JP2005301186A - Electrophotographic recording sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrophotographic recording sheet which has a satisfactory toner fixing property, does not exhibit notable yellowing when subjected to a prolonged storage or heat treatment, produces excellent recording images, and facilitates waste paper recovery and recycling. <P>SOLUTION: The electrophotographic recording sheet has a layer, on at least one surface of sheet type base material, which contains at least one resin selected from amino group-containing acrylic-based resins, rosin ester-based resins, styrene/acrylic-based resins, styrene/maleic-based resins, olefin/acrylic-based resins, and olefin/maleic acid-based resins. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an electrophotographic recording sheet that is used in a wet electrophotographic system, has good toner fixing properties, does not significantly yellow even when stored for a long period of time, or is heat-treated, and can be easily recycled.

Conventionally, as a method of copying a large amount of information such as characters and images, there are printing methods such as offset and gravure. These printing methods are excellent as a method for copying a large amount of the same information, but are inappropriate when copying various information little by little.
Therefore, electronic printing methods typified by ink jet printers and copiers have become mainstream as methods for performing a small amount of printing. Electronic printing methods include thermal methods, electrophotographic methods, inkjet methods, thermal transfer methods, and the like, and printers and printing machines using these methods have been developed. In particular, when copying at low cost, an ink jet method and an electrophotographic method are suitable. However, the ink jet method uses a dye ink using a dye as a coloring material, so that it is inferior in terms of light resistance and water resistance, and has a disadvantage that special paper provided with an ink receiving layer must be used. In consideration of satisfying conditions such as high image quality, high speed, and low cost, the electrophotographic method is most preferable.

  There are two types of electrophotographic methods: dry and wet. The dry electrophotographic system is a system typified by office copying machines and the like, and uses a solid powder toner composed of a pigment and a synthetic resin as a toner for forming an image. The image quality is formed by a method in which toner is attracted to an electrostatic latent image generated by corona charging, the toner is transferred to a recording sheet, and heat-pressed. In this dry electrophotographic system, the finer the toner, the easier it is to scatter to the surrounding environment, and if this is inhaled, there is a health problem, so there is a limit to miniaturizing the solid powder toner. There is a drawback that high resolution is difficult to obtain. Also, if the thickness of the transfer object is not uniform, the charge density of the transfer object surface due to corona discharge will vary, resulting in an undesirable image called “fogging” in the non-image area, or a somewhat high temperature. There are many problems such as melting and solidification.

  On the other hand, the wet electrophotographic method using liquid toner can obtain a sharper image because the toner can be made finer than the dry electrophotographic method, and the pigment can be used as a coloring material, so it is light resistant. There is no problem of water resistance or water resistance.

  Wet electrophotographic methods have been studied for a long time, and some have been put to practical use. However, there are problems in recording properties, solvent odor, transferability to substrates, etc., and they have not been generalized. . However, recently, a product name “E-PRINT” manufactured by INDIGO has been provided as an apparatus in which the above-mentioned various drawbacks are improved.

  As recording materials used in the wet electrophotographic system, plastic films, plastic sheets, pigment-coated paper, metals, and the like are used, and various improvements have been made. When the recording material is a plastic film, a plastic sheet, or the like, liquid toner does not penetrate into the recording material, and an excess solvent (toner dispersion medium) remains on the surface of the recording material. Therefore, in order to fix the toner to the film or the like, it is necessary to remove the excess solvent, and a process of heating the film or the like at a high temperature is required. Further, even after the solvent is removed by heating, in order to improve the adhesion between the film and the toner, it is necessary to reheat the toner and completely melt the toner resin on the film and the like. Therefore, at present, usable plastic films and plastic sheets are limited to some plastic films and sheets such as a polyester resin film having a relatively high heat resistance.

  The use of pigment-coated paper is also being considered, but the paper thickness is increased, and as with plastic films and plastic sheets, toner permeability, toner transfer and adhesion are low, and high-speed printing is possible. In this case, the printed surface after printing is rubbed and blurred, or the toner is peeled off when rubbed with an eraser, or the printed part is peeled off with cellophane tape. There is also a problem that there are many troubles of paper supply / discharge during continuous printing.

  In order to cope with these problems, it has been proposed to subject the recording material to polyethyleneimine treatment [JP-A-8-286410 (Patent Document 1), JP-A-9-179329 (Patent Document 2), JP-A-11-119460 (Patent Document 3)]. The use of polyethyleneimine can improve the toner fixability, but the recording material is yellowed due to the passage of days after heating and heating, and it is a strong cation. There was a problem that polyethyleneimine itself was expensive.

  On the other hand, there are examples of research to improve toner fixing properties, such as using a resin that dissolves the resin constituting the toner at a low temperature, and producing a toner using a thermosetting resin. The toner produced in this manner is often inferior in stability over time or in basic physical properties for electrophotography, and a practical level has not been realized.

JP-A-8-286410 JP 9-179329 A JP 11-119460 A

  An object of the present invention is to provide an electrophotographic recording medium that has good toner fixing properties, does not significantly yellow even after long-term storage or heat treatment, and provides an excellent recorded image. To provide a sheet.

  As a result of intensive studies in view of the above problems, the present inventor has found that an amino group-containing acrylic resin, rosin ester resin, styrene / acrylic resin, styrene / maleic resin, olefin / acrylic resin, and olefin・ Maleic resin (hereinafter sometimes referred to as “toner fixing improver”) exhibits an excellent liquid toner fixing improvement effect comparable to or exceeding that of polyethyleneimine, and is prominent even after long-term storage and heat treatment. It was found that no yellowing was observed.

  In the electrophotographic recording sheet according to the present invention, at least one surface of a sheet-like base material is subjected to toner receptive treatment, and the toner receptive treatment includes amino group-containing acrylic resin, rosin ester resin, styrene. -It was made by the processing agent containing at least 1 sort (s) chosen from acrylic resin, styrene / maleic acid resin, olefin / acrylic resin, and olefin / maleic acid resin. It is preferable to further contain a styrene / butadiene copolymer in the treatment agent.

  In a preferred embodiment, the treating agent contains at least an amino group-containing acrylic resin.

  In another preferred embodiment, the treatment agent contains at least a rosin ester resin. In this case, it is preferable to use rosin ester resin in combination with at least one selected from styrene / acrylic resin, styrene / maleic resin, olefin / acrylic resin and olefin / maleic resin.

  In another aspect, the electrophotographic recording sheet according to the present invention has a sheet-like substrate and a toner receiving layer on at least one surface thereof, and the amino group-containing acrylic resin in the toner receiving layer. And rosin ester resin, styrene / acrylic resin, styrene / maleic acid resin, olefin / acrylic resin, and olefin / maleic acid resin. It is preferable that a styrene / butadiene copolymer is further contained in the toner receiving layer.

  In a preferred embodiment, the toner receiving layer contains at least an amino group-containing acrylic resin.

  In another preferred embodiment, the toner receiving layer contains at least a rosin ester resin. In this case, it is preferable to use rosin ester resin in combination with at least one selected from styrene / acrylic resin, styrene / maleic resin, olefin / acrylic resin and olefin / maleic resin.

In a preferred embodiment, the electrophotographic recording sheet comprises at least one toner fixing improver of 0.1 g / m ² or more, preferably 0.8 g / m ² or less, preferably on at least one surface of the sheet-like substrate. The coating amount is 0.3 g / m ² or more and 0.5 g / m ² or less.

  The electrophotographic recording sheet coated with the toner fixing improver according to the present invention is excellent in toner fixing property, is not significantly yellowed, has no trouble in feeding and discharging, and is excellent in recyclable recording sheet. It is.

  As the sheet-like substrate in the electrophotographic recording sheet of the present invention, any material can be used as long as it can be provided with a processing agent or toner-receiving layer mainly composed of the toner fixing improver. However, the fixing property of the toner to the sheet-like substrate itself is not essentially affected, and various paper substrates, resin substrates such as plastic films and plastic sheets are used. However, considering recovery and regeneration, paper substrates are preferred.

  When the sheet-like substrate of the present invention is a paper substrate, hardwood or softwood wood fibers can be used as the pulp fibers. The pulp manufacturing method is not particularly limited, and one or two or more stages of delignification treatment of unbleached pulp obtained by cooking methods such as kraft cooking method, polysulfide cooking method, sulfite cooking method, etc., followed by chlorine, caustic soda, hydro It may be bleached by a multi-stage bleaching method with appropriate addition of sulfite, etc. (craft pulp, sulfide pulp, etc.). Considering the load of organic chlorine compounds on wastewater, chlorine dioxide can be substituted for chlorine. An ECF pulp obtained from a bleaching method using a TCF or a TCF pulp obtained from a multi-stage bleaching method using no chlorine-based bleaching chemicals using ozone is preferred. In addition, mechanical pulp such as groundwood pulp (GP), thermomechanical pulp (TMP), chemithermo mechanical pulp (CTMP), semi-chemical pulp such as semichemical pulp (SCP), and chemiground pulp (CGP) It can be used. In addition, hemp pulp, kenaf pulp, and bagasse pulp, which are non-wood fibers, can be mentioned, and waste paper pulp can also be used because of effective utilization of resources.

  The pulp is appropriately selected and beaten in the range of 300 to 500 ml CSF, and the paper is made with a long mesh multi-cylinder paper machine, a long mesh Yankee type paper machine, a twin wire type paper machine, a circular net type paper machine, and an inclined wire type paper machine. To do. In addition, this invention does not receive any restriction | limiting about the paper machine to be used.

  In addition, inorganic or organic fillers can be used for papermaking. For example, kaolin, talc, clay, calcium carbonate, calcined clay, titanium oxide, diatomaceous earth, particulate anhydrous silica, activated clay, zinc oxide, aluminum oxide, aluminum hydroxide, zinc sulfate, barium sulfate, silicon dioxide, colloidal silica, etc. Organic fillers such as inorganic fillers, urea-formalin resin fillers, nylon powder, polyethylene powder and the like can be mentioned.

  The sizing agent for internal addition and external addition is not particularly limited, and any sizing agent can be used. For example, a rosin sizing agent, an alkyl ketene dimer sizing agent, an alkenyl succinic anhydride, or the like can be used as the sizing agent. Depending on the application, if the Steecht sizing degree is less than 10 seconds, problems such as bleeding of the writing ink occur, which is not preferable. On the other hand, if it exceeds 200 seconds, the toner fixing property is deteriorated, which is not preferable. When using an alkyl ketene dimer sizing agent as an external additive sizing agent, it is necessary to adjust the coefficient of friction to be in the range of 0.45 to 0.75. In addition, as other internal chemicals, paper auxiliary chemicals such as a colorant, a paper strength enhancer, and a yield improver can be used as long as they do not affect the Steecht sizing degree and the friction coefficient. As the paper strength enhancer, cation-modified starch, polyacrylamide and the like can be used, and as the wet paper strength enhancer, polyamide polyamine epichlorohydrin resin, melamine-formalin resin, urea-formalin resin and the like can be used. However, the use of a wet paper strength enhancer extremely deteriorates the disaggregation property, so care must be taken when using it.

  Various binder resins can be used for the purpose of improving the surface strength. Oxidized starch, enzyme-modified starch, cation-modified starch, ester starch, ether starch, etc., methylcellulose, ethylcellulose, carboxymethylcellulose, methoxycellulose, hydroxycellulose, fully (or partially) saponified polyvinyl alcohol, carboxy-modified polyvinyl alcohol, silicon-modified Polyvinyl alcohols such as polyvinyl alcohol, polyacrylamide, polyvinylpyrrolidone, acrylic acid amide, acrylic acid ester copolymer, acrylic acid amide ester, methacrylic acid copolymer, styrene / maleic anhydride copolymer alkali salt, isobutylene Maleic anhydride copolymer water-soluble polymer such as alkali salt, casein, polyvinyl acetate, polyurethane, polyacrylic acid, polyacrylate ester, polybutyl methacrylate DOO, latexes such as styrene-butadiene copolymer.

  The method for externally adding the surface strength agent is not particularly limited. Air knife coater, roll coater, reverse roll coater, blade coater, bar coater, gravure coater, kiss roll coater, cast coater, curtain coater, die slot coater, Chanplex On-machine and off-machine coaters equipped with coating equipment such as coaters, brush coaters, gate roll coaters, Hamilton coaters, KCM coaters, size press coaters, methade size presses, methade film transfer roll coaters, lip coaters, slide bead coaters, etc. Apply and dry.

  On the other hand, when using a resin substrate as a sheet-like substrate, cellulosic materials such as viscose and acetate, or polyethylene, polypropylene, polyvinyl chloride, polystyrene, nylon, polycarbonate, polyethylene terephthalate, polybutylene terephthalate, etc. The organic resin can be mixed with a filler or a chemical as necessary and formed into a sheet by a known method such as an extrusion method, a calendar method, or a stretching method. Synthetic paper and spunbonded nonwoven fabric can also be used.

  In a preferred embodiment, the present invention uses an amino group-containing acrylic resin as a toner fixing improver. The electrostatic charge liquid developing system for wet electrophotography selectively develops an electrostatic charge developing liquid toner, which will be described later, into a latent image charge, and then develops the solvent by volatilizing the solvent by heat treatment with a transfer drum. This is a mechanism for forming a film based on a resin contained in the toner, for example, a polyolefin resin, and bonding the film to a recording sheet. Therefore, in the adhesion between the toner resin-based film and the recording sheet, a physical adhesive force that the film softened by heating is fused to the recording sheet is the center. In such a situation, when an amino group-containing acrylic resin having a hydrophobic part (polyethylene) and a hydrophilic part (amino nitrogen) in the same molecule is used, the paper base mainly composed of cellulose fibers has a hydrophilic part. (Amino nitrogen) is chemically bonded, and the toner resin-based film is in a crosslinked state by fusing and identifying the hydrophobic part (polyethylene). Due to this phenomenon, a strong adhesive force is developed between the recording sheet and the toner resin-based film, and the fixing property can be remarkably improved.

  As an amino group-containing acrylic resin, an amino group-containing acrylic monomer neutralized partly or entirely with an organic acid and a monomer mainly composed of alkyl (meth) acrylate were emulsion-polymerized in the presence of an emulsifier. Is.

  The amino group-containing acrylic monomer refers to an amino group-containing (meth) acrylic acid ester or (meth) acrylamide, etc., and an aminoalkyl (meth) acrylate monomer or N-aminoalkyl (meth) acrylamide single amount Such as body.

  Specific examples of the aminoalkyl (meth) acrylate monomer include dimethylaminoethyl (meth) acrylate, dimethylaminopropyl (meth) acrylate, t-butylaminoethyl (meth) acrylate, and monomethylaminoethyl (meth) acrylate. Etc.

  Specific examples of the N-aminoalkyl (meth) acrylamide monomer include dimethylaminopropyl (meth) acrylamide and dimethylaminoethyl (meth) acrylamide.

  The amino group-containing acrylic monomer is partially or completely neutralized with an organic acid and subjected to emulsion polymerization. As such an organic acid, an organic carboxylic acid is preferable. Examples of the organic carboxylic acid include formic acid (boiling point 100.8 ° C.), acetic acid (boiling point 117.8 ° C.), propionic acid (boiling point 140.8 ° C.), and the like. These should just use at least 1 sort.

  The alkyl (meth) acrylate refers to an alkyl ester of (meth) acrylic acid, and an alkyl ester of (meth) acrylic acid having an alkyl group having 1 to 10 carbon atoms is preferable. Specific examples include methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, hydroxypropyl (meth) acrylate, β-ethoxyethyl (meth) acrylate, glycidyl (meta ) Acrylate and the like. By the way, the alkyl group includes a substituted alkyl group.

  In another embodiment, in the present invention, the toner fixing improver is at least one selected from rosin ester resins, styrene / acrylic resins, styrene / maleic resins, olefin / acrylic resins, and olefin / maleic resins. Use seeds. As described above, the electrophotographic electrostatic liquid developing system of wet electrophotography selectively develops electrostatic charge developing liquid toner to latent image charges, and then develops it. Then, the solvent is volatilized by heat treatment with a transfer drum, This is a mechanism in which a film based on a resin contained in the liquid toner, for example, a polyolefin resin, is formed and adhered to a recording sheet. Therefore, the adhesion between the toner resin-based film and the recording sheet is centered on the physical adhesive force at which the film softened by heating is fused to the recording sheet.

  In this situation, when a rosin ester resin having a hydrophobic part and a hydrophilic part is used, the hydrophilic part is chemically bonded to a paper base mainly composed of cellulose fibers, and the toner resin-based film has a hydrophobic part. It becomes a crosslinked state by fusing and identifying. Styrene / acrylic resins, styrene / maleic resins, olefin / acrylic resins, and olefin / maleic resins have the same effect, but these resins have the effect of further penetrating rosin ester resins. In combination with the rosin ester resin, the adhesion of the toner resin-based film to the recording sheet is enhanced. By this phenomenon, a strong adhesive force is developed between the recording sheet and the toner resin-based film, and the fixing property can be remarkably improved.

  Therefore, in a preferred embodiment, the toner fixing improver in the present invention is selected from rosin ester resins, styrene / acrylic resins, styrene / maleic resins, olefin / acrylic resins, and olefin / maleic resins. In combination with at least one of them. In this case, the styrene / acrylic resin, the styrene / maleic resin, the olefin / acrylic resin or the olefin / maleic resin is used alone or in combination, and is 0.1 to 50% by mass with respect to the rosin ester resin. , Preferably 1 to 10% by mass, more preferably 3 to 5% by mass.

  Rosin ester resins, styrene / acrylic resins, styrene / maleic resins, olefin / acrylic resins, and olefin / maleic resins are all widely used as papermaking chemicals and do not turn yellow over time. In addition, there is no difficulty in disaggregation of recovered waste paper and waste paper.

The toner fixing improver is applied in an amount of 0.1 g / m ² or more on at least one surface of the sheet-like substrate. There is no limitation on the coating method, and any method may be used as long as it can efficiently coat 0.1 g / m ² among the methods that can be used for coating the toner fixing improver. In particular, when a coating method called a transfer roll coater method is used, the amount of penetration of the toner fixing improver into the paper substrate is small and the toner fixing agent is uniformly present on the outermost surface of the paper substrate. The fixing effect is further improved. Examples of the transfer roll coater type include a gate roll coater type, a Hamilton roll coater, a KCM coater and the like as a gate roll coater type, and a shim sizer type such as a metade size press and a metade film transfer roll coater. It is not done.

  The toner fixing improver only needs to be present on the surface of the sheet-like base material, and the layer configuration and processing form are not selected. For example, it may be applied to the surface of the sheet-like substrate, or may be mixed with other substances and applied to the sheet-like substrate, or may be added internally during sheet formation. Accordingly, the electrophotographic recording sheet of the present invention may be prepared by subjecting at least one surface of a sheet-like base material to a toner receptive treatment with a treating agent containing at least one toner fixing improver. Further, it may be prepared by laminating a toner receiving layer containing at least one kind of the toner fixing improver on at least one surface of the sheet-like substrate. When a toner fixing improver is contained in the toner receiving layer, it may be added at the stage of coating preparation, and the various binder resins described above may be used as the binder resin of the coating, and the various fillers described above may be used as the pigment. it can. The toner-receptive treatment and toner-receptive layer only need to contain a toner fixing improver, and are not affected by the type of binder resin or pigment or the coating method. Alternatively, a larger amount of toner fixing improver is required than when applied to the coated paper surface.

  It is preferable that a styrene / butadiene copolymer (also referred to as “SB copolymer”) is further contained in the processing agent containing a toner fixing improver or in the toner receiving layer. In this styrene / butadiene copolymer, the total amount of the two components of the styrene monomer and the butadiene monomer is 90 mol% or more, preferably 95 mol% or more with respect to 100 mol% of the copolymer. Such a styrene / butadiene copolymer is hydrophobic and has an effect of fusing with a resin used in the toner to promote toner fixing properties.

The coating amount of the toner fixing improver on one surface of the sheet-like substrate is 0.1 g / m ² or more and 0.8 g / m ² or less, preferably 0.3 g / m ² or more and 0.5 g / m ² or less. is there. When the coating amount is less than 0.1 g / m ² , the toner fixing property is deteriorated, and when rubbed with an eraser, the print is blurred or the cellophane tape bonded to the toner fixed image portion is peeled off. Is not preferable because it peels off. As for the upper limit, even if coating or internal addition exceeds 0.8 g / m ² , the effect is saturated and the cost is increased. In the case of an amino group-containing acrylic resin, recording by oxidation of amine is performed. This is not preferable because yellowing of the sheet occurs.

  The toner fixing improver of the present invention is generally used for paper products. If it is within the above-mentioned range, yellowing that becomes a problem when polyethyleneimine is used, and disaggregation of damaged paper and waste paper are used. The problem of being bad does not occur.

  In the electrophotographic recording sheet of the present invention, the coefficient of friction is important for ensuring good running properties, and a range of 0.40 to 0.75 is preferable. If the recording sheet is less than 0.40, the recording sheet is too slippery, which may cause the recording sheet to be double-fed or idle. Even if it exceeds 0.75, double feeding and idling may occur. The runnability is also related to the stiffness of the recording sheet, and the thickness is preferably 60 to 230 μm, and the Clark stiffness in the CD direction is preferably 13.5 to 30.0 cm. If it is less than 13.5 cm, there is a high possibility of winding around the paper feed roll or transfer roll in the printing press due to lack of stiffness. Conversely, if it exceeds 30.0 cm, not only paper supply / discharge but also printing will be affected. Since it may give, it is not preferable.

  The coefficient of friction is preferably adjusted by adding or externally adding a lubricant. Examples of the lubricant to be used include modified polyolefin wax or emulsion, natural fats and oils, and stearic acid metal salts. The Clark stiffness is preferably adjusted by changing the density with the calendar. However, it is also effective to use the adjustment of the press line pressure in the water pressing step in papermaking.

The basis weight of the liquid electrophotographic liquid toner recording sheet of the present invention is preferably 50 to 220 g / m ² , and the air permeability (JIS P8117) is preferably 40 seconds or less from the viewpoint of preventing curling of the printed matter. In particular, the curl height in the width direction, the flow direction, and the torsion when the one printed by the copier is suspended is measured, and the A4 vertical width direction curl height is 30 mm or less, the flow direction curl height is 25 mm or less, A sheet having a twist curl height of 20 mm or less is suitable as a recording sheet. The whiteness is not particularly limited, but 70% or more is preferable because the printed surface looks beautiful.

  The toner particles in the electrostatic charge developing liquid toner as the image forming material are not particularly limited, and those produced by a conventional method can be used. For example, as described in JP-B-55-3696, JP-A-52-125333, JP-A-48-49445, etc., previously refined pigments or dyes and thermoplastic resins There is a developer obtained by dispersing a toner containing as a main component in a toner dispersion medium. Moreover, as similar, as described in JP-A-61-36759, a small amount of non-aqueous solvent is added to a thermoplastic resin and a colorant, and the mixture is kneaded by a kneading means such as a ball mill or a high-speed stirrer, and concentrated There is also a method in which a toner is used and further dispersed in a non-aqueous solvent using a disperser. More recently, a manufacturing method as disclosed in Japanese Patent Publication No. 5-87825 has been proposed. This is insoluble in a nonpolar solvent at 40 ° C. or lower, but once the temperature exceeds 50 ° C., a thermoplastic resin having a property of solvating with the nonpolar solvent is once solvated with the nonpolar solvent and then cooled. This is a method for producing a liquid developer by forming fine thermoplastic resin fine particles. As described above, various liquid toner production methods have been presented, but the present invention is not limited to them.

  Further, the composition of the toner particles in the liquid toner is not particularly limited, and conventionally known ones can be used. In general, toner particles include a fixing agent for fixing toner particles to a recording sheet, a colorant such as a pigment or a dye for visualization, and a charge imparting agent for imparting electrical characteristics to a liquid toner. Etc.

  As the fixing resin for the electrostatic toner for developing an electrostatic charge, a known resin that has been conventionally used for the electrostatic toner for developing an electrostatic charge can be used, and a thermoplastic resin is particularly preferable, such as polystyrene, polyethylene, and polypropylene. Polyolefin resin, polyester, polyurethane, polyamide and the like can be used alone or in combination. Of these, thermoplastic resins containing carboxyl groups such as polyacrylic acid, styrene-acrylic acid copolymer, ethylene-acrylic acid copolymer, and ethylene-methacrylic acid copolymer are particularly preferred. It is not particularly limited.

  As the colorant for the liquid toner for electrostatic charge development used in the present invention, known pigments, dyes or a mixture of both conventionally used for the liquid toner for electrostatic charge development can be used. For example, Hansaero, Benzidine Ero, Benzidine Orange, First Red, Brilliant Carmine 3B, Copper Phthalocyanine Blue, Phthalocyanine Green, Spirit Black, Oil Blue, Alkali Blue, Rhodamine 6B, Nigrosine, Carbon Black, Dichloroquinacridone, Isoindolinone It is done.

  A charge adjusting agent can be added to the liquid toner for developing electrostatic charge used in the present invention. Examples of the charge control agent include metal salts of fatty acids such as naphthenic acid, octenoic acid, oleic acid, stearic acid, and lauric acid, metal salts of sulfosuccinic acid esters, and oil-soluble sulfonic acid metal salts described in JP-B-45-556. A metal salt of abietic acid or hydrogenated abietic acid described in JP-B-48-25666, an alkylbenzenesulfonic acid Ca salt described in JP-B-55-2620, and an aroma described in JP-A-52-107837 Nonionic surfactant such as aromatic carboxylic acid or sulfonic acid metal salt, polyoxyethylated alkylamine, fats and oils such as lecithin and linseed oil, polyvinyl pyrrolidone, organic acid ester of polyhydric alcohol, etc. , All regulators can be used.

  The recording sheet for liquid toner for wet electrophotography of the present invention is a postcard, general printing paper (multi-color compatible), ink jet paper, ink jet paper requiring water resistance, foam paper, dry electrophotographic transfer paper, thermal transfer acceptance It can also be used for paper, office paper, release base paper for lamination, and the like.

  Hereinafter, the present invention will be described in more detail based on examples. In the examples, “part” means mass part, and “%” means mass%. Note that the present invention is not limited to these examples.

Examples 1-4
Eucalyptus, 100% EBK bleached LBKP made from oak as raw material is beaten into 380 ml CSF, 10.0% by weight light calcium carbonate as filler, alkenyl succinic anhydride as internal sizing agent (National Starch, Fibran 81) Of 0.07% by mass, Yield improver (manufactured by Kyowa Sangyo Co., Ltd., Percoll 182) at 0.02% by mass with a long mesh multi-cylinder paper machine, and a sheet-like base having a basis weight of 64.0 g / m ² A material (hereinafter referred to as “base paper”) was prepared. As a component amount of toner receptive treatment per one side of the base paper, polyvinyl alcohol (manufactured by Denki Kagaku Kogyo Co., Ltd., PVAK17) is 0.3 g / m ² and an amino group-containing acrylic resin (manufactured by Chuo Rika Co., Ltd., Rikabond ET-8) 0.1 g / m ² (Example 1), 0.3 g / m ² (Example 2), 0.5 g / m ² (Example 3) or 0.8 g / m ² (Example 4). As described above, a mixed liquid of the polyvinyl alcohol and the amino group-containing acrylic resin was applied with a gate roll coater and then dried to obtain an electrophotographic recording sheet.

Example 5
Examples 1 to 4 were used except that the base paper obtained in Examples 1 to 4 was used and another amino group-containing acrylic resin (manufactured by Sumitomo Seika Co., Ltd., Zyxen AC) was applied at 0.3 g / m ² . In the same manner as in Example 4, an electrophotographic recording sheet was obtained.

Example 6
Using the base paper obtained in Examples 1 to 4, on one side of the base paper, 0.3 g / m ^{2 of} polyvinyl alcohol (PVAK17, manufactured by Denki Kagaku Kogyo Co., Ltd.) as a component amount for toner receptive treatment, rosin A mixture of 97 parts of ester resin (manufactured by Arakawa Chemical Co., Ltd., Superester E-730-55) and 3 parts of styrene / acrylic resin (manufactured by Arakawa Chemical Co., Ltd., Polymeron 1308) was adjusted to 0.3 g / m ^2. A liquid mixture of polyvinyl alcohol and the mixture was applied with a gate roll coater and then dried to obtain an electrophotographic recording sheet.

Example 7
Using the base paper obtained in Examples 1 to 4, 95 parts of rosin ester resin (Arakawa Chemical Co., Superester E-650) and styrene / maleic acid resin (Arakawa Chemical Co., Polymeron 385) 5 An electrophotographic recording sheet was obtained in the same manner as in Example 6 except that 0.3 g / m ² of the mixture was applied.

Example 8
Using the base papers obtained in Examples 1 to 4, 95 parts of rosin ester resin (Arakawa Chemical Co., Superester E-650) and olefin / maleic acid resin (Arakawa Chemical Co., Polymeron 482S) 5 An electrophotographic recording sheet was obtained in the same manner as in Example 6 except that 0.3 g / m ² of the mixture was applied.

Example 9
Using the base paper obtained in Examples 1 to 4, polyvinyl alcohol (manufactured by Denki Kagaku Kogyo Co., Ltd., PVAK17) 0.6 g / m ² and amino group-containing acrylic resin (manufactured by Chuo Rika Co., Ltd., Rikabond ET-8) Was obtained in the same manner as in Examples 1 to 4 except that 0.6 g / m ² was impregnated with a 2-roll size press impregnator.

Example 10
Using the base paper obtained in Examples 1 to 4, polyvinyl alcohol (manufactured by Denki Kagaku Kogyo, PVAK17) 0.6 g / m ² and rosin ester resin (manufactured by Arakawa Chemical Co., Ltd., Superester E-730-) 55) 97 parts of a styrene-acrylic resin (manufactured by Arakawa chemical Industries, Ltd., the mixture 0.6 g / m ² of Polymaron 1308) 3 parts to be impregnated with a 2-roll size press impregnator in the same manner as in examples 1 to 4 Thus, an electrophotographic recording sheet was obtained.

Example 11
0.3 g of polyvinyl alcohol (manufactured by Denki Kagaku Kogyo Co., Ltd., PVAK17) is used as a component for toner receptive treatment on one side of matte-coated paper 81.4 g / m ² (made by Oji Paper, New Age) as a sheet-like substrate. and / m ^2, an amino group-containing acrylic resin (central Rika, Rikabondo ET-8) so that the a 0.3 g / m ^2, a mixed solution of the polyvinyl alcohol and the amino group-containing acrylic resin by a roll coater After coating, it was dried to obtain a recording sheet for electrophotography.

Example 12
Using the base papers obtained in Examples 1 to 4, an SB copolymer (manufactured by Zeon Corporation, POT 7192) was added to 0.3 g / m ^{2 on} one side of the base paper as a component for toner receptivity treatment. A mixed solution of the SB copolymer and the amino group-containing acrylic resin so that the amino group-containing acrylic resin (Rikabond ET-8, manufactured by Chuo Rika Co., Ltd.) is 0.3 g / m ^2. And dried after coating to obtain an electrophotographic recording sheet.

Example 13
Using the base papers obtained in Examples 1 to 4, 50 parts of an SB copolymer (manufactured by A & L Japan, PA 3056) and polyvinyl alcohol (electric chemical Co., Ltd., PVAK17) a mixture of 50 parts of 0.3 g / m ^2, an amino group-containing acrylic resin (central Rika Co., Rikabondo ET-8) so that the a 0.3 g / m ^2, SB-based copolymer A mixed liquid of a polymer, polyvinyl alcohol and the amino group-containing acrylic resin was applied with a gate roll coater and then dried to obtain an electrophotographic recording sheet.

Example 14
[Preparation of undercoat]
Using 25 parts of light calcium carbonate (made by Okutama Kogyo Co., Ltd., Tamapearl TP121) as a pigment and 75 parts of heavy calcium carbonate (made by Bihoku Powder, Softon 2200), polyacrylic acid soda (manufactured by Toagosei Co., Ltd.) for the pigment as a dispersant Aron A-9) 0.2 part was added, and a pigment slurry having a solid content of 70% was prepared using a Coreless disperser. To this slurry, 10 parts of oxidized starch (manufactured by Oji Cornstarch, Ace A) and 10 parts of SB copolymer (manufactured by Nippon Zeon Co., Ltd., PT1004) (in terms of each solid content) were added, and water was added to obtain a solid content concentration. A 62% paint was prepared.
[Top coat]
Using 50 parts kaolin (CADAM, Amazon) as a pigment and 50 parts light calcium carbonate (Otama-Tama Kogyo, Tamapearl TP121) as a dispersant, polyacrylic acid soda (manufactured by Toagosei Co., Aron A-9) 0.2 parts were added, and a pigment slurry having a solid content of 70% was prepared using a Coreless disperser. To this slurry, 5 parts of oxidized starch (manufactured by Oji Cornstarch, Ace A) and 15 parts of SB copolymer (manufactured by ZEON, PT1004) (in terms of each solid content) were added, respectively, and an amino group-containing acrylic resin ( 10 parts of Rikabond ET-8) manufactured by Chuo Rika Co., Ltd. and water were added to prepare a paint having a solid concentration of 60%.
After coating and drying the undercoat paint on one side of the base paper obtained in Examples 1 to 4 using a rod coater to a dry mass of 15 g / m ² , the top coat paint was dried using a rod coater. The recording sheet for electrophotography was obtained by coating and drying at 10 g / m ² .

Comparative Example 1
0.3 g / m ^{2 of} polyvinyl alcohol (manufactured by Denki Kagaku Kogyo Co., Ltd., PVAK17) and 0.3 g / m of polyethyleneimine-based resin (manufactured by Nippon Shokubai Chemical Co., Ltd., Epomin p1000) per side of the base paper obtained in Examples 1-4. The mixed liquid of the polyvinyl alcohol and the polyethyleneimine resin was coated on both sides with a gate roll coater and dried so as to obtain m ² , thereby obtaining an electrophotographic recording sheet.

Comparative Example 2
The base paper obtained in Examples 1 to 4 was coated with a coating solution not containing an amino group-containing acrylic resin in the same manner as in Example 1 to obtain an electrophotographic recording sheet.

Comparative Example 3
A coating liquid containing no amino group-containing acrylic resin was applied to the matte coated paper used in Example 11 in the same manner as in Example 11 to obtain an electrophotographic recording sheet.

  Table 1 shows the physical properties of the electrophotographic recording sheets obtained in Examples 1 to 14 and Comparative Examples 1 to 3 and the results of the following evaluation.

(Printability)
(Print density)
Image output was performed with a wet electrophotographic copying machine (E-PRINT 1000, manufactured by Indigo Corporation). The reflection density of the black solid portion and the obtained image was measured with a reflection densitometer (“Macbeth RZ-918” manufactured by Macbeth).
(Cellophane tape peeling test)
The state of the printed part was evaluated when the cellophane tape (cello tape (R), manufactured by Nichiban Co., Ltd.) was attached to the black solid printed part and then peeled off.
(Eraser resistance test)
The character printing part was rubbed 20 times with an eraser (PE-04A manufactured by Dragonfly Pencil Co., Ltd.) to evaluate the printing state.

(Visual evaluation of yellowing)
The test piece was placed in a hot air circulating oven at 105 ° C. and left for 24 hours, and the yellowing state was observed.

◎ No state change 〇 No state change △ Some state change × State change

Claims (10)

  In a recording sheet for electrophotography in which at least one surface of a sheet-like base material is subjected to toner receptive treatment, the toner receptive treatment includes amino group-containing acrylic resin, rosin ester resin, styrene / acrylic resin, styrene A recording sheet for electrophotography, which is made of a processing agent containing at least one selected from maleic resin, olefin / acrylic resin, and olefin / maleic resin.   The electrophotographic recording sheet according to claim 1, wherein the treatment agent contains at least an amino group-containing acrylic resin.   The electrophotographic recording sheet according to claim 1, wherein the treatment agent contains at least a rosin ester resin.   The treating agent contains a rosin ester resin and at least one selected from a styrene / acrylic resin, a styrene / maleic resin, an olefin / acrylic resin and an olefin / maleic resin, The electrophotographic recording sheet according to claim 3.   The electrophotographic recording sheet according to claim 1, further comprising a styrene / butadiene copolymer in the treatment agent.   An electrophotographic recording sheet having a sheet-like substrate and a toner receiving layer on at least one surface thereof, wherein the toner receiving layer includes an amino group-containing acrylic resin, a rosin ester resin, and a styrene / acrylic resin. An electrophotographic recording sheet comprising: at least one selected from styrene / maleic resin, olefin / acrylic resin, and olefin / maleic resin.   The electrophotographic recording sheet according to claim 6, wherein the toner receiving layer contains at least an amino group-containing acrylic resin.   The electrophotographic recording sheet according to claim 6, wherein the toner receiving layer contains at least a rosin ester resin.   The toner receiving layer contains a rosin ester resin in combination with at least one selected from a styrene / acrylic resin, a styrene / maleic resin, an olefin / acrylic resin, and an olefin / maleic resin. The electrophotographic recording sheet according to claim 8.   The electrophotographic recording sheet according to claim 6, further comprising a styrene / butadiene copolymer in the toner receiving layer.