JP2013160849A - Electrophotographic recording material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrophotographic recording material that prevents the occurrence of blanket ghost, and has good conveyability and high toner fixing strength.SOLUTION: An electrophotographic recording material includes a toner reception layer on a support; and the toner reception layer contains at least a pigment having a value of a penetration degree testing regulated in JIS K2207 of 3 or more.

Description

  The present invention relates to an electrophotographic recording material. More specifically, the present invention relates to an electrophotographic recording material which has no blanket ghost and has good transportability and high toner fixing strength in an electrophotographic system and further in a wet electrophotographic system.

  Electrophotographic recording is applied to various fields such as copying machines, terminal print output, facsimile, and small number of copies. The progress of the output device is also remarkable, the printing speed is improved, not to mention full color, it achieves high definition by improving the toner, the color reproducibility is greatly improved, and it is used for various applications from document output to photo output It has come to be.

  Among such electrophotographic systems, the dry electrophotographic system is a system typified by a copying machine and the like, and a solid powder toner made of a pigment and a synthetic resin is used as a toner for forming an image. In the image forming method, toner is adsorbed to an electrostatic image on a photoreceptor roll generated by corona charging, the toner is transferred to a recording material, and the transferred recording material is heated by a fixing roll to fix the toner. It is a method to do. In this method, there is a limit to the miniaturization of toner, and it is difficult to obtain high resolution. In addition, there is a problem in that the gloss of the toner fixing portion of the image line portion becomes high, and a gloss difference is generated from that of the non-image line portion, resulting in an unnatural depiction.

  On the other hand, in the wet electrophotographic method, since the toner is dispersed in the liquid, the scattering of the powder is not a problem, and the toner can be reduced to 1/10 or less compared to the dry electrophotographic method. This is a method suitable for photographic output without causing a problem of weather resistance since the dots forming the portion can be made fine, and in addition, since a pigment can be used as a coloring material, there is no difference in gloss of the image.

  The wet electrophotographic image forming method proceeds by the toner adsorbing to the electrostatic image on the photoreceptor roll and transferring the toner to the blanket roll using potential repulsion in the same manner as the dry electrophotographic method. . The surface of the blanket roll is made of a material with low interface free energy such as silicon rubber. The toner is transferred from the blanket roll to the recording material, and the blanket roll is heated, so that the toner becomes molten and becomes the recording material. This is an image forming method for fixing. In such a system, the blanket roll, the recording material, or the wet toner is required to have an ability of transferring the wet toner from the blanket roll to the recording material, and so-called toner transferability is important.

  Since high smoothness is required for photographic output, it is preferred that the recording material is a resin-coated base paper or a polymer film as a base material. However, resin-coated paper and polymer film are not sufficiently fixed with toner, and a configuration in which a toner receiving layer is provided has been proposed. As such a configuration, an electrophotographic recording material has been proposed in which a specific polypropylene resin layer is provided on both sides of a base paper and a toner receiving layer is provided thereon (see, for example, Patent Document 1). In addition, an electrophotographic recording material has been proposed in which a resin layer having a glass transition point defined on a polymer film, a low-resistance treatment agent, and organic polymer fine particles are used as a receiving layer (see, for example, Patent Document 2). However, the toner receiving layer as described in Patent Document 1 or Patent Document 2 is a blanket ghost in which an unnecessary image is printed on the non-printing portion of the print in terms of wet electrophotographic toner fixing strength. The problem is still insufficient.

  As a toner image-receiving layer, an electrophotographic image-receiving sheet containing organic particles having a glass transition temperature or a melting point equal to or lower than a temperature at which an image is fixed to the image-receiving layer has been proposed (for example, see Patent Document 3). Although such an electrophotographic image-receiving sheet is improved in transportability, it is insufficient in terms of generating blanket ghosts, and the toner fixing strength is quite insufficient.

  An electrophotographic film is proposed in which an image receiving layer containing a matting agent and a binder is provided on at least one surface of a transparent film, and the matting agent is composed of fine particles having at least two different shapes (for example, (See Patent Document 4). Also proposed is an image-receiving sheet having an image-receiving layer on a transparent substrate, wherein the resin of the image-receiving layer has a protrusion having a softening point lower than that of the toner and a material having a softening point higher than that of the toner. (For example, refer to Patent Document 5). However, the receiving layer as described in Patent Document 4 or Patent Document 5 is improved in terms of transportability, but is insufficient in terms of generating blanket ghosts, and the toner fixing strength is not sufficient. is there.

JP 2002-351121 A JP 2007-65517 A JP 2002-258507 A JP-A-6-19179 JP-A-9-160277

  In the wet electrophotographic image forming method, the wet toner is attracted to the electrostatic image on the photoreceptor roll, transferred to the blanket roll using the potential repulsion, and further transferred from the blanket roll to the recording material. Since the surface of the blanket roll is made of a material having low interface free energy such as silicon rubber, all the wet toner on the blanket is transferred to the recording material. However, depending on the type of recording material used, when the print image is changed, a phenomenon in which the old image is printed lightly on the new image may be seen. This phenomenon is called blanket ghost. In recent years, with the development of printing technology, high-speed printing has become possible. As a result of intensive studies by the present inventor, the blanket ghost is a part of the blanket that is originally damaged by the transfer material remaining on the blanket. It was found that this was a phenomenon in which the previous image was printed lightly. Further, it has been found that the inclusion of a matting agent and the provision of a protruding portion in the toner image-receiving layer of the recording material can easily cause scratches on the surface of the blanket roll, although improving the transportability.

  An object of the present invention is to provide an electrophotographic recording material which is free from blanket ghosts and has good transportability and high toner fixing strength.

  The above object of the present invention is that the electrophotographic recording material having a toner receiving layer provided on a support contains at least a pigment having a penetration test value of 3 or more defined in JIS K2207 in the toner receiving layer. Is basically achieved by Preferably, the addition ratio of the pigment in the toner receiving layer is 1 to 40% by mass with respect to the total solid content of the toner receiving layer. Preferably, the toner receiving layer contains an ionomer resin as a binder.

  By carrying out the present invention, an excellent electrophotographic recording material having no blanket ghost, good transportability and high toner fixing strength can be obtained.

  The electrophotographic recording material of the present invention does not damage the blanket because the toner receiving layer contains a pigment having a penetration test value of 3 or more as defined in JIS K2207. There is no problem. In addition, the electrophotographic recording material of the present invention can reduce friction between recording materials and a conveyance roll inside the printing machine by adding a pigment, and there are problems such as double feeding and paper jam during conveyance. It does not occur. In the electrophotographic recording material of the present invention, toner fixing strength is further improved when the toner receiving layer contains an ionomer resin as a binder.

  The toner receiving layer of the present invention contains at least a pigment having a penetration test value defined by JIS K2207 of 3 or more. When a pigment having a penetration test value smaller than 3 is added, a blanket ghost is generated. An organic pigment or an inorganic pigment can be used as the pigment. Organic pigments are particularly preferred because of the ease of obtaining pigments with a penetration test value of 3 or more. Examples of organic pigments include polyethylene resins, acrylic resins, polyolefin resins, polystyrene resins, and ethylene-acrylic acid copolymers. Examples include resins, styrene-acrylic copolymer resins, styrene-methacrylic acid copolymer resins, styrene-butadiene copolymer resins, urea resins, melamine resins, starches, and silicone resins. The organic pigment is already commercially available, for example, as Chemipearl W type manufactured by Mitsui Chemicals, Inc., and can be used in the toner receiving layer of the present invention.

  The addition ratio of the pigment in the toner receiving layer of the present invention is preferably 1 to 40% by mass with respect to the total solid content mass of the toner receiving layer. In such a range, the toner fixing strength and transportability are better. When the addition ratio of the pigment is lower than 1% by mass, the transportability may be reduced, and when it is higher than 40% by mass, the toner fixing strength may be reduced.

  In the present invention, the toner receiving layer preferably contains an ionomer resin as a binder. By containing an ionomer resin, the toner fixing strength becomes better. The ionomer resin in the toner receiving layer of the present invention is a copolymer of a monomer such as ethylene and an unsaturated carboxylic acid such as acrylic acid, methacrylic acid or maleic acid, wherein the carboxylic acid moiety is sodium, magnesium, It is a synthetic resin that uses an agglomeration force caused by metal ions such as zinc and lithium, ammonium ions, etc., and interpolymer bonds the copolymer to form an aggregate. As the ionomer resin, for example, S type of Chemipearl manufactured by Mitsui Chemicals, Inc., Xyxen manufactured by Sumitomo Seika Co., Ltd., ionomer dispersion manufactured by Maruyoshi Chemical Co., Ltd., etc. are already commercially available. Can be used for receiving layer.

  In addition, various inorganic acids, organic acids, pH adjusters, image preservatives, colorants, thickeners, surfactants, and the like can be appropriately added to the toner receiving layer.

  The thickness of the toner receiving layer in the present invention is preferably 0.05 to 10 μm.

  As the support in the present invention, resin-coated paper, polymer film, high-quality paper, medium-quality paper, reprinted paper, craft paper, coated paper for printing, and the like can be used, and resin-coated paper and polymer film are particularly preferable. . The thickness of the support is preferably 50 to 300 μm.

  As the method for forming the toner receiving layer in the present invention, a direct gravure coater, an offset gravure coater, a micro gravure coater, a reverse gravure coater, a reverse roll coater, a bar coater such as a wire bar coater or an extrusion bar coater, a curtain coater, and an air knife coater. And a method of applying a coating solution for a toner receiving layer on a support by using a comma coater, a die coater, a lip coater, a blade coater, a slide hopper coater, or a combination thereof. As a drying device for the applied coating liquid, various drying methods such as straight tunnel dryers, arch dryers, air loop dryers, hot air dryers such as sine curve air float dryers, dryers using infrared rays, heating dryers, microwaves, etc. An apparatus can be mentioned.

  In the following, the present invention will be described in detail by way of examples. Needless to say, the present invention is not limited to the examples. Unless otherwise specified,% is in terms of solid content or mass% of a substantially active ingredient. Unless otherwise specified, parts are in terms of solid content or parts by mass of the substantially active ingredient.

<Example 1>
In preparing the toner receiving layer coating solution, ionomer resin (manufactured by Mitsui Chemicals, Chemipearl S111, concentration 27%): 99.9 parts as a binder, and polyethylene particles (manufactured by Mitsui Chemicals, Chemipearl W100) as pigments. , concentration 40%): 0.1 parts were mixed by stirring, which was a toner-receiving layer coating solution, the paper resin-coated basis weight 170 g / m ² was melt laminated to both surfaces of woodfree paper polypropylene resin, per side The recording material of Example 1 was obtained by applying to both sides with a reverse gravure coater so that the coating amount was 1.5 g / m ² and drying with a hot air dryer. The addition ratio of the pigment is 0.1% with respect to the total solid content mass of the toner receiving layer.

<Examples 2 to 9, Comparative Examples 1 and 2>
A recording material of each example or each comparative example was obtained in the same manner as in Example 1 except that the binders and pigments shown in Table 1 were used and added in the ratios shown in Table 1.

(Evaluation of toner fixing strength)
Using a HP Indigo 7000 Digital Press as a wet electrophotographic printer, printing was performed on a recording material in a standard 4-color, 8-bit mode, 1219 dpi. Adhere cellophane tape to a solid print section of black, cyan, magenta, yellow, and 100% color density (color optical density), remove the tape, observe the toner attached to the tape, and evaluate the toner fixing strength. did. In the present invention, if the evaluation is で あ れ ば, ○, or Δ, there is no practical problem.
A: The toner does not adhere to the tape, and the toner fixing strength is excellent.
○: Slight toner adhesion is observed on the tape, but the toner fixing strength is good.
Δ: Toner adheres to the tape, and the toner fixing strength is at a practical limit.
X: Most of the toner adheres to the tape, and the toner fixing strength is not practical.

(Evaluation of blanket ghost)
Using a HP Indigo 7000 Digital Press as a wet electrophotographic printer, printing was performed on a recording material in a standard 4-color, 8-bit mode, 1219 dpi. Using two types of evaluation images, the expression state of the ghost image in the non-image part after changing the evaluation image was observed to evaluate the blanket ghost. In the present invention, if the evaluation is ○ or Δ, there is no practical problem.
○: A blanket ghost is not recognized in the non-image area, which is good.
Δ: Slight dirt is seen in the non-image area, but it is at a practical limit.
X: Blanket ghost is recognized in the non-image area, which is a practically unusable level.

(Evaluation of transportability)
[Evaluation of double feed]
As a wet electrophotographic printer, HP Indigo 7000 Digital Press was used, 100 sheets of A3 paper were continuously printed, and the presence or absence of double feed was confirmed. In the present invention, if the evaluation is ○ or Δ, there is no practical problem.
○: All 100 sheets were printed on both sides without occurrence of double feed.
(Triangle | delta): Although double feeding generate | occur | produced once in 100 sheets, it is a practical limit level.
X: Double feeding occurs 100 times or more in 100 sheets, which is a practically unusable level.

[Evaluation of paper jam]
As a wet electrophotographic printer, HP Indigo 7000 Digital Press was used, and 100 sheets of A3 paper were continuously printed to check for the occurrence of paper jams. In the present invention, if the evaluation is ○ or Δ, there is no practical problem.
○: All 100 sheets were printed on both sides with no paper jam.
(Triangle | delta): Although paper jam generate | occur | produced once in 100 sheets, it is the level of a practical limit.
X: A paper jam occurs twice or more in 100 sheets, which is a practically unusable level.

  The evaluation results of each example and each comparative example are shown in Table 1.

  From Examples 1 to 9, the electrophotographic recording material according to the present invention containing a pigment having a penetration test value of 3 or more as defined in JIS K2207 is excellent in toner fixing strength and generates blanket ghosts. It can be seen that the transportability is good. Comparative Example 1 and Comparative Example 2 that do not correspond to the present invention cannot obtain such an effect of the present invention. From the comparison of Examples 1 to 6, it can be seen that the pigment addition ratio is preferably 1 to 40% by mass with respect to the total solid content of the toner receiving layer in terms of transportability and toner fixing strength. From the comparison between Example 2 and Example 9 and the comparison between Example 4 and Example 8, it can be seen that an ionomer resin is preferable as a binder in terms of toner fixing strength.

Claims (3)

  An electrophotographic recording material having a toner-receiving layer provided on a support, wherein the toner-receiving layer contains at least a pigment having a penetration test value defined by JIS K2207 of 3 or more. .   2. The electrophotographic recording material according to claim 1, wherein in the toner receiving layer, the pigment addition ratio is 1 to 40% by mass relative to the total solid content mass of the toner receiving layer.   The electrophotographic recording material according to claim 1, wherein the toner receiving layer contains an ionomer resin as a binder.