JPH0222048A - Composite polyester film - Google Patents

Abstract

PURPOSE:To obtain a composite film enhanced in the adhesive strength with a vapor deposition film and reduced in electrostatic capacity change rate by superposing a polymer film on the single surface of a polyester film and further superposing a metal layer thereon by vapor deposition. CONSTITUTION:In a composite polyester film mainly used as an industrial material, a film composed of poly(1,4-cyclohexylene dimethylene terephthalate) containing 50% or more, pref., 70% or more of a cyclohexane dimethanol unit is provided to the single surface or both surfaces of a polyester film and a metal layer composed of aluminium or zinc is further provided on this polymer film by vapor deposition. By this method, the adhesion, orientation and growth state of the vapor deposition film becomes dense and the adhesive strength thereof is enhanced and an electrostatic capacity change rate is reduced.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a composite polyester film.

More specifically, the present invention mainly relates to composite polyester films for industrial materials.

[Prior Art] Conventionally, composite polyester films include films in which a polyethylene terephthalate film is composited with a film made by copolymerizing polyethylene isophthalate and polyethylene terephthalate on one side, and a vapor-deposited metal is provided on one side, and a film is disclosed in Japanese Patent Publication No. 58-12153. As shown, composite films of films having a specific heat of crystal fusion are known.

[Problems to be Solved by the Invention] However, the above-mentioned conventional composite polyester film has problems in that the adhesion of the deposited film is poor and the rate of change in capacitance is large.

An object of the present invention is to improve such problems and provide a composite polyester film with excellent adhesion of a deposited film and excellent capacitance change rate.

[Means for Solving the Problems] The present invention provides a polyester film with a poly(1,4-cyclohexylene dimethylene terephthalate) film provided on at least one side thereof, and a poly(1,4-cyclohexylene dimethylene terephthalate) film. It is characterized by a composite polyester film with vapor-deposited metal on its surface.

The polyester film in the present invention is a film made of a polymer or copolymer in which 50 mol% or more, preferably 75 mol% or more of the polymer chains are connected by ester bonds, and includes polyethylene terephthalate,
Typical examples include polybutylene terephthalate, polyethylene naphthalate, and polyethylene bis(2-chlorophenoxy)ethane-4°4'-dicarboxylate film, but polyethylene terephthalate film is particularly preferred in the present invention. The polyethylene terephthalate mentioned here is one in which ethylene terephthalate units account for 80 mol% or more. In other words,
Other molecular units such as ethylene isophthalate, butylene terephthalate, ethylene adibet, alkylene glycol, polyalkylene glycol, etc. may be copolymerized within a range not exceeding 20 mol %. This polyethylene terephthalate may contain known additives, such as inorganic fine particles and color inhibitors.

The polyester film of the present invention is obtained by biaxially stretching and orienting the above-mentioned polyester film.

The poly(1,4-cyclohexylene dimethylene terephthalate) [hereinafter abbreviated as PCT] film of the present invention is a poly(1,4-cyclohexylene dimethylene terephthalate) [hereinafter abbreviated as PCT] film in which cyclohexane dimetatool units are bonded by ester bonds consisting of 50 mol% or more, preferably 70 mol% or more. It is a film made of a copolymer or mixture of The diol component of the cyclohexane dimetatool unit is:
Typical examples of the acid component include terephthalic acid, isophthalic acid, naphthalene dicarboxylic acid, and the like, with 70 mol% or more of terephthalic acid being particularly preferred.

Further, the melting point of the polymer is preferably 245°C or higher, more preferably 255°C or higher. Known additives, such as inorganic fine particles and anti-coloring agents, may be added to this polymer. Note that the average surface roughness of the PCT film of the present invention is preferably 0.005 to 0.05μ.
m1 is more preferably 0.01 to 0.04 μm. In addition, the external particle content in the film has an average particle size of 0.1 to
It is preferable that particles having a size of 0.6 μm are contained in an amount of 0.05 to 0.5%.

The vapor-deposited metal of the present invention is not particularly limited in type, and may be a low melting point metal such as aluminum, zinc, copper, or tin, or a high melting point metal such as chromium, nickel, iron, or titanium. The thickness of the film to be vapor-deposited is preferably in the range of about 0.02 to 0.2 μm.

The composite polyester film used in the present invention is a composite of a PCT film in which a vapor-deposited metal is provided on one or both sides of the above-mentioned polyester film.The vapor-deposited metal may be provided on only one side.Composite The thickness of each layer of the polyester film is preferably 1 to 25 μm for the polyester film layer, and 0 to 25 μm for the PC lower film layer.
．． The thickness is preferably 0.5 to 3 μm, more preferably 0.5 to 3 μm. If the thickness of the PC film layer is smaller than the above range, the rate of change in capacitance under humidity resistance will increase, and if it is larger than the above range, the polymer film may develop creases or its mechanical properties may deteriorate. do.

Next, the method for manufacturing the composite polyester film of the present invention will be explained.

Pellets of polyethylene terephthalate (hereinafter abbreviated as PET) and PCH were each fed to separate extruders.
Melt extrusion was carried out at 85° C. and the respective melts were combined in a T-shaped nozzle to form a sheet consisting of two layers under PET/PC. This sheet was heated to 100'C, stretched 3.2 times in the longitudinal direction, cooled once, heated again to 110'C, stretched 3.3 times in the width direction, and kept under tension for 200
Heat treatment in hot air at 'C for 5 seconds.

The heat-treated film is slowly cooled to room temperature to form the PET layer 10.
A composite polyester film with 5 μm and 1 μm PCT layer is obtained. Aluminum is vapor-deposited to a thickness of 0.05 μm on the surface of the PCT layer of this composite polyester film according to a conventional method.

The composite polyester film produced in this way is used for industrial material applications such as capacitors and packaging.

[Effect of the invention] The present invention provides a polyester/PCT composite film
It is presumed that because the T layer was vapor-deposited, the deposition of the vapor-deposited film, the orientation of the vapor-deposited film, and the growth state of the vapor-deposited film were different from those in the case of vapor-depositing on the polyester layer, and were denser. This seems to be the reason why the adhesion of the deposited film improved and the rate of change in capacitance decreased.

Furthermore, since it is a composite film with a polyester layer, it has the advantage that other properties can be improved while maintaining the mechanical properties of the polyester layer, making it suitable for industrial material applications.

[Method for measuring characteristics and evaluating effectiveness] (1) Adhesion of vapor deposited film Fill water in a constant temperature bath, make it warm to 65°C, soak the vapor deposited film in it for 15 minutes, and observe the degree of disappearance of the vapor deposited film. did. ○ means that there is no change in the deposited film, △ means that there is a slight change
, those in which the deposited film has almost disappeared are marked as ×, and 3
Adhesion was evaluated in stages.

(2) Capacitance change rate A capacitor element (1.5 μF) was made from the deposited film, and the capacitance change rate (ΔC
/C) (%) was measured.

(3> Mechanical Properties Breaking strength and elongation were determined by the method of JIS C2318-72. Young's modulus was also calculated from the elongation and stress.

"Examples" Hereinafter, embodiments of the present invention will be described based on Examples.

Example 1 PET pellets (melting point 260'C1 average particle size O0,3
85 mol% of terephthalic acid, 15 mol% of isophthalic acid,
Cyclohexane dimetatool 100 as diol component
% copolymerized PCT (melting point 270'C, average particle size 0.
Pellets of 4 μm dry silica (containing 0.15% silica) were each fed into a separate extruder and melt extruded at 290'C, and each melt was combined in a T-type nozzle to form a layer under the surface of the PET layer. A sheet consisting of two layers was made. This sheet is 100
3.5 times in the longitudinal direction at 'C and 3.5 times in the width direction at 110°C.
Stretched 5 times and heat treated at 200'C for 5 seconds to form PET layer 9
A composite film with a PCT layer of 1 μm and a PCT layer of 1 μm was obtained. The surface roughness of the PCT film was 0.03 μm. Aluminum is applied to the surface of the PCT layer of this composite film to a thickness of 0.05 μm.
It was deposited to a thickness of .

Table 1 shows the evaluation results of the vapor-deposited composite film.
Good results were shown in both the adhesion of the deposited film and the rate of change in capacitance.

Comparative Example 1 PET pellets (melting point 260°C1 average particle size 0°3μ
containing 0.1% by weight of dry silica) and isophthale 1
PET copolymerized with 117.5 mol% (melting point 210°C
> pellets were each fed to separate extruders and heated at 280'C.
A two-layer sheet was made by melt extrusion. This sheet is 90
3.5 times in the longitudinal direction at 'C, 3.5 times in the width direction at 100°C.
Stretched 5 times and heat treated at 180°C for 5 seconds to form PET layer 9
A composite film having a thickness of 1 μm and a copolymerized PET layer of 1 μm was obtained. Aluminum was deposited on the surface of the copolymerized PET layer of this composite film to a thickness of 0.05 μm.

The evaluation results of the vapor-deposited composite film are shown in Table 1, and both the adhesion and the rate of change in capacitance were worse than in Example 1.

Comparative Example 2 Only the pellet under PE of Example 1 was melt extruded at 280'C to make a single layer sheet. This sheet was stretched 3.5 times in the longitudinal direction at 90'C and 3.5 times in the width direction at 95°C, and heat treated at 200'C for 5 seconds to obtain a 10 μm single layer film. The aluminum of this film is 0.05μm
It was deposited to a thickness of .

The evaluation results of the deposited film are shown in Table 1, and both the adhesion and the rate of change in capacitance were poor.

Comparative Example 3 The raw material of Example 1 (however, the PCT copolymer pellets did not contain dry silica) was stretched in the same manner, and PE
A two-layer composite film having a T layer of 2 μm and a PCT layer of 8 μm was obtained. The surface roughness of the PCT film was 0.003 μm.

Aluminum was deposited on this film to a thickness of 0.05 μm.

Table 1 shows the evaluation results of the vapor-deposited composite film.
Both adhesion and capacitance change rate were worse than Example 1, mechanical properties were inferior, and it was difficult to use.

Table 1

Claims (1)

[Claims] At least one side of the polyester film is coated with poly(1,4
- cyclohexylene dimethylene terephthalate) film, and a vapor-deposited metal is provided on the surface of the poly(1,4-cyclohexylene dimethylene terephthalate).