JPH08309942A - Manufacture of thermoplastic resin film - Google Patents

Abstract

PURPOSE: To obtain a resin film having no surface defect, excellent in productivity and with respect to cost by providing a coating step for an unoriented film having high transparency and a flat surface, and then orienting it in one direction. CONSTITUTION: Thermoplastic resin to be applied is not particularly limited if the resin can be oriented as a film, and a polyester or the like containing polyethylene terephthalate, polyethylene-2,6-naphthalate or their copolymer is preferable. The coating agent of a primer layer is used without limiting to a coating layer of a second layer, and water soluble or water dispersible polyester resin is used. As a gelatin easily stickly layer coating agent, water soluble or water dispersible acrylic resin is preferable. As a method for coating with coating liquid, a reverse roll coater or a gravure coater is used. The centerline means roughness Ra of unoriented film is 10nm or less, a base H1 is 5.0% or less, and a particle content C is 1.0ppm or more.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing a thermoplastic resin film. More specifically, it relates to a method for producing a film having a coating layer.

[0002]

2. Description of the Related Art Generally, as a method for improving the film winding property and the film handling property in the final step of film production, fine particles are added to the film, A method is known in which the protrusions are brought out to reduce the coefficient of friction and impart slipperiness.

However, in applications where transparency is particularly required, such as a glass shatterproof film attached to window glass, it is not preferable to add a large amount of particles to the film in order to ensure transparency. In addition, even in applications such as light-shielding films and gold and silver threads obtained by depositing a metal, when a large amount of particles are added to the film, minute projections formed by the appearance of the added particles, It is not preferable because the appearance of the film is significantly impaired.

Therefore, when transparency and surface smoothness are required as in the above-mentioned applications, the surface of the film containing a very small amount of particles has smoothness by in-line coating or off-line coating. It is generally practiced to reduce the friction coefficient of the surface while maintaining transparency by providing a coating layer. Further, in the thermoplastic resin, orientation is imparted by stretching for the purpose of imparting mechanical strength. In the generally adopted sequential biaxial stretching method, after orientation is imparted by a roll stretching machine equipped with a plurality of rolls in the longitudinal direction (longitudinal direction) of the film,
A tenter method in which an end portion of the film is gripped and stretched in a direction perpendicular to the longitudinal direction (transverse direction) is adopted to obtain a biaxially oriented film. When the thermoplastic film has crystallinity, it is biaxially stretched and then crystallized.

When performing in-line coating, in the sequential biaxial stretching method, it is common to provide a coating step after longitudinal stretching and before transverse stretching. That is, the tenter method is a method of gripping the film end portion, heating the film with heated air, and then stretching in the lateral direction.Therefore, if the coating is performed before the lateral stretching, the roll is applied to the coating layer provided in the coating step. This is because there is a great merit that it is possible to dry the coating layer with heated air without bringing them into contact with each other. further,
Especially in the case of polyester, the transverse stretching ratio is often 3 times or more, and since the width of the film before transverse stretching is narrower than that after transverse stretching, there is also an advantage that the coating equipment can be downsized.

By the way, in the roll stretching method, tension is generated in the film during stretching. Therefore, in order to prevent defects such as scratches on the film surface, it is important to grip the film on the roll so as not to slip. . However, particularly when the transparency of the film is high, the film is slipped on the roll due to the linear expansion of the film in the preheating roll before the longitudinal stretching and the stretching force generated on the stretching roll, causing a defect such as a scratch on the film surface. Was inevitable. For this reason, even if the basic performance of the coating layer provided on the film after longitudinal stretching is sufficient, uncoated portions may partially occur due to defects such as scratches on the film surface before coating. , Even if the film surface is completely coated, there is a problem that the appearance of the film is significantly impaired by defects such as scratches existing on the film surface before coating,
It was present especially when producing transparent films.

Further, the demands on the coating layer have become stricter year by year, and characteristics which cannot be dealt with by only one layer are being demanded. In addition, in general, in the in-line coating method, since enormous cost is required to make a large-scale equipment explosion-proof, water must be used as a main solvent of the coating agent, and thus coating defects are likely to occur.

Due to the above-mentioned defects in the pre-coated film, coating defects such as uncoated portions inevitably occur,
In addition to the problem of significantly impairing the film appearance and properties, there is also a problem that coating defects are likely to occur due to poor adhesion between the film and the coating layer due to the use of a water-based or water-dispersed coating agent. It was Attempts have also been made to improve the adhesiveness with a coating agent by performing a discharge treatment such as a corona treatment before coating, but the effect was very small with a very specific coating solution, and it was completely inadequate.

[0009]

As a result of intensive studies to solve the above problems, the present inventors have found that the above problems can be solved by providing a specific coating step, and complete the present invention. Came to.

That is, the gist of the present invention is a method for producing a thermoplastic resin film, characterized in that, in the step of producing a thermoplastic resin film, the unstretched film is coated on at least one side and subsequently stretched in at least one direction. Exist in.

The present invention will be described in detail below. The thermoplastic resin applied to the present invention is not particularly limited as long as it can be stretched as a film, but for example, polyethylene terephthalate, polyethylene-2,6-naphthalate or polyesters containing a copolymer thereof, nylon 6 , Nylon 66, nylon 610, nylon 11,
Aliphatic polyamide containing Nylon 12 or its copolymer, aromatic polyamide, polyethylene, polypropylene, polystyrene, poly-4-methyl-1-pentene, polyvinyl chloride, vinyl-based polymer containing its copolymer, polyvinylidene chloride Examples thereof include polymers. In particular, polyester containing polyethylene terephthalate, polyethylene 2,6 naphthalate or a copolymer thereof is preferable. In the thermoplastic resin used in the present invention, within a range that does not adversely affect the quality,
It may contain a stabilizer, an antistatic agent, a coloring agent, an ultraviolet absorber, a flame retardant and the like.

Any known coating agent may be used in the present invention, and is not particularly limited as long as it does not impair the required properties for the film. In the present invention, the properties of static prevention and easy adhesion, heat resistance and static prevention can be imparted by applying the coating on one side at least twice or more. In particular, it is excellent in application to special applications such as easy adhesion of gelatin in photographic applications, and can impart a composite function.

In applications where transparency and surface flatness are required, by changing the thickness of the coating layer and the composition of the coating liquid, not only slipperiness but also deterioration of the required quality can be prevented. It also becomes possible to impart functions such as antistatic property and adhesive property. Further, it is effective to add fine inorganic or organic particles to the coating layer. Furthermore, in the coating layer of the present invention, if necessary, an antifoaming agent, a coatability improving agent, a thickener, a low molecular weight antistatic agent, an organic lubricant, an antioxidant, an ultraviolet absorber, a foaming agent, a dye, You may contain a pigment etc.

The coating agents that can be used in the present invention are exemplified below, but the present invention is not limited to the following examples. For example, the following known techniques may be used, such as one that is effective for improving the adhesiveness with printing ink, adhesiveness with a laminating film, and one that imparts heat sealability.
That is, Japanese Patent Publication No. 47-3637 and Japanese Patent Laid-Open No. 50-
No. 34065, JP-A No. 50-115284,
JP-A-51-11870 and JP-A-50-3191
4, JP-A-51-87577, JP-B-49
No. 38703, Japanese Patent Publication No. 49-38704,
Japanese Unexamined Patent Publication No. 48-85757, Japanese Patent Publication No. Sho? -25917
JP-A-49-18978, JP-A-49-
No. 103970, No. 49-103971, No. 50-150782, No. 48-2.
No. 8077, No. 48-8329, No. 48-89237, No. 48-1068, No. 48-76978, No. 52-98.
074, JP-A-54-150442, JP-B-45-2104, JP-B-46-109,
JP-B-46-1114, JP-B-46-42240
JP-B, JP-B-47-25281, JP-A-48-
No. 22577, JP-A-49-59875, JP-A-51-62878, and JP-A-55- ?. 2649
JP, JP-A-56-12862, JP-A-57-
Technologies such as Japanese Patent No. 131555 can be used.

In magnetic tape applications, known coating agents known for improving the adhesion to the magnetic layer can be used. Use a technique of applying various coupling agents in order to prevent the precipitation of oligomers in films such as liquid crystal panel applications, perpendicular magnetic film applications, transparent conductive film applications, etc. that require heating in processes such as vapor deposition. You can also

Further, in photography and plate-making applications, JP-A-54-96590, which is applied to improve the adhesiveness of an adhesive layer applied to gelatin, PVA, etc., can be used. The coating agent for the application and the method for forming the coating agent will be described in detail below. In order to improve the adhesiveness with the photographic image forming layer, it is preferable to provide the coating layer on the film surface in two steps. In order to prevent the coating thickness from being uniform and to prevent coating defects during stretching, these coating layers are formed by the first layer after the die-extruded molten sheet is rapidly solidified by a rotating cooling drum during the film production process and before the longitudinal stretching. (Primer layer)
Is preferably applied to the second layer (subbing layer) after drying and before longitudinal stretching. In particular, as the subbing layer, the gelatin easy-adhesion layer may be applied after longitudinal stretching.

The coating material for the primer layer is not limited to the coating material for the second layer, and examples thereof include:
Examples thereof include water-soluble or water-dispersible polyester resins. A preferred example is a copolyester in which the dicarboxylic acid component is a blend of terephthalic acid or isophthalic acid and sodium isophthalic acid 5-sulfonate, and the glycol component is ethylene glycol. The amount of the copolymerized polyester resin in the coating layer is
It is preferably at least 30% by weight (solid content conversion). Further, the thickness of the coating layer is usually 0.001 to 1 in the final dry thickness.
The range is 1 μm, and the limit is preferably 0.01 μm or less.

An anionic surfactant or a cross-linking agent may be added to the coating liquid for the primer layer for surface modification. Examples of the anionic surfactant include sodium lauryl sulfonate, sodium dodecylbenzene sulfonate, sodium alkyl allyl ether sulfonate, and the like, and examples of the cross-linking agent include melamine formaldehyde. The amount of these additives is preferably in the range of 1 to 15%, more preferably in the range of 2 to 3%, based on the copolyester.

The primer layer preferably contains particles. Specifically, inorganic particles such as silica, silica sol, alumina, alumina sol, zirconium sol, kaolin, talc, calcium carbonate, calcium phosphate, titanium oxide, barium sulfate, carbon black, molybdenum sulfide, and antimony oxide sol are used as organic particles. Polystyrene, polyethylene, polyamide, polyester,
Examples thereof include fine particles containing or not containing a cross-linking agent composed of a homo- or copolymer such as polyacrylic acid ester, epoxy resin, polyvinyl acetate or polyvinyl chloride, and fine particles such as silicone resin and fluororesin.

The gelatin easy-adhesion layer coating agent is a water-soluble or water-dispersible acrylic resin, which is a hard monomer that can be a raw material for acrylic resins such as alkyl acrylate, alkyl methacrylate, styrene, acrylonitrile, and vinyl acetate. 70% by weight of these components, and the amount of these components is 30 to 100 mol%, and the vinyl monomer component 70 is copolymerizable and has a functional group.
It is preferably a water-soluble or water-dispersible resin containing ˜5 mol%.

Examples of alkyl groups of alkyl acrylate and alkyl methacrylate include methyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, 2-ethylhexyl group, lauryl group, stearyl group and cyclohexyl group. Can be mentioned. The vinyl monomer which is copolymerizable and has a functional group is preferably a vinyl monomer having a functional group that improves adhesion to a substrate or a functional layer, or affinity to other coating agents. . The preferred functional group is a carboxyl group, or a salt thereof, an acid anhydride group, a sulfonic acid group or a salt thereof, an amide group or an alkylolated amide group, an amino group (including a substituted amino group) or an alkylolated group. An amino group or a salt thereof, a hydroxyl group, an epoxy group and the like. Particularly preferred are a carboxyl group or a salt thereof, an acid anhydride group, an epoxy group and the like. Two or more kinds of these groups may be contained in the resin.

As the vinyl monomer having a functional group to be copolymerized, the following compounds having a functional group such as a reactive functional group, a self-crosslinking functional group and a hydrophilic group can be used. Examples of the compound having a carboxyl group or a salt thereof, or an acid anhydride group include acrylic acid, methacrylic acid, itaconic acid,
Examples thereof include maleic acid, metal salts of these carboxylic acids with sodium and the like, ammonium salts and maleic anhydride. Examples of the compound having a sulfonic acid group or a salt thereof include vinyl sulfonic acid, styrene sulfonic acid, metal salts of these sulfonic acids with sodium, ammonium salts and the like.

Examples of the compound having an amide group or an alkylolated amide group include acrylamide, methacrylamide, N-methylmethacrylamide, methylol acrylamide, methylol methacrylamide,
Examples thereof include ureido vinyl ether, β-ureido isobutyl vinyl ether, and ureido ethyl acrylate.

The compounds having an amino group or an alkylolated amino group or a salt thereof include diethylaminoethyl vinyl ether, 2-aminoethyl vinyl ether, 3-aminopropyl vinyl ether, and 2
-Aminobutyl vinyl ether, dimethylaminoethyl methacrylate, dimethylaminoethyl vinyl ether, those obtained by methylating their amino groups, alkyl halides; those obtained by quaternization with dimethylsulfate, sultone and the like.

Examples of the compound having a hydroxyl group include β-hydroxyethyl acrylate, β-hydroxyethyl methacrylate, β-hydroxypropyl acrylate, β
-Hydroxypropyl methacrylate, β-hydroxy vinyl ether, 5-hydroxypentyl vinyl ether, 6-hydroxyhexyl vinyl ether, polyethylene glycol monoacrylate, polyethylene glycol monomethacrylate, polypropylene glycol monoacrylate, polypropylene glycol monomethacrylate and the like can be mentioned. Examples of the compound having an epoxy group include glycidyl acrylate and glycidyl methacrylate.

In addition to the above compounds, the following compounds may be used in combination. That is, butyl vinyl ether, maleic acid mono- or dialkyl ester, fumaric acid mono- or dialkyl ester, itaconic acid mono- or dialkyl ester, methyl vinyl ketone, vinyl chloride, vinylidene chloride, vinyl pyridine, vinyl pyrrolidone, vinyl trimethoxysilane and the like can be mentioned. However, it is not limited thereto.

The water-soluble or water-dispersible acrylic resin which can be used in the present invention is preferably a coating agent using water as a medium for safety and hygiene, but within the scope of the present invention, An organic solvent may be contained as an auxiliary agent for the water-soluble or water-dispersible resin. When water is used as a medium, it may be a coating agent forcibly dispersed with a surfactant or the like, but is preferably a hydrophilic nonion component such as polyethers or a cationic agent such as a quaternary ammonium salt. A self-dispersion type coating agent having a group, and more preferably a water-soluble or water-dispersible coating agent having an anionic group. The water-soluble or water-dispersible coating agent having an anionic group is a compound having an anionic group bound to a resin by copolymerization or grafting,
It is appropriately selected from sulfonic acid, carboxylic acid, phosphoric acid and salts thereof.

The gelatin easy-adhesion coating liquid may contain particles for improving the slipperiness of the coating layer. As the type of particles, inorganic particles, organic particles, etc. exemplified in the primer layer can be used. For the gelatin easy-adhesion layer coating liquid,
To improve the adhesion (blocking property), water resistance, solvent resistance, and mechanical strength of the coating layer, a methylated or alkylated urea-based or melamine-based crosslinking agent is used.
Guanamine-based, acrylamide-based, polyamide-based compounds, isocyanate-based compounds, epoxy-based compounds, aziridine compounds, silane coupling agents, titanium coupling agents, zirco-aluminate-based coupling agents, peroxides, heat Also, a photoreactive vinyl compound or a photosensitive resin may be contained. In addition, if necessary, an antifoaming agent,
It may contain a coating property improver, a thickener, an antistatic agent, an organic lubricant, an antioxidant, an ultraviolet absorber, a foaming agent, a dye, a pigment and the like.

In addition to the above acrylic-based coating agent, another type of acrylic resin, urethane-based resin, ester-based resin, vinyl-based resin or the like may be added to the coating solution of the present invention to improve the coating solution or coating layer. May be contained in. A reverse roll coater, a gravure coater, a rod coater, a bar coater, an air doctor coater, etc. shown in "Coating Method" by Yuji Harasaki, Maki Shoten, 1979 is used as a method for applying the above-mentioned coating liquid to a polyester film. be able to.

The coating liquid used in the present invention may contain a small amount of an organic solvent for the purpose of improving dispersion in water or improving film forming performance, as long as water is the main medium. Examples of the organic solvent include aliphatic or alicyclic alcohols such as n-propyl alcohol, n-butyl alcohol, isopropyl alcohol, and ethyl alcohol, propylene glycol, ethylene glycol,
Glycols such as diethylene glycol, n-butyl cellosolve, ethyl cellosolve, methyl cellosolve, glycol derivatives such as propylene glycol monomethyl ether, ethers such as dioxane and tetrahydrofuran, esters such as ethyl acetate and amyl acetate, methyl ethyl ketone, acetone And the like, and amides such as N-methylpiolidone. However, the present invention is not limited to these. These organic solvents may be used alone or in combination of two or more if necessary.

The thickness of the coating layer of the film of the present invention is usually in the range of 0.001 to 2.0 μm as the final dry thickness. In particular, when the coating step is performed twice or more, the first step is primer coating and the second step is subbing, and the primer coating layer thickness is tp and the subbing coating layer thickness is tsi (i = 1 to n, n is Natural number),
It is preferable that 0.001 μm ≦ tp + Σtsi <2.0 μm. Further, when tp / tsi ≦ 1, it is suitable for function expression.

The unstretched film is obtained by rapidly cooling and solidifying a molten sheet extruded from a die on a rotating cooling drum to a temperature not higher than the glass transition temperature, to obtain a substantially amorphous unoriented sheet. It may be a single layer or a multilayer. It may be an unstretched film containing particles only in the outermost layer. The number of defects on the film surface generated by the roll stretching machine increases as the Ra of the unstretched film decreases,
The smaller the haze, the more. Therefore, particularly in a highly transparent film, 1 ppm or more of inorganic or organic fine particles may be contained in a range not deteriorating the appearance and performance of the film, but the centerline average roughness Ra of the unstretched film is usually 10 nm or less, It is preferably 8 nm or less, more preferably 6 nm or less, and the film haze H1 is 5% or less,
When the content is preferably 4% or less, the application of the present invention does not cause surface defects such as scratches during longitudinal stretching, and the effect of the present invention is remarkable.

In order to improve the flatness of the sheet, it is preferable to improve the adhesion between the sheet and the rotary cooling drum,
In the present invention, the electrostatic application adhesion method and / or the liquid application adhesion method are preferably adopted. What is the electrostatic application contact method?
Usually, a linear electrode is placed on the upper surface of the sheet in a direction orthogonal to the flow of the sheet, and a static voltage is applied to the sheet by applying a DC voltage of about 5 to 10 kV to improve the adhesion to the drum. It is a method to let. In addition, the liquid application contact method is a method for improving the adhesion between the drum and the sheet by uniformly applying the liquid to the whole or part of the surface of the rotary cooling drum (for example, only the portions that contact both ends of the sheet). Is. In the present invention, both may be used together if necessary.

In the present invention, the sheet thus obtained is coated and then stretched in at least a uniaxial direction to form a film. By applying the coating to the unstretched sheet, it is possible to prevent scratches and coating defects from occurring on the film. The biaxial stretching conditions will be specifically described. The unstretched sheet is preferably in a temperature range of 70 to 150 ° C., more preferably 75 to 130 ° C., and is first unidirectionally stretched to 3.0 to 7 by a roll type stretching machine. Double, preferably 3.2
Stretch 6 times. Next, it is stretched in a direction orthogonal to the first stage at a temperature range of preferably 75 to 150 ° C., more preferably 80 to 140 ° C. by a factor of 3.2 to 7 times, preferably 3.5 to 6 times, and biaxially stretched. Obtain an oriented film. A method in which unidirectional stretching is performed in two or more stages can be used, but in that case as well, it is desirable that the final stretching ratio falls within the above range. It is also possible to simultaneously biaxially stretch the unstretched sheet so that the area ratio becomes 10 to 40 times.

The film thus obtained is used in the range of 150 to 25
Heat treatment is performed at 0 ° C. for 30 seconds or less, limited shrinkage, or constant length for 1 second to 5 minutes. 110 after biaxial stretching
A method of re-stretching 1.05 to 2.0 times in the machine direction at a temperature of ℃ to 180 ℃, followed by heat treatment can also be adopted. At this time, a method such as heat setting before re-longitudinal stretching, longitudinal relaxation after re-longitudinal stretching, or before or after re-longitudinal stretching and fine stretching in the longitudinal direction can be appropriately adopted. Further, re-stretching may be performed in the transverse direction as well. In addition, various surface treatments may be performed in the film forming process as needed.

When the film thickness is large, the haze value increases when a large amount of particles are added to the polymer, so that it is difficult to add a large amount of particles especially in the case of a highly transparent film. The present invention is preferably applied to such a case. In order to bring out the effect of the present invention, the haze value of the final film is 10% or less, preferably 6% or less, and particularly preferably 3% or less. Film thickness is 15
It is more effective if it is at least μm, preferably at least 20 μm, more preferably at least 25 μm. The surface in contact with the cooling drum, low molecular weight components such as oligomers accumulated near the film surface during rapid cooling are present more than the opposite surface, and by preheating before stretching, these low molecular weight components are deposited on the film surface, Since there is a problem that scratches or the like may occur on the film surface due to sticking to a roll, it is particularly preferable to apply the coating to the surface in contact with the cooling drum before longitudinal stretching.

[0037]

EXAMPLES The present invention will be described in more detail with reference to examples below, but the present invention is not limited to the following examples as long as the gist thereof is not exceeded. The evaluation methods in Examples and Comparative Examples are as follows.

(1) Centerline average roughness (Ra) The average roughness was measured as follows using a surface roughness measuring device (SE-3F) manufactured by Kosaka Laboratory Ltd. That is, a portion having a reference length L (2.5 mm) is extracted from the film cross-section curve in the direction of the center line, and the center line of the extracted portion is taken as the x-axis, and the direction of longitudinal magnification is taken as the y-axis. When represented by f (x), the value given by the following equation was represented by [μm]. The center line average roughness was represented by the average value of the center line average roughness of the extracted portions obtained from the 10 section curves obtained from the surface of the sample film. The tip radius of the stylus was 2 μm, the load was 30 mg, and the cutoff value was 0.08.
mm.

[0039]

[Number 1] Ra = (1 / L) ∫ L 0 | f (x) | dx

(2) Haze (H1) According to JIS-K6714, the haze was determined by an integrating sphere type turbidimeter NDH-20D manufactured by Nippon Denshoku Industries Co., Ltd. (3) Appearance of Film (Scratch) The film was illuminated with a flashlight in a dark room to check for defects such as scratches and other uncoated portions due to scratches. A mark with no scratches is indicated by ⊚, a mark with all scratches or other defects is indicated by ×, and an intermediate mark is indicated by ◯ or Δ.

Example 1 Polyester having an intrinsic viscosity of 0.58 containing Sylysia 150 was dried, melt-extruded, and then cooled and solidified on a casting drum to form an unstretched amorphous film. At that time, the electrostatic contact method was adopted. The film thus obtained had an Ra of 5 nm and a haze of 3%. After applying the first coating to the surface of the obtained unstretched film that is in contact with the casting drum using a bar coater, the film is stretched 3.5 times in the longitudinal direction at 85 ° C. by a roll stretching machine, and 95 ° C. by a tenter method. After stretching in the transverse direction at 3.7 times, 2
The film was heat set at 35 ° C. and wound to obtain a film having a thickness of 25 μm. The composition of the coating agent used for the first coating, that is, the coating agent for the primer coating is as follows. The evaluation results of the obtained film are shown in Table 1 below.

Primer coating agent Copolymerized polyester (consisting of isophthalic acid and 5-sodium sulfoisophthalic acid in a molar ratio of 9: 1, and all of these acid components and ethylene glycol in an equivalent molar ratio)
10%, hexamethoxymethylmelamine (Cymel 303 manufactured by American Cynamid) 1.0%, surfactant (Rhodacal L manufactured by Rhone Poulin)
DS-10) 0.284%, fluorinated surfactant (3M
Fluorad FC-170C) 0.07%,
Colloidal silica (Nalco Chemical Co. Nalco
1060) 1.2% and deionized water 87.446
% Coating agent

Example 2 After applying the first coating, a roll stretching machine was used to make 8
Except that the second coating is applied after stretching 3.5 times at 5 ° C.
A 25 μm film was obtained in the same manner as in Example 1.
The coating composition used for the second coating, that is, the coating composition of the subbing coating is as follows. Table 1 shows the evaluation results of the obtained film.

Subbing coating agent Polymer A (Gantrez AN-139 manufactured by International Specialty Products) 35.5
%, Polymer B (Versa TL72 manufactured by National Starch and Chemical Co., Ltd.) 22%, compound C (triethylene glycol) 42.5% and fluorosurfactant () 0.7% (total of polymer A, B and compound C) Water-based coating agent containing 13.5%)

Comparative Example 1 A 25 μm film was obtained in the same manner as in Example 1 except that the first coating was applied after longitudinal stretching. Comparative Example 2 A 25 μm film was obtained in the same manner as in Example 1 except that the first coating was not applied.

[0046]

[Table 1]

[0047]

EFFECT OF THE INVENTION In the method for producing a thermoplastic resin film of the present invention, by providing a coating step on an unstretched film having high transparency and a flat surface, there are no surface defects and productivity is improved.
It provides a cost-effective method and its industrial value is very high.

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Claims (3)

[Claims] 1. A method for producing a thermoplastic resin film, characterized in that, in the step of producing a thermoplastic resin film, the unstretched film is coated on at least one side and then stretched in at least one direction. 2. The centerline average roughness Ra of the unstretched film,
The haze (H1) and the particle content (C) are represented by the following formula (1),
(2) and (3) are satisfied simultaneously, The manufacturing method of the thermoplastic resin film of Claim 1 characterized by the above-mentioned. Ra ≦ 10 nm (1) H1 ≦ 5.0% (2) C ≧ 1.0 ppm (3) 3. The heat according to claim 1, wherein after providing the first coating layer on the unstretched film, at least one or more coating layers are further provided on the first coating layer. A method for producing a plastic resin film.