JP6753682B2 - Optical film and its manufacturing method - Google Patents

Description

The present invention relates to an optical film and a method for producing the same.

Optical transparency, optical homogeneity, and smoothness are required for a polarizing element protective film for protecting a polarizer and an optical film represented by a film substrate for a liquid crystal display device. ..
As a method for producing such an optical film, there is known a melt extrusion method in which a resin composition as a raw material for a film is melted by an extruder and extruded into a film from a die to form a film.
When the film thus obtained is used as a product, the film is wound into a roll. However, there is a problem that the films come into contact with each other inside the wound roll, causing scratches and unevenness defects on the films (hereinafter, blocking-induced defects).

As a method of suppressing the defects caused by blocking, for example, a method of improving the film slipperiness by adding slippery particles having antiblocking property such as silica particles having a specific particle size to the molten resin is known. (See Patent Document 1).

Japanese Patent No. 5587209

However, when slippery particles are added to the molten resin as in the method described in Patent Document 1, although the effect of preventing blocking can be obtained, there is a problem that the film quality such as transparency is deteriorated.
Further, in the film manufacturing process, since the entire width of the entire surface of the film becomes slippery, the film tends to meander without gripping the transport roll during film transport. When the film meanders, the problem of winding misalignment tends to occur.
The winding misalignment is a problem related to the non-uniformity of the roll end face position due to the deviation of the end position when the film is wound into a roll.

In view of the above situation, the present invention can both suppress the occurrence of blocking-induced defects such as scratches and irregularities caused by contact between films and suppress the occurrence of winding deviation due to the meandering of the film. It is an object of the present invention to provide a method for producing a film and an optical film that can be produced by the production method.

In the method for producing an optical film, a film-like melt of a thermoplastic resin composition containing slippery particles is discharged from a die outlet of an extruder and sandwiched between a pair of rolls including a cast roll. The temperature of the film-like melt at the die outlet is raised by 5 ° C. or more in the high-temperature region of 1 or more in the width direction of the film-like melt, and the temperature of the cast roll is raised by Tg-40 ° C. or more Tg. We have found that the above problems can be solved by setting the temperature to −5 ° C. or lower (Tg is the glass transition temperature of the thermoplastic resin composition), and have completed the present invention.

That is, the present invention
(I) A method for producing an optical film in which a film-like melt of a thermoplastic resin composition containing slippery particles is discharged from a die outlet of an extruder and sandwiched between a pair of rolls including a cast roll.
The temperature of the film-like melt at the die outlet is increased by 5 ° C. or more in one or more high-temperature regions in the width direction of the film-like melt as compared with other low-temperature regions.
A method for setting the temperature of the cast roll to Tg-40 ° C or higher and Tg-5 ° C or lower (Tg is the glass transition temperature of the thermoplastic resin composition).
(Ii) The method according to (i), wherein the temperature in the high temperature region is higher than the temperature in the low temperature region by 10 ° C. or more.
(Iii) The method according to (i) or (ii), wherein the temperature of the cast roll is Tg-15 ° C. or lower.
(Iv) The method according to any one of (i) to (iii), wherein the slippery particles include multilayer structure particles.
(V) The method according to (iv), wherein the multilayer structure particles have a rubber portion having a degree of cross-linking of 2.3% by weight or more and 4.0% by weight or less.
(Vi) The method according to any one of (i) to (v), wherein the thermoplastic resin contains an acrylic resin.
(Vi) The method according to any one of (i) to (vi), wherein the thermoplastic resin composition contains rubber particles in an amount of 5 parts by weight or more and 25 parts by weight or less with respect to 100 parts by weight of the thermoplastic resin composition.
(Viii) The method according to any one of (i) to (vii), wherein there are two or more high temperature regions in the width direction of the film-like melt.
The method according to (viii), wherein the (ix) high temperature region includes both ends in the width direction of the film-like melt, and (x) an optical film containing a thermoplastic resin.
An optical film having a coefficient of static friction at both ends in the width direction of the optical film is 0.4 or more and higher than the coefficient of static friction at the center in the width direction of the optical film by 0.1 or more.
I will provide a.

According to the present invention, it is possible to manufacture an optical film capable of both suppressing the occurrence of blocking-induced defects such as scratches and irregularities caused by contact between films and suppressing the occurrence of winding deviation due to meandering of the film. A method and an optical film that can be produced by the production method can be provided.

It is a figure which shows typically about the sandwich molding.

≪Manufacturing method of optical film≫
In the method for producing an optical film, a film-like melt of a thermoplastic resin composition containing slippery particles is discharged from a die outlet of an extruder, and sandwiched and molded by a pair of rolls including a cast roll.
Slippery particles are materials that impart slipperiness to a film. Therefore, when the thermoplastic resin composition contains slippery particles, slipperiness is imparted to the surface of the film obtained through sandwich molding, and as a result, blocking-induced defects such as scratches and irregularities occur. It is suppressed.

Further, in the method for producing an optical film, the temperature of the film-like melt at the die outlet is set to be 5 ° C. or more higher than the other low-temperature regions in one or more high-temperature regions in the width direction of the film-like melt, and cast. The temperature of the roll is set to Tg-40 ° C. or higher and Tg-5 ° C. or lower (Tg is the glass transition temperature of the thermoplastic resin composition).

By providing a high temperature region and a low temperature region in the film-like melt discharged from the die outlet, when sandwiching is performed by a pair of rolls including a cast roll, the temperature difference between the regions with respect to the width direction of the film. Occurs.
Then, when the film passes through the pair of rolls and is sandwiched, the slippery particles are more likely to be buried in the place where the temperature of the film is high than in the place where the temperature of the film is low.
If the film is excessively cooled during sandwiching, the thermoplastic resin, which is the matrix material of the film, is not easily deformed. Therefore, even if there is a temperature difference between regions in the width direction of the film, the slippery particles There is little difference in the ease of burial between regions.
However, when the temperature of the cast roll is Tg-40 ° C or higher and Tg-5 ° C or lower (Tg is the glass transition temperature of the thermoplastic resin composition), the thermoplastic resin in the film sandwiched between the rolls is sufficient. Since it is easily deformed into a resin, the difference in the easiness of burying slippery particles in each region is clear in the width direction of the film.
As a result, due to the difference in the degree of burial of the slippery particles, the obtained optical film has a difference in the coefficient of static friction for each region in the width direction, and the region having a low coefficient of static friction suppresses the meandering of the film. The region with a high coefficient of static friction suppresses the occurrence of defects caused by blocking.

<Film formation method>
Hereinafter, the film forming method and the sandwich molding will be described with reference to FIG.
FIG. 1 is a diagram schematically showing sandwich molding in a method for manufacturing an optical film. In FIG. 1, the extruder 10 is simplified and only the vicinity of the T die 11 is shown.
First, a predetermined thermoplastic resin composition as a film raw material is put into the extruder 10 and heated to a temperature equal to or higher than the glass transition temperature in the extruder 10 to be in a molten state.

The thermoplastic resin composition in the molten state is transferred to the T die 11 attached to the outlet side of the extruder 10, and is discharged as the film-like melt 13 from the die outlet 12 at the tip of the die in the molten state.

Here, as the T-die 11, a T-die 11 whose temperature can be set independently in two or more plurality of regions in the width direction of the die outlet 12 is used. As the T-die 11, for example, two or more heaters whose temperatures can be adjusted independently may be provided in parallel in the width direction of the die outlet 12.
By using such a die, one or more high temperature regions and other low temperature regions can be formed in the film-like melt 13 at the die outlet 12.

Then, the temperature of the T die 11 is set so that the film-like melt 13 at the die outlet 12 is formed with one or more high-temperature regions in the width direction of the film-like melt 13 and a low-temperature region other than the high-temperature region. After that, the melt of the thermoplastic resin composition is discharged from the die outlet 12.
Here, the temperature in the high temperature region is set to be 5 ° C. or more higher than the temperature in the other low temperature region. By doing so, it is easy to make a difference in the degree of burial of the slippery particles in each region in the obtained film, and as a result, a difference in the coefficient of static friction in each region occurs in the obtained film.
The temperature in the high temperature region is preferably 10 ° C. or higher higher than the temperature in the low temperature region.

The melt viscosity of the film-like melt 13 in the low temperature region near the die outlet 12 is preferably 8000 poise or more and 15000 poise or less at a shear rate of 122 sec ^-1 .
Further, the melt viscosity of the film-like melt 13 in the high temperature region near the die outlet 12 is preferably 4000 poise or more and 7000 poise or less at a shear rate of 122 sec ^-1 .
When the melt viscosity of the film-like melt 13 in the low temperature region near the die outlet 12 is less than 8000 poise, the slippery particles are excessively buried by sandwich molding, and it is desired to be in a portion derived from the low temperature region of the obtained film. It may be difficult to impart slipperiness.
When the melt viscosity of the film-like melt 13 in the low temperature region near the die outlet 12 exceeds 15,000 poise, the location derived from the low temperature region of the obtained film due to insufficient burial of slippery particles. External haze in may be excessively high.
If the melt viscosity of the film-like melt 13 in the high temperature region near the die outlet 12 exceeds 7,000 poise, the degree of burial of the slippery particles is insufficient, and the film is also derived from the high temperature region of the obtained film. High slipperiness may be exhibited, and it may be difficult to suppress the meandering of the film.

Here, the total width of one or more high temperature regions with respect to the width direction of the film-like melt 13 is preferably 40 mm or more, and more preferably 50 mm or more.
Further, the total width of one or more high temperature regions is preferably in the range of 15% or less with respect to the total width of the film-like melt 13.
The preferable value of the upper limit of the total width of the high temperature region differs depending on the total width of the film-like melt, but the total width of the high temperature region is typically preferably 200 mm or less, more preferably 150 mm or less.

If the total width of the high temperature region is too narrow, it may be difficult to suppress the meandering of the film because the area of the low slippery region in the obtained film is small.
In addition, the low slipperiness region derived from the high temperature region in the obtained film is different from the main region of the film derived from the low temperature region in terms of slipperiness and physical properties of the film, so that it may be included in products that require high quality. It may not be preferable.
In this case, it is preferable to slit the low slippery region of the film so that it is not finally contained in the product. Therefore, if the total width of the high temperature region is more than 15%, there is a lot of loss due to excision of the low slippery region in the film, which is not preferable because the yield of the film is lowered.
However, the product may include a low slippery region as long as the difference in slipperiness and film physical properties between the low slippery region and the main region is within the allowable range required for the product.

It is preferable that the film-like melt 13 is provided with two or more high temperature regions.
When there are two or more high temperature regions, the obtained film is formed with two or more low slippery regions derived from the high temperature region. As a result, the deviation during film transportation is remarkably suppressed in the region sandwiched between the plurality of low slippery regions.
From the viewpoint of high effect of suppressing meandering, the low slippery region is preferably both ends in the width direction of the film. Therefore, it is preferable that the high temperature region is also provided at both ends of the film-like melt 13 in the width direction.
It is preferable that the low slippery region is provided at both ends in the width direction of the film because a wide film can be obtained when the low slippery region is cut by slitting or the like.

When the low slippery region is provided at both ends in the width direction of the film, the width of the high temperature region formed at both ends in the width direction of the film-like melt 13 is from both ends of the film-like melt 13. 20 mm or more is preferable, and 25 mm or more is more preferable.
The width of the high temperature region formed at both ends is preferably 100 mm or less, more preferably 75 mm or less from both end portions of the film-like melt 13.

Examples of the extrusion method include a method of ejecting the molten thermoplastic resin composition from the die outlet 12 by using an extruder that melts the thermoplastic resin composition and extrudes it to the die outlet 12.

The surface of the film-like melt 13 is smoothed by being sandwiched between a pair of smoothing rolls. One of the smoothing rolls is an elastic roll 14 and the other is a cast roll 15. The elastic roll 14 refers to a roll in which the surface of a roll made of an elastic body such as rubber is covered with a metal film, and the surface of the roll is flattened by the metal film on the surface and functions as a smoothing roll.
The cast roll 15 is a hard roll made of metal.

When sandwich molding is performed, the protrusion level of the slippery particles changes. Here, the temperature of the cast roll 15 is set to Tg-40 ° C or higher and Tg-5 ° C or lower, preferably Tg-40 ° C or higher and Tg-15 ° C or lower. Set.
The lower limit of the temperature of the cast roll 15 may be Tg-35 ° C. or higher, Tg-30 ° C. or higher, or Tg-25 ° C. or higher.
In this case, in the region in the film derived from the low temperature region of the film-like melt 13, the film is imparted with high slipperiness by suppressing excessive burial of the slippery particles.
On the other hand, in the region in the film derived from the high temperature region derived from the low temperature region of the film-like melt 13, the slipperiness is suppressed by sufficiently burying the slippery particles.
As a result of the above, a high slippery region for suppressing the occurrence of blocking-induced defects and a low slippery region for suppressing winding misalignment are formed in the film.
If the temperature of the cast roll 15 is less than Tg-40 ° C., the film is likely to be pinched and pulled out, which is not preferable.

By the method described above, a film containing a low slippery region and a high slippery region in the width direction of the film can be obtained.
More preferably, after performing the above-mentioned sandwich molding, sandwich molding is further performed on the region having low slipperiness. As a result, the slipperiness of the low slippery region can be further reduced, and the effect of suppressing the winding deviation can be enhanced.
The timing at which the additional sandwiching molding is performed is not particularly limited, but it is preferable that the additional sandwiching molding is performed directly under the elastic roll 14 and the cast roll 15 and continuously with the initial sandwiching molding.

The coefficient of static friction (load 200 g, FS 50%) in the low-slip region in the film obtained by the above method is preferably 0.4 or more because it is easy to suppress the occurrence of blocking-induced defects and the meandering of the film. , 0.5 or more is more preferable, and 0.8 or more is particularly preferable.
The coefficient of static friction (load 200 g, FS 50%) in the low slip area is preferably 0.1 or more higher than the coefficient of static friction (load 200 g, FS 50%) in the high slip area, and is 0.3 or more higher. Is more preferable, and 0.5 or more is particularly preferable.
The coefficient of static friction in the high-slip area (load 200 g, FS50%) is the coefficient of static friction in the low-slip area (load 200 g, FS50%), and the coefficient of static friction in the high-slip area (load 200 g, FS50). %) Is higher, preferably 0.2 or more and 0.8 or less.

Among such films, the coefficient of static friction at both ends in the width direction is 0.4 or more because it is particularly easy to suppress the occurrence of defects caused by blocking and the occurrence of winding deviation due to meandering of the film. Moreover, a film having a coefficient of static friction at the center in the width direction higher than 0.1 or more is preferable.

It is preferable to slit a part, preferably the whole, of the low slippery region between the time of performing the sandwich molding as described above and the time of winding into a roll.
This is because the film quality differs between the high slippery region, which is the main region of the film used as a product, and the low slippery region. When producing a uniform film over the entire width, the low slipperiness is achieved. The area needs to be slit and excised.
On the other hand, if the quality non-uniformity between the high slip area and the low slip area is acceptable for the product, the low slip area may be finally included in the product.

When slitting the entire low slippery region, it is preferable to slit immediately before winding in a roll shape from the viewpoint of preventing meandering. It is also good to put knurling on the inside before and after slitting. When slitting is performed after knurling is applied, meandering is suppressed to some extent even in the knurling portion. Therefore, the slit after knurling is more preferable in that the influence of meandering and winding deviation is reduced.

The film forming method described above may include, if necessary, a step of inspecting foreign matter in the film and a step of stretching.

The thickness of the optical film produced according to the above method is not particularly limited.
In the above method, for example, even in an extremely thin film having a thickness of 30 μm or more and 80 μm or less, a low slippery region and a high slippery region can be formed, so that scratches caused by contact between the films or the like can occur. It is possible to suppress the occurrence of blocking-induced defects such as the occurrence of unevenness and the occurrence of winding deviation due to the meandering of the film.
With the conventional method, it is difficult to suppress the occurrence of blocking-induced defects and the occurrence of winding deviation in the meandering of the film at the time of producing a thin film, and such an effect is remarkable.

<Thermoplastic resin composition>
Hereinafter, essential or arbitrary components in the thermoplastic resin composition which is the material of the optical film will be described.

(Thermoplastic resin)
The thermoplastic resin is a material that constitutes a matrix portion in a film. The thermoplastic resin used in the production of the film is not particularly limited as long as it is a thermoplastic resin that can be used as an optical film and can be molded by melt extrusion.
For example, polycarbonate resin, aromatic vinyl resin and its hydrogen additive, polyolefin resin, acrylic resin, polyester resin, polyarylate resin, polyimide resin, polyether sulfone resin, polyamide resin, cellulose resin, Examples thereof include thermoplastic resin compositions such as polyphenylene oxide resin. Of these, acrylic resins are particularly preferable from the viewpoint of transparency.

The acrylic resin is not particularly limited, but a methacrylic resin containing methyl methacrylate as a monomer component can be used, and a resin containing 30 to 100% by weight of a constituent unit derived from methyl methacrylate is preferable. Among the acrylic resins, heat-resistant acrylic resins are preferable.

As a heat-resistant acrylic resin, for example,
1) Acrylic resin in which an N-substituted maleimide compound is copolymerized as a copolymerization component.
2) Acrylic anhydrous glutarate resin,
3) Acrylic resin having a lactone ring structure,
4) Glutarimide acrylic resin,
5) Acrylic resin containing hydroxyl groups and / or carboxyl groups,
6) An aromatic vinyl-containing acrylic polymer obtained by polymerizing an aromatic vinyl monomer and another monomer copolymerizable therewith (for example, a styrene monomer and another single amount copolymerizable therewith). Styrene-containing acrylic polymer obtained by polymerizing the body)
7) A hydrogenated aromatic vinyl-containing acrylic polymer obtained by partially or wholly hydrogenating the aromatic ring of the resin of 6) above (for example, a styrene monomer and another single amount copolymerizable therewith). Partially hydrogenated styrene-containing acrylic polymer obtained by partially hydrogenating the aromatic ring of the styrene-containing acrylic polymer obtained by polymerizing the body),
8) Acrylic polymer containing a cyclic acid anhydride repeating unit and the like can be mentioned.
A glutarimide acrylic resin can be more preferably used from the viewpoint of heat resistance and optical properties.

（式中、Ｒ^１およびＲ^２は、それぞれ独立して、水素原子または炭素数１〜８のアルキル基であり、Ｒ^３は、炭素数１〜１８のアルキル基、炭素数３〜１２のシクロアルキル基、または炭素数５〜１５の芳香環を含む置換基である。）
で表される単位（以下、「グルタルイミド単位」ともいう）と、
下記一般式（２）：

（式中、Ｒ^４およびＲ^５は、それぞれ独立して、水素原子または炭素数１〜８のアルキル基であり、Ｒ^６は、炭素数１〜１８のアルキル基、炭素数３〜１２のシクロアルキル基、または炭素数５〜１５の芳香環を含む置換基である。）
で表される単位（以下、「（メタ）アクリル酸エステル単位」ともいう）とを含むグルタルイミドアクリル系樹脂を好適に用いることができる。 The glutarimide acrylic resin will be described in detail below. Specifically, as the glutarimide acrylic resin, for example, the following general formula (1):

(In the formula, R ¹ and R ² are independently hydrogen atoms or alkyl groups having 1 to 8 carbon atoms, and R ³ is an alkyl group having 1 to 18 carbon atoms and cyclo having 3 to 12 carbon atoms. It is an alkyl group or a substituent containing an aromatic ring having 5 to 15 carbon atoms.)
Units represented by (hereinafter, also referred to as "glutarimide units"),
The following general formula (2):

(In the formula, R ⁴ and R ⁵ are independently hydrogen atoms or alkyl groups having 1 to 8 carbon atoms, and R ⁶ is an alkyl group having 1 to 18 carbon atoms and cyclo having 3 to 12 carbon atoms. It is an alkyl group or a substituent containing an aromatic ring having 5 to 15 carbon atoms.)
A glutarimide acrylic resin containing a unit represented by (hereinafter, also referred to as "(meth) acrylic acid ester unit") can be preferably used.

（式中、Ｒ^７は、水素原子または炭素数１〜８のアルキル基であり、Ｒ^８は、炭素数６〜１０のアリール基である。）
で表される単位（以下、「芳香族ビニル単位」ともいう）をさらに含んでいてもよい。 Further, the glutarimide acrylic resin may be prepared from the following general formula (3):

(In the formula, R ⁷ is a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, and R ⁸ is an aryl group having 6 to 10 carbon atoms.)
The unit represented by (hereinafter, also referred to as “aromatic vinyl unit”) may be further included.

In the above general formula (1), R ¹ and R ² are independently hydrogen atoms or methyl groups, respectively. R ³ is preferably a hydrogen atom, a methyl group, a butyl group, or a cyclohexyl group, R ¹ is a methyl group, R ² is a hydrogen atom, and R ³ is more preferably a methyl group.

The glutarimide acrylic resin may contain only one type as the glutarimide unit, or may contain a plurality of types having different R ¹ , R ² , and R ³ in the general formula (1). You may.
The glutarimide unit is an adjacent two alkoxycarbonyl groups contained in the continuous (meth) acrylic acid ester unit when the (meth) acrylic acid ester unit represented by the above general formula (2) is continuous. It can be formed by imidizing (carboxylic acid ester group).

Also, an acid anhydride such as maleic anhydride, or a half ester of such an acid anhydride and a linear or branched alcohol having 1 to 20 carbon atoms; acrylic acid, citraconic acid, maleic acid, maleic anhydride, The glutarimide unit can also be formed by imidizing α, β-ethylene unsaturated carboxylic acids such as itaconic acid, maleic anhydride, crotonic acid, fumaric acid, and citraconic acid.

In the above general formula (2), R ⁴ and R ⁵ are preferably hydrogen or methyl groups, respectively, R ⁶ is preferably hydrogen or methyl group, R ⁴ is hydrogen, and R ⁵ is. It is a methyl group, and it is more preferable that R ⁶ is a methyl group.
The glutarimide acrylic resin, (meth) acrylic acid ester unit, may include only a single type, R ⁴ in the general formula ^(2), R ^5, and R ⁶ is different It may include the type.
The glutarimide acrylic resin preferably contains styrene, α-methylstyrene and the like as the aromatic vinyl constituent unit represented by the general formula (3), and more preferably contains styrene.
Further, the glutarimide acrylic resin may contain only a single type as the aromatic vinyl constituent unit, or may contain a plurality of types having different R ⁷ and R ⁸ .

In the above general formula (2), R ⁴ and R ⁵ are preferably hydrogen atoms or methyl groups, respectively, R ⁶ is preferably a hydrogen atom or a methyl group, and R ⁴ is a hydrogen atom. More preferably, R ⁵ is a methyl group and R ⁶ is a methyl group.
The glutarimide acrylic resin, (meth) acrylic acid ester unit, may include only a single type, R ⁴ in the general formula ^(2), R ^5, and R ⁶ is different It may include the type.
The glutarimide acrylic resin preferably contains styrene, α-methylstyrene and the like as the aromatic vinyl constituent unit represented by the general formula (3), and more preferably contains styrene.
Further, the glutarimide acrylic resin may contain only a single type as the aromatic vinyl constituent unit, or may contain a plurality of types having different R ⁷ and R ⁸ .

In the glutarimide acrylic resin, the content of the glutarimide unit represented by the general formula (1) is not particularly limited, for example, it is preferable to change depending on the structure or the like of R ^3.

In general, the content of the glutarimide unit is preferably 1% by weight or more, more preferably 1% by weight to 95% by weight, still more preferably 2% by weight to 90% by weight of the glutarimide acrylic resin. It is particularly preferably from% to 80% by weight.
When the content of the glutarimide unit is within the above range, the heat resistance and transparency of the obtained glutarimide acrylic resin are lowered, and the moldability and the mechanical strength when processed into a film are lowered. It's hard to do.

On the other hand, if the content of the glutarimide unit is less than the above range, the heat resistance of the obtained glutarimide acrylic resin tends to be insufficient or the transparency tends to be impaired. On the other hand, if it is more than the above range, the heat resistance and the melt viscosity are unnecessarily increased, the molding processability is deteriorated, the mechanical strength at the time of film processing becomes extremely brittle, and the transparency is impaired. Tend.

In the glutarimide acrylic resin, the content of the aromatic vinyl unit represented by the general formula (3) is not particularly limited, and can be appropriately set according to the required physical properties. Depending on the intended use, the content of the aromatic vinyl unit represented by the general formula (3) may be 0% by weight.
When the aromatic vinyl unit represented by the general formula (3) is contained, the content thereof is preferably 10% by weight or more based on the total repeating unit of the glutarimide acrylic resin, and is preferably 10% by weight to 40% by weight. It is more preferably 50% by weight, further preferably 15% to 30% by weight, and particularly preferably 15% to 25% by weight. When the content of the aromatic vinyl unit is within the above range, the heat resistance of the obtained glutarimide acrylic resin is unlikely to be insufficient, and the mechanical strength during film processing is unlikely to decrease.
On the other hand, if the content of the aromatic vinyl unit is larger than the above range, the heat resistance of the obtained glutarimide acrylic resin tends to be insufficient.

If necessary, the glutarimide acrylic resin may be further copolymerized with units other than the glutarimide unit, the (meth) acrylic acid ester unit, and the aromatic vinyl unit.
Other units include, for example, copolymerization of nitrile-based monomers such as acrylonitrile and methacrylonitrile, and maleimide-based monomers such as maleimide, N-methylmaleimide, N-phenylmaleimide, and N-cyclohexylmaleimide. The constituent units can be mentioned.
These other units may be directly copolymerized or graft-copolymerized in the glutarimide acrylic resin.

The weight average molecular weight of the glutarimide acrylic resin is not particularly limited, but is preferably ^{1 × 10 4 ~5 × 10 5} . If it is within the above range, it is unlikely that the moldability is lowered and the mechanical strength at the time of film processing is insufficient. On the other hand, if the weight average molecular weight is smaller than the above range, the mechanical strength of the film tends to be insufficient. On the other hand, if it is larger than the above range, the viscosity at the time of melt extrusion is high, the molding processability is lowered, and the productivity of the molded product tends to be lowered.

The glass transition temperature of the glutarimide acrylic resin is not particularly limited, but is preferably 110 ° C. or higher, more preferably 120 ° C. or higher. When the glass transition temperature is within the above range, the applicable range of the obtained thermoplastic resin composition can be expanded.

The method for producing the glutarimide acrylic resin is not particularly limited, and examples thereof include the methods described in JP-A-2008-273140.

(Slippery particles)
The slippery particles are not particularly limited as long as they can impart slipperiness to the film, and various particulate additives conventionally used for the purpose of imparting slipperiness to a transparent resin composition may be used. it can.
Here, the slippery particles are obtained by forming a film of a thermoplastic resin composition composed of 85 parts by weight of a thermoplastic resin and 0.5 parts of particles, and determining the coefficient of static friction (load 200 g, FS 50%) of the obtained film. When A is used, it means particles in which A is 60% or less with respect to static friction coefficient (load 200 g, FS 50%) B of a film made of only a thermoplastic resin.
The film for measuring A and the film for measuring B are produced under the same conditions.

Suitable specific examples of the slippery particles include silica such as colloidal silica, kaolin, talc, aluminum oxide, calcium hydroxide, magnesium oxide, glass particles, feldspar, and inorganic particles such as zeolite, acrylic particles, and silicone resin particles. , Zeolite resin particles, and organic particles such as Teflon (registered trademark) particles.

Furthermore, organic crosslinked polymer particles can also be used as slippery particles. Examples of the organic crosslinked polymer particles include a monofunctional monomer such as methyl methacrylate and a polyfunctional monomer such as trimethylolpropane tri (meth) acrylate, allyl (meth) acrylate, and ethylene glycol di (meth) acrylate. , (Meta) acrylic crosslinked particles obtained by suspension polymerization (see Japanese Patent Application Laid-Open No. 4034157).
Styrene- (meth) acrylic crosslinked particles obtained by further copolymerizing a styrene-based monomer such as styrene, α-methylstyrene, or divinylbenzene at the time of suspension polymerization may be used. Further, at least one selected from (meth) acrylic acid monomer, (meth) acrylic acid ester monomer and styrene-based monomer was obtained by emulsion polymerization, soap-free emulsion polymerization, mini-emulsion polymerization, dispersion polymerization or seed polymerization (). It may be a meta) acrylic crosslinked particle or a styrene- (meth) acrylic crosslinked particle.

Organic-inorganic composite particles can also be used as slippery particles. Organic-inorganic composite particles consist of an organic moiety and an inorganic moiety. The content of the inorganic portion in the organic-inorganic composite particles is, for example, 0.5 to 90% by weight, preferably 1 to 70% by weight, and more preferably 2 to 60% by weight in terms of inorganic oxide. Here, the content in terms of inorganic oxide means, specifically, residual when the particles are fired at a high temperature (for example, 1000 ° C. or higher) in an oxidizing atmosphere such as in the air with respect to the weight of the organic-inorganic composite particles. It is a numerical value expressed by the ratio of the weights of the inorganic oxides to be produced.

Preferred specific examples of the organic-inorganic composite particles include an organopolymer skeleton described in JP-A-8-81561 and an organosilicon in which a silicon atom is directly chemically bonded to at least one carbon atom in the skeleton. It has a polysiloxane skeleton, particles having a content of SiO ₂ constituting the polysiloxane skeleton of 25% by weight or more, and a (meth) acryloxy group described in JP-A-2003-183337. These are particles in which a vinyl-based polymer is contained in the structure of polysiloxane particles.

Particularly preferable slippery particles include multilayer structure particles having a rubber portion having a degree of cross-linking of 2.3% by weight or more and 4.0% by weight or less and a particle diameter of 180 nm or more and 400 nm or less. The rubber portion constitutes the core of the multilayer structure particles.
Such multilayer structure particles enhance the slipperiness of the film, impart antiblocking property to the film, have excellent dispersibility in the film, and do not easily reduce the transparency of the film.

Further, the multilayer structure particles include a rubber portion having a degree of cross-linking of 2.3% by weight or more and 4.0% by weight or less. Therefore, the multilayer structure particles have a certain degree of hardness. As a result, when the films containing the multilayer structure particles come into contact with each other or between the films and the rolls, the multilayer structure particles are not easily deformed and the film is imparted with slipperiness.
The degree of cross-linking is the ratio (% by weight) of the weight of the polyfunctional monomer having two or more functionalities to the total weight of the monomer for the monomer used for manufacturing the rubber part. Is.

When the degree of cross-linking of the rubber portion is less than 2.3% by weight, the rubber portion is flexible and therefore easily deforms when the multilayer structure particles protruding from the film surface come into contact with the roll or the film. Therefore, it is difficult to impart the desired slipperiness to the film.
When the degree of cross-linking of the rubber portion exceeds 4.0% by weight, cracks and chips are likely to occur in the multilayer structure particles, and the desired slipperiness cannot be imparted to the central portion of the film, or fine powder is generated during film production. In some cases.

Further, the particle size of the rubber portion is 180 nm or more and 400 nm or less. By using the multilayer structure particles including the rubber portion of such a size, it is easy to impart slipperiness to the film without impairing the transparency of the film. When the particle size of the rubber portion is less than 180 nm, it is difficult to impart the desired degree of slipperiness to the film. Further, when the particle size of the rubber portion exceeds 400 nm, it is difficult to obtain a film having a desired degree of transparency. Here, the particle size of the rubber portion is determined by using a U-5100 type ratio beam spectrophotometer manufactured by Hitachi High-Technologies Corporation and using light scattering having a wavelength of 546 nm.

The multilayer structure particles are composed of core particles having a rubber portion having the above-mentioned predetermined requirements and a shell layer. The shell layer may be a single layer or a multi-layer.

The shell layer may be chemically bonded to the rubber portion by a covalent bond or the like, or may cover the rubber portion without being chemically bonded to the rubber portion. When the shell layer has a multi-layer structure of two or more layers, the layers constituting the shell layer may or may not be chemically bonded to each other by a covalent bond or the like. ..
A preferred example of a method of chemically bonding the shell layer to the surface of the rubber portion or the surface of another shell layer is a method of forming the shell layer by graft polymerization. The presence of the shell layer improves the compatibility with the thermoplastic resin to be mixed, and the particles can be uniformly dispersed. When particles without a shell layer are mixed with a thermoplastic resin, the particles are difficult to disperse uniformly, and the transparency of the film may decrease.

Examples of the material of the rubber portion include a butadiene-based crosslinked polymer, a (meth) acrylic-based crosslinked polymer, and an organosiloxane-based crosslinked polymer. Among them, in terms of weather resistance (light resistance) and transparency of the film, a (meth) acrylic crosslinked polymer (in the present specification, a rubber portion made of a (meth) acrylic copolymer is referred to as an acrylic rubber particle. Also referred to as) is particularly preferable.

Examples of the acrylic rubber particles include ABS resin rubber particles, ASA resin rubber particles, and acrylic acid ester rubber particles.
As the multilayer structure particles, core-shell particles obtained by forming a shell layer by performing graft polymerization on the surface of these acrylic rubber particles using a desired monomer are preferable.
From the viewpoint of the transparency of the obtained film, the acrylic-based graft copolymer particles obtained by graft-polymerizing the surfaces of the acrylic acid ester-based rubber-like polymer particles shown below are preferable as the multilayer structure particles. ..
The acrylic graft copolymer particles can be obtained by polymerizing a monomer mixture containing a methacrylic acid ester as a main component in the presence of particles of an acrylic acid ester-based rubbery polymer.

The acrylic acid ester-based rubber-like polymer, which is the material of the rubber portion, is a rubber-like polymer containing acrylic acid ester as a main component. Specifically, a monomer mixture (100% by weight) consisting of 50 to 100% by weight of an acrylic acid ester and 50 to 0% by weight of another copolymerizable vinyl-based monomer, and two or more per molecule. It is preferably obtained by polymerizing a polyfunctional monomer having a non-conjugated reactive double bond.
The polyfunctional monomer is used in a desired amount so that the degree of cross-linking of the rubber portion is in the range of 2.3% by weight or more and 4.0% by weight or less.
All the monomers may be mixed and used, or the monomer composition may be changed and used in two or more stages.

As the acrylic acid ester, it is preferable to use an alkyl group having 1 to 12 carbon atoms from the viewpoint of polymerizable property and cost. For example, methyl acrylate, ethyl acrylate, n-propyl acrylate, n-butyl acrylate, sec-butyl acrylate, isobutyl acrylate, benzyl acrylate, cyclohexyl acrylate, 2-ethylhexyl acrylate, n- acrylate. Examples thereof include octyl, phenyl acrylate, and 2-phenoxyethyl acrylate.
Two or more of these acrylic ester may be used in combination.
The amount of acrylic acid ester is preferably 50% by weight or more and 100% by weight or less, more preferably 60% by weight or more and 99% by weight or less, still more preferably 70% by weight or more and 99% by weight or less, and 80% by weight or less, based on 100% by weight of the monomer mixture. Most preferably, it is at least% by weight and 99% by weight or less.
If it is less than 50% by weight, the impact resistance is lowered, the elongation at the time of tensile break is lowered, and cracks are likely to occur at the time of film cutting.

As the other vinyl-based monomer copolymerizable with the acrylic acid ester, methacrylic acid esters are particularly preferable from the viewpoint of weather resistance and transparency. Examples of methacrylic acid esters include methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, n-butyl methacrylate, sec-butyl methacrylate, isobutyl methacrylate, benzyl methacrylate, cyclohexyl methacrylate, 2-methacrylic acid. Examples thereof include phenoxyethyl, 2-ethylhexyl methacrylate, phenyl methacrylate, n-octyl methacrylate and the like.

Aromatic vinyls and derivatives thereof, and vinyl cyanide are also preferable. Examples of these vinyl-based monomers include styrene, methylstyrene, acrylonitrile, and methacrylonitrile. Other examples include unsubstituted and / or substituted maleic anhydrides, (meth) acrylamides, vinyl esters, vinylidene halides, (meth) acrylic acids and salts thereof, (hydroxyalkyl) acrylic acid esters and the like.

Examples of the polyfunctional monomer copolymerized with the monofunctional monomer containing acrylic acid ester as a main component include allyl methacrylate, allyl acrylate, triallyl cyanurate, triallyl isocyanurate, and diallyl phthalate. Uses diallyl malate, divinyl adipate, divinylbenzene, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, trimethylroll propantrimethacrylate, pentaerythritol tetramethacrylate, dipropylene glycol dimethacrylate, and acrylates thereof. can do. Two or more of these polyfunctional monomers may be used.

The multilayer structure polymer may have another polymer layer inside (center side) of the rubber portion. From the viewpoint of anti-blocking property, a monomer mixture consisting of 40 to 100% by weight of an alkyl methacrylate ester and 60 to 0% by weight of another monomer having a copolymerizable double bond thereof, and the above-mentioned It is preferable to have a methacrylic crosslinked polymer layer obtained by polymerizing 0.01 to 10 parts by weight of a polyfunctional monomer with respect to 100 parts by weight of the monomer mixture. Examples of the monomer having a copolymerizable double bond include the above-mentioned other copolymerizable vinyl-based monomers and acrylic acid esters.
The acrylic graft copolymer comprising the rubber portion and the shell layer formed by graft polymerization on the surface of the rubber portion is 5 to 90 parts by weight (more preferably 5) of particles of the acrylic acid ester rubber-like polymer. It is preferably obtained by polymerizing 95 to 25 parts by weight of a monomer mixture containing a methacrylic acid ester as a main component in at least one step in the presence of (~ 75 parts by weight).

The methacrylic acid ester in the graft copolymer composition (monomer mixture) is preferably 50% by weight or more. If it is less than 50% by weight, the hardness and rigidity of the obtained film tend to decrease.
As the monomer used for graft copolymerization, the above-mentioned methacrylic acid ester, acrylic acid ester, and vinyl-based monomer copolymerizable with these can be similarly used, and methacrylic acid ester and acrylic acid ester are preferably used. Will be done. Methyl methacrylate is preferable from the viewpoint of compatibility with an acrylic resin, and methyl acrylate, ethyl acrylate, and n-butyl acrylate are preferable from the viewpoint of suppressing zipper depolymerization.

From the viewpoint of optical isotropic property, it is referred to as a (meth) acrylic monomer having an alicyclic structure, a heterocyclic structure or an aromatic group (referred to as "ring structure-containing (meth) acrylic monomer". ) Is also preferable as a monomer for graft copolymerization. Specific examples thereof include benzyl (meth) acrylate, dicyclopentanyl (meth) acrylate, and 2-phenoxyethyl (meth) acrylate.

The amount used is 100% by weight based on the total amount of the monomer mixture for graft copolymerization (the total amount of the ring structure-containing (meth) acrylic monomer and other monofunctional monomers copolymerizable therewith). 1 to 100% by weight is preferable, 5 to 70% by weight is more preferable, and 5 to 50% by weight is most preferable.

The other monofunctional monomer copolymerizable with the ring structure-containing (meth) acrylic monomer is the above-mentioned methacrylic acid ester, acrylic acid ester, or other copolymerizable vinyl monofunctional monomer. The monomers can be used as well, but preferably contain a methacrylic acid ester and an acrylic acid ester.

The methacrylic acid ester is preferably contained in an amount of 0 to 98% by weight based on 100% by weight of the total amount of the above-mentioned ring structure-containing vinyl-based monomer and other monofunctional monomers copolymerizable therewith. It is more preferably contained in an amount of ~ 98% by weight, further preferably 1 to 94% by weight, and particularly preferably 30 to 90% by weight.
Further, the acrylic acid ester is preferably contained in an amount of 0 to 98% by weight based on 100% by weight of the total amount of the above-mentioned ring structure-containing vinyl-based monomer and other monofunctional monomers copolymerizable therewith. .1 to 98% by weight is more preferable, 1 to 50% by weight is further preferable, and 5 to 50% by weight is particularly preferable.

The graft ratio of the acrylic ester-based rubber-like polymer to the particles is preferably 10 to 250%, more preferably 40 to 230%, and most preferably 60 to 220%.
If the graft ratio is less than 10%, the acrylic graft copolymer particles tend to aggregate in the film, which may reduce the transparency or cause foreign matter. In addition, the elongation at the time of tensile breakage decreases, and cracks tend to occur easily at the time of film cutting. If it exceeds 250%, for example, the melt viscosity during film molding tends to increase, and the formability of the film tends to decrease.

The graft ratio is a weight ratio of the graft component in the acrylic graft copolymer particles, and is measured by, for example, the following method.
2 g of acrylic graft copolymer particles are dissolved in 50 ml of methyl ethyl ketone and centrifuged at a rotation speed of 30,000 rpm and a temperature of 12 ° C. for 1 hour using a centrifuge (CP60E, manufactured by Hitachi Koki Co., Ltd.) to remove insoluble matter. Separate into dissolved particles (centrifugal separation work is set 3 times in total). From the weight of the obtained insoluble matter and the weight of the acrylic acid ester-based rubber-like polymer contained in the acrylic-based graft copolymer particles, the graft ratio is calculated by the following formula.
Graft ratio (%) = [{(weight of methyl ethyl ketone insoluble matter)-(weight of acrylic ester-based rubber polymer)} / (weight of acrylic ester rubber polymer)] × 100

Acrylic graft copolymer particles can be produced by a general emulsification polymerization method. Specifically, a method of continuously polymerizing an acrylic acid ester monomer using an emulsifier in the presence of a water-soluble polymerization initiator can be exemplified.
In the emulsion polymerization method, it is preferable to carry out continuous polymerization in a single reaction tank, and it is not preferable to use two or more reaction tanks because the mechanical stability of the latex is lowered.
The polymerization temperature is preferably 30 ° C. or higher and 100 ° C. or lower, more preferably 50 ° C. or higher and 80 ° C. or lower. If the temperature is lower than 30 ° C., the productivity tends to decrease, and if the temperature exceeds 100 ° C., the target molecular weight tends to be excessively large, and the quality tends to decrease.
Raw materials such as monomers, initiators, emulsifiers and deionized water that are continuously added to the polymerization reaction tank are accurately added under the control of a metering pump, but the amount of heat removed from the polymerization heat generated in the reaction tank. There is no problem even if it is cooled in advance as necessary to ensure the above.
If necessary, a polymerization inhibitor, a coagulant, a flame retardant, an antioxidant, and a pH adjuster may be added to the latex discharged from the reaction tank to recover unreacted monomers and post-polymerize. You may go. After that, a copolymer can be obtained through known methods such as solidification, heat treatment, dehydration, washing with water, and drying.

In the emulsion polymerization, a usual polymerization initiator can be used. For example, inorganic peroxides such as potassium persulfate and sodium persulfate, organic peroxides such as cumenehydroperoxide and benzoyl peroxide, and oil-soluble initiators such as azobisisobutyronitrile are also used. These may be used alone or in combination of two or more. These initiators are used as ordinary redox-type polymerization initiators in combination with reducing agents such as sodium sulfite, sodium thiosulfate, sodium formaldehyde, sulfoxylate, ascorbic acid, ferrous sulfate, and disodium ethylenediaminetetraacetic acid complex. You may.

A chain transfer agent may be used in combination with the polymerization initiator. Examples of the chain transfer agent include alkyl mercaptans having 2 to 20 carbon atoms, mercapto acids, thiophenols, carbon tetrachloride and the like, and these may be used alone or in combination of two or more.

The emulsifier used in the emulsion polymerization method is not particularly limited, and an ordinary emulsifier for emulsion polymerization can be used. For example, sulfate ester-based surfactants such as sodium alkylsulfate, sulfonate-based surfactants such as sodium alkylbenzene sulphonate, sodium alkylsulfonate, sodium dioctyl sulfosuccinate, sodium alkylphosphates, polyoxyethylene alkyl ethers. Examples thereof include anionic surfactants such as phosphate-based surfactants such as sodium phosphate ester. Further, the sodium salt may be another alkali metal salt such as potassium salt or an ammonium salt. These emulsifiers may be used alone or in combination of two or more. Further, a nonionic surfactant typified by an alkyl-substituted product or an aryl-substituted product of the polyoxyalkylenes or the terminal hydroxyl group thereof may be used or partially used in combination. Among them, a sulfonate-based surfactant or a phosphate-based surfactant is preferable from the viewpoint of polymerization reaction stability and particle-based controllability, and among them, dioctyl sulfosuccinate or polyoxyethylene alkyl ether phosphoric acid. Ester salts can be used more preferably.

The amount of the emulsifier used is preferably 0.05 parts by weight or more and 10 parts by weight, and more preferably 0.1 parts by weight or more and 1.0 part by weight or less with respect to 100 parts by weight of the entire monomer component. If the amount is less than 0.05 parts by weight, the particle size of the copolymer tends to be too large, and if the amount is more than 10 parts by weight, the particle size of the graft copolymer tends to be too small and the particle size distribution tends to be deteriorated. is there.

The slippery particles described above and the thermoplastic resin are mixed to obtain a thermoplastic resin composition.
The slippery particles and the thermoplastic resin may be uniformly pelletized according to a conventional method before the film is produced, or may be mixed by an extruder during the film production.
The amount of the slippery particles used is not particularly limited as long as the object of the present invention is not impaired. The amount of the slippery particles used is preferably 0.1 to 2.0 parts by weight, more preferably 0.2 to 1.5 parts by weight, based on 100 parts by weight of the thermoplastic resin.
When the amount of the multilayer structure particles used is less than 0.1 parts by weight, it is difficult to impart the desired degree of slipperiness to the highly slippery region of the film, and blocking-induced defects are likely to occur when the film is wound. ..
Further, if the amount of the multilayer structure particles used is more than 2.0 parts by weight, excessive slipperiness is given to the film, which may cause a transfer trouble.
(Rubber particles)
The thermoplastic resin composition preferably contains rubber particles together with the above-mentioned slippery particles.
The inclusion of rubber particles in the thermoplastic resin composition imparts toughness to the film, and as a result, cracking of the film in the transport process and generation of fine powder due to slit defects at the slit portion are less likely to occur, resulting in productivity. Can be improved.

The rubber particles are not particularly limited as long as they do not impair the object of the present invention and are different from the above-mentioned slippery particles.
Like the above-mentioned multilayer structure particles, the rubber particles preferably have a multilayer structure including a core having a rubber portion and one layer or two or more shell layers. The presence of the shell layer improves the compatibility with the thermoplastic resin to be mixed, and the particles can be uniformly dispersed. Although rubber particles without a shell layer can be used, if the rubber particles without a shell layer are mixed with the thermoplastic resin, the rubber particles are difficult to be uniformly dispersed, and the transparency of the film may be lowered.
The glass transition temperature of the rubber portion is not particularly limited, but is preferably less than 20 ° C.

The degree of cross-linking of the rubber portion contained in the rubber particles is preferably less than 2.3% by weight, and more preferably lower, in that the slipperiness of the low slippery region of the film is likely to be lowered.
The particle size of the rubber portion contained in the rubber particles is not particularly limited, but is preferably the same as the particle size of the rubber portion contained in the above-mentioned multilayer structure particles.

Suitable rubber particles having a multi-layer structure can be produced by the same material and the same method as the multi-layer structure particles described for the slippery particles, except that the degree of cross-linking of the rubber portion is different.

The amount of the rubber particles used is not particularly limited as long as the object of the present invention is not impaired. The amount of the rubber particles used is preferably 1 to 60 parts by weight, more preferably 1 to 30 parts by weight, still more preferably 1 to 25 parts by weight, when the total weight of the thermoplastic resin composition is 100 parts by weight. Most preferably 5 to 25 parts by weight.

(Other ingredients)
The thermoplastic resin composition may contain one or more kinds of antioxidants, ultraviolet absorbers, ultraviolet stabilizers and the like for improving stability against heat and light, in addition to the multilayer structure particles.

The optical film produced as described above includes members used in display devices such as liquid crystal display devices and organic EL devices, such as polarizing plate protective films, retardation films, brightness improving films, liquid crystal substrates, and light diffusion sheets. It can be used for a prism sheet or the like. Above all, it is suitable for a polarizing plate protective film and a retardation film.

Hereinafter, the present invention will be described in more detail based on Examples, but the present invention is not limited to these Examples.

The methods for measuring each physical property measured in Examples and Comparative Examples are as follows.
(Average particle size of the rubber part of the multilayer structure particles)
Using a sample obtained by diluting the obtained polymer latex to a solid content concentration of 0.02% as a sample, using a U-5100 type ratio beam spectrophotometer manufactured by Hitachi High-Technologies Corporation, light scattering with a wavelength of 546 nm was used. I asked for it.
(Glass-transition temperature)
Using the differential scanning calorimetry (DSC) SSC-5200 manufactured by Seiko Instruments, the sample was once heated to 200 ° C. at a rate of 25 ° C./min, held for 10 minutes, and then held at a rate of 25 ° C./min to 50 ° C. After preliminary adjustment to lower the temperature, the measurement was performed while the temperature was raised to 200 ° C at a heating rate of 10 ° C / min, the integrated value was obtained from the obtained DSC curve (DDSC), and the glass transition temperature was obtained from the maximum point. Asked.
(Melting viscosity)
Using a capillary rheometer, the melt viscosity of the pellets was measured under the conditions of the resin temperature at the extruder outlet in each example and comparative example and the shear rate of 122 sec ^-1 .
(Static friction coefficient)
A surface measuring machine (TYPE 14 manufactured by Shinto Kagaku Co., Ltd.) was used. The measurement conditions were a load of 200 g and an FS of 50%, and the friction coefficient between films having a length of 6 cm and a width of 5 cm (combination of front to back in the center and front to back in the end) was measured.
(Rolling deviation)
The deviation of the end of the rolled-up film roll is measured with a caliper, and it is evaluated as 1 mm or less (◎), larger than 1 mm and 3 mm or less slightly generated (○), and larger than 3 mm (×). did.
(Defect caused by blocking)
When a high-brightness light is applied to the rolled-up film roll from the edge, no color shading is observed (◎), and slight color shading is observed (○), high-brightness light. The case where the shade of color is observed under a fluorescent lamp without using is regarded as (x).

<Manufacturing Example 1: Production of Acrylic Resin (A1)>
In Production Example 1, an acrylic resin (A1), which is a glutarimide acrylic resin, was produced using polymethyl methacrylate (A2) as a raw material resin and monomethylamine as an imidizing agent.
In this production, a tandem type reaction extruder in which two extrusion reactors were arranged in series was used.
Regarding the tandem type reaction extruder, both the first extruder and the second extruder have a diameter of 75 mm and an L / D (ratio of the length L of the extruder to the diameter D) of 74, which is a meshing type isodirectional twin-screw extruder. Was used to supply the raw material resin to the raw material supply port of the first extruder using a constant weight feeder (manufactured by Kubota Co., Ltd.).
The degree of decompression of each vent in the first extruder and the second extruder was −0.095 MPa. Further, a pressure control mechanism inside the component that connects the first extruder and the second extruder with a pipe having a diameter of 38 mm and a length of 2 m, and connects the resin discharge port of the first extruder and the raw material supply port of the second extruder. Used a constant flow pressure valve.
The resin (strand) discharged from the second extruder was cooled by a cooling conveyor and then cut with a pelletizer into pellets. Here, in order to adjust the pressure inside the component connecting the resin discharge port of the first extruder and the raw material supply port of the second extruder, or to determine the extrusion fluctuation, the discharge port of the first extruder, the first extruder, and the first extruder are used. A resin pressure gauge was provided at the center of the connecting parts between the two extruders and at the discharge port of the second extruder.
In the first extruder, polymethyl methacrylate resin (Mw: 105,000) was used as a raw material resin, and monomethylamine was used as an imidizing agent to produce an imide resin intermediate 1. At this time, the temperature of the maximum temperature part of the extruder was 280 ° C., the screw rotation speed was 55 rpm, the amount of the raw material resin supplied was 150 kg / hour, and the amount of monomethylamine added was 2.0 parts with respect to 100 parts of the raw material resin. The constant flow pressure valve was installed immediately before the raw material supply port of the second extruder, and the pressure at the monomethylamine press-fitting portion of the first extruder was adjusted to 8 MPa.
In the second extruder, the imidizing agent and by-products remaining in the rear vent and the vacuum vent were devolatile, and then dimethyl carbonate was added as an esterifying agent to produce an imide resin intermediate 2. At this time, the barrel temperature of the extruder was 260 ° C., the screw rotation speed was 55 rpm, and the amount of dimethyl carbonate added was 3.2 parts with respect to 100 parts of the raw material resin. Further, the esterifying agent was removed by venting, extruded from the strand die, cooled in a water tank, and then pelletized with a pelletizer to obtain an acrylic resin (A1).
The obtained acrylic resin (A1) is an acrylic resin obtained by copolymerizing a glutamilimide unit and a (meth) acrylic acid ester unit.

<Manufacturing Example 2: Production of rubber particles (B1)>
In Production Example 2, rubber particles (B1), which are non-slip particles, were produced.
The following substances were charged into an 8 L polymerization apparatus equipped with a stirrer.
Deionized water 200 parts Polyoxyethylene lauryl ether Sodium phosphate 0.05 parts Sodium formaldehyde Sulfoxylate 0.11 parts Ethethylenediamine tetraacetate-2-sodium 0.004 parts Ferrous sulfate 0.001 parts In-polymerizer Was sufficiently replaced with nitrogen gas to make it substantially oxygen-free, and then the internal temperature was adjusted to 40 ° C., and the raw material mixture of acrylic rubber particles (rubber particles) (90% butyl acrylate, 10% methyl methacrylate) was used. To 45 parts by weight of the monofunctional monomer composed of the above, 0.45 parts of allyl methacrylate and 0.041 parts of cumene hydroperoxide) 45.491 parts were continuously added over 225 minutes. 20 minutes, 40 minutes, and 60 minutes after the start of addition of the raw material mixture, sodium polyoxyethylene lauryl ether phosphate (polyoxyethylene lauryl ether phosphoric acid (manufactured by Toho Chemical Industry Co., Ltd., trade name: Phosphanol RD-510Y) 0.2 parts each of the sodium salt) was added to the polymerization machine. After the addition was completed, the polymerization was continued for another 0.5 hours to obtain rubber parts particles. The polymerization conversion rate was 98.6%.
Then, the internal temperature was adjusted to 60 ° C., 0.2 part of sodium formaldehyde sulfoxylate was charged, and then the raw material mixture of the shell layer (methyl methacrylate 57.8%, butyl acrylate 4%, benzyl methacrylate 38) was charged. To 55 parts by weight of the monofunctional monomer composed of .2%, 0.3 parts of t-dodecyl mercaptan and 0.254 parts of cumenehydroperoxide) were continuously added over 210 minutes. Polymerization was continued for another hour to obtain a graft copolymer latex (rubber particles having a core-shell structure). The polymerization conversion rate was 100.0%. The obtained latex was salted out with magnesium sulfate, coagulated, washed with water, and dried to obtain white powdery rubber particles (B1).
The average particle size of the rubber particles (B1) was 121 nm. The graft ratio of the rubber particles (B1) was 56%.

<Production Example 3: Production of Multilayer Particles (B2)>
In Production Example 3, multilayer structure particles (B2), which are slippery particles that impart slipperiness to the film, were produced.
The following substances were charged into a glass reactor.
Ion-exchanged water 125 parts Boric acid 0.47 parts Sodium carbonate 0.05 parts Polyoxyethylene lauryl ether phosphoric acid 0.0042 parts After sufficiently replacing the inside of the polymerization machine with nitrogen gas, the internal temperature is set to 80 ° C. and the monomer is used. 25% of the mixture consisting of 17.5 parts (3% n-butyl acrylate, 97% methyl methacrylate), 0.17 parts allyl methacrylate and 0.065 parts t-butyl hydroperoxide was collectively put into a polymerization machine. After that, 0.00645 parts of 5% sodium formaldehyde sulfoxypolymer, 0.0056 parts of ethylenediaminetetraacetate-2-sodium, and 0.0014 parts of ferrous sulfate were added, and 15 minutes later, t-butyl was added. 0.022 part of hydroperoxide was added, and the polymerization was continued for another 15 minutes. Then, 0.013 parts of a 2% aqueous sodium hydroxide solution was added. The remaining 75% was added continuously over 30 minutes. 30 minutes after the completion of the addition, 0.0069 parts of 69% t-butyl hydroperoxide was added and kept at the same temperature for 30 minutes to complete the polymerization. The polymerization conversion rate was 98%.
Then, the obtained polymer latex was kept at 80 ° C. in a nitrogen stream, and 0.0346 parts of sodium hydroxide and 0.0519 parts of potassium persulfate were added. Then, a mixture consisting of 32.5 parts of monomer (82% n-butyl acrylate, 18% styrene), 0.97 part of allyl methacrylate and 0.3 part of polyoxyethylene lauryl ether phosphoric acid was continuously added over 74 minutes. did. It was then held for 45 minutes to complete the polymerization. The average particle size of the obtained polymer was 260 nm, and the polymerization conversion rate was 99%.
Further, the obtained polymer latex was kept at 80 ° C., 0.0097 parts of potassium persulfate and 0.05 parts of sodium hydroxide were added, and then 50 parts of a monomer (90% methyl methacrylate, n-butyl acrylate). A mixture consisting of 10%) was added continuously over 150 minutes. After the addition of the mixture was completed, the mixture was held for 1 hour to obtain a latex of multilayer structure particles (B2).
The average particle size of the multilayer structure particles was 380 nm, and the polymerization conversion rate was 99%.
The latex of the obtained multilayer structure particles was salted out with magnesium sulfate, solidified, washed with water, and dried to obtain white powdery multilayer structure particles (B2).

<Manufacturing Example 4: Production of Resin Pellets (C1)>
Using a twin-screw extruder with a diameter of 75 mm, the temperature control zone of the extruder is set to 255 ° C., the screw rotation speed is 70 rpm, 85 parts by weight of acrylic resin (A1), and white powdery rubber particles (B1) 15. A mixture of 0.5 parts by weight and 0.5 parts by weight of the white powdery multilayer structure particles (B2) was supplied at a rate of 150 kg / hr. The resin that came out as a strand from the die provided at the outlet of the extruder was cooled in a water tank and pelletized with a pelletizer. The melt viscosity of the obtained resin pellet (C1) was measured as described above.

<Manufacturing Example 5: Production of resin pellets (C2)>
Resin pellets (C2) were obtained in the same manner as in Production Example 4 except that the acrylic resin (A1) in Production Example 4 was changed to the acrylic resin (A2) which is polymethylmethacrylate (PMMA). The melt viscosity of the obtained resin pellet (C2) was measured as described above.

<Manufacturing Example 6: Production of resin pellets (C3)>
Resin pellets (C3) were obtained in the same manner as in Production Example 5, except that white powdery multilayer structure particles (B2) were not used. The melt viscosity of the obtained resin pellet (C3) was measured as described above.

<Manufacturing Example 7: Production of resin pellets (C4)>
Resin pellets (C4) were obtained in the same manner as in Production Example 5, except that white powdery rubber particles (B1) were not used. The melt viscosity of the obtained resin pellet (C4) was measured as described above.

<Example 1>
As the thermoplastic resin composition, the resin pellets (C2) (glass transition temperature Tg 119 ° C.) obtained in Production Example 5 were used, dried at 80 ° C. for 4 hours in a dryer, and then supplied to a φ90 mm single-screw extruder. did. Screen meshes were placed at the extruder outlet in the order of # 40, # 100, # 400, # 400, # 100, # 40 from the extruder side. The resin was heated and melted at the extruder outlet so that the resin temperature became 250 ° C., and the molten resin was extruded into a T-die having a width of 1850 mm via a gear pump. At this time, as the resin temperature at the T-die outlet, the resin temperature of the part is 275 ° C. when the range of 150 mm from the end is the end, and the resin temperature of the part is 260 when the other part is the center. The die set temperature was adjusted to ℃. At this time, the melt viscosity (122sec ^-1 ) at the central portion was 9000 poise, and the melt viscosity (122sec ^-1 ) at the end portion was 3500 poise.
The discharged molten resin is taken up at a line speed of 15 m / min, sandwiched between a cast roll whose temperature is adjusted to 100 ° C. and a touch roll whose temperature is adjusted to 100 ° C., cooled and solidified, and then taken up by a take-up roll and a winding core. The end portion of 200 mm was slit in the front, and a film raw fabric having a thickness of 60 μm was obtained on the take-up core. At this time, no meandering of the film before the slit was observed, no cracks or chips were generated at the slit portion, and no blocking-induced defects were observed when the film was wound, resulting in a good winding shape.
When the static friction coefficient of the product (center part) and the slit end (end part) of the film being conveyed was measured, it was 0.4 at the center part and 0.8 at the end part.

<Example 2>
As the thermoplastic resin composition, the resin pellets (C1) (glass transition temperature Tg 121 ° C.) obtained in Production Example 4 are used, dried at 80 ° C. for 4 hours in a dryer, and then supplied to a φ90 mm single-screw extruder. did. Screen meshes were placed at the extruder outlet in the order of # 40, # 100, # 400, # 400, # 100, # 40 from the extruder side. At the outlet of the extruder, the resin was heated and melted to a temperature of 250 ° C., and the molten resin was extruded into a T-die having a width of 1850 mm via a gear pump. At this time, as the resin temperature at the T-die outlet, the resin temperature of the part is 260 ° C. when the range of 150 mm from the end is the end, and the resin temperature of the part is 250 when the other part is the center. The die set temperature was adjusted to ℃. At this time, the melt viscosity (122sec ^-1 ) at the central portion was 15,000 poise, and the melt viscosity (122sec ^-1 ) at the end portion was 9000 poise.
The discharged molten resin is taken up at a line speed of 15 m / min, sandwiched between a cast roll whose temperature is adjusted to 100 ° C. and a touch roll whose temperature is adjusted to 100 ° C., cooled and solidified, and then taken up by a take-up roll and a winding core. The end portion of 200 mm was slit in the front, and a film raw fabric having a thickness of 60 μm was obtained on the take-up core. At this time, no meandering of the film before the slit was observed, no cracks or chips were generated at the slit portion, and no blocking-induced defects were observed when the film was wound, resulting in a good winding shape.
When the static friction coefficient of the product (center part) and the slit end (end part) of the film being conveyed was measured, it was 0.3 at the center part and 0.8 at the end part.

<Example 3>
As the thermoplastic resin composition, the resin pellets (C4) (glass transition temperature Tg 119 ° C.) obtained in Production Example 7 were used, dried at 80 ° C. for 4 hours in a dryer, and then supplied to a φ90 mm single-screw extruder. did. Screen meshes were placed at the extruder outlet in the order of # 40, # 100, # 400, # 400, # 100, # 40 from the extruder side. At the outlet of the extruder, the resin was heated and melted to a temperature of 250 ° C., and the molten resin was extruded into a T-die having a width of 1850 mm via a gear pump. At this time, as the resin temperature at the T-die outlet, the resin temperature of the part is 271 ° C. when the range of 150 mm from the end is the end, and the resin temperature of the part is 260 when the other part is the center. The die set temperature was adjusted to ℃. At this time, the melt viscosity (122 sec ^-1 ) at the central portion is 9000 poise, and the melt viscosity (122 sec ^-1 ) at the end portion is 4000 poise.
The discharged molten resin is taken up at a line speed of 15 m / min, sandwiched between a cast roll whose temperature is adjusted to 100 ° C. and a touch roll whose temperature is adjusted to 100 ° C., cooled and solidified, and then taken up by a take-up roll and a winding core. The end portion of 200 mm was slit in the front, and a film raw fabric having a thickness of 60 μm was obtained on the take-up core. At this time, no meandering of the film before the slit was observed, and no defect due to blocking was observed when the film was wound, but chips were generated at the slit portion and resin powder was attached to the end of the film winding.
When the static friction coefficient of the product (center portion) and the slit end (end portion) of the film being conveyed was measured, it was 0.5 at the center portion and 0.9 at the end portion.

<Example 4>
Manufactured in the same manner as in Example 2 except that after sandwiching between the cast roll and the touch roll, only the film end (corresponding to the position of the end 200 mm on the T die before neck-in) was additionally sandwiched at the lower part of the cast roll. Then, a 60 μm film raw material was obtained.
At this time, no meandering of the film before the slit was observed, and no defect due to blocking was observed when the film was wound, but chips were generated at the slit portion and resin powder was attached to the end of the film winding.
When the static friction coefficient of the product (center portion) and the slit end (end portion) of the film being conveyed was measured, it was 0.5 at the center portion and 1.2 at the end portion.

<Example 5>
It was produced in the same manner as in Example 1 except that the cast roll temperature was 110 ° C., and a 60 μm film raw fabric was obtained. At this time, no cracks or chips were generated in the slit portion, but a defect caused by blocking occurred when the film was wound, and the film before the slit meandered slightly, resulting in a slight winding deviation.
When the coefficient of static friction of the product (center part) and the slit end (end part) of the film being conveyed was measured, it was 0.8 at the center part and 0.9 at the end part.

<Example 6>
As the resin temperature at the T-die outlet, the resin temperature of the part is 265 ° C. when the range of 150 mm from the end is the end part, and the resin temperature of the part is 260 ° C. when the other part is the central part. The die was manufactured in the same manner as in Example 1 except that the set temperature of the die was adjusted (at this time, the melt viscosity (122 sec ^-1 ) at the center was 9000 poise and the melt viscosity (122 sec ^-1 ) at the end was 7,000 poise). Then, a 60 μm film raw fabric was obtained. Further, at this time, no cracks or chips were generated in the slit portion, and although no defect due to blocking was generated, the film before the slit meandered slightly, and a slight winding deviation occurred.
When the static friction coefficient of the product (center part) and the slit end (end part) of the film being conveyed was measured, it was 0.4 at the center part and 0.6 at the end part.

<Comparative example 1>
The thermoplastic resin was produced in the same manner as in Example 3 except that the resin pellet (C4) was changed to a pellet of an acrylic resin (A2) (glass transition temperature Tg119 ° C.) which is a polymethylmethacrylate resin (PMMA). , 60 μm film raw fabric was obtained. At this time, no meandering of the film before the slit was observed, but a defect due to blocking occurred when the film was wound, chips were generated at the slit portion, and resin powder adhered to the end of the film winding.
When the friction coefficient of the product (center part) and the slit end (end part) of the film being conveyed was measured, it was 1.8 at the center part and 1.9 at the end part.

<Comparative example 2>
The thermoplastic resin was produced in the same manner as in Example 2 except that the resin pellet (C1) was changed to the resin pellet (C3) (glass transition temperature Tg 119 ° C.), and a 60 μm film raw fabric was obtained. At this time, no meandering of the film before the slit was observed, and no cracks or chips were generated at the slit portion, but a defect due to blocking occurred when the film was wound.
When the coefficient of static friction of the product (center portion) and the slit end (end portion) of the film being conveyed was measured, it was 1.2 at the center portion and 1.2 at the end portion.

<Comparative example 3>
A film was produced in the same manner as in Example 1 except that the cast roll temperature was set to 75 ° C., but the film could not be produced due to pinching omission.

<Comparative example 4>
As the resin temperature at the T-die outlet, the resin temperature of the part is 260 ° C. when the range of 150 mm from the end is the end part, and the resin temperature of the part is 260 ° C. when the other part is the central part. The same as in Example 1 was produced except that the set temperature of the die was adjusted as described above (at this time, the melt viscosity (122 sec ^-1 ) was 9000 poise at both the central portion and the end portion), and a film raw fabric of 60 μm was obtained. .. At this time, no cracks or chips were generated in the slit portion, and although there was no defect caused by blocking, meandering of the film before the slit occurred and winding misalignment occurred.
When the static friction coefficient of the product (center portion) and the slit end (end portion) of the film being conveyed was measured, it was 0.4 at the center portion and 0.4 at the end portion.

Table 1 summarizes the results of Examples and Comparative Examples. The CR temperature in Table 1 is the cast roll temperature.

According to the embodiment, in a method for producing an optical film in which a film-like melt of a thermoplastic resin composition containing slippery particles is discharged from a die outlet of an extruder and sandwiched between a pair of rolls including a cast roll. The temperature of the film-like melt at the die outlet is raised in the high temperature region (both ends) by 5 ° C. or more than in the low temperature region (both ends), and the temperature of the cast roll is Tg-40 ° C. or higher and Tg-5 ° C. or lower (Tg). Is the glass transition temperature of the thermoplastic resin composition), it can be seen that the occurrence of winding misalignment and the occurrence of blocking-induced defects can be suppressed.
According to Comparative Examples 1 and 2, when the thermoplastic resin composition does not contain slippery particles, the temperature of the film-like melt at the die outlet and the temperature of the cast roll meet the predetermined requirements, but the cause is blocking. It can be seen that the occurrence of defects cannot be suppressed.
According to Comparative Example 3, when the temperature of the cast roll is excessively low, pinching and pulling out is likely to occur, and it is difficult to produce a film well.
According to Comparative Example 4, even when a thermoplastic resin composition containing slippery particles is used, if the temperature distribution in the width direction of the film-like melt is uniform at the die outlet, winding deviation occurs. It turns out that it is difficult to suppress.

10 Extruder 11 T Die 12 Die Outlet 13 Film-like melt 14 Elastic roll 15 Cast roll

Claims (8)

A method for producing an optical film in which a film-like melt of a thermoplastic resin composition containing slippery particles is discharged from a die outlet of an extruder and sandwiched between a pair of rolls including a cast roll.
The temperature of the film-like melt at the die outlet is set to be 5 ° C. or more higher than the other low-temperature regions in one or more high-temperature regions in the width direction of the film-like melt.
The temperature of the cast roll is set to Tg-40 ° C. or higher and Tg-5 ° C. or lower (Tg is the glass transition temperature of the thermoplastic resin composition) .
The slippery particles include multilayer structure particles.
Wherein the multilayer structure grains, method of degree of crosslinking to have a rubber portion is 2.3 wt% or more and 4.0 wt% or less. The method according to claim 1, wherein the temperature in the high temperature region is 10 ° C. or more higher than the temperature in the low temperature region. The method according to claim 1 or 2, wherein the temperature of the cast roll is Tg-15 ° C. or lower. The method according to any one of claims 1 to 3 , wherein the thermoplastic resin contains an acrylic resin. The method according to any one of claims 1 to 4 , wherein the thermoplastic resin composition contains rubber particles in an amount of 5 parts by weight or more and 25 parts by weight or less with respect to 100 parts by weight of the thermoplastic resin composition. The method according to any one of claims 1 to 5 , wherein the high temperature region exists in two or more in the width direction of the film-like melt. The method according to claim 6 , wherein the high temperature region includes both ends in the width direction of the film-like melt. An optical film containing a thermoplastic resin.
The optical film contains slippery particles
The slippery particles include multilayer structure particles.
The multilayer structure particles have a rubber portion having a degree of cross-linking of 2.3% by weight or more and 4.0% by weight or less.
An optical film having a coefficient of static friction at both ends in the width direction of the optical film of 0.4 or more and 0.1 or more higher than the coefficient of static friction of the central portion in the width direction of the optical film.

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