JP2002113767A - Method for producing norbornene resin film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a norbornene resin film in which spot-shaped defects are reduced remarkably by melt extrusion molding. SOLUTION: The norbornene resin film is produced by melt extrusion molding in which the average retention time, after the passage of a filter to the outlet of a mold of the resin, is 30 min or below.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a norbornene resin film by melt extrusion. The film produced by the present invention is preferably used as an optical film.

[0002]

2. Description of the Related Art Norbornene resins have the following advantages over other resins. Therefore, it is suitable as a resin raw material for optical films. (1) High heat resistance. (2) High transparency. (3) No optical rotation. (4) Low intrinsic birefringence. (5) The photoelastic coefficient is small.

However, extrusion molding of norbornene resins has been considered difficult due to poor thermal stability during melt extrusion molding. Extrusion of precision products such as optical films is particularly difficult.

A technique for improving this is disclosed in Japanese Patent No. 297727.
No. 4 (Patent gazette publication date: January 1, 1999)
January 15). According to this technique, by using a norbornene-based resin having a high number average molecular weight and a wide molecular weight distribution, a flat molded article having no residual stress can be manufactured even by melt extrusion molding.

[0005]

In general, a norbornene-based resin can be used in the air at about 260 even when an antioxidant is added.
Thermal decomposition starts at ℃. On the other hand, the melt extrusion molding temperature of the norbornene-based resin is a high temperature near 300 ° C.

Accordingly, in melt extrusion molding of norbornene-based resin, a gel-like substance is generated by thermal decomposition at a high molding temperature, so that a point defect is easily generated in a molded product.

On the other hand, norbornene-based resin films used for optical applications are required to be free from point defects. Therefore, it is very difficult to produce a norbornene resin film for optics by melt extrusion.

[0008] Usually, in melt extrusion molding, a filtration device is used to reduce point defects. By the filtration device, gel-like substances and foreign substances in the resin generated by thermal decomposition are removed or pulverized. However, since the norbornene-based resin has very poor thermal stability, a specific problem that does not occur with other resins occurs even after passing through a filter in a filtration device. That is, since the inside of the extrusion mold is at a high temperature, even after passing through the filter, a new gel-like substance is generated by thermal decomposition, or the pulverized gel-like substance is again aggregated or grows. These are inherent causes of point defects in the norbornene-based resin film.

In view of the above-mentioned problems, the present inventor has found a manufacturing method capable of solving the above-mentioned inherent cause by intensively studying conditions for melt-extrusion molding of norbornene-based resins.

An object of the present invention is to provide a method for producing a norbornene-based resin film having remarkably few point defects by melt extrusion molding.

[0011]

The present invention is as follows. 1. A method for producing a norbornene-based resin film by melt extrusion molding satisfying the following condition (1). (1) The average residence time of the norbornene resin from the filter to the mold outlet is 30 minutes or less.

2. A method for producing an optical norbornene-based resin film by melt extrusion molding satisfying the following condition (1). (1) The average residence time of the norbornene resin from the filter to the mold outlet is 30 minutes or less.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.

"Norbornene-based resin used in the present invention" A conventionally known thermoplastic saturated norbornene-based resin can be used. The thermoplastic saturated norbornene resin is a resin having a norbornane skeleton in its polymerized unit.
The norbornane skeleton may have a substituent such as an alkyl group, a carboxyl group, or a phenyl group.

Known resins are disclosed in JP-A-1-240517, JP-A-62-252406, and JP-A-62-25.
2407, Japanese Patent Application Laid-Open No. 2-133413, Japanese Patent Application Laid-Open
It is described in JP-A-3-145324, JP-A-63-264626, JP-A-57-8815, and the like.

For example, there are the following resins. A hydrogenated product of a ring-opening polymer of a norbornene-based monomer, a hydrogenated product of a copolymer of two or more norbornene-based monomers, a norbornene-based monomer and an olefin-based monomer (ethylene, α
Hydrogenated product of a copolymer of a norbornene-based monomer and a cyclic olefin-based monomer (cyclopentene, cyclooctene, 5,6-dihydrodicyclopentadiene, etc.); Denatured product.

Examples of the monomers used for the thermoplastic saturated norbornene resin are as follows. Norbornene, 5-methyl-2-norbornene, 5-ethyl-2-norbornene, 5-butyl-2-norbornene, 5-ethylidene-2-norbornene, 5-methoxycarbonyl-2-norbornene, 5,5-dimethyl-2
-Norbornene, 5-cyano-2-norbornene, 5-
Methyl-5-methoxycarbonyl-2-norbornene,
5-phenyl-2-norbornene, 5-phenyl-5
Methyl-2-norbornene, ethylene-tetracyclododecene copolymer, 6-methyl-1,4: 5,8-dimetano-1,4,4a, 5,6,7,8,8a-octahydronaphthalene, 6-ethyl-1,4: 5,8-dimetano-1,4,4a, 5,6,7,8,8a-octahydronaphthalene, 6-ethyl-1,4: 5,8-ethylidene-1, 4,4a, 5,6,7,8,8a-octahydronaphthalene, 6-chloro-1,4: 5,8-dimethano-
1,4,4a, 5,6,7,8,8a-octahydronaphthalene, 6-cyano-1,4: 5,8-dimethano-
1,4,4a, 5,6,7,8,8a-octahydronaphthalene, 6-pyridyl-1,4,5,8-dimethano-
1,4,4a, 5,6,7,8,8a-octahydronaphthalene, 6-methoxycarbonyl-1,4,5,8-
Dimethano-1,4,4a, 5,6,7,8,8a-octahydronaphthalene, 1,4-dimethano-1,4,4
a, 4b, 5,8,8a, 9a-octahydrofluorene, 5,8-methano-1,2,3,4,4a, 5,8,
8a-octahydro-2,3-cyclopentadienonaphthalene, 4,9: 5,8-dimethano-3a, 4,4a,
5,8,8a, 9,9a-octahydro-1H-benzoindene, 4,11: 5,10: 6,9-trimethano-
3a, 4,4a, 5,5a, 6,9,9a, 10,10
a, 11,11a-Dodecahydro-1H-cyclopentaanthracene, 8-carboxymethyltetracyclo
[4,4,0,1 ^2,5, 1 ^7,10] -3-dodecene, 8-carboxyethyl tetracyclo [4,4,0,1 ^2,5, 1
^7,10] -3-dodecene, 8-methyl-8-carboxymethyl tetracyclo [4,4,0,1 ^2,5, 1 ^7,10] -3-dodecene.

A known method can be used for the polymerization of the norbornene-based monomer. Norbornene monomers are
If necessary, it may be copolymerized with another monomer. The resulting polymer may be hydrogenated by hydrogenation.
The polymer or the hydrogenated polymer may be modified by a known method. Examples of the compounds used for the modification are as follows.
α, β-unsaturated carboxylic acids and derivatives thereof, styrene-based hydrocarbons, olefin-based unsaturated bonds, organosilicon compounds having a hydrolyzable group, and unsaturated epoxy monomers.

The polymerization is carried out using the following polymerization catalyst. Examples of the polymerization catalyst are as follows. Ir, Os, Ru trichloride hydrate, MoCl ₅ , W
_{C1 6, ReCl 5, (C} 2 H 5) 3 Al, (C 2 H 5) 3 Al
/ TiCl ₄ , (π-C ₄ H ₇ ) ₄ Mo / TiCl ₄ , (π
_{-C 4 H 7) 4 W /} TiCl 4, (π-C 3 H 5) 3 Cr / W
Cl ₆ .

Examples of commercially available thermoplastic saturated norbornene resins are as follows. Product names "ZEONOR", "ZEON" manufactured by Zeon Corporation
EX ”; product name“ ARTO ”manufactured by JSR Corporation
N "; trade name" OPTOREZ "manufactured by Hitachi Chemical Co., Ltd .;
"APEL" manufactured by Mitsui Chemicals, Inc.

In the present invention, the weight average molecular weight (Mw) of the norbornene resin is usually from 30,000 to 150,
000, preferably 40,000 to 110,000, more preferably 50,000 to 90,000. If the weight-average molecular weight is less than 30,000, sufficient film strength cannot be obtained, so that the film breaks or tears during molding. If the weight average molecular weight exceeds 150,000, it is necessary to increase the extrusion temperature due to the high melt viscosity, so that thermal decomposition of the resin is promoted.

The molecular weight distribution of the norbornene resin (Mw /
Mn) is preferably 1.5 to 6.0, more preferably 2.0
~ 4.0. If the molecular weight distribution is less than 1.5, the resin will have poor fluidity and cannot be extruded. If the molecular weight distribution exceeds 6.0, fumes of the resin occur at the mold outlet due to the large amount of low molecular weight components.

The weight average molecular weight (Mw) and number average molecular weight (Mn) were determined by high performance liquid chromatography analysis (GPC).
Method) and the value in terms of polystyrene. The molecular weight distribution (Mw / Mn) is a value obtained by dividing the weight average molecular weight by the number average molecular weight.

The melt flow rate of the norbornene resin is usually 4 to 200 g / 10 min, preferably 10 to 15 g.
0 g / 10 min, more preferably 20 to 120 g / 10 m
in. If the melt flow rate is less than 4 g / 10 min, the fluidity of the resin will be poor and the resin will be deteriorated during extrusion. Melt flow rate is 200g / 10m
When it exceeds in, the film strength becomes weak.

The melt flow rate is in accordance with JIS K721
0 (method A). Temperature 280 ℃, load 9
8N is shown.

In the present invention, a film is produced by melt extrusion of the above-mentioned norbornene resin. A known method is used for melt extrusion.

In the present invention, a filtration device is used. This is an apparatus for filtering the melted norbornene resin with a filter. The filtration device can be used in the present invention without any particular limitation as long as it is a device usually used for extrusion molding.

Examples of the filters used in the filtration device are as follows. Disc shape filter; Candle shape filter;
Leaf disk shape filter.

In particular, a leaf disk-shaped filter is preferable for the following reasons. (1) The filtration area can be increased. (2) Structural strength can be provided. (3) The location where the molten resin stays can be reduced.

Examples of the filter medium (media) constituting the filter are as follows. (1) A filter material in which a metal wire is woven (2) A filter material obtained by sintering metal fibers (3) A filter material obtained by sintering metal powder (4) A laminate of the above filter materials.

In particular, a filter medium obtained by sintering metal fibers is preferable in terms of filtration accuracy and filtration ability.

The porosity of the filter medium is usually 35 to 95%, preferably 50 to 95%, more preferably 60 to 80%. If the porosity is less than 35%, it will be difficult for the molten resin to pass through the filter medium, and filtration cannot be performed effectively. Porosity is 95
%, The strength of the filter medium is weakened, and the filter medium is easily broken.

The porosity indicates the percentage of the volume of the space excluding the materials such as metal fibers used from the total volume of the filter medium.

The material of the filter medium is not particularly limited. Stainless steel is preferred from the viewpoint of corrosion resistance and recycling. Particularly preferred are SUS316, 316L and 304.

The filtration accuracy of the filter medium is usually 100 μm or less,
Preferably it is 50 μm or less, more preferably 10 μm or less. The reason is that the size of the point defect which is a problem in the film is 100 μm or more, and when the quality is further required, it is 50 μm or more.

[0036] A plurality of filter media may be laminated. For example,
There are the following methods. In order to reinforce the strength of the filter medium, a woven wire mesh of several meshes may be laminated on the filter medium. (1) A method of installing a filter medium with a high filtration accuracy on the inlet side of the resin and installing a filter medium with a fine filtration accuracy on the outlet side of the resin. This method has an effect of roughly catching foreign matter in the first filter medium on the inlet side and preventing clogging of the filter medium on the outlet side. (2) A method of laminating a plurality of identical filter media. This method has the effect of improving the filtration accuracy.

The essential conditions of the production method of the present invention are as follows. (1) The average residence time of the norbornene resin from the filter to the mold outlet is 30 minutes or less. These conditions limit the residence time from the time the molten resin is filtered to the time the extrusion resin exits. This is the transit time for the molten resin to reach the extrusion die outlet after passing through the filter.

The average residence time (maximum passage time) is calculated from the total volume of the resin flow path from the passage through the filter to the exit of the mold and the extrusion amount.

Specifically, (total flow volume from the filter outlet to the extrusion die outlet)
÷ (discharge amount / resin specific gravity).

The average residence time must be less than 30 minutes. Preferably less than 10 minutes, more preferably 5 minutes
Minutes or less. If the average residence time exceeds 30 minutes, the effects of the present invention cannot be obtained, and point defects may occur in the produced film. This is because the gel substance is regenerated after filtration, or the small gel substance that has passed through the filter grows or aggregates.

The average thickness of the film produced by the present invention is preferably 10 to 500 μm, more preferably 2 to 500 μm.
It is 0 to 300 μm, most preferably 20 to 100 μm. If the thickness exceeds 500 μm, point defects inside the film are hardly recognized by inspection. In particular, a point-like defect due to a colorless and transparent foreign substance such as a gel-like substance is extremely hard to be visually recognized. Therefore, from the viewpoint of easiness of visual inspection after production, the utility of the present invention is high when producing a film having a thickness in the above range. On the other hand, even when the film is thick, the present invention is highly useful because it can produce a film with few point defects due to the difficulty of visual inspection of the point defects.

Since the film produced by the present invention has few point defects, it is suitably used as an optical film. For example, by stretching a film by a known method,
A stretched film of 0 to 300 μm can be prepared and used as an optically stretched film. Since the stretched film has a small thickness, a point defect is easily recognized. In particular, since an optical film requires a point defect inspection after production, from the viewpoint of easiness of inspection, the present invention is suitably used for producing a stretching film (raw material).

[0043]

Next, the present invention will be described in detail with reference to examples. The present invention is not limited to the following examples.

Example 1 Using a leaf disk-shaped filter, melt extrusion molding under the following conditions was carried out to obtain a width 430.
mm, and a film having a thickness of 50 μm was produced. <Conditions> Norbornene resin: Trade name "ZEONOR1600R"
(Manufactured by Nippon Zeon Co., Ltd.) Preliminary drying: 110 ° C. for 3 hours Extruder: φ50 mm, L / D = 28, single screw Extrusion temperature: 275-320 ° C. Filter: leaf disk Sintered fiber type Filtration accuracy: 10 μm T-die: 500 mm width, coat hanger type Discharge rate: 20 kg / hr Cooling roll temperature: 140 ° C. Average residence time: 3 minutes

Example 2 A film having a width of 430 mm and a thickness of 50 μm was produced under the same conditions as in Example 1 except for the following conditions. <Conditions> Discharge rate: 10 kg / hr Average residence time: 6 minutes

Example 3 A film having a width of 430 mm and a thickness of 50 μm was produced under the same conditions as in Example 1 except for the following conditions. The total volume of the flow channel is four times that of the first embodiment. <Conditions> Filter: Leaf disk Sintered fiber type Filtration accuracy: 5 μm Average residence time: 12 minutes

Comparative Example 1 A film having a width of 430 mm and a thickness of 50 μm was produced under the same conditions as in Example 1 except for the following conditions. Note that the total flow volume is 13 times that of the first embodiment. <Conditions> Average residence time: 39 minutes

"Evaluation" The films obtained in the Examples and Comparative Examples were visually inspected. 400mm width film center 1
Point defects existing in a range of 0 m ² were counted. Table 1 shows the average residence time and the point defects per unit area. The point defects of the films obtained by the production methods of Examples 1 to 3 are extremely small as compared with Comparative Examples.

[0049]

[Table 1]

[0050]

According to the present invention, a norbornene-based resin film having very few point-like defects can be produced by extrusion molding.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view schematically showing a filtering device accommodating a leaf disk-shaped filter.

Claims (2)

[Claims] 1. A method for producing a norbornene-based resin film by melt extrusion molding satisfying the following condition (1). (1) The average residence time of the norbornene resin from the filter to the mold outlet is 30 minutes or less. 2. The method according to claim 1, wherein the norbornene-based resin film is an optical film.