JPH07104448B2 - Polarizing film using perylene dye - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a polarizing film using a specific perylene dye.

Background of the Invention The most commonly used polarizing film today uses a polyvinyl alcohol-based resin as a film substrate, on which an iodine compound and / or an acid dye or a direct dye having a selected structure is used. It is a color material to which a polarizing property is imparted. Although this type of polarizing film has excellent polarizing ability, it has insufficient durability and is usually durable by covering both sides of the film with a film-like material (protective film) that has moisture resistance and at least one side is transparent. Sex is retained. That is, a means for obtaining practical durability by protecting the defects of the internal polarizing film (layer), which is inherently extremely poor in durability, with the protective films (layers) on both sides is taken.

In recent years, due to the expansion of the use of liquid crystal display devices for in-vehicle use, computers, industrial equipment, etc., the durability of the polarizing film used as one element has been improved, especially with respect to moisture resistance, weather resistance and heat resistance. There is a strong demand for improvement. 1 for this
As one of the improving means, a polarizing film using a hydrophobic resin as a substrate has been proposed, and as a known technique, JP-A-57-
No. 84409 and Nos. 58-68008 and 60-
No. 125804 is exemplified. However, although such a polarizing film is sufficiently durable, it is not necessarily satisfactory in terms of polarization.

[Problems to be Solved by the Invention] Although this type of polarizing film may have polarizing performance comparable to that of a conventional PVA type polarizing film immediately after production, When it was used, especially when it was used for a long time in a heated state, the degree of polarization was remarkably lowered, and there was a practical problem. The main reason for this is that the dye used as a polarizer is a dichroic dye mainly developed for liquid crystals, and is generally structurally selected so as to be dissolved in a liquid crystal substance at a concentration as high as possible. . However, it is considered that the molecule of such a dye easily moves in a hydrophobic resin film substrate such as polyethylene terephthalate, especially due to thermal motion during heating, and disturbs its own arrangement. In addition, in the manufacturing process of this type of polarizing film, a means for preventing shrinkage of the film and obtaining dimensional stability is usually taken by a heat treatment process subsequent to the stretching process. When a dye having extremely high solubility in a hydrophobic base resin such as a dichroic dye for liquid crystal is used, the degree of polarization may be considerably high immediately after the stretching step, but the heat treatment step After passing through, there was a disadvantage that the degree of polarization was significantly reduced. Therefore, in this type of polarizing film, if a polarizing film having a high degree of polarization is to be obtained, it is not possible to perform a sufficient heat treatment for heat fixation after the stretching treatment, so that sufficient dimensional stability and stability can be obtained. If it is not possible to obtain a product having the above-mentioned degree of polarization, and on the contrary to obtain a product having dimensional stability and a stable degree of polarization, it is necessary to carry out a sufficient heat treatment after the stretching treatment, so that it has a high degree of polarization. I didn't get anything.

[Object of the Invention] An object of the present invention is to provide a polarizing film in which an aromatic polyester-based resin is used as a film substrate and a perylene-based dye as a red component is mixed therein.

[Means for Solving Problems] As a result of various investigations for solving the above problems, in a polarizing film having an aromatic polyester resin as a film substrate, a dye used for solving the above problems is required. The most important property is that they have a high dichroism, and they have found that they must have some kind of pigment aptitude, and have arrived at the present invention.

That is, the present invention that achieves the above-mentioned object is achieved by adding the compound of the general formula (I) to an aromatic polyester resin. [In the formula (I), R ¹ and R ² may be the same or different,
Each is a hydrogen atom, a halogen atom, a methyl group or a methoxy group, R ³ and R ³ ′ may be the same or different, and each of formulas (a) to (d) —CONH · R ⁴ (a) —CO ₂ · R ⁴ (b) (In the formulas (a) and (b), R ⁴ is a hydrogen atom, an alkyl group, a cycloalkyl group or an aryl group, and R ⁵ is a hydrogen atom, an alkyl group, an alkoxy group, a cycloalkyl group, an aryl group or a halogen atom. Y is an oxygen atom or a sulfur atom, m is an integer of 1 or 2, and when m is 2, they may form a ring together with the carbon atom to which they are attached, n and n ′ is 2. ] It is the polarizing film characterized by orienting and containing the perylene type | system | group dye represented by these.

The perylene dye represented by the general formula (I) is used for coloring an aromatic polyester resin to obtain a polarizing film of the present invention, and the polarizing film of the present invention has particularly good durability and polarizing performance. Is.

Further, among the dyes represented by the general formula (I), n and n ′ =
The dye of No. 2 is particularly suitable as the dye for polarizing film.

The present invention will be described in detail below.

Specific examples of the substituent represented by R ⁴ in the general formula (I) include H; -CH ₃ , -C ₂ H ₅ ,-(CH ₂ ) ₂ CH ₃ , -CH (CH ₃ )
₂ ,-(CH ₂ ) ₃ CH ₃ , -CH ₂ CH (CH ₃ ) ₂ , -CH (CH ₃ ) C ₂ H ₅ ,-
_{C (CH 3) 3, -} (CH 2) 4 CH 3, - (CH 2) 5 CH 3, - (CH 2) 6 C
_{H 3, - (CH 2)} 7 CH 3, - (CH 2) 8 CH 3 such as an alkyl group, -C _{2
H 4 OCH 3, -C 2 H} 4 OC 2 H 5, -C 2 H 4 O (CH 2) 2 CH 3, -C 2 H 4 O (C
H ₂ ) ₃ CH _{3 and} other alkoxyalkyl groups; And other aryl groups.

Specific examples of the substituent represented by Etc. can be mentioned.

Specific examples of the substituent represented by Etc. can be mentioned.

The dye of the general formula (I) has the formula (II) With perylene tetracarboxylic acid anhydride represented by the general formula (III) [In the formula (III), R ¹ , R ² , R ³ and n are the same as defined above. ] A method of boiling aromatic amines represented by the formula (1) in an inert solvent such as nitrobenzene, or a general formula (III) equimolar to the perylene tetracarboxylic acid anhydride represented by the formula (I). The aromatic amines represented are boiled in an inert solvent such as nitrobenzene and then further represented by the general formula (III) ′ [In the formula (III) ′, R ¹ , R ² , R ³ and n ′ have the same meaning as defined above. ] Aromatic amines represented by
It can be easily synthesized by a method such as boiling.

These perylene dyes of the present invention have a dichroic property suitable for a polarizing film, and at the same time, they have physical properties substantially insoluble in water, organic solvents and liquid crystals. Here, `` substantially insoluble '' means that at room temperature, that is, at about 25 ° C., the dichroic dye is 0.
It has a solubility of not more than 05% by weight, preferably not more than 0.01% by weight. Further, here, the organic solvent is acetone, methyl alcohol, ethyl alcohol, chloroform, benzene, toluene, xylene, nitrobenzene,
It is an easily available inert organic solvent having a boiling point of 250 ° C. or less, such as chlorobenzene, 0-dichlorobenzene, N, N-dimethylformamide, N-methyl-2-pyrrolidone and ethyl acetate. Further, the liquid crystal is a liquid crystal having a nematic phase or a smectic layer that has fluidity at room temperature, that is, a schiff base liquid crystal, a biphenyl liquid crystal, a phenylcyclohexane liquid crystal, an ester liquid crystal, a pyrimidine liquid crystal, and a mixture thereof. .

As described above, it is an important characteristic that the dichroic dye used in the present invention is substantially insoluble in the organic solvent and the liquid crystal as described above. This shows that the pigment has properness. Such a dye is suitable for a polarizing film having an aromatic polyester resin as a base material, and it is possible to select a dye for such a polarizing film from dichroism by dissolving in a liquid crystal,
It means that it is impossible by judging whether or not the dichroism is excellent. That is, the means for determining whether or not the dichroic dye of the present invention has excellent dichroism suitable for a polarizing film was not always clear.

As a simple and effective means for evaluating dichroism of such a dye, the present inventors measured the dichroism of the dye in polyethylene terephthalate, which is a typical example of an aromatic polyester-based resin, to obtain the polarized light of the present invention. This was used as a method for judging the suitability of the dye applied to the film. The method has an intrinsic viscosity of 0.6 to 0.7.
A film obtained by uniformly mixing an appropriate amount of a dye with a pellet of polyethylene terephthalate having 5 and performing melt film formation, and then stretching the film at least 3 times in the longitudinal direction in the longitudinal direction at a temperature near or above the glass transition temperature. As a sample, it is a method of measuring the dichroic ratio of the dye at the maximum absorption wavelength in the visible light range.

The perylene-based dye used in the present invention has a dichroic ratio of 7 or more measured by the above method, and is suitable as a dye for a polarizing film having an aromatic polyester-based resin such as polyethylene terephthalate as a film base material. .

By the methods and criteria as described above, it is possible to easily select a dye which has conventionally been difficult to determine whether or not it has sufficiently high dichroism for a polarizing film.

In the production of the polarizing film of the present invention, the dye used can be used as it is crude, but it is preferably purified by recrystallization or other purification means, and pulverized to several microns or less. It is preferable to use.

The polarizing film of the present invention contains at least one of the above-mentioned dyes, and several types can be selected and mixed and used in order to obtain a desired hue, and particularly to obtain a polarizing film having a neutral gray color. Further, a dye having a dichroic property other than that of the present invention, a dye having no dichroic property, an additive such as an ultraviolet absorber, or another substance may be contained depending on the case.

The aromatic polyester resin used in the polarizing film of the present invention is polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, polyethylene bis-, which has excellent heat resistance, moisture resistance and transparency.
A resin composition containing at least 80% by weight or more of an aromatic polyester resin component such as α, β (2-chlorophenoxy) ethane-4,4′-dicarboxylate is preferable.

The amount of the dye used with respect to the base resin which is an aromatic polyester resin as described above is determined in consideration of the coloring ability of the dye and the thickness of the polarizing film to be obtained,
It is preferably adjusted so that the visible light transmittance per obtained polarizing film is 30 to 60%. For example, when the thickness of the polarizing film is 30 to 200 μm, the amount of the dye with respect to the base resin is in the range of 0.01 to 10% by weight.

In order to produce the polarizing film of the present invention, it is melted and colored with a base resin and at least one selected from the dyes of the present invention, and optionally other dyes to be mixed, and then formed into a film or sheet. , Then stretched 3 to 10 times in the machine or transverse direction at a temperature of 50 to 150 ℃, then 100 to 2
It can be produced by heat treatment at 30 ° C. for 1 second to 30 minutes. The stretching may be performed in only one direction, but if necessary, the stretching may be performed in a direction perpendicular to the main stretching direction by about 1.1 to 2 times.
It is also possible to improve the mechanical strength of the film.

The polarizing film produced in this manner can be processed into various forms of films and sheets for practical use depending on the application. That is, a) a film produced by the above method as it is, and b) a protective film having excellent optical transparency and mechanical strength on one or both sides, for example, protection made of colored or uncolored glass or synthetic resin. Membrane (layer)
A polarizing sheet or film in a form provided with c), a form in which an adhesive is applied to one side or both sides for convenience of application to a commonly used liquid crystal display, window glass or glasses, Further, d) a transparent film such as an indium-tin oxide is added to the surface of the polarizing film by a known method such as vapor deposition, sputtering or coating. These can also be used as a cell forming material for a liquid crystal display element.

[Examples] Representative examples of the dye of the invention and a polarizing film using the dye will be specifically described below with reference to examples.

The degree of polarization in the examples is a value measured by the following method. That is, the two polarizing films are stacked so that the stretching directions are parallel to each other and placed in the optical path of the spectrophotometer to measure the light transmittance (T _∥ ) at the maximum absorption wavelength in the visible region, and the two polarizing films are stretched. The degree of polarization (V) was calculated using the following formula from the light transmittance (T _⊥ ) at the same wavelength that was measured by overlapping so that the directions were orthogonal to each other.

Examples 1 to 7 Examples of use of the perylene-based dye used in the polarizing film of the present invention are dichroic ratio at the maximum absorption wavelength in polyethylene terephthalate and polarization degree at the maximum absorption wavelength of the polarizing film (single transmittance 40%). And the hue is shown in Table 1 below.

 ─────────────────────────────────────────────────── ─── Continuation of front page (56) Reference JP-A-50-105721 (JP, A) JP-A-59-223786 (JP, A) JP-A-57-63377 (JP, A) JP-A-57- 74361 (JP, A) JP 61-91285 (JP, A)

Claims (1)

[Claims] 1. An aromatic polyester resin containing a compound of general formula (I) [In the formula (I), R ¹ and R ² may be the same or different,
Each is a hydrogen atom, a halogen atom, a methyl group or a methoxy group, R ³ and R ³ ′ may be the same or different, and each of formulas (a) to (d) —CONH · R ⁴ (a) —CO ₂ · R ⁴ (b) (In the formulas (a) and (b), R ⁴ is a hydrogen atom, an alkyl group, a cycloalkyl group or an aryl group, and R ⁵ is a hydrogen atom, an alkyl group, an alkoxy group, a cycloalkyl group, an aryl group or a halogen atom. Y is an oxygen atom or a sulfur atom, m is an integer of 1 or 2, and when m is 2, they may form a ring together with the carbon atom to which they are attached, n and n'is 2 each. ] The polarizing film characterized by orienting and containing the perylene type | system | group dye represented by these.