JP2009244761A - Blade for electrophotographic device, and method of manufacturing blade for electrophotographic device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a blade for an electrophotographic device having a uniform characteristic by suppressing generation of dispersion in a characteristic such as hardness caused by a difference of progression of polymerization or hardening, and to provide a blade for the electrophotographic device suitable for a cleaning blade capable of performing excellent cleaning by suppressing slip of a toner or the like, especially even when being applied to a cleaning blade for the electrophotographic device using the small-sized toner. <P>SOLUTION: In the blade for the electrophotographic device including a polyurethane elastomer, the international rubber hardness (IRHD) is 65°-80°, and a dispersion of the international rubber hardness in the longitudinal direction is 4% or less. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a blade for an electrophotographic apparatus used in an electrophotographic apparatus and a method for manufacturing the same.

  In electrophotographic apparatuses represented by copying machines, printers, facsimiles, etc., the outer peripheral surface of a photoconductor is uniformly charged, and toner is attached to an electrostatic latent image formed by exposure through a copy image. A toner image is formed and transferred to a transfer material such as paper to form an image. Since toner remains on the outer peripheral surface of the photoconductor after the toner image is transferred, the residual toner is removed by contacting the outer peripheral surface of the photoconductor to prepare for the next image formation.

  The cleaning blade is provided by integrating a rubber blade at one end of a plate-like holder made of metal or the like, and fixing the holder to the apparatus. Since the blade is excellent in wear resistance, permanent strain resistance, etc., polyurethane elastomer is used. However, if the hardness of the polyurethane elastomer blade is too high, the abutting photoreceptor may be damaged.If it is too low, the abrasion resistance will be insufficient and the edge portion will be chipped, and the toner will slip through the defective portion. Cleaning failure may occur. Therefore, a cleaning blade in which the hardness of urethane rubber is set in a range of 60 to 75 (JIS A) has been reported (see Patent Document 1).

  However, in recent years, the electrophotographic apparatus has a spherical toner shape and a small diameter for high resolution, and if the cleaning blade has a slight variation in characteristics such as hardness, the toner may pass through. There is a problem that the cleaning is likely to occur and defective cleaning occurs.

  This type of polyurethane elastomer blade is produced by casting a polyurethane-forming material. For example, a mixture obtained by mixing a prepolymer obtained by partially polymerizing isocyanate, a urethane material such as polyol, and a curing agent containing a chain extender, a catalyst, and the like with a casting machine is used as a gold in which a holder is disposed. It is injected into a mold, heated and cured, and the cured product is removed from the mold.

Such a casting machine continuously feeds a certain amount of raw material for forming a blade into a mixing chamber equipped with a stirrer, mixes and discharges the mixture, and mixes and discharges the raw material. And the mixture is discharged even when the mold is not being poured into the mold. For this reason, the mixture which is not poured into the mold is a material loss. Therefore, for the purpose of reducing material loss, a method of discharging a mixture only when injecting into a mold is used (Patent Document 2). However, even when the mixture is discharged intermittently, the mixing chamber is continuously filled with the blade material, so that the polymerization reaction proceeds in the mixing chamber, and finally the mixture discharged from the mixing chamber and finally Characteristics such as hardness are different between the discharged mixtures. Furthermore, when the mixture is injected into the mold, the heating time is different between the mixture initially injected into the heated mold and the mixture injected last, so that the degree of polymerization and the degree of cure are also within one blade. However, there is a problem that non-uniformity in characteristics such as hardness occurs in the molded blade.
JP-A-7-98558 JP-A-6-210150

  An object of the present invention is to provide a blade for an electrophotographic apparatus that suppresses variations in characteristics such as hardness due to differences in progress of polymerization and curing and has uniform characteristics. In particular, even when applied to a cleaning blade of an electrophotographic apparatus using a small-diameter toner, a blade for an electrophotographic apparatus suitable for a cleaning blade capable of suppressing toner slipping and performing good cleaning can be provided. It is to provide. It is another object of the present invention to provide a method for manufacturing a blade for an electrophotographic apparatus, which can reduce the material loss of the blade for an electrophotographic apparatus and can be manufactured efficiently and easily.

  The present invention is characterized in that, in a blade for an electrophotographic apparatus containing a polyurethane elastomer, the international rubber hardness (IRHD) is 65 ° to 80 °, and the variation in the international rubber hardness in the longitudinal direction is 4% or less. The present invention relates to a blade for an electrophotographic apparatus.

Further, the present invention introduces a predetermined amount of a raw material containing a monomer or prepolymer and a curing agent into a mixing chamber,
A method of manufacturing a blade for an electrophotographic apparatus, wherein a mixture mixed in a mixing chamber is discharged from a mixing chamber and injected into a mold, and the mixture is cured to form a blade containing a polyurethane elastomer,
The injection of the mixture into the mold is performed by discharging a predetermined amount of the mixture from the mixing chamber and then stopping discharging the mixture from the mixing chamber.
The time t2 required to inject a predetermined amount of the mixture into the mold is set to 40 seconds or less, the time to stop discharging the mixture from the mixing chamber is set to t3 (seconds), the initial amount of the mixture in the mixing chamber is A, the mixture When the predetermined amount of B is B
t4 = t3 × [(A / B) −1] (1)
The present invention relates to a method of manufacturing a blade for an electrophotographic apparatus, wherein t4 represented by the formula is 0.1 seconds or more and 500 seconds or less.

  The blade for an electrophotographic apparatus of the present invention has uniform characteristics by suppressing variations in characteristics such as hardness due to differences in the progress of polymerization and curing reactions. In particular, even when it is applied to a cleaning blade of an electrophotographic apparatus using a small-diameter toner, it is possible to suppress toner slipping and the like and perform a good cleaning, which is suitable for a cooling blade.

  According to the method for manufacturing a blade for an electrophotographic apparatus of the present invention, the above-mentioned blade for an electrophotographic apparatus can be manufactured efficiently and easily with reduced material loss.

  The electrophotographic apparatus blade of the present invention is an electrophotographic apparatus blade containing a polyurethane elastomer, wherein the international rubber hardness (IRHD) is 65 ° to 80 °, and the variation of the international rubber hardness in the longitudinal direction is 4% or less. It is characterized by being.

  If the hardness of the electrophotographic apparatus blade of the present invention is 80 ° (IRHD) or less, damage to the abutting member can be suppressed, and if it is 65 ° (IRHD) or more, the blade is appropriately applied to the abutting member. It is possible to suppress damage caused by the abutting member and the abutting member.

  The electrophotographic blade of the present invention is suitable as a cleaning blade, can suppress damage to the abutting photoconductor, can suppress its own damage, and can suppress toner slippage due to damage to the tip. .

  The variation in the longitudinal direction of the international rubber hardness (IRHD) of the electrophotographic blade of the present invention is 4% or less. If the variation in the longitudinal direction of the blade is 4% or less, even in a recent electrophotographic apparatus to which a small particle size toner is applied, it is possible to suppress slip-through and to have a uniform hardness that enables good cleaning. If the hardness becomes non-uniform, even if the edge portion of the blade is not chipped, the contact pressure of the blade with respect to the photosensitive member or the like varies, and cleaning failure due to slipping of small diameter toner tends to occur. When the variation in the longitudinal direction of the international rubber hardness (IRHD) of the blade is within 4%, the cleaning failure due to the variation in the contact pressure can be suppressed and stable cleaning properties can be obtained.

  The international rubber hardness (IRHD) is measured at 10 points at equal intervals in the longitudinal direction by a measuring method according to JIS K 6253 using a Wallace microhardness meter (manufactured by HW WALLACE). The value obtained as the average value can be adopted. Further, the variation in international rubber hardness refers to a difference with respect to an average value of measured values measured by the above method.

  The shape of the blade for an electrophotographic apparatus of the present invention is not particularly limited, and may be a shape suitable for the purpose of use. For example, the thickness may be 0.5 mm to 5 mm, the length in the longitudinal direction is 200 mm to 400 mm, the length in the width direction is 2 mm to 20 mm, and the like.

  The electrophotographic blade can be produced by the following method for producing an electrophotographic apparatus blade of the present invention.

In the method for manufacturing a blade for an electrophotographic apparatus according to the present invention, a mixture in which a raw material containing a monomer or a prepolymer and a curing agent is mixed in a mixing chamber is discharged from the mixing chamber and injected into a mold, and the mixture is cured to form polyurethane. A method of forming a plurality of blades comprising an elastomer,
The injection of the mixture into the mold is performed by discharging a predetermined amount of the mixture from the mixing chamber and then stopping discharging the mixture from the mixing chamber.
The time t2 required to inject a predetermined amount of the mixture into the mold is set to 40 seconds or less, the time to stop discharging the mixture from the mixing chamber is set to t3 (seconds), the initial amount of the mixture in the mixing chamber is A, the mixture When the predetermined amount of B is B
t4 = t3 × [(A / B) −1] (1)
T4 represented by the formula is characterized in that it is 0.1 seconds or more and 500 seconds or less.

  The electrophotographic blade manufacturing method of the present invention is a polyurethane elastomer in which a mixture of raw materials containing a monomer or a prepolymer and a curing agent is mixed in a mixing chamber, discharged from the mixing chamber and injected into a mold, and the mixture is cured. Is a method of forming a plurality of blades.

  Examples of the raw material containing the monomer or prepolymer and the curing agent include polyisocyanate and polyol as monomers, and examples of the prepolymer include these prepolymers.

  Any polyisocyanate may be used as long as it has two or more isocyanate groups, and examples thereof include the following. 4,4'-diphenylmethane diisocyanate (MDI), 2,4-tolylene diisocyanate (2,4-TDI), 2,6-tolylene diisocyanate (2,6-TDI), xylene diisocyanate (XDI). 1,5-naphthylene diisocyanate (1,5-NDI), p-phenylene diisocyanate (PPDI), hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI). 4,4'-dicyclohexylmethane diisocyanate (hydrogenated MDI), tetramethylxylene diisocyanate (TMXDI), carbodiimide-modified MDI, polymethylenephenyl polyisocyanate (PAPI), and the like. Among these, MDI can be mentioned as a preferable thing. These compounds can be used alone or in combination of two or more.

  The polyol may be any polyol having two or more OH groups, but is preferably used as a prepolymer. Examples of the prepolymer include polyester polyol, polyether polyol, caprolactone ester polyol, polycarbonate ester polyol, and silicone polyol. These may be used alone or in combination of two or more. The polyol prepolymer preferably has a number average molecular weight of 1500 to 3000. If the number average molecular weight of the polyol prepolymer is 1500 or more, the physical properties of the polyurethane elastomer obtained are good, and if it is 3000 or less, the viscosity of the prepolymer is appropriate and easy to handle, which is preferable.

  Examples of the monomer or prepolymer curing agent contained in the raw material include a chain extender and a catalyst. Examples of chain extenders include the following glycols. Ethylene glycol (EG), diethylene glycol (DEG), propylene glycol (PG), dipropylene glycol (DPG), 1,4-butanediol (1,4-BD), 1,6-hexanediol (1,6-HD) ), 1,4-cyclohexanediol. 1,4-cyclohexanedimethanol, xylylene glycol (terephthalyl alcohol), triethylene glycol and the like. In addition, trivalent alcohols such as trimethylolpropane, glycerin, pentaerythritol and sorbitol can be exemplified. These can be used alone or in combination of two or more.

  As the catalyst, a tertiary amine catalyst or the like can be used. Specifically, the following can be mentioned. Amino alcohols such as dimethylethanolamine, trialkylamines such as triethylamine, tetraalkyldiamines such as N, N, N ′, N′-tetramethyl-1,3-butanediamine, triethylenediamine, piperazine, and triazine. A metal catalyst such as dibutyltin dilaurate can also be used.

  Moreover, the said catalyst may contain the isocyanurate formation catalyst which accelerates | stimulates isocyanurate formation. The isocyanurate-forming catalyst suppresses the curing reaction in the mixing chamber below the curing temperature due to its temperature sensitivity, and allows the curing reaction to proceed at a stroke after reaching the curing temperature after being injected into the mold. For this reason, variation in the progress of the curing reaction in the mixing chamber can be suppressed, and as a result, variation in the hardness of the blade after molding can be suppressed.

  Examples of the isocyanurate-forming catalyst include the following. Tertiary amines such as N-ethylpiperidine, N, N′-dimethylpiperazine, and N-ethylmorpholine, and tetraalkylammonium hydroxides and organic weak acid salts such as tetramethylammonium, tetraethylammonium, and tetrabutylammonium. Hydroxyalkylammonium hydroxides and organic weak acid salts such as trimethylhydroxypropylammonium and triethylhydroxypropylammonium. Alkali metal salts of carboxylic acids such as acetic acid, propionic acid, butyric acid, caproic acid, capric acid, valeric acid, octylic acid, myristic acid, naphthenic acid. These can be used alone or in combination of two or more. Among these, metal salts of carboxylic acids that bloom after molding of the blade and cause little contamination of other members are preferred.

  Additives such as catalysts, pigments, plasticizers, waterproofing agents, antioxidants, ultraviolet absorbers, light stabilizers and the like can be blended with the raw materials as necessary.

  As a method for introducing these raw materials into the mixing chamber, any method such as a complete prepolymer method, a semi one-shot method, a one-shot method, etc. may be used, but the viscosity of the mixture at the time of mold injection becomes high. In order to suppress it, it is preferable to mix and introduce a curing agent and a polyol. A predetermined amount of the raw material may be introduced into the mixing chamber at a time, but it is preferable to continuously introduce the predetermined amount.

  The mixing chamber prepares a mixture by mixing the monomer or prepolymer and a raw material containing a curing agent, and is appropriately equipped with a stirring device for mixing the raw materials, a temperature adjusting mechanism, and the like. As the stirring device, for example, it is preferable to use a rotor or the like by adjusting the number of rotations and the clearance with the mixing chamber so that the curing reaction proceeds uniformly and the excessive curing proceeds. As the temperature adjustment mechanism, a method of circulating the temperature-adjusted circulating water to the jacket around the mixing chamber can be used.

  In the mixing chamber, raw materials for manufacturing a plurality of blades are weighed and charged, and have a volume capable of mixing them. As will be described later, the mixing chamber only needs to have a volume that allows sufficient mixing while the raw material stays in the mixing chamber in relation to the time to stop discharging the mixture.

  In addition, the mixing chamber has a discharge port for discharging a mixture prepared by mixing raw materials, and the discharge port can discharge the mixture at a specific discharge speed, for example, 0.5 to 4.0 ml / sec. It is preferable to have the following diameter. When the discharge speed is in the above range, a blade having a uniform hardness can be obtained with a hardness suitable for toner removal when used in a cleaning blade. Discharge of the mixture from the mixing chamber is performed by discharging a predetermined amount of the mixture corresponding to the amount injected into the mold cavity and then stopping the discharge. The discharge corresponds to the injection of the mixture into the mold. And do it intermittently. By discharging after a predetermined amount of the mixture is discharged, waste of the mixture due to discharge can be suppressed while setting a mold for injecting the mixture, and material loss can be reduced.

  A time t2 required for injecting a predetermined amount of the mixture into the mold is set to 40 seconds or less. If t2 is 40 seconds or less, it can suppress that the hardness difference resulting from the difference in the curing time between the mixture initially injected into the heated metal mold and the mixture injected last is suppressed.

Also, after discharging a predetermined amount of the mixture from the mixing chamber, when the stop time of the mixture from the mixing chamber is set to t3 (seconds), the discharge of the mixture from the mixing chamber in all the steps of manufacturing a plurality of blades is stopped. The total time t4 to be expressed is expressed by Expression (1).
t4 = t3 × [(A / B) −1] (1)
In the formula (1), A indicates the amount of the mixture in the mixing chamber, B indicates the predetermined amount of the mixture (injection amount into the mold), and A / B indicates the number of blades manufactured in all steps.

Further, the expression (1) is expressed as follows, where C is the discharge speed of the mixture from the mixing chamber and t1 is the time required to discharge all the mixture in the mixing chamber
t1 = A / C,
From t2 = B / C,
t4 = t3 × [(t1 / t2) −1]
It can also be expressed as

  Then, by setting t4 between 0.1 seconds and 500 seconds, the blade has an international rubber hardness (IRHD) of 65 ° to 80 ° and a variation of the international rubber hardness in the longitudinal direction of 4% or less. Can be manufactured.

  From the above, when manufacturing a plurality of blades, the time required until the discharge of all the mixture from the mixing chamber is t2 × (A / B) + t4.

  The mixture can be injected into the mold in the longitudinal direction or in a direction perpendicular to the longitudinal direction, that is, in the width direction. The injected mixture can be cured, for example, at 80 ° C. to 150 ° C. for 0.2 minutes to 60 minutes. The heating method of the mold is not particularly limited, but since the obtained blade has a uniform hardness in the longitudinal direction, a contact-type hot plate can obtain a uniform temperature in the longitudinal direction. The method can be used. A holder that serves as a support member for the blade may be disposed in the mold, and may be integrally molded.

  The holder provided at one end in the longitudinal direction of the blade obtained by the above method and fixing the blade to the electrophotographic apparatus is not particularly limited, and is preferably plate-shaped. As the material, a metal material such as a steel plate, a stainless steel plate, a galvanized chromate coated steel plate, a chromium-free steel plate, or a resin material such as 6-nylon or 6,6-nylon can be used. As described above, the method of joining the blade and the holder can be integrally molded by placing the holder in the mold, but a method of adhering using an adhesive such as a phenol resin can be adopted. .

  The blade for an electrophotographic apparatus according to the present invention is used for an electrophotographic apparatus to which an electrophotographic technique is applied such as a copying machine, a laser beam printer, an LR printer (LED printer), an electrophotographic plate making system, and the like. In particular, it is preferably used as a cleaning blade.

  EXAMPLES Next, although an Example is given and this invention is demonstrated in detail, the technical scope of this invention is not limited to these Examples.

[Example 1]
Molding of cleaning blade A holder in which a phenolic adhesive was applied to one end of one end side in advance was prepared. A mold for forming a cleaning blade was prepared, and arranged in a state where one end of one end of the holder protruded into the cavity of the mold.

  296.6 g of 4,4′-diphenylmethane diisocyanate and 703.4 g of ethylene adipate polyester polyol having a number average molecular weight of 2000 were reacted at 80 ° C. for 3 hours to obtain a prepolymer having an NCO group content of 7.00% by mass. A curing agent prepared by mixing 39.1 g of 1,4-butanediol, 21.0 g of trimethylolpropane, 0.06 g of an ethylene glycol solution of potassium acetate (DABCO P15: manufactured by Air Products Japan), and 0.18 g of triethylenediamine (TEDA). Got. The prepolymer and the curing agent were mixed with a casting machine having a mixing chamber, and the mixture was discharged and poured into a mold. The discharge speed was 1.9 ml / second, the discharge time was 5.2 seconds for the time t2 required to inject the mixture into the mold, and the time t3 for stopping the discharge of the mixture from the mixing chamber was 5.0 seconds. t4 was 5.0 seconds, and the time required until the injection of all the mixtures in the mixing chamber into the mold was 15.4 seconds. A curing reaction was performed at 130 ° C. for 5 minutes in the mold, and the cured product was demolded to obtain a blade of 230 mm × 10 mm × 2 mm.

[hardness]
The obtained blade was measured for hardness at 10 points at regular intervals in the longitudinal direction using a Wallace micro hardness tester (manufactured by HW WALLACE) in accordance with JIS K 6253. The maximum was 70.6 °, the minimum was 69.8 °, and the average was 70.2 °. The variation in hardness was calculated by dividing the difference (maximum-minimum) by the average value. The variation was 1.1%.

[Evaluation of actual machine]
The cleaning blade obtained as described above was incorporated into a laser beam printer (Canon LBP2510), and the cleanability at a low temperature was evaluated under an environment of 15 ° C. A case where 10,000 images were output and no defective image due to poor cleaning was found on the output image obtained for the 10,000th image was marked as ◯, and a case where streaks due to poor cleaning occurred on the image was marked as x. The results are shown in Table 1.

[Example 2]
The same procedure as in Example 1 was performed except that t1 and t2 were set to 1.6 seconds, t3 was set to 1.0 seconds, and t4 was set to 1.0 seconds. The results are shown in Table 1.

[Example 3]
The same procedure as in Example 1 was performed except that t1 was 25.0 seconds, t2 was 1.6 seconds, and t3 was 30.0 seconds. t4 was 438.8 seconds, and the time required for the injection of all the mixtures in the mixing chamber into the mold was 463.8 seconds. The results are shown in Table 1.

[Example 4]
The same operation as in Example 1 was performed except that the discharge speed was 0.5 ml / second, t1 was 97.5 seconds, and t2 was 39.0 seconds. t4 was 7.5 seconds, and the time required for the injection of all the mixture in the mixing chamber into the mold was 105 seconds. The results are shown in Table 1.

[Comparative Example 1]
The same procedure as in Example 1 was performed except that t1 was 31.2 seconds, t2 was 1.6 seconds, and t3 was 30.0 seconds. t4 was 555.0 seconds, and the time required for the injection of all the mixtures in the mixing chamber into the mold was 586.2 seconds. The results are shown in Table 1.

The symbols in the table indicate the following.
4,4'-MDI: 4,4'-diphenylmethane diisocyanate,
PEA: Polyethylene adipate polyester polyol
1,4-BD: 1,4-butanediol, TMP: trimethylolpropane, P15: ethylene glycol solution of potassium acetate (manufactured by Air Products Japan),
TEDA: Triethylenediamine In Example 1-4, the variation in the longitudinal direction of the cleaning blade is 4% or less, and no cleaning failure has occurred even in the actual machine evaluation. On the other hand, in Comparative Example 1, the volume of the mixing chamber is large and the non-ejection time t3 is as long as 30.0 seconds. Therefore, t4 is 555.0 seconds, and there is a variation in reaction in the mixing chamber. large. As a result, the variation in the hardness of the cleaning blade was 6.7%, and cleaning failure due to toner slippage occurred even in the actual machine evaluation.

Claims (3)

  An electrophotographic apparatus blade comprising a polyurethane elastomer, wherein the international rubber hardness (IRHD) is 65 ° to 80 °, and the variation in the international rubber hardness in the longitudinal direction is 4% or less. blade. While introducing a predetermined amount of a raw material containing a monomer or prepolymer and a curing agent into the mixing chamber, the mixture mixed in the mixing chamber is discharged from the mixing chamber and injected into a mold, and the mixture is cured to include a polyurethane elastomer. A method of manufacturing a blade for an electrophotographic apparatus for forming a blade, wherein injection of a mixture into a mold is performed by discharging a predetermined amount of the mixture from the mixing chamber and then stopping discharging the mixture from the mixing chamber. The time t2 required to inject a predetermined amount of the mixture into the mold is set to 40 seconds or less, the time for stopping the discharge of the mixture from the mixing chamber is t3 (seconds), the amount of the mixture in the mixing chamber is A, the place of the mixture When quantification is B,
t4 = t3 × [(A / B) −1] (1)
A method for producing a blade for an electrophotographic apparatus, wherein t4 represented by the formula is 0.1 seconds to 500 seconds.   3. The method of manufacturing a blade for an electrophotographic apparatus according to claim 2, wherein the blade for the electrophotographic apparatus is a cleaning blade.