JP2010229371A - Polyester film for molded member and method for molding - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polyester film for a molded member, of which the moldability, productivity, and molding cycle are improved by improving the rate of temperature increase of the polyester film and which has beautifulness of appearance after molding. <P>SOLUTION: The polyester film for the molded member has a minimum number of transmission of 80% or lower at a wavelength of 700-2,500 nm and a melting point of 240-260°C. After the film is heated with an infrared heater for 180 sec, the rupture stress of the film in both of the longer direction and the width direction is 40 MPa or higher and lower than 100 MPa. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a polyester film for molded members, and more particularly to a polyester film for molded members that can be suitably used for a decorative sheet for molding, a surface protective sheet during molding, and the like.

  In recent years, there is a strong movement to use decorative sheets as molded substitutes for building materials, automobile parts, mobile phones, electrical appliances, and the like. At the time of molding, a method is generally used in which a decorative sheet is heated to a predetermined temperature using an infrared heater, a halogen heater, or the like, and vacuum forming, vacuum / pressure forming, plug assist molding, or the like is performed.

  In the case of molding using an infrared heater, since polyester absorbs infrared light, it takes time to reach the target temperature, resulting in low productivity.

  Under such circumstances, in the field of polyester bottles, there has been a proposal to use a composition containing an infrared absorbing agent in polyester in order to crystallize a stopper part that requires crystallization time in a short time. (For example, refer to Patent Document 1). However, in this proposal, since the amount of the infrared absorbent added to the polyester is small, there is a problem that sufficient absorption characteristics cannot be obtained when the film is formed. On the other hand, a film to which a large amount of infrared absorber is added improves the infrared absorption performance, but the surface of the molded member is roughened due to foreign matters due to the low heat resistance of the infrared absorber. There exists a problem that an external appearance is impaired (for example, refer patent document 2 and patent document 3).

JP 2005-105190 A JP 2002-286929 A JP-A-2005-120126

  An object of the present invention is to eliminate the above-described problems. That is, the present invention provides a polyester film for a molded member that improves moldability, productivity, and molding cycle by improving the temperature rising rate of the molded film, and further has a beautiful appearance after molding. With the goal.

In order to achieve the above object, the present invention has the following configuration.
(1) A polyester film having a minimum transmittance of 80% or less at a wavelength of 700 to 2500 nm and a melting point of 240 to 260 ° C., and the film breaks after heating the film with an infrared heater for 180 seconds A polyester film for a molded member having a stress of 40 or more and less than 100 MPa in both the longitudinal direction and the width direction.
(2) The polyester film for molded members according to (1), wherein the film temperature after heating for 180 seconds with an infrared heater exceeds 100 ° C.
(3) The polyester film for molded members according to (1) or (2) above, containing 0.1 to 5% by weight of infrared absorbing particles.
(4) The polyester film for molded members according to any one of (1) to (3), wherein the infrared absorbing particles have an average particle diameter of 10 to 150 nm.
(5) The molded member according to (3) or (4), wherein the infrared absorbing particles are one or more particles selected from the group consisting of indium particles, lanthanum particles, antimony particles, and zinc compound particles. Polyester film.
(6) A film comprising a polyester resin composition containing a polyethylene terephthalate resin (a) and a polybutylene terephthalate resin (b), and the resin (a) content in the resin composition The amount is 65 to 90% by weight based on the total amount of the resin (a) and the resin (b), and the content of the resin (b) is based on the total amount of the resin (a) and the resin (b). The polyester film for molded members according to any one of (1) to (5), wherein the polyester film is a film formed using a polyester-based resin composition mixed at 10 to 35% by weight.
(7) A method for forming a polyester film for molded members, wherein the polyester film for molded members according to any one of (1) to (6) is heated by an infrared heater and molded,
It is.

  The polyester film for molded members of the present invention improves productivity and molding cycle by selectively promoting heat absorption only for a film having a certain film melting point containing infrared absorbing particles, and further, after molding The beauty of the appearance can be provided.

In the present invention, the polyester film for molded members is laminated in order to prevent a deterioration in the external shape of the molded member due to a polyester film used in the decorative sheet body for molding, or scratches at the time of forming the molded member. It can be suitably used for a polyester film used as a protective sheet.

  The polyester film for molded members of the present invention is a polyester film having a minimum transmittance of 80% or less at a wavelength of 700 to 2500 nm and a melting point of 240 to 260 ° C., and the film is heated with an infrared heater for 180 seconds. The breaking stress of the heated film is characterized in that both the longitudinal direction and the width direction are 40 or more and 100 MPa or less. Hereinafter, this point will be described in more detail.

  In the polyester film for molded members of the present invention, it is important that the minimum transmittance at a wavelength of 700 to 2500 nm is 80% or less from the viewpoint of improving moldability, productivity, and molding cycle. In general, when molding a member using resin as a main component, thermal processing is used, and the heating method at the time of molding is a near infrared heater that emits a wavelength of 700 to 2500 nm and a wavelength of 4000 to 10,000 nm. Being heated by both far infrared heaters. That is, since the polyester film for molded members of the present invention is molded in a state of being laminated together with other resins in the heating method, the polyester film of the present invention is selectively heated. An increase in the heating rate can be expected.

  Moreover, if the minimum value of the transmittance in this infrared wavelength region is higher than 80% for the above reasons, the temperature rise by infrared irradiation is insufficient, and the effect of improving the moldability, productivity, and molding cycle is inferior. It is not preferable. In the present invention, it is important that it is 80% or less, preferably 70% or less, more preferably 60% or less. As a polyester film for a molded member, the lower limit is preferably 0% in order to improve the rate of temperature increase, but when laminated and integrally molded on a resin member, the infrared wavelength from the film side is cut. As a result, the heating uniformity of the resin member may be adversely affected.

  Moreover, it is important that the polyester film for molded members of the present invention has a melting point in the range of 240 to 260 ° C. in terms of productivity, moldability, and appearance after processing. If the temperature is less than 240 ° C, the heat resistance is inferior, and there is a concern about the deterioration of the peelability of the protective film due to the adhesion of the protective film to the main body resin in the molding process, and whitening of the film is recognized during the secondary processing of the film to be thermoformed. May be. Conversely, if it exceeds 260 ° C, it tends to cause wrinkling during processing, and the breaking stress of the film due to thermal processing cannot follow flexibly, and the appearance of the molded member may be deteriorated. The temperature is preferably in the range of 240 ° C to 255 ° C, more preferably 240 ° C to 250 ° C.

  Here, as will be described later, the melting point of the polyester film is measured using a differential scanning calorimeter (DSK7 manufactured by PERKIN-ELMER) at a temperature of 30 to 300 ° C. and a heating rate of 20 ° C./min. The endothermic peak that appears due to the melting phenomenon at the time of conducting was taken as the melting point. When a polyester resin having a different composition is blended and used as a film, a plurality of endothermic peaks due to melting may appear.In this case, the endothermic peak temperature appearing at the highest temperature is the melting point of the polyester film of the present invention. And

  As described later, the transmittance in the infrared wavelength region is measured by attaching a φ60 integrating sphere 130-0632 (Hitachi Ltd.) and a 10 ° inclined spacer to a spectrophotometer (U3410 Spectrophotometer) manufactured by Hitachi, Ltd. Was measured. The bandpass is set to 2 nm / servo, the gain is set to 3, and the range from 700 nm to 2500 nm is 120 nm / min. The scanning speed was measured. Moreover, as a standard white board, it measured using the thing attached to U3410.

  Furthermore, in the polyester film for molded members of the present invention, from the viewpoint of moldability and appearance, the breaking stress of the film after heating the film with an infrared heater for 180 seconds is 40 to less than 100 MPa in both the longitudinal direction and the width direction. It is important that the pressure is 45 to 95 MPa, more preferably 50 to 90 MPa. If the breaking stress is less than the above range, it may not be able to withstand the tension for transferring the film in the preheating process such as molding, and the film may be deformed or broken in some cases. May be lost. On the other hand, when the pressure is 100 MPa or more, the deformation is insufficient at the time of thermoforming, and the follow-up to the molding die is so sweet that it cannot be used as a molded member. A method for measuring the breaking stress (MPa) will be described below.

  The film was cut into a short shape having a length of 150 mm and a width of 10 mm in the longitudinal direction and the width direction to prepare a sample. Using a tensile tester (Orientec Tensilon UCT-100), the tensile test was performed in the longitudinal direction and the width direction of the film at an initial tensile chuck distance of 50 mm and a tensile speed of 300 mm / min. For measurement, the chucked film sample was placed so as to be parallel to the film surface 300 mm before the near infrared output port using a near infrared heat beam line condensing type (HYL20-11M manufactured by Hybec Co., Ltd.) A tensile test was performed after heating for 180 seconds in a 25 ° C. environment. The load applied to the film when the sample broke was read, and the value divided by the cross-sectional area (film thickness × 10 mm) of the sample before the test was taken as the breaking stress value. The measurement was performed five times for each sample and in each direction, and the average value was taken as the measured value.

Furthermore, in the polyester film for molded members of the present invention, the film temperature after heating for 180 seconds with an infrared heater is preferably more than 100 ° C, more preferably more than 105 ° C, and most preferably from the viewpoint of productivity and moldability. Is above 110 ° C. On the other hand, when the temperature exceeds 200 ° C., it is not preferable for processing because wrinkles are generated in the film. Therefore, it is preferable to adjust the type and content of the infrared absorber contained in the film so as to be 200 ° C. or less.
This is because the film productivity is improved by increasing the temperature of the film at the time of forming, that is, by increasing the temperature rising rate of the film, and further, forming according to the processing requirements can be performed within the time.

  The method for measuring the film temperature after heating for 180 seconds with an infrared heater is described below.

  A heat label (made by Micron Co., Ltd.) is attached to the film sample, and a near-infrared heat beam line condensing type (HYL20-11M made by Hybeck Co., Ltd.) is used as an infrared heater 300 mm from the near-infrared output port. The film temperature was defined as the label display temperature after fixing the film surfaces to be parallel and heating for 180 seconds in a 25 ° C. environment. The heat label was attached to the film surface on the infrared heater side.

  In order to make the polyester film for molded members of the present invention into the above-described film, it can be achieved by containing infrared absorbing particles in a polyester film having a certain melting point.

  As the infrared absorbing particles used in the present invention, lanthanum particles, antimony particles, indium particles, zinc particles, imonium particles, diimonium particles, phthalocyanine particles, aminium particles, and polymethine particles are preferably used. Of course, it is not limited to this. Use of these infrared absorbing inorganic particles is preferable because infrared rays can be efficiently absorbed. Among these, lanthanum hexaboride, antimony-added tin oxide, zinc oxide (ZnO), and indium-added tin oxide (ITO) are more preferably used, and lanthanum hexaboride is most preferable. The lanthanum hexaboride fine particles are green powder, but when fine particles having a sufficiently small particle diameter compared with the visible light wavelength are dispersed, visible light transmission occurs and infrared light is shielded. This is presumably because this material has many free electrons, and interband transition between 4f-5d and absorption due to electron-electron and electron-phonon interaction exist in the near infrared region. Further, when these particles are used in a mixture of not only one type but also several types, it becomes possible to absorb infrared rays in a wider wavelength range, which is more preferable.

  The content of the infrared absorbing particles is preferably 0.1 to 5% by weight with respect to the entire film. When the amount is less than 0.1% by weight, the infrared absorption ability of the present invention is insufficient, and the temperature rising rate during the molding process tends to be low. In addition, if the rate of temperature rise is low, the time for the film to start warming is slow, and in the molding process when the molding start temperature is fixed, it takes time to reach the set temperature required during molding. The cycle is extended and productivity is reduced. In addition, in the case of a process in which the molding heating time is determined, since the temperature rise of the film is insufficient, the stress at the time of molding becomes high, wrinkles and insufficient molding occur, and the appearance of the molded member deteriorates. End up. Conversely, when the content of the infrared absorbing particles exceeds 5% by weight, the infrared ray collecting ability is increased, but the surface of the film tends to be roughened, so that it is used for the decorative sheet body for molding. In order to deteriorate the appearance of the molded member itself, when used as a protective sheet, the surface of the film is transferred, so that the appearance is deteriorated as in the case of the decorative sheet body for molding. It is not preferable. A more preferable range of this content is 0.2 to 4% by weight, and further preferably 0.3 to 3% by weight.

  Furthermore, the average particle diameter of the infrared absorbing particles of the present invention is preferably 10 to 150 nm. When the thickness is lower than 10 nm, the infrared absorption ability tends to be reduced, and the rate of temperature increase is reduced. If it exceeds 150 nm, the dispersibility is poor, and thus the temperature rise rate varies, and it is not preferable because it cannot be optimized for a predetermined processing step. The particle size is preferably 20 to 120 nm, and more preferably 30 to 100 nm. In addition, the measuring method of the average particle diameter of infrared rays absorption particle is mentioned later.

  The polyester used in the polyester film for molded members of the present invention preferably comprises a polyethylene terephthalate resin (a) and a polybutylene terephthalate resin (b).

  Here, the polyethylene terephthalate resin (a) may be a resin comprising polyethylene terephthalate obtained by copolymerizing polyethylene terephthalate with a copolymer component of 30 mol% or less, preferably 20 mol% or less. As the copolymerization component to polyethylene terephthalate, 1,2-propanediol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexane Aliphatic dihydroxy compounds such as diol and neopentyl glycol, polyoxyalkylene glycols such as polyethylene glycol, polypropylene glycol and polytetramethylene glycol, alicyclic dihydroxy compounds such as 1,4-cyclohexanedimethanol, bisphenol A, bisphenol S and the like Aromatic dihydroxy compounds, etc., but 1,3-propanediol, 1,4-butanediol, neopentyl glycol, and 1,4-cyclohexanedimethanol are preferably used in terms of moldability and handleability. It is. Preferred dicarboxylic acid components include aromatic dicarboxylic acids such as 2,6-naphthalenedicarboxylic acid, isophthalic acid, diphenyldicarboxylic acid, diphenylsulfonedicarboxylic acid, diphenoxyethanedicarboxylic acid, 5-sodiumsulfonedicarboxylic acid, and phthalic acid. , Oxalic acid, succinic acid, adipic acid, sebacic acid, dimer acid, maleic acid, fumaric acid and other aliphatic dicarboxylic acids, 1,4-cyclohexanedicarboxylic acid and other alicyclic dicarboxylic acids, paraoxybenzoic acid and other oxycarbons An acid etc. can be mentioned. The dicarboxylic acid ester derivatives include esterified products of the above dicarboxylic acid compounds, such as dimethyl terephthalate, diethyl terephthalate, 2-hydroxyethyl methyl terephthalate, dimethyl 2,6-naphthalenedicarboxylate, dimethyl isophthalate, and dimethyl adipate. In addition, diethyl maleate, dimethyl dimer, and the like can be mentioned, but 2,6-naphthalenedicarboxylic acid and isophthalic acid are preferably used in terms of moldability and handleability. The polyethylene terephthalate resin (a) includes a resin (a1) made of 100 mol% polyethylene terephthalate not containing a copolymer component and a polyethylene terephthalate resin (a2) containing less than 20 mol% of a copolymer component. Further, it may be composed of two or more types of polyethylene terephthalate resins. Further, the polyethylene terephthalate resin (a1) may contain less than 30 mol of a copolymer component, and the polyethylene terephthalate resin (a) may be blended with three or more kinds of polyethylene terephthalate resins.

  The polybutylene terephthalate resin (b) may be a mixture of a polybutylene terephthalate resin and a polytrimethylene terephthalate resin. Examples of the copolymer component to the polyester resin (b) include ethylene glycol, 1,2-propanediol, 1,3-butanediol, 1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, and the like. Aliphatic dihydroxy compounds, polyoxyalkylene glycols such as polyethylene glycol, polypropylene glycol and polytetramethylene glycol, alicyclic dihydroxy compounds such as 1,4-cyclohexanedimethanol, aromatic dihydroxy compounds such as bisphenol A and bisphenol S, etc. Is mentioned. Preferred dicarboxylic acid components include aromatic dicarboxylic acids such as 2,6-naphthalenedicarboxylic acid, isophthalic acid, diphenyldicarboxylic acid, diphenylsulfonedicarboxylic acid, diphenoxyethanedicarboxylic acid, 5-sodiumsulfonedicarboxylic acid, and phthalic acid. , Oxalic acid, succinic acid, adipic acid, sebacic acid, dimer acid, maleic acid, fumaric acid and other aliphatic dicarboxylic acids, 1,4-cyclohexanedicarboxylic acid and other alicyclic dicarboxylic acids, paraoxybenzoic acid and other oxycarbons An acid etc. can be mentioned. The dicarboxylic acid ester derivatives include esterified products of the above dicarboxylic acid compounds, such as dimethyl terephthalate, diethyl terephthalate, 2-hydroxyethyl methyl terephthalate, dimethyl 2,6-naphthalenedicarboxylate, dimethyl isophthalate, and dimethyl adipate. , Diethyl maleate, dimethyl dimer, and the like.

  The polyester film for molded members of the present invention comprises a polyethylene terephthalate resin (a) and a polybutylene terephthalate resin (b) based on the total amount of the resin (a) and the resin (b). Is preferably 65 to 90% by weight, and the resin (b) is preferably mixed at 10 to 35% by weight. When the polyethylene terephthalate resin (a) is less than 65% by weight and the polybutylene terephthalate resin (b) exceeds 35% by weight, the melting point becomes less than 240 ° C., and the heat resistance, film appearance, and processability are improved. It may get worse. Further, when the polyethylene terephthalate resin (a) exceeds 90% by weight and the polybutylene terephthalate resin (b) is less than 10% by weight, the moldability tends to deteriorate, which is not preferable. In the present invention, preferably, the resin (a) is 70 to 85% by weight, the resin (b) is 15 to 30% by weight, and more preferably the resin (a) and the resin (b) based on the total amount. (A) is 75 to 80% by weight, and resin (b) is 20 to 25% by weight.

  Thus, the polyester film for molding members can provide the beauty after molding without shielding the infrared rays and whitening them in the process of being heated by the infrared heater at the time of molding.

  A preferable method for producing the film of the present invention using the polyester resin obtained as described above will be specifically described below.

  First, the polyethylene terephthalate-based resin (a), the polybutylene terephthalate-based resin (b) and the infrared-absorbing particles to be used are weighed at a predetermined ratio, if necessary, and before or after mixing, a nitrogen atmosphere or vacuum Dry in the atmosphere. It is preferable that the moisture content in the resin after drying is 50 ppm or less.

  Then, the mixed polyester resin is supplied to a single screw or twin screw extruder and melt extruded. Next, foreign matter is removed and the amount of extrusion is leveled through a filter and a gear pump, respectively, and discharged from the T die onto a cooling drum in a sheet form. At that time, an electrostatic application method in which a cooling drum and the resin are brought into close contact with each other by static electricity using an electrode applied with a high voltage, a casting method in which a water film is provided between the casting drum and the extruded polymer sheet, and the casting drum temperature is set to be equal to that of the polyester resin. The sheet-like polymer is brought into close contact with the casting drum, cooled and solidified by a method of sticking the extruded polymer at a glass transition point to (glass transition point−20 ° C.) or a combination of these methods, and unstretched. Get a film. Among these casting methods, when using polyester, a method of applying an electrostatic force is preferably used from the viewpoint of productivity and flatness.

  The polyester film for a molded member of the present invention may be an unstretched film or a uniaxially stretched film, but the peelability is improved when the protective film is prepared by adjusting the heat resistance and orientation described above, and a biaxially oriented film and It is preferable to do. The biaxially oriented film is obtained by stretching an unstretched film in the longitudinal direction and then stretching in the width direction, or by stretching in the width direction and then stretching in the longitudinal direction, or by the longitudinal direction of the film. It can be obtained by stretching by a simultaneous biaxial stretching method in which the width direction is stretched almost simultaneously.

  As a draw ratio in such a drawing method, preferably 2.5 to 3.5 times, more preferably 2.8 to 3.5 times, and particularly preferably 3 to 3.4 times are employed in each direction. The The stretching speed is preferably 1,000 to 200,000% / min. The stretching temperature is preferably 90 to 130 ° C, more preferably 100 to 120 ° C in the longitudinal direction and 90 to 110 ° C in the width direction. Further, the stretching may be performed a plurality of times in each direction.

  Furthermore, the film is heat-treated after biaxial stretching. The heat treatment can be performed by any conventionally known method such as in an oven or on a heated roll. This heat treatment is performed at a temperature of 120 ° C. or higher and below the melting point of the polyester, but is preferably 200 to 250 ° C. The heat treatment time can be arbitrarily set within a range not deteriorating the characteristics, and is preferably 1 to 60 seconds, more preferably 1 to 30 seconds. Further, the heat treatment may be performed by relaxing the film in the longitudinal direction and / or the width direction. Furthermore, in order to improve the adhesive force with the ink print layer, the adhesive, and the vapor deposition layer, at least one surface can be subjected to corona treatment or a coating layer can be provided.

  The polyester film for molded members of the present invention may be a single-layer film, or may be a vapor-deposited film that has been pre-deposited with metal prior to molding before giving a plating-like appearance. In the manufacturing process of the polyester film for members, the structure of A / B in which a layer containing one or more kinds of particles is laminated to improve the purpose of imparting slipperiness and scratch resistance, and the effects of the present invention are not impaired. The film structure of the present invention may be used in a part of a laminated film having two or more layers.

  The thickness of the polyester film for molded members of the present invention is preferably 10 to 300 μm, more preferably 15 to 200 μm, and most preferably 20 to 100 μm, from the viewpoint of concealing infrared rays.

  Various characteristics were measured and evaluated by the following methods.

(1) Melting point of film About 10 mg of a film sample was measured using a DSC7 manufactured by PERKIN-ELMER under the conditions of a temperature of 30 to 300 ° C. and a heating rate of 20 ° C./min. It was. When a plurality of endothermic peaks existed, the peak temperature of the endothermic peak on the highest temperature side was taken as the melting point.

(2) Film thickness A digital micrometer in which a film sample was cut into a size of 100 mm × 100 mm using an SD-type lever-type sample cutting machine SDL-100 (manufactured by Dumbbell Co., Ltd.), and 10 sheets were prepared and calibrated. (M-30, manufactured by Sony Precision Technology Co., Ltd.), the thickness of 8 points per sheet was measured, and the average thickness was calculated for each sample.

(3) Transmittance A transmittance was measured by attaching a φ60 integrating sphere 130-0632 (Hitachi Ltd.) and a 10 ° inclined spacer to a spectrophotometer (U3410 Spectrophotometer) manufactured by Hitachi, Ltd. The bandpass is set to 2 nm / servo, the gain is set to 3, and the range from 700 nm to 2500 nm is 120 nm / min. The scanning speed was measured. Moreover, the thing attached to U3410 was used as a standard white board.

(4) Average particle diameter of infrared absorbing particles The polymer is removed from the film by a plasma low-temperature ashing method to expose the particles. The processing conditions are selected such that the polymer is ashed but the particles are not damaged as much as possible. The particles are observed with a scanning electron microscope (SEM), and the particle image is processed with an image analyzer. The magnification of SEM is observed at 10,000 times, and the volume average diameter d is obtained from the particle size and the volume fraction of the number of particles of 5000 or more by changing the observation location by the following formula. When two or more kinds of particles having different particle diameters were contained, the same measurement was performed for each particle to obtain the particle diameter.

d = Σ (di · Nvi)
Here, di is the particle size, and Nvi is the volume fraction.

  When the particles are significantly damaged by the plasma low-temperature ashing treatment method, the film cross section is observed at 3000 to 20000 times depending on the particle size using a transmission electron microscope (TEM). The section thickness of the TEM is about 100 nm, the location is changed, 500 fields or more are measured, and the volume average diameter d is obtained from the above formula.

  The average particle diameter was determined from the equivalent spherical diameter of the particles corresponding to 50% by volume measured by electron micrograph of the particles. The equivalent sphere diameter is the diameter of a sphere having the same volume as the particle.

(5) Film temperature after heating for 180 seconds A heat label (Micron Co., Ltd.) is attached to the film sample, and a near infrared heat beam condensing type (HYL20-11M, Hybec Co., Ltd.) is used as an infrared heater. The label display temperature after heating for 180 seconds in a 25 ° C. environment was defined as the film temperature. The heat label was attached to the film surface on the infrared heater side.

(6) Breaking stress after heating for 180 seconds The film was cut into a short shape having a length of 150 mm and a width of 10 mm in the longitudinal direction and the width direction to prepare a sample. Using a tensile tester (Orientec Tensilon UCT-100), the tensile test was performed in the longitudinal direction and the width direction of the film at an initial tensile chuck distance of 50 mm and a tensile speed of 300 mm / min. For measurement, the chucked film sample was placed so as to be parallel to the film surface 300 mm before the near infrared output port using a near infrared heat beam line condensing type (HYL20-11M manufactured by Hybec Co., Ltd.) A tensile test was performed after heating for 180 seconds in a 25 ° C. environment. The load applied to the film when the sample broke was read, and the value divided by the cross-sectional area (film thickness × 10 mm) of the sample before the test was taken as the breaking stress value. The measurement was performed five times for each sample and in each direction, and the average value was taken as the measured value.

(7) Composition of polyester The resin or film is dissolved in hexafluoroisopropanol (HFIP) or a mixed solvent of HFIP and chloroform, and the content of each monomer residue and by-product diethylene glycol is determined using ¹ H-NMR and ¹³ C-NMR. Can be quantified. In the case of a laminated film, the components constituting each layer can be collected and evaluated by scraping each layer of the film according to the laminated thickness. In addition, about the film of this invention, the composition was computed by calculation from the mixing ratio at the time of film manufacture.

(8) Intrinsic viscosity The intrinsic viscosity of the polyester resin and the film was measured at 25 ° C. using an Ostwald viscometer after dissolving the polyester in orthochlorophenol.

(9) Thermoformability The film is heated for 180 seconds using a near-infrared heat beam line condensing type (HYL20-11M, manufactured by Highbeck Co., Ltd.) as an infrared heater, and a cylindrical mold (bottom diameter 50 mm) is used. Then vacuum forming was performed. The state that the film was formed along the mold was evaluated according to the following criteria using the forming degree (drawing ratio: forming height / bottom diameter).
Class A: Molding was possible with a drawing ratio of 0.7 or more.
Class B: Molding was possible with a drawing ratio of 0.7 to 0.3.
Class C: Breaking occurred and molding could not be performed with a drawing ratio of 0.3.
Class D: Although it was able to be molded at a drawing ratio of 0.7 or more, wrinkles entered and the appearance was poor.

  Class A and class B pass, and if it is class A, it can be suitably used for deep drawing applications.

  Hereinafter, the present invention will be described in detail by way of examples.

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

(Polyester a1 :)
To a mixture of 100 parts by mass of dimethyl terephthalate and 67 parts by mass of ethylene glycol, 0.08 parts by mass of magnesium acetate and 0.022 parts by mass of antimony trioxide are added to dimethyl terephthalate, and the temperature is gradually raised. The transesterification was carried out while distilling methanol at ℃. Next, 0.019 part by mass of 85% by weight aqueous phosphoric acid solution was added, and the temperature was gradually raised and reduced. Finally, the temperature was raised and reduced to 290 ° C. and 0.5 mmHg until the intrinsic viscosity became 0.65. A polycondensation reaction was performed to obtain a polyethylene terephthalate resin having a by-product amount of 2 mol% of diethylene glycol.

(Polyester b :)
A mixture of 100 parts by mass of terephthalic acid and 110 parts by mass of 1,4-butanediol was heated to 140 ° C. under a nitrogen atmosphere to obtain a homogeneous solution, and then 0.054 parts by mass of tetra-n-butyl orthotitanate. Then, 0.054 parts by mass of monohydroxybutyltin oxide was added, and an esterification reaction was performed by a conventional method. Next, 0.066 parts by mass of tetra-n-butyl orthotitanate was added, and a polycondensation reaction was performed under reduced pressure to produce a polybutylene terephthalate resin having an intrinsic viscosity of 0.84. Thereafter, crystallization was performed at 140 ° C. in a nitrogen atmosphere, followed by solid phase polymerization at 200 ° C. for 6 hours in a nitrogen atmosphere to obtain a polybutylene terephthalate resin having an intrinsic viscosity of 1.22. This was designated as polyester b.

(Polyester a2 :)
To a mixture of 100 parts by weight of dimethyl terephthalate, 60 parts by weight of ethylene glycol, and 20 parts by weight of 1,4-cyclohexanedimethanol, 0.04 parts by weight of manganese acetate is added, and the temperature is gradually raised. Transesterification was carried out while distilling methanol at 0 ° C. Next, 0.045 parts by mass of 85% phosphoric acid aqueous solution and 0.01 parts by mass of germanium dioxide were added, and the temperature was gradually raised and reduced. Finally, the temperature was raised to 275 ° C. and 1 hPa, and the intrinsic viscosity was reduced. The polymerization reaction was performed until 0.67 was reached, and then a strand was discharged, cooled, and cut to obtain a polyethylene terephthalate resin copolymerized with 8 mol% of 1,4-cyclohexanedimethanol. The polymer was cut into cubes having a diameter of 3 mm, and solid phase polymerization was performed using a rotary vacuum polymerization apparatus under a reduced pressure of 1 hPa at 225 ° C. until the intrinsic viscosity became 0.8, and this was designated as polyester a2.

(Particle Master :)
Add 0.04 parts by weight of manganese acetate to a mixture of 100 parts by weight of dimethyl terephthalate and 70 parts by weight of ethylene glycol, gradually increase the temperature, and finally perform transesterification while distilling methanol at 220 ° C. It was. Subsequently, 0.025 weight part of 85% phosphoric acid aqueous solution and 0.02 weight part of antimony trioxide were added. Further, an ethylene glycol slurry of agglomerated particles having a number average particle size of 2.2 μm was added so that the particle concentration was 2% by weight, and the temperature was gradually raised and depressurized. Finally, the temperature was raised to 290 ° C. and 1 hPa, The pressure was reduced and the polycondensation reaction was performed until the intrinsic viscosity became 0.63 dl / g, and then the particles were discharged in a strand, cooled, and cut to obtain particle master chips.

(ITO particle master 1 :)
Polyester a1 is subjected to a twin screw extruder with a vent, and ITO fine particles (infrared absorbing particles) having a volume average particle diameter of 40 nm having a maximum absorption peak at 2400 to 2500 nm are supplied so as to have a concentration of 5% by weight, and melt kneading is performed. And an infrared absorber masterbatch was obtained.

(ITO particle master 2 :)
Polyester a1 is subjected to a twin screw extruder with a vent, and ITO fine particles (infrared absorbing particles) having a volume average particle diameter of 40 nm having a maximum absorption peak at 2400 to 2500 nm are supplied to a concentration of 20% by weight, and melt kneading is performed. And an infrared absorber masterbatch was obtained.

(Zn compound particle master 1 :)
Polyester a1 is subjected to a twin screw extruder with a vent, and ZnO fine particles (infrared absorbing particles) having a volume average particle diameter of 50 nm having a maximum absorption peak at 2400 to 2500 nm are supplied so as to have a concentration of 5% by weight, and melt kneading is performed. And an infrared absorber masterbatch was obtained.

(Zn compound particle master 2 :)
Polyester a1 is supplied to a twin screw extruder with a vent, and ZnO fine particles (infrared absorbing particles) having a volume average particle diameter of 50 nm having a maximum absorption peak at 2400 to 2500 nm are supplied so as to have a concentration of 20% by weight, and melt kneading is performed. And an infrared absorber masterbatch was obtained.

  The raw material compositions for the polyester production are summarized in Table 1.

The abbreviations in the table are as follows.
EG: ethylene glycol residue component BD: 1,4-butanediol residue component TPA: terephthalic acid residue component DEG: diethylene glycol residue component CHDM: 1,4-cyclohexanedimethanol residue component (Example)
Examples of the present invention and comparative examples are shown below.

Example 1
As a polyester composition constituting the polyester film, polyester a1, polyester a2, polyester b, particle master, and ITO particle master 1 were used in a weight ratio of 26: 40: 30: 2: 2. The mixed polyester composition is dried in a vacuum dryer at 150 ° C. for 5 hours, and after sufficiently removing moisture, supplied to a single screw extruder, melted at 275 ° C., and cooled by controlling the temperature to 25 ° C. from a T-die. The sheet was discharged onto the drum. At that time, a wire-like electrode having a diameter of 0.1 mm was applied electrostatically and adhered to the cooling drum to obtain an unstretched film. Next, before stretching in the longitudinal direction, the film temperature is raised with a heating roll, and finally the film temperature is stretched 3.3 times in the longitudinal direction at 105 ° C., and then the preheating temperature is 100 ° C. with a tenter-type transverse stretching machine, The film was stretched 3.3 times in the width direction at a stretching temperature of 105 ° C, and heat treated for 5 seconds at a temperature of 200 ° C while relaxing 5% in the width direction in a tenter to obtain a biaxially oriented film having a film thickness of 25 µm. It was.

(Example 2)
As a polyester composition constituting the polyester film, polyester a1, polyester a2, polyester b, particle master, and ITO particle master 1 were used at a weight ratio of 24: 40: 30: 2: 4. Other than that obtained the biaxially oriented film similarly to Example 1.

Example 3
As a polyester composition constituting the polyester film, polyester a1, polyester a2, polyester b, particle master, and ITO particle master 1 were used in a weight ratio of 18: 40: 30: 2: 10. Other than that obtained the biaxially oriented film similarly to Example 1.

Example 4
As a polyester composition constituting the polyester film, polyester a1, polyester a2, polyester b, particle master, and ITO particle master 1 were used in a weight ratio of 13: 40: 35: 2: 10. Other than that obtained the biaxially oriented film similarly to Example 1.

(Example 5)
As a polyester composition constituting the polyester film, polyester a1, polyester b, particle master, and ITO particle master 1 were used in a weight ratio of 78: 10: 2: 10. Other than that obtained the biaxially oriented film similarly to Example 1.

(Example 6)
As a polyester composition constituting the polyester film, polyester a1, polyester a2, polyester b, particle master, and ITO particle master 2 were used in a weight ratio of 3: 40: 30: 2: 25. Other than that obtained the biaxially oriented film similarly to Example 1.

(Example 7)
As a polyester composition constituting the polyester film, polyester a1, polyester a2, polyester b, particle master, and Zn compound particle master 1 were used in a weight ratio of 26: 40: 30: 2: 2. Other than that obtained the biaxially oriented film similarly to Example 1.

(Example 8)
As a polyester composition constituting the polyester film, polyester a1, polyester a2, polyester b, particle master, and Zn compound particle master 1 were used at a weight ratio of 24: 40: 30: 2: 4. Other than that obtained the biaxially oriented film similarly to Example 1.

Example 9
As the polyester composition constituting the polyester film, polyester a1, polyester a2, polyester b, particle master, and Zn compound particle master 1 were used at a weight ratio of 18: 40: 30: 2: 10. Other than that obtained the biaxially oriented film similarly to Example 1.

(Example 10)
As the polyester composition constituting the polyester film, polyester a1, polyester a2, polyester b, particle master, and Zn compound particle master 2 were used at a weight ratio of 3: 40: 30: 2: 25. Other than that obtained the biaxially oriented film similarly to Example 1.

  The results of Examples 1 to 6 are shown in Table 2, and the results of Examples 7 to 10 are shown in Table 3, respectively.

The abbreviations in the table are as follows.
MD: film longitudinal direction TD: film width direction (Comparative Example 1)
As the polyester composition constituting the polyester film, polyester a1, polyester a2, polyester b, and particle master were used at a weight ratio of 28: 40: 30: 2. A biaxially oriented film was obtained in the same manner as in Example 1 except that the infrared absorbing particles were not added.

(Comparative Example 2)
As a polyester composition constituting the polyester film, polyester a1, polyester a2, polyester b, particle master and ITO particle master 1 were used in a weight ratio of 27.8: 40: 30: 2: 0.01. A biaxially oriented film was obtained in the same manner as in Example 1 except that the amount of ITO particle master was small.

(Comparative Example 3)
As a polyester composition constituting the polyester film, polyester a1, polyester a2, polyester b, particle master, and Zn compound particle master 1 were used in a weight ratio of 27: 40: 30: 2: 1. A biaxially oriented film was obtained in the same manner as in Example 1 except that the amount of Zn particle master was small.

(Comparative Example 4)
As a polyester composition constituting the polyester film, polyester a2, polyester b, particle master, and ITO particle master 2 were used at a weight ratio of 33: 35: 2: 30. A biaxially oriented film was obtained in the same manner as in Example 1 except that the ITO particle master exceeded 5% by weight.

(Comparative Example 5)
As a polyester composition constituting the polyester film, polyester a1, polyester a2, polyester b, particle master, and ITO particle master 1 were used in a weight ratio of 16: 40: 40: 2: 2. A biaxially oriented film was obtained in the same manner as in Example 1 except that the melting point was less than 240 ° C.

  The results of Comparative Examples 1-5 are shown in Table 4.

  From the table, in the examples satisfying the requirements of the present invention, it was a film having excellent characteristics as a molded member. On the other hand, in the comparative example, it was a film inferior to the characteristic as a molded member.

  The surface-protecting polyester film for molding according to the present invention has excellent molding processability, and can easily form a molded part that follows the mold in thermoforming such as vacuum forming and vacuum / pressure forming. As a molded part having the appearance, it can be suitably used as a part such as an automobile member or a household appliance. Furthermore, since the external appearance of a molded object can be kept beautiful when it uses as a surface protection sheet at the time of shaping | molding of the decoration sheet for shaping | molding, it can be used conveniently as a surface protection sheet of a decoration sheet.

Claims (7)

A polyester film having a melting point of 240 to 260 ° C. having a minimum transmittance of 80% or less at a wavelength of 700 to 2500 nm, and the breaking stress of the film after heating the film with an infrared heater for 180 seconds has a longitudinal direction and a width. A polyester film for molded members in which any of the directions is 40 or more and less than 100 MPa. The polyester film for molded members according to claim 1, wherein the film temperature after heating for 180 seconds with an infrared heater exceeds 100 ° C. The polyester film for molded members according to claim 1 or 2, comprising 0.1 to 5% by weight of infrared absorbing particles. The polyester film for molded members according to any one of claims 1 to 3, wherein the infrared absorbing particles have a particle size of 10 to 150 nm. The biaxially oriented polyester film for molded member according to claim 3 or 4, wherein the infrared absorbing particles are one or more particles selected from the group consisting of indium-based particles, lanthanum-based particles, antimony-based particles, and zinc compound particles. A film comprising a polyester resin composition containing a polyethylene terephthalate resin (a) and a polybutylene terephthalate resin (b), wherein the resin (a) content in the resin composition is: 65 to 90% by weight based on the total amount of the resin (a) and the resin (b), and the content of the resin (b) is 10 to 35 based on the total amount of the resin (a) and the resin (b). The polyester film for molded members according to any one of claims 1 to 5, which is a film formed using a polyester-based resin composition mixed by weight%. The shaping | molding method which heats the polyester film for shaping | molding members in any one of Claims 1-6 with an infrared heater, and shape | molds.