JP2004252438A - Electrophotographic transfer sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrophotographic transfer sheet which is free of paper jamming due to heat curl during paper discharge, free of melt sticking to a heat roll section and paper breaking in the heat roll section for fixation, and also ensures good image quality and water resistance after printing. <P>SOLUTION: The electrophotographic transfer sheet includes: a sheetlike support which is a laminate prepared by bonding/laminating a thermoplastic resin film layer (A) on at least one surface of a core material layer (B) formed of a paper substrate or a thermoplastic polyester resin film; and a toner receiving layer based on a conductive metal oxide and disposed on a surface of the layer (A). The sheet has a Clark stiffness of ≥12 cm in the lateral direction measured according to JIS P 8143. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic transfer sheet used for a printing apparatus using an electrophotographic method by a toner. More specifically, for electrophotography, there is no paper jam due to thermal curl at the time of paper ejection, no fusing with the transfer sheet at the heat roll for fixing and no breakage of paper, and good image quality and water resistance after printing. It relates to a transfer sheet.

  2. Description of the Related Art Conventionally, a heat roll fixing type electrophotographic printer uses PPC paper of a plain paper type and an OHP sheet having a polyester film surface-treated. However, PPC paper is limited to use in applications where water resistance, chemical resistance and strength are not required, and OHP sheets have water resistance and chemical resistance but are transparent, so their use is limited to OHP applications. I have. On the other hand, in applications where water resistance, chemical resistance and strength are required in printing methods such as offset printing and screen printing, synthetic paper mainly composed of polypropylene has been used conventionally, and high humidity, chemical exposure, outdoor use, etc. It is used for applications such as documents, drawings, photographs, maps, manuals, labels, tags, etc., which are used by being brought or affixed to the environment.

  By the way, in the heat roll fixing type electrophotographic printer, the heat roll surface temperature at the time of toner fixing is 170 to 200 ° C., which exceeds the melting point of polypropylene which is a main raw material of synthetic paper. Therefore, when a synthetic paper mainly composed of polypropylene (for example, a product “Yupo” manufactured by Yupo Corporation; Japanese Patent Publication No. 46-40794 (Patent Document 1)) is passed through a heat roll fixing type electrophotographic printer, As a result, there is a problem in running properties, such as curling due to the occurrence of paper, causing poor paper passing, and the printed matter being rounded, and the synthetic paper being melted and cut off in the fixing heat roll portion.

  In order to solve this problem, Japanese Patent Application Laid-Open No. 2002-258509 discloses an electrophotographic transfer sheet using a laminate in which a thermoplastic film layer is adhered and laminated on a paper base material or a core material layer made of a thermoplastic polyester resin film. (Japanese Patent Application Laid-Open No. H10-163,837). The publication further states that at least one surface of the laminate is preferably subjected to a conductive treatment in order to improve the printability and the antistatic property, but specific examples and detailed descriptions of the conductive agent are given. Is not described. In addition, although the range of the target surface electric resistance value by conducting the conductive treatment is mentioned, even if the conditions of the surface electric resistance value range described therein are satisfied, depending on the printing environment and the printer, In many cases, a good image cannot be obtained.

  A method using a conductive agent whose surface electric resistance value is not affected by the printing environment has been conventionally proposed. Japanese Patent Application Laid-Open No. 2001-337478 (Patent Document 3) proposes a method of applying an image receiving layer using a synthetic hectorite clay mineral as a conductive agent and a polyurethane ionomer resin as an adhesive to a surface of a support made of synthetic paper. Have been. However, the synthetic hectorite clay mineral is characterized by forming a gel, and the strength of this gel depends on the concentration of the synthetic hectorite clay mineral. A phenomenon in which the layer itself softens is observed. That is, when the paper is left in a high-temperature and high-humidity environment or immersed in water, a phenomenon in which the image receiving layer peels off may be observed, so that the use is restricted.

  Furthermore, a conductive agent using a conductive metal oxide has been proposed as a conductive agent whose surface electric resistance value is not affected by the printing environment. JP-A-6-75419 (Patent Document 4) and JP-A-7-28268 (Patent Document 5) propose to provide a layer using the conductive oxide on a transparent support. Mentions the surface electrical resistance at which an appropriate image can be obtained with an electrophotographic printer. However, it does not mention the use of a laminate in which a thermoplastic film layer is bonded and laminated to a core material layer made of a paper base or a thermoplastic polyester resin film as described above. In addition, when the appropriate range of the surface electric resistance value referred to in these publications is applied to the laminate, a good image cannot be often obtained depending on a printing environment or a printer.

  Japanese Patent Application Laid-Open No. 2000-39735 (Patent Document 6) proposes providing a coating layer of a polyester resin containing a conductive inorganic powder on both sides or one side of a base paper. Further, Japanese Patent Application Laid-Open No. 9-73184 (Patent Document 7) discloses an electroconductive transfer method for an electrophotographic transfer sheet, in which a conductive metal oxide is blended into an electrophotographic transfer material, and an appropriate range of surface electric resistance. It has been proposed. However, none of them mentions the use of a laminate obtained by bonding and laminating a thermoplastic film layer to a core material layer made of a paper base or a thermoplastic polyester resin film as described above. In addition, when the appropriate range of the surface electric resistance value mentioned is applied to such a laminate, a good image is often not obtained depending on a printing environment or a printer.

On the other hand, in a sheet in which a coating layer is provided on the surface of a sheet-like support bonded and laminated as described above, the characteristic for obtaining good printing quality with an electrophotographic printer is not a surface electric resistance value but a capacitance. Is specified in Japanese Patent Application Laid-Open No. 2002-91049 (Patent Document 8). Some of the specified laminates having a capacitance (10 pF / cm ² or more) include an electrophotographic printer. In many cases, good print quality cannot be obtained. As a result of extensive studies by the present inventors, they have found that the printing quality of a laminated electrophotographic printer greatly depends on the surface electric resistance, and have completed the present invention.

JP-B-46-40794 JP 2002-258509 A JP 2001-337478 A JP-A-6-75419 JP-A-7-28268 JP 2000-39735 A JP-A-9-73184 JP 2002-91049 A

  An object of the present invention is to provide an electrophotographic apparatus that does not cause paper jam due to thermal curl at the time of paper discharge, fusing with a transfer sheet at a fixing heat roll section or paper breakage, and has good image quality and water resistance after printing. To provide a transfer sheet.

  The transfer sheet for electrophotography according to the present invention is used in an electrophotography system in which an image is formed by toner particles, and the transfer sheet is formed of a core material layer (B) made of a paper base material or a thermoplastic polyester resin film. A sheet-like support which is a laminate in which a thermoplastic resin film layer (A) is adhered and laminated on at least one surface; and a toner receiving material containing a conductive metal oxide as a main component on the surface of the thermoplastic resin film layer (A). A cladding stiffness in the horizontal direction measured based on JIS P 8143 (TAPPI T451) of 12 cm or more. Further, it is preferable that the plastic resin film layer is a synthetic paper made of a stretched film mainly containing a polyolefin resin and an inorganic pigment.

Preferably, the conductive metal oxide is provided with semiconductivity by doping impurities into the metal oxide. More preferably, the conductive metal oxide is in a form coated on the surface of the base material.
Further, the conductive metal oxide is preferably tin oxide containing antimony as an impurity, and more preferably, the base metal surface coated with tin oxide containing antimony as an impurity is used. It is more preferable to use acicular titanium oxide having a major axis of 1 to 15 μm and a minor axis of 0.05 to 0.5 μm as the base material. Further, the surface electric resistance of the toner receiving layer containing the conductive metal oxide as a main component is preferably in the range of 1 × 10 ⁵ to 1 × 10 ¹² Ω / □.

  The electrophotographic transfer sheet according to the present invention has a stable surface electric resistance value in a wide range of environments from a low temperature and a low humidity to a high temperature and a high humidity, has excellent toner transferability, has a high image density, and can provide high quality image quality. Also, there is no paper jam due to thermal curl at the time of paper ejection, no fusion with the transfer sheet at the heat roller for fixing, and no paper breakage, and there is no breakage or deformation of the paper due to water and no peeling of toner. It is a transfer sheet for electrophotography and is extremely useful in practice.

Hereinafter, preferred embodiments of the present invention will be described in detail.
(A) Thermoplastic resin film The thermoplastic resin film used in the present invention includes, for example, ethylene resins such as high-density polyethylene and medium-density polyethylene, propylene resins, polymethyl-1-pentene, ethylene-cycloolefin copolymers, and the like. Polyolefin resin, polyamide resin such as nylon-6, nylon-6,6, etc., polyethylene terephthalate and its copolymer, polybutylene terephthalate and its copolymer, thermoplastic polyester resin such as aliphatic polyester, polycarbonate , Atactic polystyrene, syndiotactic polystyrene and the like. Among them, it is preferable to use a polyolefin resin.

  Among the polyolefin-based resins, it is preferable to use a propylene-based resin in terms of chemical resistance and cost. Examples of the propylene-based resin include an isotactic polymer or a syndiotactic polymer obtained by homopolymerizing propylene. Also, use is made of a copolymer mainly composed of propylene having various stereoregularities obtained by copolymerizing α-olefin such as ethylene, 1-butene, 1-hexene, 4-methyl-1-pentene and propylene. You can also. The copolymer may be a binary system or a ternary or higher system, and may be a random copolymer or a block copolymer. It is preferable that a resin having a lower melting point than the propylene homopolymer is blended in the propylene-based resin in an amount of 2 to 25% by mass. High-density or low-density polyethylene is exemplified as such a resin having a low melting point. As the thermoplastic resin, one of the above thermoplastic resins may be selected and used alone, or two or more may be selected and used in combination.

  If necessary, inorganic fine powders, organic fillers, stabilizers, light stabilizers, dispersants, lubricants, and the like can be added to the thermoplastic resin. When adding an inorganic fine powder, one having a particle size of 0.01 to 5 μm is preferably used. Specifically, heavy calcium carbonate, light calcium carbonate, calcined clay, silica, talc, titanium oxide, barium sulfate, alumina and the like can be used. When adding an organic filler, it is preferable to select a resin different from the thermoplastic resin as the main component. For example, when the thermoplastic resin is a polyolefin resin, the organic filler is a polymer such as polyethylene terephthalate, polybutylene terephthalate, polycarbonate, nylon-6, nylon-6,6, cyclic olefin, polystyrene, polymethacrylate, etc. A polymer having a melting point higher than the melting point of the system resin or a glass transition temperature can be used. When adding an inorganic fine powder and / or an organic filler, it is preferably added in the range of 3 to 50% by mass.

  When a stabilizer is added, it is usually added in the range of 0.001 to 1% by mass. Specifically, sterically hindered phenol-based, phosphorus-based, and amine-based stabilizers can be used. When a light stabilizer is added, it is usually added in the range of 0.001 to 1% by mass. Specifically, sterically hindered amine-based, benzotriazole-based, benzophenone-based light stabilizers and the like can be used. The dispersant and the lubricant are used, for example, for the purpose of dispersing the inorganic fine powder. The amount of addition is usually in the range of 0.01 to 4% by mass. Specifically, silane coupling agents, metal soaps of higher fatty acids such as oleic acid and stearic acid, polyacrylic acid, polymethacrylic acid, and salts thereof can be used.

  The method of forming the thermoplastic resin film is not particularly limited, and the thermoplastic resin film can be formed by appropriately selecting from known methods. For example, using a single-layer or multi-layer T-die or I-die connected to a screw-type extruder to extrude the molten resin into a sheet-like form, such as cast molding, calendar molding, rolling molding, or inflation molding. Can be.

  The thermoplastic resin film is preferably uniaxially or biaxially stretched. Stretching can be performed by any of various methods commonly used. The stretching temperature is not less than the glass transition temperature of the thermoplastic resin to be used in the case of the non-crystalline resin, and is suitable for the thermoplastic resin having a melting point of the crystalline part or less from the glass transition temperature of the non-crystalline part in the case of the crystalline resin. Can be performed in a suitable temperature range. Specifically, a temperature lower by 2 to 50C than the melting point of the thermoplastic resin is preferable. As the stretching method, longitudinal stretching using a peripheral speed difference between roll groups, transverse stretching using a tenter oven, simultaneous biaxial stretching using a combination of a tenter oven and a linear motor, and the like can be used.

  The stretching ratio is appropriately determined in consideration of the properties of the thermoplastic resin used. For example, when using a propylene homopolymer or a copolymer thereof as the thermoplastic resin, it is preferably 2 to 10 times when stretched in one direction, and in the case of biaxial stretching, it may be 10 to 50 times in area magnification. preferable.

  If a thermoplastic resin containing an inorganic fine powder or an organic filler is stretched, a stretched porous resin film having fine pores therein can be obtained. The stretched thermoplastic resin film may be composed of a single layer, or may have a multilayer structure.

  The thickness of the thermoplastic resin film is usually 15 μm or more, preferably 25 μm or more. When the thickness of the thermoplastic resin film is less than 15 μm, the thickness of the obtained electrophotographic transfer sheet is small, the mechanical strength becomes insufficient, and curling due to heat may not be sufficiently prevented. Although the upper limit of the thickness of the film is not particularly limited, if the thickness exceeds 200 μm, the thickness of the obtained electrophotographic transfer sheet becomes excessively large, which causes a disadvantage that the number of sheets supplied to the paper supply unit of the printer decreases. It is also disadvantageous economically. Therefore, in general, the thickness of the thermoplastic resin film is preferably 200 μm or less, more preferably 150 μm or less.

(B) Core layer The core layer used in the present invention includes a thermoplastic resin layer on at least one of papers such as high quality paper, coated paper, art paper, cast coated paper, etc., containing cellulose pulp as a main component. Processed paper such as laminated paper provided is preferably used. In addition, thermoplastic polyester resin films such as polyethylene terephthalate and its copolymers, polybutylene terephthalate and its copolymers, aliphatic polyesters have heat resistance, and have a smooth surface and small irregularities, so that the image quality after printing is poor. Since it is good, it is preferably used.

  The thickness of the core material layer used in the present invention is not particularly limited, but is generally 50 to 200 μm. If the thickness is less than 50 μm, the mechanical strength of the resulting electrophotographic transfer sheet may be insufficient, and the repulsive force against deformation may be insufficient, resulting in electrophotographic transfer occurring during printing or printing. In some cases, sheet curling cannot be sufficiently prevented. Further, when the thickness exceeds 200 μm, the thickness of the obtained electrophotographic transfer sheet becomes excessively large, and the number of sheets supplied to the paper supply unit of the printer decreases. The texture of the transfer sheet may be inferior.

  In the present invention, the thermoplastic resin film can be bonded to one or both sides of the core material layer. When bonding a thermoplastic resin film to only one side of the core layer, provide a coating layer made of a synthetic resin layer, pigment and adhesive, etc. on the opposite side to the bonding side of the core layer and perform curl prevention treatment. Is preferred. The coating layer can be further provided with printability, paper supply / discharge suitability, and anti-blocking properties, and various types of recording such as water resistance, oil resistance, slip resistance, thermal recording, thermal transfer recording, and ink jet recording. Of course, it is also possible to provide aptitude and the like.

  When the thermoplastic resin film is bonded to both sides of the core material layer, the thermoplastic resin film to be laminated may be the same film on the front and back, or the types of the front and back films may be different, but one of the core material layers may be different. When a polypropylene-based resin film is laminated on the surface, it is preferable to laminate a polypropylene-based resin film on the other surface in terms of curling blank paper and curling after printing.

The method of bonding and laminating the thermoplastic resin film layer (A) on at least one side of the core material layer (B) is not particularly limited, but may be a wet lamination method, an extrusion lamination method, a dry lamination method, or the like. A known technique such as a wax laminating method is used. Generally, a dry lamination method is widely used, and as an adhesive used at this time, a polyisocyanate-based, epoxy-based curing agent, or the like is added to a polymer adhesive component such as a polyether-based or polyester-based adhesive. A blended one is often used. The coating amount of the adhesive is desirably in the range of 1 to 30 g / m ² . When bonding and laminating the thermoplastic resin film layer (A) on both sides of the core material layer (B), in order to maintain curl balance, the coating amount of the adhesive on the front side film layer and the back side film layer should be the same. Is preferred. An extrusion lamination method is also preferably used for higher image quality.

(C) Toner-Receiving Layer The present invention provides a metal oxide fine particle having a semiconductivity imparted by doping an impurity into a metal oxide to form a p-type semiconducting or n-type semiconducting valence electron controlling type. It is used as a conductive agent for a semiconductor, and is provided with an adhesive or the like as a toner receiving layer on the thermoplastic film layer (A) of the support which is a laminate described above. The layer forms a conductive path by contact between the fine particles. That is, since the conductive effect is developed through the formed conductive path, there is no dependency on humidity, and stable conductive characteristics can always be obtained. As a result, with respect to the environmental characteristics of the surface electric resistance, by conducting the conductive treatment with the conductive metal oxide fine particles, the surface electric resistance value in a certain range can be obtained even in a wide range of environmental changes from low humidity to high humidity. We have developed a toner receiving layer that has good toner transferability irrespective of changes, that is, good printing is possible regardless of the printing environment in an electrophotographic printer. In addition, the conductive metal oxide is, for example, a gel that softens when exposed to a large amount of water, such as a synthetic hectorite compound used as a conductive material in JP-A-2001-337478 (Patent Document 3). Since it is not formed, the water resistance is not impaired.

Many metal oxides are reduced or oxidized and become semiconductors when their composition deviates from the chemical equivalent composition. However, it is difficult to control the deviation, and it is necessary to control the required conductivity (σ). Is difficult. Therefore, a valence electron control type semiconductor which can improve the controllability and stability of conductivity by doping metal ions having a valence different by ± 1 as impurities instead of the metal ions constituting the metal oxide is suitable. Metal oxides whose conductivity is improved by reduction include ZnO, TiO ₂ , SnO ₂ , Ta ₂ O ₅ , ThO ₂ , and PbCrO ₄ , and metal oxides whose conductivity is improved by oxidation include NiO, FeO, can be cited MnO, CoO, Cu ₂ O, the _{Cr 2 O 3, MoO 2,} Bi 2 O 3 and the like. In order to further ensure the controllability and stability, a “conductive metal oxide” can be obtained by doping a metal ion having a valence different from the constituent metal ion by ± 1 as an impurity.

Examples of the conductive metal oxide used as the conductive agent in the present invention include SnO ₂ (Sb) (ie, SnO ₂ doped with Sb; the following abbreviations have the same meaning), TiO ₂ (Sb), ZnO ( Al), ZnO (Ga), SnO ₂ (F), NiO (Li), In ₂ O ₃ (Sn) and the like. In order to adjust the surface electric resistance to the required range, it is preferable to use a conductive metal oxide doped with antimony Sb as an impurity. Since the haze of the transfer sheet increases and the transfer sheet becomes bluish-gray due to antimony Sb, that is, the toner-receiving layer is colored. It is more preferable to use a composite conductive agent coated on the surface of a (non-conductive) base material.

For example, acicular rutile titanium oxide (TiO ₂₎ tin oxide Sb doped surface (SnO ₂ (Sb)) conductive layer coated with conductive titanium oxide _{(SnO 2 (Sb) / TiO} 2) is Ishihara Sangyo ( Co., Ltd., is commercially available as Taipec FT and ET series, and Sb-doped tin oxide (SnO ₂ (Sb)) alone is commercially available from Ishihara Sangyo Co., Ltd. as Taipec SN and FS series, and potassium titanate ( Conductive potassium titanate (SnO ₂ .Sb ₂ O ₅ / K ₂ O.nTiO) with a thin layer of tin oxide (SnO ₂ ) and antimony oxide (Sb ₂ O ₅ ) coated on the surface of a K ₂ O.nTiO ₂ whisker ₂₎ whiskers is commercially available as DENTALL WK series from Otsuka Chemical Co., plate-like barium sulfate (BaSO ₄₎ surface from tin oxide Sb-doped ( nO ₂ (Sb) conductive barium sulfate conductive layer was coated in _{(SnO 2 (Sb) / BaSO} 4), and, tin oxide Sb doped aluminum borate _{(9Al 2 O 3 · 2B 2} O 3) whisker surface (SnO ₂ (Sb)) conductive barium sulfate conductive layer was coated in _{(SnO 2 (Sb) / 9Al} 2 O 3 · 2B 2 O 3) pass whiskers from Mitsui Mining & Smelting Co., Tran Series Type-IV and It is commercially available as V. These single systems or composite systems can be used, but the single system can be appropriately used in consideration of the setting of the fluctuation range of surface electric resistance and whiteness which is one of the appearance characteristics. Alternatively, the composite system can be used alone or in a mixed form.

  Generally, in order to impart good conductivity to an insulator, it is important to effectively exhibit the conductivity of a mixed conductive material. In order to effectively derive the conductivity, it is necessary for the powder to be in effective contact with each other in the toner receiving layer provided on the thermoplastic film layer (A) to form a conductive path. The chance of contact between the conductive metal oxides greatly depends on the dispersion state and orientation state of the compounded powder. In order to obtain an optimal conductive state, it is required that the powders do not agglomerate and the contact probability between the powders is high.

  That is, the shape of the conductive metal oxide itself or the shape of the carrier that supports the conductive metal oxide becomes important. The more the shape becomes spherical, the more difficult it is to disperse the particles and the easier it is to aggregate. To increase the contact probability of these spherical conductive agents, the filling rate in the insulator becomes a problem, and it is necessary to mix a large amount of conductive agents. For this reason, adoption of a spherical conductive agent causes problems such as the necessity of special dispersing instruments and equipment. The above tendency becomes more remarkable as the shape size becomes smaller. As a result, when the spherical conductive agent as described above is employed, the cost is high and the application is limited.

Based on the above, the present inventors have conducted intensive studies and found that the base material was an appropriate acicular oxide, and the surface thereof was coated with the conductive metal oxide according to the present invention. The use of a material having a major axis of 1 to 15 μm and a minor axis of 0.05 to 0.5 μm increases the probability that the conductive metal oxides come into contact with each other morphologically and effectively increases the surface electrical resistance of the toner receiving layer. Can be lowered. Particularly preferably, the base material is needle-like titanium oxide, and the surface is coated with tin oxide containing antimony as an impurity (SnO ₂ (Sb) / TiO ₂ ), and the base material has a long axis of 1 to 15 μm and a short axis. When the axis having a thickness of 0.05 to 0.5 μm was used, the probability of morphologically contact between the conductive metal oxides was extremely high, and the surface electric resistance of the toner receiving layer could be effectively reduced. .

  Generally, when the surface electric resistance is adjusted using the conductive metal oxide, the surface electric resistance depends on the amount of the conductive metal oxide applied. That is, when the coating amount is small, no conductive path is formed, and the surface electric resistance value is high. When the coating amount is gradually increased, a decrease in the surface electric resistance value is observed along with the formation of the conductive path. Adjustment of the electric resistance value is easy. The present inventors have conducted intensive studies and have found that, when the conductive metal oxide is applied, the formation of conductive paths is hindered by adding one or more other pigments, and the surface of the conductive metal oxide is reduced with an increase in the amount of coating. It was found that the electric resistance value can be reduced gradually, and the adjustment of the surface electric resistance value was facilitated.

  Such other pigments to be mixed are not particularly limited, and for example, heavy calcium carbonate, light calcium carbonate, calcined clay, silica, talc, titanium oxide, barium sulfate, alumina and the like can be used. As another pigment to be mixed, another conductive metal oxide different from the conductive metal oxide used for lowering the surface electric resistance value can be used.

  In the electrophotographic transfer sheet according to the present invention, the method for forming the toner receiving layer is not particularly limited, and examples thereof include air knife coating, wire bar coating, blade coating, roll coating, gravure coating, reverse roll coating, and curtain coating. Forming by applying and drying coating liquid by die slot coating, champlex coating, brush coating, lip coating, slide bead coating, two roll or metering blade type size press coating, bill blade coating, gate roll coating, etc. Is done.

The present invention is not particular limitation on the coating amount of the coating liquid, 0.1 to 10 g / m ² approximately at normal dry mass per one surface, preferably, it is adjusted in the range of 0.1-5 g / m ^2. If the coating amount is less than 0.1 g / m ² , the surface electric resistance value is high, and the transferability of the toner may be poor. On the other hand, if it exceeds 10 g / m ² , the cost increases. After application and drying, a smoothing treatment may be performed using a super calendar, a machine calendar, a soft calendar, or the like, depending on the application.

As described above, the type of the conductive metal oxide, the shape of the conductive metal oxide itself or the shape of the carrier supporting the conductive metal oxide, the amount of coating, the type of other pigments to be mixed, the coating method By appropriately selecting and deciding the above, as a result, it becomes possible to set the surface electric resistance value of the toner receiving layer as desired by those skilled in the art. Preferably, the toner receiving layer has a surface electric resistance of 1 × 10 ⁵ to 1 × 10 ¹² Ω / □, more preferably 3 × 10 ⁵ to 1 × 10 ¹¹ Ω / □, most preferably 1 × 10 ⁶ to 1 × 10 ⁶ Ω / □. 1 × 10 ⁹ Ω / □.

  The toner receiving layer may have a multilayer structure by providing one layer or, if necessary, two or more intermediate layers. In the case of a multi-layer structure, it is not necessary that the respective coating liquids have the same or the same coating amount, and they may be appropriately adjusted according to a desired quality level, and are not particularly limited. When a toner receiving layer is provided on one side of a sheet-like support, a synthetic resin layer, a coating layer composed of a pigment and an adhesive, an antistatic layer, etc. are provided on the back side to prevent curling, impart printability, and supply / discharge paper. It is also possible to impart anti-blocking properties and the like. In addition, the back surface of the sheet-shaped support is subjected to various processings, for example, adhesion, magnetism, flame retardancy, heat resistance, water resistance, oil resistance, anti-slip, heat-sensitive recording, various recording aptitudes such as thermal transfer recording and ink jet recording, and various applications, by post-processing. Of course, it is also possible to use with appropriate aptitude.

  The electrophotographic transfer sheet obtained in the present invention has a horizontal Clark stiffness of 12 cm or more as measured according to JIS P 8143 (TAPPI T451) by humidifying all day and night in an ISO environment (23 ° C.-50% RH). , Preferably 15 cm or more. When the Clarke stiffness is less than 12 cm, poor running may occur in the heat roll fixing type electrophotographic printer.

  Hereinafter, the present invention will be described more specifically with reference to Examples, but it is needless to say that the present invention is not limited to these ranges. In the examples, "parts" and "%" indicate "parts by mass" and "% by mass" unless otherwise specified.

Example 1
(Formation of toner receiving layer)
100 parts by mass of conductive metal oxide (trade name: FT2000, SnO ₂ (Sb) -coated acicular titanium oxide, manufactured by Ishihara Sangyo Co., Ltd.)
100 parts by mass of polyurethane ionomer (trade name: Hydran AP40, manufactured by Dick Hercules)
1 part by mass of dispersant (trade name: Alon A-9, manufactured by Toagosei Co., Ltd.)
A coating solution obtained by mixing and stirring this composition (concentration: 20% aqueous) was applied onto one surface of synthetic paper (trade name: YUPO FPG80, manufactured by YUPO CORPORATION) with a coating amount of 3 g after drying with a bar coater. / M ² and dried to obtain a toner receiving sheet.

100 μm thick art paper (manufactured by Oji Paper Co., Ltd., trade name: Kanto 104.7 g / m ² ) is laminated and laminated by dry lamination on the front and back sides of the toner receiving sheet coated with the toner receiving layer, and transferred for electrophotography. Created a sheet.

Example 2
(Formation of toner receiving layer)
100 parts by mass of conductive metal oxide (trade name: SN-100P, Sb-doped spherical tin oxide, manufactured by Ishihara Sangyo Co., Ltd.)
100 parts by mass of polyester resin (trade name: Pesresin S-110G, manufactured by Takamatsu Yushi Co., Ltd.)
This composition (concentration: 20% toluene / MEK system) was mixed and stirred, and the coating solution obtained was applied to one surface of synthetic paper (trade name: YUPO FPG80, manufactured by YUPO Corporation) after drying with a bar coater. The coating was performed so that the amount became 3 g / m ^2, and dried to obtain a toner receiving sheet.

100 μm thick art paper (manufactured by Oji Paper Co., Ltd., trade name: Kanto 104.7 g / m ² ) is laminated and laminated by dry lamination on the front and back sides of the toner receiving sheet coated with the toner receiving layer, and transferred for electrophotography. Created a sheet.

Example 3
A toner receiving sheet coated with the same toner receiving layer as in Example 1 was laminated on the front and back of a 70 μm-thick coated paper (manufactured by Oji Paper Co., Ltd., trade name OK Topcoat 84.9 g / m ² ) by dry lamination. The sheets were laminated to prepare an electrophotographic transfer sheet.

Example 4
An electrophotographic transfer sheet was prepared in the same manner as in Example 1 except that the coating amount of the toner receiving layer was 1 g / m ² .

Comparative Example 1
(Formation of toner receiving layer)
100 parts by mass of synthetic hectorite clay mineral (trade name: Laponite RD, manufactured by Laporte Industries)
100 parts by mass of polyurethane ionomer (trade name: Hydran AP40, manufactured by Dick Hercules)
1 part by mass of dispersant (trade name: Alon A-9, manufactured by Toagosei Co., Ltd.)
A coating solution obtained by mixing and stirring this composition (concentration: 20% aqueous) was applied on one surface of synthetic paper (trade name: YUPO FPG80, manufactured by YUPO Corporation) with a coating amount of 3 g after drying with a bar coater. / M ² and dried to obtain a toner receiving sheet.

100 μm thick art paper (manufactured by Oji Paper Co., Ltd., trade name: Kanto 104.7 g / m ² ) is laminated and laminated by dry lamination on the front and back sides of the toner receiving sheet coated with the toner receiving layer, and transferred for electrophotography. Created a sheet.

Comparative Example 2
The same toner receiving layer as in Example 1 was coated on both sides such that the coating amount after drying on one side was 3 g / m ^2, and dried to obtain a toner receiving sheet. Used as

[Measurement of rigidity of electrophotographic transfer sheet]
The obtained electrophotographic transfer sheet was conditioned in an ISO environment (23 ° C.-50% RH) for 24 hours, and Clark stiffness was measured according to JIS P 8143. The results are shown in Table 1.

[Measurement of surface electric resistance value of electrophotographic transfer sheet]
After the obtained electrophotographic transfer sheet was stored for 10 hours under the following low humidity condition, normal humidity condition and high humidity condition, the surface electrical resistance was measured using an electric resistance meter R12704 (manufactured by Advantest). The low humidity condition, normal humidity condition, and high humidity condition are as follows. The results are shown in Table 2.
The low humidity condition, normal humidity condition, and high humidity condition are as follows.
Low humidity conditions: temperature 10 ° C, relative humidity 30% RH
Normal humidity conditions: temperature 20 ° C, relative humidity 65% RH
High humidity conditions: temperature 30 ° C, relative humidity 85% RH

[Evaluation of recording suitability of transfer sheet for electrophotography]
The resulting electrophotographic transfer sheet was stored for 10 hours under low humidity, normal humidity, and high humidity conditions, and then image-recorded under each environment using a color copier LBP2040N (manufactured by Canon Inc.) and visually observed. The image quality was visually evaluated according to the following evaluation criteria. The results are shown in Table 3.
The low humidity condition, the normal humidity condition, and the high humidity condition are the same as the above-described measurement of the surface electric resistance.
A: Good toner transferability and high image density. Extremely good quality has been obtained.
：: Good toner transferability and sufficiently high image density. There is no practical problem and the quality is excellent.
Δ: The toner transferability was slightly uneven, and the image density was poor. There is a problem in practical use.
X: The toner transferability is considerably uneven, and the image density is extremely poor. There is a problem in practical use.

[Evaluation of runnability of transfer sheet for electrophotography]
The obtained electrophotographic transfer sheet was subjected to image recording using a color copying machine LBP2040N (manufactured by Canon Inc.) in an ISO environment, and 100 sheets were printed, and the number of running troubles was confirmed. The results are shown in Table 4.
The low humidity condition, the normal humidity condition, and the high humidity condition are the same as the above-described measurement of the surface electric resistance.
：: Occurrence of running trouble is 0 times.
○: Number of occurrences of traveling trouble is 2 or less. No problem in practical use.
Δ: Number of occurrences of traveling trouble 5 or less. There is a problem in practical use.
×: Number of occurrences of traveling trouble 10 or more times. There is a problem in practical use.

[Evaluation of toner peeling due to immersion of printing section]
The obtained electrophotographic transfer sheet was stored under normal humidity conditions for 10 hours, and then image recording was performed using a color copying machine LBP2040N (manufactured by Canon Inc.) under normal temperature environment. Further, the printed sample is immersed in water for 1 minute, taken out, and the printed portion is rubbed with a finger. The peeling degree of the toner was visually evaluated according to the following evaluation criteria. The results are shown in Table 4.
A: No toner peeling.
：: toner peeling was slightly observed, but there was no practical problem.
Δ: The toner peeled slightly, and there was a problem in practical use.
×: toner peeling is remarkable, and there is a problem in practical use.

Claims (9)

  A sheet-like support which is a laminate in which a thermoplastic resin film layer (A) is bonded and laminated on at least one surface of a paper base material or a core material layer (B) composed of a thermoplastic polyester resin film; A resin receiving layer having a conductive metal oxide as a main component is provided on the surface of the resin film layer (A), and the Clark stiffness in the lateral direction measured according to JIS P 8143 is 12 cm or more. Transfer sheet for electrophotography.   2. The electrophotographic transfer sheet according to claim 1, wherein the thermoplastic resin film is a synthetic paper composed of a stretched film containing a polyolefin resin and an inorganic pigment as main components.   The electrophotographic transfer sheet according to claim 1, wherein the conductive metal oxide is obtained by doping impurities into the metal oxide to impart semiconductivity.   The electrophotographic transfer sheet according to claim 3, wherein the conductive metal oxide is in a form coated on a surface of a base material.   The transfer sheet for electrophotography according to claim 1, wherein the conductive metal oxide is tin oxide containing antimony as an impurity.   6. The transfer sheet for electrophotography according to claim 5, wherein the conductive metal oxide has a base material surface coated with the tin oxide.   The electrophotographic transfer sheet according to claim 4, wherein the base material is a needle-like titanium oxide having a major axis of 1 to 15 μm and a minor axis of 0.05 to 0.5 μm.   The electrophotographic transfer sheet according to any one of claims 1 to 7, wherein the toner receiving layer further contains at least one pigment. The electrophotographic transfer sheet according to any one of claims 1 to 7, wherein a surface electric resistance value of the toner receiving layer is 1 x 10 < ⁵ > to 1 x 10 < ¹² > [Omega] /-.