JP2002006530A - Electrophotographic transfer paper - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide electrophotographic transfer paper having little curling after a transfer process or deterioration in its form, which is superior in traveling property and which has sufficient surface strength as electrophotographic transfer paper. SOLUTION: The electrophotographic transfer paper, containing calcium carbonate as filler contains a neutral rosin sizing agent as a sizing agent added internally, and the surface of the paper is coated with polyacrylamide by 0.3 to 0.7 g/m2. Air permeability of the electrophotographic transfer paper is <=20 seconds. Preferably, the polyacrylamide has a branched structure, 2×106 to 2.5×106 for the molecular weight.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a transfer paper for electrophotography. More specifically, the present invention relates to an electrophotographic transfer paper which is less curled in an electrophotographic copying machine, has excellent running properties, and has sufficient surface strength.

[0002]

2. Description of the Related Art An image forming method in an image forming apparatus using electrophotography or electrostatic printing generally includes a dry type developer (toner) in a transfer step of developing an electrostatic latent image formed on an image support. The electrophotographic transfer paper is superimposed on the image support. The electrophotographic transfer paper is charged from the electrophotographic transfer paper by corona discharge, and the developed toner image is transferred to the electrophotographic transfer paper. Is used. As the electrophotographic transfer paper used in this method, PPC-dedicated paper and general high-quality paper are used.

In recent years, the number of cases of performing multicolor transfer on electrophotographic transfer paper or performing transfer printing on both sides has been increasing. However, such a high-quality, high-value-added recording system is satisfied. For this purpose, JP-A-62-198875, JP-A-62-198876, JP-A-62-1
Coated paper as described in JP-A-98877, JP-A-5-241366 and the like is used.

As described above, in an image forming apparatus using electrophotography or electrostatic, in order to fix the toner transferred onto the electrophotographic transfer paper, the toner is passed between a heat roll and an elastic roll at about 180 ° C. . At that time, drying of the surface heated by the heat roll causes shrinkage of the fibers constituting the transfer paper for electrophotography. The shrinkage often causes wrinkles on the surface of the transfer paper for electrophotography, deteriorates the shape after transfer typified by curl, and significantly impairs the appearance after printing. Also, in double-sided printing and multicolor printing, wrinkles due to shrinkage hinder the fixation of the toner on the electrophotographic transfer paper in the second and subsequent printings, and the deterioration in shape after transfer is caused by poor running of the electrophotographic transfer paper. And cause adverse effects such as paper jams.

[0005]

SUMMARY OF THE INVENTION Based on the present situation,
An object of the present invention is to reduce the occurrence of curl after transfer in an electrophotographic copying machine, not to deteriorate the shape, to be excellent in running property,
An object of the present invention is to provide an electrophotographic transfer paper having a sufficient surface strength as an electrophotographic transfer paper.

[0006]

Means for Solving the Problems As a result of intensive studies, the present inventors have invented the electrophotographic transfer paper of the present invention.

That is, the electrophotographic transfer paper of the present invention contains calcium carbonate as a filler, a neutral rosin sizing agent as an internal sizing agent, and a polyacrylamide of 0.3 to 0.3 μm on the surface by a size press. The transfer paper for electrophotography is coated with 0.7 g / m ² , and the air permeability of the transfer paper for electrophotography is 20 seconds or less.

In the present invention, polyacrylamide having a branched structure having a molecular weight of 2,000,000 to 2.5,000,000 is preferable.

Further, in the present invention, preferably, waste paper pulp is blended.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Starch is generally applied by a size press, but requires a larger amount of application in terms of surface properties and strength than polyacrylamide. In an electrophotographic copying machine, when passing through a heat roll and an elastic roll, the transfer surface is wrinkled or curled due to the difference in the contraction rate of the starch and the contraction rate of the fibers constituting the transfer paper for electrophotography. , And often deteriorates the appearance after printing, and significantly deteriorates the appearance after printing. It is empirically known that such troubles increase in frequency as the amount of applied starch increases.

Further, by applying a large amount of starch, the air permeability of the transfer paper for electrophotography is deteriorated, and the distortion generated in a certain portion on the transfer paper for electrophotography is easily transmitted, which causes the deterioration of the shape after transfer. Becomes

As an index of air permeability, JIS 8117 is used.
The air permeability shown by is mentioned. When the air permeability exceeds 20 seconds, the air permeability deteriorates, and it becomes difficult to recover distortion generated in a certain portion on the electrophotographic transfer paper due to heat shrinkage by a heat roll, and the transfer of the electrophotographic transfer paper is difficult. Later shape deteriorates. Therefore, applying polyacrylamide as a starch substitute not only reduces the amount of application,
Compared with the application of starch, a porous paper layer structure is obtained, and deterioration of air permeability is prevented. As a result, deterioration of the shape of the transfer paper for electrophotography represented by curl after transfer can be prevented.

The polyacrylamide is a polymer of acrylamide, and has an effect of enhancing paper strength at the time of coating by forming a hydrogen bond by an amide group of acrylamide. For polyacrylamide, the molecular weight, the number and type of substituents can be easily changed.

The polyacrylamide used in the present invention preferably has a high molecular weight in order to enhance paper strength. Although the molecular weight is 2,000,000 to 2.5,000,000, if the molecular weight is too high, the viscosity becomes high and handling becomes difficult. Therefore, it is preferable to use a branched structure rather than a linear structure.

When the coating amount of polyacrylamide is 0.3 to 0.7 g / m ² , the same surface strength as that at the time of starch coating can be obtained, and a porous paper layer structure can be maintained. The air permeability of the electrophotographic transfer paper can be set to 20 seconds or less. As a result, a transfer paper for electrophotography which is less likely to curl in an electrophotographic copying machine and has excellent running properties is obtained.

However, when the coating amount of polyacrylamide exceeds 0.7 g / m ² , although the strength is increased, the air permeability deteriorates like starch, and
It is costly and not practical.

Conversely, if the coating amount of polyacrylamide is less than 0.3 g / m ² , even if the molecular weight is increased, a paper quality sufficiently satisfying the surface strength as an electrophotographic transfer paper can be obtained. I can't.

Making the air permeability of the electrophotographic transfer paper 20 seconds or less is necessary in order to quickly recover the distortion that has occurred at a certain location of the electrophotographic transfer paper. The fact that the air permeability is 20 seconds or less means that it has a porous paper layer structure and that heat transmission is small, and the occurrence of curling of an electrophotographic transfer paper in an electrophotographic copying machine. Less,
It means that it has excellent running performance.

The size press referred to in the present invention is:
A gate roll coater method using six rolls of a roll transfer type, an ink-jet size press method using two rolls, or a film transfer type may be used.

Other coating methods include a blade coater, a bar coater and the like, but these methods are not suitable for coating with a paper machine to form electrophotographic paper, based on the properties of the coating solution and the amount of coating.

The pulp used for the electrophotographic transfer paper of the present invention is not particularly limited as long as it is pulp used for general high-quality paper and coated base paper. Chemical pulp (NBKP,
LBKP, etc.), high yield pulp (GP, RGP, TM
Any of P) and deinked pulp (DIP) may be used, and a mixture of these may be used.

The deinked pulp used in the base paper of the present invention is obtained by drying the fibers many times during the production process.
This is advantageous for the purpose of increasing the air permeability. The addition ratio is preferably high from the viewpoint of air permeability, but on the other hand, the stiffness of the base paper and the reduction in various strengths are accompanied, so that the handling properties of the obtained electrophotographic transfer paper and the color laser copy (CLC) ) Or a color laser beam printer (CLBP), which impairs the paper-passing suitability, so that the amount is usually preferably 30 to 50% by weight of the total pulp amount.

The raw materials of the deinked pulp referred to in the present invention include: top white, ruled white, cream white, card, and the like shown in the waste paper standard quality standard table of the Waste Paper Recycling Promotion Center.
Special white, medium white, imitation, fair white, Kent, white art, special top cut,
Another example is newspaper, magazine, etc. Further specific examples include uncoated computer paper, which is information-related paper,
Printer paper such as thermal paper, pressure-sensitive paper (registered trademark), OA waste paper such as PPC paper, art paper, coated paper,
Coated paper such as lightly coated paper or matte paper, or high-quality paper, high-quality paper, notebooks, stationery, wrapping paper, fancy paper, medium-quality paper, newsprint, paper-change, super-hanging paper, imitation paper, pure white roll paper Waste paper such as uncoated paper such as milk carton and paperboard, and chemical pulp paper and high-yield pulp-containing paper, etc., which are particularly limited regardless of printing, copying, printing and non-printing is not.

The transfer paper for electrophotography of the present invention uses a neutral rosin sizing agent as an internal sizing agent and calcium carbonate as a filler. The main goal of neutralizing high-quality paper is to use low-cost calcium carbonate as a filler to reduce production costs, and to gain other benefits such as energy saving in paper production, improvement in productivity, prevention of equipment fouling, and purification of wastewater. It is aimed at. Examples of the neutral sizing agent include alkyl ketene dimer and alkenyl succinic anhydride.
It is preferable to use a neutral rosin sizing agent from the viewpoint of preventing double feeding due to slippage of the electrophotographic transfer paper and handling.

In addition, a sulfate band, a cationic starch, and a retention agent are appropriately used as internal additives.

In order to prevent image distortion and maintain an appropriate image resolution, a conductive agent such as potassium chloride, sodium chloride, a styrene-maleic acid polymer, or a quaternary ammonium salt is used in a size press of a paper machine. It is common practice to apply a surface to adjust the surface electric resistance of the electrophotographic transfer paper, and the present invention can be applied.

[0027]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, which, of course, are not intended to limit the present invention. All parts and percentages are by weight.

Example 1 Freeness 450 ml c. s. 100 parts of bleached hardwood bleached pulp beaten to f. Precipitable calcium carbonate (TP121: manufactured by Okutama Industry Co., Ltd.) 5% sulfuric acid band as paper content 1.4 parts Neutral rosin sizing agent (CC167: manufactured by Japan PMC) ) 0.36 parts Cationic starch (CATO3210: manufactured by Nippon Nc Co.) 1.0 part Slurry containing 0.02 parts of retention agent (HC-880: manufactured by Alite Coroit Co., Ltd.)
in in a Fourdrinier paper machine and passed through a size press and machine calender, basis weight 64 g / m ² , density 0.75 g / c
An electrophotographic transfer paper having m ³ and a water content of 5% was obtained. The size press method was performed by an ink-jet size press method using two rolls. As the size press chemical, a polyacrylamide surface paper strengthening agent (G3000: manufactured by Harima Chemicals, Inc.) and a styrene-maleic acid copolymer (Polymalon-482S: manufactured by Arakawa Chemical Co., Ltd.) at a ratio of 2: 0.2. The mixture was applied at a coating weight of 0.4 g / m ² on paper. The polyacrylamide surface paper strengthening agent used here has a branched structure having a molecular weight of about 2.3 million.

Example 2 The pulp and the chemicals used in Example 1 were added, and the amount of the chemical for the size press used in Example 1 was adjusted to 0.33 g / m ^2.
The transfer paper for electrophotography was obtained with the same formulation.

Example 3 The pulp and the chemicals used in Example 1 were added, and the coating amount of the chemicals for size press in Example 1 was set to 0.6 g / m ^2, and electrophotographic transfer paper was produced under the same formulation. I got

Example 4 The pulp and the chemicals used in Example 1 were added, and the coating amount of the chemicals for size press in Example 1 was 0.77 g / m ^2.
The transfer paper for electrophotography was obtained with the same formulation.

Example 5 A polyacrylamide surface strengthening agent having a molecular weight of about 20
Except for using the one having a branched structure of 100,000, the pulp and chemicals used in Example 1 were added, and an electrophotographic transfer paper was obtained with the same formulation.

Example 6 A polyacrylamide-based surface strength agent had a molecular weight of about 30.
Except for using the one having a branched structure of 100,000, the pulp and chemicals used in Example 1 were added, and an electrophotographic transfer paper was obtained with the same formulation.

Example 7 Hardwood bleached pulp 100 of the pulp used in Example 1
Parts were replaced with 30 parts, and the remaining 30 parts were replaced with 30 parts of the imitation deinked pulp.

Comparative Example 1 The pulp and chemicals used in Example 1 were added, and the coating amount of the chemicals for size press in Example 1 was adjusted to 1.0 g / m ^2, and electrophotographic transfer paper was manufactured under the same formulation. I got

Comparative Example 2 The pulp and chemicals used in Example 1 were added, and the coating amount of the chemicals for size pressing in Example 1 was 0.88 g / m ^2.
The transfer paper for electrophotography was obtained with the same formulation.

Comparative Example 3 The pulp and chemicals used in Example 1 were added, and the coating amount of the chemicals for size press in Example 1 was set to 0.2 g / m ^2, and the transfer paper for electrophotography was manufactured under the same formulation. I got

Comparative Example 4 The pulp and chemicals used in Example 1 were added, and the coating amount of the chemicals for size press in Example 1 was 0.275 g /
m ^2, and a transfer paper for electrophotography was obtained with the same formulation.

Comparative Example 5 The pulp and chemicals used in Example 1 were added, and the oxidizing starch (MS-3800:
Nippon Food Processing Co., Ltd.) and styrene-maleic acid copolymer (Polymalon-482S: Arakawa Chemical Co., Ltd.) at 6: 0.2
The mixture was applied at a rate of 1.4 g / paper.
m ² to obtain transfer paper for electrophotography.

(Evaluation Method of Transfer Paper) 1) Air Permeability The air permeability conformed to the method of JIS 8117. 2) Transferred Karl Canon electrophotographic copying machine (model: NP625)
In step 0), the A4 size electrophotographic transfer paper was copied, and two levels were performed, one in which the felt surface of the paper was in contact with the heat roll and the other in which the wire surface of the paper was in contact with the heat roll. Judgment measures the height of the four corners of A4 size after passing 100 sheets,
If it was 20 mm or less, it was acceptable, and if any one place exceeded 20 mm, it was unacceptable. 3) Paper jam Canon electrophotographic copier (model: NP625)
In 0), double-sided copying of 50 sheets of A4 size electrophotographic transfer paper is possible if there is no paper jam. If even one sheet had a paper jam, it was judged to be impossible. 4) Wrinkle generation rate An electrophotographic copying machine manufactured by Canon (model: NP625)
In 0), 50 sheets of A4 size electrophotographic transfer paper were subjected to double-sided copying, and it was determined that no wrinkles were found, and that one or more sheets were not wrinkled. 5) Surface Strength Solid printing was performed using an RI printing machine, and the degree of surface peeling was visually evaluated in five stages. A sample having a low degree of peeling was set to 5, a sample having a high degree of peeling was set to 1, and if it was 3 or less, it was determined that the surface strength of the transfer paper for electrophotography was insufficient.

The air permeability of the obtained electrophotographic transfer paper and the results of evaluation by an electrophotographic copying machine are as shown in Table 1.

[0042]

[Table 1]

From Table 1 above, the electrophotographic transfer paper obtained in Examples 1 to 7 was coated with 0.3 to 0.7 g / m ² of polyacrylamide as a starch substitute on the surface by a size press. It can be seen that by setting the air permeability to 20 seconds or less, the appearance and workability such as curl after printing with an electrophotographic copying machine are excellent. On the other hand, the transfer paper for electrophotography according to Comparative Examples 1 and 2 has too much adhesion amount and the air permeability exceeds 20 seconds, the curl judgment and the generation rate of wrinkles are deteriorated even when polyacrylamide is used, In addition, it can be seen that the transfer paper for electrophotography according to Comparative Examples 3 and 4 has too small an amount of adhesion, resulting in a decrease in surface strength. Further, the transfer paper for electrophotography according to Comparative Example 5 employs a conventional starch-based size press solution, but also shows that the characteristics after printing deteriorate due to the deterioration of the air permeability.

[0044]

According to the transfer paper for electrophotography of the present invention, a specific amount of polyacrylamide is applied to the surface of a base paper by a size press and the air permeability thereof is set to 20 seconds or less, so that the occurrence of curling is reduced. It has excellent running properties and sufficient surface strength.

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Claims (3)

[Claims] 1. An electrophotographic transfer paper containing calcium carbonate as a filler and a neutral rosin sizing agent as an internal sizing agent. m ² applied will be,
An electrophotographic transfer paper, wherein the air permeability of the electrophotographic transfer paper is 20 seconds or less. 2. The electrophotographic transfer paper according to claim 1, wherein the polyacrylamide applied by a size press has a branched structure having a molecular weight of 2,000,000 to 2.5,000,000. 3. The transfer paper for electrophotography according to claim 1, wherein waste paper pulp is blended into the base paper.