JPS6254201A - Polarizing film and its manufacturing method - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a polarizing film in which a dye is dyed and oriented on a polyamide film. The present invention relates to a polarizing film characterized in that a highly oriented dye is induced by immersion treatment in a solution in which the dye is dissolved.

[Conventional technology]

Conventional polarizing films include polyvinyl alcohol (
It is well known that Pvm)-based films are dyed with iodine or dichroic dyes. However, although these polarizing films have excellent polarizing performance, they have lI# points in heat resistance, latent resistance, etc., and in order to improve this, they are put into practical use after being laminated with a cellulose acetate film or the like. However, even this does not provide sufficient moisture resistance depending on the application.

As a polarizing film based on a hydrophobic polymer other than the pvA type, a polarizing film made by dehydrohalogenating a halogenated vinyl polymer such as PVO or PVDO to form a polyene structure is also being considered. However, these have not yet become mainstream in polarizing films because #1 has problems with heat resistance and stability against light and oxygen, and it is impossible to freely select the hue.

Furthermore, for example, special public ti1%? Polyamide-based polarizing films are disclosed in Japanese Patent Application Laid-open No. 39%% and Japanese Patent Application Laid-open No. Shoj%-@j/63. However, although polyamide-dye polarizing film is superior in heat resistance, moisture resistance, mechanical strength, etc. to PV Mu-iodine polarizing film, Pv Mu dichroic dye polarizing film, and polyene-based polarizing film,
Polarized eggs are inferior to the three.

[Purpose of the invention]

The present inventors have conducted extensive research in order to increase the dye orientation coefficient (Fdye) of polyamide-dye polarizing films. As a result, by combining the process of dyeing the polyamide film with a dichroic dye, the process of -axis stretching, and the process of immersing the film in a solution (A) that can swell the polyamide, 7dyθ was dramatically increased. It was discovered that the size increases, leading to the present invention.

[Structure of the invention]

Here, the Fdye value will be explained. Fdye is calculated by the following formula (1).

Faye=(D-/)/(D+-2) ・・−・−
...-<1) Here, D is the absorption-color ratio of the dichroic dye-containing film and is based on the following formula (2).

D=LOg (10/Im)/Log (10/
II) ...(2) However, the same - extension dispute,
Let the transmittance of an undyed film under the same processing conditions be to, and let the transmittance values when the polarization plane of the incident light beam and the stretching axis are perpendicular and parallel to each other be TI and 1 m, respectively. The II'dye value represents the degree of orientation of the dichroic dye, and a higher IPdye value indicates a higher polarizing performance of the polarizing film.

The material of the polyamide film used in the present invention is selected from aliphatic polyamide (A): aromatic polyamide (B): polyamide containing an aromatic ring (C); and; (A), (B), and (0). There are mixtures of two or three types.

Further, the stretching ratio of the above-mentioned polyamide film is not particularly controlled as long as it is 2 times or more, but it is generally preferable to stretch the polyamide film to a high ratio within the stretchable range. Although there are no particular restrictions on the stretching temperature, it is usually carried out at 20 to -00°C. The dye may be applied either before or after stretching the film. The dye used for dyeing is a dye that has a high absorption two-color ratio after dyeing among ordinary direct dyes, acid dyes, and disperse dyes. The dyeing of the film is carried out according to the usual method, and the dyeing temperature is usually 30 to 2θ°C.
The amount of dyeing is 0. Selected from between θj weight ratio or more and /weight rice cake less.

Examples of the above dyes include Direct Fast Yellow GO, Karayas Spra Orange-2GL-/26
Congo Red, Dial Z Eggplant Red 4tB1
Dial Minas Stop Blue B, 2R1 Diamond Kyupro Red jB, Kayaras Hotaru Supra Blue %G, Diamond Cupro 9 Blue R1 Nippon Brilliant Sachi Violet) B
K.

Kayarasu Supragreen GG, Kayarasu e Supraclean? ((G, Sumikaron Blue KBR.

Alizarin Bansu Fillor BF, Gold Orange, Sumirai) - Sprapul - FBGL (all products)
and mixtures thereof.

A solution capable of swelling polyamide, which is a feature of the present invention (A
) is for the purpose of dramatically increasing the Fdye value obtained in the -axis stretching process by immersing the uniaxially stretched film dyed with a dichroic dye in the solution. . In some cases, uniaxial stretching may be performed after the dipping treatment.

A solution capable of swelling the polyamide used in the present invention (A
) is an acidic aqueous solution, for example, a polyamide resin solvent such as formic acid, sulfuric acid, or metacresol, which is generally used as a diluted solution with water.

The concentration of the diluted solution is determined by the swelling degree when the polyamide film is immersed, and the solvent concentration relative to water is /θ volume percent or more and rθ volume percent or less; preferably 10 volume percent or more and rθ volume percent or less. . A concentrated solution of more than θ volume percent is not preferable because the polyamide film will dissolve.

By immersing a dichroic dye-dyed film that has been subjected to -axial stretching in the swelling solution (A), for example, the way value of θ0.2 to 0, y at the -axial stretching stage can be changed to 0. 7
This further improves to 0.6 or more.

A solution obtained by dissolving a metal salt in the swelling solution (A) can be used as the swelling solution. As the metal salt, a halogenated alkali metal bar or a halogenated alkaline earth metal bar is used, and seven or several types are selected from metal salts such as lithium chloride, potassium chloride, calcium chloride, sodium chloride, and lithium bromide. The concentration of the metal salt in the swelling solution (A) is not particularly limited and is appropriately determined depending on the solubility of each metal salt, but is usually used at an fIk degree of 5 to 30% by weight. The metal salt is used to fix and maintain the improved Fdye value obtained by immersing the dichroic dye-dyed film in the swelling solution (A).

Various methods can be considered for the dipping treatment of the present invention, but for example, after or before uniaxial stretching by a normal roll method, tenter method, or inflation method, the swelling solution
The film may be passed through a bath containing a solution of (A) in which a metal salt is dissolved. The immersion time may be from /θ seconds to 7.20θ seconds as long as the film reaches an equilibrium degree of swelling. The degree of swelling is such that the amount of absorbed solution is 10 to 20% by weight, preferably 11% by weight.
θ weight is around i−.

Polyamide film itself has excellent mechanical properties,
A polarizing film made of polyamide film does not deteriorate its polarizing performance under high temperature and high humidity conditions, without compromising its heat resistance, water resistance, and weather resistance. Further, depending on the purpose of use, the polarizing film may be used while being protected by lamination with plastic or the like.

〔Example〕

The present invention will be explained below with reference to Examples.

However, the present invention is not limited to these examples.

Comparative Example/Nylon resin was melt-extruded to form a film that was substantially free of pores. This film was coated with Congo red, a type of direct dye, at a concentration of 0. /% aqueous solution at SO 0 C for 75 minutes and dyed pale red. Next, using a biaxial stretching tester (manufactured by Long Co., Ltd.), this was stretched 3 times in the free width in the -axial direction.
A polarizing film was prepared by a conventional method by stretching at a temperature of 0°C.

Regarding the polarizing film of Jin, the transmittance of 11.11 was measured in the visible region when the polarization plane of the incident light beam and the stretching axis were perpendicular and parallel using a spectrophotometer - L type (manufactured by Hitachi), The orientation coefficient F'dye was calculated based on the following formula.

! Pdya = (D-/)/(D+J) (where D is absorption-color ratio, D=Log (to/summer x)/Log(summer o/lx) 0
is the transmittance of an undyed film under the same stretching conditions) The calculated value is for a wavelength of 620. The results are shown in Table 1, which is the average value of each value in YO%jOnm.

Example/ The polarizing film obtained in Comparative Example/ was treated with concentrated formic acid (tq).

A polarizing film with a dramatically improved payθ was obtained by immersion treatment in a formic acid aqueous solution at 20° C. for 7 minutes. In this case, due to the characteristics of Congo red, the characteristic absorption changes depending on the pH, but as in the comparative example, is the orientation coefficient? dye
was calculated and the results are shown in Table/.

The unstretched dyed raw fabric obtained in Example/Comparative Example/ was treated with ants similar to Example/.
After being immersed in an acid aqueous solution for 7 minutes, it was immediately stretched uniaxially three times. The stretching temperature at this time was -2J°C. The orientation coefficient Fdye of this polarizing film was calculated in the same manner as in Example/, and the results are shown in Table/.

Example 3 A solution of lithium chloride/θt//0000 dissolved in an aqueous solution of m acid with a formic acid concentration aO volume percent was cleaved to 1liI. Next, the stretched polarizing film obtained in Comparative Example/ was immersed in the above solution at 20°C for 70 minutes.
A polarizing film with dramatically improved ye was obtained. The Fays of this polarizing film was calculated in the same manner as in the other examples, and the results are shown in Table 1.

Example 2 A polarizing film was prepared in the same manner as in Example 3 except that potassium chloride was used as the metal salt.

The orientation coefficient of this polarizing film was calculated in the same manner as in Example/, and the results are shown in Table/.

Comparative Example A red polarizing film was prepared in exactly the same manner as in Comparative Example except that Conylon-JJ resin was used, and Pdye was calculated. The results are shown in Table/.

Example j The polarizing film obtained in Comparative Example J was subjected to the same solution immersion treatment as in Example 3, and Fdye was calculated.

The results are shown in Table/.

Comparative Example 3 A mixture obtained by melt-mixing a polyamide resin obtained by polymerizing hexamethylene diane, isophthalic acid, and terephthalic acid in a molar ratio of 3:co:/ with a nylon d resin at a composition ratio of θ/10 was melted. Extruded, substantially non-oriented 100μ
A thick film was formed. This film was coated with Congo red, a type of direct dye, at a concentration of 0. /6% in aqueous solution
It was immersed at 0°C for 3θ minutes and stained pale red. Next, using a biaxial stretching tester (manufactured by Long Co., Ltd.), this was stretched in the -axial direction with a free width twice as much at a temperature of 700 DEG C. to prepare a polarizing film according to a conventional method. F dye was calculated for this polarizing film in the same manner as in Comparative Example/, and the results are shown in Table/.

Example d A solution was prepared in which lithium chloride was dissolved at a concentration of /θf / /θOoc in an aqueous formic acid solution having a formic acid concentration of 4 tO volume percent. Next, the stretched polarizing film obtained in Comparative Example 3 was immersed in the above solution at 20° C. for 5 minutes to obtain a polarizing film with dramatically improved I' dye. The 'W dye value of this polarizing film was calculated in the same manner as in Example/, and the results are shown in Table 1.
It was shown to.

Example 2 A polarizing film was prepared in the same manner as in Example 4 except that potassium chloride was used as the metal salt.

The paye value of this polarizing film was calculated in the same manner as in Example/, and the results are shown in Table/.

Example! Using an unstretched Congo red dyed raw fabric prepared in the same manner as in Comparative Example 3, it was immersed for 3 minutes in the potassium chloride-containing solution used in the example core, and then immediately stretched uniaxially to 3 times the free width. The temperature during stretching was 23°C. The F dye of this polarizing film was calculated in the same manner as in Example/, and the results are shown in Table/.

Comparative Example A mixture obtained by melt-mixing a polyamide resin obtained by polymerizing dahexamethylene diamine, isophthalic acid, and terephthalic acid with a molar ratio of 3:λ:/ and a nylon resin at a composition ratio of θ/20 was melted. Extrusion, substantially unoriented /θθμ
A thick film was formed. This film was immersed in a 0.2% aqueous solution of Dialminus Blue B, 2R (trade name, manufactured by Mitsubishi Kasei Corporation), a type of direct dye, at 60° C. for 3θ minutes to dye it pale blue. Next, using a biaxial stretching tester (manufactured by Long Co., Ltd.), this was stretched by 9 times in the free width in the -axial direction.
A polarizing film was prepared by a conventional method by stretching at a temperature of 0°C.

Regarding this polarizing film, 1iFdy
The e value was calculated and shown in Table/.

However, the L Fdye value is the wavelength 6θ0.4.201t4tOn
It was taken as the average value of the values in m.

Example 9 The polarizing film obtained in Comparative Example D was immersed in the same solution as in Example 4 at 20° C. for 7 minutes to obtain a polarizing film with dramatically improved IF dye. The Pd7θ value of this polarizing film was calculated in the same manner as in Comparative Example DA.As is clear from the table, how does the film subjected to the immersion treatment of the present invention compare to the non-immersion treated product? It can be seen that the dye value is dramatically improved and the polarization ability is large.

Also, Example 3, da, j, j, 7, /,? The F'dye value of the polarizing film did not decrease even if it was stored indoors during the evening months.

〔Effect of the invention〕

As described above, the polyamide polarizing film of the present invention has excellent heat resistance, moisture resistance, and strength, and has a high dye orientation coefficient.

Sender: Mitsubishi Chemical Industries, Ltd. Representative Patent attorney For quality – Others/Names

Claims (10)

[Claims] (1) A polarizing film made of a polyamide film in which a dichroic dye is dyed and oriented and the orientation coefficient Fdye value due to the dye is 0.4 or more. (2) The polarizing film according to claim 1, which is made of a polyamide film having an orientation coefficient Fdye value of 0.6 or more due to dyes. (3) The feature includes three steps: dyeing the polyamide film with a dichroic dye, immersing the polyamide film in a solution that can swell the polyamide, and stretching the polyamide film in a uniaxial direction. A method for producing a polarizing film. (4) The method for producing a polarizing film according to claim 3, wherein a metal salt is dissolved in the solution capable of swelling the polyamide. (5) A method for producing a polarizing film according to claim 3, characterized in that the polyamide film dyed with a dichroic dye is uniaxially stretched and then immersed in a solution capable of swelling the polyamide. . (6) A method for producing a polarizing film according to claim 3, characterized in that a polyamide film dyed with a dichroic dye is immersed in a solution capable of swelling the polyamide, and then stretched in a uniaxial direction. . (7) The polyamide film dyed with a dichroic dye is uniaxially stretched and then immersed in a solution that can swell the polyamide in which a metal salt is dissolved. 4. A method for producing a polarizing film according to any one of Item 4. (8) The polyamide film dyed with a dichroic dye is immersed in a solution capable of swelling the polyamide in which a metal salt is dissolved, and then stretched in a uniaxial direction. 4. A method for producing a polarizing film according to any one of Item 4. (9) The method for producing a polarizing film according to any one of claims 3 to 8, wherein the solution (A) capable of swelling polyamide is an acidic aqueous solution. (10) The metal salt according to any one of claims 3, 4, 7 and 8, characterized in that the metal salt is an alkali metal halide and/or an alkaline earth metal halide. Method for manufacturing polarizing film.