KR20180095016A - Process for producing thermoplastic resin film and cyclic olefin resin film - Google Patents

Abstract

Feeding and melting of the raw material resin are carried out under the condition that 0.75? Feeding part resin transport efficiency? 1.0 is satisfied by using an extruder having a feeding part, a compression part and a metering part so that the molten resin extruded from the extruding mouth is melted A method of manufacturing a thermoplastic resin film having a step of extruding, and an application thereof. W is the screw flight distance, Hf is the groove depth in the supply portion, D is the inner diameter of the cylinder,? Is the screw flight angle, Q is the extrusion amount of the molten resin,? Is the specific gravity of the raw resin, The number of screw revolutions per minute is shown.

Description

Process for producing thermoplastic resin film and cyclic olefin resin film

This disclosure relates to a method for producing a thermoplastic resin film and a cycloolefin resin film.

Thermoplastic resin films are used for various purposes such as optical films and protective films for solar cells. For example, a cellulose-based resin film such as a cellulose acylate film is used as an optical film used for a liquid crystal display device or the like.

The cellulose-based resin film such as a cellulose acylate film is formed by melting a cellulose-based resin with an extruder and extruding it into a die, discharging the molten resin from the die in a sheet form, cooling and solidifying.

Recently, a cyclic olefin resin film has attracted attention as a small film having a small change in optical properties due to changes in environmental temperature and humidity, and it has been studied to use a cycloolefin resin as a film for a polarizing plate and a liquid crystal display by melt film formation.

In the case of producing a thermoplastic resin film by the melt extrusion method, the resin may be deteriorated by thermal oxidation to cause a foreign matter (hereinafter sometimes referred to as "thermally deteriorated foreign matter"). Particularly, in the case of an optical film, the foreign matter contained in the film becomes a point defect, and the optical transparency is lowered due to the point defect, and the unevenness is increased.

As a countermeasure for suppressing the generation of heat deteriorated foreign matters, for example, in Japanese Unexamined Patent Application Publication No. 2008-137328, by making the oxygen concentration of the opening portion of the extruder used for melt film formation to be in an inert gas atmosphere of 10 ppm or less, Thereby suppressing deterioration.

In order to reduce the oxygen concentration in the opening of the extruder to 10 ppm or less as in the method disclosed in Japanese Unexamined Patent Application Publication No. 2008-137328, a large-scale atmosphere replacing device is required.

An object of one embodiment of the present invention is to provide a method for producing a thermoplastic resin film capable of producing a thermoplastic resin film by suppressing generation of thermally deteriorated foreign matter without performing a large-scale atmosphere substitution. Another object of the present invention is to provide a cyclic olefin resin film having high light transmittance.

The present disclosure includes the following embodiments.

≪ 1 > An injection molding method, comprising the steps of: a cylinder having a feed port through which a raw resin is fed and an extrusion port through which molten resin melted in the raw resin is extruded; and a flight arranged in a spiral around the screw shaft and the screw shaft, , And a feeder resin transport efficiency calculated by the following equation is calculated as 0.75? Feeder resin transport efficiency? 1.0 using an extruder having a feeder, a compression unit and a metering unit in order from the feeder side along the screw axis in the cylinder Supplying and melting the raw material resin under the condition that the molten resin extruded from the die is melted and extruded from the die into a film form.

[Equation 1]

W: screw flight distance (mm)

Hf: groove depth in the supply part (mm)

D: Inner diameter of cylinder (mm)

Ψ: screw flight angle (°) in the supply part

Q: Extrusion amount of molten resin (kg / h)

ρ: specific gravity of the raw resin (g / cm ³ )

N: screw rotation rate per minute (rpm)

Compression ratio: Volume per screw pitch in the feed section / volume per screw pitch in the metering section

<2> The method for producing a thermoplastic resin film according to <1>, wherein the oxygen concentration in the feed port is 0.1% or less.

&Lt; 3 > The process according to any one of < 1 > to < 2 >, wherein the temperature of the raw material resin fed into the cylinder from the feed port is Tg-90 DEG C or more and Tg + 10 DEG C or less when the glass transition temperature of the raw material resin is Tg DEG C A method for producing a thermoplastic resin film.

&Lt; 4 > A method for producing a thermoplastic resin film according to any one of < 1 > to < 3 >, wherein a raw material resin is fed into a cylinder from a feed port through a vacuum hopper.

&Lt; 5 > The process for producing a thermoplastic resin film according to any one of < 1 > to < 4 >, wherein the screw is a double flight screw.

&Lt; 6 > The process according to any one of < 1 > to < 5 >, wherein the temperature of the screw at the supply portion is controlled to be Tg-80 DEG C or higher and Tg DEG C or lower when the glass transition temperature of the raw- A method for producing a thermoplastic resin film.

<7> The method for producing a thermoplastic resin film according to any one of <1> to <6>, wherein the raw material resin is a cyclic olefin resin.

<8>, the number of foreign matter greater than 0.3 is a maximum diameter of 30μm thickness 100μm per dog / cm ² or less, and the number of foreign matter 100 is less than 30μm is more than a maximum diameter of 5μm pieces / cm ² or less cyclic olefin resin film.

According to one embodiment of the present invention, there is provided a method of producing a thermoplastic resin film capable of producing a thermoplastic resin film by suppressing the generation of heat deteriorated foreign matter without performing a large-scale atmosphere substitution. According to another embodiment of the present invention, a cyclic olefin resin film having high light transmittance is provided.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic view showing an example of the entire configuration of an apparatus for carrying out the method for producing a thermoplastic resin film of the present disclosure; Fig.
2 is a schematic view showing an example of the configuration of an extruder usable in the production method of the present disclosure.
Fig. 3 is a schematic diagram showing an enlarged view of a supply portion of the extruder shown in Fig. 2;

Hereinafter, the method of producing the thermoplastic resin film of the present disclosure and the cycloolefin resin film will be described in detail with reference to the accompanying drawings. In the following description, the symbols may be omitted.

In the following description, "~ " representing a numerical range means a range including numerical values described as a lower limit value and an upper limit value before and after the numerical range, and when a unit is attached only to the upper limit value or the lower limit value, And means the same unit.

In the present specification, the term " process "is included in the term when the intended purpose of the process is achieved, not only in the independent process but also in cases where it can not be clearly distinguished from other processes.

In the present specification, the term "(co) polymer" means either or both of a homopolymer and a copolymer containing a specific repeating unit.

In the numerical range described stepwise in this specification, the upper limit value or the lower limit value described in any numerical range may be replaced with the upper limit value or the lower limit value of the numerical range of the other stepwise description. In the numerical range described in this specification, the upper limit value or the lower limit value described in any numerical range may be replaced by the value shown in the embodiment.

The method for producing a thermoplastic resin film of the present disclosure (hereinafter sometimes referred to as a production method of the present disclosure) includes a cylinder having a feed port through which a raw resin is fed and an extruded port through which a molten resin from which the raw resin is melted is extruded, An extruder having a feed screw, a compression screw, and a metering screw is provided in the cylinder, in the order from the feed screw side along the screw shaft, having a screw arranged around the screw shaft and the screw shaft and rotating in the cylinder. , Feeding and melting of the raw resin are carried out under the condition that the feeding-unit resin transport efficiency calculated by the following formula satisfies 0.75? Feeding-unit resin transport efficiency? 1.0, and the molten resin extruded from the extruding port is melted And a step of extruding.

[Equation 1]

The meanings of the symbols in the formula for calculating the supply unit resin transport efficiency are respectively as follows, and the details will be described later.

W: screw flight distance (mm)

Hf: groove depth in the supply part (mm)

D: Inner diameter of cylinder (mm)

Ψ: screw flight angle (°) in the supply part

Q: Extrusion amount of molten resin (kg / h)

ρ: specific gravity of the raw resin (g / cm ³ )

N: screw rotation rate per minute (rpm)

Compression ratio: Volume per screw pitch in the feed section / volume per screw pitch in the metering section

In the present specification, the term "raw material resin" means a resin composition including an additive added as needed in addition to the resin component.

The thermoplastic resin may be referred to as "resin ", and the thermoplastic resin film may be referred to as" film ".

First, the outline of the manufacturing apparatus and the manufacturing method used in the manufacturing method of the thermoplastic resin film of the present disclosure will be described.

Fig. 1 schematically shows an example of the overall configuration of a film forming apparatus (a thermoplastic resin film producing apparatus) for carrying out the method of producing the thermoplastic resin film of the present disclosure.

The film-forming apparatus 10 shown in Fig. 1 comprises a hopper 12 into which a thermoplastic resin as a raw material resin is charged, an extruder 14 which melts the thermoplastic resin supplied from the hopper 12, a melted resin (molten resin) A die 20 for melt-extruding the molten resin in the form of a film; a high-temperature thermoplastic resin (for example, A plurality of cooling rolls (hereinafter sometimes referred to as casting rolls) 22, 24 and 26 for multi-step cooling the thermoplastic resin 100 discharged from the die 20 to a first cooling roll 22 (Hereinafter, the contact roll may be referred to as a touch roll in some cases). Although not shown, a peeling roll for peeling the thermoplastic resin film 100 from the last third cooling roll 26 and a winding machine for winding the cooled film are usually provided.

Fig. 2 schematically shows an example of the configuration of an extruder usable in the production method of the present disclosure.

As shown in Fig. 2, the extruder 14 includes a cylinder 44 and a screw 50 disposed in the cylinder.

The cylinder 44 has a supply port 52 through which a thermoplastic resin is supplied and an extrusion port 54 through which a molten resin in which the thermoplastic resin is molten is extruded. In the cylinder 44, (A region indicated by A in Fig. 2) for transporting the thermoplastic resin supplied from the supply port 52 in the order from the sphere 52 side, a compression section (also shown as A in Fig. 2) for kneading and melting the thermoplastic resin while compressing the thermoplastic resin 2) and a metering section (area indicated by C in Fig. 2) for metering the melted resin and stabilizing the extrusion amount. Fig. 3 is an enlarged schematic diagram of the supply section A of the extruder 14. Fig.

The hopper 12 shown in Fig. 1 is mounted on the supply port 52 of the cylinder 44 shown in Fig.

The screw 50 has a flight (hereinafter sometimes referred to as a screw flight) 48 arranged in the form of a spiral around the screw shaft 46 and the screw shaft 46, (44).

In order to control the temperature of the resin in the cylinder 44, temperature control means (such as a heater or the like), which is not shown, is provided around the cylinder 44, ) Is preferably provided.

When the thermoplastic resin film is produced by the thermoplastic resin film production apparatus 10 having the constitution shown in Fig. 1 and the extruder 14 having the constitution shown in Fig. 2, the thermoplastic resin as the raw resin is fed into the hopper 12, And is supplied into the cylinder 44 through the supply port 52 of the cylinder 44. [ The thermoplastic resin supplied from the supply port 52 into the cylinder 44 is transported toward the extrusion port 54 while being preheated in the supply section A by the rotation of the screw 50.

Further, in order to prevent oxidation of the molten resin by oxygen remaining in the cylinder 44, it is more preferable to perform vacuum evacuation of the inside of the extruder in an inert gas stream such as nitrogen or using a vented extruder.

The pre-heated thermoplastic resin in the supply part (A) is transported to the compression part (B). The compression section B has a configuration in which the diameter of the screw shaft 46 gradually increases toward the extrusion port 54. The thermoplastic resin is compressed by the compression section B Is kneaded while being compressed between the inner wall and the screw (50), and is heated and melted by contacting the temperature controlled cylinder (44). The molten resin in the compression section B is transported to the metering section C and the molten resin is metered in the metering section C to stabilize the extrusion amount from the extrusion port 54.

The molten resin melted by the extruder 14 and extruded from the extruding orifice 54 is continuously fed toward the die 20 via the pipe 40 and the gear pump 16 and the filter 18. Then, the molten resin is melt-extruded from the die 20 into a film form. Fig. 1 shows a thermoplastic resin 100 extruded into a film shape.

The film-shaped thermoplastic resin melt-extruded from the die 20 is sandwiched between the contact roll (touch roll) 28 and the first cooling roll 22 to form the second cooling roll 24, Rolled by a winding machine (not shown) via a roll 26. [

In the method for producing a thermoplastic resin film of the present disclosure, when the thermoplastic resin film is produced through the above-described process, the feed-part resin transport efficiency calculated by the above-mentioned formula is in the range of 0.75? , The thermoplastic resin is supplied and melted, and the molten resin is melt-extruded from the die in the form of a film by an extruder.

The reason why generation of heat deteriorated foreign matter is suppressed in the film obtained by the method for producing a thermoplastic resin film of the present disclosure is presumed as follows.

In the formula for calculating the supply portion resin transport efficiency in the present disclosure, the numerator "Q / N" of the fraction of the first term means the extruded amount of the molten resin per revolution of the screw in the melt extrusion process. On the other hand, the denominator means the theoretical transport amount in the supply section in the cylinder, and it means that by dividing the theoretical transport amount by the compression ratio, the denomination can be transported with high efficiency regardless of the compression ratio. (D / 90) ^0.5 is a correction coefficient for the inner diameter of the cylinder.

The feed efficiency of the feed portion resin calculated by the equation of the feeding portion resin transport efficiency in the present disclosure is 0.75 or more, that is, the efficiency of solid resin transport before melting in the extruder feed portion is increased, It is difficult for the oxygen in the gap to contact the molten resin. On the other hand, melt feeding can be performed by setting the feed resin transport efficiency to 1.0 or less.

This makes it possible to produce a thermoplastic resin film in which generation of thermal deterioration foreign substances generated by the reaction of oxygen with oxygen in the obtained film is suppressed without performing a large-scale atmosphere substitution.

Next, the method for producing the thermoplastic resin film of the present disclosure will be described in more detail. Further, an example of producing a cyclic olefin resin film using a cyclic olefin resin as a raw material resin as appropriate will be described. However, the method of producing the thermoplastic resin film of the present disclosure is not limited to the method of producing the cyclic olefin resin film described later, and can be suitably applied to the case of producing a thermoplastic resin film using a thermoplastic resin other than the cyclic olefin resin have.

<Raw Material Resin>

The starting resin used in the present disclosure is not particularly limited as long as it is a thermoplastic resin and may be selected depending on the use of the film to be produced.

For example, in the case of producing an optical film, an acrylic resin, a methacrylic resin, a polycarbonate (PC) resin, and a cyclic olefin resin can be suitably used as the thermoplastic resin from the viewpoint of good transparency of the obtained film. Among them, a cyclic olefin resin is preferable.

The cyclic olefin resin is a (co) polymer resin having a cyclic olefin structure. Examples of the polymer resin having a cyclic olefin structure include (1) a norbornene polymer, (2) a monocyclic cycloolefin polymer, (3) (4) a vinyl alicyclic hydrocarbon polymer, and hydrides of (1) to (4).

Among them, a norbornene polymer (1) and a cyclic olefin polymer (2) and a hydride thereof are preferable.

The norbornene polymer in the present specification is used to mean a homopolymer and a copolymer containing a repeating unit having a norbornene structure, and the norbornene structure may be ring-opened.

For example, examples of the polymer resin having a cyclic olefin structure include an addition (co) polymeric cyclic polyolefin containing at least one kind of repeating units represented by the following general formula (II) and, if necessary, repeating units represented by the general formula (I) Units and at least one kind of units selected from the group consisting of ethylene and propylene.

As the polymer resin having a cyclic olefin structure, a ring-opening (co) polymer containing at least one cyclic repeating unit represented by the general formula (III) may also be suitably used.

[Chemical Formula 1]

(2)

(3)

In the general formulas (I), (II) and (III), m represents an integer of 0 to 4. ^{R 1, R 2, R 3} , R 4, R 5, and R ⁶ each independently represents a hydrogen atom or a hydrocarbon of a carbon number of ^{1 ~ 10, X 1, X} 2, X 3, Y 1, Y 2 , and Y ³ each independently represent a hydrogen atom, a C 1 -C 10 hydrocarbon group with a carbon number of 1 to 10 halogen atoms, the halogen atoms be replaced to, a hydrocarbon _{group, - (CH 2) n COOR} 11, - (CH 2) _{^{n OCOR 12, - (CH 2}} ) n NCO, - (CH 2) n NO 2, - (CH 2) n CN, - (CH 2) n CONR 13 R 14, - (CH 2) n NR 13 R 14 _{, - (CH 2) n OZ} , - (CH 2) n W, or X ¹ and Y ^1, (-CO) consisting of X ² and Y ^2, or X ³ and Y ₂ O ^3, or (-CO) ₂ It represents a NR ^15. In ^{addition, R 11, R 12, R} 13, R 14, and R ¹⁵ represents a hydrocarbon of a hydrogen atom or a carbon number 1 ~ 20, Z represents an a hydrocarbon substituted with a hydrocarbon group or halogen, W is SiR ¹⁶ _p D represents a _3-p, (R ¹⁶ represents an hydrocarbon having a carbon number of 1 ~ 10, D denotes a halogen atom, -OCOR ¹⁶ or -OR ¹⁶ can, p is an integer of 0 to 3), n represents an integer of 0 to 10;

The retardation (Rth) in the thickness direction of the optical film is increased by introducing a functional group having high polarizability into all or a part of substituents of X ¹ , X ² , X ³ , Y ¹ , Y ² and Y ³ , (Re) can be increased. The Re value can be increased by stretching the film having a large Re-expressing property during the film-forming process.

The functional group having a high polarizability means a functional group having two or more atoms having different electronegativity and having a dipole moment. Specific examples of the functional group having a high polarizability include a carboxyl group, a carbonyl group, an epoxy group, an ether group, a hydroxyl group, an amino group, an imino group, a cyano group, an amide group, an imide group, .

The norbornene addition (co) polymers are disclosed in Japanese Laid-Open Patent Publication No. 10-7732, Japanese Laid-Open Patent Publication No. 2002-504184, US Patent Publication No. US2004 / 229157A1, and International Publication No. WO2004 / 070463A1. The norbornene addition (co) polymer is obtained, for example, by addition polymerization of norbornene polycyclic unsaturated compounds. Further, the norbornene addition (co) polymer may contain, if necessary, norbornene polycyclic unsaturated compounds and at least one member selected from the group consisting of ethylene, propylene, butene; Conjugated dienes such as butadiene, isoprene; Nonconjugated dienes such as ethylidene norbornene; Acrylic acid, methacrylic acid, maleic anhydride, acrylic acid ester, methacrylic acid ester, maleimide, vinyl acetate, vinyl chloride and the like can be obtained by addition polymerization of acrylic acid, acrylonitrile, acrylic acid, methacrylic acid, maleic anhydride,

As norbornene addition (co) polymers, commercially available products may be used. The norbornene addition polymer (co) polymer is commercially available from Mitsui Chemicals, Inc. under the trade name APEL (registered trademark) and has a glass transition temperature (Tg) different from that of APL8008T (Tg: 70 DEG C), APL6013T Tg: 125 占 폚) and APL6015T (Tg: 145 占 폚). Norbornene addition (co) polymers such as TOPAS8007, 6013 and 6015 from Polyplastics Co., Ltd. are commercially available as pellets. Appear3000 is also commercially available as a norbornene addition (co) polymer from Ferrania.

The hydride of the norbornene polymer can be obtained by subjecting a polycyclic unsaturated compound to addition polymerization or metathesis ring-opening polymerization and hydrogenation. As for the hydrides of norbornene polymers, for example, JP-A-1-240517, JP-A-7-196736, JP-A-60-26024, JP-A-62-19801 Japanese Patent Application Laid-Open No. 2003-159767 and Japanese Laid-Open Patent Publication No. 2004-309979, and these references can be referred to in this disclosure.

The norbornene polymer used in the production process of the present disclosure is preferably a polymer containing a cyclic repeating unit represented by the general formula (III), and in the cyclic repeating unit represented by the general formula (III), R ⁵ and R ⁶ Is preferably a hydrogen atom or -CH ₃ , and X ³ and Y ³ are preferably a hydrogen atom, -Cl or -COOCH ₃ , and other groups are appropriately selected.

The norbornene resin is commercially available from JSR Corporation under the trade name of Arton (registered trademark) G or Aton F and is available from Zeon Corporation under the trade names Zeonor (registered trademark) ZF14, ZF16, Zeonex : Registered trademark) 250 or Zeonex 280, and these can be used.

In the production method of the present disclosure, various additives depending on the use of the film to be produced, for example, deterioration inhibitor, ultraviolet ray inhibitor, retardation (optical anisotropy) regulator, fine particles, exfoliation promoter and infrared absorber can be used. The additive may be solid or may be oil.

In the formula for calculating the feeding-side resin transport efficiency in the present disclosure, p represents the specific gravity (g / cm ³ ) of the raw resin (thermoplastic resin) and depends on the specific gravity rho of the resin used. Other parameters of efficiency may be set.

The thermoplastic resin as the raw material resin and the additives to be added as required are preferably blended and pelletized before the melt film formation.

In carrying out the pelletization, it is preferable to dry the thermoplastic resin beforehand. When a solid phase additive is used, it is preferable to dry the additive beforehand. When the thermoplastic resin is dried, the drying method and drying conditions are not particularly limited. As the drying method, for example, a method of heating at a temperature of 80 ° C to 110 ° C, preferably around 90 ° C, in a heating furnace for a heating time of 8 hours or more, preferably 8 hours to 12 hours, But is not limited thereto. The heating temperature and the heating time at the time of drying the thermoplastic resin may be selected in consideration of at least one of the glass transition temperature (Tg) and melting point of the thermoplastic resin.

If the additive has fluidity such as oil, it may be directly introduced into an extruder and mixed with a thermoplastic resin in an extruder.

In the pelletization of the thermoplastic resin, for example, by using a vent type extruder, it is also possible to omit drying of the thermoplastic resin which is preferably performed beforehand.

When the thermoplastic resin is pelletized, the additive to be added may be added from a raw material inlet or a vent located in the middle of an extruder used for pelletizing without mixing with a thermoplastic resin in advance.

The pellets preferably have a cross-sectional area of 1 mm ² to 300 mm ² and a length of 1 mm to 30 mm, more preferably ² mm ² to 100 mm ² and a length of 1.5 mm to 10 mm, for example.

It is preferable to reduce moisture in the pellets prior to the melt-film formation. The drying method of the pellets is not particularly limited as long as the objective water content can be obtained. Usually, drying with a dehumidifying air dryer is often carried out. The drying of the pellets is preferably carried out efficiently by using means such as heating, blowing, depressurizing and stirring, either singly or in combination. In addition, it is preferable to use a dry hopper for supplying the raw material resin, and it is preferable that the drying hopper to be used has a heat insulating structure.

The drying temperature in the case of drying the pellets is preferably 0 ° C to 200 ° C, more preferably 40 ° C to 180 ° C, and particularly preferably 60 ° C to 150 ° C.

The water content of the thermoplastic resin used as the raw material resin is preferably 1.0% by mass or less, more preferably 0.1% by mass or less, and even more preferably 0.01% by mass or less.

<Supply of raw resin to extruder>

The raw resin is fed into the hopper 12 and fed into the cylinder 44 from the feed port 52 of the cylinder 44. [ The raw resin to be fed into the hopper 12 may be a pellet of a thermoplastic resin, a pellet containing a thermoplastic resin and an additive, or a flaky thermoplastic resin.

From the viewpoint of suppressing thermal oxidation of the thermoplastic resin supplied to the cylinder 44, the oxygen concentration in the supply port 52 is preferably low, and it is preferable that the oxygen concentration is 0.1% or less on a volume basis. As a method of lowering the oxygen concentration in the supply port 52, there are a method of supplying the raw resin into the cylinder 44 from the supply port 52 through the vacuum hopper, a method of supplying the raw material resin into the supply port 52 of the cylinder 44 And a method of supplying nitrogen gas. The oxygen concentration in the supply port 52 can be measured by providing a pipe (not shown) in the supply port 52 and connecting an oxygen concentration meter (not shown).

In the calculation formula of the supply portion resin transport efficiency in the present disclosure, D represents the inner diameter (mm) of the cylinder 44. The inner diameter D of the cylinder 44 is preferably from 10 mm to 300 mm, more preferably from 20 mm to 250 mm, from the viewpoint of performing the melt extrusion by setting the feeding portion resin transport efficiency to 0.75 or more and 1.0 or less.

The resin supplied into the cylinder 44 is gradually heated by the friction due to the rotation of the screw 50 and the temperature control means (not shown) disposed around the cylinder 44. It is preferable that the thermoplastic resin is supplied from the supply port in a heated state in view of supplying the raw resin from the supply port 52 and rapidly melting the thermoplastic resin in the cylinder 44. [

When the glass transition temperature of the thermoplastic resin is Tg (占 폚), the temperature of the thermoplastic resin supplied from the supply port 52 into the cylinder 44 is preferably Tg-90 占 폚 or higher and Tg + 10 占 폚 or lower, And more preferably controlled to be Tg-80 ° C or higher and Tg-10 ° C or lower. As a method for controlling the temperature of the thermoplastic resin supplied from the supply port 52 into the cylinder 44 within the above preferable range, there are a method of preheating the pellets to be fed into the hopper, a method using the hopper provided with the heating means, And a method of providing a heating means near the supply port separately from the hopper.

<Melting of raw resin by extruder>

The thermoplastic resin supplied from the supply port 52 into the cylinder 44 is transported toward the extrusion port 54 while being preheated in the supply section A by the rotation of the screw 50.

In the calculation formula of the supply portion resin transport efficiency in this disclosure, W represents the flight distance (mm) of the screw 50 at the supply portion in the cylinder. The screw flight distance W is preferably from 10 mm to 300 mm, more preferably from 20 mm to 250 mm, from the viewpoint of performing the melt extrusion with the feeding portion resin transport efficiency being 0.75 or more and 1.0 or less.

In the calculation formula of the supply portion resin transport efficiency in the present disclosure,? Represents the screw flight angle (占 in the supply portion A). The screw flight angle Ψ in the supply part A is preferably 5 ° to 30 ° and more preferably 10 ° to 25 ° from the viewpoint of performing the melt extrusion with the supply part resin transport efficiency being 0.75 or more and 1.0 or less desirable.

The flight in the screw may be a full flight, a double flight, or the like. From the viewpoint of promoting the melt-kneading of the resin in the compression section (B), a double flight screw is preferable. Further, the double flight screw is a screw in which two flights in the compression section (B) are arranged in a spiral shape on the screw shaft.

In the formula for calculating the feeding-side resin transport efficiency in the present disclosure, Hf is a value obtained by dividing the groove depth (mm) in the feeding section A, that is, from the outer peripheral surface of the screw shaft in the feeding section A to the outer periphery of the screw flight (Hereinafter sometimes referred to as "supply groove depth") in the screw shaft diameter direction. The feed groove depth Hf is preferably from 2 mm to 30 mm, more preferably from 3 mm to 25 mm, from the viewpoint of performing the melt extrusion with the feeding portion resin transport efficiency being 0.75 or more and 1.0 or less. The supply groove depth can be adjusted by the inner diameter D of the cylinder 44, the outer diameter d1 of the screw shaft in the supply portion, and the height of the screw flight 48. [

The resin supplied into the cylinder 44 is gradually heated by friction due to the rotation of the screw 50 or the like.

In the calculation formula of the supply portion resin transport efficiency in this disclosure, N represents the number of screw revolutions (rpm: revolution / minute). In the method for producing a thermoplastic resin film of the present disclosure, since the screw is rotated in a state where the thermoplastic resin is densely packed in the supply part, the screw is usually rotated at a high torque and at a relatively low speed. From this viewpoint, the screw rotation speed (rpm) in the manufacturing method of the present disclosure is preferably 3 rpm to 150 rpm, more preferably 5 rpm to 100 rpm.

In the supply section A, it is not necessary that all of the thermoplastic resin in the cylinder 44 is melted, but in the compression section B, the thermoplastic resin needs to be completely melted. On the other hand, in order to smoothly feed the raw resin to the compression section B side by the rotation of the screw 50 in the supply section A, the screw 50 and the cylinder 44) and the resin.

Generally, if the temperature of the cylinder 44 is high, the frictional force of the resin against the cylinder 44 becomes high, and if the temperature of the screw 50 is low, the frictional force of the resin against the screw 50 becomes low, The resin is easily sent to the compression section B side. When the glass transition temperature of the thermoplastic resin is set to Tg (占 폚), if the temperature of the screw 50 is set to be higher than Tg and the temperature of the feed portion A soften the raw resin, The difference between the frictional force of the cylinder 44 and the frictional force of the resin with respect to the cylinder 44 becomes small, and it may be difficult to proceed to the compression section B for melting the resin. From this point of view, it is preferable to control the temperature of the screw in the supply portion A to be Tg-80 DEG C or higher and Tg DEG C or lower, and more preferably Tg-70 DEG C or higher and Tg-10 DEG C or lower. For example, the temperature of the screw can be controlled with high accuracy by using a screw having a structure for circulating and supplying the heat medium inside the screw shaft.

The resin heated in the supplying section A is transported to the compression section B by the rotation of the screw and further heated and melted in the compression section B. The resin (molten resin) melted in the compression section (B) is transported again to the metering section (C).

In the equation for calculating the supply portion resin transport efficiency in the present disclosure, the compression ratio represents "volume per pitch of screw flight in the supply portion / volume per pitch of screw flight in the metering portion ". The compression ratio is set such that the outer diameter d1 of the screw shaft of the supply part A, the outer diameter d2 of the screw shaft of the metering part C, the groove depth Hf of the supply part A, and the groove depth Hm ).

If the compression ratio is too small, the thermoplastic resin is not sufficiently melted and kneaded, unmelted parts are generated, unhulled foreign matters remain in the thermoplastic film after the production, and bubbles are likely to be mixed. As a result, the strength of the thermoplastic film is lowered, or the film tends to break when the film is stretched, so that there is a possibility that the orientation can not be sufficiently increased. On the other hand, if the compression ratio is too large, the shearing stress applied to the thermoplastic resin becomes too large and the resin tends to deteriorate due to heat generation, so that the thermoplastic film after production tends to become yellowish. If the shear stress applied to the thermoplastic resin becomes too large, the thermoplastic resin may be cut off by molecules, resulting in a decrease in molecular weight and a decrease in the mechanical strength of the film.

The compression ratio is preferably from 1.5 to 4.0, more preferably from 2.0 to 3.5, from the viewpoint of performing the melt extrusion at the above-mentioned point and at the feeding portion resin transport efficiency of 0.75 or more and 1.0 or less. The compression ratio is set such that the inner diameter D of the cylinder 44, the outer diameters d1 and d2 of the screw shaft in the supply portion and the metering portion, the flight spacing W of the screw 50 and the screw flight angle? It can be adjusted by adjusting at least one of them.

In the calculation formula of the feeding portion resin transport efficiency in the present disclosure, L / D is preferably 20 to 70. [ L / D is the ratio of the cylinder length (L) to the cylinder inner diameter (D).

The extrusion temperature is preferably set to 200 to 300 캜.

The set temperature in the extruder may be the same as the entire region, or may be a different temperature distribution depending on the region. It is more preferable to set the temperature of the supply part A as described above in the extruder to be higher than the temperature of the compression part B in the extruder.

If L / D is too small, insufficient melting or kneading of the thermoplastic resin in the extruder tends to occur. As in the case where the compression ratio is small, there is a possibility that unhulled foreign matter tends to be generated in the thermoplastic film after the production. On the other hand, if L / D is too large, the residence time of the thermoplastic resin in the extruder becomes too long, and the resin tends to deteriorate easily. In addition, if the residence time is prolonged, there is a possibility that molecular cut off occurs in the thermoplastic resin, or the molecular weight of the thermoplastic resin is lowered due to the breakage of the molecule, and the mechanical strength of the thermoplastic film is lowered.

From this viewpoint, L / D is preferably in the range of 20 to 70, more preferably in the range of 22 to 60, and more preferably in the range of 24 to 50.

The molten resin is extruded from the extrusion port 54 of the cylinder 44 via the metering section C. In the metering section C, the molten resin is metered, and the extrusion amount from the extrusion port 54 is stabilized.

The molten resin extruded from the extruder 14 is preferably conveyed toward the die 20 through the pipe 40 but is preferably subjected to so-called breaker plate type filtration in which the filter medium is provided at the outlet of the extruder 14 . It is preferable that the molten resin extruded from the extruder 14 is transported to the die 20 via the gear pump 16 and the filter 18. [ Further, the molten resin may be referred to as "melt ".

(Gear pump)

It is important to suppress the variation of the discharge amount of the molten resin extruded from the extruder 14 to a low level in order to improve the thickness precision of the film. It is preferable that a gear pump 16 be provided between the extruder 14 and the die 20 to supply a predetermined amount of molten resin from the gear pump 16 in view of further reducing fluctuation of the discharge amount.

The gear pump is housed in a state in which a pair of gears composed of a drive gear and a driven gear are meshed with each other. The drive gear is driven to rotate the two gears in engagement with each other so that molten resin is injected from the suction port formed in the housing into the cavity And the resin is discharged by a predetermined amount from the discharge port formed in the housing. Even if the resin pressure at the tip portion of the extruder slightly fluctuates, the fluctuation is absorbed by using the gear pump, so that the fluctuation of the resin pressure downstream of the film forming apparatus becomes very small, and the fluctuation of the thickness is improved. By using the gear pump, it is possible to make the fluctuation range of the resin pressure of the die portion within +/- 1%.

A method of changing the number of revolutions of the screw to suppress the fluctuation of the pressure applied to the thermoplastic resin before the gear pump can be used in order to improve the quantitative feed performance by the gear pump. A high-precision gear pump using three or more gears is also effective in suppressing the fluctuation of the pressure.

(filter)

It is preferable to provide the filter 18 after passing the gear pump 16 in order to prevent foreign matters from being mixed with higher accuracy. As the filter 18, a filtration apparatus having a so-called leaf type disk filter is preferable. Filtration of the thermoplastic resin discharged from the extruder may be performed by providing one filtration section, or may be multistage filtration performed by providing a plurality of filtration sections. The filtration accuracy of the filter medium is preferably high. However, from the viewpoint of considering the internal pressure of the filter medium or suppressing the increase of the filtration pressure due to clogging of the filter medium, the filtration accuracy is preferably 15 m to 3 m, more preferably 10 m to 3 m. Particularly, in the case of using a leaf disk filter device which performs final filtration of foreign matter, it is preferable to use a filter material with high filtration accuracy in terms of quality. To secure suitability of internal pressure and filter life, It is possible to adjust the internal pressure, the life of the filter, and the like.

The type of filter medium used for the filter is preferably a filter medium made of a steel material because it is used under high temperature and high pressure. Of the steel materials forming the filter material, stainless steel, steel or the like is particularly preferably used, and stainless steel is more preferably used from the viewpoint of corrosion.

As the constitution of the filter material, for example, a sintered filter material formed by sintering a metal long fiber or a metal powder can be used in addition to a filter material formed by weaving a wire material, and a sintered filter material is preferable in view of filtration accuracy and filter life.

&Lt; Melt extrusion by die &

The molten resin (melt) continuously fed to the die 20 via the extruder 14, the gear pump 16 and the filter 18 is melt-extruded from the die 20 in a film form.

As the die 20, a fish tail die and a hanger coat die may be used in addition to a commonly used T die.

A static mixer for improving the uniformity of the resin temperature may be inserted immediately before the die 20.

The slit interval (lip clearance) of the die 20 is generally 1.0 to 5.0 times, more preferably 1.2 to 3 times, and more preferably 1.3 to 2 times the thickness of the film. If the lip clearance is 1.0 times or more of the film thickness, a film having a good surface shape can be easily obtained by film formation. When the lip clearance is 5.0 times or less of the film thickness, the thickness precision of the film can be improved.

The die is one of the facilities for determining the thickness precision of the film, and it is desirable that the die can control the thickness with high accuracy. Usually, the thickness of the thickness adjusting device for adjusting the thickness of the film extruded from the die can be selected in the range of 40 mm to 50 mm in the width direction of the die. From the viewpoint that the installation interval of the thickness adjustment facility is narrower and the thickness can be controlled in detail, it is preferable to set the thickness adjustment facility at a setting interval of preferably 35 mm or less, more preferably 25 mm or less It is preferable to use a type of die capable of fine adjustment.

Further, in order to further improve the uniformity of the film, it is preferable to adjust to all the conditions which can minimize the temperature unevenness of the die and the flow rate non-uniformity in the width direction. It is also effective to use the automatic thickness adjusting die for measuring the thickness of the downstream film, calculating the thickness deviation, and feeding back the result to the die thickness adjustment.

A single-layer film-forming apparatus which is inexpensive to manufacture the film is generally used. However, if necessary, it is also possible to produce a film having two or more kinds of structures by using a multi-layer film forming apparatus in which the functional layer is provided on the outer layer of the cylinder 44. In the case of forming a multilayer film using a multilayer film forming apparatus, it is generally preferable to laminate a functional layer having a thickness thinner than that of a resin film serving as a substrate as a surface layer on the surface of the thermoplastic resin film. However, the thickness of each layer in the multilayer structure is not particularly limited.

In the calculation formula of the supply portion resin transport efficiency in the present disclosure, Q represents the extrusion amount (kg / h) of the molten resin. The amount (kg / h) of the molten resin to be extruded can be regarded as the amount of extrusion (kg / h) from the extruding port of the extruder, depending on the feed amount (kg / h) of the thermoplastic resin to the feed port of the extruder. The extrusion amount Q of the molten resin is dependent on the capacity of the cylinder of the extruder and the type of the die. From the viewpoint of performing the melt extrusion with the supply part resin transport efficiency being 0.75 or more and 1.0 or less, the extrusion amount of the molten resin is 0.5 kg / h to 1800 kg / h, and more preferably 1 kg / h to 900 kg / h.

<Cast>

Under the above conditions, the molten resin extruded into a film form from the die is cooled and solidified on a casting roll to obtain a thermoplastic resin film. Further, by heating the melt-extruded film with a far-infrared heater before the molten resin comes into contact with the casting roll, the leveling effect is developed on the drum, the surface of the melt-extruded film becomes more uniform and the film thickness distribution of the obtained film is made small And the generation of die stripes can be suppressed.

It is preferable to improve adhesion between a casting roll and a melt-extruded sheet by a method such as an electrostatic application method, an air knife method, an air chamber method, a vacuum nozzle method or a touch roll method on a casting roll on a melt-extruded film . Among them, it is preferable to use the touch roll method described above. In the touch roll method, a high temperature thermoplastic resin discharged from a die is sandwiched between a casting roll and a touch roll disposed on a casting roll, thereby cooling and shaping the film surface, that is, smoothing the film surface. The touch roll used in the present disclosure is preferably a roll having elasticity, not a roll having a normal rigidity.

The temperature of the touch roll is preferably higher than Tg-10 ° C and lower than Tg + 30 ° C, more preferably Tg-7 ° C or higher and Tg + 20 ° C or lower, more preferably Tg-5 ° C or higher and Tg + to be. In the case of using a plurality of touch rolls, it is preferable that any of the touch rolls is adjusted to the temperature reverse. It is also preferable to adjust the temperature of the casting roll to the same temperature range as the temperature range of the touch roll.

Specifically, the touch roll may be a touch roll described in, for example, Japanese Unexamined Patent Application Publication No. 11-314263 and Japanese Unexamined Patent Publication No. 11-235747. .

It is more preferable to cool the discharged thermoplastic resin by using a plurality of casting rolls. The number of the casting rolls used for the cooling is not particularly limited and is appropriately selected according to the purpose. For example, a method of using three casting rolls for the cooling of the thermoplastic resin can be cited, but the present invention is not limited thereto.

When a plurality of casting rolls are used for cooling the discharged thermoplastic resin, it is preferable that the touch roll is disposed at a position where the touch roll touches the first casting roll on the most upstream side (near the die).

The diameter of the casting roll is preferably 50 mm to 5000 mm, more preferably 100 mm to 2000 mm, and still more preferably 150 mm to 1000 mm. When a plurality of casting rolls are used, it is preferable that any casting rolls have a range of the diameter.

When a plurality of casting rolls are used, the interval between adjacent casting rolls is preferably 0.3 mm to 300 mm, more preferably 1 mm to 100 mm, and still more preferably 3 mm to 30 mm.

The line speed at the most upstream side of the casting roll is preferably 20 m / min or more and 70 m / min or less.

For example, by using a cyclic olefin resin as the thermoplastic resin, the film is produced by the above-described process under the condition that the feeding efficiency of the feeding portion resin in the present disclosure is 0.75 or more, whereby the number of foreign particles having a maximum diameter of 30 m or more It is possible to obtain a cycloolefin resin film having a number of foreign matter of not more than 0.3 number / cm ² and a maximum diameter of not less than 5 μm and not more than 30 μm of not more than 100 number / cm ² . In addition, the number and size of foreign matters included in the film produced by the manufacturing method of the present disclosure can be measured by a method in Examples described later.

The cycloolefin resin film having such a small number of foreign particles can be suitably used as an optical film for use in a liquid crystal display device or the like because of its high light transmittance and low light transmission unevenness.

The thickness of the unstretched film produced by the production method of the present disclosure may be determined depending on the application, but when it is used as an optical film, from the viewpoints of mechanical strength and light transmittance, it is preferably 20 μm to 250 μm, 25 mu m to 200 mu m, and more preferably 30 mu m to 180 mu m.

<Winding>

The cooled film (unstretched film) is peeled from the casting roll, and then wound by a nip roll (not shown).

It is also preferable to trim both ends before winding. The trimming can be carried out by a known method. As the trimming cutter used for trimming, any type of cutter such as a rotary cutter, a shear blade, and a knife may be used. As the material of the cutter, carbon steel, stainless steel, or the like can be mentioned, and a cutter of any material may be used. Generally, the trimming cutter is preferable because the life of the curl is long and the generation of cutting powder is suppressed by using a cutter having a cemented carbide blade or a ceramic blade. The portion cut by trimming may be crushed and used again as a raw material.

It is also preferable to perform knurling (knurling) at one end or both ends of the thermoplastic film. The height of the unevenness by knurling is preferably 1 to 200 占 퐉, more preferably 10 to 150 占 퐉, and still more preferably 20 to 100 占 퐉. The knurling process may be a shape in which both surfaces are convex or a shape in which one side is convex. The width of the knurl finish is preferably 1 mm to 50 mm, more preferably 3 mm to 30 mm, and still more preferably 5 mm to 20 mm. Knurling can be carried out at room temperature to 300 ° C.

When winding, it is preferable to attach a laminate film to at least one surface from the viewpoint of prevention of scratches. The thickness of the laminate film is preferably 5 占 퐉 to 200 占 퐉, preferably 10 占 퐉 to 150 占 퐉, and more preferably 15 占 퐉 to 100 占 퐉. The material of the laminate film is not particularly limited. As the material of the laminate film, for example, polyethylene, polyester, polypropylene and the like can be mentioned.

<Stretching>

The formed film can be stretched according to the purpose.

In the case of stretching, the formed film may be subjected to on-line stretching in which stretching is performed as it is, or may be performed in an off-line stretching in which the film is once wound and then stretched out and stretched.

The stretching direction may be transverse stretching in which the film is stretched in the width direction of the film, longitudinal stretching in the film forming direction of the film thus formed, or both transverse stretching and longitudinal stretching may be performed.

Further, in combination with stretching, a relaxation treatment to be described later may be performed. These can be carried out, for example, in the following combination.

As the stretching, it is preferable to perform the transverse stretching and the longitudinal stretching in combination. When transverse drawing and longitudinal drawing are performed, biaxial simultaneous drawing may be performed, or sequential drawing may be performed. Among them, it is more preferable to perform sequential stretching in which longitudinal stretching is first performed, and then transverse stretching is performed.

<Mitigation>

The dimensional stability of the resin film can be improved by carrying out a relaxation treatment after stretching the obtained resin film. The relaxation treatment is preferably a heat relaxation treatment in which the dimension of at least one of the longitudinal direction and the transverse direction of the stretched film is relaxed by, for example, about 1% to 8%. The temperature in the thermal relaxation treatment is appropriately selected depending on the kind of the thermoplastic resin used for the thermoplastic resin film, but generally 130 占 폚 to 240 占 폚 is preferable.

The thermal relaxation is preferably performed after longitudinal stretching or after transverse stretching, or both, more preferably after transverse stretching. The relaxation treatment may be performed continuously after the stretching of the thermoplastic resin film on-line, or may be performed offline with respect to the wound thermoplastic resin film after stretching.

According to the manufacturing method of the present disclosure, it is possible to produce a thermoplastic resin film having uniform physical properties, in which generation of heat deteriorated foreign matters is suppressed, with good productivity. Among them, the production method of the present disclosure is suitably applied to the production of a cycloolefin resin film in which the generation of foreign matter is greatly influenced by the quality.

The cyclic olefin resin film produced by the production method of the present disclosure can be used as an optical film alone because the generation of heat deteriorated foreign matter is suppressed and the optical characteristics are good. In addition, a functional layer such as a liquid crystal layer, a layer having a controlled refractive index (low reflection layer), or a hard coat layer may be used in combination with the polarizing plate, and the application range of the obtained cycloolefin resin film is wide.

Example

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples unless the scope of the present invention is exceeded. Unless otherwise specified, "part" is on a mass basis.

In the Examples and Comparative Examples, a resin film was basically produced by the following procedure. However, in each example, the screw flight interval W of the screw, the feed groove depth Hf, the cylinder inner diameter D of the extruder, the compression ratio, and Q / N are changed as shown in Table 1, The efficiency was adjusted.

- Coating sequence -

The resin pellets as raw materials were preliminarily dried at 100 DEG C for 5 hours.

After the preliminary drying, resin pellets were poured into a hopper provided in an extruder, and melted at 270 DEG C by an extruder. Also, the temperature is the temperature of the cylinder after the compression section.

The molten resin (melt) extruded from the extruder and transported to the gear pump through the pipe was also discharged from the gear pump and filtered by a leaf disk filter having a filtration accuracy of 5 m.

After filtration, melt (molten resin) was extruded from casting roll 1 (CR1) set at 122 DEG C from a hanger coat die having a slit interval of 1.0 mm and 270 DEG C, and the touch roll was brought into contact with the melt. Subsequently, after passing through the casting roll 2 (CR2) and the casting roll 3 (CR3), a resin film having a thickness of 100 m was obtained.

&Lt; Examples 1 to 7 >

The compression ratio and the feed groove depth (Hf (mm)) were measured using a cyclic olefin resin (ARTON (registered trademark) manufactured by JSR Corporation, specific gravity ρ: 1.08 (g / cm ³ ), glass transition temperature ), The inner diameter (D) of the cylinder of the extruder, or the Q / N ratio as shown in Table 1 (the temperature of the extruder feeding portion A was changed) did. The screw of the extruder is of a full flight type, and the screw flight angle is 17.7 DEG.

&Lt; Example 8 >

Melt extrusion was carried out in the same manner as in Example 1 except that the raw material resin was changed to polycarbonate in Example 1.

<Example 1-a to Example 1-i>

The melt extrusion was carried out in the same manner as in Example 1 except that the oxygen concentration, the injected resin temperature, the use of the vacuum hopper, the screw, or the screw temperature were changed in the feed port of the extruder. In addition, the screw flight angle in the double flight type supply portion in Examples 1-a to 1-i is 17.7 °.

&Lt; Comparative Example 1-1 >

In Example 1-i, melt extrusion was carried out in the same manner as in Example 1-i, except that the feed-portion resin transport efficiency was adjusted to 0.65 by changing the Q / N ratio to 0.56 by changing the cylinder temperature of the extruder supply portion C1 .

&Lt; Comparative Example 1-2 >

In Example 1-i, melt extrusion was carried out in the same manner as in Example 1-i, except that the compression ratio was set to 3.1 and the feeding portion resin transport efficiency was adjusted to 1.16.

&Lt; Comparative Example 1-3 >

In Comparative Example 1-1, melt extrusion was carried out in the same manner as in Comparative Example 1-1 except that the oxygen concentration was 8 ppm by continuously supplying nitrogen gas to the feed port.

&Lt; Comparative Example 6 >

In Example 6, melt extrusion was carried out in the same manner as in Example 6, except that the Q / N ratio was 1.76, the feed-portion resin transport efficiency was 0.68, and the double flight type was used as the screw.

[evaluation]

&Lt; Evaluation of the number of foreign bodies &

The number of foreign matters in the resin film (thickness: 100 mu m) produced in each example was measured using a differential interference microscope (200 times) manufactured by Nikon Corporation in the range of 10 cm x 10 cm in the center portion of the film. In the measurement, the number of foreign objects having a maximum length of 30 占 퐉 or more and the number of foreign objects having a maximum length of 5 占 퐉 or more and less than 30 占 퐉 were recorded.

&Lt; Evaluation of Yellowness &

The resin film (thickness: 100 占 퐉) prepared in each example was subjected to Lab measurement using a color difference meter (SM-T, manufactured by Suga Shikeki Co., Ltd.), and the yellowness was evaluated by b value. It is evaluated that the smaller the value of the b value is, the lower the yellowness degree and the coloring of the resin film is suppressed.

Table 1 shows the melt extrusion conditions and evaluation results of the films prepared in the respective examples.

[Table 1]

As shown in Table 1, and supply the resin transport efficiency of 0.75 or more in each of the examples under the conditions that meet the 1.0 subjected to melt extrusion, the number of foreign matter greater than the longest diameter 30μm 0.3, all / cm ² or less, and the longest diameter Cm &lt; ² &gt; or less. In addition, a cyclic polyolefin film with high light transmittance suppressed in coloring (yellow) was obtained.

The disclosure of Japanese Patent Application 2016-011074, filed on January 22, 2016, is hereby incorporated by reference.

All documents, patent applications, and technical specifications described in this specification are herein incorporated by reference in their entirety to the same extent as if each individual document, patent application, do.

Claims (8)

A cylinder having a supply port through which a raw material resin is fed and an extrusion port through which a molten resin melted by the raw material resin is extruded; a screw arranged around the screw shaft and the screw shaft in a spiral shape; Wherein the feed unit resin transport efficiency calculated by the following equation using an extruder having a feed unit, a compression unit and a metering unit in the cylinder in order from the feed port side along the screw axis is 0.75? Feed unit resin transport efficiency? 1.0 And supplying and melting the raw material resin under the condition that the molten resin is extruded from the extruding port and melt-extruding the molten resin extruded from the extruding port into a film form from the die.
[Equation 1]

W: screw flight distance (mm)
Hf: groove depth in the supply part (mm)
D: Inner diameter of cylinder (mm)
Ψ: screw flight angle (°) in the supply part
Q: Extrusion amount of molten resin (kg / h)
ρ: specific gravity of the raw resin (g / cm ³ )
N: screw rotation rate per minute (rpm)
Compression ratio: Volume per screw pitch in the feed section / volume per screw pitch in the metering section The method according to claim 1,
Wherein the oxygen concentration in said feed port is 0.1% or less. The method according to claim 1 or 2,
Wherein a temperature of the raw resin supplied into the cylinder from the supply port is Tg-90 占 폚 or higher and Tg + 10 占 폚 or lower when the glass transition temperature of the raw material resin is Tg 占 폚. The method according to any one of claims 1 to 3,
And feeding the raw material resin into the cylinder through the supply port through a vacuum hopper. The method according to any one of claims 1 to 4,
Wherein the screw is a double flight screw. The method according to any one of claims 1 to 5,
Wherein the temperature of the screw in the supply portion is controlled to be Tg-80 DEG C or more and Tg DEG C or less when the glass transition temperature of the raw material resin is Tg DEG C. The method according to any one of claims 1 to 6,
Wherein the raw material resin is a cyclic olefin resin. , The number of foreign matter greater than 0.3 is a maximum diameter of 30μm thickness 100μm per dog / cm ² or less, and the number of foreign matter 100 is less than 30μm is more than a maximum diameter of 5μm pieces / cm ² or less cyclic olefin resin film.

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