JP2005345651A - Cleaning blade, method for manufacturing the same and method for cleaning image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cleaning blade excellent in wear resistance even when used for cleaning an image forming apparatus using a polymer toner, and to provide a method for manufacturing the same and a cleaning method. <P>SOLUTION: The cleaning blade comprises a polyurethane elastic body and is used in an image forming apparatus applying an electrostatic transfer process, wherein the polyurethane elastic body has, as constituents, a bifunctional polyol compound (molecular weight Mp, blending quantity Wp), a diisocyanate compound (molecular weight Mi, blending quantity Wi), at least one trifunctional or higher functionality crosslinking agent (molecular weight Mt, blending quantity Wt) and a bifunctional chain extender (molecular weight Md, blending quantity Wd), wherein Mc defined by the expression: Mc=(Wi+Wp+Wt+Wd)/(Wt/Mt) is 2,000<Mc≤8,000. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a residual toner on the surface of a member that carries a toner such as a photoreceptor or a transfer belt or contacts a toner carrying surface in an electrostatic image forming apparatus such as a plain paper copier, a plain paper facsimile, a laser beam printer And a method for manufacturing the same, and a method for cleaning an image forming apparatus using the cleaning blade.

  In order to wipe off and remove toner remaining on the surface of a photoconductor, a transfer belt, and the like after a toner image is transferred to a sheet or the like in an electrostatic image forming apparatus, a thickness of about 1 is conventionally known. A cleaning blade formed by cutting from a polyurethane-based elastic sheet of about 3 mm has been used.

  As a polyurethane elastic body constituting such an elastic body cleaning blade, a polyurethane obtained by reacting a bifunctional polyol compound, a diisocyanate compound, a trifunctional or higher functional crosslinking agent and a bifunctional chain extender is known (Patent Document 1, 2, 3 etc.).

  The cleaning blade disclosed in Patent Document 1 aims to provide a rubber member for electrophotography that can obtain sufficiently stable cleaning characteristics, charging characteristics or development characteristics even when the environment changes. It is formed of a rubber elastic body composed of polyurethane produced from a polyol synthesized from 4-diethyl-1,5-pentanediol and adipic acid and polyisocyanate.

The technique disclosed in Japanese Patent Laid-Open No. 2004-228688 is for an electrophotographic copying machine that hardly wears the photoconductor, hardly causes paper dust or filming with fine toner, and as a result has excellent durability of the image forming apparatus. A high molecular weight polyol having a molecular weight of 1000 to 3000 and a pseudoprepolymer having an isocyanate group content of 8 to 20% prepared from a polyisocyanate and a polycaprolactone ester diol having a molecular weight of 1000 to 3000 for the purpose of providing a method for producing a cleaning blade And a curing agent composed of a low molecular weight polyol having a molecular weight of 60 to 250, mixed and stirred at a hydroxyl group / isocyanate group equivalent ratio of 0.8 to 0.9, poured into a preheated mold, JIS A hardness 65 to 80, 300% modulus 130-250 kg / cm ² , rebound resilience at 45 ° C. of 45 % Or more of the cleaning blade.

The cleaning blade disclosed in Patent Document 3 is intended to provide a cleaning blade having appropriate rebound resilience from a low temperature range to a high temperature range, and a ring opening of a lactone having a lower alkyl group as a substituent as a polyol component. Using polyester polyol, p-phenylene diisocyanate and / or 1,4-cyclohexane diisocyanate as the polyisocyanate component, and the hardness (obtained by curing a urethane prepolymer obtained by reacting them with a curing agent ( JIS A) is a cleaning blade having a rebound resilience of 25 to 70% and a glass transition point of −10 ° C. or lower in a temperature range of 65 to 80 and 0 to 60 ° C.
JP 2001-83855 A Japanese Patent Laid-Open No. 5-278045 Japanese Patent Publication No.7-113807

  However, when the cleaning blade made of the polyurethane elastic body disclosed in Patent Documents 1 to 3 is used for cleaning in an image forming apparatus using a polymerized toner that is currently being put into practical use in response to a request for image sharpening. It was revealed that the wear resistance is not sufficient.

  An object of the present invention is to provide a cleaning blade excellent in wear resistance, a method for manufacturing the same, and a cleaning method even when used for cleaning an image forming apparatus using a polymer toner.

The present invention is a cleaning blade made of a polyurethane elastic body used in an image forming apparatus utilizing an electrostatic transfer process,
The polyurethane elastic body includes a bifunctional polyol compound (molecular weight Mp, blending amount Wp), a diisocyanate compound (molecular weight Mi, blending amount Wi), at least one trifunctional or higher functional crosslinking agent (molecular weight Mt, blending amount Wt), and A bifunctional chain extender (molecular weight Md, blending amount Wd) is a constituent component, and Mc defined by the formula (Equation 3) is
2000 <Mc ≦ 8000
It is characterized by being.
(Equation 3) is
Mc = (Wi + Wp + Wt + Wd) / (Wt / Mt)
It is.

  A cleaning blade made of a polyurethane elastic body having such a configuration has excellent wear resistance even when used for cleaning an image forming apparatus using a polymer toner.

  When Mc is 2000 or less, the moldability is lowered, and when it exceeds 8000, the concentration of crosslinking points is lowered, the crosslinking effect is lowered, and the strength and wear resistance are lowered.

  In the cleaning blade described above, the polyol compound is preferably a polyester polyol.

  A cleaning blade made of a polyurethane elastic body using a polyester polyol has excellent cleaning properties especially when a polymer toner is used.

Another aspect of the present invention is a method for manufacturing a cleaning blade made of a polyurethane elastic body used in an image forming apparatus utilizing an electrostatic transfer process,
The polyurethane elastic body is composed of a bifunctional polyol compound (molecular weight Mp, blending amount Wp), diisocyanate compound (molecular weight Mi, blending amount Wi), at least one trifunctional or higher functional crosslinking agent (molecular weight Mt, blending amount Wt), And a bifunctional chain extender (molecular weight Md, blending amount Wd) to form a polymerization step, and Mc defined by the above formula (Equation 3)
2000 <Mc ≦ 8000
It is characterized by being.

  With the manufacturing method having such a configuration, a cleaning blade made of a polyurethane elastic body having excellent wear resistance can be manufactured even when used for cleaning an image forming apparatus using polymer toner.

  In the above-described method for producing a cleaning blade, the polyol compound is preferably a polyester polyol.

  A cleaning method for an image forming apparatus according to the present invention uses the cleaning blade according to claim 1 or 2.

  The cleaning method having such a configuration is a cleaning method having excellent image sharpness durability even when used for cleaning an image forming apparatus using polymer toner.

  Examples of the bifunctional polyol compound that is a component forming the polyurethane elastic body constituting the cleaning blade of the present invention include polyester polyol, polyether polyol, polycarbonate polyol, and the like. Examples of the polyester polyol include succinic acid, glutaric acid, adipic acid, One or more dicarboxylic acids such as sebacic acid, azelaic acid, maleic acid, ethylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, 1,8- Examples thereof include condensation polyesters obtained by condensation polymerization of one or more of glycols such as octanediol, 1,10-decanediol, and diethylene glycol, and ring-opening polymerization polyesters obtained by ring-opening polymerization of lactones. Moreover, as a polyether polyol, what is obtained by carrying out ring-opening addition polymerization of cyclic ethers, such as ethylene oxide, oxetane, and tetrahydrofuran, to the glycol used for the synthesis | combination of water or said polyester polyol can be illustrated. Two or more polyol compounds can be used in combination.

  Among polyester polyol compounds, using a lactone-based polyol obtained by ring-opening polymerization of ε-caprolactone or valerolactone is a preferable embodiment because a cleaning blade having excellent wear resistance can be obtained. As the lactone-based polyol compound, one having a particularly small molecular weight distribution, specifically, Plaxel-220N (Mw / Mn described in the catalog is 2 or less) is preferably used.

  Examples of the diisocyanate compound that is a component forming the polyurethane elastic body constituting the cleaning blade of the present invention include 4,4′-diphenylmethane diisocyanate, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, naphthalene diisocyanate, 4,4 ′. Aromatic diisocyanate compounds such as phenylene diisocyanate, aliphatic diisocyanate compounds such as ethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, 1,6-hexamethylene diisocyanate (HDI), hydrogenated 4,4′-diphenylmethane diisocyanate (HMDI), 1,4-cyclohexane diisocyanate (CHDI), methylcyclohexylene diisocyanate, isophorone diisocyanate (IP I), hydrogenated m- xylylene diisocyanate (HXDI), alicyclic diisocyanate compounds such as norbornane diisocyanate can be exemplified. Two or more diisocyanate compounds can also be used in combination.

Examples of the trifunctional or higher functional crosslinking agent that is a component forming the polyurethane elastic body constituting the cleaning blade of the present invention include trimethylolpropane, triethylolpropane, pentaerythritol, and triethanolamine. Two or more crosslinking agents can be used in combination. When j types of crosslinking agents are used, the formula (Equation 3) is expressed as follows, where the molecular weight of the jth type of crosslinking agent is Mt _j and the blending amount is Wt _j .
Wt / Mt = Σ (Wt _j / Mt _j )
Calculate as

  Examples of the bifunctional chain extender that is a component forming the polyurethane elastic body constituting the cleaning blade of the present invention include ethylene glycol, propylene glycol, 1,4-butanediol, neopentyl glycol and the like.

  In the production of the cleaning blade, a polyurethane polymerization catalyst may be used. Examples of the polymerization catalyst include organotin catalysts such as dibutyltin dilaurate and tin octylate, triethylenediamine, N-methylmorpholine, N, N, N ', N'-tetramethylethylenediamine, N, N, N', N'-tetramethylhexamethylenediamine, 1,8-diazabicyclo [5,4,0] undecene-7 (DBU), bis (N, N- Examples thereof include tertiary amine catalysts such as dimethylamino-2-ethyl) ether and bis (2-dimethylaminoethyl) ether, carboxylic acid metal salt catalysts such as potassium acetate and potassium octylate, and imidazole catalysts. Among these, the use of a tertiary amine catalyst is preferable.

  The cleaning blade can be produced by a known method. For example, a method for producing a cleaning blade includes a prepolymer production step of producing an isocyanate prepolymer or an isocyanate pseudoprepolymer by reacting a polyol compound and a diisocyanate compound, an isocyanate prepolymer or an isocyanate pseudoprepolymer, a crosslinking agent, and a chain extender. A mixing step of mixing with the components to make a reactive composition, a molding step of forming the reactive composition into a molded body of a predetermined shape using a mold or the like, and when the molded body is a sheet, The cleaning blade can be manufactured by a manufacturing method including a cutting step of cutting the sheet into a predetermined blade shape.

  As a cleaning method using a cleaning blade, a known method can be used. For example, a method of performing cleaning by contacting a member that performs cleaning, such as a photoconductor, a transfer belt, and a roller, with a predetermined angle and a contact pressure.

<Production of cleaning blade>
(Example 1)
Plaxel 220N (average molecular weight 2000; Daicel Chemical Industries) is used as a bifunctional polyol compound, and 75.81 g of 4,4′-diphenylmethane diisocyanate (MDI) is reacted at 70 ° C. for 1 hour with respect to 100 g of NCO. A base end prepolymer was obtained. 43.93 g of Plaxel 220N, 8.64 g of trimethylolpropane (TMP) as a crosslinking agent, and 1,4-butanediol (BD) as a chain extender for the NCO group-terminated prepolymer heated to 80 ° C. 10.01 g of the composition was added as a curing agent component, stirred to obtain a reactive composition, vacuum degassing was performed, and the inner surface was reactive to a cylindrical mold having a diameter of 340 mm and a width of 600 mm. The composition was cast and cured by heating at 150 ° C. for 1 hour, then removed from the mold, post-cured at 120 ° C. for 6 hours, and then allowed to stand at room temperature for 7 days and aged to increase the thickness. A polyurethane elastic sheet having a thickness of 2.0 mm was produced. Mc of this polyurethane elastic body calculated by the above-mentioned formula (Formula 3) was 3700.

  The polyurethane elastic sheet was cut to produce a cleaning blade having a width of 12.5 mm and a length of 326 mm, which was adhered to a predetermined metal fitting using a hot melt adhesive to obtain a cleaning blade unit.

(Example 2)
A cleaning blade unit was prepared in the same manner as in Example 1 except that a composition in which 49.38 g of Plaxel 220N, 6.53 g of TMP, and 11.89 g of BD were used as a curing agent component was used.

  Mc calculated by the above-described equation (Equation 3) of the polyurethane elastic body constituting this cleaning blade was 5000.

(Example 3)
A cleaning blade unit was prepared in the same manner as in Example 1 except that a composition in which 52.04 g of Plaxel 220N, 5.50 g of TMP, and 12.81 g of BD were used as a curing agent component was used.

  Mc of the polyurethane elastic body constituting this cleaning blade calculated by the above-described equation (Equation 3) was 6001.

(Comparative Example 1)
A cleaning blade unit was prepared in the same manner as in Example 1 except that a composition in which 58.96 g of Plaxel 220N, 2.83 g of TMP, and 15.19 g of BD were mixed as a curing agent component was used.

  Mc of the polyurethane elastic body constituting this cleaning blade calculated by the above-described equation (Equation 3) was 11998.

(Comparative Example 2)
A cleaning blade unit was produced in the same manner as in Example 1 except that a composition in which 57.54 g of Plaxel 220N, 3.37 g of TMP, and 14.71 g of BD were mixed as a curing agent component was used.

  Mc of the polyurethane elastic body constituting this cleaning blade calculated by the above-described equation (Equation 3) was 9999.

(Comparative Example 3)
A cleaning blade was manufactured in the same manner as in Example 1 except that the curing agent component was 12.16 g of Plaxel 220, 8.70 g of TMP and 2.46 g of BD were used. However, the polyurethane elastic body sheet in which the reactive composition is cast into a cylindrical mold cannot be successfully molded. Mc of this polyurethane elastic body calculated by the above-mentioned formula (Formula 3) was 1900.

<Evaluation>
The cleaning blade units of Examples 1 to 3 and Comparative Examples 1 and 3 were mounted on IPSIO COLOR 8000 (Ricoh) using a color toner which is a polymer toner, and 2000 image reproduction experiments were performed. After the image reproduction experiment, the ridge line (edge) part in contact with the photosensitive member of the cleaning blade was observed with an optical microscope or a laser microscope. When the abrasion amount of the cleaning blade ridge was 10 μm or less, the wear resistance was evaluated as “good”, and when it exceeded 10 μm, it was evaluated as “bad”. Table 1 shows the calculation results and evaluation results of Mc together.

表１の結果より、本発明の範囲のクリーニングブレードは、真球状に近い重合体トナーを使用した比較的高速の画像形成装置に使用しても耐摩耗性に優れたものであった。

From the results shown in Table 1, the cleaning blade in the range of the present invention was excellent in abrasion resistance even when used in a relatively high-speed image forming apparatus using a polymer toner having a nearly spherical shape.

Claims (5)

A cleaning blade made of a polyurethane elastic body used in an image forming apparatus utilizing an electrostatic transfer process,
The polyurethane elastic body includes a bifunctional polyol compound (molecular weight Mp, blending amount Wp), a diisocyanate compound (molecular weight Mi, blending amount Wi), at least one trifunctional or higher functional crosslinking agent (molecular weight Mt, blending amount Wt), and A bifunctional chain extender (molecular weight Md, blending amount Wd) is a constituent, and Mc defined by the formula (Equation 1) is
2000 <Mc ≦ 8000
The cleaning blade characterized by being.
(Equation 1)
Mc = (Wi + Wp + Wt + Wd) / (Wt / Mt) The cleaning blade according to claim 1, wherein the polyol compound is a polyester polyol. A method of manufacturing a cleaning blade made of a polyurethane elastic body used in an image forming apparatus utilizing an electrostatic transfer process,
The polyurethane elastic body is composed of a bifunctional polyol compound (molecular weight Mp, blending amount Wp), diisocyanate compound (molecular weight Mi, blending amount Wi), at least one trifunctional or higher functional crosslinking agent (molecular weight Mt, blending amount Wt), And a bifunctional chain extender (molecular weight Md, blending amount Wd) to form a polymerization step, and Mc defined by the formula (Equation 2) is:
2000 <Mc ≦ 8000
A method for manufacturing a cleaning blade, wherein:
(Equation 2)
Mc = (Wi + Wp + Wt + Wd) / (Wt / Mt) The method for producing a cleaning blade according to claim 3, wherein the polyol compound is a polyester polyol. A method for cleaning an image forming apparatus using the cleaning blade according to claim 1.