JP6530293B2 - Cleaning blade - Google Patents

Description

  The present invention relates to a cleaning blade for removing residual toner on the surface of a photosensitive member in an electrostatic image forming apparatus such as a plain paper copying machine, a plain paper facsimile, and a laser beam printer.

  In recent years, in the image forming apparatus, it has become mainstream to use polymerized toner which is fine particle toner. The polymerized toner is capable of sharpening the image as compared with the pulverized toner conventionally used. However, due to the shape (substantially spherical shape) and the fine particle diameter, slippage of the polymerized toner may occur at the time of cleaning and a cleaning failure may occur. Therefore, when using a polymerized toner, it is essential to further improve the cleaning performance of the cleaning blade.

  In addition, since the tendency of the long life of each unit used in the image forming apparatus is remarkable and the cleaning blade is used for a long time, the cleaning blade is also required to have high durability.

For example, in Patent Document 1 below, a cast-type polyurethane member is produced by curing and molding a polyurethane composition containing at least a polyol and an isocyanate compound, and the polyurethane member has a hard diameter of 0.5 μm or more and less than 12 μm. A cleaning blade member including a segment aggregate and having an outer diameter of a hard segment a (μm) and a number b (pieces), axb per 1000 μm ² of 70 or more and less than 1050 is described ing.

  Further, in Patent Document 2 described below, a cleaning in which at least a portion in contact with a member to be cleaned includes a polyurethane rubber and has an endothermic peak top temperature in a range of 180 ° C. or more and 220 ° C. or less by differential scanning calorimetry. A blade, wherein the polyurethane rubber has hard segments and soft segments, the average particle diameter of hard segment aggregates is 5 μm to 20 μm, and the particle size distribution of hard segment aggregates (standard deviation σ) The cleaning blade whose is 2 or more is described.

JP, 2010-134111, A JP, 2014-66787, A

  However, when the present inventors examined the inventions described in the above patent documents, the cleaning blade according to these inventions is particularly difficult to increase the hardness required for cleaning spherical and small particle size toners, and therefore cleaning is particularly effective. There was room for further improvement in terms of gender.

  The present invention has been made in view of the above-mentioned circumstances, and an object thereof is to provide a cleaning blade which is excellent in cleaning property and excellent in durability.

The cleaning blade according to the present invention is a cleaning blade including a polyurethane elastic body used in an image forming apparatus utilizing an electrostatic transfer process, wherein the polyurethane elastic body has two or more layers including an edge layer and a substrate layer. The edge layer is a polyurethane obtained by reacting a diisocyanate compound, a bifunctional polyester polyol, trimethylolpropane, and 1,4-butanediol, and the number average molecular weight of the diisocyanate compound. Is Ma, the weight ratio is a (provided that the total amount of polyurethane constituting the edge layer is 1), the weight ratio of the bifunctional polyester polyol is b, the molecular weight of trimethylolpropane is Mc, the weight ratio is c, and 1 When the weight ratio of 2,4-butanediol is d, the following formula (1 In represented by the proportion of the hard segment aggregates polyurethane constituting the edge layer (W _Hs) is not less 40% by weight or more (however, a 100 wt% of the total amount of the polyurethane constituting the edge layer),
(W _Hs ) = 100 (a−1.5 Ma (c / Mc) + d) / (a + b + c + d) (1)
And, when the total amount of the hard segment aggregate is 100% by weight, the ratio of those having an average particle diameter of 20 to 80 μm is 50 to 100% by weight.

In the above cleaning blade, the polyurethane constituting the edge layer is obtained by reacting a diisocyanate compound, a bifunctional polyester polyol, trimethylolpropane and 1,4-butanediol, and the ratio of hard segment aggregates (W _{Hs 2} ) is 40% by weight or more, and when the total amount of hard segment aggregates is 100% by weight, the proportion of particles having an average particle diameter of 20 to 80 μm is 50 to 100% by weight. As a result, the hardness of the edge layer can be increased, and the cleaning performance of the cleaning blade can be improved while the durability can be improved.

  In the cleaning blade, the base material layer is a polyurethane obtained by reacting a polyol component containing polytetramethylene ether glycol, an isocyanate component containing tolylene diisocyanate, and a trifunctional crosslinking material. Is preferred. When the base material layer is made of polyurethane obtained by reacting the respective materials, the base material layer exhibits high elasticity and low temperature dependency, and as a result, the durability of the laminated cleaning blade is further enhanced. And creep property can be improved.

  The cleaning blade according to the present invention comprises a support made of a metal plate, a polyurethane elastic body, and an adhesive layer for adhering the support and the polyurethane elastic body. In the present invention, in particular, as a polyurethane elastic body, one having a laminated structure of two or more layers having an edge layer and a base material layer is used (in the case of a laminated structure of three or more layers, two base layers are used). It shall consist of the above). When the residual toner is cleaned by the cleaning blade in the image forming apparatus, the edge of the edge layer abuts on the image carrier, and the residual toner is scraped off to clean the toner.

In the present invention, the polyurethane constituting the edge layer is obtained by reacting a diisocyanate compound, a bifunctional polyester polyol, trimethylolpropane and 1,4-butanediol. Then, the number average molecular weight of the diisocyanate compound is Ma, the weight ratio is a (however, the total amount of polyurethane constituting the edge layer is 1), the weight ratio of the bifunctional polyester polyol is b, the molecular weight of trimethylolpropane is Mc, Assuming that the weight ratio is c and the weight ratio of 1,4-butanediol is d, the ratio (W _Hs ) of hard segment aggregates of polyurethane constituting the edge layer represented by the following formula (1) is 40 % Or more (however, the total amount of polyurethane constituting the edge layer is 100% by weight), and when the total amount of hard segment aggregates is 100% by weight, the proportion of those having an average particle diameter of 20 to 80 μm Is 50 to 100% by weight. Thus, as the polyurethane constituting the edge layer, the hard layer ratio is high, and the particle diameter of the hard segment aggregate is adjusted to a relatively large range, thereby achieving high hardness of the edge layer material, and the cleaning property Can be particularly enhanced.

  As an isocyanate component which comprises an edge layer, diphenylmethane diisocyanate (p-MDI) is mainly used. Other isocyanates that can be used as the isocyanate component include tolylene diisocyanate (TDI), 1,6-hexamethylene diisocyanate, 2,2,4 (2,4,4) -trimethylhexamethylene diisocyanate, p-phenylene diisocyanate, 4,4'-Dicyclohexamethylene diisocyanate, 3,3'-dimethyldiphenyl 4,4'-diisocyanate, dianisidine diisocyanate, m-xylene diisocyanate, tetramethylxylene diisocyanate, isophorone diisocyanate, 1,5-naphthylene diisocyanate Etc.

  As the bifunctional polyester polyol constituting the edge layer, polycaprolactone polyol, polyester polyol or polytetramethylene ether glycol can be used, but in consideration of the abrasion resistance of the edge layer, polycaprolactone polyol is preferably used. It is possible. Polycaprolactone polyols include linear glycols such as ethylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, diethylene glycol; 1,2-propylene glycol It can obtain by ring-opening addition of (epsilon) -caprolactone by using side chain containing glycols, such as a 1, 3- butanediol and neopentyl glycol, etc. as an initiator. Polycaprolactone polyols using these initiators can be produced by known methods.

  By using polycaprolactone polyol in the edge layer, it is possible to manufacture a cleaning blade made of a polyurethane elastic body excellent in abrasion resistance. However, in addition to the polycaprolactone polyol, other polyol compounds can be used without limitation in the range not impairing the effects of the present invention, and lactone polyester polyols other than polycaprolactone polyols, polyether polyols, polyester polyols, polycarbonate polyols Are illustrated.

In the present invention, in addition to the diisocyanate compound and the bifunctional polyester polyol, trimethylolpropane as a crosslinker and 1,4-butanediol as a chain extender are used as materials constituting the edge layer. And in this invention, the point which the ratio (W _Hs ) of the hard segment aggregate of the polyurethane which comprises an edge layer calculated by following formula (1) becomes 40 weight% or more is a 1st characteristic.
(W _Hs ) = 100 (a−1.5 Ma (c / Mc) + d) / (a + b + c + d) (1)

  Furthermore, in the present invention, when the total amount of hard segment aggregates is 100% by weight, the second feature is that the ratio of those having an average particle diameter of 20 to 80 μm is 50 to 100% by weight. By providing the first feature and the second feature, the cleaning blade according to the present invention can increase the hardness of the edge layer, and the durability and the cleaning property can be improved. In addition, the measuring method of the average particle diameter of the hard segment aggregate of polyurethane is mentioned later.

  In the present invention, TDI is mainly used as the isocyanate component constituting the substrate layer. TDI includes 2,4-tolylene diisocyanate (2,4-TDI) and 2,6-tolylene diisocyanate (2,6-TDI), but only one of them is used in the present invention. It is also good, and you may mix and use. Other isocyanates that can be used as the isocyanate component include p-MDI, 1,6-hexamethylene diisocyanate, 2,2,4 (2,4,4) -trimethylhexamethylene diisocyanate, p-phenylene diisocyanate, 4,4 '-Dicyclohexamethylene diisocyanate, 3,3'-dimethyldiphenyl 4,4'-diisocyanate, dianisidine diisocyanate, m-xylene diisocyanate, tetramethylxylene diisocyanate, isophorone diisocyanate, 1,5-naphthyl diisocyanate, etc. Be However, when considering the impact resilience under a low temperature and low humidity environment (temperature 10 ° C., humidity 15%), it is preferable to contain 90% by weight or more of TDI as an isocyanate component constituting the substrate layer, and only TDI It is more preferable to contain.

  It is preferable to mainly use polytetramethylene ether glycol as a polyol component which comprises a base material layer. With a polyurethane obtained by reacting polytetramethylene ether glycol with TDI described later, it is possible to suppress a decrease in impact resilience under a low temperature environment. In consideration of impact resilience under a low temperature environment, the number average molecular weight of the polytetramethylene ether glycol is preferably 500 to 3,000, and more preferably 1,000 to 2,000.

  In addition to polytetramethylene ether glycol, polycaprolactone polyol or polyester polyol may be contained as a polyol component constituting the substrate layer, but in consideration of impact resilience under a low temperature and low humidity environment, the substrate layer is constituted. It is preferable to contain only polytetramethylene ether glycol as the polyol component to be removed.

  Examples of trifunctional crosslinking agents used together with polytetramethylene ether glycol and TDI when producing a polyurethane of the base layer include triethanolamine (hereinafter, also referred to as "TEA"), trimethylolpropane (hereinafter, "TMP" Also referred to), glycerin and the like. Among these, it is preferable to use TEA, in consideration of the setting resistance of the polyurethane.

  In addition to the polytetramethylene ether glycol, TDI and trifunctional crosslinker, a chain extender may be used as needed in producing the polyurethane of the base layer. As a chain extender, a chain extender known in the technical field of polyurethane can be used, and specifically, ethylene glycol, 1,3-propylene glycol, 1,4-butanediol, diethylene glycol, neopentyl glycol and the like Glycols of ethylenediamine, hexamethylenediamine, 4,4'-diaminodiphenylmethane, m-phenylenediamine, 3,3'-dichloro-4,4'diaminodiphenylmethane (MOCA), 3,5-diethyl-2,4-toluene Diamines such as 3,5-diethyl-2,6-toluenediamine, 3,5-bis (methylthio) -2,4-toluenediamine, 3,5-bis (methylthio) -2,6-toluenediamine, etc. It can be illustrated. Among them, MOCA, 3,5-bis (methylthio) -2,4-toluenediamine and 3,5-bis (methylthio) -2,6-toluenediamine are preferable in view of the physical properties of the polyurethane, and the environmental aspect 3,5-bis (methylthio) -2,4-toluenediamine and 3,5-bis (methylthio) -2,6-toluenediamine are particularly preferred in consideration of the safety of the present invention.

  The NCO / OH equivalent ratio (NCO index) in the polyurethane stock solution containing the polyol component, the isocyanate component, the crosslinker and the chain extender when producing the polyurethane constituting the base material layer and the edge layer according to the present invention is It is preferably 0.90 to 1.20, and more preferably 0.95 to 1.15.

  The polyurethane constituting the edge layer and the substrate layer can be produced by reacting the polyol component and the isocyanate component as it is, but at least a part of the polyol component and the isocyanate component form a prepolymer in advance, The prepolymer may be reacted with the remaining polyol component, and the curing component containing the crosslinking agent and the chain extender.

  In the present invention, the thickness of the polyurethane elastic body constituting the cleaning blade is 1.8 mm, of which the thickness of the edge layer is 0.5 mm, and the thickness of the base layer is 1.3 mm, though it varies depending on the specification of the product used. Are illustrated.

  The cleaning blade according to the present invention can be manufactured by, for example, a manufacturing method having the following forming process.

  1) A polyurethane stock solution containing a polyol component, an isocyanate component, a crosslinking agent and a chain extender is cast in a sheet form and reacted and cured to obtain a base sheet, and the base sheet is cut to obtain a polyurethane elastic body. In addition, 120 degrees C or less is preferable, and, as for the temperature (hardening temperature) at the time of carrying out the reaction hardening of the polyurethane which comprises an edge layer, 110 degrees C or less is more preferable. By producing the edge layer-constituting polyurethane at a low curing temperature (= forming temperature), it is possible to increase the hard segment aggregate ratio and adjust the average particle size to the desired range. The lower limit of the curing temperature is not particularly limited as long as it is a temperature at which the polyurethane reacts and cures, but for example, about 80 ° C. is exemplified. In sheet forming, a centrifugal forming method is generally used.

  2) A polyurethane elastic body is adhered to a support (such as a metal fitting) for mounting on an image forming apparatus with an adhesive or the like to form a cleaning blade.

  Hereinafter, examples that specifically show the configuration and effects of the present invention will be described. In addition, the evaluation item in an Example etc. measured as follows.

(1) Hardness The hardness (°) of polyurethane was measured at 23 ° C. in accordance with JIS-K6253. In addition, the hardness produced the laminated body of a total of 12 layers which laminated | stacked edge layer 6 layer and base material layer 6 layers alternately, and measured it from the both sides of the edge layer side and the base material layer side. The hardness measured from the edge layer side is referred to as hardness X, and the hardness measured from the base layer side is referred to as hardness Y.

(2) Rebound resilience The resilience (%) of polyurethane was measured at 23 ° C. in accordance with JIS-K 6255. In addition, the impact resilience produced the laminated body of a total of 12 layers which laminated | stacked edge layer 6 layer and base material layer 6 layers alternately, and was measured from the both sides of the edge layer side and the base material layer side. The impact resilience measured from the edge layer side is referred to as impact resilience X, and the impact resilience measured from the base layer side is impact resilience Y.

(3) Mechanical Properties The Young's modulus (MPa) of the polyurethane was measured in accordance with JIS K 6254, and the permanent elongation (%) was measured at 23 ± 3 ° C. in accordance with JIS K 6273.

(4) Cleanability The prepared cleaning blade sample was subjected to cleaning evaluation in a low temperature and low humidity environment (temperature 10 ° C., humidity 15%). The evaluation method was evaluated based on the number of sheets in which toner slip-through (cleaning failure) occurred after cleaning when 100 sheets were printed. When the number of cleaning defects is 1 or less (incidence 1% or less) is ○ (excellent cleaning ability), and when the number of cleaning defects is 2 or more (incidence 2% or more) is × (cleanability) Bad).

(5) Durability The obtained cleaning blade is attached to a Minolta Co., Ltd. plain paper copying machine, and a black / white 7% character chart is covered under normal temperature and normal humidity (temperature 23 ° C., humidity 65%). As a copy image, it was continuously performed at a rate of 25 sheets per minute, and the time for the amount of wear of the edge of the cleaning blade to reach 50 μm was checked every 20 hours. The arrival time was 100 hours or more as 〇 (good durability), and less than 100 hours as × (poor durability).

(6) Average particle diameter of hard segment aggregates The surface of the cleaning blade is observed at 200 times its original size using VK-X200 manufactured by KEYENCE Corporation, and 50 hard segments present in an area of 1 mm × 1.4 mm are arbitrarily selected. It extracted and measured the average of the particle size.

(7) Number Average Molecular Weight The number average molecular weight was measured by GPC (gel permeation chromatography) and converted to standard polystyrene.
GPC apparatus: Shimadzu Corporation LC-10A
Column: Three columns of Polymer Laboratories (PLgel, 5 μm, 500 Å), (PLgel, 5 μm, 100 Å), and (PLgel, 5 μm, 50 Å) are connected and the flow rate used: 1.0 ml / min
Concentration: 1.0 g / l
Injection volume: 40 μl
Column temperature: 40 ° C
Eluent: Tetrahydrofuran

Production Example of Polyurethanes A to D At the blending ratio described in Table 1, isocyanate group-terminated prepolymers 1 and 2 were produced. In addition, regarding Prepolymer 1, the compounding quantity of each component is represented by the ratio when the whole quantity of prepolymer is made into 100 weight%, and about Prepolymer 2, the compounding quantity of each component makes PTMG-100S 100 parts by weight. Expressed by the ratio of Polyurethanes A to D were produced by reacting the polyol component, the crosslinker, and / or the chain extender at the blending ratios described in Table 1 in Prepolymers 1 and 2.

Examples 1-2
An edge layer made of polyurethane A, B or C having a thickness of 0.5 mm was produced by centrifugal molding using a polyurethane stock solution as a raw material of polyurethanes A to C.

  Furthermore, a polyurethane undiluted | stock solution used as the raw material of polyurethane D was thrown into the inner peripheral side of the edge layer manufactured beforehand, and the base material layer which consists of polyurethane D which has 1.3 mm thickness was manufactured by centrifugal molding. The results are shown in Table 2.

Comparative Example 1
A cleaning blade sample was prepared in the same manner as in Examples 1 and 2 except that the edge layer and the base material layer were both formed of polyurethane A, B, C, or D single layer. The results are shown in Table 2.

Each raw material used is as follows.
p-MDI; Mitsui Chemicals, Inc. Coronate T-80 (2,4-TDI / 2, 6-TDI = 80/20); Tosoh Corporation PCL 2000 (polycaprolactone diol whose initiator is linear glycol, number average) Molecular weight: 2000); Daicel Chemical Industries, Ltd. PTMG-1000S (polytetramethylene ether glycol, number average molecular weight: 1000); Mitsubishi Chemical Corporation: PCL 4000 (polycaprolactone diol having linear glycol as an initiator, number average molecular weight: 4000); Daicel Chemical Industries, Ltd. TMP (trimethylolpropane); Mitsubishi Gas Chemical Co., Ltd. BD (1,4-butanediol); BASF Idemitsu Co., Ltd. Etacure 300 (3,5-bis (methylthio) -2,4-toluenediamine and Mixture of 3,5-bis (methylthio) -2,6-toluenediamine Compound); made by Albemarle

Claims (2)

A cleaning blade comprising a polyurethane elastic body used in an image forming apparatus utilizing an electrostatic transfer process, comprising:
The polyurethane elastic body has a laminated structure of two or more layers having an edge layer and a substrate layer,
The edge layer is a polyurethane obtained by reacting a diisocyanate compound, a bifunctional polyester polyol, trimethylolpropane, and 1,4-butanediol,
The number average molecular weight of the diisocyanate compound is Ma, the weight ratio is a (however, the total amount of polyurethane constituting the edge layer is 1), the weight ratio of bifunctional polyester polyol is b, and the molecular weight of trimethylolpropane is Mc, When the weight ratio is c and the weight ratio of 1,4-butanediol is d, the ratio (W _Hs ) of hard segment aggregates of polyurethane constituting the edge layer is represented by the following formula (1): 40% by weight or more (however, the total amount of polyurethane constituting the edge layer is 100% by weight),
(W _Hs ) = 100 (a−1.5 Ma (c / Mc) + d) / (a + b + c + d) (1)
And, when the total amount of the hard segment aggregate is 100% by weight, the ratio of one having an average particle diameter of 20 to 80 μm is 50 to 100% by weight.   The polyurethane according to claim 1, wherein the base material layer is a polyurethane obtained by reacting a polyol component containing polytetramethylene ether glycol, an isocyanate component containing tolylene diisocyanate, and a trifunctional crosslinking material. Description cleaning blade.