JP2016190438A - Biaxially oriented polyester film for molding and manufacturing method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a biaxially oriented polyester film for molding containing at least a polyester resin as a main component and constituting a layer containing a structural unit derived from 1,4-cyclohexanedimethanol of at least 5 mol% or more and excellent appearance with haze elevation of 1.0% or less even with rapid film heating speed.SOLUTION: There is provided a biaxially oriented polyester film for molding satisfying following conditions (1) to (2). (1) Constituting a layer containing at least a polyester resin as a main component and constituting a layer containing a structural unit derived from 1,4-cyclohexanedimethanol of at least 5 mol% or more. (2) Elevation factor of Δ haze in a zone of 140°C to 180°C of less than 1.0×10%/°C when heating the film at average heating speed of 15°C/sec. or more.SELECTED DRAWING: None

Description

  The present invention relates to a biaxially oriented polyester film that is particularly suitable for use in molding and a method for producing the same.

  In recent years, due to increasing environmental awareness, there has been an increasing demand for solventless coating, plating alternatives, etc. for building materials, automobile parts, mobile phones, electrical appliances, etc., and the introduction of decoration methods using films is progressing.

  As a molding method of the molded member, there are heat molding methods such as vacuum molding, pressure molding, vacuum pressure molding, press molding, plug assist molding, and any molding method can increase the temperature of the film by a preheating process such as an infrared heater. It has the process shape | molded after making it into a state. In order to shorten the molding shot time, rapid heating is performed in the film preheating process.

  Several proposals have been made as molding polyester films used in such decoration methods. For example, it is patent document 1. FIG.

However, in the method described in Patent Document 1, since the melting temperature in the extruder is not sufficiently high, shearing is insufficient, and microcrystals remain in the molten thermoplastic resin, so that the molten thermoplastic resin is made into a film. When cooled and solidified, the transparency may be lowered.
On the other hand, the method described in Patent Document 2 provides an extrusion method and a production method for sufficiently melting and kneading a resin to obtain a thermoplastic resin film having high transparency and less foreign matter.
However, in this method, although transparency is obtained, there is a problem that the film haze increases due to rapid heating in the preheating step for forming the film and the appearance is remarkably lowered.

JP 2011-73151 A JP 2014-151510 A

It has been found that the increase in film haze in the rapid heating in the preheating process for forming the film is caused by the occurrence of blistering of about 1 to 2 μm on the film surface when the heating rate is a certain level or more. In addition, this blister is characterized by the absence of nuclei and not due to oligomers.
As a result of intensive studies, it has been found that this increase in film haze is related to the thermal decomposition characteristics of the resin used in the film and the pellet melting temperature and time in the extruder during film production.

  The present invention provides a biaxially stretched polyester film for molding that is suppressed in haze rise and excellent in appearance even at a rapid film heating rate in a preheating step during film molding.

That is, the present invention has the following features.
A biaxially oriented polyester film for molding characterized by satisfying the following conditions (1) to (2). (1) It has a layer containing a polyester resin as a main component and containing at least 5 mol% of structural units derived from 1,4-cyclohexanedimethanol.
(2) When the film is heated at an average heating rate of 15 ° C./sec or more and 20 ° C./sec or less, the increase coefficient of Δhaze in the region from 140 ° C. to 180 ° C. is less than 1.0 × 10 ⁻² % / ° C. It is.

  The biaxially oriented polyester film for molding according to the present invention has a biaxially oriented film with an excellent appearance that suppresses an increase in film haze even at an abrupt film heating rate of an average heating rate of 15 ° C./sec to 20 ° C./sec. A polyester film can be provided.

  The polyester constituting the biaxially oriented polyester film for molding of the present invention is a general term for polymer compounds in which main bonds in the main chain are ester bonds. The polyester resin can be usually obtained by polycondensation reaction of dicarboxylic acid or its derivative with glycol or its derivative.

  In the present invention, from the viewpoint of moldability, appearance, heat resistance, dimensional stability and economy, 60 mol% or more of the glycol units constituting the polyester is a structural unit derived from ethylene glycol, and 60 mol% of the dicarboxylic acid unit. The above is preferably a structural unit derived from terephthalic acid. Here, the dicarboxylic acid unit (structural unit) or the diol unit (structural unit) means a divalent organic group from which a portion to be removed by polycondensation has been removed. Represented by the general formula.

Dicarboxylic acid unit (structural unit): —CO—R—CO—
Diol unit (structural unit): —O—R′—O—
(Where R and R ′ are divalent organic groups)
The same applies to the meaning of units (structural units) of trivalent or higher carboxylic acids such as trimellitic acid units and glycerin units, and alcohols and derivatives thereof.

  In addition to ethylene glycol, the glycol or derivative thereof that gives the polyester used in the present invention is important to contain 1,4-cyclohexanedimethanol in terms of moldability and handleability.

In addition to terephthalic acid, the dicarboxylic acid or derivative thereof that provides the polyester used in the present invention includes isophthalic acid, phthalic acid, 2,6-naphthalenedicarboxylic acid, diphenyldicarboxylic acid, diphenylsulfone dicarboxylic acid, diphenoxyethanedicarboxylic acid. Acids, aromatic dicarboxylic acids such as 5-sodiumsulfone dicarboxylic acid, oxalic acid, succinic acid, adipic acid, sebacic acid, dimer acid, maleic acid, fumaric acid and other aliphatic dicarboxylic acids, 1,4-cyclohexanedicarboxylic acid, etc. Alicyclic dicarboxylic acids, oxycarboxylic acids such as paraoxybenzoic acid, and derivatives thereof. Examples of dicarboxylic acid derivatives include dimethyl terephthalate, diethyl terephthalate, 2-hydroxyethyl methyl terephthalate, dimethyl 2,6-naphthalenedicarboxylate, dimethyl isophthalate, dimethyl adipate, diethyl maleate, and dimethyl dimer. An esterified product can be mentioned. Among them, it is important to use 1,4-cyclohexanedicarboxylic acid and esterified products thereof from the viewpoint of moldability and handleability. Furthermore, it is important that the structure includes a structural unit derived from 1,4-cyclohexanedimethanol having a ring structure, and 5 mol of a structural unit derived from 1,4-cyclohexanedimethanol is used as a glycol component in the film. It is important to contain at least%.
By containing 5 mol% or more of a structural unit derived from 1,4-cyclohexanedimethanol as a glycol component in the film, orientation crystallization of the film during molding can be suppressed, and the stress at 100% elongation of the film at 150 ° C. (F100 value) can be kept low, and the elongation at break can also be improved.
When the film contains a structural unit derived from 1,4-cyclohexanedimethanol as a glycol component in an amount of less than 5 mol%, the stress at 100% elongation (F100 value) of the film at 150 ° C. is kept low, and the elongation at break May not be improved.

The upper limit of the content of structural units derived from 1,4-cyclohexanedimethanol as the glycol component in the film is preferably 50 mol% or less.
The film temperature in the preheating step for forming the film is preferably 160 ° C. ± 10 ° C. in consideration of cooling due to the time from the preheating step to the forming step.
It is important that the film heating temperature in the preheating process at the time of film forming is 140 ° C. or higher and 180 ° C. or lower. If it is less than 140 degreeC, the temperature of a film may fall from a preheating process to a shaping | molding process, and the target shaping | molding may not be performed. If the temperature exceeds 180 ° C., the film may be crystallized to whiten and / or increase the rigidity of the film, and the target appearance and / or molding may not be achieved. Preferably, they are 150 degreeC or more and 170 degrees C or less.
It is important that the film average heating rate in the preheating process at the time of film forming is 15 ° C./sec or more and 20 ° C./sec or less.
Here, the film average heating rate in the preheating process at the time of film forming is a value obtained by dividing the difference between the target film temperature and the film temperature before heating by the time to reach the target film temperature.
If the average film heating rate in the preheating step at the time of film formation is less than 15 ° C./sec, productivity is lowered and production costs are increased, which is not preferable.
On the other hand, if it exceeds 20 ° C./sec, it becomes difficult to control the film temperature, and the target film temperature may not be obtained.
As a method of increasing the average film heating rate in the preheating process at the time of film formation, the average film heating rate is set to 15 ° C. by shortening the preheating process time by increasing the temperature of the heater or bringing the distance between the heater and the film closer. / Sec or more and 20 ° C./sec or less.
When the film is heated at an average film heating rate of 15 ° C./sec or more and 20 ° C./sec in the preheating step at the time of film forming, the increase coefficient of Δhaze in the region from 140 ° C. to 180 ° C. is 1.0 × It is important that it be less than 10 ⁻² % / ° C.
Here, the coefficient of increase in Δhaze in the region from 140 ° C. to 180 ° C. is the difference in haze when heated at an average heating rate of 15 ° C./sec to 20 ° C./sec to 180 ° C. and 140 ° C., respectively. The value divided by ℃.
Preferably, it is 0.5 × 10 ⁻² % / ° C. or less. If it is 1.0 × 10 ⁻² % / ° C. or more, the molded product may appear cloudy.
When the film is heated at an average film heating rate of 15 ° C./sec or more and 20 ° C./sec or less in the preheating step at the time of film molding, the increase coefficient of Δhaze in the region from 140 ° C. to 180 ° C. is 1.0 As a film manufacturing method which makes it less than ^{x10 <-2} >% / degreeC, it is preferable to control the resin temperature which supplies to a vent type twin-screw extruder, and is melt-extruded to 275 degreeC or more.

When the temperature is lower than 275 ° C., shearing is insufficient, and microcrystals remain in the molten thermoplastic resin. Therefore, when the molten thermoplastic resin is cooled and solidified to form a film, transparency may be lowered. . Preferably it is 280 degreeC or more.
When a film comprising a polyester resin as a main component and constituting a layer containing at least 5 mol% of a structural unit derived from 1,4-cyclohexanedimethanol is heated at an average heating rate of 15 ° C./sec or more As a method for producing a film in which the increase coefficient of Δhaze in the region from 140 ° C. to 180 ° C. is less than 1.0 × 10 ⁻² % / ° C., the structural unit derived from 1,4-cyclohexanedimethanol is at least 5 mol. It is important that the vent type twin screw extrusion temperature condition for extruding the undried resin constituting the layer containing at least% satisfies the following formula (a) or (b).

T _{(0.2 wt%)} ≧ Temp _time formula (a)
t _{(0.2 wt%)} ≧ time _Temp formula (b)
Here, T 2 _{(0.2 wt%)} is a resin containing at least 10 mol% or more of a structural unit derived from 1,4-cyclohexanedimethanol in thermogravimetric analysis that is heated under an inert gas stream and a constant temperature (hereinafter referred to as “resin”). The temperature at which% heat loss reaches 0.2% by weight when treated with undried PET-G).
Here, PET-G is a resin that is kneaded to form a layer containing at least 5 mol% of structural units derived from 1,4-cyclohexanedimethanol.
Temp _time represents the resin temperature at the exit of the extruder.
The _time corresponding to T _{(0.2 wt%)} and Temp _time is the time from when the melted resin reaches the T die to the exit of the extruder.

By setting Temp _time to T _{(0.2 wt%)} or less, the increase coefficient of Δhaze can be made less than 1.0 × 10 ⁻² % / ° C. If Temp _time exceeds T 2 _{(0.2 wt%)} , the _Δhaze increase coefficient becomes 1.0 × 10 ⁻² % / ° C. or more, which is not preferable.
Here, t _{(0.2 wt%)} is _0.2% by weight when the PET-G resin is treated in an undried state in a thermogravimetric analysis in which an inert gas stream and a constant temperature are used for heating. Indicates the time to reach.
time _Temp indicates the time from the exit of the extruder to the T die when the molten resin is present.
The temperature corresponding to t _{(0.2 wt%)} and time _Temp is the resin temperature at the exit of the extruder.

By setting time _Temp to t _{(0.2 wt%)} or less, the increase coefficient of Δhaze can be made less than 1.0 × 10 ⁻² % / ° C. When time _Temp exceeds t _{(0.2 wt%)} , the increase coefficient of Δhaze may be 1.0 × 10 ⁻² % / ° C. or more.

The method for setting time _Temp to t _{(0.2 wt%)} or less can be achieved by increasing the extrusion speed.

  The biaxially oriented polyester film for molding of the present invention can suppress an increase in film haze even at an abrupt film heating rate in a preheating process during film molding.

  The biaxially oriented polyester film for molding of the present invention preferably has a 100% elongation stress (F100 value) in the longitudinal direction and the width direction at 150 ° C. of 5 MPa to 60 MPa, respectively, from the viewpoint of moldability. As a molding method of the molded member, there are heat molding methods such as vacuum molding, pressure molding, vacuum pressure molding, press molding, plug assist molding, and any molding method can increase the temperature of the film by a preheating process such as an infrared heater. It has the process shape | molded after making it into a state. For this reason, it becomes possible to shape | mold into a complicated shape by reducing the molding stress at high temperature. Therefore, the stress at 100% elongation (F100 value) at 150 ° C. of the biaxially oriented polyester film for molding is preferably 5 MPa or more and 60 MPa or less. If the F100 value is less than 5 MPa, it may not be able to withstand the tension for film transfer in the preheating step in the molding process, and the film may be deformed or broken in some cases. Sometimes it becomes an unbearable film. On the other hand, when it exceeds 60 MPa, deformation during thermoforming is insufficient, and it may be difficult to mold into a complicated shape. From the viewpoint of handleability and moldability, the 100% elongation stress (F100 value) in the film longitudinal direction and width direction at 150 ° C. is preferably from 10 MPa to 50 MPa, and most preferably from 15 MPa to 45 MPa.

  In addition, the biaxially oriented polyester film for molding of the present invention is preferably 100% or more and 500% or less in breaking direction in the film longitudinal direction and width direction at 150 ° C. in order to be molded into a more complicated shape. . Even when it is molded into a complicated shape, it can follow a high molding processing magnification, and can be excellent in economic efficiency and heat resistance. In terms of moldability, heat resistance, and economy, the elongation in the longitudinal direction and the width direction is preferably 100% or more and 400% or less, and most preferably 120% or more and 300% or less. In particular, when used in applications that require dimensional stability, the elongation in the longitudinal direction or width direction of the film is preferably 120% or more and 200% or less.

  The biaxially oriented polyester film for molding of the present invention preferably has a storage elastic modulus at 80 ° C. of 2000 MPa to 4000 MPa from the viewpoint of dimensional stability during processing. More preferably, it is 2400 MPa or more and 3000 MPa or less. When the storage elastic modulus at 80 ° C. is less than 2000 MPa, the dimensional stability in processing steps such as printing, vapor deposition, coating, and laminating may decrease. When the storage elastic modulus exceeds 4000 MPa, the dimensional stability is excellent, but the moldability may be deteriorated.

  In the biaxially oriented polyester film for molding of the present invention, as a method for setting the storage elastic modulus at 80 ° C. in the above range, for example, a method of setting the peak temperature of loss tangent to 100 ° C. or higher and 120 ° C. or lower is preferably used. By setting the loss tangent peak temperature in the above range, the storage elastic modulus at 80 ° C. can be controlled to 2000 MPa or more and 3500 MPa or less while maintaining the moldability. The loss tangent peak is based on the glass transition of the polymer. If the loss tangent peak temperature is less than 100 ° C., the storage elastic modulus at 80 ° C. may be less than 2000 MPa, and the dimensional stability decreases. May end up. On the other hand, if the peak temperature of the loss tangent is to be made higher than 120 ° C., the 100% elongation stress (F100 value) in the film longitudinal direction and the width direction at 150 ° C. may be larger than 60 MPa, and the moldability is lowered. May end up. A more preferable range of the loss tangent is 100 ° C. or higher and 115 ° C. or lower.

  In addition, the biaxially oriented polyester film for molding of the present invention has a storage elastic modulus in the film longitudinal direction and width direction at 100 ° C. of 1000 MPa or more and 3000 MPa or less in order to further improve the dimensional stability during processing. Is preferred. More preferably, it is 1050 MPa or more and 2500 MPa or less, and most preferably 1100 MPa or more and 2000 MPa or less. By setting the storage elastic modulus in the film longitudinal direction and width direction at 100 ° C. within the above ranges, the dimensional stability during processing can be further improved, and the processing temperature region is widened, which is very preferable.

  In the biaxially oriented polyester film for molding of the present invention, the method for setting the storage elastic modulus at 100 ° C. in the above range is not particularly limited, but, for example, the loss tangent peak temperature is 105 ° C. or more and 120 ° C. or less. Is preferably used, and more preferably 105 ° C. or higher and 110 ° C. or lower.

  As a method for controlling the peak temperature of loss tangent, it is preferable to increase the draw ratio. The stretching ratio is preferably 10 times or more in terms of surface magnification, more preferably 11 times or more, and most preferably 12 times or more. Further, it is preferable to lower the stretching temperature to such an extent that uneven stretching does not occur. In particular, in sequential biaxial stretching in which stretching in the width direction is performed after stretching in the longitudinal direction, a method of lowering the stretching temperature in the longitudinal direction, specifically, a method of 80 ° C. to 90 ° C. is preferable, and the stretching temperature in the width direction is preferred. Is preferably 90 ° C to 100 ° C, which is higher than the stretching temperature in the longitudinal direction.

  In addition, the biaxially oriented polyester film for molding of the present invention preferably has a storage elastic modulus of 40 MPa or more and 400 MPa or less in the film longitudinal direction and the width direction at 180 ° C. from the viewpoint of heat resistance. When the storage elastic modulus at 180 ° C. is less than 40 MPa, the heat resistance is lowered, and the quality such as roughening of the film surface may be deteriorated during molding. If the storage elastic modulus exceeds 400 MPa, the moldability may deteriorate. From the viewpoint of heat resistance and moldability, the storage elastic modulus in the film longitudinal direction and the width direction at 180 ° C. is more preferably from 100 MPa to 300 MPa, and most preferably from 130 MPa to 250 MPa.

  As a method of setting the storage elastic modulus in the film longitudinal direction and the width direction at 180 ° C. to 40 MPa or more and 400 MPa or less, for example, the melting point of the polyester film is preferably 220 ° C. or more. From the viewpoint of heat resistance and moldability, the melting point of the polyester film is preferably 230 ° C. or higher and 255 ° C. or lower, and most preferably 235 ° C. or higher and 245 ° C. or lower.

Moreover, it is a polyester film which has X layer and Y layer, Comprising: It is preferable that it is a form which consists of 3 layer structure of X layer / Y layer / X layer from the point which can provide a function to each layer.
By imparting dimensional stability with the X layer and imparting moldability with the Y layer, it is possible to achieve both dimensional stability and moldability. A laminated polyester film composed of three layers can be obtained by biaxially stretching and heat-fixing what is extruded by a coextrusion method in which all layers are melt-extruded from a T-die.

  Moreover, when it is set as a laminated structure, as a lamination ratio of X layer from a viewpoint of moldability and dimensional stability, (thickness of X layer) / (thickness of the whole film) is 0.05 or more and 0.4 or less. Is preferred.

  The biaxially oriented polyester film for molding of the present invention preferably has a color tone b value of −1.5 or more and 1.5 or less from the viewpoint of the appearance after molding. When the color tone b value is less than -1.5, the appearance of the molded body using the biaxially oriented polyester film for molding of the present invention may become bluish and the appearance may be impaired. When the color tone b value is larger than 1.5, the appearance may be yellowish and the appearance may be deteriorated. More preferably, the color tone b value is from 0 to 1.5, most preferably from 0 to 1.2. Here, the color tone b value is a value obtained by transmission measurement based on JISZ-8722-2000 for measuring the b value in the Lab color system. The method for adjusting the color tone b value to be not less than -1.5 and not more than 1.5 is not particularly limited, but the resin temperature during extrusion when producing the biaxially oriented polyester film for molding of the present invention is controlled to 275 ° C to 295 ° C. It is preferable to do. Since the resin temperature at the time of extrusion may become higher than the extruder temperature due to shear heat generation of the resin, it is necessary to set the extruder temperature from the resin kneading time, resin viscosity, and the like. Further, it is preferable that the inside of the extruder is an inert gas, preferably a flowing nitrogen atmosphere, and the oxygen concentration inside the supply unit is 0.7 vol% or less, more preferably 0.5 vol% or less.

  In order to improve the dimensional stability after molding, the biaxially oriented polyester film for molding of the present invention preferably has a thermal shrinkage rate of 150% at 1 ° C. in the longitudinal direction and the width direction. Here, the heat shrinkage rate in the longitudinal direction and the width direction at 150 ° C. means that a film is cut into a rectangle 150 mm long × 10 mm wide in the longitudinal direction and the width direction, and marked lines are drawn on the sample at intervals of 100 mm. Is the rate of change in the distance between the marked lines before and after the heat treatment is performed by installing in a hot air oven heated to 150 ° C. for 30 minutes.

  It is very preferable that the heat shrinkage rate at 150 ° C. is 1% or less in both the longitudinal direction and the width direction because deformation or the like when the molded member after film formation is heated can be suppressed.

  Examples of a method for adjusting the heat shrinkage rate in the longitudinal direction and the width direction at 150 ° C. to 1% or less include a method of adjusting the heat treatment conditions of the film after biaxial stretching. When the treatment temperature is high, orientation relaxation occurs and the thermal shrinkage tends to be reduced, but the heat treatment temperature after biaxial stretching is 200 ° C. to 240 ° C. from the viewpoint of dimensional stability and film quality. It is preferable if it is 210 ° C to 235 ° C, more preferably 215 ° C to 230 ° C. In addition, the heat processing temperature of the biaxially oriented polyester film for molding of the present invention is caused by thermal history in a DSC curve when measured at a heating rate of 20 ° C./min in a nitrogen atmosphere in a differential scanning calorimeter (DSC). It can be determined from the minute endothermic peak.

  Moreover, as preferable heat processing time, although it can set arbitrarily in 5 to 60 second, it is preferable to set it as 10 to 40 second from a viewpoint of a moldability, dimensional stability, a color tone, and productivity, and 15-30. Preferably it is seconds. Further, the heat treatment is preferably performed while relaxing in the longitudinal direction and / or the width direction, since the heat shrinkage rate can be reduced. A preferable relaxation rate (relaxation rate) at the time of heat treatment is 3% or more. From the viewpoint of dimensional stability and productivity, 3% to 10% is preferable, and 3% to 5% is most preferable. preferable.

  Also, a method of heat treatment under two or more conditions is very preferable. After the heat treatment at a high temperature of 200 ° C. to 245 ° C., the heat shrinkage can be further reduced by performing the heat treatment at a temperature lower than the heat treatment temperature while relaxing in the longitudinal direction and / or the width direction. The heat treatment temperature in the second stage at this time is preferably 120 ° C. to 180 ° C., more preferably 150 ° C. to 180 ° C.

  Further, as a method for further reducing the thermal shrinkage rate, off-annealing treatment can be mentioned. That is, it is a method in which the polyester film once wound is subjected to heat treatment again.

  The thermal contraction rate at 150 ° C. is more preferably 0.8% or less, and most preferably 0.5% or less.

  In order to improve the dimensional stability after molding, the biaxially oriented polyester film for molding of the present invention is at least when heated at a heating rate of 5 ° C./min from 25 ° C. to 220 ° C. under a load of 19.6 mN. It is preferable that the thermal deformation rate of the film at 150 ° C. in one direction is 0 to + 3%. In order to improve the dimensional stability after molding, as described above, the off-annealing treatment is very effective, but the off-annealing treatment temperature is set to 140 ° C. or more and less than 160 ° C., and the width direction is made free. The thermal deformation rate in the width direction can be within the above range, and the longitudinal thermal deformation rate can be reduced by 0.5 to 5% lower than the unwinding rate to reduce the longitudinal thermal deformation rate. It can be a range. Furthermore, it is preferable to provide a stepwise cooling zone after the off-annealing treatment because the thermal contraction rate can be further reduced. More preferably, when the load is 19.6 mN and the temperature is increased from 25 ° C. to 220 ° C. at a rate of temperature increase of 5 ° C./min, the thermal deformation rate of the film at 150 ° C. in the longitudinal and width directions is 0 to + 3%. It is most preferable if the thermal deformation rate of the film at 150 ° C. in the longitudinal direction and the width direction is 0.5 to + 2%.

  In addition, the biaxially oriented polyester film for molding of the present invention has a load of 19.6 mN and a heating rate of 5 ° C./min from 25 ° C. to 220 ° C. when it is developed for applications in which dimensional stability after molding is particularly severe. It is preferable that the thermal deformation rate of the film at 180 ° C. in at least one direction when the temperature is raised is 0 to + 3%. More preferably, when the load is 19.6 mN and the temperature is increased from 25 ° C. to 220 ° C. at a rate of temperature increase of 5 ° C./min, the thermal deformation rate of the film at 150 ° C. in the longitudinal and width directions is 0 to + 3%. It is most preferable if the thermal deformation rate of the film at 180 ° C. in the longitudinal direction and the width direction is 0.5 to + 2%.

  In order to achieve the thermal deformation rate, it is possible to set the thermal deformation rate in the width direction to the above range by setting the off-annealing treatment temperature to 160 ° C. or more and 180 ° C. or less and making the width direction free. Moreover, the thermal deformation rate in the longitudinal direction can be set to the above range by reducing the winding speed in the longitudinal direction by 0.5 to 5% from the unwinding speed. Furthermore, it is preferable to provide a stepwise cooling zone after the off-annealing treatment because the thermal contraction rate can be further reduced. More preferably, the film has a thermal deformation rate of 0 to + 3% at 180 ° C. in the longitudinal direction and the width direction when the temperature is increased from 25 ° C. to 220 ° C. at a rate of temperature increase of 5 ° C./min with a load of 19.6 mN. It is most preferable if the thermal deformation rate of the film at 180 ° C. in the longitudinal direction and the width direction is 0.5 to + 2%.

The biaxially oriented polyester film for molding of the present invention preferably has a birefringence (Δn) of less than 20 × 10 ⁻³ from the viewpoint of uniform moldability. Here, uniform moldability means that the anisotropy of the film is small and the difference in the degree of molding is small depending on the direction. Birefringence is a numerical value defined by the refractive index of a film measured with an Abbe refractometer or the like. When the refractive index in the longitudinal direction of the film is nMD and the refractive index in the width direction is nTD, Δn = | NMD−nTD | When the birefringence is 20 × 10 ⁻³ or more, the orientation balance in the plane direction of the film is poor, so that the moldability may be deteriorated due to the influence of the high orientation direction. In order to further improve the uniform moldability, it is more preferably less than 15 × 10 ^{−3 and} most preferably less than 10 × 10 ⁻³ .

  The biaxially oriented polyester film for molding of the present invention preferably has a haze of less than 0.01% / μm from the viewpoint of the design properties of the molded member after molding. It is preferable that the haze is less than 0.01% / μm because the design of the molded member is improved.

  Examples of a method of setting the haze to less than 0.01% / μm include a method of reducing the concentration of particles to be contained in order to improve the film transportability. The biaxially oriented polyester film for molding of the present invention can contain particles in the film in order to improve the transportability of the film. Here, the particles to be used are not particularly limited, but externally added particles are preferably used in terms of transportability and appearance. Examples of the external additive particles include wet and dry silica, colloidal silica, aluminum silicate, titanium oxide, calcium carbonate, calcium phosphate, barium sulfate, and aluminum oxide, and organic particles include styrene, silicone, acrylic acid, methacrylic acid, Particles containing polyesters, divinyl compounds and the like as constituent components can be used. Among them, it is preferable to use inorganic particles such as wet and dry silica and alumina, and particles containing styrene, silicone, acrylic acid, methacrylic acid, polyester, divinylbenzene and the like as constituent components. Further, these externally added particles may be used in combination of two or more. From the viewpoint of transportability and appearance, the content of particles in the film is preferably 0.001 to 0.02% by mass, more preferably 0.002 to 0.01% by mass, based on the entire film as 100% by mass. .

  The biaxially oriented polyester film for molding of the present invention has a film thickness of preferably 25 μm or more and 500 μm or less, more preferably 50 μm or more and 300 μm or less, more preferably 75 μm or more, from the viewpoint of the depth and shape retention of the molded member. Most preferably, it is 250 μm or less.

  The biaxially oriented polyester film for molding according to the present invention can be subjected to corona treatment on at least one side in order to improve the adhesive force with various processed layers such as a printing layer, an adhesive, a vapor deposition layer, a hard coat layer, and a weather resistant layer. An adhesive layer can also be coated. As a method of providing the coating layer in-line in the film manufacturing process, at least uniaxially stretched film with a coating layer composition dispersed in water is uniformly applied using a metalling ring bar or gravure roll. Then, a method of drying the coating while stretching is preferable, and the thickness of the easy-adhesion layer is preferably 0.01 μm or more and 1 μm or less. Also, various additives such as antioxidants, heat stabilizers, ultraviolet absorbers, infrared absorbers, pigments, dyes, organic or inorganic particles, antistatic agents, nucleating agents, etc. may be added to the easy-adhesion layer. Good. The resin preferably used for the easy-adhesion layer is preferably at least one resin selected from an acrylic resin, a polyester resin, and a urethane resin from the viewpoint of adhesiveness and handleability. Among them, an acrylic resin is preferable because it is excellent in weather resistance, heat resistance, and moisture resistance. Furthermore, in order to improve the dimensional stability after molding, it is preferable to perform off-annealing at 140 to 180 ° C. In addition, transparency, suppression of iris patterns (interference fringes) when laminating hard coat layers (visibility), moisture and heat resistance with hard coat layers, adhesion when immersed in boiling water (boiling resistance) Zirconium dioxide particles may be added to improve the adhesiveness.

  The biaxially oriented polyester film for molding of the present invention preferably contains an antioxidant from the viewpoint of film quality. By containing the antioxidant, it is possible to suppress the oxidative decomposition in the drying step and the extrusion step of the polyester resin, and it is possible to prevent the deterioration of the quality due to the gel-like foreign matter. Although it does not specifically limit as a kind of antioxidant, For example, the antioxidant classified into hindered phenols, hydrazine, phosphites, etc. can be used conveniently. Among them, pentaerythrityl-tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], 3,5-di-tert-butyl-4-hydroxy-benzylphosphonate-diethyl ester 1,3,5-trimethyl-2,4,6-tris (3,5-di-t-butyl-4-hydroxybenzyl) benzene, tris (2,4-di-t-butylphenyl) phosphite, etc. Is preferably used.

  In addition, the biaxially oriented polyester film for molding of the present invention can impart weather resistance when used outdoors. Examples of a method for imparting weather resistance include a method of laminating a weather resistant layer. The weathering layer absorbs light energy with a wavelength of 350 nm or more and 360 nm or less, emits harmless heat energy, phosphorescence and fluorescence by very fast energy conversion, suppresses photoexcitation and photochemical reaction of impurities in the polymer, and whitens It is a layer having a function of preventing embrittlement, cracking, yellowing, etc., and is composed of, for example, a weather resistant resin layer or a layer in which various resin layers contain an ultraviolet absorber. In particular, it is preferable that the average transmittance of the film after the lamination in the wavelength range of 350 nm to 360 nm is 45% or less, preferably 30% or less, and more preferably 10% or less. The preferred thickness range of the weather resistant layer is 0.5 μm or more and 20 μm or less, more preferably 1 μm or more and 15 μm or less, and most preferably 2 μm or more and 10 μm or less. Moreover, the method of adding a weathering agent is also mentioned. Even when a weathering agent is added, the average transmittance of the film in the wavelength range of 350 nm to 360 nm is 45% or less, preferably 30% or less, more preferably 10% or less, as in the method of laminating the weathering layer. . The weathering agent to be used is not particularly limited, but benzophenone compounds, triazine compounds, benzotriazole compounds, salicylic acid compounds, salicylate compounds, cyanoacrylate compounds, nickel compounds, benzoxazinone compounds, cyclic iminos. An ester compound or the like can be preferably used. Among these, benzotriazole compounds, benzophenone compounds, and benzoxazinone compounds are preferably used, and benzoxazinone compounds are particularly preferably used from the viewpoint of dispersibility. These compounds can be used alone or in combination of two or more. Further, stabilizers such as HALS (Hindered Amine Light Stabilizer) and antioxidants can be used in combination, and it is particularly preferable to use a phosphorus-based antioxidant in combination. Examples of the benzotriazole-based compound include 2-2H-benzotriazol-2-yl) -4,6-bis (1-methyl-1-phenylethyl) phenol and 2- (2H-benzotriazole-2- Yl) -4- (1,1,3,3-tetramethylbutyl) phenol, 2- (2H-benzotriazol-2-yl) -4-methylphenol, 2- (2H-benzotriazol-2-yl) -4,6-di-t-butylphenol, 2- (2H-benzotriazol-2-yl) -4,6-di-t-amylphenol, 2- (2H-benzotriazol-2-yl) -4- t-butylphenol, 2- (2'-hydroxy-3'-t-butyl-5'-methylphenyl) -5-chlorobenzotriazole, 2- (2'-hydroxy-3 ', '- can be exemplified di -t- butyl phenyl) -5-chloro-benzotriazole, or the like. Examples of the benzophenone compounds include 2-hydroxy-4-octoxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2,2′-dihydroxy-4,4′-dimethoxybenzophenone, 2,2 ′, 4,4 ′. -Tetrahydroxybenzophenone, 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone-5-sulfonic acid and the like can be mentioned. Examples of the benzoxazinone compounds include 2-p-nitrophenyl-3,1-benzoxazin-4-one, 2- (p-benzoylphenyl) -3,1-benzoxazin-4-one, 2- ( 2-naphthyl) -3,1-benzoxazin-4-one, 2,2'-p-phenylenebis (3,1-benzoxazin-4-one), 2,2 '-(2,6-naphthylene) Bis (3,1-benzoxazin-4-one) and the like can be exemplified. Furthermore, it is preferable to use a cyanoacrylate-based tetramer compound in combination with another ultraviolet absorber in terms of imparting excellent weather resistance. In this case, the cyanoacrylate-based tetramer compound is preferably contained in an amount of 0.05 to 2% by weight, more preferably 0.1 to 1.0% by weight. The cyanoacrylate-based tetramer compound is a compound based on a tetramer of cyanoacrylate. For example, 1,3-bis (2′cyano-3,3-diphenylacryloyloxy) -2,2-bis- (2 ′ cyano-3,3-diphenylacryloyloxymethylpropane). Here, the ultraviolet absorber used in combination with cyanoacrylate is preferably a benzoxazinone compound, particularly 2,2 ′-(1,4-phenylene) bis (4H-3,1-benzoxazin-4-one), The addition amount is preferably 0.3 to 1.5% by weight in the film.

  Moreover, when the biaxially oriented polyester film for molding of the present invention is used on the surface of a molded member by printing, the appearance and design can be imparted. The printing method is not particularly limited, but gravure printing, offset printing, screen printing, and the like are preferably used. The thickness of the printing layer is preferably 1 nm or more and 20 μm or less.

Next, although the example of the specific manufacturing method of the biaxially-oriented polyester film for shaping | molding of this invention is described, this invention is limited to the example which concerns and is not interpreted.
The mixed polyester resin is supplied to a vent type twin screw extruder and melt extruded. At this time, the temperature of the resin to be melt-extruded is preferably controlled to 275 ° C. or more, and the extrusion temperature condition preferably satisfies the following formula (a).

T _{(0.2 wt%)} ≧ Temp _time formula (a)
Here, T _{(0.2 wt%)} is _0.2% by weight in terms of heat loss when PET-G is treated in an undried state in a thermogravimetric analysis where heating is performed under an inert gas stream and a constant temperature. Indicates the temperature reached.
Temp _time represents the resin temperature at the exit of the extruder.
The _time corresponding to T _{(0.2 wt%)} and Temp _time is the time from when the melted resin reaches the T die to the exit of the extruder.
Moreover, it is preferable that extrusion temperature conditions satisfy the following formula (b).

t _{(0.2 wt%)} ≧ time _Temp formula (b)
Here, t _{(0.2 wt%)} is _0.2% by weight of the heat source amount when the PET-G resin is treated in an undried state in the thermogravimetric analysis where heating is performed under an inert gas stream and a constant temperature. Indicates the time to reach.
time _Temp indicates the time from the exit of the extruder to the T die when the molten resin is present.
The temperature corresponding to t _{(0.2 wt%)} and time _Temp is the resin temperature at the exit of the extruder. Further, it is preferable that the inside of the extruder is under a flowing nitrogen atmosphere, the oxygen concentration is 0.7% by volume or less, and the resin temperature is controlled to be equal to or lower than the temperature obtained by the formula (a). 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 film of the present invention needs to be a biaxially oriented film from the viewpoints of heat resistance and dimensional stability. 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.

  The stretching ratio in such a stretching method is preferably 3.0 times or more and 4.2 times, more preferably 3.0 times or more and 4.0 times or less, particularly preferably in each of the longitudinal direction and the width direction. 3 times or more and 3.8 times or less are adopted. The stretching speed is desirably 1,000% / min or more and 200,000% / min or less. The stretching temperature is preferably 70 ° C. or higher and 120 ° C. or lower in the longitudinal direction and 80 ° C. or higher and 120 ° C. or lower 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, preferably 200 ° C. or higher and 240 ° C. or lower, more preferably 210 ° C. to 235 ° C., and even more preferably 215 ° C. to 230 ° C. Is most preferable. The heat treatment time can be arbitrarily set within a range not deteriorating the characteristics, and is preferably 5 seconds to 60 seconds, more preferably 10 seconds to 40 seconds, and most preferably 15 seconds to 30 seconds. Good. Further, the heat treatment may be performed by relaxing the film in the longitudinal direction and / or the width direction.

  The biaxially oriented polyester film for molding of the present invention is preferably used for decorating a molded member, and is preferably used for, for example, in-mold molding and insert molding as a molding decoration method. The in-mold molding referred to here is a molding method in which a film itself is placed in a mold and molded into a desired shape with a resin pressure to be injected to obtain a molded decorative body. Also, insert molding is to create a film molded body to be installed in the mold by vacuum molding, pressure molding, vacuum pressure molding, press molding, plug assist molding, etc., and filling the shape with resin, This is a molding method for obtaining a molded decorative body. Since a more complicated shape can be obtained, the biaxially oriented polyester film for molding of the present invention is particularly preferably used for insert molding.

  Since the biaxially oriented polyester film for molding of the present invention has a low molding stress in the molding temperature range, various molding methods such as vacuum molding, pressure molding, vacuum pressure molding, in-mold molding molded by injection resin pressure, etc. Since the storage modulus in the processing temperature range is in a specific range, it has excellent dimensional stability in processing processes such as coating, laminating, printing, and vapor deposition. It can be decorated by other means, and since it has a high storage elastic modulus in a high temperature region, it has excellent heat resistance, excellent surface properties even after molding, and excellent color tone, so the appearance is good For example, it can be suitably used for decorating molded members such as building materials, mobile devices, electrical products, automobile parts, and gaming machine parts.

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

・ PET
Polyethylene terephthalate resin (inherent viscosity 0.65) in which the terephthalic component is 100 mol% as the dicarboxylic acid component, the ethylene glycol component is 98.8 mol%, and the diethylene glycol component is 1.2 mol% as the glycol component.

・ PET-G type A
GN001 manufactured by Eastman Chemical Co. was used.
(Including 32 mol% of 1,4-cyclohexanedimethanol, intrinsic viscosity 0.76).

・ PET-G type B
S2008 manufactured by SK Chemical Company was used.
(33 mol% of 1,4-cyclohexanedimethanol contained intrinsic viscosity 0.71).
(1) Heat loss%
50 mg of PET-G Type A and Type B were weighed and used in a nitrogen atmosphere and at a constant temperature according to JIS K 7120 (1987) using a thermogravimetric analyzer (TGA-50) manufactured by Shimadzu Corporation. The heat loss up to minutes was determined.
(2) Composition of polyester A polyester resin and a film can be dissolved in hexafluoroisopropanol (HFIP), and the content of each monomer residue component and by-product diethylene glycol can be quantified using 1H-NMR and 13C-NMR. In the case of a laminated film, the components constituting each layer can be collected and evaluated by scraping off 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.

(3) Stress at 100% elongation at 150 ° C. (F100 value)
The film was cut into a rectangular shape having a length of 150 mm and a width of 10 mm in the longitudinal direction and the width direction to obtain 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 the measurement, a film sample was set in a constant temperature layer set in advance at 150 ° C., and a tensile test was performed after 90 seconds of preheating. Read the load applied to the film when the sample is stretched 100% (when the distance between chucks is 100 mm), and divide by the cross-sectional area (film thickness x 10 mm) of the sample before the test. F100 value). In addition, the measurement was performed 5 times for each sample and each direction, and the average value was evaluated.

(4) Storage viscoelasticity, loss tangent The film was cut into a rectangle having a length of 60 mm and a width of 5 mm in the longitudinal direction and the width direction to obtain a sample. The storage elastic modulus (E ′) at 80 ° C., 100 ° C., and 180 ° C. was determined using a dynamic viscoelasticity measuring device (DMS6100, manufactured by Seiko Instruments Inc.) under the following conditions.

Frequency: 10 Hz, test length: 20 mm, minimum load: about 100 mN, amplitude: 10 μm,
Measurement temperature range: −50 ° C. to 200 ° C., heating rate: 5 ° C./min.

(5) b value Based on JIS Z 8722 (2000), each film using a spectroscopic color difference meter (SE-2000 manufactured by Nippon Denshoku Industries Co., Ltd., light source halogen lamp 12V4A, 0 ° to −45 ° post-spectral method) The b value of was measured by the transmission method.

(6) Thermal contraction rate The film was cut into a rectangle of length 150 mm × width 10 mm in the longitudinal direction and width direction, respectively, and used as a sample. Marks were drawn on the sample at intervals of 100 mm, and a heat treatment was performed by placing in a hot air oven heated to 150 ° C. with a 3 g weight suspended for 30 minutes. The distance between the marked lines after the heat treatment was measured, and the thermal contraction rate was calculated from the change in the distance between the marked lines before and after heating by the following formula. For each film, five samples were carried out in the longitudinal direction and the width direction for each film, and the average value was evaluated.

Thermal shrinkage rate (%) = (distance between marked lines before heat treatment) − (distance between marked lines after heat treatment) / (distance between marked lines before heat treatment) × 100.
(7) Film haze Based on JIS K 7105 (1985), the haze of the film was measured using a haze meter (HGM-2GP manufactured by Suga Test Instruments Co., Ltd.). The measurement was performed at three arbitrary locations, and the average value was adopted.
(8) Film preheating average heating rate The film was cut into a length of 400 mm and a width of 400 mm in the longitudinal direction and the width direction to obtain a sample. The average film heating rate was a value obtained by heating the sample using a 450 ° C. far-infrared heater and dividing the temperature difference between 180 ° C. and the sample before heating by the time when the temperature of the sample reached 180 ° C. The temperature of the sample was measured with a heat label manufactured in advance by Micron Corporation.
(9) The film haze film after preheating was cut into a length of 400 mm and a width of 400 mm in the longitudinal direction and the width direction to obtain a sample. The sample was heated using a 450C far-infrared heater, and the sample was heated when the sample temperature reached 140 ° C and 180 ° C. The obtained sample was cooled to room temperature and then measured for haze using a haze meter (HGM-2GP manufactured by Suga Test Instruments Co., Ltd.) based on JIS K 7105 (1985). The measurement was performed at three arbitrary locations, and the average value was adopted. The sample haze heated to 140 ° C. was subtracted from the sample haze heated to 180 ° C. and divided by a heating temperature difference of 40 ° C. to obtain a Δhaze increase coefficient.
(10) The molded evaluation film was cut into a length of 400 mm and a width of 400 mm in the longitudinal direction and the width direction to obtain a sample. The sample was heated using a 450 ° C far-infrared heater, the sample was heated when the sample temperature reached 160 ° C, and vacuum was applied along a square mold (70 x 70 mm, height 25 mm) heated to 60 ° C. -Pressure molding (pressure: 0.2 Ma) was performed. A square mold having an edge portion with an R of 1 mm was prepared and vacuum-compressed. The molding state was evaluated according to the following criteria.
A: R1 mm can be reproduced, and cloudiness is not visually recognized through a fluorescent lamp.
○: R1 mm can be reproduced, and the cloudiness is hardly visually recognized through the fluorescent lamp.
(Triangle | delta): Although R1mm cannot be reproduced, cloudiness cannot be visually recognized by permeation | transmission of a fluorescent lamp.
X: R1 mm was reproducible, but cloudiness can be visually recognized through the fluorescent lamp.

Example 1
As the Y layer, PET and PET-G type A were mixed at a mass ratio of 60:40, supplied to a bent twin screw extruder having an oxygen concentration of 0.2% by volume, melted at 290 ° C., and the X layer. As follows, PET and PET-G type A are mixed at a mass ratio of 80:20, supplied to a vent type twin screw extruder having an oxygen concentration of 0.2% by volume, melted at 290 ° C., foreign matter removal, extrusion After the amount was leveled, the Y layer took 10 minutes and the X layer took 20 minutes from the exit of the extruder, and was discharged from a T die onto a cooling drum whose temperature was controlled at 25 ° C. At that time, a wire-like electrode having a diameter of 0.1 mm was applied electrostatically and adhered to the cooling drum to obtain an unstretched film.

  Next, before stretching in the longitudinal direction, the film temperature is raised with a heated roll, the preheating temperature is 85 ° C., the stretching temperature is 90 ° C., and the film is stretched 3 times in the longitudinal direction, and immediately controlled at 40 ° C. Cooled down.

  Next, the film was stretched 3.8 times in the width direction at a preheating temperature of 95 ° C. and a stretching temperature of 100 ° C. with a tenter type horizontal stretching machine, and the temperature was maintained at 230 ° C. for 5 seconds while relaxing 4% in the width direction. Heat treatment was performed to obtain a biaxially oriented polyester film having a film thickness of 188 μm. Table 2 shows the physical properties of the obtained film, the film haze after preheating, and the results of moldability.

(Example 2)
A biaxially oriented polyester film having a film thickness of 188 μm is obtained in the same manner as in Example 1 except that PET-G of the Y layer and X layer is type B, and the resin temperature is Y layer 280 ° C. and X layer 280 ° C. It was. Table 2 shows the physical properties of the obtained film and the results of haze and moldability after preheating.

(Examples 3, 4, and 5)
A biaxially oriented polyester film having a film thickness of 188 μm was obtained in the same manner as in Example 1 except that the Y-layer PET-G was type B and the resin temperatures were Y layer 280 ° C. and X layer 280 ° C. Table 2 shows the physical properties of the obtained film and the results of haze and moldability after preheating.

(Comparative Example 1)
A biaxially oriented polyester film having a film thickness of 188 μm was obtained in the same manner as in Example 1 except that only polyester was used. Table 2 shows the physical properties of the obtained film, the film haze after preheating, and the results of moldability.

(Comparative Examples 2 and 3)
A biaxially oriented polyester film having a film thickness of 188 μm was obtained in the same manner as in Example 2, except that the resin temperature was 300 ° C. for the Y layer and 290 ° C. for the X layer. Table 2 shows the physical properties of the obtained film, the film haze after preheating, and the results of moldability.

(Comparative Examples 4 and 5)
A biaxially oriented polyester film having a film thickness of 188 μm was obtained in the same manner as in Example 3 except that the resin temperature was 290 ° C. for the Y layer, 290 ° C. for the X layer, and the Y layer was taken from the extruder outlet for 15 minutes and discharged from the T die. Obtained. Table 2 shows the physical properties of the obtained film, the film haze after preheating, and the results of moldability.

The present invention is excellent in dimensional stability in processing steps such as coating, laminating, printing, and vapor deposition, and can be performed by various molding methods such as vacuum molding, pressure molding, vacuum pressure molding, in-mold molding molded by injection resin pressure, and the like. Provided is a biaxially oriented polyester film for molding that can be molded, has an excellent appearance after molding, and has an excellent color tone.

Claims (3)

A biaxially oriented polyester film for molding characterized by satisfying the following conditions (1) to (2).
(1) At least a layer containing a polyester resin as a main component and containing at least 5 mol% of a structural unit derived from 1,4-cyclohexanedimethanol.
(2) When the film is heated at an average heating rate of 15 ° C./sec or more and 20 ° C./sec or less, the increase coefficient of Δhaze in the region from 140 ° C. to 180 ° C. is less than 1.0 × 10 ⁻² % / ° C. It is.
(Here, the average heating rate is a value obtained by dividing the difference between the target film temperature and the film temperature before heating by the time to reach the target film temperature.
The increase coefficient of Δhaze is a value obtained by dividing the difference in haze when heated at 180 ° C. and 140 ° C. at an average heating rate of 15 ° C./sec to 20 ° C./sec by the temperature difference Δ40 ° C. ) It is a manufacturing method of the biaxially-oriented polyester film for shaping | molding of Claim 1, Comprising: The layer which has a polyester resin as a main component and contains the structural unit derived from 1, 4- cyclohexane dimethanol at least 5 mol% or more. A method for producing a biaxially oriented polyester film for molding, wherein a vent type biaxial extrusion temperature condition for extruding a constituent resin satisfies the following formula (a):
T _{(0.2 wt%)} ≧ Temp _time formula (a)
(Here, T _{(0.2 wt%)} is _{0.2 wt%} when the PET-G is treated in an undried state in thermogravimetric analysis in which an inert gas stream and a constant temperature are used for heating. Indicates the temperature reached.
Here, PET-G is a resin that is kneaded to form a layer containing at least 5 mol% of structural units derived from 1,4-cyclohexanedimethanol.
Temp _time represents the resin temperature at the exit of the extruder.
The _time corresponding to T _{(0.2 wt%)} and Temp _time is the time from when the melted resin reaches the T die to the exit of the extruder. ) It is a manufacturing method of the biaxially-oriented polyester film for shaping | molding of Claim 1, Comprising: The layer which has a polyester resin as a main component and contains the structural unit derived from 1, 4- cyclohexane dimethanol at least 5 mol% or more. A method for producing a biaxially stretched polyester film for molding, characterized in that a bent biaxial extrusion temperature condition for extruding a constituent resin satisfies the following formula (b).
t _{(0.2 wt%)} ≧ time _Temp formula (b)
(Here, t _{(0.2 wt%)} is _{0.2 wt%} when the PET-G resin is treated in an undried state in thermogravimetric analysis where heating is performed under an inert gas stream and a constant temperature. Indicates the time to reach
time _Temp indicates the time from the exit of the extruder to the T die when the molten resin is present.
The temperature corresponding to t _{(0.2 wt%)} and time _Temp is the resin temperature at the exit of the extruder. )