JP2000296529A - Method for casting and forming film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate a surface fault of a film or the like by specifying a mean concentration of a solvent in a film-like material when released, holding a surface temperature of a support of a released portion at a specific value, and forming a surface of a take-off roller when released of a material having non-adhesive surface. SOLUTION: A cast film from an extrusion die 1 is set at a mean concentration of a solvent to 10 to 30 wt.%. A temperature of a support 2 is regulated so that a temperature of the film or the like becomes 15 to 5 deg.C near a take-off roller 4, released to a semi-dried film 3. The film 3 is wrapped on the roller 4 non-adhesive surface treated with a fluororesin or the like, and sent to a drying step through conveying rollers 5 to 8, a dancer roller 9 and a conveying roller 10. The film 3 immediately after releasing from the support 2 has a remarkably large front and rear surface difference of solvent contents, contracted by abrupt solvent evaporation after releasing, curled or shrunk in a width direction. Hence, a non-contact length of the film between the rollers is reduced as much as possible to evaporate the solvent. Thus, the film has an excellent flatness, no release damage, no adhesive damage, no scratch or the like.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method of casting a polymer solution on a support made of metal or the like to form a film.
It is dried, peeled off from the support, and further dried to obtain various optical materials and thermoplastic resin films or sheets used in various other fields (hereinafter, “film or sheet” is simply referred to as “film etc.”). In some cases).

[0002]

2. Description of the Related Art In an industrial production method of a film or the like by a casting film forming method, a metal substrate such as a steel belt is generally used as a support. On this support, a polymer resin solution was cast from an extrusion die to form a film, the film was dried, and a film or the like was peeled off from the support in a state containing a certain amount of solvent. are doing. At this time, there are various restrictions on stripping a film or the like from the metal support. This is because films and the like are used for various optical applications and may not be used if there are even minute defects, and the film and the like immediately after peeling from the support contain a certain amount of solvent. This is because when the film or the like is peeled off from the support and when the film is transported, minute scratches (transfer scratches, peeling scratches, scratches, etc.) are easily generated on the surface of the film or the like.

Conventionally, several techniques have been proposed for stripping a film or the like from a support. For example,
A method of adding a release agent in a polymer resin solution to assist in peeling, or covering the support surface with, for example, a fluororesin,
A method of reducing the surface energy to reduce the peeling force of a film or the like, a method of promoting gelation using a mixed solvent, and the like have been proposed.

[0004] Japanese Patent No. 2,640,189, Japanese Patent Application Laid-Open No. 5-239229, and Japanese Patent Application Laid-Open No. 2-111 have mainly defined conditions for peeling a film or the like from a support.
511 and JP-A-7-304048 are disclosed.

Japanese Patent Application Laid-Open No. Hei 5-239229 discloses a method for producing a thermoplastic resin film or the like, characterized in that when a residual solvent amount in a resin film or sheet becomes 20% by weight or less, the resin film or sheet is peeled off from a metal substrate. Has been described.

[0006] Patent Publication No. 264,189 discloses that
The residual solvent amount at the time of peeling is set to 10 to 30% based on the dry weight, and the surface temperature of the support at the peeled portion is 20 ° C.
A casting film forming method characterized by maintaining the temperature at 5.5 ° C. or higher is described.

Japanese Patent Application Laid-Open No. Hei 2-111511 discloses a method for producing a film by peeling a film from a support, removing the film, and performing the next casting on the support. A casting film forming method, wherein the surface temperature of the support is 15 ° C. or lower, and a portion where the support is exposed is filled with a gas having a dew point lower than the surface temperature of the support. Have been.

Japanese Patent Application Laid-Open No. 7-304048 discloses that a solution of a polymer is cast on a support, and then dried to produce a polymer film for optics. It describes a method for producing a polymer film for optics, characterized by drying on a support at a temperature of -10 ° C, and a method for producing a film having optical anisotropy only in the thickness direction.

Certainly, in these techniques, a film free from surface defects such as transfer, peeling scratches, adhesive scratches and scratches can be peeled off from the support and manufactured.

However, it is difficult to say that the problems of the casting film forming method have been sufficiently solved even by using these known techniques, and the conditions for stripping have been elucidated. At present, no technology has been developed to prevent the occurrence of surface defects in the step of taking the film or the like and transporting the film or the like to the subsequent post-drying step. In other words, the above-described known technique makes it possible to satisfactorily peel the film or the like from the support. The problem of eliminating a surface defect has not been solved.

[0011] This problem arises when it is desired to increase the film forming speed.
This has become apparent when it is desired to increase the thickness of a film or the like to be formed, or when the film is difficult to dry with a combination of a polymer resin and a solvent.

The problems of the prior art will be described in more detail as follows. An apparent glass transition temperature (Tg ′) of a polymer resin film or the like containing a residual solvent that has been peeled off from the support is significantly reduced. For example, JP-A-7-2
No. 99828 describes detailed data of glass transition temperature (Tg ′) of a polymer resin film or the like containing a residual solvent, that is, a graph showing the relationship between the apparent Tg ′ and the amount of the residual solvent.

In general, when Tg 'is low, if the temperature is close to room temperature, the film or the like is soft at room temperature. Therefore, the film or the like may be deformed even with a very low tension, and the film or the like comes into contact with the roller surface. This may cause a surface defect under the influence of the surface.

If the film and the like immediately after being peeled off from the support are examined in detail in relation to the residual solvent concentration and Tg ', the surface hardness of the film and the like differs on both sides. That is,
The surface that was in contact with the metal support was softer, and the surface that was not was harder. The hardness of the surface of the film or the like is influenced by the amount of the residual solvent and the temperature of the film at that time. The surface of the film or the like immediately after peeling from the body is clearly soft on the surface in contact with the support, while the surface on the opposite side of the support is harder than the surface of the support.

Such a phenomenon cannot be avoided when a liquid film or a film is dried on a support. In the drying process of the liquid film, evaporation of the solvent is prevented because one surface of the liquid film is in contact with the support, and the solvent mainly evaporates from the anti-support surface (the surface opposite to the surface in contact with the support). This is because desolvation occurs.

Since the film or the like containing the solvent immediately after peeling is exposed to the air, the solvent evaporates, and as a result, the film or the like rapidly contracts in both the running (longitudinal) direction and the horizontal direction. If the shrinkage occurs, for example, between rollers, such as a film, which are not constrained in the width direction, curl occurs with the surface containing a larger amount of solvent facing inward, and particularly the ends of the film or the like are curved. Also, if rapid shrinkage occurs on the roller surface, the film etc. will cause stick-slip on the take-up roller and transport roller, and the surface of the film etc. will have surface defects (especially scratches)
Is generated. This may also cause foreign matter to adhere to the roller surface.

[0017]

SUMMARY OF THE INVENTION
In the prior art, there is a problem that even if the peeling from a support such as a film is successfully performed, a surface defect occurs immediately after that, before the post-drying step is started. That is, a soft film or the like immediately after peeling off from the support adheres to the surface of the take-up roller or the conveying roller, accumulates, or attaches a foreign substance to the surface of the roller, or causes a problem that a defect occurs on the surface of the film or the like. . An object of the present invention is to provide a casting film forming method which solves the above problems and has no surface defects such as a film.

[0018]

Means for Solving the Problems The present inventors have made intensive studies on the casting film forming method and found the following points to complete the present invention. That is, use of a material having a non-adhesive surface that defines specific characteristics on the roller surface of the peeling roller and the transporting roller, specifically, sandblasting, surface roughening treatment by chemical etching, fluorine resin Using a roller with a surface coated or lined with a material and sprayed with ceramic, especially a fluororesin-coated roller, or a ceramic sprayed roller, to improve the surface hardness of a film or the like immediately before and / or immediately after peeling from a support. It has been found that a surface defect does not occur if a film or the like is wound around a roller and transported.

That is, the present invention is as follows. 1. A solution of a thermoplastic polymer compound is cast on a metal support to form a film, and then dried, peeled off from the support, and further post-dried. So,
At the time of peeling, the average solvent concentration in the film-like material is kept at 10 to 30% by weight, and the surface temperature of the support at the peeled portion is kept at 15 ° C or less and 5 ° C or more, and the film is peeled from the support The casting film forming method, wherein the roller surface of the take-off roller is made of a material having a non-adhesive surface.

2. 2. The casting film forming method according to the above item 1, wherein at least one of the conveying rollers after the take-up roller is made of a material having a non-sticky surface.

3. The roller surface of the take-up roller is made of a material containing a fluorine-based resin, and has a center line average surface roughness Ra in a range of 0.5 to 0.05 μm. Casting method.

4. At least one roller surface of the transport roller group after the take-off roller is made of a material containing a fluorine-based resin, and has a center line average surface roughness Ra in a range of 0.5 to 0.05 μm. 4. The casting film forming method according to any one of the above 1 to 3, wherein

5. 3. The flow according to the above item 1 or 2, wherein the roller surface of the take-up roller is surface-treated by ceramic spraying, and has a center line average surface roughness Ra in a range of 0.5 to 0.05 μm. Rolled film forming method.

6. The surface of at least one of the conveying rollers after the take-off roller is surface-treated by ceramic spraying, and the center line average surface roughness Ra is in the range of 0.5 to 0.05 μm. 6. The casting film forming method according to any one of the above 1, 2, 3 or 5.

[7] Air suction and / or air flow is provided near the surface of the film-like material wound around at least one of the take-up roller and the conveying roller group after the take-up roller.
The casting film forming method according to any one of the above 1 to 6, wherein a flow of air is generated by blowing.

8. Immediately before and / or immediately after peeling off the film from the support, an air flow is generated by suction or / and blowing of air near the surface of the film. Casting method.

Here, in the specification of the present application, the “roller surface” means a surface where the roller can come into contact with the film-like material.
The “average solvent concentration” means a value obtained by averaging the distribution of the content (concentration) in the thickness direction, the width direction, and the running direction (machine direction) of the film-like material. It can be determined. Further, in the specification of the present application, the term "film-like material" is used in a sense including from a liquid film state cast from a die to a so-called ordinary solid film or the like by removing a solvent. I have. Further, the “transport roller group” is a generic term for some transport roller groups. The term "distance between the support and the roller or between the rollers" refers to the distance between the support and the roller or between the rollers when the film is not in contact with either the support or the roller. means.

Hereinafter, the present invention will be described in more detail. In the following, a film will be mainly described, but it goes without saying that a sheet is also an object of the present invention.

All resins that can be produced by casting can be applied to the present invention. For example, cellulose resins, polycarbonate resins, polyarylate resins, polyolefin resins, polystyrene resins, vinyl chloride resins, acrylic resins, polysulfone resins, polyethersulfone resins, and mixtures of two or more of these or Copolymerization and the like can be mentioned.

Particularly preferred polymer resins are those based on aromatic polycarbonates. Hereinafter, polycarbonate will be described in detail, but the present invention is not limited thereto.

A) Aromatic Polycarbonate and Viscosity Average Molecular Weight There is no particular limitation on the aromatic polycarbonate used in the present invention as long as the desired properties such as a film can be obtained.

The polymer material generally referred to as an aromatic polycarbonate means a material obtained by polycondensation of a phenol derivative, phosgene, diphenyl carbonate and the like. 2, which is usually called bisphenol A
Aromatic polycarbonate represented by a repeating unit having 2-bis (4-hydroxyphenyl) propane as a bisphenol component (in the present specification, this “aromatic polycarbonate having bisphenol A as a bisphenol component” is referred to as “bisphenol A polycarbonate” Is preferably selected, but by appropriately selecting other various bisphenol derivatives together with 2,2-bis (4-hydroxyphenyl) propane, an aromatic polycarbonate copolymer can be constituted.

As such copolymerization components, bis (4-hydroxyphenyl) methane, 1,1-bis (4-hydroxyphenyl) cyclohexane (also referred to as bisphenol-Z), 9,9-bis (4-hydroxyphenyl)
Fluorene (also called bisphenol FL), 9,
9-bis (4-hydroxy-methylphenyl) fluorene, 1,1-bis (4-hydroxyphenyl) -3,
3,5-trimethylcyclohexane, 2,2-bis (4
-Hydroxy-3-methylphenyl) -2-phenylethane, 2,2-bis (4-hydroxyphenyl) -1,
1,1,3,3,3-hexafluoropropane, bis (4
-Hydroxyphenyl) diphenylmethane, bis (4-
(Hydroxyphenyl) sulfide, bis (4-hydroxyphenyl) sulfide, bis (4-hydroxyphenyl) sulfone and the like. It is also possible to use a polyester carbonate containing a terephthalic acid and / or isophthalic acid component as a part of the carbonic acid component. Thus, bisphenol A
The properties of the aromatic polycarbonate, for example, heat resistance and solubility, can be improved by substituting a part of the carbonic acid component with another structural unit.

The aromatic polycarbonate used in the present invention has a viscosity average molecular weight of 20,000 to 200,000.
If it is 0 or less, it is preferably used. Viscosity average molecular weight 2
If it is less than 000, the viscosity of the solution is too low, and it becomes difficult to control the film thickness. On the other hand, when the viscosity average molecular weight exceeds 200,000, the solution viscosity becomes too high and it is difficult to control the film thickness. Particularly preferred viscosity average molecular weight is 30,000 to 70,000.
0 or less.

B) Solvent for Dissolution The solvent used for dissolving the aromatic polycarbonate in the present invention is a solvent capable of obtaining a solution viscosity that can be cast, and a stability of the obtained solution in terms of crystal precipitation (crystals are formed). Difficult) and safety during preparation of the solution (sanitary to human body).

Examples of the solvent for dissolving the aromatic polycarbonate include methylene chloride, 1,3-dioxolan, chloroform, tetrahydrofuran, dioxane, tetrachloroethane, and 1,2-dichloroethane alone or a mixture of two or more.

Also preferably, methyl alcohol, ethyl alcohol, propyl alcohol (n-propyl alcohol, isopropyl alcohol or a mixture thereof), butyl alcohol (n- A secondary solvent such as butyl alcohol, isobutyl alcohol or a mixture thereof can be used alone or in combination of two or more. In this case, the amount of the alcohol is preferably 5% by weight or less, more preferably 0.1 to 5% by weight.

In the present specification, when the above alcohol or a mixture thereof is used, the alcohol or the mixture thereof is referred to as a sub-solvent,
When used together with these sub-solvents, the above-mentioned solvents other than these sub-solvents are called main solvents.

C) Preparation of Solution In the preparation of the solution of the present invention, when the solvent is used alone, aromatic polycarbonate pellets are charged and dissolved while stirring the solvent. When the solvent is a mixed solvent composed of a main solvent and a secondary solvent, for example, methylene chloride (main solvent)
And a mixed solvent of ethyl alcohol (co-solvent)
A mixed solvent is prepared in advance, and aromatic polycarbonate pellets are charged and dissolved while stirring.

It is desirable that the concentration of the aromatic polycarbonate in the solution used for the casting film is set to 10 to 30% by weight. When the concentration of the aromatic polycarbonate in the solution is less than 10% by weight, it is extremely difficult to obtain a film or the like having a good flatness due to an excessively large drying load such as a cast film. However, when the molecular weight of the aromatic polycarbonate is large, the solution viscosity becomes too high, and it is difficult to control the film thickness. When the molecular weight of the aromatic polycarbonate is small, the effect of the evaporation during the initial evaporation of the solvent is affected by the film. This is inconvenient because it adversely affects the surface flatness. A more preferred concentration is 17 to
28% by weight. The most preferable concentration can be determined by trial and error based on the relationship between the drying conditions at the time of film formation and the characteristics (quality) of the film or the like.

The solution is filtered using a commercially available filter to remove dust and gel-like substances. It has been found that a filter having an average aperture of 0.3 to 30 μm can be suitably used. In addition, several types having different average openings can be used in combination.

It is desirable that the fluctuation width of the solution immediately before casting (casting) be kept as small as possible in order to minimize the fluctuation of the volatilization behavior of the solvent thereafter. For example, 1
Heating (or cooling) at ± 0.5 ° C for 5 ° C setting
It has been found appropriate to control.

D) Casting and drying The temperature of the cast aromatic polycarbonate solution is:
In order to prevent rapid evaporation of the solvent from a film-like material such as a liquid film or a film, it is not desirable that the solvent is much higher than the boiling point of the solvent at the beginning of drying. It is cast via a die on a support under an atmosphere temperature-controlled at a temperature of from 0 ° C. to (Y + 5 ° C.). This temperature is more desirably (Y ° C.) or less, and still more desirably 5 ° C. to (Y ° C.).

As the support, stainless steel, a ferro-type plate, or polyethylene terephthalate, polyethylene-2,6-naphthalate or the like, as the case may be, can be used.

Industrially, an endless metal plate support is generally used. For the purpose of the present invention, a support obtained by mirror-polishing an endless metal plate is desirable for flattening the surface of a film or the like. The thickness of the film or the like is adjusted by the opening degree of the die. It is also possible to use a usual thick coating method such as a method of sweeping with a doctor blade or a reverse roller coater method. The most preferred method is to cast the solution from an extrusion die onto an endless metal belt support.

The support on which the aromatic polycarbonate solution is cast has a characteristic that the center line average surface roughness (Ra) is 1.0 to 3.0 nm, the maximum length is 50 μm or more, and the maximum depth is 5 μm or more. It has been found that it is preferable to use a mirror-polished material having the following.

Outside of these ranges, when the surface of the support becomes flatter, sufficient releasability of a film or the like cannot be obtained. Conversely, when the surface of the support becomes rough,
The surface of the film or the like is roughened due to the roughening of the surface of the support, and the surface of the film or the like becomes undesirably rough.

Usually, the purpose of drying a film or the like after casting is to evaporate a large amount of solvent in a short time without changing the form of the film or the like. If the solvent is rapidly evaporated, undesired phenomena such as bubbling from the surface of the film-like material and deterioration of the thickness due to deformation of the film or the like (such a phenomenon is called leveling defect) are exhibited.
It is necessary to pay close attention to factors that control the drying speed, such as the drying temperature and air volume.

Usually, in the early stage of drying, drying is performed at a temperature lower than or not higher than the boiling point of the solvent to be used, and after the solvent has volatilized to some extent, the drying temperature is increased to finally obtain the average solvent concentration. Until it is 10 to 30% by weight or less, and a semi-dried film or the like is peeled off from the support. The temperature of the film at the time of peeling is 15
The temperature of the support is controlled by adjusting the temperature of the support to 5 ° C to 5 ° C.

E) Peeling Step and Subsequent Steps The film whose temperature is controlled as described above is peeled from the support in the peeling step. Hereinafter, description will be made with reference to FIGS. 1, 2 and 3. FIG. 2 shows an example in which a nozzle is installed on a surface of a film wound around a roller, and an air flow is created by suction or blowing to reduce the amount of solvent vapor (concentration) on the film surface.

FIG. 3 shows an example in which a suction or blowing nozzle is installed in a process immediately before peeling a film from a support, and an air flow is created by suction or blowing to reduce the amount of solvent vapor (concentration) on the film surface. Is shown.

The film cast from the extrusion die 1 in FIG. 1 moves to the left as viewed in FIG. 1, and is dried until a predetermined solvent concentration is reached, and in the meantime, a mechanism not shown in FIG. The direction is reversed by the
Near the surface of the support 2. The film immediately after peeling is indicated by 3.

The film is immediately wound around the take-up roller 4, and then transport rollers 5, 6, 7, and 8
The film is transported to a post-drying step via a dancer roller 9 and further via a transport roller 10. These transport rollers 5, 6, 7, 8, dancer roller 9, and transport roller 10 are collectively referred to as “transport roller group”.
Say

The transport rollers are used as a group of rollers because the film immediately after being peeled off from the support causes the following phenomena, and causes a curl and a scratch caused by slipping on the rollers. This is because the above (surface defect) causes a problem.

That is, as described above, the film immediately after being peeled from the support has a remarkably large difference between the front and back sides of the solvent content. That is, the surface that is in contact with the support and dried to some extent has a significantly higher solvent content than the anti-support surface. As a result, after the film 3 is peeled off from the support, the solvent rapidly evaporates and shrinks. For this reason, the film curls with the surface in contact with the support inside and the film contracts in the width direction (perpendicular to the running direction). In order to minimize the curl and width shrinkage phenomena and to run (convey) the film smoothly, it is necessary to evaporate the solvent by minimizing the free span of the film (length of non-contact between the rollers). is there. It is preferable to use 4 to 5 transport rollers, but the required number is adjusted because it is determined by the average solvent concentration of the film immediately after peeling and the difficulty of scratching the subsequent film.

The dancer roller 9 is for controlling the tension applied to the film in the peeling step and the post-drying step to be constant, thereby suppressing a sudden change in the tension in the preceding and following steps. The rollers 8 and 10 are for holding the entrance and exit of the dancer roller 9. The roller 10 also serves as a roller at the entrance of the post-drying process.

The take-off roller 4 and the transport roller groups 5 to 10 are free-rotating rollers or tension rollers that rotate with as little force as possible so that the film can be transported with low tension. Usually, this tension is applied to the film via dancer rollers, but is of the order of 2-15 kg / m wide film.

The diameter of the roller is 1
00 to 150 mm, rollers 5 to 10 are 150 to 20
The thickness is preferably set to 0 mm in terms of equipment of a roller and film formation.
The temperature of the roller can be controlled from the inside by a heat medium as needed.

The distance between the support and the roller or between the rollers is 5 mm or less, preferably 3 mm or less, between the support 2 and the take-up roller 4.
If this is increased, there is a problem that the end portion of the film immediately after being peeled from the support is likely to be curled. Further, the film that has passed through the take-off roller 4 is further transferred to rollers 5, 6,
The film is passed through a group of conveying rollers 7 and 8, and in this case as well, it is preferable that the distance between these rollers is reduced to minimize the curl of the film and the slip on the rollers so that the film runs. The distance between the roller 4 and the transport roller 5 is preferably set to 50 mm or less. If this is set too large, curling of the film edge may occur and the edge may be bent when the roller contacts. Subsequent rollers 6,
Preferably, the distance between 7, 8 is also 50 mm or less,
The distance between these rollers can be determined empirically while observing the state of curling of the film and the state of occurrence of surface defects such as scratches.

The surface of the roller is preferably treated with a fluorine resin or ceramic spray. Usually, a known fluororesin can be applied to the surface of the metal roller, a film of the fluororesin can be applied, or the film can be formed by a known method. In the case of ceramic spraying, a material obtained by spraying a known spray material on a metal roller surface by a known method can be used.

In the case of ceramic thermal spraying, the thermal sprayed material often has minute holes, so that moisture penetrates and the base material is corroded, which may cause fine irregular surface defects on the roller surface. Therefore, it is preferable to perform a so-called sealing treatment by impregnating with a polymer resin or the like. One solution to this problem is to make the thermal spray material finer,
A ceramic sprayed surface having a very small particle size distribution is preferred. The surface of such a material can also be applied to the present invention.

In the present invention, the surface of the roller treated in this way has a surface roughness (Ra) of 0.05 to 0.5 μm.
The one controlled so as to be used is used. When Ra is outside this range, if the film is flatter than 0.05 μm, the film sticks to the roller surface, causing unevenness in take-up tension, which may cause so-called horizontal unevenness in which the thickness unevenness of the film deteriorates. . On the other hand, if the thickness is less than 0.5 μm, scratches are likely to occur on the film surface, which is not preferable. A more preferable range of the roller surface roughness Ra is 0.1.
0 to 0.35 μm. The adjustment of the surface roughness of the roller can be performed using various abrasives such as a grindstone and a polishing tape.

The suction or blowing nozzle 11 which can be used in the method of the present invention removes the solvent vapor present at a relatively high concentration on the film surface to increase the hardness of the film and to increase the film hardness when the film surface comes into contact with the roller surface. This is for preventing various surface defects from occurring. FIG.
In the above, the nozzle 11 has several vapor suction ports to improve the vapor removal efficiency. Nozzle 11
Can be used as a blow-out port, but it is preferable to use it by sucking and flowing gas on the film surface from the viewpoint of preventing contamination of the atmosphere.

[0064]

Embodiments of the present invention will be described below. The present invention is not limited by the embodiment.

(Evaluation of Surface Defect) In the present invention, the surface defect of the film was evaluated as follows. In the width direction of the post-dried film, an area of 10 cm × 10 cm was sampled at the center and both ends, and aluminum was vacuum-deposited on the film surface. This was observed with a differential interference microscope to detect the presence or absence of surface defects. That is, the presence or absence of peeling scratches, adhesive scratches, minute press scratches, scratches, and transcripts was examined. The sampling was performed every 10 hours in the longitudinal direction of the film. The measurement was performed after removing the solvent by drying.

(Measurement of Surface Roughness) The surface roughness of the roller surface material was measured with a surface roughness meter. TOKYO for measurement
SEIMITSU Co., Ltd. Handysurf E-3
OA was used. The surface roughness was represented by a center line average surface roughness Ra, and the unit was μm. This Ra is a value shown in a mechanical design drafting manual (Kiyoshi Onishi, Rigaku Corporation, pages 17 to 56).

(Measurement of Average Solvent Concentration) The average solvent concentration was determined by measuring the weight of the film before and after drying at a temperature of 170 ° C. for one hour, and calculating (the amount of solvent) / (the weight of the film containing the solvent before drying) from the measured value. ) X100%. In addition,
The sample used was a film immediately after being peeled off from the support.

Example 1 Aromatic polycarbonate resin (trade name “PANLITE (registered trademark)” manufactured by Teijin Chemicals Ltd.)
Grade C-1400QJ "), viscosity average molecular weight 38,
000 in a mixed solvent of ethanol and methylene chloride (ethanol 1.5% by weight, methylene chloride 98.
5% by weight) to make an 18% by weight solution.

This solution was passed through a filter (a filter manufactured by Advantech Co., Ltd., trade name: depth cartridge filter, TCPD-05A, average pore size: 0.5 μm) to remove foreign substances inside. Thus, a clean solution for casting was prepared. Then, the temperature of the solution and the support was raised to 1
Adjusted to 5 ± 0.5 ° C, and the thickness of the film after drying is 1
The solution was cast on a support by adjusting the thickness of the liquid film to be 00 μm. The support on which the solution was applied was dried at an ambient temperature of 25 ° C. for 3 minutes. Next, it was further dried at an ambient temperature of 50 ° C. for 5 minutes. Thereafter, the temperature was cooled to 10 ° C., and the film was peeled off from the support. At this time, the average solvent concentration in the film was 25% by weight.

As a take-up roller for the film immediately after peeling, a roller whose surface was coated with a fluororesin (monochlorotrifluoroethylene polymer) was used. Further, the surfaces of the rollers 5 to 10 were all covered with the fluororesin. The surface roughness Ra of these rollers was 0.1 μm. The take-up tension is controlled by the tension applied to the dancer roller.
It was Kg / 1m film width.

In this way, the film was passed through the roller shown in FIG. 1 and further dried from the roller 10 in a post-drying step by a pin tenter method. The distance between the rollers at this time was 3 mm between the support and the roller 4, the distance between the roller 4 and the transport roller 5 was 20mm, and the distance between the rollers 6 to 8 was also 20mm.

Thereafter, a sample was taken at the end of the drying step, and its surface defects were evaluated. This film is transferred,
There were no surface defects such as press scratches and scratches. Thus, continuous film formation was performed for 100 hours. During this time, surface defects were evaluated intermittently about every 10 hours. In this case, no surface defects occurred. In addition, the presence or absence of dirt on the roller surface was visually checked by illuminating with cadonica light, but no dirt was adhered. The obtained film was excellent as an aromatic polycarbonate film for optical use with very few surface defects.

[Comparative Example 1] All the surfaces of the take-up roller and the transport roller group were hard chrome plated (surface roughness R
A film was formed in the same manner as in Example 1 except that a = 0.04 μm). The average solvent concentration of the film immediately after peeling from the support was 25% by weight. As a result, in the initial stage of film formation, there was no problem of film adhesion at the take-up roller 4, but a phenomenon that the film surface was weakly adhered to the roller at the film transport roller 5 was caused. Had a horizontal streak. The surface of the roller began to stain after a few hours, and accumulated over time. Immediately after the peeling of the film, many minute surface defects occurred.

Example 2 A film was formed in the same manner as in Example 1 except that the surfaces of the take-up roller and the conveying roller group were all sprayed with chromium oxide. The surface roughness Ra of the chromium oxide sprayed surface was 0.18 μm. The average solvent concentration of the film immediately after peeling from the support was 25% by weight. The film after post-drying was good with little unevenness in thickness, no surface defects, and was flat and excellent. In addition, film formation was carried out using this roller for 100 hours, and an excellent optical film without surface defects was obtained. At this time, no foreign matter adhered to the roller surface.

Example 3 The surfaces of the take-up roller and the conveying roller group were all sprayed with chromium oxide (surface roughness Ra).
= 0.18 μm) and using the suction nozzle shown in FIGS. 2 and 3 and setting the average solvent concentration of the film immediately after peeling off from the support to 28.5% by weight. A film was formed in the same manner as described above. An air flow was created near the non-roller surface of the film by suction of the nozzle, and the solvent evaporated from the film surface was removed by suction. This serves to promote the evaporation of the solvent from the film and at the same time to lower the solvent concentration near the surface of the film and to increase the surface hardness to some extent (FIGS. 2 and 3). This film had no surface defects, was excellent in flatness, and was suitable for optical use.

[0076]

According to the casting film forming method of the present invention, a film excellent in flatness and free from peeling scratches, adhesive scratches, scratches and the like can be formed. The present invention provides a surface defect that occurs when a relatively thick film is manufactured at a high speed or when a film is formed using a polymer resin that is relatively difficult to dry (determined by a combination of a polymer resin and a solvent). Can be eliminated.

[Brief description of the drawings]

FIG. 1 is a schematic view showing a take-up roller and a group of transport rollers of a release film according to the present invention.

FIG. 2 shows an example of the details of the structure of another roller group according to the present invention.

FIG. 3 shows an example of the details of the structure of another roller group according to the present invention.

[Explanation of symbols]

 1. Extrusion die 2. 2. Metal support (endless belt) 3. Film peeled off from support surface Take-off roller 5. Transport roller 6. Transport roller 7. Transport roller 8. Transport roller 9. Dancer roller 10. Transport roller 11. A device for blowing and sucking air.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Hirofumi Yanagawa 77 Eki Kitayoshida-cho, Matsuyama-shi, Ehime Inside Teijin Co., Ltd. (72) Inventor Minoru Hirota 77-77 Kitayoshida-cho, Matsuyama-shi Ehime Ekihito Matsuyama Works F-term (reference) 4F205 AA16 AA28 AC05 AG01 AJ02 AJ03 AJ06 AJ11 AM28 AM30 AR06 AR13 GA07 GB02 GC06 GF01 GF24 GN22 GN24 GN28 GN29

Claims (8)

[Claims] 1. A method in which a solution of a thermoplastic polymer compound is cast on a metal support to form a film, dried, peeled off from the support, and further dried. A method of casting a film, wherein the average solvent concentration in the film at the time of peeling is 10 to 10.
30% by weight, and the surface temperature of the support is kept at 15 ° C. or lower and 5 ° C. or higher at the peeling portion, and the roller surface of the take-off roller when peeling the film from the support has a non-adhesive surface. A casting film forming method. 2. The method according to claim 1, wherein at least one of the transport rollers after the take-up roller has a non-sticky surface.
The casting film forming method according to the above. 3. The take-up roller, wherein the roller surface is made of a material containing a fluorine-based resin, and the center line average surface roughness Ra is in a range of 0.5 to 0.05 μm. Item 3. The casting film forming method according to item 1 or 2. 4. The surface of at least one of the conveying rollers after the take-up roller is made of a material containing a fluorine-based resin, and has a center line average surface roughness Ra of 0.5 to 0.5. The casting film forming method according to any one of claims 1 to 3, wherein the thickness is in a range of 05 µm. 5. The take-up roller according to claim 1, wherein the roller surface is surface-treated by ceramic spraying, and the center line average surface roughness Ra is in the range of 0.5 to 0.05 μm. Or the casting film forming method according to 2. 6. The surface of at least one of the conveying rollers after the take-up roller is surface-treated by ceramic spraying, and has a center line average surface roughness Ra of 0.5 to 0.05 μm. The casting film forming method according to any one of claims 1, 2, 3, and 5, which is within a range. 7. A method for generating a flow of air by suction and / or blowing of air in the vicinity of the surface of a film-like material wound around at least one of a take-up roller and a group of transport rollers after the take-up roller. The casting film forming method according to any one of claims 1 to 6, wherein 8. An air flow is generated immediately before and / or immediately after peeling off the film from the support by suction and / or blowing of air near the surface of the film. The casting film forming method according to any one of the above.