JPH0832426B2 - Molding method of thermoplastic resin sheet - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for molding a thermoplastic resin sheet, and more particularly to an improvement in an electrostatic charge cooling method.

(Problems to be Solved by the Prior Art and Invention) When forming a thermoplastic resin into a film, the degree of the thickness plaque is irrespective of whether or not the film is stretched when the melt is cooled and solidified on the rotary cooling body. It is known to be decisive.

To improve this unevenness in thickness, for example, as described in JP-B-37-6142, when cooled and solidified into a sheet,
It is known that a so-called electrostatic applied cooling method, in which an electrostatic charge is applied to the surface of the sheet to bring the sheet into close contact with the cooling surface, is effective, and is widely used industrially.

However, when the speed of the rotary cooling body is increased for the purpose of increasing the productivity in this electrostatic applied cooling method, the adhesive force between the film and the rotary cooling body is reduced, and so-called bound bubbles are generated. Is not acceptable as a quality characteristic required for products.

Various techniques have been proposed to improve this.
For example, in the case of a linear electrode, there are methods to reduce the diameter and to sharpen the edge part in a blade electrode, but this method not only shortens the life as an electrode because the breaking strength decreases, but also increases the tension of the electrode. Since it cannot be applied, ion wind and mechanical vibrations are transmitted to the electrodes, resulting in deterioration of thickness unevenness. Moreover, such electrodes are difficult to manufacture.

(Means for Solving Problems) As a result of intensive studies in view of the above problems, the present inventors have found that by using a certain specific conductive blade as an electrode, productivity and thickness unevenness can be improved. The present invention has been completed. That is, the gist of the present invention is a method of extruding a molten thermoplastic resin from a die and cooling and solidifying it by an electrostatic application adhesion method to form a sheet. In this method, an amorphous material having a thickness of an edge portion of 50 μm or less and a width of 0.1 to 50 mm is used. A method of forming a thermoplastic resin sheet is characterized by using a metal as an electrode.

 Hereinafter, the present invention will be described in more detail.

Examples of the thermoplastic resin applicable to the present invention include polyesters, polyester ethers, polyamides, polycarbonates, polyester carbonates, polysulfones, polyether sulfones, polyetherimides, and polyolefins such as ethylene, Polymers such as propylene, butene and 4-methylpentene-1 can be mentioned. Among the thermoplastic resins listed above, the present invention is particularly effective in producing a film of polyesters such as polyethylene terephthalate, its copolymer and polyethylene naphthalate.
The present invention is also effective for polysulfones and polyamides because it is effective regardless of the electrical resistivity of the thermoplastic resin when it is melted.

 Next, details of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic view of a cooling and solidifying apparatus of the electrostatic contact method according to the present invention, and FIG. 2 is an enlarged view of the vicinity of electrodes. (T) and (w) in the figure are the thickness and width of the blade electrode. In FIG. 1, a molten thermoplastic resin sheet (1) extruded from a die is cooled and solidified by an electrically grounded metal rotary cooling body (2) and then taken off. At this time, the blade-shaped electrode (3) is placed near the first contact of the molten sheet with the rotary cooling body, and a high voltage is applied. The blade-shaped electrode is arranged on the upper surface side of the film in a direction perpendicular to the flow direction of the film and slightly away from the die.
The direction of the blade is not particularly specified, but it is preferable that the blade width direction and the drum surface are close to vertical.

The thickness of the blade electrode of the present invention is 50μ at the edge portion.
m or less, preferably 40 μm or less, more preferably
It is 30 μm or less. If the thickness of the edge portion exceeds 50 μm, the effect is small and the advantage is small compared to the wire. The width of the blade electrode is 0.1 mm to 50 mm, preferably 0.2 mm to 40 mm. When the width of the blade electrode is 0.1 mm or less, the strength becomes too weak, and it is difficult to align the direction of the blade electrode uniformly, and the workability is poor. If the width of the blade electrode is 50 mm or more, it takes up too much space and is inconvenient to install.

The material of the blade electrode used in the present invention is various amorphous metals.

The composition of the amorphous metal is mainly composed of one or two or more kinds of transition metals such as iron, cobalt and nickel,
One or more metals selected from the group of metals such as beryllium, magnesium, aluminum, titanium, vanadium, chromium, manganese, copper, zinc, zirconium, niobium, molybdenum, silver, indium, platinum, and gold, and / or Or, a single element with or without addition of one or more non-metals / semi-metals selected from the group of non-metals / semi-metals such as boron, carbon, silicon, phosphorus, germanium and antimony, or The composition ratio can be selected from multiple elements and the like. For manufacturing, any known method can be adopted. Mainly gun method, piston anvil method, atomizing method, centrifugal quenching method,
The twin roll method, the single roll method, etc. can be mentioned.
The molten metal or alloy is cooled at a cooling rate higher than the critical cooling rate at which the metal or alloy becomes amorphous, and any manufacturing method may be used as long as the conditions are satisfied. Further, after cooling, post-treatment such as heat treatment may be performed.

The structure of the amorphous metal or amorphous alloy produced by such a production method is so-called glassy, and the arrangement of the constituent atoms has substantially no long-period order. Therefore, the X-ray diffraction pattern is halo-like and shows a pattern distinctly different from that of the crystalline metal. Amorphous blades preferably used in the present invention are mainly amorphous structure, preferably 50% or more is amorphous,
It may have a crystal structure partially.

As an example of the composition of the above amorphous blade, FeCo
SiB, CoCrSiB, FeCoCrSiB, Fe _75-85 B _15-25 , Fe
_75-85 P _10-16 C _4-10 , Fe _59-67 Cr _4-9 Mo _1-6 B
_27-29 , Fe ₇₈ B ₁₀ Si ₁₂ , Fe ₆₂ Mo ₂₀ C ₁₈ , Fe ₆₂ Cr ₁₂ Mo ₈ C ₁₈ ,
Fe ₄₅ Cr ₁₆ Mo ₂₀ C ₁₈ , Co ₇₃ Si ₁₅ B ₁₂ , Co ₅₆ Cr ₂₅ C ₁₈ , Co ₄₄ Mo
_Examples include ₃₆ C ₂₀ , Co ₃₄ Cr ₂₈ Mo ₂₀ C ₁₈ , Ni ₃₄ Cr ₂₄ Mo ₂₄ C _{18, and the} like. The above symbols are element symbols, and the subscript numbers represent the composition ratio (atomic%) or the composition ratio (atomic%) range. Those without a subscript represent an arbitrary composition ratio (atomic%). However, the present invention is not limited to this, and various composition ratios satisfying the requirements of the present invention are used. Moreover, the trace elements that are inevitably contained in practice are also arbitrary. Further, the blade electrode in the present invention uses an electrode supply-winding device as shown in FIG. 1 and can appropriately and continuously supply a clean portion in accordance with contamination of the electrode by a sublimate, molten resin or the like. Is preferred. Since the blade electrode of the present invention has a characteristic that the breaking stress is larger than that of a normal metal, it is possible to significantly reduce the loss of time required for replacing the electrode, etc., but by using such a device, further continuous use is possible. It will be possible.

The present invention has been described above, and its skeleton has a thickness of 50 μm.
By using the following amorphous metal blade electrode, there is no loss due to electrode deterioration, continuous operation is possible, electrostatic adhesion is enhanced, spark discharge is suppressed, and a film without thickness spots and defects is provided, and eventually film production. It is to improve speed. Therefore, the present invention is not limited to the embodiment shown in FIG. 1 and the contents described above, as long as this effect is not impaired. For example, a plurality of electrodes, heating the electrode, irradiating the contact portion with infrared rays, attaching a cover to at least a part of the upper surface or side surface of the electrode, or
It is also possible to use a combination of known techniques such as using a cooling body provided with an insulating layer in combination with a cooling body or a rotating cooling body having a roughened surface in a satin finish.

〔Example〕

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples unless it exceeds the gist.

Example A pellet of polyethylene terephthalate having an intrinsic viscosity of 0.66 was dried, then heated and melted at 290 ° C. by an extruder, and rapidly cooled using a cooling and solidifying apparatus shown in FIG. 1 to form a film.

At this time, as the rotary cooling body, a metal-made rotary roll having a diameter of 600 mm, the surface of which was chromium-plated and finished to be a mirror surface, was used. A blade made of Co ₃₄ Cr ₂₈ Mo ₂₈ C ₁₈ having a thickness of 20 μm and a width of 2 mm and being separated from the rotary cooling body by using a blade made of Co ₃₄ Cr ₂₈ Mo ₂₈ C ₁₈ while applying a DC voltage of 6 KV to the electrode and adjusting the extrusion amount and the width A 200 μm thick film was taken off.

When the rotation speed of the cooling roll was increased, a film having no defects was obtained up to 65 m / min.

 The electrode was used for one month and was never cut.

Comparative Example A test was conducted under the same conditions as in the example except that the electrode was a blade made of Ni having a thickness of 20 μm and a width of 2 mm.

When the rotation speed of the cooling roll was increased, binding bubbles were generated in the film at 64 m / min. The electrode was cut 11 times by using it for one month.

〔The invention's effect〕

As described above in detail, the present invention has the edge thickness of 50 μm.
By performing the following amorphous blade electrode,
The continuous production is possible, the electrostatic adhesion is enhanced, the production speed can be improved, and the productivity can be dramatically improved, and the industrial significance of the present invention is great.

[Brief description of drawings]

FIG. 1 is a schematic explanatory view of a cooling and solidifying apparatus for carrying out the present invention. FIG. 2 is an enlarged side view of the vicinity of the electrode of the present invention. In the figure, (1) is a molten thermoplastic resin sheet, (2) is a rotary cooling body, (3) is a blade electrode, (4) is an electrically insulating tube, (5) is an electrode supply roll, and (6) is electrode winding. The taking roll is shown. Further, (w) is the width of the blade electrode, (t)
Indicates the thickness of the blade electrode.

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Masaji Watanabe Inventor, Masaji Watanabe, 1000 Kamoshida-cho, Midori-ku, Yokohama-shi, Kanagawa Daifoil Co., Ltd. Research Laboratory (56) Basics of Amorphous Metals "(November 25, 1982) Ohmsha Co., Ltd. 201-222

Claims (1)

[Claims] 1. A method of extruding a molten thermoplastic resin from a die and cooling and solidifying by an electrostatic application adhesion method to form a sheet, wherein an edge portion has a thickness of 50 μm or less and a width of 0.1 to 5;
A method for forming a thermoplastic resin sheet, characterized by using an amorphous metal having a thickness of 0 mm as an electrode.