JPH1110725A - Polyester film for transparent deposition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To manufacture properly a polyester film for deposition suitable for demonstrating the gas barrier properties of oxygen and water vapor of the polyester film for transparent deposition, and use the film widely for food packaging. SOLUTION: A biaxially oriented polyester film is composed of polyester of melting point of 250-280 deg.C as a main component, and provide with a fusion sub-peak (Ts) of the film of 210-245 deg.C, a planar orientation coefficient of 0.155-0.18, a birefringence (Δn) in the film longitudinal direction and the width direction of (-0.04)-(-0.005) and a centerline average roughness (Ra) of at least one face of 0.005-0.03 μm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyester film suitable for obtaining a transparent vapor deposition film having excellent barrier properties against oxygen and water vapor.

[0002]

2. Description of the Related Art In order to store foods and medicines for a long time,
It is necessary to perform packaging that has an effect of blocking intrusion of oxygen and water vapor from the outside air that promotes putrefaction and deterioration, and that has excellent so-called gas barrier properties. In recent years, there has been an increasing tendency for film packaging having excellent gas barrier properties used for this purpose to have transparency in which the state of contents can be particularly confirmed.

[0003]

It is known that a transparent gas barrier film is formed by laminating polyvinylidene chloride or an ethylene vinyl alcohol copolymer. Also,
It has been well known that a metal oxide formed on a polymer film has good gas barrier properties and transparency.

However, the conventional transparent gas barrier film has the following problems. Polyvinylidene chloride and ethylene vinyl alcohol laminated films do not have sufficient gas barrier properties against oxygen and water vapor, and their degradation is remarkable especially in sterilization treatment at high temperatures. Further, polyvinylidene chloride generates chlorine gas when incinerated, and there is a concern that it will affect the global environment.

[0005] On the other hand, polyester films on which an oxygen silicon film or an aluminum oxide film is formed by vapor deposition show good barrier properties. The importance of improving characteristics such as properties and long-term preservability of quality has been increasingly emphasized. Particularly in the packaging of snacks, foods and the like, more and more gas barrier properties have been required in order to prevent oxidation and wetness of the contents and to ensure fresh quality for a long period of time.

The present invention has been made in response to such a demand, and aims at remarkably improving the oxygen and water vapor gas barrier properties of the transparent polyester film for vapor deposition, and to provide a polyester film for vapor deposition exhibiting excellent gas barrier properties. Things.

[0007]

As a result of intensive studies to solve the above-mentioned problems, the present invention has found that the melting point is 250 to 280 ° C.
A polyester biaxially stretched polyester film having a melting sub-peak (Ts) of 210 to 245 ° C. and a plane orientation coefficient of 0.155 to 0.1
8. The birefringence (Δn) of the film is −0.04 to −0.0
05, the center line average roughness (Ra) of at least one side is 0.
It is intended to provide a transparent deposition polyester film having a thickness of from 005 to 0.03 μm.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The polyester of the polyester film as referred to in the present invention is a generic name of polymers having an ester bond as a main bonding chain, and ethylene terephthalate and polyester from the viewpoint of heat resistance, film forming property and the like. And / or an ethylene naphthalate unit as a main component is preferable. From the viewpoint of heat resistance and film-forming properties, it is necessary that the melting point of the polyester be 250 ° C or more and 280 ° C or less.

The polyester of the present invention may contain other copolymer components as long as the properties are not impaired. Examples of the dicarboxylic acid component include diphenyl dicarboxylic acid, diphenyl sulfone dicarboxylic acid, diphenoxyethane dicarboxylic acid, 5-sodium sulfoisophthalic acid, phthalic acid, aromatic dicarboxylic acids such as isophthalic acid, oxalic acid,
Aliphatic dicarboxylic acids such as succinic acid, eicoic acid, adipic acid, sebacic acid, dimer acid, dodecanedioic acid, maleic acid, fumaric acid, alicyclic dicarboxylic acids such as cyclohexyne dicarboxylic acid, p-oxybenzoic acid, etc. And polyfunctional acids such as oxycarboxylic acid, trimellitic acid, and pyromellitic acid. On the other hand, as the glycol component, for example, propanediol, butanediol, pentanediol, hexanediol, neopentyl glycol, etc.
And aliphatic glycols such as triethylene glycol, alicyclic glycols such as cyclohexanedimethanol, aromatic glycols such as bisphenol A and bisphenol S, diethylene glycol and polyalkylene glycol. Further, a polyether such as polyethylene glycol and polytetramethylene glycol may be copolymerized.

[0010] These dicarboxylic acid components and glycol components may be used in combination of two or more, or two or more polyesters may be blended and used. Further, two or more layers may be used as a co-extruded laminated film.

The laminated polyester in the present invention preferably contains ethylene terephthalate and / or ethylene naphthalate as a main component, and has a melting point of 210 to 2 from the viewpoint of improving adhesion to a vapor deposition layer and heat resistance.
Preferably it is 60 ° C. If the melting point is less than 210 ° C., not only the durability against heat load during processing is lowered, but also low molecular substances are precipitated on the surface, which causes deterioration of the barrier property.

The intrinsic viscosity (measured in orthochlorophenol at 25 ° C.) of the above-mentioned polyester film is 0.4 to 0.4.
1.2 dl / g, preferably 0.5 to 0.85 dl / g
Are suitable for the content of the present invention.

From the viewpoint of further improving the adhesiveness to the vapor-deposited layer, the amount of the carboxyl terminal group of the polyester film as the substrate is preferably at least 30 equivalents / ton, more preferably at least 35 equivalents / ton.

In the polyester, various additives such as heat stabilizers, oxidation stabilizers, weather stabilizers, ultraviolet absorbers, organic lubricants, pigments, dyes, organic or organic additives are used as long as the effects of the present invention are not impaired. You may mix | blend inorganic fine particles, a filler, a nucleating agent, etc.

Further, the film of the present invention may be coated with various coatings, and the coating is not particularly limited. However, in view of production and environment, an aqueous or water-dispersed coating agent is applied during film formation. preferable.

The polyester film of the present invention needs to be biaxially oriented. The biaxially oriented polyester film is formed by stretching a non-stretched PET sheet or film about 2.5 to 6 times in the longitudinal direction and the width direction, respectively, and performs biaxial orientation by wide-angle X-ray diffraction. Indicates a pattern.

The thickness of the polyester film of the present invention is not particularly limited and may be arbitrarily selected according to the intended use. The thickness is 0.1 to 1000 μm, preferably 0.5 to 5 μm.
It is 00 μm, and more preferably 5 to 30 μm.

As the film constitution, as described above, a single layer,
A / B two layers, B / A / B or A / B / C three layers,
Furthermore, a laminated structure of more than three layers may be employed, and the laminated thickness ratio may be arbitrarily set. Furthermore, layers other than these may be laminated, and specific examples include an antistatic layer, a mat layer, a hard coat layer, a slippery coat layer, an adhesive layer, an adhesive layer, and the like.

In the polyester film of the present invention,
The melting sub-peak (Ts) of the film is 210-245 ° C
And preferably 225 to 240
° C, more preferably 230-238 ° C. Ts is 2
If the temperature is less than 10 ° C., the thermal dimensional stability, especially at high temperatures (170 to
(200 ° C.) is not preferred because the thermal dimensional stability at 200 ° C.) deteriorates. On the other hand, if Ts exceeds 245 ° C., the film becomes brittle, which is not preferable.

In the polyester film of the present invention, the plane orientation coefficient needs to be 0.155 to 0.18, preferably 0.1625 to 0.175. When the plane orientation coefficient is less than 0.155, the orientation of the film is reduced, so that the film is liable to be stretched by a decrease in strength or external force, and the workability is undesirably reduced. On the other hand, when the plane orientation coefficient exceeds 0.18, unevenness of physical properties in the width direction of the film, whitening, and the like occur, which is not preferable.

It is necessary that the polyester film of the present invention has a birefringence (Δn) of -0.04 to -0.005, preferably -0.03 to -0.01. Here, the birefringence (Δn) is obtained by Δn = Nx (refractive index in the vertical direction) −Ny (refractive index in the horizontal direction). Δ
The fact that n is minus (-) indicates that the orientation in the film width direction is stronger than in the longitudinal direction. Birefringence is -0.
If it is larger than 005, the tensile strength in the width direction at the time of vapor deposition processing and lamination decreases, which is not preferable. Also, -0.
If it is less than 04, the orientation in the width direction becomes too strong as compared to the orientation in the longitudinal direction. As a result, the balance between the orientation in the longitudinal direction and the orientation in the width direction is unduly deteriorated, and the flatness such as uneven thickness is deteriorated. .

In the polyester film of the present invention, the refractive index in the film thickness direction is 1.49 to 1.505.
And more preferably 1.491 to
1.5. If the refractive index in the thickness direction is less than 1.49, a trouble at the time of processing such as cleavage of the film occurs, which is not preferable. On the other hand, if it exceeds 1.505, processing characteristics and printability deteriorate, which is not preferable.

In the polyester film of the present invention,
The center line average roughness (Ra) of at least one side is 0.005
To 0.03 μm, preferably 0.008 to 0.025, more preferably 0.01 to
0.02. If the center line average roughness (Ra) exceeds 0.03, pinholes are likely to be generated during the deposition, and the slipperiness is too high, and the handling properties are deteriorated. On the other hand, if it is less than 0.005, the slipperiness of the film is reduced, and the winding properties and processability are undesirably reduced.

In the present invention, a composite polyester film composed of at least two or more layers and having a center line average roughness (RaVM) of at least 0.005 to achieve both barrier properties, workability and handling properties. 0.03μ
m, difference from center line average roughness (RaNVM) of non-deposited surface (Δ
(Ra = RaNVM-RaVM) is preferably 0.003 μm or more. More preferably, the center line average roughness (RaVM) of the deposition surface is 0.005 to 0.025 μm, and the difference from the center line average roughness (RaNVM) of the non-deposition surface (ΔRa = Ra)
NVM-RaVM) is 0.005 μm or more. Center line average roughness (RaVM) of the deposition surface is 0.005 to 0.03 μm
, The excellent barrier property, ΔRa is 0.00
When the thickness is 3 μm or more, good film handling properties (slidability) and further excellent workability can be obtained. The center line average roughness (RaNVM) of the non-evaporated surface is 0.008 to 0.05 μm, more preferably 0.008 to 0.05 μm.
It is preferably from 1 to 0.03. If the center line average roughness (RaNVM) of the non-deposited surface exceeds 0.05, the slip characteristics are too high, and the deposition characteristics and workability such as the handling characteristics are deteriorated.

The particles contained in the polyester of the present invention are not particularly limited as long as they are inert to the polyester, but are arbitrarily selected from internal particles and external particles such as inorganic particles and / or organic particles. Particles are preferably 0.01 to 10% by weight, more preferably 0.02 to 1% by weight.
% By weight. The average particle diameter of the contained particles is preferably 0.001 to 10 μm, and more preferably 0.01 to 2 μm. It is not preferable to use particles having an average particle diameter of more than 10 μm because defects in the film are likely to occur. As inorganic and / or organic particles, for example, wet and dry silicas,
Colloidal silica, aluminum silicate, titanium oxide, calcium carbonate, calcium phosphate, barium sulfate, alumina,
Inorganic particles such as mica, kaolin, and clay, and organic particles containing styrene, silicone, acrylic acid, and the like as components can be used. Of these, inorganic particles such as wet and dry silica, colloidal silica, aluminum silicate, alumina, and calcium carbonate are preferred. Two or more of these internal particles, inorganic particles and / or organic particles may be used in combination.

In the present invention, the heat shrinkage at 150 ° C. for 30 minutes is 0.5 to 2.0% in the longitudinal direction of the film and − in the width direction.
It is preferably 1.2 to 0.5%, more preferably 1 to 2% in the longitudinal direction of the film, and -1 to 0% in the width direction. When the heat shrinkage ratio is more than 2% in the longitudinal direction of the film and more than 0.5% in the width direction, or less than -1.2% in the width direction, during the process of applying an external force such as vapor deposition, lamination, and printing process. The dimensional change is undesirably large.
Here, a minus (-) value of the heat shrinkage indicates elongation.

In the present invention, the breaking strength in the longitudinal and width directions of the film is preferably from 200 to 350 MPa, more preferably from 230 to 330 MPa. If the breaking strength is less than 200 MPa, the film strength is reduced, and the processability and the strength after bag making are inferior. On the other hand, if the breaking strength exceeds 350 MPa, the flexibility of the film during processing is undesirably reduced.

In the present invention, the elongation at break in the width direction of the film is 50 to 120%, and the (elongation at break in the longitudinal direction / elongation at break in the width direction) is 1.2 to 2. It is preferable, but not particularly limited, from the viewpoint of developing appropriate tensile strength in the direction and improving the vapor deposition property.

The surface of the film of the present invention may be subjected to various surface treatments, that is, a low-temperature plasma treatment, a corona discharge treatment, etc., prior to the vapor deposition.

Next, the manufacturing method of the present invention will be described, but the present invention is not necessarily limited thereto.

Polyethylene terephthalate (PE) having an intrinsic viscosity of 0.64 dl / g containing 0.05 wt% of inorganic particles (for example, wet-processed silica particles having an average particle diameter of 1.2 μm)
After drying T) according to a conventional method, it is melt-extruded, and the extruded sheet-like melt is cooled and solidified on a cooling drum to prepare a non-oriented PET film. 80 ° C ~ 1
It is stretched 2.0 to 5.0 times in the longitudinal direction while heating to 30 ° C. to obtain a uniaxially oriented PET film. Further, the film is guided into a tenter heated to 90 ° C. to 140 ° C. while being gripped with clips, stretched 2.5 to 6.0 times in the width direction, and continuously in a heat treatment zone at 160 ° C. to 250 ° C. At 1
Heat treatment for 10 to 10 seconds. During this heat treatment, a relaxation treatment of 0 to 12% may be performed as necessary.

The obtained film was subjected to vapor deposition using a continuous vacuum vapor deposition machine to obtain a polyester film for transparent vapor deposition having an aluminum oxide or silicon oxide vapor deposited layer formed thereon.

[0033]

[Method for Measuring Physical Properties and Method for Evaluating Effects] Methods for measuring physical properties and methods for evaluating effects in the present invention are as follows.

(1) Melting point, melting of the film The sub-peak film was measured with a differential scanning calorimeter (Darkin Elmer Co., Ltd.).
(SC-2 type) at a heating rate of 10 ° C./min to determine the melting peak temperature (melting point). In addition, a sub-peak temperature generated by the transformation of the pseudo crystal, which is generated at the time of this measurement, is defined as Ts. Ts appears as a history of the heat treatment temperature during the film forming process. The unit is both ° C.

(2) Refractive Index, Birefringence, Plane Orientation Coefficient Measured with an Abbe refractometer using sodium D line (wavelength 589 nm) as a light source. The plane orientation coefficient fn = (Nx + Ny) / 2-Nz obtained from the refractive indexes (Nx, Ny, Nz) in the longitudinal direction, the width direction, and the thickness direction was calculated and obtained.
The birefringence (Δn) was obtained by calculating Δn = Nx−Ny.
The measurement measured the vapor deposition surface.

(3) Center Line Average Roughness (Ra) A high-precision thin film step measuring device ET-10 manufactured by Kosaka Laboratory Co., Ltd.
It measured using. The measurement conditions are as follows.
The value was taken as the average value of 0 measurements.

・ Stylus tip radius: 0.5 μm ・ Stylus load: 5 mg ・ Measurement length: 1 mm ・ Cutoff: 0.08 mm For details of the definition of detailed parameters, see, for example, “Surface Roughness” by Jiro Nara Measurement and Evaluation Methods ”(Tokyo Gijutsu Center, 1983).

(4) Heat Shrinkage The film sample was cut to a length of 200 mm, the film was cut to a length of 10 mm, the film sample was hung in the length direction, and a load of 1 g was applied in the length direction to generate hot air at 150 ° C. After heating for 30 minutes, the length between the marked lines was measured, and the shrinkage of the film was expressed as a percentage relative to the original size.

(5) Breaking strength, elongation Using a “tensilon” (tensile tester), a tensile speed of 300 mm / min, a width of 10 mm, and a sample length of 100 m
The breaking strength and breaking elongation were measured as m.

(6) Oxygen Permeability According to ASTM-D3985, the oxygen permeability was measured at 20 ° C. and 0% RH using an oxygen permeability measuring device “OX-TRAN” 100 manufactured by Modern Control.

(7) Water vapor transmission rate “PERMAT”, a water vapor transmission rate meter manufactured by Modern Control Co., Ltd.
The measurement was performed using RAN "-W1A under the conditions of 40 ° C. and 90% RH.

(8) Handling properties Handling properties of the film during vapor deposition and processing (eg, slipperiness)
Was judged as ×. If it is good and there is no problem, it is ○.

[0043]

Next, the present invention will be described with reference to examples, but is not necessarily limited thereto.

Example 1 0.01% by weight of wet-processed silica particles having a particle diameter of 1.2 μm
Polyethylene terephthalate contained (melting point 256 ° C)
After sufficiently drying the pellet (intrinsic viscosity 0.64 dl / g) under vacuum, it was supplied to an extruder and melt-extruded at 280 ° C., and was wound around a cooling drum having a surface temperature of 25 ° C. to be cooled and solidified. In order to improve the adhesion between the sheet and the surface of the cooling drum during this time, a wire electrode is arranged
A DC voltage of 000 V was applied. The unstretched PET film (carboxyl end group: 32 equivalents / ton) thus obtained was heated to 105 ° C and stretched 3.1 times in the longitudinal direction.
This was a uniaxially stretched film. The PET film is guided into a tenter heated to 100 ° C. by grasping a flip, stretched 4.0 times in the width direction continuously in a zone heated to 110 ° C., and further heated under an atmosphere of 238 ° C. for 5 seconds. Was applied to obtain a polyester film having a film thickness of 12 μm. Further, the film was subjected to vapor deposition to obtain a transparent vapor-deposited film on which a silicon oxide film (thickness: 45 nm) was laminated. As shown in Tables 1 and 2, it can be seen that excellent barrier properties are exhibited.

Examples 2 to 7 The film forming conditions of Example 1 were changed by adding the polyester and particles shown in Table 1, respectively.
m was obtained. Vapor deposition was performed in the same manner as in Example 1 to obtain a transparent vapor-deposited film on which a silicon oxide film (44 nm in thickness) was formed. As shown in Table 2, excellent characteristics were exhibited.

Example 8 Separate polyesters were melted from an extruder I (main layer) and an extruder II (sublayer), and a main layer / sublayer (lamination ratio: 8) was obtained immediately before the die.
/ 1), and the stretching conditions of Example 1 were changed to obtain a laminated biaxially stretched polyester film having the properties shown in Table 1. The film is subjected to vapor deposition to form an aluminum oxide film (film thickness 45).
(nm) were obtained, and as shown in Tables 1 and 2, excellent properties were obtained.

Comparative Examples 1 to 4 Films shown in Table 1 were obtained in the same manner as in Example 1 except that the film forming conditions of Example 1 were changed. Furthermore, the film is subjected to vapor deposition,
A transparent vapor-deposited film on which a silicon oxide film (45 nm) was laminated was obtained. As shown in Tables 1 and 2, the gas barrier properties were poor.

[0048]

[Table 1]

[Table 2]

[0049]

INDUSTRIAL APPLICABILITY The present invention is suitable for obtaining a polyester film for vapor deposition which exhibits excellent oxygen and water vapor gas barrier properties of a transparent polyester film for vapor deposition, and can be widely used as food packaging.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI B29L 9:00 C08L 67:02

Claims (10)

[Claims] 1. A biaxially stretched polyester film containing a polyester having a melting point of 250 to 280 ° C. as a main component,
The melting sub-peak (Ts) of the film is 210 to 245
° C, the plane orientation coefficient is 0.155 to 0.18, the birefringence (Δn) of the film is -0.04 to -0.005, and the center line average roughness (Ra) of at least one surface is 0.005 to 0.5. 03
A polyester film for transparent evaporation characterized by having a thickness of μm. 2. The thermal shrinkage at 150 ° C. for 30 minutes is 0.5 to 2.0% in the longitudinal direction of the film and −1.2 to 0.2 in the width direction.
The polyester film for transparent vapor deposition according to claim 1, wherein the content is 5%. 3. The film has a melting sub-peak (Ts) of 2
The polyester film for transparent vapor deposition according to claim 1, wherein the temperature is 25 to 240 ° C. 4. 4. A film having a refractive index in the thickness direction of 1.490.
The polyester film for transparent vapor deposition according to any one of claims 1 to 3, wherein 5. The polyester film for transparent vapor deposition according to claim 1, wherein the breaking strength in the longitudinal direction and the width direction of the film is from 200 to 350 MPa. 6. The film has a birefringence (Δn) of −0.03.
~ -0.01, the center line average roughness (Ra) of one side is 0.0
1 to 0.025 μm.
5. The polyester film for transparent vapor deposition according to any one of 5. 7. The film has a melting sub-peak (Ts) of 2
The polyester film for transparent vapor deposition according to any one of claims 1 to 6, wherein the temperature is 30 to 238 ° C. 8. A plane orientation coefficient of 0.1625 to 0.175.
The polyester film for transparent vapor deposition according to any one of claims 1 to 7, wherein 9. A composite polyester film composed of at least two or more layers, wherein the center line average roughness (RaVM) of the deposited surface is 0.005 to 0.03 μm, and the center line average roughness of the non-deposited surface (RaVM) is RaNVM) (ΔRa = RaNVM)
The polyester film for transparent vapor deposition according to any one of claims 1 to 8, wherein (RaVM) is 0.003 µm or more. 10. A melting point of at least one side of 210 to 260.
The polyester film for transparent vapor deposition according to claim 9, wherein a polyester at a temperature of at least 10 ° C. is laminated.