JP2006085005A - Electrophotographic coated paper - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrophotographic coated paper that can be used for printing by an electrophotographic printer, facsimile, copying machine, on-demand printer and has superior foldability and blister resistance. <P>SOLUTION: The electrophotographic coated paper has one or more coated layers consisting mainly of pigments formed on both sides of original paper, wherein an adhesive whose tensile fracture strength and tensile fracture expansion, based on JIS K7113, are 9.8×10<SP>6</SP>Pa or higher and 150% or higher respectively, when the adhesive is formed into a film is contained in the coating layers to the limit of M parts by mass, expressed by the Formula 0.0005×H≤M≤0.0015×H, based on 100 parts by mass pigment having an average specific surface area of H cm<SP>2</SP>/g. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an electrophotographic coated paper. More specifically, the present invention relates to an electrophotographic coated paper that can be printed by an electrophotographic printer, fax machine, copying machine, and on-demand printing machine and has excellent folding processability and blister resistance.

  Output by electrophotography is rapidly expanding due to the spread of printing from personal computers and on-demand printing.

  Up to now, high-quality output media has been preceded by the sublimation thermal transfer system, which has been used in the field of medical image processing, etc. It was a point.

  Recently, coupled with dramatic improvements in resolution and ink droplet miniaturization technology, the inkjet printing method is approaching photographic image quality, and several photo systems have been put on the market due to their low running costs. . However, although the inkjet method is inexpensive, the problem that the printing process takes time has not been solved.

  The electrophotographic method, which is relatively inexpensive and has a short print processing time, has attracted attention as a full-color output method that emphasizes visuals as well as the conventional text-centric output. Also in the electrophotographic system, the resolution improvement and the toner miniaturization technology are surely progressing, and due to its active development status, it is predicted that it will eventually approach the ink jet printing system and the offset printing system. In the electrophotographic system, an original latent image is formed on a semiconductor material, and a visible toner image is formed by toner. The toner image has a negative or positive charge. When the toner image is transferred onto an image receiving material having the opposite charge, the toner image is once transferred onto an intermediate transfer material and then further transferred onto the image receiving material. There is a case. The transfer of toner to the image receiving material is carried out by the electrostatic force of the oppositely charged toner and the image receiving material, but in actuality, the toner image on the semiconductor material or intermediate transfer body and the image receiving material are in close contact with each other by mechanical pressure. Also shows an important role. Finally, the toner is fixed on the image receiving material by the action of either heat or pressure, or both. When heat is used for fixing the toner, there is a concern that a paper provided with a coating layer on both sides may generate blisters due to evaporation of moisture in the base paper. In addition, when folding is performed immediately after printing, the dried coating layer may be destroyed and a problem called folding may occur.

In order to solve the problem of blisters, some proposals have been made to regulate the moisture content of the base paper, the strength in the Z-axis direction of the base paper, and the air permeability of the paper within a certain range of values. However, these countermeasures are known methods that are already widely used in rotary rotary printing paper with heat drying, and in order to improve the air permeability of the paper, the coating amount is reduced or is generally used. The technique of reducing the addition amount of the adhesive used in the process is taken. The former tends to cause a decrease in paper texture and printing quality, and the latter is concerned about the destruction of the coating layer when a strong stress is applied to the coating layer such as folding (for example, see Patent Documents 1 to 3).
Japanese Patent No. 2745431 Japanese Patent No. 2676291 JP 2003-202695 A

  The object of the present invention relates to a coated paper for electrophotography. More specifically, the present invention provides an electrophotographic coated paper that can be printed by an electrophotographic printer, a fax machine, a copying machine, and an on-demand printing machine and has excellent folding processability and blister resistance.

  As a result of intensive studies in view of the above, the present inventors have invented the electrophotographic coated paper of the present invention.

That is, the electrophotographic coated paper of the present invention is an electrophotographic coated paper in which a coating layer mainly composed of one or more pigments is provided on both sides of the base paper, and the tensile strength in accordance with JIS K7113 when formed into a film. An adhesive having a breaking strength of 9.8 × 10 ⁶ Pa or more and a tensile breaking elongation of 150% or more is expressed by the following formula with respect to 100 parts by mass of the pigment having an average specific surface area of Hcm ² / g. It is characterized by being contained in the coating layer limited to the indicated M parts by mass.
0.0005 × H ≦ M ≦ 0.0015 × H

  The electrophotographic coated paper of the present invention can be printed by electrophotographic printers, fax machines, copiers, and on-demand printers using dry and wet toners, and has excellent toner transferability. This is a type of electrophotographic coated paper.

  Hereinafter, the electrophotographic coated paper of the present invention will be described in detail.

In the present invention, the electrophotographic coated paper provided with a coating layer mainly composed of one or more pigments on both sides of the base paper has a tensile fracture strength of 9.8 × according to JIS K7113 when formed into a film. An adhesive having 10 ⁶ Pa or higher and a tensile elongation at break of 150% or higher is applied to 100 parts by mass of the pigment having an average specific surface area of Hcm ² / g, limited to M parts by mass represented by the following formula. By containing it in the construction layer, excellent folding processability and blister resistance can be simultaneously imparted.
0.0005 × H ≦ M ≦ 0.0015 × H

  When both the tensile fracture strength and the tensile fracture elongation, or one of them falls below the specified value, the coating layer is easily broken due to the stress applied to the coating layer during the folding process. Here, the adhesive film is formed by punching or pouring into a mold. The shape is preferably suitable for the mechanical properties of the film and the measuring machine. For example, the shape of No. 1 type test piece described in JIS K7113 can be mentioned.

  The adhesive effectively exhibits folding processability and blister resistance by adding the number of parts by mass specified by the given formula. By using the specific surface area of the pigment contained in the coating layer to define the mass part to be added, the blending part number can be properly defined when using any shape of pigment. When the number of blending parts is less than the value specified here, the suitability for folding is impaired, and when it exceeds, the blister resistance is inferior.

  In the present invention, the adhesive used for the coating layer is preferably one that exhibits adhesiveness to the pigment or base paper to be used, and is preferably a styrene butadiene copolymer latex; polyvinyl alcohol or a derivative thereof. In addition, starch derivatives such as oxidized starch, etherified starch, esterified starch and phosphate esterified starch; cellulose derivatives such as carboxymethyl cellulose and hydroxyethyl cellulose; casein, gelatin, soybean protein; polyvinylpyrrolidone, maleic anhydride resin, methyl Conjugated diene copolymer latex such as methacrylate-butadiene copolymer; Acrylic polymer latex such as polymer or copolymer of acrylic acid ester and methacrylic acid ester; Vinyl heavy polymer such as ethylene-vinyl acetate copolymer Polymer latexes, or functional group-modified polymer latexes with functional group-containing monomers such as carboxyl groups of these various polymers; or these various polymers cationized with a cationic group, cationic surfactants Heavy The body surface is cationized, the polymer is polymerized under cationic polyvinyl alcohol and the polyvinyl alcohol is distributed on the polymer surface, and the polymer is polymerized in a suspension dispersion of cationic colloidal particles. Aqueous adhesives such as thermosetting synthetic resins such as melamine resins and urea resins; Polymers or copolymer resins of acrylic acid esters and methacrylic acid esters such as polymethyl methacrylate; polyurethane resins, Synthetic resin adhesives such as saturated polyester resin, vinyl chloride-vinyl acetate copolymer, polyvinyl butyral, alkyd resin, and the like can be used, and these can be used alone or in combination.

  In the present invention, examples of the pigment used in the coating layer include calcium carbonate, magnesium carbonate, kaolin, delaminated kaolin, calcined kaolin, talc, calcium sulfate, barium sulfate, titanium dioxide, zinc oxide, zinc sulfide, and carbonate. Zinc, satin white, aluminum silicate, diatomaceous earth, calcium silicate, synthetic amorphous silica, colloidal silica, cation-modified colloidal silica, aluminum hydroxide, alumina, alumina hydrate, lithopone, zeolite, hydrohalosite, hydroxylation Examples thereof include white inorganic pigments such as magnesium and organic pigments. An organic pigment having a hollow shape is also preferably used.

As a coating device, a conventional size press, a gate roll size press, or a metade film transfer type size press, a rod coater, a bill blade, a short dwell coater, a blade coater, an air knife coater, a curtain coater, a spray coater, etc. are suitable. Can be used. In order to produce a texture suitable for coated paper, the coating amount is preferably 3 to 30 g / m ² in terms of dry mass.

  The pulp that can be used when producing the electrophotographic coated paper of the present invention includes NBKP, LBKP, NBSP, LBSP, GP, TMP, and the like, as well as non-wood pulp and waste paper pulp such as kenaf and bagasse. It is used alone or in combination as required. In order to increase the compression rate of coated paper, bulky mechanical pulp such as GP and TMP, semi-mechanical pulp, kenaf, bagasse non-wood pulp, lyocell, cellulose and other regenerated cellulosic fibers are all or partly Can also be used.

  In addition, as a raw material of the used paper pulp said by this invention, the white paper, ruled white, cream white, card | curd, special white, medium white, imitation shown by the used paper standard quality specification table | surface of a used paper reproduction promotion center , Fair white, Kent, white art, special upper limit, another upper limit, newspaper, magazine and so on. Specific examples include non-coating computer paper, which is information-related paper, printer paper such as thermal paper and pressure-sensitive paper, OA waste paper such as PPC paper, art paper, coated paper, finely coated paper, matte paper, etc. Non-coated paper such as coated paper or high-quality paper, color quality, notebook, notepaper, wrapping paper, fancy paper, medium-quality paper, newsprint, reprint paper, supermarket paper, imitation paper, pure white roll paper, milk carton For example, chemical pulp paper, high-yield pulp-containing paper, and the like are used, but there is no particular limitation on printing, copying, printing, or non-printing.

  In the present invention, examples of the internal filler that can be used include calcium carbonate, magnesium carbonate, kaolin, delaminated kaolin, calcined kaolin, talc, calcium sulfate, barium sulfate, titanium dioxide, zinc oxide, zinc sulfide, zinc carbonate, Satin white, aluminum silicate, diatomaceous earth, calcium silicate, synthetic amorphous silica, colloidal silica, colloidal silica modified with cation, aluminum hydroxide, alumina, alumina hydrate, lithopone, zeolite, hydrohalosite, magnesium hydroxide, etc. White inorganic pigments, organic pigments, and the like. An organic pigment having a hollow shape is also preferably used.

  Examples of the internally added sizing agent used in producing the electrophotographic coated paper of the present invention include rosin sizing agent in the case of acidic papermaking, alkyl ketene dimer and alkenyl anhydride in the case of neutral papermaking. Examples include succinic acid, neutral rosin sizing agent, and cationic styrene acrylic.

  In addition to the above, in the stock used when producing the electrophotographic coated paper of the present invention, a yield improver that has been conventionally used, and various kinds of materials, as long as the desired effects of the present invention are not impaired. An internal additive for papermaking such as anionic, nonionic, cationic or amphoteric drainage improvers, paper strength improvers and the like is appropriately selected and used as necessary. For example, various starches, and one or more of polyacrylamide, polyethyleneimine, polyamine, polyamide / polyamine, urea formalin resin, melamine formalin resin, vegetable gum, polyvinyl alcohol, latex, polyethylene oxide, polyamide resin are appropriately used. Used in combination.

  In the electrophotographic coated paper making method of the present invention, as the paper machine, a paper machine known in the paper industry such as a long paper machine, a twin wire paper machine, a combination paper machine, a round paper machine, and a Yankee paper machine is appropriately used. it can.

  On the surface of the base paper, oxidized starch, etherified starch, esterified starch, cationic starch, phosphate starch, phosphate starch, modified starch, modified starch, casein, polyvinyl alcohol and other binders, styrene / acrylic acid co-polymer Polymer, styrene / methacrylic acid copolymer, acrylonitrile / vinyl formal / acrylic acid ester copolymer, surface sizing agent such as styrene / maleic acid copolymer, dimensional stabilizer such as ethylene-urea resin, chlorination Of course, it is possible to apply inorganic conductive agents such as sodium and potassium chloride, organic conductive agents, surfactants, and dyes alone or in combination.

  After the base paper is coated, a super calender, soft nip calender, multi-stage soft nip calender, machine calender, rewet cast and the like can be used as appropriate in order to obtain smoothness and gloss.

  In addition, the finished electrophotographic coated paper has high gloss, embossed gloss, durability, weather resistance, water resistance, oil resistance, or chemical and physical properties intended to improve transferability and fixability of specific toners. , Optical, electrical and magnetic treatments can be applied.

Although there is no restriction | limiting in particular in the thickness of coated paper, Usually, about 40-350 g / m < ² > paper is used by basic weight. Preferably, the basis weight is 70 to 250 g / m ² .

  The electrophotographic coated paper in the present invention is not limited to use as a dry and wet electrophotographic coated paper for an output device such as a copy, printer, on-demand printer, fax machine, etc., but also an offset printing paper and a gravure printing paper. It can be used as a thermal transfer image receiving paper. It is also possible to apply a pressure-sensitive adhesive layer on the surface opposite to the surface for printing and apply it to labeling.

  Examples of the present invention will be described below, but the present invention is not limited to these examples. Further, “parts” and “%” shown in the examples indicate parts by mass and mass% unless otherwise specified.

(Example 1) to (Example 4) and (Comparative Example 1) to (Comparative Example 5)
<Preparation of base paper>
LBKP (Drainage 440 mlcsf) 70 parts NBKP (Drainage 490 mlcsf) 30 parts Light calcium carbonate (indicated by ash content in base paper) 9 parts Commercial cationized starch 0.7 parts Commercial cationic polyacrylamide yield improver 0.03 parts Pulp and internal chemicals were adjusted according to the above formulation, and 0.70 g / m ² of oxidized starch was adhered on both sides by a size press to produce a base paper having a basis weight of 130 g / m ² .

<Coating solution>
Heavy calcium carbonate (specific surface area Hcm ² / g) 100 parts Commercially available polyacrylic acid-based dispersant 0.1 part Adhesive (type, tensile breaking strength and tensile breaking elongation are listed in Table 1) M part carboxymethyl cellulose Thickener 0.1 parts Lubricant (calcium stearate) 0.5 parts Optical brightener (aminostilbenzene sulfonic acid derivative system) 0.5 parts Sodium hydroxide prepared to pH 9.6, coating solution It was. The specific surface area H of the heavy calcium carbonate, the type of adhesive, the tensile fracture strength, the tensile fracture elongation, and the blending amount M are shown in Table 1.

On the base paper, the coating liquid having the above composition was coated on both sides with a blade coating device so that the coating amount per side was 15.0 g / m ² and dried. Subsequently, the super calendar process was performed and the coated paper of Examples 1-4 and Comparative Examples 1-5 was obtained.

  About the coated paper of Examples 1-4 and Comparative Examples 1-5 produced by the above, folding workability and blister resistance were evaluated with the following measuring methods. The evaluation results are shown in Table 1. In addition, it shows below about the measuring method of the specific surface area H of a pigment, the tensile fracture strength of an adhesive agent, and tensile fracture elongation.

1) Folding suitability After printing by passing 50 A4 vertical white paper samples through Fuji Xerox's Docucolor 1256GA machine, the paper was immediately folded using an automatic folding device. No image is printed above the fold line. The state of occurrence of cracking was evaluated according to the following 6 levels.
“6”: no folding at all.
“5”: The total length of occurrence of cracks exceeds 0% of the length of the fold line and is 5% or less.
“4”: The total length of occurrence of cracks exceeds 5% of the length of the fold line and is 10% or less.
“3”: The total length of occurrence of cracking exceeds 10% of the length of the folding line and is 30% or less.
“2”: The total length of occurrence of cracks exceeds 30% of the length of the fold line and is 60% or less.
“1”: The total length of occurrence of cracking exceeds 60% of the length of the folding line.
The humidity control environment and measurement environment of the sample are 23 ° C. and 50 RH%.

2) Blister resistance manufactured by Fuji Xerox: A solid image of black, cyan, magenta, and yellow was printed by passing 50 A4 vertical blank paper samples through a document color 1256GA machine. The occurrence of blisters was evaluated according to the following 6 levels.
“6”: no occurrence of blisters.
“5”: Blisters having a length of 3 mm or less can be seen in 1 of 50 samples.
“4”: Blisters having a length of 3 mm or less are observed in 2 to 5 of 50 samples.
“3”: Blisters with a length of 3 mm or less are seen in more than 5 out of 50 samples,
Blisters exceeding 3 mm in length can be seen in 1 of 50 sheets.
“2”: Blisters exceeding 3 mm in length are seen in 2 to 5 of 50 sheets.
“1”: Blisters exceeding 3 mm in length are seen in more than 5 out of 50 sheets.
The humidity control environment and measurement environment of the sample are 30 ° C. and 80 RH%.

3) Specific surface area H of the pigment
Measured with a brane air permeation device. The humidity control environment and measurement environment of the sample are 23 ° C. and 50 RH%.

4) Tensile breaking strength and tensile breaking elongation of the adhesive.
The adhesive was made into a film and had a thickness of 200 μm, a length of 500 mm, and a width of 200 mm. The measurement uses an autograph device in accordance with JIS K7113, and the humidity control environment and measurement environment of the sample are 23 ° C. and 50 RH%.

Rating:
In Examples 1 to 4, the adhesive having the tensile fracture strength and the tensile fracture elongation in the specified range is blended with an appropriate amount in consideration of the specific surface area of the pigment, thereby having very excellent folding processability. Simultaneously exhibits blister resistance. On the other hand, Comparative Examples 1 to 3 use an adhesive that does not have an appropriate tensile fracture strength and tensile fracture elongation, and even if the addition amount is changed, the folding processability and the blister resistance are simultaneously improved to an excellent level. This is an example that cannot be designed. Further, Comparative Examples 4 and 5 use an adhesive having a tensile fracture strength and tensile fracture elongation within a specified range. However, the former is less suitable for the specific surface area of the pigment, and therefore has less cracking suitability. This is an inferior example, and the latter is an example in which the blister resistance is impaired because the amount of the adhesive is larger than specified.

  It can be used as electrophotographic coated paper in various printing areas.

Claims (1)

The electrophotographic coated paper provided with a coating layer mainly composed of one or more pigments on both sides of the base paper has a tensile fracture strength of 9.8 × 10 ⁶ Pa or more according to JIS K7113 when formed into a film. The adhesive having a tensile elongation at break of 150% or more is limited to M parts by mass represented by the following formula with respect to 100 parts by mass of the pigment having an average specific surface area of Hcm ² / g. A coated paper for electrophotography characterized by containing.
0.0005 × H ≦ M ≦ 0.0015 × H