JPH09274416A - Blade for electrophotographic device and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To lessen the contamination of a metal mold, to enable iterative parting from the mold and to prevent the adhesion of a parting material by using a polyurethane sheet obtd. by adding specific amts. of a crosslinking agent and reaction accelerator to a prepolymer consisting of a specific compsn. SOLUTION: The prepolymer is formed by mixing the diisocyanate compd. of the amt. at which the content of isocyanate groups attains 5 to 20% with the polyol mixture formed by mixing bifunctional high-polymer polyol having a number average mol.wt. of 1000 to 3000 and trifunctional polyol having a number average mol.wt. of 92 to 980 in such a manner that the average functional group number attains 2.02 to 2.20. While uncured polyurethane is prepd. by continuously mixing the crosslinking agent of the atm. at which the equiv. ratio of OH groups/NCO groups is 0.90 to 1.05 and the reaction accelerator of 0.01 to 1.0 pts.wt., more preferably 0.05 to 0.5 pts.wt. per 100 pts.wt. prepolymer at prescribed ratios with the prepolymer, the uncured polyurethane is cast into the high-temp. metal mold and is cured, by which a polyurethane sheet is obtd.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cleaning blade for removing residual toner on a photosensitive drum in an electrophotographic copying machine, a printer, a facsimile, or the like, or friction charging of toner in a developing machine. However, the present invention relates to a developing blade for forming a thin film and the like, and a blade for an electrophotographic apparatus using a thermosetting polyurethane sheet, and a manufacturing method thereof.

[0002]

2. Description of the Related Art As shown in FIG. 2A, a blade 1 for an electrophotographic apparatus of this type has an elongated metal plate 3 having a V-shaped cross section.
Similarly, an elongated polyurethane sheet 2 (called a blade) is bonded to a (holder), and the tip of the blade 2 which is not bonded to the holder 3 is linearly cut by a sharp blade to form a sharp ridge line. ing. In addition,
As shown in the sectional view of FIG. 2B, when the electrophotographic apparatus blade 1 is used as a cleaning blade, the blade 2 is adhered to the holder 3 with an adhesive 63, and the tip portion of the blade 2 is attached. The drum-side ridgeline 60 (cut surface) is in contact with the outer peripheral surface of the photosensitive drum 61. By rotating the photosensitive drum 61 in the direction of the arrow x, the residual toner 62 attached to the outer peripheral surface of the photosensitive drum 61 is scraped off by the drum side ridge line 60.

Generally, the blade 2, which is a thermosetting polyurethane elastomer, is manufactured by the following method. One is a method called a centrifugal molding method shown in FIG. 3 (a), in which a mixture of a urethane prepolymer having a terminal isocyanate premixed with a cross-linking agent (polyol etc.) is formed on the inner surface of a rotating hollow drum 51. A is injected, and heating is continued for a predetermined time to cause reaction to form a large-sized cylindrical polyurethane sheet. A molded product is taken out from the drum 51, cut out, subjected to a secondary cross-linking and an aging step to form a large-sized polyurethane sheet B, and cut into a predetermined size to obtain a flat blade 2 (see FIG. 3 (b)). Further, the blade 2 is adhered and fixed to a holder 3 made of metal, which is a support, to obtain a blade 1 for an electrophotographic apparatus (see FIG. 2 (a)).

As another method, which is called a molding method, as shown in FIG. 3 (c), a metal holder 3 which has been previously treated with an adhesive is set in predetermined molds 55 and 56,
For a predetermined time by injecting a mixture of a premixed urethane prepolymer having a terminal isocyanate group and a crosslinking agent,
The blade 2 is obtained by continuing heating and molding integrally. Next, the blade 2 is taken out of the mold, subjected to secondary cross-linking, and subjected to an aging step to be cut into a predetermined size and completed.

The third method is disclosed in Japanese Patent Application Laid-Open No. 7-
There is a method called a belt-shaped continuous molding method proposed in No. 334060. As shown in FIG. 1, the urethane prepolymer having a terminal isocyanate group prepared in the reaction vessel 11 and the cross-linking agent prepared in the reaction vessel 12 are continuously mixed at a predetermined ratio by a quantitative mixing casting machine 17. The mixture is discharged into a groove (not shown) formed on the outer circumference of the rotating molding drum 20 while mixing, and the space formed by the groove and the endless belt 24 is filled with the mixture and heated for a predetermined time to polymerize. Let Since the groove portion has a width and a depth corresponding to the width and thickness of the blade, by pulling out the continuous molded product S in a band shape, cooling it by the cooling roll 25 and the cooling device 31, and cutting it to a predetermined size by the cutting device 37. A flat blade 2 is obtained. Further, this blade is adhesively fixed to a metal holder as a support with an adhesive and then cut into a predetermined size to complete a blade for an electrophotographic apparatus.

The composition of the polyurethane used for the blade is, as shown in JP-A-7-334060, a predetermined amount of polycaprolactone ester diol (number average molecular weight 2000) in a reaction vessel (not shown) at 70 ° C. for 3 hours under reduced pressure. After heating and stirring under lower temperature (5 mmHg) for dehydration, 4,
4-Diphenylmethane diisocyanate is added and stirred at 70 ° C. for 1 to 4 hours under a nitrogen gas atmosphere to prepare a liquid polyurethane prepolymer having a residual isocyanate group content of 16.7%, which is stored in the reaction vessel 11. On the other hand, 70 parts of a predetermined amount of 1,4-butanediol, trimethylolpropane, a high molecular weight polyol and a catalyst were used as the crosslinking agent component.
The cross-linking agent which has been dehydrated by heating and stirring under reduced pressure at 3 ° C. for 3 hours is stored in the reaction container 12. While mixing the prepolymer thus obtained and the cross-linking agent at a predetermined temperature and a predetermined ratio, in the belt-shaped continuous molding method described above, it is cast in the groove portion of the rotary drum and cured to form a polyurethane blade. To do.

[0007]

DISCLOSURE OF THE INVENTION In the above-mentioned blade for electrophotographic apparatus and the manufacturing method thereof, in order to release the cured molded article (blade) from the mold, a mold release agent is applied to the mold. However, a slight amount of the release agent remains on the surface of this blade. When the edge portion of this blade is cut to form a sharp ridge line and the ridge line is brought into contact with the photosensitive drum of the electrophotographic apparatus, the residual release agent is
It may contaminate the photosensitive layer coated on the surface of the photosensitive drum. Further, when the holder is adhered to the surface on which the release agent is adhered, it may cause adhesion failure.

On the other hand, since the mold release property of the blade and the mold is poor, it is necessary to spray and wipe the mold release agent every time when molding this blade or every time when molding this blade several times, which increases man-hours by manual work. . When a mold release agent is repeatedly applied to one mold and used, the mold release agent may be oxidized or may be thermally deteriorated to further reduce the mold releasability. The unreacted low molecular weight component of the polyurethane component is gradually deposited on this, impairing the surface shape (surface roughness, transparency) of the molded product (blade). In addition, using a large amount of release agent causes economic problems,
There is a safety and health problem that the working environment deteriorates. In particular, in the above-mentioned strip-shaped continuous molding method, since a rapid curing type polyurethane having a demolding time of 1 minute or less is used, the number of times the mold is used per unit time increases, which causes problems in terms of quality and productivity. Become.

The present invention has been made in view of the above-mentioned points, and a mold release agent is applied and wiped off before the start of molding to form a minimum required release film, and the mold is contaminated. It is possible to provide a blade for an electrophotographic apparatus in which a mold release agent does not adhere to a molded product (blade), and a method for manufacturing the same, which is capable of repeated mold release.

[0010]

In order to solve the above problems, the blade for an electrophotographic apparatus of the present invention comprises: a) a bifunctional polymer polyol having a number average molecular weight of 1000 to 3000; and a number average molecular weight of A mixed polyol prepared by mixing 92-980 trifunctional polyols in a ratio such that the average number of functional groups is 2.02 to 2.20 and a diisocyanate compound in an amount of 5 to 20% of isocyanate groups. In the polymer, the equivalent ratio of b) OH group / NCO group is 0.1.
A polyurethane sheet obtained by mixing 90 to 1.05 of a cross-linking agent and 0.01 to 1.0 parts by weight of a reaction accelerator with 100 parts by weight of the prepolymer and reacting the mixture is used. .

The number average molecular weight of the bifunctional polyol used is in the range of 1,000 to 3,000. If it is less than 1,000, the resulting urethane rubber becomes too hard to obtain the required physical properties (flexibility). If it exceeds 3000, the viscosity at the time of molding becomes high, and it becomes difficult to perform casting.

Examples of the bifunctional polyols include polyoxyalkylene glycols such as polyethylene glycol, polypropylene glycol and polyoxytetramethylene glycol, or polyether type polyols of bisphenol A and ethylene oxide adduct of glycerin, and adipic acid and phthalic anhydride. , Diphthalic acid such as isophthalic acid, maleic acid, fumaric acid and ethylene glycol,
Propylene glycol, 1,4-butanediol, 1,6-
Examples thereof include polyester type polyols obtained by a polymerization reaction with glycols such as hexanediol and trimethylolpropane, and polycaprolactone diols and polycarbonate diols.

The trifunctional polyol mixed with this has a number average molecular weight of 92 to 980, and when mixed with the above-mentioned bifunctional polyol, the average number of functional groups of the mixed polyol is 2.
It is mixed in a ratio of 02 to 2.20. No suitable material having a trifunctional polyol with a number average molecular weight of less than 92 has been found, and with a polyol having a number average molecular weight of more than 980, the viscosity becomes too high and casting processing becomes difficult. If the average number of functional groups of the mixed polyol is less than 2.02, the amount of three-dimensional crosslinking in the prepolymer described below is too small and the effect of initial curing is small,
If it exceeds 2.20, the three-dimensional cross-linking is excessive and the viscosity becomes too high, and the glass transition point of the blade rises, so that the cleaning property at low temperature becomes poor. Examples of the trifunctional polyol include trimethylolpropane and polycaprolactone ester triol.

The prepolymer prepared by mixing the above-mentioned mixed polyol with an amount of the diisocyanate compound having an isocyanate group content of 5 to 20% has a three-dimensional crosslinked structure of a trifunctional polyol in a part thereof. It is considered that this three-dimensional structure makes it possible to further speed up and form the polyurethane film on the contact surface when the crosslinking agent and the reaction accelerator are mixed and cast in a high temperature mold.
If the content of isocyanate groups in the prepolymer is less than 5%, the resulting polyurethane sheet has few hard segments and has too large a permanent elongation, so that the required physical properties as a blade cannot be obtained. It is too large to perform the function as a prepolymer, resulting in a large variation in the physical properties of the obtained blade (correction with a bifunctional polyol is required).

Examples of the diisocyanate compound include tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, hexanemethylene diisocyanate, isophorone diisocyanate and 1,4-cyclohexanediisocyanate.

A cross-linking agent (such as a polyol described below) in such an amount that the equivalent ratio of OH groups / NCO groups is 0.90 to 1.05 is added to this prepolymer, and 0.01 is added to 100 parts by weight of the prepolymer. To 1.0 parts by weight, preferably 0.05 to 0.5 parts by weight of a reaction accelerator are continuously mixed in a predetermined ratio to prepare an uncured polyurethane, which is cast-cured in a high temperature mold to cure the polyurethane sheet. To get At this time, the crosslinking agent and the reaction accelerator are mixed in advance. Although the mechanism of the polyurethane sheet produced by this composition and procedure is not clear, it does not adhere to the mold even after repeated castings, and unreacted material is raised and fixed on the mold surface. It does not roughen the surface of the polyurethane sheet. In this uncured polyurethane composition, the curing rate greatly changes depending on the temperature, and immediately after contacting the mold at high temperature, the curing reaction starts immediately from the contact surface to form a polyurethane polymer film on the contact surface early. It is considered that this is because it significantly reduces the chances of unreacted substances and short-molecule foreign substances coming into contact with the mold.

When the equivalent ratio of OH group / NCO group is less than 0.90, the amount of the crosslinking agent mixed is less than 0.90, and the resulting polyurethane sheet has too much NCO group residual amount, so that the obtained polyurethane sheet becomes flexible. Mold release becomes more difficult than the mold at an early stage. 1.
When it exceeds 05, the permanent elongation of the polyurethane sheet becomes too large.

As the cross-linking agent, ethylene glycol,
1,4-butanediol, diethylene glycol, 1,6-
Examples thereof include low molecular weight diols such as hexanediol and neopentyl glycol, and diamines such as ethylenediamine, hexamethylenediamine and isophoronediamine. Further, if necessary, trimethylolpropane, triethanolamine, glycerin and their ethylene oxide and propylene oxide adducts may be added as trifunctional components.

If the amount of the reaction accelerator is less than 0.01 part by weight, the reaction promoting effect is small, and if it exceeds 1.0 part by weight, the pot life after mixing until casting becomes too short, and the stirring operation is difficult. There is a problem that the curing reaction proceeds. Further, when the reaction accelerator exceeds 1.0 part by weight and remains in the urethane rubber, the reaction accelerator acts as a plasticizer, and the rubber physical properties of the obtained blade tend to be deteriorated.

The reaction accelerator used in the blade for electrophotographic apparatus according to claim 2 is a 1,8-diazabicyclo (5,4,0) undecene-7-organic acid salt called block amine. 5-diazabicyclo (4,3,0) nonene-5-
Examples thereof include organic acid salts and the like, or mixtures thereof with 2-methylimidazole, 1,2-dimethylimidazole and the like. In addition, the catalytic performance of this block amine is blocked by an organic acid to form a salt, and the catalytic performance is exhibited as soon as it is mixed with the above prepolymer and poured into a high temperature mold. It is a catalyst. This further speeds the formation of the polyurethane polymer film on the contact surface as described above.

In the method for producing a blade for an electrophotographic apparatus according to claim 3, first, a) the number average molecular weight is 1000 to 30.
The content of the isocyanate group in the mixed polyol in which the bifunctional high molecular weight polyol of 00 and the trifunctional polyol having the number average molecular weight of 92 to 980 are mixed in a ratio such that the average number of functional groups is 2.02 to 2.20. To prepare a prepolymer by mixing the diisocyanate compound in an amount of 5 to 20%, and b) an amount of a crosslinking agent in which the equivalent ratio of OH group / NCO group is 0.90 to 1.05. And 0.01 to 1.0 parts by weight of a reaction accelerator with respect to 100 parts by weight of the prepolymer at 40 to 70 ° C. to prepare an uncured polyurethane composition, and c) the uncured polyurethane composition. The product is cast into a mold having a surface temperature of 130 to 160 ° C. and a surface finish roughness of 0.1 μm or less.

This polyurethane production method is also called a quasi-prepolymer method, in which about 15% of unreacted NCO groups are left in the prepolymer state, and a necessary amount of a crosslinking agent is mixed immediately before casting. Curing (in the so-called prepolymer method, a prepolymer having a residual amount of NCO groups of 6 to 7% is mixed with a crosslinking agent and cast to cure). This method based on the quasi-prepolymer method is suitable for incorporating the properties required for a cleaning blade as described in JP-A-5-278045, and is suitable for obtaining a stable polyurethane sheet. In the present invention, which is a further improvement of this quasi-prepolymer method, a mixed polyol obtained by adding a trifunctional polyol to a bifunctional polyol is used as the polyol for the prepolymer. A diisocyanate compound is mixed with this mixed polyol to prepare a prepolymer having a slightly three-dimensional structure. This three-dimensional structure has the effect of promoting the curing of polyurethane at the time of casting, which will be described later.

While premixing the pre-mixed reaction accelerator and cross-linking agent (polyol) with this prepolymer at a relatively low temperature (40-70 ° C.) with a quantitative mixing casting machine, a high temperature (130-160 ° C.) is used. ) Cast into the mold. If the temperature at which the reaction accelerator and the cross-linking agent are mixed with the prepolymer is less than 40 ° C., the viscosity is too high to sufficiently mix them.
If the temperature exceeds ℃, curing progresses during mixing and the viscosity rises, and stable casting work cannot be continued. If the mold temperature is lower than 130 ° C., the reaction accelerator does not dissociate and the effect as a reaction promoting catalyst cannot be exhibited. If it exceeds 160 ° C., the generated polyurethane is deteriorated.

This uncured polyurethane composition is treated at high temperature (1
(30 to 160 ° C.), the curing reaction rapidly proceeds as soon as the uncured polyurethane composition comes into contact with the mold to form a cured polyurethane film on the contact surface.
The low-molecular weight unreacted polyurethane is trapped inside and the crosslinking reaction proceeds.

On the other hand, the molding surface of the mold is also lapped to a mirror surface having a surface roughness of 0.1 μm or less. This is because if the surface roughness exceeds 0.1 μm, foreign matter (decomposition product of the unreacted composition, etc.) is likely to be attached and the surface of the blade may be uneven. In order to carry out this, a steel having a fine structure is used as the material of the mold, and for example, martensitic stainless steel is preferably used.

[0026] As described in claim 4, 1,8-diazabicyclo (5,4,0) undecene-7-organic acid salt, 1,5-diazabicyclo (, which is called a block amine as a reaction accelerator. By using (4,3,0) nonene-5-organic acid salt, the method for producing a blade for an electrophotographic apparatus according to claim 3 can be continuously cast for a longer time.

[0027]

FIG. 1 is a block diagram showing an embodiment of the present invention.
Will be described based on examples. As the molding apparatus used in this example, the manufacturing apparatus 10 used in the strip-shaped continuous molding method which is the third method described in the section of the prior art is used. In the present invention, the forming drum 20
In order to improve the specularity of the molding groove (not shown) (which constitutes the groove corresponding to the width and thickness of the blade that goes around the outer peripheral surface of the molding drum), the material of the molding drum (molding surface) is A martensitic stainless steel material is used and lapped to a mirror surface with a surface roughness of 0.1 μm or less.

[0028]

EXAMPLE Using this manufacturing apparatus 10, a prepolymer having the following composition was prepared in a reaction vessel 11, and a cross-linking agent and a reaction accelerator were prepared and stored in a reaction vessel 12, respectively, and a fixed quantity mixed casting mold was prepared. While the two are continuously mixed by the machine 17, they are cast into the molding groove portion of the molding drum 20, heat-cured, taken-off and cooled to obtain a polyurethane sheet to prepare a blade for an electrophotographic apparatus. Examples 1 to 8 and Comparative Example 10 were changed by changing the kind of the polyol, and changing the amount and the amount of the diisocyanate compound and the reaction accelerator.
~ 13 were carried out.

Examples 1 to 6 Polycaprolactone ester diol (number average molecular weight 2000) as a bifunctional polyol and polycaprolactone ester triol (number average molecular weight 850) as a trifunctional polyol were obtained at a predetermined ratio (mixed and obtained. The mixed polyol was charged in a reaction container (not shown) so that the average number of functional groups of the obtained mixed polyol would be a “number of functional groups” in Table 1 described below (varied depending on the example), and the mixture was heated at 70 ° C. for 3 hours.
After dehydration by heating and stirring under reduced pressure (5 mmHg),
A predetermined amount of 4,4'-diphenylmethane diisocyanate (amount at which the content of isocyanate groups becomes 15.6% after the reaction) was added to the reaction vessel, and the mixture was heated to 70 ° C under a nitrogen gas atmosphere.
The prepolymer obtained by stirring at 1 to 4 hours in the reaction vessel 11
Transfer to and store.

On the other hand, 6.58 parts by weight of 1,4-butanediol, 4.39 parts by weight of trimethylolpropane and 100 parts by weight of polycaprolactone ester diol (number average molecular weight of 2000) were placed in a reaction vessel (not shown). 70 ° C
For 3 hours under reduced pressure (5 mmHg) under heating and stirring to dehydrate to prepare a cross-linking agent. With this cross-linking agent, 1,2-dimethylimidazole and 1,8-diazabicyclo (5,4,0) undecene- A reaction accelerator prepared by mixing 7-organic acid salt in a ratio of 1: 1
0.33 parts by weight (“promoter amount” in Table 1) was added and stirred, transferred to the reaction vessel 12 and stored.

The prepolymer thus obtained and the mixture of the cross-linking agent and the reaction accelerator were used in the case where the equivalent ratio of NCO groups / OH groups of the polyurethane after curing was "Equivalent ratio" in Table 1.
(2) ”is supplied to the quantitative mixing casting machine 17 by the metering pumps 13 and 14 and uniformly stirred and mixed, and the temperature is adjusted to 145 ° C. from the discharge port and the peripheral speed is 2 m / min. It is poured into the molding groove of the molding drum 20. A belt-shaped polyurethane sheet (blade) having a predetermined shape was continuously prepared by the cavity formed by the molding groove and the endless belt 24, and its repetitive mold releasability and mold stain resistance were evaluated. Was evaluated for physical properties.
The repetitive mold release property evaluates the degree of difficulty when the prepared blade is separated from the mold, and the mold contamination property evaluates the state of adhesion of decomposed products and foreign substances to the mold surface. As for the physical properties, the tensile elastic modulus (elastic modulus) and the permanent elongation (elongation) are determined by JIS, K-63.
It is evaluated according to 01.

The mold release agent is a fluororesin-based mold release agent manufactured by Asahi Glass Co., Ltd. under the trade name of MoldSpat MRK-66.
0 is impregnated into a fluff-free cleaning room waste cloth before the molding work is started, and is applied to the surface of the molding drum 20, and then wiped with a dry waste cloth evenly while wiping off the excess release agent. It was molded without supplementing the mold.

Example 7 The mixed polyol and the bifunctional polyol as the main component of the crosslinking agent were changed from polycaprolactone ester diol (number average molecular weight 2000) to polybutylene adipate diol (number average molecular weight 2000), and the average functionality of the mixed polyol was changed. A polyurethane sheet was prepared with the same composition and production method as in Example 6 except that the number of bases was 2.05 and the trifunctional% was 2.2, and was evaluated in the same manner.

Example 8 The bifunctional polyol as the main component of the mixed polyol and the cross-linking agent was changed from polycaplacton ester diol (number average molecular weight 2000) to polyethylene adipate diol (number average molecular weight 2000), and the average functionality of the mixed polyol was changed. A polyurethane sheet was prepared with the same composition and production method as in Example 6 except that the number of bases was 2.05 and the trifunctional% was 2.2, and was evaluated in the same manner.

Comparative Examples 10 to 12 Mixed polyols and bifunctional polyols as main components of the cross-linking agent, Comparative Example 10 is polycaprolactone ester diol (number average molecular weight = 2000), Comparative Example 11 is polybutylene adipate diol (number average). Molecular weight = 200
0) and Comparative Example 12 were polyethylene adipate diols (number average molecular weight = 2000), and did not contain trifunctional polyols (caprolactone ester triols contained in Examples 1 to 8 (number average molecular weight 850)) (hence, The average number of functional groups is 2.00). Further, as the reaction accelerator, only the imidazole derivative such as 2-methylimidazole and 1,2-dimethylimidazole was used, and the 1,8-diazabicyclo (5,4,
0) A polyurethane sheet was prepared in the same manner as in Example 6 except that undecene-7-organic acid salt or the like was not used and evaluated in the same manner. Comparative Example 13 A polyurethane sheet was prepared in the same manner as in Example 1 except that the OH group / NCO group equivalent ratio (equivalent ratio (2)) of the polyurethane after completion of curing was 0.85 and evaluated in the same manner. did.

The above examples and comparative examples are summarized in Table 1 by comparing their numbers and compositions.

[Table 1] Formulation No. Type Kind Number of functional groups 3 Functional% Equivalent ratio (1) Equivalent ratio (2) Amount of accelerator Example 1 PCL-2 2.11 5.0 8.47 1.05
0.33 Example 2 PCL-2 2.20 9.6 8.19 1.00 0.33 Example 3 PCL-2 2.20 9.0 8.19 0.90 0.33 Example 4 PCL-2 2.02 0.9 8.73 0.90 0.33 Example 5 PCL-2 2.02 0.9 8.73 1.00 0.33 Example 6 PCL-2 2.11 5.0 8.47 0.95 0.33 Example 7 PBA-2 2.05 2.2 8.65 0.95 0.33 Example 8 PEA-2 2.05 2.2 8.65 0.95 0.33 Comparative Example 10 PCL-2 2.00 0 8.80 0.95 0.33 (* 1) Comparative Example 11 PBA- 2 2.00 0 8.80 0.95 0.33 (* 1) Comparative example 12 PEA-2 2.00 0 8.80 0.95 0.33 (* 1) Comparative example 13 PCL-2 2.11 5.0 8.47 0.85 0.33 The following contents are displayed in the table. . (Note 1) In the “Type” section, the types of bifunctional polyols are abbreviated, and the abbreviations are as follows: PCL-2; polycaprolactone ester diol (number average molecular weight = 2000) PBA-2; poly Butylene adipate diol (number average molecular weight = 2000) PEA-2; polyethylene adipate diol (number average molecular weight = 2000). (Note 2) The “functional group number” section indicates the average number of functional groups of the mixed polyol obtained by mixing the bifunctional polyol with the trifunctional polyol. In the section "3 functional%", the weight% of the trifunctional polyol with respect to this mixed polyol is shown. (Note 3) In the “equivalent ratio (1)” section, the equivalent ratio of NCO groups / OH groups in the prepolymer prepared by mixing the diisocyanate compound with the mixture of the bifunctional polyol and the trifunctional polyol is shown. (Note 4) In the “equivalent ratio (2)” section, the equivalent ratio of NCO groups / OH groups in the polyurethane in which the crosslinking reaction has been completed by varying the amount of the crosslinking agent in the prepolymer and mixing is shown. . (Note 5) In the "promoter amount" section, the amount of the reaction accelerator mixed with the above-mentioned crosslinking agent is shown, and the weight part of the reaction accelerator is shown with respect to 100 parts by weight of the bifunctional polyol used as the crosslinking agent. (* 1) uses only imidazole derivative.

Each of the compositions shown in Table 1 was subjected to strip-shaped polyurethane sheet (blade before cutting) by the strip-shaped continuous molding method described in the section of the prior art using the manufacturing apparatus 10 (see FIG. 1). I made a prototype. In each example, the casting conditions are: liquid temperature = 60 ° C. for prepolymer, 60 ° C. for cross-linking agent Mold isothermal temperature = 145 ° C. for molding drum, 25 ° C. for cooling roll Preheating time from discharge port a to belt contact point b = 10 seconds Heat retention time from belt contact point b to release point c = 50
The peripheral speed of the molding drum 20 was set to 2 m / min. Table 2 shows the evaluation of the difficulty of the casting operation thus performed and the physical properties of the obtained polyurethane sheet.

[Table 2] Evaluation of Casting Work and Physical Properties of Blade No. Repeated Release Mold Contamination of Mold Elasticity Elongation (S) (1H) (2H) (5H) (9H) (S) (1H) ( 2H) (5H) (9H) Mpa% Example 1 ○ ○ ○ ○ ○ ○ ○ ○ ○ 54.5 1.2 Example 2 ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ 55.0 0.2 Example 3 ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ 54.0 0.4 Example 4 ○ ○ ○ △ △ ○ ○ ○ △ △ 48.6 0.6 Example 5 ○ ○ ○ ○ ○ ○ ○ ○ ○ 50.2 0.8 Example 6 ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ 49.8 0.5 Example 7 ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ 52.2 0.7 Example 8 ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ 51.3 0.8 Comparative Example 10 ○ △ × − − ○ △ × − − 44.5 1.0 Comparative Example 11 ○ △ × − − ○ △ × − − 44.7 1.0 Comparative example 12 ○ △ × − − ○ Δ × − − 45.7 1.0 Comparative example 13 ○ △ × − − ○ △ × − − 52.0 0.4 (Note 1) “Elastic modulus” is tensile Shows elastic modulus and "stretch" It shows a permanent growth. (Note 2) “Repeat mold release” evaluates the difficulty of separating the prepared blade from the mold, and “mold contamination” means the state of decomposition products and foreign matter adhered to the mold surface. Evaluate. The symbols in the table have the following meanings. Repeatable mold release ○: It can be released without problems △: It is difficult to release, and it cannot be released without pulling the molding sheet ×: Cannot be released Mold contamination ○: No deposit on the mold △: Mold Deposition is started and light fog is observed. ×: Fogging occurs over the entire mold (Note 3) (S) indicates the evaluation at the start of molding, H indicates time, and (1H) indicates after 1 hour. Shows the evaluation of.

As described above, in any of the examples, the average number of sensitive groups of the polyol used for the prepolymer was 2.02 to 2.20, and the mixed prepolymer and OH group / NCO of the crosslinking agent were used. The equivalent ratio of the groups (equivalent ratio (2)) was 0.90 to 1.05, and good repeatability and mold contamination could be obtained even after 10 hours from the start of the casting operation. . The physical properties such as tensile modulus and permanent elongation were also good. Comparative Examples 10 to 12 do not include a trifunctional polyol in the prepolymer, and have compositions (type of bifunctional polyol) other than using only an imidazole derivative as a reaction accelerator, and casting conditions are Examples 6 to 8. Although it is the same as the above, the repetitive mold release property and the mold contamination property are slightly decreased for 1 hour after the start of casting, and the mold release work becomes impossible after 2 hours. In Comparative Example 13, the cross-linking agent was designed so that the equivalent ratio (equivalent ratio (2)) of OH groups / NCO groups of the polyurethane after curing was 0.85, and casting work was impossible in 2 hours. became.

[0041]

As described above, the blade for an electrophotographic apparatus of the present invention is a continuous strip of thermosetting polyurethane, which is coated with a release agent once before the start of molding and wiped for a long time. It can be continuously manufactured, the adhesive force with the holder does not fluctuate, and it is a high quality product that does not contaminate the photoconductor even when it is used as a cleaning blade.

By adopting the reaction accelerator according to the second aspect, it is possible to more reliably improve the releasability of the mold during the casting operation and the contamination of the mold.

In the method of manufacturing the blade for electrophotographic apparatus according to the third aspect, in manufacturing the blade for electrophotographic apparatus according to the first or second aspect, the prepolymer, the crosslinking agent and the like are sufficiently added at a relatively low temperature. While stirring and mixing, casting into a high temperature mold facilitates formation of a film on the contact surface, further improves the polishing accuracy of the mold surface, and repeats releasability.
The mold contamination is improved. It is cheap and has a short delivery time due to continuous production, and it is also effective in improving the working environment.

[Brief description of drawings]

FIG. 1 is a side view illustrating an outline of a manufacturing apparatus 10 used in a manufacturing method of the present invention.

2A is a perspective view of the electrophotographic apparatus blade 1, and FIG. 2B is a side view illustrating a state in which the electrophotographic apparatus blade 1 is in contact with a photosensitive drum 20. FIG. .

FIG. 3A is a partial cross-sectional view illustrating a conventional centrifugal molding method. FIG. 3B shows a polyurethane sheet B molded by the centrifugal molding method, and FIG. 3C is a sectional view for explaining the molding method.

[Explanation of symbols]

 1: Blade for electrophotographic device 2: Blade 3: Holder 10: Manufacturing device 11, 12: Reaction container 20: Molding drum 24: Endless belt

Claims (4)

[Claims] 1. A bifunctional polyol having a number average molecular weight of 1,000 to 3,000, and a trifunctional polyol having a number average molecular weight of 92 to 980, having an average number of functional groups of 2.02 to 2.2.
A prepolymer prepared by mixing a mixed polyol mixed at a ratio of 0 with a diisocyanate compound having an isocyanate group content of 5 to 20% has an OH group / NCO group equivalent ratio of 0.90 to 1.05. An electrophotography comprising a polyurethane sheet obtained by mixing and reacting a certain amount of a cross-linking agent with 0.01 to 1.0 parts by weight of a reaction accelerator with respect to 100 parts by weight of the prepolymer. Equipment blade. 2. The reaction accelerator is 1,8-diazabicyclo (5,4,0) undecene-7-organic acid salt, 1,5-diazabicyclo (4,3,0) nonene-5-organic acid salt. The blade for an electrophotographic apparatus according to claim 1, which comprises any one of the following: 3. A bifunctional polyol having a number average molecular weight of 1,000 to 3,000 and a trifunctional polyol having a number average molecular weight of 92 to 980, having an average number of functional groups of 2.02 to 2.
A diisocyanate compound having an isocyanate group content of 5 to 20% is mixed with a mixed polyol mixed in a ratio of 20 to prepare a prepolymer, and the prepolymer has an equivalent ratio of OH groups / NCO groups. 0.
The uncured polyurethane composition is prepared by mixing 90 to 1.05 of the crosslinking agent and 0.01 to 1.0 parts by weight of the reaction accelerator with respect to 100 parts by weight of the prepolymer at 40 to 70 ° C. The uncured polyurethane composition was prepared at a surface temperature of 130-
A method for manufacturing a blade for an electrophotographic apparatus, comprising pouring into a mold having a surface finish roughness of 0.1 μm or less at 160 ° C. 4. The reaction accelerator is 1,8-diazabicyclo (5,4,0) undecene-7-organic acid salt, 1,5-diazabicyclo (4,3,0) nonene-5-organic acid salt. 4. The method for manufacturing a blade for an electrophotographic apparatus according to claim 3, including any of the above.