JP2018030120A - Method for producing coating film - Google Patents

Abstract

A method for producing a coated film capable of suppressing the occurrence of defects in a coated layer is provided. A first step of coating a thermoplastic resin film with a coating liquid having a liquid temperature T containing an organic solvent A, an organic solvent B, and a solute, and forming the coating liquid layer; A method for producing a coating film, comprising a second step in which the layer of the working liquid is exposed to an atmosphere having a dew point temperature Tr and a third step in which the layer of the coating liquid is dried in this order, The solubility CA of the organic solvent A in water at CA, the solubility CB of the organic solvent B in water at 20 ° C., the evaporation rate VA of the organic solvent A assuming the evaporation rate of butyl acetate as 1, and the evaporation rate of butyl acetate A method for producing a coated film, wherein the evaporation rate VB, the liquid temperature T, and the dew point temperature Tr of the organic solvent B set to 1 satisfy a predetermined relationship. [Selection figure] None

Description

  The present invention relates to a method for producing a coated film.

  A method for producing a coated film by coating a coating solution on a thermoplastic resin film has been conventionally known. In this production method, a coating liquid is usually applied onto a thermoplastic resin film to form a coating liquid layer. Then, this coating liquid layer is dried to obtain a coating film including a thermoplastic resin film and a coating layer (see Patent Document 1).

JP 2002-326049 A

  In the manufacturing method of the coated film, brushing may occur. Here, brushing refers to a phenomenon in which condensation heat is generated on the surface of the coating liquid layer due to the loss of heat of vaporization from the coating liquid layer due to the volatilization of the solvent and a decrease in the temperature of the coating liquid layer. . Such brushing is usually caused by volatilization of the solvent contained in the coating liquid layer during the period from the formation of the coating liquid layer to the drying. When brushing occurs, depressions or protrusions are generated on the surface of the coating layer due to the action of condensation, and these depressions or protrusions may appear as defects in the coating film.

  In order to suppress the occurrence of defects due to brushing, the inventors tried to suppress the occurrence of condensation. Specifically, in the period from the formation of the coating liquid layer to drying, the atmospheric temperature is set to be significantly higher than the dew point, so that condensation does not occur and defects are suppressed. Tried.

  However, in the period from the formation of the coating liquid layer to the drying, it is difficult to sufficiently suppress the occurrence of defects in the coating film even if the atmospheric temperature is set to be much higher than the dew point.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a method for producing a coating film capable of suppressing the occurrence of defects in the coating layer.

The present inventor has intensively studied to solve the above-described problems. As a result, the present inventors combined a plurality of organic solvents having different solubility in water and satisfying a predetermined relationship as the solvent of the coating liquid, and adjusting the liquid temperature at the time of coating the coating liquid Furthermore, the present inventors have found that the occurrence of defects in the coating layer can be suppressed by controlling the dew point temperature of the atmosphere until the drying after coating of the coating liquid.
That is, the present invention includes the following.

[1] A first step of coating a thermoplastic resin film with a coating liquid having a liquid temperature T containing an organic solvent A, an organic solvent B, and a solute, and forming a layer of the coating liquid;
A second step in which the coating liquid layer is exposed to an atmosphere having a dew point temperature Tr;
A third step of drying the layer of the coating solution, in this order, a method for producing a coating film,
Solubility C _{A of} the organic solvent A in water at 20 ° C.,
Solubility C _{B of} the organic solvent B in water at 20 ° C.,
The evaporation rate V _{A of} the organic solvent A with the evaporation rate of butyl acetate being 1,
The evaporation rate V _{B of} the organic solvent B with an evaporation rate of butyl acetate as 1,
The liquid temperature T, and
The dew point temperature Tr is expressed by the following formulas (1) to (4):
C _A > C _B (1)
V _A −V _B > 1.5 (2)
8 ° C>T-Tr> 0 ° C (3)
20 ° C>T> 10 ° C (4)
The manufacturing method of the coating film which satisfy | fills.
[2] The solubility C _A is 100 g / L or more,
The solubility _{C B} is less than 100 g / L, (1) method for producing a coating film according.
[3] The method for producing a coated film according to [1] or [2], wherein both the organic solvent A and the organic solvent B are poor solvents for the thermoplastic resin film.
[4] One of the organic solvent A and the organic solvent B is a poor solvent for the thermoplastic resin film,
The method for producing a coated film according to [1] or [2], wherein the other of the organic solvent A and the organic solvent B is a good solvent for the thermoplastic resin film.
[5] The method for producing a coated film according to any one of [1] to [4], wherein the thermoplastic resin film contains a cycloolefin polymer.

  According to the production method of the present invention, a coated film can be produced while suppressing the occurrence of defects in the coated layer.

  Hereinafter, the present invention will be described in detail with reference to examples and embodiments, but the present invention is not limited to the examples and embodiments shown below, and the claims of the present invention and the equivalent scope thereof Any change can be made without departing from the scope of the invention.

  In the following description, the term “(meth) acryl” encompasses both acrylic and methacryl, the term “(meth) acrylonitrile” encompasses both acrylonitrile and methacrylonitrile, and the term “(meth) acrylate” Includes both acrylates and methacrylates.

[1. Outline of Embodiment of Manufacturing Method of Coating Film]
The manufacturing method of the coating film which concerns on one Embodiment of this invention apply | coats the coating liquid of the liquid temperature T containing the organic solvent A, the organic solvent B, and a solute on a thermoplastic resin film, A first step of forming a layer; a second step in which the layer of the coating liquid is exposed to an atmosphere having a dew point temperature Tr; and a third step of drying the layer of the coating liquid.

[2. Coating liquid]
In the manufacturing method of the coating film which concerns on one Embodiment of this invention, after preparing a coating liquid, the 1st process of coating the coating liquid on a thermoplastic resin film is performed. A coating liquid contains the organic solvent A, the organic solvent B, and a solute, and may contain arbitrary components as needed. Here, the solute is a component other than the organic solvent A and the organic solvent B contained in the coating liquid, and is dissolved in the organic solvent A and the organic solvent B in the coating liquid, and depending on drying in the third step. A component that is not removed.

[2.1. solvent〕
A coating liquid contains the organic solvent A and the organic solvent B in combination as a solvent. The combination of these organic solvent A and organic solvent B includes an organic solvent A having a relatively high solubility C _A in water at 20 ° C. and an organic solvent _B having a relatively low solubility C _B in water at 20 ° C. It is a combination.

Specifically, the solubility C _A of the organic solvent A in water at 20 ° C. and the solubility C _B of the organic solvent B in water at 20 ° C. satisfy the following formula (1).
C _A > C _B (1)

The range of the difference C _A -C _B between the solubility C _A of the organic solvent _A and the solubility C _B of the organic solvent B is preferably greater than 0, more preferably greater than 100 g / L, particularly preferably greater than 250 g / L. , Preferably 1200 g / L or less, more preferably 1100 g / L or less, particularly preferably 1000 g / L or less. The solubility difference C _A -C _B is, by greater than the lower limit of the range, can significantly suppress the occurrence of defects in coating layers. Moreover, since the solubility difference C _A -C _B is equal to or less than the upper limit of the above range, the compatibility between the organic solvent A and the organic solvent B can be easily improved, so that the uniformity of the composition of the coating layer is facilitated. Can be increased.

Specific ranges of solubility _{C A} of the organic solvent A is preferably 100 g / L or more, more preferably 200 g / L or more, particularly preferably 250 g / L or more, preferably not more than 1300 g / L, more preferably 1200g / L or less, particularly preferably 1100 g / L or less. Solubility C _A of the organic solvent A is, by the range at least as large as the lower limit of the can remarkably suppress the occurrence of defects in coating layers. Further, the solubility C _A of the organic solvent A is, by it is not more than the upper limit of the range, because it is easy enhanced compatibility with organic solvent A and organic solvent B, a readily enhance the uniformity of the composition of the coating layer be able to.

The specific range of the solubility C _B of the organic solvent B is preferably 0.1 g / L or more, more preferably 0.5 g / L or more, particularly preferably 5 g / L or more, preferably less than 100 g / L, More preferably, it is less than 50 g / L, Most preferably, it is less than 30 g / L. Solubility C _B of the organic solvent B is, by the range at least as large as the lower limit of, because it is easy enhanced compatibility with organic solvent A and organic solvent B, can be enhanced easily uniformity of the composition of the coating layer it can. Further, the solubility C _B of the organic solvent B, a by less than the upper limit of the range, can effectively suppress the occurrence of defects in coating layers.

  The measured value is usually used as the solubility value of the organic solvent. However, when the solubility value is known, the known value may be adopted. For example, when the solubility value of a certain organic solvent is described in the literature, the literature value may be adopted. For example, when the solubility value of a certain organic solvent is described in a database such as PHYSPPROP Database, the value described in the database may be adopted.

Furthermore, the combination of the organic solvent A and the organic solvent B is a combination of the organic solvent A having a relatively high evaporation rate and the organic solvent B having a relatively low evaporation rate. Specifically, the evaporation speed V _A of the organic solvent A is taken as 1 the evaporation rate of butyl _acetate, and the evaporation rate V _B of the organic solvent B which has a 1 the evaporation rate of butyl acetate, the following equation (2) Fulfill. Here, the evaporation rate V _A of the organic solvent _A is not the evaporation rate in the state of being mixed with the organic solvent B, but represents the evaporation rate measured in the state of the organic solvent A alone. Further, the evaporation rate V _B of the organic solvent _B represents not the evaporation rate in the state of being mixed with the organic solvent A but the evaporation rate measured in the state of the organic solvent B alone.
V _A −V _B > 1.5 (2)

The range of the difference V _A −V _B between the evaporation rate V _A and the evaporation rate V _B is usually greater than 1.5, preferably greater than 1.54, more preferably greater than 1.58, preferably 4 Hereinafter, it is more preferably 3.9 or less, particularly preferably 3.8 or less. When the evaporation rate difference V _A −V _B is equal to or greater than the lower limit of the range, it is possible to significantly suppress the occurrence of defects in the coating layer. Further, the evaporation speed difference V _A -V _B is, by it is not more than the upper limit of the above range, it is easy to obtain organic solvent A and organic solvent B.

The specific range of the evaporation rate V _A of the organic solvent A with the evaporation rate of butyl acetate being 1 is preferably 1.5 or more, more preferably 1.7 or more, particularly preferably 2 or more, preferably 6 Hereinafter, it is more preferably 5.9 or less, particularly preferably 5.8 or less. Evaporation rate V _A of the organic solvent A is, by the range at least as large as the lower limit of the can remarkably suppress the occurrence of defects in coating layers. The evaporation rate V _A of the organic solvent A is, by it is not more than the upper limit of the range, it is possible to suppress the disturbance of the liquid surface due to solvent volatilization, it is possible to enhance the uniformity of the thickness of the coating layer.

The specific range of the evaporation rate V _B of the organic solvent B with the evaporation rate of butyl acetate being 1 is preferably 1.8 or more, more preferably 1.9 or more, particularly preferably 2 or more, preferably 3 .8 or less, more preferably 3.7 or less, and particularly preferably 3.6 or less. Evaporation speed V _B of the organic solvent B is, by the range at least as large as the lower limit of, it is possible to perform smoothly the removal of the solvent, it is possible to enhance the productivity of the coating film. Further, the evaporation speed V _B of the organic solvent B, a by the above range is not more than the upper limit value, significantly inhibited the occurrence of defects in coating layers.

  The evaporation rate of the organic solvent is determined according to ASTM D 3539-87 Standard Test Methods for. Evaporation Rates of Volatiles Liquids by Shell Thin-Film Evaporometer. Can be measured according to

  Examples of the solvent that can be used as the organic solvent A and the organic solvent B include ketone solvents such as cyclopentanone, cyclohexanone, methyl ethyl ketone, and acetone; alcohol solvents such as ethanol, methanol, 1-propanol, and 2-propanol; cyclohexane, hexane, Hydrocarbon solvents such as methylcyclohexane and ethylcyclohexane; Acetic ester solvents such as ethyl acetate, butyl acetate, amyl acetate, propyl acetate and isopropyl acetate; Aromatic hydrocarbon solvents such as toluene, xylene, chlorobenzene and 1,2-dichlorobenzene Halogenated hydrocarbon solvents such as chloroform, dichloromethane and 1,2-dichloroethane; ether solvents such as 1,4-dioxane, cyclopentylmethyl ether, tetrahydrofuran and tetrahydropyran; And the like.

  Table 1 below shows the solubility in water at 20 ° C. and the evaporation rate when the evaporation rate of butyl acetate is 1 for typical organic solvents.

  At least one of the organic solvent A and the organic solvent B is preferably a poor solvent for the thermoplastic resin film. Thereby, the breakage of the thermoplastic resin film due to the application of the coating liquid can be suppressed. Here, the poor solvent for the thermoplastic resin film refers to a solvent that hardly dissolves the resin contained in the outermost layer on the side on which the coating solution of the thermoplastic resin film is applied. The solvent in which the resin is difficult to dissolve refers to a solvent having an insoluble content of 0.5% by weight or more when 0.5 g of the resin is dissolved in 100 g of solvent at 25 ° C. On the other hand, the good solvent for the thermoplastic resin film refers to a solvent that easily dissolves the resin contained in the outermost layer on the side on which the coating solution of the thermoplastic resin film is applied. The solvent in which the resin is easily dissolved refers to a solvent having an insoluble content of less than 0.5% by weight when 0.5 g of the resin is dissolved in 100 g of solvent at 25 ° C.

  As a combination of the organic solvent A and the organic solvent B, for example, a combination in which both the organic solvent A and the organic solvent B are poor solvents for the thermoplastic resin film is preferable. According to this combination, breakage of the thermoplastic resin film due to application of the coating liquid can be effectively suppressed.

  Moreover, as a combination of the organic solvent A and the organic solvent B, for example, one of the organic solvent A and the organic solvent B is a poor solvent for the thermoplastic resin film, and the other of the organic solvent A and the organic solvent B is A combination that is a good solvent for the thermoplastic resin film is preferred. According to this combination, the orientation of the polymer in the thermoplastic resin contained in the film is relaxed by the good solvent in the vicinity of the surface coated with the coating liquid. As a result, the degree of entanglement of the polymer molecules is increased and the toughness of the resin is increased, so that it is difficult to cause the coating layer to peel off due to breakage of the thermoplastic resin film. Therefore, the adhesive force between the thermoplastic resin film and the coating layer can be increased, and is particularly effective when the thermoplastic resin film is a stretched film.

  For example, when a resin film containing a cycloolefin polymer is used as the thermoplastic resin film, examples of the good solvent include cyclopentanone, cyclohexanone, cyclohexane, hexane, methylcyclohexane, toluene, xylene, chlorobenzene, 1, 2 -Dichlorobenzene, chloroform, dichloromethane, 1,2-dichloroethane, 1,4-dioxane, cyclopentylmethyl ether, tetrahydrofuran, and tetrahydropyran. In addition, examples of the poor solvent include methyl ethyl ketone, acetone, ethanol, methanol, 1-propanol, 2-propanol, ethyl acetate, butyl acetate, amyl acetate, propyl acetate, and isopropyl acetate.

  Specific examples of the combination of the organic solvent A and the organic solvent B include, for example, combinations shown in Table 2 below.

  The weight ratio represented by “weight of organic solvent A / weight of organic solvent B” is preferably 30/70 or more, more preferably 40/60 or more, particularly preferably 50/50 or more, preferably 90 / It is 10 or less, more preferably 85/15 or less, and particularly preferably 75/25 or less. When the weight ratio falls within the above range, the occurrence of defects in the coating layer can be remarkably suppressed.

  The ratio of the total amount of the organic solvent A and the organic solvent B to 100% by weight of the coating solution is preferably 50% by weight or more, more preferably 55% by weight or more, particularly preferably 60% by weight or more, preferably 95% by weight. % Or less, more preferably 90% by weight or less, and particularly preferably 85% by weight or less. When the ratio of the total amount of the organic solvent A and the organic solvent B is not less than the lower limit of the above range, the occurrence of defects in the coating layer can be remarkably suppressed. Moreover, since the thickness of the layer of the coated coating liquid can be thickened because it is below an upper limit, a thick coating layer can be formed easily.

[2.2. Solute)
As a solute contained in the coating liquid, any material that can be dissolved in the coating liquid can be used. In the manufacturing method of the coating film which concerns on this embodiment, a coating layer is normally formed as a layer containing reaction products, such as a solute contained in a coating liquid, or its polymer. Therefore, it is preferable to set the kind of solute of a coating layer according to the kind of coating layer provided in a coating film.

  As the solute, for example, a liquid crystal compound can be used. When a liquid crystal compound is used as the solute, a retardation layer having a predetermined retardation can be obtained as the coating layer. Among these, from the viewpoint of obtaining a coating layer having excellent mechanical strength, a polymerizable liquid crystal compound is preferable as the liquid crystal compound. Examples of the polymerizable liquid crystal compound include JP-A-11-513360, JP-A-2002-030042, JP-A-2004-204190, JP-A-2005-263789, and JP-A-2007-119415. A rod-shaped liquid crystal compound having a polymerizable group described in a document such as JP 2007-186430; a reverse wavelength dispersion polymerizable liquid crystal compound described in a document such as JP 2015-111257; JP 2003-177242 A And a side chain type liquid crystal polymer compound described in a document such as a gazette.

  Moreover, as a solute, an acrylic compound is mentioned, for example. When an acrylic compound is used as the solute, a hard coat layer having high hardness can be obtained as the coating layer. Examples of acrylic compounds include (meth) acrylic acid compounds, (meth) acrylic acid ester compounds, (meth) acrylamide compounds, (meth) acrylonitrile compounds, urethane (meth) acrylate compounds, and the like. Specific examples thereof include those described in JP2012-236922A.

  Furthermore, examples of the solute include additives such as a leveling agent, a polymerization initiator, a surfactant, an ultraviolet absorber, a light stabilizer, and a silane coupling agent.

  A solute may be used individually by 1 type, and may be used combining two or more types by arbitrary ratios.

  The concentration of the solute in the coating solution can be arbitrarily set according to the thickness of the coating layer provided on the coating film, the kind of solute, and the like. The specific concentration is preferably 10% by weight or more, more preferably 12% by weight or more, particularly preferably 15% by weight or more, preferably 30% by weight or less, more preferably 27% by weight or less, and particularly preferably 25%. % By weight or less. When the concentration of the solute is equal to or higher than the lower limit value of the range, a coating layer having a desired thickness can be easily formed. When the concentration of the solute is equal to or lower than the upper limit value of the range, the organic solvent A and the organic layer Since the ratio of the solvent B can be relatively increased, the defect suppressing action can be remarkably exhibited.

[2.3. (Optional ingredients)
The coating liquid may further contain an optional component in combination with the organic solvent A, the organic solvent B, and the solute described above. For example, any solvent other than the organic solvent A and the organic solvent B; an insoluble component that does not dissolve in the solvent; Moreover, as an insoluble component, particles, such as an organic particle and an inorganic particle, are mentioned, for example.

[3. Thermoplastic resin film]
The thermoplastic resin film is a film made of a thermoplastic resin. As the thermoplastic resin, a resin containing a thermoplastic polymer and optional components as required can be used. Examples of the polymer include cycloolefin polymer, cellulose ester, polyvinyl alcohol, polyimide, polycarbonate, polysulfone, polyethersulfone, epoxy polymer, polystyrene, acrylic polymer, methacrylic polymer, polyethylene, polypropylene, and combinations thereof. Is mentioned. Among these, from the viewpoints of transparency, low hygroscopicity, dimensional stability, lightness, and the like, cycloolefin polymers and cellulose esters are preferable, and cycloolefin polymers are more preferable.

  A cycloolefin polymer is a polymer in which the structural unit of the polymer has an alicyclic structure. The cycloolefin polymer is a polymer having an alicyclic structure in the main chain, a polymer having an alicyclic structure in the side chain, a polymer having an alicyclic structure in the main chain and the side chain, and these 2 A mixture of any of the above ratios can be obtained. Among these, from the viewpoint of mechanical strength and heat resistance, a polymer having an alicyclic structure in the main chain is preferable.

  Examples of the alicyclic structure include a saturated alicyclic hydrocarbon (cycloalkane) structure and an unsaturated alicyclic hydrocarbon (cycloalkene, cycloalkyne) structure. Among these, from the viewpoint of mechanical strength and heat resistance, a cycloalkane structure and a cycloalkene structure are preferable, and a cycloalkane structure is particularly preferable.

  The number of carbon atoms constituting the alicyclic structure is preferably 4 or more, more preferably 5 or more, particularly preferably 6 or more, preferably 30 or less, more preferably per alicyclic structure. Is 20 or less, particularly preferably 15 or less. When the number of carbon atoms constituting the alicyclic structure is within this range, the mechanical strength, heat resistance and moldability of the thermoplastic resin film are highly balanced.

  In the cycloolefin polymer, the proportion of the structural unit having an alicyclic structure is preferably 50% by weight or more, more preferably 70% by weight or more, and particularly preferably 90% by weight or more. When the proportion of the structural unit having an alicyclic structure in the cycloolefin polymer is within this range, the transparency and heat resistance of the thermoplastic resin film are improved.

  Specific examples of the cycloolefin polymer include (1) a norbornene polymer, (2) a monocyclic olefin polymer, (3) a cyclic conjugated diene polymer, (4) a vinyl alicyclic hydrocarbon polymer, And hydrogenated products thereof. Among these, norbornene polymers and hydrogenated products thereof are more preferable from the viewpoints of transparency and moldability.

  Examples of the norbornene-based polymer include a ring-opening polymer of a monomer having a norbornene structure and a hydride thereof; an addition polymer of a monomer having a norbornene structure and a hydride thereof. Examples of a ring-opening polymer of a monomer having a norbornene structure include a ring-opening homopolymer of one kind of monomer having a norbornene structure and a ring-opening of two or more kinds of monomers having a norbornene structure. Examples thereof include a copolymer and a ring-opening copolymer of a monomer having a norbornene structure and an arbitrary monomer copolymerizable therewith. Furthermore, examples of the addition polymer of a monomer having a norbornene structure include an addition homopolymer of one kind of monomer having a norbornene structure and an addition copolymer of two or more kinds of monomers having a norbornene structure. And addition copolymers of a monomer having a norbornene structure and an arbitrary monomer copolymerizable therewith. Examples of these polymers include polymers disclosed in Japanese Patent Application Laid-Open No. 2002-321302. Among these, a hydride of a ring-opening polymer of a monomer having a norbornene structure is particularly suitable from the viewpoints of transparency, moldability, heat resistance, low hygroscopicity, dimensional stability and lightness.

  Specific examples of the norbornene-based polymer include “ZEONOR” manufactured by ZEON Corporation; “ARTON” manufactured by JSR Corporation; “TOPAS” manufactured by TOPAS ADVANCED POLYMERS.

  The weight average molecular weight (Mw) of the polymer contained in the thermoplastic resin is preferably 10,000 or more, more preferably 25,000 or more, preferably 100,000 or less, more preferably 80,000 or less, particularly Preferably it is 50,000 or less. When the weight average molecular weight of the polymer is in such a range, the mechanical strength and molding processability of the thermoplastic resin film are highly balanced.

  The molecular weight distribution (weight average molecular weight (Mw) / number average molecular weight (Mn)) of the polymer contained in the thermoplastic resin is preferably 1 or more, more preferably 1.2 or more, preferably 10 or less, more preferably. Is 4 or less, particularly preferably 3.5 or less.

  Here, the weight average molecular weight and number average molecular weight of the polymer are determined by gel permeation chromatography using cyclohexane as a solvent (however, if the sample does not dissolve in cyclohexane, toluene may be used). It can be measured as a value in terms of polyisoprene (when the solvent is toluene, in terms of polystyrene).

  The amount of the polymer in the thermoplastic resin is preferably 70% by weight to 100% by weight, more preferably 80% by weight to 100% by weight.

  The glass transition temperature of the thermoplastic resin is preferably 80 ° C. or higher, more preferably 100 ° C. or higher, and preferably 250 ° C. or lower. A thermoplastic resin having a glass transition temperature in such a range is excellent in durability since the deformation and stress generation during use at high temperatures are suppressed.

  The thermoplastic resin has a resin component (that is, oligomer component) having a molecular weight of 2,000 or less, preferably 5% by weight or less, more preferably 3% by weight or less, and still more preferably 2% by weight or less. When the content of the oligomer component is within the above range, generation of fine convex portions on the surface of the thermoplastic resin film is reduced, thickness variation is reduced, and surface accuracy is improved. The amount of the oligomer component can be reduced by appropriately setting, for example, selection of a polymerization catalyst and a hydrogenation catalyst; reaction conditions such as polymerization and hydrogenation; and temperature conditions in a step of pelletizing a resin as a molding material. Yes. The amount of the oligomer component can be measured by the above-mentioned gel permeation chromatography.

  As the thermoplastic resin film, a single-layer film having only one layer may be used, or a multilayer film having two or more layers may be used. When the thermoplastic resin film has two or more layers, it is preferable that the outermost layer on the side to which the coating liquid is applied contains a cycloolefin polymer. In general, the surface of a layer made of a resin containing a cycloolefin polymer tends to have poor adhesion to other layers. In contrast, when a coating solution containing a good solvent is used as one of the organic solvent A and the organic solvent B, the adhesion between the outermost layer made of a resin containing a cycloolefin polymer and the coating layer can be improved. A coated film having excellent mechanical strength can be obtained.

  As the thermoplastic resin film, a single film may be used, but a long film is preferably used. “Long film” means a film having a length of 5 times or more with respect to the width, preferably 10 times or more, and specifically wound in a roll shape. A film having a length that can be stored or transported. Although the upper limit of the ratio of the length with respect to the width of a film is not specifically limited, For example, it can be 100,000 times or less. By using a long thermoplastic resin film, roll-to-roll production is possible, and the productivity of the coating film can be increased.

  The thickness of the thermoplastic resin film may be arbitrarily set according to the application of the coating film, preferably 1 μm or more, more preferably 5 μm or more, particularly preferably 10 μm or more, preferably 1000 μm or less, more preferably Is 300 μm or less, particularly preferably 100 μm or less. A thermoplastic resin film having such a thickness has good productivity, is thin, and can be reduced in weight.

  The thermoplastic resin film can be produced, for example, by molding a thermoplastic resin by an arbitrary film forming method. Examples of the film forming method include a cast forming method, an extrusion forming method, and an inflation forming method. Especially, the melt extrusion method which does not use a solvent can reduce the quantity of a volatile component efficiently, and is preferable from a viewpoint of a global environment viewpoint, a viewpoint of work environment, and a viewpoint of manufacturing efficiency. Examples of the melt extrusion method include an inflation method using a die, and a method using a T die is preferable in terms of excellent productivity and thickness accuracy.

  Moreover, the manufacturing method of a thermoplastic resin film may include the process of extending | stretching the obtained film. Thereby, a stretched film is obtained as a thermoplastic resin film. In such a stretched film, the polymer molecules contained in the film are usually oriented. Thus, the stretched film can have optical properties such as retardation. In addition, the stretched film may have an alignment regulating force that orients the liquid crystal compound applied to the film surface.

  As the stretching process, for example, a uniaxial stretching process in which stretching is performed only in one direction may be performed, or a biaxial stretching process in which stretching is performed in two different directions may be performed. Further, in the biaxial stretching treatment, simultaneous biaxial stretching treatment in which stretching is performed simultaneously in two directions may be performed, and sequential biaxial stretching processing is performed in which stretching is performed in one direction and then stretching in another direction. Also good. Furthermore, the stretching process includes any of a longitudinal stretching process for stretching in the film longitudinal direction, a transverse stretching process for stretching in the film width direction, and an oblique stretching process for stretching in an oblique direction that is neither parallel nor perpendicular to the film width direction. You may carry out and may carry out combining these. Examples of the stretching method include a roll method, a float method, and a tenter method.

[4. First step]
In the manufacturing method of the multilayer film which concerns on one Embodiment of this invention, after preparing a coating liquid and a thermoplastic resin film, the 1st process of coating a coating liquid on a thermoplastic resin film is performed. By applying the coating liquid, the layer of the coating liquid is formed on the thermoplastic resin film.

In the first step, the liquid temperature T of the coating liquid to be applied satisfies the following formula (4).
20 ° C>T> 10 ° C (4)

  More specifically, the liquid temperature T of the coating liquid is usually higher than 10 ° C, preferably higher than 11 ° C, particularly preferably higher than 12 ° C, and usually lower than 20 ° C, preferably lower than 19.5 ° C. Especially preferably, it is less than 19 degreeC. When the liquid temperature T of the coating liquid is in the above temperature range, the occurrence of defects in the coating layer can be suppressed.

  Further, the atmosphere in the first step is preferably adjusted so that the dew point temperature of the atmosphere in the first step is the same as the dew point temperature Tr of the atmosphere in the second step. Thereby, generation | occurrence | production of the defect in a coating layer can be suppressed especially effectively. Usually, the first step and the second step are performed in the same room. Therefore, by adjusting the atmosphere in the second step so that the dew point temperature Tr is obtained, the dew point temperature of the atmosphere in the first step is also the temperature Tr. Adjusted to

  There are no restrictions on the coating method, for example, spray coating method, bar coating method, roll coating method, die coating method, inkjet coating method, screen coating method, dip coating method, slot die coating method, letterpress printing method, intaglio printing method, gravure The printing method etc. are mentioned.

[5. Second step]
After the first step, a second step is performed in which the layer of the coating liquid formed on the thermoplastic resin film is exposed to an atmosphere having a dew point temperature Tr. The dew point temperature Tr of the atmosphere to which the coating liquid layer is exposed in the second step satisfies the formula (3).
8 ° C>T-Tr> 0 ° C (3)

  More specifically, the difference T-Tr between the liquid temperature T of the coating liquid applied in the first step and the dew point temperature Tr of the atmosphere in the second step is preferably greater than 0 ° C., and preferably 8 It is less than ° C, more preferably less than 7.5 ° C, particularly preferably less than 7 ° C. When the temperature difference T-Tr is in the temperature range, the occurrence of defects in the coating layer can be suppressed.

  The second step can be performed in at least a part of the period after the first step and before the third step. Especially, it is preferable to perform a 2nd process in the at least one part period continuous from a 1st process. Furthermore, it is particularly preferable that the second step is performed in the entire period after the first step and before the third step. Therefore, for example, when manufacturing a coating film while transporting a long thermoplastic resin film, a drying apparatus for drying a layer of the coating liquid after the coating apparatus for performing the first step It is preferable to adjust the atmosphere of the film transport path so that the dew point temperature Tr is obtained in the previous section. Thereby, generation | occurrence | production of the defect in a coating layer can be suppressed especially effectively.

  The time for which the layer of the coating liquid formed on the thermoplastic resin film is exposed to the atmosphere at the dew point temperature Tr is arbitrary as long as the occurrence of defects in the coating layer can be suppressed, but is preferably 3 seconds or more, more preferably Is 5 seconds or longer, particularly preferably 7 seconds or longer, preferably 30 seconds or shorter, more preferably 27 seconds or shorter, particularly preferably 25 seconds or shorter. Since the time for exposing the coating liquid layer to the atmosphere with the dew point temperature Tr is equal to or higher than the lower limit of the above range, uniform condensation can be stably generated, so that the occurrence of defects in the coating layer is remarkably suppressed. it can. Moreover, by being below an upper limit, generation | occurrence | production of excessive dew condensation can be suppressed or productivity of a coating film can be improved.

[6. Third step]
After the second step, a third step of drying the coating liquid layer formed on the thermoplastic resin film is performed. By the third step, the organic solvent A, the organic solvent B, and any volatile components are removed from the coating liquid contained in the coating liquid layer, and a coating layer is formed. Thereby, a coating film provided with a thermoplastic resin film and a coating layer is obtained.

  In the third step, the coating liquid layer is usually dried by heating. Heating can be achieved, for example, by exposing the coating liquid layer to a high temperature dry atmosphere. The temperature of the drying atmosphere is usually higher than the liquid temperature T of the coating liquid in the first step. The specific temperature of the drying atmosphere is arbitrary as long as the solvent can be removed, but is preferably 70 ° C. or higher, more preferably 75 ° C. or higher, particularly preferably 80 ° C. or higher, preferably 110 ° C. or lower, More preferably, it is 105 degrees C or less, Most preferably, it is 100 degrees C or less.

  In addition, when the coating liquid layer contains a liquid crystal compound and the thermoplastic resin film has an alignment regulating force, the liquid crystal compound is aligned by heating the coating liquid layer in the third step. Can do.

[7. Any process]
The manufacturing method of the coating film which concerns on one Embodiment of this invention may contain the arbitrary process in addition to the process mentioned above.
The manufacturing method of a coating film may include the process of hardening a coating layer, for example. Examples thereof will be described below. The coating layer obtained by the third step described above usually contains a solute. When this solute can be polymerized by active energy rays such as ultraviolet rays, a step of irradiating the coating layer with active energy rays may be performed after the third step. By irradiation with active energy rays, the solute is polymerized and the hardness of the coating layer can be increased. Thereby, a coating film with high mechanical strength can be obtained.

  Moreover, the manufacturing method of a coating film is, for example, a step of applying a surface treatment to a coating film, a step of stretching a coating film, a protective film on the coating surface of the coating film or the opposite surface (anti-coating surface) The process of pasting, the process of slitting a coating film, the process of winding up a coating film, etc. may be included.

[8. Coating film]
By the manufacturing method mentioned above, a coating film provided with a thermoplastic resin film and a coating layer can be obtained. In the manufacturing method mentioned above, generation | occurrence | production of the defect in a coating layer can be suppressed. Therefore, there are few defects in the coating layer of the obtained coating film.
According to this inventor, it is guessed that the mechanism which can suppress generation | occurrence | production of the defect in a coating layer with the manufacturing method mentioned above is as follows. However, the technical scope of the present invention is not limited by the mechanism described below.

In the manufacturing method of the coating film described above, the layer of the coating liquid formed on the thermoplastic resin film is usually immediately after the coating liquid is applied to the thermoplastic resin film in the first step. The liquid temperature T before coating is maintained. Thereafter, as time elapses, volatile components such as a solvent are volatilized from the coating liquid layer. Here, the coating solution contains a combination of an organic solvent A having a relatively fast evaporation rate V _A and an organic solvent _B having a relatively slow evaporation rate V _B as shown in Formula (2). Therefore, when the solvent is volatilized, a large amount of the organic solvent A and a small amount of the organic solvent B are volatilized from the coating liquid layer. And since vaporization heat is lost by such volatilization, the temperature of the layer of a coating liquid falls.

  If the liquid temperature T of the coating liquid in the first process is high or the dew point temperature Tr of the atmosphere in the second process is significantly lower than the liquid temperature T of the coating liquid, the coating liquid is applied. After that, it takes a long time for the temperature of the coating liquid layer to reach the dew point temperature Tr. Then, when the temperature of the coating liquid layer reaches the dew point temperature Tr, a large amount of the organic solvent A is lost from the coating liquid layer, and the organic solvent B is mostly on the surface of the coating liquid layer. Occupy. Since the organic solvent B has a lower solubility in water than the organic solvent A, the affinity for water is poor. Therefore, when dew condensation occurs on the surface where the organic solvent B occupies most of the surface, the liquefied water tends to aggregate, and therefore dew condensation is likely to occur in a large size at a biased position. If the dew condensation is large, a large depression is generated on the surface of the coating layer in the portion where the dew condensation occurs, and a large protrusion is generated around the surface, which may cause a defect.

  On the other hand, in the manufacturing method described above, the liquid temperature T of the coating liquid is a low temperature close to the dew point temperature Tr of the atmosphere in the second step, as shown by the formulas (3) and (4). Therefore, the time required for the temperature of the layer of the coating liquid to reach the dew point temperature Tr after applying the coating liquid is short. Then, when the temperature of the coating liquid layer reaches the dew point temperature Tr, only a small amount of the organic solvent A is lost from the coating liquid layer. Therefore, the coating liquid layer can contain a sufficiently large amount of the organic solvent A.

When the coating solution layer contains a sufficiently large amount of the organic solvent A, the organic solvent A and the organic solvent B are uniformly mixed and distributed in the in-plane direction on the surface of the coating solution layer. it can. Here, as shown by the formula (1), since the solubility C _A of the organic solvent A in water is larger than the solubility C _{B of the} organic solvent B in water, the affinity of the organic solvent A for water is It is higher than the affinity of B for water. Therefore, dew condensation hardly occurs in the portion where the molecule of the organic solvent B exists, and tends to occur in the portion where the molecule of the organic solvent A exists. Therefore, according to the uniform distribution of the organic solvent A, condensation of a small size is uniformly generated in the in-plane direction on the surface of the coating liquid layer.

  When the size of the dew condensation is small, the depth of the depression or protrusion on the surface of the coating layer becomes small, so that the change in optical characteristics due to the depression or protrusion can be reduced. In addition, if the generation of condensation is uniform in the in-plane direction, the generation of dents or protrusions on the surface of the coating layer is also uniform in the in-plane direction. The change in the optical characteristics due to is not noticeable. In general, a defect is generated when there is a difference in optical characteristics between the defect portion and the periphery thereof, and therefore, a defect is hardly generated in a portion where the difference in optical characteristics with the periphery is small. Therefore, it is possible to make it difficult for defects to occur in the coating layer by causing condensation of a small size uniformly in the in-plane direction as described above.

Further, if the solubility C _A in water of the organic solvent A is particularly large, a portion of the liquefied water, without forming condensation is dissolved in an organic solvent A. Therefore, the size of the condensation formed can be further reduced. Therefore, the occurrence of defects can be suppressed particularly effectively by using an organic solvent A having a high solubility C _{A in} water.

  The thickness of the coating layer of a coating film can be arbitrarily set according to the use of a coating film. Specifically, when showing the range, the thickness of the coating layer is preferably 0.5 μm or more, more preferably 1 μm or more, particularly preferably 1.5 μm or more, preferably 20 μm or less, more preferably 15 μm or less, particularly Preferably it is 10 micrometers or less.

  Although there is no restriction | limiting in particular in the use of a coating film, From a viewpoint of utilizing effectively the effect that a defect can be suppressed, it uses as optical films, such as a phase difference film, a polarizing plate protective film, an optical compensation film, and an optical protective film. Is preferred.

  From the viewpoint of use as an optical film, the coating film preferably has high transparency. Specifically, the total light transmittance of the coated film is preferably 80% or more, more preferably 85% or more, and particularly preferably 90% or more. The total light transmittance of the coated film can be measured in the wavelength range of 380 nm to 780 nm using an ultraviolet / visible spectrometer.

  Moreover, it is preferable that the haze of a coating film is small from a viewpoint used as an optical film. Specifically, the haze of the coated film is preferably 1% or less, more preferably 0.7% or less, and particularly preferably 0.5% or less. The haze of the coated film can be measured using a haze meter (for example, “Haze Guard II” manufactured by Toyo Seiki Co., Ltd.) in accordance with JIS K7136.

  Hereinafter, the present invention will be specifically described with reference to examples. However, the present invention is not limited to the following examples, and can be implemented with any modifications without departing from the scope of the claims of the present invention and the equivalents thereof.

  In the following description, “%” and “part” representing amounts are based on weight unless otherwise specified. The following operations were performed in a normal temperature and normal pressure atmosphere unless otherwise specified.

[Evaluation method]
(Measurement method of solvent evaporation rate)
The evaporation rate of the solvent was measured using ASTM D 3539-87 Standard Test Methods for. Evaporation Rates of Volatiles Liquids by Shell Thin-Film Evaporometer. Measured according to By dividing the measured evaporation rate by the evaporation rate of butyl acetate, it was converted to the evaporation rate of the solvent with the evaporation rate of butyl acetate as 1.

(Defect evaluation method)
The coated film was hung on a suspension base, and the surface of the coated film on the coating layer side was illuminated with a high-intensity discharge lamp ((HID lamp; “Polarion Light” manufactured by Polarion)) and observed. The number of streak-like defects was counted in a range of 1.3 m in width and 2 m in length including the central portion in the width direction of the film, where the flaw-like defects are circular defects arranged continuously or intermittently. Represents a linear defect of 5 cm or more in length.

[Example 1]
(1-1. Preparation of coating solution)
A mixed solvent containing acetone as the organic solvent A and propyl acetate as the organic solvent B (weight ratio: acetone / propyl acetate = 70/30) was prepared. Acetone and propyl acetate are both poor solvents for the resin contained in the thermoplastic resin film.
62.0 parts of this mixed solvent, 50.0 parts of urethane acrylate oligomer (“UV-7640B” manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) having 6 or more acryloyl groups in one molecule, silica particles (manufactured by CIK Nanotech Co., Ltd., several 10.0 parts of an average particle diameter of 30 nm), 0.2 parts of a leveling agent (“GRANDIC PC11-6204L” manufactured by DIC) and 3.0 parts of a polymerization initiator (“Irgacure 379” manufactured by BASF) were mixed. A coating liquid as a hard coat composition was produced.

(1-2. Preparation of thermoplastic resin film)
As a thermoplastic resin film, a long transversely stretched film made of a thermoplastic resin containing a cycloolefin polymer (“ZEONOR film” manufactured by Nippon Zeon Co., Ltd., glass transition temperature (Tg) of thermoplastic resin: 126 ° C., thickness: 20 μm, wavelength: In-plane retardation at 590 nm (130 nm) was prepared.

(1-3. Production of coated film)
A die coater consisting of a coating liquid stock tank, a gear pump, a liquid feeding tube and a coating die was installed in the coating room. As the coating liquid stock tank and the coating die, those capable of adjusting the temperature by passing water were used. Moreover, the liquid supply tube was installed so that temperature adjustment was possible by water flow in a water flow jacket by covering with a water flow jacket. The stock tank, the coating die, and the water flow jacket were adjusted to flow 16 ° C. water so that the liquid temperature T of the coating solution was maintained at 16 ° C.

  Moreover, the dew point temperature Tr in the coating chamber was adjusted to 11 ° C. by adjusting the temperature and relative humidity in the coating chamber.

  The following steps were performed while continuously conveying the thermoplastic resin film in the longitudinal direction.

  A thermoplastic resin film was supplied to the coating room. And the coating liquid with the liquid temperature T = 16 degreeC as a hard-coat composition was apply | coated on the thermoplastic resin film using the die-coater, and the layer of the coating liquid was formed (1st process).

  Thereafter, the thermoplastic resin film was conveyed toward an oven provided immediately downstream of the coating chamber. At this time, the layer of the coating liquid was exposed to an atmosphere having a dew point temperature of Tr = 11 ° C. by running in the coating chamber for 20 seconds after being applied by the die coater and entering the oven (second temperature). Process).

  Thereafter, the coating liquid layer was dried for about 2 minutes in an oven at 100 ° C. Thereby, the solvent was removed from the layer of the coating liquid, and the coating layer was formed (third step).

Thereafter, the coating layer was irradiated with ultraviolet rays using an ultraviolet irradiation device (high pressure mercury lamp) under the conditions of an illuminance of 250 mW / cm ² and an integrated light quantity of 100 mJ / cm ² . Thereby, the urethane acrylate oligomer contained in the coating layer was polymerized, and the coating layer was cured. The thickness of the coating layer after curing was 3.0 μm.
As described above, a coating film including a thermoplastic resin film and a coating layer as a hard coat layer provided on the thermoplastic resin film was obtained. The defect of the obtained coating film was evaluated by the evaluation method described above.

[Example 2]
The type of organic solvent A was changed from acetone to methyl ethyl ketone. Methyl ethyl ketone is a poor solvent for the resin contained in the thermoplastic resin film.
Except for the above items, the coating film was produced and evaluated in the same manner as in Example 1.

[Example 3]
The type of organic solvent B was changed from propyl acetate to methylcyclohexane. Methylcyclohexane is a good solvent for the resin contained in the thermoplastic resin film.
Except for the above items, the coating film was produced and evaluated in the same manner as in Example 1.

[Example 4]
The type of organic solvent B was changed from propyl acetate to toluene. Toluene is a good solvent for the resin contained in the thermoplastic resin film.
Except for the above items, the coating film was produced and evaluated in the same manner as in Example 1.

[Example 5]
The type of organic solvent A was changed from acetone to ethyl acetate. Ethyl acetate is a poor solvent for the resin contained in the thermoplastic resin film. Moreover, the kind of the organic solvent B was changed from propyl acetate to toluene. Furthermore, the liquid temperature T of the coating liquid applied on the thermoplastic resin film was changed to 18 ° C.
Except for the above items, the coating film was produced and evaluated in the same manner as in Example 1.

[Example 6]
(6-1. Preparation of coating solution)
A mixed solvent containing methyl ethyl ketone as the organic solvent A and toluene as the organic solvent B (weight ratio: methyl ethyl ketone / toluene = 60/40) was prepared.
75.00 parts of this mixed solvent, 24.15 parts of a polymerizable liquid crystal compound represented by the following formula (B3) ("LC242" manufactured by BASF), surfactant ("Factent FTX-209F" manufactured by Neos) 0 .12 parts and 0.73 part of a polymerization initiator (“IRGACURE379” manufactured by BASF) were mixed to prepare a coating liquid as a liquid crystal composition.

(6-2. Preparation of thermoplastic resin film)
As the thermoplastic resin film, the same long transversely stretched film as used in Example 1 was prepared.

(6-3. Production of coated film)
A die coater having the same structure as in Example 1 was installed in the coating room. The stock tank of the die coater, the coating die, and the water passage jacket were adjusted to flow 16 ° C. water so that the coating solution was maintained at 16 ° C. Moreover, the dew point temperature Tr in the coating chamber was adjusted to 11 ° C. by adjusting the temperature and relative humidity in the coating chamber.

  The following steps were performed while continuously transporting the thermoplastic resin film in the longitudinal direction.

  A thermoplastic resin film was supplied to the coating room. And the coating liquid as a liquid-crystal composition was apply | coated on the thermoplastic resin film using the die-coater, and the layer of the coating liquid was formed (1st process).

  Thereafter, the thermoplastic resin film was conveyed toward an oven provided immediately downstream of the coating chamber. At this time, the layer of the coating solution was exposed to an atmosphere having a dew point temperature of Tr = 11 ° C. for 20 seconds after being applied by the die coater until entering the oven (second step).

  Thereafter, the coating liquid layer was dried for about 2 minutes in a 90 ° C. oven, and the solvent was removed from the coating liquid layer. Further, by heating in the oven, the polymerizable liquid crystal compound contained in the coating liquid layer was aligned in parallel with the stretching direction of the thermoplastic resin film in accordance with the alignment regulating force of the thermoplastic resin film. Thereby, the coating layer was formed (third process).

Thereafter, the coating layer was irradiated with ultraviolet rays using an ultraviolet irradiation device (high pressure mercury lamp) under the conditions of an illuminance of 250 mW / cm ² and an integrated light quantity of 100 mJ / cm ² . Thereby, the polymerizable liquid crystal compound contained in the coating layer was polymerized, and the coating layer was cured. The thickness of the coating layer after curing was 1.2 μm.
As described above, a coating film including a thermoplastic resin film and a coating layer as a liquid crystal cured layer provided on the thermoplastic resin film was obtained. The defect of the obtained coating film was evaluated by the evaluation method described above.

[Example 7]
The type of organic solvent B was changed from propyl acetate to methylcyclohexane. Moreover, the liquid temperature T of the coating liquid applied on a thermoplastic resin film was changed to 18 degreeC.
Except for the above items, the coating film was produced and evaluated in the same manner as in Example 1.

[Example 8]
The type of organic solvent B was changed from propyl acetate to methylcyclohexane. Moreover, the liquid temperature T of the coating liquid applied on a thermoplastic resin film was changed to 13 degreeC.
Except for the above items, the coating film was produced and evaluated in the same manner as in Example 1.

[Example 9]
The type of organic solvent B was changed from propyl acetate to methylcyclohexane. Further, the dew point temperature Tr in the coating chamber was changed to 14 ° C. by adjusting the temperature in the coating chamber.
Except for the above items, the coating film was produced and evaluated in the same manner as in Example 1.

[Comparative Example 1]
The liquid temperature T of the coating liquid applied on the thermoplastic resin film was changed to 22 ° C. Further, the dew point temperature Tr in the coating chamber was changed to 9 ° C. by adjusting the temperature in the coating chamber.
Except for the above items, the coating film was produced and evaluated in the same manner as in Example 1.

[Comparative Example 2]
The type of organic solvent B was changed from propyl acetate to methylcyclohexane. Moreover, the liquid temperature T of the coating liquid applied on a thermoplastic resin film was changed to 22 degreeC. Furthermore, the dew point temperature Tr in the coating chamber was changed to 13 ° C. by adjusting the temperature in the coating chamber.
Except for the above items, the coating film was produced and evaluated in the same manner as in Example 1.

[Comparative Example 3]
The type of organic solvent A was changed from acetone to ethyl acetate. Moreover, the kind of the organic solvent B was changed from propyl acetate to methylcyclohexane. Furthermore, the liquid temperature T of the coating liquid applied on the thermoplastic resin film was changed to 19 ° C.
Except for the above items, the coating film was produced and evaluated in the same manner as in Example 1.

[result]
The results of Examples and Comparative Examples described above are shown in Table 3 and Table 4 below. In the following table, the meanings of the abbreviations are as follows.
COP: cycloolefin polymer.
UA: urethane acrylate.
LQ: polymerizable liquid crystal compound.
MEK: methyl ethyl ketone.
V _A : The evaporation rate of the organic solvent A with the evaporation rate of butyl acetate as 1.
V _B : The evaporation rate of the organic solvent B with the evaporation rate of butyl acetate as 1.
T: Liquid temperature of the coating liquid.
Tr: Dew point temperature of the coating room atmosphere.
C _A : Solubility of organic solvent A in water at 20 ° C.
C _B : Solubility of organic solvent B in water at 20 ° C.
S _A : The weight ratio of the organic solvent A to the total 100% of the organic solvent A and the organic solvent B.
S _B : Weight ratio of organic solvent B to 100% of organic solvent A and organic solvent B in total.

[Consideration]
In Comparative Examples 1 to 3, the number of streak-like defects was 10 or more per 2.6 m ² area of the coated film. On the other hand, in Examples 1 to 9, the number of streak defects was 4 or less per 2.6 m ² of the coated film area, and a significant improvement was observed. From the above results, it was confirmed that the coated film can be produced while suppressing the occurrence of defects by the production method of the present invention.

Claims (5)

A first step of coating a thermoplastic resin film with a coating liquid having a liquid temperature T containing an organic solvent A, an organic solvent B and a solute, and forming a layer of the coating liquid;
A second step in which the coating liquid layer is exposed to an atmosphere having a dew point temperature Tr;
A third step of drying the coating liquid layer, in this order, a method for producing a coating film,
Solubility C _{A of} the organic solvent A in water at 20 ° C.,
Solubility C _{B of} the organic solvent B in water at 20 ° C.,
The evaporation rate V _{A of} the organic solvent A with the evaporation rate of butyl acetate being 1,
The evaporation rate V _{B of} the organic solvent B with an evaporation rate of butyl acetate as 1,
The liquid temperature T, and
The dew point temperature Tr is expressed by the following formulas (1) to (4):
C _A > C _B (1)
V _A −V _B > 1.5 (2)
8 ° C>T-Tr> 0 ° C (3)
20 ° C>T> 10 ° C (4)
The manufacturing method of the coating film which satisfy | fills. The solubility _{C A} is, it is 100 g / L or more,
The solubility _{C B} is less than 100 g / L, the manufacturing method of a coating film according to claim 1, wherein.   The method for producing a coated film according to claim 1 or 2, wherein both the organic solvent A and the organic solvent B are poor solvents for the thermoplastic resin film. One of the organic solvent A and the organic solvent B is a poor solvent for the thermoplastic resin film,
The manufacturing method of the coating film of Claim 1 or 2 whose other of the said organic solvent A and the said organic solvent B is a good solvent with respect to the said thermoplastic resin film.   The manufacturing method of the coating film as described in any one of Claims 1-4 with which the said thermoplastic resin film contains a cycloolefin polymer.