JP5037993B2 - Manufacturing method of toner supply roll - Google Patents

Description

The present invention relates to a method for producing a toner supply roll, in particular, a copying apparatus, an image recording apparatus, a printer, an image forming apparatus such as a facsimile, consisting electrophotographic photosensitive member or an electrostatic recording dielectric member or the like image carrier A developing device used for developing and visualizing the electrostatic latent image formed thereon is supplied with a predetermined toner (developer), and a photosensitive member on which the electrostatic latent image is formed is supplied. The present invention relates to a method capable of advantageously producing a toner supply roll used for forming a target toner image on the surface of such an image carrier.

  Conventionally, in an image forming apparatus such as a copying apparatus, an image recording apparatus, a printer, or a facsimile, an electrostatic latent image formed on an image carrier made of an electrophotographic photosensitive member or an electrostatic recording dielectric is developed by a developing device. The toner is developed with toner (developer) supplied from the developing roll and visualized as a toner image. Here, in such a developing device, a toner supply roll composed of a soft elastic roll for supplying a predetermined toner contained in the hopper to the developing roll and further to the image carrier side is incorporated. As such a toner supply roll, an elastic roll made of a flexible polyurethane foam (sponge) has been widely used from the viewpoint of durability, non-contamination and flexibility.

  By the way, as a function of the toner supply roll, the toner is supplied to the developing roll (toner supplying ability), and unnecessary parts are scraped off (toner scraping ability), and the toner is uniformly supplied onto the developing roll. However, in recent years, as demands for downsizing and high image quality of copying machines and the like have increased, toner supply rolls that can exhibit better toner supply performance and toner scraping performance can be obtained. Development is desired.

  Under such circumstances, various types of toner supply rolls that can exhibit excellent toner supply properties and toner scraping properties have been proposed. For example, in Patent Document 1 (Japanese Patent Laid-Open No. 2006-64773), a cylindrical elastic body made of a foam of various polymer substances, and a shaft member extending in the central axis direction of the cylindrical elastic body, A toner supply roll that is rotatably slidably contacted with an object to be slidably contacted such as a roller or a belt. A toner supply roller characterized by forming a space allowing the agitation of the toner and a manufacturing method thereof have been proposed.

  However, the toner supply roller proposed in Patent Document 1 can be manufactured through a very complicated process. That is, as disclosed in Patent Document 1, in order to make a linear body exist on the outer peripheral surface of a cylindrical elastic body, a linear body having an end portion fixed to one protruding shaft portion of a shaft member. After extending in the axial direction on the outer peripheral surface of the cylindrical elastic body, it is wound around the other protruding shaft portion of the shaft member, and then the linear body is displaced by a required angle in the circumferential direction of the cylindrical elastic body. After that, it was necessary to repeat the procedure of folding back to the outer peripheral surface and extending in the axial direction, and wrapping around one of the projecting shafts, which inevitably had a problem that its manufacturing cost was high. .

  In addition, in order to provide a concavo-convex shape on the surface of the flexible polyurethane foam layer, a method of using a molding die provided with a concavo-convex shape on the inner surface of the molding cavity has been proposed when the flexible polyurethane foam layer is produced by foam molding. However, the molding die used therein is generally expensive due to the complexity and density of the inner surface (cavity surface) shape, and the maintenance cost is also high. Similar to the toner supply roller proposed in US Pat.

  On the other hand, it is conceivable to increase the hardness of the flexible polyurethane foam layer for the purpose of improving the toner scraping property of the toner supply roll. Patent Document 2 discloses a roll having such a high hardness. In Japanese Patent No. 3072799, in a surface modification roll for an image forming apparatus in which a conductive urethane elastic body layer is formed on a core metal surface, the surface of the conductive urethane elastic body layer is an isocyanate-containing compound. There has been proposed a surface-modified roll characterized in that it is an isocyanate-treated surface layer that has been modified by immersing and heating the elastic layer in a solution containing.

  However, the inventors of the present invention examined the surface modified roll disclosed in Patent Document 2 in detail, and as a result, the surface modified roll obtained by the disclosed technique, specifically, a conductive urethane elastic body. In the surface modification roll obtained by immersing the layer in a surface treatment liquid (solution containing an isocyanate-containing compound) for a predetermined time, the surface hardness becomes too high, and this is used as a toner supply roll. It has been found that the use of the toner increases the stress applied to the toner (toner stress) and may cause problems such as toner deterioration.

JP 2006-64773 A Japanese Patent No. 3072799

The present invention has been made in view of such circumstances, and a problem to be solved is a toner supply roll that has a low stress on the toner and is excellent in toner scraping properties. It is an object of the present invention to provide a method that can be easily and advantageously produced without requiring complicated steps.

Then, in order to solve such problems, the present invention is a urethane sponge having a longitudinal rod-like metal core to be b Lumpur shaft, and a flexible polyurethane foam layer which is integrally formed around the core metal A step of preparing a roll, a step of preparing a coating film having a thickness of 40 to 200 μm comprising an isocyanate solution in a state where the solvent is not dried, and the urethane sponge roll while rotating the urethane sponge roll by for moving a modified adhering a isocyanate solution to the surface of the soft quality polyurethane foam layer in the urethane sponge roll, the surface of the soft quality polyurethane foam layer by the isocyanate solution adhered to the surface, the following equation (1 nitrogen atom abundance ratio calculated from): α (%) characterized in that the step of the 5 <alpha <surface portion 50, including The method for producing a toner supply roll which is for its gist.

Thus, in the toner supply roll thus obtained in the present invention, the flexible polyurethane foam layer, which has been formed by a reforming process using an isocyanate solution, is calculated from a predetermined equation Nitrogen atom abundance ratio: Since α (%) has a surface layer portion satisfying 5 <α <50, while maintaining the inherent characteristics (such as low toner stress) of the flexible polyurethane foam layer, The toner scraping performance is excellent.

  In addition, since the toner supply roll has a smooth toner entrance and exit on the surface (surface of the flexible polyurethane foam layer), the toner supply roll is excellent in toner supply capability to the development roll and has a toner filming property in the development roll. Generation of the toner can be effectively suppressed, and furthermore, the charging property of the toner can be advantageously improved.

  On the other hand, according to the method for producing a toner supply roll according to the present invention, it is possible to easily and advantageously produce a toner supply roll that exhibits excellent characteristics as described above, without requiring complicated steps. .

Incidentally, the toner supply roll thus obtained in the present invention, as described above, has a longitudinal rod-like metal core as a roll axis, and a soft polyurethane foam layer which is integrally formed around such core metal, In addition, the surface layer part in which the flexible polyurethane foam layer is formed by the modification treatment with the isocyanate solution on the surface thereof, and the nitrogen atom abundance ratio calculated from the following formula (1): α (%) is 5 <α <50 It is what has. By having such a predetermined surface layer portion, the toner supply roll obtained according to the present invention has a small stress applied to the toner and has an excellent toner scraping property.

  Here, the nitrogen atom abundance ratio: α (%) calculated from the above formula (1) is an index indicating the degree of the modification treatment with the isocyanate solution, and the larger the value, the more flexible polyurethane foam. This means that the isocyanate solution is immersed from the surface of the layer to a deep site, and the modification with isocyanate is progressing (high hardness is achieved by the reaction between isocyanate and polyurethane). In the present invention, if the nitrogen atom abundance ratio: α (%) is 5% or less, the toner scraping property is not sufficient, whereas if it is 50% or more, the toner supply property may be adversely affected. Nitrogen atom abundance: α (%) is 5 <α <50, preferably 7 <α <30.

  Note that the three measured values (A, B and C in the above formula (1)) used for calculating the nitrogen atom abundance ratio: α (%) are all X-ray photoelectron spectroscopy (ESCA). (Atom%) of nitrogen atoms measured by A, the surface of the flexible polyurethane foam layer modified with an isocyanate solution in A, and the flexible polyurethane modified with an isocyanate solution in B It is a numerical value obtained by measuring a portion having a depth of 1.5 mm from the surface in the foam layer, and, for C, the isocyanate used for modification.

Such preparative toner supply roll is one that may be advantageously prepared according to the method described in detail below. In this case, first, a urethane sponge roll in which a flexible polyurethane foam layer is integrally formed around a cored bar is produced. Is advantageously produced by foam-molding a polyurethane raw material which gives

  Here, as the polyurethane raw material, any of the conventionally known reactive raw materials (a blend of a polyol component and a polyisocyanate component) that is in the same liquid form as before and foams and cures in a mold is used. However, it is appropriately selected and used without any particular limitation.

  For example, as the polyol component constituting such a liquid polyurethane raw material, any of known polyols such as polyether polyol, polyester polyol, and polymer polyol, which are generally used in the production of flexible polyurethane foam, is used. obtain. In addition, as the polyisocyanate component, all known polyisocyanates having at least two or more functional groups can be used. For example, 2,4- and 2,6-tolylene diisocyanate (TDI), orthotoluidine diisocyanate (TODI), naphthy Range isocyanate (NDI), xylylene diisocyanate (XDI), 4,4'-diphenylmethane diisocyanate (MDI), carbodiimide-modified MDI, polymethylene polyphenyl isocyanate, polymeric polyisocyanate, etc. are used alone or in combination. obtain.

  In addition, in the polyurethane raw material in which these polyol component and polyisocyanate component are blended, a crosslinking agent, a foaming agent (water, a low-boiling substance, a gas body, etc.), a surfactant, a catalyst, etc. However, it is appropriately added so as to form a reactive foaming raw material so as to obtain a known composition that easily causes the structure of the flexible polyurethane foam layer in the target toner supply roll. In addition, flame retardants, fillers, conductivity imparting agents for imparting desired conductivity to toner supply rolls, antistatic agents, and the like are added to such raw materials as necessary. It is done.

  Such a liquid polyurethane raw material is foam-molded in a predetermined mold, and as the mold used in the foam molding, a mold having a mold structure exhibiting a pipe shape, so-called A pipe type is advantageously used. The pipe type is specifically a pipe having a length substantially equal to the axial length of the flexible polyurethane foam layer of the toner supply roll, and two pipes attached to both ends of the pipe to close the respective ends. It is composed of two caps, and in the state where a long bar-shaped metal core is set in the pipe, both ends of the pipe are closed with two caps, and the metal core is supported by these two caps. Thus, a molding cavity that gives the final roll shape (outer diameter) of the target toner supply roll is formed in the pipe.

  When such a pipe mold is used, the above-mentioned liquid polyurethane raw material is injected into the molding cavity in a state where the core metal is supported by the caps at both ends, and foam molding is performed in the same manner as before. Will be. In that case, the expansion ratio is generally about 5 to 20 times.

  In addition, after foaming molding of such a flexible polyurethane foam layer, known crushing may be appropriately performed. For example, a method of blowing compressed air or the like having a predetermined pressure is advantageously employed. In the case of forming a closed-cell type flexible polyurethane foam layer, mechanical foaming is desirable as a foaming method, and it is desirable to reduce the air pressure during such crushing.

  While the urethane sponge roll is prepared as described above, an isocyanate solution for treating the surface of the flexible polyurethane foam layer is prepared.

  Here, the isocyanate as a solute of the isocyanate solution is not particularly limited as long as it is an isocyanate that can react with the flexible polyurethane foam layer. For example, the above-described polyisocyanate that can be blended with the polyurethane raw material. Etc. can be mentioned.

  As the solvent for the isocyanate solution, any solvent can be used as long as it can dissolve the isocyanate. From the conventionally known various solvents, those according to the isocyanate to be used are appropriately selected and used. The Specifically, linear saturated hydrocarbon solvents such as n-hexane; organic solvents such as toluene and methyl ether ketone can be exemplified. Among these solvents, linear saturated hydrocarbon solvents and the like Those having low swellability to the flexible polyurethane foam layer can be used particularly advantageously.

  Furthermore, if the isocyanate concentration in the isocyanate solution is too low, there is a possibility that the toner scraping property of the finally obtained toner supply roll may be insufficient. On the other hand, if the isocyanate concentration is too high, the surface of the flexible polyurethane foam layer may be insufficient. The isocyanate solution is prepared so as to have a concentration of about 5 to 50% by weight since the modification proceeds more than necessary and as a result, the toner supply property of the toner supply roll may be deteriorated.

  Next, when the surface of the flexible polyurethane foam layer in the urethane sponge roll is modified using the isocyanate solution thus prepared, a coating film of the isocyanate solution in a state where the solvent is not dried is prepared. Specifically, it is prepared by applying an isocyanate solution on a smooth table or plate. If the undried coating film obtained by such coating is too thin, the surface of the flexible polyurethane foam layer may not be sufficiently modified. On the other hand, if the coating film is too thick, the foam layer surface may be modified more than necessary. In general, the isocyanate solution is applied so as to have a thickness of about 40 to 200 μm.

  Furthermore, after the application, on the coating film of the isocyanate solution before the solvent is dried, the urethane sponge roll prepared above is moved while being rotated (rolled), thereby forming the flexible polyurethane foam layer of the urethane sponge roll. The isocyanate solution is allowed to adhere to the surface. At this time, if the moving speed of the urethane sponge roll is too slow, the isocyanate solution adheres to the surface of the foam layer more than necessary, the foam layer surface is modified, and the toner scraping performance of the finally obtained toner supply roll is improved. On the other hand, if the moving speed is too fast, the foam layer surface may not be sufficiently modified, so the peripheral speed of the urethane sponge roll is usually about 50 to 600 mm / sec. The urethane sponge roll can be rotated and moved at a high moving speed. In addition, when the urethane sponge roll is moved at such a moving speed, the isocyanate solution usually reaches only a portion having a depth of about 100 μm from the surface of the flexible polyurethane foam layer.

  And after making the isocyanate solution adhere to the surface of the flexible polyurethane foam layer, the urethane sponge roll is dried, the polyurethane constituting the flexible polyurethane foam layer is reacted with isocyanate, and the foam layer surface is modified, Thus, a toner supply roll having a desired predetermined surface layer portion can be obtained. In addition, when drying a urethane sponge roll, it is also possible to heat-process as needed.

  In the toner supply roll thus obtained, the flexible polyurethane foam layer is formed by a modification treatment using an isocyanate solution, and the nitrogen atom abundance ratio: α (%) is within a predetermined range. Since it has a certain surface layer portion, it is excellent in the toner supply property originally required for the toner supply roll, the stress applied to the toner is small, and the toner scraping property is also excellent. .

  Some examples of the present invention will be shown below to clarify the present invention more specifically. However, the present invention is not limited by the description of such examples. Needless to say. In addition to the following examples, the present invention includes various changes and modifications based on the knowledge of those skilled in the art without departing from the spirit of the present invention, in addition to the specific description described above. It should be understood that improvements and the like can be added.

  First, 90 parts by weight of polyether polyol (Mitsui Chemicals, trade name: EP-828, OH value: 28) and polymer polyol (Mitsui Chemicals, trade name: POP-31-28, OH value) : 28) 10 parts by weight, 2 parts by weight of diethanolamine, 3 parts by weight of silicone foam stabilizer (trade name: L-5309, manufactured by Nippon Unicar Co., Ltd.), 2 parts by weight of water, and tertiary 0.5 parts by weight of amine catalyst (trade name: Kaulizer No.31 manufactured by Kao Corporation) and 0.1 parts by weight of tertiary amine catalyst (trade name: Toyocat HX-35, manufactured by Tosoh Corporation) And 0.1 part by weight of dibutyltin dilaurate and 30.5 parts by weight of isocyanate (manufactured by Sumitomo Bayer Urethane Co., Ltd., trade name: Sumidur VT-80, NCO (%): 45 (%)) Polyurea for forming a flexible polyurethane foam layer Tan raw material was prepared.

  A SUM22 round bar with a diameter of 5 mm is placed in a separately prepared pipe mold, both ends of the pipe mold are closed with caps and the round bar is supported, and in this state, the polyurethane raw material prepared in the molding cavity Urethane in which a predetermined amount is injected, foamed and cured under conditions of 60 ° C. × 30 minutes, and a flexible polyurethane foam layer (thickness: 5.5 mm) is integrally formed around a core metal (diameter: 5 mm) A sponge roll (outer diameter: 16 mm) was produced. A plurality of urethane sponge rolls (sponge rolls A and B) each having a different hardness of the flexible polyurethane foam layer were produced by changing the amount of polyurethane raw material injected into the molding cavity.

  On the other hand, the isocyanate solutions shown in Tables 1 and 2 below were used as isocyanate solutions, and the concentrations shown therein were prepared. In this preparation, methyl ether ketone was used as a solvent for pure MDI, and n-hexane was used for other isocyanates. And the predetermined | prescribed surface layer part was formed in the flexible polyurethane foam layer in a urethane sponge roll using either of the prepared isocyanate solutions.

  Specifically, after applying an isocyanate solution on a smooth table (thickness: about 150 μm) to form an undried coating film, the sponge roll A is immediately put on the coating film at a peripheral speed: about By moving while rotating at 300 mm / sec, the isocyanate solution was adhered to the surface of the flexible polyurethane foam layer. Thereafter, the urethane sponge roll is allowed to stand overnight in an environment of 23 ° C. × 50% RH to react the polyurethane with isocyanate and remove the solvent, thereby removing the target toner supply roll (Invention Examples 1 to 1). 6, Comparative Examples 1-2) were obtained. The toner supply roll of Comparative Example 3 was prepared according to the same method except that TDI (liquid) was used, and the toner supply roll of Comparative Example 4 was modified by an isocyanate solution. Sponge roll A that has not been modified, and the toner supply roll of Comparative Example 5 is sponge roll B that has not been modified with an isocyanate solution.

  Each toner supply roll thus obtained was subjected to the following measurements and evaluations.

-Nitrogen atom abundance: α (%) calculation-
About the surface of the flexible polyurethane foam layer modified with the isocyanate solution, the depth of the surface of the flexible polyurethane foam layer modified with the isocyanate solution: 1.5 mm, and the isocyanate used as the solute of the isocyanate solution, X According to the line photoelectron spectroscopy, the existing ratio of nitrogen atoms (the existing ratio of nitrogen atoms A to C [atom%]) was measured. Specifically, using an ESAC system (trade name: PHI5600 system, manufactured by ULVAC-PHI Co., Ltd.), an X-ray is irradiated onto an object using an Al monochromator (14 kV, 150 W), and an electron neutralizing gun is used. Measurement was performed under the conditions of measurement area: φ800 μm, photoelectron take-off angle: 45 deg, resolution: 18.75 passage, 0.8 eV / step, 20 time / step while performing charging correction. The nitrogen atom abundance (%) of each toner supply roll was calculated by introducing the nitrogen atom abundance (A to C) thus obtained into the following formula (1). The measured nitrogen atom abundances A to C and the calculated nitrogen atom abundance are shown in Table 1 and Table 2 below.

−Evaluation of density of initial copy image−
In order to evaluate the toner supply performance of each toner supply roll, the toner supply roll was incorporated into a developing device of a commercially available printer, and images were taken out. The obtained initial copy image was visually observed. “○” indicates that the image is satisfactory without density unevenness, and “△” indicates that the image has a slight density unevenness but is slight. Those with image unevenness were evaluated as “×”. The evaluation results are shown in Table 1 and Table 2 below.

-Ghost evaluation of copied images after initial and endurance-
The toner scraping property of each toner supply roll was evaluated as follows. The toner supply roll was incorporated in a developing device of a commercially available printer, a predetermined image was output, and the obtained initial copy image was visually observed. The case where there was no ghost and the image was good was evaluated as “◯”, the case where there was a slight ghost but a slight one as “Δ”, and the case where there was a ghost of a level that was difficult to put into practical use was evaluated as “x”. The evaluation results are also shown in Table 1 and Table 2 below as ghost evaluation of the initial copy image.

  On the other hand, each toner supply roll was incorporated in a developing device of a commercially available printer, and 10,000 character strings having a toner concentration of 5% were output. Thereafter, a predetermined image was further displayed, and the obtained copy image (durable copy image) was visually observed. The case where there was no ghost and the image was good was evaluated as “◯”, the case where there was a slight ghost but a slight one as “Δ”, and the case where there was a ghost of a level that was difficult to put into practical use was evaluated as “x”. The evaluation results are also shown in Tables 1 and 2 below as ghost evaluation of durable copy images.

-Toner filming evaluation of durable copy images-
The degree of stress applied to the toner in each toner supply roll was evaluated as follows. That is, each toner supply roll was incorporated into a developing device of a commercially available printer, and 10,000 character strings having a toner density of 5% were output. Thereafter, a predetermined image was further displayed, and the obtained copy image (durable copy image) was visually observed. There are no image defects such as color loss due to toner filming, and “○” indicates that the image is good, and “△” indicates that there is a slight image defect, but there is an image defect that is difficult to put into practical use. The existing ones were evaluated as “x”. The evaluation results are shown in Table 1 and Table 2 below.

-Measurement of roll hardness-
As shown in FIG. 1, the toner supply roll is supported at both end portions of the core metal, and the flexible polyurethane foam layer is 10 mm by a jig having a plate-like pressing surface having a width of 50 mm (thickness: 7 mm). A load (g) of 1 mm displacement (compression) when pressed at a speed of / min was measured. As shown in FIG. 1, the number of measurement points was 2 in the axial direction and 4 in every 90 ° in the circumferential direction, for a total of 8 points, and the average value was the roll hardness (unit: gf). In addition, it has shown that the hardness of a flexible polyurethane foam layer is so high that this number is large, ie, it is hard. The measurement results are shown in Tables 1 and 2 below.

Such Table 1 and as is clear from the results in Table 2, in the toner supply roll thus obtained in the present invention (Invention Examples 1 to 6), together with an excellent toner supply properties, the toner scraping properties In addition, it was recognized that the stress applied to the toner is small.

  On the other hand, in the toner supply roll that has not been modified with an isocyanate solution (Comparative Example 4) or the one that has been modified with a low-concentration isocyanate solution (Comparative Example 2), the toner It is inferior in scraping property, and is also modified with isocyanate alone (Comparative Example 3) or modified with a high-concentration isocyanate solution (Comparative Example 1). Were confirmed to be inferior in toner supply performance. Further, it was confirmed that the toner supply roll (Comparative Example 5) having a high hardness of the flexible polyurethane foam layer can give a great stress to the toner because the ghost evaluation of the copied image after durability is low. It is.

In an Example, it is explanatory drawing which shows the measuring method of the hardness of the flexible polyurethane foam layer in a toner supply roll, Comprising: (a) is a plane explanatory drawing, (b) is a left side explanatory drawing.

Claims (1)

A step of preparing a urethane sponge roll having a longitudinal bar-shaped cored bar serving as a roll shaft and a flexible polyurethane foam layer integrally formed around the cored bar;
A step of preparing a coating film having a thickness of 40 to 200 μm, comprising an isocyanate solution in a state where the solvent is not dried;
A step of attaching an isocyanate solution to the surface of the flexible polyurethane foam layer in the urethane sponge roll by moving the urethane sponge roll while rotating the coating film;
The isocyanate solution adhered to the surface by modifying the surface of soft quality polyurethane foam layer, the nitrogen atom present rate calculated from the following equation (1): α (%) is the step of the 5 <alpha <surface portion 50 And
A method for producing a toner supply roll, comprising:

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