JP7217177B2 - Film manufacturing method - Google Patents

Description

The present invention relates to a film manufacturing method.

Unstretched or biaxially stretched acrylic films obtained by melt extrusion molding have excellent transparency, moisture barrier properties, dimensional stability, chemical resistance, and surface hardness, so they are used as films for various applications. there is

Such films, especially optical films, are used as polarizer protective films for liquid crystal displays and surface protective films for organic EL displays. Since it will be lowered, it is desired that there are as few small scratches as possible.

For example, in Patent Document 1, when winding a film out of a tenter onto a roll, all rolls have a film speed Vf (m/min), a roll peripheral speed Vr (m/min), a roll diameter D (m/ min), the embrace angle α (rad) satisfies both 1.001<Vr/Vf<1.010 and αD(Vr/Vf−1)/2<0.5.

Further, Patent Document 2 discloses a method for producing a polyester optical film in which the number of scratches having a length of 20 mm or more and a maximum depth of 0.5 μm or more is 10/m ² or less by having a surfactant on the film surface. disclosed.

JP 2010-254395 A JP-A-9-183201

However, in Patent Document 1, when a problem occurs in the bearing, the rotation resistance of the roll increases, so the peripheral speed of the roll becomes slower than the film speed, and scratches may occur. In particular, films with low frictional resistance tend to have low adhesion to rolls and tend to be easily scratched. In addition, if the roll is of the drive type, the cost of the device will be high. In addition, the method for producing a polyester optical film described in Patent Document 2 requires a precision coater and a dryer for applying the surfactant, which increases the unit production cost of the product and lengthens the production line. Various coatings can have adverse effects in post-processing.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method of manufacturing a film that can reduce minute scratches that occur during the process of transporting and winding the film.

In order to achieve the above object, the present inventors have made intensive studies, and as a result, have completed the present invention including the following aspects.

That is, the present invention provides the following [1] to [9].
[1] A film manufacturing method comprising a step of passing the film through a plurality of free rolls in the steps from transporting the film to winding it, wherein the plurality of free rolls are all of the following formula (1 ) is satisfied.
t×d×3.14×α/360≧83 (1)
(In the formula, t is the time (seconds) until the free roll stops when the roll rotation speed is 53 rpm, d is the diameter of the free roll (cm), and α is the embrace angle (deg).)
[2] The method for producing a film according to [1] above, wherein the free roll has a steel or aluminum core and hard chrome plating applied to the surface of the core.
[3] The method for producing a film according to [1] or [2] above, wherein the free roll has a surface roughness (Ra) of 0.8 μm or less.
[4] The method for producing a film according to any one of [1] to [3] above, wherein the free roll has a surface temperature of 15 to 35°C.
[5] The method for producing a film as described in any one of [1] to [4] above, wherein the film is an acrylic resin film.
[6] The method for producing a film according to any one of [1] to [5] above, wherein the film has a storage modulus at 25° C. of 1 GPa or more.
[7] The method for producing a film according to any one of [1] to [6], wherein the film has a thickness of 10 to 300 μm.
[8] The method for producing a film according to any one of [1] to [7] above, wherein the film is produced by melt extrusion.
[9] The method for producing a film according to any one of [1] to [8] above, wherein the film is a biaxially stretched film stretched 2.25 to 6.25 times.

ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the film which can reduce the fine scratch which arises in the process from conveyance to winding of a film can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic diagram which shows one Embodiment of the apparatus used with the manufacturing method of the film of this invention. FIG. 4 is a schematic diagram showing another embodiment of the apparatus used in the film manufacturing method of the present invention. FIG. 10 is a process drawing showing a biaxial stretching process in Example 8. FIG.

An example of an embodiment to which the present invention is applied will be described below. Numerical values specified in this specification are values determined by the methods disclosed in the embodiments or examples. It should be noted that other embodiments are also included in the scope of the present invention as long as they match the gist of the present invention.

The film manufacturing method of the present invention is a film manufacturing method comprising a step of passing the film through a plurality of free rolls in the steps from film transport to winding, wherein the plurality of free rolls are Both are characterized by satisfying the following formula (1).
t×d×3.14×α/360≧83 (1)
(Wherein, t is the time until the free roll stops when the roll rotation speed is 53 rpm (roll rotation time) (seconds), d is the diameter of the free roll (cm), and α is the embrace angle (deg). show.)

FIG. 1 is a schematic diagram showing one embodiment of an apparatus used in the film manufacturing method of the present invention, and FIG. 2 is a schematic diagram showing another embodiment of the apparatus used in the film manufacturing method of the present invention. is.
As shown in FIG. 1, the film material kneaded by the extruder 1 is heated and melted by the extruder 1, then extruded in the form of a film from a T-die 4, and the polishing roll 5 of the forming roll whose surface is mirror-finished. , 6, 7, pressed and cooled to be molded. The molded film further passes between nip rolls 8, 8', free rolls 9, 10, 11, 12, and nip rolls 13, 13' in order, and is wound up by winder roll . In FIG. 1, the free roll 10 is a movable free roll that can move up and down, and by changing the position of the free roll 10, the embracing angles of the free rolls 9, 10, and 11 can be adjusted.
A gear pump 2 and a polymer filter 3 may be arranged between the extruder 1 and the T-die 4 .
Further, as shown in FIG. 2, when the film is stretched, a stretching machine 15 such as a simultaneous biaxial stretching machine is arranged between the nip roll 8 and the free roll 9 to stabilize the film width. Alternatively, the static electricity applying device 16 may be arranged at a position where static electricity can be applied to the film material passing through the polishing roll 6 .

The extruder 1 is not particularly limited, and known extruders such as a single-screw extruder, twin-screw extruder, and multi-screw extruder can be used.

The film is obtained by molding the kneaded film material in the extruder 1 . A molding method is not particularly limited. For example, known molding methods such as extrusion molding (T-die method, etc.), inflation molding, blow molding, calender molding, and cast molding can be employed, and extrusion molding is preferably employed. Extrusion methods, particularly T-die methods, can provide films with improved toughness, excellent handleability, and a good balance of toughness, surface hardness, and stiffness. The extruder 1 used in the extrusion method, particularly the T-die method, preferably has a single screw or a twin screw. Moreover, from the viewpoint of suppressing coloration of the film, it is preferable to perform melt extrusion under reduced pressure using a vent. Further, from the viewpoint of obtaining a film of uniform thickness, it is preferable to connect a gear pump 2 to the extruder 1 and melt-extrude through a polymer filter 3 in order to reduce fish eye defects. Furthermore, from the viewpoint of suppressing oxidative deterioration, it is preferable to carry out melt extrusion under a nitrogen stream. The temperature of the material discharged from the extruder 1 is preferably 220-290°C, more preferably 230-280°C.

The polishing rolls 5, 6 and 7 are preferably mirror-finished rolls, more preferably mirror-finished metal elastic rolls or mirror-finished metal rigid rolls. The linear pressure between the mirror surface rolls is preferably 10 N/mm or more, more preferably 30 N/mm or more, from the viewpoint of the surface smoothness of the resulting film. The surface temperature of the specular roll is preferably 60° C. or higher, more preferably 70° C. or higher, from the viewpoint of the surface smoothness, haze, appearance, etc. of the resulting film. Also, it is preferably 130° C. or lower, more preferably 110° C. or lower.

The nip rolls 8, 8', 13, 13' are rotatable rolls that provide a driving force for transporting the film. Examples of nip rolls include rubber rolls and metal rolls.

The free rolls 9, 10, 11 and 12 are rolls that are not driven by themselves and are used for transporting the film. All free rolls used in the process from transporting the film to winding it satisfy the following formula (1).
t×d×3.14×α/360≧83 (1)
In the formula, t is the time (seconds) until the free roll stops after rotating the roll rotation speed to 53 rpm without winding the film, d is the diameter of the free roll (cm), and α is the embrace angle (deg). represents If the left-hand side of the above formula (1) is less than 83, the film may be more likely to be scratched, resulting in poor appearance. From such a viewpoint, the left side of the above formula (1) is preferably 86 or more, more preferably 180 or more, and even more preferably 500 or more.
Although the upper limit of the left side of the above formula (1) is not particularly limited, it is usually 5,000.

If all the free rolls used in the process from transporting to winding the film satisfy the above formula (1), there is no limit to the time t (seconds) until the free rolls, which are rotated at a roll rotation speed of 53 rpm, stop. However, the longer the time, the more the roll can be rotated without resistance, so it is preferably 5 seconds or more, more preferably 10 seconds or more, and even more preferably 20 seconds or more.
The upper limit of the time (t) (seconds) until the free roll stops after rotating at a roll rotation speed of 53 rpm is not particularly limited, but is usually 500 seconds.

All the free rolls used in this step are not limited in diameter as long as they satisfy the above formula (1). If the diameter is 8 cm or more, the contact distance becomes longer even if the holding angle is the same, making it easier to apply torque and less likely to cause scratches on the film. Further, if the diameter is 25 cm or less, when a lightweight aluminum roll is used, slippage between the roll and the film is suppressed, and the film is less likely to be scratched.

As long as all the free rolls used in this step satisfy the above formula (1), there is no restriction on the embrace angle of the free roll, but it is preferably 10 deg or more, more preferably 15 deg or more, and 20 deg or more. is more preferred. The upper limit is preferably 160 deg. By setting the holding angle to 10 degrees or more, it is possible to suppress the slippage that occurs between the roll and the film.

The free roll preferably has a steel or aluminum core and hard chrome plating applied to the surface of the core. A cost reduction can be achieved if the core material is steel or aluminum. Particularly preferred are lightweight rolls made of an aluminum core. Further, by applying hard chromium plating to the surface of the core material, wear resistance, corrosion resistance, and releasability can be improved.

The surface roughness (Ra) of the free roll is preferably 0.8 μm or less, more preferably 0.5 μm or less, and still more preferably 0.1 μm or less, because it affects the damage to the film, Even more preferably, it is 0.05 μm or less.
The surface roughness (Ra) can be measured according to JIS B0601:2001, and specifically by the method described in Examples.

The surface temperature of the free roll is preferably 15-35°C. When the surface temperature of the free roll is lower than 15° C., water droplets are formed on the roll surface due to dew condensation, and the water droplets may adhere to the film and contaminate the film surface. On the other hand, when the temperature of the free roll is higher than 35°C, the adhesion between the film and the roll increases and the slippage of the film is improved. This is not preferable because it makes it easier to Further, when the film is wound on a roll while the temperature is high, the film shrinks as the temperature of the film decreases when left at room temperature, which may cause winding defects such as web buckling.

The film may be formed into a film shape and then stretched. The stretching process improves the mechanical strength of the film and makes it less likely to crack. The stretching treatment is performed by heating and stretching the film before stretching in the MD direction (machine direction, length direction, extrusion direction in film production) and TD direction (width direction perpendicular to the machine direction). Specifically, a plurality of clips are used to hold the film before stretching at regular intervals, convey it into a heating furnace, and then stretch it by simultaneously pulling it in the MD and TD directions in the stretching furnace. Thereafter, by cooling the film in a cooling furnace, a stretched film can be obtained continuously. Further, heat setting is preferably performed after the stretching treatment. A film with less thermal shrinkage can be obtained by heat setting.

The stretching method is not particularly limited, and includes a simultaneous biaxial stretching method, a sequential biaxial stretching method, a tubular stretching method, and the like. The temperature during stretching is preferably equal to or higher than the glass transition temperature of the film material, and preferably equal to or lower than the temperature higher than the glass transition temperature of the material by 50°C. If the film material has multiple glass transition temperatures, the highest value is taken as the basis for such stretching temperature. The drawing speed is preferably 100 to 5000%/min.

Further, the draw ratio is preferably 2.25 to 6.25 times, more preferably 2.3 to 5.6 times in each of the MD and TD directions, from the viewpoint of mechanical strength and resistance to cracking. be.

The production method of the present invention is suitably applied to films made of thermoplastic resin compositions. The thermoplastic resin contained in the thermoplastic resin composition is not particularly limited, and examples thereof include polycarbonate; Group vinyl resins or their hydrogenated products; Amorphous polyolefins, transparent polyolefins with fine crystal phases, olefin resins such as ethylene-methyl methacrylate resins; (Meth)acrylic resins; Polyethylene terephthalate, cyclohexanedimethanol Ester-based resins such as polyethylene terephthalate, polyethylene naphthalate, and polyarylate partially modified with or isophthalic acid; amide-based resins; imide-based resins; ether sulfone-based resins; cellulose-based resins such as triacetyl cellulose resins; (Meth)acrylic resins are preferred from the viewpoint of transparency and moldability.
In this specification, (meth)acrylic resin refers to methacrylic resin and acrylic resin.

<(Meth) acrylic resin (A)>
The (meth)acrylic resin (A) contained in the thermoplastic resin composition constituting the film is not particularly limited as long as it is a resin having a structural unit derived from a (meth)acrylic acid ester. From the viewpoint of improvement, for example, those mainly composed of structural units derived from methyl methacrylate are preferable. When the (meth)acrylic resin (A) is mainly composed of structural units derived from methyl methacrylate, the content thereof is preferably 50% by mass or more, preferably 80% by mass, from the viewpoint of improving heat resistance. It is more preferably at least 90% by mass, even more preferably at least 95% by mass, particularly preferably at least 98% by mass, and all structural units are methyl methacrylate It may be a unit.

The (meth)acrylic resin (A) may contain structural units derived from monomers other than methyl methacrylate. Other monomers are not particularly limited as long as they are copolymerizable with methyl methacrylate. Examples include methyl acrylate, ethyl acrylate, n-propyl acrylate, iso-propyl acrylate, n-butyl acrylate, iso-butyl acrylate, sec-butyl acrylate, tert-butyl acrylate, amyl acrylate, isoamyl acrylate, n-hexyl acrylate, 2-ethylhexyl acrylate, pentadecyl acrylate, dodecyl acrylate, acrylic Acrylics such as phenyl acid, benzyl acrylate, phenoxyethyl acrylate, 2-hydroxyethyl acrylate, 2-ethoxyethyl acrylate, glycidyl acrylate, allyl acrylate, cyclohexyl acrylate, norbornyl acrylate, isobornyl acrylate, etc. Acid ester; ethyl methacrylate, n-propyl methacrylate, iso-propyl methacrylate, n-butyl methacrylate, iso-butyl methacrylate, sec-butyl methacrylate, tert-butyl methacrylate, amyl methacrylate, isoamyl methacrylate , n-hexyl methacrylate, 2-ethylhexyl methacrylate, pentadecyl methacrylate, dodecyl methacrylate, phenyl methacrylate, benzyl methacrylate, phenoxyethyl methacrylate, 2-hydroxyethyl methacrylate, 2-ethoxyethyl methacrylate , glycidyl methacrylate, allyl methacrylate, cyclohexyl methacrylate, norbornyl methacrylate, isobornyl methacrylate and other methacrylic acid esters other than methyl methacrylate; Unsaturated carboxylic acids or acid anhydrides thereof; olefins such as ethylene, propylene, 1-butene, isobutylene, and 1-octene; conjugated dienes such as butadiene, isoprene, and myrcene; styrene, α-methylstyrene, p-methylstyrene, m - Aromatic vinyl compounds such as methylstyrene; acrylamide, methacrylamide, acrylonitrile, methacrylonitrile, vinyl acetate, vinylpyridine, vinyl ketone, vinyl chloride, vinylidene chloride, vinylidene fluoride and the like.
Among these, acrylic acid esters are preferred, and methyl acrylate, ethyl acrylate, n-propyl acrylate, iso-propyl acrylate, n-butyl acrylate, iso-butyl acrylate, and sec-acrylate. Butyl is more preferred.
The (meth)acrylic resin (A) used in the present invention may be used alone or in combination of two or more.

The (meth)acrylic resin (A) is a polymer containing a structural unit derived from methyl methacrylate and a structural unit derived from a compound having a ring structure in the molecule such as maleic anhydride. good too. By containing a structural unit derived from a compound having a ring structure in the molecule, the (meth)acrylic resin (A) and the resulting film are improved in heat resistance. When the (meth)acrylic resin (A) contains a structural unit derived from a compound having a ring structure in the molecule, the (meth)acrylic resin (A) of the structural unit derived from the compound having a ring structure in the molecule ) is preferably 1 to 40% by mass, more preferably 1 to 20% by mass, and still more preferably 1 to 5% by mass.

The structural unit derived from a compound having a ring structure in the molecule includes a structural unit derived from a compound containing a >CH-OC(=O)- group in the ring structure, -C(=O)-OC (=O) - Structural unit derived from a compound containing a group in the ring structure, -C (= O) -N-C (= O) - Structural unit derived from a compound containing a group in the ring structure, and >CH- A structural unit derived from a compound containing an O—CH< group in the ring structure is preferred. A structural unit derived from a compound having a cyclic structure in the molecule is obtained by combining a cyclic monomer having a polymerizable unsaturated carbon-carbon double bond, such as maleic anhydride, N-substituted maleimide, etc., with methyl methacrylate, etc. It can be incorporated into the (meth)acrylic resin (A) by polymerizing or by intramolecularly condensing and cyclizing part of the molecular chains of the (meth)acrylic resin (A) obtained by polymerization. can.

When the (meth)acrylic resin (A) contains a structural unit derived from a monomer other than methyl methacrylate, the content thereof is preferably 50% by mass or less, and 20% by mass or less. It is more preferably 10% by mass or less, even more preferably 5% by mass or less, and particularly preferably 2% by mass or less.

The glass transition temperature (Tg) of the (meth)acrylic resin (A) is preferably 80 to 140°C, more preferably 100 to 135°C, from the viewpoint of the balance between heat resistance and moldability. , more preferably 105 to 130°C, and particularly preferably 105 to 125°C. The glass transition temperature can be adjusted by changing the type or amount of the monomer copolymerized with methyl methacrylate, or by changing the stereoregularity by changing the polymerization temperature or the like.

The glass transition temperature can be measured according to JIS K7121:2012. That is, the (meth)acrylic resin is once heated to 200 ° C., then cooled to 30 ° C. or less, and then heated from 30 ° C. to 200 ° C. at a rate of 10 ° C./min. The midpoint glass transition temperature obtained from the DSC curve measured during the second heating can be used as the glass transition temperature of the (meth)acrylic resin.

The stereoregularity of the (meth)acrylic resin (A) is not particularly limited, and for example, isotactic, heterotactic, syndiotactic (meth)acrylic resins having stereoregularity can be used.

The (meth)acrylic resin (A) preferably has a weight average molecular weight of 60,000 to 150,000. When the weight average molecular weight is at least the lower limit, the mechanical properties are enhanced, and when it is at most the upper limit, the melt viscosity is lowered and the workability is improved. From the above viewpoint, the weight average molecular weight is more preferably 85,000 to 120,000, more preferably 90,000 to 100,000.
The weight average molecular weight of the (meth)acrylic resin (A) can be measured by the method described in Examples.

The method for producing the (meth)acrylic resin (A) is not particularly limited, and it can be obtained, for example, by polymerizing monomers mainly composed of methyl methacrylate. The weight average molecular weight of the (meth)acrylic resin (A) can be adjusted by adjusting the amounts of the polymerization initiator and the chain transfer agent.

The polymerization initiator used for producing the (meth)acrylic resin (A) is not particularly limited as long as it generates reactive radicals. Ethylhexanoate, 1,1,3,3-tetramethylbutylperoxy 2-ethylhexanoate, tert-butyl peroxypivalate, tert-hexylperoxypivalate, tert-butyl peroxyneodecanoate , tert-hexylperoxyneodecanoate, 1,1,3,3-tetramethylbutylperoxyneodecanoate, 1,1-bis(tert-hexylperoxy)cyclohexane, benzoyl peroxide, 3,5 ,5-trimethylhexanoyl peroxide, lauroyl peroxide, 2,2′-azobis(2-methylpropionitrile), 2,2′-azobis(2-methylbutyronitrile), dimethyl 2,2′-azobis (2-methylpropionate) and the like. Among these, 2,2'-azobis(2-methylpropionitrile), 2,2'-azobis(2-methylbutyronitrile), dimethyl 2,2'-azobis(2-methylpropionate) preferable.

Examples of chain transfer agents used in the production of (meth)acrylic resin (A) include n-octylmercaptan, n-dodecylmercaptan, tert-dodecylmercaptan, 1,4-butanedithiol, 1,6-hexanedithiol, and ethylene. Glycol bisthiopropionate, butanediol bisthioglycolate, butanediol bisthiopropionate, hexanediol bisthioglycolate, hexanediol bisthiopropionate, trimethylolpropane tris-(β-thiopropionate) and alkyl mercaptans such as pentaerythritol tetrakisthiopropionate. Among these, monofunctional alkylmercaptans such as n-octylmercaptan and n-dodecylmercaptan are preferred.

As the (meth)acrylic resin (A), a commercially available product may be used. /10 minutes (230°C, 37.3N)], “Parapet EH” [MFR: 1.3 g/10 minutes (230°C, 37.3N)], “Parapet HRL” [MFR: 2.0 g/10 minutes ( 230° C., 37.3 N)], “Parapet HRS” [MFR: 2.4 g/10 min (230° C., 37.3 N)] and “Parapet G” [MFR: 8.0 g/10 min (230° C., 37.3 N)] .3N)] [all trade names, manufactured by Kuraray Co., Ltd.] and the like.

The thermoplastic resin composition may contain rubber particles in addition to the thermoplastic resin. In particular, when the thermoplastic resin is (meth)acrylic resin (A), the rubber particles are preferably acrylic rubber particles (B) from the viewpoint of dispersibility. , International Publication No. 2017/204243, etc., can be used as the acrylic rubber particles (B).

<Thermoplastic resin composition>
The thermoplastic resin composition preferably contains (meth)acrylic resin (A) and acrylic rubber particles (B) ((meth)acrylic resin composition). The mass ratio [(A)/(B)] of the (meth)acrylic resin (A) and the acrylic rubber particles (B) is 5/95 from the viewpoint of moldability, film mechanical properties, and heat resistance. ~95/5, more preferably 30/70 to 90/10, even more preferably 50/50 to 85/15, more preferably 60/40 to 84/16 More preferably, it is particularly preferably from 77/23 to 83/17.

From the viewpoint of moldability and mechanical properties of the obtained film, the contents of the (meth)acrylic resin (A) and the acrylic rubber particles (B) in the (meth)acrylic resin composition are as follows. A range is preferred. That is, the (meth)acrylic resin (A) is preferably 5 to 95% by mass, more preferably 30 to 90% by mass, even more preferably 60 to 90% by mass, and the acrylic rubber The content of the particles (B) is preferably 95 to 5% by mass, more preferably 70 to 10% by mass, even more preferably 40 to 10% by mass. According to the production method of the present invention, even when the amount of acrylic rubber particles is small (for example, the content of acrylic rubber particles is 30 to 10% by mass), it is possible to suppress minute scratches.

<Additive>
The thermoplastic resin composition that constitutes the film may contain various additives as necessary within a range that does not impair the effects of the present invention. The type of additive is not particularly limited, and examples include ultraviolet absorbers, polymer processing aids, light stabilizers, antioxidants, heat stabilizers, lubricants, antistatic agents, pigments, dyes, matting agents, fillers. , impact modifiers, and plasticizers. An additive may be used individually by 1 type, and may use 2 or more types together. The additive may be an organic compound or an inorganic compound, but from the viewpoint of dispersibility in the resin composition, it is preferably an organic compound.

The storage modulus at 25° C. of the film to which the manufacturing method of the present invention is applied is preferably 1 GPa or more, more preferably 1.5 GPa or more, and even more preferably 2 GPa or more. When the storage elastic modulus at 25° C. is 1 GPa or more, it is possible to suppress the occurrence of wrinkles due to take-up tension when the film is conveyed, and the appearance can be improved.
The upper limit of the storage elastic modulus of the film at 25°C is not particularly limited, but is usually 7 GPa.
The storage modulus can be measured by the method described in Examples.

The thickness of the film is preferably 10 μm to 300 μm, more preferably 15 to 150 μm, and even more preferably 20 to 70 μm, from the viewpoint of dimensional stability of the polarizing plate and the like and reduction of color change of the liquid crystal display device. is. The thickness unevenness is preferably ±4 μm or less, more preferably ±2 μm or less, and even more preferably ±1 μm or less of the thickness in both MD and TD directions. If the thickness of the film becomes uneven, the roll on which the film is taken up becomes uneven, which causes wrinkles and scratches on the surface of the film, which degrades the quality of the film.

Since the film obtained by the production method of the present invention has few scratches, it can be suitably used for various optical members. For example, the front panel of the liquid crystal screen of terminals such as mobile phones, smartphones, tablets; light guide plate for liquid crystal, diffusion plate, back sheet, reflection sheet, polarizing film transparent resin sheet, retardation film, light diffusion film, prism sheet, optics As films for liquid crystal displays such as isotropic films, polarizer protective films, transparent conductive films, etc., around liquid crystal display devices; information equipment fields such as surface protection films; applicable to the application.

EXAMPLES The present invention will be described more specifically below with reference to examples and comparative examples. In addition, the present invention is not limited to the following examples. In addition, the present invention encompasses all aspects in which the above-described technical features such as characteristic values, forms, manufacturing methods, and uses are arbitrarily combined.
The following methods were used to measure physical properties in Examples and Comparative Examples.

(Weight average molecular weight Mw)
The weight average molecular weight (Mw) was determined by GPC (gel permeation chromatography) as a standard polystyrene equivalent molecular weight. The measuring equipment and conditions are as follows.
・ Apparatus: GPC apparatus "HLC-8320" manufactured by Tosoh Corporation
・ Separation column: Direct connection of “TSKgel SuperMultipore HZM-M” and “SuperHZ4000” manufactured by Tosoh Corporation ・ Detector: “RI-8020” manufactured by Tosoh Corporation
・Eluent: tetrahydrofuran ・Eluent flow rate: 0.35 mL/min ・Sample concentration: 8 mg/10 mL
・Column temperature: 40°C

(Glass-transition temperature)
In accordance with JIS K7121: 2012, the (meth)acrylic resin is once heated to 200 ° C., then cooled to 30 ° C. or less, and then heated from 30 ° C. to 200 ° C. at a rate of 10 ° C./min. Then, the DSC curve was measured by differential scanning calorimetry, and the midpoint glass transition temperature obtained from the DSC curve measured during the second heating was taken as the glass transition temperature.

(Average particle size)
The average particle size is obtained by diluting the latex containing the sample particles 200 times with water and using a laser diffraction scattering type particle size distribution measuring device (manufactured by Horiba, Ltd., device name “LA-950V2”) at 25 ° C. Dilutions were analyzed to determine particle size. At this time, the absolute refractive indices of the acrylic rubber particles (B-1) and water were set to 1.4900 and 1.3333, respectively.

(roll rotation time)
The roll rotation time was determined by rotating the metal free roll with no film wound with bare hands at 53 rpm or more, and then measuring the time from 53 rpm to rotation stop using a stopwatch.

(Hugging corner)
The arc of the contact portion between the film and the free roll was measured with a octopus thread, and the holding angle (deg) was obtained from the following formula (2).
Holding angle (deg) = Arc (cm) x 360/(Roll diameter (cm) x 3.14) (2)

(Surface roughness of free roll (Ra))
In accordance with JIS B0601: 2001, using a small surface roughness measuring machine (Surftest SJ-210, manufactured by Mitutoyo Co., Ltd.), measuring speed 0.25 mm / s, measuring length 2.5 mm, Only the reference length (2.5 mm) is extracted from the roughness curve in the direction of the average line, the X axis is taken in the direction of the average line of this extracted part, the Y axis is taken in the direction of the vertical magnification, and the roughness curve is y = f(X), it was calculated by the following formula (3). In the formula, l indicates a reference length.
The surface roughness of the roll surface was measured in the longitudinal direction of the roll.

(Surface temperature of free roll)
After the film was formed for 30 minutes, the apparatus was stopped, and the surface temperature of the free roll was measured using a handy type contact thermometer (DP-350, manufactured by Rika Kogyo Co., Ltd.).

(abrasion)
A film cut out to a length of 1 m and a width of 1 m was hung on a stand and irradiated with a Polarion light (model NP-1, halogen lamp 35 W) manufactured by Polarion, and scratches were visually observed. The length of the scratch was measured with vernier calipers. Observation was performed in an examination room surrounded by a blackout curtain, and evaluation was made as follows.
In addition, A and B were regarded as acceptable according to the following evaluation criteria.
[Evaluation criteria]
A: No scratches B: Scratches less than 3 mm long C: Scratches longer than 3 mm

(film thickness)
The thickness of the film at a position 100 mm from the center and both ends was measured with a micrometer (manufactured by Mitutoyo, model number: MDH-25), and the average value was taken as the film thickness.

(Storage modulus at 25°C)
Using a dynamic viscoelasticity measuring device (Rheogel-E4000, manufactured by UBM Co., Ltd.), a test piece obtained by cutting a film into a length of 15 mm and a width of 5 mm was measured by tension, frequency: 1 Hz, heating rate: 3°C. /min, the storage modulus of the test piece was measured from -50 to 200°C, and the value of the storage modulus at 25°C was obtained.

<Production Example 1: Production of (meth)acrylic resin (A-1)>
99.3 parts by mass of methyl methacrylate and 0.7 parts by mass of methyl acrylate, polymerization initiator [2,2'-azobis(2-methylpropionitrile), hydrogen abstraction capacity: 1%, 1 hour half-life temperature: 83° C.] and 0.26 parts by mass of a chain transfer agent (n-octyl mercaptan) were added and dissolved to obtain 3000 kg of raw material liquid.
100 parts by mass of ion-exchanged water, 0.03 parts by mass of sodium sulfate, and 0.45 parts by mass of a suspension dispersant were mixed to obtain 6000 kg of a mixed liquid. A pressure-resistant polymerization tank was charged with the mixed solution and the raw material solution (total of 9000 kg), and the temperature was raised to 70° C. to initiate a polymerization reaction while stirring in a nitrogen atmosphere. After 3 hours from the initiation of the polymerization reaction, the temperature was raised to 90° C. and stirring was continued for 1 hour to obtain a liquid in which the bead-like copolymer was dispersed. A small amount of polymer adhered to the wall surface of the polymerization vessel or to the stirring blades, but no bubbling occurred and the polymerization reaction proceeded smoothly.
The resulting copolymer dispersion was washed with an appropriate amount of ion-exchanged water, and the bead-like copolymer was taken out with a bucket-type centrifuge and dried with a hot air dryer at 80° C. for 12 hours. ) An acrylic resin (A-1) was obtained.
The obtained (meth)acrylic resin (A-1) had a methyl methacrylate unit content of 99.3% by mass, a methyl acrylate unit content of 0.7% by mass, and a weight average molecular weight ( Mw) was 92,000 and the glass transition temperature was 120°C.

<Production Example 2: Production of (meth)acrylic resin (A-2)>
(Meth)acrylic resin (A- 2) was obtained.
The obtained (meth)acrylic resin (A-2) had a methyl methacrylate unit content of 100% by mass, a weight average molecular weight (Mw) of 100,000, and a glass transition temperature of 121°C. .

<Production Example 3: Production of acrylic rubber particles (B-1)>
(1) Synthesis of inner layer In a reactor equipped with a stirrer, a thermometer, a nitrogen gas inlet tube, a monomer inlet tube and a reflux condenser, 1050 parts by mass of ion-exchanged water and 0 part of sodium polyoxyethylene tridecyl ether acetate were added. 3 parts by mass and 0.7 parts by mass of sodium carbonate (2100 kg in total) were charged, and the inside of the reactor was sufficiently replaced with nitrogen gas. The internal temperature was then raised to 80°C. 0.25 parts by mass of potassium persulfate was added thereto and stirred for 5 minutes. To this, 245 parts by mass of a monomer mixture consisting of 95.4% by mass of methyl methacrylate, 4.4% by mass of methyl acrylate and 0.2% by mass of allyl methacrylate was continuously added dropwise over 60 minutes. After completion of the dropwise addition, the polymerization reaction was further carried out for 30 minutes so that the polymerization conversion rate was 98% or higher.

(2) Synthesis of Elastic Layer Next, 0.32 parts by mass of potassium persulfate was charged into the same reactor and stirred for 5 minutes. Thereafter, 315 parts by mass of a monomer mixture consisting of 80.5% by mass of n-butyl acrylate, 17.5% by mass of styrene and 2% by mass of allyl methacrylate was continuously added dropwise over 60 minutes. After completion of the dropwise addition, the polymerization reaction was further carried out for 30 minutes so that the polymerization conversion rate was 98% or higher.

(3) Synthesis of Outer Layer Next, 0.14 parts by mass of potassium persulfate was charged into the same reactor and stirred for 5 minutes. Thereafter, 140 parts by mass of a monomer mixture consisting of 95.2% by mass of methyl methacrylate, 4.4% by mass of methyl acrylate and 0.4% by mass of n-octyl mercaptan was continuously added dropwise over 30 minutes. After completion of the dropwise addition, the polymerization reaction was further carried out for 60 minutes so that the polymerization conversion rate was 98% or higher.

After the latex containing the acrylic rubber particles (B-1) was obtained by the above operation, the latex containing the acrylic rubber particles (B-1) was frozen and coagulated. Then, it was washed with water and dried to obtain acrylic rubber particles (B-1). The particles had an average particle diameter of 0.23 μm and a graft ratio of 23%.

(Example 1)
(Meth)acrylic resin (A-1) 80 parts by mass, acrylic rubber particles (B-1) 20 parts by mass, UV absorber (ADEK STAB LA-31 manufactured by ADEKA Co., Ltd.) 2 parts by mass, and polymer processing 1.5 parts by mass of an auxiliary agent (paraloid K-125P manufactured by Dow Chemical Co.) is mixed with a Henschel mixer, and a thermoplastic resin composition is produced using a vented twin-screw extruder with a screw diameter of 58 mm set at 230 ° C. A pellet was obtained. The pellets are supplied to the hopper of a vented single-screw extruder 1 as shown in FIG. A linear pressure of 30 N/mm without bank was applied to a mirror-finished metal elastic roll 5 (surface temperature: 95°C) and a mirror-finished metal rigid roll 6 (surface temperature: 90°C). After sandwiching, cooling with a metal rigid roll 7 (surface temperature: 85 ° C.), nipping with a rubber roll 8, metal free roll 9 (rotation time 60 seconds, peripheral speed 20 m / min, diameter 12 cm, roll core material: made of aluminum, surface Treatment: hard chrome plating, surface roughness (Ra): 0.03 μm), mobile metal free roll 10 (rotation time 55 seconds, peripheral speed 20 m/min, diameter 12 cm, roll core material: aluminum, surface treatment: hard Chrome plating, surface roughness (Ra): 0.03 μm), metal free roll 11 (rotation time 82 seconds, peripheral speed 20 m / min, diameter 12 cm, roll core material: aluminum, surface treatment: hard chrome plating, surface roughness thickness (Ra): 0.03 μm), metal free roll 12 (rotation time 75 seconds, peripheral speed 20 m/min, diameter 12 cm, roll core material: aluminum, surface treatment: hard chrome plating, surface roughness (Ra): 0.03 μm), and passed through the rubber roll 13 and the film and wound up with a winder 14 to obtain a roll-shaped film with a thickness of 60 μm. Three metal free rolls and one movable metal free roll were installed so that the embracing angles were all 90 degrees. Also, the surface temperature of each free roll was 28°C. The calculation results of the left side of formula (1) are shown in Table 1. The left side of formula (1) for each free roll was 83 or more, and no scratches were observed. Moreover, the storage elastic modulus of the film at 25° C. was 2.2 GPa.

(Example 2)
In the manufacturing method of Example 1, after replacing the bearings of the movable metal free rolls 10 and adjusting the rotation time to 29 seconds, the free rolls 10 were moved upward to increase the embrace angle of each free roll. A roll film having a thickness of 60 μm was obtained in the same manner as in Example 1, except that the free roll 9 was 75 degrees, the free roll 10 was 60 degrees, and the free roll 11 was 75 degrees. The calculation results of the left side of the formula (1) are shown in Table 1. The left side of the free roll formula (1) was all 83 or more, and no scratches were observed. Moreover, the storage elastic modulus of the film at 25° C. was 2.2 GPa.

(Example 3)
In the manufacturing method of Example 1, after replacing the bearings of the movable metal free rolls 10 and adjusting the rotation time to 61 seconds, the free rolls 10 were moved upward to increase the embrace angle of each free roll. A roll film having a thickness of 60 μm was obtained in the same manner as in Example 1 except that the free roll 9 was 56 degrees, the free roll 10 was 22 degrees, and the free roll 11 was 56 degrees. The calculation results of the left side of the formula (1) are shown in Table 1. The left side of the free roll formula (1) was all 83 or more, and no scratches were observed. Moreover, the storage elastic modulus of the film at 25° C. was 2.2 GPa.

(Example 4)
In the manufacturing method of Example 1, after replacing the bearings of the movable metal free rolls 10 and adjusting the rotation time to 70 seconds, the free rolls 10 were moved upward, and the embrace angle of each roll was adjusted to A roll film having a thickness of 60 μm was obtained in the same manner as in Example 1 except that the free roll 9 was 51 deg, the free roll 10 was 12 deg, and the free roll 11 was 51 deg. The calculation results of the left side of the formula (1) are shown in Table 1. The left side of the free roll formula (1) was all 83 or more, and no scratches were observed. Moreover, the storage elastic modulus of the film at 25° C. was 2.2 GPa.

(Example 5)
In the manufacturing method of Example 1, after replacing the bearings of the movable metal free rolls 10 and adjusting the rotation time to 136 seconds, the free rolls 10 were moved upward, and the embrace angle of each roll was changed to A roll film having a thickness of 60 μm was obtained in the same manner as in Example 1 except that the free roll 9 was 52 deg, the free roll 10 was 13 deg, and the free roll 11 was 52 deg. The calculation results of the left side of the formula (1) are shown in Table 1. The left side of the free roll formula (1) was all 83 or more, and no scratches were observed. Moreover, the storage elastic modulus of the film at 25° C. was 2.2 GPa.

(Comparative example 1)
In the manufacturing method of Example 1, after replacing the bearings of the movable metal free rolls 10 and adjusting the rotation time to 11 seconds, the free rolls 10 were moved upward, and the embrace angle of each roll was adjusted to A roll film having a thickness of 60 μm was obtained in the same manner as in Example 1 except that the free roll 9 was 80 deg, the free roll 10 was 70 deg, and the free roll 11 was 80 deg. The calculation result of the left side of the formula (1) is shown in Table 1. The left side of the formula (1) for the free roll 10 is 81, and many scratches with a length of 3 mm or more were observed. Moreover, the storage elastic modulus of the film at 25° C. was 2.2 GPa.

(Example 6)
In the manufacturing method of Example 1, the movable metal free roll 10 was changed to a roll with a diameter of 20 cm, the rotation time was changed to 7 seconds by replacing the bearing, and the free rolls 9 to 12 were all set to a peripheral speed of 33 m / min. After adjusting so that the free roll 10 is moved upward, the embrace angle of each roll is changed so that the free roll 9 is 80 deg, the free roll 10 is 70 deg, and the free roll 11 is 80 deg. A roll film having a thickness of 60 μm was obtained in the same manner as in Example 1. The calculation results of the left side of formula (1) are shown in Table 1. The left side of free roll formula (1) is all 83 or more, and scratches of less than 3 mm were observed, but those of 3 mm or more not observed. Moreover, the storage elastic modulus of the film at 25° C. was 2.2 GPa.

(Example 7)
In the production of Example 6, the bearing of the moving metal free roll 10 was replaced and the rotation time was adjusted to 10 seconds. The holding angle of each roll is the same as in Example 6, except that the free roll 9 was set to 80 degrees, the free roll 10 to 70 degrees, and the free roll 11 to 80 degrees. got the film. The calculation results of the left side of the formula (1) are shown in Table 1. The left side of the free roll formula (1) was all 83 or more, and no scratches were observed. Moreover, the storage elastic modulus of the film at 25° C. was 2.2 GPa.

(Example 8)
(Meth) acrylic resin (A-2) 97.5 parts by mass, polycarbonate (SD polycarbonate 301-40 manufactured by Sumika Polycarbonate Co., Ltd.) 0.8 parts by mass, phenoxy resin (manufactured by Nippon Steel & Sumikin Chemical Co., Ltd. YP- 50S) 2.8 parts by mass, 2 parts by mass of a polymer processing aid (METABLEN P550A manufactured by Mitsubishi Chemical Corporation), and 0.9 parts by mass of an ultraviolet absorber (ADEKA Co., Ltd. ADEKA STAB LA-F70) in a Henschel mixer. and pellets of the thermoplastic resin composition were obtained using a vented twin-screw extruder with a screw diameter of 58 mm set at 230°C. As shown in FIG. 2, the pellets are supplied to a hopper of a single screw extruder 1 with a vent, melted and kneaded at 260 ° C., passed through a gear pump 2 and a polymer filter 3 in that order, and passed through a T die 4 with a lip opening of 1 mm. A film was discharged, and both ends of the film were electrified using the electrostatic applicator 16 on the polishing roll 6 to bring the film into close contact with the roll, thereby stabilizing the width of the film. Thereafter, as shown in FIG. 3, the film is gripped at regular intervals using a plurality of clips 17, transported to a simultaneous biaxial stretching machine (manufactured by Toshiba Machine Co., Ltd.) 15, and subjected to the preheating step shown in FIG. 145 ° C., the biaxial stretching process at 145 ° C., the stretching ratio is 2.4 times in the MD direction, 2.4 times in the TD direction, and the cooling process is carried out at 80 ° C. After that, the metal free roll 9 (rotation time 60 seconds , peripheral speed 20 m / min, diameter 12 cm, roll core material: aluminum, surface treatment: hard chrome plating, surface roughness (Ra): 0.03 μm), mobile metal free roll 10 (rotation time 61 seconds, peripheral speed 20 m/min, diameter 12 cm, roll core material: aluminum, surface treatment: hard chrome plating, surface roughness (Ra): 0.03 μm), metal free roll 11 (rotation time 82 seconds, peripheral speed 20 m/min, diameter 12 cm, roll core material: aluminum, surface treatment: hard chrome plating, surface roughness (Ra): 0.03 μm), metal free roll 12 (rotation time 75 seconds, peripheral speed 20 m/min, diameter 12 cm, roll core material : made of aluminum, surface treatment: hard chrome plating, surface roughness (Ra): 0.03 μm). The free rolls were installed so that the free roll 9 had an embrace angle of 56 degrees, the free roll 10 had an embrace angle of 22 degrees, the free roll 11 had an embrace angle of 56 degrees, and the free roll 12 had an embrace angle of 90 degrees. The surface temperature of each free roll was 25°C. The calculation results of the left side of formula (1) are shown in Table 1. The left side of formula (1) for each free roll was 83 or more, and no scratches were observed. Moreover, the storage elastic modulus of the film was 3.1 GPa.

(Comparative example 2)
In the production of Example 8, after replacing the bearings of the movable metal free rolls 10 and adjusting the rotation time to 13 seconds, the free rolls 10 were moved upward to adjust the embrace angle of each roll to the free A roll film having a thickness of 40 μm was obtained in the same manner as in Example 8 except that the roll 9 was 75 deg, the free roll 10 was 60 deg, and the free roll 11 was 75 deg. The calculation results of the left side of the formula (1) are shown in Table 1. The left side of the formula (1) for the free roll 10 is 82, and many scratches with a length of 3 mm or more were observed. Moreover, the storage elastic modulus of the film at 25° C. was 3.1 GPa.

The film obtained by the production method of the present invention has reduced fine scratches and can be used as a film with excellent appearance quality.

1 extruder 2 gear pump 3 polymer filter 4 T-die 5 polishing roll (elastic metal roll)
6, 7 Polishing roll (metal rigid roll)
8', 13' nip roll (metal roll)
8, 13 Nip roll (rubber roll)
9, 11, 12 free roll (metal free roll)
10 mobile free roll (mobile metal free roll)
14 winding machine roll 15 stretching machine (simultaneous biaxial stretching machine)
16 electrostatic applicator 17 clip

Claims (8)

A film manufacturing method comprising a step of passing the film through a plurality of free rolls in the process from transporting the film to winding it,
The film is made of a (meth)acrylic resin composition containing (meth)acrylic resin (A) and acrylic rubber particles (B),
The plurality of free rolls all satisfy the following formula (1),
A method for producing a film, wherein each of the plurality of free rolls has a diameter of 12 to 25 cm .
t×d×3.14×α/360≧ 86 (1)
(In the formula, t is the time (seconds) until the free roll stops when the roll rotation speed is 53 rpm, d is the diameter of the free roll (cm), and α is the embrace angle (deg).) 2. The method of producing a film according to claim 1, wherein the free roll has a steel or aluminum core material and hard chrome plating applied to the surface of the core material. 3. The method for producing a film according to claim 1, wherein the free roll has a surface roughness (Ra) of 0.8 [mu]m or less. The method for producing a film according to any one of claims 1 to 3, wherein the free roll has a surface temperature of 15 to 35°C. The method for producing a film according to any one of claims 1 to 4 , wherein the film has a storage elastic modulus at 25°C of 1 GPa or more. The method for producing a film according to any one of claims 1 to 5 , wherein the film has a thickness of 10 to 300 µm. The method for producing a film according to any one of claims 1 to 6 , wherein the film is produced by melt extrusion. The method for producing a film according to any one of claims 1 to 7 , wherein the film is a biaxially stretched film stretched 2.25 to 6.25 times.

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