JP2001341196A - Method for removing adherend on surface of roll and method for manufacturing thermoplastic resin film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To manufacture a thermoplastic resin film of high quality having no surface flaw with good productivity. SOLUTION: A molding roll of a thermoplastic resin film is irradiated with ultraviolet rays enhanced in its irradiation intensity to reduce the organic adherend on the surface of the roll.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for removing deposits on a roll surface used for producing a thermoplastic resin film,
And a method for producing a high-quality thermoplastic resin film having no surface defects.

[0002]

2. Description of the Related Art In the production of a thermoplastic resin film, a molding roll (hereinafter abbreviated as a roll) is generally used in almost all processes such as cooling, heating and stretching.

However, the problem when the thermoplastic resin comes into contact with the roll as described above is that a very small amount of low molecular weight substances such as monomers and oligomers of the resin existing on the surface of the thermoplastic resin film, decomposed products, bleed and the like are present. Organic substances typified by out-products, additives, denatured products, etc. adhere to the roll in contact with the thermoplastic resin film and deposit on the contact roll surface over time. This has the disadvantage that it is transferred to the film surface and causes abrasion. Therefore, in order to clean such a contaminated roll, the film formation has been stopped once and the roll has been wiped off to remove the deposits. However, this operation was inefficient and led to a significant decrease in productivity.

[0004] To solve this problem, various methods for online roll cleaning have been proposed. For example,
JP-A-56-69120 discloses a method in which a touch roll is brought into contact, and JP-B-47-3917 discloses a method in which a cleaning solution is applied and wiped off. However, these methods can reduce the organic deposits on the film surface, but cannot completely remove them, and have not been enough to prevent the accumulation of dirt on the roll.

[0005] Japanese Patent Publication No. 3-65775 discloses a method of cleaning a roll by irradiating ultraviolet rays. However, this method has a problem that it cannot be completely removed when the ultraviolet irradiation energy is weak and the film forming speed is high, or when the amount of the organic substance attached increases due to the type of the thermoplastic resin.

[0006]

SUMMARY OF THE INVENTION In view of the foregoing, an object of the present invention is to provide a method for removing deposits on a roll surface used for producing a thermoplastic resin film, and a high-quality thermoplastic resin free from surface defects. It is an object of the present invention to provide a method for producing a thermoplastic resin film, which makes it possible to produce a film with high productivity.

[0007]

Means for Solving the Problems The present inventors have made intensive studies in view of the above-mentioned problems, and as a result, have reached the present invention. In order to achieve the above object, the present invention employs the following configuration. (1) Removal of organic deposits on the roll surface by irradiating the roll surface used in the production of the thermoplastic resin film with ultraviolet rays having an irradiation intensity satisfying the following formula to remove organic deposits on the roll surface: Method.

Y ≧ 0.0492e ^0.0254x (where y is the irradiation intensity and x is the ultraviolet main wavelength) (2) The ultraviolet light contains at least a main wavelength of 120 nm or more and 380 nm or less. The method for removing deposits on a roll surface according to (1).

(3) The method for removing deposits on a roll surface according to the above (1) or (2), wherein the collected ultraviolet light is irradiated.

(4) The method for removing deposits on the roll surface according to any one of (1) to (3), wherein the ultraviolet light source is a low-pressure mercury lamp or an excimer lamp.

(5) The material (1) to (4), wherein the material of the roll surface is metal or ceramic.
The method for removing deposits on a roll surface according to any one of the above.

(6) The method for removing deposits on a roll surface according to any one of (1) to (5), wherein the transfer roller is irradiated with ultraviolet rays.

(7) The roll according to any one of (1) to (6), wherein the surface temperature of the roll is heated to a temperature not lower than the glass transition temperature of the resin forming the thermoplastic resin film minus 20 ° C. The method for removing deposits on the roll surface according to the above.

(8) The method for removing deposits on a roll surface according to any one of (1) to (7), wherein an electrostatic charge is applied to the roll.

(9) The deposit on the roll surface according to any one of (1) to (8), wherein the irradiation shape of the ultraviolet light is a slit shape having a long axis with respect to the roll width direction. Removal method.

(10) The method for removing deposits on a roll surface according to any one of the above (1) to (9), wherein the ultraviolet irradiation section traverses in the roll width direction.

(11) The organic compound adhering to the roll is a resin monomer, a low molecular weight product such as an oligomer, a decomposed product, a bleed-out product, or an additive. The method for removing deposits on a roll surface according to any one of the above.

(12) The low molecular weight substance attached to the roll is
The method for removing deposits on a roll surface according to the above (11), wherein at least one of terephthalic acid, bishydroxyethyl terephthalic acid, and monohydroxyethyl terephthalic acid is contained.

(13) The method for removing deposits on the roll surface according to any one of (1) to (12), wherein the thermoplastic resin film is made of any one of polyolefin, polyamide and polyester.

(14) A thermoplastic resin obtained by removing the organic deposits on the surface obtained by the method for removing deposits on the roll surface according to any one of the above (1) to (13). Film production method.

(15) The method for producing a thermoplastic resin film according to any one of the above (14), wherein the film is biaxially stretched.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a method for producing a thermoplastic resin film of the present invention will be described in detail. The present invention
When the roll is irradiated with ultraviolet light having a certain main wavelength x, it is to irradiate ultraviolet light having an irradiation intensity satisfying the following formula: y ≧ 0.0492e ^0.0254x (where y is the irradiation intensity,
x is the dominant wavelength of ultraviolet light. The effect is to remove the organic matter on the roll surface.

In general, the irradiation intensity indicates the light intensity of the ultraviolet main wavelength measured on the surface of the roll as the object to be processed. The dominant wavelength is the wavelength emitted by ultraviolet light.
126 nm, 146 nm, 157 nm, 165 nm, 1
72 nm, 190 nm, 207 nm, 222 nm, 24
8 nm, 254 nm, 258 nm, 282 nm, 308
nm, 342 nm, and 353 nm. When two or more peaks are present among these wavelengths, the following equation y ≧ 0.0492e ^0.0254x (where y is the irradiation intensity,
x is a wavelength).

The ultraviolet light is used to decompose and remove low molecular weight substances, which are the main components of organic deposits, at a wavelength of 120 nm or more.
It preferably contains at least a main wavelength of 0 nm or less. The reason is that at a wavelength of 380 nm or more, the decomposition rate of a low molecular weight substance becomes extremely slow, and at a wavelength of 120 nm or less, it is not preferable from the viewpoint of safety.

In the case of the conventional ultraviolet irradiation, the irradiation unit is an ultraviolet lamp itself, and the irradiation can be performed uniformly over a relatively wide range. However, the irradiation intensity is uniformly low, and the film forming speed is increased. However, depending on the type of the thermoplastic resin, the decomposition rate cannot keep up with that of the thermoplastic resin, and dirt adheres over time. For this reason, it is preferable to remove the organic deposits by improving the irradiation intensity by condensing the ultraviolet light. The method of condensing light is not particularly limited. For example, a method of installing a converging mirror around an ultraviolet lamp and condensing light is simple in terms of equipment. The ultraviolet light condensed in this way has high energy, and can dramatically improve the decomposition speed.

As an ultraviolet light source, an electrodeless discharge tube apparatus for exciting a light emitting material by irradiating a microwave to a discharge tube in which a light emitting material such as mercury is sealed has been conventionally used.
As this light source, a mercury lamp is used, which uses discharge light emission of mercury vapor.
It is divided into low-pressure, high-pressure and ultra-high-pressure mercury lamps. Among these, a low-pressure mercury lamp that emits light of 184.9 nm and 253.7 nm is preferable because of its high wavelength intensity.

Further, a discharge excimer lamp can be used instead of the low-pressure mercury lamp. An excimer is a dimer of excited state atoms and ground state atoms. By generating high energy such as discharge plasma in a lamp tube, atoms in the discharge tube can be brought into an excimer state. When returning from the excimer state to the ground state, strong ultraviolet light is generated by a phenomenon called excimer emission. As a result, a low-wavelength mercury lamp has a small output per wavelength and can obtain only a limited plurality of emission wavelengths, whereas an excimer lamp efficiently emits one high-intensity light compared to a normal low-pressure mercury lamp. Can be taken out.
The gas atoms sealed in the discharge tube have a wavelength of 120 nm to
Xe ₂ (center wavelength 172n) within 380 nm
m) and KrCl (center wavelength: 222 nm) are preferred.

When a light source having a center wavelength of 200 nm or less is selected, ozone is generated due to absorption of oxygen in the air. This ozone has the effect of oxidizing and decomposing organic deposits at least as much as short-wavelength light, and the decomposition efficiency is extremely high. Therefore, as the atmosphere for cleaning the roll surface,
It is preferable to have a clean oxygen atmosphere in which dust and the like do not float. It is preferable that a suction device is attached to the surroundings of the roll and the ultraviolet lamp, and fresh air is always supplied.

The roll used for the thermoplastic resin film includes a casting roll, a transfer roll, a calender roll, a cooling / preheating roll, a stretching roll, a nip roll, and the like. As the surface material of these rolls, stainless steel (SUS), ceramic, chrome / nickel plating, sandblasting, and the like can be generally used. Conversely, in the case of rolls that have been coated with silicone rubber or organic resin,
Ultraviolet rays are not preferable because they affect not only organic substances on the roll surface but also the roll surface material.

Further, the ultraviolet irradiation may be applied to a transfer roll. This transfer roll is provided for collecting organic substances on the surface of the thermoplastic resin film. The transfer roll is intended to transfer and transfer an organic substance by contacting the surface of the thermoplastic resin film to clean the film surface. When the organic material is adhered to the transfer roll in this manner, the transfer roll becomes soiled with time, so that the surface of the transfer roll not in contact with the thermoplastic resin film is always cleaned by irradiating ultraviolet rays to the transfer roll. it can.

The surface temperature of the roll is preferably heated to a glass transition temperature of the resin of −20 ° C. or higher, but is not limited to this, and may be 0 ° C. or higher.

The roll nip may apply an electrostatic charge from the back of the resin film in contact with the roll.
It is not necessarily limited to this, and a mechanical nip method may be used. The application of an electrostatic charge to the resin film 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 tip of the electrode and the film is preferably about 3 to 30 mm. The application position may be any time while the film is in contact with the roll.
Further, a charging roll in which the roll itself is charged may be used.

The ultraviolet irradiation of the present invention has a high irradiation energy and a very high decomposition efficiency of organic deposits. However, since the light is focused, the irradiation area is small, and the ultraviolet light often does not reach the entire roll. For this reason, it is preferable that the irradiation shape of the ultraviolet ray of the present invention be a long axis with respect to the roll width direction. In other words, by setting the irradiation diameter to be long in the roll width direction, the entire irradiation area can be advantageously obtained by rotating the roll.

Further, the condensed ultraviolet light is preferably traversed periodically in the roll width direction to clean the entire roll.

The organic deposit in the present invention is derived from a thermoplastic resin and produces various organic compounds generated in the process. For example, a low-molecular-weight product, a decomposition product, a bleed-out product, or an additive of the thermoplastic resin. In addition, sublimates, fats and oils, dust and the like contained in the air are also included in this. Among them, the low molecular weight compounds mainly include monomers such as terephthalic acid, bishydroxyethyl terephthalic acid and monohydroxyethyl terephthalic acid and oligomers such as dimers, trimers and cyclic trimers.

The thermoplastic resin shown in the present invention is:
For example, polyester, polyamide, polyolefin,
A resin selected from polyphenyl sulfide, a mixture thereof and a modified product thereof is typical, and a polyester resin and a polyamide resin are particularly preferable.

The polyester referred to here 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. A compound that self-condenses, such as a representative 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. Polyethylene terephthalate, polybutylene terephthalate, polyethylene-2,6-naphthalate, poly-1,4-cyclohexane dimethylene terephthalate and the like can be used. In particular, polyethylene terephthalate is inexpensive, so it is used in a wide variety of applications and is highly effective. Further, these resins may be homo resins, or may be copolymers or blends.

When the polyester film used in the present invention is polyethylene ethylene terephthalate, it can be produced by a conventionally known production method. That is, terephthalic acid and ethylene glycol and, if necessary, a copolymerization component are directly reacted to distill off water and esterify the mixture, followed by polycondensation under reduced pressure, or dimethyl terephthalate and ethylene glycol as necessary. And then subjecting the copolymerization components to reaction to remove methyl alcohol and transesterify, followed by a transesterification method in which polycondensation is performed under reduced pressure. Further, solid-state polymerization may be performed to increase the intrinsic viscosity and reduce the content of cyclic trimer and acetaldehyde. The melt polycondensation reaction may be performed in a batch reactor or a continuous reactor. In any of these methods, the melt polycondensation reaction may be performed in one step or may be performed in multiple steps. The solid-state polymerization reaction can be carried out in a batch system or a continuous system, similarly to the melt polycondensation reaction. The melt polycondensation and the solid phase polymerization may be performed continuously or may be performed separately.

Typical polyester resins include, for example, polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN) and copolymers thereof, and polycyclohexane dimethylene terephthalate (PCT). And polyethylene terephthalate (PE)
T), polyethylene naphthalate (PEN) and their copolymers are preferred, and polyethylene terephthalate and its copolymers are particularly preferred.

The repeating unit of these polymer compounds is preferably 80 or more, more preferably 120 or more.

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 hardly crystallizable nylon compound to these polyamides, because crystallization can be prevented by casting and the obtained quality can be imparted with low-temperature flexibility.

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.

The thermoplastic resin used in the present invention may be provided with a coloring agent, an ultraviolet absorber, an antioxidant, an antistatic agent, a lubricant, a nucleating agent, a release agent, etc., if necessary, to impair the object of the present invention. It can be added in a range that does not exist.

Next, the method for producing a thermoplastic resin film according to the present invention will be described more specifically as an example using a polyethylene terephthalate (PET) film.

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. The mixture is then melt-extruded under a nitrogen stream or under vacuum so as to minimize the molecular weight, for example, the intrinsic viscosity [η].

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 molten polyester resin is extruded from a molding die.

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

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.

Subsequently, the film is heated to at least Tg using a roll and stretched about 1.5 to 7 times. Next, the film is guided to a tenter-type width direction stretching machine for width direction stretching, the film is gripped at both ends of the sheet, heated to a temperature of Tg or more by hot air, and the width of the both end clips is increased so that the film is expanded in the lateral direction by 2 to 2. Stretch 8 times. Further, the film may be stretched again in the longitudinal direction in order to make the film strong in the longitudinal direction. If necessary, the film may be heat-treated with hot air at a temperature lower than the melting point of the resin.

When the film is formed by the above method, organic deposits are deposited on the roll and a defect is left on the film with the lapse of time. Thus, the organic substance on the roll is removed by the main feature of the present invention. There is an improved UV irradiation
It disassembles and removes, keeping the roll surface clean.

When the film is stretched longitudinally, the degree of crystallinity of the thermoplastic resin increases as the stretching proceeds, so that the organic matter dissolved in the resin is likely to precipitate, and the organic matter existing on the film surface is reduced. Since the amount becomes very large, the organic film easily adheres to the longitudinal stretching roll that contacts the film, and the film is easily stained. Therefore, the method of the present invention is very effective when used for a longitudinal stretching roll or a re-longitudinal stretching roll. Further, since the present invention has a high organic substance removing effect, the roll can be kept in a clean state even if the transfer amount of the organic deposits increases due to an increase in the casting speed.

By using the above-described method for producing a thermoplastic resin film of the present invention, a high-quality thermoplastic resin film having few defects can be produced with high productivity.

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

[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) Thermal properties of polyester Using a DSC RDC220 model manufactured by Seiko Denshi Kogyo, 5 mg of polyester was weighed, and heated at 20 ° C /
Quenching when the temperature rises to 300 ° C. at a rate of 20 minutes / minute, and while the temperature is raised again to 300 ° C. at a rate of 20 ° C./minute, the glass transition point (Tg) and the crystallization exothermic peak temperature (Tc)
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) UV irradiation intensity UV-METER C6080-02 manufactured by Hamamatsu Photonics
Was used to measure the irradiation intensity at a wavelength of 254 nm. Was used. (4) Roll dirt For oligomer dirt on the roll, the longitudinal stretching roll is sufficiently cleaned before the start of film formation, and the stain state 72 hours after the start of the film formation is visually observed. "◎" for the thing, "○" for the one with almost no dirt at first glance, "、" for very thin dirt (white turbidity) but no problem with continued use, "△" for the dirt considerably thick Those that adhered and required cleaning or replacement were rated "x".

[0058]

The present invention will be described in more detail with reference to Examples and Comparative 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
c was 215 ° C., and 0.1 wt% silicon oxide particles having an average particle size of 0.25 μm were used as an additive. The PET resin was dried so as to have a water content of 50 ppm or less, fed to an extruder, melted at 285 ° C., filtered through a 10 μm cut fiber sintered metal filter, and introduced into a die. While applying an electrostatic charge from a wire-like electrode to the molten film, the film was adhered to a cooling roll and cooled. Preheating the extruded film at a preheating temperature of 90 ° C.,
The film was stretched 3.0 times at a stretching temperature of 95 ° C. using a roll-type longitudinal stretching machine, and then cooled to a glass transition temperature Tg or lower. Subsequently, the film was guided to a tenter while gripping both ends of the longitudinally stretched film with clips, stretched 3.5 times in the width direction in a hot air atmosphere heated to a stretching temperature of 115 ° C, and heat-fixed at 200 ° C.

For UV irradiation, a low-pressure mercury lamp (main wavelength: 254 nm) was used as a light source. The lamp is surrounded by a chamber, and the angles of the collecting mirrors installed on all sides of the chamber,
Adjust the distance between the roll and the UV lamp, and adjust the irradiation intensity to 60.
mW / cm ² . The ultraviolet lamp is traversed (moving speed 0.05 m / mi) in the width direction of the roll.
n), and continuously irradiated the longitudinally stretched preheating roll. The film forming speed was 30 m / min, and the thickness of the obtained stretched film was 188 μm. Table 1 shows the results at this time.
Shown in

Example 2 A film was formed under the same conditions as in Example 1. However, at this time, the irradiation intensity was adjusted to be 600 mW / cm ² . Table 1 shows the obtained results.

Example 3 A film was formed under the same conditions as in Example 1. However, the irradiation intensity at this time was adjusted to be 1300 mW / cm ² . Table 1 shows the obtained results.

Example 4 A film was formed under the same conditions as in Example 1. However, a Xe ₂ excimer lamp (main wavelength: 172 nm) was used as an ultraviolet lamp. At this time, the excimer lamp irradiates the roll as close to the limit as possible, and the irradiation intensity is 5 mW / cm ² . The ultraviolet irradiation device was installed on a longitudinal stretching preheating roll. Table 1 shows the obtained results.

Example 5 A film extruded under the same conditions as in Example 1 was preheated at a preheating temperature of 90 ° C., and then stretched 3.3 times at a stretching temperature of 100 ° C. by a roll-type longitudinal stretching machine. It cooled below the transition temperature Tg. Subsequently, the film was guided to a tenter while holding both ends of the longitudinally stretched film with clips, stretched 4.0 times in the width direction in a hot air atmosphere heated to a stretching temperature of 110 ° C, and heat-fixed at 200 ° C. Further, in order to stretch the film in the longitudinal direction again, the film was stretched 1.5 times in the longitudinal direction on a roll heated to a stretching temperature of 155 ° C. Further, this film was gripped with a clip for heat treatment, heat-fixed at 200 ° C. and 130 ° C. with a tenter, and a biaxially oriented polyester film having a thickness of 6 μm was wound. UV irradiation is performed on the longitudinal stretching preheating roll and re-longitudinal stretching roll,
At this time, the angle between the roll and the condenser mirror and the distance between the ultraviolet lamp were adjusted so that the ultraviolet irradiation intensity was 600 mW / cm ² . The film forming speed is 200 m / min. Table 1 shows the obtained results.

Example 6 A film was formed under the same conditions as in Example 5. However, the irradiation intensity at this time was adjusted to be 1300 mW / cm ² . Table 1 shows the obtained results.

Example 7 A film was formed under the same conditions as in Example 5. However, a Xe ₂ excimer lamp (main wavelength: 172 nm) was used as an ultraviolet lamp. At this time, the excimer lamp was irradiated with the roll as close as possible to the limit, and the irradiation intensity was 5 mW / cm ^2. Table 1 shows the results.

Comparative Example 1 A film was formed under the same conditions as in Example 1. However, no UV irradiation was performed in this experiment. Table 1 shows the results.

Comparative Example 2 Film formation was started under the same conditions as in Example 1. However, the low-pressure mercury lamp (main wavelength: 254 nm) used at this time is a device which is not condensed but is simply covered with an enclosure. The irradiation intensity at this time is 20 mW / cm ² (0.0492 e
^0.0254 × ²⁵⁴ = 31.18 ≧ 20 mW). The ultraviolet lamp traverses in the width direction of the roll (movement speed 0.05 m
/ Min) to continuously irradiate the longitudinal stretching preheating roll and the longitudinal stretching cooling roll. Table 1 shows the results.

Comparative Example 3 A film was formed under the same conditions as in Example 5. However, no UV irradiation was performed in this experiment. Table 1 shows the obtained results.

Comparative Example 4 Film formation was started under the same conditions as in Example 5. However, the ultraviolet lamp used at this time is a device which is not condensed but is simply covered with an enclosure. The irradiation intensity at this time was 20 mW / cm ²
(0.0492e ^0.0254 × ²⁵⁴ = 31.18 ≧ 2
0 mW). The ultraviolet lamp was continuously irradiated to the longitudinal stretching preheating roll and the longitudinal stretching cooling roll so as to traverse in the width direction of the roll (moving speed: 0.05 m / min). Table 1 shows the results.

As a result, in Examples 1 to 6, there was no roll contamination, and there was no sliding of the film on the roll, and no scratches or scratches on the film surface. No roll contamination was observed even for long-term film formation. The film thus obtained was a film having excellent flatness without any roll contamination or surface defects.

On the other hand, in Comparative Examples 1 to 4, slight generation of deposits was already observed on the roll surface 48 hours after film formation, and film slippage and scratch transfer occurred on the roll after 72 hours. did. The surface of the biaxially stretched film obtained at this time had many surface defects such as scratches and scratches as well as foreign substances attached.

[0072]

[Table 1]

[0073]

As described above, according to the present invention, the occurrence of film surface scratches generated in the step of forming a thermoplastic resin film is reduced, and the number of film forming interruptions for cleaning dirt adhered to a roll is drastically reduced. And the productivity can be improved.

Claims (15)

[Claims] 1. The method of claim 1, wherein the surface of the roll used in the production of the thermoplastic resin film is irradiated with ultraviolet rays having an irradiation intensity satisfying the following formula to remove organic deposits on the roll surface. Method. y ≧ 0.0492e ^0.0254x (where y is the irradiation intensity and x is the main ultraviolet wavelength) 2. The method according to claim 1, wherein the ultraviolet light has at least a main wavelength of 120 nm or more and 380 nm or less. 3. The method for removing deposits on a roll surface according to claim 1, wherein the collected ultraviolet light is irradiated. 4. The method for removing deposits on a roll surface according to claim 1, wherein the ultraviolet light source is a low-pressure mercury lamp or an excimer lamp. 5. The method for removing deposits on a roll surface according to claim 1, wherein the material of the roll surface is metal or ceramic. 6. The method according to claim 1, wherein the transfer roller is irradiated with ultraviolet rays. 7. The method according to claim 1, wherein the surface temperature of the roll is heated to at least the glass transition temperature of the resin forming the thermoplastic resin film minus 20 ° C. A method for removing deposits on the roll surface. 8. The method for removing deposits on a roll surface according to claim 1, wherein an electrostatic charge is applied to the roll. 9. The method for removing deposits on a roll surface according to claim 1, wherein the irradiation shape of the ultraviolet light is a slit shape having a long axis in the roll width direction. . 10. The method for removing deposits on a roll surface according to claim 1, wherein the ultraviolet irradiation section traverses in the roll width direction. 11. The method according to claim 1, wherein the organic substance attached to the roll is a resin monomer, a low molecular weight substance such as an oligomer, a decomposition product, a bleed-out product, or an additive. The method for removing deposits on a roll surface according to the above item. 12. The roll according to claim 11, wherein the low molecular weight substance attached to the roll contains at least one of terephthalic acid, bishydroxyethyl terephthalic acid and monohydroxyethyl terephthalic acid. A method for removing deposits on the surface. 13. The method for removing deposits on a roll surface according to claim 1, wherein the thermoplastic resin film is made of any one of polyolefin, polyamide and polyester. 14. A thermoplastic resin film comprising a roll obtained by removing the organic deposits on the surface obtained by the method for removing deposits on the roll surface according to any one of claims 1 to 13. Production method. 15. The method according to claim 1, wherein the film is biaxially stretched.
5. The method for producing a thermoplastic resin film according to any one of 4.