JPH03275725A - Production of photoconductive polymer - Google Patents

Abstract

PURPOSE:To inexpensively obtain the title polymer useful as a photosensitive layer of electrophotographic photoreceptor of light printer, having high photosensitivity and crystallizability, by using a carboxylic acid prepared by reacting a diamine compound with a tetracarboxylic acid in a specific ratio. CONSTITUTION:A compound shown by formula I {A is group shown by formula II [Xi is (substituted) aromatic group; Yi is O, S, Se, Te or group shown by formula III; n>=1; i is 1-n]} and a compound shown by formula IV (Z is group containing aromatic group) in a blending molar ratio of diamine to dicarboxylic acid of 1:1+M) (M>0) are subjected to condensation reaction to give a polyamic acid, which is applied to a substrate, then immersed in a solution (preferably <=50wt.% pyridine is added) containing acetic anhydride and heat treated to give the objective polymer.

Description

[Detailed Description of the Invention] Industrial Field of Application The present invention relates to the photosensitive layer of an electrophotographic photoreceptor used in an optical printer or the like, or the photoconductive layer of a spatial light modulation element using liquid crystal. Conventional technologyThe development of organic materials with photoconductivity has become popular in recent years as photoreceptor materials for electrophotography.Polybaraphenylene sulfide (hereinafter abbreviated as PPS) is a material with high carrier transport ability. ) was proposed (Unexamined Japanese Patent Publication No. 1983)
-164556). PPS is an insulating material with excellent heat resistance.We found that heat treatment in oxygen significantly improves carrier transport ability (35th Japan Society of Applied Physics Joint Conference Proceedings 31 pages A 11/
). It is thought that the oxygen molecules taken into the film act to weakly bind the PPS molecules, enter the amorphous region and bond, and connect the bonds in the crystalline region.In PPS, the carrier propagation direction is perpendicular to the molecular chains, and in the crystalline region. Oligo-phenylene sulfide (hereinafter referred to as 0PS) is estimated to have high carrier mobility and the length of each PPS molecule is shortened to a degree of polymerization of about 5 to 7.The orientation and crystallinity are improved by vapor deposition. It was found that the photoconductivity of this film increased by expanding the crystalline region, and that the direction of carrier conduction was perpendicular to the long axis of the molecules (Proceedings of the 41st Annual Conference of the Japan Society of Applied Physics). 5p-ZH
-15). Furthermore, molecules incorporating functional groups into OPS can be oriented using an orientation method.If a film state with good crystallinity is achieved, carriers absorbed and generated in the optical absorption band of the functional group can be transmitted through the OPS skeleton (Japanese Patent Application Laid-Open No. 63-274871)
.

The absorption region of PPS and OPS is limited to a short wavelength region of 4007I111 or less. It was shown that visible range sensitization is possible by using this material as a charge transport layer and laminating it with a charge generation layer to form a functionally separated photosensitive layer.On the other hand, it is also possible to directly incorporate the charge generation material into PPS and OPS. Attempt? .

It is characterized by being a copolymer of an oligomer having one or more groups consisting of a group IV atom represented by the following general formula (c) and an aromatic or substituted aromatic group, and another organic molecule. It was discovered that a photoconductive material using an organic polymer is superior →X1-Yi→-(c) n≧2, i=1. 2. =・, nXI
: ○, S, Se, Te YI:
Aromatic or substituted aromatic groups are used to effectively incorporate functional groups into molecules of organic polymers such as PPS and OPS.The invention aims to solve this problem by making it possible to obtain photosensitive layers with various sensitivity wavelengths. Problem crystal method There is a strong correlation between orientation and photosensitivity, and it is difficult to control it.1. In particular, in the case of photoconductive polyimide with good photosensitivity, the photoconductivity of the polyimide film obtained from it varies greatly depending on the synthesis conditions of the polyamic acid solution that is its precursor. It is necessary to control this. Means for Solving the Problem A polyimide film is synthesized by synthesizing a polyamic acid from a diamine compound represented by the following general formula (a) and a tetracarboxylic acid represented by the following general formula (b). The mixing molar ratio of the raw materials diamine and carboxylic acid is l: I +M (M
>0) Tozumu N He -A -N Ha (a)
A: −(Xi−Yi)−−Xi −n≧15i=
1, 2, 3, "-n Xi: aromatic or substituted aromatic group Yi: O, S, Se, Te.

Either -CH=CH- (b) 0 Z: Group action containing aromatic The photoconductive polymer we have invented changes from an amorphous state to a crystalline film, resulting in a significant increase in photosensitivity.However, the crystallization process The presence of a crystal nucleus is indispensable for the crystallization process.On the other hand, the presence of a crystal nucleus is essential for crystallization when the polymer contains an oligomer consisting of an aromatic ring with a rigid molecular structure.On the other hand, the carboxylic acid moiety can be considered as the crystal nucleus. is a planar structure that easily interacts with the carboxylic acid moiety of other molecules.In other words, even if we think that the planar structure forms a stacked structure by bringing its surfaces together, this part becomes a crystal nucleus and the polymers line up. Even though we assume a growth mechanism that expands the crystal region, we also established a model in which the crystal nucleus is formed by the position of the carboxylic acid at the end of the polymer. When the group undergoes hydrolysis, it becomes a carboxylic acid. This group forms a dimer through hydrogen bonding with the carboxylic acid terminal group of other polymers, and this causes the polymers to line up. In order to introduce these crystal nuclei, Even if the ratio of carboxylic acid is increased as a synthesis condition for polyamic acid, a state in which carboxylic acid enters the end of the polymer can also be obtained by adding carboxylic acid to the polyamic acid solution and changing the diamine end to a carboxylic acid end. On the other hand, if the molar ratio of diamine and carboxylic acid deviates from 1:1 until it becomes 1:2, it becomes difficult to form a polymer chain, but the crystallization process requires movement in which the polymers slide and back against each other. be.

Although the polymer of the present invention requires a process of dehydration condensation to form an imide ring and a crystallization process in which the polymer is aligned, thermal condensation allows both processes to proceed simultaneously.

However, the first process impedes the thermal movement of molecules. Therefore, in the first step, after coating a polyamic acid solution on the substrate, it is immersed in a solution containing acetic anhydride. In this process, after dehydration and condensation, hydrolyzed acetic acid remains between the molecules, creating a state in which the molecular spacing is widened. keep. When the second heating crystallization is performed, the sliding movement of the molecules is facilitated, and the crystallization is carried out in a diamine molecule having the structure of the general formula (a) in the present invention, YI: aromatic or substituted aromatic. Examples of the group include the following: fused polycyclic hydrocarbons such as benzene, anthracene, naphthalene, pyrene, perylene, naphthacene, benzanthracene, benzophenanthrene, chrysene, triphenylene, and phenanthrene, and their substituted derivatives, anthraquinone, and dibenzopyrene. Fused polycyclic quinones such as quinone, anthanthrone, isoviolanthrone, and vilantrone, and their substituted derivatives; Metal-free phthalocyanines, red; Metallic phthalocyanines containing metals such as nickel and aluminum; indigo and thioindigo; and their derivatives. -A (1) A+ S)^-ph 2, 3, 4, 5 ・ ・ ・ ) is called n. ) 0). -Ph 2, 3, 4, 5...) Referred to as n) e) n-Ph 3.4, 5...) Referred to as n) CH), Ph 3, 4, 5...) HR (Ph (n=L (hereinafter 5DA (2) A: -(Ph (n-1, (hereinafter 0DA) (3) A: -(Ph-3 (n-1, 2, (hereinafter 5eDA) (4) A : -(Ph-CI (n=1, 2, (hereinafter referred to as BDA-n)) (5) A: -ph-s-x-s-ph-(X:
(Polycyclic aromatic rings such as naphthalene, anthracene, pyrene, perylene) (Ph represents a benzene ring bonded at the p-position) are also examples of compounds represented by the general formula (b) (friend (1) Pyromellitic acid (hereinafter referred to as PMDA) (2)
Benzophenone tetracarboxylic dianhydride (hereinafter referred to as BPD)
(referred to as A) (3) 3,3° 4.4゛-biphenyltetracarboxylic dianhydride (hereinafter referred to as B I DA I) (4) 1.l'5,5°-biphenyltetracarboxylic dianhydride (hereinafter referred to as BIDA2) (5) Naphthalene-1,4,5,8-tetracarboxylic dianhydride (hereinafter referred to as NADAI) (6) Naphthalene-2,3,6,7-tetracarboxylic dianhydride Example 1 Hereinafter, one implementation of the present invention Examples will be explained based on the attached drawings. Examples of the polyimide film having one or more groups composed of a group IV atom and an aromatic or substituted aromatic group according to the present invention include, for example, a polymer having the following structural formula. For example, the polyimide membrane described in C.2 can be treated by the following method.
The benzophenonetetracarboxylic dianhydride represented by the general formula (b) of the present invention is poured into N-dimethylacetamide (hereinafter referred to as DMAc) and dissolved using a Stargie or the like. A highly viscous polyamic acid can be obtained by mixing for about 30 minutes with a Stargy etc. After adding the solution, apply the polyamic acid solution onto a glass substrate, aluminum substrate, etc. using a spin cord, and heat it at about 80°C using a hot plate etc. for about 30 minutes. After temporary drying, the polyimide is heated at about 300°C for about 2 hours in a constant temperature bath. By this, the polyimide after the dehydration reaction is obtained. Since it is expressed as S 2, the molecular weight of Imol is 12x 18+
lx 16414×2+32x2-324g (C=1
28=IN=145=32) and the above-mentioned benzophenonetetracarboxylic dianhydride (from the structural formula of
l x 6+16x 7-322g (C=12.OH=
1. From the above, polyimide (hereinafter referred to as BPDA-P) synthesized from benzophenone tetracarboxylic dianhydride (phenylene sulfide diamine) and benzophenone tetracarboxylic dianhydride
h3) has a linear weight ratio of 1:1 in which the molar ratio of diamine compound to tetracarboxylic acid is 1:1.

Therefore, the molar ratio can be determined by the weight ratio of the diamine compound and the tetracarboxylic acid. is 0.9g
The polyamic acid solution was coated and heated at 300°C to form a polyimide film. BPDA, +5DA2)l As shown in Figure 1, the horizontal axis shows BPDA/(BPDA+DA3) and the vertical axis shows the polyimide film thickness.
The film thickness suddenly became thick when PDA/ (BPDA + DA3) was around 0.5. This is because the molecular chain of polyimide is long. Polymerization progresses the most under normal synthesis conditions (the above weight ratio -0.5) Show that.

Figure 2 1. The horizontal axis is the X-ray irradiation angle 2θ from X-ray structural analysis.
, the vertical axis shows the scattering intensity in the polyimide film.
As the diagram shows! , BPDA/(BPDA +D
Sample 1 with A, 3) of 0.511 or more 2θ=18
．． There are scattering peaks at 6° and 2θ = 22.4", and the polyimide film is crystallized. f = Bragg's reflection condition formula % formula % is the incident angle of the X-ray n is the order of reflection λ is the wavelength βπ/1
80), each surface spacing indicated by 2θ = 18.6° and 2θ = 22.4° (so d = 4.8 [in], d = 4
．． 0[Person 1 and required BPDA/ (BPDA10D
No scattering peak was observed in samples with A3) of 0.5 or less.In Figure 3, the horizontal axis is BPDA/ (BPDA + DA3), and the vertical axis is scattering per unit film thickness. Even if it shows strength, ○ is 2θ-18,6
As shown in the figure, if BPDA/(BPDA+DA3) is less than 0.5, it is an amorphous film.If it is greater than 0.5, it is a polyimide film with crystallinity. In FIG. 4, the horizontal axis shows BPDA/(BPDA+DA3), and the vertical axis shows the photosensitivity by electrophotography. Photosensitivity measurements are performed by positively charging the surface of a polyimide film on an AI substrate with a corona charging potential of +9 kV, then irradiating it with light, and calculating the amount of light required to halve the surface potential (half-reduction exposure amount E + - * [
1ux-see]) represents the photosensitivity. BPDA/
In the case of an amorphous film with (BPDA + DA3) of 0.5 or less, the sensitivity is 3001 ux-sec or more, which is a low force <, 0.
A polyimide film with a high sensitivity of 201 ux-see or less was obtained when the temperature was higher than 5. From these results, polyamic In particular, a highly sensitive polyimide film with crystallinity was obtained after acid heating.
When PDA1DA3) is 0.556, 71ux-se
A maximum photosensitivity of e was obtained and t:.

Also, as shown in Figure 1, BPDA/ (BPDA+
When DA3) is higher than 0.66, the film is formed as thin as 2 μm or less.
When (BPDA+DA3) was higher than 0.66, no scattering peak was observed and the film was an amorphous film.As shown in Figure 4, BPDA/(BPDA+DA3) was 0.66.
When higher than 66, a polyimide film with a low photosensitivity of several hundred ux-sec is formed, and from our results, the molar ratio is BPDA/(BPDA+
Ph5) is 0.66 or less, the molar ratio of diamine compound and tetracarboxylic acid is 1=1+M (0<M<
Example 2 in which a particularly highly sensitive crystallized polyimide film was formed when the conditions of FIG.

In order to demonstrate the crystallinity and photosensitivity of polyimide due to the addition of tetracarboxylic acid, polyamic acid was synthesized using the following method, and polyamic acid of BPDA-Ph3 was synthesized using the same method as in Example 1 in which a polyimide film was formed. Using DMA c as a solvent, the total weight of BPDA and DA3 is 0.9 g, and the weight percentage of BPDA to be added (BPDA
/ (BPDA + DA3)) of 0.55 was synthesized. This polyamic acid was coated on an aluminum substrate and heated to 300°C. Even if the scattering intensity is shown by X-ray structural analysis with addition
Although the horizontal axis of each data shows the X-ray irradiation angle 2θ and the vertical axis shows the scattering intensity, as shown in the figure, when BPDA is not added to both A and B, it is amorphous film. A scattering peak was observed, and a crystallized polyimide film was obtained. ) As shown in Table 1, both polyamic acid solutions A and B are amorphous films after the dehydration reaction, and the photosensitivity is low at several hundred ux-sec (on the other hand, each polyamic acid solution with BPDA added In acid, the scattering intensity per unit film thickness is approximately 3.0 to 3.45, showing high crystallinity, and the photosensitivity is also 2.
．． A polyimide with a high sensitivity of 91 ux-sec was formed. Also, since the film thickness of each polyimide became thicker after adding BPDA, the added BPDA was dehydrated and condensed with the terminal diamine, and the molecular chain length distribution became longer. The formation of a crystallized polyimide film is thought to be due to excess BPDA being located at the ends of each molecule and becoming crystal nuclei. By adding tetracarboxylic acid, a highly sensitive crystallized polyimide film was formed.Also, when the polyamic acid solution after adding tetracarboxylic acid was 1:l+M and 0<M<1, a highly sensitive crystallized polyimide film was formed. A crystallized polyimide is obtained.

Example 3 Figures 7 and 8 are diagrams showing the method for producing an organic polymer photoconductive material in the third example of the present invention. In order to show the dehydration reaction effect of immersion in acetic anhydride, polyimide films were Measure crystallinity and photosensitivity? , :o3ml N,
A polyamic acid prepared by synthesizing 0.42 g of BPDA and 0.38 g of DA3 using N-dimethylacetamide as a solvent was coated on an aluminum substrate, immersed in acetic anhydride for a predetermined period of time, and then heated at 300°C. The horizontal axis shows the scattering intensity when immersed in acetic anhydride, and the vertical axis shows the scattering intensity obtained by X-ray structural analysis. The scattering intensity is indicated by a circle.Especially when the immersion time is 2 hours, a crystallized polyimide film with a high value of 5.2 is obtained. ) is shown.

When immersed in acetic anhydride (as compared to when heated only),
It shows high photosensitivity, especially when immersed in acetic anhydride for 3 hours. A polyimide film with high sensitivity as ux-see was obtained. So, △ means polyimide that was not immersed in acetic anhydride.It is 1 when it was not immersed in acetic anhydride.
Low photosensitivity and strength When immersed in acetic anhydride,
A crystallized polyimide film with high sensitivity can be obtained by dividing the process into a dehydration reaction caused by immersion in acetic anhydride and crystallization by heat treatment, rather than a heat treatment process in which dehydration reaction and crystallization are performed simultaneously. ,
A highly sensitive crystallized polyimide film was obtained.Also, a highly sensitive crystallized polyimide film was obtained by adding pyridine to a solution containing acetic anhydride in an amount of 50% by weight or less based on acetic anhydride. Figures 9 and 1O show the crystallinity and photosensitivity with respect to the pyridine addition rate [%] (pyridine weight/acetic anhydride weight*100). Polyamic acid synthesized with 42 g of BPDA and 0.38 g of DA3,
L immersed in acetic anhydride with varying amounts of pyridine for 2 hours
In Fig. 9, which was heated to 300°C, the horizontal axis shows the pyridine added wind, and the vertical axis shows the scattering intensity by X-ray analysis. When the addition of pyridine is more than 50%, an amorphous film is obtained, and when it is less than 50%, a crystallized film is obtained. ) As shown in Figure 3, when the amount of pyridine added is higher than 50%, the photosensitivity is low, on the order of several hundred 1ux-seC.When the amount added is less than 50%, the photosensitivity is low, less than 51ux-seC. From these results, adding pyridine to a solution containing acetic anhydride at 50% by weight or less of acetic anhydride accelerates the dehydration reaction, resulting in high crystallinity and a highly sensitive polyimide film. Example 4 An electrophotographic photoreceptor was produced by the manufacturing method of the present invention.
-The structural cross-sectional view of the photoreceptor is shown in Figure 11. Serious cylindrical board surface +0
The polyamic acid of BPDAi)h3 of Example 1 was applied to the sample to a thickness of 15 μm.The molar ratio used was 0.52. Coating: After drying, heat treatment is performed at 300°C for 2 hours.

This photoreceptor was installed in a copying machine and the image characteristics were evaluated using the photosensitive method.The initial surface potential was 700V, and the half-decreased exposure amount was 3.01uxs.
ec.

It had a good residual potential of 50 V, and exhibited stable sensitivity and images even after 10,000 continuous images were output.9 Example 5 A spatial light modulation element was manufactured using the manufacturing method of the present invention.
, A cross-sectional view of the element configuration is shown in FIG.

A photoconductive polyimide BPDAPh3 is formed as an alignment film 203 on a glass substrate 201 on which an ITO transparent electrode 202 is formed.One alignment film 206 is formed to have a film thickness of 5 μm according to the method of Example 3. Film thickness 1000
This spatial light modulation element 2 is filled with BPDAPh3 as A.
10 is because the alignment state of the liquid crystal 205 changes in response to the optical energy of the incident light 21+ that exceeds a certain threshold.Therefore, the optical energy of the emitted light 212 changes as shown in Fig. 13, and the optical neural network Taku Optical calculation Effects of the Invention According to the manufacturing method of the present invention, a crystalline polymer having high photosensitivity can be provided. This photosensitive material provides a thermally stabilized electrophotographic photoreceptor with excellent printing durability at a low cost, and also provides a highly sensitive optical switching element when used as a liquid crystal alignment film.

[Brief explanation of drawings]

Figure 1 shows no change in the film thickness of the polymeric photoconductive material produced by the manufacturing method of the present invention. Figure 2 shows the scattering intensity due to the difference in the weight percentage of tetracarboxylic acid. The scattering intensity per film thickness due to the difference in
Figure 4 shows the photosensitivity due to the difference in the weight percentage of tetracarboxylic acid. Figure 5 shows the scattering intensity per film thickness due to the difference in the amount of tetracarboxylic acid added. Figure 6 shows the photosensitivity due to the difference in the immersion time in acetic anhydride. Figure 7 shows no photosensitivity due to differences in acetic anhydride immersion time. Figure 8 shows the relationship between scattering intensity and photosensitivity for different acetic anhydride immersion times. Figure 9 shows pyridine. Figure 1O shows the scattering intensity in the film thickness due to the difference in the amount of pyridine added. 13 is a diagram showing the optical switching characteristics of the spatial light modulator shown in FIG. 12. 101...Support 102...Photoconductive layer 103...Free surface 201.207...Transparent substrate 202.206.
- Transparent electrode 203... Photoconductive alignment film 204... Liquid crystal 205... Alignment film 208... Polarizer 209... Analyzer 210... Spatial light modulation element 211... Incident light
212...Emission 9

Claims (6)

[Claims] (1) A photoconductive polyimide film is formed using the following general formula (
When synthesizing polyamic acid from the diamine compound represented by (a) and the tetracarboxylic acid represented by the following general formula (b), the mixing molar ratio of the raw materials diamine and carboxylic acid should be 1:1+M (M>0). Method for producing photoconductive polymers characterized by ▲Mathematical formulas, chemical formulas, tables, etc.▼・・・・・・(a) A: -(Xi-Yi)n-Xi- n≧1, i=1,2 , 3,...,n Xi: aromatic or substituted aromatic group Yi: O, S, Se, Te, -CH=CH- ▲ Numerical formula, chemical formula, table, etc. are available ▼... (b) Groups containing aromatics (2) The mixing molar ratio of raw material diamine and carboxylic acid is 1
2. The method for producing a photoconductive polymer according to claim 1, wherein: 1+M and M<1. (3) A polyimide film having photoconductivity is formed using the general formula (a).
When synthesizing polyamic acid from the diamine compound represented by the formula (B) and the tetracarboxylic acid represented by the general formula (B), it is recommended that the tetracarboxylic acid represented by the general formula (B) be added after mixing in a predetermined ratio. Characteristic method for producing photoconductive polymers. (4) The mixing molar ratio of diamine and carboxylic acid in the polyamic acid solution after adding tetracarboxylic acid is 1:1
4. The method for producing a photoconductive polymer according to claim 3, wherein +M satisfies 0<M<1. (5) After applying a polyamic acid solution obtained by a condensation reaction between a diamine compound represented by the general formula (a) and a tetracarboxylic acid represented by the general formula (b) onto a substrate, the polyamic acid solution is poured into a solution containing acetic anhydride. 1. A method for producing a photoconductive polymer, comprising immersion and subsequent heat treatment. (6) The method for producing a photoconductive polymer according to claim 5, characterized in that pyridine is added to the solution containing acetic anhydride in an amount of 50% by weight or less based on acetic anhydride.