JP4587805B2 - High sensitivity heat sensitive stencil printing polyester film - Google Patents

Description

  The present invention relates to a heat-sensitive stencil sheet and a film used therefor. More specifically, the present invention is excellent in independence of punching at low energy by a thermal head, excellent in resolution (gradation) at the time of printing, storage stability of the master, curling properties, and printing durability that can withstand printing of a large number of sheets. The present invention relates to a film for a high-sensitivity heat-sensitive stencil printing paper excellent in durability (printing durability).

  Conventionally, as a heat-sensitive stencil sheet, a heat-sensitive stencil sheet in which an ink-permeable porous thin paper is bonded to a thermoplastic resin film such as polyester with an adhesive is known. The required properties of the film used for the heat-sensitive stencil sheet include perforation sensitivity, curl resistance, printing durability, image resolution and density during printing, and the like. In such a conventional heat-sensitive stencil sheet, the adhesive easily accumulates in the portion where the fiber overlaps the film and the portion where the film comes into contact. The portion is not sufficiently perforated by the thermal head, and the unperforated portion causes white spots during printing. Therefore, a master having a new configuration that does not obstruct the passage of ink has been proposed (Patent Document 1).

In recent years, high resolution is required for printed materials, and attempts are being made to reduce the size of individual heads and increase the number of perforations per unit area in order to obtain high resolution in perforation with a thermal head. In addition, in order to reduce the load on the thermal head and extend its life, it is necessary to reduce the energy supplied to each head. Therefore, there is a demand for a film that can be punched uniformly and reliably with low energy. Yes. That is, the film imparts a high shrinkage characteristic from a low temperature range so that it can be melted with a small amount of heat and perforated with an appropriate size can be obtained. For this reason, the perforated peripheral film is thermally deformed or the perforated shape becomes non-uniform, which causes the image to deteriorate in applications that require delicate and sharpness such as photographic images. ing.

  In addition, in order to achieve low energy perforation, a thin film is preferentially used. Therefore, a master curl due to film residual stress or a misfeed of the master due to insufficient rigidity of the master or a master clogging. It is a cause of trouble. Stencil printing is characterized by the printing of a large number of sheets, but depending on the characteristics of the film used, the pressure and abrasion resistance at the printing paper edge and the contact area of the stencil film are poor, and it is a factor that limits the number of printed sheets. Yes.

In order to solve the above problems, a film having improved printing characteristics and printing durability from a master structure has been proposed (Patent Document 1). Moreover, the film etc. which prescribed | regulated the polymer characteristic and the composition for the purpose of the advancement of a film are proposed (patent documents 2-4). However, these methods are insufficient, and there is a demand for a polyester film for heat-sensitive stencil printing paper that satisfies the independence of perforation, uniformity of perforation diameter, curl properties and printing durability, which are basic properties of the master at the same time.
Japanese Patent Laid-Open No. 10-24667 Japanese Patent Publication No. 7-64128 JP-A-3-39294 JP-A-2-307788

  The present invention has been made in view of the above circumstances, and the problem to be solved is to ensure piercing performance and piercing independence at a low energy, which has not been realized by the prior art, and to ensure uniform piercing diameter and piercing. Another object of the present invention is to provide a film that is excellent in improving the sharpness of a photographic image with little shrinkage distortion in the peripheral film, excellent in curling properties and printing durability, and capable of increasing the number of printable sheets.

  As a result of intensive studies in view of the above problems, the present inventors have found that the above problems can be easily solved by a film having a specific configuration, and have completed the present invention.

That is, the gist of the present invention is a film containing 80% by weight or more of a copolyester containing 10 to 40 mol% of 2,6-naphthalenedicarboxylic acid component and 5 to 70 mol% of 1,4-butanediol component. The melting point of the film is 130 ° C. to 230 ° C., the glass transition temperature is 50 ° C. to 80 ° C., the loss elastic modulus (G ″) is 100 Pa or more in the temperature range from the melting point temperature to 300 ° C., and the film thickness Is a polyester film for high-sensitivity heat-sensitive stencil printing base paper, characterized in that it is 0.5 to 7.0 μm.

Hereinafter, the present invention will be described in detail.
The polyester of the present invention refers to a polyester having aromatic dicarboxylic acid as the main acid component and alkylene glycol as the main glycol component. Examples of the aromatic dicarboxylic acid include terephthalic acid, isophthalic acid, and 2,6-naphthalenedicarboxylic acid. Examples of the alkylene glycol include ethylene glycol, 1,4 butanediol, triethylene glycol, tetramethylene glycol, neopentyl glycol, 1,4-cyclohexanedimethanol and the like. Such a polyester may be a polyester starting from one kind of aromatic dicarboxylic acid and one kind of alkylene glycol, but is preferably a copolymer containing three or more kinds of components.

  In any case, the composition of the film is appropriately selected so that the melting point is 130 to 230 ° C and the glass transition temperature is 50 to 80 ° C. A material having a melting point exceeding 230 ° C. is not preferable because a large amount of heat energy is required for perforation and the perforation characteristics are poor. Further, if the glass transition temperature is less than 50 ° C., the film dimensional change near room temperature increases, which causes the curling of the master, which is not preferable.

  The intrinsic viscosity of the polyester used in the present invention is usually 0.5 or more, preferably 0.6 to 1.0. When the intrinsic viscosity is less than 0.5, the film productivity is inferior and the mechanical strength of the film is insufficient. In addition, the loss elastic modulus related to the perforated diameter is small, and the temperature change is large. The viscosity of the polyester raw material used is effective in adjusting the loss elastic modulus in the high temperature range.

  The film thickness of the present invention is in the range of 0.5 to 7.0 μm, preferably in the range of 0.5 to 2.5 μm. If the thickness of the film is reduced, the heat transfer distance is shortened and the thermal energy required for punching is also reduced, so that the punchability is improved and the resolution at the time of printing is improved. If it is less than 0.5 μm, the productivity during film production and the winding workability deteriorate. A film having a thickness exceeding 7 μm is not preferable because even if the perforation energy is increased, the perforation property is poor and unevenness occurs during printing.

  In the film of the present invention, when the loss elastic modulus in the temperature range from the melting point to 300 ° C. is less than 100 Pa, the polymer flows at the time of perforation, the independent perforations are fused together, and continuous uniform perforations are obtained. Disappear. The loss elastic modulus is preferably 150 Pa or more. Further, when the temperature change of the loss elastic modulus is −100% or more, the deformation unevenness at the time of drilling and the diameter of the drill hole are non-uniform, and preferably the box where the temperature change of the loss elastic modulus is small in the temperature range where the hole is drilled at −70% or less The mold shape distribution is preferable to ensure the uniformity of the bore diameter.

  Since the film of the present invention is an extremely thin film, when the tensile elastic modulus in the longitudinal direction and the width direction of the film are both 3000 MPa or more, the film handling workability and transportability are good. The use of two or more kinds of polyester-based raw materials works effectively for adjusting the loss elastic modulus acting on the melting point, glass transition temperature and perforation diameter. Among the polyester-based raw materials to be used, the use of a raw material-based material containing 10 to 40% mol% of a 2,6-naphthalenedicarboxylic acid component works more effectively. If the blending amount exceeds 40%, the temperature dependency is large and the perforation diameters may be uneven.

  Polyethylene naphthalate as used in the present invention refers to a polymer whose structural units are substantially composed of polyethylene-2, 6-naphthalate units, but 25 mol% or less, ethylene-2 modified with a third component, 6-Naphthalate polymer is included. Polyethylene naphthalate is generally obtained by condensing naphthalene-2,6-dicarboxylic acid or a functional derivative thereof such as dimethyl naphthalene-2,6-dicarboxylate and ethylene glycol in the presence of a catalyst under suitable reaction conditions. Manufactured. In this case, as the third component, for example, dicarboxylic acid such as adipic acid, sebacic acid, phthalic acid, isophthalic acid, terephthalic acid, naphthalene-2,7-dicarboxylic acid, or a lower alkyl ester thereof, oxycarboxylic acid such as P-oxybenzoic acid Examples thereof include acids or lower alkyl esters thereof, or dihydric alcohols such as propylene glycol, trimethylene glycol, tetramethylene glycol, pentamethylene glycol, and hexamethylene glycol.

  Polyethylene terephthalate refers to polyester obtained using terephthalic acid or its ester and ethylene glycol as main starting materials, but may contain other third component. The polyester of the present invention refers to a polyester having 80% or more of repeating structural units. Polyethylene terephthalate isophthalate refers to a copolyester in which 65 mol% or more of the dicarboxylic acid component is terephthalic acid, 10 mol% or more is isophthalic acid, and 70% or more of the diol component is ethylene glycol.

  The polybutylene terephthalate here is 70 mol% or more of the dicarboxylic acid component, preferably 80 mol% or more is terephthalic acid, 75 mol% or more, preferably 80% mol% or more of the diol component is 1,4-butanediol. It refers to a certain polyester.

  As 2,6 naphthalene copolymer, 3 to 50 mol% of the acid component is composed of 2,6-naphthalenecarboxylic acid component, and 5 to 70 mol% of the glycol component is composed of 1,4 butanediol. Refers to polyester.

  The polyester film of the present invention can be obtained by melt-kneading the PEN polyester, PET polyester, and PBT polyester as the components described above. This kneading is usually performed at the time of film formation or may be previously kneaded at a stage before film formation. This melt-kneading is carried out so as to disperse uniformly.

  In addition, the film of the present invention is used to improve the workability during winding process during film production, coating during base paper production, laminating process and printing, or preventing thermal head and film from fusing during thermal drilling. Therefore, it is preferable to roughen the surface to give the film appropriate slipperiness, but for that purpose, fine inert particles may be added to the film. The average particle diameter of the fine inert particles used is preferably 0.2 to 1.0 times the film thickness, more preferably 0.3 to 0.7 times, and particularly preferably 0.3 to 0.00. 5 times. If the average particle size is 1.0 times or more of the film thickness, the flatness of the film surface may be impaired, resulting in uneven heat transfer, uneven perforation, poor resolution, and print quality. May be damaged. On the other hand, when the average particle size is less than 0.2 times the film thickness, workability during film production and base paper production tends to deteriorate, such as poor winding properties of the film.

  The amount of particles added is usually 0.05 to 3.0% by weight, preferably 0.1 to 2.0% by weight. If it is less than 0.05% by weight, the winding properties tend to be inferior. On the other hand, if the amount exceeds 3% by weight, the degree of roughening of the film surface tends to be too large and uneven heat transfer tends to occur, resulting in uneven perforation, poor resolution, and impaired print quality. Sometimes.

  Examples of inert particles used in the present invention include silicon oxide, titanium oxide, zeolite, silicon nitride, boron nitride, celite, alumina, calcium carbonate, magnesium carbonate, barium carbonate, calcium sulfate, barium sulfate, calcium phosphate, lithium phosphate. , Magnesium phosphate, lithium fluoride, kaolin, talc, carbon black, and crosslinked polymer fine powder as described in JP-B-59-5216, but are not limited thereto. . At this time, the inert particles to be blended may be a single component, or two or more components may be used simultaneously. In the present invention, the method of blending the inert particles with the polyester is not particularly limited. For example, a method of adding the inert particles to the polyester polymerization step or a method of melt-kneading before film formation is preferably used.

  In the present invention, a film whose surface is appropriately roughened by the method as described above is obtained, but in order to satisfy the workability, the resolution at the time of printing, and the print quality more highly, the center line average of the film surface is obtained. The roughness (Ra) is preferably 0.02 to 0.2 [mu] m, more preferably 0.05 to 0.15 [mu] m, and it is desirable to select conditions appropriately so as to be in this range.

Next, the manufacturing method of the polyester film of this invention is demonstrated.
In the present invention, the polymer is supplied to a well-known melt extrusion apparatus typified by an extruder, and heated to a temperature equal to or higher than the melting point of the polymer to melt. Next, the molten polymer is extruded from a slit-shaped die and rapidly cooled and solidified on the rotary cooling drum so that the temperature is equal to or lower than the glass transition temperature, thereby obtaining a substantially amorphous unoriented sheet. In this case, in order to improve the flatness of the sheet, it is preferable to improve the adhesion between the sheet and the rotary cooling drum, and usually an electrostatic application adhesion method is employed.

  The sheet thus obtained is stretched in the biaxial direction to form a film. The stretching conditions will be specifically described. The unstretched sheet is preferably 75 to 100 ° C., more preferably 75 to 90 ° C., and 2.5 to 7.0 times in one direction, preferably 3. Stretch from 0 to 5.0 times. Next, stretching is preferably performed at a temperature range of 70 to 100 ° C., more preferably 75 to 95 ° C. in a direction orthogonal to the first stage, 2.5 to 7.0 times, preferably 3.0 to 5.0 times. A biaxially oriented film is obtained.

  Note that a method of performing unidirectional stretching in two or more stages can also be used, but in this case as well, it is desirable that the final stretching ratio is in the above-described range. Further, the unstretched sheet can be simultaneously biaxially stretched so that the area magnification is 6 to 40 times. The film thus obtained may be heat-treated, and heat-treated as necessary.

  Further, when producing a heat-sensitive stencil base paper, curling that may be caused by film shrinkage may occur during a drying process of about 40 to 70 ° C. and long-term storage through summer. Therefore, in order to prevent curling in the present invention, when the obtained film is aged at 30 to 50 ° C. for 5 hours to 5 days, preferably at about 40 ° C. for 12 hours to 3 days, the curl resistance in the environment is good. It becomes.

  The film for heat-sensitive stencil of the present invention can adjust the hole diameter size and the hole independence, and the film deformation around the hole by adjusting the temperature characteristics of the melt viscoelasticity near the temperature punched by the thermal head. As described above, a clear image can be obtained for high image quality applications in which the perforation probability and the perforation size are problems, and its industrial value is high.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to a following example, unless the summary is exceeded. In addition, the physical-property measuring method used by this invention is as showing below.

(1) Melting point and glass transition temperature Measured using TA instruments DSC-2920 type. The DSC measurement conditions are as follows. That is, 10 mg of a sample film was set in a DSC apparatus, melted and stored at a temperature of 300 ° C. for 5 minutes, and then rapidly cooled with liquid nitrogen. The rapidly cooled sample was heated from 0 ° C. at a rate of 10 ° C./min, and the glass transition temperature (Tg) and the melting point (Tm) were measured. Tg is sensed in such a way that the DSC curve bends due to the change in specific heat and the baseline moves in parallel. The intersection point between the tangent line of the base line at a temperature equal to or lower than the bending point and the tangent line of the point where the inclination is maximum at the bent portion is defined as a bending start point, and this temperature is defined as Tg. Tm was measured as an endothermic peak temperature due to melting.

(2) Loss elastic modulus temperature characteristic G ″ (Pa)
The measurement was performed using a viscoelasticity measuring device MCR30 manufactured by Nippon Shibel Hegner. The loss elastic modulus temperature change from 70 ° C. to 300 ° C. was measured. The measurement was carried out by punching from a film in which test pieces having a diameter of 20 mm were stacked, melting in a high-temperature bath, compressing with a measuring plate, cooling to 70 ° C., and then raising the temperature to 300 ° C. at a rate of 2 ° C./min. The temperature change of the loss elastic modulus G "(Pa) was calculated by the following formula.
Rate of change (%) = (loss elastic modulus at 230 ° C.-270 ° C. loss elastic modulus) × 100/230 ° C. loss elastic modulus

(5) Curling resistance Using a Japanese paper made of Manila hemp fibers as a support on a 1.5 μm polyester film, using a vinyl resin dissolved in toluene as an adhesive, laminating the film and Japanese paper, 50 ° C. Was dried in an air oven for 10 seconds to obtain a heat-sensitive stencil sheet. The obtained base paper was treated for 1 week in a constant temperature and humidity of 50 ° C. and 90% humidity. In the curl test, a 50 mm wide test piece was cut out from the above-mentioned sample and left at 25 ° C. and 65% RH, and the curl amount was measured by measuring the curl height at both ends of the test piece. The diameter was measured when curling into a cylindrical shape because of poor curl properties. A height of 10 mm or less at both ends of the test piece is not a practical problem. The curl amount was measured in two directions perpendicular to the longitudinal direction, and a value with a large curl amount was defined as the curl amount of the film.

(6) Practical characteristics of heat-sensitive stencil printing base paper Washi paper was bonded to a film to prepare a base paper. The obtained base paper was subjected to plate making of a character image and a 16-step gradation image with a thermal head at an applied energy of -50% of standard printing energy and standard energy. The perforated state of the gradation image portion was observed with a microscope from the film side of the plate-making base paper, and the following items were evaluated.

(A) Perforation independence and uniformity ◎ ... Predetermined perforation is reliably performed, the perforation diameter is uniform, and no continuous hole is observed ○ ... Predetermined perforation is almost certainly performed, and the perforation diameter is almost uniform △… There are rarely the part where the predetermined perforation cannot be obtained and there are parts where the perforation size is insufficient. ×… There are many parts where the predetermined perforation cannot be obtained, and the size of the perforation is insufficient. In addition, there is a problem in practical use. Further, the following characteristics were visually determined for the characters and images obtained by actually printing using a stencil paper and using a Ricoh Priport VT3950 printer.

(B) Print image quality ◎ ... There is no uneven density or blurring, and it can be printed clearly. ○ ... There is no uneven density or blurring, and it can be printed clearly. △ ... Slight unevenness or blurring is observed, and it is slightly clear. ×… Shading unevenness, blurring, or faintness

(C) Wrinkles around the perforations and distortion of plate making ◎… No film wrinkles are observed around the continuously perforated portion of the solid printing portion ○ ○ Slight film wrinkles are found around the perforated portion of the continuously printed portion X: Film wrinkles are observed in a wide range around the perforated part of the solid printed part.

(D) Printing durability The film was brought into contact with a metal drum having a diameter of 25 mm at 180 degrees and repeatedly worn at a speed of 10 mm / min. The abrasion length was 75 mm, and abrasion was repeated for 24 hours. The evaluation was based on three stages of film surface change and film damage level.
○: Little change in film surface and little damage Δ: Thin scratches are observed on the film surface, but no significant film wear is observed ×: The film surface is partially destroyed from the perforated part

Next, production of each polyester used in each example will be described.
(Polyester A)
75 mol% of dimethyl terephthalate, 25 mol% of dimethyl 2,6-naphthalenedicarboxylate, 50 parts by weight of ethylene glycol, 50% of 1,4 butanediol, 0.005% by weight of tetrabutyl titanate are put in a reactor, and the reaction start temperature is set. The reaction temperature was gradually raised with the distillation of methanol at 150 ° C., and the temperature was adjusted to 210 degrees after 3 hours. After 4 hours, 0.5 parts by weight of an ethylene glycol slurry in which spherical silica particles having an average particle diameter of 1.2 μm were dispersed was added to the reaction mixture in which the transesterification reaction was substantially completed. After adding 005% by weight, the polycondensation reaction was carried out 4 hours later. At this time, the temperature was gradually raised from 220 ° C. to 280 ° C. On the other hand, the pressure was gradually reduced from the normal pressure, and finally 0.3 mmHg. The reaction was stopped when 5 hours were obtained after the start of the reaction, and the polymer was blown out under nitrogen pressure to obtain a copolyester. Three types of polymer [η] were obtained: high viscosity [η] = 0.74, medium viscosity [η] = 0.65, and low viscosity [η] = 0.54.

(Polyester B)
Transesterification was carried out using 100 parts by weight of dimethyl 2,6-naphthalenedicarboxylate, 60 parts by weight of ethylene glycol and 0.1 part by weight of calcium acetate-hydrate as a reactor. That is, the reaction start temperature was set to 180 ° C., and the reaction temperature was gradually raised with the outflow of methanol, and after 4 hours, reached 230 ° C. to complete the substantial transesterification reaction. Next, 0.04 part by weight of phosphoric acid was added, 0.30 part by weight of calcium carbonate having an average particle diameter of 1.5 μm and 0.04 part by weight of antimony trioxide were added, and a polycondensation reaction was carried out by a conventional method. That is, the temperature was gradually decreased and the pressure was gradually decreased from the normal pressure, and after 2 hours, the temperature was 290 ° C. and the pressure was 0.3 mmHg. The reaction was stopped at the time when 4 hours were obtained after the start of the reaction, and polyethylene naphthalate was discharged under nitrogen pressure. [Η] of the obtained polyethylene naphthalate was 0.65.

(Polyester C)
100 parts by weight of dimethyl terephthalate, 60 parts by weight of ethylene glycol and 0.1 part by weight of calcium acetate-hydrate were placed in a reaction vessel, and the polyester was exchanged. That is, the polyester exchange reaction start temperature was set to 170 ° C., the reaction solution was heated with methanol flowing out to start the ester exchange reaction, and heated to 230 ° C. after 4 hours to carry out the ester exchange reaction. 5 parts by weight of an ethylene glycol slurry containing 0.5% by weight of spherical silica particles having an average particle diameter of 0.70 μm was added to the reaction product after the transesterification reaction, and 0.04 part by weight of phosphoric acid was then added. Thereafter, 0.005 part by weight of tetrabutyl titanate was added to carry out a polycondensation reaction. That is, the reaction solution was heated, the pressure in the system was decreased, and polycondensation was started. After 2 hours, the reaction solution was heated to 280 ° C. and depressurized to 0.3 mmHg. Furthermore, when several hours passed, the polycondensation reaction was stopped to obtain polyester A. [Η] of this polyester A was 0.70.

(Polyester D)
In polyester D, polyester D was obtained in the same manner as polyester C described above except that 100 parts by weight of dimethyl terephthalate was changed to 78 parts by weight of dimethyl terephthalate and 22 parts by weight of dimethyl isophthalate. [Η] of this polyester D was 0.70.

(Polyester E)
In Polyster E, 100 parts by weight of dimethyl terephthalate. Polyester E was obtained in the same manner as polyester C described above, which was 56 parts by weight of 1,4-butanediol. [Η] of this polyester was 1.05 .

Example 1
Raw material of polyester A: [η] = 0.74 is extruded into 100 parts by weight with a twin-screw extruder at 265 ° C., and is rapidly cooled and solidified by an electrostatic application cooling method on a rotary cooling drum whose surface temperature is set at 30 ° C. A substantially amorphous sheet having a thickness of 25 μm was obtained. The resulting sheet was stretched 4.0 times in the longitudinal direction at 83 ° C, then stretched 4.2 times in the transverse direction at 90 ° C, and then subjected to heat treatment for 5 seconds while relaxing 2.0% at 95 ° C. A biaxially oriented film having a thickness of 1.5 μm was produced. Then, the obtained film was bonded to a porous thin paper in accordance with a conventional method to prepare a heat-sensitive stencil printing base paper, which was subjected to copying printing .

(Example 2)
In Example 1, film formation was performed in the same manner as in Example 1 except that 90 parts by weight of polyester raw material: polyester A [η] = 0.64 and 10 parts by weight of polyester C were melt kneaded by a twin screw extruder. A base paper for heat-sensitive stencil printing was prepared and copied .

(Example 3)
The polyester raw material was implemented except that 80 parts by weight of polyester A [η] = 0.65, 10 parts by weight of polyester C, 5 parts by weight of polyester E, and 5 parts by weight of polyester D were melt kneaded by a twin screw extruder. A film was formed in the same manner as in Example 1 to prepare a heat-sensitive stencil printing base paper, and copying was performed .

(Comparative Example 1)
Polyester raw materials were polyester B: 15 parts by weight, polyester D: 35 parts by weight, polyester E: 50 parts by weight by a twin-screw extruder, and formed into a film by the same method as in Example 1. Fabricated and printed.

(Comparative Example 2 )
The polyester raw material was 100 parts by weight of polyester A [η] = 0.54 and extruded and formed into a film using a twin-screw extruder under the same conditions as in Example 1 to produce a heat-sensitive stencil base paper and copy-printed.

(Comparative Example 3 )
Polyester D: Extruded 100 parts by weight with a twin-screw extruder and formed a film in the same manner as in Example 1 except that the transverse stretching temperature was changed to 96 ° C. and the heat treatment temperature was changed to 102 ° C. to produce a heat-sensitive stencil printing base paper, Copied printing was performed.

(Comparative Example 4 )
A method similar to Example 1 except that 50 parts by weight of polyester raw material D and 50 parts by weight of polyester E are melt-kneaded with a twin screw extruder instead of the three types of blends of polyester B, polyester D and polyester E in Example 4. To form a film. Except that the longitudinal stretching temperature was changed to 75 ° C., the lateral stretching temperature was changed to 80 ° C., and the heat treatment temperature was changed to 105 ° C., a film was formed in the same manner as in Example 1 to prepare a heat-sensitive stencil printing paper and copy-printed.

上記表中、Ａは、ＤＭＴ／ＮＤＣＥ／ＥＧ／１，４Ｂ系、ＢはＰＥＮ系、ＣはＰＥＴ系、ＤはＩＰＡ系、ＥはＰＢＴ系である。

In the above table, A is DMT / NDCE / EG / 1, 4B system, B is PEN system, C is PET system, D is IPA system, and E is PBT system.

The film of the present invention can be suitably used, for example, as a film for a highly sensitive heat-sensitive stencil sheet.

Claims (1)

It is a film containing 80% by weight or more of a copolymerized polyester containing 10 to 40 mol% of 2,6-naphthalenedicarboxylic acid component and 5 to 70 mol% of 1,4-butanediol component, and the melting point of the film is 130 ° C. ˜230 ° C., glass transition temperature is 50 ° C. to 80 ° C., loss elastic modulus (G ″) is 100 Pa or more in the temperature range from melting point temperature to 300 ° C., and film thickness is 0.5 to 7.0 μm. A polyester film for a high-sensitivity heat-sensitive stencil sheet.