JP6550973B2 - Oligomer precipitation prevention polyester film - Google Patents

Description

  The present invention relates to a polyester film used for industrial use and packaging. More specifically, it relates to a polyester film having excellent post-heating oligomer precipitation preventing properties.

  Polyester films represented by polyethylene terephthalate films have excellent properties such as mechanical strength, dimensional stability, flatness, heat resistance, chemical resistance, optical properties, etc., and are excellent in cost performance, so they are used in various applications. It is done.

  Polyester is a linear polymer usually produced from a dicarboxylic acid component and a glycol component by a polycondensation reaction. However, conventionally known polyesters contain several% of oligomers such as cyclic trimers. Such an oligomer such as cyclic trimer has a problem that when the polyester film is heat-treated, the oligomer is deposited on the film surface and the film is whitened. In particular, as the use of polyethylene terephthalate film diversifies, the processing conditions and use conditions of the film also diversify, for example, when oligomer deposition on the film surface requires high transparency such as optical use etc. Is a major problem. From the viewpoint of productivity, the precipitation of oligomers by heat treatment is becoming more serious as the temperature of heat treatment applied to post-processing becomes higher.

  Then, as a method of suppressing the precipitation of the oligomer by heating, in order to reduce the oligomer in a polyester film, reducing the cyclic oligomer amount of polyester raw material by solid phase polymerization method is proposed (refer patent document 1 and 2). Although this method can reduce the number of cyclic oligomers, the polycondensation reaction of the polyester also proceeds simultaneously, the degree of polymerization of the obtained polyester becomes high, and there is a problem that the load becomes large when performing extrusion molding.

  Further, it has been proposed to suppress oligomer deposition after heating by applying a specific coating layer to a general polyester film and modifying the surface thereof. (See Patent Document 3)

JP-A-9-99530 JP 2000-141570 A JP 2005-336394

  However, when the heating condition of the polyester film is higher and the requirement for the transparency is high, the effect of preventing the precipitation of the oligomer may be insufficient only by the surface modification by the known coating layer. Specifically, when the polyester film is wound, stored, and transported in the form of a roll, the function of preventing oligomer deposition may be deteriorated as compared with the polyester film before winding.

  An object of the present invention is to solve the problems of the prior art described above, and to provide a polyester film which is excellent in transparency after heat processing and in which precipitation of oligomers is extremely small.

  MEANS TO SOLVE THE PROBLEM As a result of earnestly examining in order to solve the said subject, the present inventors discovered that the following polyester film exhibited the oligomer precipitation prevention effect remarkably. That is, the present invention has the following constitution.

1. A laminated polyester film in which a coating layer having a thickness of 20 nm or more is provided on at least one surface of a polyester film substrate, and the resin used for the coating layer is an amino acrylic resin having a Tg of 90 ° C. to 200 ° C. The coefficient of static friction μs of the contact surface is 0.1 or more and 0.6 or less when stacked so that one side of the film and the opposite side are in contact with each other, and the haze before and after heat treatment at 150 ° C. for 60 minutes The oligomer precipitation preventing polyester film characterized in that the increase amount Δ haze is 0.3% or less and the haze before the heat treatment is 1.5% or less.
2. The oligomer deposition-preventing polyester film as described in the first above, wherein the coating layer contains particles, the average particle diameter of the particles is 50 nm or more and 200 nm or less, and the thickness is larger than the thickness of the coating layer.

  The oligomer precipitation preventing polyester film of the present invention is excellent in transparency after heat processing and hardly causes precipitation of an oligomer. Therefore, since it can be post-processed at high temperatures, it is a film suitably used in industrial applications including optical applications where high quality is required.

  The reason why the polyester film of the present invention exhibits an oligomer precipitation preventing effect is considered as follows. That is, the deposition of the oligomer which can not be prevented by the surface modification by the conventional film coating layer is deposited on the surface through the defects of the very small coating layer, and the cause of the generation of such defects is the surface of the film. It is considered to be due to the local frictional force applied to the

  In the present invention, by setting the static friction coefficient between one side of the film and the opposite side to a certain value or less, the frictional force to the coated layer is reduced, and by keeping the certain value or more, the film is wound into a roll. It is considered that local pressure load due to winding deviation at the time of rolling is alleviated, and the transparency after heat processing is suitably excellent, and the precipitation of the cyclic oligomer can be prevented.

Hereinafter, the present invention will be described in detail.
The oligomer precipitation preventing polyester film of the present invention is a laminated polyester film having a coating layer on at least one side of a polyester film substrate. The polyester film substrate is a film obtained by melt-extruding a polyester resin by a known method and then stretched, and a film having a thickness of 10 to 250 μm is suitably used. The polyester film substrate may also contain various stabilizers, ultraviolet inhibitors, antistatic agents, lubricants, pigments, antioxidants, plasticizers and the like.

  The polyester resin may be homopolyester or copolyester. When it consists of homo polyesters, what is obtained by polycondensing aromatic dicarboxylic acid and aliphatic diol is preferred. Examples of the aromatic dicarboxylic acid include terephthalic acid, isophthalic acid and 2,6-naphthalenedicarboxylic acid. Examples of aliphatic glycols include ethylene glycol, 1,3-propanediol, 1,4-butanediol, and 1,2. 4-cyclohexanedimethanol etc. are mentioned. Examples of representative homopolyesters include polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polytrimethylene terephthalate (PTT), polybutylene terephthalate (PBT) and the like, with polyethylene terephthalate being particularly preferred. On the other hand, as the dicarboxylic acid component of the copolyester, isophthalic acid, phthalic acid, terephthalic acid, 2,6-naphthalenedicarboxylic acid, adipic acid, sebacic acid, oxycarboxylic acid (eg, P-hydroxybenzoic acid etc.), etc. 1 type or 2 or more types to be selected are mentioned, 1 type selected from ethylene glycol, diethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,4-cyclohexanedimethanol, neopentyl glycol etc. as a diol component Or 2 or more types are mentioned. In any case, it is preferable that the polyester referred to in the present invention is a polyester in which usually 60 mol% or more, preferably 80 mol% or more, comprises ethylene terephthalate as a repeating unit.

  The lower limit of the amount of oligomers contained in the polyester film substrate is preferably 0.25% by mass, more preferably 0.3% by mass, and still more preferably 0.35% by mass. If the amount of oligomers contained in the polyester film substrate is 0.25% by mass or more, the treatment for reducing the amount of oligomers does not require a particularly long time, which is preferable from the viewpoint of productivity.

  The upper limit of the amount of oligomers contained in the polyester film substrate is preferably 1% by mass, more preferably 0.95% by mass, and still more preferably 0.9% by mass. When the amount of oligomers contained in the polyester film substrate is 1% by mass or less, the effect of suppressing deposition of oligomers by the coating layer is particularly easily exhibited, which is preferable.

  The oligomer precipitation preventing polyester film of the present invention has a remarkable effect of preventing the oligomer precipitation when it is wound up into a roll. In the film roll by the oligomer precipitation prevention polyester film of the present invention, the width of the film roll is not particularly limited, but from the viewpoint of ease of handling, the lower limit of the width of the film roll is 0.7 m or more Preferably, it is more preferably 1.0 m or more. On the other hand, the upper limit of the width of the film roll is determined by the size of the device of the customer to be post-processed, but at present 2.2m is considered to be the maximum width, more preferably 2.0m or less. More preferably, it is 5 m or less. In addition, the winding length of the film roll is not particularly limited, but from the viewpoint of ease of winding and handling, when the film has a thickness of about 10 μm, it is preferably 10000 m or less, more preferably 8000 m or less preferable. When the film has a thickness of about 250 μm, it is preferably 2000 m or less, and more preferably 1800 m or less. Therefore, when the thickness of the film is in the middle of 10 to 250 μm, the winding length is preferably set to 500 m or more and 10000 m or less. The lower limit of the winding length is preferably 100 m. When the winding length is 100 m or more, the effect of the optimization of the slip property of the front and back in the present invention is more clearly exhibited.

  In addition, as a winding core, paper of 3 inches, 6 inches, 8 inches etc., a plastic core, and a metal core can be used normally.

  There is no particular limitation on the type of resin used for the coated layer of the polyester film of the present invention, and preferable examples include PMMA resin, amino acrylic resin, cycloolefin polymer and the like.

  The Tg of the resin used in the coating layer is preferably 90 ° C. or more and 200 ° C. or less, more preferably 95 ° C. or more and 170 ° C. or less, and still more preferably 100 ° C. or more and 150 ° C. or less. Oligo block property does not fall that Tg is 90 degreeC or more, and is preferable. A resin having a Tg of more than 200 ° C. can be suitably used specifically as a transparent resin and there is not much resin likely to be used.

  As a means to express the slipperiness of the front and back of the film while maintaining the transparency of the film itself, there is a method of adding particles in the coating layer to prevent precipitation of the oligomer, or the opposite side of the coating layer to prevent precipitation of the oligomer And the method of coating a slippery layer, the method of providing the layer which disperse | distributed particle | grains only to the surface layer of the film used as a base material etc. are mentioned.

  When particles are added to the coating layer, the lower limit of the average particle diameter of the particles contained in the coating layer is preferably 50 nm, more preferably 60 nm, and still more preferably 70 nm. When the average particle size is 50 nm or more, the slipperiness is not insufficient and the scratch is hard to occur, so the oligomer is hard to precipitate, which is preferable.

  The upper limit of the average particle diameter of the particles contained in the coating layer is preferably 200 nm, more preferably 180 nm, and still more preferably 160 nm. When the average particle size of the particles is 200 nm or less, the haze is low and the transparency is maintained, which is preferable. The average particle diameter of the particles is preferably larger than the thickness of the coating layer. When the average particle diameter of the particles is larger than the thickness of the coating layer, appropriate slipperiness can be effectively obtained, and as a result, the oligomer precipitation suppressing effect can be obtained. More preferably, the average particle diameter of the particles is more preferably 15 nm or more larger than the thickness of the coating layer, and particularly preferably 20 nm or more. However, if the average particle size of the particles is too large relative to the thickness of the coating layer, the particles are likely to come off due to abrasion, so the average particle size of the particles should be larger in the range of 100 nm or less than the thickness of the coating layer. preferable.

  The average particle diameter of the particles was measured by observing the particles of the cross section of the laminated film after processing with a scanning electron microscope, observing 100 particles, and taking the average value as the average particle diameter.

  The shape of the particles is not particularly limited as long as the object of the present invention is satisfied, and spherical particles and irregular-shaped non-spherical particles can be used. The particle size of the irregularly shaped particles can be calculated as the equivalent circle diameter. The equivalent circle diameter is a value obtained by dividing the area of the observed particles by π, calculating the square root and doubling it.

  The type of particles contained in the coating layer is not particularly limited. For example, siloxane copolymer acrylic resin, crosslinked polystyrene, polystyrene-divinylbenzene, polymethyl methacrylate, methyl methacrylate copolymer, methyl methacrylate copolymer crosslinked body, poly Organic particles such as tetrafluoroethylene, polyvinylidene fluoride, polyacrylonitrile, benzoguanamine resin, silicone resin, acrylic resin etc., silica, alumina, titanium dioxide, kaolin, talc, graphite, calcium carbonate, feldspar, molybdenum disulfide, carbon black Inorganic particles such as barium sulfate can be used. Moreover, you may use the core-shell type | mold particle | grains of the multilayer structure comprised with the substance from which each property inside and outside differs. Preferably, silica is mentioned.

  The lower limit of the particle content contained in the coating layer is preferably 4 mass (%, relative to resin), more preferably 5 mass (%, relative to resin). Since slipperiness | lubricity is maintained as it is 4 mass% or more, it is hard to be damaged, an oligomer does not precipitate easily, and is preferable.

  The upper limit of the particle content contained in the coating layer is preferably 20 mass (%, relative to resin), more preferably 17 mass (%, relative to resin), still more preferably 15 mass (%, relative to resin) It is. When it is 20% by mass or less, the haze is not too high and the transparency is maintained, which is preferable. The said particle content is represented by the mass% of particle content with respect to resin solid content of a coating layer.

  The lower limit of the thickness of the coating layer is preferably 20 nm, more preferably 30 nm, and even more preferably 40 nm. When the thickness of the coating layer is 20 nm or more, the effect of suppressing oligomer deposition becomes clear, which is preferable.

  The upper limit of the thickness of the coating layer is preferably 150 nm, more preferably 130 nm, and still more preferably 120 nm. When the thickness of the coating layer is 150 nm or less, it is preferable that the problem of blocking does not easily occur.

  The lower limit of the ratio of thickness of coating layer / average particle diameter of particles in coating layer is preferably 0.1, more preferably 0.2, and still more preferably 0.3. When the ratio of the thickness of the coating layer / the average particle diameter of the particles in the coating layer is 0.1 or more, the particles do not fall off, there is no possibility of scratching the film surface, and oligomers are difficult to precipitate, which is preferable.

  The upper limit of the ratio of thickness of coating layer / average particle diameter of particles in coating layer is preferably 0.9, more preferably 0.85, and still more preferably 0.83. When the ratio of the thickness of the coating layer / the average particle diameter of the particles in the coating layer is 0.9 or less, the slipperiness does not become insufficient, and the film surface is hardly scratched, so that the oligomer hardly precipitates, which is preferable.

  An undercoat layer may be provided on the surface of the polyester film substrate, but the resin of the undercoat layer is preferably a polyester resin. It is preferable to contain naphthalene dicarboxylic acid as an acid component of the polyester resin, and by including naphtha reresidue carboxylic acid, the refractive index is increased, and iris color under a fluorescent lamp is easily suppressed, which is preferable. Thus, the adhesion to the oligo block layer can be improved, and the refractive index can be adjusted to improve the light transmittance. In addition, a crosslinking agent may be contained in the undercoat layer. By containing a crosslinking agent, the solvent resistance at the time of applying the coating layer for oligomer precipitation suppression can be improved. As a crosslinking agent, a urea type, an epoxy type, a melamine type, an isocyanate type, an oxazoline type etc. are mentioned. Among these, melamine-based, isocyanate-based and oxazoline-based ones are more preferable in view of the temporal stability of the coating solution and the adhesion improvement effect under high temperature and high humidity treatment. In addition, in order to accelerate the crosslinking reaction, it is also preferable to appropriately use a catalyst or the like as necessary.

  The lower limit of the thickness of the undercoat layer is preferably 5 nm, more preferably 10 nm. If the thickness of the undercoat layer is 5 nm or more, the adhesion to the oligo block layer is preferably increased.

  The upper limit of the thickness of the undercoat layer is preferably 100 nm, more preferably 80 nm. When the thickness of the undercoat layer is 100 nm or less, the haze is not too large, and the high transparency is not likely to be impaired, which is preferable.

  The lower limit of the refractive index of the undercoat layer is preferably 1.5, more preferably 1.53, and still more preferably 1.55. When the refractive index of the undercoat layer is 1.5 or more, the effect of improving the light transmittance becomes clear, which is preferable.

  The upper limit of the refractive index of the undercoat layer is preferably 1.7, more preferably 1.67, and still more preferably 1.65. When the refractive index of the undercoat layer is 1.7 or less, the haze is not too high, and high transparency is maintained, which is preferable.

In order to adjust the refractive index of the undercoat layer to be high, it is preferable that the undercoat layer contain high refractive index particles. The high refractive index particles in the undercoat layer are not particularly limited, but specific examples include metal oxide particles having a refractive index of 1.7 or more and 3.0 or less. As such metal oxides, TiO2 (refractive index 2.7), ZnO (refractive index 2.0), Sb2O3 (refractive index 1.9), SnO2 (refractive index 2.1), ZrO2 (refractive index 2) .4), Nb 2 O 5 (refractive index 2.3), CeO 2 (refractive index 2.2), Ta 2 O 5 (refractive index 2.1), Y 2 O 3 (refractive index 1.8), La 2 O 3 (refractive index 1.9), In 2 O 3 (Refractive index 2.0), Cr 2 O 3 (refractive index 2.5), etc., and composite oxides containing these metal atoms are listed.
Can be mentioned.

  In the present invention, as a method of providing a coating layer having an oligomer deposition suppressing effect on a polyester film substrate, a polyester film is produced using a reverse roll coater, a gravure coater, a rod coater, an air doctor coater or a coating device other than these. The method of coating outside the process is preferred. Although it may be applied during the film production process, the method of applying it outside the former polyester film production process is more preferable in that it is necessary to be careful not to cause micro defects in the coating layer by stretching after application. is there.

  The lower limit of the solid content concentration of the coating solution for forming the coating layer is preferably 0.1% by mass, and more preferably 0.2% by mass. When the solid content of the coating solution is 0.1% by mass or more, the solvent resistance of the coating film is satisfied, and it is preferable because the problem of partial transfer of the coating layer to the back side does not occur when it is in a roll shape.

  The upper limit of the solid content concentration of the coating layer is preferably 10% by mass, more preferably 5% by mass. When the solid content concentration of the coating layer is 10% by mass or less, the viscosity does not become too high, the coatability is good, and the coating layer tends to be uniform, which is preferable.

  The lower limit of the drying temperature after application is preferably 70 ° C, more preferably 80 ° C, and still more preferably 90 ° C. When the drying temperature is 70 ° C. or higher, curing of the resin is not likely to be insufficient, and the oligomer precipitation suppressing effect is effectively exhibited.

  The upper limit of the drying temperature after coating is 180 ° C, preferably 170 ° C, more preferably 160 ° C. A drying temperature of 180 ° C. or lower is preferable because there is no fear of deformation of the substrate due to heat, and flatness is maintained.

  The lower limit of the drying time after coating is 10 seconds, preferably 15 seconds or more, and more preferably 20 seconds or more. When the drying time is 10 seconds or more, curing failure does not occur and the effect of suppressing oligomer precipitation is reliably obtained.

  The upper limit of the drying time after application is 120 seconds, preferably 90 seconds or less, and more preferably 60 seconds or less. If the drying time after application is 120 seconds or less, there is no problem of deformation of the substrate due to heat, and planarity is maintained, which is preferable.

  The lower limit of the static friction coefficient of the contact surface is preferably 0.1 when one side of the film and the opposite side are in contact so as to be in contact with each other. The coefficient of static friction is about 0.1 as a range that can be industrially mass-produced in practice.

  The upper limit of the static friction coefficient of the contact surface is preferably 0.6, and more preferably 0.5, when one side of the film and the opposite side are in contact so as to be in contact. When the static friction coefficient is 0.6 or less, there is no possibility of being scratched, and the effect of suppressing oligomer deposition is remarkably obtained, which is preferable.

  The coefficient of static friction between the contact surfaces when the single side of the polyester film substrate finally provided with the coating layer is in contact with the opposite side is more preferably 0.2 or more and 0.5 or less. Particularly preferably, it is 0.3 or more and 0.4 or less. When the coefficient of static friction is 0.6 or less, the frictional force applied to the coating layer does not become too large, and no scratch or crack occurs in the coating layer. On the other hand, when the coefficient of static friction is 0.1 or more, there is no problem of excessive slippage after winding, and it is difficult to feed the winding displacement, so there is no problem of local pressure being applied and there is a possibility that scratches or cracks may occur in the coated layer Absent.

  After production, the upper limit of the initial haze not particularly heat-treated is preferably 1.5%, more preferably 1.3%, still more preferably 1.2%, particularly preferably 1.0%. An initial haze of 1.5% or less is preferable in terms of transparency.

  The upper limit of ΔHaze, which is the increase in haze before and after heat treatment at 150 ° C. for 60 minutes, is preferably 0.3%, more preferably 0.2%, and still more preferably 0.1%. When the Δhaze is 0.3% or less, the transparency of the film after heating is maintained, and the optical characteristics are maintained. In addition, when the Δ haze is 0.3% or less, when the film wound in a roll is wound after long-term storage, oligomer deposition is suppressed, and transparency is preferably maintained.

  In the present invention, ΔHaze is an index of whitening susceptibility by heating, and is represented by ΔHaze = (Haze after heating) − (Haze before heating). The range of ΔHaze 0.3 or less corresponds to increase in haze before and after heating when it is determined that white light is observed by visually applying strong light to a film in a dark room and whitening is not caused by heating.

  EXAMPLES Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited to the following examples. In addition, "part" in an Example and a comparative example shows a "weight part."

[Evaluation method]
(1) Haze It measured based on JISK7105 "optical property test method of plastic" haze (cloudiness value). As a measuring instrument, NDH-300A type turbidity meter by Nippon Denshoku Industries Co., Ltd. was used.

(2) Amount of increase in haze before and after heat treatment (ΔHaze) Evaluation A film is cut into a 50 mm × 75 mm square and is subjected to heat treatment according to JIS K 7105 “Optical property test method of plastic” haze (cloudiness value) The initial haze was measured. As a measuring instrument, NDH-300A type turbidity meter by Nippon Denshoku Industries Co., Ltd. was used. In order to measure the haze after heating, a protective film (PC-T073 manufactured by Fujimori Kogyo) is adhered to the surface of the sample film piece which has not been subjected to the haze evaluation before the heat treatment using a roller so as to prevent air bubbles. With the protective film attached, the film is set in an oven heated to 150 ° C., and after 60 minutes, the film is taken out. Thereafter, the protective film is peeled off, and the haze of the film is measured in the same manner as described above to obtain a haze after heating. The difference in haze before and after heating is taken as ΔHaze.
Δ Haze (%) = (Haze after heating)-(Haze before heating)

(3) Measurement of static friction coefficient The static friction coefficient of the contact surface when one side of the film and the opposite side of the film are overlapped so as to be in contact using a universal testing machine (manufactured by Shimadzu Corp., AGS-1 kNG) (Μs) was measured according to JIS K-7125 under the following conditions.
Test piece: width 50 mm x length 60 mm
Load: 4.4kg
Test speed: 200 mm / min

Example 1
2.5 parts of amino acrylic resin (manufactured by Hitachi Chemical Polymer Co., Ltd .: Tesfine 322: solid content 40%), 0.025 parts of P-toluenesulfonic acid (manufactured by Hitachi Chemical Polymer Co., Ltd .: dryer 900) as an acid catalyst, silica sol as a lubricant 50 parts of toluene and 47.2 parts of methyl ethyl ketone dissolved in a mixed solution of 0.3 parts of methyl ethyl ketone dispersion (manufactured by Nissan Chemical Industries, Ltd .: MEK-ST-L: 30% of solid content) The coating solution was applied to a non-slip surface of a 125 μm thick biaxially stretched polyethylene terephthalate film (Toyobo Co., Ltd .: A4100) and dried at 150 ° C. for 1 minute to make the thickness of the coating layer 75 nm.

(Example 2)
A film was prepared in the same manner as in Example 1 except that the coating solution of Example 1 was coated so as to give a coating thickness of 25 nm after drying.

(Reference Example 3)
3.0 parts of polyester resin (Toyobo Co., Ltd .: Byron 20SS: solid content 30%), 0.13 parts of isocyanate (Nippon Polyurethane Co., Ltd .: Coronate L: solid content 75%) 0.13 parts as a curing agent, silica sol methyl ethyl ketone dispersion liquid as lubricant A coating solution having a solid content of 1% by weight prepared by dissolving 0.3 parts of MEK-ST-L: 30 parts of solid content by Nissan Chemical Industries, Ltd. in a mixed solution of 50 parts of toluene and 46.8 parts of methyl ethyl ketone It apply | coated to the non-smooth surface of the 125-micrometer-thick biaxial stretching polyethylene terephthalate film (Toyobo Co., Ltd. make: A4100), dried at 150 degreeC for 1 minute, and set thickness of the application layer to 75 nm.

(Reference Example 4)
Polymethyl methacrylate (Mitsubishi Rayon Co., Ltd .: BR-80: solid content 100%) 1.0 part, silica sol methyl ethyl ketone dispersion as lubricant (Nissan Chemical Industry Co., Ltd .: MEK-ST-L: solid content 30%) 0. A coating liquid having a solid content of 1% by weight prepared by dissolving 3 parts in 50 parts of toluene and 48.7 parts of methyl ethyl ketone was treated with a 125 μm thick biaxially stretched polyethylene terephthalate film (Toyobo Co., Ltd .: A4100) The smooth surface was coated and dried at 150 ° C. for 1 minute to make the thickness of the coating layer 75 nm.

(Example 5)
2.5 parts of amino acrylic resin (manufactured by Hitachi Chemical Polymer Co., Ltd .: Tesfine 322: solid content 40%), 0.025 parts of P-toluenesulfonic acid (manufactured by Hitachi Chemical Polymer Co., Ltd .: dryer 900) as an acid catalyst, silica sol as a lubricant A methyl ethyl ketone dispersion (manufactured by Nissan Chemical Industries, Ltd .: MEK-ST-L: 30% solid content) 0.18 parts, dissolved in a mixed solution of 50 parts of toluene and 47.3 parts of methyl ethyl ketone The coating solution was applied to a non-slip surface of a 125 μm thick biaxially stretched polyethylene terephthalate film (Toyobo Co., Ltd .: A4100) and dried at 150 ° C. for 1 minute to make the thickness of the coating layer 25 nm.

(Comparative example 1)
Apply a solution prepared by mixing 50 parts of ethyl silicate (Colcoat N-103X), 25 parts of water, and 25 parts of isopropyl alcohol on a non-slip surface of a wire bar # 5 (Toyobo Co., Ltd .: A4100) at 150 ° C. Dried for 1 minute. The thickness of the coating layer was 75 nm.

(Comparative example 2)
2.5 parts of amino acrylic resin (manufactured by Hitachi Chemical Polymer Co., Ltd .: Tesfine 322: solid content 40%), 0.025 parts of P-toluenesulfonic acid (manufactured by Hitachi Chemical Polymer Co., Ltd .: dryer 900) as an acid catalyst, silica sol as a lubricant 50 parts of toluene and 47.4 parts of methyl ethyl ketone were dissolved in a mixed solution of 0.1 parts of methyl ethyl ketone dispersion (manufactured by Nissan Chemical Industries, Ltd .: MEK-ST-L: 30% of solid content) to prepare a solid content of 1% by weight The coating solution was applied to a non-slip surface of a 125 μm thick biaxially stretched polyethylene terephthalate film (Toyobo Co., Ltd .: A4100) and dried at 150 ° C. for 1 minute to make the thickness of the coating layer 7.5 nm.

(Comparative example 3)
2.5 parts of amino acrylic resin (manufactured by Hitachi Chemical Polymer Co., Ltd .: Tess Fine 322: solid content 40%), 0.025 parts of P-toluenesulfonic acid (manufactured by Hitachi Chemical Polymer Co., Ltd .: dryer 900) as an acid catalyst and 50 parts of toluene A coating solution having a solid content of 1% by weight dissolved in 47.5 parts of methyl ethyl ketone mixed solution is applied to a non-slip surface of a 125 μm thick biaxially stretched polyethylene terephthalate film (Toyobo Co., Ltd .: A4100), 150 It dried at 1 degreeC for 1 minute, and set thickness of the application layer to 75 nm.

  The oligomer precipitation-preventing polyester film of the present invention is excellent in transparency after heat processing and hardly causes precipitation of oligomers, so post-processing at high temperatures is possible and optical applications requiring high quality are included. It is a film suitably used also in the industrial use and packaging general use.

Claims (2)

A laminated polyester film in which a coating layer having a thickness of 20 nm or more is provided on at least one surface of a polyester film substrate, and the resin used for the coating layer is an amino acrylic resin having a Tg of 90 ° C. to 200 ° C. The coefficient of static friction μs of the contact surface is 0.1 or more and 0.6 or less when stacked so that one side of the film and the opposite side are in contact with each other, and the haze before and after heat treatment at 150 ° C. for 60 minutes The oligomer precipitation preventing polyester film characterized in that the increase amount Δ haze is 0.3% or less and the haze before the heat treatment is 1.5% or less.   The polyester precipitation preventing polyester film according to claim 1, wherein the coating layer contains particles, the average particle diameter of the particles is 50 nm or more and 200 nm or less, and the thickness is larger than the thickness of the coating layer.