JPS60255410A - Preparation of extremely thin polyester film - Google Patents

Abstract

PURPOSE:To reduce the insulating defect of the titled film obtained by peeling off the same for a laminate film consisting of a polyolefin film and a polyester film, by preliminarily containing specific modified silicone oil in the polyolefin film of said laminate film. CONSTITUTION:In a laminate film consisting of a polyolefin film and a polyester film, modified silicone oil, {which is represented by formulae I -III [wherein Me is methyl, R1 is 1-20C hydrocarbon, R2 is H or 1-20C hydrocarbon, (x) is 1- 50, (y) is 2-50 and (n) is 1-5] and of which the modification ratio is pref. 45- 99% and the viscosity is pref. 100-10,000 centistokes} is preliminarily contained in the polyolefin film pref. in an amount of 0.05-0.5wt%. Then, said laminate film is peeled to obtain the objective film.

Description

[Detailed description of the invention] [Technical field of invention] The present invention particularly relates to ultrathin polyester films.

The present invention relates to a method for producing a polyester film having a thickness of 01 to 4 μm, more specifically, a thickness of 01 to 2 μm. Such a film is particularly suitable as a dielectric for a capacitor.

[Prior art and its drawbacks]

As a manufacturing method for ultra-thin polyester film.

Co-extruded and laminated polyester and polyolefin,
A method of peeling a polyester film from a laminated film obtained by stretching this film is disclosed in Japanese Patent Application Laid-Open No. 57-1761.
It is described in 25.58-5226.58-136417 and is publicly known. However, with this conventional method, the resulting ultra-thin polyester film has many insulation defects.

Electrical Application 9 For example, it has the disadvantage that it is difficult to use as a dielectric for capacitors.

[Purpose of the invention]

An object of the present invention is to provide a method for producing an ultrathin polyester film with few insulation defects as described above.

[Structure of the invention]

The present invention has a secondary configuration to achieve the above object.

That is, in a method for producing an ultra-thin polyester film by peeling a polyester film from a laminated film formed by closely laminating a polyolefin film and a polyester film, amine groups, carboxyl groups, The main feature is a method for producing an ultra-thin polyester film characterized by containing a modified silicone oil into which at least one group among polyoxyalkylene groups has been introduced.

What is the polyolefin film in the present invention?

Consists of olefin polymers or copolymers.

It refers to a non-oriented, -axially oriented or biaxially oriented film, and although the thickness is not particularly limited, it is usually 5 to 50 μm. 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, or copolymers and mixtures thereof. Particularly preferred in the present invention is a propylene copolymer having a melting point of 100 to 150°C, and also particularly preferred in the present invention.

Most preferred is a propylene-ethylene copolymer with a melting point of ioo to 140°C. This copolymer is Propyref 80-9
A propylene/ethylene random copolymer having an ethylene content of 2.5 to 8.0% by weight is particularly preferred. For this copolymer.

It may also be a terpolymer in which the sixth copolymer component 9, for example, butene-1, is further copolymerized within a range less than the ethylene content. In addition, this copolymer contains 50% by weight
Other polyolefins, such as polyethylene and polybutene-1, may be mixed within the range not exceeding .

In addition, various known additives 1 such as antioxidants, antistatic agents, lubricants, plasticizers, antiblocking agents, ultraviolet absorbers, or coloring pigments may be added to this copolymer.

What is the ultra-thin polyester film in the present invention?

Thickness 0.1-4.0 pm, especially 0.1-2.0
μm uniaxially or biaxially oriented polyester film. Polyester is a polymer or copolymer in which 50 or more moles of polymer bond chains, preferably 75 moles or more, are connected by ester bonds.

Typical examples include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polyethylene-bis(2-chlorophenoxy)ethane-4,4'-dicarboxylate, or a condensation polymer of cyclohexane dimetatool and dicarboxylic acid. 9 Particularly preferred for the present invention is polyethylene terephthalate.

Here polyethylene terephthalate),! :3) Ethylene terephthalate units account for 90 moles or more. In other words, other molecular units 2 such as ethylene isophthalate,
Pethylene terephthalate, ethylene adipate, alkylene glycol+'') alkylene glycol, etc. may be copolymerized. In this polyethylene terephthalate, known additives may be added.

For example, inorganic fine particles 1, coloring pigment, 9 coloring preventive agents or waxes may be added.

In the present invention, the laminated film formed by closely laminating two films is one in which a polyolefin film and a polyester film are overlapped with each other with substantially no voids, and is not particularly limited.

The peeling force when peeling the polyester film from the polyolefin film is preferably p, o, i to 10 g per q width of the polyester film.

A range of 0.1 to 1.Og is more preferable. (Measured at room temperature under the conditions of a peel angle of 180 degrees and a peel rate of 200 mm/min). This laminated film may be a two-layer laminated film in which a polyester film is laminated on one side of a polyolefin film, or a six-layer laminated film in which a polyester film is laminated on both sides of a polyolefin film. Such a laminated film is produced by merging and laminating polyolefin and polyester together in their melts and extruding the resulting sheet from a die. It can be produced by a so-called coextrusion method, and the laminated film of the present invention can be easily obtained by stretching the coextruded film in one or two directions.

Now, the gist of the present invention is to use a modified silicone oil in which at least one group selected from among an amino group, a carboxyl group, and a polyoxyalkylene group has been introduced into a polyolefin film, which is a laminated film made of a polyolefin and a polyester. It is important to keep it contained. As is well known.

Common silicone oils, ie dimethylpolysiloxane and diphenylpolysiloxane, do not have amine, carboxyl or polyoxyalkylene groups. Even if such ordinary silicone oil is used for the purposes of the present invention, it will have little effect in reducing the insulation defects of the ultra-thin polyester film for the purpose of the present invention, and even if it exists to some extent, it will still cause other adverse effects. For example, this is not preferable because it may make it difficult to deposit metal onto the polyester film.

Now, the amine group, carboxyl group or polyoxyalkylene group may be bonded into the organopolysiloxane chain in any form.

To give a specific example, there is a chemical structure having the following 9th order.

(1) Examples of amine groups (referred to as amine-modified silicone oils) Me 0H2-R4-0-NH2 (2) Examples of carboxyl groups (referred to as carboxyl-modified silicone oils) Me 0H2-R1-000R2 (3) Polyoxyalkylene Examples of groups (referred to as polyoxyalkylene modified silicone oil) Me ■ Me: Methyl group R1: Hydrocarbon group having 0 to 20 carbon atoms R2: Hydrogen Hydrocarbon group having 1 to 20 carbon atoms X: 1 to 50 Integer y: An integer from 2 to 50 n: An integer from 1 to 5 Of course, it is not necessary that all the monomer units in the organopolysiloxane chain have undergone such modification, and the monomer units that have undergone modification and.

It may also be in the form of a copolymer with ordinary unmodified siloxane units (such as dimethylsiloxane units). The ratio of monomer units undergoing modification is generally referred to as the modification rate.2 The modification rate of the modified silicone oil used in the present invention is preferably in the range of 0 to 99 degrees, and is preferably in the range of 45 to 99 degrees. is more preferable. Furthermore, among the various modified silicone oils mentioned above, the two most suitable for the present invention are:
Use polyoxyalkylene modified silicone oil.

Particularly desirable are those modified with polyoxyethylene or polyoxypropylene. Note that the viscosity of the first modified silicone suitable for the present invention is 40°C as measured at 25°C.
A range of ˜40,000 centistokes is preferred, io
More preferably, it is in the range of 0 to 10,000 setystokes. This modified silicone oil can be replaced with ordinary dimethylpolysiloxane or diphenylpolysiloxane.
It may be used by mixing it with I, etc., but in that case, it is desirable that the ratio of modified silicone oil to the total amount is 50 or more.

The amount of modified silicone oil contained in the polyolefin film is 0 based on the weight of the polyolefin film.
．． The range of 0.01 to 1 inch is preferable, and the range of 0.05 to 0.5 inch is particularly preferable. If the content is less than this range, this is the object of the present invention. It becomes difficult to reduce insulation defects in ultra-thin polyester films. Conversely, if the content is higher than this range, the metal deposition properties of the resulting ultra-thin polyester film will be reduced. This is undesirable because it deteriorates the adhesion with adhesives, printing inks, toners, etc.

Next, a specific example of the method of the present invention will be described, but of course the present invention is not limited thereto.

First, polyethylene terephthalate (abbreviated as PET) and propylene-ethylene copolymer (abbreviated as PEO) containing 01% modified silicone oil are fed into separate extruders and heated to a temperature of 260 to 600°C. The PFiT and PKOO layers are merged in two melt extrusion nozzles,
It is in the form of a sheet consisting of six layers: P, ET/P E a/PET. This sheet is wound around a cooling drum with a surface temperature of 60°C and cooled and solidified to produce a 6-layer laminated sheet.

This sheet is heated to 80 to 160°C and stretched 25 to 5 times in the longitudinal direction and width direction, respectively. What is the stretching method?

First, it is stretched in the longitudinal direction and then in the width direction.

A so-called sequential biaxial stretching method may be used, or the longitudinal direction and two width directions may be stretched simultaneously. Any of the so-called simultaneous biaxial stretching methods may be used. Stretched laminated film, 1
Heat treatment is performed at a temperature of 50 to 260°C for 1 to 10 seconds, and then slowly cooled to room temperature.

A laminated film is obtained in which six layers of PET/PKO/PET are closely laminated. The thickness of each layer of this film is 9
For example, the PET layers on two sides are each 05 μm thick, and the PE0 layer in the center is 05 μm thick.
The layer thickness is such as 15 μm. For example, by continuously peeling the PFiT film of the surface layer 9 from this laminated film.

An ultra-thin PET film with a thickness of 05 μm can be obtained. In addition, as another method, P'ET of laminated film
After a metal such as aluminum or zinc is deposited on the surface to a thickness of 100 to 200 OA by a conventional method, the deposited PET layer may be peeled off. Alternatively, the deposited PET layer may be peeled off after the deposited laminated film is formed into a tape by micro-slitting it into a tape having a width of 1 to 20 openings. A capacitor element can also be made by making two sets of this tape-shaped vapor-deposited PET film, peeling off the vapor-deposited PET layer from each, and winding the two layers. By attaching terminals to both ends of this element using a method such as metal spraying, a foil-wound capacitor can be created.

[Effects of the present invention]

The present invention is a laminated film in which a polyolefin film and a polyester film are closely laminated, and by incorporating a specific modified silicone oil into the polyolefin film, an ultra-thin polyester film is obtained by peeling the laminated film from the laminated film. This has the effect of significantly reducing the number of insulation defects. If insulation defects are reduced, the quality of capacitor elements made using this polyester film as a dielectric will be improved, and the quality of capacitors obtained from these elements will also be improved.
The present invention is particularly useful for ultrathin polyester films for capacitors.

[Method of measuring physical properties]

The methods for measuring physical properties etc. used in the present invention are as follows.

(1) Thickness of film: 1 μm+jp For thick films, measure with dial gauge-c and -h. For films with a diameter of 1 μm or less, attach the film to a glass support without wrinkles, apply it to a stylus surface roughness meter, and measure the boundary between the area where the film is absent and the area where the film is present. The difference in level was measured and this was taken as the film thickness.

(2) Melting point Using DSQ, the temperature was raised at a rate of 20° C./min, and the temperature corresponding to the top of the endothermic peak accompanying melting was defined as the melting point (sample amount: 10 mg).

In addition, when two or more melting point peaks appeared, the temperature at the top of the higher peak was taken as the melting point.

(3) An ultra-thin polyester film with aluminum vapor-deposited on one side of several insulation defects is spread out on the copper plate without wrinkles. At this time, the polyester film is sandwiched between copper and aluminum with the vapor deposition surface facing upward. Then, using copper and aluminum as electrodes, during this time,
A DC voltage of 100 V is applied per 1 μm of film thickness. Then, current flows between the electrodes in the insulation defect area, and the vapor-deposited surface partially disappears, so by this method, the number of insulation defects per unit area of the film can be determined. Here, the number of insulation defects is expressed as (pieces/m2). The smaller this number is, the better it is as a capacitor film.

〔Example〕

Hereinafter, two embodiments of the present invention will be described based on Examples. Of course, the two embodiments do not restrict the content of the present invention.

Example 1 The following two types of raw materials (pellets) were prepared.

PET: Melting point 259℃, intrinsic viscosity 0.62 (dl/
g) polyethylene terephthalate. Average particle size, 0
It contains 0.1% by weight of synthetic silica particles of 6 μm and 0.1% by weight of sodium montanate.

PEO: Propylene-ethylene random copolymer with an ethylene content of 5.5% by weight. Melting point: 125°C. Contains 0.155% by weight of polyoxyethylene modified silicone oil (denaturation rate 80%, viscosity 1800 centistokes at 25°C).

These two types of raw materials are fed to separate extruders and heated to 280°C.
The melts were melted and extruded in a T-shaped nozzle to form a three-layer structure of PET/PFiO/PET, which was then wrapped around a cooling drum with a surface temperature of 25°C to cool and solidify. Toshida is a laminated sheet. P'ET on both sides
The thickness of each layer is 5 μm, and the thickness of the central PE0 layer is 150 μm.
It was μm.

This sheet was heated to 90°C, stretched 6.1 times in the longitudinal direction, and immediately cooled to 60°C. Then again 10
The film was heated to 0°C, stretched 6.2 times in the 9-width direction, then heat-treated at 200°C for 6 seconds while maintaining the tension, slowly cooled, cooled to room temperature, and wound into one roll. The obtained film was a laminated film in which three layers were closely laminated, with the PET layers on both sides having a thickness of 05 μm, and the PEC layer at the center having a thickness of 15 μm.

Aluminum was deposited on the surfaces of the PET layers on both sides of this laminated film by a conventional method, and then the deposited PET layers were peeled off to obtain a deposited PET film with a thickness of 0.5 μm. Note that the peeling force at this time was o, 2 g/(2). When we measured the number of insulation defects in this film, we found that it was 6.
It was found that the film had a very low value of 1000 ml/m2, and was good as a film for capacitors.

Comparative Example 1 The polyoxyethylene-modified silicone oil was removed from the OPEC layer of Example 1 above, all other conditions being the same,
A vapor-deposited PET film of 0.05 μm was made. The number of insulation defects in this film is as high as 42/m2, so it is not very good as a capacitor film75
That's one.

Example 2 Instead of the polyoxyethylene-modified silicone oil of Example 1, amine-modified silicone oil (modification rate 75%,
with a viscosity of 1200 centistokes at 25°C),
A vapor-deposited PET film with a thickness of 0.5 μm was made using the same method as in Example 1.

The number of insulation defects in the film was measured.

7 pieces/m2, showing good results as in Example 1.

Patent applicant Higashi Shikikai Co., Ltd.

Claims (1)

[Claims] In a method for producing an ultra-thin polyester film by peeling a polyester film from a laminated film formed by closely laminating a polyolefin film and a polyester film, an amino group, a carboxyl group, or a polyoxyalkylene is preliminarily added to the polyolefin before the adhesive lamination. A method for producing an ultra-thin polyester film, characterized in that it contains a modified silicone oil into which at least one of the groups has been introduced.