JPH0922036A - Polyurethane resin material for nonlinear optics - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an optical material having increased nonlinear susceptibility by incorporating a specified structural unit in the main chain. SOLUTION: This polyurethane resin material has a structure expressed by formula I. In formula I, X<1> -X<3> are bivalent org. groups Z<1> , Z<2> are such atomic groups that the product of the molecular polarizability β and the dipole moment μof the molecule expressed by formula II is >=50×10<-48> esu. As for the bivalent org. groups X<1> -X<3> , substd. or branched alkylene groups or alkylene groups containing ether type oxygen atoms can be used. If X<1> -X<3> are too long, Tg of the polymer decreases. Therefore, the number of atoms except hydrogen is preferably <=6. Thus, such a material that contains the dye having larger molecular polarizability β above described and that the dye skeleton part is included in a specified form in the polymer main chain has high performance and shows stable orientation.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a nonlinear optical material and a method for manufacturing the same. In particular, the present invention relates to a non-linear optical material that is a polymer material exhibiting a large non-linear optical effect and is effective as a light control element that can be used in an electro-optical light modulation element, a wavelength conversion element, and the like, and a manufacturing method thereof.

[0002]

2. Description of the Related Art Non-linear optical materials are widely used for conversion and control of light, particularly laser light, such as wavelength conversion of light, modulation of light by change in refractive index, switching and the like. This is understood as a phenomenon caused by the non-linear polarization of matter by an externally applied electromagnetic field. here,
When E is an electric field (light or electrostatic field) applied from the outside and P is the polarization of the substance induced by the electric field, P is expanded by E, which is represented by the following formula (I).

[0003]

[Equation 1] P = P ₀ + χ ⁽¹⁾ E + χ ⁽²⁾ EE + χ ⁽³⁾ EEE + ... (I)

This χ ⁽²⁾ is called the quadratic nonlinear susceptibility and χ ⁽³⁾ is called the third-order nonlinear susceptibility.
Y. R. "Principles of N."
online Optics ".

At present, KDP (KH ₂ PO ₄ ), LiNbO ₃ is actually used as a nonlinear optical material.
(Lithium niobate), KTP (KTiOPO ₄ ) and other oxide single crystals, and semiconductor materials such as GaAs are mainly used.
In recent years, π-electron conjugated organic compounds have attracted attention as this nonlinear optical material. This is because the nonlinear susceptibility is much higher than that of inorganic materials, and it is derived from electronic polarization. It depends on what is expected. In addition, it has a low dielectric constant, is more resistant to optical damage than lithium niobate, etc., the manufacturing method is easier for polymer materials than single crystal growth, and various functions are possible due to various molecular designs. There is a possibility of adding the above-mentioned reason as another reason why the organic material is expected as a nonlinear optical material. By utilizing the features of such organic compounds, it is possible to fabricate wavelength conversion elements such as second harmonic generation for low power lasers such as semiconductor lasers, and electro-optical modulation elements that are driven at low voltage and have high speed response. It is possible.

Various forms of organic materials have been investigated as actual organic materials as nonlinear optical materials. For organic compounds, nonlinear susceptibility is discussed in terms of the hyperpolarizability of the molecule.
When the electric field acting on the molecule is E and the dipole moment of the molecule induced by this is p, it is expressed by the following formula (II).

[0007]

## EQU00002 ## p = .mu. +. Alpha.E + .beta.EE + .gamma.EEE + ... (II)

Here, α is called a molecular polarizability, β and γ are called second-order and third-order molecular hyperpolarizabilities, respectively, and the nonlinear susceptibility of the molecular assembly is derived from these β and γ. As a second-order nonlinear optical material, an intramolecular charge-transfer material in which a molecule contains an electron-donating group and an electron-withdrawing group and is connected by a π-electron conjugated system is a secondary molecule. It has been shown that the hyperpolarizability (β) is large, and most of the organic compounds showing a large χ ⁽²⁾ known so far, as represented by methyl nitroaniline (MNA), Is a type of molecule.

However, the second-order nonlinear optical material has a limitation that its structure has no macroscopic inversion symmetry. That is, since χ ⁽²⁾ is a third-order tensor, β
大 き く⁽²⁾ becomes 0 when the aggregate has a crystal structure having inversion symmetry or is amorphous even if is large. Therefore, how to orient a molecule having a large β into a polar structure is a major issue in searching for a material.

In this organic nonlinear optical material, it is the most common practice to utilize the crystal structure,
The powder SHG method is a method for simply screening such a material. Heretofore, in order to obtain a crystal in which molecules are optimally arranged, several ideas for molecular design such as introduction of an optically active group, a skeleton having a small ground state dipole moment, and use of a hydrogen bond have been proposed.

However, the effect is not clear unless the crystal is finally obtained. Further, the crystal of the organic compound is a molecular crystal and is soft and poor in workability. Further, it is often desirable to process into a waveguide structure when it is put to practical use as a non-linear optical element. However, a thin film forming method, control of crystal orientation, and a method of partially changing the refractive index are very necessary for this. It's difficult. For this reason, despite the fact that a great number of organic crystals have been investigated for their potential as non-linear optical materials, there are currently only a few cases where elements have been processed into elements.

Another secondary organic non-linear optical material is a polymer material. This is because an acrylic polymer is doped with a large β molecule represented by Disperse Red 1 (N-ethyl-N-hydroxylethyl-4-amino-4′-nitroazobenzene) or a side chain of the polymer. It is represented by a dye bound to. (Note that in the present invention, even if the molecule has no color in the visible light region,
A molecule or an atomic group that exhibits a nonlinear optical effect is called a "dye" for convenience. ) It is known that polymer materials can be easily formed into thin films by coating and become optical waveguide materials that are optically excellent, but the film just coated is generally amorphous and χ ⁽²⁾ is 0. . To obtain χ ⁽²⁾ , a polymer film is heated to a temperature near the glass transition temperature (hereinafter, abbreviated as “Tg”) while applying an electric field, and a unit having a large β is aligned. The operation called poling, in which the material is allowed to cool to room temperature and then fixed in orientation after being allowed to stand, is most often used, and a material exhibiting an electro-optical effect comparable to that of lithium niobate is obtained. However, the biggest disadvantage of this operation is that the orientation is thermally relaxed, and χ ⁽²⁾ is gradually attenuated. Further, a dye having a large β that exhibits a non-linear optical effect by poling is diluted in a polymer matrix, and further cannot be perfectly oriented due to a disturbance due to temperature. For these reasons, the large nonlinear optical effect expected of organic compounds has not been obtained.

To increase χ ⁽²⁾ of a polymer material,
It is necessary to increase β of the dye contained in it. A molecule with a large β has a structure in which an electron-donating group and an electron-withdrawing group are conjugated with π electrons, and β is known to increase as the charge mobility in the molecule is increased. For this purpose, it is effective to extend the π-electron conjugation or to introduce a stronger electron donating group or electron withdrawing group.
However, the molecule with increased β in this way is
In general, it has a good flatness and an elongated structure, and also has a large dipole moment, so when it is present in a polymer at a high concentration, the interaction between molecules is large, and a transparent film cannot be obtained due to aggregation, or poling treatment. There is a tendency that the expected nonlinear optical characteristics cannot be obtained. for that reason,
Introducing a substituent such as a bulky alkyl group that alleviates intermolecular interaction into the dye molecule has been devised to satisfy the characteristics as a polymer for nonlinear optics. However, the introduction of a large alkyl group needs to increase the molecular weight of the dye and increase the content of the dye unit in the polymer.
Not preferred. Further, there is a drawback that the glass transition temperature of the polymer is lowered and the thermal stability of the nonlinear optical effect is lowered.

[0014]

As described above, in order to obtain a device with high characteristics, it is necessary to develop a nonlinear optical material having a high nonlinear susceptibility. Conventionally, such a nonlinear optical material has been provided. The current situation is that it has not been done. The present invention has been made in view of the above conventional circumstances, in which a dye having a large molecular hyperpolarizability β that can be used to obtain a material having a large nonlinear susceptibility is bonded to a polymer with a special structure. It is an object of the present invention to provide a non-linear optical material capable of significantly increasing the non-linear susceptibility obtained by poling and producing an element exhibiting higher performance than a conventional element.

[0015]

The present inventors have found that a material having a dye having a large β and having a dye skeleton part in a special form in the polymer main chain exhibits high performance, and The inventors have found that the orientation is also stable and have reached the present invention. That is, an object of the present invention is to provide a polyurethane resin material for nonlinear optics, which has a significantly increased nonlinear susceptibility, and an object of the invention is to provide a polyurethane resin material for nonlinear optics having a structure of the following general formula (1). More easily achieved.

[0016]

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(In the formula, X ¹ , X ² and X ³ are divalent organic groups, and Z ¹ and Z ² are

[0018]

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It represents an atomic group in which the product of the molecular hyperpolarizability β of the molecule represented by and the dipole moment μ is 50 × 10 ⁻⁴⁸ electrostatic units or more. ) A more preferable polyurethane resin material for a nonlinear optical material has a structural unit represented by the following general formula (2).

[0020]

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(Wherein X ¹ , X ² and X ³ are divalent organic groups, Y ¹ , Y ² , Y ³ and Y ⁴ each represent CH or N, D is an electron donating group, A represents an electron-withdrawing group,
Q ¹ and Q ² represent an optionally substituted aromatic ring or heterocycle. )

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION In the above general formulas (1) and (2),
Examples of the divalent organic group of X ¹ , X ² and X ³ include an alkylene group which may be substituted or branched, and those containing an etheric oxygen atom therein. If this part is too long, the Tg of the polymer will decrease, so
The number of atoms other than hydrogen is preferably 6 or less.

Examples of the electron-donating group of D include an alkyl group, an allyl group, an amino group which may be substituted with an acyl group, an alkoxy group having 6 or less carbon atoms, an allyloxy group, a thioether group, and the like. Particularly, an amino group substituted with an alkyl group having 6 or less carbon atoms is desirable. Also, A
Examples of the electron-withdrawing group include a nitro group, a cyano group, a dicyanovinyl group, a tricyanovinyl group, a halogen atom, a carbonyl group, a sulfone group, a perfluoroalkyl group, and the like, but particularly a nitro group, a cyano group, a dicyano group. A vinyl group and a tricyanovinyl group are desirable.

As Q ¹ and Q ² , benzene ring, pyridine ring, thiophene ring, thiazole ring, thiadiazole ring,
A furan ring, an oxazole ring, an oxadiazole ring, a naphthalene ring, an anthracene ring, etc. are mentioned. The hydrogen atoms of these rings may be substituted with an alkyl group, an alkoxy group or the like, and a part of the hydrogen atoms of this substituent may be substituted with a fluorine atom or a hydroxyl group.

The molecular weight of the polyurethane resin of the present invention may be any as long as it does not hinder the molding process, and normally the number average molecular weight is preferably about 2,000 to 100,000. The polyurethane resin material for nonlinear optics of the present invention is
And the third-order nonlinear optical material, it is particularly excellent as the second-order nonlinear optical material. Therefore, the non-linear polyurethane resin material of the general formula (1) or (2) is heated. However, it is preferable to apply an electric field for orientation, and to fix it for use.

More preferable examples of the polyurethane resin material for nonlinear optics oriented by an electric field are compounds having two or more isocyanate groups in the polyurethane resin material for nonlinear optics represented by the general formula (1) or (2). Are mixed and fixed by cross-linking by heat treatment before, after or simultaneously with orientation by applying an electric field. The introduction of the dye having a large hyperpolarizability into the polymer skeleton has an effect of preventing aggregation between adjacent molecules by the polymer main chain. This is more effective than introducing a bulky group to alleviate the intermolecular interaction of the dye, and effectively acts even at a high concentration.

There are several methods for obtaining the hyperpolarizability β. Method to measure SHG by applying electric field to solution (D
CDHG or EFISH), a method of measuring hyper-Rayleigh scattering of a solution, a method of dissolving a molecule in a polymer and poling it with a constant electric field, and obtaining it from the measurement of this SHG or electro-optical effect are known. Generally, β depends on the frequency of the electric field concerned (light or an electric field applied from the outside). It is known that β obtained by different measurement methods can be converted to each other by using the dispersion relation of the two-level model, and they match well with the values obtained by experiments. Furthermore, in the limit of extrapolating the frequency to 0, all χ ⁽²⁾ and β converge. Β in the text indicates a value extrapolated to this frequency 0.

The present invention will be specifically described below with reference to examples. The material of the general formula (1) or (2) can be synthesized by reacting a diol compound of a corresponding dye with a diisocyanate compound. The molecular structure of the diol compound of the dye corresponding to the material of the general formula (1) or (2) is as shown below.

[0029]

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[0030]

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Specific examples of such a diol compound include the following.

[0032]

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[0033]

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[0034]

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[0035]

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[0036]

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[0037]

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These compounds may be used alone or in combination of two or more. Further, in order to control the dye concentration or introduce another function, other compounds having two or more hydroxyl groups or amino groups may be mixed and used. As such a low molecular weight compound, a polyol having a number average molecular weight of 300 to 5000 or a molecular weight of 500 is used.
The following short chain diols or short chain diamines can be utilized.

Examples of such polyols include those usually used in polyurethane production, and examples thereof include polyether diol, polyester diol, polyether ester diol, polyolefin polyol and a mixture of two or more kinds thereof. As the polyether diol, those obtained by homopolymerizing or copolymerizing alkylene oxide, for example, polyethylene glycol, polypropylene glycol, polyethylene-
Propylene glycol, polytetramethylene ether glycol, polyhexamethylene ether glycol, polyoctamethylene ether glycol and their 2
Mixtures of more than one species. Polyester diols include dicarboxylic acids (terephthalic acid, succinic acid, glutaric acid, adipic acid, sebacic acid, fumaric acid, maleic acid, phthalic acid, etc.) or their anhydrides and glycols (ethylene glycol, diethylene glycol, triethylene glycol, propylene). Glycol, dipropylene glycol, tripropylene glycol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 3-methyl-
1,5-pentanediol, neopentyl glycol,
2-methyl-1,3-propanediol, 2-methyl-
2-propyl-1,3-propanediol, 2-butyl-2-ethyl-1,3-propanediol, 1,5-pentanediol, 1,6-hexanediol, 2-methyl-2,4-pentanediol , 2,2,4-trimethyl-1,3-pentanediol, 2-ethyl-1,3-
Hexanediol, 2,5-dimethyl-2,5-hexanediol, 1,8-octamethylene glycol, 2-
Methyl-1,8-octamethylene glycol, 1,9-
Alicyclic glycols such as bishydroxymethylcyclohexane; xylylene glycol, aromatic glycols such as bis-hydroxyethoxy benzene; aliphatic glycols such as nonanediol alkyldialkanolamine such C ₁ ~ _{1 8} alkyl diethanolamine and the like) and the Those obtained by polycondensation, for example, polyethylene adipate, polybutylene adipate, polyhexamethylene adipate,
Examples thereof include polyethylene / propylene adipate and the like, or polylactone diols obtained by using the above diols as an initiator, for example, polycaprolactone diol, polymethylvalerolactone, and a mixture of two or more thereof. The polyether ester diol is obtained by reacting a mixture of an ether group-containing diol or another glycol with the above dicarboxylic acid or an anhydride thereof, or by reacting a polyester glycol with an alkylene oxide, for example, a poly (ether oxide). (Polytetramethylene ether) adipate may be mentioned. Examples of the polyolefin polyol include hydrogenated polybutadiene polyol and hydrogenated polyisoprene polyol.

Besides, polycarbonate diols and polybutadiene polyols can also be used. Examples of the short chain diol include ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, polytetramethylene glycol, 1,5-pentanediol, 1,6-hexanediol, 3-methyl-
1,5-pentanediol, neopentyl glycol,
2-ethyl-1,3-hexane glycol, 2,2,4
-Trimethyl-1,3-pentanediol, 3,3-dimethylolheptane, 1,9-nonanediol, 2-methyl-1,8-octanediol, cyclohexanedimethanol, bishydroxyethoxybenzene, N-alkyldiethanolamine, Bisphenol A etc. are mentioned. Examples of the short-chain diamine include ethylenediamine, propylenediamine, hydrazine, aliphatic diamine such as 2,4,4-trimethylhexamethylenediamine, piperazine, cyclohexanediamine, mentenediamine, isophoronediamine, 4,4′-methylenebis (cyclohexylamine). ) Etc. alicyclic diamine etc. are mentioned. Further, polyfunctional alcohols such as trimethylolpropane and glycerin can be used in combination. It is also possible to partially substitute monoamine or monoalcohol. As monoamine, methylamine, ethylamine,
Butylamine, dibutylamine, ethanolamine, diethanolamine and the like can be mentioned. Examples of the monoalcohol include methanol, ethanol, propanol, butanol, hexanol and the like.

Further, N, N-dihydroxylethyl-4-amino-4'-nitroazobenzene, N, N-
Mention may also be made of diols such as dihydroxylethyl-4-amino-4′-nitrostilbene, diol compounds containing dyes used for other nonlinear optics, such as.

These diols can be reacted with a compound having two or more isocyanate groups to synthesize polyurethane. Examples of such polyisocyanate compounds include paraphenylene diisocyanate,
2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 4,4′-diphenylmethane diisocyanate, naphthalene-1,5-diisocyanate,
Trizine diisocyanate, 3,3′-dimethyl-4,
4'-diisocyanatobiphenyl, 3,3'-dimethoxy-4,4'-diisocyanatobiphenyl, 3,3'-
Aromatic diisocyanates such as dimethyl-4,4'-diphenylmethane diisocyanate, hexamethylene diisocyanate, lysine methyl ester diisocyanate,
Aliphatic diisocyanates such as 2,4,4-trimethylhexamethylene diisocyanate and dimer acid diisocyanate, isophorone diisocyanate, 4,4′-methylenebis (cyclohexyl isocyanate), ω, ω ′
Alicyclic diisocyanate such as diisocyanate dimethylcyclohexane, xylylene diisocyanate, α,
Aliphatic diisocyanates having an aromatic ring such as α, α ′, α′-tetramethylxylylene diisocyanate and the like can be mentioned. Of these, diisocyanates having an aromatic ring are preferable. These may be used alone or in combination of two or more.

The polyurethane of the present invention is produced by a known method such as a one-shot method and a prepolymerization method. As a solvent when producing polyurethane,
Usually, ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclopentanone, cyclohexanone and isophorone, esters such as ethyl acetate, butyl acetate and cellosolve acetate, hydrocarbons such as benzene, toluene, xylene and hexane, diacetone alcohol,
Some alcohols such as isopropanol, secondary butanol and tertiary butanol, and methylene chloride, tetrahydrofuran, dimethylformamide and the like are used.

The polymerization can be carried out by mixing a compound having a hydroxyl group and a compound having an isocyanate group in a solvent. At this time, although a catalyst can be used, the polymerization can be performed by heating without using it. As the catalyst, a usual urethanization reaction catalyst is used. For example,
Examples thereof include tin-based compounds such as dibutyltin dilaurate, dioctyltin dilaurate, dibutyltin dioctoate and stannas octoate, iron-based compounds such as iron acetylacetonate and ferric chloride, and tertiary amine-based compounds such as triethylamine and triethylenediamine.

Next, a method of imparting a second-order nonlinear optical effect to the obtained polymer material will be described. The polymer material of the present invention can be used as a third-order nonlinear optical material, but is preferably used as a second-order nonlinear optical material. As a third-order nonlinear optical material, a nonlinear optical effect appears even in a bulk or film form, but when used as a second-order nonlinear optical material, it has a polar structure that does not have inversion symmetry in the bulk by some method. There is a need to. Several methods have been proposed for this.

The most commonly performed method is to heat the polymer material to near the Tg so that the dye can move in the polymer and to apply an electric field to the interaction between the dipole moment of the dye and the electric field. This is a method called poling, in which the dye is oriented in (1) and then cooled to fix the orientation. As a method of applying a voltage to the sample, there are a method of applying a voltage between electrodes provided on the sample and a method of applying a voltage by corona charging. The polymer material of the present invention has a high T
If it has g, it has sufficient heat resistance, but as a method of further improving heat resistance, it is also possible to fix the orientation of the dye by crosslinking the polymer during or after poling to cure the polymer. When polyurethane or polyurea is mixed with a compound containing two or more isocyanates and heated, a crosslinked polymer is formed and it is effective in suppressing relaxation of orientation. Examples of such polyisocyanate compounds include paraphenylene diisocyanate,
2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 4,4′-diphenylmethane diisocyanate, naphthalene-1,5-diisocyanate,
Trizine diisocyanate, 3,3′-dimethyl-4,
4'-diisocyanatobiphenyl, 3,3'-dimethoxy-4,4'-diisocyanatobiphenyl, 3,3'-
Aromatic diisocyanates such as dimethyl-4,4'-diphenylmethane diisocyanate, hexamethylene diisocyanate, lysine methyl ester diisocyanate,
Aliphatic diisocyanates such as 2,4,4-trimethylhexamethylene diisocyanate and dimer acid diisocyanate, isophorone diisocyanate, 4,4′-methylenebis (cyclohexyl isocyanate), ω, ω ′
Alicyclic diisocyanate such as diisocyanate dimethylcyclohexane, xylylene diisocyanate, α,
Aliphatic diisocyanates having an aromatic ring such as α, α ′, α′-tetramethylxylylene diisocyanate, 1,
6,11-undecane triisocyanate, 1,8-diisocyanate-4-isocyanate octane, 1,
3,6-hexamethylene triisocyanate, bicycloheptane triisocyanate, tris (isocyanate phenyl) methane, tris (isocyanate phenyl)
Examples thereof include polyisocyanates such as thiophosphate, trimers thereof, water adducts thereof, and polyol adducts thereof. As a method for producing isocyanurate by trimerization of polyisocyanate, the above-mentioned polyisocyanate is prepared by using a suitable trimerization catalyst such as tertiary amines, phosphinic acid, alkoxides, metal oxides and carboxylates. After partial trimerization of the group and stopping the trimerization by adding a catalyst poison,
There is a method in which unreacted polyisocyanate is removed by solvent extraction, thin film distillation or the like to obtain the desired isocyanurate group-containing polyisocyanate. As a method for producing a water adduct of polyisocyanate, 1 mol of water is added to 70 to 20
A method of reacting with at least 3 mol or more of the polyisocyanate at a temperature of 0 ° C can be mentioned. The polyol adduct is the polyisocyanate and glycerin, trimethylolpropane, trimethylolethane, 1, 2, 6-
Hexanetriol, 1,2,4-butanetriol,
It can be obtained by reacting a polyol such as erythritol, sorbitol, pentaerythritol, and dipentaerythritol under conditions of excess isocyanate. The addition reaction follows a known method in the production of polyurethane, and an ordinary urethanization reaction catalyst is used as the catalyst. Various glycols can be used as the polyol, and a part of them can be replaced with monoalcohol, diamine, monoamine, or the like.

These may be used alone or in combination of two or more. Further, from the viewpoint of heat resistance, it is preferable that the isocyanate group is directly bonded to the aromatic ring. Further, those having a trifunctional or higher functional isocyanate in the molecule are preferable to those having a bifunctional one. Further, if a photoreactive group is introduced into the side chain or main chain of the polymer of the present invention, crosslinking by light irradiation is possible.

These polyisocyanate compounds are contained in an amount of 1 to 60 parts, preferably 5 to 60 parts, based on 1 part of the polymer of the present invention.
Add 40 parts. When this is heated at 100 ° C to 250 ° C, the crosslinking reaction proceeds. The degree of crosslinking progress depends on the absorption of NCO in the IR spectrum and tetrahydrofuran (hereinafter "THF")
It is possible to monitor the easiness of being invaded by an organic solvent such as, and to monitor the easiness of movement of dye molecules at the same time as the poling treatment by measuring the electro-optical effect described later. For the monitoring method by measuring the electro-optic effect, see S. Aramaki et al., Jpn. J. Appl. Phys. Volume 33 575
This is described in detail in Section 9 (1994).

For the polling operation, see D. M. Bu
Chemical Review by rland et al.
94, item 31 (1994) has a detailed explanation, and it can be carried out according to a known method as described therein. The polymer material of the present invention exhibits a very large second-order nonlinear optical effect by forming a structure having no such inversion symmetry. The second-order nonlinear optical effect is wavelength conversion and the first-order electro-optical effect (Pockels effect).
However, since the polymer of the present invention has strong absorption in the visible region, its application to light control using the Pockels effect in light in the near infrared region is promising.

As a specific application example, since the refractive index is changed by the electric field, the phase control of light can be mentioned. this is,
Information can be added by modulating the phase of light, and can be used for optical communication and optical information processing. Also, this change in phase is
If an interferometer is used, it is possible to change the intensity of light, and it can be applied to intensity modulation. Such a modulation element can be made in bulk, but it is desirable to construct an optical waveguide element by taking advantage of the characteristic of a polymer material that it can be easily made into a film. Further, if the material of the present invention is applied to the directional coupler, an optical switch element can be constructed. For more specific examples of optical waveguide devices, see the Japan Society of Applied Physics
There is a detailed explanation in "Optical Integrated Circuits: Fundamentals and Applications" (Asakura Shoten), and all of the optical waveguide elements utilizing the electro-optic effect can be realized by the polymer material of the present invention.

Further, since the polymer material of the present invention has extremely high performance, even if the polymer material is not an optical waveguide that propagates in the film to control the phase, the light perpendicularly incident on the film is transmitted through the film. A method of changing the phase at that time can also be used. In such a thing, in the phase of light,
It is possible to apply different modulation depending on the place, and it can be used as a spatial modulation element. Such a thing is useful for optical interconnection for connecting boards by light, image processing, and the like. Furthermore, by imparting photoconductivity to the polymer material of the present invention, the photorefractive effect can be efficiently exhibited.

The electro-optical effect measuring method used in the present invention is basically based on C.I. C. Teng et al., Appl. P
hys. Lett. 56, p1734 (1990). Figure 1 shows the layout of the experimental equipment.
Shown in In FIG. 1, 1 is a laser, 2 is a polarizer, and 3
Is a Babinet Soleil compensator, 4 is an analyzer, 5 is a photodiode, 6 is a lock-in amplifier, 7 is a power supply, 8 is a sample, 9 is a heater, 10 is an electrode, and 11 is a temperature controller. Here, the difference from Teng et al. Is in the sample (8).
Is fixed to the heat block, the temperature can be controlled by the temperature controller, and the applied voltage can be offset from alternating current to direct current. In the paper of Teng et al., The derivation of the phase difference between p-polarized light and s-polarized light is inadequate.

[0053]

(Equation 3)

[0054]

EXAMPLES The present invention will be described in more detail below with reference to examples. Example 1 Synthesis of 2,5-di (acetoxyethoxy) nitrobenzene 11 g of p-dihydroxyethoxybenzene was mixed with 180 g of acetic acid.
It was dissolved in ml, 17.0 g of acetic anhydride was added dropwise, and the mixture was refluxed for 2 hours. While cooling this solution to below 20 ° C, 60%
What dissolved 5.78 g of nitric acid in 20 ml of acetic acid was dripped. After stirring for 2 hours, the mixture was poured into water and extracted twice with dichloromethane. The separated organic layer was washed with water, an aqueous solution of sodium hydrogen carbonate and an aqueous solution of sodium chloride, and then dried over anhydrous sodium sulfate. The solution is concentrated and dried to give 1 yellow solid.
0.4 g was obtained. The mass spectrum confirmed the molecular ion peak of 2,5-di (acetoxyethoxy) nitrobenzene.

Synthesis of 2,5-di (acetoxyethoxy) aniline 2,5-di (acetoxyethoxy) nitrobenzene 4.
Dissolve 4 g in 100 ml of ethanol by heating,
% Of palladium carbon was added, and catalytic reduction was performed with hydrogen gas. The reaction was stopped when 0.9 liter of the theoretical amount of hydrogen had been absorbed, the catalyst was filtered off, and the solvent was concentrated to obtain 8.1 g of a white powder.

Synthesis of aminonitroazobenzene derivative 1.4 g of nitroaniline was dissolved in 5 ml of hydrochloric acid and 13 ml of water, and sodium nitrite 0.8 was added while cooling to 5 ° C or lower.
What melt | dissolved g in 4 ml of water was dripped, and it stirred for 3 hours. This reaction solution was added to 2,5-di (acetoxyethoxy)
Aniline (2.0 g) dissolved in methanol (20 ml) was added dropwise at 0 ° C., and the mixture was stirred for 3 hours. The obtained solid was filtered to obtain 3.0 g of a red powder represented by the following structural formula.

[0057]

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Synthesis of Disazo Dye 7.9 g of the aminonitroazobenzene derivative obtained as above was added to 300 ml of dimethylformamide at 60 ° C.
It was dissolved in, and 23 ml of hydrochloric acid and 55 ml of water were added thereto at room temperature. 0.16 g of sodium nitrite at room temperature in 3 ml of water
Was added, and the mixture was gradually heated and stirred at 40 ° C. for 1 hour. This solution was mixed with 2.7 g of diethylaniline and 80 ml of methanol.
It was dripped at 10 to 20 ° C. and stirred for 3 hours. The produced solid was filtered, and the filtrate was combined with the solid obtained by concentrating what was extracted with dichloromethane and purified by column chromatography on dichloromethane / silica gel to obtain 1.75 g of a purple powder.

1.75 g of this product was dissolved in 50 ml of tetrahydrofuran, cooled to 10 ° C., 0.57 g of potassium hydroxide dissolved in 30 ml of methanol was added dropwise, and the mixture was stirred for 10 minutes and neutralized with hydrochloric acid. And poured into water. The generated precipitate was separated by filtration and dried to obtain 1.27 g of purple powder. Tetrahydrofuran / n-hexane =
Purification by column chromatography using silica gel with a mixed solvent of 5/3 gave 0.71 g of a purple powder. By confirming the molecular ion peak in the mass spectrum, it was confirmed that the purple powder was a disazo dye represented by the following structural formula.

[0060]

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Polyurethane synthesis Molecular sieve dried dimethylformamide 2
In 0 ml, 0.6 g of dihydroxy compound of disazo dye, poly-3-methyl-1,5-pentylene terephthalate (number average molecular weight 500, manufactured by Kuraray Co., Ltd., hereinafter referred to as "PMP").
T500 ") and neopentyl glycol (0.106 g) are dissolved and heated at 50 ° C for 4,
4'-diphenylmethane diisocyanate (hereinafter MDI
Abbreviated) 0.793 g was added, and the mixture was heated and stirred at 80 ° C. for 7 hours. The precipitate obtained by pouring into methanol is filtered,
Reprecipitation with tetrahydrofuran / methanol was repeated twice for purification, and 1.2 g of a black-purple powder was obtained.

・ Analysis result The IR spectrum of the obtained polyurethane film is shown in FIG. From the measurement of gel permeation chromatography, the molecular weight is Mn = 4700, Mw = 7400.
(In terms of polystyrene), and it was found that the monomer did not remain. Further, by comparing the oscillator strength in the visible light absorption band of the absorption spectrum of the dimethylformamide solution of polyurethane with the dihydroxy form of the disazo dye, it was found that the disazo dye was contained in the polyurethane at a concentration of 29 wt%. .

Reference Experiment μβ (product of dipole moment μ and hyperpolarizability β) of the following dye was measured by Pockels effect using a laser of 1.31 μm.

[0064]

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The above dye is a compound similar to the dye used in Example 1, and μβ of the above dye is considered to be almost equal to the value of the dye used in Example 1. The value determined by measurement was 1370 × 10 ⁻⁴⁸ electrostatic units. The absorption maximum (about 550 nm) of this molecule and the value extrapolated to the frequency 0 using the dispersion equation of the two-level model are 985 × 10 ⁻⁴⁸ electrostatic units.

Example 2 Synthesis of N, N-diethyl-2,5-di (acetoxyethoxy) aniline 50 ml of N-methylpyrrolidone was supplemented with 2,5-di (acetoxyethoxy) aniline as an intermediate of Example 1. 4.0
g, potassium carbonate 2.2 g, methyl iodide 4.1 g
Mix and heat at 50-60 ° C. for 2 hours. The reaction solution was poured into water and extracted 3 times with dichloromethane. The extract was washed twice with water, the organic layer was dried over anhydrous sodium sulfate and concentrated. It was used for the next diazo coupling while containing N-methylpyrrolidone.

・ Synthesis of monoazo dye 1.8 g of nitroaniline was dissolved in 7 ml of hydrochloric acid and 17 ml of water, and sodium nitrite 1.0 was added while cooling to 5 ° C. or lower.
What melt | dissolved g in 5 ml of water was dripped, and it stirred for 3 hours. This reaction solution was added dropwise to a solution prepared by dissolving the concentrated solution of the reaction solution of N, N-diethyl-2,5-di (acetoxyethoxy) aniline in 30 ml of methanol at 0 ° C., and stirred for 3 hours. The obtained solid was filtered and recrystallized from ethanol to obtain 3.5 g of red powder. this,
Methanol 10.4 ml and potassium hydroxide 1.35 g were mixed and stirred at 10 ° C. for 15 minutes. 20 ml of water on this
It was added, neutralized with hydrochloric acid, and extracted with THF. After concentrating the extract, the obtained powder was recrystallized from a mixed solvent of ethanol / THF = 2/1 to obtain a monoazo dye (red powder) represented by the following structural formula.

[0068]

[Chemical 21]

Polyurethane synthesis Molecular sieve dried dimethylformamide 2
In 0 ml, 0.5 g of the dihydroxy derivative of azobenzene obtained above, 0.391 g of PMPT500, and 0.083 g of neopentyl glycol were dissolved, and 0.693 g of MDI was added at 50 ° C. while heating. 90
The mixture was heated and stirred at 7 ° C for 7 hours. The reaction solution was poured into methanol, and the generated precipitate was reprecipitated twice with tetrahydrofuran / methanol and once with tetrahydrofuran / n-hexane to obtain 0.6 g of a dark red powder.

The IR spectrum of the obtained polyurethane film is shown in FIG. From the measurement of gel permeation chromatography, the molecular weight is Mn = 5600, Mw
= 11400 (in terms of polystyrene), and it was found that the monomer did not remain.

Example 3 Polymer Poling 0.2 g of the polymer prepared in Example 1 was added to cyclopentano.
Dissolved in 1 g of ITO, and this is ITO glass (100 ohm)
Was spin coated on top of. Dry at 130 ° C for 30 minutes,
A film having a thickness of 1.6 μm was formed. Further to this
Gold was vapor-deposited to 100 nm. Mark the voltage of 80V between the electrodes
Add (electric field 0.5 MV / cm) and heat to 110 ° C for 5
After heating for a minute, cool to room temperature while applying voltage, and
The pressure was removed and poling was performed. Of this film
Electro-optic effect (Pockels coefficient r ₃₃) 1.31 μm
When measured using a semiconductor laser, it is 4.4 pm / V
there were. Compared with Comparative Example 1 described later, the dye concentration is
Even if the polling electric field is the same,
Since the Kels coefficient was shown, the polymer of the present invention was
The intermolecular interaction is relaxed to show the large performance of the molecule.
It is suggested that

Example 4 Test of Light Propagation Characteristics A cyclopentanone solution of the polymer of Example 1 was spin-coated on a quartz substrate to prepare a film of 2 to 2.5 μm. Continuous light of a 1.32 μm Nd: YAG laser was combined with this using a strontium titanate prism by the prism coupling method, and the light propagating through the film was observed using an infrared camera. . I plotted the brightness of the observed optical path in the distance traveled, but
No light attenuation was observed over cm. From this measurement, it was found that the film of this polymer had an attenuation constant at 1.32 μm of less than 1 dB / cm, and was found to be excellent as a material for an optical waveguide.

Example 5 Fixation by Crosslinking Reaction 0.2 g of the polymer of Example 1 and 0.36 g of 2,4-tolylene diisocyanate trimer (50% solution) were dissolved in 1 g of cyclopentanone. This is ITO glass (10
0 ohm) was spin coated. After heat treatment at 130 ° C. for 40 minutes and further at 190 ° C. for 30 minutes, a film having a thickness of 2.7 μm was formed. 100n more money on this
m was vapor-deposited. A voltage of 135 V was applied between the electrodes (electric field 0.5 MV / cm), heated to 190 ° C. and heated for 30 minutes, then cooled to room temperature with the voltage applied, and the voltage was removed to perform a poling treatment. In the IR absorption spectrum, the absorption of the isocyanate group derived from the 2,4-tolylene diisocyanate trimer disappeared, and the absorption by the organic solvent did not occur at all, indicating that the crosslinking reaction proceeded. The electro-optic effect (Pockels coefficient r ₃₃ ) of this film was 3.5 pm / V when measured using a 1.31 μm semiconductor laser. This value is a reasonable value considering that the dye concentration was lowered by the addition of the cross-linking agent, and shows that the cross-linking does not hinder the orientation of the dye. This polarized polymer is
No decrease in the Pockels coefficient was observed even after heating at 1.5 ° C. for 1.5 hours. When stored in an incubator at 85 ° C., it was found that after the initial attenuation of about 10% was observed, no attenuation was observed even after 1000 hours, and the thermal stability of polarization was excellent.

Example 6 Immobilization by cross-linking reaction 0.2 g of the polymer of Example 1 and tris (isocyanatophenyl) thiophosphate (Desmodur RF)
E, manufactured by Bayer, 27% solution) (0.3 g) was dissolved in 1 g of cyclopentanone. This was spin coated on ITO glass (100 ohm). Heat treatment was performed at 130 ° C. for 40 minutes and further at 190 ° C. for 30 minutes to form a film having a thickness of 2 to 2.5 μm. 100nm of gold on this
Evaporated. A voltage such that an electric field of 0.5 MV / cm was applied between the electrodes, and the mixture was heated to 190 ° C. and heated for 30 minutes, then cooled to room temperature with the voltage applied, and the voltage was removed to perform poling treatment. In the IR absorption spectrum, the absorption of the isocyanate group disappeared, and the compound was not affected by the organic solvent at all, indicating that the crosslinking reaction proceeded. The electro-optic effect (Pockels coefficient r ₃₃ ) of this film was 3.0 pm / V when measured using a 1.31 μm semiconductor laser. This polarized polymer
Even after heating at 150 ° C. for 1.5 hours, no attenuation of the Pockels coefficient was observed. When stored in an incubator at 85 ° C., at 85 ° C., an initial attenuation of about 10% was observed, and no attenuation was observed even after 1000 hours, indicating that the thermal stability of polarization was excellent. .

Comparative Example 1 Synthesis of Dye Monomer 5 g of N, N-dihydroxyethylaniline was dissolved in methanol and cooled to 10 ° C. or lower. To this, Fast
A solution prepared by dissolving 11.5 g of Black K salt (manufactured by Tokyo Kasei Co., Ltd.) in a mixed solvent of 50 ml of methanol and 20 ml of water was added dropwise while keeping the temperature at 10 ° C or lower. The reaction solution was stirred for 4 hours, filtered, and washed with water. The obtained crude crystals were dissolved in THF, n-hexane was added and reprecipitated, and the obtained crystals were used for polymerization. As for the structure, a molecular ion peak (M + = 494) in a mass spectrum was detected, and it was confirmed that the dye was a diol molecule represented by the following structural formula.

[0076]

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Polymerization Dimethylformamide 3 dried over molecular sieves
1 ml of the dye diol molecule obtained as described above was added to 0 ml.
0 g, 0.821 g of PMPT500 and 0.174 g of neopentyl glycol were dissolved, 1.534 g of MDI was added at 50 ° C. with heating, and the mixture was heated with stirring at 80 to 90 ° C. for 8 hours. The reaction solution was poured into methanol, and the formed precipitate was reprecipitated 3 times with tetrahydrofuran / methanol to obtain 2.13 g of black-purple powder.

Analysis results The IR spectrum of the obtained polyurethane film is shown in FIG. From the measurement of gel permeation chromatography, it was found that the molecular weight was Mn = 4800 and Mw = 8600, and the monomer did not remain. Also,
Comparing the oscillator strength of the visible light absorption band of the absorption spectrum of the dimethylformamide solution of polyurethane with the dihydroxy form of the disazo dye, it was found that the disazo dye was contained in the polyurethane at a concentration of 26 wt%.

Poling 0.2 g of the polymer synthesized as described above was dissolved in 1 g of cyclopentanone, and this was mixed with ITO glass (100 ohm).
Was spin coated on top of. Dry at 130 ° C for 30 minutes,
A film having a thickness of 1.6 μm was formed. Gold was further vapor-deposited thereon to a thickness of 100 nm. A voltage of 80 V is applied between the electrodes (electric field 0.5 MV / cm) and heated to 110 ° C. for 5
After heating for a minute, the device was cooled to room temperature while applying a voltage, the voltage was removed, and a poling treatment was performed. The electro-optical effect (Pockels coefficient r33) of this film is 1.31 μm
2.5 pm / V when measured with the semiconductor laser of
Met. The dye concentration and poling conditions of Comparative Example 1 are almost the same as those of Example 3, but the electro-optical effect is smaller than that of the present invention. This is presumed to be because the interaction between molecules is large due to the presence of the dye in the polymer side chain, and the molecules cannot be independently oriented, so that the inherent nonlinear optical effect of the dye cannot be utilized.

[0080]

According to the present invention, a high performance polyurethane resin material for nonlinear optics is provided, and by using this, a nonlinear optical element having high efficiency and excellent thermal stability can be manufactured.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an apparatus used for measuring an electro-optical effect in the present invention.

FIG. 2 is an infrared absorption spectrum of a film of the polymer material of Example 1 formed on a NaCl plate.

FIG. 3 is an infrared absorption spectrum of a film of the polymer material of Example 2 formed on a NaCl plate.

FIG. 4 is an infrared absorption spectrum of a film of the polymer material of Comparative Example 1 formed on a NaCl plate.

[Explanation of symbols]

 1 Laser 2 Polarizer 3 Babinet Soleil Compensator 4 Analyzer 5 Photodiode 6 Lock-in Amplifier 7 Power Supply 8 Sample 9 Heater 10 Electrode (ITO and Gold) 11 Temperature Controller

Claims (5)

[Claims] 1. A polyurethane resin material for nonlinear optics having a structural unit represented by the following general formula (1) in the main chain. Embedded image (In the formula, X ¹ , X ² and X ³ are divalent organic groups, and Z ¹ and Z
² is the following Represents an atomic group in which the product of the molecular hyperpolarizability of the molecule and the dipole moment is 50 × 10 ⁻⁴⁸ electrostatic units or more. ) 2. A polyurethane resin material for nonlinear optics, which has a structural unit represented by the following general formula (2) in the main chain. Embedded image (In the formula, X ¹ , X ² and X ³ are divalent organic groups, and Y ¹ and Y
² , Y ³ and Y ⁴ each represent CH or N, D represents an electron-donating group, A represents an electron-withdrawing group, and Q ¹ and Q ² represent an optionally substituted aromatic ring or heterocycle. . ) 3. A non-linear optical material obtained by mixing the polyurethane resin material for non-linear optics according to claim 1 or 2 with a compound having two or more isocyanate groups, and crosslinking and fixing the mixture by heat treatment. 4. A method for producing a polyurethane by polymerizing a diisocyanate component and a diol component, wherein a diol component represented by the following general formula (3): (In the formula, X ¹ and X ² are divalent organic groups, and Z ¹ and Z ² are Represents an atomic group in which the product of the molecular hyperpolarizability of the molecule and the dipole moment is 50 × 10 ⁻⁴⁸ electrostatic units or more. )
A method for producing a polyurethane resin for non-linear optics, which comprises using a diol component containing a diol represented by: 5. A method for producing a polyurethane by polymerizing a diisocyanate component and a diol component, wherein the diol component is represented by the following general formula (4): (In the formula, X ¹ and X ² are divalent organic groups, and Y ¹ , Y ² and Y
³ , Y ⁴ each represent CH or N, D represents an electron-donating group, A represents an electron-withdrawing group, and Q ¹ and Q ² represent an optionally substituted aromatic ring or heterocycle. The manufacturing method of the polyurethane resin for non-linear optics characterized by using the diol component containing the diol represented by these.