JP3209847B2 - Polyurethane resin composition, charging member and electrophotographic apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a polyether type urethane resin composition, and more particularly to a urethane resin composition having a medium resistance such as antistatic property .

Further, the present invention relates to a charging member and an electrophotographic apparatus used in an electrophotographic apparatus, and more particularly, to a contact charging member and an electrophotographic apparatus for pressing a charging apparatus against an electrostatic latent image carrier such as a photosensitive member to charge the same. .

[0003]

2. Description of the Related Art Recently, polyurethane resins are used in various products due to their good moldability and the like, and the market is expanding.

[0004] However, polyurethane resins are easily charged with static electricity, and therefore, it has been desired to develop a resin which has a low electric resistance and can easily conduct electricity. In other words, when the polyurethane resin is charged with static electricity, dirt and dust adhere to the resin surface and become dirty, and the resins adhere to each other due to the static electricity, thereby reducing work efficiency and reducing static electricity during processing of the resin. In many cases, sparks are generated due to charging.

[0005] For this reason, development for preventing static charge has been conventionally performed. As an example, there is a method of adding a cationic or nonionic surfactant to the resin as an antistatic agent. However, if the amount is not increased, the effect is not obtained, the economic efficiency is poor, and the bonding strength is weak. As a result, the resin may fall off from the resin, and the composition as the resin may be changed, which is not practical.

Further, there is a method of dispersing a conductive filler in a resin. However, this method is also not preferable because of problems such as a quantity problem and a moldability problem.

Further, there is a method of spraying the above-mentioned surfactant or the like on the resin after molding in a post-treatment. However, the effect is not long-lasting compared with the processing cost, and the method is not economical. Was.

Recently, a contact charging member for directly contacting and charging a photoreceptor has been proposed, for example, as described in JP-A-63-167380, and compared with a conventionally used corona charging system. It is recognized that it has advantages such as a low applied voltage and low ozone generation.

The conductivity is adjusted by adding a conductive substance such as conductive carbon black to the elastic layer. In order to improve the electrical characteristics and the like, see, for example, JP-A-1-191161.
As described in the above item, an additional 4.0 × is applied on the elastic layer.
A contact charging member coated with a member having a volume resistance value of 10 ⁹ Ωcm or more has been proposed.

In any case, the resistance value of the binder resin used for the elastic layer is generally as high as 10 ¹⁰ Ωcm or more.
It is difficult to stably lower the resistance value, and there are problems such as resistance fluctuation due to energization and resistance fluctuation due to molding conditions.

According to the studies by the inventors, it has been found that these problems are caused by a difference in resistance between the binder resin and the conductive pigment. This is considered to be because when the difference between the specific resistance values of the binder resin and the conductive pigment is large, electricity flows intensively to the pigment portion and is liable to deteriorate. Accordingly, development of an inexpensive resin in the medium resistance region has been desired.

In addition, there has been proposed a method of applying an AC electric field and a DC electric field together in order to obtain uniform charging. In contact-type charging, in which charging is performed by applying an electric field obtained by superimposing an AC electric field on a DC electric field to the contact charging member, the mechanical vibration of the charging member due to the AC electric field occurs, which gives an unpleasant environment as a charging noise. There is. In particular, when the frequency of the AC electric field is as high as several hundred Hz, it is recognized that the charging noise becomes remarkable due to the problem of the timbre. This phenomenon occurs when an AC electric field is applied to the charging member, the charging member vibrates due to the intensity of the electric field, and the vibration propagates to the photosensitive member. At this time, when the support of the photoreceptor is made of a metal cylinder as conventionally used, it is recognized that the propagated vibration does not attenuate and resonates to generate a remarkable charging noise. A charging member that can be charged only in the field is desired.

An object of the present invention is to provide a contact charging member which has solved the above-mentioned disadvantages.

Another object of the present invention is to provide an elastic body which solves the above-mentioned problem.

Another object of the present invention is to provide a urethane resin composition having a low specific resistance value.

It is a further object of the present invention to provide a charging member in which the resistance value does not change even when current is repeated.

Still another object of the present invention is to provide a charging member capable of realizing uniform charging only by a DC electric field.

It is a further object of the present invention to provide an electrophotographic apparatus using such a charging member.

[0019]

Means for Solving the Problems That is, the present invention is 2
The reaction obtained by mixing and polymerizing more than one prepolymer
Reaction product, wherein at least one of the prepolymers is a
1 polyether polyol and aromatic diisocyanate
Is the first prepolymer obtained by reacting
At least one of which is a second polyether polyol and an aliphatic
The first preploid obtained by reacting a diisocyanate
A second prepolymer different from the lima, wherein the first and the second
The second polyether polyol is a dihydric alcohol
To mix and polymerize two or more prepolymers
The solution containing two or more prepolymers used for
Containing a solid electrolyte represented by the general formula (1).
A polyurethane resin composition containing a solid electrolyte .

[0020]

Embedded image (In the formula, R ₁ to R ₄ represent a hydrogen atom, an alkyl group or an aryl group.)

In a charging member which contacts a member to be charged and applies a voltage to perform charging, wherein the charging member having at least a conductive elastic layer, the conductive elastic layer comprises two or more prepolymers. An anti-cast product obtained by mixing and conducting a polymerization reaction.
A reaction product obtained by reducing the amount of the prepolymer.
At least one being a first polyether polyol and an aromatic
First prepoly obtained by reacting diisocyanate
At least one of which is a second polyetherpolyol.
And aliphatic diisocyanate
A second prepolymer different from the first prepolymer.
The first and second polyether polyols are divalent
Alcohol, a mixture of two or more prepolymers
Contains two or more prepolymers used for the reaction
A solid electrolyte represented by the following general formula (1):
A charging member comprising a solid electrolyte-containing polyurethane resin composition characterized by containing:

[0022]

Embedded image (In the formula, R ₁ to R ₄ represent a hydrogen atom, an alkyl group or an aryl group.)

In an electrophotographic apparatus having a photosensitive member, a latent image forming unit, a unit for developing the formed latent image, and a unit for transferring the developed image to a transfer material, the photosensitive member is charged as the latent image forming unit. An electrophotographic apparatus, wherein the charging member is used for processing.

Hereinafter, the present invention will be described.

The polyether polyol used in the present invention
(Hereinafter abbreviated as polyol (PO) ) include alkyl dihydric alcohols obtained by polymerizing alkyl oxides such as ethylene oxide and propylene oxide as monomers, and aromatic dihydric alcohols such as bisphenol.

When polymerizing the above dihydric alcohol, two or more monomers may be used as the PO of the present invention, or the PO may be used after being polymerized alone and mixed. Further, PO synthesized alone may be mixed with the copolymer. One of these preferably contains polyethylene oxide.

The isocyanate used in the present invention includes:
Tolylene diisocyanate (TDI) and diphenylmethane diisocyanate (MD) as aromatic isocyanates
General-purpose isocyanates such as I). Examples of the aliphatic isocyanate include general-purpose isocyanates such as hexamethylene diisocyanate (HDI), hydrogenated MDI, and hydrogenated xylylene diisocyanate (hydrogenated XDI). In the present invention, two or more isocyanates are used in combination in order to improve mechanical properties and the like.

Polyurethane (PU) used in the present invention
The synthesis method, the polymer with a two-step using a diamine were reacted as previously prepolymer of PO and isocyanate, a chain extender or the like.

[0029] In the present invention, prepared two or more prepolymer, by mixing it with the polymerization step, is more spread coexistence range of conductive and elastic.

In the present invention, a quaternary ammonium salt of perchloric acid is used as the solid electrolyte. The quaternary ammonium is represented by the following formula.

[0031]

Embedded image (In the formula, R ₁ to R ₄ represent a hydrogen atom, an alkyl group or an aryl group.) The addition amount of the quaternary ammonium salt of perchloric acid used in the present invention is preferably 0.05 to 30% by weight. . If the addition amount is less than 0.05% by weight, the effect of addition is small, and if it exceeds 30% by weight, the workability and strength are lowered, which is not preferable.

In the present invention, a conductive pigment may be added to finely adjust the resistance value. Examples of the conductive pigment include carbon black, zinc oxide, titanium oxide, and metal particles.

If necessary, known materials such as amine-based and organotin-based catalysts, crosslinking agents, stabilizers, and foaming agents may be blended.

Further, it is possible to coat the surface with a thin layer for the purpose of improving the surface properties of the charging member and improving the bleed resistance.

The shape of the charging member used in the present invention is as follows.
The contact portion may be uniform such as a cylinder, a blade, or a block. It is preferably cylindrical for durability and the like.

As the photosensitive layer used in the present invention, α-S
A photosensitive layer containing a commonly used photoreceptor such as i, selenium, OPC (organic photoreceptor) can be used. In particular, an OPC photoreceptor is preferred because of the simplicity of the production method and the like.

The OPC photoreceptor has a single layer type in which a charge generation (CG) material and a charge transport (CT) material are mixed, or a layer type in which a CG layer and a CT layer are stacked. In the case of a single-layer type photosensitive layer, a CG material and a CT material are dissolved and mixed in a suitable resin component using a solvent or the like, and the photosensitive layer is formed on a support by coating. In the case of a laminated photosensitive layer, a CG layer and a CT layer are laminated on a support in this order,
What is necessary is just to laminate | stack in order of T layer and CG layer, and this is determined by a use.

The bias used in the present invention includes a DC power supply and a DC + AC power supply. Specifically, in the case of a DC power supply, an electric field obtained by adding a charging start voltage to a desired charging voltage is applied. Further, the amount by which the resistance fluctuates due to the environment or the like may be finely adjusted by constant current control. In the case of a DC + AC power supply, an electric field in which a charging target voltage is superimposed on an AC having a peak-to-peak voltage that is twice or more the charging start voltage is applied.

Examples of the electrophotographic apparatus used in the present invention include a copying machine and an LBP as shown in FIG. In FIG. 1, 1 is a member to be charged, 2 is a charging device, 3 is a document exposing device, 4 is an entire surface exposing device, 5 is a developing device, 6 is a transfer device, 7 is a cleaning device, 8 is a charging device power source, and 9 is a charging device power supply. An original table 10, a lens 10, and a fixing device 11 are omitted (except for main devices).

[0040]

EXAMPLES Specific examples will be described below, but it is obvious that the present invention is not limited to these examples . Example 1 1 mol. Of PPG (Mw: 1000). To TDI 2mo
l. Is reacted to obtain Prepolymer 1. PTMG (M
w: 1000) 1 mol. HDI 2 mol. Is reacted to obtain a prepolymer 2. PEG (Mw: 1000)
1 mol. TDI 2 mol. Is reacted to obtain Prepolymer 3.

As a quaternary ammonium perchlorate compound, tetrabutylammonium perchlorate in an amount of 5% by weight and 1 mol. And 3 mol. Of 1,4-butanediol as a chain extender. After adding the organotin catalyst, φ6
mm around the core metal so that the thickness becomes 3 mm,
A cylindrical molded product was obtained. The specific resistance was measured to be 3 × 10 ⁶ Ωcm.

The laser beam printer LBPA
404 (manufactured by Canon Inc.), and a bias was applied using the power supply of the main body.

Development V _DC -400 V Drum surface potential -550 V _DC voltage -550 V AC voltage 1.8 KV _PP , f = 150 Hz Low temperature and low humidity environment (15 ° C., 10%, hereinafter L / L) and high temperature and high humidity environment ( At 32.5 ° C., 85%, hereinafter H / H), the image was evaluated by endurance of 3000 sheets.

As a result, there was no problem in both L / L and H / H at both the initial stage and after the endurance, and there was no problem.

Example 2 The end of 10 parts by weight of PPG (Mw: 1000) was PEG
(Mw: 1000) PO modified by 90 parts by weight
1 mol. Against 2 mol. Is reacted to obtain Prepolymer 1. PPG (Mw: 1000) 1 mol.
HDI 2 mol. Is reacted to obtain a prepolymer 2.

The quaternary ammonium perchlorate was added in the same manner as in Example 1. Using these, a charging member was formed in the same manner as in Example 1. When the specific resistance was measured in a normal environment, it was 1 × 10 ⁶ Ωcm.

As a result, there was no problem in H / H, both in the initial stage and after the endurance, and there was no problem. However, in L / L, a decrease in potential due to an increase in resistance due to environmental fluctuation was observed.
However, no abnormality on the image was observed.

Embodiment 3 The charging member of Embodiment 1 is attached to the charging device position of a copying machine FC310 (manufactured by Canon Inc.), and the bias is set to -12.
A DC electric field of 00 V was applied to perform image evaluation.

As a result, neither L / L nor H / H had an abnormal image at the initial stage, and no abnormality related to durability was observed.

[0050] except that the addition amount with perchloric acid Tetorahe Bed <br/> chill ammonium Example 4 perchlorate quaternary ammonium salt and 30% by weight, was evaluated in the same manner as in Example 1. The resistance value is 5 × 10
It was ⁴ Ωcm.

As a result, no abnormal image was found in the initial stage for both L / L and H / H, but generation of minute cracks was observed with the endurance. However, no abnormality was observed on the image.

[0052] except that the amount of perchlorate Tetorahe Bed chill ammonium and 0.05 wt% in Example 5 Example 4 was carried out as in Example 2. The resistance value was 5 × 10 ⁷ Ωcm.

As a result, no abnormality was observed in H / H both at the initial stage and after the endurance, but in L / L, an increase in resistance due to environmental fluctuation and endurance was observed, and a decrease in potential occurred. . However, no abnormality on the image was observed.

Comparative Example 1 PPG and HDI were prepared in Example 2 except for Prepolymer 1.
The evaluation was performed in the same manner except that the evaluation was made only with the above. Resistance is 5 × ¹⁰ 10 Ωcm, in the charging device resistance is high, it was impossible to obtain a uniform charging.

As a result, in both L / L and H / H, fogging due to poor charging occurred on the image from the beginning, and the image was not usable.

Comparative Example 2 Evaluation was made in the same manner as in Example 2 except that HDI of prepolymer 2 was replaced by TDI and the isocyanate component of prepolymers 1 and 2 was changed to TDI alone. Resistance value is 1 ×
It was 10 ⁹ Ωcm.

As a result, both L / L and H / H had no abnormal image at the beginning and there was no problem. However, in both environments, mechanical defects such as cracks occurred in the charging member due to durability, and especially in L / L. The image defect due to cracking occurred and was not usable.

Comparative Example 3 Evaluation was made in the same manner as in Example 1 except that the quaternary ammonium perchlorate compound was omitted. Resistance value is 1 × 1
It was 0 ¹⁰ Ωcm.

As a result, an increase in resistance due to environmental fluctuation was observed in L / L, fog was generated from the beginning, and the product was not usable.

[0060]

As described above, the polyurethane resin composition of the present invention has a resistance value in a medium resistance region.

Further, these polyurethane resinsComposition
Touches the charging member to the photoconductor and applies an electric field to the charger.
The present invention is applicable to a contact charging member that performs additional charging.

Further, it is possible to satisfy both the resistance value and the mechanical properties such as hardness.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an electrophotographic apparatus of the present invention.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-2-269723 (JP, A) JP-A-4-298518 (JP, A) JP-A-5-88508 (JP, A) JP-A-3- 38663 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) C08L 75/00-75/16 C08K 3/00-13/08 G03G 15/02

Claims (3)

(57) [Claims] 1. A polymerization reaction in which two or more prepolymers are mixed.
A reaction product obtained by
At least one of the first polyether polyol and the fragrance
First prepolymer obtained by reacting an aromatic diisocyanate
Lima, at least one of which is a second polyether poly
Obtained by reacting all and aliphatic diisocyanates.
A second prepolymer different from the first prepolymer.
The first and second polyether polyols are divalent
Alcohol, a mixture of two or more prepolymers
Contains two or more prepolymers used for the reaction
A solid electrolyte represented by the following general formula (1):
A solid electrolyte-containing polyurethane resin composition comprising: Embedded image (In the formula, R ₁ to R ₄ represent a hydrogen atom, an alkyl group or an aryl group.) 2. A charging member which contacts a member to be charged and charges by applying a voltage, wherein the charging member having at least a conductive elastic layer has two or more conductive elastic layers .
Reaction products obtained by mixing and polymerizing prepolymers
Wherein at least one of said prepolymers is a first polymer
Reacts ether polyol and aromatic diisocyanate
A first prepolymer obtained by subjecting at least one
Is a second polyether polyol and an aliphatic diisocyanate
What is the first prepolymer obtained by reacting anate
A different second prepolymer, wherein the first and second polymers are different.
The reether polyol is a dihydric alcohol,
Used to mix and polymerize the above prepolymer
The solution containing two or more prepolymers is further represented by the following general formula
Characterized by containing a solid electrolyte represented by (1).
A charging member comprising a solid electrolyte-containing polyurethane resin composition . Embedded image (In the formula, R ₁ to R ₄ represent a hydrogen atom, an alkyl group or an aryl group.) 3. An electrophotographic apparatus having a photosensitive member, a latent image forming unit, a unit for developing the formed latent image, and a unit for transferring the developed image to a transfer material, wherein the photosensitive member is charged as the latent image forming unit. An electrophotographic apparatus using the charging member according to claim 2 for processing.