JP2010229289A - Polyester film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polyester film that is excellent in moldability so that the stress induced in the film is maintained low during the molding process and the film has high elongation and is excellent in heat resistance and dimensional stability as well. <P>SOLUTION: The polyester film has a peak intensity ratio obtained by measurement of X ray diffraction peak intensity (a transmission method) which satisfies formula (1), 0.4<Ib/Ia≤1.2, and formula (2), 0.4<Ic/Ib≤1.2, in which Ia is a peak intensity near 2θ=26°; Ib is a peak intensity near 2θ=23.5°; and Ic is a peak intensity near 2θ=22.5°, provided that the peak intensity is obtained by 2θ/θ scan measurement (measurement of change in intensity relative to an angle of θ by allowing X rays to be incident at an angle of θ to the direction of a film surface (to the horizontal direction of a sample) and detecting X rays of an angle of 2θ to the incident X ray from among X-rays reflected from the sample). <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention has excellent moldability and is extremely excellent in moldability that can easily form a molded part that follows a mold in thermoforming such as vacuum and pressure forming. The present invention relates to a polyester film that is suitably used for molded member applications such as telephones and electrical products.

  In recent years, due to increasing environmental awareness, there has been an increasing demand for solvent-free coating and plating substitutes for building materials, automotive parts, mobile phones, electrical appliances, etc., and the introduction of decorative methods for molded parts using decorative sheets for molding has been introduced. Progressing.

  Under such circumstances, several proposals have been made as molding polyester films. For example, a polyester film excellent in moldability having a specific melting point and elongation at break has been proposed (see, for example, Patent Document 1). Furthermore, a film in which polyethylene terephthalate and polybutylene terephthalate are mixed at 1: 1 to give formability is disclosed (for example, see Patent Document 2). However, these proposed films have a high deformation stress at the time of forming, so that it is difficult to form a complicated shape.

  Further, a polyester film for molded members having a specific melting point and employing specific film forming conditions is also disclosed (for example, see Patent Document 3). Further, in order to achieve both formability, designability, and smoothness, a polyester film having a three-layer laminated film of an A layer, a B layer, and a C layer and having a moldability in the B layer of the intermediate layer has been proposed (for example, , See Patent Document 4). However, these polyester films do not have sufficient elongation at break and cannot withstand deep drawing.

JP 2001-72841 A JP 2002-321277 A JP 2003-221606 A JP 2006-51747 A

  The present invention eliminates the problems of the prior art described above, maintains a low stress during molding, and provides a polyester film having excellent heat resistance and dimensional stability in addition to excellent moldability with high elongation. Is.

The present invention employs the following means in order to solve such problems. That is, the polyester film of the present invention is characterized in that the peak intensity ratio obtained by X-ray diffraction intensity measurement (transmission method) satisfies the expressions (1) and (2).
0.4 <Ib / Ia ≦ 1.2 (1)
0.4 <Ic / Ib ≦ 1.2 (2)
Ia: peak intensity near 2θ = 26 ° Ib: peak intensity near 2θ = 23.5 ° Ic: peak intensity near 2θ = 22.5 ° where the peak intensity is 2θ / θ scan measurement (X-rays on the film surface) The incident angle is θ with respect to the direction (horizontal direction of the sample), and X-rays reflected from the sample are detected at an angle of 2θ with respect to the incident X-ray, and the intensity change with respect to θ is measured) It is what I have sought.

  The polyester film of the present invention is easily molded by thermoforming, and has excellent heat resistance and dimensional stability, and can be uniformly formed into a complicated shape. It can be suitably used for molded parts such as automobile parts, mobile phones, electrical products, and gaming machine parts.

It is explanatory drawing (sectional drawing) of X-ray diffraction intensity measurement (2 (theta) / (theta) scan measurement).

In order to satisfy the excellent moldability and heat resistance of the polyester film of the present invention, the peak intensity ratio obtained from X-ray diffraction intensity measurement (transmission method) must satisfy the following formulas (1) and (2): It is.
0.4 <Ib / Ia ≦ 1.2 (1)
0.4 <Ic / Ib ≦ 1.2 (2)
Here, Ia is a peak intensity in the vicinity of 2θ = 26 °, Ib is a peak intensity in the vicinity of 2θ = 23.5 °, and Ic is a peak intensity in the vicinity of 2θ = 22.5 °. The peak intensity in the vicinity of 2θ = 26 ° means a value having the highest intensity in the range of 2θ = 25.5 ° to 26.5 °. Similarly, the peak intensity in the vicinity of 2θ = 23.5 ° The highest intensity value in the range of 2θ = 23.1 ° to 24 °, and the peak intensity in the vicinity of 2θ = 22.5 ° refers to the highest intensity value in the range of 2θ = 22.1 ° to 23 °. .

  The peak intensity is 2θ / θ scan measurement (X-rays are incident at an angle of θ with respect to the film surface direction (sample horizontal direction), and 2θ with respect to the incident X-rays out of the X-rays reflected from the sample. The angle X-ray is detected and the intensity change with respect to θ is measured) (FIG. 1).

When Ib / Ia is larger than 1.2, the heat resistance of the film is lowered, and the film may not be able to withstand the processing step. On the other hand, if Ib / Ia is 0.4 or less, sufficient moldability may not be obtained. Moreover, when Ic / Ib is larger than 1.2, the transparency of the film is lowered. On the other hand, when Ic / Ib is 0.4 or less, the dimensional stability of the film is lowered. The following expressions (1) ′ and (2) ′ are more preferable, and the expression (1) ″ (2) ″ is most preferable.
0.4 <Ib / Ia ≦ 1.1 (1) ′
0.5 <Ic / Ib ≦ 1.1 (2) ′
0.4 <Ib / Ia ≦ 1 (1) ''
0.6 <Ic / Ib ≦ 1 (2) ''
In order for the polyester film of the present invention to satisfy the formula (1), a method of setting the plane orientation coefficient of the film to 0.04 or more and 0.1 or less is mentioned. By setting the plane orientation coefficient in the above-described range, it becomes difficult for crystals in the film plane direction to grow, so Ia becomes small, and it becomes easy to satisfy the formula (1). The range of the plane orientation coefficient is more preferably 0.045 or more and 0.09 or less, and most preferably 0.05 or more and 0.08 or less.

  In order to make the plane orientation coefficient of the polyester film of the present invention 0.04 or more and 0.1 or less, for example, a method of constituting a film composition from a specific diol component can be mentioned.

  The polyester resin constituting the polyester film of the present invention is a general term for polymer compounds in which the main bonds in the main chain are ester bonds, and is usually obtained by polycondensation reaction of a dicarboxylic acid component and a glycol component. Can do.

  In the present invention, from the viewpoint of moldability, appearance, heat resistance, dimensional stability, and economy, it is preferable that 50 mol% or more of the glycol component constituting the polyester film is an ethylene glycol component. When it is less than 50 mol%, the heat resistance is particularly poor and it cannot be used for molding. As long as the glycol component contains 50 mol% or more of an ethylene glycol component, a plurality of other glycol components may be included.

  Other glycol components contained in the polyester film of the present invention include 1,2-propanediol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, Aliphatic dihydroxy compounds such as 1,6-hexanediol and neopentyl glycol, polyoxyalkylene glycols such as diethylene glycol, polyethylene glycol, polypropylene glycol and polytetramethylene glycol, and alicyclic dihydroxy compounds such as 1,4-cyclohexanedimethanol And aromatic dihydroxy compounds such as bisphenol A and bisphenol S.

  Preferred dicarboxylic acid components used in the polyester film of the present invention include terephthalic acid, isophthalic acid, phthalic acid, 2,6-naphthalenedicarboxylic acid, diphenyldicarboxylic acid, diphenylsulfone dicarboxylic acid, diphenoxyethanedicarboxylic acid, 5 -Aliphatic dicarboxylic acids such as sodium sulfone dicarboxylic acid, oxalic acid, succinic acid, adipic acid, sebacic acid, dimer acid, maleic acid, fumaric acid and other aliphatic dicarboxylic acids, 1,4-cyclohexanedicarboxylic acid and other alicyclic rings Oxycarboxylic acids such as aliphatic dicarboxylic acids and paraoxybenzoic acids. The dicarboxylic acid ester derivatives include esterified products of the above dicarboxylic acid compounds, such as dimethyl terephthalate, diethyl terephthalate, 2-hydroxyethyl methyl terephthalate, dimethyl 2,6-naphthalenedicarboxylate, dimethyl isophthalate, and dimethyl adipate. , Diethyl maleate, dimethyl dimer, and the like.

  In order to make the plane orientation coefficient of the polyester film of the present invention 0.04 or more and 0.1 or less, 10 to 20 mol% of the glycol component is preferably a 1,4-cyclohexanedimethanol component. A more preferable range of the 1,4-cyclohexanedimethanol component is 11 to 18 mol%, and most preferably 12 to 17 mol%.

  Moreover, as a method of setting the plane orientation coefficient of the polyester film of the present invention to 0.04 or more and 0.1 or less, there is a method of stretching at least uniaxially, more preferably biaxially. When the film is stretched in the longitudinal direction and the width direction (biaxial stretching), a stretching ratio of 2.5 to 3.5 times is preferably employed in the longitudinal direction and the width direction, respectively.

  The total draw ratio is preferably 6.2 times or more and 13 times or less. The total draw ratio is obtained by multiplying the draw ratio in the longitudinal direction by the draw ratio in the width direction. If the total draw ratio is set to a low value of less than 6.2 times in an attempt to reduce the plane orientation coefficient of the film, the thickness unevenness may increase, which is not preferable. If the total draw ratio is larger than 13, the plane orientation coefficient may exceed 0.1. The stretching speed is preferably 1,000 to 200,000% / min. The stretching temperature is preferably 80 to 130 ° C. In the case of stretching biaxially, it is preferable that the stretching temperature in the longitudinal direction is 85 to 120 ° C and the stretching temperature in the width direction is 90 to 110 ° C. By including the glycol component described above and employing the above stretching conditions, it is possible to achieve a moderately low orientation such that the plane orientation coefficient is 0.04 or more and 0.1 or less.

  In addition, the heat treatment conditions of the film after biaxial stretching are also important for adjusting the plane orientation coefficient. The heat treatment can be performed by any conventionally known method such as in an oven or on a heated roll. However, the heat treatment temperature can be increased at a high temperature to achieve low orientation as described above. it can. A preferable heat treatment temperature is a film melting point of −60 ° C. or more and a film melting point or less, more preferably a film melting point of −50 ° C. or more and a film melting point of −10 ° C. or less, and a film melting point of −40 ° C. or more and a film melting point of −15 ° C. or less. Is most preferable. When the heat treatment temperature is lower than the film melting point−60 ° C., the orientation relaxation is not sufficiently performed, and the plane orientation coefficient may be larger than 0.1. Furthermore, the dimensional stability may be lowered, which is not preferable. Further, if the heat treatment temperature is higher than the film melting point−5 ° C., film thickness unevenness and whitening may occur and the quality may be deteriorated.

  Further, the heat treatment may be performed by relaxing the film in the MD direction and / or the TD direction. The MD direction here refers to the longitudinal direction of the film (the traveling direction of the film in the film forming process), while the TD direction refers to the width direction of the film (the direction orthogonal to the MD direction).

  The polyester film of the present invention preferably has a melting point of 230 ° C. or higher and 250 ° C. or lower in terms of heat resistance and moldability. When the melting point exceeds 250 ° C., the heat resistance is too high, so that the deformation stress at the time of secondary processing of the film is too high, making it difficult to form a complicated shape. On the other hand, when the melting point of the polyester film is less than 230 ° C., the film may be melted at the time of high-temperature molding, which is not preferable because the handleability is lowered. The melting point here is an endothermic peak temperature which is manifested by a melting phenomenon when measured at a temperature rising rate of 20 ° C./min using a differential scanning calorimeter. When polyester resins having different compositions are blended and used to form a film, a plurality of endothermic peaks accompanying melting may appear. In this case, the endothermic peak temperature appearing at the highest temperature is defined as the melting point.

  In order for the polyester film of the present invention to satisfy the formula (2), for example, a method of constituting a film composition from a specific diol component can be mentioned. For example, 4 to 30 mol% is preferably 1,4-butanediol or 1,3-propanediol, and 8 to 30 mol% is 1,4-butanediol from the viewpoint of dimensional stability. preferable. By including the glycol component as described above, Ic increases, and the formula (2) is easily satisfied.

  Moreover, in order for the polyester film of this invention to satisfy | fill Formula (2), it is preferable to contain a crystal nucleating agent. Here, the crystal nucleating agent refers to a crystalline substance that improves the crystallization speed by adding to polyester, for example, talc, aliphatic carboxylic acid amide, aliphatic carboxylate, aliphatic alcohol, aliphatic It can be preferably selected from the group of carboxylic acid esters, sorbitol compounds, and organic phosphoric acid compounds. Among these, in the present invention, the crystal nucleating agent is particularly preferably at least one crystal nucleating agent selected from the group consisting of aliphatic carboxylic acid amides, aliphatic carboxylates and sorbitol compounds. By containing a crystal nucleating agent, Ic increases, and the formula (2) is easily satisfied. Here, as preferable content of a crystal nucleating agent, the whole polyester film is 100 mass%, and a crystal nucleating agent is 0.1 mass% or more and less than 2 mass%. If the concentration of the crystal nucleating agent is less than 0.1% by mass, the effect may not be sufficiently exhibited. If the content of the crystal nucleating agent is 2% by mass or more, the transparency may be impaired, which is not preferable. More preferably, it is 0.15% by mass or more and less than 1.5% by mass, and most preferably 0.2% by mass or more and less than 1% by mass.

  Here, aliphatic carboxylic acid amides include aliphatic monocarboxylic acids such as lauric acid amide, palmitic acid amide, oleic acid amide, stearic acid amide, erucic acid amide, behenic acid amide, ricinoleic acid amide, and hydroxy stearic acid amide. Acid amides, N-oleyl palmitic acid amide, N-oleyl oleic acid amide, N-oleyl stearic acid amide, N-stearyl oleic acid amide, N-stearyl stearic acid amide, N-stearyl erucic acid amide, methylol stearic acid amide N-substituted aliphatic monocarboxylic amides such as methylol behenic acid amide, methylene bis stearic acid amide, ethylene bis lauric acid amide, ethylene bis capric acid amide, ethylene bis oleic acid amide, Phosphoric acid amide, ethylene biserucic acid amide, ethylene bisbehenic acid amide, ethylene bisisostearic acid amide, ethylene bishydroxystearic acid amide, butylene bisstearic acid amide, hexamethylene bisoleic acid amide, hexamethylene bisstearic acid Aliphatic biscarboxylic amides such as amide, hexamethylene bisbehenic acid amide, hexamethylene bishydroxystearic acid amide, m-xylylene bisstearic acid amide, m-xylylene bis-12-hydroxystearic acid amide, N, N′-dioleyl sebacic acid amide, N, N′-dioleyl adipic acid amide, N, N′-distearyl adipic acid amide, N, N′-distearyl sebacic acid amide, N, N′-di Stearyl isophthalamide, N-substituted aliphatic carboxylic acid bisamides such as N, N-distearyl terephthalamide, N-butyl-N'-stearyl urea, N-propyl-N'-stearyl urea, N-stearyl-N'-stearyl Use N-substituted ureas such as urea, N-phenyl-N'-stearyl urea, xylylene bisstearyl urea, toluylene bisstearyl urea, hexamethylene bisstearyl urea, diphenylmethane bisstearyl urea, diphenylmethane bislauryl urea be able to. These may be one kind or a mixture of two or more kinds. Among these, aliphatic monocarboxylic acid amides, N-substituted aliphatic monocarboxylic acid amides, and aliphatic biscarboxylic acid amides are preferably used. In particular, palmitic acid amide, stearic acid amide, erucic acid amide, and behenic acid are used. Amide, ricinoleic acid amide, hydroxystearic acid amide, N-oleyl palmitic acid amide, N-stearyl erucic acid amide, ethylene biscapric acid amide, ethylene bisoleic acid amide, ethylene bislauric acid amide, ethylene biserucic acid amide, m -Xylylene bis-stearic acid amide and m-xylylene bis-12-hydroxystearic acid amide are preferably used.

  Specific examples of the aliphatic carboxylate include acetates such as sodium acetate, potassium acetate, magnesium acetate, calcium acetate, sodium laurate, potassium laurate, potassium hydrogen laurate, magnesium laurate, calcium laurate, zinc laurate , Laurates such as silver laurate, lithium myristate, sodium myristate, potassium hydrogen myristate, magnesium myristate, calcium myristate, zinc myristate, silver myristate, myristate, lithium palmitate, palmitic acid Potassium, magnesium palmitate, calcium palmitate, zinc palmitate, copper palmitate, lead palmitate, thallium palmitate, cobalt palmitate, etc., palmitate, sodium oleate Oleates such as potassium oleate, magnesium oleate, calcium oleate, zinc oleate, lead oleate, thallium oleate, copper oleate, nickel oleate, sodium stearate, lithium stearate, magnesium stearate, stear Stearates such as calcium phosphate, barium stearate, aluminum stearate, thallium stearate, lead stearate, nickel stearate, beryllium stearate, sodium isostearate, potassium isostearate, magnesium isostearate, calcium isostearate, barium isostearate , Isostearates such as aluminum isostearate, zinc isostearate, nickel isostearate, sodium behenate , Potassium behenate, magnesium behenate, calcium behenate, barium behenate, aluminum behenate, zinc behenate, nickel behenate, etc., sodium montanate, potassium montanate, magnesium montanate, calcium montanate Further, montanates such as barium montanate, aluminum montanate, zinc montanate and nickel montanate can be used. These may be one kind or a mixture of two or more kinds. In particular, stearic acid salts and montanic acid salts are preferably used, and in particular, sodium stearate, potassium stearate, zinc stearate, barium stearate, sodium montanate, and the like are suitably used.

  Specific examples of the aliphatic alcohol include aliphatic monoalcohols such as pentadecyl alcohol, cetyl alcohol, heptadecyl alcohol, stearyl alcohol, nonadecyl alcohol, eicosyl alcohol, seryl alcohol, and melyl alcohol, 1,6-hexane. Diol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, aliphatic polyhydric alcohols such as 1,10-decanediol, cyclopentane-1,2-diol, cyclohexane-1 , 2-diol, cyclic alcohols such as cyclohexane-1,4-diol, and the like can be used. These may be one kind or a mixture of two or more kinds. In particular, aliphatic monoalcohols are preferably used, and stearyl alcohol is particularly preferably used.

  Specific examples of the aliphatic carboxylic acid ester include lauric acid cetyl ester, lauric acid phenacyl ester, myristic acid cetyl ester, myristic acid phenacyl ester, palmitic acid isopropylidene ester, palmitic acid dodecyl ester, and palmitic acid tetraethyl ester. Aliphatic monocarboxylic acid esters such as dodecyl ester, palmitic acid pentadecyl ester, palmitic acid octadecyl ester, palmitic acid cetyl ester, palmitic acid phenyl ester, palmitic acid phenacyl ester, stearic acid cetyl ester, behenic acid ethyl ester, Monoesters of ethylene glycol such as glycol monolaurate, glycol monopalmitate, glycol monostearate, glycol dilaurate, di Diesters of ethylene glycol such as glycol lumitate and glycol distearate, glycerin monoesters such as monolauric acid glycerin ester, monomyristic acid glycerin ester, monopalmitic acid glycerin ester, monostearic acid glycerin ester, dilauric acid glycerin ester, Glycerin diesters such as dimyristic acid glycerin ester, dipalmitic acid glycerin ester, distearic acid glycerin ester, trilauric acid glycerin ester, trimyristic acid glycerin ester, tripalmic acid glycerin ester, tristearic acid glycerin ester, palmitodiolein, Use glycerol triesters such as palmitodistearin and oleodistearin. Can. These may be one kind or a mixture of two or more kinds. Of these, ethylene glycol diesters are preferred, and ethylene glycol distearate is particularly preferred.

  Specific examples of such aliphatic / aromatic carboxylic acid hydrazides include sebacic acid dibenzoic acid hydrazide, specific examples of melamine compounds, specific examples of melamine cyanurate, polymelate melamine, and phenylphosphonic acid metal salts. For example, phenylphosphonic acid zinc salt, phenylphosphonic acid calcium salt, phenylphosphonic acid magnesium salt, and phenylphosphonic acid magnesium salt can be used.

  Examples of the sorbitol compound include 1,3-di (P-methylbenzylidene) sorbitol, 2,4-di (P-methylbenzylidene) sorbitol, 1,3-dibenzylidenesorbitol, 2,4-dibenzylidenesorbitol, Examples include 3-di (P-ethyldibenzylidene) sorbitol and 2,4-di (P-ethyldibenzylidene) sorbitol.

  Sodium bis (4-t-butylphenyl) phosphate, phosphoric acid-2,2′-methylenebis (4,6-di-t-butylphenyl) sodium, cyclic organophosphate basic polyvalent metal salt and alkali metal Examples thereof include a mixture selected from a carboxylate, an alkali metal β-diketonate, and an alkali metal β-ketoacetate salt and an organic carboxylate metal salt.

  Among the above, aliphatic carboxylic acid amides, aliphatic carboxylates and sorbitol compounds are preferably used from the viewpoint of transparency and heat resistance.

  Further, as a preferable method satisfying the formula (2), a method of increasing the heat treatment temperature can also be mentioned. Increasing the heat treatment temperature increases Ic, which makes it easier to satisfy equation (2). In order to make it compatible with the quality of the film, the heat treatment temperature is preferably a film melting point of −40 ° C. or more and a film of −15 ° C. or less, and more preferably a film melting point of −30 ° C. or more and a film melting point of −15 ° C. or less.

  In the polyester film of the present invention, from the viewpoint of film secondary workability such as thermoforming, it is preferable that the elongation at break in the longitudinal direction and the width direction at 150 ° C. in at least one direction is 300% or more and 700% or less. . If the breaking elongation of the film at 150 ° C. is less than 300%, the film may break during thermoforming or deformation may be insufficient. Further, if it is attempted to be higher than 700%, it is very difficult to achieve both heat resistance, and the film may be deformed because it cannot withstand the tension for transferring the film in the preheating step in the molding process. This is not preferable. The polyester film of the present invention is sufficiently molded even if there is a direction in which the breaking elongation does not satisfy 300% or more and 700% or less as long as the breaking elongation at 150 ° C in at least one direction is 300% or more and 700% or less. And heat resistance can be satisfied. The elongation at break at 150 ° C. is preferably 320 to 650% from the viewpoint of handleability and moldability, and most preferably 350 to 600%.

  Here, the breaking elongation at 150 ° C. means that a film sample cut into a rectangular shape having a test length of 20 mm is preheated for 90 seconds in a constant temperature layer set at 150 ° C., and then subjected to a tensile test at a strain rate of 500 mm / min. It is the elongation when the film breaks.

  In order that the breaking elongation of the film at 150 ° C. in at least one direction of the polyester film in the present invention satisfies the above range, it is preferable that the total stretching ratio of the film is 6.2 times or more and 13 times or less. In the heat setting step after stretching, it is preferable to increase the heat treatment temperature because the orientation of the amorphous portion of the film can be relaxed. A preferable heat treatment temperature is a film melting point of −60 ° C. or more and a film melting point or less. Moreover, in order to make the elongation at break within the above range, it is necessary to reduce the film defects after film formation as much as possible during film formation. In order to eliminate the drawbacks, it is important to provide a dust-proofing facility in a film forming atmosphere, maintenance of an extruder, maintenance of a drawing roll and a winding roll.

  It is also important to prevent polymer degradation during extrusion. In order to prevent deterioration of the polymer at the time of extrusion, it is necessary to optimize the extrusion temperature and the residence time of the polymer, purge the nitrogen in the extruder, remove the moisture of the polymer, and the like. A preferable extrusion temperature is the melting point of the polymer + 10 to 40 ° C. Moreover, although the suitable residence time of a polymer changes with polymers, it is preferable to shorten so that an unmelted material may not generate | occur | produce.

  Moreover, the method of making film thickness into 10 micrometers or more is also mentioned. If the film thickness is less than 10 μm, the stretch margin of the film is reduced and the breaking elongation is lowered. The film thickness is more preferably 15 μm or more and less than 250 μm, and most preferably 20 μm or more and less than 200 μm from the viewpoint of moldability and handleability.

  In addition, the polyester film of the present invention preferably has a heat shrinkage rate of 2% or less at 150 ° C. for 30 minutes in at least one direction from the viewpoint of dimensional stability. For example, when laminating with other materials or coating with a thick film in a processing step, dimensional stability is important for suppressing curling properties during laminating and coating. It is very effective that the heat shrinkage rate per minute is 2% or less. The method for setting the heat shrinkage rate at 150 ° C. for 30 minutes in at least one direction of the polyester film of the present invention in the above-described range is not particularly limited, but a method of constituting the film composition from a specific diol component can be mentioned. For example, 8 to 30 mol% is preferably 1,4-butanediol or 1,3-propanediol, and more preferably 10 to 30 mol% is 1,4-butanediol. Moreover, the method of making the whole polyester film 100 mass% and containing a crystal nucleating agent 0.1 mass% or more and less than 2 mass% is also used preferably. Furthermore, a method of increasing the heat treatment temperature of the film after biaxial stretching is effective. By performing the heat treatment at such a high temperature, distortion in the film is relieved, so that the thermal deformation rate can be lowered. A preferable heat treatment temperature is a film melting point of −60 ° C. or more and a film melting point or less. In addition, a method in which the film is relaxed in the longitudinal direction and / or the width direction during the heat treatment is also preferably used. By relaxing at the time of heat treatment, the residual strain in the film is released, so the thermal deformation rate is lowered. A preferable relaxation rate (relaxation rate) during heat treatment is 3% or more. A method of relaxing at a temperature lower than the heat treatment temperature after the high temperature heat treatment is also preferable.

  The polyester film of the present invention preferably has a crystal melting energy ΔHm of 5 to 35 J / g in terms of moldability, heat resistance, and dimensional stability. The crystal melting energy ΔHm referred to here is an endothermic peak calorie manifested by a melting phenomenon when measurement is performed at a temperature rising rate of 20 ° C./min using a differential scanning calorimeter (DSC). When polyester resins having different compositions are used in a blend and used as a polyester film, a plurality of endothermic peaks associated with melting may appear. In this case, the amount of heat of the endothermic peak appearing at the highest temperature is determined. The crystal melting energy of the film. A crystal melting energy ΔHm of less than 5 J / g is not preferable because the crystallinity is too low and the dimensional stability is poor. On the other hand, if the crystal melting energy ΔHm is larger than 35 J / g, the crystallinity is too high and the moldability is lowered, which is not preferable.

  Examples of the method for setting the crystal melting energy of the polyester film of the present invention to 5 to 35 J / g include a method in which the glycol component constituting the polyester film is composed of two or more glycol components. As a preferable configuration, 50 to 80 mol% of the glycol component is ethylene glycol, and 20 to 50 mol% is the other glycol component. More preferably, the other glycol component is a component selected from a 1,4-cyclohexanedimethanol component, a 1,4-butanediol component, and a 1,3-propanediol component. Most preferably, 50 to 80 mol% of the glycol component is an ethylene glycol component, 10 to 20 mol% is a 1,4-cyclohexanedimethanol component, and 10 to 30 mol% is 1,4-butanediol.

  Moreover, it is also preferable that the polyester film is composed of two or more kinds of dicarboxylic acid components from the viewpoint that the crystal melting energy is within the above range. In particular, it is preferably composed of terephthalic acid and isophthalic acid.

  In the polyester film of the present invention, the more preferable crystal melting energy ΔHm for achieving both heat resistance, dimensional stability and moldability is 10 to 30 J / g, and most preferably 15 to 25 J / g.

  In order to improve the appearance of the polyester film of the present invention, the haze of the film is preferably 0.1% or more and less than 3%. When the haze is 3% or more, the appearance of the film appears to be cloudy, and the appearance and design may be inferior. On the other hand, if the haze is less than 0.1%, the film slips poorly, handling becomes difficult, scratches are generated on the film surface, and wrinkles are easily generated when the film is wound into a roll shape. It may become. A more preferable range of haze is 0.2 to 2.5%, and 0.3 to 2% is particularly preferable.

As a method of making the haze 0.1% or more and less than 3%, at least a two-layer configuration of A layer / B layer, adding lubricant particles only to the A layer and the B layer, while maintaining the handleability of the film, A method of controlling optical properties is preferred. Moreover, when it is set as the 3 layer structure of A layer / B layer / C layer, it is preferable to add a particle only to A layer and C layer. In particular, when the layer thickness of the A layer is t _A (unit: μm), the equivalent circle diameter P (unit: μm) of the particles added to the A layer is 0.5 ≦ P / t _A ≦ 2. A method of adding 0.005 to 0.5 mass%, more preferably 0.01 to 0.2 mass% of satisfactory particles in the A layer is preferred. Here, although it does not specifically limit as a lubricant particle to be used, it is more preferable to use an external addition particle | grain rather than an internal precipitation particle | grain. Examples of the external additive particles include wet and dry silica, colloidal silica, aluminum silicate, titanium dioxide, calcium carbonate, calcium phosphate, barium sulfate, and aluminum oxide, and organic particles include styrene, silicone, acrylic acid, methacrylic acid, Particles containing polyesters, divinyl compounds and the like as constituent components can be used. Among them, it is preferable to use inorganic particles such as wet and dry silica and alumina, and particles containing styrene, silicone, acrylic acid, methacrylic acid, polyester, divinylbenzene and the like as constituent components. Furthermore, these externally added particles may be used in combination of two or more.

  From the viewpoint of economy and productivity, the polyester constituting the C layer is preferably polyester A. That is, it is preferable that the A layer and the C layer have the same composition. Furthermore, in order to improve economy and productivity, it is preferable to make the laminated thickness of the A layer and the C layer equal.

  Further, when the layer having the thickest layer is the main layer and the other layers are sublayers, the lamination ratio (layer thickness of the main layer) / (film thickness of the entire film) is preferably 0.999 or less. . When the lamination ratio is larger than 0.999, the thickness of the sub-layer is too thin, so that the film formation stability is inferior and uneven lamination may occur. The lamination ratio (main layer) / (whole film) is more preferably 0.99 or less, and most preferably 0.95 or less. The main layer is preferably a B layer.

  Said lamination thickness ratio can be achieved by adjusting the discharge amount when the polyester of each layer is extruded. The discharge amount can be appropriately adjusted depending on the number of rotations of the screw of the extruder, the number of rotations of the gear pump, the extrusion temperature, the viscosity of the polyester raw material, etc., when a gear pump is used.

  The film thickness and the film thickness ratio are obtained by observing the cross section of the film with a scanning electron microscope, a transmission electron microscope, an optical microscope, etc. at a magnification of 500 to 10,000 times to determine the thickness and the film ratio of each layer. Can do.

  In the case of a laminated configuration, in order to prevent delamination between layers after molding, the interlayer adhesion between the A layer and the B layer is preferably 5 N / 15 mm or more. If the interlayer adhesion between the A layer and the B layer is less than 5 N / 15 mm, peeling occurs at the interface between the A layer and the B layer after molding a polyester film or a molded member using the polyester film. There is a case. Further preferred interlayer adhesion is 8 N / 15 mm or more, most preferably 12 N / 15 mm or more.

  In order to make the interlaminar adhesion between the A layer and the B layer within the above range, the polyester constituting the A layer is polyester A, and the polyester constituting the B layer is polyester B. It is effective to resemble the composition of

  Next, although the specific manufacturing method of the polyester film of this invention is described, it is not limited to this. First, a polyester resin to be used is prepared. In the case of using a crystal nucleating agent as a crystallization accelerator, it is preferable to compound in advance in a polyester resin from the viewpoint of handleability and dispersibility. For example, drying is performed at 180 ° C. for 4 hours in a nitrogen atmosphere, a vacuum atmosphere, or the like, respectively, and the moisture content in the polyester is preferably 50 ppm or less. When two or more kinds of polyesters are mixed, they are weighed and mixed at a predetermined ratio and dried. Thereafter, it is supplied to an individual extruder and melt extruded. In addition, when performing melt extrusion using a vent type twin screw extruder, the resin drying step may be omitted. Next, foreign matter is removed and the amount of extrusion is leveled through a filter and a gear pump, respectively, and discharged from the T die onto a cooling drum in a sheet form. In the case of a laminated structure of two or more layers, for example, a feed block or a multi-manifold installed on the top of the T die is laminated to form an A / B type two-layer laminated film, and then the sheet is placed on the cooling drum from the T die To be discharged. In the case of forming an A / B / C type three-layer laminate and a film, polyester A, polyester B, and polyester C are supplied to individual extruders and melt extruded. If polyester A and polyester C have the same composition, a three-layer laminated film of A layer / B layer / A layer can be formed by a feed block or multi-manifold with two extruders. When discharging into a sheet on a cooling drum, for example, a method of applying static electricity using a wire electrode or a tape electrode, a casting method of providing a water film between a casting drum and an extruded polymer sheet, and a casting drum temperature The sheet polymer is brought into close contact with the casting drum by the method of adhering the extruded polymer from the glass transition point of the polyester resin to (glass transition point−20 ° C.) or by combining these methods, and then solidified by cooling. An unstretched film is obtained. Among these casting methods, when using polyester, a method of applying an electrostatic force is preferably used from the viewpoint of productivity and flatness. Although the polyester film of the present invention exhibits excellent characteristics even when used as an unstretched film, it is preferably biaxially stretched in terms of heat resistance and dimensional stability. As a method for stretching an unstretched film, the film is stretched in the longitudinal direction and then stretched in the width direction, or the film is stretched in the width direction and then stretched in the longitudinal direction, or the longitudinal direction and width of the film. Examples thereof include a simultaneous biaxial stretching method in which the directions are stretched almost simultaneously.

  As a draw ratio in such a drawing method, preferably 2.5 to 3.5 times, more preferably 2.8 to 3.5 times, and particularly preferably 3.0 to 3.4 times in each direction. Is done. The stretching speed is preferably 1,000 to 200,000% / min. The stretching temperature is preferably 80 to 130 ° C, more preferably 85 to 120 ° C in the longitudinal direction and 90 to 110 ° C in the width direction. Moreover, you may perform extending | stretching in multiple times with respect to each direction.

  Furthermore, the film is heat-treated after biaxial stretching. The heat treatment can be performed by any conventionally known method such as in an oven or on a heated roll. This heat treatment is performed at a temperature of 120 ° C. or higher and lower than or equal to the melting point of the polyester. The heat treatment time can be arbitrarily set within a range not deteriorating the characteristics, and is preferably 1 to 60 seconds, more preferably 1 to 30 seconds. Further, the heat treatment may be performed by relaxing the film in the longitudinal direction and / or the width direction. Furthermore, in order to improve the adhesive force with the ink print layer, the adhesive, and the vapor deposition layer, it is also preferable that at least one surface is subjected to corona treatment or a coating layer is provided.

  As a method of providing the coating layer in-line in the film manufacturing process, at least uniaxially stretched film with a coating layer composition dispersed in water is uniformly applied using a metalling ring bar or gravure roll. Then, a method of drying the coating while stretching is preferable, and in this case, the coating layer thickness is preferably 0.01 to 0.5 μm.

  Since the polyester film of the present invention is excellent in moldability, heat resistance and dimensional stability, it is preferably used for molding applications. When the polyester film of the present invention is used for molding applications, it can be molded into a complicated shape, so that a very excellent molded member can be obtained.

  Examples of such molding applications include in-mold molding applications and insert molding applications. The in-mold molding referred to here is a molding method in which a film itself is placed in a mold and molded into a desired shape with a resin pressure to be injected to obtain a molded decorative body. In insert molding, a film molded body to be installed in a mold is prepared by vacuum molding, vacuum / pressure forming, plug assist molding, etc., and a molded decorative body is obtained by filling the shape with resin. This is a molding method. Since a more complicated shape can be produced, the polyester film of the present invention is particularly preferably used for insert molding.

  When used for insert molding, an easy-adhesion layer may be provided on the resin side surface of the film in order to enhance the adhesion to the resin to be injection molded. As the resin for injection molding, polyester, polyamide, polycarbonate, ABS (acrylonitrile-butadiene-styrene), AS (acrylonitrile-styrene), polypropylene, polymethyl methacrylate, TPO (Thermo Plastic Olefin elastomer) or a mixed resin thereof is preferable. Since it is used, it is preferable that the adhesiveness with these resins is high. Such an easy-adhesion layer is not particularly limited, and examples thereof include polyester, urethane, acrylic, and polypropylene chloride resins.

  When the polyester film of the present invention is used for insert molding, the thickness is preferably 75 to 500 μm and more preferably 100 to 300 μm in terms of depth and shape retention of the molded body after molding. 150 to 250 μm is most preferable.

  The polyester film of the present invention can be used by being bonded to a molding substrate. By laminating with the molding substrate, a molding decorative sheet composed of the molding substrate / polyester film is obtained. Furthermore, when the weather resistance coating is given to the polyester film, it becomes the structure of the base material for shaping | molding / polyester film / weather resistance layer.

  Although it does not specifically limit as this base material for shaping | molding, A resin sheet, a metal plate, paper, wood, etc. are mentioned. Among these, a resin sheet is preferably used in terms of moldability, and a thermoplastic resin sheet is preferably used in terms of high moldability.

  Here, the thermoplastic resin sheet is not particularly limited as long as it is a polymer sheet that can be thermoformed. However, a polyester sheet, an acrylic sheet, an ABS (acrylonitrile-butadiene-styrene) sheet, a polystyrene sheet, an AS (AS) Preferably, an acrylic-styrene (TPN) sheet, a TPO (Thermo Plastic Olefin elastomer) sheet, a TPU (Thermo Plastic Urethane elastomer), or the like is preferably used. The thickness of the sheet is 50 μm to 2000 μm, more preferably 100 μm to 1800 μm, and still more preferably 250 to 1500 μm. When the polyester film is used by being bonded to a molding substrate, the thickness is preferably less than 10 to 75 μm, more preferably from 12 to 50 μm, more preferably from 15 to 40 μm in terms of bonding properties and handleability. Is most preferable.

  Moreover, in order to improve the adhesiveness with the base material for shaping | molding, it is preferable that the polyester film of this invention provides an adhesive layer. Although it does not specifically limit as a contact bonding layer, Polyester type, urethane type, an acrylic type, a chlorinated polypropylene type resin etc. are used preferably.

  Here, although the molding method of the decorative sheet for molding having the above-described configuration using the polyester film of the present invention will be specifically described, the molding method is not limited thereto.

  The polyester film of the present invention or the decorative sheet for molding is heated using a far-infrared heater at 150 to 400 ° C. so that the surface temperature becomes 50 to 230 ° C., the mold is pushed up, and vacuuming is performed. To form the desired shape. In the case of molding with a strict magnification, deeper molding is possible by applying pressure air to the sheet and molding. The decorative sheet for molding thus formed is trimmed to form a molded member. The molded member may be used as it is. However, in order to give strength as a molded product, the above-described resin or the like may be injected into a depressed portion by pressing a mold. In this way, the molded member is completed.

  When using the polyester film of this invention for an in-mold shaping | molding use and an insert molding use, since a molded member can show the outstanding external appearance by laminating | stacking a decoration layer on the film surface, it is preferable. The decorative layer referred to here is a layer for adding decoration such as coloring, unevenness, pattern, wood grain, metal tone, pearl tone and the like. Although it does not specifically limit as a formation method of a decoration layer, For example, it can form by metal vapor deposition, printing, a coating, a transfer, etc.

  Here, the metal used for metal deposition is not particularly limited, but indium (melting point: 156 ° C), tin (melting point: 228 ° C), aluminum (melting point: 660 ° C), silver (melting point: 961). ° C), copper (melting point: 1083 ° C), zinc (melting point: 420 ° C), nickel (melting point: 1453 ° C), chromium (1857 ° C), titanium (1725 ° C), platinum (melting point: 1772 ° C), palladium (melting point) : 1552 ° C) or an alloy thereof, but it is preferable to use a metal having a melting point of 150 to 400 ° C. It is preferable to use a metal having a melting point within the range because the polyester film can be molded in a temperature range and the deposited metal layer can be molded, and the occurrence of defects in the deposited layer due to molding can be easily suppressed. The melting point of a particularly preferable metal compound is 150 to 300 ° C. Although it does not specifically limit as a metal compound whose melting | fusing point is 150-400 degreeC, Indium (157 degreeC) and tin (232 degreeC) are preferable, and it is preferable to use indium especially at the point of metallic luster and a color tone. it can.

  Further, as a method for producing a vapor deposition film, a vacuum vapor deposition method, an EB vapor deposition method, a sputtering method, an ion plating method, or the like can be used. In order to further improve the adhesion between the polyester film and the vapor deposition layer, the surface of the film may be pretreated by a method such as a corona discharge treatment or an anchor coating agent. The thickness of the deposited film is preferably 1 to 500 nm, more preferably 5 to 300 nm. From the viewpoint of productivity, the thickness is preferably 10 to 200 nm.

  Moreover, the transfer foil use can also be mentioned preferably for shaping | molding. In general, the transfer foil is formed by sequentially laminating an easy adhesion layer, a release layer, a printing layer, an adhesive layer, and the like on one surface of a film that is a base material. As a transfer method of these transfer foils, a transfer device is used to transfer to a transfer object with a heating roll, or a so-called hot stamping method, or an adhesive layer is in contact with a mold resin of an injection molding machine or a blow molding machine. After setting the transfer material, injection molding or blowing of molding resin, transfer at the same time as molding, take out the molded product from the mold after cooling, generally known as so-called simultaneous molding transfer method represented by in-mold transfer It has been. When used as a transfer foil, the film thickness is preferably 50 to 200 μm, more preferably 60 to 150 μm from the viewpoint of moldability and heat resistance.

  Moreover, as a shaping | molding use, it can use preferably also as a shaping | molding protective film of a decorating sheet. In the case of molding as the above-described in-mold molding or insert molding, a protective film may be used from the viewpoint of reducing the glossiness of the decorative sheet surface and suppressing scratches, but moldability and surface gloss are required. Since the polyester film of the present invention is very excellent in surface properties and moldability during heating, it can exhibit very excellent characteristics as a molding protective film.

  The polyester film of the present invention has excellent moldability, and can easily form a molded part following the mold in thermoforming such as vacuum and pressure forming, so in-mold molding, insert molding, transfer foil, It is preferably used for molding applications such as molding protective films. For this reason, it is related with the polyester film used suitably for shaping | molding member uses, such as a building material, a motor vehicle part, a mobile phone, and an electrical appliance.

  Hereinafter, the present invention will be described in detail by way of examples. The characteristics were measured and evaluated by the following methods.

(1) Melting point, crystal melting energy Using a differential scanning calorimeter (Seiko Denshi Kogyo's RDC220), measurement and analysis were performed in accordance with JIS K7121-1987 and JIS K7122-1987.

  Using 5 mg of the polyester layer or polyester film as a sample, the temperature at the top of the endothermic peak obtained from the DSC curve when the temperature was raised from 25 ° C. to 300 ° C. at 20 ° C./min was defined as the melting point. The amount of heat per unit mass obtained from the endothermic peak area was defined as crystal melting energy. When the DSC curve is a straight line, the points that are separated from the baseline before and after the peak and the points that return to the baseline are connected by a straight line, and when the DSC curve is curved, the curved curve connects the two points. Went. When a plurality of endothermic peaks existed, the temperature at the apex of the endothermic peak on the highest temperature side was defined as the melting point, and the amount of heat per unit mass obtained from the endothermic peak area was defined as the crystal melting energy. Note that an endothermic peak with a very small peak area (0.5 J / g or less in terms of crystal melting energy) seen on the baseline was removed as noise.

(2) X-ray diffraction intensity Measured by the transmission method using an X-ray diffractometer under the following conditions, 2θ / θ scan (X-ray is incident at an angle of θ with respect to the film surface direction (sample horizontal direction)) The intensity data was obtained by detecting X-rays having an angle of 2θ with respect to the incident X-rays from the X-rays reflected from the sample and measuring the intensity change with respect to θ.

X-ray diffractometer: Spectris X'pert Pro MPD type (PW3040 / 60),
X-ray source: CuKα ray (using Ni filter),
Output: 45kV 40mA,
Goniometer: Spectris,
Slit: 0.1mmφ-1 ° -1 °,
Detector: Scintillation counter,
Count recording device: Spectris Co., Ltd. When X-rays are irradiated to the crystalline polymer surface at an incident angle θ, the parallel plane reflects the X-rays, and when the following Bragg equation is satisfied, strong diffraction occurs and the intensity peak Observed.

nλ = 2d _hkl Sinθ
n: Order, λ: X-ray wavelength, d _hkl : Interplanar spacing of crystal (hkl).

(3) Haze Film haze was measured using a haze meter (HGM-2GP manufactured by Suga Test Instruments Co., Ltd.) based on JIS K 7105 (1985). The measurement was performed at three arbitrary locations, and the average value was adopted.

(4) Film thickness, layer thickness The film was embedded in an epoxy resin, and the film cross section was cut out with a microtome. The cross section was observed with a transmission electron microscope (TEM H7100, manufactured by Hitachi, Ltd.) at a magnification of 5000 times to determine the film thickness and the thickness of each layer.

(5) Composition of polyester layer and polyester film Dissolve the polyester layer or film in hexafluoroisopropanol (HFIP) or a mixed solvent of HFIP and chloroform, and use ¹ H-NMR and ¹³ C-NMR to dicarboxylic acid component and glycol The components can be qualitative and the content can be quantified. In the case of a laminated film, it can be evaluated by scraping each layer of the film according to the laminated thickness. In addition, about the film of this invention, the composition was computed by calculation from the mixing ratio of the polyester resin at the time of film manufacture.

(6) Plane orientation coefficient Using sodium D line (wavelength 589 nm) as a light source and using an Abbe refractometer, the refractive index (n _MD ) in the longitudinal direction of the film, the refractive index (n _TD ) in the width direction, and the refractive index in the thickness direction The ratio (n _ZD ) was measured, and the plane orientation coefficient (fn) was calculated from the following formula.
fn = ( _nMD + _nTD ) / 2- _nZD .

(7) Breaking elongation at 150 ° C. The film was cut into a rectangle having a length of 150 mm × width of 10 mm in the longitudinal direction and the width direction as a sample. Using a tensile tester (Orientec Tensilon UCT-100), the tensile test was performed in the longitudinal direction and the width direction of the film at an initial tensile chuck distance of 20 mm and a tensile speed of 500 mm / min. For the measurement, a film sample was set in a constant temperature layer set in advance at 150 ° C., and a tensile test was performed after preheating for 60 seconds. The elongation when the film broke was defined as the breaking elongation. In addition, the measurement was performed 5 times for each sample and 10 arbitrary directions, and the highest value among the average values in each direction was adopted.

(8) Thermal contraction rate at 150 ° C. for 30 minutes The film was cut into a rectangular shape having a length of 150 mm and a width of 10 mm in an arbitrary direction to obtain a sample. Marks were drawn on the sample at intervals of 100 mm, and a heat treatment was performed by placing in a hot air oven heated to 150 ° C. with a 3 g weight suspended for 30 minutes. The distance between the marked lines after the heat treatment was measured, and the thermal shrinkage rate was calculated from the change in the distance between the marked lines before and after heating, and used as an index of dimensional stability. The measurement was carried out three times each in 10 arbitrary directions, and the smallest value among the average values in each direction was adopted.

(9) Formability To the polyester film of the present invention, an adhesive prepared by mixing Toyo Morton Co., Ltd. adhesive AD503, curing agent CAT10, and ethyl acetate at a ratio of 20: 1: 20 was applied as an adhesive layer. An ABS sheet having a thickness of 1500 μm was bonded to the adhesive layer, and heat-pressed (80 ° C., 0.1 MPa, 3 m / min) using a laminator to prepare a decorative sheet for molding. The decorative sheet for molding is heated using a far-infrared heater at 400 ° C. so that the surface temperature becomes 150 ° C., and vacuum forming is performed along a mold (bottom diameter 50 mm) heated to 70 ° C. went. The state of being molded along the mold was evaluated according to the following criteria using the molding degree (drawing ratio: molding height / bottom diameter).
S: Molding was possible with a drawing ratio of 0.7 or more.
A: Molding was possible with a drawing ratio of 0.6 to less than 0.7.
B: Molding was possible with a drawing ratio of 0.5 to less than 0.6.
C: Low followability and could not be formed into a shape with a drawing ratio of 0.5.

(10) Heat resistance About the molded object sample after vacuum forming by the method of (9), it evaluated on the following reference | standard.
S: No roughness was observed on the film surface after molding, and the absolute value of the difference in glossiness between the films before and after molding was less than 3.
A: Roughness was not observed on the film surface after molding, and the absolute value of the difference in glossiness between the films before and after molding was 3 to less than 5.
B: Roughness was observed on the film surface after molding, and the absolute value of the difference in glossiness between the films before and after molding was less than 5.
C: Roughness was observed on the film surface after molding, and the absolute value of the difference in glossiness between the films before and after molding was 5 or more.

In addition, glossiness shall be measured based on the following method.
With respect to the surface of the molded article, 60 ° specular gloss was measured using a digital variable angle gloss meter UGV-5D manufactured by Suga Test Instruments Co., Ltd. according to the method defined in JIS-Z-8741 (1997). Measurement was performed at n = 5, and an average value excluding the maximum value and the minimum value was adopted as the glossiness.

(11) Dimensional stability The film was affixed to a 20 cm × 30 cm metal frame with a double-sided tape and heat treated at 80 ° C. for 120 minutes in a hot air oven. The state of the film after the heat treatment was evaluated according to the following criteria.
S: No change was observed in the film before and after the heat treatment.
A: A part of the film was loosened after the heat treatment, but the surface property was not changed.
B: After the heat treatment, some of the film was loosened, and the surface property was slightly lowered.
C: After the heat treatment, the film was loosened and the surface property was lost.

(12) Transparency The haze measured in (3) was evaluated according to the following criteria.
S: Haze was 0.1% or more and less than 2%.
A: The haze was 2% or more and less than 2.5%.
B: The haze was 2.5% or more and less than 3%.
C: The haze was 3% or more.

(Manufacture of polyester)
The polyester resin used for film formation was prepared as follows.

(Polyester A)
0.04 parts by mass of manganese acetate is added to a mixture of 100 parts by mass of dimethyl terephthalate and 70 parts by mass of ethylene glycol, the temperature is gradually raised, and finally transesterification is performed while distilling methanol at 220 ° C. It was. Next, 0.025 parts by mass of 85% phosphoric acid aqueous solution and 0.02 parts by mass of germanium dioxide were added, and a polycondensation reaction was performed at 290 ° C. under a reduced pressure of 1 hPa, the intrinsic viscosity was 0.65, and by-produced diethylene glycol 2 A mol% copolymerized polyethylene terephthalate resin was obtained.

(Polyester B)
A mixture of 100 parts by mass of terephthalic acid and 110 parts by mass of 1,4-butanediol was heated to 140 ° C. under a nitrogen atmosphere to obtain a homogeneous solution, and then 0.054 parts by mass of tetra-n-butyl orthotitanate. Then, 0.054 parts by mass of monohydroxybutyltin oxide was added to carry out an esterification reaction. Next, 0.066 parts by mass of tetra-n-butyl orthotitanate was added and a polycondensation reaction was performed under reduced pressure to prepare a polybutylene terephthalate resin having an intrinsic viscosity of 0.88. Thereafter, crystallization was performed at 140 ° C. in a nitrogen atmosphere, followed by solid phase polymerization at 200 ° C. for 6 hours in a nitrogen atmosphere to obtain a polybutylene terephthalate resin having an intrinsic viscosity of 1.22.

(Polyester C)
Copolymerized polyester in which 33 mol% of 1,4-cyclohexanedimethanol was copolymerized (Eastster PETG6763 manufactured by Eastman Chemical Co., Ltd.) and PET were mixed at a mass ratio of 90:10, and 280 using a vent type twin screw extruder. The resulting mixture was kneaded at 0 ° C. to obtain 30 mol% of 1,4-cyclohexanedimethanol copolymerized polyethylene terephthalate resin in which 2 mol% of by-produced diethylene glycol was copolymerized.

(Particle Master)
0.04 parts by mass of manganese acetate is added to a mixture of 100 parts by mass of dimethyl terephthalate and 70 parts by mass of ethylene glycol, the temperature is gradually raised, and finally transesterification is performed while distilling methanol at 220 ° C. It was. Subsequently, 0.025 mass part of 85% phosphoric acid aqueous solution and 0.02 mass part of germanium dioxide were added. Furthermore, an ethylene glycol slurry of wet silica agglomerated particles having a number average particle size of 1.2 μm was added so that the particle concentration was 2% by mass, and a polycondensation reaction was performed at 290 ° C. under a reduced pressure of 1 hPa. 0.65, a polyethylene terephthalate particle master copolymerized with 2 mol% of diethylene glycol as a by-product was obtained.

(Nuclear Agent Master A)
Polyester A prepared as described above and barium stearate are mixed at a mass ratio of 90:10, and kneaded at 280 ° C. using a vented twin screw extruder to obtain 10% by weight of master pellets of barium stearate. Obtained.

(Nuclear agent master B)
Polyester A prepared as described above and ethylene bislauric acid amide are mixed at a mass ratio of 90:10, and kneaded at 270 ° C. using a vented twin screw extruder, and 10% by mass of ethylene bislauric acid amide. Of master pellets were obtained.

(Nuclear Agent Master C)
Polyester A prepared as described above and sodium montanate are mixed at a mass ratio of 90:10, and kneaded at 270 ° C. using a vent type twin screw extruder, to obtain a master pellet of sodium montanate 10% by mass. Obtained.

(Nuclear Agent Master D)
0.04 parts by mass of manganese acetate is added to a mixture of 100 parts by mass of dimethyl terephthalate and 70 parts by mass of ethylene glycol, the temperature is gradually raised, and finally transesterification is performed while distilling methanol at 220 ° C. It was. Next, 0.025 parts by mass of 85% phosphoric acid aqueous solution and 0.02 parts by mass of germanium dioxide were added, and 10 parts by mass of sodium acetate was further added, and a polycondensation reaction was carried out under reduced pressure at 290 ° C. and 1 hPa to obtain intrinsic viscosity. Of polyethylene terephthalate resin of 10% by mass of sodium acetate copolymerized by 2 mol% of diethylene glycol as a by-product of 0.65.

(Nuclear Agent Master E)
Polyester A prepared as described above and 2,4-di (P-methylbenzylidene) sorbitol are mixed at a mass ratio of 90:10 and kneaded at 270 ° C. using a vented twin screw extruder. , 4-Di (P-methylbenzylidene) sorbitol 10% by mass master pellets were obtained.

(Nuclear Agent Master F)
Polyester B prepared as described above and barium stearate are mixed at a mass ratio of 90:10, and are kneaded at 270 ° C. using a vented twin screw extruder to obtain 10% by weight of master pellets of barium stearate. Obtained.

Example 1
A three-layer laminated film of A layer / B layer / A layer was obtained. The composition of layer A was used by mixing polyester A, polyester B, polyester C, nucleating agent master A and particle master in a mass ratio of 27: 20: 50: 2: 1. The composition of layer B was used by mixing polyester A, polyester B, polyester C, and nucleating agent master A in a mass ratio of 28: 20: 50: 2.

  Each mixed polyester resin was individually dried in a vacuum dryer at 180 ° C. for 4 hours, and after sufficiently removing moisture, supplied to separate single screw extruders, melted at 280 ° C., and filtered through separate paths. After removing the foreign matter and leveling the amount of extrusion through the gear pump, A layer / B layer / A layer (see the table for lamination thickness ratio) in the feed block installed on the top of the T die After the lamination, the sheet was discharged from a T die onto a cooling drum whose temperature was controlled at 25 ° C. At that time, a wire-like electrode having a diameter of 0.1 mm was applied electrostatically and adhered to the cooling drum to obtain an unstretched film.

  Next, before stretching in the longitudinal direction, the film temperature was raised with a heated roll, finally stretched 3.3 times in the longitudinal direction at a film temperature of 95 ° C., and immediately cooled with a metal roll whose temperature was controlled at 40 ° C. . Next, the film was stretched 3.3 times in the width direction at a preheating temperature of 85 ° C. and a stretching temperature of 100 ° C. with a tenter type horizontal stretching machine, and the temperature was maintained at 205 ° C. for 5 seconds while relaxing in the width direction by 3%. Heat treatment was performed to obtain a biaxially oriented polyester film having a film thickness of 50 μm.

(Example 2)
It was set as the single layer film. The composition of layer B was used by mixing polyester A, polyester B, polyester C, nucleating agent master A and particle master in a mass ratio of 28: 20: 50: 2: 1.

  Each mixed polyester resin is individually dried in a vacuum dryer at 180 ° C for 4 hours, and after sufficiently removing moisture, it is supplied to a single screw extruder, melted at 280 ° C, passed through a filter, removed foreign matter, extruded After the amount was leveled, the sheet was discharged from a T-die onto a cooling drum whose temperature was controlled at 25 ° C. At that time, a wire-like electrode having a diameter of 0.1 mm was applied electrostatically and adhered to the cooling drum to obtain an unstretched film.

  Next, before stretching in the longitudinal direction, the film temperature was raised with a heated roll, finally stretched 3.3 times in the longitudinal direction at a film temperature of 95 ° C., and immediately cooled with a metal roll whose temperature was controlled at 40 ° C. . Next, the film was stretched 3.3 times in the width direction at a preheating temperature of 85 ° C. and a stretching temperature of 100 ° C. with a tenter type horizontal stretching machine, and the temperature was maintained at 205 ° C. for 5 seconds while relaxing in the width direction by 3%. Heat treatment was performed to obtain a biaxially oriented polyester film having a film thickness of 50 μm.

Example 3
A biaxially oriented polyester film having a film thickness of 50 μm was obtained in the same manner as in Example 1 except that the heat treatment temperature was 220 ° C.

Example 4
A biaxially oriented polyester film having a film thickness of 50 μm was obtained in the same manner as in Example 1 except that the draw ratio in the longitudinal direction was 3.5 times and the draw ratio in the width direction was 3.5 times.

(Example 5)
A three-layer laminated film of A layer / B layer / A layer was obtained. The composition of layer A was used by mixing polyester A, polyester B, polyester C, nucleating agent master B and particle master in a mass ratio of 27: 20: 50: 2: 1. The composition of layer B was used by mixing polyester A, polyester B, polyester C and nucleating agent master B in a mass ratio of 28: 20: 50: 2.

  Thereafter, a biaxially oriented polyester film having a film thickness of 50 μm was obtained in the same manner as in Example 1.

(Example 6)
A three-layer laminated film of A layer / B layer / A layer was obtained. The composition of layer A was used by mixing polyester A, polyester B, polyester C, nucleating agent master C and particle master in a mass ratio of 27: 20: 50: 2: 1. The composition of layer B was used by mixing polyester A, polyester B, polyester C, and nucleating agent master C in a mass ratio of 28: 20: 50: 2.

  Thereafter, a biaxially oriented polyester film having a film thickness of 50 μm was obtained in the same manner as in Example 1.

(Example 7)
A three-layer laminated film of A layer / B layer / A layer was obtained. The composition of layer A was used by mixing polyester A, polyester B, polyester C, nucleating agent master D and particle master in a mass ratio of 27: 20: 50: 2: 1. The composition of layer B was used by mixing polyester A, polyester B, polyester C, and nucleating agent master D in a mass ratio of 28: 20: 50: 2.

  Thereafter, a biaxially oriented polyester film having a film thickness of 50 μm was obtained in the same manner as in Example 1.

(Example 8)
A three-layer laminated film of A layer / B layer / A layer was obtained. The composition of layer A was used by mixing polyester A, polyester B, polyester C, nucleating agent master E and particle master in a mass ratio of 27: 20: 50: 2: 1. The composition of layer B was used by mixing polyester A, polyester B, polyester C and nucleating agent master E in a mass ratio of 28: 20: 50: 2.

  Thereafter, a biaxially oriented polyester film having a film thickness of 50 μm was obtained in the same manner as in Example 1.

Example 9
A three-layer laminated film of A layer / B layer / A layer was obtained. The composition of layer A was used by mixing polyester A, polyester B, polyester C, nucleating agent master A and particle master in a mass ratio of 32: 20: 45: 2: 1. The composition of layer B was used by mixing polyester A, polyester B, polyester C, and nucleating agent master A in a mass ratio of 33: 20: 45: 2.

  Thereafter, a biaxially oriented polyester film having a film thickness of 50 μm was obtained in the same manner as in Example 1.

(Example 10)
A three-layer laminated film of A layer / B layer / A layer was obtained. The composition of layer A was used by mixing polyester A, polyester B, polyester C, nucleating agent master A and particle master in a mass ratio of 37: 20: 40: 2: 1. The composition of layer B was used by mixing polyester A, polyester B, polyester C and nucleating agent master A in a mass ratio of 38: 20: 40: 2.

  Thereafter, a biaxially oriented polyester film having a film thickness of 50 μm was obtained in the same manner as in Example 1.

(Example 11)
A three-layer laminated film of A layer / B layer / A layer was obtained. The composition of layer A was used by mixing polyester A, polyester B, polyester C, nucleating agent master A and particle master in a mass ratio of 42: 20: 35: 2: 1. The composition of layer B was used by mixing polyester A, polyester B, polyester C, and nucleating agent master A in a mass ratio of 43: 20: 35: 2.

  Thereafter, a biaxially oriented polyester film having a film thickness of 50 μm was obtained in the same manner as in Example 1.

Example 12
A three-layer laminated film of A layer / B layer / A layer was obtained. The composition of layer A was used by mixing polyester A, polyester B, polyester C, nucleating agent master A and particle master in a mass ratio of 22: 20: 55: 2: 1. The composition of layer B was used by mixing polyester A, polyester B, polyester C and nucleating agent master A in a mass ratio of 23: 20: 55: 2.

  Thereafter, a biaxially oriented polyester film having a film thickness of 50 μm was obtained in the same manner as in Example 1.

(Example 13)
A three-layer laminated film of A layer / B layer / A layer was obtained. The composition of layer A was used by mixing polyester A, polyester B, polyester C, nucleating agent master A and particle master in a mass ratio of 17: 20: 60: 2: 1. The composition of layer B was used by mixing polyester A, polyester B, polyester C, and nucleating agent master A in a mass ratio of 18: 20: 60: 2.

  Thereafter, a biaxially oriented polyester film having a film thickness of 50 μm was obtained in the same manner as in Example 1.

(Example 14)
A three-layer laminated film of A layer / B layer / A layer was obtained. The composition of layer A was used by mixing polyester A, polyester B, polyester C, nucleating agent master A, and particle master in a mass ratio of 12: 20: 65: 2: 1. The composition of layer B was used by mixing polyester A, polyester B, polyester C and nucleating agent master A in a mass ratio of 13: 20: 65: 2.

  Thereafter, a biaxially oriented polyester film having a film thickness of 50 μm was obtained in the same manner as in Example 1.

(Example 15)
A three-layer laminated film of A layer / B layer / A layer was obtained. The composition of layer A was used by mixing polyester A, polyester B, polyester C, nucleating agent master A and particle master in a mass ratio of 24: 20: 50: 5: 1. The composition of layer B was used by mixing polyester A, polyester B, polyester C, and nucleating agent master A in a mass ratio of 25: 20: 50: 5.

  Thereafter, a biaxially oriented polyester film having a film thickness of 50 μm was obtained in the same manner as in Example 1.

(Example 16)
A two-layer laminated film of A layer / B layer was obtained. The composition of layer A was used by mixing polyester A, polyester B, polyester C, nucleating agent master A and particle master in a mass ratio of 22: 20: 50: 8: 1. The composition of layer B was used by mixing polyester A, polyester B, polyester C and nucleating agent master A in a mass ratio of 22: 20: 50: 8.
Thereafter, a biaxially oriented polyester film having a film thickness of 50 μm was obtained in the same manner as in Example 1.

(Example 17)
A three-layer laminated film of A layer / B layer / A layer was obtained. The composition of layer A was used by mixing polyester A, polyester B, polyester C, nucleating agent master A and particle master in a mass ratio of 17: 20: 50: 12: 1. The composition of layer B was used by mixing polyester A, polyester B, polyester C and nucleating agent master A in a mass ratio of 18: 20: 50: 12.

  Thereafter, in the same manner as in Example 1, a biaxially oriented polyester film having a film thickness of 38 μm was obtained.

(Example 18)
A three-layer laminated film of A layer / B layer / A layer was obtained. The composition of layer A was used by mixing polyester A, polyester B, polyester C and particle master in a mass ratio of 29: 20: 50: 1. The composition of layer B was used by mixing polyester A, polyester B and polyester C in a mass ratio of 30:20:50.

  Thereafter, a biaxially oriented polyester film having a film thickness of 50 μm was obtained in the same manner as in Example 1.

(Example 19)
A three-layer laminated film of A layer / B layer / A layer was obtained. The composition of layer A was used by mixing polyester A, polyester B, polyester C and particle master in a mass ratio of 34: 15: 50: 1. The composition of layer B was used by mixing polyester A, polyester B and polyester C in a mass ratio of 35:15:50.

  Thereafter, a biaxially oriented polyester film having a film thickness of 75 μm was obtained in the same manner as in Example 1.

(Example 20)
A three-layer laminated film of A layer / B layer / A layer was obtained. The composition of layer A was used by mixing polyester A, polyester B, polyester C and particle master in a mass ratio of 39: 10: 50: 1. The composition of layer B was used by mixing polyester A, polyester B and polyester C in a mass ratio of 40:10:50.

  Thereafter, a biaxially oriented polyester film having a film thickness of 75 μm was obtained in the same manner as in Example 1.

(Example 21)
A three-layer laminated film of A layer / B layer / A layer was obtained. The composition of layer A was used by mixing polyester A, polyester B, polyester C and particle master in a mass ratio of 44: 5: 50: 1. The composition of layer B was used by mixing polyester A, polyester B and polyester C in a mass ratio of 45: 5: 50.

  Thereafter, a biaxially oriented polyester film having a film thickness of 25 μm was obtained in the same manner as in Example 1.

(Comparative Example 1)
A three-layer laminated film of A layer / B layer / A layer was obtained. The composition of layer A was used by mixing polyester A, polyester B, polyester C, nucleating agent master C and particle master in a mass ratio of 47: 20: 30: 2: 1. The composition of layer B was used by mixing polyester A, polyester B, polyester C and nucleating agent master C in a mass ratio of 48: 20: 30: 2.

  Thereafter, a biaxially oriented polyester film having a film thickness of 50 μm was obtained in the same manner as in Example 1.

(Comparative Example 2)
A three-layer laminated film of A layer / B layer / A layer was obtained. The composition of layer A was used by mixing polyester A, polyester B, polyester C, nucleating agent master A and particle master in a mass ratio of 7: 20: 70: 2: 1. The composition of layer B was used by mixing polyester A, polyester B, polyester C, and nucleating agent master A in a mass ratio of 8: 20: 70: 2.

  Thereafter, a biaxially oriented polyester film having a film thickness of 50 μm was obtained in the same manner as in Example 1.

(Comparative Example 3)
A three-layer laminated film of A layer / B layer / A layer was obtained. The composition of layer A was used by mixing polyester A, polyester C and particle master in a mass ratio of 29: 70: 1. The composition of layer B was used by mixing polyester A and polyester C in a mass ratio of 30:70.

  Thereafter, a biaxially oriented polyester film having a film thickness of 25 μm was obtained in the same manner as in Example 1.

(Comparative Example 4)
A three-layer laminated film of A layer / B layer / A layer was obtained. The composition of layer A was used by mixing polyester A, polyester B, polyester C, nucleating agent master A and particle master in a mass ratio of 9: 20: 50: 20: 1. The composition of layer B was used by mixing polyester A, polyester B, polyester C and nucleating agent master A in a mass ratio of 10: 20: 50: 20.

  Thereafter, in the same manner as in Example 1, a biaxially oriented polyester film having a film thickness of 38 μm was obtained.

(Comparative Example 5)
A three-layer laminated film of A layer / B layer / A layer was obtained. The composition of layer A was used by mixing polyester C, nucleating agent master F and particle master in a mass ratio of 79: 20: 1. The composition of layer B was used by mixing polyester C and nucleating agent master F at a mass ratio of 80:20.

  Thereafter, a biaxially oriented polyester film having a film thickness of 50 μm was obtained in the same manner as in Example 1.

(Comparative Example 6)
A three-layer laminated film of A layer / B layer / A layer was obtained. The composition of layer A was used by mixing polyester A, polyester B, polyester C, nucleating agent master A, and particle master in a mass ratio of 29: 20: 30: 20: 1. The composition of the B layer was used by mixing polyester A, polyester B, polyester C, and nucleating agent master A in a mass ratio of 30: 20: 30: 20.

  Thereafter, a biaxially oriented polyester film having a film thickness of 50 μm was obtained in the same manner as in Example 1.

(Comparative Example 7)
A three-layer laminated film of A layer / B layer / A layer was obtained. The composition of layer A was used by mixing polyester A, polyester C and particle master in a mass ratio of 69: 30: 1. The composition of layer B was used by mixing polyester A and polyester C in a mass ratio of 70:30.

  Thereafter, a biaxially oriented polyester film having a film thickness of 25 μm was obtained in the same manner as in Example 1.

(Comparative Example 8)
A three-layer laminated film of A layer / B layer / A layer was obtained. The composition of layer A was used by mixing polyester A, polyester C and particle master in a mass ratio of 19: 80: 1. The composition of layer B was used by mixing polyester A and polyester C in a mass ratio of 20:80.

  Thereafter, a biaxially oriented polyester film having a film thickness of 50 μm was obtained in the same manner as in Example 1.

The abbreviations in the table are as follows.
EG: ethylene glycol component DEG: diethylene glycol component BD: 1,4-butanediol component CHDM: 1,4-cyclohexanedimethanol component TPA: terephthalic acid residue component.

  The present invention relates to a polyester film, and is particularly excellent in moldability, so that it can be suitably used for molding materials such as building materials, automobile parts, mobile phones, and electrical products.

Claims (7)

A polyester film characterized in that the peak intensity ratio determined by X-ray diffraction intensity measurement (transmission method) satisfies the expressions (1) and (2).
0.4 <Ib / Ia ≦ 1.2 (1)
0.4 <Ic / Ib ≦ 1.2 (2)
Ia: peak intensity near 2θ = 26 ° Ib: peak intensity near 2θ = 23.5 ° Ic: peak intensity near 2θ = 22.5 ° where the peak intensity is 2θ / θ scan measurement (X-rays on the film surface) The incident angle is θ with respect to the direction (horizontal direction of the sample), and X-rays reflected from the sample are detected at an angle of 2θ with respect to the incident X-ray, and the intensity change with respect to θ is measured) It is what I have sought. 2. The polyester film according to claim 1, wherein the polyester film has a heat shrinkage rate of −2% or more and 2% or less at 150 ° C. in 30 minutes and a breaking elongation at 150 ° C. of 300% or more and 700% or less. Polyester film. The polyester film according to claim 1 or 2, wherein 10 to 30 mol% of the glycol component constituting the polyester film is 1,4-butanediol. The polyester film according to any one of claims 1 to 3, wherein 10 to 20 mol% of the glycol component constituting the polyester film is a 1,4-cyclohexanedimethanol component. The polyester film according to any one of claims 1 to 4, wherein the polyester film contains a crystal nucleating agent in an amount of 0.1 to 2% by mass. The plane orientation coefficient is 0.04 or more and 0.1 or less, The polyester film according to any one of claims 1 to 5. The polyester film according to claim 1, wherein the polyester film has a haze of 0.1% or more and less than 3%.

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