JP5707855B2 - Method for producing hard coat film - Google Patents

Description

  The present invention relates to a method for producing a hard coat film, a hard coat film produced by the production method, a polarizing plate using the hard coat film as a transparent protective film, and a liquid crystal display using the hard coat film or the polarizing plate. Relates to the device.

  In recent years, a liquid crystal display device has been widely used as an image display device for a personal computer, a monitor of a portable device, a television, or the like because of various advantages such as low voltage and low power consumption, and miniaturization and thinning.

  In general, a transparent protective film is attached to a polarizing plate of a liquid crystal display device, for example, to improve scratch resistance. As this transparent protective film, for example, as disclosed in Patent Document 1, a hard coat film in which a hard coat layer is formed on a base film may be used. The hard coat film is required to have high transparency (clearness) and flatness in order to maintain excellent contrast and visibility of the liquid crystal display device.

  However, for example, if the hard coat film before use is rolled up and stored in a stacked state, the films are blocked and stuck together, deformed when peeled off, and flatness and thus clearness are impaired. There's a problem. This blocking problem is more likely to occur in a relatively high temperature and high humidity environment.

  As a technique for coping with this problem, for example, in Patent Document 2, a resin composition containing a first component and a second component is applied, a resin of the first component is precipitated by phase separation, and a fine surface is formed on the surface of the film. It is disclosed that blocking resistance is obtained by forming irregularities. However, in general, since the phase separation structure changes greatly due to slight differences in the raw material lot of the resin to be used and the composition of the composition, it is difficult to control the phase separation of the first component resin with this technique. There are problems such as it being difficult to form irregularities stably.

  Moreover, the fine unevenness | corrugation formed in the surface of a film must be a magnitude | size suitable for blocking resistance, and a magnitude | size which does not impair the clearness of a film. That is, it is necessary to make the blocking resistance and clearness of the film compatible.

JP 2007-152937 (paragraph 0011) JP 2009-13384 A (paragraph 0009)

  An object of the present invention is to stably provide a hard coat film excellent in blocking resistance and clearness.

  The inventor adjusted the drying temperature and drying time within a certain range in the rate-decreasing drying section when drying the resin composition applied on the base film, whereby the surface roughness of the hard coat layer was The present invention has been completed by finding that the surface roughness is suitable for blocking resistance and does not impair the clearness.

One aspect of the present invention is a method for producing a hard coat film in which a hard coat layer is formed by applying a resin composition on a base film and then drying the coating composition. A period for drying the resin composition at a temperature at which the viscosity of the resin in the resin composition applied on the base film is 3 to 7 mPa · s is provided, and the drying rate of the drying is such that the viscosity of the resin is low. When the length of the period is t seconds and the volume of the resin in the resin composition applied per 1 m ^{2 of the} base film is Vcm ³ / m ² , the temperature is 3 mPa · s or more. The length of the said period is set so that it may become 0.5V <= t <= 4.5V, It is a manufacturing method of the hard coat film characterized by the above-mentioned.

  In the said manufacturing method, it is preferable to manufacture the hard coat film whose arithmetic average roughness Ra of a hard-coat layer is 2-20 nm.

  In the said manufacturing method, it is preferable that resin contained in a resin composition is actinic radiation curable resin.

  In the said manufacturing method, it is preferable that a base film is a cellulose-ester film.

In the production method, the resin composition contains a solvent having a solubility parameter of 18.5 to 21 (MPa) ^{1/2 and} the resin: solvent mass ratio in the resin composition is 100: 10 to 100. : 50 is preferable.

  Another aspect of the present invention is a hard coat film produced by the production method.

  Yet another aspect of the present invention is a polarizing plate characterized in that the hard coat film is used on at least one surface.

  Still another aspect of the present invention is a liquid crystal display device using the hard coat film or the polarizing plate.

  According to the present invention, the surface roughness of the hard coat layer is adjusted by adjusting the drying temperature and the drying time within the above ranges in the rate-decreasing drying section when drying the resin composition coated on the base film. Since the surface roughness is suitable for blocking resistance and does not impair the clearness, a hard coat film excellent in blocking resistance and clearness is stably provided. In addition, a polarizing plate and a liquid crystal display device using the hard coat film are provided.

It is explanatory drawing of a structure of the polarizing plate using the hard coat film which concerns on embodiment of this invention. It is explanatory drawing of the relationship between temperature and resin viscosity. It is explanatory drawing of the relationship between resin volume and drying time.

  Hereinafter, although the form for implementing this invention is demonstrated in detail, this invention is not limited to these.

<Main features of this embodiment>
As illustrated in FIG. 1, the method for producing a hard coat film according to the present embodiment forms a hard coat layer by applying a resin composition on a base film and then drying. The resin composition at a temperature at which the viscosity of the resin in the resin composition (hereinafter sometimes referred to as a hard coat layer composition) applied on the base film is 3 to 7 mPa · s in the drying rate reduction drying section. A period of drying is provided. When the length of the period is t seconds and the volume of the resin in the resin composition applied per 1 m ^{2 of the} base film is Vcm ³ / m ² , 1.5V ≦ t ≦ 4.5V Is set to the length of the period.

  As illustrated in FIG. 2, for example, the viscosity of the resin A decreases as the temperature increases, and the viscosity becomes 7 mPa · s or less near 82 ° C., and the viscosity becomes less than 3 mPa · s near 96 ° C. Therefore, when only the resin A is contained as a resin in the resin composition applied on the base film, the temperature at which the viscosity of the resin in the resin composition is 3 to 7 mPa · s is approximately 82 to 96. It becomes ℃.

  Similarly, the viscosity of the resin B decreases as the temperature rises, and the viscosity becomes 7 mPa · s or less near 96 ° C., and the viscosity becomes less than 3 mPa · s around 110 ° C. Therefore, when only the resin B is contained as a resin in the resin composition applied on the base film, the temperature at which the viscosity of the resin in the resin composition is 3 to 7 mPa · s is approximately 96 to 110. It becomes ℃.

  In the case of Resin C, the viscosity does not become 7 mPa · s or less unless the temperature rises to around 126 ° C. And when temperature rises to 142 degreeC vicinity, a viscosity will be less than 3 mPa * s. Therefore, when only the resin C is contained as a resin in the resin composition applied on the base film, the temperatures at which the viscosity of the resin in the resin composition is 3 to 7 mPa · s are the resin A and B. Relatively higher, approximately 126-142 ° C.

  These resins A, B, and C are merely examples for explanation, and are not limited thereto. Moreover, you may mix multiple types of resin in a resin composition. In that case, the temperature at which the viscosity of the resin in the resin composition becomes 3 to 7 mPa · s varies depending on the type of the mixed resin, the mixing ratio, and the like.

  Thus, the temperature at which the resin has a viscosity of 3 to 7 mPa · s varies depending on the type of resin. In the present embodiment, it is important to provide a period during which the resin composition is dried at a temperature at which the viscosity of the resin in the resin composition applied on the base film is 3 to 7 mPa · s in the rate-decreasing drying section. In addition, the period for drying the resin composition at the above temperature may be provided in the decreasing rate drying section, and another period for drying the resin composition at another temperature is provided in addition to the decreasing rate drying section. Also good. However, it is not preferable to provide a period for drying the resin composition at a temperature higher than the above temperature (that is, at a temperature at which the viscosity of the resin is less than 3 mPa · s) because the flowability of the resin becomes excessive (the reason will be described later). To do).

  In general, when drying starts, the drying process changes from a constant drying rate (constant drying interval) to a gradually decreasing state (decreasing drying interval). In the constant rate drying section, the amount of heat given for drying is consumed for evaporation of the solvent from the coating film surface of the resin composition coated on the base film. When the solvent on the coating film surface decreases from this state, the evaporation surface moves from the coating film surface to the inside of the coating film, and shifts to the decremental drying section. In the decreasing rate drying section, the temperature of the coating film rises, for example, approaches the temperature of hot air blown for drying, the viscosity of the resin in the resin composition applied on the base film decreases, and the resin flow Sex will increase.

  And like this embodiment, when the viscosity of the resin in the resin composition apply | coated on the base film fell to 3-7 mPa * s in the decreasing rate drying area, it produced in the coating film of the resin composition. Convection causes the surface of the coating to become uneven, and a large number of fine protrusions appear irregularly on the surface of the coating, resulting in the formation of a large number of fine irregularities on the surface of the hard coat layer. The

In many cases, the viscosity of the resin is temperature-dependent and can be estimated from the Andrade viscosity equation below. In the formula, η is the viscosity, E is the apparent activation energy, R is the gas constant, T is the absolute temperature, and A and B are constants.
η = A · exp (E / RT)
lnη = (A + B) / T
Therefore, if the viscosity η at two temperatures is experimentally measured in advance and the values of the constants A and B are obtained by substituting them into the above equation, the viscosity η at other temperatures can be estimated. is there.

  In this embodiment, it is important to provide a period during which the resin composition is dried at a temperature at which the resin viscosity is 3 to 7 mPa · s in the decreasing rate drying section. In addition to this, the length of the period is also important. It is.

As exemplified in FIG. 3, the volume of the resin in the resin composition applied per 1 m ^{2 of the} base film is Vcm ³ / m ² , this is taken on the x axis, and the drying time of the resin composition is t seconds, This is taken on the y-axis. The line of t = 1.5V indicates that the drying time becomes longer as the resin volume increases. For example, when the resin volume is 5 cm ³ / m ² (when converted to thickness, the drying time is 7 μm). .5 seconds.

Similarly, the line of t = 4.5V indicates that the drying time becomes longer as the resin volume becomes larger. For example, when the resin volume is 4 cm ³ / m ² (when converted to thickness, it is 4 μm), the drying time is longer. The time is defined as 18 seconds.

In this embodiment, the length (t seconds) of the period for drying the resin composition at a temperature at which the resin viscosity becomes 3 to 7 mPa · s depends on the resin volume (Vcm ³ / m ² ), and t = It is important to dry the resin composition at a time of 1.5 V or more (t ≧ 1.5 V) and t = 4.5 V or less (t ≦ 4.5 V).

Therefore, for example, when a resin composition containing only the resin A of FIG. 2 as a resin is applied on the base film so that the volume of the resin A is 5 (cm ³ / m ² ), As illustrated by reference symbols a and b in FIG. 2, drying is performed at a drying temperature of 82 to 96 ° C. for 7.5 to 22.5 seconds.

Similarly, for example, when a resin composition containing only the resin B of FIG. 2 as a resin is applied on the base film so that the volume of the resin B is 4 (cm ³ / m ² ), the rate of drying section In FIG. 2, as exemplified by reference numerals d and e, the film is dried at a drying temperature of 96 to 110 ° C. for 6 to 18 seconds.

  Thus, by adjusting the drying temperature and drying time in the decreasing rate drying section to the above ranges, the resin viscosity in the resin composition is reduced to 3 to 7 mPa · s, and is generated in the coating film of the resin composition. Due to the convection, the surface of the coating becomes uneven, and a large number of fine protrusions appear irregularly on the surface of the coating, resulting in the formation of irregularities on the surface of the hard coat layer. Thus, the surface roughness of the hard coat layer is suitable for blocking resistance and does not impair the clearness.

  Here, the surface roughness suitable for blocking resistance is, for example, the contact area between the films to the extent that blocking (sticking) between the films is suppressed when the hard coat films are left in a stacked state. Refers to reduced surface roughness.

  The surface roughness that does not impair the clearness is, for example, the degree to which the excellent contrast and visibility of the liquid crystal display device are maintained when the hard coat film is used as a transparent protective film for the polarizing plate of the liquid crystal display device. Furthermore, it refers to the surface roughness that maintains the high transparency of the hard coat film.

  As the surface roughness that is suitable for such blocking resistance and does not impair the clearness, the arithmetic average roughness Ra of the hard coat layer is preferably 2 to 20 nm, more preferably 3 to 18 nm, More preferably, it is 4-16 nm. The arithmetic average roughness Ra is a value measured by, for example, an optical interference type surface roughness meter (RST / PLUS, manufactured by WYKO) based on the provisions of JIS B0601: 1994. When the arithmetic average roughness Ra of the hard coat layer is less than 2 nm, the expression of blocking resistance may be insufficient. On the other hand, when the arithmetic average roughness Ra of the hard coat layer exceeds 20 nm, the clearness of the hard coat layer may be deteriorated.

  From such a viewpoint, as exemplified by reference numerals c and f in FIG. 2, when the drying temperature in the decreasing rate drying section is a temperature at which the resin viscosity is less than 3 mPa · s, the fluidity of the resin becomes excessive, The surface roughness of the hard coat layer becomes excessively large. As a result, as described above, the clearness of the hard coat layer may deteriorate. On the contrary, when the drying temperature in the decreasing rate drying section is a temperature at which the resin viscosity exceeds 7 mPa · s, the fluidity of the resin is insufficient, and the surface roughness of the hard coat layer becomes excessively small. As a result, as described above, the expression of blocking resistance may be insufficient.

  Further, when the drying time in the decreasing rate drying section is below the t = 1.5 V line illustrated in FIG. 3, the fluidity of the resin is insufficient and the surface roughness of the hard coat layer becomes excessively small. . As a result, as described above, the expression of blocking resistance may be insufficient. On the contrary, when the drying time in the decreasing rate drying section exceeds the t = 4.5 V line illustrated in FIG. 3, the fluidity of the resin becomes excessive, and the surface roughness of the hard coat layer becomes excessively large. End up. As a result, as described above, the clearness of the hard coat layer may deteriorate.

  The manufacturing method of the hard coat film according to the present embodiment includes the hard coat layer only by controlling the drying temperature and the drying time in the rate-decreasing drying section when drying the resin composition coated on the base film. One feature is that the surface can be formed with fine irregularities having roughness that is suitable for blocking resistance and does not impair clearness. For example, when hard coat films are blocked and attached to each other during storage by forming fine irregularities with roughness that is suitable for blocking resistance and does not impair clearness on the surface of the hard coat layer Both the problem that the flatness and thus the clearness are deteriorated and the problem that the transparency of the hard coat film is lowered and the excellent contrast and visibility of the liquid crystal display device are lowered are avoided at the same time.

  Conventionally, as a method of forming fine irregularities on the film surface in order to obtain blocking resistance, a method of pressing the surface of the film with a mold, a method of mixing fine particles in a resin composition containing a resin constituting the film, compatibility A method of causing phase separation by mixing a plurality of types of resins that are poor in a resin composition is known. However, each of them requires an extra mold and a stamping process, which increases costs and decreases productivity, may cause unevenness due to aggregation of fine particles, and may impair the appearance of the film. There are various adverse effects such as difficulty in stably forming fine irregularities. Since the manufacturing method of the hard coat film according to the present embodiment only controls the drying temperature and the drying time in the decreasing rate drying section, there is an advantage that such various disadvantages of the conventional technology do not occur. Therefore, a hard coat film excellent in blocking resistance and clearness can be obtained stably.

  In the present embodiment, the hard coat layer is formed by applying a resin composition (hard coat layer composition) containing a resin constituting the hard coat layer onto the base film, drying the resin composition, and curing the resin. Can be formed.

  The resin composition preferably contains a solvent that swells or dissolves the base film. This is because when the resin composition is applied onto the base film, mixing at the interface between the base film and the resin composition proceeds and the adhesion of the hard coat layer to the base film is improved. Examples of such a solvent include ketones such as methyl ethyl ketone and acetone; and acetates such as methyl acetate, ethyl acetate and butyl acetate; These can be used singly or in combination of two or more.

When the base film is a cellulose ester film, the resin composition preferably contains a solvent having a solubility parameter (SP value) of 18.5 to 21 (MPa) ^1/2 . This is because when the resin composition is applied onto the cellulose ester film, mixing at the interface between the cellulose ester film and the resin composition proceeds and the adhesion of the hard coat layer to the cellulose ester film is improved. Examples of such solvents include acetone (20.3), butyl lactate (19.2), cyclohexanone (20.3), diacetone alcohol (18.6), ethyl acetate (18.6), ethyl lactate. (20.5), methyl acetate (19.6), methylcyclohexanone (19.0), methyl ethyl ketone (19.0), propylene glycol methyl ether (20.7), tetrahydrofuran (18.6) and the like. These can be used singly or in combination of two or more.

Here, the solubility parameter (SP value) is defined by the following equation. Where δE is the cohesive energy per mole of substance and V is the molar volume of the substance. The unit of the solubility parameter is (MPa) ^1/2 .
SP value = (δE / V) ^1/2

  The solubility parameter is a measure of the miscibility between liquids as described in J. H. It was proposed by Hildebrand. Empirically, it is known that the smaller the difference in solubility parameter between two substances, the greater the solubility.

  The action of the solvent on the polymer substance can also be explained by the solubility parameter. The solubility parameter of the polymer substance can be determined by examining the solubility of the polymer substance in a solvent having a known solubility parameter.

  For solubility parameters, see, for example, J.M. H. Hildebrand, J.M. M.M. Prausnitz. R. L. Reference can be made to “Regular and Related Solutions” by Scott, Van Nostrand-Reinhold, Princeton (1970), “Polymer Data Handbook Fundamentals”, Polymer Society of Japan, and the like.

  In the present embodiment, specific numerical values of the solubility parameter are J.P. BRANDRUP and E. H. Numerical values described in IMMERGUT, “POLYMER HANDBOOK”, THIRD EDITION, JOHN WILEY & SONS (1989) were used.

The solubility parameter of the cellulose ester is about 19 to 20 (MPa) ^1/2 depending on the degree of substitution. Therefore, the solvent having a solubility parameter of 18.5 to 21 (MPa) ^1/2 is cellulose ester. Swells or dissolves. For this reason, when the substrate film is a cellulose ester film, if the resin composition contains a solvent having a solubility parameter of 18.5 to 21 (MPa) ^1/2 , the resin composition is converted to cellulose ester. When applied on the film, mixing at the interface between the cellulose ester film and the resin composition proceeds, and the adhesion of the hard coat layer to the cellulose ester film is improved.

  In the present embodiment, the resin: solvent content mass ratio in the resin composition is preferably 100: 10 to 100: 50. When the content ratio of the solvent is less than 10, the adhesion of the hard coat layer to the base film may be insufficient. When the content ratio of the solvent exceeds 50, the haze of the hard coat film may be deteriorated.

In the present embodiment, the resin composition may contain other solvents as long as the solubility parameter does not inhibit the effect of the solvent having a solubility parameter of 18.5 to 21 (MPa) ^1/2 . Examples of such solvents include hydrocarbons such as toluene (18.2) and xylene (18.0); methanol (29.7), ethanol (26.0), isopropanol (23.5), butanol (23.3), alcohols such as cyclohexanol (23.3); ketones such as methyl isobutyl ketone (17.2); glycol ethers; These can be used singly or in combination of two or more.

  As means for applying the resin composition on the base film, known application means such as a gravure coater, dip coater, reverse coater, wire bar coater, die (extrusion) coater, and ink jet can be used.

  The coating amount of the resin composition is preferably 0.1 to 40 μm, more preferably 0.5 to 30 μm, as a wet film thickness. Moreover, as a dry film thickness (namely, film thickness of a hard-coat layer), an average film thickness of 0.1-30 micrometers is preferable, 1-20 micrometers is more preferable, and 5-10 micrometers is more preferable.

  When two or more hard coat layers are provided, the thickness (dry average film thickness) of the hard coat layer in contact with the base film is preferably 0.05 to 2 μm. Lamination of two or more hard coat layers can be performed, for example, by simultaneous multilayering. The simultaneous multi-layering is to form two or more hard coat layers simultaneously by applying two or more layers of the resin composition on the base film without going through a drying step. In order to perform simultaneous multi-layering, for example, the resin compositions may be sequentially applied using a coater, or the resin compositions may be simultaneously applied using a die having a plurality of slits.

  As a method of drying the resin composition applied on the base film, for example, a known drying method such as a method of spraying hot air on the resin composition, a method of heating the resin composition by applying a heater or microwave, etc. Can be used.

In the present embodiment, as described above, as a condition for drying the resin composition applied on the base film, the viscosity of the resin in the resin composition applied on the base film is 3 in the decreasing rate drying section. A period for drying the resin composition at a temperature of ˜7 mPa · s is provided, and the length of the period is t seconds, and the volume of the resin in the resin composition applied per 1 m ^{2 of the} base film is Vcm. The length of the period is set so that 1.5 V ≦ t ≦ 4.5 V when ³ / m ² is satisfied.

  As described above, the temperature at which the resin viscosity becomes 3 to 7 mPa · s varies depending on the type and mixing ratio of the resin, but is preferably 80 ° C. or higher, more preferably 85 ° C. or higher, and 90 ° C. or higher. Further preferred. Moreover, 150 degrees C or less is preferable, 145 degrees C or less is more preferable, and 140 degrees C or less is further more preferable. By setting the drying temperature in the decreasing rate drying section to such a relatively high temperature, convection is surely generated in the coating film of the resin composition, and the surface of the coating film becomes non-uniform. A large number of fine protrusions appear irregularly on the surface, and as a result, a large number of fine irregularities are irregularly formed on the surface of the hard coat layer, and the surface roughness of the hard coat layer is suitable for blocking resistance, And it becomes surface roughness (for example, arithmetic average roughness Ra of a hard-coat layer is 2-20 nm) which does not impair clearness.

  In addition, by drying the resin composition at a relatively high temperature in this way, the mixing of the interface between the base film and the resin composition further proceeds, and the penetration of the resin composition into the base film is promoted. The anchor effect is increased and the adhesion between the base film and the hard coat layer is further improved.

  After the resin composition is dried and the resin is cured, the cured film (that is, the hard coat layer) may be further heat-treated as necessary. As temperature of such heat processing, 80 degreeC or more is preferable, 100 degreeC or more is more preferable, and 120 degreeC or more is further more preferable. By performing such a heat treatment, the mechanical strength (abrasion resistance, pencil hardness, etc.) of the hard coat layer becomes better.

  According to this embodiment, by adjusting the drying temperature and the drying time to the above ranges in the rate-decreasing drying section when drying the resin composition (hard coat layer composition) applied on the base film, The surface roughness of the hard coat layer is suitable for blocking resistance and does not impair the clearness. Therefore, the hard coat film excellent in blocking resistance and clearness is stably manufactured by the manufacturing method according to the present embodiment.

  In addition, the above is a case where the period during which the resin composition is dried at a temperature at which the viscosity of the resin in the resin composition applied on the base film is 3 mPa · s or more and 7 mPa · s or less is provided in the rate-decreasing drying section. As described above, instead of this, the period during which the resin composition is dried at a temperature at which the viscosity of the resin in the resin composition coated on the base film exceeds 3 mPa · s and is 7 mPa · s or less is reduced by a drying interval. Even if it is provided, the same effects can be obtained.

  Hereinafter, other characteristic portions of the present embodiment will be described in order.

<Hard coat film>
As illustrated in FIG. 1, the hard coat film according to the present embodiment is basically configured to have a hard coat layer on a base film. The arithmetic average roughness Ra of the hard coat layer is preferably 2 to 20 nm, more preferably 3 to 18 nm, and still more preferably 4 to 16 nm.

[Hard coat layer]
In the present embodiment, the hard coat layer preferably has fine protrusions on the surface so that the arithmetic average roughness Ra is 2 to 20 nm. The height of the fine protrusion is preferably 1 nm to 1 μm, and more preferably 10 nm to 0.5 μm. The width of the fine protrusion is preferably 50 nm to 100 μm, and more preferably 50 nm to 50 μm. The height and width of the fine protrusion can be obtained from cross-sectional observation. For example, in the cross-sectional observation image, a center line is drawn horizontally so as to cross the fine protrusion, and the distance between the peak and the center line on the vertical line that descends perpendicularly to the center line from the peak of the fine protrusion The distance between the two intersections of the two oblique lines and the center line along both slopes of the mountain of the fine protrusion can be the width of the fine protrusion. The number of fine protrusions is preferably about 500 to 200,000 / mm ² , for example.

  In this embodiment, 1% or less is appropriate for the haze value of the hard coat layer, and 0.7% or less is preferable from the viewpoint of maintaining the clearness of the film and the visibility of the liquid crystal display device. In order to control the haze value of the hard coat layer, adjustment of the resin and solvent content mass ratio of the resin and solvent of the hard coat layer composition, and the rate of drying in the drying process It can be achieved with the processing temperature condition of the section. In addition, since the arithmetic average roughness Ra of the hard coat layer also affects the haze value as surface haze, it is effective to control the shape and number of the protrusions.

  In addition, the hard coat film which concerns on this embodiment is 2H or more in pencil hardness which is a parameter | index of hardness, More preferably, it is 3H or more. If it is 3H or more, it is not only difficult to be scratched in the polarizing plate forming step of the liquid crystal display device, but also used for outdoor applications, and is a surface protective film for large liquid crystal display devices and liquid crystal display devices for digital signage. Excellent mechanical properties when used. Pencil hardness is specified by JIS K5400 using a test pencil specified by JIS S 6006 under the condition of a weight of 500 g after the prepared hard coat film is conditioned at a temperature of 23 ° C. and a relative humidity of 55% for 2 hours or more. It is a value measured according to the pencil hardness evaluation method.

  In the present embodiment, the hard coat layer is preferably composed of an actinic radiation curable resin. Therefore, in this embodiment, it is preferable that a hard-coat layer composition contains actinic radiation curable resin. The actinic radiation curable resin refers to a resin that can be cured through a crosslinking reaction or the like by irradiation with actinic rays such as ultraviolet rays or electron beams.

  As the actinic radiation curable resin, a component containing a monomer having an ethylenically unsaturated double bond is preferably used, and the actinic radiation curable resin layer is cured by irradiation with actinic radiation such as ultraviolet rays or electron beams. It is formed.

  Typical examples of actinic radiation curable resins include ultraviolet curable resins and electron beam curable resins, but resins that are cured by ultraviolet irradiation are superior in mechanical strength (such as scratch resistance and pencil hardness). To preferred.

  As the ultraviolet curable resin, for example, an ultraviolet curable urethane acrylate resin, an ultraviolet curable polyester acrylate resin, an ultraviolet curable epoxy acrylate resin, an ultraviolet curable polyol acrylate resin, or an ultraviolet curable epoxy resin is preferable. Used. Of these, UV curable acrylate resins are preferred.

  As the ultraviolet curable acrylate resin, a polyfunctional acrylate is preferable. As the polyfunctional acrylate, pentaerythritol polyfunctional acrylate, dipentaerythritol polyfunctional acrylate, pentaerythritol polyfunctional methacrylate, dipentaerythritol polyfunctional methacrylate and the like are preferable. Here, the polyfunctional acrylate is a compound having two or more acryloyloxy groups or methacryloyloxy groups in the molecule.

  Examples of the polyfunctional acrylate monomer include ethylene glycol diacrylate, diethylene glycol diacrylate, 1,6-hexanediol diacrylate, neopentyl glycol diacrylate, trimethylolpropane triacrylate, trimethylolethane triacrylate, and tetramethylolmethane triacrylate. , Tetramethylolmethane tetraacrylate, pentaglycerol triacrylate, pentaerythritol diacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, glycerol triacrylate, dipentaerythritol triacrylate, dipentaerythritol tetraacrylate, dipentaerythritol pentaacrylate, dipentaerythritol Lithol hexaacrylate, tris (acryloyloxyethyl) isocyanurate, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, 1,6-hexanediol dimethacrylate, neopentyl glycol dimethacrylate, trimethylolpropane trimethacrylate, trimethylolethane trimethacrylate, Tetramethylol methane trimethacrylate, tetramethylol methane tetramethacrylate, pentaglycerol trimethacrylate, pentaerythritol dimethacrylate, pentaerythritol trimethacrylate, pentaerythritol tetramethacrylate, glycerol trimethacrylate, dipentaerythritol trimethacrylate, dipentaerythritol tetramethacrylate Acrylate, dipentaerythritol penta methacrylate, dipentaerythritol hexa methacrylate, dimethylol propane tetraacrylate, etc. isocyanurate derivative of an active ray curable are preferably exemplified. Commercially available products may be used as these polyfunctional acrylates, such as pentaerythritol tri / tetraacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd., A-TMM-3L), pentaerythritol triacrylate (manufactured by Kyoeisha Chemical Co., Ltd., PE-3A). Etc. can be obtained. In addition, these compounds are used individually or in mixture of 2 or more types, respectively.

  The isocyanurate derivative of the actinic radiation curable resin is not particularly limited as long as it is a compound having a structure in which one or more ethylenically unsaturated groups are bonded to the isocyanuric acid skeleton, but three or more in the same molecule. A compound having an ethylenically unsaturated group and one or more isocyanurate rings is preferred.

  A commercial item can also be used as such an isocyanuric acid triacrylate compound, for example, Shin-Nakamura Chemical Co., Ltd. A-9300 etc. are mentioned. As a commercial item of an isocyanuric acid diacrylate compound, Toagosei Co., Ltd. Aronix M-215 etc. are mentioned, for example. Examples of the mixture of the isocyanuric acid triacrylate compound and the isocyanuric acid diacrylate compound include Aronix M-315 and Aronix M-313 manufactured by Toagosei Co., Ltd. Examples of ε-caprolactone-modified actinic radiation-curable isocyanurate derivatives include A-9300-1CL manufactured by Shin-Nakamura Chemical Co., Ltd., which is ε-caprolactone-modified tris- (acryloxyethyl) isocyanurate, and Aronix manufactured by Toagosei Co., Ltd. Examples thereof include, but are not limited to, M-327.

  These compounds are used alone or in admixture of two or more. Moreover, you may use oligomers, such as a dimer and a trimer of the said monomer. The viscosity of the polyfunctional acrylate is preferably 3000 mPa · s or less, more preferably 1500 mPa · s or less, at 25 ° C. Particularly preferably, it is 1000 mPa · s or less. Examples of such low viscosity resins include glycerin triacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate and the like. By using such a low-viscosity resin, sufficient fluidity of the resin composition can be obtained in the drying step, so that a protrusion shape is easily formed on the hard coat layer. In addition, the said viscosity is the value measured on 25 degreeC conditions using the E-type viscosity meter.

  Further, the hard coat layer according to this embodiment may contain a monofunctional acrylate. Monofunctional acrylates include isobornyl acrylate, 2-hydroxy-3-phenoxypropyl acrylate, isostearyl acrylate, benzyl acrylate, ethyl carbitol acrylate, phenoxyethyl acrylate, lauryl acrylate, isooctyl acrylate, tetrahydrofurfuryl acrylate, behenyl Examples include acrylate, 4-hydroxybutyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, and cyclohexyl acrylate. Monofunctional acrylates can be obtained from Shin Nakamura Chemical Co., Ltd., Osaka Organic Chemical Industry Co., Ltd., and the like. These compounds are used alone or in admixture of two or more. Moreover, oligomers, such as a dimer and a trimer of the said monomer, may be sufficient.

  In addition, when using monofunctional acrylate, it is preferable to contain by polyfunctional acrylate: monofunctional acrylate = 80: 20-99: 2 by the mass ratio of polyfunctional acrylate and monofunctional acrylate.

  Furthermore, urethane acrylate may be used as the actinic radiation curable resin. As urethane acrylate, for example, commercially available products such as Beam Set 575CB manufactured by Arakawa Chemical Industries, Ltd. and UA-306H manufactured by Kyoeisha Chemical Co., Ltd. can be used.

  The amount of the actinic radiation curable resin in the hard coat layer composition is usually 10 to 99 parts by mass, preferably 35 to 99 parts by mass, when the entire composition is 100 parts by mass. When the amount of the actinic radiation curable resin is small, the film strength of the hard coat layer cannot be obtained sufficiently. Moreover, when there are many compounding quantities, since the malfunction of the film thickness uniformity at the time of apply | coating with the well-known application | coating method mentioned later, an application | coating stripe, etc. generate | occur | produce, it is unpreferable.

  The hard coat layer preferably further contains a photopolymerization initiator in order to accelerate the curing of the actinic radiation curable resin. As a compounding quantity of a photoinitiator, it is preferable to contain by mass ratio with photoinitiator: active ray curable resin = 20: 100-0.01: 100.

  Specific examples of the photopolymerization initiator include alkylphenone series, acetophenone, benzophenone, hydroxybenzophenone, Michler's ketone, α-amyloxime ester, thioxanthone, and derivatives thereof, but are not particularly limited thereto. It is not a thing. Commercially available products may be used, and preferred examples include Irgacure 184, Irgacure 907, and Irgacure 651 manufactured by Ciba Japan.

  The hard coat layer preferably contains an ultraviolet absorber. Since the ultraviolet absorber absorbs ultraviolet rays of 400 nm or less, durability can be improved. In particular, the ultraviolet absorber preferably has a transmittance of 10% or less at a wavelength of 370 nm, more preferably 5% or less, and still more preferably 2% or less. Specific examples of the ultraviolet absorber are not particularly limited. For example, oxybenzophenone compounds, benzotriazole compounds, salicylic acid ester compounds, benzophenone compounds, cyanoacrylate compounds, triazine compounds, nickel complex salts, inorganic powders. Examples include the body.

  More specifically, for example, 5-chloro-2- (3,5-di-sec-butyl-2-hydroxylphenyl) -2H-benzotriazole, (2-2H-benzotriazol-2-yl) -6 -(Linear and side chain dodecyl) -4-methylphenol, 2-hydroxy-4-benzyloxybenzophenone, 2,4-benzyloxybenzophenone, etc. can be used. Commercially available products may be used, and for example, Tinuvin 109, Tinuvin 171, Tinuvin 234, Tinuvin 326, Tinuvin 327, Tinuvin 328 and the like manufactured by Ciba Japan are preferably used.

  Preferred ultraviolet absorbers are benzotriazole ultraviolet absorbers, benzophenone ultraviolet absorbers, and triazine ultraviolet absorbers, and particularly preferred are benzotriazole ultraviolet absorbers and benzophenone ultraviolet absorbers.

  In addition, a discotic compound such as a compound having a 1,3,5 triazine ring is also preferably used as the ultraviolet absorber.

  As the UV absorber, a polymer UV absorber can be preferably used, and a polymer type UV absorber is particularly preferably used.

  In addition, as a benzotriazole type ultraviolet absorber, TINUVIN 109 (octyl-3- [3-tert-butyl-4-hydroxy-5- (5-chloro-) manufactured by Ciba Specialty Chemicals Co., Ltd.) is a commercially available product. 2H-benzotriazol-2-yl) phenyl] propionate and 2-ethylhexyl-3- [3-tert-butyl-4-hydroxy-5- (5-chloro-2H-benzotriazol-2-yl) phenyl] propionate Mixture), TINUVIN 928 (2- (2H-benzotriazol-2-yl) -6- (1-methyl-1-phenylethyl) -4- (1,1,3,3-tetramethylbutyl) phenol), etc. Can be used.

  As a triazine type ultraviolet absorber, TINUVIN 400 (2- (4,6-bis (2,4-dimethylphenyl) -1,3,5-triazine-) manufactured by Ciba Specialty Chemicals Co., Ltd., which is a commercial product, is used. 2-yl) -5-hydroxyphenyl and oxirane reaction product), TINUVIN 460 (2,4-bis [2-hydroxy-4-butoxyphenyl] -6- (2,4-dibutoxyphenyl) -1 , 3-5-triazine), TINUVIN 405 (2- (2,4-dihydroxyphenyl) -4,6-bis- (2,4-dimethylphenyl) -1,3,5-triazine and (2-ethylhexyl)) -Reaction product of glycidic acid ester) and the like.

  Furthermore, the hard coat layer is composed of two or more layers, and the hard coat layer in contact with the base film contains the ultraviolet absorber, so that the objective effect of the present embodiment is exhibited well, and the hard coat layer The film strength (scratch resistance) and the pencil hardness are preferred from the standpoint of obtaining good results. As content, it is preferable to contain by mass ratio, ultraviolet absorber: hard-coat layer composition = 0.01: 100-10: 100.

  Furthermore, the hard coat layer may contain a conductive agent in order to impart antistatic properties, and preferred conductive agents include metal oxide particles or π-conjugated conductive polymers. An ionic liquid is also preferably used as the conductive compound.

  Furthermore, the hard coat layer has a nonionic surfactant such as a silicone surfactant, a fluorosurfactant or a polyoxyether, an anionic interface, from the viewpoint of coating properties and the uniform dispersibility of fine particles. An activator and a fluorine-siloxane graft polymer may be included.

  The fluorine-siloxane graft polymer refers to a copolymer polymer obtained by grafting polysiloxane containing siloxane and / or organosiloxane alone and / or organopolysiloxane to at least a fluorine-based resin. Moreover, as a commercial item, Fuji Chemical Industries Ltd. ZX-022H, ZX-007C, ZX-049, ZX-047-D etc. can be mentioned.

  The silicone-based surfactant is a surfactant obtained by substituting a part of the methyl group of the silicone oil with a hydrophilic group. Examples of the hydrophilic group include polyether, polyglycerin, pyrrolidone, betaine, sulfate, phosphate, and quaternary salt. Specific products of silicone surfactants include, for example, SH200, BY16-873, PRX413 (dimethylsilicone oil; manufactured by Toray Dow Corning Silicone Co., Ltd.), SH203, SH230, SF8416 (alkyl-modified silicone oil; Toray Dow Corning Silicone Co., Ltd.), SF8417, BY16-208, BY16-209, BY16-849, BY16-872, FZ-2222, FZ-2207 (dimethylpolysiloxane / polyethylene oxide linear block copolymer; Japan) Unicar Co., Ltd. FZ series), KF-101, KF-102, KF-105 (epoxy-modified silicone oil; manufactured by Shin-Etsu Chemical Co., Ltd.), BYK-UV3500, BYK-UV3510, BYK-333, BYK- 31, BYK-337 (polyether-modified silicone oil, BYK Chemie Japan Ltd.), but like without limitation.

  Moreover, it is preferable to add these components in 0.01-5 mass% with respect to the solid content component in a coating liquid.

  As a light source for UV curing treatment (irradiation with active rays), any light source that generates ultraviolet rays can be used without limitation. For example, a low pressure mercury lamp, a medium pressure mercury lamp, a high pressure mercury lamp, an ultrahigh pressure mercury lamp, a carbon arc lamp, a metal halide lamp, a xenon lamp, or the like can be used.

Irradiation conditions vary depending on each lamp, but the irradiation amount of active rays is usually 50 to 1000 mJ / cm ² , preferably 50 to 300 mJ / cm ² .

  Moreover, when irradiating actinic radiation, it is preferable to carry out while applying tension | tensile_strength in the conveyance direction of a film, More preferably, it is performing applying tension | tensile_strength also in the width direction. The tension to be applied is usually 30 to 500 N / m, preferably 30 to 300 N / m. The method for applying tension is not particularly limited, and tension may be applied in the transport direction on the back roll, or tension may be applied in the width direction or biaxial direction by a tenter. Thereby, a film having further excellent flatness can be obtained.

[Base film]
As Sm (the uneven | corrugated average space | interval of a hard-coat layer coating surface) of the base film which concerns on this embodiment, 3-25 micrometers is preferable. Sm is a value measured using an optical interference type surface roughness meter (RST / PLUS, manufactured by WYKO) based on the provisions of JIS B0601: 1994. The arithmetic average roughness Ra of the base film is preferably 2.0 nm to 4.0 nm, more preferably 2.5 nm to 3.5 nm. As a method of controlling Sm of a base film in the said range, it can control by the extending | stretching conditions etc. as described in the manufacturing method of the base film mentioned later.

  The base film is preferably easy to manufacture, easy to adhere to the hard coat layer, and optically isotropic. Moreover, in this embodiment, the hard coat film using a base film is used as a transparent protective film of a polarizing plate.

  The base film that can be used in the present embodiment is not particularly limited as long as it is a film having the above properties, and any film may be used. For example, triacetyl cellulose film (cellulose triacetate film), cellulose acetate propionate film, cellulose diacetate film, cellulose ester film such as cellulose acetate butyrate film, polyester film such as polyethylene terephthalate and polyethylene naphthalate, polycarbonate film, Polyarylate film, polysulfone (including polyethersulfone) film, polyethylene film, polypropylene film, cellophane, polyvinylidene chloride film, polyvinyl alcohol film, ethylene vinyl alcohol film, syndiotactic polystyrene film, norbornene resin film, Polymethylpentene film, Polyer Le ketone film, polyether ketone imide film, a polyamide film, a fluororesin film, a nylon film, cycloolefin polymer films, and polyester films, polymethyl methacrylate film, or an acrylic film.

  Of these, cellulose ester films (for example, Konica Minoltak KC8UX, KC4UX, KC5UX, KC8UCR3, KC8UCR4, KC8UCR5, KC8UY, KC4UE, KC4UE, and KC12UE (above, manufactured by Konica Minolta Opto Cycloolefin), polycarbonate film A polymer film and a polyester film are preferable, and in the present embodiment, a cellulose ester film is particularly preferable from the viewpoint of the effect, productivity, and cost of the present invention. The cellulose ester film will be further described later.

The refractive index of the base film is preferably 1.30 to 1.70, and more preferably 1.40 to 1.65. The refractive index is measured by the method of JIS K7142 using an Atpe refractometer 2T manufactured by Atago. The base film has the following relationship with tan δ measured by changing the temperature from 25 ° C. to 210 ° C. at a humidity of 55% RH in the width direction of the film. It is preferable from the point of exhibiting.
0.5 ≧ (tan δ ₋₄₀ / tan δ _peak ) ≧ 0.24
Here, tan δ _peak is the maximum value obtained by measuring the tan δ value by changing the temperature from 25 ° C. to 210 ° C., and tan δ- ₄₀ is the value of tan δ at a temperature of −40 ° C. when tan δ _peak is indicated.

By making the tan δ in the film width direction of the base film, that is, the balance between the storage elastic modulus and the loss elastic modulus with respect to the temperature within the above range, the object effect of the present invention can be exhibited better. The tan δ was measured, for example, by using a sample that had been conditioned for 24 hours in an atmosphere of 23 ° C. and 55% RH in advance and increasing the temperature under the following conditions at a humidity of 55% RH or setting the temperature.
Measuring device: RSA III manufactured by TI Instruments
Sample: width 5 mm, length 50 mm (gap set to 20 mm)
Measurement conditions: Tensile mode Measurement temperature: 25-210 ° C or -40 ° C
Temperature rising condition: 5 ° C / min
Frequency: 1Hz

(Cellulose ester film)
Next, a cellulose ester film preferable as a substrate film will be described. The cellulose ester resin (hereinafter sometimes simply referred to as cellulose ester), which is the main component of the cellulose ester film, is preferably a lower fatty acid ester of cellulose. The lower fatty acid in the lower fatty acid ester of cellulose means a fatty acid having 6 or less carbon atoms, such as cellulose monoacetate, cellulose diacetate, cellulose triacetate, cellulose propionate, cellulose butyrate, and the like. Mixed fatty acid esters such as cellulose acetate propionate, cellulose acetate butyrate, and cellulose acetate propionate butyrate as described in Japanese Patent No. 45804, Japanese Patent Application Laid-Open No. 08-231761, US Pat. No. 2,319,052, etc. Can be used.

  Among the above descriptions, the lower fatty acid esters of cellulose that are particularly preferably used are cellulose diacetate, cellulose triacetate, and cellulose acetate propionate. These cellulose esters can be used alone or in combination.

  As the cellulose diacetate, those having an average degree of acetylation (bound acetic acid amount) of 51.0 to 56.0% are preferably used. Specifically, it can be synthesized with reference to the method described in JP-A-10-45804. Moreover, as a commercial item, L20, L30, L40, L50 of a Daicel company, Ca398-3, Ca398-6, Ca398-10, Ca398-30, Ca394-60S, etc. of an Eastman Chemical company are mentioned.

  The cellulose triacetate preferably has an average degree of acetylation (bound acetic acid amount) of 54.0 to 62.5%, and more preferably cellulose triacetate having an average degree of acetylation of 58.0 to 62.5%. is there.

  When the average acetylation degree is small, the dimensional change is large, and the polarization degree of the polarizing plate is lowered. When the average acetylation degree is large, the solubility in a solvent is lowered, and the productivity is lowered.

  Cellulose triacetate has an acetyl group substitution degree of 2.80 to 2.95, a number average molecular weight (Mn) of 125,000 or more and less than 155000, a weight average molecular weight (Mw) of 265,000 or more and less than 310,000, Mw / Mn. Triacetate A having a acetyl group substitution degree of 2.75 to 2.90, a number average molecular weight (Mn) of 155,000 or more and less than 180000, and a weight average molecular weight (Mw) of 1.9 to 2.1. It is preferable to contain cellulose triacetate B which is 290000 or more and less than 360,000 and Mw / Mn is 1.8 to 2.0.

  Furthermore, when using cellulose triacetate A and cellulose triacetate B together, it is preferable that the mass ratio is in the range of cellulose triacetate A: cellulose triacetate B = 100: 0 to 20:80.

A preferred cellulose ester other than cellulose triacetate has an acyl group having 2 to 4 carbon atoms as a substituent, the substitution degree of acetyl group is X, and the substitution degree of propionyl group or butyryl group is Y, It is a cellulose ester containing the cellulose ester which satisfy | fills (I) and (II) simultaneously.
Formula (I): 2.6 ≦ X + Y ≦ 3.0
Formula (II): 0 ≦ X ≦ 2.5
In particular, cellulose acetate propionate is preferably used, and among them, 1.9 ≦ X ≦ 2.5 and 0.1 ≦ Y ≦ 0.9 are preferable.

The number average molecular weight (Mn) and the weight average molecular weight (Mw) of the cellulose ester can be measured using high performance liquid chromatography. An example of measurement conditions is as follows.
Solvent: Methylene chloride Column: Shodex K806, K805, K803G (Used by connecting three Showa Denko Co., Ltd.)
Column temperature: 25 ° C
Sample concentration: 0.1% by mass
Detector: RI Model 504 (GL Science Co., Ltd.)
Pump: L6000 (manufactured by Hitachi, Ltd.)
Flow rate: 1.0 ml / min
Calibration curve: Standard polystyrene STK standard polystyrene (manufactured by Tosoh Corp.) Mw = 100000 to 500 calibration curves were used. The 13 samples are preferably used at approximately equal intervals.

  Hereinafter, a cellulose acetate film (that is, a film mainly composed of cellulose monoacetate, cellulose diacetate and / or cellulose triacetate) will be described as an example of the base film. However, the same applies to the case where other films (for example, films mainly composed of cellulose acetate propionate, cellulose acetate butyrate, cellulose acetate propionate butyrate, etc.) are used as the base film. Needless to say.

  In the present embodiment, the cellulose acetate film preferably contains the following sugar ester compound.

  In the present embodiment, the sugar ester compound is a compound obtained by esterifying all or part of the OH group of a sugar such as the following monosaccharide, disaccharide, trisaccharide or oligosaccharide.

  Examples of the sugar include glucose, galactose, mannose, fructose, xylose, arabinose, lactose, sucrose, nystose, 1F-fructosyl nystose, stachyose, maltitol, lactitol, lactulose, cellobiose, maltose, cellotriose, maltotriose, Mention may be made of raffinose and kestose. In addition, gentiobiose, gentiotriose, gentiotetraose, xylotriose, galactosyl sucrose, and the like are also included. Among these compounds, compounds having a furanose structure and / or a pyranose structure are particularly preferable. Among these, sucrose, kestose, nystose, 1F-fructosyl nystose, stachyose and the like are preferable, and sucrose is more preferable. As oligosaccharides, maltooligosaccharides, isomaltooligosaccharides, fructooligosaccharides, galactooligosaccharides, and xylo-oligosaccharides can also be preferably used.

  The monocarboxylic acid used for esterifying the sugar is not particularly limited, and known aliphatic monocarboxylic acid, alicyclic monocarboxylic acid, aromatic monocarboxylic acid and the like can be used. The carboxylic acid to be used may be one kind or a mixture of two or more kinds.

  Preferred aliphatic monocarboxylic acids include acetic acid, propionic acid, butyric acid, isobutyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, 2-ethyl-hexanecarboxylic acid, undecylic acid, lauric acid , Saturated fatty acids such as tridecylic acid, myristic acid, pentadecylic acid, palmitic acid, heptadecylic acid, stearic acid, nonadecanoic acid, arachidic acid, behenic acid, lignoceric acid, serotic acid, heptacosanoic acid, montanic acid, melicic acid, and laccelic acid And unsaturated fatty acids such as undecylenic acid, oleic acid, sorbic acid, linoleic acid, linolenic acid, arachidonic acid and octenoic acid.

  Examples of preferred alicyclic monocarboxylic acids include cyclopentane carboxylic acid, cyclohexane carboxylic acid, cyclooctane carboxylic acid, or derivatives thereof.

  Examples of preferred aromatic monocarboxylic acids include benzoic acid, aromatic monocarboxylic acids having an alkyl group or alkoxy group introduced into the benzene ring of benzoic acid, cinnamic acid, benzylic acid, biphenylcarboxylic acid, naphthalenecarboxylic acid, tetralin Examples thereof include aromatic monocarboxylic acids having two or more benzene rings such as carboxylic acids, or derivatives thereof. More specifically, xylic acid, hemelic acid, mesitylene acid, prenicylic acid, γ-isoduric acid, duryl acid, mesitonic acid, α-isoduryl acid, cumic acid, α-toluic acid, hydroatropic acid, atropic acid, hydrocinnamic Acid, salicylic acid, o-, m-, p-anisic acid, creosote acid, o-, m-, p-homosalicylic acid, o-pyrocatechuic acid, β-resorcylic acid, vanillic acid, isovanillic acid, veratric acid, o -Veratrmic acid, gallic acid, asaronic acid, mandelic acid, homoanisic acid, homovanillic acid, homobellatrumic acid, o-homobellatrumic acid, phthalonic acid, p-coumaric acid and the like can be mentioned. Benzoic acid is particularly preferable.

Among the ester compounds esterified, an acetyl compound into which an acetyl group has been introduced by esterification is preferable. That is, in this embodiment, the sugar ester compound is a sugar in which a part or all of the OH groups of sugars such as monosaccharides, disaccharides, trisaccharides and oligosaccharides are substituted with acetyl groups (CH ₃ CO—). Ester compounds are preferred.

  Although the specific example (compound 1-compound 13) of the sugar ester compound which can be used in this embodiment below is shown, it is not limited to these.

(Compound 1)

(Compound 2)

(Compound 3)

(Compound 4)

(Compound 5)

(Compound 6)

(Compound 7)

(Compound 8)

(Compound 9)

(Compound 10)

(Compound 11)

(Compound 12)

(Compound 13)

  Furthermore, as the sugar ester compound, a compound represented by the following general formula (1) is preferable from the viewpoint of satisfactorily exerting the effects of the present embodiment. Next, the compound represented by the general formula (1) will be described.

（式中、Ｒ_１〜Ｒ_８は、置換又は無置換のアルキルカルボニル基、或いは、置換又は無置換のアリールカルボニル基を表し、Ｒ_１〜Ｒ_８は、同じであっても、異なっていてもよい。） (General formula (1))

(In the formula, R _{1 to} R ₈ represent a substituted or unsubstituted alkylcarbonyl group or a substituted or unsubstituted arylcarbonyl group, and R _{1 to} R ₈ may be the same or different. Good.)

  First, although the compound shown by General formula (1) is shown to a more specific (compound 1-1-compound 1-23), it is not limited to these.

  The compound represented by the general formula (1) can be obtained, for example, by the following method.

A four-headed colben equipped with a stirrer, a reflux condenser, a thermometer, and a nitrogen gas inlet tube was mixed with 34.2 g (0.1 mol) of sucrose, 180.8 g (0.8 mol) of benzoic anhydride, 379. 7 g (4.8 mol) is charged, and the temperature is raised while bubbling nitrogen gas from a nitrogen gas introduction tube with stirring, and an esterification reaction is carried out at 70 ° C. for 5 hours. Next, the inside of the Kolben was depressurized to 4 × 10 ² Pa or less, and after excess pyridine was distilled off at 60 ° C., the inside of the Kolben was depressurized to 1.3 × 10 Pa or less and the temperature was raised to 120 ° C. Most of the acid and benzoic acid formed are distilled off. Then, 1 L of toluene and 300 g of a 0.5% by mass aqueous sodium carbonate solution are added, and the mixture is stirred at 50 ° C. for 30 minutes and then allowed to stand to separate the toluene layer. Finally, 100 g of water was added to the collected toluene layer, and after washing with water at room temperature for 30 minutes, the toluene layer was collected, and toluene was distilled off at 60 ° C. under reduced pressure (4 × 10 ² Pa or less). A mixture of the following exemplary compounds A-1, A-2, A-3, A-4 and A-5 is obtained.

  When the actually obtained mixture was analyzed by HPLC and LC-MASS, A-1 was 7% by mass, A-2 was 58% by mass, A-3 was 23% by mass, A-4 was 9% by mass, A- 5 was 3 mass%. Further, the obtained mixture is purified by column chromatography using silica gel to obtain exemplary compounds A-1, A-2, A-3, A-4 and A-5 having a purity of 100%, respectively. Can do.

  Among the compounds represented by the general formula (1), the total average substitution degree (indicated as “average substitution degree” in the examples of the specific compounds (compound 1-1 to compound 1-23)) is 6.1. The compound of -6.9 is preferable from the point which exhibits the effect of this embodiment better also on severer conditions. In the synthesis example shown above, the substitution degree distribution can be adjusted to the target substitution degree by adjusting the esterification reaction time or mixing compounds having different substitution degrees.

  As content of the sugar ester compound in the cellulose acetate film which concerns on this embodiment, for example, the sugar ester compound which consists of a monosaccharide or an oligosaccharide is contained with respect to cellulose acetate with an acetylation degree of 51.0%-56.0%. When making it, it is preferable to contain 1-30 mass% of sugar ester compounds, it is more preferable to contain 5-25 mass%, and it is more preferable to contain 5-20 mass%.

  In the present embodiment, the cellulose acetate film may contain an ester compound represented by the following general formula (2) from the viewpoint of satisfactorily exhibiting dimensional stability under environmental changes.

(General formula (2))
B- (GA) n-GB
(In the formula, B is a hydroxy group or a carboxylic acid residue, G is an alkylene glycol residue having 2 to 12 carbon atoms, an aryl glycol residue having 6 to 12 carbon atoms, or an oxy having 4 to 12 carbon atoms. An alkylene glycol residue, A represents an alkylene dicarboxylic acid residue having 4 to 12 carbon atoms or an aryl dicarboxylic acid residue having 6 to 12 carbon atoms, and n represents an integer of 1 or more.)

  In the ester compound represented by the general formula (2), examples of the alkylene glycol component having 2 to 12 carbon atoms include ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, and 1,2-butanediol. 1,3-butanediol, 1,2-propanediol, 2-methyl-1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 2,2-dimethyl-1,3- Propanediol (neopentyl glycol), 2,2-diethyl-1,3-propanediol (3,3-dimethylolpentane), 2-n-butyl-2-ethyl-1,3-propanediol (3,3 -Dimethylolheptane), 3-methyl-1,5-pentanediol, 1,6-hexanediol, 2,2,4-trimethyl 1,3-pentanediol, 2-ethyl-1,3-hexanediol, 2-methyl-1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,12-dodecanediol, etc. These glycols can be used as one kind or a mixture of two or more kinds.

  These alkylene glycols having 2 to 12 carbon atoms are particularly preferable because of their excellent compatibility with cellulose acetate.

  In the ester compound represented by the general formula (2), examples of the aryl glycol component having 6 to 12 carbon atoms include hydroquinone, resorcin, bisphenol A, bisphenol F, bisphenol S, and the like. Or it can be used as a mixture of two or more.

  In the ester compound represented by the general formula (2), examples of the oxyalkylene glycol component having 4 to 12 carbon atoms include diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, and tripropylene glycol. These glycols can be used as one or a mixture of two or more.

  In the ester compound represented by the general formula (2), examples of the alkylene dicarboxylic acid component having 4 to 12 carbon atoms include succinic acid, maleic acid, fumaric acid, glutaric acid, adipic acid, azelaic acid, sebacic acid, and dodecane. There exist dicarboxylic acid etc., and these can be used as a 1 type, or 2 or more types of mixture.

  In the ester compound represented by the general formula (2), the aryl dicarboxylic acid component having 6 to 12 carbon atoms includes phthalic acid, terephthalic acid, isophthalic acid, 1,5-naphthalenedicarboxylic acid, and 1,4-naphthalenedicarboxylic acid. Etc.

  Although the specific example (ester compound 2-1 to 2-23) of the ester compound shown by General formula (2) below is shown, it is not limited to these.

  As content of the ester compound shown by General formula (2) in the cellulose acetate film which concerns on this embodiment, 1-50 mass% of ester compounds shown by General formula (2) are contained with respect to a cellulose acetate, for example. The content is preferably 5 to 35% by mass, more preferably 5 to 25% by mass.

(Other additives)
<Plasticizer>
The cellulose acetate film according to the present embodiment may contain a plasticizer as necessary.

  The plasticizer that can be used is not particularly limited, but polyvalent carboxylate plasticizer, glycolate plasticizer, phthalate ester plasticizer, fatty acid ester plasticizer, and polyhydric alcohol ester plasticizer, ester. And plasticizers such as acrylic plasticizers and acrylic plasticizers.

  The polyhydric alcohol ester plasticizer is a plasticizer comprising an ester of a divalent or higher aliphatic polyhydric alcohol and a monocarboxylic acid, and preferably has an aromatic ring or a cycloalkyl ring in the molecule. Preferably it is a 2-20 valent aliphatic polyhydric alcohol ester. Although the specific examples 1-35 of a polyhydric alcohol ester plasticizer are shown below, it is not limited to these.

  The glycolate plasticizer is not particularly limited, but alkylphthalylalkyl glycolates can be preferably used. Examples of alkyl phthalyl alkyl glycolates include methyl phthalyl methyl glycolate, ethyl phthalyl ethyl glycolate, propyl phthalyl propyl glycolate, butyl phthalyl butyl glycolate, octyl phthalyl octyl glycolate, methyl phthalyl ethyl Glycolate, ethyl phthalyl methyl glycolate, ethyl phthalyl propyl glycolate, methyl phthalyl butyl glycolate, ethyl phthalyl butyl glycolate, butyl phthalyl methyl glycolate, butyl phthalyl ethyl glycolate, propyl phthalyl butyl glycol Butyl phthalyl propyl glycolate, methyl phthalyl octyl glycolate, ethyl phthalyl octyl glycolate, octyl phthalyl methyl glycolate, octyl phthalate Ethyl glycolate, and the like.

  Examples of the phthalate ester plasticizer include diethyl phthalate, dimethoxyethyl phthalate, dimethyl phthalate, dioctyl phthalate, dibutyl phthalate, di-2-ethylhexyl phthalate, dioctyl phthalate, dicyclohexyl phthalate, and dicyclohexyl terephthalate.

  Examples of the citrate plasticizer include acetyl trimethyl citrate, acetyl triethyl citrate, and acetyl tributyl citrate.

  Examples of fatty acid ester plasticizers include butyl oleate, methylacetyl ricinoleate, and dibutyl sebacate.

  Examples of the phosphate ester plasticizer include triphenyl phosphate, tricresyl phosphate, cresyl diphenyl phosphate, octyl diphenyl phosphate, diphenyl biphenyl phosphate, trioctyl phosphate, tributyl phosphate and the like.

  The polyvalent carboxylic acid ester plasticizer is a compound composed of an ester of a divalent or higher, preferably a divalent to 20 valent polyvalent carboxylic acid and an alcohol.

  Specific examples of polyvalent carboxylic acid ester plasticizers include triethyl citrate, tributyl citrate, acetyl triethyl citrate (ATEC), acetyl tributyl citrate (ATBC), benzoyl tributyl citrate, acetyl triphenyl citrate, acetyl Examples include, but are not limited to, tribenzyl citrate, dibutyl tartrate, diacetyl dibutyl tartrate, tributyl trimellitic acid, tetrabutyl pyromellitic acid, and the like.

  In addition, when the plasticizer as described above is contained in the cellulose acetate film according to the present embodiment, the amount used is not uniform depending on the type of plasticizer, usage conditions, etc. About 50% by mass is preferably contained, and more preferably about 5 to 35% by mass.

<Ultraviolet absorber>
The cellulose acetate film which concerns on this embodiment may contain the ultraviolet absorber which is used for the hard-coat layer mentioned above.

  The ultraviolet absorber is added by dissolving the ultraviolet absorber in an alcohol, such as methanol, ethanol, butanol or the like, an organic solvent such as methylene chloride, methyl acetate, acetone, dioxolane, or a mixed solvent thereof, and then becomes a film substrate. It may be added to the resin solution (dope) or directly during the dope composition.

  For an inorganic powder that does not dissolve in an organic solvent, a dissolver or a sand mill is used in the organic solvent and cellulose acetate to disperse and then added to the dope.

  The amount of the UV absorber used is not uniform depending on the type of UV absorber, the use conditions, etc., but when the hard coat film has a dry film thickness of 30 to 200 μm, it is 0.5 to 10 with respect to the hard coat film. % By mass is preferable, and 0.6 to 4% by mass is more preferable.

<Antioxidant>
The cellulose acetate film in this embodiment may further contain an antioxidant (also referred to as a deterioration preventing agent).

  When a liquid crystal image display device or the like is placed in a high humidity and high temperature state, the cellulose acetate film may be deteriorated. The antioxidant has a role of delaying or preventing the cellulose acetate film from being decomposed by, for example, a residual solvent amount of halogen in the cellulose acetate film or phosphoric acid of a phosphoric acid plasticizer.

  As such an antioxidant, a hindered phenol compound is preferably used. For example, 2,6-di-t-butyl-p-cresol, pentaerythrityl-tetrakis [3- (3,5-di- -T-butyl-4-hydroxyphenyl) propionate], triethylene glycol-bis [3- (3-t-butyl-5-methyl-4-hydroxyphenyl) propionate], 1,6-hexanediol-bis [3 -(3,5-di-t-butyl-4-hydroxyphenyl) propionate], 2,4-bis- (n-octylthio) -6- (4-hydroxy-3,5-di-t-butylanilino)- 1,3,5-triazine, 2,2-thio-diethylenebis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], octa Sil-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate, N, N'-hexamethylenebis (3,5-di-t-butyl-4-hydroxy-hydrocinnamamide) 1,3,5-trimethyl-2,4,6-tris (3,5-di-t-butyl-4-hydroxybenzyl) benzene, tris- (3,5-di-t-butyl-4-hydroxy Benzyl) -isocyanurate and the like.

  In particular, 2,6-di-t-butyl-p-cresol, pentaerythrityl-tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], triethylene glycol-bis [3 -(3-t-butyl-5-methyl-4-hydroxyphenyl) propionate] is preferred. Further, for example, hydrazine-based metal deactivators such as N, N′-bis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyl] hydrazine and tris (2,4-di- A phosphorus processing stabilizer such as t-butylphenyl) phosphite may be used in combination.

  The addition amount of these compounds is preferably 1 ppm to 10000 ppm, more preferably 10 to 1000 ppm by mass ratio with respect to the cellulose acetate film.

<Fine particles>
In order to improve the handleability, the cellulose acetate film according to the present embodiment has, for example, silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, kaolin, talc, calcined calcium silicate, hydrated calcium silicate, silica It is preferable to contain matting agents such as inorganic fine particles such as aluminum oxide, magnesium silicate, and calcium phosphate, and a crosslinked polymer. Among these, silicon dioxide is preferably used because it can reduce the haze of the cellulose acetate film.

  The primary average particle diameter of the fine particles is preferably 20 nm or less, more preferably 5 to 16 nm, and particularly preferably 5 to 12 nm.

  These fine particles preferably form secondary particles having a particle size of 0.1 to 5 μm and are contained in the cellulose acetate film, and the more preferable average particle size is 0.1 to 2 μm, particularly preferably 0.2. ~ 0.6 μm. Thereby, the unevenness | corrugation about 0.1-1.0 micrometer high can be formed in the film surface, and this can give appropriate slipperiness to the film surface. The primary average particle diameter of the fine particles is measured by observing the particles with a transmission electron microscope (magnification of 500,000 to 2,000,000 times), observing 100 particles, measuring the particle diameter, and using the average value to obtain the primary value. The average particle size was taken.

  The apparent specific gravity of the fine particles is preferably 70 g / liter or more, more preferably 90 to 200 g / liter, and particularly preferably 100 to 200 g / liter. A higher apparent specific gravity is preferable because a high-concentration dispersion can be produced, and haze and aggregates are improved.

  Silicon dioxide, which is a fine particle preferably used in the present embodiment, is commercially available under the trade names of, for example, Aerosil 200V and Aerosil R972V (manufactured by Nippon Aerosil Co., Ltd.), and these can be used.

The apparent specific gravity described above is calculated by the following formula by measuring a weight of silicon dioxide fine particles in a graduated cylinder and measuring the weight at that time.
Apparent specific gravity (g / liter) = silicon dioxide mass (g) / volume of silicon dioxide (liter)

  Next, a method for dispersing fine particles will be described using silicon dioxide as an example. The concentration of silicon dioxide when the silicon dioxide fine particles are mixed with a solvent and dispersed is preferably 5% by mass to 30% by mass, more preferably 10% by mass to 25% by mass, and most preferably 15% by mass to 20% by mass. A higher dispersion concentration is preferable because liquid turbidity with respect to the added amount tends to be low, and haze and aggregates are improved.

  Examples of the solvent used include lower alcohols, and preferred specific examples include methyl alcohol, ethyl alcohol, propyl alcohol, isopropyl alcohol, butyl alcohol and the like. Although it does not specifically limit as solvents other than a lower alcohol, It is preferable to use the same kind of solvent as the solvent used at the time of film formation of a cellulose acetate.

  The amount of fine particles added to the cellulose acetate film varies depending on the type of fine particles. For example, when silicon dioxide is taken as an example, the silicon dioxide fine particles are preferably 0.01 to 5.0% by mass with respect to cellulose acetate. 0.05-1.0 mass% is still more preferable, and 0.1-0.5 mass% is the most preferable. When the addition amount is large, the coefficient of dynamic friction is excellent, and when the addition amount is small, aggregates are reduced.

  For dispersion of the fine particles, a normal disperser such as a ball mill or a sand mill can be used. In addition, casting a dope containing fine particles so as to be in direct contact with the casting support is preferable because a film having high slip properties and low haze can be obtained.

In the cellulose acetate film, the total amount of calcium and magnesium and the amount of acetic acid preferably satisfy the following relational expression (a).
Relational expression (a): 1 ≦ (acetic acid amount) / (total amount of calcium and magnesium) ≦ 30

  Calcium and magnesium are contained in cellulose, which is a raw material for cellulose acetate film, but neutralize and stabilize the acid catalyst (especially sulfuric acid) added to the cellulose production process. It may be added as a metal salt (inorganic acid salt, organic acid salt). Moreover, you may add as a metal oxide, a metal hydroxide, and a metal salt (inorganic acid salt, organic acid salt) at the time of film formation of a cellulose acetate film. The total amount of calcium and magnesium refers to their total amount. The amount of acetic acid refers to the total amount of residual acetic acid and free acetic acid.

  After casting, the film is peeled off, dried and wound into a roll, and then a functional thin film of a hard coat layer is provided. Until processing or shipment, packaging is usually performed in order to protect the product from dirt, static electricity, and the like.

  The packaging material is not particularly limited as long as the above purpose can be achieved, but a material that does not hinder volatilization of the residual solvent from the film is preferable. Specific examples include polyethylene, polyester, polypropylene, nylon, polystyrene, paper, various non-woven fabrics, and the like. Those in which the fibers are mesh cloth are more preferably used.

(Manufacturing method of base film)
Next, the manufacturing method of the base film which concerns on this embodiment is demonstrated taking the manufacturing method of a cellulose acetate film as an example.

  The cellulose acetate film according to this embodiment can be preferably used regardless of whether it is a film produced by a solution casting method or a film produced by a melt casting method.

  The production by the solution casting method includes a step of preparing a dope by dissolving cellulose acetate and an additive in a solvent, a step of casting the dope on an endless metal support that moves infinitely, a web of the cast dope As a drying process, a peeling process from a metal support, a stretching or width holding process, a further drying process, and a winding process of a finished film.

  The process for preparing the dope will be described. The concentration of cellulose acetate in the dope is preferably higher because the drying load after casting on the metal support can be reduced. However, if the concentration of cellulose acetate is too high, the load during filtration increases and the filtration accuracy is poor. Become. As a density | concentration which makes these compatible, 10-35 mass% is preferable, More preferably, it is 15-25 mass%.

  The solvent used in the dope may be used alone or in combination of two or more. However, it is preferable to use a mixture of a good solvent and a poor solvent of cellulose acetate in terms of production efficiency, and there are many good solvents. This is preferable from the viewpoint of solubility of cellulose acetate.

  The preferable range of the mixing ratio of the good solvent and the poor solvent is 70 to 98% by mass for the good solvent and 2 to 30% by mass for the poor solvent. With a good solvent and a poor solvent, what dissolve | melts the cellulose acetate to be used independently is defined as a good solvent, and what swells or does not melt | dissolve independently is defined as a poor solvent.

  Therefore, the good solvent and the poor solvent change depending on the average acetylation degree (acetyl group substitution degree) of cellulose acetate.

  The good solvent is not particularly limited, and examples thereof include organic halogen compounds such as methylene chloride, dioxolanes, acetone, methyl acetate, and methyl acetoacetate. Particularly preferred is methylene chloride or methyl acetate.

  Although it does not specifically limit as a poor solvent, For example, methanol, ethanol, n-butanol, a cyclohexane, cyclohexanone etc. are used preferably. Moreover, it is preferable that 0.01-2 mass% of water contains in dope.

  Moreover, the solvent used for melt | dissolution of a cellulose acetate collect | recovers the solvent removed from the film by drying at the film-forming process, and uses this again.

  The recovery solvent may contain trace amounts of additives added to cellulose acetate, such as plasticizers, UV absorbers, polymers, monomer components, etc., but these are preferably reused even if they are included. Can be purified and reused if necessary.

  As a method for dissolving cellulose acetate when preparing the dope described above, a general method can be used. When heating and pressurization are combined, it is possible to heat above the boiling point at normal pressure.

  It is preferable to stir and dissolve while heating at a temperature that is equal to or higher than the boiling point of the solvent at normal pressure and does not boil under pressure, in order to prevent the formation of massive undissolved materials called gels and mamacos.

  Further, a method in which cellulose acetate is mixed with a poor solvent and wetted or swollen, and then a good solvent is added and dissolved is also preferably used.

  The pressurization may be performed by a method of injecting an inert gas such as nitrogen gas or a method of increasing the vapor pressure of the solvent by heating. Heating is preferably performed from the outside. For example, a jacket type is preferable because temperature control is easy.

  A higher heating temperature with the addition of a solvent is preferable from the viewpoint of solubility of cellulose acetate, but if the heating temperature is too high, the required pressure increases and the productivity deteriorates.

  A preferable heating temperature is 45 to 120 ° C, more preferably 60 to 110 ° C, and still more preferably 70 ° C to 105 ° C. The pressure is adjusted so that the solvent does not boil at the set temperature.

  Alternatively, a cooling dissolution method is also preferably used, whereby cellulose acetate can be dissolved in a solvent such as methyl acetate.

  Next, this cellulose acetate solution is filtered using a suitable filter medium such as filter paper. As the filter medium, it is preferable that the absolute filtration accuracy is small in order to remove insoluble matters and the like, but there is a problem that the filter medium is likely to be clogged if the absolute filtration accuracy is too small.

  For this reason, a filter medium with an absolute filtration accuracy of 0.008 mm or less is preferable, a filter medium with 0.001 to 0.008 mm is more preferable, and a filter medium with 0.003 to 0.006 mm is still more preferable. There are no particular restrictions on the material of the filter medium, and ordinary filter media can be used. However, plastic filter media such as polypropylene and Teflon (registered trademark), and metal filter media such as stainless steel do not drop off fibers. preferable. It is preferable to remove and reduce impurities, particularly bright spot foreign matter, contained in the raw material cellulose acetate by filtration.

Bright spot foreign matter means that when two polarizing plates are placed in a crossed Nicol state, an optical film or the like is placed between them, light is applied from one polarizing plate side, and observation is performed from the other polarizing plate side. It is a point (foreign matter) where light from the opposite side appears to leak, and the number of bright spots having a diameter of 0.01 mm or more is preferably 200 / cm ² or less.

More preferably, it is 100 pieces / cm < ² > or less, More preferably, it is 50 pieces / cm < ² > or less, More preferably, it is 0-10 pieces / cm < ² > or less. Further, it is preferable that the number of bright spots of 0.01 mm or less is small.

  The dope can be filtered by a normal method, but the method of filtering while heating at a temperature not lower than the boiling point of the solvent at normal pressure and in a range where the solvent does not boil under pressure is the filtration pressure before and after filtration. The increase in the difference (referred to as differential pressure) is small and preferable.

  A preferred temperature is 45 to 120 ° C, more preferably 45 to 70 ° C, and still more preferably 45 to 55 ° C.

  A smaller filtration pressure is preferred. The filtration pressure is preferably 1.6 MPa or less, more preferably 1.2 MPa or less, and further preferably 1.0 MPa or less.

  Here, the dope casting will be described. The metal support in the casting (casting) step preferably has a mirror-finished surface. As the metal support, a stainless steel belt or a drum whose surface is plated with a casting is preferably used.

  The cast width can be 1 to 4 m. The surface temperature of the metal support in the casting step is −50 ° C. to a temperature lower than the boiling point of the solvent, and a higher temperature is preferable because the drying speed of the web can be increased. May deteriorate.

  A preferable support temperature is 0 to 55 ° C, and more preferably 25 to 50 ° C. Alternatively, it is also a preferable method that the web is gelled by cooling and peeled from the drum in a state containing a large amount of residual solvent.

  The method for controlling the temperature of the metal support is not particularly limited, and there are a method of blowing hot air or cold air, and a method of contacting hot water with the back side of the metal support. It is preferable to use warm water because heat transfer is performed efficiently, so that the time until the temperature of the metal support becomes constant is short. When warm air is used, wind at a temperature higher than the target temperature may be used.

  In order for the cellulose acetate film to exhibit good flatness, the residual solvent amount when peeling the web from the metal support is preferably 10 to 150% by mass, more preferably 20 to 40% by mass or 60 to 130% by mass. Especially preferably, it is 20-30 mass% or 70-120 mass%.

The amount of residual solvent is defined by the following formula.
Residual solvent amount (% by mass) = {(MN) / N} × 100
M is the mass of a sample collected during or after the production of the web or film, and N is the mass after heating M at 115 ° C. for 1 hour.

  Moreover, in the drying step of the cellulose acetate film, the web is peeled off from the metal support, and further dried, and the residual solvent amount is preferably 1% by mass or less, more preferably 0.1% by mass or less, Especially preferably, it is 0-0.01 mass% or less.

  In casting, co-casting can be used, and the cellulose acetate film according to this embodiment may be a film laminated in two or more layers by a production method such as co-casting.

  In the film drying step, generally, a roll drying method (a method in which webs are alternately passed through a plurality of rolls arranged above and below) and a method in which the web is dried while being conveyed by a tenter method are employed.

  Furthermore, in order to produce the cellulose acetate film according to the present embodiment, stretching is performed in the width direction (lateral direction) as described later in a tenter method in which both ends of the web are gripped with clips or the like. Peeling is preferably performed at a peeling tension of 300 N / m or less.

  The means for drying the web is not particularly limited, and can be generally performed with hot air, infrared rays, a heating roll, microwave, or the like, but it is preferably performed with hot air in terms of simplicity. The drying temperature in the web drying step is preferably increased stepwise from 40 to 200 ° C.

  Although the film thickness of a cellulose acetate film is not specifically limited, 10-200 micrometers is used. In particular, the film thickness is particularly preferably 10 to 100 μm. More preferably, it is 20-60 micrometers.

  A cellulose acetate film having a width of 1 to 4 m is used. In particular, those having a width of 1.4 to 4 m are preferably used, and particularly preferably 1.6 to 3 m. If it exceeds 4 m, conveyance becomes difficult.

  The cellulose acetate film can be biaxially or uniaxially stretched sequentially or simultaneously in the longitudinal direction (film forming direction) and in the direction perpendicular to the film plane, that is, the width direction. The stretching ratio in the biaxial direction is preferably 0.8 to 1.5 times in the longitudinal direction and 1.1 to 2.5 times in the width direction, and 0.8 to 1.0 times in the longitudinal direction. More preferably, it is performed in the range of 1.1 to 2.0 times in the width direction.

  The stretching temperature is preferably 120 ° C. to 200 ° C., more preferably 150 ° C. to 200 ° C., and more preferably 150 ° C. to 190 ° C. or less. The residual solvent in the film is preferably 20 to 0%, more preferably 15 to 0%. More specifically, it is preferable that the residual solvent is stretched by 11% at 155 ° C., or the residual solvent is stretched by 2% at 155 ° C. Alternatively, it is preferable that the residual solvent is stretched at 11% at 160 ° C, or the residual solvent is stretched at less than 1% at 160 ° C.

  By stretching the film within the above range, Sm of the base film can be controlled to 3 to 25 μm.

  There is no particular limitation on the method of stretching the web. For example, a method in which a difference in peripheral speed is applied to a plurality of rolls, and the roll peripheral speed difference is used to stretch in the longitudinal direction, the both ends of the web are fixed with clips and pins, and the interval between the clips and pins is increased in the traveling direction. And a method of stretching in the vertical direction, a method of stretching in the horizontal direction and stretching in the horizontal direction, a method of stretching in the vertical and horizontal directions and stretching in both the vertical and horizontal directions, and the like. Of course, these methods may be used in combination.

  In the case of the so-called tenter method, driving the clip portion by the linear drive method is preferable because smooth stretching can be performed and the risk of breakage and the like can be reduced.

  These width maintenance or lateral stretching in the film forming process is preferably performed by a tenter, and may be a pin tenter or a clip tenter.

(Physical properties of base film)
The substrate film has a slow axis or a fast axis in the film plane, and θ1 is preferably −1 ° or more and + 1 ° or less, assuming that the angle formed with the film forming direction is θ1, It is more preferable that the angle is not less than ° and not more than + 0.5 °.

  This θ1 can be defined as an orientation angle, and θ1 can be measured using an automatic birefringence meter KOBRA-21ADH (Oji Scientific Instruments). Each of θ1 satisfying the above relationship can contribute to obtaining high luminance in a display image, suppressing or preventing light leakage, and contributing to obtaining faithful color reproduction in a liquid crystal display device.

Further, the moisture permeability of the base film, 40 ° C., preferably 300~1800g ^/ m 2 · 24h at 90% RH, further 400~1500g ^/ m 2 · 24h are preferred, 40~1300g ^/ m 2 · 24h is particularly preferable. The moisture permeability can be measured according to the method described in JIS Z 0208.

  The base film according to this embodiment preferably has a breaking elongation of 10 to 80%, and more preferably 20 to 50%.

  The substrate film according to this embodiment preferably has a visible light transmittance of 90% or more, and more preferably 93% or more.

  The haze of the substrate film according to the present embodiment is preferably less than 1% and particularly preferably 0 to 0.1% per film.

  Moreover, you may obtain the retardation value over a still wider range by apply | coating a liquid-crystal layer further to a base film.

[Functional layer]
In the hard coat film of the present embodiment, functional layers such as a back coat layer, an antireflection layer, and an antiglare layer can be provided in addition to the hard coat layer.

(Back coat layer)
In the hard coat film according to this embodiment, a back coat layer may be provided on the surface of the base film opposite to the side on which the hard coat layer is provided in order to prevent curling and blocking.

  In terms of curling and blocking prevention, the back coat layer includes silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, calcium carbonate, talc, clay, calcined kaolin, calcined calcium silicate, tin oxide, indium oxide, Particles such as zinc oxide, ITO, hydrated calcium silicate, aluminum silicate, magnesium silicate and calcium phosphate can be added.

  The particles contained in the backcoat layer are preferably 0.1 to 50% by mass with respect to the binder. When the back coat layer is provided, the increase in haze is preferably 0.5% or less, and particularly preferably 0.1% or less. As the binder, a cellulose ester resin is preferable. The coating composition for forming the backcoat layer preferably contains a solvent for alcohols, ketones and / or acetate ester sugars.

(Antireflection layer)
The hard coat film according to this embodiment can also be used as an antireflection film having an antireflection function for external light by coating an antireflection layer on the hard coat layer.

  The antireflection layer is preferably laminated in consideration of the refractive index, the film thickness, the number of layers, the layer order, and the like so that the reflectance is reduced by optical interference. The antireflection layer is composed of a low refractive index layer having a lower refractive index than the protective film as the support, or a combination of a high refractive index layer and a low refractive index layer having a higher refractive index than the protective film as the support. Preferably it is. Particularly preferably, it is an antireflection layer composed of three or more refractive index layers, and three layers having different refractive indexes from the support side are divided into medium refractive index layers (high refractive index layers having a higher refractive index than the support). Are preferably laminated in the order of a layer having a lower refractive index) / a high refractive index layer / a low refractive index layer. Alternatively, an antireflection layer having a layer structure of four or more layers in which two or more high refractive index layers and two or more low refractive index layers are alternately laminated is also preferably used.

As the layer structure of the antireflection film, the following structure is conceivable, but is not limited thereto.
Cellulose acetate film / hard coat layer / low refractive index layer Cellulose acetate film / hard coat layer / medium refractive index layer / low refractive index layer Cellulose acetate film / hard coat layer / medium refractive index layer / high refractive index layer / low refractive index Layer Cellulose acetate film / hard coat layer / high refractive index layer (conductive layer) / low refractive index layer Cellulose acetate film / hard coat layer / antiglare layer / low refractive index layer

(Low refractive index layer)
The low refractive index layer preferably contains silica-based fine particles, and the refractive index is preferably in the range of 1.30 to 1.45 when measured at 23 ° C. and a wavelength of 550 nm.

  The film thickness of the low refractive index layer is preferably 5 nm to 0.5 μm, more preferably 10 nm to 0.3 μm, and most preferably 30 nm to 0.2 μm.

  The composition for forming a low refractive index layer preferably contains at least one kind of particles having an outer shell layer and porous or hollow inside as silica-based fine particles. In particular, the particles having the outer shell layer and having a porous or hollow interior are preferably hollow silica-based fine particles.

  The composition for forming a low refractive index layer may contain an organosilicon compound represented by the following general formula (OSi-1), a hydrolyzate thereof, or a polycondensate thereof.

(General formula (OSi-1))
Si (OR) ₄

  In the organic silicon compound represented by the general formula, R represents an alkyl group having 1 to 4 carbon atoms. Specifically, tetramethoxysilane, tetraethoxysilane, tetraisopropoxysilane and the like are preferably used.

  In addition, a silane coupling agent, a curing agent, a surfactant and the like may be added as necessary. Moreover, you may contain the compound which has a thermosetting and / or photocurability which mainly contains the fluorine atom which contains a fluorine atom in 35-80 mass%, and contains a crosslinkable or polymeric functional group. Specifically, a fluorine-containing polymer or a fluorine-containing sol-gel compound is used. Examples of the fluorine-containing polymer include hydrolysates and dehydration condensates of perfluoroalkyl group-containing silane compounds (for example, (heptadecafluoro-1,1,2,2-tetrahydrodecyl) triethoxysilane), and fluorine-containing polymers. Examples thereof include a fluorine-containing copolymer having a monomer unit and a crosslinking reactive unit as constituent units. In addition, a silane coupling agent, a curing agent, a surfactant, and the like may be added as necessary.

(High refractive index layer)
The refractive index of the high refractive index layer is preferably adjusted to a refractive index in the range of 1.4 to 2.2 by measuring at 23 ° C. and a wavelength of 550 nm. The thickness of the high refractive index layer is preferably 5 nm to 1 μm, more preferably 10 nm to 0.2 μm, and most preferably 30 nm to 0.1 μm. The means for adjusting the refractive index can be achieved by adding metal oxide fine particles and the like. The metal oxide fine particles used preferably have a refractive index of 1.80 to 2.60, more preferably 1.85 to 2.50.

  The kind of metal oxide fine particles is not particularly limited, and Ti, Zr, Sn, Sb, Cu, Fe, Mn, Pb, Cd, As, Cr, Hg, Zn, Al, Mg, Si, P and S A metal oxide having at least one element selected from the group consisting of Al, In, Sn, Sb, Nb, a halogen element, Ta and the like is doped with a minute amount of atoms. May be. A mixture of these may also be used. In the present embodiment, at least one metal oxide fine particle selected from among zirconium oxide, antimony oxide, tin oxide, zinc oxide, indium-tin oxide (ITO), antimony-doped tin oxide (ATO), and zinc antimonate. It is particularly preferable to use as the main component. In particular, it is preferable to contain zinc antimonate particles.

  The average particle diameter of the primary particles of these metal oxide fine particles is in the range of 10 nm to 200 nm, particularly preferably 10 to 150 nm. The average particle diameter of the metal oxide fine particles can be measured from an electron micrograph taken with a scanning electron microscope (SEM) or the like. You may measure by the particle size distribution meter etc. which utilize a dynamic light scattering method, a static light scattering method, etc. If the particle size is too small, aggregation tends to occur and the dispersibility deteriorates. If the particle size is too large, the haze is remarkably increased. The shape of the metal oxide fine particles is preferably a rice grain shape, a spherical shape, a cubic shape, a spindle shape, a needle shape, or an indefinite shape.

  The metal oxide fine particles may be surface-treated with an organic compound. By modifying the surface of the metal oxide fine particles with an organic compound, the dispersion stability in an organic solvent is improved, the dispersion particle size can be easily controlled, and aggregation and sedimentation over time can be suppressed. . For this reason, the surface modification amount with a preferable organic compound is 0.1 mass%-5 mass% with respect to metal oxide particle, More preferably, it is 0.5 mass%-3 mass%. Examples of the organic compound used for the surface treatment include polyols, alkanolamines, stearic acid, silane coupling agents, and titanate coupling agents. Of these, silane coupling agents are preferred. Two or more kinds of surface treatments may be combined. The high refractive index layer may contain a π-conjugated conductive polymer. The π-conjugated conductive polymer can be used as long as it is an organic polymer having a main chain composed of a π-conjugated system. Examples thereof include polythiophenes, polypyrroles, polyanilines, polyphenylenes, polyacetylenes, polyphenylene vinylenes, polyacenes, polythiophene vinylenes, and copolymers thereof. From the viewpoint of ease of polymerization and stability, polythiophenes, polyanilines, and polyacetylenes are preferable.

  The π-conjugated conductive polymer can provide sufficient conductivity and solubility in a binder resin even if it is not substituted, but in order to further improve conductivity and solubility, an alkyl group, a carboxy group, a sulfo group, an alkoxy group. A functional group such as a group, a hydroxy group, or a cyano group may be introduced.

Moreover, you may contain an ionic compound. The ionic compounds, imidazolium, pyridinium-based, alicyclic amine-based, aliphatic amine, cations and _BF ⁴ aliphatic phosphonium -, PF ₆ ^- inorganic ion system such, _CF 3 SO ₂ ^- , (CF ₃ SO ₂ ) ₂ N ⁻ , CF ₃ CO ₂ ^—, etc. The ratio of the polymer to the binder is preferably 10 to 400 parts by mass of the binder with respect to 100 parts by mass of the polymer, and particularly preferably 100 to 200 parts by mass of the binder with respect to 100 parts by mass of the polymer.

(Anti-glare layer)
The antiglare layer reduces the visibility of the reflected image by blurring the outline of the image reflected on the film surface, and the reflected image is reflected when using an image display device such as a liquid crystal display, an organic EL display, or a plasma display. Specifically, it is a layer that does not bother you, and specifically, the arithmetic average roughness of the layer surface by adding fine particles etc. to the hard coat layer or by pressing the mold to form protrusions on the surface. It is preferable that the layer has a thickness Ra adjusted to 0.1 to 1 μm.

<Polarizing plate>
A polarizing plate using the hard coat film according to this embodiment will be described. As illustrated in FIG. 1, in the present embodiment, the polarizing plate has a configuration in which a hard coat film according to the present embodiment, a polarizing film, and a norbornene polymer film are laminated, and the norbornene polymer film An adhesive layer is formed on the surface. The polarizing plate can be produced by a general method. The polarizing plate according to this embodiment uses the hard coat film as a transparent protective film on at least one surface. Therefore, the polarizing plate using the hard coat film excellent in blocking resistance and clearness is provided.

  For example, a completely saponified polyvinyl alcohol aqueous solution is formed on at least one surface of a polarizing film prepared by subjecting the back side of the hard coat film of the present embodiment to an alkali saponification treatment and immersing and stretching the treated hard coat film in an iodine solution. It is preferable to stick together.

  The other surface may use the hard coat film or the base film described above. KC8UX2MW, KC4UX, KC5UX, KC4UY, KC8UY, KC12UR, KC4UEW, KC8UCR-3, KC8UCR-4, KC8UCR-5, KC4FR-1, KC4FR-2, KC8UE, KC4UE, KC4UE May be used. For other commercially available products, it is preferable to use a ZEONOR film (manufactured by ZEON Corporation) or an ARTON film (manufactured by JSR Corporation). In the example shown in FIG. 1, a norbornene polymer film is used.

  The polarizing film, which is the main component of the polarizing plate, is an element that transmits only light having a polarization plane in a certain direction. A typical polarizing film known at present is a polyvinyl alcohol polarizing film, which is a polyvinyl alcohol film. There are those in which iodine is dyed on a system film and those in which dichroic dye is dyed, but it is not limited to this.

  As the polarizing film, a polyvinyl alcohol aqueous solution is formed and dyed by uniaxially stretching or dyed, or uniaxially stretched after dyeing, and then preferably subjected to a durability treatment with a boron compound. A polarizing film having a thickness of 5 to 30 μm, preferably 8 to 15 μm, is preferably used.

  On the surface of the polarizing film, one side of the hard coat film according to the present embodiment is bonded to form a polarizing plate. It is preferably bonded with an aqueous adhesive mainly composed of completely saponified polyvinyl alcohol or the like.

  The pressure-sensitive adhesive layer used on one side of the film to be bonded to the substrate of the liquid crystal cell is preferably optically transparent and exhibits moderate viscoelasticity and pressure-sensitive adhesive properties. Specific examples of the adhesive layer include adhesives or adhesives such as acrylic copolymers, epoxy resins, polyurethane, silicone polymers, polyethers, butyral resins, polyamide resins, polyvinyl alcohol resins, and synthetic rubbers. A film such as a drying method, a chemical curing method, a thermal curing method, a thermal melting method, a photocuring method, or the like can be formed and cured using a polymer such as the above. Among them, the acrylic copolymer can be preferably used because it is most easy to control the physical properties of the adhesive and is excellent in transparency, weather resistance, durability and the like.

<Liquid crystal display device>
By incorporating the polarizing plate of the present embodiment produced using the hard coat film according to the present embodiment into a display device, it is possible to produce an image display device having various visibility and high durability. The liquid crystal display device according to this embodiment uses the hard coat film or the polarizing plate. Therefore, a liquid crystal display device using a hard coat film excellent in blocking resistance and clearness is provided.

  The hard coat film according to the present embodiment is incorporated in a polarizing plate, and is a reflective type, transmissive type, transflective liquid crystal display device or TN type, STN type, OCB type, HAN type, VA type (PVA type, MVA type), It is preferably used in liquid crystal display devices of various driving systems such as IPS type and OCB type.

  Hereinafter, the present invention will be described in more detail through examples, but the present invention is not limited to these examples.

<Manufacture of hard coat film>
[Hard coat film 1]
(Preparation of base film)
<Preparation of fine particle dispersion>
11 parts by mass of silica fine particles (“Aerosil R972V” from Nippon Aerosil Co., Ltd.) were dispersed in 89 parts by mass of ethanol. For dispersion, first, the mixture was stirred and mixed for 50 minutes using a dissolver, and then dispersed using Manton Gorin. Thereby, a fine particle dispersion was prepared.

<Preparation of fine particle additive solution>
5 parts by mass of the prepared fine particle dispersion was dispersed in 99 parts by mass of methylene chloride. To disperse, first add methylene chloride into a dissolution tank, and slowly add the fine particle dispersion with sufficient stirring, and then disperse using an attritor so that the secondary particles have a predetermined particle size. I did it. The resulting dispersion was filtered using Finemet NF from Nippon Seisen Co., Ltd. This prepared the fine particle addition liquid.

<Preparation of main dope solution>
A main dope solution having the following composition was prepared. First, methylene chloride and ethanol were added to the pressure dissolution tank. Next, cellulose acetate was added to the pressurized dissolution tank containing the solvent while stirring. This was completely dissolved with heating and stirring. Furthermore, an ester compound, an additive, and a fine particle additive solution were added and mixed with stirring. This was designated as Azumi Filter Paper No. The main dope solution was prepared by filtration using 244.
-340 parts by mass of methylene chloride-64 parts by mass of ethanol-100 parts by mass of cellulose acetate (made by Eastman Kodak Co., Ltd.) having a acetylation degree of 55%-6. Ester compound 2-16 represented by the general formula (2) 0 parts by mass, additive (ultraviolet absorber: tinuvin 328) 6.0 parts by mass, fine particle additive 1 part by mass

<Preparation of base film>
Next, using an endless belt casting apparatus, the dope solution was uniformly cast on a stainless steel belt support at a temperature of 33 ° C. and a width of 1500 mm. The temperature of the stainless steel belt was controlled at 30 ° C. On the stainless steel belt support, the solvent was evaporated until the residual solvent amount in the cast (cast) film was 75%, and then peeled off from the stainless steel belt support with a peeling tension of 130 N / m. The peeled cellulose acetate film was stretched 36% in the width direction using a tenter while applying heat at 160 ° C. The residual solvent at the start of stretching was 15%. Next, drying was terminated while the drying zone was conveyed by a number of rolls. The drying temperature was 130 ° C. and the transport tension was 100 N / m. After drying, it was slit to a width of 1.5 m, a knurling process having a width of 10 mm and a height of 10 μm was applied to both ends of the film, wound into a roll, and a cellulose acetate film having a dry film thickness of 40 μm was obtained. The winding length was 5200 m.

(Preparation of hard coat layer composition)
A hard coat layer composition was prepared by stirring and mixing the following materials. The hard coat layer composition was finally filtered using a polypropylene filter having a pore size of 0.4 μm.
・ 100 parts by mass of pentaerythritol tri / tetraacrylate (“NK Ester A-TMM-3L” from Shin-Nakamura Chemical Co., Ltd.) ・ 2 parts by mass of Irgacure 184 (Ciba Japan) ・ Polyether-modified polydimethylsiloxane ("BYK-UV3510" from Big Chemie Japan Co., Ltd.) 1 part by weight, 10 parts by weight of cyclohexanone, 93 parts by weight of methyl ethyl ketone

(Manufacture of hard coat film)
The prepared hard coat layer composition is applied onto the prepared cellulose acetate film (base film) using an extrusion coater, dried at 90 ° C. for 15 seconds, and an oxygen concentration of 1.0% by volume or less. A hard coat layer having a dry film thickness of 5 μm is cured by purging with nitrogen so as to obtain an atmosphere of, using an ultraviolet lamp to cure the coating layer with an irradiance of 100 mW / cm ² and an irradiation amount of 0.25 J / cm ^2. Was wound up to produce a roll-shaped hard coat film.

[Hard coat film 2]
In the production of the hard coat film 1, the hard coat film 2 was produced in the same manner as the production of the hard coat film 1 except that the drying temperature was 95 ° C. and the drying time was 22.5 seconds.

[Hard coat film 3]
In the production of the hard coat film 1, the hard coat film 3 was produced in the same manner as the production of the hard coat film 1 except that the drying temperature was 82 ° C. and the drying time was 7.5 seconds.

[Hard coat film 4]
In the production of the hard coat film 1, the resin of the hard coat film 1 is a mixture of pentaerythritol triacrylate and pentaerythritol tetraacrylate (mass ratio 3: 7) and the drying temperature is 100 ° C. A hard coat film 4 was produced in the same manner as in the production.

[Hard coat film 5]
In the production of the hard coat film 1, the hard coat film 5 was produced in the same manner as in the production of the hard coat film 1 except that the resin of the hard coat layer was dimethylolpropane tetraacrylate and the drying temperature was 105 ° C.

[Hard coat film 6]
In the production of the hard coat film 1, the resin of the hard coat layer was a mixture of pentaerythritol triacrylate and isocyanuric acid EO (ethylene oxide) modified triacrylate (mass ratio 8: 2), and the drying temperature was 110 ° C. A hard coat film 6 was produced in the same manner as in the production of the hard coat film 1.

[Hard coat film 7]
In the production of the hard coat film 1, a hard coat film 7 was produced in the same manner as in the production of the hard coat film 1, except that the drying temperature was 98 ° C.

[Hard coat film 8]
In the production of the hard coat film 1, a hard coat film 8 was produced in the same manner as the production of the hard coat film 1 except that the drying temperature was 81 ° C.

[Hard coat film 9]
In the production of the hard coat film 1, the hard coat film 9 was produced in the same manner as the production of the hard coat film 1 except that the drying temperature was 85 ° C. and the drying time was 5 seconds.

[Hard coat film 10]
In the production of the hard coat film 1, the hard coat film 10 was produced in the same manner as the production of the hard coat film 1 except that the drying temperature was 85 ° C. and the drying time was 25 seconds.

[Hard coat film 11]
In the production of the hard coat film 1, the hard coat film 11 was prepared in the same manner as in the production of the hard coat film 1 except that the resin of the hard coat layer was an acrylic polymer mixture (phase separation resin) and the drying temperature was 85 ° C. Manufactured.

<Evaluation of hard coat film>
[Blocking resistance]
A large number of 5 cm × 5 cm test pieces were cut out from the obtained hard coat film, 10 sheets were stacked so that the base film and the hard coat layer were in contact with each other, and 9.8 × 103 Pa (100 g) in the thickness direction of the film. / Cm ² ), the state after being allowed to stand for 96 hours in an environment of 40 ° C. and 80% was visually observed and evaluated according to the following criteria.
○: Blocking between films was not confirmed ×: Blocking between films was confirmed

[Clearness]
The obtained hard coat film was visually observed under a three-wavelength fluorescent lamp and evaluated according to the following criteria.
○: The film was transparent and clear. ×: The film was low in transparency and clouded.

The evaluation results are shown in Table 1. In Table 1, the resin type refers to the type of resin in the hard coat layer composition, and the drying temperature (° C.) refers to the drying temperature and resin viscosity in the reduced rate drying section of the hard coat layer composition. (MPa · s) is the viscosity of the resin in the hard coat layer composition at the drying temperature, and the resin volume V (cm ³ ) is applied per 1 m ^{2 of the} base film (cellulose acetate film). The volume of the resin in the hard coat layer composition (cm ³ / m ² ) and the drying time t (seconds) are the drying time, the surface roughness (nm) in the rate-decreasing drying section at the drying temperature. There is an arithmetic average roughness Ra of the hard coat layer.

<Consideration of results>
In the decreasing rate drying section, the hard coat layer composition is dried at a drying temperature (° C.) at which the viscosity of the resin in the hard coat layer composition is 3 to 7 mPa · s, and t (seconds) = 1.5 V (cm ³ / m ² ) or more and t (seconds) = 4.5 V (cm ³ / m ² ) or less, the hard coat films 1 to 6 produced by drying are excellent in both blocking resistance and clearness. It was.

  The hard coat films 1 to 3 have a common resin type of pentaerythritol triacrylate. Of these three films, hard coat film 2 has the highest drying temperature (95 ° C.), the longest drying time (22.5 seconds), and therefore the most heat, resulting in the surface of the hard coat layer being The roughness was the largest (Ra was 18 nm), and the result was the most excellent in blocking resistance. The hard coat film 3 has the lowest drying temperature (82 ° C.), the shortest drying time (7.5 seconds), and therefore the least amount of heat. As a result, the hard coat layer has the smallest surface roughness (Ra 4 nm), which is the best result of clearness.

  Although the hard coat films 4 to 6 have a drying temperature (° C.) at which the resin viscosity becomes 3 to 7 mPa · s, which is higher than the hard coat films 1 to 3, the surface roughness of the hard coat layer is the same as the drying time ( 15 seconds), which is smaller than the hard coat film 1 and more excellent in clearness.

  The hard coat films 7 to 10 are the same as the hard coat films 1 to 3 in which the resin type is pentaerythritol triacrylate. However, the hard coat film 7 has a drying temperature that is too high (98 ° C.), the resin viscosity becomes less than 3 mPa · s (2.6 mPa · s), and the surface roughness of the hard coat layer becomes excessively large (Ra 30 nm), the result was inferior in clearness.

  The hard coat film 8 has a drying temperature that is too low (81 ° C.), the resin viscosity exceeds 7 mPa · s (7.2 mPa · s), and the surface roughness of the hard coat layer becomes excessively small (Ra = 1). .5 nm), which is inferior in blocking resistance.

  The hard coat film 9 had a drying time that was too short (5 seconds), and the surface roughness of the hard coat layer was excessively small (Ra was 1 nm), resulting in poor blocking resistance.

  The hard coat film 10 had a drying time that was too long (25 seconds), the surface roughness of the hard coat layer was excessively large (Ra was 25 nm), and the clearness was poor.

The hard coat film 11 was coated with an acrylic copolymer mixture containing a first component and a second component, and the first component acrylic copolymer was precipitated by phase separation, thereby forming fine irregularities on the surface of the film. However, at the recommended drying temperature (85 ° C.), the resin viscosity is less than 3 mPa · s (2.5 mPa · s), the surface roughness of the hard coat layer is excessively large (Ra is 50 nm), and anti-blocking. Although it was excellent in property, it was a result inferior to clearness.

Claims (6)

A method for producing a hard coat film in which a hard coat layer is formed by applying a resin composition on a base film and then drying,
A period for drying the resin composition at a temperature at which the viscosity of the resin in the resin composition applied on the base film is 3 to 7 mPa · s is provided in the drying rate reduction drying section, and the drying The decreasing rate drying section is performed at a temperature at which the viscosity of the resin is 3 mPa · s or more ,
When the length of the period is t seconds and the volume of the resin in the resin composition applied per 1 m ^{2 of the} base film is Vcm ³ / m ² , 1.5V ≦ t ≦ 4.5V The method for producing a hard coat film is characterized in that the length of the period is set.   The method for producing a hard coat film according to claim 1, wherein a hard coat film having an arithmetic average roughness Ra of 2 to 20 nm is produced.   The method for producing a hard coat film according to claim 1 or 2, wherein the resin contained in the resin composition is an actinic radiation curable resin.   The method for producing a hard coat film according to claim 3, wherein the actinic radiation curable resin contains pentaerythritol acrylate.   The method for producing a hard coat film according to claim 1, wherein the base film is a cellulose ester film. The resin composition contains a solvent having a solubility parameter of 18.5 to 21 (MPa) ^1/2 , and the resin: solvent mass ratio in the resin composition is 100: 10 to 100: 50. The manufacturing method of the hard coat film of any one of Claims 1-5 characterized by the above-mentioned.

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