JPS60230606A - Polarizing film - Google Patents

Abstract

PURPOSE:To improve the polarizing performance and the durability at high temp. and humidity by sticking a dichroic dye to the surface of a film of modified polyvinyl alcohol contg. cation groups in the molecule and/or by incorporating the dye into the film. CONSTITUTION:Modified polyvinyl alcohol (PVA) contg. cation groups is prepd. The modified PVA contains copolymerizable units selected among copolymerizable units represented by formulae I -VI (where each of R<1>-R<14> is H, lower alkyl or the like; B is a group represented by formula VII or the like; X<-> is an anion; A is a group combining N in B with N in amido; and D is a group combining N in B with 0). The modified PVA is formed into a film and the resulting PVA-base film is dyed with a dichroic dye such as ''Direct Fast Yellow GN(R)'' to obtain the desired polarizing film.

Description

Detailed Description of the Invention A4 Technical Field of the Invention The present invention relates to a polarizing film with excellent polarizing performance and durability. More specifically, polarized light with excellent polarizing performance and durability, characterized by having a dichroic dye on the surface and/or inside of a polyvinyl alcohol film made of modified polyvinyl alcohol containing a cationic group in the molecule. It concerns membranes.

B. Prior art and its problems In recent years, liquid crystal displays have been used in watches, calculators, game machines, etc., and the amount of polarizing films indispensable for liquid crystal displays has rapidly increased. Furthermore, its field of use is also OA.
It is expanding into equipment, automotive equipment, televisions, etc., but when used in harsh environmental conditions, such as automotive equipment,
Even better polarization performance and durability are required.

There are many types of polarizing films, but currently most of them are produced industrially, with dichroic substances adsorbed and oriented on polyvinyl alcohol (hereinafter abbreviated as PVA) films. Furthermore, depending on the type of dichroic substance, there are two types: (1) iodine-based polarizing film and (2) dichroic dye-based polarizing film. Other %P
Polyene-based scouting films have also been proposed, which are obtained by inducing a dehydration reaction from a VA-based film or by forming a polyene through a dehydrochloric acid reaction from a polyvinyl chloride film.

However, although the iodine-based polarizing film has a high degree of polarization,
If left in a high temperature and high humidity environment, the iodine sublimes and loses its polarizing properties. In order to improve this shortcoming of lack of durability under high temperature and high humidity conditions, proposals have been made to treat polarizing films with a boric acid aqueous solution or heat treatment, and to use laminated films coated with hydrophobic resin as protective films. Although it has been proposed to use it as a method, satisfactory results have not yet been obtained.

The polarizing film, which adsorbs and aligns dichroic dyes that do not sublimate even under high temperature and high humidity conditions instead of iodine, has excellent durability under high temperature and high humidity conditions. Dichroic dyes have a wide variety of color tones, such as ones that exhibit the same neutral gray color as iodine, and color displays used in automobile equipment and televisions. Because the molecular weight is large, P
It has drawbacks such as difficulty in adsorption to VA-based films, resulting in uneven adsorption, resulting in uneven dyeing, and a low degree of polarization.

In addition, the polyene polarizing film has the disadvantage that the polyene formation reaction progresses due to heat and light, and the polarization performance changes over time, so it has not been put into practical use. In view of this, as a result of careful examination, we found that a polarizing film characterized by having a dichroic dye on the surface and/or inside of a polyvinyl alcohol film made of modified polyvinyl alcohol containing a cationic group in the molecule. Since a PVA film made of modified polyvinyl alcohol (hereinafter abbreviated as modified PvA) containing cationic groups is used, it is extremely easy for dichroic dyes to be adsorbed onto the base film. They found that there is no uneven dyeing, a high degree of polarization, and excellent durability under high temperature and high humidity conditions, leading to the completion of the present invention.

D1 More detailed description of the present invention The cationic groups contained in the modified PVA containing cationic groups in the molecule used in the present invention are primary amines,
Secondary amines, tertiary amines, quaternary ammonium salts, pyridine, pyridinium, imidazole, imidazolinium,
Refers to chemical structural units such as sulfonium and phosphoram that dissociate in aqueous solution and become positively charged.

Modified PVA containing these cationic groups in the molecule includes all those containing the above-mentioned positively charged chemical structural units, but those having the following general formulas (1), (II),
(m), (JV), (■) Alloy is modified PVA containing a cationic group selected from the copolymerized units shown in (■) TE.
Not only does it have excellent performance, but it is also preferred because it is stable and easy to implement as a method for industrially introducing cationic groups and obtaining a degree of saponification according to the purpose.

2 gl 3 (where R1, 'R2, R3 are hydrogen atoms or lower alkyl is a hydrogen atom or a lower alkyl group (which may contain a substituent), X- is an anion, A is a nitrogen atom in B and an amide +CH2-CH+ +CHs+-CH)- (Here, R7, R8, R9, RIG are hydrogen atoms, lower alkyl groups, or phenyl groups (including substituents). ),
X- means an anion. ) (Here B
is the same as B in (1), and D means - which connects the nitrogen atom and oxygen atom in B, respectively. ) to 11÷CHz-C+(V) (where R11, R12, 113, and R14 are hydrogen atoms or lower alkyl groups (which may contain substituents),
- means an anion. ) Modified PVA containing copolymerized units represented by the above general formulas (1) to (IV) can be produced by combining vinyl ester, rewake vinyl acetate, and the following formulas (a) to (=) 3 CH2= C)l CH2=CH (Kokote, 11-13, R7-RIO1X-1A, B:
Do has the same meaning as above. ) in the presence of a radical polymerization initiator, and then an alkali or acid catalyst is applied to the alcohol solution of the copolymer to form vinyl ester units in the copolymer. It can be effectively and easily produced by partially or highly saponifying it to form vinyl alcohol units depending on the purpose.

In the monomer represented by general formula (a), B, 1. R2
is a hydrogen atom or a lower alkyl group, usually a hydrogen atom or a methyl group is preferred, and a hydrogen atom is particularly preferred because the polymerization rate during copolymerization with vinyl acetate is high. R3 is also a hydrogen atom or a lower alkyl group, and usually represents a hydrogen atom or a lower alkyl group which may contain a methyl atom or a substituent, and X- represents an anion. R
4, Hfi, R6 is preferably a methyl group for normal purposes, but for special purposes it may be an ethyl group, a lower alkyl group such as a propyl group, a methylol group for the purpose of imparting reactivity, a diethyl group for hydro, or a cationic group. A lower alkyl group containing a substituent such as an aminoalkyl group is also used for the purpose of improving the density. X is a chlorine atom such as chlorine, oxal, iodine, or CHsO8
Oa, CH3C6H4SO3, and CHaCOO are preferred, but chlorine atoms are particularly preferred from the economic, safety, and physical properties of modified PVA. B is preferably in the form of a quaternary ammonium salt for ease of handling in the production of modified PVA, but -class to tertiary amines can also achieve the effects of the present invention. As the group A that connects the nitrogen atom in the amino group B and the nitrogen atom of the amide group, any group containing a stable bond can be used, but usually a linear or branched aliphatic group is used. It will be done.

Examples of the monomer represented by the above general formula (a) include the following. N-(2-dimethylaminoethyl)acrylamide, N-(2-dimethylaminoethyl)
Methacrylamide, N-(3-dimethylaminopropyl)acrylamide, N-(3-diethylaminepropyl)acrylamide, N-(3-dimethylaminopropyl)methacrylamide, N-(3-diethylaminopropyl)methacrylamide, N- (1,1-dimethyl-3-
dimethylaminopropyl)acrylamide, N-(1゜1-diethyl-3-dimethylaminobutyl)acrylamide, N-(1-methyl-1,3diphenyl-3-
diethylaminepropyl)methacrylamide, N-(3
-methylethylaminopropyl) methacrylamide, N
-Methyl-N-(3-dimethylaminopropyl)acrylamide, N-(2,2-dimethyl-3-diethylaminopropyl)acrylamide, N-(2,2-dimethyl-3-dimethylaminepropyl)crotonic acid amide, N
-(3°3-dimethyl-4-dimethylaminobutyl)methacrylamide, N-(3-methylaminopropyl)acrylamide, N-(aminoethyl)methacrylamide, isopropylaminopropylmethacrylamide.

Among the monomers represented by the above general formula (A), those in the form of quaternary ammonium salts are obtained by using the above-mentioned tertiary amine group-containing monomers with commonly used quaternizing agents such as methyl halide, benzyl halide, It can be obtained by quaternizing dialkyl sulfuric acid, paratoluenesulfonic acid alkyl ester, or alkylene oxide with an acid such as acetic acid or hydrochloric acid. Among the monomers exemplified above, N-(1,1-dimethyl-3-dimethylaminopropyl)acrylamide, trimethyl-(3-acrylamido-3,3-dimethylpropyl)ammonium chloride, N-(3-dimethyl Aminopropyl)methacrylamide and trimethyl-(3-methacrylamidopropyl)ammonium chloride are used in the production of the modified PVA of the present invention from the viewpoints of polymerization rate, stability of amide groups, and economic efficiency during monomer production. Are better.

Further, examples of the monomer shown in (b) above include the following. 1-vinylimidazole, 1-vinyl-2-methylimidazole, 1-viny/l/-2-methylimidazole, 1-vinyl-2-phenylimidazole, 1-vinyl-2,4,5-trimethylimidazole. Further, the monomer represented by the above general formula (c) can be easily obtained by quaternizing the monomer represented by the above general formula (b) with a commonly used quaternizing agent.

Examples of the monomer represented by () in the above general formula include dimethylaminoethyl vinyl ether, dimethylaminopropyl ether, vinyloxyethylamine, or quaternized products thereof. As a method for containing the copolymerized units shown above, vinyl esters discovered by the present inventors, particularly vinyl acetate and N-vinylacetamide,
N-vinyl-N-methylacetamide or #iN-vinyl-N-methylformamide or N-vinyl-methylcarbamate, N-vinyl-t-butylcarbamate, N-impropenylmethylcarbamate, N-isopropenyl-t-butyl It is preferable to copolymerize a carbamate or the like in the presence of a radical polymerization initiator and then hydrolyze the copolymer, since the amide group or carbamate group can be hydrolyzed to form a vinylamine unit. Furthermore, the amine group of the modified PVA obtained by decomposing the amide group or carbamate group can be quaternized to form a quaternary ammonium group as shown in the above formula (b).

Conventionally reported methods for producing cation-modified PVA include copolymerization and saponification of vinylpyridine and vinyl acetate, copolymerization of N-vinylphthalimide or N-vinylsuccinimide and vinyl acetate, and then saponification of vinyl acetate with alkali or hydrazine. Method of decomposing imide groups in PVA
A method of aminoacetalizing or aminobenzalizing with an acid catalyst, a method of reacting PVA with alkoxydimethylamine, glycidyltrimethylammonium hydrochloride or 3-chloro-2-hydroxyglohiltrimethylammonium hydrochloride, a method of reacting PVA with acrylamide A method is known in which an amino group is introduced from a Hofmann fraction tIsK after Michael addition of . Cation-modified PVA synthesized by these methods can also be used in the composition of the present invention, but the above-mentioned method for producing cation-modified PVA has various problems in the cationization process itself in order to be implemented industrially. Cationically modified PVA containing a sulfonium group or phosphonium group is similar to cationically modified PVA containing a quaternary ammonium group, and a method of copolymerizing a monomer containing a sulfonium group or a phosphonium group with a vinyl ester and then saponifying the PVA. It is produced by reacting a compound containing a sulfonium group or a phosphonium group with a compound containing a sulfonium group or a phosphonium group. Examples include a method of copolymerizing and saponifying methyl diallylsulfonium methyl sulfate and vinyl acetate, and a method of converting PVA into p-chloromethylbenzaldehyde acetal and then reacting with dimethyl sulfide to introduce a benzyldimethylsulfonium chloride group. Furthermore, a benzyltrimethylphosphonium group can be introduced by converting PVA into p-chloromethylbenzaldehyde acetal and then reacting it with trimethylphosphine.

The content of cationic groups in the cationic group-modified PvA used in the present invention, the degree of saponification, and the degree of Fi polymerization are selected as appropriate, but these three factors must be carefully controlled in order to obtain a polarizing film with excellent performance. It is important to combine the

For the purposes of the present invention, the content of cationic groups is 0.01.
~',; O mol, preferably 01 to 10 mol, degree of saponification 60 to 100 mol, degree of polymerization 100 to 6,00
A range of 0 is preferred.

On the other hand, the dichroic dye used in the present invention is a dye having so-called dichroism, and there is no restriction on the type thereof, such as a direct dye, an acid dye, or a disperse dye.

For example, oDirect Fast Yel manufactured by Sumitomo Chemical
low GN.

Diract Sky Blue 5B, Direc
t Brown MA, SunlightSupra
Red 5BW, Sunlight 5upra
Blue FBGL.

Sunlight, 5upra, Gray CGL,
Kayarus Light Rose manufactured by Nippon Kayaku
F'R, Kayaku Direct Violet L
NA, Kayanol Blue N2G, Kaya
nol Yellow GG.

Examples include Kayanol Milling Red GRA.

In producing the above-mentioned modified PVA gold film containing cationic groups in the molecule, polyvinyl alcohol rust conductors such as conventional unmodified polyvinyl alcohol polymers and saponified products of poly(ethylene-vinyl acetate) copolymers are used. There is nothing wrong with appropriately mixing them as long as the purpose of the invention is not impaired.

There is no particular restriction on the mixing ratio of the above-mentioned polyvinyl alcohol crocodile conductor and the modified PVA containing a cationic group in the molecule of the present invention, but for example, in terms of weight ratio, the former/alligator = 0/100 to 1. It is 9971.

Furthermore, there is no problem in using glycols such as glycerin or diethylene glycol as a plasticizer, or in combination with additives such as lubricants and surfactants.

As a film forming method for the PVA film made of modified PVA containing a cationic group in the molecule of the present invention, conventionally known methods are used, such as dissolving the modified PVA in water and casting it on a drum or pelt. Spread method or modified PV
A film is formed by adding water to A and dissolving in an extruder (7) to form a film.

A conventionally known method can be used to produce a polarizing film using the PVA film thus obtained.

For example, (1') a method in which a PVA-based film is dyed with a dichroic dye and then stretched, ([phase] after stretching a PVA-based film,
Any method may be used, such as dyeing with a dichroic dye, printing an O dichroic dye on a PVA film and then stretching it, or printing a dichroic dye on a PVA film after stretching it. .

To give a more specific example of method 0, )' VA film is immersed in a 1-4 thiboric acid aqueous solution (bath temperature 30-40°C), and then stretched 3-7 times in one direction. Furthermore, set this to 0
．． 05-0.5% dichroic dye aqueous solution (bath temperature 30-4
0°C) to adsorb the dye, then immersed at 80-100°C.
This is a method of drying and heat fixing at C.

The dichroic dye used in the polarizing film of the present invention is a modified P dye having one cationic group in the molecule.
It exists on the surface and/or inside of the VA film, and its content is not particularly limited, but it is usually 0.01 to 5% by weight, particularly preferably 0.01 to 5% by weight, relative to the PVA film. A range of 2 weights is suitable.

The polarizing film of the present invention obtained in this way can be used as is depending on the purpose, but it may be made into a polarizing plate with a retention film having excellent optical transparency and physical strength on one or both sides. You can also do it.

The invention will now be described with reference to several examples. Note that the light transmittance in the examples is the light transmittance of a single polarizing film or a polarizing plate.

In addition, the degree of polarization was calculated using the following formula.

In the above formula, Hll is the light transmittance of two polarizing films or polarizing plates stacked so that their stretching directions are parallel, and Hll is the light transmittance of two polarizing films or polarizing plates stacked so that their stretching directions are perpendicular. This is the light transmittance of the layers stacked so that

Example 1 Shoes containing 1 mole of cationic group in the molecule 4i degree 99
．． 0-r-le%, 4% aqueous solution (iD 20'CK off
Modified polyvinyl alcohol with a viscosity of 30 cp (Type B)
12 parts of glycerin and water were added to modified PVA (hereinafter abbreviated as modified PVA), and an aqueous solution with a moisture content of 85 parts by weight was prepared on a hot water bath.

This aqueous solution was discharged from the slit onto a roll having a surface temperature of 70°C and dried to obtain a PVA film having a thickness of 75 μm.

In addition, various mixtures of unmodified PVA with a degree of polymerization of 1750 and a degree of saponification of 99.9 mol and the above-mentioned modified PVA containing 1 mole of cationic groups in the molecule (mixing ratios are shown in Table 1). 12% glycerin/(undenatured PVA ten modified PV
A), and by adding water.

Aqueous solutions each having a water content of 85 kg were prepared on a hot water bath. These aqueous solutions were discharged from the slit onto a roll having a surface temperature of 70° C. and dried to obtain PVA-based films each having a thickness of 75 μm.

These PVA-based films were immersed in soft water at 20°C for 1 minute to swell, and then treated with Sumitomo Chemical's dichroic dye Dire.
ct Sky Blue 5 B was immersed for 4 minutes in a 30° C. staining solution (the dye concentration is shown in Table 1) dissolved in soft water 11. Continue washing in soft water at 20℃ for 1 minute,
P
Wipe off the water adhering to the surface of the VA film, and
3 minutes with 0℃ hot air.

The interlayer film was dried to produce a polarizing film. Table 1 shows the various performances of the polarizing film thus obtained.

Table 1 Comparative Example 1 A polarizing film was obtained according to the method of Example 1, using only unmodified PVA with a degree of polymerization of 1750 and a saponification i of 99.9 moles instead of the modified PVA of Example 1. Various performances of the obtained polarizing film are also shown in Table 1.

From the results in Table 1, it can be seen that the polarizing film of the present invention, which is characterized by having a dichroic dye on the surface and/or inside the PVA film made of modified PVA having a cationic group in its molecules, is made from unmodified PVA. It is clear that compared to other polarizing films, the dye concentration of the dyeing solution to obtain a constant light transmittance can be made extremely low, and there is no uneven dyeing, in other words, it is a polarizing film with excellent dyeing properties. It is. It is also clear that the degree of polarization is extremely excellent.0 As is clear from Table 1, the effect of using modified PVA having a cationic group in the molecule of the present invention is that the mixing ratio of modified PVA/unmodified PVA is can be sufficiently clearly exhibited at 1/99 or more.

Example 2 After applying urethane adhesive to both sides of the polarizing film made in Example 1, acetate film was attached to make a polarizing plate, and the light transmission after leaving it at 80°C x 9 (IR) L x 1000 hours Table 2 Comparative Example 2 A urethane adhesive was applied to both sides of the polarizing film prepared in Comparative Example 1, and then an acetate film was bonded to the film to obtain a polarizing plate. Regarding this polarizing plate, 80'CX 90'RHx
Table 2 also shows the results of measuring changes in light transmittance and degree of polarization after being left to stand for 1000 hours.

As is clear from the results in Table 2, the polarizing plate obtained using the polarizing film of the present invention shows almost no change in light transmittance and polarization degree over time when left for a long time at high temperature and high humidity.
It is extremely durable.

Patent applicant: RiRa Co., Ltd. Patent attorney, Honda (Volunteer to write procedural amendments) June 29, 1980 Commissioner of the Patent Office Shiga Gakudon 1, display of polarizing film 3, person making amendments Related: Patent applicant: 1621 Sakazu, Kurashiki City (108) Rira Shi Co., Ltd. Representative Director: Ueno et al. - 4, Agent: Kuraray Patent Department Column 6 of the detailed description of the invention in the specification, Contents of amendments (1) ) In page 18, line 16 of the specification, "the above-mentioned polyvinyl alcohol derivative" is corrected to "the above-mentioned unmodified polyvinyl alcohol polymer or polyvinyl μalcohol/l'derivative."

that's all

Claims (1)

[Scope of Claims] (1) A polarizing film characterized by having a dichroic dye on the surface and/or inside of a modified polyvinyl alcohol film containing a cationic group in the molecule. (2 ) Modified polyvinyl alcohol containing a cationic group in the molecule is a copolymerized unit selected from the following general formulas (Natsu), (II), (m), (■), (V), and (Vl). The polarizing film according to claim 1, which is a modified polyvinyl alcohol containing at least one type of polymerized unit. Al R
6 represents a hydrogen atom or a lower alkyl group (which may contain a substituent); X- represents an anion; Al; a group connecting the nitrogen atom of the amide group to the nitrogen atom in iB; ) (Here, R7, R8, R9, and R10 are a hydrogen atom, a lower alkyl group, or a phenyl group (which may contain a substituent).
, X- each mean an anion. ) R6 represents a hydrogen atom or a lower alkyl group (which may contain a substituent group), X- represents an anion, and D represents a group connecting the nitrogen atom and oxygen atom in B, respectively. ) 1l -(-CH2-C+(V) (Here, R11, R1!, R13, R14 are hydrogen atoms,
A lower alkyl group (which may contain an @ substituent) and X- each mean an anion. )