JP5178664B2 - Cellulose ester film and method for producing the same - Google Patents

Description

  The present invention relates to a photographic photosensitive material formed by a solution casting method and a film used for optical applications, and relates to a cellulose ester film having good surface flatness and slipperiness and a method for producing the same.

  Cellulose ester (including cellulose acetate, cellulose acetate butyrate, and cellulose acetate propionate) films have good transparency, high mechanical strength, and small dimensional variation with humidity and heat (dimensional stability) For example, cellulose acetate films, especially cellulose triacetate (triacetylcellulose, TAC) films are widely used. . Such a cellulose ester film is produced by a solution casting method. This solution casting method involves casting a polymer solution dissolved in an organic solvent from a casting die onto a casting support. A film is formed on a support.

  By the way, since a support for photographic photosensitive materials and optical materials is required to have flatness and slipperiness, various techniques for improving the flatness and slipperiness of films that can be used for the support have been proposed. ing. For example, Japanese Patent Laid-Open No. 6-123937 discloses a squeeze value before treatment in a roll shape at a drying temperature of 50 ° C. or more and a glass transition temperature or less in the formation of a polyester film of 10 g or more and 400 g or less. A silver halide photographic material having good properties has been proposed.

  JP-A-9-225953 discloses a cationic polymer or anion in the uppermost layer or in the vicinity of the uppermost layer of a coating film provided upstream of the flatness improving unit for the purpose of improving the flatness in the drying process of the TAC film. There has been proposed a method for producing a cellulose acetate film characterized in that a functional polymer is applied or a matting agent is applied upstream of the flatness improving portion.

  JP-A-8-207210 has a core portion (substitution degree 2.7 or less) having a different degree of acetylation (substitution degree) and a surface layer (substitution degree 2.8 or more). A cellulose acetate laminated film with improved transparency, dimensional stability, and heat and humidity resistance has been proposed.

  However, as proposed in Japanese Patent Application Laid-Open No. 9-225953, in the cellulose ester film used for the support of the photographic photosensitive material, in order to ensure the slipperiness, the coating film applied on both surfaces of the film. In general, a cationic polymer or an anionic polymer is applied to the uppermost layer or in the vicinity of the uppermost layer, but it is not fully satisfactory.

  The cellulose ester film used for the polarizing plate protective film has a matting agent added to the dope in order to prevent tacking. The addition amount of this matting agent is preferably larger in order to prevent tacking, but if the addition amount of the matting agent is increased, the haze increases and the light transmittance decreases and the photographic properties deteriorate.

  The present invention solves the above problems, and by adding a small amount of matting agent, while ensuring good flatness and anti-tacking properties, it is possible to sufficiently ensure transparency, and a cellulose ester film thereof An object is to provide a manufacturing method.

The cellulose ester film according to the present invention is a cellulose ester film having a multilayer structure having at least a base layer and a surface layer, each layer is formed of the same cellulose ester, and a matting agent is added to the surface layer only in an amount of 5 to 500 mg / m ^2. is, and with the thickness of the surface layer is 0.0002Mm～0.02Mm, the total thickness is 0.02Mm～0.5Mm, the center line average roughness of the surface layer surface 0.1 to 1 m, the matting agent And forming a surface layer by casting a composition containing inorganic particles by a co-casting method, or forming a surface layer by casting a composition containing inorganic particles by a sequential casting method. It is characterized by being for a photographic photosensitive material or an optical material.

  Moreover, the center line average roughness of the surface layer surface is preferably 0.01 μm to 5 μm, and the center line average roughness is more preferably 0.1 μm to 1 μm.

  The method for producing a cellulose ester film according to the present invention is characterized by using inorganic particles as a matting agent and casting a composition containing inorganic particles by a co-casting method to form a surface layer.

  Further, the method for producing a cellulose ester film according to the present invention is characterized in that inorganic particles are used as a matting agent, and a composition containing inorganic particles is cast by a sequential casting method to form a surface layer.

  According to the present invention, by laminating a surface layer to which a small amount of a matting agent is added on the surface of a cellulose ester film having a multilayer structure, tackiness can be prevented without decreasing the overall transmittance of the cellulose ester film, and a flat surface. A cellulose ester film having good properties can be obtained.

  The cellulose ester film of the present invention has a multilayer structure having at least a base layer and a surface layer, and a matting agent is added only to the surface layer. This surface layer may be laminated only on one side of the base layer, or may be laminated on both sides of the base layer. That is, as shown in FIG. 1, a three-layer mode comprising a base layer 1 and a surface layer 2 laminated on both sides thereof, and as shown in FIG. 2, a base layer 1 and a surface layer 2 laminated on one surface thereof, There are two-layer embodiments. The surface layer is laminated at a position located on the surface, and another layer can be laminated between the base layer and the surface layer.

  In such a cellulose ester film, a matting agent is added only to the surface layer, and no matting agent is added to the base layer. That is, by adding a matting agent only to the surface layer, it ensures the flatness and anti-tacking property of the surface of the cellulose ester film, and in the base layer (including the intermediate layer when other layers are laminated in the middle). By not adding a matting agent, the transparency of the entire cellulose ester film is secured.

Examples of the matting agent that can be added to the surface layer of the cellulose ester film of the present invention include SiO ₂ , TiO ₂ , BaSO ₄ , CaCO ₃ , talc, and kaolin. In addition, examples of inorganic compounds include fine powders of inorganic substances such as barium sulfate, manganese colloid, titanium dioxide, strontium barium sulfate, and silicon dioxide. Further, for example, synthetic silica obtained by wet method or gelation of silicic acid, etc. And titanium dioxide (rutile type or anatase type) produced by silicon dioxide or titanium slug and sulfuric acid. It can also be obtained by pulverizing from an inorganic substance having a relatively large particle size, for example, 20 μm or more, followed by classification (vibration filtration, wind classification, etc.). A preferred inorganic compound matting agent includes conductive fine particles. Specifically, at least one crystalline metal oxide selected from ZnO, TiO ₃ , SnO ₂ , Al ₂ O ₃ , In ₂ O ₃ , SiO ₂ , MgO, BaO, and MoO ₃ , or these There are fine composite oxide particles.

  Further, examples of the matting agent made of a polymer compound include polytetrafluoroethylene, cellulose acetate, polystyrene, polymethyl methacrylate, polypropyl methacrylate, polymethyl acrylate, polyethylene carbonate, starch, and the like. . Further, a polymer compound synthesized by a suspension polymerization method, a polymer compound made spherical by a spray drying method or a dispersion method, or an inorganic compound can be used. Moreover, the polymer compound which is a polymer of one kind or two or more kinds of monomer compounds described below may be formed into particles by various means.

  For example, acrylic acid esters, methacrylic acid esters, vinyl esters, styrenes, and olefins are preferably used. Moreover, you may use the particle | grains which have a fluorine atom or a silicon atom as described in Unexamined-Japanese-Patent No. 62-14647, 62-17744, 62-177743. Among these, particle compositions preferably used are polystyrene, polymethyl (meth) acrylate, polyethyl acrylate, poly (methyl methacrylate / methacrylic acid = 95/5) (molar ratio), poly (styrene / styrene sulfonic acid = 95/5). ) (Molar ratio), polyacrylonitrile, poly (methyl methacrylate / ethyl acrylate / methacrylic acid = 50/40/10), silica and the like.

As the matting agent, various inorganic compounds and polymer compounds can be used as described above. However, an inorganic compound is preferable for the dispersant using methylene chloride, and silica (SiO ₂ ) is particularly inexpensive and easily available. preferable.

The addition amount of the matting agent is preferably ^{5~500mg / m 2, 10~100mg / m} 2 is more preferable. When the addition amount of the matting agent is less than 5 mg / m ² , it becomes difficult to ensure the slipperiness and tackiness prevention property of the cellulose ester film surface, and when it exceeds 500 mg / m ² , the transparency is deteriorated.

The thickness of the surface layer of the cellulose ester film is preferably from 0.0002 mm to 0.02 mm, more preferably from 0.0005 mm to 0.01 mm. The thickness of the surface layer is 0.
If it is less than 0002 mm, it is difficult to form a uniform layer. On the other hand, if the thickness of the surface layer exceeds 0.02 mm, the advantage of lamination may be impaired.

  The total thickness of the cellulose ester film is appropriately determined depending on the use of the photographic material, the optical material, etc., but is generally set in the range of 0.02 mm to 0.5 mm.

  The center line average roughness of the surface layer of the cellulose ester film according to the present invention is preferably 0.01 μm to 5 μm, and the center line average roughness is more preferably 0.1 μm to 1 μm. When the center line average roughness of the surface layer is less than 0.01 μm, the film is squeaked and fine scratches are generated. On the other hand, when the center line average roughness exceeds 5 μm, the flatness deteriorates.

  In producing a cellulose ester film, a cellulose ester, a plasticizer and a solvent (including a matting agent in the case of a surface layer) are generally used. The cellulose ester is typically a lower fatty acid ester of cellulose (eg, cellulose acetate, cellulose acetate butyrate and cellulose acetate propionate). Lower fatty acid means a fatty acid having 6 or less carbon atoms. Cellulose acetate includes cellulose triacetate (TAC) and cellulose diacetate (DAC).

Typical phosphoric ester plasticizers are represented by the following formulas (Ia) and (Ib).

In the formulas (Ia) and (Ib), R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ and R ⁷ are each an alkyl group (including a cycloalkyl group), an aryl group or an aralkyl group. is there. Each group may have a substituent. The alkyl group preferably has 1 to 12 carbon atoms. Examples of alkyl groups include methyl, ethyl, butyl, cyclohexyl and octyl. An example of an aryl group is phenyl. An example of an aralkyl group is benzyl. Examples of the substituent include an alkyl group (eg, methyl), an aryl group (eg, phenyl), an alkoxy group (eg, methoxy, butoxy) and an aryloxy group (eg, phenoxy). In the formula (Ib), R ⁸ is a divalent linking group selected from an alkylene group, an arylene group, a sulfonyl group, and combinations thereof. n is an integer of 1 or more, and preferably 1 to 10.

  The plasticizer is preferably a phosphate plasticizer, and examples of the phosphate plasticizer include triphenyl phosphate, biphenyl diphenyl phosphate, tricresyl phosphate, octyl diphenyl phosphate, triethyl phosphate and tributyl phosphate. It is. In addition, a carboxylic acid ester plasticizer may be used. Examples of carboxylate plasticizers include dimethyl phthalate, diethyl phthalate, dibutyl phthalate, dioctyl phthalate, diethyl hexyl phthalate, dimethoxyethyl phthalate, glycerol triacetate, butyl phthalyl butyl glycolate, ethyl phthalyl ethyl glycolate, methyl phthalate Ruethyl glycolate and triacetin are included. Examples of citrate esters include acetyl triethyl citrate (OACTE) and tributyl citrate (OACTB). Examples of other carboxylic acid esters include butyl oleate (BO), methyl acetyl linoleate (MAL), and sebatin. Examples include dibutyl acid (DBS) and various trimellitic acid esters. Examples of other low molecular plasticizers include o- or p-tolueneethylsulfonamide.

  The plasticizer is generally used in the range of 5 to 40% by weight based on the cellulose ester. It is preferably used in an amount of 10 to 20% by weight based on the cellulose ester. Trimellitic acid or pyromellitic acid ester may be used in combination with a phosphate ester plasticizer. Trimellitic acid and pyromellitic acid esters have the effect of preventing bleed out of the phosphate ester plasticizer. The esters of these acids are described in JP-A-5-5047.

  As the solvent, a lower aliphatic hydrocarbon chloride or a lower aliphatic alcohol is generally used. An example of a lower aliphatic hydrocarbon chloride is methylene chloride. Examples of lower aliphatic alcohols include methanol, ethanol, n-propyl alcohol, isopropyl alcohol and n-butanol. Examples of other solvents are substantially free of halogenated hydrocarbons, acetone, and ketones having 4 to 12 carbon atoms include, for example, methyl ethyl ketone, diethyl ketone, diisobutyl ketone, cyclohexanone and methylcyclohexanone, carbon Examples of the ester having 3 to 12 atoms include ethyl formate, propyl formate, pentyl formate, methyl acetate, ethyl acetate, propyl acetate, butyl acetate, pentyl acetate and 2-ethoxy-ethyl acetate. Examples of alcohols from 1 to 6 include methanol, ethanol, propanol, iso-propanol, 1-butanol, t-butanol, 2-methyl-2-butanol, 2-methoxyethanol, 2-butoxyethanol and the like, and carbon atoms The number is 3 Examples of ethers up to 12 include diisopropyl ether, dimethoxymethane, dimethoxyethane, 1,4-dioxane, 1,3-dioxolane, tetrahydrofuran, anisole and phenetole, and cyclic carbonization having 5 to 8 carbon atoms. Examples of hydrogens include cyclopentane, cyclohexane, cycloheptane, and cyclooctane.

  Of these solvents, methylene chloride is particularly preferred. Other solvents may be mixed with methylene chloride. However, the mixing ratio of methylene chloride is preferably 70% by weight or more. Particularly preferred mixing ratios are 75 to 93% by weight for methylene chloride and 7 to 25% by weight for other solvents. The solvent is removed in the formation of the cellulose ester film. The residual amount of solvent is generally less than 5% by weight. The residual amount is preferably less than 1% by weight, and more preferably less than 0.5% by weight.

  An ultraviolet absorber can be added to the cellulose ester film of the present invention, and examples of the ultraviolet absorber include benzophenone-based, salicylate-based, and benzotriazole-based compounds. Examples of the benzophenone-based ultraviolet absorber include 2,2′-dihydroxy-4,4′-dimethoxybenzophenone, 2-hydroxy-4-methoxybenzophenone and 2-hydroxy-4-n-dodecyloxybenzophenone. An example of the salicylate-based ultraviolet absorber is 4-t-butylphenyl salicylate. Examples of benzotriazole UV absorbers include 2- (hydroxy-5-t-octylphenyl) benzotriazole, 2- (2′-hydroxy-5′-methylphenyl) benzotriazole and 2- (2′-hydroxy -3,5'-di-t-butylphenyl) -5-chlorobenzotriazole. Examples of other ultraviolet absorbers include [2,2′-thiobis (4-t-octylphenolate)] n-butylamine nickel II. The amount of the ultraviolet absorber used is generally in the range of 0.1 to 3.0% by weight based on the cellulose ester.

  Matting agents, plasticizers, ultraviolet absorbers and the like may be added in advance in the dope in the dissolution tank, or may be added and mixed online in the middle of the dope feeding pipe.

  In order to produce the cellulose ester film of the present invention, a lamination casting method such as a co-casting method (multi-layer simultaneous casting), a sequential casting method, or a coating method can be used. When manufacturing by the co-casting method and the sequential casting method, first, dope for each layer is prepared. The co-casting method is based on a casting giusa that extrudes each casting dope for each layer (or three or more layers) on a casting support (band or drum) simultaneously from another slit or the like. This is a casting method in which a dope is extruded and each layer is cast at the same time, peeled off from a support at an appropriate time, and dried to form a film.

  In the sequential casting method, the casting dope for the first layer is first extruded from the casting gussa on the casting support and cast for the second layer without drying or drying. The dope for casting is extruded from the casting giusa, and thereafter, the dope of the third layer and thereafter is successively cast and laminated, peeled off from the support at an appropriate time, and dried to form a film. This is a casting method for molding.

  In general, the base layer film is formed by a solution casting method to prepare a coating solution to be applied to form a surface layer, and is applied to the film one side at a time or on both sides simultaneously using an appropriate coating machine. In this method, a coating film is applied and dried to form a film having a laminated structure.

  As described above, any of the co-casting method, the sequential casting method, and the coating method may be used for producing the cellulose ester film of the present invention. However, in general, the drying load after coating increases in the coating method, and the process becomes complicated in the sequential casting method, and it is difficult to maintain the flatness of the film. Since it is simple, the productivity is high, and the flatness of the film can be obtained relatively easily, it is preferable to manufacture by a co-casting method.

  The apparatus for producing the cellulose ester film of the present invention may be a solution casting apparatus using a casting band whose surface is mirror-finished or a solution casting apparatus using a casting drum. A solution casting apparatus using a casting band is shown in FIG. 3, and a solution casting apparatus using a casting drum is shown in FIG.

  In the band-type solution casting apparatus shown in FIG. 3, 11 is a stirrer in which cotton, a plasticizer and a solvent are charged. This stirrer 11 includes a transfer pump 12, a filter 13, a stock tank 14, It is connected to a casting die 17 via a casting liquid pump 15 and an additive injection pump 16 for adding a matting agent, a dye, an ultraviolet absorber (UV agent) and the like. A casting band 18 and a decompression chamber 19 are provided below the casting die 7.

  In the drum type solution casting apparatus shown in FIG. 4, reference numeral 20 denotes a casting drum, which is provided in place of the casting band 18 in the band type solution casting apparatus. The stirrer 11, the transfer pump 12, the filter 13, the stock tank 14, the casting liquid pump 15, the additive injection pump 16, and the casting die 17 are configured identically.

  As the casting die, those shown in FIGS. 5, 6 and 7 can be used.

  FIG. 5 shows a casting die used for forming a single-layer film, which is used for the sequential casting method. The casting die 30 has a single manifold 31 formed therein. FIG. 6 shows a multi-manifold type co-casting die. The co-casting die 30 is formed with three manifolds 32 and can form a film having a three-layer structure. FIG. 7 shows a feed block type co-casting die. The co-casting die 30 is provided with a manifold 33 and a feed block 34. The feed block 34 is joined together to form a plurality of layers (FIG. 7). In this case, the dope having three layers is cast.

  In the above casting die, a coat hanger die is used, but the present invention is not limited to this, and a die having another shape such as a T die may be used.

[Examples 1 to 4]
In the dope formulation shown in Table 1, the base layer dope and the surface layer dope were co-cast, and the thickness after drying was set to 0.06 mm (base layer) and 0.01 (surface layer) mm. It was dried with hot air at 100 ° C. until the residual solvent amount was 10 wt%, and then dried with hot air at 140 ° C. for 10 minutes.

[Examples 5 to 8]
With the dope formulation shown in Table 1, the base layer dope and the surface layer dope were successively cast, and the thicknesses after drying were 0.06 mm (base layer) and 0.01 mm (surface layer). It was dried with hot air at 100 ° C. until the residual solvent amount was 10 wt%, and then dried with hot air at 140 ° C. for 10 minutes.

[Examples 9 to 11]
In the dope formulation shown in Table 1, the base layer dope and the surface layer dope were co-cast as in Examples 1 to 4, and the respective thicknesses after drying were 0.07 mm (base layer) and 0.005 mm (surface layer). did. It was dried with hot air at 100 ° C. until the residual solvent amount was 10 wt%, and then dried with hot air at 140 ° C. for 10 minutes.

[Comparative Examples 1-4]
In the formulation of Table 1, only the surface layer dope was cast as a single layer, and the thickness after drying was 0.08 mm. It was dried with hot air at 100 ° C. until the residual solvent amount was 10 wt%, and then dried with hot air at 140 ° C. for 10 minutes.

  The obtained film samples were evaluated for static friction coefficient, creaking, dynamic friction coefficient, wrinkle generation, centerline average roughness and transparency. The results are shown in Table 2.

Evaluation method:
<Static friction coefficient>
After storing the sample sample in 25 ° C. and 60% RH for 2 hours, one of which was cut into 35 mm × 35 mm was used as a measuring needle, and the other sample was relatively loaded at a load of 100 g and a speed of 60 cm / min. The static friction coefficient was measured using a HEIDON-14 type dynamic friction coefficient measuring machine manufactured by Shinto Kagaku.

<Kishimi>
Squeaking is a phenomenon that occurs during winding when the inner surface and the outer surface of the roll are smooth when the film is wound when the film support is manufactured, or when the dynamic friction coefficient between the inner surface and the outer surface is high. For the evaluation of this state, a static friction coefficient is measured using a HEIDON-14 type dynamic friction coefficient measuring machine manufactured by Shinto Chemical Co., Ltd. for a sample sample stored at a constant temperature and constant humidity for a certain period of time.

The evaluation of the coefficient of static friction in the table is as follows.
○: 0.7 or less ×: 0.7 or more

The evaluation of the coefficient of dynamic friction in the table is as follows.
○: 0.6 or less ×: 0.6 or more

<Wrinkles>
Wrinkle is a phenomenon in which when a film is heat-treated at the time of producing a film support, stretching or shrinking of the film occurs non-uniformly due to poor slipperiness, and the film is wrinkled and flatness is deteriorated. For the evaluation of this phenomenon, a small width handling device is used to evaluate wrinkle generation in rolls and winding by handling with constant tension.

<Center line average roughness (Ra)>
The calculation principle of the center line average roughness conforms to the center line average roughness specified in JIS-B0601 “Surface roughness”. The measurement was performed using a universal surface shape measuring instrument, SE-3F, manufactured by Kosaka Laboratory.

<Transparency>
Transparency measured the transmittance | permeability of visible light using the transparency measuring device (For example, product made from KOTAKI Corporation).

The evaluation of transparency in the table is as follows.
◎: Transmittance is 92% or more ○: Transmittance is 90% or more Δ: Transmittance is 85% or more ×: Transmittance is 82% or more XX: Transmittance is 80% or less

  From the results shown in Table 2, it was found that the cellulose ester film according to the present invention was very excellent in transparency while preventing generation of creaking and wrinkles as compared with a cellulose ester film composed of a single layer.

  Moreover, it turned out that a static friction coefficient and centerline average roughness have the relationship of FIG. From the relationship shown in FIG. 8, it was found that when the center line average roughness is less than 0.01 μm, the coefficient of static friction increases, and the squeak becomes too large to use.

It is a fragmentary sectional view which shows the laminated constitution of the cellulose-ester film by this invention. It is a fragmentary sectional view which shows the laminated constitution of the cellulose-ester film by this invention. It is a schematic diagram of the apparatus which manufactures the cellulose-ester film by this invention. It is a schematic diagram of the apparatus which manufactures the cellulose-ester film by this invention. It is sectional drawing of the casting die used for the apparatus which manufactures the cellulose-ester film by this invention. It is sectional drawing of the casting die used for the apparatus which manufactures the cellulose-ester film by this invention. It is sectional drawing of the casting die used for the apparatus which manufactures the cellulose-ester film by this invention. It is a graph which shows the relationship between "centerline average surface roughness" and "static friction coefficient".

DESCRIPTION OF SYMBOLS 1 Base layer 2 Surface layer 11 Stirrer 12 Transfer pump 13 Filter 14 Stock tank 15 Casting liquid pump 16 Additive injection pump 17 Casting die 18 Casting band 19 Decompression chamber 20 Casting drum 30 Casting die

Claims (1)

A cellulose ester film having a multilayer structure having at least a base layer and a surface layer, each layer is formed of the same cellulose ester, 5 to 500 mg / m ^{2 of a} matting agent is added only to the surface layer, and the thickness of the surface layer is 0 .0002 mm to 0.02 mm, the total thickness is 0.02 mm to 0.5 mm, the center line average roughness of the surface is 0.1 μm to 1 μm, and inorganic particles are used as the matting agent. A photographic light-sensitive material or optical material characterized in that a surface layer is formed by casting a composition containing inorganic particles by a casting method, or a surface layer is formed by casting a composition containing inorganic particles by a sequential casting method. Cellulose ester film for materials.

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