JP2012184399A - Polyester film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a film that achieves flame retardancy, a thin film, heat resistance, and printability without impairing appearance, transparency, mechanical properties, and chemical properties which an oriented polyester film originally has.SOLUTION: The polyester film contains a compound, which is obtained when a specific cyclic phosphine compound is bonded to a side chain of a specific aliphatic polyester, and has a thickness of 20-100 μm, wherein the polyester film has a phosphorus content of 0.30-2.00 wt.% and a melting point (Tm) of 247°C or more and includes a coating layer containing a polyester component in a film production process.

Description

  The present invention relates to a flame retardant polyester film. More specifically, the present invention provides flame retardancy, thin film properties, heat resistance without impairing the features of the oriented polyester film such as appearance, transparency, mechanical strength, thermal properties, electrical properties, and higher workability. The present invention relates to a film that achieves printability and printability.

  Biaxially stretched polyester film excels in transparency, dimensional stability, mechanical properties, heat resistance, electrical properties, gas barrier properties, chemical resistance, etc., packaging materials, electrical insulation materials, metal deposition materials, plate making materials, It is used in many applications such as magnetic recording materials, display materials, transfer materials, and window paste materials.

  With the recent increase in heat generation due to downsizing and higher efficiency of personal computers and mobile phones, the polyester film for labels used in the batteries of these devices requires a thin film on the label from the viewpoint of miniaturization, and heat generation. From the viewpoint of fire prevention from the origin, there is an increasing demand for useful mechanical properties and heat resistance as a structural material requiring flame retardancy and heat resistance to the label. In general, as an indicator of flame retardancy, certification under the standard UL94 of UNDERWRITERS LABORATORIES is often used.

  As a flame retardant compound capable of imparting flame retardancy to a polyester film, halogen-containing compounds such as organic halogen compounds and halogen-containing organic phosphorus compounds are known to have a high flame retardant effect. However, a resin containing a halogen-containing flame retardant compound has been regarded as a problem that a toxic gas is generated during processing or combustion. In particular, it has been pointed out that bromine-containing flame-retardant compounds generate hydrogen bromide gas during molding and processing, and generate dioxin-like gas during combustion. Therefore, in recent years, it has been strongly demanded to use a flame retardant compound containing no halogen.

  In addition, as other flame retardant compounds, inorganic compounds typified by magnesium hydroxide, inorganic phosphorus compounds typified by red phosphorus, and organic phosphorus compounds such as phosphate esters, phosphonic acid compounds and phosphinic acid compounds are known. . Of these, inorganic flame retardant compounds such as inorganic compounds and inorganic phosphorus compounds are not as toxic as halogen flame retardant compounds, but are poorly compatible with resins and significantly impair the transparency of resins. Sometimes. From this viewpoint, an organophosphorus compound has attracted attention as a flame retardant compound.

  As a flame retarding technique for a polyester film, for example, as disclosed in Patent Document 1, Patent Document 2, etc., a method of adding or mixing an organic phosphorus compound or copolymer melt extrusion is proposed.

  Among them, a method (copolymerization method) in which a flame-retardant compound is added and copolymerized at the time of polyester polymerization is known as a method having high industrial value because of its bleed-out resistance. For this reason, many methods for copolymerizing an organic phosphorus compound with polyester have been proposed for the purpose of imparting flame retardancy. For example, polyester contains an organic phosphorus compound as a method of copolymerizing a phosphate ester (Patent Document 3), a method of copolymerizing a phosphonic acid (Patent Document 4), and a phosphorus compound having a special ester-forming functional group (Patent Document 5), a method of copolymerizing carboxyphosphinic acid (Patent Document 6), a method of copolymerizing a phosphine oxide derivative (Patent Document 7), and the like.

However, those obtained by copolymerizing a phosphorus compound at the time of polyester polymerization have a drawback that the mechanical properties and heat resistance are deteriorated because the melting point (Tm) is lowered. This is considered to be because a phosphorus compound having a lower softening point intervenes in the polyester.
In addition, in the case of phosphate ester, it is considered that this is due to the low binding energy of P—O in the compound, and the molecular weight is lowered due to the autocatalytic action accompanying the main chain cleavage during molding and processing. Also occurs. That is, in order to express higher flame retardancy, the mechanical properties and heat resistance are worsened as the copolymerization amount of the phosphorus compound in the polyester is increased. For this reason, it is considered difficult to achieve both flame retardancy, heat resistance, and mechanical properties.

  On the other hand, in recent years, a high degree of flame retardancy has also been demanded particularly for home appliances, electrical and OA equipment related parts. It is disclosed that flame retardancy of V-1 or V-0 can be realized with respect to UL94 standards for molded products having a thickness of 1.5 to 3.2 mm along with their miniaturization. (Patent Document 8, Patent Document 9). In these documents, a phosphorus compound and an inorganic compound are added together with polyester during molding and processing. In Patent Document 12, an amorphous resin is added together with polyester.

  However, regarding a very thin polyester film for a label used for a battery of a small terminal device such as a smartphone, a material that maintains flame retardancy has not been obtained.

  Patent Document 10 proposes an invention relating to a flame-retardant polyester film using a specific phosphorus compound. When the film is used as a battery label, it is necessary to apply a primer offline after forming a polyester film in order to improve printability. Since the primer itself is not a polymer material such as a polyester film, it is difficult to self-extinguish once burned, and the flame retardancy is lowered. Therefore, it cannot be said that the invention itself has a printing function, and further has flame retardancy even after the primer layer is provided.

  Patent Document 11 proposes that a primer layer is applied at the time of forming a polyester film. The polyester film according to the present invention has good printability without taking a primer off-line and is also considered to have flame retardancy. In general, a normal plastic film becomes more flammable as the film becomes thinner from the viewpoint of specific surface area. However, although the invention considers a thick polyester film, the thin film is not considered. Further, since the flame retardant compound and the polyester are copolymerized, the melting point of the polyester is lowered, so that the film has low heat resistance. That is, the present invention satisfies flame retardancy and printability, but cannot satisfy thin film properties and heat resistance.

Japanese Patent Publication No.51-19858 Japanese Patent Publication No. 55-41610 Japanese Patent Publication No.49-22958 JP 59-91122 A Japanese Patent Publication No. 36-20771 Japanese Patent Publication No.53-13479 Japanese Patent Laid-Open No. 1-40521 Japanese Examined Patent Publication No. 53-128195 JP 2007-112875 A Japanese Patent Laid-Open No. 63-19254 JP 2001-158070 A Japanese Patent Application No. 2007-538702 JP2006 / 318937

  The present invention has been made in view of the above circumstances, and the problem to be solved is flame retardancy, thin film without impairing the appearance, transparency, mechanical properties, and chemical properties inherent to the oriented polyester film. The object is to provide a film that achieves the performance, heat resistance and printability.

  As a result of intensive studies in view of the above problems, the present inventors have found that a flame-retardant polyester film having excellent characteristics can be obtained by using a specific film configuration, and to complete the present invention. It came.

  That is, the gist of the first invention is a polyester film having a thickness of 20 to 100 μm containing a compound represented by the following chemical formula (1), and a phosphorus content in the polyester film is 0.30 to 2.00. The polyester film has a melting point (Tm) of 247 ° C. or higher and is provided with a coating layer containing a polyester component in the film production process.

（上記化合物の平均分子量は１１７０以上である）

(The average molecular weight of the compound is 1170 or more)

  The gist of the second invention resides in the polyester film according to the first invention, which is a coating layer containing a urethane component and a melamine resin as a crosslinking agent.

  According to the present invention, there is provided a film that achieves imparting flame retardancy and maintaining the heat resistance of the film without impairing characteristics such as appearance, transparency, and thermal properties inherent to the oriented polyester film. be able to. The said film can be used suitably as a polyester film for labels used for the battery of a personal computer or a mobile phone, and the industrial value of this invention is high.

  The polyester film as referred to in the present invention refers to a film which is extruded by a co-extrusion method in which all layers are co-melt extruded from a die and then heat-set as necessary. Hereinafter, a single-layer or three-layer film will be described as the polyester film. In the present invention, the polyester film may be a multilayer of three or more layers or two layers as long as the purpose is satisfied.

In the present invention, the polymer constituting each layer of the film is mainly polyester obtained by using aromatic dicarboxylic acid or its ester and glycol as main starting materials, and 60% or more of the repeating structural units are ethylene terephthalate. Refers to a polyester having units or ethylene-2,6-naphthalate units. And if it is the conditions which do not deviate from said range, the other 3rd component may be contained.
Examples of the aromatic dicarboxylic acid component include terephthalic acid, dimethyl terephthalate, and 2,6-naphthalenedicarboxylic acid, for example, isophthalic acid, phthalic acid, adipic acid, sebacic acid, oxycarboxylic acid (for example, p-oxyethoxy) Benzoic acid etc.) can be used. In particular, terephthalic acid or dimethyl terephthalate is preferably used.
As an example of a glycol component, 1 type, or 2 or more types, such as diethylene glycol, propylene glycol, butanediol, 1, 4- cyclohexane dimethanol, neopentyl glycol, can be used other than ethylene glycol, for example. In particular, it is preferable to use ethylene glycol.

  The viscosity of the polyester composition constituting the polyester film of the present invention: IV [dl / g] is usually 0.48 to 0.75, preferably 0.50 to 0.70, more preferably 0.52 to 0, respectively. .67. When the IV value is less than 0.48, the heat resistance, mechanical strength, and the like, which are excellent characteristics of the polyester film when used as a film, tend to be inferior. Moreover, when IV value exceeds 0.75, there exists a tendency for the negative in the extrusion process at the time of polyester film manufacture to become large too much, and there exists a possibility that productivity may fall.

  The phosphorus content P in the polyester film of this invention is calculated | required by XRF mentioned later. The range of the phosphorus content P is 0.30 to 2.00% by weight, preferably 0.50 to 1.40% by weight, and more preferably 0.60 to 1.20% by weight. When the phosphorus content P is less than 0.30% by weight, flame retardancy is not exhibited. On the other hand, if P is more than 2.00% by weight, breakage in the tenter frequently occurs, and even if it becomes a film, the flame retardancy is good, but the mechanical strength and bleed resistance are greatly reduced, which is preferable. Absent.

  In the present invention, a flame retardant compound represented by the following chemical formula (1) is used.

（上記化合物の平均分子量は１１７０以上である）

(The average molecular weight of the compound is 1170 or more)

  The organophosphorus compound represented by the chemical formula (1) contains a phosphorus atom in the molecule, and the lower limit of the average molecular weight by GPC measurement is 1170, preferably 2290, more preferably 3410. If the average molecular weight is less than 1170, volatilization of the organophosphorus compound during film formation, inhibition of crystallization of the polyester resin, and further bleed-out of the organophosphorus compound lead to a decrease in mechanical strength. The upper limit of the average molecular weight is not particularly specified, but it is considered that dispersibility of the compound (1) in the resin is inhibited by excessively increasing the molecular weight. In addition, the synthesis method (production example) of the compound (1) will be described later.

  In the present invention, a method of directly adding a flame retardant compound during production of the polyester film is preferred. Moreover, when manufacturing the flame-retardant polyester film used, it does not specifically limit about the method of adding the said flame-retardant compound to a polyester film manufacturing system. This is because when a flame-retardant compound having a lower softening point is copolymerized at the time of polyester polymerization, the melting point (Tm) of the polyester may be lowered. Along with this, the mechanical properties and heat resistance are concerned, so this method was used. On the other hand, the flame retardant compound (1) has a structure having a certain number of repeating units. Therefore, it has an appropriate molecular weight and dispersibility within the resin, and it is presumed that the movement to the film surface was further suppressed.

The fine inert particles used in the present invention are preferably particles having an average particle diameter of 0.5 to 3.0 μm, and further an average particle diameter of 0.8 to 2.0 μm. When the average particle size is less than 0.5 μm, the winding property of the film is inferior and the workability tends to be deteriorated. On the other hand, if the average particle size exceeds 3.0 μm, the flatness and / or transparency of the film surface may be impaired.
Moreover, the addition amount of particle | grains is 0.005-0.5 weight%, Furthermore, the range of 0.01-0.1 weight% is preferable. When the added amount of the particles is less than 0.005% by weight, the winding property of the film is inferior and the workability tends to be deteriorated. On the other hand, if the added amount of particles exceeds 0.5% by weight, the roughness of the film surface becomes too large, and the transparency of the film may be impaired.

  Examples of inert particles include aluminum oxide, silicon oxide, titanium oxide, silicon nitride, boron nitride, calcium carbonate, magnesium carbonate, barium carbonate, calcium sulfate, barium sulfate, calcium phosphate, lithium phosphate, magnesium phosphate, fluoride Lithium, zeolite, celite, kaolin, talc, carbon black, and crosslinked polymer fine powders as described in JP-B-59-5216 can be exemplified, but of course not limited thereto. At this time, the inert particles to be blended may be a single component, or two or more components may be used simultaneously.

  In the present invention, the method of adding inert particles or the like to the polyester is not particularly limited, but a method of adding in a polymerization step, a method of kneading particles in advance using an extruder, and making a masterbatch, etc., are particularly preferable. The method is a method in which particles are directly added and mixed in an extrusion process in the film manufacturing process. As the extruder at that time, a twin screw extruder with a vent is preferable. Further, in order to improve the dispersion of particles, a different-direction twin-screw extruder is preferable to a same-direction twin-screw extruder.

  In addition, the polyester film of the present invention is preferably one in which the extruded layer is stretched and heat-fixed biaxially by a co-extrusion method in which all layers are co-melt extruded from the die. As a method for co-melt extrusion, either a feed block type or a multi-manifold type may be used. Then, although the manufacturing method of the polyester film of this invention is demonstrated more concretely, as long as the structural requirements of this invention are satisfied, it is not specifically limited to the following illustrations.

  First, a polyester containing a flame retardant compound and, if necessary, inert particles is supplied to separate melt extrusion apparatuses, and heated to a temperature equal to or higher than the melting point of the polymer to be melted. Next, the molten polymer is bonded and laminated in an extrusion die in a laminar flow and extruded from a slit die. And it cools and solidifies so that it may become the temperature below a glass transition temperature on a rotary cooling drum, and the non-oriented sheet of a substantially amorphous state is obtained. In this case, in order to improve the flatness of the sheet, it is preferable to improve the adhesion between the sheet and the rotary cooling drum. In the present invention, an electrostatic application adhesion method and / or a liquid application adhesion method is employed.

In the present invention, the sheet obtained by such a method is stretched biaxially to form a film. Specifically describing stretching conditions, the unstretched sheet is stretched 2 to 6 times in the longitudinal direction at 70 to 145 ° C. to form a longitudinally uniaxially stretched film, and then a coating solution is applied to at least one side of the film. It is preferable that the film is dried or undried, stretched 2 to 6 times in the transverse direction at 90 to 160 ° C., and heat-treated at 150 to 250 ° C. for 1 to 600 seconds. At this time, a method of relaxing 0.1 to 20% in the longitudinal direction and / or the transverse direction in the maximum temperature zone of the heat treatment and / or the cooling zone at the outlet of the heat treatment is preferable. Further, it is possible to add re-longitudinal stretching and / or re-lateral stretching as necessary.
The total thickness D [μm] of the polyester film of the present invention is usually 20.0 to 100.0 μm. When the total thickness of the film is less than 20.0 μm, the specific surface area is large, and thus flame retardancy is not exhibited. On the other hand, if it is thicker than 100.0 μm, it is difficult to satisfy the demand for downsizing the battery.

  The melting point of the polyester film of the present invention is 247 ° C. or higher based on the DSC measurement described later. Preferably it is 249 degreeC or more, More preferably, it is 250 degreeC or more. When the melting point is less than 247 ° C., the physical properties when exposed to a high thermal environment are lowered. Although there is no particular upper limit for the melting point, 260 ° C. is a realistic value.

  When the polyester film of the present invention is used for a battery label, printing with ink is performed to indicate the name of the battery. In this case, since the polyester film is generally inactive, the printability is poor, and it is preferable to provide a coating layer in advance in order to improve the adhesion with the print layer.

  As a method for forming the coating layer, a so-called in-line coating method in which coating is performed before the tenter entrance (before completion of orientation crystallization) and drying in the tenter is preferable. At this time, the application may be performed on one side or both sides.

  In the polyester film of the present invention, the coating layer formed on the biaxially stretched polyester film mainly comprises a combination of various binder resins and a crosslinking agent. As the binder resin, a polyester resin is preferably used from the viewpoint of adhesiveness / flame retardancy, and a combination of a polyester resin and a urethane resin is more preferable.

  The amount of the polyester-based resin in the coating agent is usually 10 to 80% by weight, preferably 15 to 75% by weight. When the blending amount of the polyester resin is less than 10% by weight, the other binder components are relatively increased, which is not preferable from the viewpoint of flame retardancy. Moreover, since it exists in the tendency for adhesiveness with ink to become inadequate when it exceeds 85 weight%, it is unpreferable.

The type of polyurethane resin in the coating agent is not limited, but a polycarbonate polyurethane resin is preferable. A compounding quantity is 5 to 75 weight% normally, Preferably it is the range of 10 to 70 weight%. When the blending amount of the polyurethane resin is less than 5% by weight, the adhesion with the ink may be insufficient. On the other hand, if it exceeds 75% by weight, the amount of the polyester resin is relatively reduced, which is not preferable from the viewpoint of flame retardancy.

  As the crosslinking agent resin, melamine-based, epoxy-based, and oxazoline-based resins are used, and melamine-based resins are particularly preferable from the viewpoints of flame retardancy and ink adhesion. The melamine resin is not particularly limited, but melamine, a methylolated melamine derivative obtained by condensing melamine and formaldehyde, a compound partially or completely etherified by reacting methylolated melamine with a lower alcohol, And a mixture thereof can be used.

  Moreover, as a melamine type resin, any of the condensate which consists of a monomer and / or a multimer more than a dimer may be sufficient.

  As the lower alcohol used for the etherification, methyl alcohol, ethyl alcohol, isopropyl alcohol, n-butanol, isobutanol and the like are preferable. In addition, the functional group has an imino group, a methylol group, or an alkoxymethyl group such as a methoxymethyl group or a butoxymethyl group in one molecule, an imino group type methylated melamine resin, a methylol group type melamine resin, A methylol group type methylated melamine resin, a completely alkyl type methylated melamine resin, or the like can be used. Among these, methylolated melamine resin is particularly preferable. Furthermore, an acidic catalyst such as p-toluenesulfonic acid can be used to accelerate the thermal curing of the melamine-based crosslinking agent.

  The compounding quantity of the melamine resin in a coating agent is 1 to 50 weight% normally, Preferably it is 5 to 30 weight%, More preferably, it is the range of 7 to 15 weight%. When the blending amount of the crosslinking agent resin is less than 1% by weight, the durable adhesiveness may not be sufficiently exhibited, and the effect of improving the solvent resistance may be insufficient. On the other hand, if it exceeds 50% by weight, the binder resin is relatively decreased, and sufficient flame retardancy may not be exhibited, which is not preferable.

  In the present invention, it is preferable to contain inorganic particles or organic particles in the coating layer in order to improve the slipperiness and adhesion of the film.

  The compounding amount of the particles in the coating agent is usually 0.2 to 10% by weight, preferably 0.5 to 5% by weight. When the blending amount of the particles to be added is less than 0.2% by weight, the blocking resistance may be insufficient. On the other hand, if it exceeds 10% by weight, the function of blocking resistance is saturated, which is not preferable.

  Examples of the inorganic particles include zirconium oxide, titanium oxide, barium oxide, antimony oxide, calcium carbonate, silicon dioxide, molybdenum sulfide, alumina, carbon black, kaolin, and talc. Among these, silicon dioxide is easy to use because it is inexpensive and has various particle sizes.

  Examples of the organic particles include polystyrene or polyacrylate polymethacrylate in which a crosslinked structure is achieved by a compound (for example, divinylbenzene) containing two or more carbon-carbon double bonds in one molecule.

  The above inorganic particles and organic particles may be surface-treated. Thus, examples of the surface treatment agent include a surfactant, a silane coupling agent, a titanium coupling agent, and a polymer as a dispersant.

  Moreover, the coating layer may contain a thickener, an antioxidant, an ultraviolet absorber, an antistatic agent, an antifoaming agent, a coating property improving agent, a foaming agent, a dye, a pigment, and the like.

  As long as water is the main medium, the coating agent may contain a small amount of an organic solvent for the purpose of improving dispersion in water or improving the film-forming performance. The organic solvent is preferably used as long as it is soluble in water. Examples of the organic solvent include aliphatic or alicyclic alcohols such as n-butyl alcohol, n-propyl alcohol, isopropyl alcohol, ethyl alcohol, and methyl alcohol, glycols such as propylene glycol, ethylene glycol, and diethylene glycol, n-butyl cellosolve, Examples include glycol derivatives such as ethyl cellosolve, methyl cellosolve, propylene glycol monomethyl ether, ethers such as dioxane and tetrahydrofuran, esters such as ethyl acetate and amyl acetate, ketones such as methyl ethyl ketone and acetone, and amides such as N-methylpyrrolidone. Can be mentioned. These organic solvents may be used alone or in combination of two or more.

  As a coating method of the coating agent, for example, reverse roll coater, gravure coater, rod coater, air doctor coater or the like other than those shown by Yuji Harasaki, Tsuji Shoten, published in 1979, “Coating Method” A coating device can be used.

The coating layer may be formed on one side of the polyester film or on both sides as necessary.
When formed only on one side, other characteristics can be imparted by forming a coating layer different from the above-mentioned coating layer on the opposite surface as necessary. In addition, in order to improve the applicability and adhesion of the coating agent to the film, the film may be subjected to chemical treatment or electric discharge treatment before application, and furthermore, in order to improve the surface characteristics, the electric discharge treatment is performed after forming the coating layer. You may give it.

  The thickness of the coating layer is usually in the range of 0.010 to 0.300 μm, preferably 0.015 to 0.100 μm, and more preferably 0.020 to 0.080 μm as the dry thickness. When the thickness of the coating layer is less than 0.010 μm, the adhesion with the ink is not sufficient. On the other hand, if the thickness of the coating layer exceeds 0.300 μm, the flame retardancy tends to be poor.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to a following example, unless the summary is exceeded. The physical property measurement method used in the present invention is shown below.

(1) Evaluation of film-forming property When the amorphous sheet was stretched in the horizontal direction after being stretched, the state in which the film was broken at the time of stretching in a transverse stretching machine (tenter) was evaluated based on the following three rank criteria.
○: Almost no film breakage and good productivity Δ: Occasionally film breakage and poor productivity ×: Always breakage, no productivity at all

(2) Film thickness D [μm]
Measured with a micrometer.

(3) Phosphorus element amount P [wt%]
XRF: The amount of elements in the film was determined by single-sheet measurement under the conditions shown in Table 1 below using a fluorescent X-ray analyzer (model “XRF-1800” manufactured by Shimadzu Corporation).

(4) Melting point (Tm)
The polyester film was 10 ° C./min. With DSC type 7 manufactured by Perkin Elma. The endothermic peak temperature due to crystal melting obtained at the rate of temperature rise was defined as the melting point (Tm).

(5) Flame retardance A UL94VTM test was conducted according to the vertical combustion test method of UL94, a flammability test standard for plastic materials issued by Underwriters Laboratories. The evaluation targets are the accepting state (23 ° C./50% RH / 48 h) and after aging (after 70 ° C./168 h). Regarding the evaluation criteria, this test method varies in the combustion test evaluation results, and the UL follow-up service provides up to three opportunities. A series of evaluation operations was performed three times. Below, a flame-retardant evaluation procedure ([1]-[5]) is demonstrated.
[1] Prepare 30 test pieces according to UL94 VTM test.
[2] Select 10 randomly from [1] above.
[3] A UL94VTM test is performed on five test pieces, and the test ends when the test passes VTM-0. If it is unacceptable, the UL94VTM test is performed on the remaining five test pieces to determine whether the VTM-0 is acceptable or not.
[4] Repeat the above steps [1] to [2] three times.
[5] The UL94VTM test results obtained in [2] are evaluated. The evaluation criteria are as follows.
◎: Passed VTM-0 three times ○: Passed VTM-0 twice △: Passed VTM-0 once ×: Passed all VTM-0

(6) Adhesiveness UV curable ink was applied to the coating layer of the film and cured, and then the adhesiveness was determined. Details are as follows.
Ink type:
FD Carton ACE Aiguchi / Sumiguchi (Tokyo Ink Co., Ltd.)
Application conditions:
The film was applied to a thickness of about 2 μm using an offset printing test machine “RI Tester RI-2 (manufactured by Meisei Seisakusho)”.
Curing conditions:
Curing was performed with a UV irradiation apparatus “UVC-402 / 1HN: 302 / 1MH (manufactured by USHIO INC.)” Under the conditions of a mercury lamp output of 120 W / cm, a line speed of 15 m / min, and a lamp-film interval of 150 mm.
Adhesion judgment:
A crosscut is made on the obtained film surface so that the fifth is 100 pieces in a 1-inch width, and a rapid peel test is immediately performed on the same part using a cello tape (registered trademark), and the adhesiveness is evaluated from the peeled area. did. Judgment criteria are as follows.
◎: More than 80% remaining ○: More than 60% less than 80% △: More than 40% remaining less than 60% ×: Less than 40% remaining

The flame retardant compounds used in the following Examples and Comparative Examples, and methods for producing polyester raw materials are as follows. In the examples, “%” represents “% by weight” unless otherwise specified.
≪Flame retardant compound: Organophosphorus compound (Chemical formula (1)) ≫
9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (the following chemical formula (2)) was added to a 3 L glass flask equipped with a stirrer, thermometer, gas inlet, and distillation port. ) 7.8 mol and 25.97 mol of ethylene glycol were added and the flask was heated until the temperature of the contents reached 100 ° C. to dissolve the components. Next, 7.96 mol of itaconic acid was added with stirring, and the flask was heated from the distillation port through a vacuum device in a vacuum state of 30 Torr to bring the contents to a boil. At this point, the produced water was removed by adjusting the distillation rate of the distillation port. Furthermore, while maintaining the boiling state of the contents, the temperature in the flask was raised, and the degree of vacuum was also lowered accordingly. As a breakdown, it took 4 hours for the temperature of the contents to reach 185 ° C., and the degree of vacuum at this point was 430 Torr. Further, the heating was continued, and finally the contents were heated until the temperature reached 200 ° C. After confirming this point, nitrogen gas was blown into the reactor to return the flask to normal pressure. The reaction mixture is an ethylene glycol solution of the following chemical formula (3). Moreover, the solid compound of the following chemical formula (3) can be purified by removing ethylene glycol under reduced pressure.

Subsequently, 130 g of ethylene glycol containing 0.33 g of antimony trioxide (Sb ₂ O ₃ ) and zinc acetate dihydrate [(AcO) ₂ Zn · 2H ₂ O] was added into the flask. The inside of the flask was maintained at 200 ° C., and the degree of vacuum was gradually increased to obtain a vacuum state of 1 Torr or less. Furthermore, the temperature of the content was raised to 220 ° C., and the point at which the distillation of ethylene glycol was extremely reduced was determined as the reaction end point. After confirming this point, the organic phosphorus compound (1), which is a yellowish transparent glassy solid, was obtained by solidifying the contents in a SUS container while pressurizing the contents with nitrogen gas.

  By repeating the above operation, the necessary amount of the organophosphorus compound (1) to be added in Examples and Comparative Examples described later was secured.

  Regarding this organophosphorus compound (1), the weight-average molecular weight (Mw) was 6,800 from GPC analysis of the product. In the analysis, a peak in a low molecular weight region, which was estimated to be an acid anhydride of a compound represented by the following chemical formula (4) or a cyclic ester of compound (4) and ethylene glycol, was also observed. In addition, the XRF measurement showed that the phosphorus content P [wt%] was 8.31%. Therefore, the average value of n of the organophosphorus compound (1) corresponded to 18.1.

<< Manufacture of polyester A >>
Using 100 parts by weight of dimethyl terephthalate and 60 parts by weight of ethylene glycol as starting materials, 0.02 part of magnesium acetate tetrahydrate as a catalyst is placed in the reactor, the reaction start temperature is set to 150 ° C., and the reaction is gradually carried out as methanol is distilled off. The temperature was raised to 230 ° C. after 3 hours. After 4 hours, the transesterification reaction was substantially terminated. After adding 0.03 part of ethyl acid phosphate to this reaction mixture, it moved to the polycondensation tank, added 0.04 part of antimony trioxide, and performed polycondensation reaction for 4 hours. That is, the temperature was gradually raised from 230 ° C. to 280 ° C. On the other hand, the pressure was gradually reduced from normal pressure, and finally 0.3 mmHg. After the start of the reaction, the reaction is stopped at a time corresponding to an intrinsic viscosity of 0.66 due to a change in the stirring power of the reaction tank, the polymer is discharged under nitrogen pressure, extracted into a strand, cooled with water, and cut with a cutter. Polyester resin pellets (prepolymer) were produced. The polyester resin pellet (prepolymer) was used as a starting material, and solid phase polymerization was performed at 220 ° C. under vacuum to obtain pellet A of polyester A. The intrinsic viscosity of the obtained polyester was 0.85.

≪Manufacture of polyester B≫
Polyester A and a flame retardant compound (organophosphorus compound (1)) were compounded at a ratio of 50:50 with a vented twin screw extruder to obtain a flame retardant compound MB.

≪Polyester C production≫
In the production of polyester A prepolymer (intrinsic viscosity 0.66), after completion of transesterification, a flame retardant compound represented by the following chemical formula (3), 10- [2,3-di (2-hydroxyethoxy) carbonylpropyl -9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide is added to the polymer chain so that the amount of phosphorus element is 3.00% by weight. Polyester C was obtained in the same manner as the prepolymer. The viscosity of the obtained polyester was 0.61. A conceptual diagram of polyester C is shown in chemical formula (5).

≪Production of polyester D≫
In the production of polyester C, polyester D was obtained in the same manner as polyester C, except that the amount of flame retardant compound added was 1.50 wt% of the amount of phosphorus element relative to the polymer chain. The viscosity of the obtained polyester was 0.63.

≪Manufacture of polyester E≫
In the production of a prepolymer of polyester A (intrinsic viscosity 0.66), the same method as the prepolymer of polyester A, except that 0.1 part by weight of silica particles having an average particle size of 2.30 μm is blended after the end of transesterification Polyester E was obtained. The viscosity of the obtained polyester was 0.66.

≪Manufacture of polyester F≫
Polyester A and a solid flame retardant compound (chemical formula (3)) were compounded at a ratio of 50:50 by a twin screw extruder with a vent to obtain a flame retardant compound MB.

Further, the raw material components of the water-based paint applied before completion of the orientation crystallization used in the following Examples and Comparative Examples, and the composition of the water-based paint are as follows.

<< Ingredients for water-based paint >>
Aqueous component a
Aqueous dispersion aqueous component of a polyester resin having a molar ratio of terephthalic acid / isophthalic acid / sulfoisophthalic acid / ethylene glycol / 1,4-butylene glycol = 27.5 / 20 / 2.5 / 32.5 / 17.5 b
A prepolymer comprising a molar ratio of isophorone diisocyanate / modified polyhexamethylene carbonate / polyoxytetramethylene glycol / pentaethylene glycol / dimethylolpropanoic acid = 10 / 61.8 / 4.2 / 7.5 / 16.5, Water dispersion aqueous component c of polyurethane resin neutralized with triethylamine and chain-extended with isophoronediamine and having a Tg (glass transition temperature) of −20 ° C.
Melamine: J-101 (manufactured by DIC)
Aqueous component d
Silica sol aqueous dispersion aqueous component e having an average particle size of 0.07 μm
Surfactant: Neugen TDX-50 (Daiichi Kogyo Seiyaku Co., Ltd.)
A water-based paint was prepared by blending the above components with the formulation shown in Table 2 below.

Example 1:
A blend raw material of polyester A / polyester B / polyester E = 66/29/5 was fed into an extruder set at 280 ° C. Here, a twin screw extruder in the same direction was used as the extruder. Extruder polymer is extruded into a sheet form from the die through a gear pump and a filter, and rapidly cooled and solidified using an electrostatic cooling method with a rotating cooling drum whose surface temperature is set to 30 ° C. Got the sheet. The obtained amorphous sheet was stretched 3.3 times in the longitudinal direction at 83 ° C., and then the aqueous paint I described above was applied to a coating thickness of 0.030 μm. The film was stretched 0 times and heat-treated at 220 ° C. to obtain a biaxially stretched polyester film having a layer thickness of 36 μm. The evaluation results are shown in Table 3 below.

Examples 2-3:
A biaxially stretched polyester film was obtained in the same manner as in Example 1 with respect to the raw material blending ratio and film thickness shown in Table 2 below. The evaluation results are shown in Table 3.

Example 4:
The blend raw material of polyester A / polyester B = 78/22 was fed to the main extruder set at 280 ° C., and the blend raw material of polyester A / polyester B / polyester E = 73/22/5 was set to 280 ° C. It was sent to the extruder. Here, both the main and sub extruders used twin-screw extruders in the same direction. The discharge amount ratio per unit time was set to main: sub = 80: 20. Except for the above, a biaxially stretched polyester film was obtained in the same manner as in Example 3. The evaluation results are shown in Table 3.

Examples 5-7:
A biaxially stretched polyester film was obtained in the same manner as in Example 1 with respect to the raw material blending ratio and film thickness shown in Table 2 below. The evaluation results are shown in Table 3.

Examples 8 and 9:
A biaxially stretched polyester film was obtained in the same manner as in Example 1 except that the coating thickness of the aqueous paint I was set to the thickness shown in Table 2. The evaluation results are shown in Table 3.

Examples 9 and 10:
A biaxially stretched polyester film was obtained in the same manner as in Example 1 except that the coating material was of the type / thickness of the aqueous coating material shown in Table 3. The evaluation results are shown in Table 3.

Comparative Example 1:
A biaxially stretched polyester film was obtained in the same manner as in Example 1 with respect to the raw material blending ratio and film thickness shown in Table 4 below. The evaluation results are shown in Table 4.

Comparative Example 2:
A study was conducted to obtain a biaxially stretched polyester film by the same method as in Example 1 so that the film thickness was 75 μm at the raw material blending ratio shown in Table 4, but breakage occurred frequently in the tenter, and the film formation was abandoned. did. The amount of phosphorus was obtained by measuring film fragments after rupture with XRF. However, the film was so deformed that flame retardancy could not be evaluated.

Comparative Examples 3-6:
A biaxially stretched polyester film was obtained in the same manner as in Example 1 with respect to the raw material blending ratio and film thickness shown in Table 4. The evaluation results are shown in Table 4.

Comparative Example 7:
An attempt was made to obtain a biaxially stretched polyester film in the same manner as in Example 1 with respect to the raw material blending ratio and film thickness shown in Table 4. However, when the polyester film was produced, when the kneaded material came out of the die, smoke was confirmed, so that the film could not be collected. Here, the organophosphorus compound (3) added to the polyester film in this comparative example is a compound having a lower molecular weight than the monomer body without the repeating unit, that is, the organophosphorus compound (1). . Therefore, it is estimated that a part or most of the added organophosphorus compound (3) is volatilized by heating and kneading at the time of producing the ester F or polyester film.

Comparative Example 8:
A biaxially stretched polyester film was obtained in the same manner as in Example 1 except that the aqueous paint was not applied. The evaluation results are shown in Table 4.

  The polyester film of the present invention can be suitably used in many applications such as packaging materials, electrical insulating materials, metal vapor deposition materials, plate making materials, magnetic recording materials, display materials, transfer materials, and window pasting materials.

Claims (2)

It is a polyester film having a thickness of 20 to 100 μm containing a compound represented by the following chemical formula (1), a phosphorus content in the polyester film is 0.30 to 2.00% by weight, and a melting point of 247 ° C. or higher. A polyester film having (Tm) and having a coating layer containing a polyester component in the film production process.

(The average molecular weight of the compound is 1170 or more) The polyester film according to claim 1, which is a coating layer containing a urethane component and a melamine resin as a crosslinking agent.