Optical member polyethylene naphthalate resin composition and uniaxially stretched film

Abstract

The present application provides a polyethylene naphthalate resin composition which can be used for optical members such as optical films. The polyethylene naphthalate resin composition for optical members of the present application contains (A) polyethylene naphthalate and (B) a phosphorus compound or a salt thereof represented by the following formula (I) or (II) (in the formula, R1 represents an alkyl group having 1 to 12 carbon atoms, an aryl group having 6 to 12 carbon atoms, or a benzyl group, R2 and R3 represent an alkyl group having 1 to 12 carbon atoms, an aryl group having 6 to 12 carbon atoms, a benzyl group, a glycol group, or a hydrogen atom, and R1 and R2 can be bonded to form a ring).

Description

Technical Field

[0001] The present invention relates to a polyethylene naphthalate resin composition for optical components that can exhibit a high refractive index in the stretching direction by stretching, and a uniaxial stretched film made of the resin composition. Background Technology

[0002] As is well known, polyethylene naphthalate resin has excellent mechanical properties such as strength, elongation, Young's modulus or elastic recovery, physical properties such as heat resistance or dimensional stability, or chemical properties such as chemical resistance or water resistance, and is inexpensive. Therefore, it has high industrial value and is widely used in fibers, resin molded products and films.

[0003] However, polyethylene naphthalate resin has rigid molecular chains, resulting in lower crystallinity and moldability (especially blow molding properties such as PET bottles) compared to polyethylene terephthalate resin (PET), making it difficult to mold into large bottles like the Type 20 fire extinguisher. To improve this crystallinity, the addition of specific phosphorus compounds has been proposed (see, for example, Patent Documents 1 and 2).

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: International Publication No. 2015 / 125846 (Japanese Patent No. 6181847)

[0007] Patent Document 2: Japanese Patent Application Publication No. 2008-247932 (Japanese Patent No. 5217052) Summary of the Invention

[0008] In Patent Documents 1 and 2, the blow molding properties of the polyethylene naphthalate resin composition with the aforementioned phosphorus compound added were improved, and the resulting molded articles exhibited excellent weather resistance and other physical properties. However, Patent Documents 1 and 2 did not investigate the optical properties such as the refractive index of such resin compositions; therefore, it is unclear whether such resin compositions can be applied to optical components.

[0009] According to research by the present invention, it is known that a polyethylene naphthalate resin composition with added specific phosphorus compounds exhibits a high refractive index in the stretching direction when the film of the resin composition is stretched, and therefore can be used in optical components such as optical films. The object of the present invention is to provide a polyethylene naphthalate resin composition that can be used in optical components such as optical films.

[0010] The inventors have discovered that the above-mentioned problems can be solved by the present invention having the following solutions.

[0011] Option 1

[0012] A polyethylene naphthalate resin composition for optical components, comprising:

[0013] (A) Polyethylene naphthalate, and

[0014] (B) A phosphorus compound or a salt thereof represented by formula (I) or (II),

[0015]

[0016] (In the formula, R1 represents an alkyl group with 1 to 12 carbon atoms, an aryl group with 6 to 12 carbon atoms, or a benzyl group; R2 and R3 represent an alkyl group with 1 to 12 carbon atoms, an aryl group with 6 to 12 carbon atoms, a benzyl group, an ethylene glycol group, or a hydrogen atom; R1 and R2 can be bonded to form a ring).

[0017] Option 2

[0018] The resin composition as described in Scheme 1, wherein the amount of the phosphorus compound or its salt added is 0.1 to 10,000 ppm.

[0019] Option 3

[0020] The resin composition as described in Scheme 1, wherein the phosphorus compound or its salt is phenylphosphonic acid or its salt, or 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide or its salt.

[0021] Option 4

[0022] The resin composition as described in Scheme 1, wherein the salt is at least one selected from manganese salts, cobalt salts, and zinc salts, and / or

[0023] The above resin composition contains at least one selected from manganese ions, cobalt ions, and zinc ions.

[0024] Option 5

[0025] The resin composition as described in Scheme 1, wherein the refractive index in the stretching direction of the sheet after the sheet of the above-described resin composition is stretched at the maximum uniaxial stretching ratio is higher than the refractive index of the sheet after the sheet of the resin composition without the above-described phosphorus compound or its salt is stretched at the maximum uniaxial stretching ratio under the same conditions.

[0026] Option 6

[0027] A uniaxially stretched film is composed of the resin composition described in Scheme 1.

[0028] Plan 7

[0029] The uniaxially stretched membrane as described in Scheme 5, wherein the refractive index in the stretching direction is 1.80 to 1.95.

[0030] Option 8

[0031] The uniaxially stretched film as described in Scheme 5 has an orientation degree of 94.5% or higher and a crystal size of 6 nm or less.

[0032] The polyethylene naphthalate resin composition of the present invention exhibits a high refractive index in the stretching direction upon stretching, which is useful in optical applications such as optical films. Furthermore, since the birefringence is also increased, it can be appropriately used in applications such as reflective polarizers and polarizing films. Detailed Implementation

[0033] The polyethylene naphthalate resin composition of the present invention (hereinafter sometimes referred to as PEN composition) is a composition containing (A) polyethylene naphthalate and (B) a phosphorus compound or a salt thereof having a specific chemical structure.

[0034] (A) Polyethylene naphthalate

[0035] The polyethylene naphthalate in the PEN composition of the present invention is as follows:

[0036]

[0037] The diagram shows a polymer using 2,6-naphthalenedicarboxylic acid as the dicarboxylic acid component and ethylene glycol as the diol component. However, other dicarboxylic acids and other diol components can be copolymerized without impairing the effects of the present invention. Furthermore, the PEN composition of the present invention may contain a small amount of polyester composed of other dicarboxylic acids and other diol components. The amount that can be copolymerized is 10 mol% or less for each dicarboxylic acid component and diol component independently relative to the naphthalenedicarboxylic acid component. Additionally, the amount of polyester composed of the aforementioned dicarboxylic acids and other diol components may be 20 wt% or less relative to the weight of the PEN composition of the present invention.

[0038] Other dicarboxylic acid components include aromatic dicarboxylic acids, aliphatic dicarboxylic acids, alicyclic dicarboxylic acids, or their ester-forming derivatives. As aromatic dicarboxylic acids, examples include phthalic acid, isophthalic acid, terephthalic acid, 2,7-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 1,6-naphthalenedicarboxylic acid, 2,5-naphthalenedicarboxylic acid, 4,4'-diphenyldicarboxylic acid, 4,4'-diphenoxyethanedicarboxylic acid, 4,4'-diphenylsulfonedicarboxylic acid, 4,4'-diphenylmethanedicarboxylic acid, 4,4'-diphenylethanedicarboxylic acid, 4,4'-diphenylpropanedicarboxylic acid, 4,4'-diphenylketonedicarboxylic acid, diphenyl ether-4,4'-dicarboxylic acid, diphenyl sulfide-4,4'-dicarboxylic acid, tetrahydronaphthalenedicarboxylic acid, and 6,6'-(alkylenedioxy)di-2-naphthoic acid. Alternatively, for diphenyldicarboxylic acid, the substituent is not limited to the 4,4'- position, but can also be an aromatic dicarboxylic acid located at the 2,4'-, 3,4'-, 2,5'-, 2,2'-, 3,3'-, etc.

[0039] Furthermore, ester-forming derivatives of aromatic dicarboxylic acids refer to lower dialkyl esters with 1 to 6 carbon atoms, lower diaryl esters with 6 to 10 carbon atoms, and diacyl halides. More specifically, examples include dimethyl esters, diethyl esters, di-n-propyl esters, diisopropyl esters, di-n-butyl esters, di-sec-butyl esters, di-tert-butyl esters, dipentyl esters, dihexyl esters, diheptyl esters, dioctyl esters, dinonyl esters, didecyl esters, diphenyl esters, dibenzyl esters, dinaphthalene esters, or aromatic dicarboxylic acid difluorides, aromatic dicarboxylic acid dichlorides, aromatic dicarboxylic acid dibromates, and aromatic dicarboxylic acid diiodides. The dialkyl esters with 1 to 6 carbon atoms or the diaryl esters with 6 to 10 carbon atoms can also be esters obtained by substituting one or more of their hydrogen atoms with halogen atoms, alkyl ether groups, aryl ether groups, alkyl ester groups, aryl ester groups, alkyl carbonyl groups such as acetyl groups, or aryl carbonyl groups such as benzoyl groups.

[0040] Other aliphatic and alicyclic dicarboxylic acid components include, specifically, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, octanoic acid, azelaic acid, sebacic acid, undecanoic acid, dodecanoic acid, tridecanoic acid, tetradecanoic acid, pentadecanoic acid, hexadecanoic acid, heptadecanoic acid, octadecanoic acid, nonadecanoic acid, eicosanoic acid, docosanoic acid, fumaric acid, maleic acid, itaconic acid, etc. Dicarboxylic acids; 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid or 1,4-cyclohexanedicarboxylic acid, perhydronaphthalenedicarboxylic acid (decahydronaphthalenedicarboxylic acid), dimer acids (products obtained by the Diels-Alder reaction of 9,11-conjugated linoleic acid with non-conjugated linoleic acid, etc.), cyclobutanedicarboxylic acid, tetramethylcyclobutanedicarboxylic acid, tricyclodecanedicarboxylic acid, norbornanedicarboxylic acid, adamantanedicarboxylic acid and other alicyclic dicarboxylic acids.

[0041] Other dicarboxylic acid components may also be acid anhydrides or ester-forming derivatives as described above. It is more preferable to use one or two of these dicarboxylic acid components. Preferably, the copolymerization rate of these dicarboxylic acid components relative to the 2,6-naphthalenedicarboxylic acid component is 0 to 10 mol%, more preferably 2 to 8 mol%. Furthermore, compounds having three or more carboxyl groups within their molecules, such as trimellitic acid, pyromellitic acid, pyromellitic tetracarboxylic acid, gallic acid, and tricarboxylic acid, may also be copolymerized in the range of 1 to 5 mol%.

[0042] Furthermore, other diol components besides ethylene glycol can be copolymerized into a portion of the ethylene glycol component of the polyethylene naphthalate constituting the PEN composition of the present invention. Preferably, diol components with 2 to 20 carbon atoms are included; specifically, examples include 1,2-propanediol, trimethylenediol, tetramethylenediol, pentamethylenediol, hexamethylenediol, heptamethylenediol, octamethylenediol, nonamethylenediol, decamethylenediol, undecamethylenediol, dodecamethylenediol, tridecamethylenediol, tetradecamethylenediol, pentadecylmethylenediol, hexadecylmethylenediol, neopentyl glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, etc. Dipropylene glycol, tripropylene glycol, tetrapentanediol, 2,2-diethyl-1,3-propanediol, 2-ethyl-2-butyl-1,3-propanediol, 2,2,4-trimethyl-1,3-pentanediol, 1,1-dihydroxycyclohexane, 1,2-dihydroxycyclohexane, 1,3-dihydroxycyclohexane, 1,4-dihydroxycyclohexane, 1,1-cyclohexanediethanol, 1,2-cyclohexanediethanol, 1,3-cyclohexanediethanol, 1,4-cyclohexanediethanol, 2,2, 4,4-Tetramethylcyclobutane-1,3-diol, p-bis(2-hydroxyethoxy)benzene, p-bis(3-hydroxypropoxy)benzene, 4,4'-bis(2-hydroxyethoxy)biphenyl, 4,4'-bis(3-hydroxypropoxy)biphenyl, 2,2-bis(4-β-hydroxyethoxyphenyl)propane, 2,2-bis(4-γ-hydroxypropoxyphenyl)propane, 2,2-bis(4-ω-hydroxyethoxyethoxyphenyl)propane, bis(4-β-hydroxyethoxyphenyl) Sulfone, bis(4-γ-hydroxypropoxyphenyl)sulfone, bis(4-ω-hydroxyethoxyethoxyphenyl)sulfone, 2,2-bis(4-β-hydroxyethoxycycloalkyl)propane, 2,2-bis(4-γ-hydroxypropoxycycloalkyl)propane, bis(4-β-hydroxyethoxycycloalkyl)sulfone, bis(4-γ-hydroxypropoxycycloalkyl)sulfone, 2,2,4,4-tetramethyl-1,3-cyclobutanediol, adamantanediol, spirodiol, tricyclic [5.2.1.0², 6 Decanediethanol. Other diol components besides the two mentioned above are more preferably any one or two of these compounds. Furthermore, when the aromatic dicarboxylic acid component is set to 100%, compounds such as pentaerythritol and tetra(hydroxymethyl)methane having three or more hydroxyl groups can be copolymerized at a ratio of 1 to 3 mol%.

[0043] Furthermore, in this invention, compounds other than the dicarboxylic acid components, diol components, compounds having three or more carboxyl groups in their molecules, and compounds having three or more hydroxyl groups in their molecules can be copolymerized, that is, hydroxycarboxylic acids can be copolymerized as needed. Examples of hydroxycarboxylic acids include glycolic acid, lactic acid, glyceric acid, 2-hydroxybutyric acid, 3-hydroxybutyric acid, 4-hydroxybutyric acid, 2-hydroxyisobutyric acid, 2-hydroxy-2-methylbutyric acid, 2-hydroxyvalerate, 3-hydroxyvalerate, 4-hydroxyvalerate, 5-hydroxyvalerate, 6-hydroxyhexanoic acid, 10-hydroxystearic acid, malic acid, tartaric acid, citrate, citric acid, isocitrate, leucine, mevalonic acid, pantothenic acid, ricinoleic acid, transricinoleic acid, cerebrolysic acid, quinic acid, shikimic acid, 4-(β-hydroxy)ethoxybenzoic acid, β-propiolactone, β-butyrolactone, γ-butyrolactone, δ-valerate, and ε-caprolactone. When copolymerizing hydroxycarboxylic acids, it is preferable that the content relative to 2,6-naphthalenedicarboxylic acid is in the range of 10 mol% or less. Furthermore, monocarboxylic acids and monohydric alcohols may also be copolymerized in the PEN compositions of the present invention, provided the amount is small.

[0044] The polyethylene naphthalate in the PEN composition of the present invention can preferably be obtained by the following manufacturing methods: by performing an ester-forming derivative of the dicarboxylic acid component as described above with a diol such as ethylene glycol for transesterification, followed by polycondensation; or by performing an esterification reaction of the dicarboxylic acid with a diol such as ethylene glycol, followed by polycondensation.

[0045] (B) Phosphorus compounds or their salts

[0046] In addition, the PEN composition of the present invention contains a phosphorus compound or a salt thereof represented by formula (I) or (II).

[0047]

[0048] In the above general formula (I) or (II), R1 represents an alkyl group with 1 to 12 carbon atoms, an aryl group with 6 to 12 carbon atoms, or a benzyl group, and R2 and R3 represent an alkyl group with 1 to 12 carbon atoms, an aryl group with 6 to 12 carbon atoms, a benzyl group, an ethylene glycol group, or a hydrogen atom. R1 and R2 can be bonded to form a ring.

[0049] The preferred amount of the phosphorus compound or its salt is 0.1 to 10,000 ppm. Alternatively, the amount of the phosphorus compound or its salt may be 0.1 ppm or more, 1 ppm or more, 5 ppm or more, 10 ppm or more, 50 ppm or more, or 100 ppm or more, and may be less than 10,000 ppm, less than 8,000 ppm, less than 6,000 ppm, less than 4,000 ppm, less than 3,000 ppm, or less than 2,000 ppm.

[0050] The phosphorus compound or its salt acts as a nucleating agent in the PEN composition, preferably added during the transesterification reaction. Adding this phosphorus compound or its salt not only deactivates the transesterification catalyst but also improves the crystallinity of the PEN composition and increases the refractive index of the film formed from this composition during stretching. On the other hand, if too much of the phosphorus compound is added, phosphorus compound aggregation sometimes occurs in the PEN composition of the present invention. As a result, the transparency of the PEN composition is lost, which is therefore undesirable.

[0051] The compound represented by formula (I) or (II) above is an organophosphonic acid or its phosphate ester form, and more specifically, alkylphosphonic acid, arylphosphonic acid, or benzylphosphonic acid or its phosphate ester form can be cited. Specifically, alkylphosphonic acids include methylphosphonic acid, ethylphosphonic acid, n-propylphosphonic acid, tert-butylphosphonic acid, n-pentylphosphonic acid, isopentylphosphonic acid, n-hexylphosphonic acid, isohexylphosphonic acid, heptylphosphonic acid, octylphosphonic acid, nonylphosphonic acid, decylphosphonic acid, undecylphosphonic acid, dodecylphosphonic acid, cyclohexylphosphonic acid, cyclooctylphosphonic acid, and cyclodecylphosphonic acid. Specifically, examples of arylphosphonic acids include phenylphosphonic acid, methylphenylphosphonic acid, dimethylphenylphosphonic acid, trimethylphenylphosphonic acid, tetramethylphenylphosphonic acid, pentamethylphenylphosphonic acid, ethylphenylphosphonic acid, methylethylphenylphosphonic acid, diethylphenylphosphonic acid, monomethyldiethylphenylphosphonic acid, dimethyldiethylphenylphosphonic acid, triethylphenylphosphonic acid, propylphenylphosphonic acid, methylpropylphenylphosphonic acid, dimethylpropylphenylphosphonic acid, ethylpropylphenylphosphonic acid, dipropylphenylphosphonic acid, butylphenylphosphonic acid, methylbutylphenylphosphonic acid, ethylbutylphenylphosphonic acid, dimethylbutylphenylphosphonic acid, pentylphenylphosphonic acid, methylpentylphenylphosphonic acid, hexylphenylphosphonic acid, naphthylphosphonic acid, methylnaphthylphosphonic acid, dimethylnaphthylphosphonic acid, ethylnaphthylphosphonic acid, and benzylphosphonic acid. In the case of compounds in these groups of compounds, in the case of compounds with multiple aliphatic groups bonded to the phenyl or naphthyl group, it goes without saying that regardless of the substitution position of these aliphatic groups on the phenyl or naphthyl group, they belong to the phosphorus compounds represented by general formula (I) or (II) of the present invention.

[0052] In addition, as phosphate esters of alkylphosphonic acids, arylphosphonic acids, and benzylphosphonic acids, examples include dimethyl ester, diethyl ester, dipropyl ester, di-n-butyl ester, di-tert-butyl ester, di-n-pentyl ester, diisopentyl ester, dihexyl ester, diisohexyl ester, diheptyl ester, dioctyl ester, dinonyl ester, didecyl ester, di(undecyl) ester, di(dodecyl) ester, dicyclohexyl ester, dicyclooctyl ester, dicyclodecyl ester, diethylene glycol ester, methyl ethyl ester, methyl propyl ester, methyl n-butyl ester, methyl tert-butyl ester, methyl n-pentyl ester, methyl isopentyl ester, methyl hexyl ester, methyl isohexyl ester, methyl heptyl ester, methyl heptyl ester, methyl octyl ester, methyl nonyl ester, methyl decyl ester, methyl undecyl ester, methyl dodecyl ester, methyl cyclohexyl ester, and methyl Cyclooctyl ester, methyl cyclodecyl ester, ethyl propyl ester, ethyl n-butyl ester, ethyl tert-butyl ester, ethyl n-pentyl ester, ethyl isopentyl ester, ethyl hexyl ester, ethyl isohexyl ester, ethyl heptyl ester, ethyl octyl ester, ethyl nonyl ester, ethyl decyl ester, ethyl undecyl ester, ethyl dodecyl ester, ethyl cyclohexyl ester, ethyl cyclooctyl ester, ethyl cyclodecyl ester, propyl n-butyl ester, propyl tert-butyl ester, propyl n-pentyl ester, propyl isopentyl ester, propyl hexyl ester, propyl isohexyl ester, propyl heptyl ester, propyl octyl ester, propyl nonyl ester, propyl decyl ester, propyl undecyl ester, propyl dodecyl ester, propyl cyclohexyl ester, propyl cyclooctyl ester, propyl cyclodecyl ester, n-butyl tert-butyl ester, n-butyl n-pentyl ester, n-butyl isopentyl ester, n-butyl Hexyl ester, n-butyl isohexyl ester, n-butyl heptyl ester, n-butyl octyl ester, n-butyl nonyl ester, n-butyl decyl ester, n-butyl undecyl ester, n-butyl dodecyl ester, n-butyl cyclohexyl ester, n-butyl cyclooctyl ester, n-butyl cyclodecyl ester, tert-butyl n-pentyl ester, tert-butyl isopentyl ester, tert-butyl hexyl ester, tert-butyl isohexyl ester, tert-butyl heptyl ester, tert-butyl heptyl ester, tert-butyl cyclooctyl ester, tert-butyl cyclodecyl ester, n-pentyl isopentyl ester, n-pentyl hexyl ester, n-pentyl isohexyl ester, n-pentyl heptyl ester, n-pentyl octyl ester, n-pentyl nonyl ester, n-pentyl decyl ester, n-pentyl undecyl ester, n-pentyl dodecyl ester alkyl esters, n-pentylcyclohexyl ester, n-pentylcyclooctyl ester, n-pentylcyclodecyl ester, isopentylhexyl ester, isopentylisohexyl ester, isopentylheptyl ester, isopentylnonyl ester, isopentyldecyl ester, isopentylundecyl ester, isopentyldodecyl ester, isopentylcyclohexyl ester, isopentylcyclooctyl ester, isopentylcyclodecyl ester, hexylisohexyl ester, hexylheptyl ester, hexyloctyl ester, hexylnonyl ester, hexyldecyl ester, hexylundecyl ester, hexyldodecyl ester, hexylcyclohexyl ester, hexylcyclooctyl ester, hexylcyclodecyl ester, isopentylheptyl ester, isopentyloctyl ester, isopentylnonyl ester, isopentyldecyl ester, isopentylundecyl ester, isopentyldodecyl ester, isopentylcyclohexyl ester, isopentylcyclooctyl ester, isopentylcyclodecyl esterHeptyl octyl ester, heptyl nonyl ester, heptyl decyl ester, heptyl undecyl ester, heptyl dodecyl ester, heptyl cyclohexyl ester, heptyl cyclooctyl ester, heptyl cyclodecyl ester, octyl nonyl ester, octyl decyl ester, octyl undecyl ester, octyl dodecyl ester, octyl cyclohexyl ester, octyl cyclooctyl ester, octyl cyclodecyl ester, nonyl decyl ester, nonyl undecyl ester, nonyl dodecyl ester, nonyl cyclohexyl ester, nonyl cyclooctyl ester, nonyl cyclodecyl ester, decyl undecyl ester Alkyl esters, decyl dodecyl ester, decyl cyclohexyl ester, decyl cyclooctyl ester, decyl cyclodecyl ester, undecyl dodecyl ester, undecyl cyclohexyl ester, undecyl cyclooctyl ester, undecyl cyclodecyl ester, dodecyl cyclohexyl ester, dodecyl cyclodecyl ester, cyclohexyl cyclooctyl ester, cyclohexyl cyclodecyl ester, cyclooctyl cyclodecyl ester, diphenyl ester, dinaphthalene ester, dibenzyl ester, phenylnaphthalene ester, phenyl benzyl ester, naphthyl benzyl ester.

[0053] The compound represented by formula (II) above is an organophosphonic acid or its phosphate ester form. More specifically, examples include alkylphosphonic acids, arylphosphonic acids, or benzylphosphonic acids, or their phosphate ester forms. Examples of alkylphosphonic acids, arylphosphonic acids, and benzylphosphonic acids include compounds formed by converting the phosphonic acid portion of the phosphonic acid compounds mentioned in the specific examples above into phosphonic acids. Furthermore, examples of phosphate ester forms of alkylphosphonic acids, arylphosphonic acids, and benzylphosphonic acids include, specifically, methyl esters, ethyl esters, n-propyl esters, n-butyl esters, tert-butyl esters, n-pentyl esters, isoamyl esters, n-hexyl esters, isohexyl esters, heptyl esters, octyl esters, nonyl esters, decyl esters, undecyl esters, dodecyl esters, cyclohexyl esters, cyclooctyl esters, cyclodecyl esters, ethylene glycol esters, phenyl esters, naphthyl esters, and benzyl esters. Another example is 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide.

[0054] The compounds represented by formula (I) or (II) above may also be their salts. Preferably, the salt is selected from at least one of manganese salts, cobalt salts, and zinc salts.

[0055] Furthermore, the PEN composition of the present invention preferably contains at least one selected from manganese ions, cobalt ions, and zinc ions. These manganese ions, cobalt ions, and zinc ions can be obtained by adding compounds containing these ions, such as manganese acetate tetrahydrate, cobalt acetate tetrahydrate, zinc acetate dihydrate, etc.

[0056] These manganese, cobalt, and zinc ions act as catalysts for the transesterification reaction of polyethylene naphthalate. The content of at least one of these manganese, cobalt, and zinc ions is preferably 10–50 mmol% per mole relative to the dicarboxylic acid component constituting polyethylene naphthalate. When the content is less than 10 mmol%, no effect is observed; conversely, if it exceeds 50 mmol%, graying of the hue may occur, resulting in a deterioration in color. More preferably, the content is 15–45 mmol%, even more preferably 18–40 mmol%, and particularly more preferably 20–35 mmol.

[0057] The sheet formed from the PEN composition of the present invention is characterized in that the refractive index in the stretching direction of the sheet after being stretched at the maximum uniaxial stretching ratio is higher than the refractive index of the sheet formed from a resin composition that does not contain the above-mentioned phosphorus compound or its salt, after being stretched under the same conditions at the maximum uniaxial stretching ratio. Here, the maximum uniaxial stretching ratio refers to the ratio at which the sheet is about to break when it is stretched uniaxially.

[0058] Therefore, the present invention also relates to a uniaxially stretched film formed by uniaxially stretching the above-mentioned PEN composition. The refractive index in the stretching direction of the uniaxially stretched film of the present invention is preferably 1.80 to 1.95, more preferably 1.85 to 1.95.

[0059] Example

[0060] The present invention will now be described in detail with reference to examples, but the invention is not limited to the following examples unless it departs from its spirit. It should be noted that the film-forming conditions and stretching conditions of the obtained polyethylene naphthalate resin composition film, as well as the determination of various physical properties, were performed by the following methods. It should be noted that unless otherwise specified, the term "parts" in the following description refers to "parts by weight".

[0061] (a) Film-forming conditions

[0062] The PEN composition chips were dried at 160°C for 5 hours before film formation to remove moisture. Film formation was then carried out at a film formation temperature of 285–300°C, with the resulting film thickness adjusted to approximately 200 μm, to obtain an unstretched sheet.

[0063] (b) Tensile conditions

[0064] The stretching was performed at a temperature of 140℃ and a stretching speed of 2.1 m / min. The stretch ratio was calculated by measuring the elongation at 1 cm intervals marked before the sheet broke.

[0065] (c) Refractive index

[0066] The refractive index of the stretched film was measured using a prism coupler model 2010 from Metricon at a laser wavelength of 633 nm.

[0067] (d) Intrinsic viscosity

[0068] The PEN composition was dissolved in a mixed solvent of phenol / tetrachloroethane (60 / 40 weight ratio) to prepare a solution with a polymer concentration of 1.2 g / dL. The intrinsic viscosity was determined by measuring the solution at 35 degrees Celsius.

[0069] (e) Glass transition temperature (Tg)

[0070] Tg was determined using a differential scanning calorimeter (DSC) at a heating rate of 20 °C / min. The sample was weighed in an aluminum pot (TA Instruments) at a rate of approximately 10 mg and the determination was performed under a nitrogen atmosphere.

[0071] (f) Orientation

[0072] The stretched film was subjected to WAXD (wide-angle X-ray diffraction) measurements. Based on the results from the thru-view, the full width at half maximum (WH) of the orientation peak at a diffraction angle of 2θ = 15.3° was used, and the degree of orientation was calculated using the formula: degree of orientation = (180 - WH) / 180 × 100. If the degree of orientation is greater than 94.5%, the crystallinity resulting from molecular orientation increases, which is therefore preferred from the viewpoint of increasing the refractive index in the stretching direction.

[0073] (g) Crystal size

[0074] The stretched film underwent WAXD (wide-angle X-ray diffraction) measurements. Based on the results from the through view, the peak at the diffraction angle 2θ = 15.3° was calculated using the following Scherrer formula. If the crystal size is below 6 nm, light scattering is suppressed, which is preferable from the perspective of uniformly increasing the refractive index.

[0075] Scherrer's formula: D = Kλ / BCosθ

[0076] D: Crystal size

[0077] K: Scherrer constant (0.94)

[0078] λ: X-ray wavelength (154.2 nm)

[0079] B: Half-peak width of the peak

[0080] θ: Angle Bragg

[0081] [Example 1]

[0082] 100 parts of dimethyl 2,6-naphthalenedicarboxylate (hereinafter sometimes referred to as NDC) and 51 parts of ethylene glycol (hereinafter sometimes referred to as EG) were added to a reaction vessel. Manganese acetate tetrahydrate, at a molar percentage relative to NDC, was used as the transesterification catalyst to initiate the transesterification reaction. After methanol distillation, 20 minutes later, antimony trioxide, at a molar percentage relative to NDC, was added as a polymerization catalyst to continue the transesterification reaction. Then, after approximately 1 hour, phenylphosphonic acid, at a molar percentage relative to NDC, was added to terminate the transesterification reaction. Next, polycondensation was carried out under high temperature and high vacuum. The polymer was then removed from the reaction vessel and sliced.

[0083] The obtained polyethylene 2,6-naphthalenedicarboxylate composition was used to form an unstretched sheet. The intrinsic viscosity of the unstretched sheet was 0.55 dL / g. Then, it was stretched to obtain a stretched film. The refractive index of the obtained stretched film was measured, and the results are shown in Table 1.

[0084] [Example 2]

[0085] Instead of phenylphosphonic acid, 150 mmol% (1268 ppm) of HCA (represented by the chemical formula hereinafter) was added relative to NDC, and slices were prepared in the same manner as in Example 1. Unstretched sheets were obtained by film formation. The intrinsic viscosity of the obtained unstretched sheets was 0.60 dL / g. Stretching was then performed to obtain stretched films. The refractive index of the obtained stretched films was measured, and the results are shown in Table 1.

[0086]

[0087] [Comparative Example 1]

[0088] The 40 mmol% phenylphosphonic acid was replaced with 50 mmol% (200 ppm) orthophosphoric acid. Otherwise, slices were prepared in the same manner as in Example 1, and an unstretched sheet was obtained by film formation. The intrinsic viscosity of the obtained unstretched sheet was 0.51 dL / g. Then, stretching was performed to obtain a stretched film. The refractive index of the obtained stretched film was measured, and the results are shown in Table 1.

[0089] [Comparative Example 2]

[0090] Instead of phosphoric acid, 500 mmol% (4536 ppm) of TPP (triphenyl phosphate, represented by the following chemical formula) was added relative to NDC. Otherwise, slices were prepared in the same manner as in Comparative Example 1, and an unstretched sheet was obtained by film formation. The intrinsic viscosity of the obtained unstretched sheet was 0.58 dL / g. Then, stretching was performed to obtain a stretched film. The refractive index of the obtained stretched film was measured, and the results are shown in Table 1.

[0091]

[0092] [Table 1]

[0093]

Claims

1. A polyethylene naphthalate resin composition for optical components, comprising: (A) Polyethylene naphthalate, and (B) A phosphorus compound or a salt thereof represented by formula (I) or (II), In the formula, R1 represents an alkyl group with 1 to 12 carbon atoms, an aryl group with 6 to 12 carbon atoms, or a benzyl group, and R2 and R3 represent an alkyl group with 1 to 12 carbon atoms, an aryl group with 6 to 12 carbon atoms, a benzyl group, an ethylene glycol group, or a hydrogen atom. R1 and R2 can be bonded to form a ring.

2. The resin composition according to claim 1, wherein, The amount of the phosphorus compound or its salt added is 0.1 to 10,000 ppm.

3. The resin composition according to claim 1, wherein, The phosphorus compound or its salt is phenylphosphonic acid or its salt, or 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide or its salt.

4. The resin composition according to claim 1, wherein, The salt is selected from at least one of manganese salts, cobalt salts, and zinc salts, and / or The resin composition contains at least one selected from manganese ions, cobalt ions, and zinc ions.

5. The resin composition according to claim 1, wherein, The refractive index in the stretching direction of a sheet of the resin composition stretched at the maximum uniaxial stretching ratio is higher than the refractive index of a sheet of the resin composition without the addition of the phosphorus compound or its salt stretched at the maximum uniaxial stretching ratio under the same conditions.

6. A uniaxially stretched film comprising the resin composition of claim 1.

7. The uniaxially stretched membrane according to claim 5, wherein, The refractive index in the stretching direction is 1.80–1.

95.

8. The uniaxially stretched membrane according to claim 5, wherein, The orientation degree is above 94.5%, and the crystal size is below 6nm.

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