol esters, and modified silicones. By blending these, a molded product excellent in mechanical properties, moldability, and heat resistance can be obtained.

Fatty acids having 6 to 40 carbon atoms are preferred. Specifically, oleic acid, stearic acid, lauric acid, hydroxystearic acid, behenic acid, arachidonic acid, linoleic acid, linolenic acid, ricinoleic acid, palmitic acid, montan Examples thereof include acids and mixtures thereof. The fatty acid metal salt is preferably an alkali (earth) metal salt of a fatty acid having 6 to 40 carbon atoms, and specific examples include calcium stearate, sodium montanate, and calcium montanate.
Examples of the oxy fatty acid include 1,2-oxysteric acid. Paraffin having 18 or more carbon atoms is preferable, and examples thereof include liquid paraffin, natural paraffin, microcrystalline wax, petrolactam and the like.
As the low molecular weight polyolefin, for example, those having a molecular weight of 5000 or less are preferable, and specific examples include polyethylene wax, maleic acid-modified polyethylene wax, oxidized type polyethylene wax, chlorinated polyethylene wax, and polypropylene wax.

Fatty acid amides having 6 or more carbon atoms are preferred, and specific examples include oleic acid amide, erucic acid amide, and behenic acid amide.
The alkylene bis fatty acid amide is preferably one having 6 or more carbon atoms, and specifically includes methylene bis stearic acid amide, ethylene bis stearic acid amide, N, N-bis (2-hydroxyethyl) stearic acid amide and the like.
As the aliphatic ketone, those having 6 or more carbon atoms are preferable, and examples thereof include higher aliphatic ketones.
Examples of the fatty acid partial saponified ester include a montanic acid partial saponified ester. Examples of the fatty acid lower alcohol ester include stearic acid ester, oleic acid ester, linoleic acid ester, linolenic acid ester, adipic acid ester, behenic acid ester, arachidonic acid ester, montanic acid ester, isostearic acid ester and the like.

Examples of fatty acid polyhydric alcohol esters include glycerol tristearate, glycerol distearate, glycerol monostearate, pentaerythritol tetrastearate, pentaerythritol tristearate, pentaerythritol dimyristate, pentaerythritol Examples include tall monostearate, pentaerythritol adipate stearate, sorbitan monobehenate and the like. Examples of fatty acid polyglycol esters include polyethylene glycol fatty acid esters, polytrimethylene glycol fatty acid esters, and polypropylene glycol fatty acid esters.
Examples of the modified silicone include polyether-modified silicone, higher fatty acid alkoxy-modified silicone, higher fatty acid-containing silicone, higher fatty acid ester-modified silicone, methacryl-modified silicone, and fluorine-modified silicone.

Of these, fatty acid, fatty acid metal salt, oxy fatty acid, fatty acid ester, fatty acid partial saponified ester, paraffin, low molecular weight polyolefin, fatty acid amide, and alkylene bis fatty acid amide are preferable, and fatty acid partial saponified ester and alkylene bis fatty acid amide are more preferable. Of these, montanic acid ester, montanic acid partial saponified ester, polyethylene wax, acid value polyethylene wax, sorbitan fatty acid ester, erucic acid amide, and ethylene bisstearic acid amide are preferable, and montanic acid partial saponified ester and ethylene bisstearic acid amide are particularly preferable. .
A mold release agent may be used by 1 type and may be used in combination of 2 or more type. The content of the release agent is preferably 0.01 to 3 parts by weight, more preferably 0.03 to 2 parts by weight, with respect to 100 parts by weight of polyethylene naphthalate.

<Other resins>
The resin of the present invention is a polyester other than a phenolic resin, a melamine resin, a thermosetting polyester resin, a silicone resin, an epoxy resin, a polycarbonate resin, or polyethylene naphthalate, as long as it does not contradict the spirit of the present invention. Resin, polyarylate resin, liquid crystalline polyester resin, polyamide resin, polyimide resin, polyetherimide resin, polyphenylene ether resin, polyphenylene sulfide resin, polysulfone resin, polystyrene resin, acrylonitrile / styrene copolymer (AS resin), polystyrene resin, A thermoplastic resin such as high impact polystyrene resin or syndiotactic polystyrene resin may be included.

<Preform molding>
The polyethylene naphthalate of the present invention is usually obtained as a pellet, and a preform is formed from this as a raw material. Various molding methods such as injection molding, press molding, and extrusion molding can be selected as the molding method, but injection molding and press molding are preferred from the viewpoint of rapid cooling without crystallizing the preform. In the injection molding, not only a normal cold runner molding method but also a hot runner molding method is possible. In such injection molding, not only a normal molding method but also injection compression molding, injection press molding, foam molding (including by supercritical fluid injection), insert molding, in-mold coating molding, as appropriate, depending on the purpose. A molded product can be obtained using an injection molding method such as rapid heating / cooling die molding.

  In the present invention, a preform having a multilayer structure can be adopted. When taking a multi-layer structure, a multi-layer structure of polyethylene naphthalates may be used, and a multi-layer structure with other resins may be used without departing from the spirit of the present invention. Other resins include phenol resins, melamine resins, thermosetting polyester resins, silicone resins, epoxy resins and other thermosetting resins, polycarbonate resins, polyester resins other than polyethylene naphthalate, polyarylate resins, liquid crystalline polyester resins, Polyamide resin, polyimide resin, polyetherimide resin, polyphenylene ether resin, polyphenylene sulfide resin, polysulfone resin, polystyrene resin, acrylonitrile / styrene copolymer (AS resin), polystyrene resin, high impact polystyrene resin, syndiotactic polystyrene resin, etc. These thermoplastic resins can be mentioned. In the production of a preform having a multilayer structure, the preform can be produced in one stage by co-injection molding, or can be produced by sequential molding in two or more stages in which one layer is injection molded.

  When producing the preform of the present invention, for example, in the case of injection molding, polyethylene naphthalate is pre-dried in a hot air dryer at 130 to 170 ° C. for 5 hours or more, then melted at a cylinder temperature of 260 to 300 ° C. and injected. It is preferable to mold. If the predrying temperature is less than 130 ° C, the drying becomes insufficient, the resin may be decomposed by moisture remaining in the pellets, and the intrinsic viscosity may not be stable. If the predrying temperature is higher than 170 ° C, the pellets turn yellow. The appearance of the molded body may be impaired. The mold temperature for molding the preform is preferably 5 to 40 ° C, more preferably 10 to 30 ° C. When the mold temperature is less than 5 ° C, the appearance of silver or the like may frequently occur in the molded product due to the condensation of the mold. When the mold temperature exceeds 40 ° C, the crystallization of the preform proceeds and blow molding is performed. Container may be damaged.

<Blow molding>
Arbitrary methods are employ | adopted as the preparation methods of the hydrogen gas tank of this invention. Examples thereof include direct blow molding, extrusion direct blow molding, one-stage biaxial stretch blow molding, and two-stage biaxial stretch blow molding. Two-stage biaxial stretch blow molding is preferable.
The hydrogen gas tank of the present invention preferably has a draw ratio of 10 to 20 times or more, more preferably 12 to 18 times in terms of the thickness of the body. If the draw ratio is less than 10 times, the tank body may be thin and not as designed. When the draw ratio exceeds 20 times, a fine crack may be partially generated, which is not preferable.

  When biaxial stretching blow is performed in two stages, it is preferable to preheat (preheat) before blow molding. The preheating temperature is preferably 70 to 140 ° C, preferably 90 ° C to 130 ° C, and most preferably 100 ° C to 110 ° C. If the preheating temperature is less than 70 ° C., it takes time for the main heating time in the subsequent process. If the preheating temperature exceeds 140 ° C., polyethylene naphthalate may crystallize, and the container may be damaged during blow molding. . The preheating method may be any method such as storage of a preform in a hot air dryer or heating with an infrared heater.

  Heating during blow molding (main heating) is preferably performed from both heating from the inside of the preform (internal heating) and heating from the outside of the preform (external heating). As the heating method, an infrared heating method is preferable since heating efficiency is good. In particular, when the thickness of the preform is thick, the temperature difference between the outer side and the inner side of the preform becomes large, and the outer side may crystallize, resulting in a defect in which numerous cracks are generated inside.

Hereinafter, the present invention is described in detail by way of examples. However, the present invention is not limited to these.
1. Production method of polyethylene naphthalate Polyethylene naphthalate was produced by the method shown in the production examples below. Moreover, the value of the intrinsic viscosity in a manufacture example was calculated | required by the following method.
(1) Intrinsic Viscosity (IV) Measurement Method 0.6 g of resin was melted by heating in 50 ml of a mixed solvent of phenol / tetrachloroethane = 3/2 (weight ratio), then cooled to room temperature, and the viscosity of the resulting resin solution Was measured using an Ostwald viscosity tube at a temperature of 35 ° C., and the intrinsic viscosity (IV) of the resin was determined from the obtained solution viscosity data.

(2) Production of resin [Production Examples 1-3, 5, 6: Polyethylene naphthalate PEN-2-4, 6, 7]
2,6-naphthalenedicarboxylic acid dimethyl ester, terephthalic acid dimethyl ester, ethylene glycol, and 30 mmol% of the total moles of dicarboxylic acid ester as a transesterification catalyst prepared in quantities so as to have the polymer composition shown in Table 1. 70 mmol% manganese acetate tetrahydrate with respect to the total number of moles of cobalt acetate tetrahydrate and dicarboxylic acid ester was supplied to the reactor, and transesterification was performed at 240 ° C. in a nitrogen atmosphere. Subsequently, after adding antimony trioxide at 80 mmol% with respect to the total number of dicarboxylic acid esters, orthophosphoric acid was added with 60 mmol% with respect to the total number of dicarboxylic acid esters and kept at 260 ° C. for 30 minutes. did. Thereafter, the temperature was increased and the pressure was gradually reduced, and polymerization was finally performed at 300 ° C. and 0.1 kPa or less. The degree of progress of the polycondensation reaction was confirmed as a load on the stirring blade, and the reaction was terminated when the desired degree of polymerization was reached. Thereafter, the reaction product in the system was continuously extruded in a strand form from the discharge part, cooled and cut to obtain about 3 mm granular pellets. The obtained composition and physical properties are shown in Table 1.

[Production Example 4: PEN-5]
The same procedure as in Production Example 1 was conducted except that dimethyl terephthalate was changed to dimethyl phthalate. The results are shown in Table 2.

<Other resins>
As other resins, the following resins were used.
PEN-1: Teonex TR-8065S manufactured by Teijin Limited [polyethylene naphthalate produced from 100 mol% naphthalene dicarboxylic acid and 100 mol% ethylene glycol, intrinsic viscosity 0.67 dl / g]
Polyamide: MX nylon S6011 [metaxylenediamine-adipic acid polycondensate] manufactured by Mitsubishi Gas Chemical Company, Inc.

<Other additives>
As other additives, the following additives were used.
Heating aid: MIR-362 [phthalocyanine-based infrared absorber] manufactured by Mitsui Chemicals, Inc.
Antioxidant: Irganox 1076 [n-octadecyl-3- (3 ′, 5′-di-tert-butyl-4′-hydroxyphenyl) propionate] manufactured by BASF Corporation
Mold release agent: Riken Vitamin Co., Ltd. rickester EW-400 [Fatty acid ester release agent]

2. Evaluation of Blow Molding and Blow Molded Body Blow molding and blow molded body were evaluated by the methods shown in the following Examples and Comparative Examples. Moreover, each value in an Example was calculated | required with the following method.
(1) Body Thickness After the body of the blow molded body was cut out to a size of 70 mm × 70 mm, the thickness was measured at 10 points at random, and the average value was calculated.
(2) Transparency (Haze)
Using the sample of 70 mm × 70 mm used in (1), Haze was measured using a reflection / transmittance meter HT-100 manufactured by Murakami Color Research Laboratory.
(3) Hydrogen gas permeation coefficient Using the 70 mm x 70 mm sample used in (1), JIS using a differential pressure gas / vapor permeability measuring device GTR-30XAD2, G2700T • F (GTR Tech Co., Ltd.) The hydrogen permeation coefficient was measured according to K7126-1. The measurement is performed at a test temperature of 23 ° C., a test differential pressure of 1 atm, a permeation area of 15.2 × 10 ⁻⁴ m ² , a detector gas chromatograph (heat conduction detector [TCD]), relative humidity of 0%, 50%, and 90%. The conditions were as follows.

Example 1
After PEN-1 was dried with a hot air dryer at 160 ° C. for 5 hours, a preform was formed. The molding machine used was EC160NII-4Y manufactured by Toshiba Machine Co., Ltd., and molding was performed at a cylinder temperature of 300 ° C., a mold temperature of 20 ° C., and a cooling time of 20 seconds to obtain a preform having a thickness of 4.2 mm. Next, biaxial stretching of the preform was performed using FDB-1D manufactured by Frontier Co., Ltd. as a blower and using a 1.5 L container-shaped blow mold (length 2.3 times × width 3.4 times). Blow molding was performed. The preform preliminarily heated in a hot air dryer at 100 ° C. for 1 hour was set in a blow molding machine, the output of the IR heater was set so that the preform surface temperature was 150 ° C., and the main heating was performed. Subsequently, rod stretching speed 60%, primary blow delay time 0.2 seconds, primary blow time 0.3 seconds, primary blow pressure 1.2 MPa, secondary blow time 1.2 seconds, secondary blow pressure 3 Molding was performed under conditions of 0.4 MPa and a mold temperature of 20 ° C., and blow molding was performed. Each evaluation mentioned above was performed using the obtained blow molded object. The results are shown in Table 2.

(Examples 2-6, Comparative Example 1)
Molding was performed in the same manner as in Example 1 except that the resin used was changed from PEN-1 to the resin described in Table 2. Each evaluation mentioned above was performed using the obtained blow molded object. The results are shown in Table 2.

(Examples 7 to 9)
After the composition shown in Table 2 was uniformly premixed by dry blending, the premixed mixture was supplied from the first supply port, melt-extruded and pelletized. Here, the first supply port is a base supply port. The melt extrusion was carried out using a vent type twin screw extruder (TEX30XSST manufactured by Nippon Steel Works) with a diameter of 30 mmφ. The extrusion temperature was C1 / C2 to C11 / D = 50 ° C./300° C./280° C., the screw rotation speed was 150 rpm, the discharge rate was 20 kg / h, and the vent pressure reduction was 3 kPa. Molding was performed in the same manner as Example 1 using the obtained pellets. Each evaluation mentioned above was performed using the obtained blow molded object. The results are shown in Table 2.

(Comparative Example 2)
After the polyamide (MX nylon) was dried with a hot air dryer at 120 ° C. for 5 hours, a preform was formed. As the molding machine, EC160NII-4Y manufactured by Toshiba Machine Co., Ltd. was used, and molding was performed at a cylinder temperature of 280 ° C., a mold temperature of 30 ° C., and a cooling time of 20 seconds to obtain a preform having a thickness of 4.2 mm. Next, the preform was blow-molded using FDB-1D manufactured by Frontier Co., Ltd. as a blower and using a 1.5 L container-shaped blow mold. The preform preliminarily heated in a hot air dryer at 60 ° C. for 1 hour was set in a blow molding machine, the output of the IR heater was set so that the preform surface temperature was 100 ° C., and the main heating was performed. Subsequently, rod stretching speed 60%, primary blow delay time 0.2 seconds, primary blow time 0.3 seconds, primary blow pressure 1.2 MPa, secondary blow time 1.2 seconds, secondary blow pressure 3 Molding was performed under conditions of 0.4 MPa and a mold temperature of 20 ° C., and blow molding was performed. Each evaluation mentioned above was performed using the obtained blow molded object. The results are shown in Table 2.

<Examples 1-9>
Examples 1 to 9 using resins within the scope of the present invention were blow-moldable, and showed stable and excellent hydrogen gas barrier properties at relative humidity of 0%, 50% and 90%.

<Comparative Example 1>
When PEN-7 copolymerized with 22 mol% of the A-1-2 component was used, the thickness of the trunk portion was reduced and the hydrogen gas barrier property was deteriorated.

<Comparative example 2>
When polyamide was used as the resin, an excellent hydrogen gas barrier property was exhibited when the humidity was low, but the hydrogen gas barrier property was significantly lowered at a high humidity of 90% relative humidity.

A-1: preform mouth A-2: preform neck A-3: preform shoulder A-4: preform trunk A-5: preform bottom B-1: blow molded article Mouth B-2: Blow molded body neck B-3: Blow molded body shoulder B-4: Blow molded body B-5: Blow molded body bottom

Claims (3)

  (A) The dicarboxylic acid component (A-1 component) is selected from the group consisting of naphthalenedicarboxylic acid or its ester derivative (A-1-1 component) 80 to 100 mol% and terephthalic acid, isophthalic acid and their ester derivatives. A hydrogen gas tank liner resin comprising at least one kind (component A-1-2) of 0 to 20 mol%, and a diol component (component A-2) comprising polyethylene naphthalate (component A) comprising ethylene glycol.   The resin for a hydrogen gas tank liner according to claim 1, wherein the intrinsic viscosity of the component A is 0.5 to 1.0 dl / g.   A resin liner for a hydrogen gas tank obtained by molding a preform using the resin according to claim 1 or 2 and then biaxially stretch-blow molding.

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