MXPA98003717A - Flexible scraper sheet of shoe abras - Google Patents

Abstract

A flexible scraper blade has a metal bar (13) with the lower part joined by a double-sided adhesive tape (15) to a resilient layer of porous foam (7). The lower part of the foam layer is joined by means of a double adhesive side tape (8) to a shoe (1), which is rigid in the direction of movement of the roller (9) that makes contact with the shoe. The shim has a polyester body (3) and a lower layer or base (5) containing abrasive granules and conductive carbon black. Finally, the end of the scraper blade is immersed in a conductive paste that hardens in a conductive coating (17) that bypasses the conductive layer of the shim and the metal bar. The advantages are the reduced costs and the improved performance, particularly with respect to the strips of packaging in the contact line prev

Description

FLEXIBLE SCRAPER SHEET ABRASIVE SHEET TECHNICAL FIELD This invention relates to the electrophotographic development and, more particularly, relates to a flexible scraper blade operating on a developer roller.

BACKGROUND OF THE INVENTION U.S. Patent No. 5,085,171 of Aulick et al., Assigned to the same assignee to whom this request is granted,. it is directed to a flexible scraper blade having a thin outer metallic layer on a granular surface facing the developer roller. This replaces the earlier rigid scraper blades which would allow the toner layer of the developer roller to vary with the surface variations on the scraper blade itself and with the developer roller with which it comes into contact. These variations cause variations in the visible image achieved by the toner, both in printed and graphic form. A flexible scraper blade ideally eliminates these variations. U.S. Patent No. 5,623,718, assigned to the same assignee to whom this application is assigned, describes the material sold commercially in P1289 / 98MX United States by the transferee of this application and that is the prior art of this application. The scraper blade constitutes a flexible scraper blade in which the flexible scraper ink has a solid binder containing the dispersed granule particles and a conductive filler. This flexible member prolongs the operating life of the scraper blade. Additionally, the scraper blade has a rigid front extension that forms a barrier for almost the entire rear area of the contact or gripping line of the flexible member and the developer roller. This eliminates the possibility of a toner wedge forming on the nip or contact line. When the wedge is formed, it interferes with the ability of the scraper blade to measure or dose the correct amount of toner. The following three * patent applications, assigned to the assignee of this invention, are not the prior art since they share inventors with this application and describe the subject that has been commercially sold for less than a year: the Patent Application of the States. Joined with Serial Number 08 / 724,881 filed on November 3, 1996, now U.S. Patent No. 5,708,943, is directed to flexible scraper blades with a layer of granules containing molybdenum disulfide to eliminate the formation of P1289 / 98MX toner film. The same granule layer is used as the granule layer of the preferred embodiment of this invention. U.S. Patent Application Serial Number 08 / 623,362 filed March 28, 1996, is directed to a conductive tape formula for use with flexible scraper blades. The same conductive ink is used as the conductive ink of the preferred embodiment of this invention. U.S. Patent Application Serial Number 08 / 623,363 also filed on March 28, 1996, currently U.S. Patent No. 5,702,812, is directed to flexible scraper blades with a rigid shim, in the lower part of a layer of foam on which a belt having an abrasive is located. The shim controls the size of the contact line or grip to avoid the formation of a wedge of toner in the line of contact or grip. This invention eliminates the tape by using only a shim with an abrasive surface. A relatively long conductive tape is replaced with conductive abrasive material only in the shim.

SUMMARY OF THE INVENTION In accordance with this invention, a flexible scraper blade comprises a coproductive metal bar P1289 / 98MX having a lower surface to which a resilient lid is attached. The lower surface of the resilient cap has a rigid shim attached to it, the shim has a lower layer of conductive and abrasive material. At the end of the scraper blade, a resilient conductive coating bridges the abrasive layer and the metal rod. For better operation, the lower end of the conductive sheet is at an angle at which the developing roller makes gripping or clamping contact with the middle of the layer of abrasive material.

BRIEF DESCRIPTION OF THE DRAWINGS The details of this invention will be described in connection with the following accompanying drawing in which Figure 1 is a perspective view of the scraper blade and Figure 2 is a cross section of the scraper blade.

BEST MODE FOR CARRYING OUT THE INVENTION The scraper blade of this invention has the desired flexibility with the developer roller but does not have a pre-contact or funnel-shaped point of attachment that may occur with some scraper blades, as discussed above. Leg 1 is a laminate P1289 / 98MX consisting of a polyester layer 3 (Figure 2) and an abrasive and conductive layer 5. The shoe 1 is attached to the lower surface of a layer of resilient foam 7 by means of a double-sided adhesive clamp 8, which can be a commercially available double-sided adhesive tape comprising a thousandth-thick polyester having adhesive on it. both sides. During use, the abrasive and conductive layer 5 makes contact with a developer roller 9. The rigidity of the shim 1 in the direction of the movement of the roller 9, shown by the arrow 11, the process direction, prevents the foam from deforming into the region prior to the contact line or grip and cause the undesirable funnel shape. The rigidity of the shim 1 also avoids an undesirably long rounded contact and mimics the contact or gripping geometry of the steel sheet identically. The region prior to the contact or grip line of the present invention is almost identical to that found with a steel scraper blade. In the long direction of the shim 1, along the length of the developer roller 9, the shim 1 is flexible to conform to the surface of the developer roller. As best seen in Figure 1, the flexible scraper blade of the present invention comprises an aluminum support bar 13, preferably, for P1289 / 98MX example, of an aluminum bar 6063-T5 of 4.0 mm x 10 mm and 231.5 mm in length. In the specific embodiment, the bottom surface 13a (Figure 2) has an upward angle of 6 degrees which compensates for the dimensions in the image forming device, so that the contact or grip line of the shoe 1 and the developer roller 9 can be located precisely in the middle of block 1 (this is because block 1 has a relatively small surface and, therefore, the physical response to be out of center is significant. considerably larger surface, the location of the contact line or grip to the center would not normally be significant). As shown in Figure 1, the shim 1 has the same extension as the length of the bar 13. The porous foam layer 7 has a thickness of from about 2.0 to about 3.0 mm and extends the entire length of the bar. support 13. A preferred foam material is a PORON foam, a polyurethane foam available commercially from Rogers Corp. as # 4701-40-20093-1064. The foam layer 7 can be attached to the underside of the support bar using any conventional adhesive material that bears the forces on the scraper blade during use. In the modality, this material P1289 / 98 X adhesive 15 is a commercially available double-sided adhesive tape comprising 1 mil thick polyester having adhesive on both sides. The foam layer 7 is resilient. Before assembling or assembling the shim 1 on the scraper blade, the adhesive and the conductive layer 5 is applied to the polyester layer 3. This is effected by coating with liquid, preferably on sheets or sheets of polyester 3. After cured, the sheets or sheets are mechanically cut in a very thin connection and then manually separated and applied to the foam 7, the adhesive tape 8 is first applied to the foam 7. The formula for the liquid application of the layer 5 is the same as that of the preceding application directed to the formula having molybdenum disulfide, which is as follows: FORMULATION OF THE AGGLUTINATING LAYER Material Percent by Weight Polyurethane (Z001 by Lord Chemical) 15 Molybdenum disulfide (plates with an average particle size of 10 um) Carbon black (Degussa's XE-2) 5 Silicon carbide (with an average particle size of 20 um) The previous formulation of the abrasive layer and P1289 / 98MX conductive is mixed thoroughly and applied to form a thin, solid coating 5 (eg, from about 25 to about 35 microns thick) in layer 3 of 14 mil polyethylene terephthalate. 5 percent by weight of carbon black results in an electrical resistance less than 1 x 10E5 (ten to fifth power) ohms / square. Molybdenum disulfide eliminates film formation, at least when used with acrylic-based toner for which this invention is particularly designed (ie, toners such as those of OPTRA laser printers, sold commercially by the transferee of this invention). The polyurethane forms a body containing silicon carbide as an abrasive and carbon black as the conductive filler and the molybdenum disulfide mixed perfectly in the solid coating 5. Silicon carbide are granule particles for abrasion. Granule particles generally have a particle size of from about 8 to about 20 microns, preferably about 20 microns in diameter, and preferably are a ceramic oxide such as for example silicon carbide (e.g., NORBIDE, commercially available from Norton. Corp.). Other materials from P1289 / 98MX granule which are useful in the present invention include aluminum oxide, diamond powder, titanium dioxide, zirconium dioxide and mixtures thereof. Carbon black provides conductivity. The conductivity allows electric current to be applied to the scraper blade which will be led to the developer roller 9. The conductive material for use in the present invention is one in which conductive particles are included and these are perfectly dispersed in the solid layer 5. conductive materials that may be used in the present invention, include carbon black, graphite, metallic fillers, ionic salts and mixtures thereof. The preferred conductive material is carbon black. The conductive particles must provide the layer 5 with an electrical resistance of less than about 1 x 10E5 ohms / square. The charge of carbon black in the above specific formula greater than 5 weight percent results in a surface roughness which is very smooth for the desired operation of layer 5. As the layer 5 is conductive in its entirety, according to the layer 5 wears, the electrical properties of the scraper blade remain constant. The shoe 1 is attached to the lower part of the resilient foam layer 7 (that is, to the face of the layer 7 facing or facing the developer roller P1289 / 98MX 9). When designing shoe 1 it is important that you maintain an appropriate balance between rigidity and flexibility. Specifically, the shoe 1 must maintain the rigidity in the process direction (the direction 11 in which the developer roller 9 moves), and still maintain the flexibility in a direction perpendicular to the process direction (i.e., over the length of the scraper blade). It is the rigidity of the shim 1 that provides the proper configuration of the contact line or grip, while the flexibility over the length of the scraper blade allows the blade to conform or adapt closely to the surface of the developer roller 9. In this way, the scraper blade of the present invention provides the benefits of both an inflexible steel scraper blade and a flexible scraper blade. Any material that maintains this balance of flexibility / rigidity can be used as the body 3 of the shim 1 of the present invention. In deciding whether a particular material is suitable for use as shoe 1, both the nature of the material and its thickness will be important. Specifically, if a material is very thin or very soft, it may not provide the appropriate degree of rigidity required, whereas if it is very thick or very hard, it may not show the required degree of flexibility. Footwear 1 can P1289 / 98MX manufactured from any material that has the required exchange or flexibility / rigidity concession and preferably is a material that does not corrode and that has an appropriate cost. Examples of material that can be used include brass, phosphor bronze, beryllium copper, polycarbonate, polyester and stainless steel. Polyester is the particularly preferred material, because it is easier than the metal to cut to the desired shape. Stainless steel is the preferred second, due to its attractive cost and the fact that it does not corrode. As an example, when stainless steel is used as shim 1, a thickness below approximately 0.004 inches (0.102 mm) makes the shim very fragile. When polyester is used, specifically MYLAR polyethylene terephthalate available commercially from Dupont, a caliper thickness 1 below approximately 0.356 mm (0.014 inches) makes the material very flexible; a greater thickness is required. On the other hand, stainless steel in a thickness greater than approximately 0.305 mm (0.012 inches) is very thick and does not provide the required degree of flexibility. Thus, the thickness for the selected shim material is simply a function of the stiffness / flexibility required. The material P1289 / 98MX of shim used in the scraper blade of the present invention should have a thickness of from about 0.5 to about 31.0, preferably from about 10.0 to about 25.5 inches of deflection / inches of length / pound of force. This rigidity is measured as follows: a shim of 4 mm wide is fixed at one end and is loaded or receives a load on the other (the magnitude of the load may be sufficiently low to avoid plastic deformation of the shim); then the loaded displacement is emitted. Putting it in another way, the shim must have a stiffness that is greater than that of polyester 0.014 inches thick and less than or equal to 0.012 inches thick stainless steel. The preferred shoe 1 has a body, layer 3, which is 0.014 inch thick polyester, whose stiffness is slightly increased also by the abrasive / conductive layer 5. The electrical conductivity between the aluminum rod 13 and the abrasive layer / conductive 5 is provided by a coating of conductive adhesive 17 on one or both ends of the scraper blade. This forms a continuous layer that puts the abrasive / conductive layer 5 and the aluminum bar 13 in contact, thereby providing an electrical path between the layer 5 and the bar 13. The ends of the sheet P1289 / 98MX scraper are beyond the location on the developer roller 9 that reveals an image, so that the slight irregularity of the toner flow of the adhesive 17 is not material for image formation. The adhesive material 17 is the same as that of the preceding application with Serial No. 08 / 623,362. This material is a conductive paste comprising from about 70% to about 96% (preferably from about 94% to about 96%) of a flexible elastomer having a hardness of less than about 50 Shore A when dry (such as vulcanizable silicone). room temperature or latex rubber) and from about 4% to about 30% (preferably from about 4% to about 6%) of an electrically conductive particulate material (such as carbon black). This paste also optionally may include a conventional solvent, such as methyl ethyl ketone. The adhesive material can be applied in any convenient way to form the coating 17. When it is dissolved in the solvent, it can be spread, painted or sprayed. Preferably, the end of the scraper blade is simply immersed in the material having some solvent and the resulting coating is then hardened by evaporation of the solvent to form the P1289 / 98MX coating 17. The developer roller 9 comprises a semiconductor organic elastomer charged to a predetermined potential by a fixed potential source. The roller 9 is brought into contact with a charged toner supply as it rotates clockwise. The toner is usually charged in main form up to a polarity, same polarity as that of the roller while having a significant amount of toner charged to the opposite polarity. The sector of the roller 9 that meets the scraper blade carries this toner and, the toner of opposite polarity is blocked by the loaded scraper blade, so that only a thin layer of toner passes to the scraper blade and that thin layer is loaded on the scraper blade. predominant form to the correct polarity. The advantages of the scraper blades of this invention are reduced costs on the blades that have a separate lamination of the shim, an improved performance, particularly in the reduction of the bands (sometimes referred to as skid marks), which occur in areas on the gray scale by varying the toner flow, caused by the toner that is packed immediately before the line of contact or grip (pre-packed to the line of contact or grip) and the elimination of the fundamental damage during assembly what P1289 / 98MX can occur from the developer roller that rotates in the opposite direction, thus moving the lamination away from contact with the developer roller (normally, these can not be repaired). This invention greatly reduces packing prior to contact line or grip on the previously known flexible scraper blades. The variation in the form and the materials used are easily visualized and will be within the scope of this invention. Coverage is sought as provided by law with particular preference to the accompanying claims.

P1289 / 98MX

Claims (16)

1. NOVELTY OF THE INVENTION Having described the present invention, it is considered as a novelty and, therefore, the content of the following CLAIMS is claimed as property: 1. A scraper blade for measuring or dosing charged electrophotographic toner, which are held in a developer roller, physically contacting one sector of the roller with a surface of the sheet that is electrically charged, the sheet comprises a support member for positioning the sheet adjacent to the roller, a resilient layer attached to the support member, a shoe attached to the resilient layer on a first side, the shim will be rigid in the process direction of the developer roller, at least the outer surface on a side opposite the first side of the shim will be abrasive and electrically conductive and an electrical conductor on the scraper blade in electrical contact with the outer surface of the shim. The scraper blade according to claim 1, wherein the shim has a polyester body and the outer surface of the shim is a layer of material P1289 / 98MX abrasive and conductive. 3. The scraper blade according to claim 2, wherein the resilient layer is a porous material. 4. The scraper blade according to claim 1, wherein the resilient layer is a porous material. The scraper blade according to claim 4, wherein the electrical connector is a continuous coating of a layer of electrically conductive material at one end of the scraper blade that contacts the outer surface and the support member. The scraper blade according to claim 1, wherein the electrical connector is a continuous coating of a layer of electrically conductive material at one end of the scraper blade that contacts the outer surface and the support member. The scraper blade according to claim 2, wherein the electrical connector is a continuous coating of a layer of electrically conductive material at one end of the scraper blade that contacts the outer surface and the support member. The scraper blade according to claim 3, wherein the electrical connector is a continuous coating of a layer of electrically conductive material at one end of the scraper blade that contacts the outer surface and the support member. P1289 / 98MX 9. The scraper blade according to claim 8, wherein the shim has a resin body and wherein the outer surface is a coating on the body of about 25 to 35 microns thick of abrasive particles and conductive charge in a body of resin. The scraper blade according to claim 1, wherein the shim has a resin body and wherein the outer surface is a coating on the body of about 25 to 35 microns thick of abrasive particles and conductive filler in a resin body. The scraper blade according to claim 2, wherein the shim has a resin body and wherein the outer surface is a coating on the body of about 25 to 35 microns thick of abrasive particles and conductive filler in a resin body. The scraper blade according to claim 3, wherein the shim has a resin body and wherein the outer surface is a coating on the body of approximately 25 to 35 microns thick of abrasive particles and conductive filler in a resin body. The scraper blade according to claim 4, wherein the shim has a resin body and wherein the outer surface is a coating on the body of about 25 to 35 microns thick of abrasive particles and conductive filler in a resin body. P1289 / 98MX 14. The scraper blade according to claim 5, wherein the shim has a resin body and wherein the outer surface is a coating on the body of about 25 to 35 microns thick of abrasive particles and conductive filler in a body of resin. 15. The scraper blade according to claim 6, wherein the shim has a resin body and wherein the outer surface is a coating on the body of approximately 25 to 35 microns thick abrasive particles and conductive filler in a resin body. 16. The scraper blade according to claim 7, wherein the shim has a resin body and wherein the external surface is a coating on the body of about 25 to 35 microns thick of abrasive particles and conductive filler in a resin body. P1289 / 98MX