JPH0934215A - Conductive roller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a conductive roller using catalysts which do not induce contamination by forming a conductive elastic layer by the polyurethane elastomer obtd. by reactively curing a specific reactive mixture by using the specific catalysts. SOLUTION: The outer periphery of a revolving shaft is provided with the conductive elastic layer. The conductive elastic layer consists of the polyurethane elastomer obtd. by reactively curing the reactive mixture contg. polyisocyanate, polyol and electrical conductivity imparting agent in the presence of the diazabicycloamine salt catalyst. The diazabicycloamine salt catalyst is the salt of ternary amine, i.e., quaternary ammonium compd. and is expressed by formula. In the formula, (n) is 3, 4, 5 or 6; A is the residue of the acid forming a salt with diazabicycloamine. A is preferably the residue of octyl acid, oleic acid, p-toluene sulfonic acid, formic acid, phenol, orthophthalic acid, acetic acid, maleic acid or boric acid.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a conductive roller,
In particular, the present invention relates to a conductive roller that does not contaminate a photoconductor (photosensitive drum) that comes into contact with an electrophotographic apparatus.

[0002]

2. Description of the Related Art Electrophotographic devices such as copying machines, facsimiles, printers and the like are generally equipped with electrically conductive rollers such as a charging roller and a developing roller. For example, in a one-component developing type electrophotographic apparatus, toner (developer) is moved from a developing roller, which is in pressure contact with each other, to a photosensitive member, and an electrostatic latent image is visualized to perform development.

Such a developing roller is required to have elasticity because it is pressed against a photosensitive member with a predetermined contact width and carries a thin layer of toner by a blade or the like, and typically, it has an outer periphery of a rotating shaft. A roller having a conductive elastic layer formed of an elastomer (elastic body) having a low hardness and containing a conductivity-imparting agent is used.

For the conductive elastic layer of these rollers, a polyurethane elastomer which is easily deformed and excellent in restorability and which does not contaminate the photoreceptor is preferably used.

When a polyisocyanate and a polyol are reacted to form a conductive elastic layer made of a polyurethane elastomer, a catalyst is usually used in order to adjust the reaction rate and improve workability.

The most widely used catalysts are tertiary amine catalysts. Examples of the tertiary amine catalyst include triethylenediamine, N-methylmorpholine, N-ethylmorpholine, dimethylethanolamine, 1-methyl-4-dimethylaminoethylpiperazine, 3-methoxy-N, N.
-Dimethylpropylamine, N, N-diethyl-3-diethylaminopropylamine, 1,2-dimethylimidazole, dimethylbenzylamine and bis (2-dimethylaminoethyl) ether.

When a conductive roller having a conductive elastic layer made of the above-mentioned catalyst-containing polyurethane elastomer is used in an electrophotographic apparatus, the catalyst often exudes from the conductive elastic layer during use.

This phenomenon is particularly remarkable under high temperature and high humidity. When the catalyst oozes out, it attacks and contaminates the photosensitive layer on the surface of the photoconductor in contact. As a result, discoloration of the photoconductor, clouding, and further dissolution (exposure of the photoconductor substrate) proceed.

Such deterioration of the photoconductor causes defective charging of the photoconductor, and finally causes image defects (disturbs the image) when copying or printing.

[0010]

As described above, when a conductive roller is made of a polyurethane elastomer using a conventionally used catalyst, the photosensitive roller or other members are contacted by the catalyst contained in the conductive elastic layer. There was a pollution problem.

The present invention has been made in view of this problem, and an object of the present invention is to provide a conductive roller using a catalyst that does not cause pollution.

[0012]

SUMMARY OF THE INVENTION The present invention relates to a conductive roller having a conductive elastic layer made of a polyurethane elastomer reaction-cured with a temperature-sensitive catalyst. According to the present invention, in the conductive roller provided with the rotating shaft and the conductive elastic layer formed on the outer periphery thereof, the conductive elastic layer comprises a reactive mixture containing a polyisocyanate, a polyol and a conductivity-imparting agent, Provided is a conductive roller made of a polyurethane elastomer obtained by reaction curing in the presence of a diazabicycloamine salt catalyst.

The conductive elastic layer is not limited to a single conductive elastic layer, but the conductive elastic layer further has a surface coating layer on its outer periphery in order to protect the conductive elastic layer and impart environmental stability to the layer. But it's okay.

The polyurethane elastomer which can be used in the present invention is obtained by reacting a polyisocyanate, a polyol and, if necessary, a chain extender, a crosslinking agent and the like. The polyisocyanate may be aliphatic, alicyclic or aromatic. Preferred polyisocyanates include 4,4'-diphenylmethane diisocyanate (MDI), polymethylene polyphenyl isocyanate (polymeric MDI), dicyclohexylmethane diisocyanate (hydrogenated MDI), hexamethylene diisocyanate (HDI), isophorone diisocyanate (I
PDI), xylylene diisocyanate, tolylene diisocyanate, naphthalene diisocyanate, phenylene diisocyanate, and modified products thereof. The modified product means a dimer, a trimer, a urethane modified product, a urea modified product, or the like obtained by reacting polyisocyanates with each other. These polyisocyanates can be used alone or as a mixture of two or more kinds. In the present invention, the polyisocyanate used is preferably liquid at room temperature (10 to 40 ° C.). Particularly preferred are modified MDI, polymeric MDI,
Hydrogenated MDI, TDI, HDI, IPDI.

Polyols that can be used in the present invention include polyether polyols and polyester polyols.
Examples of the polyether polyol include polyethylene polyether glycol, polypropylene ether glycol, polytetramethylene ether glycol, polyhexamethylene ether glycol, polyoctamethylene ether glycol, polydecamethylene ether glycol, and mixtures thereof. As the polyol, it is possible to use one having three or more hydroxyl groups in one molecule, for example, polypropylene ether polyol. Examples of the polyester glycol include those obtained by reacting a dibasic acid with glycol. Examples of the dibasic acid include adipic acid, succinic acid, sebacic acid, terephthalic acid, alkyl derivatives and halogen derivatives of these acids,
Examples of glycols include ethylene glycol, diethylene glycol and propylene glycol. Further, polycaprolactone polyol obtained by ring-opening polymerization of lactone can also be used. These polyols can be used alone or as a mixture of two or more kinds. As the polyol, a high-molecular weight polyol and a low-molecular weight polyol are generally selected from the above-mentioned ones and used in combination. In that case, the ratio of each polyol is usually 100/0 to 95 / by weight. 5 (the former / the latter)
It is preferably within the range. In the present invention, it is particularly preferable to use a mixture of high molecular weight polypropylene ether glycol and low molecular weight polyol.

Like the polyisocyanate, it is preferable to use a polyol which is liquid at room temperature. Particularly preferred are polypropylene ether glycol, polypropylene ether polyol, β-methyl-δ-valerolactone polyol, and 3-methylpentylene adipate. In the present invention, polyisocyanate which is liquid at room temperature,
The reason why the polyol is preferably used is that when it is liquid at room temperature, operations such as measurement, mixing, and casting are easy to perform, and it is not only safe but also the utility cost is saved.

In addition to polyisocyanate and polyol,
Chain extenders can also be used. The chain extender includes a hydroxy chain extender and an amine chain extender. Examples of the hydroxy chain extender include ethylene glycol, propylene glycol, diethylene glycol, 1,4-butanediol, 1,6-hexanediol and the like. Examples of the amine chain extender include ethylenediamine, 1,2-propylenediamine, tetramethylenediamine, hexamethylenediamine, decamethylenediamine, isophoronediamine, m-xylylenediamine and hydrazine. A crosslinking agent may be used in the polyurethane reaction. Like the chain extender, the cross-linking agent also includes a bidroxy cross-linking agent and an amine cross-linking agent. Hydroxy crosslinkers are glycerin and trimethylolpropane and other alkylenetriols. Amine crosslinkers are alkanolamines such as diethanolamine, triisopropanolamine and the like.

The diazabicycloamine salt catalyst which can be used in the present invention is a salt of a tertiary amine, namely a quaternary amine.
Is a quaternary ammonium compound and has the general formula (1)

[0019]

Embedded image

Where n is 3, 4, 5 or 6,
A is a residue of an acid that forms a salt with diazabicycloamine. ) Is a diazabicycloamine salt, preferred examples of the acid forming the salt are octylic acid, oleic acid, p-toluenesulfonic acid, formic acid, phenol, orthophthalic acid, acetic acid, maleic acid or boric acid. Is. Preferred examples of diazabicycloamines are 1,8-diazabicyclo- (5,4,0) -undecene-7 (DBU) and 1,5-diazabicyclo (4,3,0) -nonene-.
5 (DBN). A particularly preferred catalyst is DBU-
Phenol salts, DBU-formates and DBU-octylates. The amount of such a catalyst used is the amount of Polyol 1
The amount is preferably 0.2 to 1.0 part by weight, more preferably 0.3 to 0.5 part by weight, per 100 parts by weight.

An important aspect of the present invention is to form a conductive elastic layer by carrying out a curing reaction using the diazabicycloamine salt as a catalyst. Generally, in a tertiary amine, the higher the basicity, the higher the catalytic activity, and in this respect, DBU, DBN, etc., which have no steric hindrance to the lone electron pair of the amine nitrogen,
The diazabicycloamine contained in the general formula (1) is preferable as the polyurethane conversion catalyst. However, since the basicity is high, when diazabicycloamine is used alone, the catalyst remaining in the formed conductive elastic layer exudes from the roller. As described above, when the roller comes into contact with the photoconductor, the catalyst contaminates the surface of the photoconductor. The present invention is characterized in that the diazabicycloamine is used in the form of a salt with a thermosensitive acid instead of the diazabicycloamine. That is, since the diazabicycloamine salt used in the present invention is in a salt form at room temperature, for example, 10 ° C to 40 ° C, it hardly shows catalytic activity, but at a constant temperature,
For example, at 70 ° C. to 150 ° C., diazabicycloamine is released and catalytic activity is developed. Thus, the diazabicycloamine salt used in the present invention is temperature-sensitive,
When it is cooled to around room temperature after the polyurethane reaction, it returns to its original salt form. In the salt form, the basicity is lowered and the catalytic activity is lost, but there is no contamination on the photoconductor. The reason why the amount of the catalyst used is within the above range is
If it is less than 0.2 parts by weight, sufficient catalytic activity cannot be obtained,
Further, if the amount exceeds 1.0 part by weight, the photoconductor may be contaminated.

In order to impart conductivity to the polyurethane elastomer, a conductivity-imparting agent is usually added to the polyol in advance and uniformly dispersed before use. Examples of the conductivity imparting agent include tin oxide particles and the like, in addition to carbon black. A preferred conductivity-imparting agent is carbon black. The amount used is 0.2 to 100 parts of polyol.
It is 1.0 part by weight, preferably 0.5 part by weight.

The polyurethane elastomer used in the conductive roller of the present invention can be manufactured by a known method. For example, a polyisocyanate, a polyol, a catalyst and, if desired, other auxiliaries are mixed and reaction-cured to obtain a polyurethane elastomer. The blending ratio of the polyisocyanate component and the polyol component is NCO / OH, which is the ratio of NCO groups and OH groups contained in each.
0.95 to 1.20, preferably 1.00 to 1.10.
Adjust to react. As described above, it is preferable to use a polyisocyanate and a polyol that are liquid at room temperature as described above, and to carry out reaction curing without a solvent. The auxiliaries which can be used in the present invention are colorants, flame retardants, antioxidants, release agents and the like.

In the integral molding method, which is a method for carrying out the present invention, the reactive mixture (including the catalyst) is put into a mold at ambient temperature, and after filling, the mold is cured at 70 to 150 ° C. for curing.
Heat to the temperature of. According to another method of implementation, after filling the mold with the reactive mixture preheated to 80 ° C., the mold is likewise heated to 150 ° C. for curing. In either case, heating of the mold is accomplished by placing the mold in an oven set at a temperature slightly higher than the desired mold temperature. In both cases, the mold temperature was 70% due to the curing reaction.
C. to 150.degree. C., preferably 80.degree. C. to 110.degree.

[0025]

In the present invention, since a temperature-sensitive catalyst is used,
As the temperature of the reactive mixture in the mold rises, the diazabicycloamine salt catalyst liberates diazabicycloamine, which catalyzes the curing reaction. Typically,
A curing time of 20 to 30 minutes is required, but according to the method of the present invention, the curing time is shortened to about 10 minutes. After curing, the mold is removed by a conventional method to obtain a molded conductive roller. The conductive roller of the present invention is useful as a conductive roller of an electrophotographic apparatus, but can be applied to conductive rollers having various other uses. When a temperature-sensitive amine catalyst, particularly a diazabicycloamine salt catalyst, is used in the urethane-forming reaction, at a temperature of 70 to 150 ° C., the amine salt liberates diazabicycloamine and exhibits a strong catalytic activity.
Curing is completed, polyurethane elastomer is formed,
When the temperature is further returned to room temperature, it becomes an amine salt again and remains in the formed polyurethane matrix, but it does not exude from the polyurethane elastomer.

[0026]

The present invention will be described by way of examples and comparative examples, which do not limit the scope of the present invention. Parts are parts by weight unless otherwise specified. MW is the molecular weight, f
Represents the number of functional groups.

Example 1 Polypropylene ether glycol (MW = 3000,
f = 2, Sumitomo Bayer Urethane Co., Ltd.) 98 parts,
Polypropylene ether polyol (MW = 400, f
= 4, manufactured by Sumitomo Bayer Urethane Co., Ltd.) and 0.5 part of carbon black were thoroughly mixed and stirred, and then kneaded with a roll to uniformly disperse the carbon black in the polyol component.

Then, DBU was added to this mixture as a catalyst.
-0.3 parts of phenol salt (manufactured by San-Apro Co., Ltd.) was added and stirred to disperse the catalyst. After the mixture became uniform, it was dehydrated under reduced pressure at 40 ° C. and a pressure of 3 Torr or less for 5 hours.

A metal cored bar (rotating shaft) coated with an adhesive on the outer periphery was set in a roller mold heated to 80 ° C. Next, modified MDI (SI-0389, manufactured by Sumitomo Bayer Urethane Co., Ltd.) was added to and mixed with the polyol mixture prepared as described above, followed by stirring with an agitator. The liquid temperature during stirring was set to 40 ° C. After the stirring was completed, the reactive mixture was poured into a mold preheated to 80 ° C. and reaction-cured for 10 minutes to obtain a roller molded body having a polyurethane elastomer formed on the outer periphery of the rotating shaft. This was removed from the mold, left to dry at room temperature for 1 day, and then surface-polished with a grinder to obtain a conductive roller.

Example 2 The amount of DBU-phenol salt added in Example 1 was adjusted to 0.
A conductive roller was manufactured in the same manner as in Example 1 except that 5 parts were used.

Example 3 Instead of the DBU-phenol salt in Example 1, DB was used.
A conductive roller was manufactured in the same manner as in Example 1 except that 0.3 part of U-formate (manufactured by San-Apro Co., Ltd.) was used.

Example 4 Instead of the DBU-phenol salt in Example 1, DB was used.
A conductive roller was manufactured in the same manner as in Example 1 except that 0.3 part of U-octylate (manufactured by San-Apro Ltd.) was used.

Comparative Example 1 A conductive roller was manufactured in the same manner as in Example 1 except that 0.5 part of triethylenediamine (manufactured by Mitsui Toatsu Co., Ltd.) was used instead of the DBU-phenol salt in Example 1. .

Comparative Example 2 In place of the DBU-phenol salt in Example 1, 2-
A conductive roller was manufactured in the same manner as in Example 1 except that 0.3 part of methylimidazole (manufactured by San-Apro Co., Ltd.) was used.

Comparative Example 3 Instead of the DBU-phenol salt in Example 1, DB was used.
A conductive roller was manufactured in the same manner as in Example 1 except that 0.3 part of U (manufactured by San-Apro Co., Ltd.) was used alone.

Comparative Example 4 Instead of the DBU-phenol salt in Example 1, DB was used.
A conductive roller was manufactured in the same manner as in Example 1 except that 0.3 part of N (manufactured by San-Apro Co., Ltd.) was used alone.

Photoconductor Contamination Test Each roller of the above Examples and Comparative Examples was left pressed for one week in an atmosphere of a temperature of 35 ° C. and a humidity of 85% while being pressed against the photoconductor for a copying machine. The contamination of the photoreceptor was observed with the naked eye in each case. Table 1 shows the results.

[0038]

[Table 1]

In the example of Comparative Example 4, dissolution of the surface of the photosensitive member was partially observed.

[0040]

The conductive roller of the present invention has the advantage of using a temperature-sensitive catalyst during the polyurethane reaction.
Not only the exudation of the catalyst from the roller at the use environment temperature of the roller is substantially completely suppressed, but also in the curing reaction, remarkable catalytic activity is expressed by the temperature rise, and the curing reaction is completed promptly.

Since the curing time is shortened in this way, the reaction,
The cycle time for curing and demolding is shortened, the mold rotates faster, and productivity is improved.

Moreover, the conductive roller of the present invention does not contaminate the photoconductor even if it is incorporated in an electrophotographic apparatus and used for a long period of time.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Internal reference number FI Technical display location G03G 15/08 501 G03G 15/08 501D (72) Inventor Shinichi Murakami 3-13 Kuguchi, Amagasaki City, Hyogo Prefecture No. 26 Sumitomo Bayer Urethane Co., Ltd. (72) Inventor Masanori Nagayasu 3-13-26 Kukuchi, Amagasaki City, Hyogo Prefecture Sumitomo Bayer Urethane Co., Ltd.

Claims (4)

[Claims] 1. A conductive roller having a rotating shaft and a conductive elastic layer concentrically provided on the outer periphery of the rotary shaft, wherein the conductive elastic layer contains a reactive mixture containing a polyisocyanate, a polyol and a conductivity-imparting agent. ) A conductive roller comprising a polyurethane elastomer obtained by reaction curing in the presence of a diazabicycloamine salt catalyst represented by Embedded image (In the formula, n is 3, 4, 5 or 6, and A is a residue of an acid which forms a salt with diazabicycloamine.) 2. The diazabicycloamine of the general formula (1) is 1,8-diazabicyclo (5,4,0) -undecene-7 or 1,5-diazabicyclo (4,3,0) -nonene-5. The conductive roller according to claim 1, wherein 3. A of the general formula (1) is octylic acid, oleic acid, p-toluenesulfonic acid, formic acid, phenol,
The conductive roller according to claim 1, which is a residue of orthophthalic acid, acetic acid, maleic acid or boric acid. 4. The conductive roller according to claim 1, wherein both the polyisocyanate and the polyol are liquid at room temperature.