JP2007033484A - Cleaning blade for electrophotographic device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cleaning blade for an electrophotographic device capable of demonstrating excellent scratch capability even at low temperature. <P>SOLUTION: The cleaning blade for an electrophotographic device has a elastic rubber member made of polyurethane stuck to a support member, wherein the elastic rubber member made of polyurethane has hardness at 23°C of 65-80 IRHD by a micro-test method of the JISK6253 International Rubber Hardness Degrees test, and the polyurethane has such a contact pressure ratio (A/B) between contact pressure (A) measured at the point of further pressing the tip of the elastic rubber member of the cleaning blade by 1.3 mm at a speed of 1 mm per second after preliminarily pressing the tip of the elastic rubber member by 0.1 mm and contact pressure (B) measured one minute later in the state, that is 1.2 or more under the atmosphere at 10°C. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a cleaning blade for an electrophotographic apparatus that can exhibit excellent scraping properties even at low temperatures.

  According to an electrostatic electrophotographic copying machine using plain paper as a recording paper, generally, an electrostatic charge is given to the surface of the image carrier by discharge, and an image is exposed thereon to form an electrostatic latent image. Then, the charged toner is attached to the electrostatic latent image and developed, and the toner image is transferred to the recording paper. Finally, the recording paper on which the toner image is transferred is heated and pressurized to fix the toner on the recording paper. Make a copy.

  Therefore, in order to sequentially copy on a plurality of recording papers, it is necessary to remove the toner remaining on the surface of the image carrier after the toner image is transferred from the image carrier to the recording paper in the above-described process. Such toner removal is usually performed by a cleaning blade for an electrophotographic apparatus. The cleaning blade for an electrophotographic apparatus is usually formed of a support member made of a metal plate, an elastic rubber member, and an adhesive layer for joining the support member and the elastic rubber member.

  As a conventional elastic rubber member, for example, a polyurethane elastic rubber member having a hardness of 65 to 80 IRHD according to the JISK6253 international rubber hardness test micro test method and a rebound resilience of 20 to 60% is used. In use, the edge of the elastic rubber member in contact with the surface of the image carrier vibrates with a small amplitude when it slides on the surface of the rotating image carrier, and the toner remaining on the surface of the image carrier In general, the surface of the image carrier is cleaned by the effect of flipping particles.

  In recent years, in electrophotographic apparatuses, a higher quality printed matter has been demanded, and accordingly, a toner having a small particle size (hereinafter referred to as a small particle size toner) or a toner having a spherical toner particle (hereinafter referred to as a toner particle) , Called spherical toner). When such a toner is used, it is preferable that the force for pressing the cleaning blade for an electrophotographic apparatus is strong in order to scrape the toner remaining on the surface of the image carrier. However, if the force for pressing the cleaning blade for an electrophotographic apparatus is too strong, the rotational torque of the image carrier becomes too high, and the surface of the image carrier is damaged.

  In general, the physical properties of the elastic rubber member change depending on the temperature. When the temperature is lowered, the elastic property of the elastic rubber member is lost and hardened. Therefore, it is difficult to press the cleaning blade for an electrophotographic apparatus sufficiently against the image carrier. There was a tendency to become. Therefore, in a cold region, there is a need for an electrophotographic apparatus cleaning blade that can exhibit excellent scraping performance that is the same as that at room temperature even at low temperatures.

In Patent Document 1 (Japanese Patent Application Laid-Open No. 11-212418), when a urethane cured body is exposed to an environment of a mechanical loss tan δ peak temperature or less, the hardness increases, and sag is likely to occur in a low temperature environment. The cleaning blade has been proposed in which the tan δ peak temperature is lowered to a range of 1.0 to 10 ° C. because the cleaning property is deteriorated, but it is not sufficient.
Patent Document 2 (Japanese Patent Laid-Open No. 2003-58008) proposes a measure for providing a heating device to heat the cleaning blade.
Patent Document 3 (Japanese Patent Laid-Open No. 2002-214989) discloses an elastic rubber member having a two-layer structure including an edge layer that comes into contact with an image carrier and a base layer that is joined to a support member. The base layer is made of a material having a JIS A hardness of 70 to 85 and a rebound resilience of 0 to 20%, the base layer has a JIS A hardness of 65 to 70 and a rebound resilience of 15 to A cleaning blade for an electrophotographic apparatus made of a material that is 40% and has a permanent elongation of 2% or less has been proposed.

Japanese Patent Laid-Open No. 11-212418 JP 2003-58008 A JP 2002-214989 A

  An object of the present invention is to provide a cleaning blade for an electrophotographic apparatus that can exhibit excellent scraping properties even at low temperatures.

The present invention mainly provides the following solutions.
(1) In a cleaning blade for an electrophotographic apparatus in which an elastic rubber member made of polyurethane is bonded to a support member, the elastic rubber member made of polyurethane has a hardness at 23 ° C. according to JIS K6253 international rubber hardness test micro test method. It is 65-80IRHD, and after pressing the tip of the elastic rubber member of the cleaning blade in advance by 0.1 mm, the pressure contact force (A) measured at the time of further pushing 1.3 mm at a speed of 1 mm per second and the measurement after 1 minute in that state A cleaning blade for an electrophotographic apparatus, comprising a polyurethane having a pressure contact ratio (A / B) of 1.2 to 1.7 in a 10 ° C. atmosphere.
(2) The cleaning blade for an electrophotographic apparatus according to (1), wherein the pressure contact force ratio (A / B) is 1.4 to 3.5 in an atmosphere of 0 ° C.
(3) The cleaning blade for an electrophotographic apparatus according to (1), wherein the pressure contact force ratio (A / B) is 1.8 to 3.5 in an atmosphere at 0 ° C.
(4) The cleaning blade for an electrophotographic apparatus according to any one of (1) to (3), wherein a dynamic storage elastic modulus (E ′) in an atmosphere at 0 ° C. is 60 to 150 MPa.

INDUSTRIAL APPLICABILITY The present invention can provide a cleaning blade using polyurethane that exhibits high stress immediately after deformation even at low temperatures, and exhibits normal pressure contact force after the stress is relaxed. It is possible to reduce poor cleaning at low temperatures and suppress wear of the photoreceptor due to long-term use. In a low-temperature atmosphere, the pressure contact force at the start of rotation of the photoconductor is high and the cleaning property is good. In a steady state, the pressure contact force is reduced, so that photoconductor wear can be suppressed.

There is a problem that the electrophotographic apparatus has a cleaning defect in a low temperature atmosphere such as immediately after starting up the electrophotographic apparatus in the cold region, particularly in the morning in the cold region. Although the cause of this phenomenon itself is said to be various, it is unknown. As a result of earnest research, the present invention has acquired the knowledge that the toner should be damped by showing a large pressure contact force at the moment when the photosensitive member starts rotating, and is compatible with a blade capable of obtaining a good image even in a steady state. A cleaning blade that can be put to practical use is completed.
Since it is difficult to measure the stress at the moment when the photosensitive member starts rotating, the pressure contact force A is used as a stable measurement condition in the present invention.
If the stress (pressure contact force A) at the start of rotation is low, the toner enters between the cleaning blade and the photoconductor, and then the toner slips through, or there is a gap between the blade and the photoconductor due to the presence of the toner. It is estimated that the toner will slip through the gap one after another. The temperature and humidity dependence characteristics of toner, photoconductor, charging roller and other electrophotographic parts are also considered to be affected. For example, toner has a large charge amount in a low temperature (≈ low humidity) atmosphere and strongly interacts with the photoconductor. It acts and is difficult to scrape with a blade.
As a result of measuring the pressure contact force of a commercially available cleaning blade based on this unique point of view, the initial pressure contact force A is about 109 g / cm at about 23 ° C., which is usually close to room temperature, and there is a problem. Absent. However, it was found that a slight malfunction occurred at 10 ° C. and a rain-like malfunction occurred on the entire image at 0 ° C., and excess toner was transferred. On the other hand, the pressing force B assuming a steady operation state slightly decreased to about 106 g / cm.
In a commercially available cleaning blade, the toner is dammed even at an initial pressure contact force of 109 g / cm at room temperature, but the action is effective even at a low temperature range, for example, a pressure contact force A at 0 ° C. of 140 g / cm. It is insufficient. The reason is not completely elucidated, but can be considered as follows. Since the blade with a low initial pressure contact force A has low stress against rapid deformation, it is likely to be deformed with respect to fast external force, and the blade edge line is dragged by the photoreceptor at the start of rotation of the photoreceptor. It is assumed that with the blade, the stress is relaxed in this posture and the pressure contact force A is low, the toner is sandwiched between the photosensitive member at the start of rotation of the photosensitive member, and the pressure contact force is further relaxed to cause the toner to slip through. The It is considered that this situation appears remarkably when the connection between the toner and the photoconductor becomes strong at low temperatures.
In order to avoid this cause, if a blade having a high initial pressure contact force A is created, the stress against fast deformation is high, and it becomes difficult to deform against fast external force, and the ridge line of the blade is dragged against the photoconductor at the start of rotation of the photoconductor. It is assumed that no toner slips out even if the pressure contact force is eased because the toner is not sandwiched between the photosensitive member and the photosensitive member at the start of rotation.
However, a blade made of a hard rubber, that is, a rubber having a high pressure contact force A and a high pressure contact force B is preferable. However, if the pressure contact force B is too high, there is a disadvantage that the wear of the photosensitive member is increased. It is symbolized that the upper limit of hardness described in various application specifications is generally about 80. The reason why the lower limit of the hardness is generally set to about 65 degrees is to avoid shortage of the absolute value of the pressure contact force. Also in the present invention, the rubber hardness at room temperature is set to 65-80.
In addition, the toner has a large charge amount in a low-temperature atmosphere and interacts strongly with the photoconductor, making it difficult to scrape off with a cleaning blade. We have developed a cleaning blade that can be used.

In the present invention, the stress immediately after the start of rotation of the rotating body and the pressure contact force in the steady rotation state are measured as the pressure contact force A and the pressure contact force B by the following method, and the ratio is used to specify the material of the cleaning blade. It was.

<Pressure force measurement and pressure force ratio>
A width of 10 mm was cut out from the cleaning blade to be tested and arranged as shown in FIG. After pressing 0.1 mm in the direction of the arrow in advance (FIG. 1 (a)), further pressing 1.3mm at a speed of 1mm per second (FIG. 1 (b)), the pressure contact force at this time (= weight g / The pressure contact force ratio A / B was measured with A as the width cm) and B as the pressure contact force after 1 minute.

  The cleaning blade 6 is brought into contact with the pressure receiving surface 5 connected to the load cell 4 at an angle of 27 degrees, and in this state, a pressing operation is performed so as not to move the contact tip, and the pressure contact force in a predetermined state is obtained. It was measured. That is, after 0.1 mm in advance in the direction of the arrow, it is further pushed in by 1.3 mm at a speed of 1 mm per second, and the pressure contact force (= weight / width) at this time is measured and set as the pressure contact force A. Further, the pressure contact force after 1 minute is measured and set as pressure contact force B. The ratio of the pressure contact force A to the pressure contact force B is calculated as the pressure contact force ratio A / B.

  The pressing force A measured by the pressing force measuring apparatus shown in FIG. 1 relaxes to the pressing force B. However, a cleaning blade having a high pressing force A has a high stress against rapid deformation applied to the blade at the start of rotation of the photosensitive member. The cleaning blade is less likely to be deformed by a fast external force and maintains the posture in which the ridgeline of the cleaning blade is not dragged to the photoconductor at the start of rotation of the photoconductor. Since it is easily deformed by a fast external force, the ridgeline of the cleaning blade is dragged by the photoconductor when the photoconductor starts to rotate. In this cleaning posture, the stress is relaxed and the cleaning blade having a low pressure contact force A sandwiches toner between the photosensitive member at the start of rotation of the photosensitive member, and the pressure contact force is further relaxed to cause toner slipping. With a cleaning blade having a high force A, toner is not sandwiched, and toner does not slip through even if the pressure contact force is reduced.

Thus, a cleaning blade using an elastic rubber having a high pressure contact force A and a high pressure contact force B is preferable. However, if the pressure contact force B is too high, the photoconductor is aggravated. For this reason, in general, an upper limit of hardness of 80 degrees according to the JISK6253 micro test method is required. The lower limit of hardness is due to a lack of the absolute value of the pressure contact force, and is generally 65 degrees according to the micro test method. Therefore, in order to achieve both cleanability in a low-temperature atmosphere and photoconductor wear, it is preferable that the pressure contact force A is high, and then relaxes to show a pressure contact force equivalent to that of a general urethane blade. In the present invention, for this reason, the hardness of the cleaning blade is set to 80 to 65, and the pressure contact force ratio independent of the shape is limited as a characteristic.
In the present invention, the pressure contact ratio (A / B) is suitably 1.2 to 1.7 at 10 ° C., 1.4 to 3.5 at 0 ° C., and preferably 1.8 to 3.5 at 0 ° C. . The upper limit values 1.7 and 3.5 are limited by ranges that do not lose rubber elasticity. That is, as will be described later, according to experimental data, there is a tendency that a higher pressing force is better, but if it is too high, rubber elasticity is lost, and generally such a thing is good in a low temperature region of 10 ° C. or lower. Since the cleaning function cannot be performed, the upper limit value is limited by this.

  The above-mentioned pressure contact force ratio indicates stress relaxation with respect to time of the elastic rubber member, and the temperature dependency of stress relaxation is clarified by comparing the pressure contact force ratio of the elastic rubber member at temperatures of 0 ° C. and 10 ° C. can do. At room temperature higher than 10 ° C., Reference 1 (Masao Doyama, Ryoichi Yamamoto “Polymer Material”, page 54 (University of Tokyo Press) 1996), Reference 2 (Kozo Sato, “Polymer Processing”, Volume 47, No. 7, page 324 ( As shown in the figures of Polymer publications (1998) and Reference 3 (Yuji Harasaki, “Basic Science of Coatings”, p. 110 (Tsubaki Shoten), 1988), amorphous polymers such as elastic rubber members have a secondary transition point. In the high temperature range, the storage elastic modulus shows a substantially constant value with respect to the temperature, and the stress relaxation can be regarded as constant, so that there is no significant variation in the pressure contact force ratio in the operating temperature state of a normal electrophotographic apparatus. Can be considered. Therefore, the cleaning blade which does not cause a problem at 23 ° C. can sufficiently function in a temperature range higher than that.

In the present invention, characteristics such as dynamic viscoelasticity are also shown for reference. When a sinusoidal distortion τ expressed by τ = τoeiωt is given to the viscoelastic body in a steady vibration manner, the stress σ is expressed by σ = σoei (ωt + δ). When the dynamic elastic modulus at this time, that is, the complex elastic modulus is E *, it is expressed as E * = σ / τ = σ ₀ / τ ₀ · cos δ + i · σ ₀ / τ ₀ · sin δ = E ′ + iE ” E ′ is the storage modulus and E ″ is the loss modulus. Further, the loss tangent is represented by tan δ = E ″ / E ′. The peak temperature of tan δ is one of dynamic viscoelastic characteristics, and is a tan δ measured by a dynamic viscoelasticity measuring device. A temperature indicating a maximum value (peak value).

  The cleaning blade for an electrophotographic apparatus of the present invention has a structure in which polyurethane elastic rubber is bonded to a support member schematically shown in FIG. The elastic rubber member 1 made of polyurethane is joined to the bent support member 3 via the adhesive layer 2 on the front end side.

The elastic rubber used for the cleaning blade of the present invention is made of polyurethane.
The polyurethane elastomer is obtained by polymerizing a polyol component (A1) and an organic polyisocyanate (A2) as essential components, and using a chain extender (A3), a crosslinking agent (A4), and a terminator (A5) as optional components. And polyurethane elastomers.
As the polyurethane elastomer, any one of thermoplastic and thermosetting resins can be obtained depending on (A1) to (A5), and any of them can be selected according to the intended use.

As the polyol component (A1), a high molecular polyol (a1) and, if necessary, a low molecular polyol (a2) are used.
Examples of the polymer polyol (a1) include polyester polyol (a11), polyether polyol (a12), and a mixture of two or more thereof.
The hydroxyl equivalent of the polymer polyol (a1) (number average molecular weight per hydroxyl group based on hydroxyl value measurement; the same applies hereinafter) is preferably 250 to 5,000 from the viewpoint of obtaining a soft feeling and desired strength of the molded product. More preferably, it is 350-2,500, Most preferably, it is 400-2,000. The number of hydroxyl groups per molecule of the polymer polyol (a1) is preferably 2 to 4, more preferably 2 to 3, particularly preferably 2.

  Examples of the low-molecular polyol (a2) include 2 to 3 or more polyols having a hydroxyl group equivalent of less than 250. Specific examples thereof include dihydric alcohols such as aliphatic diols having 2 to 12 carbon atoms [linear diols (ethylene glycol, diethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol. 1,6-hexanediol, and the like, and branched diols (1,2-propylene glycol, neopentyl glycol, 3-methyl-1,5-pentanediol, 2,2-diethyl-1,3-propane Diol, 1,2-, 1,3- and 2,3-butanediol, etc.]]; diols having a cyclic group having 6 to 25 carbon atoms, for example, those described in JP-B No. 45-1474; Group-containing diol [1,4-bis (hydroxymethyl) cyclohexane, hydrogenated bisphenol A, etc.]; aromatic ring-containing diol [ -And p-xylylene glycol, dihydric phenols [monocyclic dihydric phenols (hydroquinone, etc.), bisphenols (bisphenol A, bisphenol S, bisphenol F, etc.), dihydroxynaphthalene, etc.] ), Bishydroxyalkyl (2 to 4 carbon atoms) esters of aromatic dicarboxylic acids [such as bis (2-hydroxyethyl) terephthalate]]; trihydric alcohols such as glycerin, trimethylolpropane, and alkylene oxide adducts thereof (hydroxyl groups) Equivalents of less than 250); and mixtures of two or more thereof. Of these, aliphatic diols and aromatic ring-containing diols are particularly preferred.

  The polyester polyol (a11) includes (1) condensation polymerization of low molecular polyol and / or polyether polyol and dicarboxylic acid; (2) ring-opening addition of a lactone monomer to the low molecular polyol and / or polyether polyol. And a dicarboxylic acid-modified product thereof; (3) those obtained by condensation polymerization of low-molecular polyols and / or polyether polyols and carbonic acid diesters (dimethyl carbonate, ethylene carbonate, etc.); and mixtures of two or more of these. .

  Specific examples of the dicarboxylic acid used in the above (1) include aliphatic dicarboxylic acids having 4 to 15 carbon atoms [succinic acid, adipic acid, sebacic acid, glutaric acid, azelaic acid, maleic acid, fumaric acid, etc.], carbon Aromatic dicarboxylic acids having a number of 8 to 15 [terephthalic acid, isophthalic acid, etc.], ester forming derivatives thereof [acid anhydrides, lower alkyl (carbon number 1 to 4) esters, acid halides (acid chlorides, etc.), etc.], And a mixture of two or more of these.

  Specific examples of the low molecular polyol and / or polyether polyol used in the above (1) to (3) include those exemplified above as (a2) and (a12), respectively.

  Examples of the lactone monomer used in the above (2) include lactones having 4 to 18 carbon atoms such as α-caprolactone, β-caprolactone, γ-caprolactone, δ-caprolactone, ε-caprolactone, α-methyl-ε-caprolactone, β -Methyl-ε-caprolactone, heptalactone, octalactone, undecalactone, pentadecalactone, γ-butyrolactone, γ-valerolactone, and mixtures of two or more thereof.

  Specific examples of the polyester polyol (a11) include (1) polyethylene adipate diol, polybutylene adipate diol, polyhexamethylene adipate diol, polybutylene isophthalate diol, polyhexamethylene isophthalate diol, polyneopentyl adipate diol, polyethylene Propylene adipate diol, polyethylene butylene adipate diol, polybutylene hexamethylene adipate diol, poly (polytetramethylene ether) adipate diol, poly (diethylene glycol) isophthalate diol; (2) polycaprolactone diol, adipic acid-modified polycaprolactone diol, terephthalic acid Modified polycaprolactone diol, isophthalic acid modified polycaprolactone geo Le; (3) polyhexamethylene carbonate diol; and combinations of two or more of these.

  Examples of the polyether polyol (a12) include compounds having a structure in which an alkylene oxide is added to the low molecular polyol (a2).

  In the above and the following, the alkylene oxide includes alkylene oxides having 2 to 10 or more carbon atoms, and phenyl or halo substitution products thereof, ethylene oxide (hereinafter abbreviated as EO), propylene oxide (hereinafter abbreviated as PO), 1,2-, 1,3-, 1,4- and 2,3-butylene oxide, styrene oxide, α-olefin oxide having 5 to 10 or more carbon atoms, epihalohydrin (such as epichlorohydrin), and the like Or a combination of two or more (block and / or random addition). Of these, EO, PO and combinations thereof (block and / or random addition) are particularly preferred.

  Specific examples of the polyether polyol (a12) include polyethylene glycol, polypropylene glycol, polyoxyethylene-polyoxypropylene (block and / or random) glycol, polytetramethylene ether glycol, polyoxybutylene-polyoxyethylene (block). And / or random) glycols, polyoxybutylene-polyoxypropylene (block and / or random) glycols, EO and / or PO adducts of bisphenol A, and combinations of two or more thereof.

  Among the polymer polyols (a1), preferred are polyester polyols (a11), more preferred are the polyester polyols of (1) above, and particularly preferred are aliphatic diols and dicarboxylic acids, especially aromatic dicarboxylic acids. Polyester diol by condensation of

Examples of the organic polyisocyanate (A2) include the following (a21) to (a25) and a mixture of two or more thereof.
(A21) 6 to 16 aromatic diisocyanate {1,3- and / or 1,4-phenylene diisocyanate, 2,4- and / or 2 excluding carbon in NCO group; , 6-tolylene diisocyanate (TDI), crude TDI, 2,4'- and / or 4,4'-diphenylmethane diisocyanate (MDI), 4,4'-diisocyanatobiphenyl, 3,3'-dimethyl-4 , 4′-Diisocyanatobiphenyl, 3,3′-dimethyl-4,4′-diisocyanatodiphenylmethane, crude MDI [crude diaminophenylmethane [condensation product of formaldehyde and aromatic amine (aniline) or a mixture thereof] A mixture of diaminodiphenylmethane and a small amount (for example, 5 to 20% by weight) of a trifunctional or higher polyamine] Polyallyl polyisocyanate (PAPI)], 1,5-naphthalene diisocyanate, 4,4 ′, 4 ″ -triphenylmethane triisocyanate, m- and p-isocyanatophenylsulfonyl isocyanate, etc.};
(A22) C6-C10 aliphatic diisocyanate [ethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate (HDI), dodecamethylene diisocyanate, 1,6,11-undecane triisocyanate, 2,2,4-trimethylhexamethylene Diisocyanate, lysine diisocyanate, 2,6-diisocyanatomethylcaproate, bis (2-isocyanatoethyl) fumarate, bis (2-isocyanatoethyl) carbonate, 2-isocyanatoethyl-2,6-diisocyanatohexa Noate etc.];
(A23) C6-C16 alicyclic diisocyanate [isophorone diisocyanate (IPDI), dicyclohexylmethane-4,4′-diisocyanate (hydrogenated MDI), cyclohexylene diisocyanate, methylcyclohexylene diisocyanate (hydrogenated TDI), bis (2-isocyanatoethyl) -4-cyclohexene-1,2-dicarboxylate, 2,5- and / or 2,6-norbornane diisocyanate, etc.];
(A24) an araliphatic diisocyanate having 8 to 12 carbon atoms [m- and / or p-xylylene diisocyanate (XDI), α, α, α ′, α ′,-tetramethylxylylene diisocyanate (TMXDI), etc.];
(A25) Modified products of these organic diisocyanates [(a21) to (a24)], such as modified MDI (urethane modified MDI, carbodiimide modified MDI, trihydrocarbyl phosphate modified MDI), urethane modified TDI, biuret modified HDI, isocyanurate modified Modifications of polyisocyanates such as HDI and isocyanurate-modified IPDI and mixtures of two or more of these [for example, combined use of modified MDI and urethane-modified TDI (isocyanate-containing prepolymer)] are included. The polyol used in the production of the urethane-modified polyisocyanate [free isocyanate-containing prepolymer obtained by reacting excess polyisocyanate (TDI, MDI, etc.) and polyol] is a polyol having a hydroxyl equivalent of 30 to 200, such as ethylene. Glycols such as glycol, propylene glycol, diethylene glycol and dipropylene glycol; triols such as trimethylolpropane and glycerine; highly functional polyols such as pentaerythritol and sorbitol; and adducts thereof with these alkylene oxides (ethylene oxide and / or propylene oxide) Can be mentioned. Of these, particularly preferred are those having 2 to 3 functional groups.
The concentration (% by weight) of the free isocyanate in the modified polyisocyanate and the prepolymer is usually 8 to 33%, preferably 10 to 30%, particularly preferably 12 to 29%.
Among these, particularly preferred are (a21) and (a23), particularly MDI, TDI, IPDI and hydrogenated MDI, from the viewpoints of resin strength and durability of the molded article.

Examples of the chain extender (A3) used as necessary include the following (a31) to (a33) and combinations of two or more thereof.
(A31) Low molecular diol having an average molecular weight of less than 500: aliphatic dihydric alcohols (ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, 1,4-butanediol, neopentyl glycol, 1,6-hexanediol, 1 , 8-octanediol), low molecular diols having a cyclic group [1,4-bis (hydroxymethyl) cyclohexane, m- and p-xylylene glycol, 1,4-bis- (2-hydroxyethoxy) benzene 1,4-bis (α-hydroxyisopropyl) benzene, 2,2-bis (4-hydroxyethoxyphenyl) propane and the like];
(A32) Diamine compound: aliphatic diamine (ethylenediamine, hexamethylenediamine, etc.), alicyclic diamine (isophorone diamine, 4,4′-dicyclohexylmethanediamine, norbornane diamine, etc.), aromatic diamine (4,4′-diamino) Diphenylmethane, etc.), araliphatic diamines (diphenylmethanediamine, toluenediamine, 3,3′-dichloro-4,4′-diaminodiphenylmethane, xylylenediamine, etc.), hydrazine or derivatives thereof, polyoxyalkylenediamine, diethylene glycol bis (4 -Aminobenzoate), 3,5-diamino-4-chlorobenzoic acid 2-methylpropyl ester, etc.]; and mixtures of two or more of the above;
(A33) Alkanoldiamine: hydroxylethylethylenediamine, N, N′-dihydroxyethylethylenediamine and the like.

As a crosslinking agent (A4) used as needed, the following (a41) is mentioned, for example.
(A41) Polyhydric (trivalent or higher) alcohols having an average molecular weight of less than 500: Trihydric alcohols (glycerin, trimethylolpropane, hexanetriol, etc.), tetrahydric or higher polyhydric alcohols (sorbitol, sucrose, etc.), etc. .

  Moreover, when manufacturing this polyurethane elastomer, a stopper (A5) can also be used if necessary. Examples of (A5) include monoalcohol (such as methanol and butanol), monoamine (such as butylamine and dibutylamine), and alkanolamine (such as monoethanolamine and diethanolamine).

  In the production of the polyurethane elastomer, the total number of moles of active hydrogen groups (A1), (A3), (A4) and (A5), which are components having active hydrogen groups, and the number of moles of isocyanate groups (A2) (H / NCO ratio) is usually 0.75 to 1.2, preferably 0.85 to 1.05.

  In the production of the polyurethane elastomer, if necessary, organic solvents {ketones [acetone, methyl ethyl ketone (hereinafter referred to as MEK), methyl isobutyl ketone, etc.], esters (ethyl acetate, butyl acetate, ethyl cellosolve acetate, etc.), ethers ( Dioxane, tetrahydrofuran, etc.), hydrocarbons (n-hexane, n-heptane, cyclohexane, tetralin, toluene, xylene, etc.), alcohols (methanol, ethanol, isopropyl alcohol (hereinafter referred to as IPA), n-propyl) Alcohol, butanol, etc.), chlorinated hydrocarbons (dichloroethane, trichloroethane, trichloroethylene, perchloroethylene, etc.), amides (dimethylformamide, dimethylacetamide, etc.), N-methylpi May be carried out in pyrrolidone etc.}, an organic solvent may be added after the reaction during or reaction.

The method for producing the polyurethane elastomer is not particularly limited. For example,
(1) One-shot method in which each component is reacted at once [for example, a method of reacting (A1), (A2) and (A3) in a molten state in a biaxial extrusion kneader],
(2) A multi-stage method in which each component is reacted stepwise [for example, after reacting (A2) with a part of the active hydrogen compound to form an isocyanate group-terminated prepolymer, the remainder of the active hydrogen compound is added to further react Prepolymer method, semi-one-shot method, etc.]
You may manufacture by any method of these. Further, as described above, the obtained elastomer may be either thermoplastic or thermosetting.

  In the production of polyurethane elastomer, the reaction is usually performed at a temperature of 30 to 200 ° C, preferably 60 to 160 ° C. (However, when the amine compound is reacted, it is usually carried out at a temperature of 150 ° C. or lower, preferably 30 to 100 ° C.)

  If necessary, in order to accelerate the reaction, a catalyst used in a normal urethane reaction [amine catalyst (triethylamine, N-ethylmorpholine, triethylenediamine, etc.), tin-based catalyst (dibutyltin dilaurate, dioctyltin dilaurate, tin octylate) Etc.), titanium-based catalysts (tetrabutyl titanate, etc.)] and the like may be used.

  In the case of a thermoplastic urethane elastomer, the number average molecular weight of the polyurethane elastomer in the present invention is preferably 5,000 or more, more preferably 8,000 or more, preferably from the viewpoint of molding workability, from the viewpoint of the resin strength of the elastomer. Is 200,000 or less, more preferably 100,000 or less.

  The support member used for the cleaning blade for an electrophotographic apparatus used in the present invention is not particularly limited with respect to the material, and examples thereof include a rigid metal, a metal having elasticity, a plastic, a ceramic manufactured, and the like. In general, it is possible to use an untreated steel plate or a steel plate that has been subjected to a surface treatment such as zinc phosphate treatment or chromate treatment. In the production of the cleaning blade for an electrophotographic apparatus of the present invention, the support member is preferably used after being degreased with a solvent or the like.

  The cleaning blade for an electrophotographic apparatus of the present invention may be manufactured by a method according to a method usually used for polyurethane elastomers. For example, a sheet of the elastic material of the present invention obtained by centrifugal molding or the like is cut into a predetermined size. After the blade member is obtained, a method is used in which a commonly used adhesive is applied to the support member, and the blade member is bonded to the support member by heating and pressing; the support member coated with the adhesive is used for forming the blade member. For example, the elastic material generating liquid of the present invention is poured around the bonding portion and held at the mold, and bonded simultaneously with the curing reaction. In this case, the adhesive used for bonding is not particularly limited, and examples thereof include a hot melt adhesive. Moreover, it does not specifically limit as an adhesive agent used for hardening simultaneous adhesion | attachment, For example, a phenol type solution adhesive agent etc. are mentioned.

[Example]
<Synthesis of prepolymer>
Prepolymers were synthesized with the blending compositions shown in Table 1 for the cleaning blade members of each Example and each Comparative Example.
For the synthesis of the prepolymer, generally used polyurethane molding methods can be used, and examples thereof include the following methods. First, the polyol was synthesized by subjecting the polyol to dehydration under reduced pressure at 70 ° C. × 3 mmHg × 3 hours, and then adding a predetermined MDI and reacting in a nitrogen gas atmosphere at 70 ° C. × 3.5 hours.

<Creating a cleaning blade>
The resulting prepolymer was degassed under reduced pressure at 60 ° C. × 3 mmHg × 1 hour. Next, a curing agent composed of a polyol, 1,4-butanediol, ethylene glycol, 1,1,1-trimethylolpropane having a composition shown in Table 1 and a catalyst is removed under reduced pressure at 60 ° C. × 3 mmHg × 1 hour. After foaming, it was mixed with the prepolymer. The mixture was poured into a cleaning blade molding die holding a supporting member treated with an adhesive and heated to 110 ° C., and solidified in the die for 5 minutes to obtain a blade semi-finished product. The obtained blade semi-finished product was cut into a predetermined size and washed with isopropyl alcohol to obtain a cleaning blade. In addition, a sheet for measuring physical properties was prepared using a sheet molding die having a thickness of 2 mm, various physical properties tests were performed, and the results are shown in Table 2. For image evaluation, LASER SHOT LBP-5500 manufactured by Canon Inc. was used.

<Preparation of pressure contact measurement sample>
The cleaning blade was cut to 10 mm to obtain a test piece. This test piece was used for the pressure contact test shown in FIG. The results are shown in Table 2.

  Table 2 shows the measured values for the three types of Examples and the two types of Comparative Examples as the prepolymer blend composition of the sample for measuring physical properties.

  Comparative Example 1 is a distribution product. In Comparative Example 2, the tan δ peak temperature of Comparative Example 1 was lowered, and the general idea for maintaining cleaning properties even in a low temperature atmosphere (tan δ peak temperature decrease = secondary transition point decrease = urethane viscosity even at low temperatures) This is a comparative test based on the concept of maintaining the elastic properties in the same manner as at room temperature.

The results shown in Table 2 show that the pressure contact force A is 102 g / cm or more in each example at 23 ° C., and it can be confirmed that no cleaning failure occurs in the actual image evaluation test machine.
However, in Comparative Examples 1 and 2 in which the pressure A is 113 g / cm or less at 10 ° C., a cleaning failure occurs, and in each example, 120 g / cm or more is shown, and it is recognized that a good image is obtained. Further, Example 3 showing a pressure contact force A of 198 g / cm or more at 0 ° C. can form a good image, and Examples 1 and 2 showing 153 g / cm and 185 g / cm have a slight cleaning defect. In Comparative Examples 1 and 2 of 140 g / cm or less, there is an image defect at all.
In such a state, the pressure contact force B is set in each example in the first half of 90 to 110 so as to reduce the influence of wear on the rotating body in the steady state.
As a result, the pressure contact force ratio (A / B) is good at 1.20 to 1.30 in an atmosphere of 10 ° C., and it is recognized that it is inappropriate at 1.10 or less. Similarly, when the pressure force ratio (A / B) is 1.40 or higher in an atmosphere of 0 ° C., improvement is recognized, good is observed when it is 1.80 or higher, and poor when it is 1.35 or lower. I understand.

  In the measurement of dynamic viscoelasticity in this embodiment, since the frequency is measured at a constant 10 Hz, both the dynamic elastic modulus E ′ and the dynamic loss E ″ are functions of relaxation time or delay time. The measured value of dynamic viscoelasticity is closely related to the stress relaxation of the elastic rubber member.

  As shown in Table 2, when the secondary transition point of the elastic rubber member is lower than 10 ° C. from the peak temperature of tan δ, the storage elastic modulus E ′ is both values at 10 ° C. and 23 ° C. compared to the value at 0 ° C. Is an approximation. In addition, the storage elastic modulus E ′, which is a kind of dynamic elastic modulus at 0 ° C., of the elastic rubber member shown in the examples shows the median value of the storage elastic modulus E ′ in the comparative example 2 It seems that the viscoelastic behavior at low temperature is different between the example and the comparative example.

  In Examples 1 to 3 in which the pressure contact force ratio at 0 ° C. is 1.4 or more and the pressure contact force ratio at 10 ° C. is 1.2 or more, there is no problem in the image evaluation at 10 ° C., and the pressure contact force at 10 ° C. In Examples 1 and 2 where the ratio approximated 1.2, image defects were slightly observed at 0 ° C. However, in Comparative Examples 1 and 2 in which the pressure contact force ratios at 0 ° C. and 10 ° C. were 1.4 and 1.2, respectively, image defects occurred at both 0 ° C. and 10 ° C.

As a result of Table 2, in the cleaning blade for an electrophotographic apparatus in which the elastic rubber member is bonded to the support member, the elastic rubber member has a hardness at 23 ° C. of 70 to 74 IRHD according to the JISK6253 international rubber hardness test micro test method. In addition, the use of polyurethane having a pressure contact force ratio of 1.2 or more in a 10 ° C. atmosphere and 1.8 or more in a 0 ° C. atmosphere as a result of the pressure contact measurement method described in the present invention provides good toner scraping performance. I was able to.

FIG. 3 is a schematic diagram for measuring a pressing force of a cleaning blade. FIG.

Explanation of symbols

1: Elastic rubber member 1
2: Adhesive layer 3: Support member 4: Load cell 5: Pressure support surface 6: Cleaning blade

Claims (4)

In the cleaning blade for an electrophotographic apparatus in which an elastic rubber member made of polyurethane is bonded to a support member, the elastic rubber member made of polyurethane has a hardness at 23 ° C. of 65-80 IRHD according to JISK6253 international rubber hardness test micro test method. The pressure contact force (A) measured when the tip of the elastic rubber member of the cleaning blade was pushed in by 0.1 mm in advance and then pushed in by 1.3 mm at a speed of 1 mm per second, and the pressure contact force measured after 1 minute in that state A cleaning blade for an electrophotographic apparatus, comprising a polyurethane having a pressure contact ratio (A / B) with (B) of 1.2 to 1.7 in an atmosphere of 10 ° C. 2. The cleaning blade for an electrophotographic apparatus according to claim 1, wherein the pressure contact force ratio (A / B) is 1.4 to 3.5 in an atmosphere at 0 [deg.] C. 2. The cleaning blade for an electrophotographic apparatus according to claim 1, wherein the pressure contact force ratio (A / B) is 1.8 to 3.5 in an atmosphere of 0 [deg.] C. The cleaning blade for an electrophotographic apparatus according to any one of claims 1 to 3, wherein a dynamic storage elastic modulus (E ') in an atmosphere of 0 ° C is 60 to 150 MPa.