JP2006098910A - Electrophotographic transfer paper manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrophotographic transfer paper free from defective traveling even when the paper is used immediately after seal breaking under an environment at high temperature and high humidity. <P>SOLUTION: An electrophotographic transfer paper manufacturing method is provided by which a cast coating layer is formed by coating one side of a base paper with coating liquid mainly constituted of pigment and binding agent, sticking a wet coating layer to a heated mirror-finished surface by pressure, and then, drying the paper. The coating liquid contains high molecular silicone having a number average molecular weight of 600,000 to 900,000, and also, the paper is held and humidified in air conditioned at 20 to 80°C and 50 to 90%RH for 20 seconds or longer after drying. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for producing transfer paper for use in an electrophotographic copying machine or the like, and particularly for electrophotography that has not only high glossiness on a blank paper but also excellent running characteristics in a copying machine, particularly in a high humidity environment. The present invention relates to a transfer paper manufacturing method.

  In general commercial printing and high-grade printing fields, offset printing is the mainstream, and coated paper such as art paper, coated paper, and cast coated paper is used. This is because the surface of the coated paper is very smooth, has good ink transferability and high image reproducibility, and good color reproducibility. Similarly, in the field of copiers, in order to obtain a more vivid image than ever before, the number of cases using the above coated paper in place of conventional PPC paper or printer paper is increasing. When a high quality feeling is required, cast coated paper is used. This trend is due to the recent progress in color, high speed, and high image quality of copiers and printers, and in the field of on-demand publishing, it is easy to publish a small number of copies using color copiers and printers, Increasingly, examples of making and publishing on copiers and the like have emerged.

  Copiers and printers supply paper to the printing unit by placing paper to be used in a tray inside the machine body or a manual feed tray installed outside the machine body. When supplying high-gloss, glossy coated paper for printing to such a copier or printer and passing it in a high-humidity environment, the paper and paper will stick together, making it difficult to supply. It is known that defects and running failures occur and are likely to cause paper jams.

  High white glossy coated paper has a highly smooth upper pigment layer, so high-quality PPC paper has high air permeability of 10 to 20 seconds, whereas the air permeability is several It is about 1,000 to 10,000 seconds, and the air permeability is low. For this reason, when laminated in a sheet form, the air between the papers is pushed out from the interlayer by pressurization, so that the papers are easily brought into close contact. In particular, when the laminated sheet is exposed to a high humidity environment, the periphery of the sheet suddenly swells due to moisture absorption from the cut surface of the paper. It is estimated to cause paper jams. Another factor affecting the occurrence of paper feed failure is blank paper curl (curl before copying). Therefore, it is desired that the blank paper curl be suppressed as much as possible to finish it flat and that the generated curl be small in a wide range of environments.

On the other hand, a method for producing cast coated paper includes a direct method in which a coating liquid is applied to the surface of a base paper and then immediately pressed onto a cast drum by a forming roll while the coating layer is in a wet state. After coating, the coating layer is passed through a coagulation bath, solidified into a deformable plastic gel state, and then crimped to the cast drum, and after coating the coating solution, it is dried once and dried After obtaining the coated surface, the dried coated surface is roughly classified into a re-wetting method in which the dry coated surface is re-moistened with water or a suitable re-wetting liquid and then pressed onto a cast drum. In each of these methods, a coating liquid having a pigment and a binder is applied to a base paper, a coating layer in a plastic state is applied, and a forming roll (press roll) is applied to a cast drum surface having a heated mirror surface. They are common in that they are pressure-bonded, dried and released to give a high gloss finish. In general, cast coated paper has a large difference in coating amount between the front and back surfaces, so that, for example, when environmental humidity is changed, curling tends to occur more easily than in general coated paper.
For example, to prevent curling, etc., after applying the coating solution to the base paper, after the drying process or after the drying is finished, the cast paper with polyethylene glycol applied to the back of the base paper is manufactured to prevent curling. In addition, it is disclosed to obtain a transfer paper having good running properties (see Patent Document 1). However, curling suppression and running performance in environmental changes such as high humidity are still insufficient.
JP 9-228296 A

  Therefore, the object of the present invention is to suppress the adhesion and curling between papers even though the surface property of the cast surface is good, and the running property when printing by electrophotography under high humidity is good. Another object of the present invention is to provide a method for producing an electrophotographic transfer paper.

As a result of intensive studies to solve the above-described problems, the present inventors have found that a high number average molecular weight of 600,000 to 900,000 is present in the coating liquid at the time of producing cast coated paper mainly composed of a pigment and a binder. It has been found that adhesion and curling between papers are suppressed and the running property is improved by adding molecular silicone and adjusting the humidity after pressure-bonding and drying to a heated mirror-finished surface before winding. .
That is, in the present invention, a coating liquid mainly composed of a pigment and a binder is applied to one side of a base paper, and then a wet coating layer is pressure-bonded to a heated mirror-finished surface and dried. In the method for producing an electrophotographic transfer paper in which a cast coating layer is formed by the above, the coating solution contains a high molecular silicone having a number average molecular weight of 600,000 to 900,000, and after the drying, 20 to 80 ° C., 50 A method for producing an electrophotographic transfer paper, characterized in that it is kept in air adjusted to ˜90% RH for 20 seconds or more and humidified. In particular, when passing through a high-temperature, high-humidity chamber, it is preferable to blow air having substantially the same temperature and humidity as the air in the chamber on the cast coating surface and the opposite surface. Further, when humidifying the paper by blowing the adjusted air, it is preferable to suppress the generation of wrinkles using an expander roll, and water or an aqueous solution is preferably formed on the opposite surface of the cast coating surface immediately before the humidity adjustment. Alternatively, it is preferable to apply an aqueous dispersion such as a pigment. Furthermore, when drying the opposite side of the cast coating surface, it is preferable to use a cylinder dryer having a large restraining force in the CD direction during drying.

  The transfer paper obtained by the present invention has a water content close to that which is reached when electrophotographic printing is performed under high humidity, and adhesion and curling between the papers are suppressed, so that the running property is reduced. The surface property of the coated surface is also good.

  The base paper used in the present invention is, for example, disaggregating pulp fibers to form a slurry, and if necessary, adding a filler, a sizing agent and other additives, making paper with a paper machine and drying, or after making paper, It can be obtained by subjecting starch or an aqueous solution of a polymer substance to size pressing, drying, and applying a machine calendar. The pulp to be used can be appropriately selected from pulps used in normal papermaking, such as chemical pulp of L (hardwood) material and N (softwood) material, mechanical pulp, and waste paper pulp. As the internally added filler, for example, talc, kaolin, clay, calcium carbonate, titanium dioxide, silica and the like can be appropriately selected and used from fillers usually used.

The base paper used in the present invention is a base paper having a basis weight of 50 to 400 g / m ² used for general printing coated paper and cast coated paper. Depending on the purpose, high quality paper, medium quality paper, recycled paper, etc. are selected. And use it. Further, as the base paper, a base paper coated with a paint containing a pigment and an adhesive may be used. As the coating method for undercoating, coating using a known coating machine such as a blade coater, air knife coater, roll coater, spray coater, kiss coater, squeeze coater, curtain coater, bar coater, gravure coater, comma coater, etc. The method can be appropriately selected and used.

  In the present invention, the pigment used for the coating layer at the time of casting is, for example, kaolin, clay, calcium carbonate, talc, amorphous silica, alumina, aluminum hydroxide, magnesium carbonate, satin white, titanium dioxide, silicic acid. Pigments such as aluminum, colloidal silica, montmorillonite, and plastic pigment can be used alone or in combination of two or more.

Examples of the binder used in the coating layer of the present invention include casein, soybean protein and synthetic protein, styrene / butadiene latex, acrylic emulsion, vinyl acetate emulsion, polyurethane, oxidized starch, esterified starch and other starches, polyvinyl One or two or more kinds of binders selected from alcohol, carboxymethylcellulose, hydroxycellulose and the like can be used.
Furthermore, the coating liquid of the present invention includes a dispersant, a fluidity modifier, an antifoaming agent, a dye, a lubricant, a water retention agent, a pigment dispersant, a thickener, a fluidity improver used in general paints, Antifoaming agent, antifoaming agent, release agent, foaming agent, penetrating agent, coloring dye, coloring pigment, fluorescent whitening agent, ultraviolet absorber, conductive agent, antioxidant, antiseptic, antibacterial agent, water resistance agent Various auxiliary agents such as a wet paper strength enhancer and a dry paper strength enhancer can also be added.

  In the present invention, a coating layer is formed by applying a coating liquid containing a pigment, a binder, and a polymeric silicone having a number average molecular weight of 600,000 to 900,000, typically polyalkylsiloxane, as a release agent. After being provided, while the coating layer is in a wet state, the coating layer is pressed onto a heated mirror-finished surface and dried. The reason why the adhesion between the papers is suppressed when blending the coating layer with a polymer silicone having a number average molecular weight of 600,000 to 900,000 is not clear, but the coating layer is pressed onto the heated mirror-finished surface and dried. When the polymer silicone is not uniformly distributed in the coating layer, the polymer silicone is distributed on the outermost surface of the coating layer by moving to the outermost surface, and the lubricity and It is considered that the adhesion between the coating layer and the opposite layer of the coating layer is suppressed by the impact relaxation property. In addition, since it is possible to make the polymer silicone exist on the very surface, the electrophotographic recording quality such as toner transfer property and image reproducibility is not deteriorated as compared with the case of applying the polymer silicone solution, It is presumed that adhesion between papers can be suppressed.

If the number average molecular weight of the polymer silicone is less than 600,000, the transferability is too high, which adversely affects the transportability in the electrophotographic copying machine and may cause a paper jam. On the other hand, when the number average molecular weight exceeds 900,000, the transferability is too low, and the effect of containing the polymeric silicone in the coating solution is not observed. The number average molecular weight can be determined by a known analysis such as GPC method.
The polymeric silicone is preferably used by adding 0.5 to 10 parts by weight with respect to 100 parts by weight of the pigment in the coating layer. It is possible to suppress the adhesion between papers as the amount of the polymeric silicone is increased. However, when the blending ratio is large, performances other than adhesion (such as printability) tend to deteriorate. By setting it as the said mixture ratio, the adhesiveness between papers can be suppressed, without impairing electrophotographic printability. As the high molecular silicone, polyalkyl siloxane, polyaminosiloxane, polyamide siloxane, polyepoxy siloxane, polycarboxy siloxane, polyphenol siloxane, polyether siloxane, polyfluoroalkyl siloxane, etc. can be used, especially polyalkyl siloxane is used. It is preferable.

  In the present invention, the coating liquid for the coating layer is prepared by dispersing the pigment, the binder, the polymer silicone, and other additives blended as necessary in an aqueous system. When an aqueous coating solution is used, it is preferable to add the polymeric silicone as an aqueous dispersion (polymeric silicone dispersion) to the coating solution using an emulsifier such as polyether-modified silicone. By using the polymer silicone dispersion, a stable coating solution in which the polymer silicone is uniformly dispersed can be obtained. The amount of the emulsifier at this time can be appropriately determined while observing the state of emulsification of the polymer dispersion, but usually about 20 to 50% by weight of the emulsifier may be added to the polymer silicone.

The method of applying the coating liquid to the surface of the base paper is the same as the method of applying the undercoat layer, blade coater, air knife coater, roll coater, comma coater, brush coater, kiss coater, squeeze coater, curtain coater. The coating method using a known coating machine such as a bar coater, a gravure coater, or a spray coater can be appropriately selected. The coating amount of the coating layer can be arbitrarily adjusted as long as the surface of the base paper is covered and the toner is sufficiently uniformly fixed, but it is 5 to 30 g / m ^{2 in} terms of solid content per side. It is preferable that it is 10-25 g / m < ² > especially.

  The coating layer thus formed on the base paper is formed by pressing and drying in a wet state on a cylindrical drum having a heated mirror-finished surface. The wet coating layer can be pressure-bonded to the mirror drum and dried. The direct coating method can be the method of pressing the wet coating layer directly to the mirror drum, or the non-dried surface after coating can be treated with a coagulation liquid. A solidification method in which the working layer is brought into a gel state and then pressure-bonded, or a re-wetting method in which a re-wetting liquid is applied to a coating layer once dried after coating to plasticize it and then pressure-bonded can be used.

  In the present invention, in particular, a coagulation method is used in which a wet coating layer is coagulated with a coagulation liquid containing an organic acid, an oxo acid, or a metal salt of those acids and then pressed and dried on a mirror drum. Is preferable because the surface properties of the cast coating layer can be improved as compared with the direct method and the rewet method.

  In the present invention, before winding the coated paper press-bonded and dried on the mirror drum as described above, the coated paper is passed through an atmosphere having a temperature of 20 to 80 ° C. and a humidity of 50 to 90% RH. Thus, moisture can be applied from both sides of the paper without impairing the surface properties of the cast coated surface. If moisture is applied using water vapor as in the past, water vapor can be applied only from the opposite side of the cast coating surface so that the surface property of the cast coating surface is not impaired. Since dew condensation occurs in the equipment, it was difficult to give a lot of moisture. On the other hand, according to the method of the present invention described above, moisture can be applied from both sides of the paper, and the occurrence of dew condensation can also be suppressed, so that more water is applied than in the conventional method using water vapor. Can do. Moreover, since moisture is applied from both sides, the occurrence of curling due to moisture application can be suppressed.

  In the present invention, in order to impart moisture, it is preferable that the surroundings where the paper after the formation of the cast coating surface passes is at a high temperature and high humidity, so that condensation does not occur when the paper passes. It is preferable to keep the temperature and humidity constant in the range of ˜80 ° C. and 50˜90% RH. Furthermore, in order to give a large amount of moisture, it is preferable that the pass line length is designed to be relatively long and the passing time is set to 20 seconds or longer. As a specific configuration example, for example, the one shown in FIG.

Since the rate at which moisture is applied is increased by increasing the temperature and humidity, the moisture application efficiency is also increased. However, when the environment is high in temperature and humidity, deterioration of the working environment and the occurrence of dew condensation in the surrounding facilities are likely to be problematic. Therefore, the temperature is preferably adjusted to 40 to 60 ° C. and 60 to 90% RH.
It should be noted that the temperature of the web of cast coated paper is very high immediately after pressure bonding to the mirror drum and drying. Lowering the paper surface temperature before introducing the chamber increases the amount of moisture adhering to the web and increases the moisture application efficiency in the chamber than when the web temperature remains high when the web is fed into a constant temperature and humidity chamber. Become. Therefore, it is preferable to lower the temperature of the web before introducing the chamber.

As a method for lowering the temperature of the web, there are a method using a cooling device, a method of bringing cooling water or the like into contact with the surface of a metal roll, a method of blowing low temperature air, and the like. Further, before introduction into the constant temperature and humidity chamber, water may be applied to the opposite surface of the coating surface, or air may be sprayed onto the web surface.
After the web is introduced into the chamber, the web can be repeatedly run in a loop in the chamber in order to hold the web in the chamber for 20 seconds or longer, preferably 30 seconds or longer. At this time, especially when the temperature and humidity in the chamber are set high, the paper rapidly expands in the direction perpendicular to the running direction because of rapid moisture absorption, so use a normal paper roll when running the paper in a loop. When the paper running direction is changed, it is often the case that wrinkles are generated on the roll without absorbing the paper elongation. Therefore, it is preferable to use an expander roll that has the effect of stretching the paper in the lateral direction, particularly in the initial stage when the web runs in the chamber.

  Furthermore, when passing through a chamber of high temperature and high humidity, it is preferable to blow air having substantially the same temperature and humidity as the air in the chamber on both the cast coating surface and the opposite surface. As a result, the moisture application efficiency can be increased without impairing the surface properties of the cast coating surface, and the size and shape of the curl can be further increased by adjusting the air volume for the cast coating surface and the opposite surface. It is possible to suppress. In addition, in order to reduce the curl that occurs after printing in the electrophotographic system when the environmental humidity is changed, immediately after press-bonding and drying to the mirror drum, water or After applying an aqueous dispersion such as an aqueous solution or pigment and drying, apply moisture in a room controlled to high temperature and high humidity, or apply water in a room controlled to high temperature and high humidity, and then cast It is preferable to dry by applying water to the opposite surface of the work surface.

  The reason why the curl is improved by applying moisture to the cast coated paper as described above is not necessarily clear, but as a result of the increase in the moisture content in the paper of the cast coated paper, It is considered that the amount of moisture absorption upon contact is reduced and curling is suppressed. It is also conceivable that curling that occurs with changes in environmental humidity is improved by applying and drying the aqueous dispersion on the opposite surface. This is because the opposite surface of the cast coating surface is stretched by applying an aqueous dispersion such as water, aqueous solution or pigment to the opposite surface of the cast coating surface formed after pressure bonding to the mirror drum and drying, and then drying again. Then, not only the stress is released in the process of shrinking moderately thereafter, but also the fibers close to the cast coating surface side are released from the shrinkage stress accumulated during drying in the cast drum, so that curling can be prevented. It is considered a thing.

In this way, even if the high moisture sheet to which moisture has been applied is exposed to a high humidity environment, the degree of swelling of the periphery of the sheet due to moisture absorption from the cut surface is kept small compared to the low moisture sheet. It is estimated that the running performance is improved while the performance is suppressed.
In the present invention, although depending on the properties of the cast coated surface and the required quality level, if the moisture content in the paper of the product is 8% by weight or more, the surface properties of the cast coated surface will be slightly impaired. The final moisture content in the paper is preferably about 5.5 to 8% by weight.

For the method of applying a water dispersion such as water or starch or an aqueous dispersion such as a pigment to the opposite surface of the cast coating surface after press-bonding to the mirror drum and drying to form a cast coating surface, uniformly Any device may be used as long as it is applied, and there is no particular limitation. Generally, from among coating methods using known coating machines such as blade coaters, air knife coaters, roll coaters, spray coaters, kiss coaters, squeeze coaters, curtain coaters, bar coaters, gravure coaters, comma coaters, etc. Select and use.
In general, the coating speed at the time of cast coating is slower than that at the time of coating general coated paper, and it is difficult to obtain a uniform coating profile. Therefore, in order to obtain an appropriate coating amount, a plurality of coating apparatuses using a known coating method may be arranged in the coating direction. Water content at the time of applying the water to the opposite surface, the quality characteristic of interest, 0.1 to 20 g / ^{m 2,} is preferably selected arbitrarily from the range of 1 to 10 g / ^{m 2.}

In addition, as a method of performing drying with restraint in the CD direction, a cylinder dryer for drying in a state where it is pressed against a rotating cylinder, a dryer of a type in which hot air is blown in a state where paper is pressed against a cylinder or the like, For example, a dryer that heats and dries while holding paper between a belt or canvas. Generally, the drying method using a cast drum is the same as the drying mechanism of a cylinder dryer, and since the binding force in the CD direction during drying is strong, the drying method after coating treatment on the opposite surface is also the CD direction of the cylinder dryer or the like. It is preferable to perform drying in a state where the above-described constraint is given, because the balance in drying between the front and back surfaces can be balanced and curling can be further suppressed.
The moisture content in the cast coated paper after drying is preferably 1 to 10% by weight, particularly preferably 3 to 8% by weight, from the viewpoint of the surface properties of the cast surface and curling suppression.

  Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples, but the present invention is not limited thereto. Further, “parts” and “%” shown below represent “parts by weight” and “% by weight” unless otherwise specified. In addition, the evaluation method of each evaluation item is as follows.

<Evaluation methods>
(1) Evaluation of corrugation and curl The cast coated paper produced in each Example and Comparative Example was cut into A4 size (297 × 210 mm), and 200 sheets were immediately piled up at 23 ° C. and 50% RH. The sample was allowed to stand for 4 hours or more in the above environment, and the state of wavy deformation occurring on the cut surface was visually evaluated.
○: No waviness occurs and has a good cut surface.
Δ: Slight undulation is observed, but the cut surface is relatively good.
×: Wavy.

  Each curl was cut into a size of 100 mm × 100 mm, and evaluated after standing for 4 hours or more with the cast coating surface facing up. The curl was measured by placing each sample on a flat plate so that the inner surface of the curl was up and measuring the height of the four corners of each sample. The values shown in the table are average values of the heights of the four corners. Further, a positive value was obtained when the cast coating surface was curled inward, and a negative value was obtained when the opposite surface was curled. For this reason, the curl is better as the absolute value of the numerical values in the table is smaller.

(2) Surface property of cast coated surface The surface property of the cast coated surface was visually evaluated.
A: The mirror surface pattern is reproduced well and has a smooth surface shape.
(Triangle | delta): A mirror surface pattern is not fully reproduced and there exists some gloss unevenness.
X: Mirror surface pattern reproduction is insufficient and gloss unevenness occurs.

(3) White paper glossiness It was measured at 75 ° glossiness according to JIS P 8142.
(4) Adhesiveness Under an environment of 30 ° C. and 80% RH, the maximum force when the uppermost paper is pulled horizontally in the deposited state immediately after opening the wrapping paper is taken as the adsorption force, did.

(5) Running performance Using an electrophotographic copying machine (DocuPrint C1250: product name of Fuji Xerox Co., Ltd.), after opening the wrapping paper in a high humidity environment of 30 ° C. and 80% RH, immediately run 100 sheets by double-sided printing. And evaluated as follows.
A: No double feed or paper jam occurs.
○: Almost no double feed or paper jam occurs.
Δ: Occasional occurrence of double feed or paper jam.
X: Frequent feeding and paper jam frequently occur.

A paper slurry is made by adding 15 parts of heavy calcium carbonate, 0.2 part of alkyl ketene dimer and 0.5 part of aluminum sulfate to a pulp slurry consisting of 100 parts of hardwood bleached kraft pulp with a freeness of 400 ml. A base paper having a smoothness of 40 seconds and a basis weight of 130 g / m ² was obtained.
On the surface of the obtained base paper, 60 parts of primary kaolin (Ultra White 90, manufactured by EMC) and 40 parts of light calcium carbonate (TP-121, manufactured by Okutama Kogyo Co., Ltd.) are used as pigments, and styrene-butadiene latex ( 10 parts of JSR0617 (manufactured by Nippon Synthetic Rubber Co., Ltd.), 5 parts of casein (Lactic casein, trade name from New Zealand), and calcium stearate (Nopcoat C-104-HS, manufactured by San Nopco) as a mold release agent is set to 0. Add 5 parts of polyalkylsiloxane (number average molecular weight 700,000) 60 wt%, polyether-modified silicone 20 wt%, and water 5 wt% dispersion (solid content). Using a roll coater, the coating amount of the solid content concentration of 50% is set to 20 g / m ^2. After coating on one side of the base paper, it is solidified using a 10% aqueous solution of calcium formate, and while the coating layer is in a wet state, it is pressed onto a mirror surface (cast drum) heated to 105 ° C. and dried. A cast coating layer was obtained.
Next, the paper was passed through a chamber adjusted to a temperature of 45 ° C. and 75% RH for 60 seconds to obtain an electrophotographic transfer paper having a water content of 7% (see FIG. 1). . The coating amount in this case was 18 g / m ² by dry weight.

  After obtaining a cast coated surface in the same manner as in Example 1, when passing paper for 60 seconds through a temperature-controlled and humidity-controlled chamber at 45 ° C. and 75% RH, the cast coated surface and the opposite surface were respectively provided. The electrophotographic transfer as in Example 1 except that the moisture content in the paper was 7.3% by blowing air adjusted to 45 ° C. and 75% RH with a nozzle at a wind speed of 7 m / sec. Paper was obtained (Figure 1).

  After obtaining a cast coated surface in the same manner as in Example 1, when passing paper through a chamber adjusted to 45 ° C. and 75% RH for 60 seconds, 5 m / second on the cast coated surface, The same electron as in Example 1 except that the moisture content in the paper is 7.3% by blowing air adjusted to 45 ° C. and 75% RH with a nozzle at a wind speed of 10 m / sec on the opposite surface. Photographic transfer paper was obtained (FIG. 1).

After obtaining a cast coated surface in the same manner as in Example 1, 6.1 g / m ^{2 of} water was applied to the opposite surface of the cast coated surface using a roll coater, and dried using a cylinder dryer. Next, for electrophotography similar to Example 1, except that the moisture content in the paper is 7% by passing the paper through a chamber adjusted to a temperature of 45 ° C. and 75% RH for 60 seconds. A transfer paper was obtained. When drying with a cylinder dryer, drying was performed so that the cast coating surface was in contact with the cylinder dryer (FIG. 3).

  After obtaining a cast coated surface in the same manner as in Example 1, when passing paper for 60 seconds through a temperature-controlled and humidity-controlled chamber at 50 ° C. and 85% RH, the cast coated surface and the opposite surface were respectively provided. For electrophotography similar to Example 1, except that air adjusted to 50 ° C. and 85% RH is blown with a nozzle at a wind speed of 7 m / second, and the moisture content in the paper is 8.1%. A transfer paper was obtained. At this time, a humidifier using an expander roll was used (FIG. 2).

[Comparative Example 1]
After obtaining a cast coated surface in the same manner as in Example 1, an electrophotographic transfer paper similar to that in Example 1 was obtained except that the moisture content in the paper was 3.1% without applying moisture. It was.

[Comparative Example 2]
After obtaining the cast coated surface in the same manner as in Example 1, the moisture content in the paper was 4.3% by passing the paper through a chamber adjusted to a temperature of 45 ° C. and 85% RH for 15 seconds. Except that, an electrophotographic transfer paper similar to that in Example 1 was obtained.

[Comparative Example 3]
After obtaining the cast coated surface in the same manner as in Example 1, the surface opposite to the cast coated surface was humidified using steam humidification, and the moisture content in the paper was 4.5% except for Example 1. An electrophotographic transfer paper similar to the above was obtained.

[Comparative Example 4]
After obtaining a cast coated surface in the same manner as in Example 1, after applying 6.1 g / m ^{2 of} water using a roll coater on the opposite side of the cast coated surface, it was dried using a cylinder dryer, An electrophotographic transfer paper similar to that of Example 1 was obtained except that the moisture content in the paper was 3.6%. When drying with a cylinder dryer, drying was performed such that the cast coating surface was in contact with the cylinder dryer.

  For the coated papers obtained in Examples 1 to 5 and Comparative Examples 1 to 4, the corrugated surface of the cut surface, the curl height, the glossiness of the blank surface of the cast surface, and the adhesion between papers in a high humidity environment (adsorptive power) ), And the results of evaluating the running performance of the electrophotographic copying machine are shown in Table 1. As is apparent from the results in Table 1, the cast coated paper obtained by the method of the present invention is different from the coated paper obtained in the comparative example in that the adhesion between the papers in a high humidity environment is suppressed. As a result, it was confirmed that the running property of the electrophotographic system was good.

  Since the electrophotographic transfer paper of the present invention has good runnability, it is particularly effective when used in a hot and humid environment.

FIG. 3 is a diagram showing an example of a process for producing an electrophotographic transfer paper of the present invention. The number of air blowing nozzles in the figure can be changed as appropriate. It is a figure which shows the manufacturing process of the transfer paper for electrophotography of this invention when an expander roll is used in a chamber. It is a figure which shows the manufacturing process of the electrophotographic transfer paper of this invention in the case of using a cylinder roll.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Cast drum 2 Coater head 3 Coagulation liquid application place 4 Back surface water coating apparatus 5 Cylinder dryer 6 Air spray nozzle 7 Constant temperature and humidity chamber 8 Blower 9 Expander roll

Claims (7)

  After coating a coating solution mainly composed of pigment and binder on one side of the base paper, the wet coating layer is pressure-bonded to the heated mirror-finished surface and dried to form a cast coating layer. In the method for producing an electrophotographic transfer paper to be formed, the coating solution contains a high molecular silicone having a number average molecular weight of 600,000 to 900,000 and is adjusted to 20 to 80 ° C. and 50 to 90% RH after the drying. A method for producing an electrophotographic transfer paper, wherein the method is maintained in the air for 20 seconds or more and humidified.   The method for producing an electrophotographic transfer paper according to claim 1, wherein the adjusted air is humidified by spraying each of the cast coating surface and the opposite surface.   The method for producing an electrophotographic transfer paper according to claim 1 or 2, wherein an expander roll is used to suppress generation of wrinkles during the humidification.   The method for producing an electrophotographic transfer paper according to any one of claims 1 to 3, further comprising a step of cooling the web that has been heated to a high temperature by pressure bonding and drying to a mirror-finished surface before the humidification.   5. The method for producing an electrophotographic transfer paper according to claim 4, wherein the cooling step is a step of applying water or an aqueous dispersion such as an aqueous solution or a pigment to the surface opposite to the cast coating surface.   The method for producing an electrophotographic transfer paper according to any one of claims 1 to 5, wherein the high molecular weight silicone is polyalkylsiloxane. The method for producing an electrophotographic transfer paper according to any one of claims 1 to 6, wherein the surface opposite to the cast coating surface is dried by a cylinder dryer.