JPH02266937A - Laminated film - Google Patents

Abstract

PURPOSE:To enhance pinhole resistance, the adhesion strength of a deposited film and soldering resistance by forming a polyester film from 1,4- polycyclohexylene dimethylene terephthalate and specifying the thickness of a polyolefin support film. CONSTITUTION:A laminated film is constituted by laminating a polyester film having a thickness of 0.2-1.5mum to the single surface or both surfaces of a polyolefin support film and the polyester film is composed of 1, 4- polycyclohexylene dimethylene terephthalate and the thickness of the polyethylene support film is set to a range of 5-100 times that of the polyester film. Further, the polyolefin film is a non-oriented, uniaxially oriented or biaxially oriented film composed of a polymer or copolymer of olefin and, as polyolefin, a propylene copolymer having an m.p. of 100-150 deg.C is especially pref. This laminated film can be used in a dielectric for a condenser or a thermal transfer ribbon.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to a thin polyester film having a support, and more specifically, in the laminated film, the ultrathin polyester film is smoother than the polyolefin support. The present invention relates to a polyester film that can be easily peeled off, has good solder resistance, has a high holding power for a vapor-deposited aluminum layer, and is excellent as a capacitor dielectric.

[Prior Art] In recent years, as electric or electronic circuits have become smaller, capacitors have become smaller, and dielectric layer films have become thinner. As such ultra-thin films, for example, Japanese Patent Application Laid-open No. 58-5526, Japanese Patent Application Laid-open No. 58
-13252θ, JP-A-58-136417, etc., there are known methods in which different types of polymers are stretched in a laminated state to form a laminated film, and then one side is peeled off and used as an ultra-thin film. ing.

[Problems to be solved by the invention] Such conventional laminated films are easy to tear when peeled,
Also, pinholes are likely to be formed. Furthermore, since the vapor deposited film has weak adhesion and poor solder resistance, there is a problem in that the capacitor properties of the obtained film are significantly inferior.

The present invention solves the above-mentioned drawbacks and provides a laminated film having a thin polyester layer that is hard to tear and has excellent pinhole resistance, strong adhesion of the vapor deposited film, and high solder resistance, making it excellent as a capacitor film. That is the purpose.

[Means for Solving the Problems] In order to achieve the above object, the present invention has the following configuration, that is, a polyester film with a thickness of 0.2 to 1.5 μm is composited on one or both sides of a polyolefin support film. In the laminated film, the polyester film is made of 1,4-polycyclohexylene dimethylene terephthalate, and the thickness of the polyolefin support film is 5 to 100 times the thickness of the polyester film.
It is made of a laminated film characterized by being within a double range.

The polyolefin film in the present invention refers to a non-oriented, -axially oriented or biaxially oriented film made of an olefin polymer or copolymer, and the thickness is not particularly limited, but a film of 1 to 10 μm is suitable for the present invention. is suitable.

Typical examples of polyolefins include low density polyethylene, medium density polyethylene, high density polyethylene, linear low density polyethylene, polypropylene, polybutene-1,
Poly-4-methyl-pentene-1, copolymers and mixtures thereof can be mentioned, but preferred in the present invention is a propylene copolymer (hereinafter referred to as PPC) having a melting point of 100 to 160°C. , furthermore, among these, the melting point is 1
A propylene copolymer having a temperature of 00 to 155°C is preferred.

This copolymer is preferably a copolymer of 80 to 97 mol% of propylene and 3 to 20 mol% of an olefin other than propylene. Furthermore, it is preferable to add various known mold release agents such as silicone, petroleum resin, terpene resin, higher fatty acid waxes, etc. to the polyolefin layer of the present invention. Furthermore, there is no problem in adding various known additives such as antioxidants, antistatic agents, coloring pigments, antiblocking agents, and ultraviolet absorbers.

The polyester of the present invention is 1,4-polycyclohexylene dimethylene terephthalate (hereinafter sometimes referred to as PCT), which mainly contains 1゜4-cyclohexanedimethylene terephthalate as a glycol component and mainly terephthalic acid as a dicarboxylic acid. It is polyester as a component.

90 mol% or more of the glycol component, more preferably 95 mol%
．． It is preferable that 1,4-cyclohexane dimetatool accounts for at least 80% of the acid component in terms of improving heat resistance, increasing the adhesion of the deposited film, reducing pinhole defects, and improving capacitor properties. For the same reason, it is preferable that terephthalic acid accounts for at least 90 mol%, more preferably at least 95 mol%, and even more preferably at least 95 mol%. However, as long as it does not affect the effects of the present invention, it may contain a small amount, preferably 10 mol% or less, of other glycol components, and may also contain a small amount, preferably 10 mol% or less, of other acid components. It's okay to stay.

In addition to the above-mentioned PCT, the polyester may optionally contain additives and inorganic particles that are normally added to polyesters, such as lubricants, stabilizers, and antistatic agents. Further, other polymers may be blended within a range that does not adversely affect the present invention.

The polyester film of the present invention is preferably biaxially stretched and substantially bidirectionally oriented from the viewpoint of heat resistance and durability.

The thickness of the polyester layer of the present invention is 0.2~1゜5μm1
Preferably it is 0.3 to 1.0 μm.

If the thickness is less than 0.2 μm, it is not preferable because there is a problem of tearing during film formation or peeling.

In addition, when the thickness is more than 1.5 μm, preferably 1.0 μm, the workability and film formability are good even when the film is alone.
This is not preferred since it is not necessary to form a laminated film as in the present invention.

In addition, if the thickness of the support film is less than 5 times the thickness of the polyester film, it will not function as a support, and if the thickness exceeds 100 times, the thickness of the laminated film will be too thick and there will be a lot of loss. Practically unfavorable.

The laminate film of the present invention is a laminate of the polyolefin layer and the polyester layer, and the laminate structure is not particularly limited, but three layers of polyester/PPC/polyester are preferred. Further, in the case of a three-layer structure of polyester/PPC/polyester, the thickness of the polyester films on both sides may be the same or may be different within the scope of the present invention.

PCT constituting the polyester layer in the present invention can be manufactured by a conventionally known polyester manufacturing method. For example, it can be produced by a direct esterification method of terephthalic acid and 1,4-cyclohexane dimetatool, or by a transesterification method of dimethyl terephthalate and 1,4-cyclohexanedimetatool.

The PCT produced in this manner may be copolymerized with a third component in a small proportion as described above.

Next, a specific example of the method for producing a laminated film of the present invention will be explained. However, it is not limited to this example.

First, a polyester resin and a polyolefin resin are each supplied to separate extruders, melted, and merged in a die to form a sheet.The sheet is wound around a metal roll at approximately 60°C, cooled, and unstretched. A laminated sheet of

Next, the laminated sheet is stretched 3.0 to 4.5 times in the longitudinal direction at a temperature of 80 to 120°C and 3.0 to 5.5 times in the transverse direction at a temperature of 90 to 120°C, then 180-25
The laminated film of the present invention can be obtained by heat treatment at a temperature of 0°C.

For stretching the laminated film, either a sequential biaxial stretching method or a simultaneous two-wheel stretching method can be applied.

The thus obtained laminated film is used by subjecting the polyester surface to vapor deposition, coating, lamination, etc., and then peeling and removing the PPC layer. This peeling method is not particularly limited, but continuous peeling is easy if the laminated film is nipped between a set of nip rolls and peeled with the polyester film running along the surface of one of the rolls.

Note that the above-mentioned vapor deposition etc. may be performed after peeling.

The laminated film of the present invention can be used in many applications such as dielectrics for capacitors and ribbons for thermal transfer.

[Measurement method] The measurement method and evaluation criteria for physical properties, etc. used in the present invention are as follows.

(1) Capacitance of capacitor element using automatic capacitance bridge, 25℃, 1kHz
Capacitance was measured at z.

■Insulation failure rate of capacitor elements A voltage of DC 80V per 1 μm of dielectric film thickness was applied instantaneously to 100 capacitor elements, and the ratio of elements that suffered dielectric breakdown was defined as the insulation failure rate.

(3) Solder heat resistance of capacitor The initial capacity was evaluated by the rate of change in capacity after being immersed in a 230°C solder bath for 10 seconds. It goes without saying that the smaller the value, the better.

4) Adhesion of vapor deposited film The vapor deposited film was immersed in 65° C. hot water in a constant temperature bath for 15 minutes, the degree of disappearance of the vapor deposited film was observed, and the adhesion was evaluated in three stages.

0: No change in the deposited film Δ: Slight change ×: Almost all the deposited film has disappeared ■ Peel off the pinhole laminated film using a slitter, and place the peeled polyester film on a white film. Layer them so that there are no wrinkles. Magic ink was sprayed on the entire surface of a 1 m 2 area, and the number of spots formed on the white film was defined as a pinhole.

O: No pinholes △: 1 to 5 pinholes ×: 6 or more pinholes [Effects of the invention] By keeping the structure of the laminated film within the scope of the present invention, the ultra-thin polyester film layer is pin-resistant. We were able to create a polyester laminated film with excellent hole properties, strong adhesion of the deposited film, and high solder resistance (and excellent performance as a capacitor film).

[Example] Hereinafter, embodiments of the present invention will be described based on Examples.

Example 1 (1) Manufacture of vapor deposited laminated film The following two types of raw materials were prepared.

ppc: melting point 130°C. A propylene/ethylene random copolymer with an ethylene content of 6% by weight. Contains 0.03% of Toshi Silicone (SH3746) as a mold release agent.

PCT: Copolymerized with 95 mol% of terephthalic acid, 5 mol% of isophthalic acid as an acid component, and 100% of cyclohexane dimetatool as a diol component.

Melting point: 284°C. Average particle size 0.5μm wet silica of 0.5% and average 0.075 for particles with a particle size of 1°5μm Contains %.

These two types of raw materials are supplied to separate extruders and melt-extruded at 295°C, and the respective melts are combined in a T-shaped nozzle to form a three-layer structure of PCT/PPC/PCT.
It was wrapped around a hot water drum at ℃ and cooled and solidified to form a three-layer laminated sheet.

After heating this sheet to 105℃,
．． It was stretched 5 times and immediately cooled. Then again at 105℃
The film was heated to 230° C. and stretched 3.degree. 5 times in the width direction, then heat treated at 230.degree. C. for 6 seconds while maintaining tension, then relaxed by 5%, slowly cooled to room temperature, and rolled up.

In this way, a laminated film was obtained in which the thickness of the PCT layers on both sides was 0.5 μm, the thickness of the PPC layer at the center was 5 μm, and the total thickness was 6 μm.

This film roll was applied to a vacuum evaporator with a width of 500 mrn, and aluminum was applied to the PCT layer surface on both sides with a surface resistance of 2.
Both sides were deposited to a thickness of Ω/mouth. At this time, the vapor deposition portion 8.
A margin portion was formed in the longitudinal direction at a ratio of 1°Qmm to 0mm.

The vapor-deposited laminated film was passed through a micro-slitter, and blades were inserted into the center of the vapor-deposited part and the center of the margin part, so that the film width was 4.5 mm and the inner margin width was 0.5 mm. It was made into a 5 nm tape and wound up in a laminated state.

■Manufacture of capacitor elements A pair of vapor-deposited laminated film reels are placed on a winder, one vapor-deposited PCT film is peeled off from each reel, and the two films are wound together, and further pressed to produce a capacitor element. Ta. Both ends of this element were sprayed with metallized silicon to form external electrodes, lead wires were attached to this, and the element was covered with powder epoxy and evaluated as a capacitor with a capacitance of 1°0 μF.

(3) Evaluation The evaluation results of the obtained capacitors, vapor deposited films, etc. are shown in Table 1.

Example 2 The PPC pellets of Example 1 and PCT had 80 mol% of terephthalic acid and 20 mol% of isophthalic acid as acid components, and 100% of cyclohexane dimetatool as a diol component.
(melting point: 268°C) at 290°C.
A three-layer laminated sheet was made by melt extrusion. This sheet is 95
The film was stretched 3.5 times in the longitudinal direction at 100°C and 3.5 times in the transverse direction at 100°C, then heat treated at 230°C for 6 seconds to relax 5%, and then wound up.

The thickness of the PCT layers on both sides is 0.5 μm each.1 Center PPC
A laminated film with a layer thickness of 5 μm and a total of 6 μm was obtained.

Evaluation was made in the same manner as in Example 1.

Comparative Example I PPC pellets and PCT copolymerized with 70 mol% terephthalic acid and 30 mol% isophthalic acid as the acid component and 100% cyclohexane dimetatool as the diol component (melting point 260°C) were used. A film was formed in exactly the same manner as in Example 1 to obtain a three-layer laminated film.

Evaluation was made in the same manner as in Example 2.

Comparative Example 2 A pellet of PPC and PET (melting point 265° C.) were used instead of PCT, and the pellets were supplied to separate extruders, and a film was formed and evaluated in the same manner as in Example 2.

Claims (2)

[Claims] (1) A laminated film comprising a polyester film having a thickness of 0.2 to 1.5 μm on one or both sides of a polyolefin support film, wherein the polyester film is composed of 1,4-polycyclohexylene dimethylene terephthalate. , and the thickness of the polyolefin support film is 5 to 10 times the thickness of the polyester film.
A laminated film characterized by being in the range of 0 times. (2) Claim (1) characterized in that it is a laminated film for a capacitor formed by vapor deposition on the polyester film.
) The laminated film described in ).