JPH08334618A - Phase difference film and its production and laminated polarizing plate - Google Patents

Abstract

PURPOSE: To obtain a phase difference film partially varying in phase differences and a process for producing the film with good efficiency. CONSTITUTION: The phase difference film 1 consists of a single layered continuous stretched film exhibiting the distribution characteristics 11, 12 of >=2 kinds of phase differences partially varying in the phase difference in accordance with the partial differences in the degree of molecule orientation. The process for producing the phase difference film comprises partially imparting the heat above the glass transition temp. or above on the stretched film or partially applying a medicinal liquid for dissolving or swelling the film on the film to partially lower the degree of orientation of the molecules, thereby partially varying the phase differences. The laminated polarizing plate consists of a laminate composed of the phase difference film and the polarizing plate. As a result, the phase difference film consisting of the single layered continuous stretched film distributed with the regions where the phase differences are varied by the differences in the degree of the molecule orientation in a pattern form is efficiently formed with >=2 kinds of the fine phase difference distribution patterns.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a retardation film which is partially different in retardation and is suitable as a polarization modulator such as an optical isolator, a method for producing the same, and a laminated polarizing plate using the film. .

[0002]

2. Description of the Related Art Conventionally, a uniaxial retardation film has been used as a polarization modulator such as an optical isolator such as a half-wave plate or a quarter-wave plate, or a retardation compensation plate for a liquid crystal cell such as STN type. There has been known a stretched film obtained by simply stretching with biaxial or the like. There is a strong demand for such a polarization modulator that can partially compensate the phase difference or partially compensate the phase difference.

However, there has been a problem that it is difficult to partially make the retardation different from the conventional mere stretched film, and it is not possible to obtain a material that can serve the above purpose. The target retardation film can be formed by a method of partially adhering another stretched film having a different retardation to the base film made of a stretched film, but in that case, it takes a lot of time and labor to form the retardation film. However, it becomes a film having a step, and the practicability between layers becomes poor, and it is also difficult to make the phase difference different from each other by a fine pattern, and it is difficult to obtain a practically practical retardation film. Therefore, it is not more practical to partially connect stretched films having different retardations to obtain the desired retardation film.

[0004]

An object of the present invention is to develop a practical retardation film in which retardations are partially different, and a method for efficiently producing such a film.

[0005]

DISCLOSURE OF THE INVENTION The present invention comprises a continuous stretched film of a single layer exhibiting two or more types of retardation distribution characteristics in which retardations are partially different based on partial differences in molecular orientation. Characterized in that the retardation film characterized in that, and the stretched film is partially imparted heat above the glass transition temperature to partially reduce the degree of orientation of the molecules and partially differ the retardation. A method for manufacturing the retardation film is provided.

Further, the present invention is characterized in that a stretched film is partially applied with a chemical solution capable of dissolving or swelling the stretched film to partially lower the degree of orientation of molecules and partially shift the retardation. The present invention also provides a method for producing the above retardation film, and a laminated polarizing plate comprising a laminate of the above retardation film and a polarizing plate.

[0007]

By making the molecular orientation degree of the stretched film partially different, the retardation can be made partially different based on the difference. In that case, according to the above method in which the degree of molecular orientation is partially reduced by heat or a drug, it is easy to make the phase difference different in a fine pattern.
A retardation distribution pattern of at least one kind can be efficiently formed, and the desired retardation film can be obtained as a continuous stretched film of a single layer without the need for laminating treatment or connecting treatment. Also, it is easy to control the phase difference to be made different.

[0008]

EXAMPLES The retardation film of the present invention comprises a single-layer continuous stretched film exhibiting two or more types of retardation distribution characteristics in which retardations are partially different based on partial differences in molecular orientation. An example thereof is shown in FIG. Reference numeral 1 is a retardation film, and 11 and 12 are regions in which the retardation is partially different based on the partial difference in the degree of molecular orientation. In addition, 2 is an adhesive layer provided as needed, and 3 is a separator.

The retardation film of the present invention can be produced by, for example, partially applying heat above the glass transition temperature to the stretched film to partially lower the degree of orientation of molecules and to cause partial difference in retardation. Alternatively, the stretched film can be partially applied with a chemical solution capable of dissolving or swelling the stretched film to partially reduce the degree of orientation of molecules and partially retard the phase difference.

The stretched film can be obtained, for example, by subjecting a polymer film to stretching treatment by an appropriate method such as uniaxial or biaxial. From the viewpoint of controlling the retardation, a stretched film excellent in uniformity of retardation can be preferably used because the molecules are oriented as uniformly as possible. Therefore, any conventional retardation film can be used. As the polymer film forming the stretched film, an appropriate film made of transparent plastic can be used and is not particularly limited.

Incidentally, examples of the polymer film include polycarbonate-based polymers, polyester-based polymers such as polyarylate and polyethylene terephthalate,
Polyimide-based polymer, polysulfone-based polymer, polyethersulfone-based polymer, polystyrene-based polymer, polyolefin-based polymer such as polyethylene and polypropylene, polyvinyl alcohol-based polymer, cellulose acetate-based polymer, polyvinyl chloride-based polymer , A film made of a thermoplastic polymer such as polymethylmethacrylate polymer. Further, a film made of a liquid crystal polymer can also be used.

The operation of lowering the degree of molecular orientation in the stretched film can be carried out by a method of applying heat above the glass transition temperature (heat distortion temperature) or a method of applying a chemical solution capable of dissolving or swelling. There is no particular limitation on the method of applying heat or the method of applying the chemical solution, such as a heating method via a heat source or a heat applying method via electric discharge, or an application method such as an organic solvent capable of dissolving or swelling the stretched film. It is possible to employ an appropriate method of, and it is also possible to use both methods of applying heat and applying the chemical solution.

A pattern consisting of regions where the phase difference has changed,
Particularly, from the viewpoint of efficiently forming a fine pattern, a method of applying heat or applying a chemical solution by an appropriate heating type or chemical solution ejecting printer such as a thermal transfer printer or an inkjet printer is preferable. Also, a desired pattern such as a fine pattern can be efficiently formed by a heating method using a laser beam, a press heating method such as a stamp method, or a method of applying a chemical by a mask method, a printing method, or the like.

The region where the retardation is changed may be a region having a desired pattern, or a region other than the desired pattern, that is, a region having the desired pattern remains due to the degree of molecular orientation in the original stretched film. However, a region other than the pattern may be a region having a reduced degree of molecular orientation. The latter operation of lowering the degree of molecular orientation can be performed by, for example, a method of masking a target pattern region with a resist or the like and treating with heat or a chemical solution.

The retardation film of the present invention has two or more types of retardation distribution characteristics in which the degree of molecular orientation is partially different and the retardation is partially different due to the difference. The distribution state of the retardation can be appropriately determined according to the purpose of use of the retardation film, and may be in any distribution state such as an identification mark shape, a stripe shape, a lattice shape or a checkered pattern distribution. .

In the above-mentioned distribution characteristics, two or more kinds of suitable numbers can be selected as a combination of regions having different phase differences. In the present invention, an arbitrary retardation state can be formed in the range of the original molecular orientation degree of the stretched film from the state in which the molecular orientation is substantially lost (molecular orientation degree 0).
Generally, the distribution characteristic is a combination of 20 or less types, particularly 10 or less types, and particularly 2 to 7 types of regions having different phase differences.

The formation of regions having different phase differences, that is, the control of the extent to which the degree of molecular orientation is lowered, is controlled by controlling the amount of heat by adjusting the heating temperature or the heating time, adjusting the solubility or swelling degree depending on the type of drug, and treating time. It can be performed by an appropriate method such as a method of controlling the degree of dissolution or swelling by adjusting the above.

The size of the unit area of the phase difference such as the size of each area having a different phase difference or the size of each area having the same phase difference can be appropriately determined according to the target pattern shape and the like. The size may be different, or the size may be different. In the present invention, a minute area of about 1/1000 to 1/100 mm ² can be easily formed through the various printers described above.

Since the retardation film of the present invention is composed of a continuous film of a single layer, it is advantageous to use it as a single layer film from the viewpoint of thinning, but two or more layers of the same or different retardation films. It can also be used as a laminate. By stacking by a method of changing the crossing state of the optical axes, the distribution state of the phase difference as a whole can be changed.

The thickness of the retardation film is appropriately determined based on the desired retardation value (product of refractive index difference of birefringence and thickness) and the like. In general, the thickness of the monolayer film is 500 μm or less, preferably 5 to 300 μm.

The retardation film of the present invention can be used for various purposes as a polarization modulator, etc., but may be used as it is in practical use, or may be used as a film or resin coat for the purpose of protecting the pattern of retardation. You may provide the surface protection layer which becomes. Further, as illustrated in FIG. 1, the adhesive layer 2 for the purpose of adhering to an adherend or the like may be attached in advance.

The adhesive layer can be provided on one side or both sides of the retardation film. For forming the adhesive layer, an appropriate adhesive substance such as a rubber-based adhesive, an acrylic-based adhesive, a silicone-based adhesive or a polyvinyl ether-based adhesive can be used. From the viewpoint of preventing changes in the phase difference pattern, those that do not require a high temperature process or long-time treatment at the time of curing or drying are preferable. The adhesive layer is preferably covered with a separator 3 for the purpose of preventing contamination and the like until it is put into practical use as illustrated in FIG.

Further, the retardation film of the present invention can be put to practical use as a laminated polarizing plate composed of a laminate with a polarizing plate. The laminated polarizing plate 5 is illustrated in FIG. 4 is a polarizing plate. By using a laminated polarizing plate, for example, a circularly polarized light portion due to a quarter wavelength difference and an elliptically polarized light portion due to other retardation can be mixed in a predetermined pattern depending on the phase difference pattern.

As the polarizing plate, an appropriate one can be used without any particular limitation. Generally, a film made of a hydrophilic polymer such as polyvinyl alcohol is treated with a dichroic dye such as iodine and stretched, or a plastic film such as polyvinyl chloride is oriented with polyene. And a polarizing film covered with a sealing film for protection.

Example 1 A polycarbonate film having a thickness of 60 μm was stretched 1.7 times at 155 ° C. and heated at 0.5 mm intervals through a 0.4 mj / dot thermal transfer printer to form a striped pattern. To give a retardation film. When the retardation value (Δnd) of this retardation film was examined, Δnd was 960 nm (non-heated part) and Δn
The portion having d of 630 nm (heated portion) had a stripe pattern formed at 0.5 mm intervals. The pattern state is shown in FIG.

Example 2 A polycarbonate film having a thickness of 60 μm and stretched 1.2 times at 157 ° C. was partially wiped with a cloth impregnated with toluene to swell, and then dried to obtain a phase difference. I got a film. When the retardation value (Δnd) of this retardation film was examined, Δnd was 430 nm
In the base area of (non-treatment part), treated with toluene △
The part where nd was 300 nm was mixed.

[0027]

According to the present invention, it is possible to obtain a retardation film comprising a continuous stretched film of a single layer in which the retardation is partially different due to the difference in the degree of molecular orientation and the retardation difference regions are distributed in a pattern. You can Further, according to the manufacturing method of the present invention, the phase difference can be easily made different with a fine pattern, two or more types of phase difference distribution patterns can be efficiently formed, and the control of the phase difference to be made different is also possible. It's easy.

[Brief description of drawings]

FIG. 1 is a sectional view of an example of a retardation film.

FIG. 2 is a sectional view of an example of a laminated polarizing plate.

FIG. 3 is a graph showing retardation in the retardation film of Example 1.

[Explanation of symbols]

 1: Retardation film 11, 12: Retardation difference area due to difference in molecular orientation degree 2: Adhesive layer 4: Polarizing plate 5: Laminated polarizing plate

Claims (6)

[Claims] 1. A retardation film comprising a single-layer continuous stretched film exhibiting two or more types of retardation distribution characteristics in which retardations are partially different based on partial differences in molecular orientation. . 2. The retardation film according to claim 1, which has a pattern based on a difference in retardation. 3. An adhesive layer on one side or both sides
Alternatively, the retardation film according to item 2. 4. The heat of the glass transition temperature or higher is partially applied to the stretched film to partially reduce the degree of orientation of molecules,
2. The phase difference is partially different from each other.
Or the method for producing the retardation film according to 2. 5. The stretched film is partially applied with a chemical solution capable of dissolving or swelling the stretched film to partially reduce the degree of orientation of molecules and partially differ the retardation. Item 3. A method for producing a retardation film according to item 1 or 2. 6. A laminated polarizing plate comprising a laminated body of the retardation film according to claim 1 and a polarizing plate.