JPH106393A - Biaxially stretched polyester film for vapor deposition of silicon oxide - Google Patents

Abstract

PROBLEM TO BE SOLVED: To uniformize the thickness of a vapor deposition film by proventing the generation of the slackening or wrinkles of a base material film on the cooling drum of a vapor deposition machine by using a polyester film having a specific range of a heat shrinkage factor. SOLUTION: A phenol/tetrachloroethane mixed solvent is used to extrude PET from a T-die in a molten state and the extrudate is cooled on a drum to obtain a non-stretched film. Succeedingly, this film is longitudinally stretched and subsequently laterally stretched to be thermally set to obtain a biaxially stretched film. Next, the obtained stretched film is supplied to a vacuum vapor deposition apparatus and SiOx is vapor-deposited on the film under heating by an electron beam heating system to obtain a film having a transparent SiOx film formed on its single surface. The dry heat shrinkage factors (160 deg.C×5min) in the longitudinal and lateral directions of the film are respectively 1.0-2.0% and 0.5-1/0%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a biaxially stretched polyester film used as a base material of a silicon oxide (SiOx) vapor-deposited film having excellent gas barrier properties, which is suitable for packaging, particularly as a food packaging film.

[0002]

2. Description of the Related Art Aluminum foil, aluminum vapor-deposited film, polyvinylidene chloride coated film and the like are used as gas barrier materials for packaging applications. Materials that generate such incineration residues and materials that generate chlorine gas during incineration, such as polyvinylidene chloride, have been reduced in use. Further, there is a problem that the contents of the aluminum foil and the aluminum vapor-deposited film cannot be seen, and that the heat treatment cannot be performed by a microwave oven. Under these circumstances, a transparent vapor-deposited film obtained by vacuum-depositing SiOx on a substrate film has a transparent vapor-deposited film, and the contents can be confirmed.
Because of its excellent water resistance, the gas barrier performance after retort sterilization treatment is less deteriorated, and it can be applied to a microwave oven.

In particular, polyethylene terephthalate (PET)
Polyester film represented by) has excellent properties such as heat resistance, dimensional stability, thickness uniformity, etc., is widely used as a base film for various metal vapor deposition films, and is also suitable for SiOx vapor deposition. Base film.

[0004]

However, when a polyester film is used for depositing SiOx, there is a problem that the gas barrier performance of the deposited film is not always sufficient and the gas barrier performance varies. Was.

[0005]

Means for Solving the Problems The present inventor has made intensive studies to solve the above-mentioned problems, and as a result, by using a polyester film having a specific range of heat shrinkage, a cooling drum of a vapor deposition machine is used. The sagging of the base film and the generation of wrinkles are prevented, the thickness of the deposited film becomes uniform, and the moderate thermal shrinkage of the base film makes the structure of the deposited film more dense, The inventors have found that the gas barrier performance is improved, and arrived at the present invention.

That is, the gist of the present invention is to provide a biaxially oriented film for vapor deposition of SiOx in which the dry heat shrinkage (160 ° C. × 5 minutes) in the longitudinal and transverse directions of the film is 1.0 to 2.0% and 0.5 to 1.0%, respectively. In the polyester film.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail. As the polyester in the present invention, PET is optimal, but as long as the effects of the present invention are not impaired, those obtained by copolymerizing other components, polybutylene terephthalate (PBT), polyethylene naphthalate (PEN)
) And polycyclohexylene dimethylene terephthalate (PCT).

The dry heat shrinkage of the polyester film of the present invention in the machine direction and the transverse direction at 160 ° C. × 5 minutes is respectively
It needs to be 1.0-2.0% and 0.5-1.0%. If the heat shrinkage is out of the above range, uniform
It becomes difficult to obtain a SiOx deposited film, and the gas barrier property of the deposited film is reduced.

[0009] The polyester film of the present invention can be produced by a known production method. For example, it can be manufactured by extruding PET into a sheet, stretching it sequentially or simultaneously in the longitudinal direction and width direction, and heat-setting. The biaxially stretched polyester film has a thickness of 5 to 200 μm, usually 9 to 50 μm.

When a transparent SiOx vapor-deposited film is produced by using the film of the present invention, SiOx is composed of Si, SiO ₂ , SiO ₂
The ratio is used as long as the gas barrier properties and transparency are not impaired, and within the range where the object of the present invention can be achieved, aluminum oxide, other metal oxides such as magnesium oxide are added. Is also good.

The thickness of the deposited SiOx film is not particularly limited, but is preferably 50 to 1,500 °. If the thickness is less than 50 mm, it is difficult to obtain sufficient gas barrier properties.
Exceeding not only is disadvantageous in terms of cost but also undesirably lowers flexibility.

As a method for forming the SiOx deposited film, a vacuum deposition method, an EB deposition method, a sputtering method, an ion plating method, or the like can be used as appropriate. However, the vacuum deposition method is the most preferable in terms of productivity and cost. preferable.

Further, a polyester film as a base material and SiOx
It is desirable to pre-treat the surface of the polyester film in order to improve the adhesion with the deposited film. As the pretreatment, a discharge treatment or a method of applying an anchor coat agent is generally used.

The SiOx vapor-deposited film using the film of the present invention can be laminated with another film such as a nylon film (ON) or a PET film, or provided with a heat seal property, such as polypropylene (CPP) or polyethylene (PE). ) Can be used after being laminated. Examples of the configuration of such a laminated film include vapor-deposited film / PE, vapor-deposited film / ON / CPP, PET / vapor-deposited film / CPP, and the like. As a lamination method,
Although there is no particular limitation, a method such as a dry lamination method or an extrusion lamination method is used.

Since the SiOx-deposited polyester film thus obtained has excellent gas barrier properties, it can be used as a food for retort foods such as spices, coffee, etc., which are required to have aroma-preserving properties, side dishes, etc. It can also be used for packaging, non-food packaging, or applications other than packaging.

[0016]

Next, the present invention will be described specifically with reference to examples. The evaluation methods used in the examples are as follows.

(1) Dry heat shrinkage rate A film cut into strips having a width of 1 cm and a length of 15 cm is marked with a mark of 10 cm in the longitudinal direction, and heated in a hot air dryer heated to 160 ° C. After processing for 5 minutes, the interval (cm) between the gauges after the processing was read and determined by the following equation. Dry heat shrinkage (%) = (10-length between gauges after treatment) x 100
/ 10 (2) Oxygen permeability According to ASTM D-3985, use an oxygen permeability measuring device (model OX-TRAN 100, manufactured by Modern Control) at 20 ° C and 10 ° C.
The oxygen permeability was measured under the condition of 0% RH. (3) Three-dimensional surface roughness According to JIS B-0601, maximum peak height using a stylus type surface roughness meter
SR _ma , 10-point average peak height SR _z , average roughness SR _a , and the number of peaks SP _c were measured.

EXAMPLE 1 Using a 6/4 mixed solvent of phenol / tetrachloroethane, PET having an intrinsic viscosity of 0.63 measured at 30 ° C. and T at 280 ° C.
Extrusion from a die, cooling on a 40 ° C drum, thickness
An unstretched film of 150 μm was obtained. Subsequently, the film was stretched 3.5 times in the machine direction (MD) at 90 ° C., then stretched 3.5 times in the transverse direction (TD) at 110 ° C., and then heat-set at 230 ° C. for 5 seconds to obtain a 12 μm thick An axially stretched film was obtained. The dry heat shrinkage of the obtained stretched film is 1.1% for MD, T
D was 0.9%. Next, the obtained stretched film is
99.9% pure SiOx is heated and evaporated by a 10kw electron beam heating method under a vacuum of 5 × 10 ^-5 Torr under a vacuum of 5 × 10 ^-5 Torr to form a 600 mm thick SiOx transparent film on one side of the film Obtained film was obtained. The three-dimensional surface roughness and oxygen permeability of the obtained vapor-deposited film were measured.
It was shown to.

Example 2 A 12 μm-thick biaxially stretched film was obtained in the same manner as in Example 1 except that the heat setting temperature was 235 ° C. The dry heat shrinkage of the obtained stretched film was as follows: MD: 1.0%, TD: 0.5
%Met. Table 1 shows the performance of the SiOx deposited film produced in the same manner as in Example 1.

Example 3, Comparative Examples 1 and 2 The procedure of Example 1 was repeated except that the heat setting temperature was changed.
As shown in Table 1, stretched films having different dry heat shrinkage rates were obtained. Table 1 shows the performance of the SiOx vapor-deposited film produced in the same manner as in Example 1 using each of the stretched films as the base film.

[0021]

[Table 1]

Example 4 A urethane-based adhesive (Dick Dry, manufactured by Dainippon Ink and Chemicals, Inc.) was applied to the vapor-deposited surface of the vapor-deposited film obtained in Example 1.
After applying 2 μm of a two-component adhesive in which LX-75 and KW-40 were mixed at a ratio of 5: 1, a low-density PE film having a thickness of 60 μm was laminated by a dry lamination method. Table 2 shows the results of measuring the oxygen permeability and the lamination strength of the obtained laminate film.

Comparative Example 3 A laminated film was prepared in the same manner as in Example 4 using the vapor-deposited film obtained in Comparative Example 1. Table 2 shows the results of measuring the oxygen permeability and the lamination strength of the obtained laminate film.

Comparative Example 4 A laminated film was prepared in the same manner as in Example 4 using the vapor-deposited film obtained in Comparative Example 2. Table 2 shows the results of measuring the oxygen permeability and the lamination strength of the obtained laminate film.

[0025]

[Table 2]

[0026]

According to the present invention, sagging and wrinkling of the film on the cooling drum of the vapor deposition machine are prevented, the film thickness of the SiOx vapor deposited film is uniform, and the structure of the vapor deposited film is dense gas barrier property. The present invention provides a biaxially stretched polyester film capable of obtaining a SiOx deposited film excellent in quality.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical display location B29L 7:00

Claims (1)

[Claims] 1. The film has a dry heat shrinkage in the longitudinal and transverse directions (160 ° C. × 5 minutes) of 1.0 to 2.0% and 0.5%, respectively.
A biaxially stretched polyester film for silicon oxide vapor deposition of up to 1.0%.