JP2739160B2 - Transfer paper for electrophotography - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic transfer paper, and more particularly to an electrophotographic monochrome and color copying machine that reproduces high-quality images comparable to prints. The present invention relates to transfer paper used in an electrophotographic printer after performing beautiful printing or form printing in advance.

2. Description of the Related Art In a copier using an electrophotographic system, various functions of a printer have been improved with the progress of office automation, and the use of the printer has been aimed at increasing the added value. For example, copiers not only have improved mechanical construction functions such as high speed, enlargement / reduction, trimming, automatic double-sided copy, and automatic document feed, but also improved exposure methods, toner quality, and development methods to improve halftone recording suitability and blackness. Other than the above, recording quality has been improved, such as single-color recording, multi-color recording, full-color recording, etc., and improvements have been made from a simple monochrome copier to a multi-color printer. For electrophotographic printers, we also developed a two-color printer for red and black and printed out data from a computer on paper that had been beautifully printed in advance, such as multi-color printing or color form printing, for direct mail. Efforts are being made to add value, such as creating postcards and pamphlets. Coated paper is generally used as the transfer paper for performing recording with high image quality and high added value. In order to enhance the multicolor printing effect, the use of ordinary coated paper has been proposed,
It has been proposed to use a special coated paper for high quality recording in electrophotographic recording. (Japanese Patent Laid-Open No. 62-19887
(5, JP-A-62-198876, JP-A-62-198877) However, when recording with a high photographic or image area ratio using these coated papers, there is a disadvantage that the curl after recording becomes large, There is a problem in ease of handling.

[Problems to be Solved by the Invention] An object of the present invention is to reproduce a high-quality copy image, have good pre-printing suitability, and curl after recording even when recording is performed with a high image area ratio. An object of the present invention is to provide a transfer paper for electrophotography, which has a small amount and is easy to handle.

[Means for Solving the Problems] In order to achieve the above object, the present inventors have intensively studied the mechanism of curl generation after recording and the improvement thereof. As a result, when the transfer paper on which the toner is transferred passes through a heat roll or an oven-type fixing device, the transfer paper and the toner are heated to about 120 ° C. to 220 ° C., so that moisture in the transfer paper evaporates instantaneously. The transfer paper contracts, and in this state, the toner is heat-fused on the transfer paper to form a toner layer, and is discharged from the fixing device. For this reason, the transfer paper after recording is indoors,
In particular, it has been found that when placed at a high humidity of 20 ° C. and 65% RH or higher, the transfer paper absorbs moisture and elongates, whereas the toner layer does not elongate, which is considered to cause curl.

In order to improve such curling, it is not possible to obtain a sufficient effect simply by controlling the types of chemicals in the coating layer, the compounding ratio thereof, and the amount of application to improve the expansion and contraction of the transfer paper. The stretch of the base paper itself used for the transfer paper must be reduced.

For this reason, the present invention uses a base paper made by a Yankee machine, provides a coating layer on at least one side thereof, and adjusts the surface to a Beck smoothness measured by JIS P8119 of 20-2000 seconds. The present invention relates to a transfer paper for electrophotography, wherein a humidity change expansion and contraction rate (lateral direction) measured according to .TAPPI No.28 is 0.41% or less.

Paper made with a Yankee machine has high smoothness on one side and is glossy, so it is considered unsuitable as writing paper or transfer paper for electrophotography and has not been used so far. However, based on the above findings, the present inventors have rather focused on a feature that the elasticity with respect to a change in humidity is small.

In general, paper made efficiently at high speed is dried while receiving tension between a large number of cylindrical dryer groups in the vertical direction (papermaking direction) and freely shrinking in the horizontal direction.
When paper undergoes a change in humidity, the expansion and contraction in the lateral direction tends to increase. For example, paper conditioned at 20 ° C and 65% RH at 20 ° C
When placed in a low humidity of% RH, the vertical length /
Lateral direction = 0.1-0.3% / 0.3-0.5% Shrink, when placed in high humidity of 20 ° C 88% RH, vertical / horizontal direction = 0.1-0.3% / 0.3-0.7% of the original length Elongate.

On the other hand, when making paper with a Yankee machine, the paper is dried in close contact with a large-diameter cylindrical dryer that is hard chrome-plated and mirror-finished in a high-moisture state with a water content of 60% or more. Without being subjected to vertical tension, and by being in close contact with the dryer,
Drying shrinkage is controlled in both the vertical and horizontal directions.
For this reason, even if the paper undergoes a change in humidity after drying, the expansion and contraction in the horizontal direction is only slightly larger than that in the vertical direction. For example, when a paper conditioned at 20 ° C and 65% RH is placed in a low humidity of 20 ° C and 33% RH, the vertical / horizontal direction = 0.05 to the original length
0.2% / 0.1 ~ 0.2% shrinkage, when placed in high humidity of 20 ℃ 88% RH, vertical / horizontal = 0.05 ~ 0.2% /
Extends 0.1-0.2%.

As described above, the paper made by the Yankee machine has a small expansion and contraction in the lateral direction, and is therefore effective in improving the curl tendency after recording of the transfer paper provided with the coating layer. In the present invention, the paper made by such a Yankee machine is used for an electrophotographic transfer paper, and the humidity change expansion and contraction rate (transverse direction) of the surface after providing a coating layer is determined by J.TAPPI No. When measured according to 28 "Testing method for expansion and contraction of paper and paperboard due to changes in humidity"
The intended purpose is achieved by providing electrophotographic transfer paper having a content of 0.41% or less.

When making paper with a Yankee machine In general, the blending ratio of hardwood bleached kraft pulp (LBKP) and softwood bleached kraft pulp (NBKP) with a beating degree of 400 to 600 cc measured with a Canadian freeness tester is 100/0 to 30/70. And mix with
The pulp slurry thus obtained is added to talc, clay,
In addition to a filler such as calcium carbonate, a sizing agent, and a fixing agent, a wet strength improver, a dye, and a fluorescent whitening agent are appropriately added and used. As a sizing agent, use a rosin sizing agent or a petroleum resin sizing agent, use an acidic papermaking method using aluminum sulfate as a fixing agent, or use an alkyl ketene dimer or alkenyl succinic anhydride as a sizing agent to fix cationized starch. A neutral papermaking method used as an agent can be used.

In the present invention, after providing a coating layer on at least one side of the base paper made by a Yankee machine, by a calendar treatment or the like, the Bekk smoothness of the coating layer surface measured by JIS P8119 is 20 to 2000 seconds. Do the processing. By performing calendar processing, etc., it is possible to improve the runnability of transfer paper in copiers and printers, and to enable high quality recording,
The pre-printing effect can be improved. In this case, if the Bekk smoothness of the coating layer is less than 20 seconds, the coated surface has a rough feeling and has dry wrinkles after coating, so that the recorded image quality is deteriorated and the pre-printing effect is not sufficiently exerted. Also,
Since the coefficient of static friction between the front and back surfaces of the paper is large, the running property of the paper in the printer becomes poor. On the other hand, if the Bekk smoothness of the coating layer exceeds 2,000 seconds, the adhesion between the papers becomes too strong, the coefficient of static friction between the papers increases, and the running property also becomes poor.

In the present invention, after forming the coating layer in this way, the humidity change expansion and contraction rate (horizontal direction) after setting the Beck smoothness to 20 to 2000 seconds is set to 0.41% or less. By doing so, as shown in Table 1, it is possible to provide an electrophotographic transfer paper which has a good curl generation state after recording, and has excellent multicolor printing effect and running property. Becomes

The pigment serving as the main component of the coating layer smoothes the coating layer surface by calendering after coating, so that the average particle size is 2.0 μm.
Below, desirably fine particles of 1.5 μm or less are suitable,
For example, inorganic pigments such as heavy calcium carbonate, light calcium carbonate, kaolinite clay, sericite, siegrite, calcined clay, aluminum hydroxide, lithopone, zinc oxide, titanium dioxide, barium sulfate, silica, talc, magnesium carbonate and the like Organic pigments such as styrene resin beads, urea resin beads, acrylic resin beads, ethylene resin beads, propylene resin beads, and benzoguanamine resin beads are used. As the adhesive, a water-soluble adhesive, an emulsion, or a latex, which has a strong adhesion to a pigment or a base paper and has a low blocking property, is used alone or as a mixture.
For example, polyvinyl alcohol, starch, methylcellulose, hydroxyethylcellulose, styrene-acrylic resin, isobutylene-maleic anhydride resin, water-soluble resin such as carboxymethylcellulose and acrylic emulsion, vinyl acetate emulsion, vinylidene chloride emulsion,
Polyester emulsion, styrene-butadiene latex, acrylonitrile-butadiene latex and the like are used. Among these adhesives, a resin having a high degree of polymerization or a relatively hard resin having a minimum film forming temperature of 0 ° C. or more is desirable. In addition, a dye or a colored pigment may be added to the paint to adjust the color tone, or a fluorescent whitening agent may be added to improve the visual whiteness. A dispersant or an antifoaming agent may be added to facilitate the preparation of the paint.

The mixing ratio of the pigment and the adhesive in the paint is preferably from 95/5 to 30/70. If the blending ratio of the pigment exceeds 95%, the strength of the coating film is reduced, which may cause troubles such as peeling of the coating film in the manufacturing process. The cut may be blocked at the time of cutting, or the friction coefficient may be increased under a high humidity condition, which may cause running trouble. The coating amount is preferably ² to 30 g / m ² per one side. When the coating amount is less than 2 g / m ² , the recording quality and the pre-printing quality are not much different from the uncoated paper, and there is no effect of providing the coating layer. When the amount of coating exceeds 30 g / m ² , the paper has a weak point and the running property is deteriorated. As a coating method, a general coating method, for example, a coating method such as blade coating, air knife coating, roll coating, bar coating, slit die coating, or gravure coating can be used. The smoothing process is performed so that the Bekk smoothness measured according to JIS P 8119 of the coated surface is 20 to 2,000 seconds, but it is possible to use a super calender, a gloss calender, a thermopranisher, a machine calender, etc. it can.

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples. In the examples, parts represent parts by weight.

Example 1 Hardwood bleached kraft pulp (LBKP) 90 with a beating degree of 500 cc
Part, bleaching degree 460cc softwood bleached kraft pulp (NBKP) 1
A pulp slurry obtained by adding 5 parts of talc, 2 parts of starch, 1 part of a rosin sizing agent and 1 part of a sulfuric acid band to 0 parts is added.
Paper was made with a Yankee machine so that the basis weight measured according to JIS P 8124 was 65 g / m ^2, and used as base paper. Heavy calcium carbonate (whiten SSB (red), average particle size 1.2 on both sides of base paper)
5μm, 80 parts of Shiraishi calcium company, SBR latex (JSR0
662, solid content 48%, Nippon Synthetic Rubber Co., Ltd. 31 parts, oxidized starch (Ace A, Oji Cornstarch Co., Ltd.) 5 parts, lubricant (calcium stearate, Nopcoat C-104HS, solid content 55%, San Nopco Co., Ltd.) The coating amount after drying the paint consisting of 2 parts and 170 parts of water has the top surface / back surface = 10/10 g / m ²
After coating with an air knife coater, a smoothing treatment was performed with a super calender, and the Beck smoothness of the top surface measured according to JIS P8119 was set to 100 seconds to obtain transfer paper.

Example 2 60 parts of kaolinite clay (Ultra Gloss 90, average particle diameter 0.3 μm, manufactured by EMC) and calcined clay (Ansilex 93, average particle diameter of 0. 0) were placed on the top surface of the base paper prepared in Example 1.
15 parts, 6 μm, manufactured by EMC, 10 parts of titanium dioxide (Taipek A-220, average particle size: 0.1 μm, manufactured by Ishihara Sangyo), acrylic-vinyl acetate emulsion (Movinyl 630, solid content: 50)
%, Hoechst Gosei Co., Ltd.) 24 parts, polyvinyl alcohol (Poval 117, Kuraray Co., Ltd.) 3 parts, lubricant (calcium stearate, Nopcoat C-104HS, solid content 55%,
Sannopco) 2 parts, optical brightener (Kayahole Path Liquid, solid content 50%, Nippon Kayaku Co., Ltd.) 0.5 part, the coating amount after drying 220 parts of water is 5.0 g / m ² . Then, the coated paper was treated with a super calender so that the Beck smoothness of the coated surface was 150 seconds, to obtain a transfer paper.

Example 3 80 parts of LBKP having a beating degree of 550 cc, 20 parts of MBKP having a beating degree of 460 cc, 10 parts of calcium carbonate, 1 part of alkyl ketene dimer,
The basis weight of the pulp slurry with 2 parts of cationized starch added
Paper was made with a Yankee mansi so as to become 70 g / m ² and used as base paper. After applying the coating material used in Example 2 on both sides of the base paper using a bar coater so that the applied amount after drying becomes top surface / back surface = 10/10 g / m ² , the top surface is smoothed with a super calender. The processing was performed so that the degree became 180 seconds, and transfer paper was obtained.

Example 4 A pulp slurry obtained by adding 5 parts of talc, 2 parts of starch, 1 part of a rosin sizing agent and 1 part of a sulfuric acid band to 100 parts of LBKP having a beating degree of 450 cc and making a pulp slurry with a Yankee mansi so that the basis weight becomes 78 g / m ^2. And used as base paper. The paint used in Example 2 was applied on the top surface of the base paper so that the applied amount after drying was 20 g / m ^2, and the Bekk smoothness was 1,800 using a super calender.
The process was performed to obtain a transfer paper.

Comparative Example 1 Using the pulp slurry of Example 1, the basis weight was 65 g / m ^2.
Paper was made with a fourdrinier machine and dried with a multi-tube dryer to obtain a base paper. The coating material of Example 2 was applied to both sides of the base paper with an air knife coater so that the application amount after drying was 25/25 g / m ² = top surface / back surface to obtain transfer paper.
Since no calendar processing was performed, the smoothness of the top surface was 15 seconds.

Comparative Example 2 The transfer paper of Comparative Example 1 was subjected to a smoothing process using a super calender, and the Bekk smoothness of the top surface was set to 2,500 seconds.

Example 3 In Example 1, high quality paper (sunflower) was used as the base paper.
Transfer paper was obtained in the same manner as in Example 1 except that 64 g / m ² , manufactured by Oji Paper Co., Ltd.) was used.

The transfer papers of Examples 1 to 4 and Comparative Examples 1 to 3 were preliminarily printed by a four-color web offset printing machine, cut to A-4 size by a rotary cutter, and used for the test. Table 1 shows the test results of the Beck smoothness, the rate of change in humidity change, the curl after recording, the multicolor printing effect, and the running property of the transfer paper. Examples 1-4
Showed that after recording, the curl, the multicolor printing effect, and the running property were good. Comparative Example 1 was inferior in curl, multicolor printing effect and running property after recording, Comparative Example 2 was poor in curl and running property after recording, and Comparative Example 3 was poor in curl after recording.

Evaluation method Expansion / contraction ratio: Performed in accordance with J.TAPPI No.28 “Testing method for expansion / contraction ratio of paper and paperboard due to changes in humidity”. Based on 20 ℃ 65% RH,
The value obtained by adding the expansion ratio (%) at 20 ° C. and 33% RH and the expansion ratio (%) at 20 ° C. and 88% RH is evaluated as the humidity change expansion ratio.

Post-recording curl: Fuji Xerox laser printer
Using 9700KPS, record a test pattern with an image area ratio of 30%. When the paper after recording is left for 1 hour in an atmosphere of 20 ° C. and 65% RH with the recording surface up, the lifting height of the four corners of the recording paper is measured, and the average value is calculated.

:: 20 mm or less △: 21 to 50 mm ×: 51 mm or more Multi-color printing effect: After performing four-color offset printing, the glossiness and halftone dot reproducibility of the printed surface are comprehensively evaluated.

○: good △: poor △ ×: poor Travelability: Laser printer 9700KP from Fuji Xerox
Using S, a 500-sheet continuous recording test is performed to evaluate the running performance.

：: No trouble △: Trouble such as double feed, misfeed, jam, etc. 1 or 2 times ×: Trouble, such as double feed, misfeed, jam, etc. 3 or more [Effect of the Invention] According to the present invention, curl after recording is prevented. However, it is possible to provide a transfer paper for electrophotography having good pre-printing suitability, and to reproduce high-quality copy quality.

Claims (1)

(57) [Claims] (1) using a base paper made by a Yankee machine,
A coating layer is provided on at least one side, and JIS P8
An electronic device characterized in that the Beck smoothness measured according to 119 is 20 to 2000 seconds and the humidity change expansion and contraction ratio (lateral direction) measured according to J.TAPPI No.28 is 0.41% or less. Photographic transfer paper.