JP2001139709A - Method for cleaning surface of thermoplastic resin sheet and method for producing thermoplastic resin sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a high-quality thermoplastic resin sheet without surface defects with a good productivity. SOLUTION: Foreign materials present on the surface of a thermoplastic resin sheet are brought into contact with a transfer roll and efficiently transferred to migrate. Thereby, the foreign materials on the sheet surface are removed to carry out the formation of a film.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for cleaning the surface of a thermoplastic resin sheet having no surface foreign matter and excellent surface characteristics, and a method for producing a thermoplastic resin sheet using the method. is there.

[0002]

2. Description of the Related Art In the production of a thermoplastic resin sheet, when stretching or heating the necessary thermoplastic resin, generally, the thermoplastic resin is heated, stretched, transported, and cooled while being in contact with a roll.・ Molding is performed.

However, the problem when the thermoplastic resin comes into contact with the rolls is that very little monomer, oligomer or other low molecular weight compound, decomposed product of the resin present on the surface of the thermoplastic resin sheet. , Bleed-outs,
Additives, foreign substances typified by denatured substances, the foreign substances adhere to the roll in contact with the thermoplastic resin sheet, especially the heated roll, more foreign substances will be deposited on the contact roll surface over time, This has the drawback that it transfers to the film surface and causes abrasion. Therefore, in order to clean the rolls contaminated in this way, once stopping film formation and wiping the rolls,
Clean the rolls that become dirty during film formation with a cloth or the like, further contact an adhesive roll on the surface of the resin sheet, or put them in water and wash them with jets using mechanical stirring or external force such as ultrasonic waves. And so on.

[0004]

However, such a method is not only inefficient, but also cannot clean the sheet sufficiently. Therefore, the film is formed and processed while the sheet has scratches or foreign matter. I had to.

In view of the above, it is an object of the present invention to provide a method for cleaning the surface of a thermoplastic resin sheet which enables a high-quality thermoplastic resin sheet having no surface defects to be manufactured with high productivity. Another object of the present invention is to provide a method for producing a thermoplastic resin sheet using the cleaning method.

[0006]

Means for Solving the Problems In view of the above-mentioned problems, the present inventors have made intensive studies and arrived at the present invention. A method for cleaning the surface of a thermoplastic resin sheet is as follows. The method is characterized in that a film is formed and processed after contacting a transfer roll to transfer and transfer, and then cleaning a sheet surface.

[0007] In the method for producing a thermoplastic resin sheet of the present invention, when the thermoplastic resin sheet is produced, the surface of the thermoplastic resin sheet is formed using the above-described method for cleaning the surface of the thermoplastic resin sheet of the present invention. This is a method for producing a thermoplastic resin sheet, which is performed while removing foreign matter.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of the method for cleaning the surface of a thermoplastic resin sheet of the present invention and a method for producing a thermoplastic resin sheet using the cleaning method will be described below.

In the present invention, the thermoplastic resin is a resin which exhibits fluidity when heated, and is selected from, for example, polyesters, polyamides, polyolefins, polyphenylene sulfides, vinyl polymers, and mixtures and modified products thereof. Resins are typical, and among them, polyester resin, polyamide resin, polyolefin resin, polyphenylene sulfide (PPS) and the like are preferable, and polyester resin and polyamide resin are particularly preferable.

[0010] Polyester is a polymer compound having an ester bond in the molecular main chain, and is usually synthesized by a polycondensation reaction between a diol and a dicarboxylic acid, but is typically represented by hydroxybenzoic acid. A compound that self-condenses, such as a hydroxycarboxylic acid, may be used. Representative diol compounds include ethylene glycol, propylene glycol, butylene glycol, hexene glycol represented by HO (CH ₂ ) nOH, diethylene glycol, polyethylene glycol, ethylene oxide adduct, propylene oxide adduct and the like. And diols such as ether-containing diols, and the like, alone or in combination.

Representative dicarboxylic acid compounds include phthalic acid, isophthalic acid, terephthalic acid, naphthalenedicarboxylic acid, succinic acid, adipic acid, pimelic acid,
Suberic acid, azelaic acid, sebacic acid, dimer acid,
Maleic acid, fumaric acid, and mixtures thereof. Representative polyester resins include, for example, polyethylene terephthalate (PET), polybutylene terephthalate (PBT), and polyethylene naphthalate (PE).
N) and their copolymers, such as polycyclohexane dimethylene terephthalate (PCT). Among them, polyethylene terephthalate (PET) and polyethylene naphthalate (PEN) and their copolymers are preferable, and particularly, polyethylene terephthalate and The copolymer is preferred.

The repeating unit of these high molecular compounds is preferably 80 or more, more preferably 120 or more. The intrinsic viscosity is preferably 0.4 (d) as measured in orthochlorophenol (OCP).
l / g) or more, more preferably 0.55 (dl / g) or more. Of course, these polyester resins include various additives such as a slip agent, an antiblocking agent, a bulking agent, a stabilizer, an antioxidant, a viscosity modifier, an antistatic agent, a colorant, a pigment, or a liquid crystal polyester. Resins can be used in combination.

In the present invention, the polyamide resin is a polymer compound having an amide bond in the main chain,
Typical are nylon 6, nylon 66, nylon 610, nylon 12, nylon 11, nylon 7, polymeta / paraxylylene adipamide, polyhexamethylene terephthalamide / isophthalamide and their related copolymers, There are polyamide compounds selected from mixtures and the like. In the case of the present invention, among these, nylon 6 and its copolymer, nylon 66 and its copolymer are preferred polyamides. Furthermore, it is preferable to add a flexible nylon or a nylon compound that is difficult to crystallize to these polyamides because crystallization can be prevented by casting and the obtained quality can be provided with low-temperature flexibility.

Further, polyphenylene sulfide (PP
S) As the resin, a linear PPS compound substantially free of a branched structure is preferable.

Examples of the polyolefin resin include polyethylene (PE), polypropylene (PP), methylpentene polymer (MPP), ethylene vinyl alcohol (EVOH), vinyl acetate polymer (EVA), and various copolymers thereof. Can be used.

When the thermoplastic resin sheet is melt-extruded, the molten resin sheet is cooled and adhered and solidified while applying an electrostatic charge to produce the sheet, in order to suppress crystallization and homogenize the thickness. Is preferred from the viewpoint of preventing contamination of the surface of the quenched casting drum.

The volume resistivity at room temperature of the resin used in the present invention is preferably 10 ⁶ Ωcm or more and 10 ¹⁸ Ωcm or less, more preferably 10 ⁹ Ωcm or more and 10 ¹⁵ Ωcm or less. . Therefore, it can be said that a thermoplastic resin sheet having a resistance value in a relatively low resistance range is more effective, but is not necessarily limited to this.

In the present invention, in order to remove and clean foreign substances on the surface of the thermoplastic resin sheet, the thermoplastic resin sheet is brought into contact with a transfer roll to transfer and transfer the foreign substances to clean the sheet surface. It is.

Here, the foreign matters include low molecular compounds such as resin monomers and oligomers, decomposition products, bleed-out products,
It is a compound typified by an additive, a modified product, and the like, and of course, includes a fragment, a chip, a shavings of a thermoplastic resin, and a floating foreign substance such as silicon oxide and dust as a general matter.

As the surface material of the transfer roll, a material such as stainless steel (SUS), ceramic, chromium / nickel plating or sandblasting can be used in general, but is not particularly limited to these. Not silicon rubber lining, E
It is also possible to use a PT rubber lining or an organic resin coating such as a thermosetting resin.

The surface roughness of the transfer roll is not particularly limited, but according to the knowledge of the present inventors, the surface is slightly roughened, for example, R, rather than smooth.
The transfer efficiency of foreign matter is better on the surface roughened to a y value of about 0.5 to 3 μm (the ratio of the number of foreign matter transferred by one transfer roll contact to the total number of foreign matters on the transfer-receiving sheet).
Is preferred.

Further, the surface temperature of the transfer roll during the sheet manufacturing process is preferably heated to around the glass transition temperature of the resin because the transfer rate is high, but it is not necessarily limited to this. There may be. On the other hand, if the heating temperature is too high, the surface roughness of the transfer roll tends to be transferred to the sheet, which is not preferable in some cases. The heating may be any of heating medium heating, electric resistance heating, electromagnetic induction heating and the like, and an appropriate heating method can be used.

The diameter of the transfer roll is not particularly limited, but is preferably 100 mm or more, more preferably 15 mm or more, from the viewpoint of ease of use, transfer efficiency, and foreign matter removal rate.
A large-diameter roll of about 0 to 1000 mm is preferable.

The transfer roll may be a free rotation roll, a torque supply rotation roll, or a drive roll.
Since the roll has many functions such as heating / cooling and transfer / removal, a forced drive system is preferable.

In order to transfer and transfer the foreign matter on the surface of the resin sheet to the transfer roll efficiently, the above-mentioned transfer efficiency value is preferably as high as 70% or more. For this purpose, it is preferable to apply an electrostatic charge from the back surface of the resin sheet that is in contact with the transfer roll. However, the present invention is not limited to this, and a mechanical nip method may be used.

The application of an electrostatic charge to the resin sheet can be performed, for example, by supplying the electrostatic charge from a DC or AC power supply through an electrode. As the shape of the electrode, various shapes such as a wire, a blade, a tape, a band, and a needle can be used without particular limitation. A shape or a needle shape is preferable. The voltage used is about 5 to 25 Kv, and the current is 0.1 to 2
It is about 0 mA.

The distance and distance between the electrode tip and the sheet is preferably about 3 to 30 mm. The application position may be any time as long as the sheet is in contact with the transfer roll, but the transfer rate is better when the application is performed at the point where the sheet starts to contact. Also,
When there are a plurality of transfer rolls, an electrostatic charge may be applied to each of them. Further, a charging roll in which the transfer roll itself is charged may be used.

When foreign matter is adhered to the transfer roll in this way, the transfer roll becomes soiled with time, so that a cloth such as gauze, cloth or non-woven fabric is brought into contact with the surface of the transfer roll where the thermoplastic resin sheet is not in contact. It is important that the surface of the transfer roll be kept clean at all times.

Another method of cleaning the transfer roll is to keep the surface of the transfer roll clean by a discharge treatment such as corona discharge or normal-pressure plasma treatment on the surface of the transfer roll not in contact with the thermoplastic resin sheet. Can also.
In particular, atmospheric pressure plasma treatment in the atmosphere is preferable in terms of efficiency and space. Of course, it is preferable that the cloth or discharge electrode to be cleaned traverses periodically in the width direction of the transfer roll.

Next, the method of cleaning the surface of the thermoplastic resin sheet of the present invention will be described more specifically as an example using a polyethylene terephthalate (PET) sheet.

As a raw material, a polyethylene terephthalate (PET) resin or a raw material obtained by adding and blending another compound as required, for example, a liquid crystal polymer or another polyester resin, further, silicon oxide, magnesium oxide, calcium carbonate, titanium oxide, aluminum oxide , Mica, talc, kaolin and other inorganic compounds, crosslinked polyester,
Prepare raw materials to which organic compounds such as cross-linked polystyrene, ethylenebisstearylamide, and ionic polymer compound ionomers are added, and raw materials in which recovered raw materials are mixed once, and then dried and dehydrated. Weight, extruder, twin screw extruder, vent extruder, tandem extruder, etc.
Is extruded under a nitrogen stream or under vacuum so as not to lower as much as possible. Of course, the melting temperature is usually higher than the melting point (Tm) of the polyester resin,
It is also possible to perform extrusion in a so-called supercooled state, in which the resin is once melted at a temperature equal to or higher than the melting point (Tm) of the resin and then cooled to a temperature equal to or lower than the melting point Tm and equal to or higher than the melt crystallization temperature (Tmc). Extrusion in such a supercooled state not only has the effect of reducing the thermal decomposition and gelation of the resin, but also has the effect of reducing the generation of low-molecular-weight oligomers, thereby reducing drum contamination and facilitating casting. There is also.

Next, in order to remove foreign matter in the raw material, the molten resin is extruded while being filtered through an appropriate filter, for example, a sintered metal, a porous ceramic, a sand, a wire mesh or the like.
The polyester resin thus melted is extruded from an arbitrary die such as a molding die, a coat hanger die, a fishtail die, an L die, and a ring die.

At this time, it is preferable to extrude the molten resin sheet from the die in the vertical direction in order to eliminate the stripes in the die or to perform stable casting. More preferably, the base land direction is also preferably oriented in the vertical direction. The positional relationship between the die and the casting drum is not particularly limited, but rather than the die being located on the top of the casting drum, the position of the die is more tangential to the drum in the sheet traveling direction, more preferably in the vertical direction. It is more preferable for thickness uniformity, surface defects, and the like. For this reason, it is preferable that the shape of the mouthpiece is a crow mouth type with a sharp tip.

The draft ratio when the molten sheet is extruded from the die (= the distance between the lip of the die / the thickness of the extruded sheet) is preferably 3 or more, more preferably 5 to 20. It is easy to obtain a small, flat sheet. The thus melted polyester resin is extruded from a crow-mouth-shaped die, and the molten resin sheet is brought into close contact with a casting drum as a cooling medium with a wire electrode charged to a negative electrode at about 5 to 15 kv and rapidly cooled. .

On the surface of the thermoplastic resin sheet thus obtained, oligomers and foreign substances of PET resin, and further, PET
There are many foreign objects such as facets,
The foreign material on the sheet is transferred and transferred to the transfer roll efficiently. For this purpose, the transfer roll is heated to about 50 to 160 ° C., or a chrome plating roll having a large surface roughness is used as a transfer roll material.
Further, an electrostatic charge is applied while the sheet is in contact with the transfer roll. Of course, since the transfer roll becomes soiled with time, the transfer roll that is not in contact with the sheet is always kept clean by using gauze, normal pressure plasma treatment, corona treatment, or the like.

Subsequently, the sheet from which the foreign matter has been removed is subjected to Tg using a roll by a roll-type longitudinal stretching machine.
The film is heated and stretched about 1.5 to 7 times. Next, the sheet is guided to a tenter type width direction stretching machine for width direction stretching, the sheet is gripped at both ends by a clip, heated to a temperature of Tg or more by hot air, and the width of the both end clip is increased so that the sheet is expanded in the lateral direction by 2 to 2. Stretch 8 times. Further, in order to make the sheet strong in the longitudinal direction, the sheet is roll-drawn in the longitudinal direction again. At this time, as in the case of the cast sheet, the surface of the sheet is preferably removed by a transfer roll to remove foreign substances, and then re-stretched. The stretching temperature at this time is preferably 30 to 80 ° C. higher than the Tg of the resin. Further, if necessary, the sheet may be heat-treated at a temperature lower than the melting point of the resin by hot air.

By using the above-described method for cleaning the surface of a thermoplastic resin sheet of the present invention, a high-quality thermoplastic resin sheet can be manufactured with high productivity.

In particular, according to the present invention, a high-quality thermoplastic resin sheet can be produced by winding at a film forming speed of 10 to 500 m / min.
High speed of 100 m / min or more, for example, 400 m to 500 m
It is also possible to perform winding production at around m / min, which is of great industrial significance.

The sheet thus obtained can be widely used for optics, magnetic recording media, electric insulation, and other general industrial uses, which are concerned with surface defects.

[0040]

[Measurement method of physical properties] Next, the measurement method used in the present invention will be described below. 1. The intrinsic viscosity [η] of the polyester resin was determined at 25 ° C. using o-chlorophenol as a solvent by the following formula.

[Η] = lm [ηsp / c] The specific viscosity ηsp is obtained by subtracting 1 from the relative viscosity ηr.

C is the density. The unit is expressed in dl / g. 2. Polyester Thermal Characteristics Using a DSC RDC220 model manufactured by Seiko Denshi Kogyo Co., Ltd., 20 mg of polyester was weighed, and heated at 20 ° C.
The temperature is raised at a rate of 300 ° C./min to quench when the temperature reaches 300 ° C., and the temperature is again increased to 300 ° C. at a rate of 20 ° C./min.
c) The melting point (Tm) was measured. After reaching 300 ° C., the temperature was further decreased at a rate of 20 ° C./min, and the crystallization exothermic peak temperature (Tmc) was measured. 3. Volume resistivity R (Ωcm) A sheet is sandwiched between the main electrode with guard and the counter electrode, a DC voltage is applied to this electrode, and R is calculated from the following equation.

R = applied voltage V × main electrode area S / (measured current i × sheet thickness D)

[0044]

The present invention will be described in more detail by way of examples.

Example 1 As a thermoplastic resin, polyethylene terephthalate (P
ET) (intrinsic viscosity [η] = 0.65, Tg is 70 ° C, cold crystallization temperature Tcc is 128 ° C, melting point Tm is 265 ° C, Tm
As for c, 215 ° C., 0.1 wt. of silicon oxide particles having an average particle size of 0.25 μm as an additive, and a melting specific resistance at 285 ° C. of 109 Ωcm) were used. The water content of the PET resin is 10
ppm, and then supplied to a conventionally known tandem extruder having a screw diameter of 250 mm, melted at 285 ° C., cooled to 270 ° C.
The mixture was filtered by passing through a fiber-sintered metal filter having a .mu.m cut, introduced into a crow-mouth type T-die die having a width of 2200 mm, and extruded forward from the top of the drum in the rotational direction from the top of the drum ( Forward cast),
While applying an electrostatic charge to the molten sheet from a band-shaped electrode, 100 m / m 2 was placed on a drum having a diameter of 2 m, a surface length of 250 mm, and a chromium-plated surface having a surface roughness of 0.1 S.
The sample was brought into close contact with each other and cooled.

As a result of extrusion casting in this way, the cast adhesion at high speed was good, and the surface properties of the obtained sheet were also good. The cast sheet thus obtained was an amorphous sheet having a thickness of 90 μm and a width of 1950 mm, a small thickness unevenness, excellent flatness, and no surface defects.

Since foreign matters such as PET resin oligomers and foreign matters adhere to the surface of the thermoplastic resin sheet thus obtained, the foreign matters are forcibly driven and rotated at the same speed as the sheet speed. It is transferred to a roll to clean the surface of the stretched sheet. For this purpose, a transfer roll (outer diameter 300 mm) made of a chrome-plated material having a large surface roughness of 0.8 μm as the surface roughness Ry
The sheet was heated to 5 ° C. by electrostatic induction, and the sheet (resistivity 1 at 65 ° C.)
The transfer efficiency is increased to 90% or more by applying an electrostatic charge from the wire-shaped electrode to the sheet surface at the moment when the transfer roller contacts the transfer roll. Of course, since the transfer roll becomes soiled with the passage of time, the surface of the transfer roll not in contact with the sheet is always kept clean while wiping with a gauze traversing in the width direction.

After the surface of the extruded sheet was thus cleaned, the extruded sheet was stretched three times at a stretching temperature of 88 ° C. by a roll-type longitudinal stretching machine, and then cooled to a glass transition temperature Tg or lower. Subsequently, the sheet was guided to a tenter while holding both ends of the longitudinally stretched sheet with clips, and stretched 4.0 times in the width direction in a hot air atmosphere heated to a stretching temperature of 93 ° C.
And fixed by heat.

On the surface of the biaxially stretched thermoplastic resin sheet thus obtained, in addition to oligomers and foreign substances of PET resin, P
Since foreign matter such as ET itself is adhered, the foreign matter is further transferred to a transfer roll that is forcibly driven and rotated at the same speed as the biaxially stretched sheet speed to clean the surface of the sheet to be stretched. is there. For this purpose, a transfer roll (outer diameter 420 mm) made of a ceramic roll having a large surface roughness of 1.5 μm as the surface roughness Ry was set at 145 ° C.
Then, at the moment when the stretched sheet comes into contact with the transfer roll, an electrostatic charge is applied to the sheet surface from the wire-like electrode to increase the adhesion, thereby increasing the transfer efficiency to 70% or more. Of course, the surface of the transfer roll that is not in contact with the sheet,
The normal pressure plasma processor is traversed in the width direction to decompose and scatter foreign matter, and the transfer roll is always kept clean.

Further, in order to stretch the biaxially stretched sheet again in the longitudinal direction, a preheating temperature of 96 ° C. and a stretching temperature of 1
The film was stretched 1.5 times in the longitudinal direction on a roll heated to 55 ° C. At this time, there was no slippage of the sheet on the roll, and there was no scratch or scratch on the sheet surface.

Further, this sheet was gripped with a clip for heat treatment, and was heated at 200 ° C. and 130 ° C. with a tenter.
Then, a biaxially oriented polyester sheet having a thickness of 6 μm was wound and formed at a high speed of about 450 m / min in a stable state.

The sheet thus obtained was a sheet excellent in flatness with no surface defects. Comparative Example 12 A biaxially stretched sheet was formed in exactly the same manner as in Example 1 except that the contact with the transfer roll before performing the roll stretching in the longitudinal direction twice was stopped.

As a result, the biaxially stretched sheet had many surface defects such as scratches and scratches on the surface of the biaxially stretched sheet as well as scratches and scratches, and was a sheet having many surface defects that could not be used for optical applications.

[0054]

According to the present invention, by efficiently transferring foreign matter on the surface of a thermoplastic resin sheet to a transfer roll before stretching the roll, a high-quality sheet free from surface defects can be manufactured with high productivity.

The sheet manufactured in this manner can be preferably used as an industrial material, a magnetic material, a packaging material and the like.

Claims (15)

[Claims] 1. A method for cleaning the surface of a thermoplastic resin sheet, wherein foreign matters on the surface of the thermoplastic resin sheet are transferred to and transferred from a transfer roll. 2. The method according to claim 1, wherein the foreign matter is a monomer or an oligomer of the resin.
The method for cleaning the surface of a thermoplastic resin sheet according to claim 1, wherein the thermoplastic resin sheet is a low-molecular compound such as a decomposed product, a bleed-out product, an additive, or a modified product. 3. The method for cleaning the surface of a thermoplastic resin sheet according to claim 1, wherein the surface temperature of the transfer roll is heated to near the glass transition temperature of the resin. 4. The transfer roll surface material is chrome plating,
4. The method for cleaning the surface of a thermoplastic resin sheet according to claim 1, wherein the material is selected from stainless steel (SUS), sandblasted SUS, ceramic, and the like. 5. The method for cleaning the surface of a thermoplastic resin sheet according to claim 1, wherein an electrostatic charge is applied from the back surface of the thermoplastic resin sheet in contact with the transfer roll. 6. The method for cleaning the surface of a thermoplastic resin sheet according to claim 1, wherein the transfer roll itself is a charged roll. 7. The thermoplastic resin sheet according to claim 1, wherein an electrostatic charge is applied to both surfaces of the thermoplastic resin sheet or a charging roll is brought into contact with both surfaces. How to clean the surface. 8. The transfer roll according to claim 1, wherein the surface of said transfer roll is kept clean by bringing a cloth-like material into contact with a portion where said thermoplastic resin sheet is not in contact with said transfer roll.
4. The method for cleaning the surface of a thermoplastic resin sheet according to 4, 5, 6, or 7. 9. The surface of the transfer roll is always kept clean by performing a discharge treatment such as corona discharge or plasma treatment on a portion where the thermoplastic resin sheet is not in contact with the transfer roll. 1, 2, 3, 4, 5, 6,
9. The method for cleaning the surface of a thermoplastic resin sheet according to 7 or 8. 10. The method for cleaning the surface of a thermoplastic resin sheet according to claim 8, wherein the cloth to be cleaned and the discharge electrode are traversed periodically in the width direction of the transfer roll. 11. The thermoplastic resin sheet is cooled and adhered while applying an electrostatic charge when melt-extruding the thermoplastic resin sheet. 1
0. The method for cleaning the surface of a thermoplastic resin sheet according to 0. 12. The thermoplastic resin according to claim 1, wherein the thermoplastic resin is a resin selected from the group consisting of a polyester resin, a polyamide resin, a polyolefin resin, and polyphenylene sulfide. , 9, 10 or 1
2. The method for cleaning the surface of a thermoplastic resin sheet according to 1. 13. The method of claim 1, 2, 3, 4, 5, 6, 7, 8, 9, 1 when producing a thermoplastic resin sheet.
A method for producing a thermoplastic resin sheet, wherein the method is performed while removing foreign substances present on the surface of the thermoplastic resin sheet by using the method for cleaning the surface of the thermoplastic resin sheet according to 0, 11, or 12. 14. A thermoplastic resin sheet having a thickness of 10 to 500 m
The method for producing a thermoplastic resin sheet according to claim 13, wherein the film is produced by winding at a film forming speed of / min. 15. The method according to claim 1, wherein the thermoplastic resin sheet is wound and produced at a high speed of 100 m / min or more.
4. The method for producing a thermoplastic resin sheet according to 3.