JP2002178401A - Biaxially stretched polyester film and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a biaxially stretched polyester film having excellent tearing rectilinearity, strength, heat resistance and dimensional stability and useful as a packaging material for foods such as confectionery, pickles, miso, soup, jam, frozen food, cold storage food, retort-packed pouch or the like, pharmaceutical product, daily necessities, cosmetics or the like, and a method for manufacturing the same. SOLUTION: The biaxially stretched polyester film comprises a polyester composition containing at least two types or more of polyester components and having an ester exchange rate <B> value of less than 0.150. Thus, the film has excellent tearing rectilinearity of a flowing direction of a machine.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a confectionery, pickle, miso, soup, jam, frozen, refrigerated, retort pouch, etc., having excellent tear straightness, excellent strength, heat resistance and dimensional stability. The present invention relates to a biaxially oriented polyester film useful as a packaging material for foods, pharmaceuticals, daily necessities, cosmetics, and the like, and a method for producing the same.

[0002]

2. Description of the Related Art Packaging bags made of various plastic films are often used for packaging foods, medicines and miscellaneous goods. Two or three layers of a biaxially oriented plastic film and a heat-sealable non-oriented plastic film are used. The packaging bags laminated as described above are widely used. The biaxially oriented polyester film has excellent durability, moisture resistance, mechanical strength, heat resistance, and oil resistance. Manufactured using tubular method, flat simultaneous biaxial stretching method, flat sequential biaxial stretching method, etc. The obtained biaxially stretched polyester film is widely used in the field of food packaging.

However, a packaging bag using a biaxially oriented polyester film has a problem in that tear-openability is poor. There is a method of providing a notch to improve the openability, but when tearing from the notch, a phenomenon that it does not tear linearly often occurs, and not only is the content scattered but wasted, but also cookies etc. The soft confectionery may break when opened, or may cause troubles such as soiling clothes when the contents are liquid.

[0004] As an easy-opening packaging material excellent in straightness when the film is torn, there is a material obtained by laminating a uniaxially oriented polyolefin film as an intermediate layer. Examples of such a film include a three-layer laminate film of a biaxially oriented polyester film / a uniaxially oriented polyolefin film / a non-oriented polyolefin film,
An intermediate layer had to be provided, which was problematic in terms of cost, and its use was limited. Due to such circumstances, there is a demand for a polyester film having excellent tear straightness even if it is a single layer, but there are some problems in its development.

[0005] Another problem in use is that the conventional polyester film having excellent tear straightness has a low impact strength and may break during handling when used as a retort bag. had.

[0006] Manufacturing problems have the following problems. A conventional polyester film excellent in tear straightness expresses tear straightness by utilizing the anisotropy of the phase separation structure of the polymer blend. In order to control the anisotropy of this film, for example, JP-A-08-169
962 specifies the anisotropy of the unstretched sheet. However, before the film is completed, since the stretching process, relaxation process, heat setting process, etc. are included, the anisotropy changes depending on the process experienced afterwards, and it can be finally controlled to the desired anisotropy. was difficult.

In general, two types of polyester chips are melt-mixed to develop a phase-separated structure by a polymer blend. In this case, when a large-scale melt-mixing or a raw material is used, a polyester composition is used. , The thermal stability is reduced. In particular, there is a problem that the tearing straightness deteriorates due to a transesterification reaction occurring between the mixed polyesters.

[0008]

DISCLOSURE OF THE INVENTION The present invention is intended to solve such a problem, and it is intended to solve the problems of the biaxially oriented polyester film, such as the mechanical properties, fragrance retention, heat resistance, oil resistance, and the like. An object of the present invention is to provide a biaxially oriented polyester film that has both excellent tear straightness and impact strength while maintaining moisture absorption properties and dimensional stability under dry heat and wet heat environments particularly required for food packaging materials. is there. Furthermore,
The purpose of this study is to provide a biaxially oriented polyester film with excellent tearing straightness, in which the transesterification reaction progresses little even under production conditions subject to severe thermal histories and conforms to a wide range of production conditions. is there.

[0009]

Means for Solving the Problems The present inventors have made intensive studies to solve such problems, and as a result, have reached the present invention. That is, the present invention comprises a polyester composition containing at least two or more kinds of polyester components, and has a transesterification ratio <B> value of less than 0.150. It is an excellent biaxially oriented polyester film.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The biaxially oriented polyester film of the present invention comprises a polyester composition containing at least two or more polyester components. Preferably, the polyester composition comprises a polyester (A) comprising at least one crystalline polyester resin in which at least 80 mol% of the acid component is terephthalic acid and at least 97 mol% of the glycol component is a single glycol; Crystal segment of ℃ or more, and melting point or softening point is 100 ℃
Below, it is good to be a mixture with the block copolymer polyester (B) which consists of a soft polymer whose molecular weight is 400-8000. With such a configuration, the tear straightness and impact strength of the biaxially oriented polyester film are improved.

The crystalline polyester resin in the polyester (A) includes, for example, a polyester having ethylene terephthalate as a main repeating unit, preferably polyethylene terephthalate (PET).
Is used, and at least 80 mol% of the acid component is terephthalic acid and at least 97 mol% of the glycol component is a single glycol, such as two or more crystalline polyester resins such as PET and polybutylene terephthalate (PB).
T), a mixture of PET and polyethylene naphthalate (PEN) can be used. PET and PB
Mixtures of T are preferred. Moreover, 80 mol% or more of the acid component is terephthalic acid, and 97 mol of the glycol component.
% Or more of a single glycol may be used, and copolymers of two or more crystalline polyester components such as PET and polybutylene terephthalate (PBT), and PET and polyethylene naphthalate (PEN) may be used.

The polyethylene terephthalate preferably has an intrinsic viscosity of 0.60 dl / g or more.
More preferably, it is 0.62 dl / g or more and 0.8 dl / g or less. When the intrinsic viscosity is less than 0.60 dl / g, the impact strength is not excellent. Intrinsic viscosity is 0.8
If the material is larger than dl / g, the extrusion moldability is poor.

The method of polymerizing the crystalline polyester resin is not particularly limited, but a solid phase polymerization method can be used in combination to keep the intrinsic viscosity in a suitable range.

In the above block copolymer polyester (B), the crystal segment having a melting point of 170 ° C. or higher has a melting point of 170 ° C. or higher when a polymer is formed solely from its components. As such a crystal segment, for example, a residue of an aromatic dicarboxylic acid such as terephthalic acid, isophthalic acid, or 2,6-naphthalenedicarboxylic acid, and ethylene glycol, propylene glycol, butanediol, pentamethylene glycol, P-xylene glycol, Polyesters comprising residues of aliphatic, aromatic, or alicyclic diols such as cyclohexanedimethanol can be used, and it is particularly desirable that terephthalic acid residues account for 80 mol% or more.

In the block copolymer polyester (B), a soft polyester having a molecular weight of 400 to 8000 has a melting point or softening point of 100 ° C. or lower when measured only with the segment constituents. Molecular weight 40
When less than 0 is used, the obtained block copolymerized polyester (B) has a low melting point and a high tackiness, and it is difficult to process it into a film. In addition, the molecular weight is 80
If it exceeds 00, the soft polymer undergoes layer separation, exhibits an extremely high melt viscosity, becomes hard and brittle, and becomes difficult to remove from the polymerization vessel after the copolymerization reaction. When combined with
Transparency is poor. Particularly preferably, the molecular weight is 8
Those having a molecular weight of 00 to 4000 are preferred.

Examples of the soft polymer include polyethers such as polyethylene oxide glycol, polytetramethylene oxide glycol, polypropylene oxide glycol, copolymerized glycol of ethylene oxide and propylene oxide, and copolymerized glycol of ethylene oxide and tetrahydrofuran. And aliphatic polyesters such as polyneopentyl azelate, polyneopentyl adipate and polyneopentyl sepacate, and polylactones such as poly-ε-caprolactone and polypivalolactone. Preferably, polyethylene oxide glycol, polytetramethylene oxide glycol and the like are practical.

In the block copolymerized polyester (B), the proportion of the soft polymer in the block copolymerized polyester is preferably in the range of 1 to 12 mol%. When the amount is less than 1 mol%, it is difficult to obtain the properties as a soft polymer, and when the amount exceeds 12 mol%, the dispersion of the block copolymer polyester (B) becomes large at the time of mixing and melting with the polyester (A), and the tear straightness decreases. And the transparency is also reduced. Particularly preferably, it is 3 to 8 mol%.

Specific examples of the block copolymer polyester (B) include a polyethylene terephthalate-polyethylene oxide block copolymer, a polyethylene terephthalate-polytetramethylene oxide block copolymer, a polybutylene terephthalate-polyethylene oxide block copolymer, Polybutylene terephthalate-polytetramethylene oxide block copolymer,
Polyethylene terephthalate-polyethylene oxide, polypropylene oxide block copolymer, polytetramethylene terephthalate / isophthalate-polytetramethylene oxide block copolymer, polyethylene terephthalate-poly-ε-caprolactone block copolymer, polybutylene terephthalate-poly-ε Caprolactone block copolymer, polyethylene terephthalate-polyneopentylseparate block copolymer, block copolymer of polyester from di (4-carboxyphenoxy) ethane and ethylene glycol with polyethylene glycol, bis (N-paracarbo (Ethoxyphenyl) block copolymer of polyethylene glycol with polyester from adipamide and ethylene glycol. Can be. The block copolymer is composed of the various components described above, and one type may be used alone or two or more types may be used in combination.

The block copolymer polyester (B) can be produced by a usual condensation polymerization method.

In the present invention, the polyester (A)
Is mainly composed of polyethylene terephthalate (a) and polybutylene terephthalate (b), polyethylene terephthalate (a) is 90 to 7
0 wt%, the total amount of polybutylene terephthalate (b) and block copolymer polyester (B) is 10 to 30 wt%
%. More preferably, polyethylene terephthalate (a) is 90 to 75 wt%, and the total amount of polybutylene terephthalate (b) and block copolymerized polyester (B) is 10 to 25 wt%, and particularly preferably, polyethylene terephthalate (a) is 90 to 80 wt%.
%, And the total amount of polybutylene terephthalate (b) and block copolymer polyester (B) is preferably 10 to 20 wt%. When the sum of the polybutylene terephthalate (b) and the block copolymerized polyester (B) is less than 10% by weight, the tear straightness cannot be obtained. When the sum of the polybutylene terephthalate (b) and the block copolymerized polyester (B) exceeds 30% by weight, the tensile strength of the biaxially oriented polyester film decreases, and the dimensional stability and rigidity decrease. When the polyester (A) is mainly composed of polyethylene terephthalate (a) and polybutylene terephthalate (b), the polybutylene terephthalate (b) and the block copolymerized polyester (B)
Is not particularly limited.

In the present invention, the polyester (A)
Is mainly composed of polyethylene terephthalate,
The mixing ratio of each resin is from 90 to polyethylene terephthalate.
70 wt%, 10 block copolymer polyester (B)
It is preferably about 30% by weight. More preferably,
90 to 75% by weight of polyethylene terephthalate, 10 to 25% by weight of the block copolymer polyester (B), particularly preferably 90 to 80% by weight of polyethylene terephthalate.
wt%, block copolymer polyester (B) 10-2
The content is preferably 0 wt%. When the amount of the block copolymer polyester (B) is less than 10% by weight, tearing straightness cannot be obtained. Further, when the block copolymerized polyester (B) is 30
If the content exceeds wt%, the tensile strength of the biaxially oriented polyester film decreases, and dimensional stability and rigidity decrease.

The biaxially oriented polyester film of the present invention must have a transesterification <B> value of less than 0.150. By setting the transesterification ratio <B> to less than 0.150, the functions of the components of the polyester composition constituting the biaxially oriented polyester can be sufficiently exhibited. In addition, it becomes compatible with a wide range of manufacturing conditions, and even if the biaxially oriented polyester film of the present invention is used as a raw material for recovery, it is possible to prevent a decrease in straight-line tearing due to repetition of heat history and to maintain performance, thereby reducing costs. Can be reduced. In particular, when the above-mentioned block copolymer polyester (B) is included, the effect of improving tear straightness is effectively exhibited. The transesterification <B> value is 0.1
It is preferably less than 00, more preferably less than 0.07.

The method for reducing the ester exchange rate <B> value to less than 0.150 and further reducing it is not particularly limited. For example, titanium as a catalyst for synthesizing the constituent resin of the biaxially oriented polyester film of the present invention may be titanium. Although it can be realized by avoiding the use of a system catalyst or the like, it is extremely effective to include a transesterification inhibitor in the polyester composition used.

As the transesterification inhibitor, an organic phosphorus compound having at least one PO bond in the molecule is preferably used. Examples of such a substance include an organic phosphorus ether such as an organic phosphite, an organic phosphorus ester such as an organic phosphate, and an organic phosphorus ether such as an organic phosphine oxide. Specific examples of such a substance include, for example, aromatic phosphites such as triphenyl phosphite, aliphatic phosphites such as bis (acetadeca) pentaerythritol diphosphite, and bis (2,6-di-t- Butyl-4-methylphenyl) pentaerythritol diphosphite, bis (2,4-dicumylphenyl) pentaerythritol diphosphite, 2-[[2,4,8,10, -tetrakis (1,1-dimethylether) Dibenzo [d, f]
[1,2,3] dioxaphosphepin-6-yl] oxy] -N, N-bis [2-[[2,4,8,10, -tetrakis (1,1-dimethylel) dibenzo [[ d,
f] [1,3,2] dioxaphosphepin 6-yl]
Oxy] -ethyl] ethanolamine, aliphatic aromatic phosphites such as diphenylisodecyl phosphite, trimethyl phosphate, triethyl phosphate, tributyl phosphate, ethyl diethyl phosphono acetate;
Organic phosphate esters such as benzylethylphosphonate, di-2-ethylhexyl phosphate, and tris (2-chloroethyl) phosphate can be given.

The content of the organic phosphorus compound having at least one PO bond in the molecule in the polyester composition is based on the amount of metal [M] in the metal catalyst present in the polyester composition. It is preferable that the ratio [P] / [M] of the amount of phosphorus [P] in the organic phosphorus compound is in the range of 0.5 or more and 500 or less. [P] / [M]
When the value is smaller than the above range, the coordination efficiency of the metal to the organic phosphorus compound is reduced, the deactivation of the catalyst is insufficient, and when the value is larger than the above range, the organic phosphorus compound acts plastically and lowers the physical properties of the film. become.

The polyester composition constituting the biaxially oriented polyester film of the present invention does not cause any problem even if appropriate additives such as an antioxidant, an antiblocking agent, an ultraviolet absorber and a lubricant are added in advance.

The heat shrinkage of the biaxially oriented polyester film of the present invention is 3% or less in both the machine flow direction (MD direction) and the width direction (TD direction) at 150 ° C. for 30 minutes. It is preferred that When the heat shrinkage exceeds 3%, printability deteriorates.

The haze of the biaxially oriented polyester film of the present invention is preferably 4% or less. If it exceeds 4%, the transparency of the film deteriorates, and the commercial value is impaired.

In the production of the biaxially oriented polyester film of the present invention, the blending order of each resin in the polyester composition constituting the film is not particularly limited, but a chip mixture in which each resin is simultaneously mixed in a chip state is used as a raw material. Simultaneous mixing and extrusion are preferred because they form a suitable phase-separated structure of the polymer and, even after a large-scale manufacturing process with a severe thermal history, provide improved tear straightness.

In the production of the biaxially oriented polyester film of the present invention, when a transesterification inhibitor is contained in the polyester composition, it may be added directly by melt-mixing in a melt extruder in the film production process. Alternatively, a chip obtained by melting and mixing the raw material resin in advance may be used.

The method for producing the biaxially oriented polyester film of the present invention is not particularly limited, and examples thereof include the following method. A mixture of each resin in the polyester composition constituting the film in the form of chips is charged into an extruder, melted by heating, and extruded and discharged from a die orifice of a T-die into a sheet. In this case, the shear rate of the resin at the die orifice is preferably 200 sec ^-1 or more. If the shear rate is less than 200 sec ⁻¹ , the isotropic evaluation value of the film is larger than 0.70, and the straight cut property cannot be obtained. Next, the sheet in this softened state
It is wound tightly around the cooling drum and cooled. Subsequently, the obtained unstretched sheet is stretched at a stretching ratio of 3 to 4 times in the machine direction at a temperature of 90 to 110 ° C. Then, 8
The film is stretched at a temperature of 0 to 110 ° C. in the transverse direction at a stretch ratio of 3.5 to 4.5 times. If the stretching ratio is less than the respective temperatures, it may not be possible to obtain a uniform stretched film, and if the respective temperatures exceed the respective temperatures, the crystallization of the crystalline polyester resin is promoted and the transparency is deteriorated. There is. The biaxially stretched film is subsequently
Heat treatment is performed at a temperature of ~ 250 ° C. Heat treatment temperature is 21
If the temperature is lower than 0 ° C., the shrinkage of the film increases, which causes deformation when the film is used as a bag. On the other hand, when the temperature is higher than 250 ° C., the film melts and it becomes difficult to form a film. The biaxial stretching method is preferably a sequential biaxial method using a roll and a tenter, and it is desirable that the film be stretched in the longitudinal direction and then stretched in the transverse direction. When the longitudinal stretching is performed after the transverse stretching, it is difficult to obtain a straight tearing property.

The biaxially oriented polyester film of the present invention can be subjected to a corona discharge treatment, a flame treatment, a surface hardening treatment or a surface treatment with various coatings.

Next, the present invention will be described specifically with reference to Test Examples and Examples, but the present invention is not limited to these.

Test Examples Test Methods (1) Reduced Viscosity and Intrinsic Viscosity For each of the resins used in Examples and Comparative Examples, using a Ubbelohde type viscosity tube, a mixed solvent of phenol / tetrachloroethane in a weight ratio of 6/4 was added to The sample was dissolved at a solution concentration of 0.4 g / dl, the reduced viscosity was determined from the value measured at a temperature of 30 ° C., and the reduced viscosity was further converted to the intrinsic viscosity as necessary.

(2) Ester exchange ratio <B> value Biaxially oriented polyester film 70 of Examples and Comparative Examples
0 mg dissolved in deuterated trifluoroacetic acid solvent,
Varian Co. UNITY-500 (125MH
13C-NMR spectrum was measured at room temperature using z). In the obtained chart, the peak integrated intensity Ia derived from carbons at the 1st and 4th positions in the terephthalic acid unit bonded only to the ethylene glycol unit (at 13
5.6 ppm), the peak integrated intensity Ib (135.9 ppm) derived from the terephthalic acid unit and the 1st and 4th carbons in the terephthalic acid unit only bonded to the butanediol unit, and both the ethylene glycol unit and the butanediol unit. Of the carbons at the 1- and 4-positions of the terephthalic acid unit bound to the butanediol unit
Integrated intensity Id (136.1 pp
m), and the transesterification <B> value is represented by the following formula 1. <B> = {Id / (Ia + Id)} + {Id / (Ib + Id)} Equation 1

(3) Straightness of tearing From the biaxially oriented polyester films of Examples and Comparative Examples, strips of 200 mm in the MD direction and 40 mm in the TD direction were cut out, and one short side of this film piece was cut out. A sample with a notch of 5 mm in the center was placed on 30
I made this book. Next, the tearing was performed by hand in the MD direction from the cut, and when the tear propagation end reached within 5 mm from the center of the short side facing the cut side, a circle of 5 mm
Those that reached the above were evaluated as △, and those that did not reach the opposite short sides were evaluated as ×, and the tear straightness was evaluated.

2. Test results The results of the above test (1) are shown in Examples, and the results of (2) and (3) are shown in Tables 4 to 6.

[0038]

EXAMPLES Example 1-1 As polyethylene terephthalate (a) in polyester (A), RE553 manufactured by Toyobo Co., Ltd.
62 dl / g) using 82 wt% of polyester (A)
9 wt% of Novadur NV5020 manufactured by Mitsubishi Plastics, Inc. as a polybutylene terephthalate (b), 100 mol% of terephthalic acid as a dicarboxylic acid component, 93.3 mol% of butanediol as a diol component, and a molecular weight of 1000 as a block copolymerized polyester (B). 9 wt% of copolymerized PBT (reduced viscosity 1.50 dl / g) composed of 6.7 mol% of tetramethylene glycol
The mixture was prepared in a solid chip state at a ratio of. This chip mixture was put into a 200 mmφ extruder equipped with a T die, melt-extruded at a resin temperature of 280 ° C.
Approximately 2mm in thickness, quenched by close contact with the cast roll adjusted to ℃
A 00 μm unstretched sheet was obtained. At this time, the shear rate at the die was 360 sec ⁻¹ . Next, the obtained unstretched sheet was rolled at 100 ° C. with a roll-type longitudinal stretching machine.
After stretching 7 times and 4.5 times with a tenter type transverse stretching machine at 105 ° C., perform a 5% relaxation treatment in the transverse direction, perform a heat treatment at 240 ° C., cool to room temperature, and form a 12 μm thick An axially oriented polyester film was obtained.

Example 1-2 As polyethylene terephthalate (a) in polyester (A), RE553 manufactured by Toyobo Co., Ltd.
62 dl / g) using 82 wt% of polyester (A)
6 wt% of Novadur NV5020 manufactured by Mitsubishi Plastics, Inc., 100 mol% of terephthalic acid as a dicarboxylic acid component, 93.3 mol% of butanediol as a diol component, a polybutylene terephthalate (b) having a molecular weight of 1000 as polybutylene terephthalate (b). 12 wt% of copolymerized PBT (reduced viscosity 1.50 dl / g) composed of 6.7 mol% of tetramethylene glycol
The mixture was prepared in the form of solid chips at a ratio of% and a biaxially oriented polyester film was obtained in the same manner as in Example 1-1.

Example 1-3 As polyethylene terephthalate (a) in polyester (A), RE553 manufactured by Toyobo Co., Ltd.
62 dl / g) using 82 wt% of polyester (A)
13.5 wt% of Novadur NV5020 manufactured by Mitsubishi Plastics Corporation as polybutylene terephthalate (b) in
As the block copolymerized polyester (B), 100 mol% of terephthalic acid as a dicarboxylic acid component, 85.7 mol% of butanediol as a diol component, and a molecular weight of 10
14.3 mol% of polytetramethylene glycol of 00
Was mixed in a solid chip state at a ratio of 4.5% by weight of a copolymerized PBT (reduced viscosity 1.90 dl / g), and a biaxially oriented polyester film was obtained in the same manner as in Example 1-1.

Example 1-4 As polyethylene terephthalate (a) in polyester (A), RE553 manufactured by Toyobo Co., Ltd.
62 dl / g) using 82 wt% of polyester (A)
1.0 wt% of Novadur NV5020 manufactured by Mitsubishi Plastics, Inc. as polybutylene terephthalate (b), 100 mol% of terephthalic acid as a dicarboxylic acid component, 96.7 mol% of butanediol as a diol component, and a molecular weight of 100 as a block copolymerized polyester (B).
Of copolymerized PBT (reduced viscosity 1.33 dl / g) consisting of 3.3 mol% of polytetramethylene glycol
What was mixed in the ratio of wt% was adjusted. This is 90m
It was melt-extruded from a T-die at a resin temperature of 270 ° C. using an mφ extruder, and was closely adhered and rapidly cooled to a cast roll adjusted to 25 ° C. to obtain an unstretched sheet having a thickness of about 200 μm. The shear rate at this time is 360 sec ^-1.
Met. Next, the obtained unstretched sheet is stretched 3.7 times at 100 ° C. by a roll type longitudinal stretching machine and 4.5 times at 105 ° C. by a tenter type transverse stretching machine, and then relaxed by 5% in the transverse direction. After the treatment, heat treatment was performed at 240 ° C., and the mixture was cooled to room temperature to obtain a biaxially oriented polyester film having a thickness of 12 μm.

Example 1-5 As polyethylene terephthalate (a) in polyester (A), RE553 manufactured by Toyobo Co., Ltd.
62 dl / g) as a block copolymer polyester (B), 100 mol% of terephthalic acid as a dicarboxylic acid component, 96.7 mol% of butanediol as a diol component, and 3.3 mol% of polytetramethylene glycol having a molecular weight of 1,000. A mixture prepared by mixing polymerized PBT (reduced viscosity: 1.33 dl / g) at a ratio of 18 wt% was prepared. This was melt extruded from a T-die at a resin temperature of 270 ° C. using a 90 mmφ extruder,
The roll was closely cooled to a cast roll adjusted to 5 ° C. and rapidly cooled to obtain an unstretched sheet having a thickness of about 200 μm. At this time, the shear rate at the die was 360 sec ⁻¹ . Next, the obtained unstretched sheet is stretched 3.7 times at 100 ° C. by a roll type longitudinal stretching machine and 4.5 times at 105 ° C. by a tenter type transverse stretching machine, and then relaxed by 5% in the transverse direction. Treat at 240 ° C
And cooled to room temperature to obtain a biaxially oriented polyester film having a thickness of 12 μm.

Comparative Example 1-1 As a polyethylene terephthalate (a) in the polyester (A), 90 wt% of RE553 (intrinsic viscosity: 0.62 dl / g) manufactured by Toyobo Co., Ltd., and as a dicarboxylic acid component as a block copolymerized polyester (B) Copolymerized PBT comprising 100 mol% of terephthalic acid, 96.7 mol% of butanediol as a diol component, and 3.3 mol% of polytetramethylene glycol having a molecular weight of 1,000
(Reduced viscosity of 1.33 dl / g) was mixed at a ratio of 10 wt%. This was melt-extruded from a T-die at a resin temperature of 280 ° C. using a 200 mm φ extruder, and closely adhered to a cast roll adjusted to 25 ° C., and rapidly cooled.
An unstretched sheet having a thickness of about 200 μm was obtained. At this time, the shear rate at the die was 360 sec ⁻¹ . Then, the obtained unstretched sheet was rolled with a roll-type longitudinal stretching machine to 100
After stretching 3.7 times at 105 ° C. and 4.5 times at 105 ° C. with a tenter-type transverse stretching machine, a 5% relaxation treatment in the transverse direction was performed.
Heat treatment at 240 ° C, cool to room temperature, thickness 12μ
m biaxially oriented polyester film was obtained.

Comparative Example 1-2 Polyethylene terephthalate (a) in polyester (A) was RE553 (manufactured by Toyobo Co., Ltd.)
62 dl / g) of 92 wt%, 100 mol% of terephthalic acid as a dicarboxylic acid component, 93.3 mol% of butanediol as a diol component, and 6.7 mol% of polytetramethylene glycol having a molecular weight of 1000 as a block copolymer polyester (B). A mixture of polymerized PBT (reduced viscosity 1.50 dl / g) in a solid chip state at a ratio of 8 wt% was prepared, and a biaxially oriented polyester film was obtained in the same manner as in Example 1-1.

Example 2-1 Polyethylene terephthalate (a) in polyester (A) was RE553 manufactured by Toyobo Co., Ltd.
The block copolymer polyester (B) is composed of 100 mol% of terephthalic acid as a dicarboxylic acid component, 96.7 mol% of butanediol as a diol component, and 3.3 mol% of polytetramethylene glycol having a molecular weight of 1,000. Copolymerized PBT
(Reduced viscosity: 1.33 dl / g) mixed at a ratio of 18 wt%, and bis (acetadeca) petaerythritol diphosphite (manufactured by Asahi Denka Co., Ltd.)
A trade name of ADK STAB PEP-8) was prepared in an amount of 0.4 part by weight based on 100 parts by weight of the polyester composition. This is 200 with T die
It was put into a mmφ extruder, melt-extruded at a resin temperature of 280 ° C., and closely cooled to a cast roll adjusted to 25 ° C. to obtain an unstretched sheet having a thickness of about 200 μm. At this time, the shear rate at the die was 360 sec ⁻¹ .
Then, the obtained unstretched sheet is rolled with a roll-type longitudinal stretching machine to obtain 1 sheet.
After stretching 3.7 times at 00 ° C and 4.5 times at 105 ° C with a tenter-type transverse stretching machine, it is subjected to a 5% relaxation treatment in the transverse direction, heat-treated at 240 ° C, and cooled to room temperature. , Thickness 1
A 2 μm biaxially oriented polyester film was obtained.

Example 2-2 Bis (2,6-di-tert-butyl-4-methylphenyl) pentaerythritol diphosphite (trade name, manufactured by Asahi Denka, ADK STAB PEP-3) as a transesterification inhibitor
A biaxially oriented polyester film was obtained in the same manner as in Example 2-1, except that 6) was used and 0.7 parts by weight was added to 100 parts by weight of the polyester composition.

Example 2-3 As a transesterification inhibitor, bis (2,4-dicumylphenyl) pentaerythritol diphosphite (manufactured by Asahi Denka, trade name, Adekastab PEP-45) was used, and 100 parts by weight of a polyester composition was used. A biaxially oriented polyester film was obtained in the same manner as in Example 2-1 except that the addition amount was 0.7 parts by weight to the above.

Comparative Example 2-1 Example 2-1 except that no transesterification inhibitor was used.
In the same manner as in the above, a biaxially oriented polyester film was obtained.

Example 2-4 As polyethylene terephthalate (a) in polyester (A), RE553 manufactured by Toyobo Co., Ltd.
The block copolymer polyester (B) is composed of 100 mol% of terephthalic acid as a dicarboxylic acid component, 96.7 mol% of butanediol as a diol component, and 3.3 mol% of polytetramethylene glycol having a molecular weight of 1,000. Copolymerized PBT
(Reduced viscosity of 1.33 dl / g) at 13.5 wt%, and 100 mol of terephthalic acid as a dicarboxylic acid component
%, Butanediol 85.7 mol as diol component
%, Polytetramethylene glycol 1 having a molecular weight of 1000
4.3 mol% copolymerized PBT (reduced viscosity 0.8
Bis (acetadeca) pentaerythritol diphosphite (trade name, manufactured by Asahi Denka Co., Ltd.) as a transesterification inhibitor.
Adekastab PEP-8) is a polyester composition 100
What was added so that it might become the ratio of 0.4 weight part with respect to weight part was prepared. This was put into a 200 mmφ extruder equipped with a T die, melt-extruded at a resin temperature of 280 ° C., closely adhered to a cast roll adjusted to 25 ° C., and rapidly cooled.
An unstretched sheet having a thickness of about 200 μm was obtained. At this time, the shear rate at the die was 360 sec ^{- 1} . Next, the obtained unstretched sheet is rolled to a longitudinal stretching machine at 100 ° C.
3.7 times at 105 ° C with a tenter type horizontal stretching machine.
After stretching by a factor of 5, a 5% relaxation treatment in the transverse direction was performed,
Heat treatment was performed at 0 ° C., and the mixture was cooled to room temperature to obtain a biaxially oriented polyester film having a thickness of 12 μm.

Example 2-5 Bis (2,6-di-t-butyl-4-methylphenyl) pentaerythritol diphosphite (trade name, manufactured by Asahi Denka, Adekastab PEP-3) as a transesterification inhibitor
Using 6), a biaxially oriented polyester film was obtained in the same manner as in Example 2-4, except that 0.7 parts by weight was added to 100 parts by weight of the polyester composition.

Example 2-6 Bis (2,4-dicumylphenyl) pentaerythritol diphosphite (trade name, manufactured by Asahi Denka, ADK STAB PEP-45) was used as a transesterification inhibitor, and 100 parts by weight of a polyester composition was used. A biaxially oriented polyester film was obtained in the same manner as in Example 2-4, except that 0.7 parts by weight of the polyester film was added.

Example 2-7 The amount of the transesterification inhibitor added to the polyester composition 1
Example 2 except that 0.2 parts by weight was added to 00 parts by weight.
In the same manner as in -1, a biaxially oriented polyester film was obtained.

Example 2-8 The amount of the transesterification inhibitor added to the polyester composition 1
Example 2 except that 0.3 parts by weight was added to 00 parts by weight.
-2, a biaxially oriented polyester film was obtained.

Example 2-9 Polyester composition 1
Example 2 except that 0.3 parts by weight was added to 00 parts by weight.
In the same manner as in the step No.-3, a biaxially oriented polyester film was obtained.

Comparative Example 2-2 Example 2-4 except that no transesterification inhibitor was used.
In the same manner as in the above, a biaxially oriented polyester film was obtained.

Example 3-1 As polyethylene terephthalate (a) in polyester (A), RE553 manufactured by Toyobo Co., Ltd.
62 dl / g) using 82 wt% of polyester (A)
6 wt% of Novadur NV5020 manufactured by Mitsubishi Plastics, Inc., 100 mol% of terephthalic acid as a dicarboxylic acid component, 93.3 mol% of butanediol as a diol component, a polybutylene terephthalate (b) having a molecular weight of 1000 as polybutylene terephthalate (b). 12 wt% of copolymerized PBT (reduced viscosity 1.50 dl / g) composed of 6.7 mol% of tetramethylene glycol
A mixture prepared in a solid chip state at a ratio of% was prepared.
Further, bis (acetadeca) pentaerythritol diphosphite (trade name, Adekastab PEP-8, manufactured by Asahi Denka) as a transesterification inhibitor was added to the chip mixture at a ratio of 0.4 parts by weight to 100 parts by weight of the polyester composition. So that it becomes 200 mm with a T-die.
It was put into a φ extruder, melt-extruded at a resin temperature of 280 ° C., closely adhered to a cast roll adjusted to 25 ° C. and rapidly cooled to obtain an unstretched sheet having a thickness of about 200 μm. At this time, the shear rate at the die was 360 sec ⁻¹ . Then, the obtained unstretched sheet was rolled by a roll-type longitudinal stretching machine to 10
After stretching 3.7 times at 0 ° C. and 4.5 times at 105 ° C. with a tenter-type transverse stretching machine, a 5% relaxation treatment in the transverse direction was performed.
Heat treatment at 240 ° C, cool to room temperature, thickness 12μ
m biaxially oriented polyester film was obtained.

Example 3-2 Bis (2,6-di-t-butyl-4-methylphenyl) pentaerythritol diphosphite (trade name, manufactured by Asahi Denka, ADK STAB PEP-3) as a transesterification inhibitor
Using 6), a biaxially oriented polyester film was obtained in the same manner as in Example 3-1 except that 0.7 parts by weight was added to 100 parts by weight of the polyester composition.

Example 3-3 100 parts by weight of a polyester composition using bis (2,4-dicumylphenyl) pentaerythritol diphosphite (trade name, Adekastab PEP-45, manufactured by Asahi Denka) as a transesterification inhibitor A biaxially oriented polyester film was obtained in the same manner as in Example 3-1 except that the mixture was added so that the ratio was 0.7 parts by weight based on the weight of the polyester film.

Example 3-4 The amount of the transesterification inhibitor was changed to polyester composition 1
Example 3 except that 0.2 parts by weight was added to 00 parts by weight.
In the same manner as in -1, a biaxially oriented polyester film was obtained.

Example 3-5 The amount of the transesterification inhibitor added to the polyester composition 1
Example 3 except that the amount was 0.3 parts by weight with respect to 00 parts by weight.
-2, a biaxially oriented polyester film was obtained.

Example 3-6 The amount of the transesterification inhibitor added to the polyester composition 1
Example 3 except that the amount was 0.3 parts by weight with respect to 00 parts by weight.
In the same manner as in Preparation No.-3, a biaxially oriented polyester film was obtained.

Comparative Example 3-1 Example 3-1 except that no transesterification inhibitor was used.
In the same manner as in the above, a biaxially oriented polyester film was obtained.

[0063]

According to the present invention, the biaxially oriented polyester film has the following characteristics: durability, moisture proofness, mechanical properties,
A biaxially oriented polyester film having heat resistance, oil resistance, and tearability in the MD direction of the film and having improved bag dropping strength is obtained. Further, a biaxially oriented polyester film having the above characteristics can be efficiently and inexpensively provided by mass production using a large-scale production machine or a production method utilizing recovered materials.

[Table 1]

[Table 2] PEP-8: Pheas (acetadica) pentaerythritol phosphite (molecular weight: 732, P is 62) PEP-36: Pheas (2,6-di-t-butyl-4-methylphenyl) pentaerythritol phosphite ( PEP-45: bis (2,4-dimethylphenyl) pentaerythritol diphosphite (molecular weight 740, P is 62)

[Table 3] PEP-8: Pheas (acetadica) pentaerythritol phosphite (molecular weight: 732, P is 62) PEP-36: Pheas (2,6-di-t-butyl-4-methylphenyl) pentaerythritol phosphite ( PEP-45: bis (2,4-dimethylphenyl) pentaerythritol diphosphite (molecular weight 740, P is 62)

[Table 4]

[Table 5]

[Table 6]

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) B29L 7:00 B29L 7:00 (72) Inventor Keizo Kawahara 2-1-1 Katata Katsuta Otsu City, Shiga Prefecture Toyobo (72) Inventor Kazunori Okamoto 2-1-1 Katata, Otsu-shi, Shiga Prefecture Toyobo Research Institute (72) Inventor Tetsuyo Nagara 2-1-1 Katata, Otsu-shi, Shiga Prefecture No. 1 Toyobo Co., Ltd. (72) Inventor Keiji Mori 344 Maebata, Inuyama-shi, Aichi prefecture Inuyama factory (72) Inventor Kazumoto Imai 344 Maebata, Inuyama-shi, Aichi prefecture No.Toyobo Co., Ltd. Inuyama Factory F-term (reference) 4F071 AA44 AA45 AA46 AA47 AC15 AE22 BA01 BB06 BB08 BC01 BC17 4F210 AA24A AA24C AA24F AA24K AG01 AH 54 QA03 QG01 4J002 CF061 CF072 CF103 CF173 CF193 EW046 EW066 EW146 FD206 GG00

Claims (9)

[Claims] An excellent transesterification in the machine flow direction, characterized by comprising a polyester composition containing at least two or more polyester components and having a transesterification <B> value of less than 0.150. Biaxially oriented polyester film. 2. The polyester composition has an acid content of 80 m
ol% or more is terephthalic acid and the glycol component 9
Polyester (A) comprising at least one kind of crystalline polyester resin in which 7 mol% or more is a single glycol
And a crystal segment having a melting point of 170 ° C. or higher, and a melting point or softening point of 100 ° C. or lower and a molecular weight of 400 to 800.
2. The biaxially oriented polyester film according to claim 1, wherein the film is a mixture with a block copolymer polyester (B) composed of a soft polymer having an excellent tear straightness in a machine flow direction. 3. 3. Polyester (A) is mainly composed of polyethylene terephthalate (a) and polybutylene terephthalate (b), and the mixing ratio of each resin is 90 to 70 wt% of polyethylene terephthalate (a) and polybutylene terephthalate (b). And a block copolymer polyester (B) having a total amount of 10 to 30% by weight, which has excellent tear straightness in a machine flow direction.
The biaxially oriented polyester film according to the above. 4. The polyester (A) is mainly composed of polyethylene terephthalate, and the compounding ratio of each resin is such that polyethylene terephthalate is 90 to 70 wt% and block copolymer polyester (B) is 10 to 30 wt%. 3. The biaxially oriented polyester film according to claim 2, which has excellent tear straightness in a machine flow direction. 5. The biaxially oriented polyester film according to claim 1, wherein the polyester composition contains a transesterification inhibitor and has excellent tear straightness in a machine flow direction. . 6. The machine according to claim 5, wherein the transesterification inhibitor is an organophosphorus compound having at least one PO bond in the molecule, and the machine is excellent in tearing straightness in a machine flow direction. Biaxially oriented polyester film. 7. The biaxial shaft according to claim 1, wherein the transesterification ratio <B> is less than 0.100, and the machine is excellent in tearing straightness in a machine direction. Oriented polyester film. 8. The method according to claim 1, wherein the transesterification <B> value is less than 0.070, and the machine is excellent in tear straightness in a machine flow direction. Biaxially oriented polyester film. 9. The biaxially oriented polyester film according to claim 1, wherein a chip mixture obtained by simultaneously mixing each of the resins constituting the polyester composition in a chip state is used as a raw material. Manufacturing method.