WO2020175058A1

WO2020175058A1 - Biaxially oriented polyester film, and production method for biaxially oriented polyester film

Info

Publication number: WO2020175058A1
Application number: PCT/JP2020/004302
Authority: WO
Inventors: 昇玉利; 考道後藤; 雅幸春田
Original assignee: 東洋紡株式会社
Priority date: 2019-02-26
Filing date: 2020-02-05
Publication date: 2020-09-03
Also published as: JPWO2020175058A1; JP6826784B2

Abstract

A biaxially oriented polyester film including a polyester resin composition that contains a polybutylene terephthalate resin (A) at a proportion of 60-100 mass%, said biaxially oriented polyester film having at most 7 layers and satisfying the following requirements: (1) the intrinsic viscosity of the biaxially oriented polyester film is 0.7 dl/g or higher; (2) the absolute value of the orientation angle of the biaxially oriented polyester film is 25° or greater; (3) the planar orientation ΔP of the biaxially oriented polyester film is 0.145-0.160; (4) the puncture strength of the biaxially oriented polyester film as measured by a puncture test conforming to JIS-Z1707 is 0.40 N/μm or greater; and (5) the thickness variation in the biaxially oriented polyester film is 0.7% or less.

Description

\¥0 2020/175058 1 卩 (: 17 2020 /004302 Clear details

Title of invention:

Biaxially oriented polyester film, and method for producing biaxially oriented polyester film

Technical field

The present invention relates to a biaxially oriented polyester film, and a method for producing the biaxially oriented polyester film.

Background technology

[0002] Polybutylene terephthalate (hereinafter, referred to as polybutylene terephthalate) is a polyethylene terephthalate (hereinafter, polyethylene terephthalate is abbreviated as "mite") resin, which is superior in moldability to a vacuum heat insulating material. Applications are also being investigated in the fields of exterior materials, drawing films, films for can inner bags, release films, etc.

[0003] For example, in Patent Document 1, 60% by weight of Mingko resin is used, yield stress in the longitudinal and width directions is 7 OMPa or more, breaking strength is 160 IV! 3 or more, and breaking elongation is It is disclosed that the content of 100% or more can be preferably used for nylon film and other flexible film applications.

[0004] In Patent Document 2, a release layer containing an acid-modified olefin resin and a cross-linking agent is provided on one side of a polyester film containing substantially no particles, and a release layer having an easy-sliding layer is provided on the other outermost layer. Mold films are disclosed. Further, the arithmetic average roughness of the surface of the release layer is 10 n 01 or less, the maximum height is 100 n or less, and the easy sliding layer contains particles, the easy sliding layer contains particles, The arithmetic mean roughness of the surface of the easy-slip layer is 10

It is disclosed that it can be preferably used by setting it to less than.

[0005] In Patent Document 3, the surface roughness is 0.05 to 0.

The difference in the thermal shrinkage ratio in the longitudinal direction at both ends of the film is 0 to 0.3%, and the difference in anisotropy is 0 to 0.

When it is set to 20, it is considered that it can be suitably used as a release film. \¥0 2020/175058 2 卩 (: 17 2020 /004302

It is shown.

Prior art documents

Patent literature

[0006] Patent Document 1: Patent No. 5 9 9 4 8 6 4

Patent Document 2: JP 2 0 1 6-2 2 1 7 3 7

Patent Document 3: Patent No. 3 0 3 1 5 2 0 Summary of Invention

Problems to be Solved by the Invention

[0007]Because the Mitomo resin has a high crystallization rate, crystallization proceeds even during casting.

In particular, the end portion of the film obtained by casting tends to be thicker than the center portion for manufacturing reasons. Therefore, crystallization becomes more remarkable at the edges of the film obtained by casting.

In the above-mentioned Patent Document 1, a static mixer is used to form the super-multilayer before extruding the molten resin from the die. Therefore, crystals do not grow between the layers, and as a result, crystallization during casting can be suppressed. On the other hand, by introducing a static mixer in the melt line, the dead area (retention area) increased, and gel was generated in that area, resulting in the formation of fish eyes (small particle defects) in the film. There is a possibility that the number will increase and the quality will be insufficient for industrial applications requiring high quality.

In the above Patent Documents 2 and 3, polyethylene terephthalate is preferably used as a release film by using it as a substrate film. On the other hand, for release film applications that involve molding, it may not be possible to support deep drawing due to the characteristics of the polyethylene terephthalate substrate.

[0008] The present invention has been made in view of the above problems. That is, an object of the present invention is to provide a biaxially oriented polyester film which has a good film quality that can be used for industrial applications and is also suitable as a release film accompanied by deep drawing. \¥02020/175058 3 ((171?2020/004302

Means for solving the problem

[0009] The present inventors have earnestly studied a biaxially oriented polyester film. As a result, it was found that, by adopting the following constitution, a biaxially oriented polyester film having good deep-drawing moldability and having few fish eyes in the film and excellent quality can be obtained, and the present invention is completed. Came to.

That is, the biaxially oriented polyester film according to the present invention,

A polyester resin composition containing 60 to 100 mass% of a poly(ethylene terephthalate) resin (eight),

The number of layers is 7 or less,

It is characterized by satisfying the following requirements (1) to (5).

(1) The intrinsic viscosity of the biaxially oriented polyester film is 0.7 丨/ ₉ or more.

(2) The absolute value of the orientation angle of the biaxially oriented polyester film is 25 degrees or more.

(3) The degree of plane orientation △ of the biaxially oriented polyester film is ○ 0.145 to ○.

1600

(4) ”The puncture strength of the biaxially oriented polyester film measured by the puncture test according to 1 3-7 1 7 0 7 is 0.401\1/1 or more.

(5) Thickness unevenness of the biaxially oriented polyester film is 0.7% or less.

[001 1] According to the above-mentioned constitution, since the polyester resin composition containing 60% by mass or more of the polypropylene terephthalate resin (8) is contained, the puncture strength can be improved. In addition, since the polyester resin composition containing the poly(ethylene terephthalate) resin (8) in an amount of 60% by mass or more is included, the drawability can be improved.

Further, since the number of laminated layers is 7 or less, it is possible to manufacture without introducing a static mixer in the melt line. Therefore, it is possible to prevent the generation of fish eyes (small particle defects) in the film caused by the introduction of the static mixer. As a result, a film with high quality can be obtained.

In addition, since the intrinsic viscosity is 0.7 0.7 /9 or more, the biaxially oriented polyester is \¥02020/175058 4 卩 (: 171?2020/004302

When a resin composition for producing a steal film is cast on a cooling port to obtain an unstretched sheet, crystallization of the unstretched sheet can be suppressed, and the yield stress at the thick end is particularly You can avoid getting too high. As a result, it can be made difficult to break in the stretching process.

Further, the absolute value of the orientation angle is 25 degrees or more. The larger the absolute value of the orientation angle, the closer to the widthwise end of the film. If the plane orientation angle is less than 25 degrees, the film is near the center in the width direction of the film, so when the molten resin is in close contact with the cooling port, the end of the cold air blown from the face side by the multi-duct. The effect of lowering the temperature is less. For films that have an absolute orientation angle of 25 degrees or more and are close to the edges in the width direction, when the molten resin is adhered to the cooling holes, the edges of the cold air blown by the multi-duct from the face side By lowering the temperature, the number of breaks during film formation can be reduced, and the thickness unevenness of the obtained film can be reduced.

Further, the plane orientation degree is 0. 145 to 0. 160. Since the above-mentioned degree of plane orientation Δ is not less than 0.145, the plane orientation is suitably high, the puncture strength is sufficient, and the deep drawability is superior. Since the plane orientation degree Δ is not more than 0.160, the heat shrinkage can be kept low and the thermal stability can be made better.

Further, since the puncture strength is 0.401\1/1 or more, the deep drawing formability can be improved.

In addition, since the thickness variation is 0.7% or less, uniform molding can be performed when deep drawing is performed, and tearing of the film and pinholes are less likely to occur.

[0012]The biaxially oriented polyester film of the present invention is assumed to be a film after production (after casting and stretching treatment), that is, a film not subjected to slit treatment (film in a mill roll state). ing. However, the biaxially oriented polyester film of the present invention contains a polyester resin composition containing 60 to 100% by weight of a polybutylene terephthalate resin (8), and the number of laminated layers is 7 or less, and the above requirement (1 )-(5) \¥02020/175058 5 卩 (: 171?2020/004302

The film is not limited, and includes, for example, a film made into small pieces by slit processing or the like, and a single film.

[0013] In the above structure, it is preferable that the polyester resin composition contains a polyester resin (Mitsumi) other than the polyethylene terephthalate resin (8).

[0014] When the polyester resin composition contains a polyester resin (Mitsumi) other than the polypropylene terephthalate resin (8), the film formability during biaxial stretching and the mechanical properties of the obtained film can be adjusted. You can

[0015] In the above configuration, the maximum diameter on the biaxially oriented polyester film is ◯.

It is preferable 3_Rei! 〇! Or more of the fish eye is five / Rei_1 ² or less.

[0016] When the fish-eye is a ^5/2 or less, to one surface of the biaxially oriented polyester film, may have a release layer, when the winding storage, opposite to the release layer It is possible to suppress the transfer of unevenness to the release layer by the fish eyes on the surface. As a result, it is possible to make it difficult to impair the film quality. Also, the film can be provided with elaborate printing layers.

[0017] Further, the present invention is the method for producing a biaxially oriented polyester film, which comprises a step of casting a resin composition for producing a biaxially oriented polyester film in a cooling port to form an unstretched sheet. When,

And a process step of blowing air to the unstretched sheet on the cooling port, the process step, when the total width of the unstretched sheet is 100%, the temperature of the wind blown to the center is X, When the temperature blown to both ends is assumed to be less than 1, X is 15 ^° or less, and the temperature is lower than X, and the end is at least 1 from the edge. It is characterized by including the area within 0%.

[0018] According to the above-mentioned configuration, the unstretched sheet on the cooling port is blown with a wind of not more than 15°, and the unstretched sheet has a mound surface (a surface opposite to the surface in contact with the cooling port) ) Is rapidly cooled, the crystallinity can be reduced and the film-forming property can be improved. \\02020/175058 6 卩 (: 171-12020/004302

In addition, the thickness of the end portion of the unstretched sheet is often thicker than that of the central portion. By quenching the end portion (at least a region within 10% from the edge) more strongly than the center there, crystallization can be suppressed in the end portion corresponding to the center portion, and the film forming property can be improved.

[0019] In the above configuration, it is preferable that the temperature is 10 ^° or less. When the grain diameter is 10° or less, the crystallinity of the end face of the unstretched sheet does not become too high and the film formability becomes better.

Effect of the invention

[0020] According to the present invention, it is possible to provide a biaxially oriented polyester film which has good deep-drawing moldability, has few fish eyes in the film, and is excellent in quality.

Brief description of the drawings

[0021] [Fig. 1] Fig. 1 is a schematic front view for explaining a method of blowing cooling air from a multi-duct onto a mound surface of an unstretched sheet on a cooling port.

[Fig. 2] Fig. 2 is a side view of Fig. 1.

FIG. 3 is a bottom view showing an example of a multi-duct.

[FIG. 4] A cross-sectional view of a mold used for evaluation of deep drawing formability.

FIG. 5 is a plan view of the mold shown in FIG. MODE FOR CARRYING OUT THE INVENTION

[0022] Hereinafter, embodiments of the present invention will be described.

[0023] The biaxially oriented polyester film according to the present embodiment is

The number of layers is 7 or less,

A biaxially oriented polyester film which satisfies the following requirements (1) to (5).

(2) The absolute value of the orientation angle of the biaxially oriented polyester film is 25 degrees or more. \¥02020/175058 7 卩(: 171-12020/004302

1 60 〇

(4)” 13-71 The piercing strength of the biaxially oriented polyester film measured by the piercing test according to 707 is 0.401 \1/ or more.

[0024] [Composition of biaxially oriented polyester film]

The polyester resin composition has a minor resin () as a main constituent, and the content of the minor resin (8) in the polyester resin composition is 60% by mass or more. It is preferably 75% by mass or more, and more preferably 90% by mass or more. When the amount is 60% by mass or more, the puncture strength can be made sufficient and the deep drawing moldability can be improved. Mingho resin (8) is used as a dicarboxylic acid component. Thus, the content of terephthalic acid is preferably 90 mol% or more, more preferably 95 mol% or more, still more preferably 98 mol% or more, and most preferably 100 mol%. The glycol component is preferably 1,4-butanediol in an amount of 90 mol% or more, more preferably 95 mol% or more.

[0025] The lower limit of the intrinsic viscosity of the above-mentioned Mingko resin (8) is preferably 〇0.80 / ₉ , more preferably 〇0.95/ ₉ , and further preferably 1.0 I/9. .. By setting the intrinsic viscosity of Mending resin () to be 0.80 丨/ ₉ or more, the intrinsic viscosity of the film obtained by film formation can be increased, and the deep drawability and film formability are improved. be able to.

The upper limit of the intrinsic viscosity of the Mouto resin () is preferably 1.3 丨/ ₉ . 1.

With丨/ ₉ or less, to suppress a high stress during film stretching Risugiru, the film-forming property can be improved. Furthermore, when using Mingbo resin with a high intrinsic viscosity, the melting temperature of the resin increases, so it is necessary to raise the extrusion temperature, but Mingo with an intrinsic viscosity of 1.3 I / 9 or less. \¥02020/175058 8 卩 (: 171?2020/004302

By using the resin (8), it is not necessary to perform high temperature extrusion, and the generation of decomposition products can be suppressed.

[0026] The polyester resin composition contains a polyester resin (M) other than the Ming resin (8) for the purpose of adjusting film-forming properties during biaxial stretching and mechanical properties of the obtained film. Is preferred.

Examples of the polyester resin (Mitsumi) include polyester, polyethylene naphthalate, polypropylene naphthalate, polypropylene terephthalate and the like, or isophthalic acid, orthophthalic acid, naphthalenedicarboxylic acid, biphenyldicarboxylic acid, cyclohexanedicarboxylic acid. Acid, adipic acid, azelaic acid, sebacic acid, and at least one dicarboxylic acid copolymerized with Mitsuba resin, ethylene glycol, 1,3-propylene glycol, 1,2-propylene glycol , Neopentyl glycol, 1,5-pentane diol, 1,6-hexane diol, diethylene glycol, cyclohexane diol, polyethylene glycol, polytetramethylene glycol and at least one diol component selected from the group consisting of polycarbonate. At least one dicarboxylic acid selected from the group consisting of polymerized benign resin, isophthalic acid, orthophthalic acid, naphthalenedicarboxylic acid, biphenyldicarboxylic acid, cyclohexanedicarboxylic acid, adipic acid, azelaic acid and sebacic acid. Methylene resin copolymerized with 1,3-butanediol, 1,3-propylene glycol, 1,2-propylene glycol, neopentyl glycol, 1,5-pentanediol, 1,6-hexanediol , Diethylene glycol, cyclohexanediol, polyethylene glycol, polytetramethylene glycol, and polycarbonate, and at least one resin selected from the Mending resins copolymerized with at least one diol component selected from the group consisting of To be

[0027] Among them, the resin mainly composed of mitoba has a high melting point, is excellent in heat resistance, has good compatibility with mitoba resin and is excellent in transparency, and therefore mitoba resin or copolymerized mitoba resin is preferable. Mingko resin is particularly preferable. \¥02020/175058 9 卩 (: 171?2020/004302

[0028] The amount of the polyester resin (M) added is preferably 40% by mass or less, more preferably 30% by mass or less, and further preferably 20% by mass, based on the entire polyester resin composition. % Or less, particularly preferably 10% by mass or less. When the amount of the polyester resin (Mitsumi) added is 30% by mass or less, the puncture strength can be further increased, and the deep drawability is more excellent. Also, the transparency can be kept high. Further, the addition amount of the polyester resin (Mitsumi), which has excellent impact strength and pinhole resistance, is 0% by mass or more, 10% by mass or more, 20% by mass or more based on the whole polyester resin composition. can do.

[0029] The lower limit of the intrinsic viscosity of the polyester resin (Mitsumi) is preferably 0.5 I/

It is 9, more preferably 0.6 丨/ ₉ , and even more preferably 0.8 丨/9. The upper limit of the intrinsic viscosity of the polyester resin (Mitsumi) is preferably 1.3 丨/ ₉ . By setting the intrinsic viscosity of the polyester resin (Mitsumi) within the above numerical range, it becomes possible to mix the polyester resin (Mitsumi) with the Mitsuko resin (Hachi) better.

[0030] The biaxially oriented polyester film contains, in addition to the polyester resin composition, conventionally known additives such as a lubricant, a stabilizer, a colorant, an antioxidant, an antistatic agent, and an ultraviolet absorber. It may be contained.

[0031] When the total amount of the biaxially oriented polyester film is 100% by mass, the content of the polyester resin composition is preferably 99.5% by mass or more, and more preferably 99.6% by mass or more. , 99.7 mass% or more is more preferable. The content of the polyester resin composition is preferably 100% by mass or less, when the total amount of the biaxially oriented polyester film is 100% by mass, and 99.

9 mass% or less is more preferable, and 99.8 mass% or less is further preferable.

The above-mentioned lubricant can adjust the dynamic friction coefficient of the film, and examples thereof include inorganic lubricants such as silica, calcium carbonate and alumina, and organic lubricants. Silica and calcium carbonate are more preferable, and silica has a low haze. \¥0 2020/175058 10 卩 (: 171-1? 2020 /004302

It is particularly preferable in that it is reduced. By these, transparency and slipperiness can be exhibited.

The lower limit of the content of the lubricant in the biaxially oriented polyester film is preferably 100 mass 111, more preferably 800 mass 111. When the amount is 100 mass or more, the slipperiness can be improved. The upper limit of the lubricant content is preferably 2000 mass 111, more preferably 100 mass, and particularly preferably 180 mass 111. By setting the amount to be 200 mass% or less, transparency can be maintained.

[0034] [Layer constitution of biaxially oriented polyester film]

The biaxially oriented polyester film has 7 or less laminated layers. The number of laminated layers is more preferably 3 or less. From the viewpoint of reducing fish eyes, a single layer is most preferable. When it is desired to improve the surface properties of the film, a layer structure of 2 types 2 layers, 2 types 3 layers, or 3 types 3 layers in which a plurality of types of layers having different compositions are laminated is preferable. Properties that improve include slipperiness, antistatic properties, ultraviolet cutability, and easy adhesion. The improvement of these surface properties can be achieved by adding a lubricant, an antistatic agent, an ultraviolet absorber, a copolymer, and their auxiliaries to the surface layer of the plurality of layers.

[0035] [Characteristics of biaxially oriented polyester film]

(1) Intrinsic viscosity of biaxially oriented polyester film

The biaxially oriented polyester film has an intrinsic viscosity of 0.7 0.7 / ₉ or more. The intrinsic viscosity is preferably at least 0.751/ _9, more preferably at least 0.80

That is all. Since the intrinsic viscosity is 0.7 7 / ₉ or more, when the resin composition for producing a biaxially oriented polyester film is cast in a cooling port to obtain an unstretched sheet, the unstretched sheet is crystallized. It can be suppressed, and the yield stress can be prevented from becoming too high especially at the thick end. As a result, it can be made difficult to break in the stretching step. \¥02020/175058 11 卩 (: 171-1? 2020 /004302

Further, the inherent viscosity is preferably 1. is a 20 I / less, more preferred is properly 1. is 1 5丨/ ₉ or less, more preferably 1 0丨/ ₉ hereinafter 1.. When the intrinsic viscosity is 1.20 丨/9 or less, the stress during stretching does not become too high and the film-forming property becomes better.

The intrinsic viscosity of the unstretched sheet is almost the same as the intrinsic viscosity of the biaxially oriented polyester film, the lower limit is preferably 0.7 I / 9, and more preferably 0. 75 I / ₉ , It is more preferably 0.80 / ₉ , and particularly preferably 0.90 / ₉ .

In addition, in order to set the intrinsic viscosity of the biaxially oriented polyester film in a preferable range, it is preferable to set the extrusion temperature as low as possible. Although the temperature changes depending on the intrinsic viscosity of the polyester resin used, the shape of the extruder, etc., lowering the intrinsic viscosity of the biaxially oriented polyester film can be suppressed by extrusion at a low temperature, and as a result, during stretching. Breakage tends to occur less easily.

[0036] (2) Absolute value of orientation angle of biaxially oriented polyester film

The absolute value of the orientation angle of the biaxially oriented polyester film is 25 degrees or more. The larger the absolute value of the orientation angle, the closer to the widthwise end of the film. If the surface orientation angle is less than 25 degrees, the film is near the center in the width direction of the film, so when the molten resin is in close contact with the cooling port, the end of the cold air blown by the multi-duct from the face side The effect of lowering the temperature is less. For films that have an absolute orientation angle of 25 degrees or more and are close to the edges in the width direction, the temperature of the edges of the cold air blown by the multi-duct from the face side when the molten resin is in close contact with the cooling holes is controlled. By lowering it, breakage during film formation is reduced, and unevenness in the thickness of the obtained film can be reduced.

(3) Degree of plane orientation of biaxially oriented polyester film Δ

The biaxially oriented polyester film has a degree of plane orientation of 8 0.145 to 0.

1 60. The plane orientation degree is more preferably 0.145 or more, and further preferably 0.146 or more. 〇 When it is 45 or more, the surface orientation is suitably high, the piercing strength is sufficient, and the deep drawability is superior. \¥02020/175058 12 ((171?2020/004302

The degree of plane orientation 8 is more preferably 0.157 or less, and further preferably 0.154 or less. When it is less than 0.160, the heat shrinkage rate can be kept low, and the heat stability can be further improved.

[0038] (4) Puncture strength

The puncture strength of the biaxially oriented polyester film measured by the puncture test according to 3 _ 1 707 is 0.401\1/0.01 or more.

The puncture strength is preferably 〇.501\1/ or more, more preferably 〇.601\1/ or more. Since the puncture strength is 〇.401 \1/ or more, it is possible to improve the deep drawing formability.

The puncture strength is preferably 1.01\!/ or less, more preferably 〇.901\1/ or less, further preferably 〇.851\1/ or less, and particularly preferably 〇. It is less than 801\1/. ...! If it is less than .01\1/, the heat shrinkage is suppressed and the thermal stability is superior.

In the present specification, "the puncture strength is 0. 401\1/ or more" means that the puncture strength is 0.401\\ or more in any part of the biaxially oriented polyester film. Say.

(5) Thickness and unevenness of thickness of biaxially oriented polyester film

The lower limit of the thickness of the biaxially oriented polyester film is preferably 5. It is more preferably 7, and even more preferably 90! When it is at least 50!, the strength as a film can be made sufficient.

The upper limit of the thickness of the biaxially oriented polyester film is preferably 40. It is more preferably 30, and even more preferably 20.

From the viewpoint of flexibility and resource saving, it is preferable that the thickness is thin.

[0040] The uneven thickness of the biaxially oriented polyester film is 0.7% or less. The aforementioned thickness unevenness is preferably 0.6% or less, more preferably 0.5% or less. Since the thickness unevenness is 0.7% or less, uniform molding can be performed when deep drawing is performed, and tearing of the film and pinholes are less likely to occur. The thickness variation is determined by the method described in Examples. \¥02020/175058 13 卩(: 171?2020/004302

[0041] (6) Fit Yui

The biaxially oriented polyester film is preferably a maximum diameter 0.5 3_Rei on the biaxially oriented polyester film! 〇! More fisheyes is 5 / 〇! ² below. The fisheyes, more preferably ^4/2 or less, and more preferably ^3/2 or less. If the number of fish eyes is not more than 5/2, even if the release layer is provided on one surface of the biaxially oriented polyester film, it is on the surface opposite to the release layer during winding and storage. Moreover, it is possible to suppress the transfer of unevenness onto the release layer by the fisheye. As a result, it is possible to make it difficult to deteriorate the film quality.

[0042] (7) Thermal shrinkage

The upper limit of the heat shrinkage rate of the biaxially oriented polyester film after heating at 150°° for 15 minutes in the IV!0 direction for 15 minutes is preferably 5%. It is more preferably 3.0% and even more preferably 2.5%. When it is 5% or less, it is possible to prevent the film from shrinking significantly when heat is applied in the post-processing, and the processing becomes easier.

The lower limit of the heat shrinkage rate of the biaxially oriented polyester film after heating at 150° ◯ for 15 minutes in the IV!0 direction is preferably ◯%. It is more preferably 0.8% and even more preferably 1.2%. When it is 0%% or more, the puncture strength can be increased and the bag puncture resistance can be maintained high.

The upper limit of the heat shrinkage rate of the biaxially oriented polyester film after heating for 15 minutes at 150° in the zero direction for 15 minutes is preferably 5%. It is more preferably 3.0% and even more preferably 2.5%. When it is 5% or less, it is possible to prevent the film from shrinking significantly when heat is applied in the post-processing, and the processing becomes easier.

The lower limit of the heat shrinkage rate of the biaxially oriented polyester film after heating for 15 minutes at 150° in the zero direction for 15 minutes is preferably 11%. It is more preferably 0.8% and even more preferably 1.2%. If it is more than 1% %, the puncture strength can be increased and the bag puncture resistance can be maintained high. \¥02020/175058 14 卩 (: 171?2020/004302

[0043] In addition, in the width direction of the biaxially oriented polyester film, sampling is performed at a position of 1 from each of the left and right ends toward the center, and each of them is sampled."

3_ <7 1 1 most higher value of the two density measured in accordance with the 1.40 ₉ / 〇 3 or less. More preferably 1.

And more preferably...! 389/〇 01 ³ . Wherein the density is &!. 49 / Rei_rei_1 ³ or less, the crystallization of the end portion is suppressed. As a result, it is possible to suppress excessive stress at the end portion in the stretching step when manufacturing the biaxially oriented polyester film, and to improve the film forming property.

Further, the density is preferably 1.28.

³ or more, and more preferably 1.

Or more, further preferably 1.30 ₉ / Rei_rei_1 ³ than on. 1.28

^When it is ³ or more, the crystallinity is moderately high and the mechanical strength is better.

Note that the density of the edges (from the left and right edges toward the center, 1

The density of the sampled area) is 1.4

If it is ³ or less, the density on the central side of the sampling point is 1.

The following will be met:

[0044] In addition, the biaxially oriented polyester film has a width direction of the biaxially oriented polyester film that is 1 toward the center from each of the left and right ends.

Sampling was performed at each position, and the Fourier transform infrared spectroscopy

When I asked for Minami

It is preferable that the highest value is less than 0.62.

The ratio/min (highest value of the ratio/min) is more preferably 0.61 or less, and further preferably 0.6 or less. When the ratio 8/M is less than or equal to 0.62, the crystallinity does not become too high, so the stress during stretching is suppressed and it becomes difficult to break.

The ratio/min is preferably 0.52 or more, more preferably 0.53 or more, and still more preferably 0.54 or more. 〇.52 and above \¥02020/175058 15 卩(: 171?2020/004302

, The crystallinity is not too low, and the mechanical strength is better.

In addition, if the biaxially oriented polyester film has a surface ratio of 8/norths of 0.62 or less, naturally, the ratio of 8/norms of the surfaces also satisfies 0. 622 or less.

[0045] The biaxially oriented polyester film preferably has the same composition over the entire area of the film.

[0046] A printing layer may be laminated on the biaxially oriented polyester film.

As the printing ink for forming the printing layer, water-based and solvent-based resin-containing printing inks can be preferably used. Examples of the resin used in the printing ink include acrylic resin, urethane resin, polyester resin, vinyl chloride resin, vinyl acetate copolymer resin, and mixtures thereof. Printing inks include antistatic agents, light blocking agents, UV absorbers, plasticizers, lubricants, fillers, colorants, stabilizers, lubricants, defoamers, cross-linking agents, anti-blocking agents, antioxidants, etc. Known additives may be contained.

The printing method for providing the printing layer is not particularly limited, and known printing methods such as an offset printing method, a gravure printing method and a screen printing method can be used. For drying the solvent after printing, known drying methods such as hot air drying, hot air drying, and infrared drying can be used.

Further, the biaxially oriented polyester film may be subjected to corona discharge treatment, glow discharge treatment, flame treatment, and surface roughening treatment, as long as the object of the present invention is not impaired. Known anchor coat treatment, printing, decoration and the like may be applied.

[0049] A gas barrier layer such as an inorganic thin film layer or a metal foil such as an aluminum foil may be provided on at least one surface of the biaxially oriented polyester film.

When the inorganic thin film layer is used as the gas barrier layer, the inorganic thin film layer is a thin film made of metal or inorganic oxide. The material for forming the inorganic thin film layer is not particularly limited as long as it can form a thin film, but from the viewpoint of gas barrier properties, inorganic oxides such as silicon oxide (silica), aluminum oxide (alumina), and a mixture of silicon oxide and aluminum oxide. The thing is preferably mentioned. Especially the flexibility of the thin film layer \\0 2020/175058 16 卩 (: 171? 2020 /004302

A composite oxide of silicon oxide and aluminum oxide is preferable from the viewpoint of achieving both denseness.

[0051] In this composite oxide, the mixing ratio of silicon oxide and aluminum oxide is preferably in the range of 20 to 70% by weight in terms of metal content. If the Hachijo concentration is 20% or more, the water vapor gas barrier property can be further enhanced. On the other hand, when the content is 70% or less, the inorganic thin film layer can be softened, and it is possible to prevent the film from being destroyed during the secondary processing such as printing or laminating, thereby lowering the gas barrier property. The term "silicon oxide" as used herein refers to various silicon oxides such as 3 O and 3 I 0 ₂ or a mixture thereof, and aluminum oxide refers to various aluminum oxides such as 8 O and 8 O ₂ O ₃ . Or a mixture thereof.

The thickness of the inorganic thin film layer is usually 1 to 100 nm, preferably 5 to 50 n. When the thickness of the inorganic thin film layer is 1 nm or more, more satisfactory gas barrier properties are likely to be obtained. On the other hand, when it is 100 or less, it is advantageous in terms of bending resistance and manufacturing cost.

The method for forming the inorganic thin film layer is not particularly limited, and examples thereof include physical vapor deposition methods such as vacuum vapor deposition method, sputtering method, and ion plating method (○ method).

Alternatively, a known vapor deposition method such as a chemical vapor deposition method (<30 method) may be appropriately adopted. Hereinafter, a typical method for forming an inorganic thin film layer will be described by taking a silicon oxide/aluminum oxide thin film as an example. For example, when employing the vacuum evaporation method, a mixture of 3丨〇 ₂ and eight丨₂ 〇 ₃ as evaporation raw material, or 3丨〇 ₂ and eight丨mixtures are preferably used. Particles are usually used as these vapor deposition raw materials, and it is desirable that the size of each particle is such that the pressure during vapor deposition does not change, and the preferable particle diameter is 1101 to 501. 01. For heating, resistance heating, high frequency induction heating, electron beam heating, laser heating, and other methods can be adopted. It is also possible to introduce oxygen, nitrogen, hydrogen, argon, carbon dioxide, water vapor or the like as the reaction gas, or employ reactive vapor deposition using means such as ozone addition or ion assist. In addition, the object to be vapor-deposited \¥02020/175058 17 卩(: 171?2020/004302

The film forming conditions can be arbitrarily changed, such as applying a bias to the layer film) or heating or cooling the deposition target. The vapor deposition material, reaction gas, bias of the object to be vapor-deposited, heating/cooling, etc. can be similarly changed when the sputtering method or the zero method is adopted. Further, a printing layer may be laminated on the inorganic thin film layer.

[0054] In the present embodiment, it is preferable to provide a protective layer on the gas barrier layer. The gas barrier layer made of metal oxide is not a completely dense film, but has small defects. By coating the metal oxide layer with a specific resin composition for the protective layer, which will be described later, to form the protective layer, the resin in the resin composition for the protective layer penetrates into the defective portion of the metal oxide layer. As a result, the gas barrier property is stabilized. In addition, by using a material with gas barrier properties for the protective layer itself, the gas barrier performance of the laminated film will be greatly improved.

[0055] As the protective layer, a urethane-based, polyester-based, acrylic-based, titanium-based, isocyanate-based, imine-based, polybutadiene-based resin, etc., to which a curing agent such as an epoxy-based, isocyanate-based, or melamine-based resin is added Can be mentioned. Examples of the solvent (solvent) used when forming the protective layer include aromatic solvents such as benzene and toluene; alcohol solvents such as methanol and ethanol; ketone solvents such as acetone and methyl ethyl ketone; ethyl acetate; Ester solvents such as butyl acetate; polyhydric alcohol derivatives such as ethylene glycol monomethyl ether, etc. may be mentioned.

[0056] In the urethane resin, since the polar group of the urethane bond interacts with the inorganic thin film layer and also has flexibility due to the presence of the amorphous portion, the inorganic thin film layer is also subjected to bending load. It is preferable because damage to the can be suppressed. The acid value of urethane resin is 10 to 6

And more preferably within the range of

When the acid value of the fat is within the above range, the liquid stability is improved when it is made into an aqueous dispersion, and the protective layer is highly polar. \¥02020/175058 18 卩 (: 171?2020/004302

Since it can be uniformly deposited on the inorganic thin film, the coat appearance becomes good.

[0057] The urethane resin preferably has a glass transition temperature (Ding 9) is 8 0 ^° ● As, more preferably 9 0 ^° ● As. By setting Ding 9 to 80 ^° or more, the swelling of the protective layer due to the molecular motion in the wet heat treatment process (temperature increase-heat retention-temperature decrease) can be reduced.

As the urethane resin, it is more preferable to use a urethane resin containing an aromatic or araliphatic diisocyanate component as a main constituent from the viewpoint of improving gas barrier properties.

Among them, it is particularly preferable to contain the metaxylylene diisocyanate component. By using the above resin, the cohesive force of the urethane bond can be further increased by the stacking effect of the aromatic rings, and as a result, good gas barrier properties can be obtained.

In the present embodiment, the proportion of the aromatic or araliphatic diisocyanate in the urethane resin is not less than 50 mol% in 100 mol% of the polyisocyanate component (50 to 100 mol%). ) It is preferable to set it as the range of. The proportion of the total amount of the aromatic or aromatic aliphatic diisocyanate is preferably 60 to 100 mol%, more preferably 70 to 100 mol%, and further preferably 80 to 100 mol%. is there. As such a resin, “Yukerack (registered trademark) \ZV P B” series commercially available from Mitsui Chemicals, Inc. can be preferably used. When the proportion of the total amount of aromatic or araliphatic diisocyanate is 50 mol% or more, better gas barrier properties can be obtained.

From the viewpoint of improving the affinity with the inorganic thin film layer, the urethane resin preferably has a carboxylic acid group (carboxyl group). In order to introduce the carboxylic acid (salt) group into the urethane resin, for example, a polyol component having a carboxylic acid group such as dimethylolpropionic acid or dimethylolbutanoic acid may be introduced as a copolymerization component. .. Further, a urethane resin of an aqueous dispersion can be obtained by synthesizing a carboxylic acid group-containing urethane resin and then neutralizing it with a salt forming agent. Specific examples of the salt forming agent include ammonia and trimethyl alcohol. \\0 2020/175058 19 卩 (: 171-1? 2020 /004302

Min, triethylamine, triisopropylamine, tree 11-propylamine, tree 1·!-butylamine and other trialkylamines, 1\1-methylmorpholine, 1\]-ethylmorpholine and other 1\1-alkylmorpholines, 1\1-dimethyl ethanolamine, 1\1-diethyl ethanolamine and other 1\1-dialkylalkanolamines. These may be used alone or in combination of two or more.

[0061] The biaxially oriented polyester film may be laminated with a layer made of another material. As a method thereof, the biaxially oriented polyester film may be attached after being produced or may be attached during film formation.

[0062] The biaxially oriented polyester film is used as a packaging material, for example, by providing an inorganic vapor deposition layer on the biaxially oriented polyester film, and further forming a heat-sealable resin layer (also referred to as a sealant layer) called a sealant. be able to. The heat-sealable resin layer is usually formed by an extrusion laminating method or a dry laminating method. The thermoplastic polymer forming the heat-sealable resin layer may be any one as long as it can sufficiently exhibit sealant adhesiveness,

!! _ !_ 0 Polyethylene resin such as Tomomi, polypropylene resin. Ethylene-vinyl acetate copolymer, ethylene-olefin-random copolymer, ionomer resin and the like can be used.

[0063] The sealant layer may be a monolayer film or a multilayer film, and may be selected according to the required function. For example, from the viewpoint of imparting moisture resistance, a multilayer film in which a resin such as an ethylene-cyclic olefin copolymer or polymethylpentene is interposed can be used. Further, the sealant layer may be blended with various additives such as a flame retardant, a slip agent, an anti-blocking agent, an antioxidant, a light stabilizer and a tackifier.

The thickness of the sealant layer is preferably from 10 to 1001 and more preferably from 20 to 600!.

[0064] The biaxially oriented polyester film can be used in the field of packaging foods, pharmaceuticals, industrial products and the like. In particular, the biaxially oriented polyester film, \¥02020/175058 20 units (: 171-12020/004302

It can be used as a base film (base layer) of a packaging laminate. In the layer structure of the packaging laminate, when the layer boundary is represented by /, for example, base material layer/gas barrier layer/protective layer, base material layer/gas barrier layer/protective layer/adhesive layer/sea run layer, Base material layer/gas barrier layer/protective layer/adhesive layer/resin layer/adhesive layer/sealant layer, base material layer/adhesive layer/resin layer/gas barrier layer/protective layer/adhesive layer/sealant layer, base Material layer/gas barrier layer/protective layer/printing layer/adhesive layer/sealant layer, base material layer/printing layer/gas barrier layer/protective layer/adhesive layer/sealant layer, base material layer/gas barrier layer/protective layer/ Adhesive layer/resin layer/printing layer/adhesive layer/sealant layer, base material layer/adhesive layer/resin layer/printing layer/gas barrier layer/protective layer/adhesive layer/sealant layer, base material layer/printing layer / Gas barrier layer / Protective layer / Adhesive layer / Resin layer / Adhesive layer / Sealant layer, Substrate layer / Printing layer / Adhesive layer / Resin layer / Gas barrier layer / Protective layer / Adhesive layer / Sealant layer, Substrate Layer/adhesive layer/resin layer/gas barrier layer/protective layer/printing layer/adhesive layer/sealant layer, etc.

[0065] The laminate using the biaxially oriented polyester film can be suitably used for applications such as packaging products, various label materials, lid materials, sheet molded products, and laminated tubes. In particular, it is used for packaging bags (eg pillow bags, standing pouches and bouches such as 4-way pouches). The thickness of the laminate can be appropriately determined according to its application. For example, it is used in the form of a film or sheet having a thickness of about 5 to 500, preferably about 10 to 300.

[0066] [Method for producing biaxially oriented polyester film]

As a suitable method for obtaining the biaxially oriented polyester film, the die method is preferable from the viewpoint of thickness accuracy in the width direction. In the inflation method, the stretching ratio is difficult to increase due to the manufacturing method, and thickness defects in the width direction may occur.

Further, as a suitable method for obtaining the biaxially oriented polyester film, when a molten polyester resin composition is cast in a cooling port, a conventional method is \¥02020/175058 21 卩 (: 171-1? 2020 /004302

A method has been proposed in which a uniform unstretched sheet is obtained by suppressing crystallization by forming a resin having the same composition into eight layers or more by using a tick mixer, etc. In addition, from the viewpoint of facility simplicity and maintainability, it is preferable to form a laminate of 7 layers or less at the time of melt extrusion by the casting method described below for obtaining a homogeneous unstretched sheet. More preferably, the number of layers is 3 or less. In terms of equipment maintenance, single layer is the most preferable. When it is desired to improve the surface properties of the film, a layer structure of 2 types 2 layers, 2 types 3 layers, or 3 types 3 layers is preferable.

Since the Ming resin has a high crystallization rate, the lower limit of the intrinsic viscosity of the unstretched sheet obtained is preferably 0.7.

More preferably 〇. 75丨/ _9, more preferably from 〇. 80丨/ _9, particularly preferably from 0.9 0_Rei_1丨/ 9. ◯. When it is 70 70 ¢1 /9 or more, crystallization during casting is suppressed and the yield stress of the unstretched sheet becomes low, and as a result, breakage tends not to occur during stretching.

The upper limit of the intrinsic viscosity of the obtained unstretched sheet is preferably 1.2 丨/ ₉ , more preferably 1.1 丨/ ₉ . ...! .2 丨/ ₉ or less

The stress during stretching does not become too high, and the film-forming property becomes better.

The lower limit of the die temperature is preferably 240°, more preferably 245°, and particularly preferably 250°. If it is 240° or more, the discharge is more stable and the thickness can be made more uniform.

Further, when the temperature is 240° or more, it is possible to prevent the resin remaining in the resin melt extrusion step from becoming an unmelted substance and being mixed into the film, thereby impairing the quality of the film. The upper limit of the resin melting temperature is preferably 280 ^° , more preferably 275°, and most preferably 270°. When the temperature is 280 ^° C or less, the decomposition of the resin can be suppressed, the film can be prevented from becoming brittle, and the deterioration of the film quality due to a thermally deteriorated product can be prevented. Further, the progress of crystallization during casting can be suppressed, and the film forming property can be further improved. \¥02020/175058 22 卩 (: 171?2020/004302

The upper limit of the die temperature is preferably from 2 8 0 ^° 〇, more preferably 2 7 5 ^° 〇 or less, more preferably 2 7 0 ° ◦ below. When it is 280°° or less, it is possible to prevent the thickness from becoming uneven. Further, it is possible to prevent the appearance of the resin from being deteriorated due to stains on the die lip or the like. Further, it is possible to prevent the intrinsic viscosity of the obtained film from decreasing. Further, the progress of crystallization at the time of casting is suppressed, and the film forming property becomes better.

[0068] The lower limit of the rotation speed of the screw in the resin melt extrusion step is preferably 7

0 ", more preferably 8 0 ", and particularly preferably 90 "01. 7 0" When 01 or more, the discharge is more stable and the thickness is more uniform. Is more sufficient, and appearance defects can be further suppressed.

The upper limit of the number of rotations of the screw in the resin melt extrusion step is preferably 150 ", more preferably 1300", and particularly preferably 1100". It is possible to suppress the decomposition of the molten resin due to shearing heat generation, and to suppress the decrease in the inherent viscosity of the film to be obtained, and to suppress the progress of crystallization during casting and to improve the film-forming property. It will be better.

[0069] The upper limit of the cooling port temperature is preferably 40°, and more preferably 10° or less. If it is 40 ^° C. or less, the crystallinity of the molten polyester resin composition upon cooling and solidification does not become too high, and the stretching becomes easier.

The lower limit of the cooling port temperature is preferably 0°. When it is 0° or more, the effect of suppressing crystallization when the molten polyester resin composition is cooled and solidified can be sufficiently exhibited. When the temperature of the cooling port is within the above range, it is preferable to reduce the humidity of the environment near the cooling port to prevent dew condensation.

[0070] When the molten polyester resin composition is cast on the surface of the cooling hole, the temperature of the surface of the cooling hole rises because the high temperature resin comes into contact with the surface. Normally, a chill roll is cooled by flowing cooling water through a pipe inside, but to ensure a sufficient amount of cooling water, devise a layout of the pipe, and maintain it so that sludge does not adhere to the pipe. \¥02020/175058 23 卩(: 171-12020/004302

It is necessary to reduce the temperature difference in the width direction of the chill roll surface, for example.

At this time, the thickness of the unstretched sheet is preferably in the range of 15 to 2500. It is more preferably 500 or less, and further preferably 300 or less.

[0071] The time from when the molten polyester resin composition is discharged from the die until it touches the cooling port (hereinafter, also referred to as contact time) is preferably in the range of 0.1 to 1.0 seconds, and More preferably within the range of .2 to .05 seconds. The contact time is a value obtained by (air gap)/(ejection speed). Here, the air gap is the distance between the discharge port 12 and the surface of the cooling port 20.

After casting the resin composition for producing the biaxially oriented polyester film in the cooling port, from the viewpoint of reducing the crystallinity of the unstretched sheet and enhancing the stretchability (film forming property). After the step), it is preferable to rapidly cool the bottom surface of the unstretched sheet on the cooling port.

Further, in order to further enhance the stretchability, it is preferable that the end portion of the non-stretched sheet's face is quenched more strongly than the center portion. Specifically, when the total width of the unstretched sheet is 100%, when the temperature of the air blown to the center is X, and the temperature of the air blown to both ends is lower, X is 15 ^° It is below, and it is preferable that the temperature is lower than the temperature X.

In addition, the thickness of the end portion of the unstretched sheet is often thicker than that of the central portion. Then, by quenching the edge portion more strongly than the central portion, crystallization can be suppressed to the central portion and the film forming property can be improved. The method of quenching is not particularly limited, but a method of blowing cooling air through a multi-duct is preferable from the viewpoint of facility simplicity and maintainability.

The X is more preferably 5° or less. The X is preferably _ 5 ° 〇 or more. When the above X is not less than 150°, a sufficient effect of suppressing crystallization of the face of the unstretched sheet can be obtained.

It is preferable that the edge portion is an area at least within 10% from the edge. \¥02020/175058 24 卩 (: 171?2020/004302

.. The end portion is more preferably an area within 15% from the edge, more preferably an area within 20% from the edge, and particularly preferably an area within 25% from the edge. Is.

[0073] The temperature is preferably 10° or less, and more preferably 5° or less. When the grain size is 10 or less, the crystallinity of the end face of the unstretched sheet does not become too high, and the film formability becomes better. It is preferable that the temperature is _ 5 ^° 〇 or more. When the temperature is not less than 15°, a sufficient effect of suppressing the crystallization of the face of the unstretched sheet can be obtained.

[0074] FIG. 1 is a schematic front view for explaining a method of blowing cooling air from a multi-duct onto the mound surface of an unstretched sheet on a cooling port, and FIG. 2 is a side view thereof.

As shown in FIGS. 1 and 2, the die 10 is arranged so that the discharge port 12 faces the surface of the cooling port 20. The distance (shortest distance) between the discharge port 12 and the surface of the cooling port 20 is not particularly limited, but is generally about 20 to 100.

Further, a multi-duct 30 is arranged on the outer peripheral surface of the cooling port 20.

In the side view (Fig. 2), the position of the multi-duct 30 is the rotation of the cooling port 20 when the position of the die 10 is 0 ^° with respect to the center of the cooling port 20. with respect to the direction (Figure 2, right rotation direction), preferably Rukoto been installed in a range of 〇_～ 4 5 °, 1 0~ 3 5 ° and more preferred arbitrarily installed in the range of. When the multi-duct 30 is arranged within the above range, it is possible to cool the mound surface of the unstretched sheet 40 cast on the cooling port 20 immediately after casting.

Further, the time from the time when the resin composition for producing the biaxially oriented polyester film is cast into the cooling port (the time when it is touched) to the time when the air is blown to the relevant part is within 2.0 seconds. The time is preferably within 1.0 second, more preferably within 0.5 second. Resin for manufacturing biaxially oriented polyester film \¥02020/175058 25 卩 (: 171?2020/004302

The time from when the composition is cast into the cooling port (when touched) to when the air is blown to the relevant part (time until the relevant part moves directly under the multi-duct 30) is 2 When the time is within 0.0 seconds, the mound surface of the unstretched sheet 40 can be cooled immediately after casting.

It is preferable that the lateral width (length in the left-right direction in FIG. 1) of the multi-duct 30 be equal to or larger than the width of the unstretched sheet 40 to be cast. By setting the width of the multi-duct 30 to be equal to or larger than the width of the unstretched sheet 40 to be cast, it becomes easy to obtain a sufficient crystallization suppressing effect up to the end of the mound face of the unstretched sheet 40.

[0076] When the total width of the unstretched sheet is 100%, the multi-duct 30 is blown to the temperature of the wind blown to the central part and the 20% left end and 20% right end. It is preferable that the temperature is different from that of the temperature. Specifically, there is a method in which the outlet of the multi-duct 30 is divided into a plurality of parts by a partition plate or the like, and air of different temperatures is blown out from each outlet. The mode of dividing the air outlets is not particularly limited, and the air outlets may be evenly divided or may have different widths for the respective air outlets.

[0077] Fig. 3 shows an example of the multi-duct. Figure 3 is a bottom view (viewed from the side of the cooling port) showing an example of a multi-duct. In the multi-duct 30 according to the present embodiment, the width is set so as to be the same width as the unstretched sheet 40 (Fig. 2), and as shown in Fig. 3, the outlet of the multi-duct 30 is partitioned. It is divided into 5 by the plate 3 2. Specifically, the outlets of the multi-duct 30 are divided into outlets 3 1 — 1 to outlets 3 1 — 5 in order from the left side to the right side in FIG.

[0078] The vertical width of the multi-duct 30 (the length in the vertical direction in Fig. 1) is preferably not less than 30.01 and not more than 800!

The following is more preferable.

The speed at which the unstretched sheet 40 moves on the cooling port 20 is preferably 20 |^/min to 100001/min, and 4001/min to 8001/ In minutes \¥02020/175058 26 卩 (: 171?2020/004302

More preferably.

By setting the vertical width of the multi-duct 30 within the above numerical range and the speed of the unstretched sheet 40 within the above numerical range, a suitable amount of cooling air can be blown to the bottom surface of the unstretched sheet 40. it can.

[0079] The upper limit of the height of the multi-duct 30 from the cooling port 20 is 200 or less, and more preferably 100.

It is the following. When it is 200 or less, the cooling efficiency is improved, and the effect of suppressing crystallization of the end portion of the unstretched sheet 40 is sufficiently obtained. The lower limit of the height of the multi-duct 30 from the cooling port 20 is not particularly limited, but is preferably within a range where it does not come into contact with the unstretched sheet 40.

[0080] The upper limit of the wind velocity of the cooling air from the multi-duct 30 is preferably 200 /min, more preferably 18001 /min or less. When it is at most 200/minute, it is possible to prevent the ground point when casting the molten sheet-forming resin composition from being shaken by cooling air.

The lower limit of the cooling air velocity is preferably 50/min. When it is 50/min or more, the effect of suppressing crystallization of the end portion of the unstretched sheet 40 can be sufficiently obtained.

Among the above, the method for producing the biaxially oriented polyester film according to the present embodiment,

A step 8 of forming a non-stretched sheet by casting a resin composition for producing a biaxially oriented polyester film in a cooling port.

And a step for blowing air to the unstretched sheet on the cooling port, wherein the step width is, when the unstretched sheet total width is 100%, the temperature of the wind blown to the center is X, When the temperature sprayed on both ends is assumed to be low, X is 15 ^° or less, and the temperature is lower than X, and the end is at least 1 from the edge. It is preferable to include the area within 0%

Next, the stretching method will be described. The stretching method may be simultaneous biaxial stretching or sequential biaxial stretching, and is not particularly limited.

[0083] The lower limit of the stretching temperature in the longitudinal direction (hereinafter, also referred to as IV! 0 direction) is preferably 5 5 \¥02020/175058 27 卩 (: 171?2020/004302

Is 0°, more preferably 60°. If it is 55° or more, fracture can be further suppressed. Further, it is possible to prevent the orientation in the vertical direction from becoming too strong, and to suppress an increase in the thermal shrinkage in the IV! The upper limit of the elongation temperature in the IV! 0 direction is preferably 100 ^° 〇, more preferably 95 ^° 〇.

If it is 100 ^° or less, the orientation can be sufficiently provided and the mechanical properties can be further enhanced.

[0084] The lower limit of the stretching ratio in the IV! 0 direction is preferably 2.5 times, and particularly preferably.

2.7 times. If the ratio is 2.5 times or more, the orientation can be sufficiently provided and the mechanical properties can be further enhanced. Further, when it is 2.5 times or more, uneven thickness can be suppressed and slack of the film roll can be prevented.

The upper limit of the stretching ratio in the IV! 0 direction is preferably 3.8 times, and more preferably

It is 3.6 times, particularly preferably 3.4 times. When it is not more than 8 times, the effect of improving mechanical strength and thickness unevenness can be sufficiently obtained.

[0085] The lower limit of the stretching temperature in the width direction (hereinafter, also referred to as the 0 direction) is preferably 55° 〇, more preferably 60 ^° 〇. If it is 55 ^° or more, it is possible to make it difficult for fracture to occur. It also prevents the lateral orientation from becoming too strong,

It is possible to prevent the heat shrinkage in the 70 direction from increasing.

The upper limit of the stretching temperature Ding 0 direction is preferably 1 00 ° 〇, more preferably 95 ^° 〇. When it is 100 ^° or less, the orientation can be sufficiently provided, and the mechanical properties can be further enhanced.

[0086] The lower limit of the draw ratio in the 0-direction is preferably 3.5 times, and more preferably

It is 3.6 times, particularly preferably 3.7 times. If it is 3.5 times or more, the degree of orientation in the width direction can be increased and the mechanical strength can be increased. The upper limit of the draw ratio in the 0-direction is preferably 5.0 times, and more preferably

It is 4.6 times, particularly preferably 4.3 times. When it is 5.0 times or less, the effect of improving mechanical strength and thickness unevenness can be sufficiently obtained.

[0087] The lower limit of the heat setting temperature is preferably 1 70 ° 〇, more preferably 1 80 ° 〇. \¥02020/175058 28 卩 (: 171?2020/004302

Is. When it is 1 70° or more, the heat shrinkage rate can be further reduced. The upper limit of the heat setting temperature is preferably 220°○. When it is 220° or less, it is possible to prevent the film from melting and the puncture strength from decreasing.

The lower limit of the relaxation rate is preferably 0.5%. ○ When it is more than 0.5%, the heat shrinkage in the direction of the neck can be kept low.

The upper limit of the relaxation rate is preferably 10%. When it is 10% or less, slack and the like can be prevented from occurring, and the flatness can be improved.

[0089] The lower limit of the temperature for the relaxation process is preferably 130°°, and more preferably 150°°. When it is at least 30°°, the film will be sufficiently shrunk when relaxing and the heat shrinkage reduction effect can be sufficiently obtained.

The upper limit of the relaxation temperature is preferably 190 ^° 〇, more preferably 170° 〇. When it is 1 90° or less, it is possible to prevent the flatness of the film from being deteriorated due to wrinkles and the like.

The method for manufacturing the biaxially oriented polyester film according to this embodiment has been described above.

Example

[0091] Next, the present invention will be described in more detail by way of examples, but the present invention is not limited to the following examples. The film was evaluated by the following measuring method.

[0092] [Intrinsic viscosity of film]

From the films produced in the Examples and Comparative Examples, the center position in the film width direction and the position of 100011 from the left and right ends toward the center are centered.

Each sample was cut out.

The intrinsic viscosity of the sample was measured using an automatic viscosity measuring device "33_600_1_1" manufactured by Shiyama Scientific Instruments Co., Ltd. As the solvent liquid, a mixed liquid of —chlorophenol/1,1,2,2-tetrachloroethane=6/4 (mass ratio) was used. \¥02020/175058 29 卩 (: 171?2020/004302

[0093] [Thickness and thickness unevenness of film]

6 from the left and right edges of the film width direction toward the center

The length of the film in the longitudinal direction and the width direction centered on the position (13% from the end of the mill roll relative to the total width) is 10 1 Width 40

Was sampled into a long strip and was measured at a speed of 5 (0!/min) using a continuous contact thickness gauge manufactured by Micron Measuring Instruments Co., Ltd.

The thickness variation (%) in the longitudinal direction and the thickness variation (%) in the width direction are calculated by the following formula 1 from the standard deviation of the measured thickness and the average value of the thickness, and the thickness variation (%) and the width in the longitudinal direction are calculated. The average value of the thickness unevenness (%) in the direction was defined as the thickness unevenness (%).

Thickness variation = {(standard deviation of thickness) / (average value of thickness)) X 100 (%)

-Formula 1

[0094] [Orientation angle of film]

6 from the left and right edges of the film width direction toward the center

Film (13% to the entire width from the end of the mill roll)

Using an IV! 〇811 60 04 type molecular orientation meter manufactured by Oji Scientific Co., Ltd., the orientation angle of the principal axis of the molecular chain was determined with reference to the axis in the width direction of the film. At this time, the counterclockwise inclination with respect to the film width direction was set to "10", and the clockwise rotation was set to "1".

[0095] [The degree of plane orientation of the film Δ]

From the films produced in Examples and Comparative Examples, the 680

5 centered at the position of (13% from the end of the mill roll to the entire width)

Each sample was cut out.

Samples” 丨 3 <7 1 42- 1 996 According to the eight method, the refractive index in the longitudinal direction of the film (father) and the widthwise direction ( N 7), Refractive index in thickness direction

Is measured by the following formula

Was calculated.

Degree of plane orientation (△?) = [(Fujyu 1\1 ₇ )/2] -N 2 \¥02020/175058 30 卩 (: 171?2020/004302

[0096] [Strength of film piercing]

From the films produced in Examples and Comparative Examples, the film width direction was adjusted from the left and right edges toward the center, respectively.

Vertical position centered on the position (position 13 from the end of the mill roll to the entire width)

Each of the samples was cut out.

The puncture strength of the polyester film was calculated by converting the value measured by the test method described in "1 3-7 1 7 0 7" into 1 by the following formula.

Puncture strength (1\1 / ^0 = measured puncture strength / film thickness

[0097] [The heat shrinkage rate of the film after heating at 150°° for 15 minutes]

The heat shrinkage rate of the polyester film was measured by the dimensional change test method described in "3-0-2 318" except that the test temperature was 150° and the heating time was 15 minutes. Samples were prepared from the films prepared in Examples and Comparative Examples from the left and right edges in the width direction of the film toward the central portion, respectively.

Position (13% of the total width from the end of the mill roll)

Each sample was cut out.

[0098] [Fourier transform infrared spectroscopy (total reflection method)]

From the films produced in Examples and Comparative Examples, sample samples of 5 0! 511 111 in width were cut out from the left and right edges in the width direction of the film, centered at the position of 100! It was

Using, the medium crystal was brought into close contact with the film surface layer as diamond, and the spectral intensity was measured by the total reflection method while light was incident parallel to the IV!0 direction. The resolution of the spectrometer 4_Rei - ^1, spectrum accumulation number was measured as 6 4 times. The spectral intensity is the absorbance at each wave number. It was calculated by the following formula. The measurement was performed on the Mitsumi surface. Absorbance ratio (8/M) = Absorbance 8

Peak spectrum intensity) / Absorbance value (1 4 1 0 ± 1 0 0 0)

Intensity of the peak of) [0099] [Film density]

From the films prepared in Examples and Comparative Examples, \¥02020/175058 31 卩 (: 171?2020/004302

From the center toward the center, a sample with a length of 5! and a width of 5 111 111 centered at the position of 1 0 111!

The density of the sample was measured by the 0 method (density gradient method) of “3 <7 1 1 2 ”. The measurement conditions were as follows. Table 1 shows the highest measured value of the left and right samples.

Gradient liquid: calcium nitrate tetrahydrate

Temperature in gradient tube: 300

Sample size: 5 01 111 X 5 111 111

Soaking time: 16 hours

[0100] [Evaluation of film formability]

When the films of Examples and Comparative Examples were produced, the case where continuous film formation was possible without break for 30 minutes or more was evaluated as ◯, and the case where breakage occurred at least once within 30 minutes was evaluated as X.

[0101] [Evaluation of fish eyes]

From the films produced in Examples and Comparative Examples, centered at the position of 6800 1 01 from the left and right edges in the film width direction toward the center (13% of the width from the edge of the mill roll). To the width direction

Longitudinally

Each of the samples was cut out and the number of fish eyes was counted under deflection using a magnifying glass (I--10) made by Tokai Sangyo Co., Ltd. (observation magnification: 10 times). The same operation is repeated 10 times, and the average value of the counts of 10 times is calculated by the following formula.

It was calculated as the number of fish eyes per one.

[Fish eyes (pieces/〇! ² )] = [average count of fish eyes (pieces)] / [measuring range (6 3 0^ ² )]

[0102] [Evaluation of transfer to release layer]

The following release layer-forming coating liquid was applied to one surface of the base material so that the coating amount after drying was 0.05/ ² . Then, the coated film was heated with hot air at 1300 ^° for 5 seconds for 10 seconds, hot air at 1700° for 20 seconds and 10 seconds, \¥02020/175058 32 卩 (: 171?2020/004302

1 It was dried for 10 seconds with hot air of 30°○, 200○!/sec. As described above, the release layer was laminated on one surface of the base material. After that, it was rolled up as a mouth.

The number of transfer marks was visually counted using a bromolite in the range of 210.101 in the width direction and 300 in the longitudinal direction on the release layer side of the obtained film. Repeat 1 〇 times similar operation, by the following equation the average value of 1 0 times the number of counts, was calculated as the number of transfer marks of or 1 ² Ah, was determined by the number. The point to be counted was on the core side of the center of the mouth in the longitudinal direction.

[Transfer marks (pieces/

] = [Average transfer mark count (pieces)] / [Measurement range (63 〇! ² )]

Judgment 3 pieces / _{0! 2} or less: ○, 4 pieces / _{0! 2} or more: X

[0103] [Preparation of release layer forming coating liquid]

The components were mixed in the composition shown below to obtain a release layer-forming coating liquid. Toluene = 56.05 mass%

Isopropanol: 1 4.01 mass%

Acid-modified polyolefin resin solution = 29.4% by mass

Hexamethylene diisocyanate-based blocked isocyanate compound: 0.5 4% by mass

(Asahi Kasei Chemicals Duranate (registered trademark) 1\/1 _ [<60 solids concentration 60% 1\100% = 6.5%)

The method for producing the acid-modified polyolefin resin solution will be described below. 80 ^° 〇 the pressurized heated and oxidized wax in toluene 989 (manufactured by Nippon Rosha made 3-9 1 25 acid value 32 9 <〇! ^~ 1/9) 2 ₉ were charged, and stirred for 30 minutes to dissolve. After the dissolved acid-modified polyolefin resin solution was cooled to 25 ^° 〇, it was filtered through a 300 mesh stainless steel filter (wire diameter 〇0.035 〇 101, plain weave) to obtain an acid-modified polyolefin resin solution. ..

[0104] [Evaluation of deep drawability]

From the films produced in Examples and Comparative Examples, 680 positions from the left and right ends in the width direction of the film toward the central part (from the end of the mill roll to the full width) \¥02020/175058 33 卩 (: 171-12020/004302

Then, a sample was cut out in the longitudinal direction (longitudinal direction) 1500 1 and the lateral direction (width direction) 100, centered at 13% position. This sample was set in the mold shown in Figs. 4 and 5, and pressed from above to perform draw forming. FIG. 4 is a cross-sectional view of the mold used for evaluation of deep drawing formability, and FIG. 5 is a plan view of the mold shown in FIG. In particular,

A film (films of Examples and Comparative Examples) was placed on the mold 50 of size 3, and the film was pressed by the punch 54 having a shape corresponding to the mold 50 while the film was suppressed by the film presser 52. The squeezing speed was 60101/3.

N = 10 was performed for each drawing depth, and the maximum drawing depth when no film tearing or pinholes occurred at N = 10 was taken as the deep drawing molding value of the sample.

[0105] [Example 1]

— Using a screw extruder, Mingko resin (terephthalic acid//butanediol = 100/100/100 (mol %) intrinsic viscosity 1.28 I/ ₉ ) and Mending resin (terephthalic acid//ethylene) A resin composition for the production of biaxially oriented polyester film containing an intrinsic viscosity of 0.62 1/9 (containing silica particles) consisting of glycol = 100//100 (mol %) was melted at 290°○. After that, the unstretched sheet was obtained by casting from a 250° 〇 die and making a cold air blow from the multi-duct to the face while adhering to the 10 ^° cooling port by the electrostatic contact method. The width of the obtained non-stretched sheet was 1,600. The multi-duct has a structure as shown in Fig. 1, and cool air of 10° 〇 is blown from the outlets 3 1-1 and 3 1 -5 (hereinafter also referred to as outlets 1 and 5), and the outlet 3 1 Cold wind of 15 ° was blown from -2 to 3 1-4 (hereinafter also referred to as blow-out ports 2 to 4). In this embodiment, the widths of the outlets 1 and 5 are respectively

Outlet

The width of 2 to 4 is

did.

Of the unstretched sheet, 32 〇 toward the center from the left and right edges

The wind from the outlet 1 or 5 was blown up to the position of, and the wind from the outlets 2 to 4 was blown to the central portion side than that. \¥02020/175058 34 卩(: 171-12020/004302

At this time, the vertical width of the multi-duct was 5, and the moving speed of the unstretched sheet was 60/min.

In addition, the time from the time when the resin composition for producing the biaxially oriented polyester film was cast into the cooling port (the time when it was touched) to the time when the air was blown to the part was 0.5 seconds. ..

The content of the silica particles in the resin composition for producing the biaxially oriented polyester film is the silica concentration when the resin composition for producing the biaxially oriented polyester film is the whole (100% by mass). .16% by mass.

[0106] Next, the obtained unstretched sheet was machined in the longitudinal direction at a temperature of 70 °C.

Direction)

Stretching at 3.3 times, then passing through a tenter at 80 ° 〇 in the width direction (chome direction) at 4.0 times, heat setting treatment ^at 200 ^° 〇 for 3 seconds and 1 second. A relaxation treatment of 9% was carried out to obtain a biaxially oriented polyester film having a thickness of 15. Table 1 shows the resin composition in the resin composition for producing the biaxially oriented polyester film and the film forming conditions. In addition, Table 1 shows the physical properties and evaluation results of the obtained film.

[0107] [Examples 2 to 6]

A film was formed in the same manner as in Example 1 except that the resin composition, the die temperature, and the heat treatment temperature were changed as described in Table 1, to obtain a biaxially oriented polyester film having a thickness of 15. Table 1 shows the physical properties and evaluation results of the obtained film.

[0108] [Comparative Example 1]

— Using a screw extruder, mix 80% by weight of Mending resin and 20% by weight of Mending resin, and use silica particles with an average particle size of 2.4 as inert particles in the mixed resin. was melted at 9 0 0 become as those formulated 2 9 〇 ^° 〇 in contrast, the introduction of melt line static mixers one 1 0 element. As a result, the polyester resin melt was divided and laminated to obtain a multilayer melt of the same raw material and having a number of laminated layers of 10 2 4 and then cast from a die with a die temperature of 250 ^° A biaxially oriented film was obtained in the same manner as in Example 2 except that an unstretched sheet was obtained while being adhered to the cooling port of °° by the electrostatic adhesion method. The film was formed into a biaxially oriented polyester film having a thickness of 15. Table 1 shows the physical properties and evaluation results of the obtained film.

[Comparative Example 2, Comparative Example 3]

A film was formed in the same manner as in Comparative Example 1 except that the number of layers was changed as shown in Table 1 to obtain a biaxially oriented polyester film having a thickness of 15. The physical properties and evaluation results of the obtained film are shown in Table 1.

[01 10] [Comparative Examples 4 and 6]

In Example 2, the die temperature was changed to 270° 〇 (Comparative Example 4) and 285° 〇 (Comparative Example 6), and when the molten resin was brought into close contact with the cooling port, the multi-duct was applied from the face side. A biaxially oriented film was formed in the same manner as in Example 2 without blowing cold air to obtain a biaxially oriented polyester film having a thickness of 15. The results are shown in Table 1 . In Comparative Example 6, the film was ruptured in the stretching process in the width direction, and a sample for evaluating the film could not be obtained.

[01 1 1] [Comparative example 5]

In Example 2, a film was formed in the same manner as in Example 2 except that the casting conditions were changed as shown in Table 1 to obtain a biaxially oriented polyester film having a thickness of 15. Table 1 shows the physical properties and evaluation results of the obtained film.

[01 12] [Comparative Example 7]

A film was formed in the same manner as in Example 2 except that the resin composition was changed as shown in Table 1 to obtain a biaxially oriented polyester film having a thickness of 15. Table 1 shows the physical properties and evaluation results of the obtained film.

[01 13] [¾ji

\¥02020/175058 37 卩(: 171-12020/004302

[0114] As shown in Table 1, the biaxially stretched polyester films (Examples 1 to 5) obtained according to the present invention have few thickness irregularities and fish eyes and have good deep drawing moldability. And a biaxially oriented polyester film having excellent quality was obtained.

However, in Comparative Examples 1 to 3, since the melt line was introduced into the static mixer and multilayered to 64 layers or more, the number of fish eyes was larger than that of the Examples, and it was not suitable for applications requiring high quality. It was

In Comparative Example 4, when the molten resin was brought into close contact with the cooling port and no cold air was blown through the multi-duct from the face side, there were many breaks during film formation. In addition, the obtained film had large thickness unevenness and was inferior in deep drawing formability. In Comparative Example 5, the temperature of the cold air blown by the multi-duct from the face side when the molten resin was brought into close contact with the cooling port was higher than that in the Example, so that there were many breaks during film formation. Further, the obtained film had large thickness unevenness and was inferior in deep drawing moldability.

In Comparative Example 6, since the temperature at which the resin was melted and extruded was high, the intrinsic viscosity of the film was low, and the film broke during the stretching process in the width direction, and a sample for evaluating the film could not be obtained.

Further, in Comparative Example 7, the piercing strength was poor because the ratio of Mitsuko was low. Industrial availability

[0115] The biaxially oriented polyester film of the present invention has a good film quality that can be used for industrial applications, and since it uses Ming as the main component, it is suitable as a release film accompanying deep drawing. is there.

Explanation of symbols

[01 16] 1 0 Dice

1 2 Discharge port

20 Cooling port

3 0 multi duct \¥02020/175058 38

3 1 (3 1-1, 3 1 -2, 3 1 -3, 3 1 -4, 3 1 -5) Balloon

32 dividers

40 unstretched sheet

50 mold

60 films

70 film control

80 punch

Claims

\¥02020/175058 39 卩(: 17 2020/004302 Claims [Claim 1] Polyester terephthalate resin (8) Includes a polyester resin composition containing 60 to 100% by mass, and the number of laminated layers is 7 or less. The biaxially oriented polyester film is characterized by satisfying the following requirements (1) to (5).

(1) The intrinsic viscosity of the biaxially oriented polyester film is at least 0.7 7 /9.

(3) The degree of plane orientation Δ of the biaxially oriented polyester film is ◯ 0.145 to 0 1 60.

(4)” 1 The puncture strength of the biaxially oriented polyester film measured by the puncture test according to 3-71 707 is 0.401 \1/ or more.

[Claim 2] The polyester resin composition is a polybutylene terephthalate resin.

The biaxially oriented polyester film according to claim 1, containing a polyester resin (Mitsumi) other than (8).

[Claim 3] The maximum diameter on a biaxially oriented polyester film is 0.3.

3. The biaxially oriented polyester film according to claim 1, wherein the number of fish eyes is 5 or less/ ² .

[Claim 4] A method for producing the biaxially oriented polyester film according to any one of claims 1 to 3,

Step 8 of casting a resin composition for producing a biaxially oriented polyester film in a cooling port to form an unstretched sheet,

A step of blowing air onto the unstretched sheet on the cooling port,

When the total width of the unstretched sheet is 100%, the process \¥02020/175058 40 units (：171?2020/004302

When the temperature of the wind to be applied is X, and the temperature of the air blown to both ends is assumed to be 15 ^° 〇 or less, and the temperature is lower than X.

The method for producing a biaxially oriented polyester film, wherein the edge portion includes at least a region within 10% from the edge.