JP2689413B2 - Method for producing ultra-thin evaporated polyester film - Google Patents

Description

Description: TECHNICAL FIELD OF THE INVENTION The present invention has a thickness of 0.2 to 4.0 μm, and particularly a thickness of 0.2 to 2.0.
The present invention relates to a method for continuously and efficiently producing an ultrathin vapor-deposited polyester film having a thickness of .mu.m, more specifically 0.2 to 1.0 .mu.m. Such ultra-thin evaporated polyester film,
It is particularly suitable for capacitors. [Prior art and its drawbacks] A method of making an ultrathin polyester film by peeling the polyester film from a laminated film obtained by closely laminating a polyolefin film and a polyester film is disclosed in JP-A-58-5226, 58-136417, 57. It is already known, for example, in Japanese Patent Publication No. 176125. Further, JP-A-58-5226 also suggests a method of peeling after vapor deposition on a laminated film. However, actually, when the ultrathin vapor-deposited polyester film is continuously peeled off from the polyolefin support film to obtain a long film, the film breaks immediately, which is a drawback that it is difficult to put into practical use. there were. [Object of the invention] The object of the present invention is a method without the above defects, that is, the ultra-thin vapor deposition polyester film is continuously peeled from the polyolefin support film, peeling without causing film breakage, ultra-thin vapor deposition It is an object of the present invention to provide a method for producing a polyester film. [Structure of the invention] In order to achieve the above object, the present invention has the following structure, that is, at least one surface of a support film made of polyolefin, and an oriented polyester film having a thickness of 0.2 to 4.0 µm is adhered and laminated, Further, the vapor-deposited laminated film obtained by vapor-depositing metal on the polyester film is slit by a cutting device so that the film width after slit is 300 mm or less and the unevenness of the slit end surface is 10 μm or less, and then the polyolefin support The essence is a method for producing an ultrathin vapor-deposited polyester film, which is characterized by continuously peeling a vapor-deposited polyester film from a film. The vapor-deposited laminated film used in the present invention is a film obtained by vapor-depositing a metal on the polyester surface of a film in which polyolefin and polyester are adhered and laminated. As a laminated structure, there are 3 layers of polyolefin / polyester / vapor-deposited metal layer.
The layer structure or a five-layer structure of vapor-deposited metal layer / polyester / polyolefin / polyester / vapor-deposited metal layer is typical, but not limited thereto. Such a vapor-deposited laminated film is obtained by coextruding polyolefin and polyester to prepare a laminated unstretched film, stretched uniaxially or biaxially to give molecular orientation, and then heat-treated to prepare an oriented laminated film. It is a general method to manufacture by a method of vapor-depositing a metal on the surface of the polyester film, but of course, it may be prepared by a method other than this. The polyolefin referred to in the present invention means low density polyethylene, medium density polyethylene, high density polyethylene, linear low density polyethylene, polypropylene, polybutene-
1, a polymer of olefin such as poly-4-methyl-pentene-1, or a copolymer or mixture thereof. Among these, particularly preferable for the present invention is the melting point.
It is a propylene-ethylene copolymer at 100 to 140 ° C. This copolymer contains 80 to 98% by weight of propylene and 2 to 2 of ethylene.
20% by weight, and particularly preferred is a propylene / ethylene / random copolymer having an ethylene content of 2.5 to 8.0% by weight. The copolymer may be a terpolymer in which a third copolymerization component, for example, butene-1 is further copolymerized in an amount less than the ethylene content. Further, this copolymer may be mixed with other polyolefin, for example, polyethylene or polybutene-1 within a range not exceeding 50% by weight. In this copolymer, various known additives, for example, antioxidants,
An antistatic agent, a lubricant, a plasticizer, an antiblocking agent, an ultraviolet absorber or a coloring pigment may be added.
The polyolefin film serving as the support may be uniaxially or biaxially molecularly oriented, or may be a non-oriented film. Next, the polyester referred to in the present invention means polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polyethylene bis (2-chlorophenoxy) ethane-4,4'-dicarboxylate or cyclohexanedimethanol and condensation polymerization of dicarboxylic acid. It means a polymer such as a polymer having an ester bond as a main polymerization unit, a copolymer, or a mixture thereof. Of these, polyethylene terephthalate is particularly preferable for the present invention. The term "polyethylene terephthalate" used here means that ethylene terephthalate units are 90 mol%.
It occupies the above. In other words, 10 mol%
Other molecular units such as ethylene isophthalate, butylene terephthalate, ethylene adipate, alkylene glycol, polyalkylene glycol and the like may be copolymerized within a range not exceeding the above. Known additives such as inorganic fine particles, coloring pigments, anti-coloring agents, waxes, etc. may be added to the polyethylene terephthalate. The polyester film constituting the present invention is required to be uniaxially or biaxially molecularly oriented. An unoriented film is fragile and difficult to peel continuously, and also has poor electrical properties. The thickness of this oriented polyester film is 0.2-
4.0 μm, especially 0.2-2.0 μm, more specifically 0.2-1.0
The range of μm is suitable for the present invention. When the thickness is less than this range, continuous peeling is difficult even when the method of the present invention is used. On the contrary, in the case of a film thicker than the above range, continuous peeling is generally easy, so that the necessity of using the method of the present invention is lacking. The metal deposited on the polyester film is generally a low melting point metal such as aluminum, zinc, tin or copper, but may be a high melting point metal such as chromium, nickel or titanium. As the vapor deposition method, a resistance heating type vapor deposition method,
Known methods such as an electron beam heating type vapor deposition method, a sputtering method and an ion plating method can be used. The film thickness of the metal to be vapor-deposited is not particularly limited, but is usually preferably in the range of 0.02 to 0.2 μm. By the way, in the following explanation, as a representative of a polyolefin film, a propylene / ethylene copolymer film having a melting point of 132 ° C (hereinafter abbreviated as PEC), and as a representative of a polyester film, a polyethylene terephthalate film (hereinafter referred to as PET) Aluminum (hereinafter abbreviated as AL) is used as a representative of the vapor-deposited metal layer and vapor-deposited metal layer, and a vapor-deposited laminated film having a three-layer structure of PEC / PET / AL is used as a representative example. It is extremely difficult to continuously peel PET / AL layer (laminate) from this film.
If the PET thickness is 1.0 μm or less, the film will be broken immediately and continuous peeling will not be possible. The inventors have earnestly studied a method of facilitating the continuous peeling, and arrived at the present invention. One of the gist of the present invention is 300 mm or less in width of the vapor-deposited laminated film before peeling, preferably 200.
It is to pre-slit to be not more than mm, more preferably not more than 100 mm, and then peel off the PET / AL layer. When the PET / AL layer is peeled off after the film width of the vapor-deposited laminated film is narrowed by slits in advance, film breakage is unlikely to occur and continuous peeling becomes extremely easy. The lower limit of the film width is not particularly limited, but if it is narrower than 5 mm, it becomes a string-like shape and is easily cut, which is not desirable. Another skeleton of the present invention is that the degree of unevenness of the end face (slit cut end) of the vapor-deposited laminated film that is slit is 10
μm or less, preferably 8 μm or less, more preferably 5 μm
m or less. When the degree of unevenness of the slit film end surface is larger than the above range, continuous peeling of the film becomes extremely difficult, and the film is immediately broken. The lower limit of the unevenness is not particularly limited, but it is substantially difficult to set it to 0.5 μm or less. The method of holding the unevenness of the slit film end surface in the small range as described above is not particularly limited and may be a slit by a known cutting device, but a slit by a laser beam and a heating blade (metal, Blades made of ceramics such as alumina ceramics, zirconia ceramics, silicon carbide ceramics, silicon nitride ceramics, etc. (heating temperature is 100 to 300 ° C.)
It is a slit by. A slit made of leather having a particularly sharp cutting edge or a slit made by a particularly sharp shear cutter may be used. Further, the end surface of the film having a degree of unevenness larger than the above range may be heated with infrared rays or may be brought into contact with a heating roll, a heating bar or the like to reduce the degree of unevenness, and then the film may be contained within the above range. Now, the present invention is a method for continuously peeling the PET / AL layer from the PEC layer, which is a support, by the method as described above, to make an ultrathin vapor-deposited polyester film. For example, a continuous nip can be facilitated by nipping with a nip roll composed of a combination of a rubber-coated roll and a metal roll, and peeling the PET / AL layer from the PEC layer at the nipping point so that peeling occurs. That is, the PEC layer of the support film and PET / A
The peeling start point from the L layer is placed at the nip portion of the nip roll or immediately after that (a point within 5 mm from the nip point). The PET / AL layer separated at the nip point of the nip roll may be subsequently run along one roll of the nip roll and then transferred to another roll, or may be wound directly. At this time, the winding tension of the PET / AL layer is preferably maintained in the range of 3 to 30 g / (cm film width). [Advantages of the Invention] The present invention, as described above, a vapor-deposited laminated film in which a metal is vapor-deposited on the polyester surface of a laminated film made of polyolefin and polyester, the film width after slitting.
300mm or less, slit so that the unevenness of the slit end surface is 10μm or less, and then continuously peeling the vapor-deposited polyester film from the polyolefin support film to obtain a method for producing an ultra-thin vapor-deposited polyester film. It is possible to obtain an ultrathin vapor-deposited polyester film with good properties and without causing film breakage. Further, since the peelability is good, the resulting ultrathin vapor-deposited polyester film has few insulation defects such as pinholes and is particularly suitable as a material for capacitors. The obtained ultrathin vapor-deposited film can be wound to form a so-called wound capacitor, or a large number of films can be stacked and laminated and adhered, and the capacitor can be cut out therefrom to form a so-called laminated capacitor. [Measurement and Evaluation Method] 1. Roughness of Slit Film End Face The slit film end face is observed with a 400 × optical microscope from directly above the film face. Since the unevenness at the edge of the film is observed, this is photographed and further magnified 2.5 times at the development printing stage, and the vertical distance between the bottom of the deepest valley and the highest peak of the mountain in one visual field. Is measured in μm. This measurement is performed for 30 fields of view on an arbitrary part of the film end face, the vertical distances between the valleys and the peaks obtained in each are summed, and this is divided by 30 to obtain an average value, which is taken as the unevenness. 2. Polymer melting point 10 mg of polymer sample was set in DSC and heated at a heating rate of 20 ° C / min, and the temperature corresponding to the top of the endothermic peak accompanying melting was taken as the melting point. The melting point peak is 2
When more than one peak appears, the temperature at the top of the higher peak was taken as the melting point. 3. Evaluation method of continuous peeling property The slit vapor-deposited laminated film is set in a rewinding machine, the film is run at a speed of 10 m / min, and the vapor-deposited polyester film layer is peeled at one roll contact part in the middle. Then, it was guided to another winder and wound up. 500m in this test
"Peelability is best" for those that can be continuously peeled above, "Normal peelability" for films that are 100 m or longer and shorter than 500 m, and "Peelability" for films that are less than 100 m Although it is practically necessary that the peelability is "poor", the peelability is the best, but it can be used at a normal level depending on the application. [Examples] Hereinafter, one embodiment of the present invention will be described based on Examples. Example 1 <Method for producing vapor-deposited laminated film> Pellets of PET (intrinsic viscosity 0.60 measured in orthochlorophenol at 25 ° C) and PEC (melting point 130 ° C) were fed to separate extruders and melted at 280 ° C. Extrude, merge both melts in the die, mold with the die, and then PET / PEC / PE
A laminated sheet having three layers of T was formed. Surface temperature 3
It was wound around a 0 ° C. cooling drum and cooled and solidified to prepare an unstretched laminated sheet. This sheet is heated to 90 ° C, stretched 3.5 times in the longitudinal direction, once cooled, then heated again to 105 ° C and stretched 5.0 times in the width direction, then the temperature is raised to 190 ° C and tension is applied. In this state, heat-treat for 5 seconds, slowly cool it, and then wind it while removing static electricity with an electrostatic eliminator.
A laminated film having three layers of PET / PEC / PET was obtained. The total thickness of this film was 15 μm, of which the PET layers each had a thickness of 0.5 μm. Set this laminated film in a resistance heating type vapor deposition machine, on the PET film surface,
Aluminum was evaporated to a thickness of 0.06 μm. The vapor deposition laminated film thus obtained had a total width of 500 mm. The vapor-deposited laminated film thus obtained was applied to a micro slitter and slit into a film width of 50 mm. The slit was performed by a carbon dioxide gas laser beam, and the unevenness of the slit film end surface was set to 2 μm. When the vapor-deposited PET film layer was continuously peeled from this film, no film break occurred even after peeling 500 m or more, and the "peelability was the best". Example 2 Instead of the laser beam slit used in Example 1, a sharp ceramic blade was used for slitting, and the unevenness of the slit film end surface was set to 4 μm. This film was also the "best for peeling". Comparative Example 1 When the test of Example 2 was performed under the same conditions except that the film width was expanded to 450 mm, the film was broken when peeled by 80 m and the result was "poor peelability". Comparative Example 2 By changing the degree of sharpness of the ceramic blade in Example 2, a film having a 12 μm unevenness on the slit film end surface was produced. When continuous peelability was evaluated for this, film breakage occurred at around 50 m and it was “poor peelability”. Example 3 The vapor-deposited laminated film prepared in Example 1 had a film width of 60.
Slit to mm. The slit is made with a sharp ceramic blade, and the unevenness of the slit film edge is 5μ.
m. Nip this film with a pair of nip rolls consisting of a combination of metal roll and rubber coated roll,
At the nipped portion, the vapor-deposited PET film is the P of the support.
It was designed to be peeled off from the EC film. Stripped vapor deposition
The PET film was run along a metal roll, and the PEC film was run along a rubber-covered roll on the opposite side, and each was guided to another winder and wound up. At this time, the winding tension of the vapor-deposited PET film was 6 g / (cm film width). The winding speed is 3 times faster than 10m / min of the continuous peelability evaluation method described above.
Although the film was continuously peeled at 30 m / min, the film did not break at all, and the ultrathin vapor-deposited PET film could be wound continuously for 1000 m or more. This ultra-thin vapor-deposited PET film had few pinholes and was an extremely excellent material for capacitors.

Claims (1)

(57) [Claims] At least one surface of a support film made of polyolefin, an oriented polyester film having a thickness of 0.2 to 4.0 μm is adhered and laminated, and a vapor-deposited laminated film in which a metal is vapor-deposited on the polyester film,
An ultrathin vapor-deposited polyester characterized by slitting the film width after slitting to 300 mm or less with a cutting device so that the irregularity of the slit end surface is 10 μm or less, and then continuously peeling the vapor-deposited polyester film from the polyolefin support film. Film manufacturing method.