JP2006039114A - Color electrophotographic transfer paper - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a color electrophotographic transfer paper capable of obtaining an image free from fixing failure and transfer failure in electrophotographic image formation using polymerized toner. <P>SOLUTION: In the color electrophotographic transfer paper, an index B expressed by B = Gurley stiffness/air permeability<SP>2</SP>(mgf/s<SP>2</SP>) is 0.05 or less. The freeness of pulp is in the range of 300ml to 450ml. Filler in paper is in the range of 5 wt.% to 30 wt.%. The paper is subjected to supercalender processing. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an electrophotographic transfer paper, and more particularly to a color electrophotographic transfer paper used in a color electrophotographic image forming apparatus.

  Conventionally, as a multiple transfer device in a color image forming apparatus adopting an electrophotographic system, for example, an intermediate transfer member such as an intermediate transfer roll or an intermediate transfer belt is used, and each color toner image is once electrostatically transferred to the intermediate transfer member. There is an intermediate transfer system in which toner images of four colors are formed and transferred to a recording medium such as paper at once.

JP 55-142799 A

  However, the conventional transfer device has the following problems.

  When transferring a recording material having a relatively high resistance in a low humidity environment such as 23 ° C. and 5% RH in the above transfer device, an image due to transfer defects called “explosion” and “scattering” described below. There was a problem of quality degradation.

  “Explosion”: A phenomenon that occurs mainly when high-resistance paper is used in a low-temperature, low-humidity environment. For example, on an image sample, the toner scatters in a white area around the solid area, It is a transfer defect that degrades image quality. This is thought to be because the unfixed toner image once transferred onto the image is affected by the excess charge on the back of the transfer paper, repels each other and scatters like an explosion.

  “Spattering” is a phenomenon in which when toner is transferred, it is not transferred to a predetermined position and scatters in an arbitrary direction. For example, on the image sample, the outline around the character portion becomes blurred, and the character image This is a transfer failure that disturbs the image quality and lowers the image quality.

  As shown in Patent Document 1 and the like that solve such a problem, there is a method of limiting the electric resistance of a sheet to a specific range, but this method alone cannot be said to be a sufficient effect.

  An object of the present invention is to provide a color electrophotographic transfer paper capable of obtaining an image free from fixing defects and transfer defects in electrophotographic image formation using a polymerized toner.

  A color electrophotographic transfer paper having an index B represented by the following formula of 0.05 or less.

B = Gurley stiffness / air permeability ² (mgf / s ² )
The freeness of the pulp is 300 to 450 ml, the amount of filler in the paper is 5 to 30%, and supercalendering is performed.

  In the color electrophotographic transfer paper of the present invention, an image free from fixing defects and transfer defects can be obtained in electrophotographic image formation using polymerized toner.

  The present inventors have found that the occurrence of abnormal images in a low humidity environment such as “explosion” and “scattering” is closely related to the behavior of the transfer paper after passing through the transfer site, and as a result, the rigidity of the transfer paper is reduced. I found that it had a big influence. Furthermore, the present inventors have found that the occurrence of abnormal images under low humidity environments such as “explosion” and “scattering” has a close correlation with the porosity of the transfer paper, and as a result, the air permeability of the transfer paper is reduced. I found that it had a big influence.

From these results, as a result of intensive studies, the present inventors have made not only the resistance of the transfer paper, but also the index B shown in the following formula to be 0.05 or less, thereby reducing low humidity such as “explosion” and “scattering”. It has been found that the occurrence of abnormal images under the environment can be reduced.

B = Gurley stiffness / air permeability ² (mgf / s ² )
As a method of setting the value of B to a desired value, there is a method of filling a gap in the transfer paper with a substance other than fibers. For filling, fillers such as clay, talc, titanium white and calcium carbonate can be used.

  In addition, the desired air permeability and stiffness can be obtained by filling the voids in the transfer paper by beating the fibers to make the fibers fluffy or making them into fine fibers (single fibers). By improving the beating of the pulp in this way, the degree of entanglement between the fibers in papermaking can be improved, the voids in the paper can be reduced, the desired air permeability can be obtained, and the stiffness is also reduced. To do. Furthermore, by performing a super calendar process, a smoothing process can be performed, and the voids in the transfer paper can be crushed to obtain the desired air permeability and stiffness.

  The method for adjusting the B 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, and silicic acid is added to the pulp to be beaten. At this time, it is desirable to obtain the desired characteristics by matching the degree of beating to the freeness specified earlier.

  Further, a paper machine such as a long net 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 paper, such as a filler, a sizing agent, a binder as a paper strength enhancer, a dye, and a resistance modifier in advance to the pulp is moved in the direction of arrow R from the stock inlet 31. The obtained pulp sheet is further dehydrated by the press part and then dried by 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 the 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, and the like can be used. It is done.

  Examples of the cationic low resistance treatment agent include polyvinylbenzyltrimethylammonium chloride, polyvinylbenzyltriethylammonium chloride, polydimethylallyl ammonium chloride, polydiethyldiallylammonium chloride, polyethyleneimine hydrochloride, poly-4-vinyl-N methylpyridinium. Chloride, poly-2-hydroxy-3-methacryloxypropylmethylammonium chloride, poly-2-hydroxy-3-methacryloxypropylethylammonium chloride, poly-2-hydroxy-3-acryloxypropyltrimethylammonium chloride, poly-2 -Hydroxy-3-acryloxypropyltriethylammonium chloride, poly-2-methacryloxyethyl Limethylammonium chloride, poly-2-methacryloxyethyl triethylammonium chloride, poly-2-acryloxyethyltrimethylammonium chloride, poly-2-acryloxyethyltriethylammonium chloride, polystyrene acrylate ethyltrimethylammonium chloride, polystyrene acrylate ethyl Quaternary ammonium salts such as triethylammonium chloride can be mentioned, and these can be used alone or in combination.

  Examples of the anionic low-resistance treatment agent include polystyrene sulfonate (sodium salt and ammonium salt), polyacrylate (sodium salt and ammonium salt), polymethacrylate (sodium salt and ammonium salt), and polyvinylsulfone. Examples thereof include polymer electrolytes such as acid salts (sodium salt, ammonium salt) and polyvinyl phosphate (sodium salt, ammonium salt), and these can be used alone or in combination.

Further, the coating liquid finely coated by the size press part is a dispersion of an inorganic pigment, a low-resistance treatment agent, etc., and this is preferably 1 to 10 g / m 2 in terms of dry solid content per side.
Finely coat the surface so that The fine coating in the size press part is desirably performed in order to obtain the smoothness of the transfer paper or to adjust the surface resistance.

  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, what was described above 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 basis weight of the transfer material was measured according to JIS-P-8124.

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

  The Gurley stiffness of the transfer material is J. TAPPI No. Measured according to 40.

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

  The surface specific resistance value was measured according to JIS-K-6911.

  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. 30% by weight kaolin, 0.5% by weight sulfuric acid band, 0.3% by weight rosin size based on the dry weight of the base paper (pulp sheet) before coating on P (hardwood pulp) (freeness 300 ml) Then, paper is made using a pulp suspension prepared by mixing 3.2% by weight of a water-soluble binder, dried in the first dry part, and then a surface coating liquid for surface coating is applied by a roll coater. 2.0g / m2 for one side
Each was coated on both sides, and the coating liquid was dried with a second dry part, and smoothed with a calendar part using six rolls to produce a transfer paper. At this time, the density of the pulp suspension as the paper stock was adjusted according to the papermaking speed, and the basis weight was adjusted to 209 g / m ² . Further, this transfer paper was subjected to a super calendar process.

  The obtained transfer paper had a Gurley stiffness of 710 mgf and an air permeability of 128 seconds.

  Table 1 shows the results of forming an image on the transfer paper produced above using an electrophotographic image forming apparatus and evaluating the transfer in an environment of 23 ° C. and 5% Rh. As a result, it was possible to obtain an image having a level with no problem of explosion and scattering.

Based on the manufacturing process shown in FIG. B. K. P (hardwood pulp) (freezing degree 300 ml), 5% by weight kaolin, 0.5% by weight sulfate band, 0.3% by weight rosin size based on dry weight of base paper (pulp sheet) before coating Then, paper is made using a pulp suspension prepared by mixing 3.2% by weight of a water-soluble binder, dried in the first dry part, and then a surface coating liquid for surface coating is applied by a roll coater. by coating on both sides by 2.0 g / m ² with respect to one side, the second dried coating liquid with a dry part, produce the transfer sheet is subjected to smoothing treatment by calendering part with six rolls did. 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 .

  The obtained transfer paper had a Gurley stiffness of 97.8 mgf and an air permeability of 68.6 seconds.

  Table 1 shows the results of forming an image on the transfer paper produced above using an electrophotographic image forming apparatus and evaluating the transfer in an environment of 23 ° C. and 5% Rh. As a result, an image without explosion and scattering could be obtained.

  In Example 2, transfer papers having various physical properties shown in Table 1 were produced in the same manner as in Example 2 except that the freeness of pulp was 450 ml and the ratio of filler was 30%. When the obtained transfer paper was used for evaluation in the same manner as in Example 2, an image without explosion or scattering could be obtained. The results are shown in Table 1.

Based on the manufacturing process shown in FIG. B. K. P (hardwood pulp) (freezing degree 300 ml), 5% by weight kaolin, 0.5% by weight sulfate band, 0.3% by weight rosin size based on dry weight of base paper (pulp sheet) before coating Then, paper is made using a pulp suspension prepared by mixing 3.2% by weight of a water-soluble binder, dried in the first dry part, and then a surface coating liquid for surface coating is applied by a roll coater. by coating on both sides by 2.0 g / m ² with respect to one side, the second dried coating liquid with a dry part, produce the transfer sheet is subjected to smoothing treatment by calendering part with six rolls did. 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 52 g / m ² .

  The obtained transfer paper had a Gurley stiffness of 21.2 mgf and an air permeability of 28.9 seconds.

  Table 1 shows the results of forming an image on the transfer paper produced above using an electrophotographic image forming apparatus and evaluating the transfer in an environment of 23 ° C. and 5% Rh. As a result, it was possible to obtain an image having a level with no problem of explosion or scattering.

  In Example 4, transfer paper having various physical properties shown in Table 1 was produced in the same manner as in Example 2 except that the freeness of the pulp was 450 ml and supercalendering was performed. When the obtained transfer paper was evaluated in the same manner as in Example 4, an image free from explosion and scattering could be obtained. The results are shown in Table 1.

In Example 4, transfer paper having various physical properties shown in Table 1 was produced in the same manner as in Example 4 except that the freeness of pulp was 450 ml and the proportion of filler was 30%. When the obtained transfer paper was evaluated in the same manner as in Example 4, an image free from explosion and scattering could be obtained. The results are shown in Table 1.
<Comparative Example 1>
In Example 1, the transfer paper having various physical properties shown in Table 1 is the same as Example 1 except that the freeness of the pulp is 450 ml, the proportion of the filler is 5%, and the supercalendering is not performed. Manufactured. When the obtained transfer paper was evaluated in the same manner as in Example 1, explosion and scattering were at an unacceptable level. The results are shown in Table 1.
<Comparative example 2>
In Example 2, transfer paper having various physical properties shown in Table 1 was produced in the same manner as in Example 2 except that the freeness of the pulp was 450 ml. When the obtained transfer paper was evaluated in the same manner as in Example 1, explosion and scattering were at an unacceptable level. The results are shown in Table 1.
<Comparative Example 3>
In Example 4, transfer papers having various physical properties shown in Table 1 were produced in the same manner as in Example 2 except that the freeness of the pulp was 450 ml. When the obtained transfer paper was evaluated in the same manner as in Example 1, explosion and scattering were at an unacceptable level. The results are shown in Table 1.

  The evaluation results of Examples 1 to 6 and Comparative Examples 1 to 3 are summarized in Table 1.

The evaluation regarding explosion and scattering was evaluated according to the following evaluation method.
<Explosion, scattering>
Under 23 ° C / 5% Rh, solid images of magenta and cyan (each 0.5g / A4) were formed and fixed on transfer paper that had been allowed to stand in the environment, and their explosion and scattering were judged visually. And evaluated.

It is the schematic of the typical papermaking process at the time of making the transfer paper of this invention.

Explanation of symbols

31 Stock inlet 32 Wire 33 Roll coater 34 Roll

Claims (4)

A color electrophotographic transfer paper having an index B represented by the following formula of 0.05 or less.
B = Gurley stiffness / air permeability ² (mgf / s ² )   2. The color electrophotographic transfer paper according to claim 1, wherein the freeness of the pulp is from 300 ml to 450 ml.   2. The color electrophotographic transfer paper according to claim 1, wherein the content of the paper filler is 5% by weight or more and 30% by weight or less.   2. The color electrophotographic transfer paper according to claim 1, wherein supercalendering is performed.

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