JPWO2017126572A1 - Method for producing thermoplastic resin film and cyclic olefin resin film - Google Patents

Abstract

Using an extruder having a supply section, a compression section, and a metering section, a molten resin that is supplied and melted from the extrusion port under the condition that satisfies 0.75 ≦ supply section resin transport efficiency ≦ 1.0 A method for producing a thermoplastic resin film having a step of melt-extruding a resin from a die into a film and its application. W is the screw flight interval, Hf is the groove depth in the supply section, D is the inner diameter of the cylinder, ψ is the screw flight angle, Q is the extrusion amount of the molten resin, ρ is the specific gravity of the raw resin, N is The number of screw rotations per minute is shown.

Description

  The present disclosure relates to a method for producing a thermoplastic resin film and a cyclic olefin resin film.

  Thermoplastic resin films are used in various applications such as optical films and solar cell back surface protective films. For example, as an optical film used for a liquid crystal display device or the like, a cellulose resin film such as a cellulose acylate film is used.

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

  In recent years, a cyclic olefin resin film has attracted attention as a film having a small change in optical properties with respect to changes in environmental temperature and humidity, and it has been studied to melt the cyclic olefin resin and use it as a film for polarizing plates and liquid crystal displays. ing.

When a thermoplastic resin film is produced by the melt extrusion method, the resin may be thermally oxidized and deteriorated to generate foreign matter (hereinafter, sometimes referred to as “thermally deteriorated foreign matter”). In particular, in the case of an optical film, the foreign matter contained in the film becomes a point defect, which has a great influence on the quality of the optical film, such as a decrease in light transmission due to the point defect and an increase in unevenness.
As a measure for suppressing the generation of heat-deteriorated foreign matter, for example, in Japanese Patent Application Laid-Open No. 2008-137328, the oxygen concentration at the opening of an extruder used for melt film formation is set to 10 ppm or less in an inert gas atmosphere. Thus, it is disclosed that thermal oxidation deterioration of the resin is suppressed.

  As in the method disclosed in Japanese Patent Application Laid-Open No. 2008-137328, in order to make the oxygen concentration at the opening of the extruder 10 ppm or less, a large atmosphere replacement 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 the generation of heat-degraded foreign matter without performing extensive atmosphere replacement. . The subject of another embodiment of this invention is providing the cyclic olefin resin film with high light transmittance.

The present disclosure includes the following embodiments.
<1> A cylinder having a supply port to which the raw material resin is supplied and an extrusion port from which the molten resin in which the raw material resin is melted is extruded, a screw shaft and a flight spirally arranged around the screw shaft, A supply part resin calculated by the following formula using an extruder having a supply part, a compression part and a metering part in order from the supply port side along the screw axis in the cylinder. The process of supplying and melting the raw material resin under the condition that the transport efficiency satisfies 0.75 ≦ supply part resin transport efficiency ≦ 1.0, and melt-extruding the molten resin extruded from the extrusion port into a film form from the die. A method for producing a thermoplastic resin film.

W: Screw flight interval (mm) in the supply section
Hf: Groove depth in the supply section (mm)
D: Inner diameter of cylinder (mm)
Ψ: Screw flight angle (°) in the supply section
Q: Extrusion amount of molten resin (kg / h)
ρ: Specific gravity of raw resin (g / cm ³ )
N: Number of screw rotations per minute (rpm)
Compression ratio: Volume per pitch of screw flights in the supply section / Volume per pitch of screw flights in the measuring section

<2> The method for producing a thermoplastic resin film according to <1>, wherein the oxygen concentration in the supply port is 0.1% or less.
<3> When the glass transition temperature of the raw material resin is Tg ° C., the temperature of the raw material resin supplied into the cylinder from the supply port is Tg−90 ° C. or more and Tg + 10 ° C. or less <1> or <2> The manufacturing method of the thermoplastic resin film of description.
<4> The method for producing a thermoplastic resin film according to any one of <1> to <3>, wherein the raw material resin is supplied from the supply port into the cylinder through a vacuum hopper.
<5> The method for producing a thermoplastic resin film according to any one of <1> to <4>, wherein the screw is a double flight screw.
<6> When the glass transition temperature of the raw material resin is Tg ° C, the screw temperature in the supply unit is controlled to any one of <1> to <5>, which is Tg-80 ° C or higher and Tg ° C or lower. The manufacturing method of the thermoplastic resin film of description.
<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 matters having a longest diameter of 30 μm or more is 0.3 pieces / cm ² or less per 100 μm thickness, and the number of foreign matters having a longest diameter of 5 μm or more and less than 30 μm is 100 pieces / cm ² or less. Olefin resin film.

  According to one embodiment of the present invention, there is provided a method for producing a thermoplastic resin film capable of producing a thermoplastic resin film while suppressing the generation of heat-degraded foreign matter without performing large-scale atmosphere replacement. Moreover, according to another embodiment of this invention, a cyclic olefin resin film with high light transmittance is provided.

FIG. 1 is a schematic diagram illustrating an example of the overall configuration of an apparatus for carrying out the method for producing a thermoplastic resin film of the present disclosure. FIG. 2 is a schematic diagram illustrating an example of a configuration of an extruder that can be used in the manufacturing method of the present disclosure. FIG. 3 is an enlarged schematic view showing a supply section of the extruder shown in FIG.

Hereinafter, a method for producing a thermoplastic resin film and a cyclic olefin resin film of the present disclosure will be specifically described with reference to the accompanying drawings. In the following description, reference numerals may be omitted.
In addition, in the following description, “to” representing a numerical range means a range including numerical values described as lower and upper limits before and after that, and when only the upper limit or the lower limit is attached with a unit. , Meaning the same unit throughout the numerical range.
In this specification, the term “process” is not only an independent process, but is included in this term if the intended purpose of the process is achieved even when it cannot be clearly distinguished from other processes.
In the present specification, “(co) polymer” means either or both of a homopolymer and a copolymer containing a specific repeating unit.
In the numerical ranges described stepwise in the present specification, the upper limit value or lower limit value described in a numerical range may be replaced with the upper limit value or lower limit value of the numerical range described in other steps. . Further, in the numerical ranges described in this specification, the upper limit value or the lower limit value described in a certain numerical range may be replaced with the values shown in the examples.

  A 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 supply port to which a raw material resin is supplied and an extrusion port from which a molten resin in which the raw material resin is melted is extruded. A cylinder, a screw shaft and a screw spirally arranged around the screw shaft, and a screw that rotates in the cylinder, and the supply unit in order from the supply port side along the screw shaft in the cylinder Using a extruder having a compression part and a metering part, supply and melting of the raw material resin under the condition that the supply part resin transport efficiency calculated by the following formula satisfies 0.75 ≦ supply part resin transport efficiency ≦ 1.0 And a step of melt-extruding the molten resin extruded from the extrusion port into a film shape from the die.

The meanings of the symbols in the formula for calculating the supply part resin transport efficiency are as follows, and details will be described later.
W: Screw flight interval (mm) in the supply section
Hf: Groove depth in the supply section (mm)
D: Inner diameter of cylinder (mm)
Ψ: Screw flight angle (°) in the supply section
Q: Extrusion amount of molten resin (kg / h)
ρ: Specific gravity of raw resin (g / cm ³ )
N: Number of screw rotations per minute (rpm)
Compression ratio: Volume per pitch of screw flights in the supply section / Volume per pitch of screw flights in the measuring section

In the present specification, the “raw resin” means a resin composition containing not only a resin component but also an additive added as necessary.
Further, the thermoplastic resin may be referred to as “resin”, and the thermoplastic resin film may be referred to as “film”.

First, an outline of a manufacturing apparatus and a manufacturing method used in the method for manufacturing a thermoplastic resin film of the present disclosure will be described.
FIG. 1 schematically shows an example of the entire configuration of a film forming apparatus (thermoplastic resin film manufacturing apparatus) for carrying out the method for manufacturing a thermoplastic resin film of the present disclosure.
A film forming apparatus 10 shown in FIG. 1 includes a hopper 12 into which a thermoplastic resin as a raw material resin is charged, an extruder 14 for melting the thermoplastic resin supplied from the hopper 12, and a molten resin (molten resin). A gear pump 16 that stabilizes the extrusion amount, a filter 18 that filters the molten resin, a die 20 that melt-extrudes the molten resin into a film, and a plurality of coolings that cool the high-temperature thermoplastic resin discharged from the die 20 in multiple stages. Contact rolls (hereinafter referred to as contact rolls) that sandwich the thermoplastic resin 100 discharged from the rolls (hereinafter, the cooling rolls may be referred to as casting rolls) 22, 24, 26 and the die 20 with the first cooling rolls 22. Is sometimes referred to as a touch roll) 28. Although not shown, normally, a peeling roll for peeling the thermoplastic resin film 100 from the last third cooling roll 26 and a winder for winding the cooled film are provided.

FIG. 2 schematically shows an example of the configuration of an extruder that can be used 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 to which a thermoplastic resin is supplied and an extrusion port 54 to which a molten resin in which the thermoplastic resin is melted is extruded. The inside of the cylinder 44 is along the screw shaft 46 along the supply port 52 side. In order, a supply part (region indicated by A in FIG. 2) for transporting the thermoplastic resin supplied from the supply port 52 while preheating, and a compression part (in FIG. 2) for kneading and melting the thermoplastic resin while compressing. B) and a metering unit (region indicated by C in FIG. 2) that measures the melted resin and stabilizes the extrusion amount. FIG. 3 is an enlarged schematic view of the supply section A of the extruder 14.
Further, the hopper 12 shown in FIG. 1 is attached to the supply port 52 of the cylinder 44 shown in FIG.

  The screw 50 has a screw shaft 46 and a flight (hereinafter also referred to as a screw flight) 48 arranged in a spiral shape around the screw shaft 46 and is rotated in a cylinder 44 by a motor (not shown). Has been.

  Although not shown, in order to control the temperature of the resin in the cylinder 44, a temperature control means (a heater or the like) arranged in the longitudinal direction, for example, by dividing into 3 to 20 is provided around the cylinder 44. It is preferable to provide it.

  When an extruder 14 having the configuration shown in FIG. 2 is provided and a thermoplastic resin film is manufactured by the thermoplastic resin film manufacturing apparatus 10 having the configuration shown in FIG. 1, a thermoplastic resin as a raw material resin is introduced into the hopper 12. The gas 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 part A by the rotation of the screw 50.

  In order to prevent the molten resin from being oxidized by the remaining oxygen in the cylinder 44, it is more preferable to carry out the inside of the extruder in an inert air stream such as nitrogen or using a vented extruder while evacuating. .

  The thermoplastic resin preheated in the supply part A is transported to the compression part B. The compression part B has a configuration in which the diameter of the screw shaft 46 gradually increases toward the extrusion port 54, and the thermoplastic resin is transferred between the inner wall of the cylinder 44 and the screw 50 along with the transport in the compression part B. The mixture is kneaded while being compressed, and is heated and brought into contact with the temperature-controlled cylinder 44 to melt. The resin melted in the compression unit B is transported to the metering unit C, and the metering unit C measures the molten resin, and the amount of extrusion from the extrusion port 54 is stabilized.

The molten resin melted by the extruder 14 and extruded from the extrusion port 54 is continuously fed toward the die 20 through the pipe 40 through the gear pump 16 and the filter 18. The molten resin is melt extruded from the die 20 into a film. A thermoplastic resin 100 extruded into a film is shown in FIG.
The film-like thermoplastic resin melt-extruded from the die 20 is sandwiched between the contact roll (touch roll) 28 and the first cooling roll 22, passed through the second cooling roll 24 and the third cooling roll 26, It is wound up by the illustrated winder.

  In the manufacturing method of the thermoplastic resin film of the present disclosure, when the thermoplastic resin film is manufactured through the steps as described above, the supply part resin transport efficiency calculated by the above-described formula is 0.75 ≦ supply part resin transport. The thermoplastic resin is supplied and melted under a condition satisfying efficiency ≦ 1.0, and the resin melted by the extruder is melt-extruded from the die into a film.

The reason why generation of thermally deteriorated foreign matter is suppressed in the film obtained by the method for producing a thermoplastic resin film of the present disclosure is estimated as follows.
In the formula for calculating the supply resin transport efficiency in the present disclosure, the fractional molecule “Q / N” in the first term means the amount of molten resin extruded per screw rotation 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 the theoretical transport amount is divided by the compression ratio so that it can be transported with high efficiency regardless of the compression ratio. Further, (D / 90) ^0.5 is a correction coefficient for the cylinder inner diameter.

Then, the supply resin transport efficiency calculated by the formula of the supply resin transport efficiency in the present disclosure is 0.75 or more, that is, the solid resin transport efficiency before melting in the extruder supply unit is increased, and the original resin density By reducing the voids of the solid resin in the extruder to a region close to, and then melting, it becomes difficult for the oxygen in the voids to contact the molten resin. On the other hand, melt extrusion can be performed by setting the resin transport efficiency of the supply section to 1.0 or less.
Therefore, it is considered that a thermoplastic resin film in which the generation of heat-deteriorated foreign matter generated by the reaction between the resin and oxygen in the obtained film is suppressed can be produced without requiring a large atmosphere replacement.

  Next, the manufacturing method of the thermoplastic resin film of the present disclosure will be described more specifically. In addition, the example which manufactures a cyclic olefin resin film suitably using cyclic olefin resin as raw material resin is demonstrated. However, the method for producing a thermoplastic resin film of the present disclosure is not limited to the method for producing a cyclic olefin resin film described below, and is also suitable for producing a thermoplastic resin film using a thermoplastic resin other than the cyclic olefin resin. Can be applied to.

<Raw resin>
The raw material resin used in the present disclosure is not particularly limited as long as it is a thermoplastic resin, and may be selected according to the application of the film to be produced.
For example, when an optical film is produced, an acrylic resin, a methacrylic resin, a polycarbonate (PC) resin, or a cyclic olefin resin is preferably used as the thermoplastic resin from the viewpoint of good transparency of the resulting film. Can do. Of these, cyclic olefin resins are preferred.
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-based polymer and (2) a monocyclic cyclic olefin polymer. And (3) a polymer of a cyclic conjugated diene, (4) a vinyl alicyclic hydrocarbon polymer, and hydrides of (1) to (4).

Among these, (1) a norbornene polymer and (2) a polymer of a monocyclic olefin and a hydride thereof are preferable.
In addition, the norbornene-type polymer in this specification is used by the meaning containing the homopolymer and the copolymer containing the repeating unit which has a norbornene structure, and a ring-opening may be sufficient as a norbornene structure.
For example, as a polymer resin having a cyclic olefin structure, an addition (co) polymer cyclic polyolefin containing at least one repeating unit represented by the following general formula (II) and, if necessary, a general formula (I) An addition copolymer cyclic polyolefin further comprising at least one or more repeating units represented.
Moreover, 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) can also be suitably used.

In general formula (I), (II), and (III), m represents the integer of 0-4. R ¹ , R ² , R ³ , R ⁴ , R ⁵ , and R ⁶ each independently represent a hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms, and X ¹ , X ² , X ³ , Y ¹ , Y ² and Y ³ are each independently a hydrogen atom, a hydrocarbon group having 1 to 10 carbon atoms, a halogen atom, a hydrocarbon group having 1 to 10 carbon atoms substituted with a halogen atom,-(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 (—CO) ₂ O composed of NR ¹³ R ¹⁴ , — (CH ₂ ) _n OZ, — (CH ₂ ) _n W, or X ¹ and Y ¹ , X ² and Y ² , or X ³ and Y ³ Alternatively, (—CO) ₂ NR ¹⁵ is represented. R ¹¹ , R ¹² , R ¹³ , R ¹⁴ , and R ¹⁵ represent a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms, Z represents a hydrocarbon group or a hydrocarbon group substituted with a halogen, W represents SiR ¹⁶ _p D _3-p , (R ¹⁶ represents a hydrocarbon group having 1 to 10 carbon atoms, D represents a halogen atom, —OCOR ¹⁶ or —OR ¹⁶ , and p is an integer of 0 to 3 N represents an integer of 0 to 10.

By introducing a highly polarizable functional group into all or part of the substituents of X ¹ , X ² , X ³ , Y ¹ , Y ² and Y ³ , the retardation in the thickness direction (Rth) of the optical film is reduced. It is possible to increase the expression of in-plane retardation (Re). A film having a high Re developability can increase the Re value by stretching in the film forming process.
The functional group having a large polarizability means a functional group containing two or more types of atoms having different electronegativity and having a dipole moment. Specific examples of functional groups having a large degree of polarity include, for example, a carboxy group, a carbonyl group, an epoxy group, an ether group, a hydroxy group, an amino group, an imino group, a cyano group, an amide group, an imide group, an ester group, and a sulfone group. Etc.

Norbornene-based addition (co) polymers are disclosed in JP-A-10-7732, JP-T-2002-504184, US Patent Publication US2004 / 229157A1, International Publication WO2004 / 070463A1, and the like. The norbornene-based addition (co) polymer is obtained, for example, by addition polymerization of norbornene-based polycyclic unsaturated compounds. In addition, a norbornene-based addition (co) polymer includes, if necessary, a norbornene-based polycyclic unsaturated compound, ethylene, propylene, butene; conjugated dienes such as butadiene and isoprene; non-conjugated dienes such as ethylidene norbornene; acrylonitrile It can also be obtained by addition polymerization with linear diene compounds such as acrylic acid, methacrylic acid, maleic anhydride, acrylic acid ester, methacrylic acid ester, maleimide, vinyl acetate, and vinyl chloride.
A commercially available product may be used as the norbornene-based addition (co) polymer. The norbornene-based addition (co) polymer is commercially available from Mitsui Chemicals, Inc. under the name of Apel (registered trademark), and has a different glass transition temperature (Tg), such as APL8008T (Tg: 70 ° C.), APL6013T ( Grades such as Tg: 125 ° C) and APL6015T (Tg: 145 ° C). Norbornene-based addition (co) polymers such as TOPAS 8007, 6013, and 6015 are commercially available as pellets from Polyplastics. Furthermore, Appear 3000 is commercially available as a norbornene addition (co) polymer from Ferrania.

A hydride of a norbornene-based polymer can be obtained by subjecting a polycyclic unsaturated compound to addition polymerization or metathesis ring-opening polymerization and then hydrogenation. As for the hydride of norbornene-based polymer, for example, JP-A-1-240517, JP-A-7-196736, JP-A-60-26024, JP-A-62-19807, JP-A-2003-159767 and No. 2004-309979 and the like, and the description thereof can be referred to the present disclosure.
The norbornene-based polymer used in the production method of the present disclosure is preferably a polymer containing a cyclic repeating unit represented by the general formula (III). In the cyclic repeating unit represented by the general formula (III), R ⁵ and ^{R 6} is preferably a hydrogen atom or -CH _3, ^{X 3,} and ^{Y 3} is a hydrogen atom, it is -Cl or -COOCH ₃ preferably, the other groups are selected appropriately.
Norbornene-based resins are commercially available from JSR Corporation under the trade name Arton (registered trademark) G or Arton F, and from Zeon Corporation, Zeonor (registered trademark) ZF14, ZF16, Zeonex (Zeonex). : Registered trademark) 250 or ZEONEX 280, which are commercially available, and these can be used.

  Further, in the production method of the present disclosure, various additives according to the use of the film to be produced, such as a deterioration inhibitor, an ultraviolet ray inhibitor, a retardation (optical anisotropy) modifier, fine particles, a peeling accelerator, An infrared absorber or the like can be used. The additive may be solid or oily.

In addition, in the calculation formula of the supply part resin transport efficiency in the present disclosure, ρ indicates the specific gravity (g / cm ³ ) of the raw material resin (thermoplastic resin), and the supply part is in accordance with the specific gravity ρ of the resin used. Other parameters of resin transport efficiency may be set.

It is preferable that the thermoplastic resin as the raw material resin and the additive added as necessary are mixed in advance and pelletized prior to melt film formation.
It is preferable to dry the thermoplastic resin in advance for pelletization. When using a solid additive, it is preferable to dry the additive in advance. When drying a thermoplastic resin, a drying method and drying conditions are not particularly limited. Examples of the drying method include a method of heating in a heating furnace at a temperature of 80 ° C. to 110 ° C., preferably around 90 ° C., for a heating time of 8 hours or longer, preferably 8 hours to 12 hours. This is not the case. The heating temperature and heating time for 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.
In the case where the additive has fluidity such as an oily substance, it may be put into the extruder as it is and mixed with the thermoplastic resin in the extruder.

When pelletizing the thermoplastic resin, for example, by using a vent type extruder, drying of the thermoplastic resin, which is preferably performed in advance, can be omitted.
Additives added as necessary when pelletizing the thermoplastic resin are not mixed with the thermoplastic resin in advance, but are added from the raw material inlet or vent port in the middle of the extruder used for pelletization You can also

The size of the pellets, for example, the cross-sectional area of ^{1 mm} 2 to 300 mm ^2, the length 1mm~30mm by weight, more preferably cross-sectional area ^{2 mm} 2 100 mm ^2, length 1.5Mm～10mm.

It is preferable to reduce the moisture in the pellets prior to melt film formation. The method for drying the pellet is not particularly limited as long as the desired moisture content can be obtained. Usually, drying using a dehumidifying air dryer is often performed. It is preferable to efficiently dry the pellets by using means such as heating, blowing, decompressing, stirring, etc. alone 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 dry hopper to be used has a heat insulating structure.
The drying temperature when 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 moisture 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 further preferably 0.01% by mass or less.

<Supply of raw material resin to the extruder>
Raw material resin is put into the hopper 12 and supplied into the cylinder 44 from the supply port 52 of the cylinder 44. The raw material resin charged into the hopper 12 may be a thermoplastic resin pellet, 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 at the supply port 52 is preferably low, and specifically, it is preferably 0.1% or less on a volume basis. Examples of a method for reducing the oxygen concentration at the supply port 52 include a method of supplying a raw material resin into the cylinder 44 from the supply port 52 through a vacuum hopper, and a method of supplying nitrogen gas to the supply port 52 of the cylinder 44. The oxygen concentration at the supply port 52 can be measured by providing a pipe (not shown) at the supply port 52 and connecting an oxygen concentration meter (not shown).

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

The resin supplied into the cylinder 44 is gradually heated by friction caused by the rotation of the screw 50 and temperature control means (not shown) arranged around the cylinder 44. From the viewpoint of supplying the raw material resin from the supply port 52 and quickly melting the thermoplastic resin in the cylinder 44, it is preferable that the thermoplastic resin is supplied from the supply port in a heated state.
When the glass transition temperature of the thermoplastic resin is Tg (° C.), the temperature of the thermoplastic resin supplied from the supply port 52 into the cylinder 44 is preferably Tg−90 ° C. or higher and Tg + 10 ° C. or lower. It is more preferable to control to −80 ° C. or higher and Tg−10 ° C. or lower. As a method of controlling the temperature of the thermoplastic resin supplied into the cylinder 44 from the supply port 52 to the above preferable range, a method of preheating pellets to be put into the hopper, a method using a hopper equipped with a heating means, In addition to the hopper, there may be mentioned a method of providing a heating means in the vicinity of the supply port.

<Melting of raw material 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 part A by the rotation of the screw 50.
In the calculation formula of the supply part resin transport efficiency in the present disclosure, W indicates the flight interval (mm) of the screw 50 in the supply part in the cylinder. The screw flight interval W is preferably 10 mm to 300 mm, and more preferably 20 mm to 250 mm, from the viewpoint of carrying out melt extrusion with the supply part resin transport efficiency of 0.75 to 1.0.

  Moreover, in the calculation formula of the supply part resin transport efficiency in the present disclosure, ψ indicates the screw flight angle (°) in the supply part A. The screw flight angle Ψ in the supply part A is preferably 5 ° to 30 °, more preferably 10 ° to 25 °, from the viewpoint of carrying out melt extrusion with the supply part resin transport efficiency of 0.75 to 1.0. .

  A full flight, a double flight, or the like can be adopted as a flight in the screw. From the viewpoint of promoting the melt kneading of the resin in the compression part B, a double flight screw is preferable. The double flight screw is a screw in which two flights are spirally arranged on the screw shaft in the compression section B.

  In the calculation formula of the supply part resin transport efficiency in the present disclosure, Hf is the groove depth (mm) in the supply part A, that is, the screw shaft radial direction from the outer peripheral surface of the screw shaft in the supply part A to the outer periphery of the screw flight. The distance (hereinafter may be referred to as “supply section groove depth”) is shown. Supply section groove depth Hf is preferably 2 mm to 30 mm, and more preferably 3 mm to 25 mm, from the viewpoint of carrying out melt extrusion with a supply section resin transport efficiency of 0.75 to 1.0. The supply section 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 section, and the height of the screw flight 48.

The resin supplied into the cylinder 44 is gradually heated by friction caused by the rotation of the screw 50.
In the calculation formula for the supply resin transport efficiency in the present disclosure, N indicates the screw rotation speed (rpm: rotation / min). In the method of manufacturing a thermoplastic resin film of the present disclosure, the screw is rotated in a state where the thermoplastic resin is dense in the supply unit. Therefore, the screw is normally rotated at a relatively low speed with a high torque. It will be. From this viewpoint, the screw rotation speed (rpm) in the manufacturing method of the present disclosure is preferably 3 rpm to 150 rpm, and more preferably 5 rpm to 100 rpm.

In the supply part A, it is not necessary to melt all the thermoplastic resin in the cylinder 44, but in the compression part B, all the thermoplastic resin needs to be melted. On the other hand, in order to smoothly feed the raw material resin to the compression part B side by the rotation of the screw 50 in the supply part A, the difference in the friction force between the screw 50, the cylinder 44 and the resin in the supply part A and the compression part B. It is preferable that there is.
In general, if the cylinder 44 is at a high temperature, the frictional force of the resin with respect to the cylinder 44 is increased. If the screw 50 is at a low temperature, the frictional force of the resin with respect to the screw 50 is decreased, resulting in a frictional force difference. It becomes the relationship that it becomes easy to send to the compression part B side. When the glass transition temperature of the thermoplastic resin is Tg (° C.), if the temperature of the screw 50 is set higher than Tg and is set to a temperature at which the raw material resin is softened by the supply unit A, the frictional force of the resin against the screw 50 and There is a possibility that the difference in the frictional force of the resin with respect to the cylinder 44 becomes small and it is difficult to proceed to the compression part B where the resin is melted. From this viewpoint, it is preferable to control the temperature of the screw in the supply part A to Tg-80 ° C or more and Tg ° C or less, and more preferably Tg-70 ° C or more and Tg-10 ° C or less. For example, the temperature of the screw can be controlled with high accuracy by using a screw having a structure that circulates and supplies a heat medium inside the screw shaft.

The resin heated by the supply unit A is transported to the compression unit B by the rotation of the screw, and is further heated and melted by the compression unit B. The resin melted in the compression part B (molten resin) is further transported to the measuring part C.
In the calculation formula for the supply unit resin transport efficiency in the present disclosure, the compression ratio indicates “volume per screw flight pitch in the supply unit / volume per screw flight pitch in the metering unit”. The compression ratio is calculated using the outer diameter d1 of the screw shaft of the supply unit A, the outer diameter d2 of the screw shaft of the measuring unit C, the groove depth Hf of the supplying unit A, and the groove depth Hm of the measuring unit C. The

If the compression ratio is too small, the thermoplastic resin is not sufficiently melt-kneaded, an undissolved portion is generated, undissolved foreign matter tends to remain in the manufactured thermoplastic film, and air bubbles are easily mixed. As a result, the strength of the thermoplastic film may decrease, or the film may be easily broken when it is stretched, and the orientation may not be sufficiently increased. On the other hand, if the compression ratio is too large, the shear stress applied to the thermoplastic resin becomes too large and the resin is likely to deteriorate due to heat generation, so that there is a possibility that a yellowish color is likely to appear on the thermoplastic film after production. Further, if the shear stress applied to the thermoplastic resin becomes too large, molecules may be cut in the thermoplastic resin, the molecular weight may be reduced, and the mechanical strength of the film may be reduced.
The compression ratio is preferably from 1.5 to 4.0, more preferably from 2.0 to 3.5, from the viewpoints described above and from the viewpoint of carrying out melt extrusion by setting the resin transport efficiency of the supply section to 0.75 to 1.0. preferable. The compression ratio is adjusted by adjusting at least one of the inner diameter D of the cylinder 44, the outer diameters d1 and d2 of the screw shafts in the supply unit and the metering unit, the flight interval W of the screw 50, and the flight angle Ψ. Can do.

In the calculation formula of the supply part 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 ° C to 300 ° C.
The set temperature in the extruder may be the same temperature in the entire region, or may have a different temperature distribution depending on the region. It is preferable that the temperature distribution is different depending on the region. In particular, it is more preferable that the temperature of the supply unit A described above is higher than the temperature of the compression unit B in the extruder.

If L / D is too small, the thermoplastic resin in the extruder will be insufficiently melted or kneaded, and undissolved foreign matter may easily be generated in the manufactured thermoplastic film as in the case where the compression ratio is small. There is. 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 be deteriorated. In addition, if the residence time becomes long, molecular cutting may occur in the thermoplastic resin, or the molecular weight of the thermoplastic resin may decrease due to molecular cutting, and the mechanical strength of the thermoplastic film may decrease. .
From this viewpoint, L / D is preferably in the range of 20 to 70, more preferably in the range of 22 to 60, and still more preferably in the range of 24 to 50.

  The molten resin is extruded from the extrusion port 54 of the cylinder 44 through the measuring section C. In the measurement part C, the molten resin is measured, and the extrusion amount from the extrusion port 54 is stabilized.

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

(Gear pump)
In order to improve the thickness accuracy of the film, it is important to keep the variation in the discharge amount of the molten resin extruded from the extruder 14 low. From the viewpoint of further reducing fluctuations in the discharge amount, it is preferable to provide a gear pump 16 between the extruder 14 and the die 20 and supply a certain amount of molten resin from the gear pump 16.
The gear pump is accommodated in a state in which a pair of gears composed of a drive gear and a driven gear mesh with each other, and the drive gear is driven to engage and rotate the two gears so that the gear pump is melted from the suction port formed in the housing. Resin is sucked into the cavity, and a certain amount of resin is discharged from a discharge port also formed in the housing. Even if the resin pressure at the tip portion of the extruder varies slightly, by using the gear pump, the variation is absorbed, the variation in the resin pressure downstream of the film forming apparatus becomes very small, and the thickness variation is improved. By using a gear pump, it is possible to keep the fluctuation range of the resin pressure in the die portion within ± 1%.

  In order to improve the quantitative supply performance by the gear pump, it is also possible to use a method of changing the number of rotations of the screw to suppress the pressure fluctuation applied to the thermoplastic resin before the gear pump. A high-precision gear pump using three or more gears is also effective in suppressing pressure fluctuations.

(filter)
In order to prevent foreign matters from being mixed with higher accuracy, it is preferable to provide the filter 18 after passing through the gear pump 16. The filter 18 is preferably a filtration device incorporating a so-called leaf type disk filter. Filtration of the thermoplastic resin discharged from the extruder may be filtration performed by providing one filtration unit, or multistage filtration performed by providing a plurality of filtration units. It is preferable that the filtration accuracy of the filter medium is higher. However, the filtration accuracy is preferably 15 μm to 3 μm, and more preferably 10 μm to 3 μm, from the viewpoint of considering the pressure resistance of the filter medium or suppressing an increase in the filtration pressure due to clogging of the filter medium. In particular, when using a leaf-type disk filter device that finally filters foreign matter, it is preferable to use a filter medium with high filtration accuracy in terms of quality, and in order to ensure the appropriate pressure resistance and filter life, the filtration section The pressure resistance, filter life, etc. can be adjusted by the number of filter media loaded in the filter.

The type of filter medium used for the filter is preferably a filter medium formed of a steel material because it is used under high temperature and pressure. Of the steel materials forming the filter medium, stainless steel, steel and the like are particularly preferred, and stainless steel is more preferred from the viewpoint of corrosion.
As the structure of the filter medium, in addition to the filter medium formed by knitting a wire, for example, a sintered filter medium formed by sintering a metal long fiber or metal powder can be used. From the viewpoint of filtration accuracy and filter life, the sintered filter medium can be used. Is preferred.

<Melt extrusion by die>
The molten resin (melt) continuously sent to the die 20 through the extruder 14, the gear pump 16 and the filter 18 is melt-extruded from the die 20 into a film.

As the die 20, a fish tail die or 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 placed immediately before the die 20.
The slit interval (lip clearance) of the die 20 is generally preferably 1.0 to 5.0 times the film thickness, more preferably 1.2 to 3 times, and even more preferably 1.3 to 2 times. . If the lip clearance is 1.0 times or more of the film thickness, it is easy to obtain a good surface film by film formation. Moreover, if the lip clearance is 5.0 times or less of the film thickness, the thickness accuracy of the film can be improved.

The die is one of the equipment that affects the thickness accuracy of the film, and a die that can control the thickness with high accuracy is preferable. Usually, the installation interval in the width direction of the die of the thickness adjusting equipment for adjusting the thickness of the film extruded from the die can be selected in the range of 40 mm to 50 mm. From the viewpoint that the thickness can be controlled in detail as the installation interval of the thickness adjustment equipment is narrower, the thickness adjustment equipment can be installed with the installation interval of preferably 35 mm or less, more preferably 25 mm or less. It is preferable to use a die of an adjustable type.
In order to further improve the uniformity of the film, it is preferable to adjust the conditions so that the temperature unevenness of the die and the flow rate unevenness in the width direction can be reduced as much as possible. It is also effective to reduce the thickness fluctuation in long-term continuous production by measuring the thickness of the downstream film, calculating the thickness deviation, and feeding back the result to the die thickness adjustment.

  For production of a film, a single-layer film forming apparatus with a low equipment cost is generally used. However, if necessary, a film having two or more types of structures can be manufactured using a multilayer film forming apparatus in which a functional layer is provided on the outer layer of the cylinder 44. When a multilayer film is formed using a multilayer film forming apparatus, it is generally preferable to laminate a functional layer having a thickness smaller than that of a resin film serving as a substrate as a surface layer on the surface of a thermoplastic resin film. However, the thickness ratio of each layer in the multilayer structure is not particularly limited.

  In the calculation formula of the supply part resin transport efficiency in the present disclosure, Q indicates the extrusion amount (kg / h) of the molten resin. The extrusion amount (kg / h) of the molten resin depends on the supply amount (kg / h) of the thermoplastic resin to the supply port of the extruder and is regarded as the extrusion amount (kg / h) from the extrusion port of the extruder. You can also. The extrusion amount Q of the molten resin depends on the cylinder capacity of the extruder, the type of the die, etc., but from the viewpoint of carrying out the melt extrusion with the resin transport efficiency of the supply part being 0.75 or more and 1.0 or less, the molten resin The extrusion rate is preferably 0.5 kg / h to 1800 kg / h, more preferably 1 kg / h to 900 kg / h.

<Cast>
Under the above conditions, the molten resin extruded from the die in the form of a film is cooled and solidified on a casting roll to obtain a thermoplastic resin film. In addition, before the molten resin comes into contact with the casting roll, by heating the melt-extruded film with a far infrared heater, a leveling effect is developed on the drum, and the surface of the melt-extruded film becomes more uniform. The film thickness distribution of the obtained film can be reduced, and the occurrence of die streaks can be suppressed.

  Adhesion between the cast roll and the melt-extruded sheet using a method such as electrostatic application, air knife method, air chamber method, vacuum nozzle method, touch roll method, etc., on the melt-extruded film on the casting roll Is preferable. Of these, the touch roll method described above is preferably used. 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 the casting roll to cool and shape the film surface, that is, smooth the film surface. It is a method of doing. The touch roll used in the present disclosure is preferably a roll having elasticity instead of a normal high-rigidity roll.

  The temperature of the touch roll exceeds Tg-10 ° C and is preferably Tg + 30 ° C or less, more preferably Tg-7 ° C or more and Tg + 20 ° C or less, and further preferably Tg-5 ° C or more and Tg + 10 ° C or less. When using a plurality of touch rolls, it is preferable to adjust any touch roll to the above temperature range. Further, the temperature of the casting roll is preferably adjusted to a temperature range similar to the temperature range of the touch roll described above.

  Specific examples of the touch roll include touch rolls described in JP-A Nos. 11-31263 and 11-235747, and the touch rolls described herein can be used in the manufacturing method of the present disclosure.

Moreover, it is more preferable that the discharged thermoplastic resin is gradually cooled by using a plurality of casting rolls. The number of casting rolls used for slow cooling is not particularly limited and is appropriately selected according to the purpose. For example, although the method of using three casting rolls for slow cooling of a thermoplastic resin is mentioned, it is not this limitation.
When a plurality of casting rolls are used for cooling the discharged thermoplastic resin, the touch roll is preferably arranged at a position where the first casting roll on the most upstream side (the one closer to the die) is touched.

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 all the casting rolls have a diameter within the above range.
When using a plurality of casting rolls, the distance between adjacent casting rolls is preferably 0.3 mm to 300 mm, more preferably 1 mm to 100 mm, and even more preferably 3 mm to 30 mm between the surfaces.
The line speed on 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 a thermoplastic resin and producing a film by the above process under the condition that the supply resin transport efficiency in the present disclosure is 0.75 or more, the longest diameter is 30 μm or more per 100 μm thickness. A cyclic olefin resin film having the number of foreign matters of 0.3 / cm ² or less and the number of foreign matters having a longest diameter of 5 μm or more and less than 30 μm is 100 / cm ² or less can be obtained. In addition, the number and magnitude | size of the foreign material contained in the film manufactured by the manufacturing method of this indication can be measured by the method in the Example mentioned later.

  Such a cyclic olefin resin film having a small number of foreign substances has high light transmittance and little light transmission unevenness, and therefore can be suitably used as an optical film for use in liquid crystal display devices and the like.

  The thickness of the unstretched film produced by the production method of the present disclosure may be determined according to the use, but when used as an optical film, 20 μm to 250 μm is preferable from the viewpoint of mechanical strength and light transmittance. Preferably they are 25 micrometers-200 micrometers, More preferably, they are 30 micrometers-180 micrometers.

<Winding>
After the cooled film (unstretched film) is peeled off from the casting roll, it is wound up through a nip roll (not shown).

  It is also preferable to trim both ends before winding. Trimming can be performed 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. Examples of the material of the cutter include carbon steel and stainless steel, and any material cutter may be used. In general, it is preferable to use a trimming cutter having a cemented carbide blade or a ceramic blade because the life of the cutter is long and generation of chips is suppressed. The portion cut off by trimming may be crushed and used again as a raw material.

  It is also preferable to perform a thicknessing process (knurling process) on one or both ends of the thermoplastic film. The height of the irregularities by the thicknessing process is preferably 1 μm to 200 μm, more preferably 10 μm to 150 μm, and still more preferably 20 μm to 100 μm. Thickening processing may be a shape that is convex on both sides or a shape that is convex on one side. The width of the thickening process is preferably 1 mm to 50 mm, more preferably 3 mm to 30 mm, and still more preferably 5 mm to 20 mm. Thickening processing can be performed at room temperature to 300 ° C.

  When winding, it is preferable to attach a lami film on at least one side from the viewpoint of preventing scratches. The thickness of the laminated film is preferably 5 μm to 200 μm, preferably 10 μm to 150 μm, and preferably 15 μm to 100 μm. The material of the laminated film is not particularly limited. Examples of the material for the laminated film include polyethylene, polyester, and polypropylene.

<Extension>
The formed film can be stretched according to the purpose.
When stretching, the formed film may be subjected to on-line stretching which is stretched as it is, or may be subjected to off-line stretching which is once wound and then fed out and stretched again.

The stretching direction may be transverse stretching that extends in the width direction of the formed film, longitudinal stretching that extends in the film forming direction of the formed film, or both transverse stretching and longitudinal stretching.
Furthermore, you may perform the below-mentioned relaxation process combining with extending | stretching. These can be implemented by, for example, the following combinations.

  The stretching is preferably performed by combining transverse stretching and longitudinal stretching. When performing transverse stretching and longitudinal stretching, biaxial simultaneous stretching may be performed, or sequential stretching may be performed. Among these, it is more preferable to perform longitudinal stretching first, and then perform sequential stretching for lateral stretching.

<Relaxation treatment>
The dimensional stability of the resin film can be improved by performing relaxation treatment after stretching of the obtained resin film. The relaxation treatment is preferably a heat relaxation treatment in which at least one of the longitudinal and transverse dimensions of the stretched film is relaxed by, for example, about 1% to 8%. Although the temperature in a heat relaxation process is suitably selected by the kind of thermoplastic resin used for a thermoplastic resin film, generally 130 to 240 degreeC is preferable.
The thermal relaxation is preferably performed after longitudinal stretching, either after lateral stretching, or both, and more preferably after lateral stretching. The relaxation treatment may be performed online continuously after the stretching of the thermoplastic resin film, or may be performed offline on the thermoplastic resin film wound up after the stretching.

According to the manufacturing method of the present disclosure, it is possible to manufacture a thermoplastic resin film having uniform physical properties with suppressed generation of heat-deteriorated foreign matter with high productivity. Especially, the manufacturing method of this indication is applied suitably for manufacture of the cyclic olefin resin film in which generation | occurrence | production suppression of a foreign material has big influence on quality.
Since the cyclic olefin resin film produced by the production method of the present disclosure is suppressed in generation of heat-degraded foreign matter and has good optical properties, the film alone may be used as an optical film. Further, it may be used in combination with a polarizing plate, and may be used by providing a functional layer such as a liquid crystal layer, a layer having a controlled refractive index (low reflection layer), a hard coat layer, and the obtained cyclic olefin resin. The application range of film is wide.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples unless it exceeds the gist thereof. Unless otherwise specified, “part” is based on mass.

  In Examples and Comparative Examples, resin films were basically produced by the following procedure. However, in each example, the screw flight interval W of the screw, the supply portion groove depth Hf, the cylinder inner diameter D of the extruder, the compression ratio, and the Q / N are changed as shown in Table 1 to supply the supply portion resin. Adjusted efficiency.

-Film formation procedure-
The raw material resin pellets were pre-dried at 100 ° C. for 5 hours.
After the preliminary drying, the resin pellets were put into a hopper provided in the extruder and melted at 270 ° C. by the extruder. In addition, the said temperature is the temperature of the cylinder after a compression part.
The molten resin (melt) extruded from the extruder and transported to the gear pump through the pipe was further sent out from the gear pump and filtered through a leaf type disk filter having a filtration accuracy of 5 μm.

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

<Example 1 to Example 7>
Cyclic olefin resin (ARTON (registered trademark) manufactured by JSR Corporation, specific gravity ρ: 1.08 (g / cm ³ ), glass transition temperature Tg: 138 ° C.) is used as a raw material resin, compression ratio, supply section groove depth Adjust Hf, the cylinder inner diameter D or Q / N of the extruder as shown in Table 1 (change the temperature of the extruder supply section A) so that each has a predetermined supply section resin transport efficiency. The melt extrusion was carried out. In addition, the screw of an extruder is a full flight type and a screw flight angle is 17.7 degrees.

<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>
In Example 1, melt extrusion was performed in the same manner as in Example 1 except that the oxygen concentration at the supply port of the extruder, the charged resin temperature, the use of a vacuum hopper, the screw, or the screw temperature was changed. In addition, the screw flight angle in the double flight type supply unit in Example 1-a to Example 1-i is 17.7 °.

<Comparative Example 1-1>
Example 1 except that in Example 1-i, Q / N was changed to 0.56 by changing the cylinder temperature of the extruder supply part (C1), and the supply part resin transport efficiency was adjusted to 0.65. Melt extrusion was performed in the same manner as 1-i.

<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 3.1 and the supply part resin transport efficiency was adjusted to 1.16.

<Comparative Example 1-3>
In Comparative Example 1-1, melt extrusion was performed in the same manner as in Comparative Example 1-1 except that the oxygen concentration was changed to 8 ppm by continuously supplying nitrogen gas to the supply port.

<Comparative Example 6>
In Example 6, melt extrusion was carried out in the same manner as in Example 6 except that the Q / N was 1.76, the resin transport efficiency of the supply unit was 0.68, and the double flight type was used as the screw. .

[Evaluation]
<Evaluation of the number of foreign objects>
The number of foreign matters in the resin film (thickness: 100 μm) produced in each example was measured using a differential interference microscope (200 times) manufactured by Nikon Corporation in the range of 10 cm × 10 cm. In the measurement, the number of foreign matters having a maximum length of 30 μm or more and the number of foreign matters having a length of 5 μm or more and less than 30 μm were recorded.

<Evaluation of yellowness>
About the resin film (thickness: 100 micrometers) manufactured in each case, Lab was measured using the color difference meter (the Suga Test Instruments Co., Ltd. make, SM-T), and yellowness was evaluated by b value. It is evaluated that the smaller the value of b value, the lower the yellowness and the more colored the resin film is.

  Table 1 shows the melt extrusion conditions and evaluation results of the films produced in each example.

As shown in Table 1, in each Example in which melt extrusion was performed under the condition that the resin transport efficiency of the supply part satisfies 0.75 or more and 1.0 or less, the number of foreign matters having a longest diameter of 30 μm or more is 0.3 / cm ² or less, and the number of foreign matters than the longest diameter is 5μm or more 30μm was 100 / cm ² or less. Moreover, the cyclic polyolefin film with high light transmittance in which coloring (yellowishness) was also suppressed was obtained.

The disclosure of Japanese Patent Application No. 2006-011074 filed on January 22, 2016 is incorporated herein by reference.
All documents, patent applications, and technical standards mentioned in this specification are to the same extent as if each individual document, patent application, and technical standard were specifically and individually stated to be incorporated by reference, Incorporated herein by reference.

Claims (8)

A cylinder having a supply port to which raw material resin is supplied and an extrusion port through which molten resin in which the raw material resin is melted is extruded; a screw shaft and a flight spirally arranged around the screw shaft; And a screw that is calculated by the following formula using an extruder that has a supply unit, a compression unit, and a metering unit in order from the supply port side along the screw shaft in the cylinder. The raw resin is supplied and melted under a condition that the resin transport efficiency of the resin satisfies 0.75 ≦ supply resin transport efficiency ≦ 1.0, and the molten resin extruded from the extrusion port is formed into a film from a die. A method for producing a thermoplastic resin film comprising a step of melt extrusion.


W: Screw flight interval (mm) in the supply section
Hf: Groove depth in the supply section (mm)
D: Inner diameter of cylinder (mm)
Ψ: Screw flight angle (°) in the supply section
Q: Extrusion amount of molten resin (kg / h)
ρ: Specific gravity of raw resin (g / cm ³ )
N: Number of screw rotations per minute (rpm)
Compression ratio: Volume per pitch of screw flights in the supply section / Volume per pitch of screw flights in the measuring section   The method for producing a thermoplastic resin film according to claim 1, wherein an oxygen concentration at the supply port is 0.1% or less.   The temperature of the said raw material resin supplied in the said cylinder from the said supply port is Tg-90 degreeC or more and Tg + 10 degrees C or less when the glass transition temperature of the said raw material resin is set to Tg degreeC. The manufacturing method of the thermoplastic resin film of description.   The method for producing a thermoplastic resin film according to any one of claims 1 to 3, wherein the raw material resin is supplied into the cylinder from the supply port through a vacuum hopper.   The said screw is a double flight screw, The manufacturing method of the thermoplastic resin film of any one of Claims 1-4.   The temperature of the said screw in the said supply part is controlled to Tg-80 degreeC or more and TgC or less in any one of Claims 1-5 when the glass transition temperature of the said raw material resin is TgC. The manufacturing method of the thermoplastic resin film of description.   The method for producing a thermoplastic resin film according to any one of claims 1 to 6, wherein the raw resin is a cyclic olefin resin. The thickness per 100 [mu] m, the number of foreign matter longest diameter is more than 30μm is 0.3 / cm ² or less, and a cyclic olefin resin film number of foreign matters of less than longest diameter 5μm or 30μm is 100 / cm ² or less .