JP2006039115A - Electrophotographic transfer paper - Google Patents

Abstract

An electrophotographic transfer paper capable of obtaining an image free from transfer defects even in a low humidity environment.
An electrophotographic transfer paper, wherein an index K expressed by K = thickness ² / air permeability (μm ² / sec) is 200 or less. The Steecht sizing degree is 10 sec or more. The freeness of the pulp is 100 ml or more and 350 ml or less. A calendar process is performed.
[Selection] Figure 1

Description

  The present invention relates to an electrophotographic transfer paper, and more particularly to an electrophotographic transfer paper that is free from transfer defects even in a low humidity environment when used in an electrophotographic image forming apparatus having a transfer roller.

  Conventionally, as a transfer device in an image forming apparatus adopting an electrophotographic system, a configuration using a transfer roller that is excellent in cost and durability has been adopted.

  FIG. 2 shows an example of an electrophotographic image forming apparatus using a contact charging type transfer device.

  The transfer device 6 includes a conductive roller 6a such as a metal roller serving as a metal core, and a cylindrical conductive layer 6b formed on the outer peripheral surface thereof. The transfer device 6 is rotatably supported at both ends of the conductive roller 6a by a bearing member (not shown), and is arranged in parallel with the photosensitive drum 1, and in the direction of the photosensitive drum 1 by a pressing means such as a spring (not shown). Is pressed with a predetermined pressing force. As a result, the transfer device 6 forms a transfer nip portion N in which the outer conductive layer 6b is pressed against the photosensitive drum 1 and sandwiches and conveys the transfer paper P between the transfer drum P and the transfer paper P. When the paper is fed to the nip portion N, the conductive layer 6b comes into contact with the back surface of the recording material P, and is driven to rotate in the direction of arrow R6 as the transfer paper P is conveyed in the direction of arrow K1.

  Further, a power supply 11 is connected to the conductive roller 6a of the transfer device 6. The transfer device 6 is applied with a predetermined bias voltage by the power supply 11, and charges the reverse surface of the transfer paper P with a polarity opposite to that of the toner. By direct application, the toner image on the photosensitive drum 1 is transferred to the surface of the transfer paper P. Note that the above-described transfer device 6 may be configured such that a gear is attached to the conductive roller 6a and forcibly driven by driving means such as a motor.

JP 09-034158 A JP 2000-112167 A JP 2001-281904 A

  However, the conventional transfer device has the following problems.

  In the above-described transfer device, when a recording material having a relatively high resistance is transferred under a low humidity environment such as 23 ° C. and 5% RH, the image quality is deteriorated due to a transfer defect called “penetration” described below. A malfunction occurred.

  “Punch-through” is a phenomenon in which an image such as a halftone or solid black image is whitened in a circular shape having a diameter of about 0.2 to 1.0 mm. It is considered that the toner on the image carrier is not normally transferred to the paper and remains on the image carrier due to a discharge phenomenon on the surface of the paper sandwiched between and the internal gap.

  In order to solve such a transfer failure due to a discharge phenomenon in a low-humidity environment, the method of defining the surface smoothness of the paper is shown in Torii Literature 1, but in this method, in particular, the inside of the paper This does not alleviate the discharge phenomenon in the voids, so that a sufficient effect cannot be obtained.

  Patent Documents 2, 3 and the like disclose electrophotographic transfer papers that define the air permeability, but these are configurations for solving toner blisters and paper blisters, and under the low humidity environment of the present invention. This is different from solving the transfer failure in

  An object of the present invention is to provide an electrophotographic transfer paper capable of obtaining an image having no transfer failure even in a low humidity environment.

  As a result of intensive studies, the inventors have concluded that according to the electrophotographic transfer paper, the index K represented by the following formula is 200 or less, the above problems can be solved. It came.

K = thickness ² / air permeability (μm ² / sec)
Further, preferably, the Stekkite sizing degree is 10 sec or more. In addition, the freeness of the pulp is 100 ml or more and 350 ml or less. Furthermore, it is preferable to perform a calendar process.

  The electrophotographic transfer paper of the present invention can obtain an image having no transfer defect even in a low humidity environment, particularly when used in an electrophotographic image forming apparatus having a transfer roller.

  The inventors of the present invention have found that abnormal image generation in a low humidity environment called “push-through” is caused mainly by a transfer electric field in the vicinity of the transfer nip between the image carrier and the transfer roller, and a discharge phenomenon occurs mainly in the gap inside the paper. In order to find out and suppress the occurrence of an abnormal image, the inventors have come to the idea that it is effective to make the gaps in the paper as small and small as possible.

Regarding the voids inside the paper, the air permeability of the paper is considered to represent this most. The air permeability is the time required for a predetermined amount of air to pass through a predetermined area of paper, so the time for air to pass per unit volume is
Indicated by air permeability / thickness. Since the porosity of paper is thought to correlate with the time for air to pass per unit volume, the porosity is
It is thought to correlate with thickness / air permeability. Therefore, the number of voids that are the source of discharge is
It is considered to correlate with porosity x thickness = thickness ² / air permeability. That is, as the value of “thickness ² / air permeability” is smaller, the paper is thinner and denser, and there are few voids that are the sources of discharge, so it is considered that the “pierce” phenomenon is less likely to occur. Hereinafter, the value correlated with the number of voids is represented as K.

K = thickness ² / air permeability (μm ² / sec)
As a method of setting the above K value to a desired value, an internal sizing agent such as rosin, sulfate band, starch, casein, silicic acid or the like is mixed with raw pulp in advance to make paper, or in a process called size press treatment, It is effective to bury a surface sizing agent such as talc, titanium white or calcium carbonate in the gaps in the transfer paper.

  Also, by beating the fibers to make them stand up or to make fine fibers (single fibers), the degree of entanglement between the fibers in papermaking can be improved, and the voids in the paper can be reduced. The desired value of K can be obtained.

  Furthermore, the target K value can be obtained by crushing the gaps in the transfer paper by performing a calendar process.

  The method for adjusting the K value of the transfer paper of the present invention is not limited to the above method.

  Hereinafter, the present invention will be described in more detail with reference to preferred embodiments of the present invention.

  As a raw material of the transfer paper, L. B. K. P (hardwood kraft pulp) and N.I. B. K. A pulp such as P (conifer kraft pulp) is used, and a sizing agent such as rosin, sulfate band, starch, casein, silicic acid, etc. is added to this and beaten. At this time, it is desirable to adjust the degree of beating to a predetermined freeness to obtain the value of K shown on the left.

  Further, a paper machine such as a long paper machine is added with a filler such as titanium oxide, kaolin, zinc sulfide and talc.

  FIG. 1 is an explanatory diagram of a manufacturing process when manufacturing transfer paper.

  In the manufacturing process of FIG. 1, a pulp suspension obtained by adding a filler such as a filler, a sizing agent, a paper strength enhancer, a dye, and a paper stock such as a resistance adjuster to the pre-treated pulp, It is jetted onto the wire 32 moving in the direction of arrow R from the stock inlet 31, and dehydrated at the wire part to obtain a pulp sheet. The obtained pulp sheet is further dehydrated in the press part and then dried in the first dry part to form a base paper. The dried base paper is coated with a coating liquid for surface fine coating by a roll coater 33 in a size press part, then dried in a second dry part, and pressed and pressed by a plurality of rolls 34 in a calendar part. After being compressed and adjusting the smoothness, the obtained transfer paper is wound up by a reel part.

  As a low resistance treatment agent for reducing the surface resistivity of the transfer paper, a cationic low resistance treatment agent, an anionic low resistance treatment agent, or the like can be used.

Moreover, the coating liquid finely coated by the size press part is a product in which an inorganic pigment, a low-resistance treatment agent, or the like is dispersed, and this is preferably 1 to 10 g / m ^{2 in} terms of dry solid content per side. So that the surface is finely coated. As described above, fine coating in this size press part is not only for filling the gaps in the transfer paper to obtain the desired characteristics, but also for obtaining the water resistance and smoothness of the transfer paper, and for surface resistance. It is done for the purpose of adjusting. As the inorganic pigment used for surface fine coating, for example, inorganic pigments generally used in coated paper such as calcium carbonate, kaolin and clay can be used, and these can be used alone or in combination. . Examples of the water-soluble binder used together with these inorganic pigments include starch, polyvinyl alcohol, and latex emulsion, and these can be used alone or in combination. Moreover, the above-mentioned thing can be used for the low resistance processing agent used for surface fine coating.

  Various physical property values in the present invention are measured by the following measuring methods.

  The thickness of the transfer paper was measured according to JIS-P-8118.

  The air permeability of the transfer paper was measured according to JIS-P-8117.

  The degree of sizing of the transfer paper was measured according to IS-P-8122.

  The freeness of the transfer paper pulp was measured according to JIS-P-8121.

  Hereinafter, the present invention will be described more specifically according to Examples and Comparative Examples. In addition, this invention is not limited to an Example.

Based on the manufacturing process shown in FIG. B. K. P (hardwood pulp), 5% by weight kaolin, 0.5% by weight sulfuric acid band, 0.3% by weight rosin size and 3.2% by weight based on the dry weight of the base paper (pulp sheet) before coating Paper is made using a pulp suspension (freeness of 235 ml) mixed with a water-soluble binder and dried for the first dry part, and then a surface coating liquid is applied by a roll coater. Coat on each side of 2.0 g / m ² with respect to one side of the base paper, dry the coating solution with the second dry part, smoothen it with the calendar part using 6 rolls, and transfer paper Manufactured. At this time, the density of the pulp suspension as the paper stock was adjusted according to the paper making speed, and the basis weight was set to 90 g / m ² .

  Table 1 shows the physical properties and papermaking conditions of the obtained transfer paper. Furthermore, as a result of forming an image on the transfer paper produced above using an electrophotographic image forming apparatus and evaluating the transfer image in an environment of 23 ° C. and 5% Rh, an image having no “pierce” Could get.

Based on the manufacturing process shown in FIG. B. K. P (hardwood pulp), 5% by weight kaolin, 0.5% by weight sulfuric acid band, 0.3% by weight rosin size and 3.2% by weight based on the dry weight of the base paper (pulp sheet) before coating Paper is made using a pulp suspension (freeness of 235 ml) mixed with a water-soluble binder and dried for the first dry part, and then a surface coating liquid is applied by a roll coater. Coat on each side of 2.0 g / m ² with respect to one side of the base paper, dry the coating solution with the second dry part, smoothen it with the calendar part using 6 rolls, and transfer paper Manufactured. At this time, the density of the pulp suspension as the paper stock was adjusted according to the paper making speed, and the basis weight was adjusted to 200 g / m ² .

  Table 1 shows the physical properties and papermaking conditions of the obtained transfer paper. Furthermore, as a result of forming an image on the transfer paper produced above using an electrophotographic image forming apparatus and evaluating the transferred image in an environment of 23 ° C. and 5% Rh, the result was a slight “through”. I was able to get a good image.

  In Example 1, a transfer paper was produced in the same manner as in Example 1 except that the smoothing process was not performed on the calendar part. Table 1 shows the physical properties and papermaking conditions of the obtained transfer paper. Furthermore, when the obtained transfer paper was used for image evaluation in the same manner as in Example 1, a slight image with a degree of “piercing” could be obtained.

Based on the manufacturing process shown in FIG. B. K. P (hardwood pulp), 5% by weight kaolin, 0.5% by weight sulfuric acid band, 0.3% by weight rosin size and 3.2% by weight based on the dry weight of the base paper (pulp sheet) before coating The paper was made using a pulp suspension (freeness 400 ml) having a shorter beating time than that of Example 1 and dried in the first dry part. Apply the coating liquid for fine coating to both sides by 2.0 g / m ² with respect to one side of the base paper, dry the coating liquid with the second dry part, and use the calendar part with 6 rolls. Smoothing treatment was performed to produce a transfer paper. At this time, the density of the pulp suspension as the paper stock was adjusted according to the paper making speed, and the basis weight was set to 90 g / m ² .

  Table 1 shows the physical properties and papermaking conditions of the obtained transfer paper. Furthermore, as a result of forming an image on the transfer paper produced above using an electrophotographic image forming apparatus and evaluating the transfer image in an environment of 23 ° C. and 5% Rh, the degree of “piercing” is acceptable. I was able to obtain a possible image.

Based on the manufacturing process shown in FIG. B. K. P (hardwood pulp), 5% by weight kaolin, 0.5% by weight sulfuric acid band, 0.3% by weight rosin size and 3.2% by weight based on the dry weight of the base paper (pulp sheet) before coating After making paper using a pulp suspension (freeness of 235 ml) beaten in the same manner as in Example 1 by mixing with a water-soluble binder, and drying with a dry part, the surface fine coating process was omitted, and six pieces were made. A transfer paper was produced by performing a smoothing process on a calendar part using a roll. At this time, the density of the pulp suspension as the paper stock was adjusted according to the paper making speed, and the basis weight was set to 90 g / m ² .

Table 1 shows the physical properties and papermaking conditions of the obtained transfer paper. Furthermore, as a result of forming an image on the transfer paper produced above using an electrophotographic image forming apparatus and evaluating the transfer image in an environment of 23 ° C. and 5% Rh, the degree of “piercing” is acceptable. I was able to obtain a possible image.
<Comparative Example 1>
Based on the manufacturing process shown in FIG. B. K. P (hardwood pulp), 5% by weight kaolin, 0.5% by weight sulfuric acid band, 0.3% by weight rosin size and 3.2% by weight based on the dry weight of the base paper (pulp sheet) before coating A paper suspension was made using a pulp suspension (freeness 400 ml) with a shorter beating time than Example 1, and dried in a dry part to produce a transfer paper. In the process of this comparative example, the surface fine coating process and the smoothing process in the calendar part were omitted. At this time, the density of the pulp suspension as the paper stock was adjusted according to the paper making speed, and the basis weight was set to 90 g / m ² .

Table 1 shows the physical properties and papermaking conditions of the obtained transfer paper. Furthermore, as a result of forming an image on the transfer paper produced above using an electrophotographic image forming apparatus and evaluating the transfer image in an environment of 23 ° C. and 5% Rh, the degree of “piercing” is acceptable. It was an impossible image.
<Comparative example 2>
Based on the manufacturing process shown in FIG. B. K. P (hardwood pulp), 5% by weight kaolin, 0.5% by weight sulfuric acid band, 0.3% by weight rosin size and 3.2% by weight based on the dry weight of the base paper (pulp sheet) before coating After the paper suspension was made using a pulp suspension (freeness 400 ml) having a shorter beating time than Example 1 and dried in a dry part, the surface fine coating process was as follows: The transfer paper was manufactured by performing smoothing with a calendar part using 6 rolls. At this time, the density of the pulp suspension as the paper stock was adjusted according to the paper making speed, and the basis weight was set to 90 g / m ² .

Table 1 shows the physical properties and papermaking conditions of the obtained transfer paper. Furthermore, as a result of forming an image on the transfer paper produced above using an electrophotographic image forming apparatus and evaluating the transfer image in an environment of 23 ° C. and 5% Rh, the degree of “piercing” is acceptable. It was an impossible image.
<Comparative Example 3>
Based on the manufacturing process shown in FIG. B. K. P (hardwood pulp), 5% by weight kaolin, 0.5% by weight sulfuric acid band, 0.3% by weight rosin size and 3.2% by weight based on the dry weight of the base paper (pulp sheet) before coating After making paper using a pulp suspension (freeness of 235 ml) beaten in the same manner as in Example 1 by mixing with a water-soluble binder, and drying with a dry part, the surface fine coating process was omitted, and six pieces were made. A transfer paper was produced by performing a smoothing process on a calendar part using a roll. At this time, the density of the pulp suspension as the paper stock was adjusted according to the paper making speed, and the basis weight was adjusted to 200 g / m ² .

  Table 1 shows the physical properties and papermaking conditions of the obtained transfer paper. Furthermore, as a result of forming an image on the transfer paper produced above using an electrophotographic image forming apparatus and evaluating the transfer image in an environment of 23 ° C. and 5% Rh, the degree of “piercing” is acceptable. It was an impossible image.

  The evaluation results of Examples 1 to 5 and Comparative Examples 1 to 3 are summarized in Table 1.

  The evaluation regarding the penetration was made by using a transfer paper that had been left in the environment at room temperature of 23 ° C. and a humidity of 5% to create a blue image on the entire surface using iR3300 manufactured by CANON CORPORATION. Judgment was made by visual inspection and evaluation was performed.

尚、実施例における画像評価は、単色の画像形成装置を用いて行ったが、本発明が対象とする画像形成装置はこれに限定されるものではなく、例えば中間転写体を用いたフルカラー画像形成装置等においても、同様の効果を得ることができる。

The image evaluation in the examples was performed using a single-color image forming apparatus. However, the image forming apparatus targeted by the present invention is not limited to this. For example, full-color image formation using an intermediate transfer member is performed. Similar effects can be obtained in the apparatus and the like.

It is the schematic of the typical papermaking process at the time of making the transfer paper of this invention. It is a typical sectional view of an electrophotographic image forming apparatus using a conventional transfer roller.

Explanation of symbols

31 Stock inlet 32 Wire 33 Roll coater 34 Roll

Claims (4)

An electrophotographic transfer paper having an index K represented by the following formula of 200 or less.
K = thickness ² / air permeability (μm ² / sec)   2. The transfer sheet for electrophotography according to claim 1, wherein the sizing degree is 10 sec or more.   The electrophotographic transfer paper according to claim 1 or 2, wherein the freeness of the pulp is from 100 ml to 350 ml.   4. The electrophotographic transfer paper according to claim 1, wherein a calendar process is performed.

Images