JP4518703B2 - Paper sheet separating member - Google Patents

Description

【図面の簡単な説明】
【図１】本発明の紙葉類分離部材におけるポリオレフィンワックスの分散状態の模式図である。
【符号の説明】
１ ポリウレタン
２ ポリオレフィンワックスの界面溶融部分
３ ポリオレフィンワックス[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a paper sheet separating member for the purpose of preventing double feeding in a paper feeder of various OA devices such as a copying machine, a facsimile machine, and a printer. More specifically, the present invention can maintain a friction coefficient over a long period of time. The present invention relates to a paper sheet separating member capable of preventing occurrence of “squealing” and preventing contamination during printer printing.
[0002]
[Prior art]
In the paper feeding device, a paper sheet separating member is disposed opposite to a rotating feed roller, and the paper sheet separating member is pressed against the feed roller. As the paper sheet separating member, one made of ethylene / propylene rubber has been generally used, and in recent years, one made of polyurethane has been used.
[0003]
In this conveyance, when a plurality of paper sheets are supplied between the feed roller and the paper sheet separating member, the paper sheets on the paper sheet separating member side are between the paper sheet separating members. Double feed is prevented by the frictional force acting on the. The paper sheet on the paper sheet separating member side is conveyed by the rotation of the feed roller when it reaches the feed roller side.
[0004]
[Problems to be solved by the invention]
However, it is inevitable that such a paper sheet separating member is worn out in contact with the paper sheet with time and the friction coefficient becomes unstable due to the paper powder of the paper sheet. There is a problem in that it causes leaf double feed and paper feed error (JAM).
[0005]
Further, when the paper sheet separating member and the paper sheet are slid, an abnormal sound called “squeal” is generated. In order to suppress the occurrence of this squeal, a cork-filled rubber or the like has been conventionally used. However, in that case, there is a problem that the wear resistance and the coefficient of friction maintenance characteristic are insufficient.
[0006]
In such a phenomenon, the pad is fixed in a state where a certain pressing force is applied to the roll, and in this state, the frictional resistance between the roll, paper / paper, pad / paper, and paper is successively reduced. Ideally, the frictional resistance between them depends on the pad material and surface condition, and it is extremely difficult to adjust the frictional resistance, especially with long-term use. If the surface condition due to friction on the pad surface changes, the above-mentioned problems are unavoidable.
[0007]
In view of such technical problems, Japanese Patent Application Laid-Open No. 8-245007 discloses an automatic supply in which 1 to 200 parts by weight of spherical particles having an average particle diameter of 1 to 300 μm are added to 100 parts by weight of a pad material. A paper pad is described.
That is, this prior art is intended to solve the above technical problem by adding spherical particles such as spherical silica, spherical silicone rubber, glass beads and the like having a specific particle size to the pad material.
[0008]
However, it is difficult to say that the above spherical particles have excellent miscibility or affinity with the pad material, and it is inevitable that the spherical particles will fall off while being used over a long period of time. It cannot necessarily be said that the pad for transporting paper sheets is excellent.
[0009]
Furthermore, in recent years, the use field has expanded with the progress of miniaturization and cost reduction of color printers, such as inkjet printers, and it is realistic that a variety of paper sheets must be handled. There is a request. In an inkjet printer, manufacturers of each company are demanding prevention of double feeding even for dedicated coated paper and a dedicated OHP film in order to obtain a clearer image.
[0010]
However, since the back surface of the dedicated OHP film has a very large coefficient of friction, there are problems in that proper separation cannot be performed with conventional separating members, paper feeding cannot be performed smoothly, and vibration and noise are generated. is doing.
On the other hand, if the friction coefficient on the back side of the special coated paper is lowered, there is a problem that the friction coefficient decreases with ordinary PPC paper and the like, and double feeding occurs. The appearance of members is desired.
[0011]
In addition, these paper types are transferred to paper if the feed roller or paper sheet separating member contains contaminants, and this causes a deterioration in image quality such as image blurring. It is rare.
[0012]
The present inventor has been researching for many years to solve these problems, and as one of the solutions, a paper made of fine foamed polyurethane having a specific hardness and a cell diameter of 0.2 mm or less. Leaf separation pad (Japanese Patent Application No. 2000-263259), having a two-layer structure with different hardness, upper layer material in contact with paper sheet having low hardness and high coefficient of friction, and lower layer material having high hardness Developed a paper sheet separation pad (Japanese Patent Application No. 2000-263161), and further developed a paper sheet separation pad (Patent Application No. 2001-51607) using foam rubber having conductivity. Yes.
[0013]
The inventor re-examined the above-mentioned prior application, added further improvements, and continued research for a separation pad with excellent properties of paper sheet separation function over a long period of time. By adding a specific compounding agent with performance and crosslinking it, the compounding agent is taken into the pad member in a semi-molten state at the interface with the pad member, so that the compounding agent does not fall off from the pad, A paper sheet separation pad that can maintain the characteristics of the paper sheet separating function over a long period of time has been completed, and the present application has been completed.
[0014]
[Means for Solving the Problems]
That is, according to the present invention, in a paper sheet separating member using polyurethane as a base material, granular polyolefin wax is dispersed in the base material at least partially in a molten state at the interface with polyurethane, A paper sheet separating member is provided in which the portion is exposed on the surface of the member.
[0015]
In addition, according to the present invention, there is provided the paper sheet separating member, wherein the polyolefin wax added to the polyurethane has an average particle size of 10 μm to 1 mm.
[0016]
Further, according to the present invention, there is provided the paper sheet separating member, wherein the polyolefin wax is a polyethylene wax and / or a polypropylene wax having a molecular weight of 1500 to 5000.
[0017]
In addition, according to the present invention, there is provided the paper sheet separating member, wherein a blending amount of the polyolefin wax is 1 to 50 parts by weight with respect to 100 parts by weight of polyurethane.
[0018]
In addition, according to the present invention, there is provided the paper sheet separating member, wherein a difference between the crosslinking temperature of the polyurethane and the softening point temperature of the polyolefin wax (crosslinking temperature of the polyurethane−softening point of the polyolefin wax) is within 30 ° C. The
[0019]
DETAILED DESCRIPTION OF THE INVENTION
An important feature of the present invention is that polyurethane is used as the base material of the paper sheet separating member, and a granular polyolefin wax is added to the base material together with a crosslinking agent, a crosslinking accelerator, etc. The polyolefin wax is dispersed in a state of being bonded at least partially in a molten state at the interface with the polyurethane as a base material.
[0020]
Polyurethane is adopted as the base material of the paper sheet separating member, and a low molecular weight polyolefin, that is, a polyolefin wax granule, is added thereto to add dicumyl peroxide, tert-butylcumyl peroxide, 1,3-bis. (Tertiary butyl peroxyisopropyl) Benzene and other known crosslinking agents, and, if necessary, crosslinking with a crosslinking aid, the polyolefin wax dispersed in the polyurethane as a base material by the heat at the time of crosslinking, It will be in a molten state at the interface, and its central part will not melt as it is and will exist in a solid state.
FIG. 1 schematically shows a cross section in this state.
In FIG. 1, 1 is a polyurethane as a substrate, 2 is a polyolefin wax, and the interface 3 between them is taken into the polyurethane in a molten state on the surface of the polyolefin wax.
[0021]
In other words, the granular polyolefin wax that exists as an island of sea-island structure in polyurethane acts as a lubricant, suppresses the phenomenon of “squeal” when transporting paper sheets, and this polyolefin is in a molten state at the interface with polyurethane. Since it is bonded, it does not fall off from the polyurethane, and can continue to provide a function as a lubricant over a long period of time.
[0022]
The proportion of the polyolefin wax blended in the polyurethane is about 1 to 50 parts by weight, preferably about 5 to 40 parts by weight with respect to 100 parts by weight of the polyurethane.
As the polyolefin wax, polyethylene wax and / or polypropylene wax is preferably used.
[0023]
Although the polyolefin wax of the present invention is amorphous, it is granular and added to the polyolefin and subjected to crosslinking. However, after the crosslinking, the polyolefin wax interface is dispersed in the polyurethane in a molten state. For this, it is important that the softening point of the polyolefin wax is lower than the crosslinking temperature of the polyurethane, and the difference is within 30 ° C.
[0024]
According to the inventor's experiment, in order to satisfy the above conditions for dispersing the compounding agent having a function as a lubricant in the paper sheet separating member in such a combined state, polyurethane is adopted as the base material. In the case where a polyolefin wax is adopted as a lubricant and it is necessary to crosslink, and when another rubber member is used as a base material, the polyolefin wax interface is dispersed in the base material in a molten state. Even when other lubricants were used, excellent paper sheet separation characteristics such as a combination of polyurethane and polyolefin wax were not obtained.
[0025]
When a polyethylene wax is used as the polyolefin wax and a polypropylene wax is used, it is necessary to change the crosslinking temperature according to the difference in the softening point.
[0026]
That is, in the case of polyethylene wax, although it depends on the molecular weight thereof, for example, in the case of polyethylene wax having a molecular weight of 2000 and a softening point of 122 ° C, the crosslinking temperature exceeds 122 ° C and is performed at a temperature up to 152 ° C. When the polyolefin wax is a polypropylene wax having a molecular weight of 4000 and a softening point of 152 ° C., the crosslinking temperature exceeds 152 ° C. and is performed at a temperature up to 182 ° C.
[0027]
When such a condition is not satisfied, the polyolefin wax as a lubricant cannot be dispersed in the polyurethane in a molten state only at the interface in the polyurethane as the base material.
Polyethylene wax and polypropylene wax can be mixed and used as the polyolefin wax, but in that case, the molecular weight of both is adjusted to bring the softening point close to each other, and the difference from the crosslinking temperature of the polyurethane is within 30 ° C. You can do that.
[0028]
It is important that the polyolefin wax of the present invention is dispersed in polyurethane in the form of particles, and by cross-linking in this state, a sheet separation member having a sea-island structure in which the polyolefin wax is dispersed in the polyurethane is obtained.
The polyolefin wax dispersed in the base material is formed such that at least a part thereof protrudes from the surface of the member by polishing the surface after crosslinking.
[0029]
The particle size of the polyolefin wax is not particularly limited, but is 10 μm to 1 mm, preferably about 200 μm to 500 μm, in order for the polyolefin wax forming the islands of the sea-island structure to more suitably achieve the properties as a lubricant. .
[0030]
As the polyurethane constituting the base material of the paper sheet separating member, any polyurethane known per se that has been conventionally used as a paper sheet separating member can be used.
The polyurethane of the present invention may be foamed.
The shape of the double feed preventing member can be made into an arbitrary shape such as a plate shape or a cylindrical shape by a method known per se, and further processed or polished to obtain a product.
[0031]
When the polyurethane constituting the base material is composed of a foamed molded product having closed cells, the surface roughness is preferably 20 to 100 μm in average roughness at 10 points. When the surface roughness is less than 20 μm, the mechanical strength is poor, and when it exceeds 100 μm, the stability of the cell is lowered.
[0032]
Further, the paper sheet separating member of the present invention has a hardness of 50 ° or more, preferably 60 to 95 ° in Asker C. When the paper sheet separating member has a hardness of less than 50 °, the frictional force becomes too large, which may cause a paper feeding error.
[0033]
Further, when the paper sheet separating member is in a solit shape, a hardness (JIS A) of 50 ° or more, particularly 60 to 80 °, is an appropriate frictional force for separating the paper sheet.
[0034]
The paper sheet separating member of the present invention is configured such that when a plurality of paper sheets are inserted between the paper sheet separating member and the feed roller, the paper sheet on the paper sheet separating member side is the paper sheet separating member. Abut and receive frictional force. In the present invention, since this paper sheet separating member has a polyolefin wax partially dispersed in the polyurethane in a molten state, sufficient frictional force is applied to the paper sheet, and double feeding is reliably prevented. Is done. Furthermore, this paper sheet separating member can prevent “squeal” that occurs when transporting paper sheets, and even when used over a long period of time, not only is the decrease in the coefficient of friction against paper sheets suppressed, A friction coefficient suitable for conveyance according to the paper type can be maintained, and a suitable paper sheet separation characteristic is exhibited regardless of the paper type.
[0035]
The paper sheet separating member of the present invention can take any shape according to the shape and purpose of the apparatus. For example, as a method for forming irregularities, the inner surface of the mold for forming the paper sheet separating member It is possible to employ a method in which the surface is brought into contact with the surface of the molded product and subjected to molding using the mold. Further, it is also possible to form irregularities by performing blasting such as sandblasting, rubbing the surface with a grindstone, or performing electric discharge machining.
[0036]
The paper sheet separating member of the present invention consists essentially of the above-mentioned polyurethane in which a partially melted polyolefin wax is dispersed, but within the range not impairing the object of the invention, an inorganic filler, carbon Various compounding agents such as black can be added.
For example, as the inorganic filler, talc or calcium carbonate is preferably used, which improves heat resistance, heat expansion resistance, chemical resistance, wear resistance, and has physical properties such as when silica is contained. There is no significant decline.
Further, the blending amount of the inorganic filler is not particularly limited. However, when talc is blended, 10 to 30 parts by weight with respect to 100 parts by weight of rubber, and when blending calcium carbonate, 80%. Or about 100 weight part is preferable in the point which exhibits the said effect more.
[0037]
【The invention's effect】
According to the present invention, a polyurethane is adopted as a base material, and a granular polyolefin wax is dispersed therein, and this is crosslinked, so that the polyolefin wax is at least partially melted at the interface and dispersed in the polyurethane. Therefore, it is possible to provide a paper sheet separating member that does not drop off the foaming agent, prevents the occurrence of squealing over a long period of time, and has excellent paper feeding characteristics.
[0038]
【Example】
Hereinafter, the present invention will be described by way of examples.
The physical properties of the paper sheet separating members obtained in the examples and comparative examples were evaluated by the following methods.
* Friction coefficient: A Teflon free roll loaded with a load of 200 gf was placed on the sample pad of the sample, and during that time, Xerox-P paper was used as the paper sheet, and the end of the paper sheet was connected to the load cell. The coefficient of friction when paper was fed at a speed of sec was measured.
* Rebound resilience: Measured according to JIS K 6255.
* Evaluation of squeal: The obtained paper sheet separating member was pressed against an EPDM feed roller with a load of 2.9 N, and three types of paper sheets (“plain paper”) were placed between the paper sheet separating member and the feed roller. ”,“ Recycled paper ”,“ Thick paper ”), and the occurrence of“ squeal ”after the passage of 20,000 sheets of paper was confirmed.
○: No noise was generated during feeding of 50,000 sheets.
Δ: A slight squeak occurred after feeding about 40,000 sheets.
X: A squeal occurred after feeding about 20,000 sheets.
[0039]
< Examples 1-3, Comparative Examples 1-4 >
Polyolefin wax was blended at a ratio shown in Table 1 with respect to 100 parts by weight of polyurethane (polycaprolactone ester urethane).
The blend was sufficiently kneaded with a 10-inch open roll, and 10 parts by weight of dicumyl peroxide was added and further kneaded.
Then, it crosslinks for 25 minutes at the temperature described in Table 1, and obtained the plate-shaped molded object.
The polyethylene wax used had a molecular weight of 2000 and a softening point of 122 ° C., a polypropylene wax molecular weight of 4000 and a softening point of 152 ° C.
The results are shown in Table 1.
[0040]
[Table 1]

[Brief description of the drawings]
FIG. 1 is a schematic view of a dispersion state of a polyolefin wax in a paper sheet separating member of the present invention.
[Explanation of symbols]
1 Polyurethane 2 Interfacial melting part of polyolefin wax 3 Polyolefin wax

Claims (5)

In a paper sheet separating member using polyurethane as a base material, granular polyolefin wax is dispersed in the base material at least partially in a molten state at the interface with polyurethane, and at least a part of the wax is exposed on the surface of the member. A paper sheet separating member characterized by existing in a state of The paper sheet separating member according to claim 1, wherein the polyolefin wax added to the polyurethane has an average particle size of 10 µm to 1 mm. The paper sheet separating member according to claim 1 or 2, wherein the polyolefin wax is polyethylene wax and / or polypropylene wax having a molecular weight of 1500 to 5000. The paper sheet separating member according to any one of claims 1 to 3, wherein a blending amount of the polyolefin wax is 1 to 50 parts by weight with respect to 100 parts by weight of polyurethane. The paper sheet according to any one of claims 1 to 4, wherein a difference between a crosslinking temperature of the polyurethane and a softening point temperature of the polyolefin wax (crosslinking temperature of the polyurethane-softening point of the polyolefin wax) is within 30 ° C. Separation member.

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