JP3042021B2 - Amorphous polyolefin film - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to amorphous polyolefin films and sheets, and more particularly to mechanical properties,
The present invention relates to an amorphous polyolefin film and sheet having excellent optical properties.

[0002]

2. Description of the Related Art Conventionally, polymers represented by an amorphous polyolefin such as a norbornene-based polymer and a ring-opened polymer of dicyclopentadiene have very excellent transparency and a small water absorption, and therefore, for example, Japanese Patent Application Laid-Open No. 218721,
For example, Japanese Patent Application Laid-Open No. 63-234201 proposes use for optical applications.

[0003]

However, in order to use the amorphous polyolefin as a film for optical applications,
It is necessary to form a film having a very smooth surface and no defects. However, a film having a smooth surface generally has poor slippage and is easily scratched during film production, processing into an applied product, and during actual use.In particular, in optical applications, which are the main applications of the film, scratches on the film surface are difficult. Deterioration of surface quality is a big problem.

[0004] To improve the slippage of the film, a method of forming fine projections on the film surface with particles, such as adding inorganic fine particles or organic fine particles to a polymer, or a stretching operation during the production of the film, may be used. The method of forming fine irregularities on the surface is adopted, but in any case, the method of roughening the film surface deteriorates the transparency of the film, so it must be suitable for optical use Under such circumstances, there has been a demand for a method for improving the slipperiness of a film without deteriorating optical characteristics.

On the other hand, in order to use the above-mentioned amorphous polyolefin film for optical applications, it is necessary to maintain the optical isotropy without orienting the polymer in the film as much as possible. Therefore, the method for producing a film employs a step of extruding only, which does not include a stretching operation. When a stretching operation is performed, it is inevitable that some orientation occurs even in an amorphous polymer, and an increase in optical anisotropy is observed in the form of an increase in birefringence.

[0006] In an unstretched film that has not been subjected to this stretching operation, the slipperiness of the film is further reduced as compared with a stretched film. This is because the fine particles do not form projections on the film surface as in the case where the stretching operation is performed even if the fine particles are added as slip improvement. Further, the amorphous polyolefin is a polymer having a molecular weight such that practically sufficient mechanical strength can be realized, the melt viscosity is large, and the extrusion molding conditions may be extremely narrow in order to maintain the amorphous state. However, this is a constraint on the film surface formation.

An object of the present invention is to provide an amorphous polyolefin film having good optical properties and good handleability, with the object of improving the problem relating to the slipperiness of the amorphous polyolefin.

[0008]

The present invention relates to an amorphous polyolefin film comprising an amorphous polyolefin polymer and having a surface resistance of 1.0 × 10 ¹¹ Ω or less.

An amorphous polyolefin polymer is generally a polymer whose melting point is hardly observed by heat measurement. A typical example of the amorphous polyolefin in the present invention is hydrogen of a ring-opened polymer of dicyclopentadiene. Hydride of a copolymer of dicyclopentadiene and ethylene and a norbornene-based polymer, having a glass transition point of 100 ° C. or higher, preferably 130 ° C. or higher, and a water absorption of 0.1 or more. % Is preferred.

The hydride of the ring-opening polymer of dicyclopentadiene is a conventionally known substance, for example, Japanese Patent Publication No. 58-43.
No. 412 and JP-A-63-218727. Copolymers of dicyclopentadiene and ethylene are known in JP-A-63-314220 and the like, and norbornene-based polymers are described in US Pat. No. 2,883,372.
As disclosed in JP-B-46-14910, JP-A-1-149938, etc., a polymer obtained by obtaining a polycyclic norbornene-based compound having four or more rings from a mixture of dicyclopentadiene and genophile Etc. are known. Of course, the dicyclopentadiene includes an alkyl-substituted product such as a methyl- or ethyl-substituted product thereof, an endo isomer, a oxo isomer or a mixture thereof.

The glass transition point of these amorphous polyolefin polymers is as high as 100 ° C., preferably as high as 130 ° C. or more, because the physical properties of the film do not change over time.

The amorphous polyolefin film of the present invention has a surface resistance of 1.0 × 10 ¹¹ Ω or less, preferably 1.0 × 10 ¹¹ Ω or less.
0 ¹⁰ Ω or less. As described above, the amorphous polyolefin film has a problem which is considered to be caused by the slipperiness of the surface in handling. However, even if the surface cannot be formed as in a general biaxially stretched film, usually 1.0 × 10 ¹⁶ ~ 1.0
A film surface resistance of about × 10 ¹⁷ Ω
It was found that when the resistance was set to ¹¹ Ω or less, scratches and the like in the actual manufacturing process and processing process were significantly reduced. The reason for this is not clear, but it is thought that the reduced surface resistance changes the charged state of the film as it travels in various devices from the conventional state, and that the film is less likely to be charged with static electricity and less likely to wrinkle on the film. Can be Further, the amorphous polyolefin polymer of the present invention is excellent in that, for example, the moisture absorption rate is small as compared with a polyester-based polymer and various physical properties are stable against changes in humidity environment. It seems that there is a problem peculiar to the polymer that the toner is easily charged with static electricity.

As a method of reducing the surface resistance to 1.0 × 10 ¹¹ Ω or less, there are a method of kneading various antistatic agents into the amorphous polyolefin polymer of the present invention, and a method of thinly coating the film surface. Examples of the antistatic agent include dodecylbenzenesulfonate, bis [octylpolyoxyethylene] phosphate soda, phosphonium dodecylbenzenesulfonate, alkylsulfonate, phosphonium alkylsulfonate, polyethylene glycol, styrenesulfonic acid and salts thereof. Constituent vinyl resins are exemplified, but not particularly limited thereto.

When the antistatic agent is kneaded into the polymer, there are a method of kneading the entire film and a method of laminating the polymer in which the antistatic agent is kneaded on the surface layer, but from the viewpoint of the transparency of the film. Lamination of an antistatic layer is preferred. The addition amount of the antistatic agent is preferably 5% or less based on the weight of the polymer in view of the transparency of the film and its effect.

The molecular weight of the amorphous polyolefin polymer of the present invention is 30,000 or more and less than 70,000, preferably 35,000 or more and less than 60,000 in number average molecular weight. If the molecular weight is too low, it is difficult to maintain the mechanical strength of the film as a whole, especially impact strength. If the molecular weight is too high, the melt viscosity becomes extremely high and molding becomes difficult, which is not preferable. From the aspect of kneading the antistatic agent, the kneading antistatic agent with a low molecular weight easily bleeds out to the film surface over time or under a high temperature environment. It is not preferable in that it is difficult.

The birefringence of the amorphous polyolefin film of the present invention is preferably 0.005 or less, more preferably 0.001 or less. When the birefringence is large, when the film of the present invention is used, for example, as a protective film for a liquid crystal display panel, it causes color spots.

The surface roughness of the amorphous polyolefin film of the present invention is required to be preferably 0.1 μm or less, more preferably 0.05 μm or less from the application of the film. The haze value of the film is preferably 1 μm or less. .5%
Or less, more preferably 1.0% or less. They are,
Depends on the fine particles added to the film and the film formation method,
It is important to satisfy the above-mentioned characteristics at the same time, and by setting the surface resistance to a specific range as in the present invention, it is possible to avoid the deterioration in handling properties while having such characteristics.

In the polyolefin film of the present invention, any known additives such as a coloring inhibitor, an antioxidant, a heat stabilizer, a crystal nucleating agent, an adhesion improver, a slipping agent, an antiblocking agent, a weathering agent, Obviously, a foaming agent, a clarifying agent, a viscosity modifier and the like may be contained.

Next, a method for producing the film of the present invention will be described, but the present invention is not limited thereto.

The amorphous polyolefin polymer is melted after the content of ultra-low molecular volatiles having a molecular weight of less than 100, such as water, gas, melt, volatiles and decomposition products, is preferably 0.05% by weight or less, and then melted. The cast sheet is obtained by discharging the molten sheet and solidifying it in close contact with the cooling drum. When the antistatic agent is kneaded into the polymer, the antistatic agent is not particularly limited as long as it is added by the time the polymer is melted by an extruder. When the antistatic agent layer is laminated as described above, the molten sheet is discharged from the die after laminating a polymer containing the antistatic agent and a polymer not containing the antistatic agent by a known method such as using a composite tube. As the casting method, a nip roll method, a calendar method, an electrostatic application contact method, an air knife method, an air camber method, and the like can be used. In the present invention, the nip roll method and the calendar method are preferable. The drum is made of chrome plating or stainless steel with a surface roughness Rmax
It is preferable to use a surface drum of 0.2 μm or less. The surface temperature of the drum depends on the type of the amorphous polyolefin polymer, but is preferably around the glass transition temperature of the polymer.
Those having a temperature of from 05 to 165 ° C are often used. Further, it is preferable that the draft ratio is as small as 20 or less because the film becomes optically isotropic.

If necessary, heat treatment or stretching may be added, and coextrusion with another polymer, lamination, coating, or the like may be added.

When a method of applying an antistatic agent is employed, this can be performed by a known coating method.

[0023]

[Evaluation method of physical properties] (1) Surface resistance Main electrode (50mmφ), guard electrode (inner diameter 70mmφ, outer diameter 80mmφ) concentric with the main electrode and counter electrode (80mφ)
mφ), the resistance was determined from the value of the current flowing from the main electrode to the guard electrode when a voltage of 1 kV was applied, and this was multiplied by 60π to obtain the surface resistance.

(2) Number Average Molecular Weight The number average molecular weight was measured by gel permeation chromatography using toluene as a solvent.

(3) Birefringence The birefringence in the film plane was measured using sodium D line (589
nm) as a light source and placed on a polarizing microscope equipped with orthogonal Nicols so that the sample film surface is perpendicular to the optical axis, and the optical path difference に よ っ て caused by the birefringence of the sample is obtained from the compensation value of the compensator. Birefringence. Here, d is the thickness of the sample film.

(4) Average surface roughness (Ra) A stylus type surface roughness meter HOMM specified in DIN4768
Expressed as the center line average roughness at a cutoff of 0.25 mm, as measured by EL TESTER10.

(5) Haze Total haze was measured according to the method of JIS K6782.

[0028]

The present invention will be described below by way of examples.

Examples 1 and 2, Comparative Example 1 71.1 mol% of ethylene, DMOB (4.9, 5.8-
Dimethano-3a, 4,4a, 5,8,8a, 9,9a-
Octahydro-1H-benzoindene: I) 22.8 mol%, DMOF (1.4,5.8-dimethano-1,4,4)
4a, 4b, 5,8,8a, 9a-octahydro-9H
-Fluorene) was hydrogenated to obtain an amorphous polyolefin polymer having a number average molecular weight of 53,000.

These polymers were placed in a hot air oven at 10
After drying at 0 ° C. for 12 hours, the mixture was melted in an extruder, compounded, extruded from a T-type die, adhered to a 100 ° C. drum with a nip roll, and cooled to obtain an amorphous polyolefin film having a thickness of about 400 μm. . At this time, the pressing force of the nip roll was 10 kg / cm in linear pressure.

In Examples 1 and 2, sodium dodecylbenzenesulfonate and sodium alkylsulfonate (carbon number: 11) were formed before being formed into films.
Was added to the polymer. In Comparative Example 1, no antistatic agent was added. Table 1 shows the characteristic values. The obtained film was slit into an edge portion, wound up in a roll shape, and then coated with an adhesive using a general coater in order to evaluate it as a protective film for a polarizing plate. Example 1
In the films of Nos. 2 and 3, the processed film had no defects on the surface, but in Comparative Example 1, scratches, wrinkles and the like were generated. In addition, the roll wound after film formation was cut open, the two overlapping films were kept as they were, and the coefficient of friction was measured. Turned out to be in a bad state.

[0032]

[Table 1]

[0033]

According to the present invention, by setting the surface resistance of a film made of an amorphous polyolefin polymer to a specific range, an amorphous polyolefin film having excellent handleability such as slip properties while maintaining good optical properties can be obtained. Was done.

Therefore, the amorphous polyolefin film of the present invention is suitably used as a protective film for compact discs, video discs, optical cards, polarizing films and the like.

Continuation of the front page (56) References JP-A-4-283245 (JP, A) JP-A-4-292633 (JP, A) JP-A-4-266950 (JP, A) JP-A-4-272937 (JP) , A) (58) Field surveyed (Int. Cl. ⁷ , DB name) C08J 5/00-5/24

Claims (4)

(57) [Claims] 1. An amorphous polyolefin film comprising an amorphous polyolefin polymer and having a surface resistance of 1.0 × 10 ¹¹ Ω or less. 2. The amorphous polyolefin film according to claim 1, wherein the number average molecular weight of the amorphous polyolefin polymer is from 30,000 to less than 70,000. 3. An amorphous polyolefin polymer comprising a hydride of a ring-opening polymer of dicyclopentadiene, a hydride of a copolymer of dicyclopentadiene and ethylene, and a copolymer of ethylene with a reaction product of dicyclopentadiene and ethylene. The amorphous polyolefin film according to claim 1 or 2, comprising at least one selected from a hydride of a polymer and a norbornene-based polymer. 4. An average surface roughness (Ra) of 0.1 μm or less, a film haze value of 1.5% or less, and a birefringence of 0.0
The amorphous polyolefin film according to any one of claims 1 to 3, wherein the thickness is not more than 05.