JP3449050B2 - Method for producing thermoplastic resin film - Google Patents

Description

Detailed Description of the Invention

[0001]

The present invention relates relates to a method for producing a thermoplastic resin film. More specifically, we manufacture thermoplastic resin films with less coarse protrusions used in base films for magnetic tape than thermoplastic resins with fillers and thermoplastic resin films with improved electrical properties used in dielectrics for capacitors. directed to a method of.

[0002]

2. Description of the Related Art Among thermoplastic resin films, polyethylene terephthalate, polyethylene 2, which have high functionality in mechanical properties, thermal properties, electrical properties, etc.
Films based on 6-naphthalate, polyphenylene sulfide, polypropylene, polystyrene, polyamide, aramid, etc. are preferably used for magnetic materials, capacitors, electrical insulation, thermal transfer ribbons, stencil printing applications and the like.

These thermoplastic resin films are generally manufactured in a wide width, wound into a roll, and processed by a method such as coating, printing, vapor deposition, and sputtering. Not only the characteristics of the final product of these thermoplastic resin films but also the good processability in these processing steps are important quality characteristics. In recent years, in particular, attempts have been made to improve the workability and improve wear resistance by adjusting the surface roughness of the thermoplastic resin film by appropriately adding a filler, and the surface of the thermoplastic resin film In order to meet the requirements for flatness and smoothness and the requirements for good slipperiness and wear resistance, special attention is paid to the material of the filler to be added, the state of forming fine particles, the size, and the addition amount ( For example, Japanese Patent Laid-Open No. 6-322243). In addition, various methods for improving the dispersed state of these fillers at the thermoplastic resin production stage have been proposed (for example, JP-A-2-11636 and JP-A-6-322242).
Issue Bulletin). In particular, the flatness of the film surface as well as the smoothness are strongly demanded for magnetic material applications, capacitor applications, etc., and there is a great interest in selection in consideration of the properties of these fillers themselves.

[0004]

In view of these problems, the present inventors have proposed a method in which the addition of an inorganic and / or organic filler to a thermoplastic resin does not impair the film quality such as flatness and smoothness. The present invention has been accomplished as a result of intensive research.

Workability, that is, the quality represented by the surface roughness and slipperiness of the thermoplastic resin film, and the required quality of the final product, that is, the flatness, smoothness, abrasion resistance, and electrical characteristics of the thermoplastic resin film. The quality represented by (1) depends on the characteristics of the filler added together. In particular, the average particle size of the filler may be used as an index representing these characteristics.

In view of the relationship between the quality of these thermoplastic resin films and the particle size of the filler, the present inventors have noticed that the particle size slightly larger than the average particle size of the added filler determines these qualities. The present invention has been reached.
Needless to say, the particle size distribution and the average particle size that determine the quality are obtained by controlling the particle size distribution in the filler manufacturing stage and / or the thermoplastic resin manufacturing stage to distribute the particle size distribution in the narrowest possible range. It is possible to make the diameters substantially the same, but even if the particles thus adjusted are used, the particles are re-aggregated when melted again by using the extruder for film formation, and the target is obtained. It may be difficult to obtain a flat and smooth surface of the thermoplastic resin film.

An object of the present invention is to relatively easily obtain a film having a target quality by physically cutting a filler which is coarser than the average particle diameter of the filler added to the thermoplastic resin by, for example, several times or more. It is in.

Another object of the present invention is to improve the dispersibility of particles in a thermoplastic resin film containing agglomerated particles.

[0009] Still another object of the present invention is to provide a filter which has a higher filtration pressure than conventional filters which remove gels, foreign substances, etc. in order to cut coarse particles of the filler, and which has improved filtration ability. To do.

Still another object of the present invention is to provide a base film for magnetic materials having few coarse projections, a base film for capacitors having improved electric characteristics, and the like.

[0011]

The above object can be achieved by the following means. That is, a thermoplastic resin containing at least one inorganic and / or organic filler having an average particle diameter of δ μm and a standard deviation σ of the particle diameter of 0.1δ or more is melted by using an extruder, and the molten thermoplastic resin is , The filler and the filtration accuracy ημm satisfy the expression (1), and the diameter d _n μm of the metal fiber of the n-th medium and the basis weight w _n g
/ M ² product (w _n · d _n ) satisfies the equations (2) and (3), and the porosity is such that the axis of the metal fiber is arranged in the direction orthogonal to the flow of the molten thermoplastic resin. with laminated 35-90% of media, the basis weight ^{_{w p g / m 2 (4}} )
Air flow resistance r of 35 to 80 is obtained by laminating one or more layers of media made of metal powder satisfying the formula and having a porosity of 25 to 65% on the downstream side of the media made of the metal fibers.
The method for producing a thermoplastic resin film is characterized in that after filtering through a filter of 0 mmH ₂ O, it is discharged from a die and rapidly cooled to form a sheet.

In the above, 2.5 <η / δ <50 (1) 400 < (w _n · d _n ) <16000 (2) 0.2 ≦ (w _{n + 1} · d _{n + 1} ) / (w _{n · d n) ≦ 2.5 (} 3) 500 ≦ w p ≦ 20000 (4) where n is the medium number of the upstream side of the laminated media constituting the filter.

For the filter, a filter composed of a medium obtained by sintering metal fibers and metal powder is used.
The metal fiber and / or metal powder is preferably made of stainless metal.

The melt viscosity of the thermoplastic resin when passing through the filter is preferably adjusted to 200 to 12000 poise.

The primary particle size is 0.01 to 1 μm, the average particle size δ is 0.2 to 3 μm, and the standard deviation σ is 0.2.
The center line average roughness Ra, the 10-point average roughness Rz, and the maximum roughness Rmax of the film surface using a thermoplastic resin containing one or more aggregated fillers of δ or more are Rmax ≦ (2δ) ^1/3 Rz Rz ≦ It is possible to produce a thermoplastic resin film having a 10 δ ^1/2 Ra and a Ra of 10 to 200 nm, which is suitable as a base film for capacitors. Average particle size of the filler in this film θ
Is 1/2 or less of the average particle diameter δ of the filler in the thermoplastic resin, and its standard deviation ψ is 0.6θ or less.

Further, the average particle size δ is 0.01 to 1 μm.
And the center line average roughness Ra of the film surface using a thermoplastic resin containing one or more fillers having a standard deviation σ of 0.1δ or more is 15 nm or less, and there are 5 coarse projections of H2 or more /
It is possible to produce a thermoplastic resin film having a size of 100 cm ² or less, which is suitable as a base film for magnetic materials.

In addition, in these thermoplastic resin films, it is preferable that after being formed into a sheet, it is stretched in the longitudinal and / or transverse directions and heat-fixed to obtain a uniaxially or biaxially stretched film. Is preferably 0.5 to 25 μm in the case of a biaxially stretched film.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below along with preferred embodiments. Examples of the thermoplastic resin used in the present invention include polyesters such as polyethylene terephthalate and polyethylene 2,6-naphthalate, which are highly functional thermoplastic resins in terms of mechanical properties, thermal properties, electrical properties, etc., and polyphenylene sulfide. , Polypropylene, polystyrene, polyamide, aramid and the like are preferable. The present invention particularly melt-extrudes a thermoplastic resin into a sheet, further biaxially stretched in the longitudinal and transverse directions, and subjected to heat treatment for dimensional stability, for magnetic materials excellent in mechanical and thermal stability,
It is suitable for thermoplastic resin films used for capacitors, electrical insulation, thermal transfer ribbons, stencil printing applications and the like.

In the present invention, an inorganic and / or organic filler is used to improve the final quality and handleability. The final quality here means the quality in the form of functioning as a product. In other words, in the case of magnetic material applications, recorded or recorded material is reproduced more faithfully, and flatness required for the base film, formation of uniform protrusions, restriction of coarse protrusions, heat -It refers to all quality characteristics such as mechanical stability and head touch. In addition, taking capacitor applications as an example, it means that the capacitors function as designed after they have been installed in equipment, such as withstand voltage characteristics, frequency characteristics, capacity uniformity, and stability against thermal and mechanical shocks. Refers to the quality characteristics of. Further, the handling property is a quality in the middle of processing for achieving the final quality. That is, taking magnetic materials as an example, the suitability of the magnetic powder coating process is good, the winding characteristics of the tape are good, high-speed dubbing is possible, and there are no wrinkles, scrapes on the surface, or falling off during these processing processes. is there. In addition, taking a capacitor application as an example, wrinkles during vapor deposition processing and wrinkles due to heat are less likely to occur, and the winding characteristics are good, and the element winding characteristics of the capacitor are good. All of these characteristics are represented by the surface roughness and slipperiness of the film as the quality characteristics of the base film, but they can also be expressed by secondary characteristics represented by air entrainment and surface adhesion. is there.

As the inorganic filler used in the present invention,
There are inorganic inert particles such as silicon dioxide, titanium dioxide, zirconium dioxide, calcium carbonate, alumina, talc and kaolin. In addition, an aggregate of these inert particles may be used. Furthermore, as an organic filler,
Particles of high heat-resistant polymer such as styrene, silicone, polymethylmethacrylate, and polyamideimide are preferable, and these organic fillers may be used alone or in combination with the inorganic filler.

The average particle size of the filler used in the present invention is
The range of 0.01 to 3 μm is preferable. If it is 0.01 μm or less, the degree of improvement of the film surface in the processing step and the quality of the final product becomes small even if the filler is added, and if the addition amount is increased in order to exert the effect, the subsequent stretching step. It is easy to cause uneven thickness,
It is not preferable because it easily breaks and the stretching becomes difficult. On the other hand, if it is larger than 3 μm, it may be too large in relation to the thickness of the film as the final product, and it is not possible to apply the thermoplastic resin containing such a filler to the preferable thickness and the required quality of the film of the present invention. Not practical.

When a type having a very smooth surface such as a magnetic material is required, the filler to be added is a monodisperse filler having an average particle diameter of 0.01 to 1 μm.
It is preferable to add one or more kinds of the above fillers. on the other hand,
For a relatively rough surface type such as a capacitor application, an aggregate filler can be appropriately used in addition to the monodisperse filler. In this case, it is preferable that the average particle size (primary particle size) of the monodisperse filler is 0.01 to 1 μm and the average particle size of the aggregated filler is 0.2 to 3 μm. In addition, in the present invention, regarding the particle size when several kinds of particles are added, the average value of the larger particle size distribution is referred to as the average particle size. Here, if the average particle size of the aggregated particles is 0.2 μm or less, no effect is obtained. Also 3μ
When it is m or more, the load applied to the filter becomes too large when the filtration according to the present invention is used, which is not practical.

In addition to the average particle diameter δ, the filler used in the present invention has a standard deviation σ of 0.
It is 1 δ or more, and the present invention is intended for those to which such a filler is added. If the standard deviation is 0.1δ or less, the particle size distribution is limited to a narrow range, so that it is effective in dispersing the filler re-aggregated after melting in the extruder. There is no major reason to "filter coarse particles that are several times coarser than the average particle diameter by a filter".

The preferred amount of filler added is 0.
The content is 001 to 1% by weight, but if the filtration capacity is sufficient, the content may be used without being limited to this range. Of course, 0.
If it is 001% by weight or less, the effect of adding a filler is not obtained. still,
In the filler manufacturing stage or the thermoplastic resin manufacturing stage, the filter of the present invention is used to control the distribution of the filler by cutting coarse particles of several times to several tens times the average particle size, and melting the sheet using an extruder. It is more effective and preferable to use the method of the present invention to discharge from a wide die when molding.

The media layers composed of metal fibers are arranged so that the axes of the metal fibers are parallel to the media layers, that is, in a direction (perpendicular direction) orthogonal to the flow of the molten thermoplastic resin. The effect of the invention becomes remarkable. If the metal fiber axis is arranged in a direction other than the direction perpendicular to the flow, it seems that the porosity of the medium becomes large, which is preferable, but there is a loss in the space between the metal fibers effective for filtration. However, the function of the present invention of laminating extremely thin layers and filtering with high precision is lost, which is not preferable.

Further, the medium composed of the metal fibers is constructed so that the material diameter and the basis weight satisfy the relations of the above expressions (2) and (3). Equation (2) shows that, for example, when a material with a large diameter is used in a medium requiring strength, the weight of the material is reduced, and a material with a small diameter is used for the medium for controlling the filtration accuracy, and the weight of the material is increased. is important. In the present invention, the range of the expression (2) is set to be larger than 400 and less than 16000. If it is less than 400, sufficient filtration cannot be performed, which is not preferable. Also, 160
When it is 00 or more, the density of the filtration layer in the thickness direction increases, and the efficiency of filtration inside decreases, which is not preferable.

The equation (3) shows the overall state of the media constructed by stacking, and is important for achieving effective filtration. The number of layers is not particularly limited as long as it is 2 or more, but preferably 3 or more, more preferably 4 or more. In addition, it is preferable to stack several tens of layers so that (w · d) is continuous so that a large filtration capacity can be obtained.

The porosity of these media is 35 to 9
It is 0%. It is preferably 50 to 80%, more preferably 65 to 75%. If it is less than 35%, it becomes difficult to carry out effective filtration, which is not preferable. On the other hand, when it is 90% or more, the medium cannot withstand the filtration pressure, which is not preferable. Furthermore, the difference in porosity between adjacent media to be stacked is 1
5% or less, more preferably 10% or less,
It is not limited to this.

The basis weight of each medium is 100-
10000 g / m ² is preferred. It filtration is less than 100 g / m ² is not enough, since the filtration clogging exceeds 10000 g / m ² is increased undesirably. Here, the basis weight is the weight per unit filtration area of the material forming the medium. The material diameter is 0.5 to 30 μm. If it is less than 0.5 μm, it is not realistic because it is difficult to obtain the material. Further, if it exceeds 30 μm, it is difficult to obtain the filtration accuracy targeted by the present invention, which is not preferable. Here, the material diameter of the metal fiber is usually its average diameter, and when a different diameter material having a major axis and a minor axis in the form of a metal fiber is used, the minor axis is referred to as the material diameter.

In the present invention, a medium formed by sintering metal powder is laminated on the downstream side through which the thermoplastic resin passes, in addition to the medium formed by laminating the metal fibers constructed as described above. That is, the weight of the metal powder is 500 to 20
Sinter and laminate so that the porosity is 25 to 65% at 000 g / m ² . It is preferable to sinter the metal powder from a spherical powder of 2 to 200 μm obtained by an atomizing method or the like, but not limited to this. Further to hardly out effect basis weight of the metal powder are stacked is less than 500 g / m ^2, since taking carelessly large volume as compared with the metal fiber layer which determines the inherent filtration accuracy and ability exceeds 20000 g / m ² Not preferable. Preferably 800-10,000
g / m ² , more preferably 1000 to 5000
It is g / m ² . If the porosity is less than 25%,
If the laminated thickness is not thin enough to bring out the effect of this media layer, the pressure loss becomes large. If it exceeds 65%,
The binding force between the metal powders is weakened, and the metal powders fall off during use, which is not preferable. Preferably 30-
60%, more preferably 35-55%.

In the present invention, the above-mentioned lamination may be carried out by laminating individual media after sintering, or by forming the metal fibers and / or metal powders constituting the individual media into, for example, a non-woven fabric layer and then integrally forming the same. You may sinter.
The term "sintering" as used herein means that powder particles are bonded at a temperature lower than the melting point of the substance, and its characteristics are described in detail, for example, in "Handbook of Metals (edited by The Japan Institute of Metals, published by Maruzen)". As is done.

Here, the purpose of using the media obtained by sintering the metal powder is to have the function of receiving the filtering pressure generated in the media of the fine metal fibers as the upper layer, and also to pass the metal fibers through the sintered layer. The filler in the uniformly filtered thermoplastic resin flows in a hollow tunnel having a complicated cross section formed by sintering of metal powders as shown in FIG. 1, which will be described later. It is thought that this is because there is a function to disperse fillers etc. in order to generate a complicated velocity distribution. For the above-mentioned purpose, the metal powder sintered layer in the present invention is to be laminated on the downstream side of the metal fiber layer, but is laminated on the most upstream side of the metal fiber layer, and the filler is finely divided in advance for filtering accuracy. It is also possible to lead to fine metal fiber layers. However, in consideration of the speed of filter clogging, it is preferable to stack the metal powder sintered layer after accurate filtration as in the present invention, because there is an advantage that the thickness of the metal powder layer can be reduced. .

The filtration accuracy is determined by the gap between the metal fibers and / or metal powders and the length of passage of the thermoplastic resin. The filler added to the thermoplastic resin is added to the thermoplastic resin film by the method of the present invention. It is important to exist and most effectively achieve the desired quality characteristics. Filtration accuracy should be determined from the thickness of the thermoplastic resin film, the size of the filler used, and the required quality. When more flatness and smoothness are required, filtration accuracy of 10 μm or less, flatness and smoothness 5μ if required
A filtration accuracy of m or less may be required. Further, when a film having an ultra-smooth surface is required, a filter having a filtration accuracy of 1 μm or less can be used, and further 0.5
It is also possible to use a filter having a filtration accuracy of μm or less. on the other hand,
When a film having a rough surface is required, a film having a filtration accuracy of 30 μm or less may be used.

Further, in the present invention, the average particle diameter and filtration accuracy of the filler used in the thermoplastic resin are the same as those described in (1) above.
It is necessary to maintain the relation of expressions. Here, the filtration accuracy means a particle diameter (μm) in which 95% of the 11 kinds or dust ACFTD defined in JIS-Z8901-1974 is cut. That is, in equation (1),
The present invention is achieved by filtering 95% or more of particles on the side that is more than 2.5 times and less than 50 times larger than the average particle diameter of the filler. That is, it is important to physically remove particles on the rougher side than this range. (1)
The range of the formula is preferably 3 to 30, more preferably 4 to
Twenty. When it is 2.5 or less, the load for filtering the filler becomes extremely high, which is not preferable. On the other hand, when it is 50 or more, the effect of the present invention becomes difficult to obtain, which is not preferable. on the other hand,
The formula (1) also represents the difficulty of the filler passing through the filter, and is preferable because the filtering operation becomes easy when the selection of the filler and the filtering accuracy are sufficiently considered according to the present invention.

Further, the filter of the present invention has an air flow resistance value in the range of 35 to 800 mmH ₂ O. In the case of a medium exhibiting a flow resistance of less than 35 mmH ₂ O, the effect of cutting coarse particles of the added filler and the dispersion effect of aggregation are poor, and the collection efficiency is also poor. Further, if the flow resistance value by air exceeds 800 mmH ₂ O, the filtration resistance is too high and it becomes difficult to pass the molten thermoplastic resin, which is not preferable. Preferably, 50~600mmH ₂ O,
More preferably, it is 60 to 500 mmH ₂ O.

By using the filters thus laminated, the number of filters to be used is reduced, for example, when the filters made of the medium of the present invention are housed in a casing having the same volume, and the apparent filtering area is reduced. The smaller the filter, the greater the substantial filtration capacity.

As the metal of the filter medium used in the present invention, stainless steel, bronze, copper or the like can be used, but from the viewpoint of activity with a thermoplastic resin and recycling and reuse, stainless steel is preferable. Among stainless steel, SUS304, SUS316, SUS316
L, SUS430 and the like are preferable, but not limited thereto.

The extruder that can be used in the present invention is, for example, a screw type extruder, and it is preferable to use a single-screw or twin-screw extruder.
It is important that uniform melting can be achieved without the abnormal temperature rise as described above.

The range of the melt viscosity of the thermoplastic resin which can be filtered through the filter in the present invention is, for example, 200.
Adjusted to a range of ~ 12000 poise. When it is less than 200 poise, the filter of the present invention does not increase the filtration resistance and it becomes difficult to effectively utilize the entire surface of the medium of the present invention, which is not preferable. On the other hand, if the melt viscosity is more than 12000 poise, filtration resistance through the filter of the present invention becomes too high, which increases the risk of deformation of the media and collapse of the media layer, which is not preferable. The viscosity of the thermoplastic resin changes depending on the molten state. That is, since the melt viscosity changes depending on the molecular weight and the melting temperature of the thermoplastic resin, for example, when passing through a filter configured as in the present invention, the melt viscosity is controlled to be adjusted to 200 to 12,000 poise. is important. By doing so, the filtration resistance becomes abnormally high, causing damage to the filter, and the non-uniform flow of the molten thermoplastic resin that occurs when the filtration resistance becomes abnormally low is prevented, and a uniform thermoplastic resin is discharged. It becomes possible to use it in an optimum state including the collection efficiency of the filter.

An apparatus for adjusting the melt viscosity of the molten thermoplastic resin to the melt viscosity of the present invention is, for example,
A general method is to control the external heating temperature of the extruder. A thermometer is installed in front of the filter device, and the viscosity can be calculated from the temperature of the molten thermoplastic resin according to the temperature-viscosity relationship, and can be fed back to the temperature control unit of the extruder for adjustment. As a more preferable adjusting method, it is preferable to adjust the viscosity of the molten thermoplastic resin immediately before entering the filter, because it can be easily adjusted, the adjustment range is widened, and thermal deterioration of the thermoplastic resin can be suppressed. That is, with a jacket capable of heating and cooling at the same time, by passing through a melt viscosity adjusting device having a structure capable of exchanging heat with a thermoplastic resin inside,
The melt viscosity can be adjusted by adjusting the temperature of the thermoplastic resin in a short time. Use a static mixer, etc. to prevent uneven temperature in the thermoplastic resin after heat exchange.
It is more preferable to install the temperature control device inside or on the outlet side. Also in the present melt viscosity adjusting device, the temperature of the thermoplastic resin is detected on the outlet side thereof, and is fed back to the temperature control unit for adjustment according to the temperature-viscosity relationship.

In the above description, it is preferable to enclose a liquid in the jacket for facilitating heat exchange from the viewpoint of heat exchange efficiency and temperature unevenness, and circulate the liquid between the temperature control unit, but not limited to this. A heat exchange system combining an electric heater, air, water, etc. may be used. Further, the melt viscosity adjusting device used in the present invention is preferably applied to the thermoplastic resin after passing through the filter so as not to be held at an abnormally high temperature for a long time. The time is not limited to this as long as the time until the ejection is short.

Further, it is advisable to detect the pressure of the molten thermoplastic resin before entering the filter device to prevent an abnormally high pressure from being applied to the filter and to install a pressure gauge for detecting clogging of the filter.

The die in the present invention is preferably used in a T-shape, a coat-hanger shape, a fishtail shape and the like. Further, two or more extruders may be installed on the upstream side of the die in the present invention, and a type of laminating using a feed block or a die of laminating in the die may be used. As a matter of course, the filter according to the present invention can be used between each of these extruders and the die to perform the filtration that is the object of the present invention.

The thermoplastic resin sheet can be molded by discharging it onto a rotating drum whose temperature is controlled below the glass transition temperature of the thermoplastic resin and quenching it. In order to improve the cooling efficiency, it is preferable to use an electrostatic casting method, a method of spraying an air jet, a method of forming a thin water film on the drum, or the like so as to bring them into close contact with the rotating drum, because the rapid cooling efficiency increases.

Further, the thermoplastic resin sheet is heated to a temperature near the glass transition temperature or higher by a longitudinal stretching machine, longitudinally stretched 3 to 7 times, and both ears are gripped by clips and guided to a horizontal stretching machine. Similarly, a biaxially stretched thermoplastic resin film of extremely high quality can be obtained by being heated above the glass transition point temperature, laterally stretched 3 to 5 times, and thermally fixed at a temperature below the melting point.

[0046]

EXAMPLES The present invention will be described in detail below with reference to examples. The measuring method used was as follows. (1) Average particle diameter of filler, standard deviation The area of particles is determined from a transmission electron micrograph, and the average value and standard deviation of all observed particles are determined as the diameter of a circle having the same area.

(2) Average particle size and standard deviation of filler in the film The thermoplastic resin film on the surface of the thermoplastic resin film was removed by a plasma method, and a scanning electron microscope photograph was taken to determine the area of the particles. As the diameter of the circle, the average value and standard deviation of all observed particles are calculated.

(3) Filtration accuracy test 11 kinds of powder JIS-Z8901-1974 or dust ACFTD were dispersed in distilled water, the particle size distribution was measured by HIAC, and compared with the particle size distribution after passing through the filter. The 95% cut value is taken as the filtration accuracy.

(4) Porosity The volume of the space is calculated from the volume of the medium, the amount of the material used, and the specific gravity, and expressed as a percentage.

(5) Unit weight The weight of the material used per unit filtration area of the media is expressed (unit: g / m ² ).

(6) Material diameter The material diameter of the particles is measured by a micrograph and the average diameter is determined. In the case of different diameters having a long diameter and a short diameter, the short diameter is measured and the average diameter is used.

(7) Section of Filter Media After the filter media is hardened with epoxy resin, it is cut along the longitudinal or flat section of the media, and the cut surface is polished, and then a metallographic photograph is taken to locate the metal fiber axis.
Observe the material diameter and the state of voids.

(8) Flow resistance A pair of hemispherical upper and lower cups having holes for allowing air to flow seal the outer circumference of a filter having an effective diameter of 40 mm to 0.5
l / min.・ Read the difference between the air pressures in the upper and lower cups with a manometer when flowing cm ² of air.

(9) Surface roughness Ra, Rz, and Rmax are measured at 10 points with a length of 4 mm and a cutoff of 0.8 mm in accordance with JIS-B0601, and the average is taken.

(10) Dielectric Breakdown Voltage Electrical insulation characteristics are measured by the element method according to JIS-C2318, and the average breakdown voltage at that time is compared.

(11) Intrinsic viscosity Measured at 25 ° C. using orthochlorophenol as a solvent.

(12) Melt viscosity The viscosity of the heat-melted thermoplastic resin is measured by a Koka type flow tester to prepare a calibration curve of a temperature-viscosity curve.
The viscosity of the thermoplastic resin when melted is calculated from the calibration curve by detecting the temperature.

[0058] (13) Paste the thermoplastic resin film to large projections smooth glass cylindrical surface, a Newton ring (interference fringe) which can when irradiated with light of a sodium lamp and microscopic observation, the above double ring
The number of coarse protrusions that form Newton rings (H2 or more) is counted for an area of 100 cm ² .

[Example] The material of the filter is SUS
316L stainless steel fiber with various wire diameters and SUS43
The metal powder of No. 0 was used, and the media shown in Tables 1, 3, and 5 were laminated and constituted and sintered. The upper side of the table is the upstream side. The flow resistance due to air at this time is shown in the same table, and a typical example of a vertical cross section of the media layer made of metal fibers and a flat cross section in the direction perpendicular to the flow (axial direction of the metal fibers) is shown in FIG. In the photomicrograph of FIG. 1, the white portion represents the cross section of the metal fiber or metal powder, and the photo on the left side shows 1 from the upstream side.
A longitudinal section of a filter having 01, 102, and 103 portions is shown, and the photograph on the right side shows each portion 10
The cross-sectional view (plan cross-sectional view) in the plane direction (parallel to the filter surface) of 1, 102, 103 is shown.

In the filter device, as shown in FIG. 2, the media are the upstream metal fiber media 1 and 1 ', and the downstream metal fiber media 2,
2 ', the media 3 and 3'of the metal powder on the downstream side, are molded into a disk-shaped filter having a diameter of 12 inches, two disk-shaped filters are combined, and the filtration pressure is applied to the inside of the two filters. Made of SUS30 as a support to withstand the heat and ensure a space through which the molten thermoplastic resin can flow.
4 is welded to the outer periphery (welded portion 5), and a seal ring 6 having a circular discharge hole 7 in the central portion is welded to the inner peripheral portion (welded portion 5 '). Molten thermoplastic resin Were collected in the central portion in the radial direction of the filter.

The disk-shaped filter 10 is overlaid in FIG.
The filter device was assembled as follows. In FIG. 3, a plurality of disc-shaped filters 10 are stacked and assembled by using a plurality of filter trees 30 as a support, and housed in filter casings 20 and 20 '. The molten thermoplastic resin is introduced through the thermoplastic resin introduction hole 40, filtered by each filter 10, and then the thermoplastic resin discharge hole 5
Emitted from 0.

As shown in FIG. 4, a single-screw extruder 60 having a diameter of 90 mm is used as the extruder, and its motor 61 is used.
By controlling the number of rotations of No. 2 via the motor control device 62, the number of rotations of the squeeze, the melting of the raw material charged from the hopper 63, the discharge amount, etc. were controlled. Further, as a melt viscosity adjusting device 70 for the thermoplastic resin, a high mixer 71 equipped with a jacket 72 for circulating a liquid for temperature control was used to pass through this and adjust the viscosity of the thermoplastic resin. The conversion of temperature-viscosity is obtained by measuring the viscosity in advance with a flow tester for each type of thermoplastic resin, inputting a calibration curve into the computer, converting it from temperature to viscosity, and calculating the difference from the desired viscosity. The required temperature was fed back to the liquid temperature control unit.

Further, a pressure detecting device 81 is installed at the inlet of the filter device 80 to measure the pressure applied to the filter and to stop the motor 61 of the extruder when an abnormally high pressure is applied. I tried to activate the lock. In addition, the pressure at the inlet of the filter device 80 is 250 kg after the thermoplastic resin starts passing through the filter.
The total passing amount up to / cm ² was calculated from the rate of increase of the pressure, and was taken as the filtration capacity per unit filtration area. As the wide base 90, a T-shaped base with a width of 550 mm is used.
It was discharged onto a cooling drum 92 as a rotary cooling body having a diameter of 700 mm. The surface temperature of the cooling drum 92 was 25 ° C. In addition, electrostatic pinning 91 was used to bring the thermoplastic resin sheet into close contact with the drum 92.

Examples 1 and 2 (Tables 1 and 2) As the thermoplastic resin, agglomerated silica having a primary particle diameter of 0.02 μm, an average particle diameter of 2.6 μm and a standard deviation of 0.5 μm was used. Polyethylene terephthalate having an intrinsic viscosity of 0.62 added with 2% by weight and 0.15% by weight of aluminum silicate having an average particle diameter of 0.4 μm was used (Example 1). Further, 0.1% by weight of agglomerated silica having a primary particle diameter of 0.02, an average particle diameter of 1.8 μm and a standard deviation of 0.4 μm, and 0.2% of an aluminum silicate having an average particle diameter of 0.4 μm. Polyethylene terephthalate having an intrinsic viscosity of 0.63 added with weight% was used (Example 2). It was dried by a conventional method, melt-extruded at 280 ° C. by the extruder, and then filtered through a viscosity adjusting device and a filter device. Table 1 shows the constitution and characteristics of the filter used for filtration and the adjustment of the thermoplastic resin. Then, it was rapidly cooled with a rotary cooling body, stretched 4.5 times at 110 ° C. in a longitudinal stretching machine, and further stretched 3.8 times at 115 ° C. in a transverse stretching machine,
It was heat set at 200 ° C and cooled at 150 ° C. It was relaxed by 3% in the transverse direction from heat setting to cooling to obtain a 2.0 μm biaxially stretched polyethylene terephthalate film. Table 2 shows the withstand voltage characteristics of the capacitor element prepared along with the film characteristic values.

Comparative Examples 1, 2 and 3 (Tables 1 and 2) Using the polyethylene terephthalate having the same formulation as Examples 1 and 2, respectively, the media of Comparative Examples 1, 2 and 3 shown in Table 1 were used for the filter device. Discharged on a rotary cooling body in the same device as in the example using, with the characteristic values of polyethylene terephthalate film heat-fixed biaxially stretched after molding,
A capacitor element was prepared and its withstand voltage characteristics are shown in Table 2. Here, in Comparative Example 2, a filter composed of a single-layer medium obtained by sintering metal fiber made of SUS316L was used. Further, in Comparative Example 3, a filter composed of a single-layer medium obtained by sintering SUS430 metal powder was used.

Examples 3, 4, 5 (Tables 3 and 4) As a thermoplastic resin, 0.2% by weight of synthetic silica particles having an average particle diameter of 0.12 μm was contained, and further the average particle diameter δ and its standard deviation. σ is 0.1 for each calcium carbonate particle in Table 4.
Intrinsic viscosity (IV) added by 5% by weight is 0.61 to 0.6
Dry polyethylene terephthalate of 3 by a conventional method,
After melt-extruding at 280 ° C. in the extruder, it was filtered through a viscosity adjusting device and a filter device. Table 3 shows the constitution and characteristics of the filter used for filtration.

Then, it was rapidly cooled with a rotary cooling body, stretched 3.6 times at 98 ° C. by a longitudinal stretching machine, and further 105 ° C. by a transverse stretching machine.
Stretched to 3.9 times and heat-set at 200 ° C for 150
Cooled at ° C. 3.3 laterally from heat setting to cooling
%, A biaxially stretched polyethylene terephthalate film having a thickness of 7 μm was obtained. Characteristic values such as surface roughness and surface protrusion at the start and end of passage are shown in Table 4.

Comparative Examples 4, 5, 6 and 7 (Tables 3 and 4) Using the same filters as in Example 3, the average particle size was 1.4.
Polyethylene terephthalate containing a filler having a standard deviation of 0.3 μm and a standard deviation of 0.3 μm (Comparative Example 4), the same polyester as in Example 3 was used in the filter of Comparative Example 5, and the same polyester as in Example 3 was used in Comparative Example 6. Using a filter, the polyester of Example 4 was passed through the filter of Comparative Example 7 and discharged onto a rotary cooling body by the same device as that of Example, and after molding, biaxially stretched and heat-fixed polyethylene terephthalate film was prepared. The characteristic values are shown in Table 4. Here, the filter of Comparative Example 7 is a filter composed of a single layer medium of SUS316L metal fiber.

Comparative Example 8 In Example 3, the temperature of the viscosity adjusting device was adjusted so that the melt viscosity was 170 poises. Since the molten thermoplastic resin discharged from the die did not flow evenly through the filter,
The sheet could not be formed due to uneven viscosity and uneven color.

Comparative Example 9 The polyethylene terephthalate of Example 3 was placed in a heating and depressurizing apparatus before the drying thereof and solid-phase polymerized to obtain an intrinsic viscosity of 0.82. When the temperature of the extruder and the viscosity adjusting device was set to 290 ° C. and fed into the filter device of Example 3, the pressure gauge at the inlet became 250 kg / cm ² or more, the interlock was turned on, and the motor of the extruder stopped. The melt viscosity at this time was 13,000 poise in conversion.

Example 6 As a thermoplastic resin, the primary particle size is 0.02 μm, the average particle size is 2.0 μm, and the standard deviation is 0.5 μm. 0.4 μm
Containing 0.2% by weight of calcium phosphate has an intrinsic viscosity of 0.
Polyethylene terephthalate (63) was dried by a conventional method, melt-extruded at 285 ° C. by the above extruder, and then filtered through a viscosity adjusting device and a filter. The constitution and characteristics of the filter used for filtration are shown in Table 5.

After that, it was rapidly cooled with a rotary cooling body, and 1 with a longitudinal stretching machine.
The film was stretched 3.3 times at 00 ° C., further laterally stretched at 110 ° C. 3.6 times, heat-set at 225 ° C., and cooled at 150 ° C.
Relaxed 3% laterally from heat setting to cooling, 1.2
A polyethylene terephthalate film having a thickness of μm was obtained. The characteristics and withstand voltage characteristics are shown in Table 6.

Comparative Example 10 (Tables 5 and 6) Polyethylene terephthalate having the same formulation as that of Example was used, passed through the filter of Table 5, and discharged onto a rotary cooling body by the same apparatus as that of Example. Table 6 shows the characteristics and withstand voltage characteristics of the polyethylene terephthalate film that was axially stretched and heat-set.

[0074]

[Table 1]

[0075]

[Table 2]

[0076]

[Table 3]

[0077]

[Table 4]

[0078]

[Table 5]

[0079]

[Table 6]

[0080]

According to the present invention, the target film quality can be relatively easily obtained by physically cutting the filler coarser than the average particle diameter of the filler added to the thermoplastic resin.

Further, the dispersibility of particles of the thermoplastic resin film containing agglomerated particles is improved, and the appearance of large protrusions can be prevented.

Further, since the coarse particle portion of the filler is cut, the filter having a higher filtration pressure than the conventional filter excluding gels, foreign matters, etc., and having improved filtration ability can be provided.

Further, it is possible to easily provide a base film for magnetic materials with few coarse protrusions, a base film for capacitors with improved electric characteristics, and the like, while satisfying both processability and required quality.

[Brief description of drawings]

FIG. 1 shows a vertical cross section of a filter composed of a medium obtained by sintering a metal powder layer on a metal fiber layer used in the present invention and a plane cross section in a direction perpendicular to the flow (metal fiber axial direction).
It is a micrograph.

FIG. 2 is a cross-sectional view of a filter used in an example.

FIG. 3 is a cross-sectional view of a filter device used in an example.

FIG. 4 is a schematic configuration diagram of a thermoplastic resin sheet molding apparatus according to the present invention.

[Explanation of symbols] 1, 1'Upstream metal fiber media 2,2 'Downstream metal fiber media 3,3 'Downstream metal powder media 4 SUS wire mesh 5,5 'weld 6 seal ring 7 discharge hole 10 filters 20, 20 'filter casing 30 filter tree 40 thermoplastic resin introduction hole 50 thermoplastic resin discharge hole 60 extruder 61 motor 62 Motor control device 63 hopper 70 Melt viscosity adjusting device 71 High Mixer 72 Temperature control jacket 73 Temperature control unit 80 filter device 81 Pressure detector 90 mouthpiece 91 Electrostatic pinning 92 Rotating cooling body 101, 102 metal fiber layer 103 metal powder layer

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI B29L 7:00 B29L 7:00 (56) References JP-A-6-322243 (JP, A) JP-A-6-322242 (JP , A) JP 2-11636 (JP, A) JP 7-68726 (JP, A) JP 7-37235 (JP, A) JP 6-312453 (JP, A) JP 4-87020 (JP, A) JP 62-259221 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B29C 47/00-47/96

Claims (8)

(57) [Claims] 1. A thermoplastic resin containing at least one inorganic and / or organic filler having an average particle diameter of δ μm and a standard deviation σ of the particle diameter of 0.1δ or more is melted by using an extruder, and the heat of fusion is melted. The plastic resin, the filler and filtration accuracy η
μm satisfies the equation (1), and the product of the diameter d _n μm of the metal fiber of the n-th medium and the basis weight w _n g / m ² (w _n ·
laminating media having a porosity of 35 to 90%, in which d _n ) satisfies the expressions (2) and (3), and the axes of the metal fibers are arranged in the direction orthogonal to the flow of the molten thermoplastic resin. together, the basis weight w _p g / m ^2, thereby satisfying the expression (4), porosity than the media by the metal fibers of one or more layers of media by 25-65% of the metal powder were stacked on the downstream side,
A method for producing a thermoplastic resin film, which comprises filtering through a filter having a flow resistance r by air of 35 to 800 mmH ₂ O, then discharging from a die and rapidly cooling to form a sheet. 2.5 <η / δ <50 (1) 400 <(w _n · d _n ) <16000 (2) 0.2 ≦ (w _{n + 1} · d _{n + 1} ) / (w _n · d _n ) ≦ 2.5 (3) 500 ≦ w _p ≦ 20000 (4) Here, n is the number of the medium from the upstream side of the laminated medium that constitutes the filter. 2. The heat according to claim 1, wherein a filter formed by laminating two or more layers of metal fibers having a diameter d of metal fibers of 0.5 to 30 μm and a basis weight w of 100 to 10,000 g / m ² is used. A method for producing a plastic resin film. 3. A filter comprising a metal fiber and / or a metal powder made of stainless metal is used.
Alternatively, the method for producing a thermoplastic resin film of 2. 4. The viscosity μ of the molten thermoplastic resin is 200 to 1
The method for producing a thermoplastic resin film according to claim 1, wherein the method is adjusted to 2000 poise and passed through a filter. 5. The thickness of the film, which is discharged from the die and rapidly cooled to form a sheet, and then stretched in the machine direction and / or the transverse direction, and then heat set, has a thickness of 0.5 to 25 μm. 5. The method for producing a thermoplastic resin film according to any one of 1 to 4. 6. The average particle diameter θ of the filler in the film is 1 of the average particle diameter δ μm of the aggregated filler in the thermoplastic resin.
/ 2 or less, and its standard deviation ψ is 0.6θ or less,
A method for producing the thermoplastic resin film according to claim 1. 7. A center line average roughness Ra of a film surface is obtained by using a thermoplastic resin containing one or more fillers having an average particle diameter δ of 0.01 to 1 μm and a standard deviation σ of 0.1δ or more.
Is 15 nm or less, and the number of coarse protrusions of H2 or more is 5/100
The film is formed so as to have a size of not more than cm ^2.
6. The method for producing a thermoplastic resin film according to any one of 5 to 5. 8. The method for producing a thermoplastic resin film according to claim 1, wherein the thermoplastic resin is polyester.