JP2855690B2 - Polyester laminated film - Google Patents

Description

The present invention relates to a laminated film formed by laminating a support film and an ultrathin polyester film,
More specifically, in the laminated film, from the support film consisting of polyphenylene sulfide, while the ultra-thin polyester film can be peeled smoothly, the support film is strong, by using a polyphenylene sulfide film excellent in heat resistance. Polyester laminated film capable of obtaining a polyester film excellent in capacitor dielectrics and heat-sensitive stencil base paper, which enables extremely thinning of the support film and high-temperature heat treatment, and has extremely good vapor deposition properties and slit properties. It is.

[Related Art] In recent years, with the miniaturization of capacitors accompanying the miniaturization of electric or electronic circuits, the thickness of dielectric layer films has been further reduced. Examples of such ultra-thin films include, for example, JP-A-58-5526 and JP-A-58-5526.
Japanese Patent Application Laid-Open No. 58-132520 and Japanese Patent Application Laid-Open No. 58-136417 disclose a method in which different kinds of polymers are stretched in a laminated state to form a laminated film, and one of the films is peeled off and used as an ultrathin film. Have been.

[Problems to be Solved by the Invention] Since such a conventional laminated film uses a film having no support and having poor heat resistance, the film may be broken at the time of film formation and heat treatment, or the strength of the back may be reduced. Since the thickness of the support is increased for covering, the loss increases and there is a problem in productivity. On the other hand, at the time of vapor deposition, due to the winding tension, the film is likely to be stretched, wrinkles due to heat are likely to occur, and even at the time of slitting, the degree of unevenness of the slit end surface is large, and the film tends to be cut out and the margin width is easily varied, so that There is a problem that the capacitor characteristics of the obtained film are remarkably inferior.

The present invention solves the above-mentioned drawbacks, is resistant to tearing, is excellent in pinhole resistance, thins the support, vapor deposition of the laminated film, increases the slitting property, etc., as a capacitor film, and also for heat-sensitive stencil paper. It is an object of the present invention to provide a laminated film having an excellent ultra-thin polyester film.

Means for Solving the Problems In order to achieve the above object, the present invention provides the following constitution, that is, one side or both sides of a support film having a thickness of 0.2 to
In a laminated film in which a 1.5 μm polyester film is laminated with an adhesive force that can be peeled off from the support film, the intrinsic viscosity of the polyester film is 0.55 or more and 1.
5 or less, and the support film is made of a polyphenylene sulfide film.

The polyester film used in the present invention refers to a uniaxial or biaxial resin composition comprising a polymer or a copolymer in which 70% by mole or more, preferably 85% by mole or more of a bonding chain of a polymer is connected by an ester bond. It is an axially oriented film.

If it is less than 70 mol%, the crystallinity, heat transition temperature, etc. of the composition will be low, and the heat resistance, dimensional stability, mechanical properties, etc., which are characteristics of a film made of the composition, will be impaired. The remaining less than 30 mol% in the composition may contain additives other than polyester, such as polymers other than polyester, inorganic or organic fillers, lubricants, coloring agents, and ultraviolet absorbers.

The main glass transition point measured by DSC is 6
Those in the range of 0 to 100 ° C are preferred.

The intrinsic viscosity of the polyester film used in the present invention,
It is 0.55 or more and 1.5 or less, preferably 0.65 or more and 1.0 or less.

If the intrinsic viscosity is less than 0.55, a sharp increase in pinholes is caused, and if the intrinsic viscosity exceeds 1.5, it becomes difficult to control the extrusion stability and film formation due to heat generation due to shearing and the like.

Examples of the polyester include polyethylene terephthalate (hereinafter sometimes abbreviated as PET) and its copolymer, polybutylene terephthalate and its copolymer, polyethylene bis (2-chlorophenoxy) ethane-4,4'-dicarboxy. Rate and its copolymer,
Examples thereof include 1,4-polycyclohexylene dimethylene terephthalate (hereinafter, may be abbreviated as PCT) and a copolymer thereof, polyethylene-2,6-naphthalate, and the like.

The thickness of the film ranges from 0.2 to 1.5 μm,
From the viewpoint of reducing the size and shape of the condenser and improving the thermal efficiency of the heat-sensitive stencil base paper, 0.2 to 0.2
A range of 1.0 is more preferred. If the thickness is less than 0.2μm,
It is not preferable because a trouble that breaks during film formation or peeling is likely to occur. On the other hand, when the thickness is more than 1.5 μm, the film forming property and the workability are good even with a single film, and it is not necessary to form the laminated film as in the present invention.

The average surface roughness Ra of the film is preferably in the range of 0.03 to 0.10 μm from the viewpoints of workability during winding or lamination and self-healing characteristics of the completed capacitor.

In the present invention, a polyphenylene sulfide film (hereinafter sometimes abbreviated as a PPS film), which is a support film, is a uniaxial or biaxially oriented film of a resin composition containing poly-p-phenylene sulfide as a main component. It is. The thickness of the film is not particularly limited, but a film having a thickness of 1 to 10 μm is suitable for the present invention.

Here, the resin composition containing poly-p-phenylene sulfide as a main component (hereinafter sometimes abbreviated as a PPS-based composition) refers to a composition containing 70% by weight or more of poly-p-phenylene sulfide. .

70% by weight of poly-p-pheninyl sulfide
If less than, the crystallinity of the composition, the heat transition temperature, etc. will be low, and when the support is thinned, the stiffness, heat resistance,
Dimensional stability, mechanical properties, vapor deposition properties, slit properties, etc. are impaired, and the requirements of the present invention cannot be satisfied.

The remaining less than 30% by weight of the composition may contain additives other than poly-p-phenylene sulfide, such as polymers other than poly-p-phenylene sulfide, inorganic or organic fillers, release agents, lubricants, coloring agents, and UV absorbers. No problem. The melt viscosity of the resin composition is preferably from 500 to 12,000 poise (more preferably from 1,000 to 10,000 poise) at a temperature of 300 ° C. and a shear rate of 200 sec ⁻¹ from the viewpoint of film formability. The melt viscosity of the resin composition is equal to the melt viscosity of the finally obtained polyphenylene sulfide film.

In the present invention, poly-p-phenylene sulfide (hereinafter sometimes abbreviated as PPS) refers to a compound having a structural formula of 70 mol% or more (preferably 85 mol% or more) of a repeating unit. Means a polymer comprising the structural unit represented by Such components
If it is less than 70 mol%, the crystallinity, heat transition temperature, etc. of the polymer will be low, and the heat resistance, dimensional stability, and mechanical properties, which are characteristics of a film composed of a resin composition containing PPS as a main component, will be impaired.

If the amount of the repeating unit is less than 30 mol%, preferably less than 15 mol%, a unit containing a copolymerizable sulfide bond may be contained. The thickness of the support film is 3 times the thickness of the polyester film. ~ 30 times is preferred. If the support film is too thin, it is difficult to handle such as vapor deposition and cutting as a laminated film.If the support film is too thick, the thickness of the laminated film becomes too thick, handling is inconvenient, and loss is large and practical. Not preferred.

In the present invention, the laminated film is a film in which a polyester film is laminated on one side or both sides of the support film with an adhesive force capable of peeling off the support film.

The adhesion between the support film and the polyester film (adhesion measured at a peel angle of 180 ° and a peel speed of 200 mm / min) is 0.
The range is preferably 2 to 3.0 g / cm (more preferably 0.3 to 1.0 g / cm). If the adhesion is less than 0.2 g / cm, it may cause a problem of peeling during film formation, vapor deposition, or micro slitting. If it exceeds 3.0 g / cm, continuous peeling is difficult, and the film often breaks.

As a method for producing the laminated film, for example, a PPS-based composition and a polyester, which are raw materials for a support film, are supplied to separate extruders, respectively, and are melted at a melting point of each polymer or higher. Into a polymer tube or a die to form a laminated state, which is extruded from the die and cooled and solidified to form a two-layer laminated sheet of a polyester / PPS-based composition or a three-layered sheet of a polyester / PPS-based composition / polyester Laminated sheet (the thickness of the polyester film on both sides may be the same or different), and then uniaxially or biaxially stretched the laminated sheet at a temperature equal to or higher than the glass transition point of the PPS composition and equal to or lower than 120 ° C. The heat treatment is performed at a temperature of 180 ° C. or higher (preferably 210 ° C. or higher) and the melting point of the polyester or lower.

For the stretching of the laminated film, any of a sequential biaxial stretching method and a simultaneous biaxial stretching method can be applied.

The polyester laminated film of the present invention thus obtained is vapor-deposited on the polyester film surface depending on its use,
After coating, laminating, etc., a micro slit is usually performed, and the degree of unevenness of the slit end face is 3 μm.
m or less. This unevenness degree is correlated with the total thickness of the laminated film, the thickness of the support layer film, the stiffness of the support layer, and the like. Yes, too large is not preferable because troubles such as film breakage at the time of peeling occur.

After the micro slit, from the laminated film,
The PPS support film is peeled off and used.

Although there is no particular limitation on the peeling method, continuous peeling is easy if the laminated film is nipped between a pair of nip rolls and the polyester film is peeled off along one roll surface.

The laminated film of the present invention can be used in many applications such as dielectrics for capacitors, heat-sensitive stencil paper, and heat-sensitive transfer ribbons.

The following are typical application examples of the laminated film of the present invention,
The general method of processing condensers and thermosensitive stencils is described.

First, regarding the capacitor, the polyester film layer of the polyester laminated film obtained as described above is metallized and wound or laminated to obtain a capacitor.

Here, metallization means forming a metal thin film having no self-supporting property formed on a film by a method such as vacuum evaporation. As the method, the vacuum deposition method is most common, but other examples include a sputtering method and an ion plating method.

Aluminum, zinc, nickel, and the like can be given as the metal to be used as the thin film. Of these, aluminum is preferable in terms of vapor deposition properties and characteristics. The surface resistance of the metallized film formed by metallization is preferably 0.5 to 10Ω from the viewpoint of the moisture resistance and self-heel of the obtained capacitor.

In metallizing the polyester laminated film, vapor deposition can be performed on one side or both sides. When metallizing,
Alternatively, it is a usual method to provide a non-metallized portion (a so-called margin) by using a tape mask, an oil mask, or a laver beam so that the counter electrode does not short-circuit after metallization.

Next, a capacitor element is manufactured. Here, one method for each of the winding type and the lamination type is exemplified, but the method is not limited. To obtain a wound capacitor, two strips of a metallized film slit into a narrow tape with a margin at one end are stacked on top of each other with the margins facing each other while peeling off the deposited film. It is a common method to wind up a so-called peeling element. In the case of a multilayer capacitor, a capacitor mother element is obtained by winding the film on a large-diameter drum or flat plate while peeling off the deposited film.

In the case of a wound capacitor, the obtained mother element is press-molded at a temperature of room temperature to 230 ° C. The preferred range of the temperature is from ordinary temperature to 160 ° C. Thereafter, a capacitor is obtained through an external electrode mounting process (using metal spraying, conductive resin, or the like), a lead wire mounting process, and a sheathing process when a lead-type capacitor is used.

In the case of a multilayer capacitor, the mother element wound on a large-diameter drum or a flat plate is formed by applying pressure in the thickness direction of the film, for example, by tightening with a ring or the like, or by pressing with a parallel flat plate or the like. The temperature range at that time is from ordinary temperature to 230 ° C. The preferred range of the temperature is from ordinary temperature to 160 ° C.

Before or after the press molding, the mother element is cut in the longitudinal direction of the film such that the metal thin film electrodes are opposed to each other with a margin, and an external electrode mounting step (metal spraying, conductive resin, or the like) is performed. Cutting process,
When a lead-type capacitor is used, a capacitor is obtained through a lead wire attaching process and an exterior process.

On the other hand, as a processing example in the heat-sensitive stencil paper application, an adhesive is coated on a porous support such as Japanese paper, Tetoron gauze, and the polyester laminated film of the present invention is adhered, and then a polyphenylene sulfide film as a support is used. Peel off two layers of polyester film. If necessary, a release layer is provided on the bonded polyester film. This is what is called a heat-sensitive stencil stencil sheet.

Using this heat-sensitive stencil sheet, perforation and printing are usually performed by the following two methods. One method is the flash method, which is perforated with a xenon lamp, infrared rays, etc. and is applied to a printing machine, and the other is the method of perforating and printing with a thermosensitive element called the thermal head method. It is.

[Effect of the Invention] As described above, by using a PPS film as a support film, the support film can be made thinner, which contributes to an improvement in productivity and also prevents film breakage during film formation and heat treatment. Decrease. Also, at the time of vapor deposition of the obtained laminated film, elongation of the film and almost no generation of wrinkles due to heat, at the time of micro slit, because the degree of unevenness of the slit end surface is extremely small,
Variation in margin width is reduced, and film breakage during peeling is reduced. In addition, since the polyester film obtained by peeling is excellent in pinhole resistance, mechanical properties, and the like, when a capacitor is used, a capacitor element having few dielectric insulation defects can be produced despite being an extremely thin film.

[Method for Measuring and Evaluating Characteristic Values] The method for measuring and evaluating characteristic values used in the description of the present invention will be described.

(1) Intrinsic viscosity of polyester film The polyester was dissolved in orthochlorophenol at 25 ° C, and the intrinsic viscosity was measured by a conventional method.

(2) Degree of Concavity and convexity of Slit End Surface When a polyester / PPS-based composition / polyester laminated film was vapor-deposited and micro-slitted, the degree of concavity and convexity of the end surface was measured with a microscope and photographed, and judged according to the following criteria.

○: Unevenness 3 μm or less on the end face △: ３ 3 to 5 μm ×: ５ 5 μm or more (3) Pinhole The laminated film is peeled off using a slitter, and the peeled polyester film is laminated on a white film without wrinkles. . Magic ink was sprayed over the entire area of 1 m ² , and the number of spots formed on the white film was defined as a pinhole.

◎: No pinholes generated ○: 1 to 4 pinholes △: 5 or more pinholes ×: 10 or more pinholes (4) Melting point of polymer Set 10 mg of sample in DSC and raise at 20 ° C / min. The temperature was raised at a temperature rate, and the temperature corresponding to the top of the endothermic peak accompanying the melting was defined as the melting point. When there are two or more peaks, the temperature corresponds to the peak having the higher height.

(5) Both the glass transition point of the polymer and the main peak of the heat crystallization were measured by DSC.

(6) Capacitance of Capacitor Element The capacitance (capacitance) was measured at 25 ° C. and 1 kHz using an automatic capacitance bridge.

(7) Insulation failure rate of the capacitor element For 100 capacitor elements, a voltage of DC 80 V per 1 μm of the dielectric film thickness is applied by the instantaneous application method.
The ratio of the element that caused insulation breakdown was defined as the insulation failure rate.

(8) Solder heat resistance of the capacitor The initial capacity was evaluated by the rate of change of the capacity after immersion in a 210 ° C. solder bath for 10 seconds. It goes without saying that the smaller the value, the better.

(9) Capacitor processability The three-layer laminated film is placed on a vacuum evaporation machine, and one side or both sides are aluminum-deposited and rolled, and heat loss, film elongation, occurrence of wrinkles, etc., and the end face during micro slitting Was evaluated by comprehensively evaluating the degree of unevenness, the variation of the margin, and the breakage of the film at the time of peeling.

：: Good configuration in all Δ: Configuration with some problems X: Many problems [Examples] Hereinafter, embodiments of the present invention will be described with reference to the present invention and comparative examples.

Example 1 (1) Production of laminated film The following two kinds of raw materials (pellets) were prepared.

PET: intrinsic viscosity 0.75dl / g, melting point 264 ° C. Wet silica with a particle size of 0.5 μm as the outer particle
Contains 0.5% and an average particle size of 1.5 μm 0.075%.

PPS: Poly-p-phenylene sulfide consisting of 100% p-phenylene sulfide linkage.

 Melting point 285 ° C Contains 0.5% of Asahi Denka Kogyo CLE-1000 as a release agent.

The two types of raw materials are supplied to separate extruders,
The three-layer composite die with a structure in which the three flows merge in the die, the polyester resin is supplied to the outer two layers and the PPS resin is supplied to the central layer, and the three layers of PET / PPS / PET are laminated. In this state, the sheet was extruded into a sheet, wound around a cooling drum and rapidly cooled and solidified to obtain an unstretched three-layer laminated sheet.

This sheet was stretched 3.6 times in the longitudinal direction at 96 ° C. between rolls, then stretched 3.4 times in the width direction at 98 ° C. in the tenter, and further heat-treated at 230 ° C. for 6 seconds in the same tenter. Further cooling was performed to obtain a three-layer laminated film of the present invention in which the thickness of the PET layers on both surfaces was 0.5 μm and the thickness of the central PPS layer was 3 μm. Although the support was 3 μm, the laminated film was sufficiently stiff. The intrinsic viscosity of PET film is
It was 0.72. At this time, the adhesion when peeling the polyester film from the support was 0.8 g / cm.

(2) Evaporation This laminated film roll is applied to a vacuum evaporator with a width of 500 mm, and aluminum is applied to the surface of both PET layers with a surface resistance of 2Ω.
/ Both sides were vapor-deposited to a thickness of.

At this time, a margin portion was formed in the longitudinal direction at a ratio of 1.0 mm to the vapor deposition portion of 8.0 mm.

The above-mentioned vapor-deposited laminated film was cut into a tape having a film width of 4.5 mm and an inner margin width of 0.5 mm by a micro-slitter with a blade at the center of the vapor-deposited portion and the center of the margin portion, and wound up in a laminated state.

At this time, the degree of unevenness of the slit end face was as good as 2 μm, and there was no problem at the time of vapor deposition and micro slitting.

(3) Manufacture of a capacitor element
While peeling off one PET film each from the book tape, two sheets were wound together as they were, and further pressed to make a capacitor element. Both ends of the device were sprayed with metallikon to form external electrodes, which were provided with lead wires, covered with powdered epoxy, and evaluated as capacitors having a capacity of 1.0 μF.

(4) Evaluation Table 1 shows the evaluation results of the obtained capacitors.
Everything was good.

Example 2 Instead of polyethylene terephthalate (PET) of Example 1, 1,4-polycyclohexylene dimethylene terephthalate (hereinafter sometimes abbreviated as PCT) was used, and PCT / PPS / The PCT was extruded into a sheet in a three-layer laminated state, wound around a cooling drum and quenched and solidified to obtain an undrawn three-layer laminated sheet.

This sheet was stretched 3.6 times in the longitudinal direction at 100 ° C. between rolls, then stretched 3.5 times in the width direction at 105 ° C. in the tenter, and further heat-treated at 250 ° C. for 6 seconds in the same tenter. Further cooling was performed to obtain a three-layer laminated film in which the thickness of both surface PCT layers was 0.5 μm and the thickness of the central PPS layer was 3 μm. Although it was a 3 μm support, it was a sufficiently rigid laminated film. The adhesion was 0.9 g / cm, and the intrinsic viscosity of the PCT film was 1.0.

Vacuum deposition and micro slitting were performed on the film roll in the same manner as in Example 1.

At this time, the degree of unevenness of the slit end face was 1 μm, indicating a good slit property.

Using the obtained PCT film, a capacitor having a capacity of 1.0 μF was manufactured and evaluated. The results are shown in Table 1.

Comparative Example 1 A film was formed in exactly the same manner as in Example 1 except that the intrinsic viscosity of PET was changed to 0.55 dl / g, and a laminated film of 0.5 μm in the polyester film in both tables and 4 μm in the PPS film as the support was obtained. Was.

The pinholes of the peeled ultra-thin PET film were abnormally large at 30 holes / m ^2, and the degree of irregularity of the slit end face was poor at 5 μm. The adhesion was 0.6 g / cm, and the intrinsic viscosity of this polyester film was 0.52 dl / g. Table 1 shows the evaluation results.

Comparative Example 2 The following two kinds of raw materials (pellets) were prepared.

PET: Wet silica with an intrinsic viscosity of 0.75 dl / g, melting point of 264 ° C, and an outer particle size of 0.5 μm
Contains 0.5% and an average particle size of 1.5 μm 0.075%.

Polyolefin: melting point 130 ° C. Ethylene content 6% by weight
Propylene / ethylene random copolymer. Contains 0.03% of Toray Silicone (SH3746) as a release agent.

The two kinds of raw materials are supplied to separate extruders and melt-extruded at 280 ° C., and the respective melts are combined in a T-type die to form a three-layer structure of PET / polyolefin / PET.
C. and wound around a hot water drum to solidify by cooling to obtain an unstretched three-layer laminated sheet.

This sheet is stretched 3.5 times in the longitudinal direction at 90 ° C., then stretched 4.5 times in the width direction at 98 ° C. in the tenter, and further heat-treated at a temperature of 210 ° C. for 6 seconds in the same tenter. It was cooled to room temperature and wound up. Thus, a three-layer laminated film having a thickness of the PET layer on both sides of 0.5 μm and a thickness of the central polyolefin layer of 7 μm was produced. In addition, when the thickness of the polyolefin as the support was set separately to 5 μm, wrinkles were formed in the laminated film at the time of winding, probably because of weakness, and it was difficult to make the support thin. The intrinsic viscosity of the PET film was 0.72, and the adhesion when peeling the polyester from the support was 0.55 g / cm.

This film roll is applied to a vacuum evaporator with a width of 500 mm, and aluminum is applied to both PET layer surfaces with a surface resistance of 2Ω /
Both sides were deposited to a thickness of □. The vapor-deposited film had problems in elongation of the film due to the winding tension and wrinkles due to the heat, and weakness in the stiffness and heat resistance of the support film.

When the above vapor-deposited film was slit with a micro slitter, the degree of irregularity of the slit end face was as bad as 8 μm,
Since the polyolefin film as the support layer was not rigid and soft, and had a large thickness, the slit property was very poor. When the polyester film was peeled from the polyolefin support, the edge face was poorly sharpened and the unevenness was large, and sometimes a phenomenon of snagging was observed, sometimes leading to film breakage.

Claims (2)

(57) [Claims] A thickness of one side or both sides of a support film.
In a laminated film in which a polyester film of 0.2 to 1.5 μm is laminated with an adhesive force that can be peeled from the support film, the intrinsic viscosity of the polyester film is 0.55 or more and 1.5 or less, and the support film is a polyphenylene sulfide film. A polyester laminated film characterized by comprising: 2. The thickness of the support film is 3 to 30 times the thickness of the polyester film, and the adhesion when the polyester film is peeled from the support film is 0.2 to 3.0.
The polyester laminated film according to claim 1, wherein the thickness is in the range of g / cm.