JPH068382B2 - Polyethylene terephthalate film - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a polyethylene terephthalate film having few surface foreign matter defects and good transparency.

[Conventional technology and problems of the technology] Polyethylene terephthalate film is used today for metal vapor deposition or sputter film, electrophotographic / photosensitive material film, magnetic tape or disk film, release film,
Used in capacitors and films. These applications are subject to processing that is exposed to dry heat and high temperature, specifically about 160 to 200 ° C., for example, when exposed to 160 ° C. for 1 hour, oligomers will precipitate and adhere to the surface layer of the film, resulting in dry heat processing. Surface foreign matter becomes a defect. The surface foreign matter is
For example, magnetic tapes and magnetic disks cause dropouts, capacitors cause poor withstand voltage, and optical ones cause poor photosensitivity and opacity, both of which are product defects.

On the other hand, as a technique for controlling the amount of this oligomer, Japanese Patent Publication No.
No. 8-2410 and Japanese Patent Laid-Open No. 58-121128 are known, but they only mention surface layer oligomers and magnetic recording medium characteristics, and there is a problem that transparency is not combined.

[Means for Solving Problems] In the present invention, polyethylene terephthalate contains 0.11 to 0.5% by weight of a higher fatty acid ester composed of a higher aliphatic monocarboxylic acid and a monovalent or divalent alcohol. Stretched film and 160 to 200 ° C
The surface layer oligomer amount Mt (μg / cm ² ) of the film heat-treated at an arbitrary temperature T (° C.) for 1 hour, and the temperature T
The polyethylene terephthalate film is characterized by having the following relationship with the haze (value converted into a film thickness of 15 μ) Ht (%) of the film heat-treated at (° C.) for 1 hour.

Mt ≦ 0.8 (1) Mt / Ht <0.1 (2) The polyethylene terephthalate in the present invention is obtained by polycondensing terephthalic acid and ethylene glycol. In this case, isophthalic acid, phthalic acid, 2,6-naphthalenedicarboxylic acid, anthracene dicarboxylic acid, α,
Aromatic dicarboxylic acids other than terephthalic acid such as β-bis (2-chlorophenoxy) ethane-4,4′dicarboxylic acid, or alkylene glycols other than ethylene glycol such as diethylene glycol, trimethylene glycol, tetramethylene glycol and hexamethylene glycol. Can be used together in a small amount, and they can be used as a copolymerization component. In the polycondensation, an esterification or polymerization catalyst such as calcium acetate, alkyl titanate or antimony trioxide can be used. In the polycondensation, water, alcohol or the like is distilled out under normal pressure or high vacuum to allow the reaction to proceed. . The polyethylene terephthalate thus obtained has an intrinsic viscosity I.V. V. The (measured in an orthochlorophenol solution at 25 ° C.) is preferably 0.5 to 0.8. In the following polyethylene terephthalate, of course, known additives such as antistatic agents,
A heat stabilizer, an ultraviolet absorber or the like may be contained within a range that does not impair the effects of the present invention, and well-known internal particles (metal compounds added during the synthesis of polyethylene, such as calcium compounds, magnesium compounds and lithium compounds). , Phosphorus compounds bound to polyethylene terephthalate to form precipitates) and inert particles (I Periodic Table I)
Chemically inert ones selected from oxides or inorganic salts of group I, III, IV elements, such as silica, aluminum silicate, barium sulfate, titanium dioxide, molybdenum disulfide, mica, aluminum oxide, carbonic acid. calcium)
Alternatively, polyethylene may contain inactive organic particles (for example, fluorine-containing fine particles or crosslinked polymer) within a range that does not impair the effects of the present invention.

The higher aliphatic monocarboxylic acid and the higher fatty acid ester composed of a monovalent or divalent alcohol in the present invention have a carbon number of 10 to 33, preferably 18 to 33, more preferably 20 to 32. Chain and branched higher aliphatic monocarboxylic acids, such as capric acid, lauric acid, stearic acid, nonadecanoic acid, arachidic acid, behenic acid, melissic acid, lignoceric acid, cerotic acid, montanic acid, pentriacontanoic acid, petroselinic acid, Obtained by partially or wholly esterifying oleic acid, erucic acid, linoleic acid and an acid mixture containing them with a monovalent or divalent linear or branched alcohol having 2 to 33 carbon atoms. It is a thing. Specifically, montanic acid ethylene glycol ester, montanic acid ethyl ester, montanic acid ceryl, octanosyl lignoceric acid, melicyl lignoceric acid, ceryl lignoceric acid, myricyl serotiate, ceryl acid ceryl and mixtures thereof, and the like, naturally. The resulting montan wax, carnauba wax, beeswax,
Candelilla wax, nuka wax, and squid wax are also preferably used. However, an ester salt, that is, a metal salt of an ester, such as sodium montanate ester salt, is not desirable because it is difficult to satisfy both the absence of surface foreign matter and good transparency.

Those in which the number of carbon atoms of the monocarboxylic acid component and the alcohol component constituting the above higher fatty acid ester are in the range other than the above range are not desirable from the viewpoint of achieving both the defect-free surface foreign matter of the film and the good transparency. . Further, a higher fatty acid ester having a melting point of 135 ° C. or higher is not preferable from the viewpoint of achieving both surface foreign matter and good transparency.

In the present invention, the content of higher fatty acid ester is 0.1
It should be 1 to 0.5% by weight, preferably 0.15 to 0.4% by weight. Less than 0.11% by weight or 0.
If it exceeds 5% by weight, at least one of the defects of the surface foreign matter of the film and the defect of the transparency appears.

In the present invention, a film heat-treated at an arbitrary temperature T (° C.) in the range of 160 to 200 ° C. for 1 hour has an oligomer amount Mt attached to the surface layer of the film of 0.8 μg / cm ² or less. Need to be 0.8 μg / c
If it exceeds m ² , surface foreign matter defects or opacity will appear.
The amount of oligomer Mt is preferably 0.7 μg / cm ² or less,
More preferably, it is 0.6 μg / cm ² or less.

In the present invention, the ratio Mt / Ht between the surface layer oligomer amount Mt and the haze Ht of the film treated at the temperature T (° C.) for 1 hour and converted to a thickness of 1.5 μ is less than 0.1. There must be. When this ratio is 0.1 or more, both the absence of surface foreign matter defects and the good transparency are incompatible.

The film in the present invention may be either a well-known uniaxially oriented film or a biaxially oriented film, and the uniaxially oriented film has good anisotropy and thus is desirable for polarizing applications. Ideal for tape and condenser applications. The biaxially oriented film can be obtained by simultaneous biaxial stretching or sequential biaxial stretching.
It is important to select the conditions so that t and Mt / Ht are within the specified range. In the case of sequential biaxial stretching, 70 to 70 in the machine direction.
Stretched 3 to 5 times at 120 ° C, then 90 to 140 in transverse direction
It can be obtained by a method of stretching at a temperature of 3 to 5 times at 160C and heat setting at 160 to 240C for several seconds to tens of seconds. A well-known tensilized film is also desirable as the film of the present invention. The thickness of the film is not particularly limited, but is 2 to 90.
μ is desirable.

[Operation, Effect, Use] As described above, the present invention provides a polyethylene terephthalate film comprising: A. Higher fatty acid ester content, and B. The amount of the oligomer Mt and the ratio of the amount Mt of the oligomer and the film haze Ht are each within a specific range, and when either of the above A and B terms is not satisfied, the effect of the present invention, that is, surface foreign matter There is no defect and the effect of good transparency does not appear. In some cases, even if the condition A is satisfied, the condition B may not be satisfied. Therefore, generally, if the specified amount of the higher fatty acid ester is contained, the effect is not obtained, but if the higher fatty acid ester is not contained at all, Since the B term is not always satisfied, the higher fatty acid ester has mutual interaction with polyethylene terephthalate,
It is presumed that it has effects of reducing oligomers and suppressing haze increase.

The present invention exerts the excellent effects that the surface foreign matter defects are small and the transparency is good by the above-mentioned action.

INDUSTRIAL APPLICABILITY Since the present invention has the effects described above, a base film for a magnetic recording medium such as a magnetic tape or a floppy disk, an electrophotographic / photosensitive optical base film, a condenser base film, a graphic base film,
Suitable as a cover film for liquid crystal displays, a release base film, a packaging base film, an adhesive tape base film, an electrical insulating base film, a polarizing film, a printed circuit board base film, and in particular surface foreign matter. It is ideal for magnetic recording media, capacitors, and optical applications such as covers for photographs and liquid crystal displays, and polarized light, where defects and opacity are disliked.

[Characteristic Measuring Method and Evaluation Criteria] The characteristic measuring method and evaluation criteria in the present invention are as follows.

(1) Content of higher fatty acid ester W (% by weight) The film sample before dry heat treatment was dissolved in the solvent CDC ₃ and measured by nuclear magnetic resonance at 400 MHz, ¹ H-NMR.
(JOEL GX-400 type pulse FT spectrometer) and 22.5 MHz, ¹³ C-NMR (JOEL FT-
900 type pulse FT spectrometer) was analyzed and W was calculated | required. In addition to the NMR method, in addition to the NMR method, FT
-IR method, ESCA method, SIMS method, MOLE method, GC
-MS method etc. were used.

(2) Film surface layer oligomer amount Mt (μg / cm ² ) Cut into a film of 10 cm × 10 cm and dry-heat treated
Immerse in 100 ml of HC _{3 at} 25 ° C for 5 minutes and take out. Oligomer-containing CHC extracted into this CHC _{3
The 3} liquids were fed up into a 100 ml quantitative cell, the absorbance at a wavelength of 240 nm was measured using a Hitachi spectrophotometer 100-60 type, and the weight of the oligomer was measured by applying the Lambert-Beer law formula. It was converted per unit area (cm ² ). (It can be confirmed from the IR spectrum that the oligomer is a cyclic trimmer.) The film subjected to dry heat treatment means a film treated at an arbitrary temperature T (° C) in the range of 160 to 200 ° C for 1 hour. Specifically, it refers to five types of films that are respectively heat-treated under the conditions of 160 ° C. for 1 hour, 170 ° C. for 1 hour, 180 ° C. for 1 hour, 190 ° C. for 1 hour, and 200 ° C. for 1 hour. To do.

(3) Film Haze Ht (%), Transparency A dry heat-treated film was prepared in the same manner as in the item (2), and the haze of the film was measured according to ASTM-D-1003-52 and converted to 15 μm. The transparency is
When the Ht value of haze exceeds 7%, it is indicated by "X", and when it is 7% or less, it is indicated by "O".

(4) Surface foreign matter A dry-heat-treated film is prepared in the same manner as in (2), aluminum is vacuum-deposited to a thickness of 100 nm on the film, and the film is observed with a differential interference microscope manufactured by Nippon Kogaku Co., Ltd. to obtain a photograph with a magnification of 1000 times. Next, the surface foreign matter visually observed on this photograph is counted and converted into 1 cm ² (unit: pieces / cm ² ).

There are various shapes of foreign matter, but if the major axis is 3 μm or more and the number is 1 piece / cm ² or more, the surface foreign matter is evaluated as poor, and if it is 0 piece / cm ² , the surface foreign matter is The evaluation is good and is indicated by a mark "○".

Example Hereinafter, an example of an embodiment of the present invention will be described based on an example.

Example 1, Comparative Examples 1 and 2 100 parts by weight of terephthalic acid and 43 parts by weight of ethylene glycol were kneaded to prepare a slurry. 245 ℃ in the reactor
The slurry was continuously added at a constant rate to the reaction product of terephthalic acid (50 parts by weight) and ethylene glycol (21.5 parts by weight), and the esterification reaction was carried out at 245 ° C. under atmospheric pressure to distill the produced water. Let An esterification reaction product corresponding to 100 parts by weight of terephthalic acid was transferred from the obtained reaction product to a polymerization device, and 0.045 parts by weight of phosphoric acid, 0.023 part by weight of antimony trioxide, and an average particle size of 1.5 μm were used. 0.03 parts by weight of calcium carbonate was added as an ethylene glycol slurry, and polycondensation reaction was carried out according to a conventional method.
The obtained polymer had an intrinsic viscosity of 0.615 (designated as polymer A).

In the same manner as for Polymer A, 0.03 part by weight of calcium carbonate was added to carry out a polycondensation reaction, and after the reaction was completed, 1 part by weight of myricyl cerotinate, which is a higher fatty acid ester, was added and kneading was performed for about 10 minutes. A polymer having an intrinsic viscosity of 0.610 was obtained (designated as polymer B).

The term myrisyl cerotate means cerotic acid [CH ₃ (CH ₂ ) ₂₄ COOH] having 26 carbon atoms and myricyl alcohol [C which is a monovalent alcohol having 30 carbon atoms.
H ₃ (CH ₂ ) ₂₉ OH] and a higher fatty acid ester.

A polymer having an intrinsic viscosity of 0.615, which was polyethylene terephthalate only, was obtained in the same manner as polymer B, but without adding calcium carbonate or higher fatty acid ester (designated as polymer C).

A polymer composition obtained by blending the thus-obtained polymers A, B and C in appropriate amounts (Example 1, Comparative Example 2) and a polymer composition containing the polymers A and C and containing no myrisyl cerotate (Comparative Example 1). Was prepared, and each polymer composition was dried under reduced pressure (180 ° C. for 2 hours) and melt extruded at 290 ° C.,
After casting on a cooling drum at 55 ° C. to obtain a non-stretched sheet, first, a roll between which a difference in peripheral speed was imparted was used.
It was stretched 3.7 times in the longitudinal (longitudinal) direction at 5 ° C. Then, send it to the tenter, grasping both ends with clips,
The film was stretched 4.0 times in the transverse (width) direction at 0 ° C, heat-set at 205 ° C for 10 seconds without being relaxed in the transverse direction in the same manner, sent out from the tenter, and wound as a film having a thickness of 15 µm.

Then, these three types of films were subjected to 170 ° C. and 170 ° C.
℃, 180 ℃, 190 ℃, 200 ℃ (Comparative Example 2 160
C. and 200.degree. C.) separately exposed to a dry heat oven for 1 hour, then removed from the oven and the amount of surface oligomer M
The film haze Ht was measured, Mt / Ht was calculated, and the surface foreign matter and transparency were evaluated.

The results of measurement and evaluation are shown in Table 1.

As is clear from Table 1, in Example 1, the amount of higher fatty acid ester added, Mt, and Mt / Ht are within the scope of the present invention. Therefore, the surface foreign matter evaluation is “◯”, and the transparency evaluation is “◯”. there were. On the other hand, Comparative Example 1 does not contain myricyl serotiate at all, and Comparative Example 2 does not have enough content even if it contains myricyl cerotate, so that both the evaluation of surface foreign matter and the transparency are “○”. It did not result.

Comparative Examples 3, 4, 5, and 6 As in Example 1, but 1 part by weight of montanic acid ethyl ester, beeswax, sodium montanate, sorbitan stearate ester, respectively, in place of the myricyl cerotylate of Example 1. Polymers D, E,
F and G were obtained. Of the above four additives, montanic acid ethyl ester and beeswax are preferred higher fatty acid esters of the present invention, but sodium montanate ester salt is a metal salt of the ester, and sorbitan stearate is also 4 Since it is an ester composed of sorbitan having a valent hydroxyl group, it is excluded from the preferred higher fatty acid ester of the present invention and is not desirable.

As in Example 1, four kinds of polymers were prepared by blending polymers A, D, C and polymers A, E, C, and polymers A, F, C, and polymers A, G, C in appropriate amounts. A composition was prepared (Comparative Examples 3 to 6), and in Comparative Examples 5 and 6, a film having a thickness of 15 μ was formed under the conditions of sequential biaxial stretching and heat setting as in Example 1. On the other hand, in Comparative Examples 3 and 4, extrusion was performed in the same manner as in Example 1, the stretching conditions were changed to the conditions shown in Table 3 to perform film formation, and the thickness was 15 μm.
And the film. Then, one of these four types of film
Separately exposed to a dry heat oven at 60 ° C. (160 ° C. and 200 ° C. for the film of Comparative Example 5) for 1 hour, and then taken out from the oven, and the surface layer oligomer amount Mt and the film haze Ht.
Was measured, Mt / Ht was calculated, and foreign matter on the surface and transparency were evaluated.

The results of measurement and evaluation are shown in Table 2.

As is clear from Table 2, Comparative Example 3 has too much Mt, Comparative Example 4 has too large Mt / Ht, and Comparative Example 5 shows that the higher fatty acid ester is not an ester but an ester metal salt. Mt and Mt / Ht both are large, and in Comparative Example 6, the higher fatty acid ester is composed of a tetravalent alcohol, and Mt and Mt / Ht are also large, so that the surface foreign matter of the film is good and the transparency is good. It was not possible to achieve both.

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Claims (1)

[Claims] 1. A stretched film comprising polyethylene terephthalate containing 0.11 to 0.5% by weight of a higher fatty acid ester comprising a higher aliphatic monocarboxylic acid and a monohydric or dihydric alcohol, and 160 To 200
The surface layer oligomer amount Mt (μg / cm ² ) of the film heat-treated at an arbitrary temperature T (° C.) in the range of 0 ° C. and the haze (film thickness of the film heat-treated at the temperature T (° C.) for 1 hour. A polyethylene terephthalate film having the following relationship with Ht (value converted to 15 μm). Mt ≦ 0.8 …… (1) Mt / Ht <0.1 …… (2)