JP2000029307A - Developing blade for electrophotographic device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a developing blade for an electrophotographic device having a blade member which has low hardness and physical properties of low temp. dependency and which is excellent in frictional electrification characteristics, peelability from toner, wear resistance and durability. SOLUTION: In the developing blade for the electrophotographic device which is constituted by adhering the blade member to a supporting body, the blade member consists of a polyurethane elastomer which is a reaction product of a polyol compound and a polyisocyanate compound. The polyol compound consists of a blend body of polydimethylsiloxane and polypropylene glycol having active hyrogens at least at both terminals of a molecule.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing blade for an electrophotographic apparatus in which a blade member made of a polyurethane elastomer is adhered to a support.

[0002]

2. Description of the Related Art In a developing section of an electrophotographic apparatus such as a copying machine, a facsimile, a printer, etc., a thinning blade for thinning a toner by frictional charging with a developing roller, and a photosensitive member and / or an intermediate transfer member A cleaning blade is used to scrape off the residual toner on the surface, clean these surfaces, and use the electrophotographic apparatus process repeatedly. As such a blade, a blade composed of a blade member made of polyurethane elastomer or silicone elastomer and a support is generally used.

[0003] In recent years, such a blade member has been required to have excellent triboelectric charging characteristics in order to demagnetize the toner. For this reason, the surface of a blade member made of a polyurethane elastomer is coated with a toner material such as nylon or the like which is easily charged with a negatively charged polymer, or the material of the blade member is replaced with silicone rubber which is easily charged with a negatively charged toner. A response was being made.

However, the means for coating the surface of the blade member with a polymer substance has a problem in that the coating process is complicated, and it is difficult to coat the blade member edge portion. In addition, when the material of the blade member is replaced with silicone rubber, the silicone rubber has excellent charging characteristics, but its wear resistance is remarkably inferior, so it cannot be used for high-speed machines used in business with a large number of copies. there were.

On the other hand, in recent years, the melting point of the toner itself has decreased due to a decrease in the fixing temperature of the toner, and the toner is liable to be mechanically damaged.

However, if the hardness of the blade member made of the polyurethane elastomer is reduced, tackiness is generated in the polyurethane elastomer itself, and the adhesion to the toner is increased, so that the durability is reduced. Therefore, it was not easy to manufacture a blade member having low hardness and excellent releasability from toner.

[0007] Assuming that the office is in summer or winter, there is no problem because air conditioning is performed every day, but there are many cases where air conditioning is not performed at night or early in the morning. In particular, since the facsimile functions at night and on holidays, it is necessary that the blade member has little change in physical properties under an environment of 5 to 35 ° C. At present, a blade member that can be favorably used in many environments has not been realized yet.

[0008]

SUMMARY OF THE INVENTION In view of the above, the present invention has low hardness, low temperature dependence of physical properties, and is excellent in triboelectric charging characteristics, releasability from toner, abrasion resistance and durability. It is an object of the present invention to provide a developing blade for an electrophotographic apparatus having a blade member.

[0009]

A first aspect of the present invention is a developing blade for an electrophotographic apparatus having a blade member adhered to a support, wherein the blade member is formed by reacting a polyol compound with a polyisocyanate compound. Consisting of a polyurethane elastomer, the above polyol compound,
A blade for an electrophotographic device, comprising a blend of polydimethylsiloxane having active hydrogen at least at both ends of molecules and polypropylene glycol.

A second aspect of the present invention is a developing blade for an electrophotographic apparatus comprising a blade member adhered to a support, wherein the blade member is made of a polyurethane elastomer which is a reaction product of a polyol compound and a polyisocyanate compound. Wherein the polyol compound is a polydimethylsiloxane having active hydrogen at least at both ends of the molecule,
A blade for an electrophotographic apparatus, which is a copolymer with a polyether compound or a polyester compound.

A third aspect of the present invention is a developing blade for an electrophotographic apparatus comprising a blade member adhered to a support, wherein the blade member comprises a polyurethane elastomer which is a reaction product of a polyol compound and a polyisocyanate compound. Wherein the polyol compound comprises a polydimethylsiloxane having a reactive group having active hydrogen at least at both ends of the molecule, and a blend of a copolymer of the polydimethylsiloxane and a polyether compound or a polyester compound. And a blade for an electrophotographic apparatus. Hereinafter, the present invention will be described in detail.

A developing blade for an electrophotographic apparatus according to the first aspect of the present invention comprises a blade member adhered to a support, and the blade member is made of a polyurethane elastomer which is a reaction product of a polyol compound and an isocyanate compound. Become. The polyol compound comprises a mixture of polydimethylsiloxane having at least both ends reactive hydrogen with an isocyanate and active hydrogen and polypropylene glycol.

The polydimethylsiloxane includes, for example, polydimethylsiloxane represented by the following general formula (4).

Embedded image (In the formula, n is an integer of 10 to 38, and R represents an alkylene group.) As the alkylene group, for example,
Examples include a methylene group, an ethylene group, and a propylene group.

The number average molecular weight of the polypropylene glycol is preferably from 1,000 to 3,000. If the number average molecular weight exceeds 3,000, the compatibilizing range (molecular weight of polydimethylsiloxane, blend ratio) becomes narrow, and the compatibilizing effect cannot be sufficiently exhibited. If the molecular weight is less than 1,000, the compatibility becomes better, but the molecular weight between the cross-linking points between the polypropylene glycols becomes smaller, and the chains cannot move freely, resulting in impaired low-temperature properties and a lower hardness cannot be achieved.

The above-mentioned polydimethylsiloxane and the above-mentioned polypropylene glycol can be blended in any ratio. Therefore, when more importance is placed on triboelectric charging, the blending ratio of polydimethylsiloxane can be increased, and when abrasion resistance is more important, the blending ratio of polypropylene glycol can be increased.

The isocyanate component is not particularly restricted but includes, for example, aromatic isocyanates, aliphatic isocyanates and alicyclic isocyanates. Specific examples include, for example, p-phenylene diisocyanate, 1,5-naphthalene diisocyanate, 4,4'-diphenylmethane diisocyanate, tolylene diisocyanate (including a mixture of isomers), toluidine diisocyanate, 1,4-cyclohexane diisocyanate, , 6-hexanediisocyanate,
Examples include isophorone diisocyanate.
These may be used alone or in combination of two or more.

Normally, polydimethylsiloxane having active hydrogen alone has low compatibility with isocyanate. Therefore, when both are mixed and cured, they are separated from each other before curing, and the resulting product is obtained. In some cases, the elastomer itself may have a non-uniform structure or may have partial curing failure. In addition, the viscoelastic behavior of the elastomer having such a macro-phase-separated structure shows a behavior independent of its components. In addition, the behavior derived from polydimethylsiloxane chains, which are excellent in low-temperature properties, appeared at low temperatures, and the structure derived from urethane chains appeared at temperatures around room temperature, so that the temperature dependence of physical properties near room temperature was significantly increased. . Furthermore, crystallization of urethane chains occurs due to macro phase separation, and the resulting elastomer tends to be cloudy, opaque and of high hardness.

However, since the above polypropylene glycol has a methyl group in the side chain and has a structure relatively similar to polydimethylsiloxane, it is naturally compatible with polydimethylsiloxane having active hydrogen, and is not limited to isocyanate. Good compatibility with Therefore, it can act as a compatibilizer for both the siloxane component and the isocyanate.

That is, by using the polypropylene glycol as a compatibilizer, the mixture of the polyol and the isocyanate does not exhibit macro phase separation, and the polydimethylsiloxane and the isocyanate react uniformly. The resulting polyurethane elastomer has a low hardness because of its amorphous structure, and has no surface tack due to the effect of the siloxane chain. In addition, the polyurethane elastomer has a urethane bond in the molecular structure, and has acquired the good abrasion resistance of urethane.

Further, the above-mentioned polyurethane elastomer is
Since the siloxane chains are uniformly dispersed, they are charged to + when rubbed. The toner used in the electrophotographic apparatus is-
Although it is common that the blade member is charged to +, it is more advantageous to charge the toner to-,
The triboelectric property possessed by siloxane can be imparted. Furthermore, since the siloxane chains are uniformly dispersed, the polyurethane elastomer has a low friction coefficient,
Since it is excellent in water repellency and oil repellency, the releasability from the toner is improved, and a stable toner thin layer can be formed.

The method for producing the polyurethane elastomer is not particularly limited, and a commonly used production method can be used. For example, a prepolymer method in which a polyol and an isocyanate are preliminarily reacted to form an NCO-terminated prepolymer, and then a low-molecular-weight cross-linking agent, an extender is added, and heat curing is performed as necessary. A one-shot method, a semi-one-shot method in which a part of the polyol component during the production of the prepolymer is crosslinked and an extender component is used, and the like can be mentioned.

As described above, since the conventional method for producing a polyurethane elastomer can be used, it becomes easy to design a compounding system satisfying the function as a blade member.

The developing blade for an electrophotographic apparatus according to the first aspect of the present invention can be obtained, for example, by bonding the above blade member to a support using an adhesive. As the adhesive, a conventionally used adhesive can be used.

The developing blade for an electrophotographic apparatus according to the first aspect of the present invention, as a blade member, has low hardness, low temperature dependence of physical properties, triboelectric charging characteristics, peelability from toner, abrasion resistance and durability. Since a polyurethane elastomer having excellent properties is used, it is suitably used as a regulating blade for charging and thinning the toner. Further, it is suitably used as a cleaning blade for scraping off residual toner on the photoreceptor. When the developing blade for an electrophotographic apparatus according to the first aspect of the present invention is used as a cleaning blade, the uniform distribution of the siloxane component has a low coefficient of friction, which leads to the elimination of an initial reversal trouble without toner and abrasion. Sex life is also increased.

A second aspect of the present invention is a developing blade for an electrophotographic apparatus comprising a blade member adhered to a support, wherein the blade member comprises a polyurethane elastomer which is a reaction product of a polyol compound and a polyisocyanate compound. Wherein the polyol compound is a polydimethylsiloxane having active hydrogen at least at both ends of the molecule,
A blade for an electrophotographic apparatus, which is a copolymer with a polyether compound or a polyester compound.

The developing blade for an electrophotographic apparatus has a blade member adhered to a support, and the blade member is made of a polyurethane elastomer which is a reaction product of a polyol compound and an isocyanate compound.
The above-mentioned polyol compound comprises a block copolymer of polydimethylsiloxane having active hydrogen which reacts with isocyanate at least at both terminals and a polyether compound or a polyester compound.

Examples of the polydimethylsiloxane having active hydrogen at least at both terminals include those similar to the polydimethylsiloxane of the first aspect of the present invention.

The polyether compound is not particularly restricted but includes, for example, polyethylene oxide and polypropylene oxide.

The polyester compound is not particularly restricted but includes, for example, poly (6-hydroxyhexanoic acid).

As the above block copolymer, for example,
Examples include block copolymers represented by the following general formulas (1) to (3).

[0031]

Embedded image (In the formula, n is an integer of 10 to 38, and m is 11 to
57 is an integer, o is an integer of 16 to 25, and p is
Is an integer of 4 to 31. )

As the polyol compound, one kind of the above block copolymer may be used alone, or two or more kinds of the above block copolymers may be blended and used.
In the present invention, another polyol may be blended with the block copolymer.

The above-mentioned other polyols are not particularly restricted but include, for example, polyether polyols such as polyoxyethylene glycol, polyoxypropylene glycol and polybutylene glycol; polycarbonate diols,
Examples thereof include polyester polyols such as neopentyl glycol, polyethylene adipate ester, polyethylene butylene adipate ester, and caprolactone ester diol.

The above-mentioned isocyanate compound is not particularly limited, and examples thereof include those similar to the isocyanate compound of the first aspect of the present invention.

Since the above copolymer has a polyether or polyester having a polar group in the hydrophobic portion of polydimethylsiloxane in the structure, it has excellent compatibility with isocyanate, and further has a good compatibility with other polar polyols. Excellent compatibility. For this reason, the obtained elastomer can have a homogeneous structure.

As the method for producing the polyurethane elastomer, for example, the same method as the production method of the first invention can be mentioned.

The developing blade for an electrophotographic apparatus according to the second aspect of the present invention can be obtained, for example, by bonding the above blade member to a support using an adhesive. As the adhesive, a conventionally used adhesive can be used.

The developing blade for an electrophotographic apparatus according to the second aspect of the present invention has a low hardness, a small temperature dependency of physical properties, a triboelectric charging characteristic, a releasability from toner, abrasion resistance and durability as a blade member. Since a polyurethane elastomer having excellent properties is used, it is suitably used as a regulating blade for charging and thinning the toner. Further, it is suitably used as a cleaning blade for scraping off residual toner on the photoreceptor.

A third aspect of the present invention is a developing blade for an electrophotographic apparatus comprising a blade member adhered to a support, wherein the blade member comprises a polyurethane elastomer which is a reaction product of a polyol compound and a polyisocyanate compound. Wherein the polyol compound comprises a blend of polydimethylsiloxane having active hydrogen at least at both terminals of the molecule, and a copolymer of polydimethylsiloxane and a polyether compound or polyester compound. This is a device blade.

The developing blade for an electrophotographic apparatus has a blade member adhered to a support, and the blade member is made of a polyurethane elastomer which is a reaction product of a polyol compound and an isocyanate compound.
The polyol component comprises a mixture of a polydimethylsiloxane having active hydrogen that reacts with an isocyanate at least at both terminals and a block copolymer of the polydimethylsiloxane and a polyether compound or a polyester compound. The polydimethylsiloxane and the block copolymer constituting the polyol component,
They can be mixed in any ratio, but the mixing ratio (polydimethylsiloxane / block copolymer) is 95 /
5-5 / 95 is preferred. The polydimethylsiloxane and the polydimethylsiloxane constituting the block copolymer may be the same or different as long as they have active hydrogen at least at both ends of the molecule.

Examples of the polydimethylsiloxane include those similar to the polydimethylsiloxane of the first aspect of the present invention.

The polyether compound constituting the block copolymer is not particularly restricted but includes, for example, polyethylene oxide and polypropylene oxide.

The polyester compound constituting the block copolymer is not particularly limited.
-Hydroxyhexanoic acid) and the like.

As the above block copolymer, for example,
Examples include block copolymers represented by the following general formulas (1) to (3).

[0045]

Embedded image (In the formula, n is an integer of 10 to 38, and m is 11 to
57 is an integer, o is an integer of 16 to 25, and p is
Is an integer of 4 to 31. )

The above-mentioned isocyanate compound is not particularly limited, and examples thereof include those similar to the isocyanate compound of the first present invention.

The above-mentioned polyol compound comprises a block copolymer of polydimethylsiloxane and a polyether compound or a polyester compound. The above-mentioned block copolymer may act as a compatibilizer when producing the above-mentioned polyurethane elastomer. Therefore, the polyurethane elastomer can have a homogeneous structure.

That is, by giving a polar group to the block copolymer, the copolymer is compatible with the urethane segment, and the siloxane segment is compatible with the polydimethylsiloxane polyol. In addition, since a copolymer compatible with both of them is present in the same molecular chain, it can serve as an adhesive for two segments having greatly different polarities.

As a method for producing the above-mentioned polyurethane elastomer, the same method as the production method of the first present invention can be mentioned.

The developing blade for an electrophotographic apparatus according to the third aspect of the present invention can be obtained, for example, by bonding the above blade member to a support using an adhesive. As the adhesive, a conventionally used adhesive can be used.

The developing blade for an electrophotographic apparatus according to the third aspect of the present invention is a blade member having a low hardness, a small temperature dependency of physical properties, a triboelectric charging characteristic, a releasability from a toner, abrasion resistance and durability. Since a polyurethane elastomer having excellent properties is used, it is suitably used as a regulating blade for charging and thinning the toner. Further, it is suitably used as a cleaning blade for scraping off residual toner on the photoreceptor.

As described above, the polyurethane elastomer constituting the first, second, and third developing blades for the electrophotographic apparatus of the present invention has a structure in which siloxane chains are homogeneously distributed in the structure thereof. In addition, the charging characteristics and the releasability from the toner can be sufficiently exhibited. Further, since it has a urethane bond and a polyether or polyester structure, the abrasion resistance can be remarkably improved as compared with the conventional silicone rubber.

[0053]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples.

Example 1 KF6001 (hydroxyl value = 59 KOHmg / g) manufactured by Shin-Etsu Chemical Co., Ltd. was used as polydimethylsiloxane polyol. In addition, the molecular weight is 2 as polypropylene glycol.
000 PP2000 manufactured by Sanyo Chemical Industries, Ltd. was used. KF6
After 001 and PP2000 are blended in a molar ratio of 75/25, 2,4-tolylene diisocyanate (manufactured by Nippon Polyurethane Industry Co., Ltd.) is added to 100 parts of the blend polyol so that the molar ratio [(NCO) / (OH)] = 2. , T-1
00) (hereinafter referred to as TDI), and reacted at 70 ° C. for 5 hours under N ₂ atmosphere to obtain NCO
Was 3.7% by weight.

With respect to 100 parts of the obtained prepolymer,
3.6 parts of a mixture of 1,4-butanediol and trimethylolpropane in a 60/40 weight ratio (hereinafter, referred to as a polyol mixture) was added, and after mixing for 2 to 3 minutes so that air was not trapped, The adhesive-treated core was set, the mixture was poured into a mold preheated to 140 ° C., cured for 1 hour, demolded, and after-cured at 110 ° C. for 24 hours. Thereafter, the molded product was cut into a predetermined size to obtain a blade member. The obtained blade member was a yellow-brown translucent soft elastic body.

Example 2 The procedure of Example 1 was repeated, except that PP2000 having a molecular weight of 1,000 and manufactured by Sanyo Chemical Industries, Ltd. was used instead of PP2000. That is, 75/25 of KF6001 and PP1000
With respect to 100 parts of the blend polyol in a molar ratio, TDI was adjusted to 2 so that the molar ratio [(NCO) / (OH)] = 2.
By adding 2.4 g, a prepolymer having an NCO content of 4.1% by weight was similarly obtained. A blade member was obtained in the same manner as in Example 1 except that 4.0 parts of the polyol mixture was added to 100 parts of the prepolymer. The obtained blade member was a yellow-brown translucent soft elastic body.

Example 3 The procedure of Example 1 was repeated, except that PP3000 manufactured by Sanyo Chemical Industries, Ltd. having a molecular weight of 3000 was used instead of PP2000. That is, 75/25 of KF6001 and PP3000
With respect to 100 parts of the blend polyol having a molar ratio, TDI is adjusted to 1 so that the molar ratio [(NCO) / (OH)] = 2.
By adding 6.6 g, a prepolymer having an NCO content of 3.3% by weight was similarly obtained. 3.2 parts of the polyol mixture was added to 100 parts of the prepolymer to obtain a blade member in the same manner as in Example 1. The obtained blade member was a yellow-brown translucent soft elastic body.

Example 4 The procedure of Example 1 was repeated, except that the molar ratio of polydimethylsiloxane to polypropylene glycol was changed to 50/50. That is, KF6001 and PP20
To 100 parts of the blend polyol having a 50/50 molar ratio of 00, 18.1 parts of TDI was added so that the molar ratio [(NCO) / (OH)] = 2, and the NCO content was 3%. A prepolymer of 0.7% by weight was obtained. 3.6 parts of the polyol mixture was added to 100 parts of the prepolymer to obtain a blade member in the same manner as in Example 1. The obtained blade member was a yellow-brown translucent soft elastic body.

Comparative Example 1 The procedure of Example 1 was repeated, except that polybutylene adipate having a molecular weight of 2,000 (Nipporan 4010, manufactured by Nippon Polyurethane Industry) was used instead of PP2000. The resulting blade member was white and relatively hard and had a rough surface.

Comparative Example 2 In place of PP2000, polytetramethylene glycol having a molecular weight of 2,000 (manufactured by Hodogaya Chemical, 2000SN)
The procedure was performed in the same manner as in Example 1 except that was used. The obtained blade member was harder than Comparative Example 1.

In Examples 1 to 4 and Comparative Examples 1 and 2, the hardness, rebound resilience, surface condition, contact angle, and coefficient of static friction of the obtained blade members were evaluated by the following methods.
A running test was performed by the following method. The results are shown in Table 1.

Evaluation methodhardness  It was measured according to JIS A.Rebound resilience  According to JIS K 6255 at 5 ° C, 25 ° C and 35 ° C
Measured.Surface condition  It was evaluated visually and by touch.Static friction coefficient  100mm / min speed with a load of 50g using Haydon
Was used to determine the coefficient of static friction with respect to the PET film.Contact angle  The contact angle with water was measured by the droplet method. Large contact angle
The key is that the surface has a water-repellent siloxane component.
To do so.Running test  Commercially available electrophotographic equipment pre-printed with 5,000 sheets
Performed.

[0063]

[Table 1]

In the running test, 5000 blades were used. However, in Examples 1 to 4, no change in the blade was observed after the completion of 5000 sheets.

In Comparative Examples 1 and 2, the rebound resilience was higher at lower temperatures and lower at higher temperatures, because the elastomer of the blade component showed a macrophase-separated structure, and was derived from a hard segment composed of urethane bonds. This is because the tan δ transition is around room temperature. In addition, the temperature dependence of the rebound resilience increased due to the transition near room temperature. In Comparative Examples 1 and 2, since the hardness of the blade member was high and the toner could not be uniformly thinned, a thin portion of the toner layer was formed on the developing roller, and it is considered that blurring occurred.

In Examples 1 to 4, the reason why the surface properties are smooth is that a macro phase-separated structure is not taken and a homogeneous structure is shown. On the other hand, the rough surface in Comparative Examples 1 and 2 seems to be due to the fact that the siloxane segment and the urethane hard segment formed by macro phase separation have a sea-island structure. That is, the result of the macro phase separation structure is shown similarly to the temperature dependence of the rebound resilience.

Example 5 X-22-4272 manufactured by Shin-Etsu Chemical Co., Ltd. (having a hydroxyl value of 41.3 KOHm) was used as a polydimethylsiloxane having a copolymerized block structure having a polyethylene oxide structure at both ends.
g / g) and dried under reduced pressure at 70 ° C. for 12 hours. Sumitomo N3500 (NCO content: 21.8% by weight) manufactured by Sumitomo Bayer Urethane, which is a trimer of 1,6-hexane diisocyanate, was used as the isocyanate. After adding 0.01 parts of dibutyltin dilaurate as a reaction accelerator to 100 parts of polyol and mixing them in advance, the molar ratio [(NCO) / (OH)] =
14.9 parts of Sumidur N3500 was added to 100 parts of the polyol so as to be 1.05, and after mixing for 2 to 3 minutes so that air was not entrapped, the core metal was set in advance and 1
The mixed solution was poured into a mold preheated to 00 ° C., heated and cured for 90 minutes, taken out of the mold, cooled after cooling at 80 ° C. for 24 hours, and cut into a predetermined size to obtain a blade member. The obtained blade member had transparency.

Example 6 Instead of X-22-4272, X-22-4 manufactured by Shin-Etsu Chemical Co., Ltd. was used as a polydimethylsiloxane having a copolymerized block structure having a polypropylene glycol structure at both ends.
952 (hydroxyl value 36 KOH mg / g) except that the molar ratio [(NCO) / (O
H)] was added to 12.4 parts of Sumidur N3500 with respect to 100 parts of the polyol so as to obtain 1.05 to obtain a blade member. The obtained blade member had transparency.

Example 7 Instead of X-22-4272, Danzol SP50 manufactured by Dainichi Seika Kogyo Co., Ltd. was used as polydimethylsiloxane having a copolymerized block structure having a polycaprolactone structure at both ends.
Except that KF1 (hydroxyl value 23 KOH mg / g) was used, the molar ratio [(NCO) / (O
H)] = 1.05, and 8.3 parts of Sumidur N3500 were added to 100 parts of polyol to obtain a blade member. The obtained blade member had transparency.

Example 8 Danzol SP50KF1 of Example 7 had a molecular weight of 2,000
Polycaprolactone (Placcel 2 by Daicel Chemical)
20) was blended in a 75/25 molar ratio. That is, 100 parts of Danzol SP50KF1, plus 2 parts of Praxel
20 parts were added. In the same manner as in Example 5, 0.01 part of dibutyltin dilaurate was added to 131 parts of the polyol.
After adding 3 parts and mixing in advance, the molar ratio [(NCO) / (O
H)] = 1.05 so that Sumidule N350
0 was added to obtain a blade member. The obtained blade member was slightly cloudy, but had transparency.

Comparative Example 3 Instead of X-22-4272, OH-C ₂ H was added to both terminals.
_{The same} procedure as in Example 5 was carried out except that a normal polydimethylsiloxane polyol having a _4- OC ₃ H ₆ structure, KF6002 (hydroxyl value: 36 KOHmg / g) manufactured by Shin-Etsu Chemical Co., Ltd. was used. And the molar ratio [(NCO) /
(OH)] = 1.05.
Then, the solution was poured into a mold preheated to 100 ° C. and cured as in Example 5. When the mold was removed after 90 minutes, the lower surface of the blade member was cloudy and bumpy, but was hardened, but the upper portion was slightly light white with a tacky state, and a sample for evaluation was not obtained.

Comparative Example 4 A molar ratio [(NCO) / (O) was obtained in the same manner as in Example 8 except that polycaprolactone 100 was used as the polyol.
H)] = 1.05, 20.2 parts of Sumidur N3500 were added to 100 parts of polyol, and a blade member was obtained in the same manner. The obtained blade member was transparent and slightly hard.

Comparative Example 5 A blade member was produced from commercially available addition-reaction silicone having a hardness of 30A.

In Examples 5 to 8 and Comparative Examples 3 to 5, the evaluation methods used in Examples 1 to 4 and Comparative Examples 1 and 2 for the hardness, surface condition, contact angle and static friction coefficient of the obtained blade members were used. Was evaluated in the same manner as described above. A running test was performed by the following method. The results are shown in Table 2.

Evaluation methodRunning test  A commercial electrophotographic apparatus pre-printed with 6000 sheets
Performed.

[0076]

[Table 2]

The reason why the tack was left on the upper part in Comparative Example 3 was that the isocyanate and the polyol were separated during the heat curing.
The lower part is in a state containing more isocyanate, the upper part is in a state containing less isocyanate, and the molar ratio of the upper part [(NCO) /
(OH)] was much lower than 1 and the terminal OH group became excessively large, so that the upper portion was not completely cured and the tack remained. Further, it is considered that the reason why the white and bumpy powder was formed was that the polyol and the isocyanate were not compatible, and the siloxane component and the urethane component were macro-phase separated to have a sea-island structure.

In Comparative Example 4, fogging occurred early because the absence of the siloxane component and the surface urethane component resulted in poor triboelectric charging characteristics, the toner was not sufficiently charged, and the non-image area was charged. It is probably caused by low toner spattering during development. In the case of the ordinary silicone rubber of Comparative Example 5, the evaluation was good up to 3000 sheets, but the density unevenness occurred thereafter. When the developing section was disassembled, the contact area between the blade and the developing roller was worn as if it were cut off, and it was impossible to form a uniform toner layer, resulting in thick and thin portions of toner. Seem.

Example 9 KF6001 as polydimethylsiloxane polyol
Was used. Danzol SP75KF3 (manufactured by Dainichi Seika Kogyo Co., Ltd.) having a polycaprolactone structure at both terminals as a copolymerized polydimethylsiloxane polyol (hydroxyl value = 1)
(4.5 KOH mg / g). These polyols were blended in a 75/25 molar ratio. 4,4-Diphenylmethane diisocyanate (Millionate MT, manufactured by Nippon Polyurethane Industry Co., Ltd.) (hereinafter referred to as MDI) was used in a molar ratio [(NCO) /
(OH)] = 2, and reacted at 70 ° C. for 3 hours under an N ₂ atmosphere to obtain a prepolymer having an NCO content of 2.2% by weight. 2.1 parts of a polyol mixture was added to 100 parts of the obtained prepolymer,
Air was mixed so as not to entrap for 3 minutes, a core was set in advance, poured into a mold preheated to 140 ° C., and cured for 1 hour. After removal from the mold, after-curing at 80 ° C. for 24 hours, cooling, and cutting to a predetermined size, a blade member was obtained.

Example 10 The procedure of Example 1 was repeated except that the blend ratio of the polyol was changed to 50/50. That is, 10.4 parts of MDI was added to 100 parts of the mixed polyol to similarly obtain a prepolymer having an NCO content of 1.6% by weight. Prepolymer 1
1.5 parts of a polyol mixture was added to 00 parts, and a blade member was similarly obtained.

Example 11 Instead of the prepolymer method in Example 9, a one-shot method was used in which a polyol and a polyol mixture were mixed in advance and then MDI was added, followed by mixing for 2 to 3 minutes to obtain a blade member in the same manner.

Example 12 Instead of Danzol SP75KF3, X-22-42 was used.
Example 9 was repeated except that 72 was used. That is, 7
23.7 parts of MDI was added to 100 parts of the blend polyol having a molar ratio of 5/25, and a prepolymer having an NCO content of 3.2% by weight was obtained in the same manner. To 100 parts of the obtained prepolymer, 3.1 parts of a polyol mixture was added, and a blade member was obtained in the same manner.

Example 13 Instead of Danzol SP75KF3, X-22-49 was used.
Same as Example 9 except that No. 52 was used. That is, 7
22.6 parts of MDI was added to 100 parts of the blend polyol having a molar ratio of 5/25 to obtain a prepolymer having an NCO content of 3.1% by weight. The obtained prepolymer 10
Three parts of the polyol mixture was added to 0 parts to obtain a blade member in the same manner.

Comparative Example 6 The procedure of Example 9 was repeated except that no copolymer type polyol was used. That is, 26.3 parts of MDI was added to 100 parts of KF6001, and the NCO content was 3.
4% by weight of prepolymer was obtained. To 100 parts of the obtained prepolymer, 3.4 parts of the polyol mixture was added, and a blade member was obtained in the same manner.

Comparative Example 7 The procedure of Comparative Example 6 was repeated except that the one-shot method was used instead of the prepolymer method. After curing at 140 ° C. for 1 hour, the mold was demolded, but was not cured. Therefore, after-curing was carried out in Example 9 as it was, that is, heating was performed at 80 ° C. for 24 hours. After 24 hours, the mixture in the mold was not cured, and no blade member was obtained.

Comparative Example 8 The procedure of Example 9 was repeated except that the polyol was changed to a normal polyethylene adipate having a molecular weight of 2,000.

Comparative Example 9 A blade member was manufactured from a commercially available addition reaction type silicone rubber having a hardness of 40A.

In Examples 9 to 13 and Comparative Examples 6 to 9,
The hardness of the obtained blade member, the surface state, the evaluation of the contact angle and the coefficient of static friction and the execution of the running test, Example 5
8. The same method as that used in Comparative Examples 3 to 5 was used.
The results are shown in Table 3.

[0089]

[Table 3]

It is considered that the reason why the density unevenness occurred in Comparative Example 6 in the initial stage was that the toner layer between the blade and the roller became non-uniform because the surface property was not smooth. In addition, it is considered that the fusion of the toner was observed because the damage to the toner was large due to the high hardness. In Comparative Example 7, the components were separated during heat curing, and the molar ratio [(NC
O) / (OH)].

In Comparative Example 8, since the siloxane component was not contained because of ordinary polyurethane, the toner could not be charged sufficiently, and it was considered that a fog image was generated. Further, since the hardness was high and the water repellency was poor, the fusion of the toner was remarkable as compared with Comparative Example 6. The silicone rubber of Comparative Example 4 exhibited a sufficient function when the number of prints was small. However, when the number of prints was large without abrasion resistance, abrasion occurred at the contact portion with the developing roller, and proper toner regulation could not be performed. It seems that unevenness has occurred.

[0092]

According to the first, second and third aspects of the present invention, in any case, the hardness is low, the temperature dependence of physical properties is small, and the frictional charging characteristics and toner It is possible to provide a developing blade for an electrophotographic apparatus having a blade member having excellent peelability, abrasion resistance and durability.

Claims (7)

[Claims] 1. A developing blade for an electrophotographic apparatus, wherein a blade member having excellent triboelectric charging characteristics and abrasion resistance is adhered to a support. 2. A blade member comprising a polyurethane elastomer which is a reaction product of a polyol compound and a polyisocyanate compound, wherein the polyol compound is a blend of polydimethylsiloxane and polypropylene glycol having active hydrogen at least at both ends of the molecule. The blade for an electrophotographic apparatus according to claim 1, comprising: 3. The electrophotographic blade according to claim 1, wherein the polypropylene glycol has a number average molecular weight of 1,000 to 3,000. 4. The blade member is made of a polyurethane elastomer which is a reaction product of a polyol compound and a polyisocyanate compound, wherein the polyol compound comprises a polydimethylsiloxane having active hydrogen at least at both ends of the molecule, a polyether compound or 2. The blade for an electrophotographic apparatus according to claim 1, comprising a copolymer with a polyester compound. 5. A blade member comprising a polyurethane elastomer which is a reaction product of a polyol compound and a polyisocyanate compound, wherein the polyol compound comprises a polydimethylsiloxane having active hydrogen at least at both ends of a molecule; 2. The blade for an electrophotographic apparatus according to claim 1, comprising a blend of a copolymer of a siloxane and a polyether compound or a polyester compound. 6. A copolymer of a polydimethylsiloxane having active hydrogen at least at both ends of the molecule and a polyether compound or a polyester compound is represented by the following general formula (1):
The electrophotographic blade according to claim 4, wherein the compound is a compound represented by the following formula (3). Embedded image In the formula, n is an integer of 10 to 38, and m is 11 to 5
7, o is an integer of 16 to 25, and p is
Is an integer of 4-31. 7. The control blade according to claim 1, wherein the blade is a regulating blade for charging and thinning the toner in the developing section.
7. The developing blade for an electrophotographic apparatus according to 5 or 6.