JPH04333002A - Polarization film and manufacture thereof - Google Patents

Abstract

PURPOSE: To provide a polarizing film which has excellent polarization performance, is not changed by heat and moisture and is capable of maintaining polarization characteristics over a long period of time by incorporating specific dichromatic dyestuff into a hydrophobia resin 100. CONSTITUTION: The film obtd. by adding 0.001 to 15 pts.wt. dichromatic resins expressed by the formula to 100 pts.wt. hydrophobic resin and melting and kneading these resins, and molding the mixture to a film form is uniaxially stretched to 2 to 12 times. In the formula, Q is -N=N- or -CH=CH-, R<1> , R<2> are 1 to 10C alkyl groups having straight chains or side chains; R<3> is hydrogen or methyl group. The hydrophobia resin is a polyolefin resin, polyvinylidene cyanide resin, polyvinylidene fluoride resin, or polycarbonate resin. The uniaxial stretching is executed at a stretching magnification of 3 to 10 times within a temp. range of Tm-100 deg.C to Tm-5 deg.C or Tg-50 deg.C to Tg+100 deg.C when the melting p. of the hydrophobic resin is defined as Tm and the glass transition point as Tg.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polarizing film containing a hydrophobic resin and a specific oriented dichroic dye and having excellent polarizing properties and durability, and a method for producing the same.

0002

[Prior Art] Conventionally, polarizing films used for liquid crystal displays, photographic filters, etc. are generally made by attaching iodine or dichroic dye to a film base material such as polyvinyl alcohol resin to impart polarizing properties. It has been known.

0003

However, since such polarizing films have poor heat resistance and moisture resistance, they are usually put into practical use by covering both sides of the film with a durable protective film. However, since the polarizing film does not have sufficient durability, a durable film has been desired. On the other hand, a polarizing film using dichroic dye and polyester resin (Japanese Patent Laid-Open No. 58-68008
Although other methods have been proposed, such as dyes with improved dichroic ratios, that is, dyes with high dichroism, still result in insufficient orientation and only low polarization performance. It wasn't. Further, European Patent No. 348964 discloses a film in which a dichroic organic compound having liquid crystal properties is dispersed in a hydrophobic resin. The dichroic organic compound changes its state from an isotropic liquid state to a liquid crystal state and a crystalline state. , it is necessary to set the temperature to be suitable for processing the hydrophobic resin forming the matrix, and the combination of the dichroic compound and the hydrophobic resin,
There were problems such as difficulty in selecting the processing temperature.

0004

[Means for Solving the Problems] [Summary of the Invention] In view of the above problems, the present inventors have conducted extensive research, and as a result, have formed a dichroic dye with a specific structure in a specific state in a hydrophobic resin. The present invention was completed based on the finding that a polarizing film having excellent polarizing performance and high durability can be provided by doing so. That is, the polarizing film of the present invention has the general formula

embedded image (wherein, Q is -N=N- or -CH=CH-,
R1 and R2 are linear or side chain alkyl groups having 1 to 10 carbon atoms, and R3 is hydrogen or a methyl group. ) A resin film containing a dichroic dye represented by 0.001 to 15 parts by weight, characterized in that the dichroic dye is oriented in a hydrophobic resin. It is. In addition, in the method for producing a polarizing film, which is another invention of the present invention, the general formula

embedded image (wherein, Q is -N=N- or -CH=CH-,
R1 and R2 are linear or side chain alkyl groups having 1 to 10 carbon atoms, and R3 is hydrogen or a methyl group. ) is characterized by adding 0.001 to 15 parts by weight of a dichroic dye, melt-kneading it, forming it into a film, and uniaxially stretching the obtained film 2 to 12 times. .

[Detailed Description of the Invention] [1] Polarizing film (1) Constituent component (a) Hydrophobic resin The hydrophobic resin used as a component constituting the polarizing film of the present invention may be formed into a transparent film. There is no particular restriction as long as it is a hydrophobic thermoplastic resin that can be stretched and stretched; for example, polyolefins such as polyethylene and polypropylene; polyvinylidene halides such as polyvinylidene fluoride and polyvinylidene chloride; polyethylene terephthalate and polybutylene. Examples include polyesters such as terephthalate; polycarbonates; poly(meth)acrylate; polyether; polystyrene; polysulfone; homopolymers or copolymers such as polyamide; and resins obtained by mixing these. Preferably,
Polyolefin resins such as polyethylene and polypropylene, polyvinylidene cyanide, polyvinylidene fluoride,
A polyvinylidene halide resin such as polyvinylidene chloride, a polycarbonate resin, or the like can be used. The molecular weight of these hydrophobic resins is not particularly limited as long as they can be formed into a film by known film forming and stretching methods.

(b) Dichroic dye The dichroic dye used as a component constituting the polarizing film of the present invention has the general formula

embedded image (wherein, Q is -N=N- or -CH=CH-,
R1 and R2 are linear or side chain alkyl groups having 1 to 10 carbon atoms, and R3 is hydrogen or a methyl group. ) is suitable, preferably R
1 and R2 have 1 to 6 carbon atoms, and R3 is hydrogen or a methyl group. Such azo dyes can be synthesized by known methods, such as 4,
It can be produced by simultaneously azo coupling a diamine compound such as 4'-diaminostilbene or 4,4' diaminoazobenzene with two molecules of dialkylaminobenzene. As a specific compound,

[C6]

[C7]

[Chemical formula 8]

[Chemical formula 9]

Compounds such as embedded image can be mentioned. (c) Other blended components In addition to the dichroic dye and hydrophobic resin, which are the above-mentioned essential components, additives such as ultraviolet absorbers and antioxidants, pigments, etc. may be included as optional components. can.

(2) Amount ratio The amount ratio of the dichroic dye contained in the polarizing film of the present invention is 0.0 parts by weight to 100 parts by weight of the hydrophobic resin.
01 to 15 parts by weight, preferably 0.001 to 5 parts by weight,
More preferably, it is contained in an amount of 0.01 to 2 parts by weight.

(3) Orientation In the polarizing film of the present invention, it is important that the dichroic dye is oriented in the hydrophobic resin. Whether or not the dichroic dye is oriented in the hydrophobic resin in such a polarizing film can be determined by measuring the dye orientation coefficient FD value. The FD value is determined by measuring the absorbance from the change in the light intensity of the maximum absorption wavelength of polarized light vibrating parallel and perpendicular to the film's stretching axis that has passed through the sample film, and is determined by the following formula.

[Math 1] However, in the above formula

[Equation 2] where A// is the absorbance of polarized light parallel to the stretching axis, and A|
represents the absorbance of polarized light perpendicular to the stretching axis. The dichroic dye in the hydrophobic resin is generally 0.45 to 0.95, preferably 0.
．． It is oriented to an orientation degree of 75 to 0.95. (4) Physical properties The polarizing film of the present invention generally has a degree of polarization of 80% or more due to the orientation of the dichroic dye. Furthermore, the heat resistance and moisture resistance are improved so that the rate of change in the degree of polarization after 1,000 hours is within 5%, particularly within 2%.

[II] Method for producing a polarizing film (1) Formulation First, the dichroic dye and the hydrophobic resin are mixed in a predetermined ratio as described above, and heated to a temperature higher than the melting point of the dichroic dye, for example, the melting point. Melt-kneading is carried out at a temperature of ~ melting point +200°C, preferably melting point +5°C ~ melting point +150°C. The kneading can be carried out by a commonly used extruder, a mixer such as a Brabender plastograph, or the like. Among these mixers, it is preferable to use a Brabender Plastograph or the like for kneading.

(2) Production of film (a) Film forming The kneaded product of the resin composition obtained as described above is formed into a film at the above-mentioned kneading temperature by, for example, a T-die method or an inflation method. The thickness of the film at this time is 100 to 750 μm, preferably 150 to 500 μm.
It is.

(b) Stretching It is important for the polarizing film of the present invention that the dichroic dye is maintained in a highly oriented state within the film thus formed. As a means for highly oriented the dichroic dye in this manner, the obtained film is uniaxially stretched. In the uniaxial stretching method, a roll stretching machine,
This is generally carried out using a calender roll or the like. The stretching temperature is preferably Tm-100°C to Tm-5°C or Tg-50°C to Tg+100°C, where Tm is the melting point and Tg is the glass transition point of the hydrophobic resin. At this temperature, the film is uniaxially stretched 2 to 12 times, more preferably 3 to 10 times. The thickness of the polarizing film of the present invention thus obtained is generally 10 to 15
0 μm, preferably 30 to 100 μm.

[III] Applications The polarizing film thus produced can be used not only as a film or sheet, but also as various molded products after being subjected to various processing. For example, depending on the application, a transparent conductive film of indium-tin-based oxide may be formed on the surface of the polarizing film of the present invention by lamination with other polymers, or by vapor deposition, sputtering, or coating. can.

[0013]

EXAMPLES The present invention will be explained in more detail with reference to examples below, but the present invention is not limited to the following examples. The polarizing performance of the polarizing film can be measured using the following measurement method:
Measured using evaluation criteria. (1) Polarization performance spectrophotometer (MPS-2000, manufactured by Shimadzu Corporation)
The light transmittance (T1) at the maximum absorption wavelength in the visible region measured in the optical path of a spectrophotometer by stacking two polarizing films so that the stretching directions are parallel using
The light transmittance (T2) at the same wavelength measured by stacking two polarizing films so that their stretching directions were perpendicular to each other and placing them in the optical path was determined, and the degree of polarization (V) was calculated using the following formula.

[Math 3]

Example 1 Polypropylene resin (FY-4, manufactured by Mitsubishi Yuka Co., Ltd.) 1
20g and the structural formula is

A masterbatch was prepared by uniformly blending 0.9 g of dichroic dye A represented by the following formula at 240° C. using a Brabender Plastograph. Obtained masterbatch 110
g and 780 g of polypropylene resin using a 15 mm extruder equipped with a T die (dice width 120 mm).
The film was formed at 10°C. Next, using the roll stretching machine shown in FIG. 1, it is passed through a low-speed roll 6 (0.85 m/min) at a temperature of 120°C, and then stretched by 6.5 m/min in the longitudinal direction by a high-speed cooling roll 5 (5.5 m/min). This was stretched twice to obtain a polarizing film with a thickness of about 75 μm. The polarizing properties of the obtained polarizing film are as follows:
The transmittance (light transmittance at the maximum absorption wavelength of one polarizing film; T0) is 36.0%, and the degree of polarization (V) is 98.
5%, and no variation in the width direction was observed.

Example 2 The structural formula is

[Chemical formula 12] Instead of the dichroic dye A represented by, the structural formula is

[Chemical 1
3] A polarizing film was produced in the same manner as in Example 1, except that a masterbatch was prepared by blending dichroic dye B represented by the formula B at a temperature of 210° C. using a Brabender plastograph. The properties of the obtained polarizing film are T0
= 36.8%, V = 97.0%, and no variation in the width direction was observed.

Example 3 Polyvinylidene fluoride (Solef 1008 manufactured by Solvay) was used as a binder resin, and the structural formula was

A polarizing film was produced in the same manner as in Example 2 using dichroic dye B represented by the following formula. The properties of the obtained polarizing film were T0 = 38.0% and V = 96.3%, and no variation in the width direction was observed.

Example 4 Vinylidene cyanide/vinyl acetate copolymer (synthesized product manufactured by Mitsubishi Yuka Co., Ltd.) and the structural formula

210 in the same manner as in Example 2 using dye D represented by
The film was formed at ℃. Then, this was stretched in the longitudinal direction by a factor of 6.0 at 180° C. and a speed of 20 mm/min using a roll stretching machine shown in FIG. 1 to obtain a polarizing film of about 80 μm. The properties of the obtained polarizing film are: T0 = 39.0%,
V=96.5%, and no variation in the width direction was observed.

Example 5 120 g of polycarbonate (L-1250 manufactured by Teijin) and a structural formula of

A masterbatch was prepared by uniformly blending 0.9 g of dichroic dye D represented by the following formula at 250° C. using a Brabender plastograph. Obtained masterbatch 11
0g and 780g of polycarbonate using a 15mm extruder equipped with a T die (dice width 120mm).
The film was formed at 50°C. Next, this was stretched 5.0 times in the longitudinal direction at 175° C. and a speed of 20 mm/min using a roll stretching machine shown in FIG. 1 to obtain a polarizing film with a thickness of about 80 μm. The properties of the obtained polarizing film are T0 = 3
5.0%, V=96.0%, and no variation in the width direction was observed.

[0019]

[Effects of the Invention] The polarizing film of the present invention has an easily oriented dichroic dye highly oriented in a hydrophobic resin, so it has excellent polarizing performance and is also heat resistant and moisture resistant. Excellent and highly durable. Therefore, it is hardly changed by heat or moisture, and can maintain its polarization properties for a long period of time.

[Brief explanation of drawings]

FIG. 1 shows a roll stretching machine used in producing the polarizing film of the present invention.

[Explanation of symbols]

1 Extruder 2 T-die 3 Chill roll 4 Nip roll 4' Nip roll 5 High speed (cooling) roll 6. Low speed (preheating) roll

Claims (7)

[Claims] Claim 1: With respect to 100 parts by weight of the hydrophobic resin, the general formula [I] [Formula 1] (wherein, Q is -N=N- or -CH=CH-,
R1 and R2 are linear or side chain alkyl groups having 1 to 10 carbon atoms, and R3 is hydrogen or a methyl group. ) A polarized light resin film containing a dichroic dye represented by 0.001 to 15 parts by weight, the dichroic dye being oriented in a hydrophobic resin. film. [Claim 2] The general formula [I] according to Claim 1 is applied to 100 parts by weight of the hydrophobic resin (where Q is -N=N- or -CH=CH-,
R1 is a straight chain or side chain alkyl group having 1 to 10 carbon atoms, R2 is a straight chain or side chain alkyl group having 5 to 10 carbon atoms, and R3 is hydrogen or a methyl group. ) A polarizing film containing a dichroic dye represented by 0.001 to 15 parts by weight, the dichroic dye being oriented in a hydrophobic resin. . Claim 3: R1 in [I] of the general formula is a methyl group, n
-pentyl group or hexyl group, R2 is n-pentyl group or hexyl group, and R3 is hydrogen or methyl group, the polarizing film according to claim 1. 4. The polarizing film according to claim 1, wherein the hydrophobic resin is a polyolefin resin, a polycyanide vinylidene resin, a polyvinylidene fluoride resin, or a polycarbonate resin. 5. With respect to 100 parts by weight of the hydrophobic resin, the general formula [I] [Chemical formula 2] (wherein, Q is -N=N- or -CH=CH-,
R1 and R2 are linear or side chain alkyl groups having 1 to 10 carbon atoms, and R3 is hydrogen or a methyl group. ) A polarizing film characterized by adding 0.001 to 15 parts by weight of a dichroic dye, melt-kneading it, forming it into a film, and uniaxially stretching the obtained film 2 to 12 times. Production method. 6. The method for producing a polarizing film according to claim 5, wherein the hydrophobic resin is a polyolefin resin, a polycyanide vinylidene resin, a polyvinylidene fluoride resin, or a polycarbonate resin. 7. Uniaxial stretching is carried out at a temperature where the melting point of the hydrophobic resin is Tm.
, wherein the stretching is carried out at a stretching ratio of 3 to 10 times within a temperature range of Tm-100°C to Tm-5°C or Tg-50°C to Tg+100°C, where the glass transition point is Tg. Method for manufacturing polarizing film.