JP2000292961A - Transfer sheet for electrophotography - Google Patents

Abstract

(57) [Summary] [Problem] When used as a material to be transferred in a copier and a printer of an indirect dry electrophotography system, the surface gloss of the image is not uneven, the image gloss is suppressed to a low level, the graininess is excellent, and the image is excellent. Provided is a transfer sheet for electrophotography, which provides a full-color image excellent in anti-peeling properties, and has excellent blocking resistance and running properties. SOLUTION: When a plurality of electrophotographic transfer sheets having a sheet-like support and a porous toner receiving layer formed on at least one surface thereof are overlapped with each other, JIS-P8147 (horizontal method) is used. ) Is controlled so that the standard deviation of the coefficient of static friction according to (1) is 0.05 or less. Glossiness of toner receiving layer (JISZ 874
(1,75 degrees) is preferably 10 to 30%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transfer sheet useful as a material to be transferred in an indirect dry electrophotographic copying machine and printer. More specifically, the present invention can receive a full-color image when used as a transfer material in an indirect dry electrophotographic copying machine and a printer, and the transferred image has a moderate gloss. The present invention relates to a transfer sheet which has no uneven surface gloss, is excellent in graininess, has no image peeling, and has excellent blocking resistance and running property in a copying machine and a printer.

[0002]

2. Description of the Related Art Hitherto, along with the colorization and digitization of a transferred image obtained by an electrophotographic copying machine or a printer, higher image quality of an electrophotographic system has been studied. In particular, in electrophotographic full-color copying machines and printers, digitization of image input / output has been advanced in order to obtain high-quality images, and image input methods, input image processing methods, developing methods, transfer methods, and fixing have been developed. The law has been significantly improved. Further, developers and photosensitive image forming materials have also been improved so as to support digital high-definition and high-color-forming color recording.

However, in an electrophotographic full-color copying machine or printer, if a toner having a particle size of several μm to several tens μm is used and high-quality paper or coated paper is used as an image support, the toner in a transferred image may be deteriorated. Rises, and the gloss increases in the high-density portions of the toner, and decreases in the low-density portions, resulting in uneven gloss on the surface of the toner image. There is a problem of poor quality. Also, in toner transfer, unlike photography or printing, an image step is generated by toner, so that a problem that unevenness of an image gives a stranger to a viewer of the image has been recognized.

On the other hand, in an electrophotographic full-color copying machine and a printer, a toner having a high sharp-melt property is used in order to enhance the melting property and color mixing property of the toner during heat fixing. However, when this type of toner is applied to plain paper, the molten toner tends to excessively enter the voids between the fibers of the paper, and as a result, the graininess of the image deteriorates. Also,
When coated paper is used, since the penetration of the molten toner in the thickness direction of the coated paper is small, the molten toner spreads on the surface of the coated paper, and thus the graininess of an image is deteriorated. Therefore, even when using plain paper or using coated paper,
There is also a problem that the quality of the obtained image is inferior to the photographic image or the printed image.

In order to solve the above problem, Japanese Patent Application Laid-Open No.
JP-A-171266 discloses a method in which a porous coating layer having voids for absorbing toner is provided on an image support, and the gloss of the image is reduced by embedding the toner in the porous coating layer using a fixing device. A method is disclosed. However, the method of embedding the toner in the porous coating layer can suppress the swelling of the toner to some extent.
A transfer sheet having a porous coating layer easily adheres to a fixing device at the time of fixing and winds easily, thereby causing a problem that the fixing device is broken and a normal image cannot be obtained.
When this transfer sheet is used, image defects such as discharge marks may occur in a low humidity environment.

In Japanese Patent Application Laid-Open No. 5-297621, a small amount of pigment is coated on a base paper to form a coating layer having regular voids on the paper surface, and the toner is placed inside the voids. A method for fixing is disclosed. However, a sufficient amount of voids cannot be ensured by only applying a small amount of pigment, so that in the transfer of a secondary color or a tertiary color with a large amount of transfer toner, the toner can be sufficiently absorbed. In particular, solid areas cannot avoid toner swelling,
The gloss is high, and gloss unevenness and graininess cannot be improved.

Further, Japanese Patent Application Laid-Open No. 8-171306 discloses a method of controlling the gloss of an image by fixing conditions of an image forming apparatus. However, in the method of controlling the gloss of the image by the fixing condition, it is not possible to eliminate the step between the image portion and the blank portion, so that the unevenness remains on the screen, and the uncomfortable feeling of the image quality cannot be eliminated.

One of the inventors of the present invention solves the above-mentioned problem by providing, in Japanese Patent Application Laid-Open No. 9-315021, a porous toner receiving layer made of a resin on at least one surface of a support. When used as a transfer material in electrophotographic copying machines and printers, there is no unevenness in the surface gloss of the image, low image gloss, no discomfort due to the height of the toner image, excellent granularity, low humidity environment We have proposed an electrophotographic transfer sheet capable of obtaining an excellent full-color image without generating discharge marks below.

However, when a porous toner receiving layer containing a resin as a main component is used, problems such as a decrease in blocking resistance and a deterioration in running property of the obtained transfer sheet may occur. In addition, since the resin is a main component and the cushioning property is high, the porous toner receiving layer may show stickiness, and thus the blocking resistance is reduced. That is, when the transfer sheets are overlapped, the adhesiveness between the front surface (the surface of the toner receiving layer) and the back surface of the transfer sheets that are in contact with each other increases, and the porous coating structure of the toner receiving layer is destroyed or the copy is performed. Adhesion between the paper feed roll of the machine or printer and the transfer sheet increases, making it difficult to perform stable paper feeding and discharging operations, resulting in problems such as reduced image quality or the inability to form images. May occur.

[0010]

INDUSTRIAL APPLICABILITY The present invention is useful as a transfer material for an indirect dry electrophotographic copying machine and a printer, and can receive a full-color image. It is intended to provide a transfer sheet that is not uneven in surface gloss, has excellent graininess, does not have image peeling, and has excellent blocking resistance and running properties in a copying machine and a printer. is there.

[0011]

According to the present invention, there is provided an electrophotographic transfer sheet comprising a sheet-like support, a porous sheet formed on at least one surface thereof, having a large number of fine pores, and receiving toner. An electrophotographic transfer sheet having a toner receiving layer, wherein when a plurality of the electrophotographic transfer sheets are overlapped, JIS-P8
147 (horizontal method), the standard deviation of the coefficient of static friction is 0.
05 or less. In the electrophotographic transfer sheet of the present invention, the coefficient of static friction is 0.1.
It is preferably in the range of 2 to 0.9. In the transfer sheet for electrophotography of the present invention, an anti-curl layer may be formed on the back surface of the sheet-like support. In the electrophotographic transfer sheet of the present invention, the porous toner receiving layer preferably has a glossiness (incidence, reflection angle = 75 degrees) of 10 to 30% as measured according to JIS Z8741. In the electrophotographic transfer sheet of the present invention,
The porous toner-receiving layer is coated with a bubble-containing resin liquid prepared by mechanically stirring a resin-containing liquid containing a water-dispersible polyurethane resin as a main component on at least one surface of the sheet-like support. It is preferably formed by drying and has a large number of fine pores. In the electrophotographic transfer sheet of the present invention, the average pore diameter of the fine pores on the surface of the porous toner receiving layer is 0.5 to 50 μm.
m is preferable. In the electrophotographic transfer sheet of the present invention, the porous resin-containing liquid for a toner receiving layer further contains an additional polymer, and the compatibility parameter of the additional polymer is larger than the compatibility parameter of the water-dispersible polyurethane resin. It is preferably 3.0 to 10.0 higher. In the transfer sheet for electrophotography of the present invention,
It is preferable that the heat-sealing start temperature of the water-dispersed polyurethane resin in a heat sealing test is 90 to 150 ° C. In the transfer sheet for electrophotography of the present invention, it is preferable that the water-dispersed polyurethane resin has a glass transition temperature of 30 to 100 ° C. In the transfer sheet for electrophotography of the present invention, the water-dispersible polyurethane resin forms an insoluble film in a film and exhibits an insoluble residual ratio of 60 to 100% by weight when immersed in a tetrahydrofuran solvent at 25 ° C. for 24 hours. Preferably, it is

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The present inventors have found that in the formation of an image by electrophotography, in particular, in the formation of a full-color image, prevention of unevenness in gloss of the image and appropriate adjustment of gloss, elimination of discomfort due to image height, and graininess In order to achieve an improvement in the transfer resistance and the blocking resistance and running property of the transfer sheet, the structure, material properties, and friction between the superposed transfer sheets of the porous toner receiving layer of the electrophotographic transfer sheet are improved. Coefficients and the like are studied diligently, and as a result, the standard deviation of the static friction coefficient (according to JIS-P8147, horizontal method) between the contact surfaces of the superposed transfer sheets (sample (data) standard deviation)
Is controlled to 0.05 or less, and the above problem can be solved, and the present invention has been completed.

The sheet-like support used in the electrophotographic transfer sheet of the present invention may be made of paper such as paper containing pulp as a main component, coated paper, laminated paper and the like, and woven cloth and non-woven cloth and the like. Can be formed. Further, as a sheet-like support, plastic films such as polyolefins, methacrylates, and cellulose acetate; synthetic papers composed of polyolefins and pigments; and porous synthetic resin films such as foamed polyethylene terephthalate films and foamed polypropylene films. Etc. can also be used. When papers containing pulp as a main component, for example, coated paper, are used as a support, the obtained transfer sheet has an advantage that it can be recycled.

The paper used as the sheet-like support in the electrophotographic transfer sheet of the present invention preferably has a basis weight specified in JIS P8124 in the range of 70 to 180 g / m ^2. Preferably 80 to 150 g / m
Suitably within the range of ² . Specifically, high-quality paper, medium-quality paper, plain paper such as recycled paper, coated paper for printing, art paper, cast-coated paper, and the like can be used as the sheet-like support, but are not limited thereto. is not. When the basis weight of the support paper is less than 70 g / m ² ,
The rigidity and resilience of the transfer sheet become insufficient. As a result, when a roll-type fixing device is used, the transfer sheet is likely to be wound around the roll, and the occurrence of curl after fixing the toner becomes remarkable. There is. Conversely, if the basis weight exceeds 180 g / m ² , the amount of heat required to embed the toner in the receiving layer of the transfer sheet becomes excessive,
There is a possibility that uneven gloss may occur.

In particular, the present invention provides a so-called coated paper obtained by applying a paint containing a pigment and an adhesive as a main component on the surface of a paper and smoothing the coated surface with a super calender or the like. It can be suitably used as a sheet-like support for a transfer sheet. In the present invention, when the coated paper is used as a sheet-like support, when a porous toner receiving layer is formed by coating a bubble-containing resin liquid thereon,
The surface of the toner receiving layer can be easily flattened. As a result, the adhesion between the transfer sheet thus obtained and the toner fixing roll in the copying machine is improved, and the occurrence of mottle (speckles and mottle) is suppressed. Can be.

The Beck smoothness of the sheet-like support used in the electrophotographic transfer sheet of the present invention is preferably 20 to 5000 seconds, more preferably 40 to 4000 seconds.
A range of seconds is appropriate. When the coated paper is used as a sheet-like support and the surface Bekk smoothness exceeds 5000 seconds, the porous toner-receiving layer formed by applying the bubble-containing resin liquid is used as a sheet-like support. Since the anchoring effect on the surface is insufficient, the support and the porous toner receiving layer may peel at the interface between them.
If the Beck smoothness is less than 20 seconds, it is difficult to ensure the smoothness of the surface of the porous toner receiving layer due to the roughness of the support surface, or the thickness of the coating layer is not sufficient. In some cases, the toner may be uniform, or uneven transfer of toner may occur, resulting in mottle.

The transfer sheet for electrophotography of the present invention has, as a toner receiving layer, a coating layer comprising a porous film containing a transparent resin as a main component on at least one surface of a sheet-like support. The average pore diameter of the fine pores on the surface of the toner-receiving layer is preferably in the range of 0.5 to 50 μm, more preferably 3 to 50 μm.
In this way, by forming a large number of fine voids in the toner receiving layer, the toner for forming a toner image is absorbed into the porous toner receiving layer at the time of fixing, and high gloss is also achieved in a solid image portion. It is possible to suppress and improve uneven gloss. Further, the phenomenon that the toner spreads on the surface of the toner receiving layer due to the absorption of the toner can be suppressed, and an image having excellent granularity can be formed. Hereinafter, the porous toner receiving layer is referred to as a porous toner receiving layer.

When the average pore diameter of the fine pores on the surface of the porous toner receiving layer is less than 0.5 μm, the amount of voids for toner absorption becomes insufficient, and thus the toner receiving layer of the molten toner in the high-density image area becomes insufficient. The penetration in the thickness direction becomes insufficient, so that the maximum glossiness and the gloss difference (maximum glossiness-minimum glossiness) of the image area cannot be suppressed low, and it is impossible to secure granularity. May be. When the average pore diameter of the fine pores on the surface of the porous toner receiving layer exceeds 50 μm, the amount of voids becomes excessive, and the molten toner tends to enter the voids excessively, so that sufficient granularity of the image is secured. In some cases, the density of the toner receiving layer is excessively low, and therefore, in a low humidity environment, the occurrence of discharge marks, which are image defects during transfer, may increase. The pore diameter of the fine pores on the surface of the porous toner receiving layer can be measured by using an optical microscope or a scanning electron microscope photograph and an image analyzer.

The porous film constituting the toner receiving layer of the transfer sheet of the present invention contains a water-dispersible polyurethane resin or a mixture of a water-dispersible polyurethane resin and a pigment as a main component. The liquid material containing the components can be mechanically stirred to form a large number of fine air bubbles, and the air-containing resin liquid can be applied on a support and dried to form.

Here, the water-dispersed polyurethane resin is a urethane-based polymer or urethane-based oligomer which is stably dispersed in an aqueous emulsion, a colloidal dispersion (microemulsion), or an aqueous solution in water as a medium. Things. Further, the water-dispersed polyurethane resin in the present invention may contain a polyurethane polymer as its component, and may contain other resin components such as acrylate, styrene, and acrylonitrile as a copolymer component or a mixed component. May be.

In the production of the water-dispersible polyurethane resin, the main reaction is a nucleophilic reaction of the hydroxyl group of the polyol compound with respect to the carbon having a low electron density contained in the isocyanate group of the isocyanate compound. Same as the reaction. Isocyanate compounds generally used to produce polyurethane resins include aliphatic, alicyclic and aromatic polyisocyanate compounds, such as 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 4,4-diphenylmethane diisocyanate, phenylene diisocyanate, xylylene diisocyanate, tetramethyl xylylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, lysine diisocyanate ester, 1,4-cyclohexylene diisocyanate, 4,4′-dicyclohexyl methane diisocyanate, , 3'-Dimethoxy-4,4'-biphenylenediisocyanate, 1,5
-Naphthalenediisocyanate, 1,5-tetrahydronaphthalenediisocyanate, isophorone diisocyanate and the like.

The polyol compound used for producing the polyurethane resin includes, for example, ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, and 1,2-butylene glycol. , 1,
3-butylene glycol, 1,4-butylene glycol, neopentyl glycol, 1,6-hexanediol, hydrogenated bisphenol A, low molecular weight polyol compound (for example, hydroxyalkoxybisphenol A, etc.)
Adducts of ethylene oxide and / or propylene oxide, polyether polyols such as polyethylene glycol, polypropylene glycol, polyethylene / propylene glycol and polytetramethylene glycol; low molecular weight polyols; and polybasic acids such as succinic acid, glutaric acid, Adipic acid, sebacic acid, phthalic acid, isophthalic acid, terephthalic acid, tetrahydrophthalic acid, endmethylenetetrahydrophthalic acid, hexahydrophthalic acid, and the like, or condensates with carbonic acid, such as polyester polyol, polycarbonate polyol, and polycaprolactone. Can be

As a method for dispersing the polyurethane in water, there are cases where an emulsifier is used and cases where it is not used. A typical aqueous dispersion method is shown below, but any method may be used. As a method of using an emulsifier, for example, a phase inversion emulsification method, a method of chain extension in an emulsified state,
And a method using a blocked isocyanate.

In the phase inversion emulsification method, a polyurethane is synthesized in an organic solvent from an oligomer polyol which is a hydrophobic raw material, an organic polyisocyanate and, if necessary, a chain extender such as a low molecular weight polyol or a polyamine. A polyurethane emulsion can be obtained by preparing an organic solvent solution and gradually adding an emulsifier aqueous solution thereto. Examples of the emulsifier include anionic surfactants such as sodium alkyl sulfate, sodium alkylbenzene sulfonate, and sodium dioctyl sulfosuccinate; nonionic surfactants such as ethylene oxide adducts of long-chain alcohols or alkylphenols; and quaternary ammonium salts. And a cationic surfactant represented by

The method of producing a polyurethane dispersion in which the chain is extended in an emulsified state is different from an emulsion polymerization method of a vinyl monomer or the like in that a urethane prepolymer having an isocyanate group is reacted in an emulsifier aqueous solution with a low molecular weight diamine in an emulsified state. This is a method to extend the chain. In this method, to obtain a stable aqueous emulsion, it is effective to use a monofunctional compound such as n-butylamine as a polymerization degree regulator.

In the method for producing a polyurethane dispersion using a blocked isocyanate, oximes, lactams and tertiary compounds having the property of reacting with an isocyanate group to form an amide compound which is a blocked isocyanate and regenerating the isocyanate group by heating are disclosed. Blocking agents such as secondary alcohols, phenols, acetylacetone, acetoacetate, malonic diester, and sodium bisulfite are used. In this method, a blocking agent is allowed to react with a urethane polymer having a free isocyanate group in an organic solvent to protect the isocyanate group.
A stable emulsion can be obtained by emulsifying and dispersing in a surfactant aqueous solution together with a polyfunctional crosslinking agent such as N ′, N′-tetrakis (2-hydroxypropyl) ethylenediamine.

Next, as a method for producing a polyurethane dispersion liquid without using an emulsifier, for example, a method using a water-soluble raw material, a self-emulsification method, and the like are generally known. In the method using a water-soluble raw material, a water-soluble oligomer such as polyethylene glycol is used as a main raw material polyol constituting the polyurethane, and this is chain-extended with an organic polyisocyanate. The polyurethane obtained by this method has insufficient water resistance as it is, and is difficult to be put to practical use. In order to improve the water resistance of such a polyurethane, acrylic acid is grafted onto the polyurethane to bond some carboxyl groups to the polyurethane main chain, and then zinc, calcium, magnesium is added to the graft product. And a method of reacting a salt of a polyvalent metal such as aluminum or an alkoxide to form a metal crosslink, or a method of grafting a reactive acrylic monomer such as N-methylolacrylamide to impart crosslinkage by a methylol group. A method for improving water resistance can be used.

In the self-emulsifying method, in order to synthesize a cationic self-emulsifying polyurethane emulsion, a urethane prepolymer obtained from a hydrophobic polyol compound and an organic polyisocyanate compound and having a free isocyanate group is treated with N 2 A tertiary amino group is introduced by extending the chain with an alkyl dialkanolamine so as to contain 0.1% by weight or more of nitrogen in the main chain of the polyurethane; Neutralized with an aqueous solution of, or the urethane polymer is chain-extended so that a small amount of free isocyanate groups remain, and at the time of neutralization, the remaining isocyanate groups are reacted with water as a medium, Further polymerizes. There is also a method in which a tertiary amino group in the main chain is quaternized with diethyl sulfate, methyl iodide, or the like to cationize the tertiary amino group.Moreover, a diisocyanate / bromohydrin compound and dimethylalkanolamide are simultaneously reacted to extend the chain and form a salt. And a method of simultaneously forming a crosslinked structure and forming a salt using 1,4-bischloromethylbenzene as a quaternizing agent.

On the other hand, an anionic self-emulsifying polyurethane emulsion is prepared by reacting an amino group-containing polyurethane compound with a lactone, a sultone or a cyclic carboxylic acid anhydride, or a urethane prepolymer with a diaminosulfonic acid or It is obtained by reacting a diaminocarboxylic acid and introducing a sulfonic acid group or a carboxylic acid group of the acid so as to form a side chain of a polymer chain. As a method of introducing a sulfonic acid group into a polymer chain, there is also a method of directly sulfonating an aromatic polyisocyanate. In addition to the above basic production methods, there is also a method using a hydrophobic reaction or a cross-linking reaction of a hydrophilic group in a polymer. For example, a method of crosslinking between urethane bonds of polyurethane molecules with methylene groups using formaldehyde, a method of introducing a halohydrin structure into a polyurethane chain to impart thermosetting properties to polyurethane, crosslinking with an epoxy compound, or N-methylol There are methods such as crosslinking with a compound, crosslinking with an aziridine compound, and hydrophobization of a carboxyl group.

The water-dispersed polyurethane resin used in the present invention preferably has a heat fusion initiation temperature in a heat sealing test in the range of 90 to 150 ° C., more preferably 100 to 140 ° C. Particularly preferably, it is 120 to 130 ° C. By using such a water-dispersible polyurethane resin, a transfer sheet having extremely excellent blocking resistance even at high temperatures can be obtained. When the heat fusing start temperature is lower than 90 ° C., a coating material containing a large number of fine bubbles in a water-dispersed polyurethane mixed resin liquid is coated on a sheet-like support by mechanical stirring. The porous toner receiving layer formed by drying may show stickiness (adhesiveness), and the blocking resistance is reduced, that is, the adhesiveness between the toner receiving layer and the back surface of the transfer sheet increases, and the porous toner receiving layer becomes porous. The coating structure is destroyed, or the adhesiveness between the transfer roll and the paper feed roll to the copier or printer is increased, making it difficult to stably feed and discharge paper, deteriorating image quality, or reducing image quality. In some cases, troubles such as the inability to form an image may occur. On the other hand, if the heat fusing start temperature exceeds 150 ° C., the obtained porous toner receiving layer itself becomes brittle, and the resin film is broken in the porous toner receiving layer, which may cause local peeling of an image. is there. However, the foaming ratio (weight ratio of foamed resin-containing liquid and unfoamed resin-containing liquid in the same volume) must be optimized, or two or more types of water-dispersed polyurethane resins must be mixed at an appropriate ratio to optimize the strength. In some cases, peeling of the image can be avoided.

In order to measure the heat-sealing start temperature of the water-dispersed polyurethane resin by the heat sealing test, the water-dispersed polyurethane resin liquid is coated on one surface of a high-quality paper, dried, and then obtained. A piece of a predetermined area is cut out from the polyurethane resin liquid-coated material, and one surface of an uncoated high-quality paper section having the same size as that of the piece is superimposed on the polyurethane resin liquid-coated surface of the section, and a thermal gradient tester is used. Using a press (manufactured by Toyo Seiki Co., Ltd.), the two are pressed at a predetermined pressure while heating at a predetermined temperature, and the state of heat fusion is evaluated. That is, when the high-quality paper section is slowly peeled off from the sample heated and pressed at each temperature by changing the heating temperature in the above test, the lowest temperature at which the paper layer on the surface of the high-quality paper is broken due to adhesion with the polyurethane resin at the interface. Is the heat fusing start temperature. The heating temperature in the above test is generally changed in the range of 50 to 180 ° C., and the pressure bonding conditions are a pressure of 3 kg / cm ² and a time of 5 seconds. The area of the test section is 50 cm ² . Further, the thickness of the polyurethane resin film is preferably set to 200 ± 10 μm.

In the present invention, the method for controlling the heat-sealing temperature in the heat sealing test of the water-dispersed polyurethane resin is not particularly limited, but generally, the glass transition temperature (Tg) of the polyurethane resin or the tetrahydrofuran-insoluble. By optimizing the amount, a desired heat fusing temperature can be easily achieved.

The water-dispersible polyurethane resin used in the present invention preferably has a Tg in the range of 30 to 100 ° C. If the Tg is lower than 30 ° C., the porous toner receiving layer may show stickiness (adhesion), and the blocking resistance may be insufficient. On the other hand, if the Tg exceeds 100 ° C., the porous toner receiving layer itself becomes brittle, and it may be difficult to form a good image due to local peeling of the image. However, it is necessary to optimize the expansion ratio when forming the toner receiving layer, or to mix two or more types of water-dispersed polyurethane resins at an appropriate ratio to form a toner receiving layer having appropriate strength from the mixture. In some cases, peeling of the image can be avoided.

The method for controlling the Tg of the water-dispersed polyurethane resin to a desired value is not particularly limited, but generally, a diol having a molecular weight of 200 or less is contained in the polyol component used for producing the polyurethane resin. It can be easily achieved by containing the compound in a ratio of 1 to 30% by weight. Such diol compounds include ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2
-Butylene glycol, 1,3-butylene glycol,
Examples thereof include 1,4-butylene glycol, neopentyl glycol, 1,6-hexanediol, and the like.

As the water-dispersed polyurethane resin used in the present invention, a film is formed from the water-dispersed polyurethane resin, and when the film is immersed in a tetrahydrofuran solvent at 25 ° C. for 24 hours, the film is cured.
It preferably has an insoluble residual ratio of from 100 to 100% by weight, more preferably 80 to 100% by weight.
It is. When the insoluble residual ratio is less than 60% by weight,
The resulting porous toner receiving layer may exhibit stickiness (adhesion), and thus may have insufficient blocking resistance. Among various solvents, for example, acetone and toluene hardly dissolve the water-dispersible polyurethane of the present invention.In particular, by using a tetrahydrofuran solvent, the degree of crosslinking of the water-dispersible polyurethane resin is controlled from the insoluble residual ratio. It turned out to be possible.

In general, when the percentage of insoluble residue in a tetrahydrofuran solvent increases, the porous toner receiving layer itself becomes brittle, causing local exfoliation of the image, which may make it difficult to form a good image. . However, in the present invention, for example, to optimize the expansion ratio,
By mixing and using more than one type of water-dispersible polyurethane resin at an arbitrary ratio, the strength of the toner receiving layer can be optimized and the like, so that a decrease in toner transferability and peeling of the coating film can be prevented.

The method of controlling the tetrahydrofuran-insoluble residual ratio is not particularly limited, but generally,
This can be easily achieved by crosslinking the molecules of the water-dispersed polyurethane resin. For example, the polyurethane resin can be appropriately crosslinked using formaldehyde, an epoxy compound, an N-methylol compound, an aziridine compound, or the like. The above control can also be easily achieved by including a triol compound or a tetraol compound at a ratio of 1 to 30% by weight in the polyol component used for producing the polyurethane resin. Examples of such a triol compound include glycerin, triethanolamine and the like. Pentaerythritol can be used as the tetraol compound.

Specific examples of the water-dispersible polyurethane resin used in the present invention include, for example, NeNe, trademark: Ne
oRez R-9679, R-966, R-9030,
R-960, R-986, Dainippon Ink and Chemicals, Inc.
Trade name: IP-27, and Asahi Denka Kogyo Co., Ltd., trade name: HUX-381.

The water-dispersible polyurethane resin used in the present invention may be mixed with different types of water-dispersible or water-soluble polymers so as to meet the required level of recording performance or the performance of the recording apparatus. It is possible and can be used in combination with an additional polymer comprising at least one of a water-dispersible polymer and a water-soluble polymer as exemplified below. For example, water-soluble additional polymers include polyvinyl alcohols and derivatives thereof (eg, carboxy-modified polyvinyl alcohol and silyl-modified polyvinyl alcohol), starches and derivatives thereof (eg, dextrin, carboxymethyl starch, etc.) of various molecular weights and degrees of saponification, And, for example, various modified starches such as oxidized starch, methoxycellulose, carboxymethylcellulose, methylcellulose, cellulose derivatives such as ethylcellulose, sodium polyacrylate, polyvinylpyrrolidone, acrylamide-acrylate copolymer, acrylamide- Acrylic ester-methacrylic acid ester copolymer, styrene-maleic anhydride copolymer alkali salt, polyacrylamide and derivatives thereof (for example, cation Sex polyacrylamide and anionic modified polyacrylamide, etc.), and polyethylene glycol or the like is used, and as the additional polymer water dispersible, polyvinyl acetate, styrene - butadiene copolymer,
Acrylonitrile-butadiene copolymer, polyacrylate, vinyl chloride-vinyl acetate copolymer, polybutyl methacrylate, ethylene-vinyl acetate copolymer,
Latexes such as styrene-butadiene-acrylic copolymers and polyvinylidene chloride are used, and glue, casein, soy protein, gelatin, sodium alginate and the like can be used.

Here, the glossiness of the porous toner receiving layer can be controlled by selecting the additional polymer to be mixed with the water-dispersed polyurethane resin. For example, the glossiness (75) based on JIS Z8741 of the porous toner receiving layer is used.
Degree) is preferably a matte tone of 10 to 30%.

It has been found that the glossiness of the porous toner receiving layer is contributed by the compatibility parameter of the additional polymer mixed with the water-dispersible polyurethane resin. That is, when the compatibility parameter of the additional polymer mixed with the water-dispersed polyurethane resin is 3.0 to 10.0 higher than that of the water-dispersed polyurethane resin, the J of the porous toner receiving layer is reduced.
The glossiness (75 degrees) based on lsZ8741 is 10 to
We found that we could control it to 30%. When the difference in the compatibility parameter between the additional polymer mixed with the water-dispersible polyurethane resin is smaller than 3.0, the compatibility of the additional polymer mixed with the water-dispersible polyurethane resin is good, and the porous toner after the formation of the coating film is received. Since a so-called sea-island structure is not easily formed in the resin portion on the surface of the layer, the diffusion of reflected light is small, and the glossiness is higher than 30%. On the other hand, when the difference in the compatibility parameter is larger than 10.0, an undesired phenomenon such as separation of the paint into two layers may not be achieved at the stage of preparing the paint, and a uniform mixing state may not be maintained.

Here, carboxymethylcellulose (for example, AG gum manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), polyacrylic acid-based compound as an additional polymer whose compatibility parameter is 3.0 to 10.0 higher than that of the water-dispersible polyurethane resin. (For example, Modicol VDS manufactured by San Nopco) or the like can be used. The addition amount (solid content) of the additional polymer for adjusting glossiness is preferably 10% or less (weight) based on the weight of the solid content of the water-dispersible polyurethane resin.

The compatibility parameters of the water-dispersible polyurethane resin and the additional polymer are determined by the method described in Trans. Faraday Soc., 195.
It can be determined experimentally by comparing the water-dispersible polyurethane resin and the additional polymer to be mixed with the compatibility of a solvent having a known compatibility parameter, using the method described in Vol. That is, a plurality of solvents are selected such that the difference in their compatibility parameters is at regular intervals, and the compatibility parameters of the water-dispersed polyurethane resin or the additional polymer to be mixed are determined for two types of solvents in which both are best compatible. It was in the middle. When the compatibility parameter cannot be measured by the above method because there is no compatible solvent, the structural formula of the water-dispersible polyurethane resin or the additional polymer is specified, and Polym. Eng. Sci., Vol.
It can be obtained by calculation using the method described on page 7.

In the transfer sheet of the present invention, the porous toner receiving layer may contain a pigment. Examples of such pigments include zinc oxide, titanium oxide, calcium carbonate, silicic acid, silicate, clay, talc, mica, calcined clay, aluminum hydroxide, barium sulfate, lithopone,
And inorganic pigments such as colloidal silica, polystyrene, polyethylene, polypropylene, epoxy resin, and true spheres such as styrene-acrylic copolymers, hollow or organic pigments called plastic pigments of a type processed into various shapes and Starch powder, cellulose powder and the like can be used. These pigments can be used alone or as a mixture of two or more, if necessary.

Since the resin coating film forming the porous toner receiving layer in the transfer sheet of the present invention has essentially no strong coating film strength, as inferred from its porous structure, When various pigments are added thereto, the strength of the coating film is further reduced, and as a result, troubles such as image peeling may occur as described above. Therefore, when various kinds of pigments are contained in the water-dispersed polyurethane resin-containing liquid to form the porous toner receiving layer, it is necessary to use an appropriate mixing ratio in consideration of the overall quality of the transfer sheet. Is natural. Generally, the pigment content of the toner receiving layer is preferably 80% by weight or less, more preferably 50% by weight or less, based on the weight of the toner receiving layer. In the resin before foam formation or in the liquid containing the mixture of the resin and the pigment, a known viscosity modifier, dispersant, dye, water-proofing agent, lubricant, crosslinking agent, and / or A plasticizer or the like can be added.

In the transfer sheet of the present invention, the coating amount of the porous toner receiving layer is preferably in the range of ^{2 to} 40 g / m ² , more preferably 5 to 20 g / m ² . When the coating amount of the porous toner receiving layer is less than 2 g / m ² , it may be difficult for the porous toner receiving layer to sufficiently cover the surface roughness of the sheet-like support,
For this reason, a transfer sheet surface having appropriate smoothness may not be obtained, or a porous toner receiving layer having sufficient heat insulating properties and compressive deformation properties may not be obtained. On the other hand, if it exceeds 40 g / m ² , the thickness of the porous toner receiving layer becomes excessively large, and the bonding strength in the porous toner receiving layer is reduced. In some cases, troubles such as peeling of the layer occur, and a good image cannot be formed. Therefore, the coating amount of the porous toner receiving layer may be appropriately selected so as to conform to the desired performance of the transfer sheet.

In order to appropriately control the surface electric resistance of the porous toner receiving layer of the transfer sheet of the present invention,
What is necessary is just to mix | blend a conductive agent in a resin containing liquid, and it is usually 1 * 10 < ⁸ > -1 * 10 < ¹² > ohm, Preferably it is 1 * 1.
0 ⁸ to 1 × 10 ¹¹ Ω, more preferably 1 × 10 ⁹ to 1 ×
It can be adjusted in the range of 10 ¹¹ Ω. When the surface electric resistance value is lower than 1 × 10 ⁸ Ω, the transfer of the toner to the transfer sheet in a high humidity environment becomes insufficient, and the density is easily reduced and the density is likely to be uneven. If it exceeds 1 × 10 ¹² Ω, in a low-humidity environment, when the transfer sheet is peeled off from the photoreceptor after toner transfer, the toner is liable to be scattered, thereby causing image disorder and deteriorating image quality. May be. As the conductive agent, for example, sodium chloride, potassium chloride, salts of styrene / maleic acid copolymer, quaternary ammonium salts, and the like are preferably used.

In the transfer sheet of the present invention, the porous toner receiving layer is formed by adding a large number of microbubbles to the above-mentioned water-dispersible polyurethane resin liquid or a coating liquid comprising a water-dispersible polyurethane resin and a pigment as main components. And applying the same to a sheet-like support, followed by drying. Air bubbles are formed in the coating liquid,
There are no particular restrictions on the method, equipment, and coating method used.

The method of generating and dispersing air bubbles in the resin-containing coating solution (foaming method) is used, for example, for a stirrer having a stirring blade rotating while carrying out planetary motion, for example, a foaming machine for confectionery, and generally for emulsification and dispersion. A stirrer such as a homomixer and a Cowles dissolver, or a device that can mechanically stir these while continuously feeding a mixture of air and a resin-containing liquid into a closed system to disperse and mix air as fine bubbles,
For example, a continuous foaming machine manufactured by Gaston County of the United States and Stoke of the Netherlands can be used.

The bubble-containing state of the water-dispersible polyurethane resin-containing coating solution containing bubbles is not particularly limited, either, but the foaming ratio is represented by the volume ratio of a constant weight of the bubble-containing liquid to the stock solution of the same weight. Is preferably more than 1 time and 5 times or less, more preferably 1.2 times or more and 4 times or less.
Less than twice. That is, the foaming ratio is a measure of the bubble content in the cell-containing water-dispersed polyurethane resin-containing coating solution. As the foaming ratio increases, the thickness of the resin film (wall) surrounding the bubbles decreases. As described above, when the resin film is thin, it may be difficult to maintain the strength of the obtained porous toner receiving layer at a sufficient level. In this respect, the expansion ratio and the water-dispersed polyurethane resin-containing coating The composition of the liquid may be appropriately selected so as to conform to the desired performance of the transfer sheet.

The size of the pores contained in the toner receiving layer of the transfer sheet of the present invention depends on the composition of the water-dispersible polyurethane resin-containing coating liquid before the bubble formation / dispersion treatment, that is, the kind of the material, the mixing ratio, the foaming, and the like. Coating, after drying, is affected by various factors such as the amount of components directly related to the thickness of the cell envelope film in the porous toner receiving layer, or the above-mentioned expansion ratio, coating method, etc. It is necessary to set bubble formation conditions. Further, the size of the fine pores on the surface of the porous toner receiving layer in the present invention is also related to the size of the bubbles in the bubble-containing resin liquid obtained by mechanical stirring, and generally, the smaller the bubbles in the resin-containing liquid, the smaller the size. Since the fine pores on the surface of the porous toner receiving layer after coating and drying are also reduced, the bubble-containing state of the aqueous dispersion-type polyurethane resin-containing mixture is not particularly limited, but the surface of the porous toner receiving layer is It is preferable that fine bubbles having the same size as the fine pores, that is, fine bubbles having an average diameter of 0.5 to 50 μm, are dispersed and mixed in the coating liquid, and a more preferable average diameter is 3 to
50 μm. The size of the bubbles contained in the coating liquid or the porous toner receiving layer can be measured by taking a photograph of a part of the bubble with an optical microscope and measuring it with an image analyzer.

A foam stabilizer and a foaming agent may be added to the resin-containing coating solution. These are added when the desired bubble-containing state cannot be obtained due to insufficient mechanical stirring ability, or when it is necessary to improve the stability of the bubbles in the bubble-containing coating solution. Specifically, stearic acid, higher fatty acids such as palmitic acid, sodium lauryl sulfate, ammonium stearate, higher fatty acid salts such as ammonium palmitate, and alkyl alkanolamides, higher fatty acid modified products such as sorbitan fatty acid esters, etc. It is particularly useful in the present invention because it has a high effect of enhancing the foamability of the resin-containing liquid and improving the dispersion stability of the bubbles. Although there is no strict restriction on these choices, it is preferable to avoid those which may significantly impair the fluidity of the resin-containing mixed liquid or impair coating workability. The amount of the foam stabilizer and the foaming agent is preferably 0 to 30 parts by weight, more preferably 1 to 20 parts by weight, based on 100 parts by weight of the solids in the coating solution. It is appropriate to be within the range, and even if it is added in an amount exceeding 30 parts by weight, the desired effect of addition is saturated and the effect cannot be improved.

The coating method for forming the porous toner receiving layer on the support includes a Meyer bar method, a gravure roll method, a roll method, a reverse roll method, a blade method, a knife method, an air knife method, an extrusion method, It can be arbitrarily selected from known methods such as a cast method.

The porous toner receiving layer of the transfer sheet of the present invention can receive a good image even when the air-containing resin mixed liquid is applied and dried, but the above-mentioned porous toner receiving layer can be used. Metal rolls and resin rolls on the layer,
Alternatively, a finishing treatment may be performed using a super calender configured by appropriately combining a metal roll and a cotton roll to further improve the surface smoothness. After coating, the semi-dry or dry sheet is brought into contact with a cast surface of a mirror-finished heated or unheated cast drum or the like to further improve the surface smoothness of the porous toner receiving layer. May be improved.

However, when the above-mentioned smooth finishing treatment is performed under excessive pressure, the resin wall surrounding the air bubbles of the porous toner receiving layer is broken, and the toner receiving layer is densified, and the heat insulating property and the cushioning property are reduced. Alternatively, the pores on the surface of the porous toner receiving layer may be destroyed, thereby deteriorating the excellent transfer performance of the porous toner receiving layer. Care must be taken.

Further, in the steps of coating, drying, winding up, etc., when producing the transfer sheet of the present invention by applying the bubble-containing coating solution on the sheet-like support, the transfer sheet itself is coated. The curled surface may be curled inside or outside. When an image forming sheet of a predetermined size obtained by cutting such a curled transfer sheet is used,
Paper feed to the image forming device may not be performed properly,
Further, troubles such as deterioration of the running property of the transfer sheet in the apparatus may occur.

In order to prevent various troubles caused by such curling, it is desirable to minimize the difference in shrinkage or expansion between the porous film and the support during heating. For this purpose, an anti-curl layer may be applied or laminated on the back surface of the transfer sheet, that is, on the surface opposite to the porous toner receiving layer. There is no limitation on the material, forming method, coating amount, laminating amount, etc. of the anti-curl layer, and various types such as the type of support, the thickness or the properties of the porous toner receiving layer, that is, the material composition, expansion ratio, coating amount, etc. In consideration of the above factors, optimization can be achieved. For example, curling may be prevented by the porous toner receiving layer itself.

As described above, even if the curl is prevented by coating or laminating the curl preventing layer, there may be a problem in running properties such as double feeding and paper jam. The present inventors have found that this poor running property results from the high cushioning property of the porous toner receiving layer. That is, a copying machine,
Or, in recording by a printer, a porous toner in which fine pores are formed by coating and drying a bubble-containing coating liquid obtained by mechanically stirring a resin-containing liquid on a sheet-like support, Forming a receiving layer, when using a transfer sheet having such a porous toner receiving layer,
When a plurality of the transfer sheets are stacked and set in a paper feed unit of a copying machine or a printer, the porous toner receiving layer having a high cushioning property is compressed. Strongly adhere to the porous toner receiving layer of the transfer sheet. Therefore, the larger the number of sheets fed, that is, the more the porous toner receiving layer of the transfer sheet is compressed, the higher the possibility of problems related to runnability such as double feeding of the transfer sheet and paper jam.

Therefore, the inventors of the present invention determined the material, forming method, coating amount, laminating amount, etc. of the back surface of the transfer sheet, in particular, the type and thickness of the support, and the porous toner receiving layer. Various factors such as the properties of the material, that is, the material composition, the expansion ratio, and the amount of coating, were intensively studied. As a result, by selecting an appropriate material for the back surface of the transfer sheet, for example, a material for forming the anti-curl layer, or a material for forming the porous toner receiving layer, the porous toner receiving layer of the transfer sheet,
JIS-P814 between the back side, especially the anti-curl layer
The standard deviation of the coefficient of static friction in the horizontal method of No. 7 is 0.05
It has been found that a high-quality transfer sheet having excellent running properties, no printing trouble, and high image quality can be obtained only by controlling the following conditions. That is, the back surface of the transfer sheet (curl prevention layer)
It has been found that if the sliding property between the porous toner receiving layer and the porous toner receiving layer is kept constant, the problem of runnability caused by the adhesion between the porous toner receiving layer and the porous toner receiving layer due to the high cushioning property can be solved. . In order to form a transfer sheet having excellent running properties, it is necessary to use a J
It is necessary to control the standard deviation of the static friction coefficient in the horizontal method of IS-P8147 to 0.05 or less, and it is preferable that the static friction coefficient be in the range of 0.2 to 0.9. If the standard deviation of the coefficient of static friction is larger than 0.05, the slip property between the back surface of the transfer sheet (anti-curl layer) and the porous toner receiving layer in contact therewith becomes insufficient, and the back surface of the transfer sheet (anti-curl layer) And, due to high adhesion with the porous toner receiving layer in contact therewith,
Runnability problems such as double feeding and paper jam occur. The coefficient of static friction between the contact surfaces of the superposed transfer sheets is 0.2
It is preferably between 0.9 and 0.9. If the coefficient of static friction is higher than 0.9, the slip property between the anti-curl layer and the porous toner receiving layer becomes insufficient, and the adhesion between the anti-curl layer and the porous toner receiving layer becomes high. As a result, there may be a problem of poor running properties such as double feeding of transfer sheets and paper jams in the copying machine or the printer. If the coefficient of static friction is less than 0.2, the transfer of the transfer sheet by the transport rolls in the copying machine or the printer may become uncertain.

Generally, depending on the selection of the material of the support of the transfer sheet, when the transfer sheet travels in the image forming apparatus, it receives various frictional forces due to the mechanism of the apparatus, or the humidity inside the apparatus decreases due to heating. As a result, the transfer sheet may be charged with static electricity. When a large number of images are continuously formed in such a state, the image forming surface of the transfer sheet and the back surface of the transfer sheet that is in contact with the transfer sheet are electrostatically adhered to each other and are hardly peeled off. In particular, since various plastic sheets, synthetic paper, and the like inherently have a property of being easily charged, when these are used as a sheet-like support,
Static electricity may be generated during the sheet forming process by cutting and during storage of the processed sheet, and the front and back of the sheet may not be easily peeled off. As a matter of course, even when paper is used as the support, the above-described trouble can occur.

It is very effective to form a so-called antistatic layer on the back surface of the transfer sheet in order to prevent such troubles caused by charging. Also, in order to prevent troubles caused by charging, use of an antistatic material or reduction of the coefficient of friction between the back surface of the transfer sheet and the porous toner receiving layer (the front surface of the transfer sheet) in contact therewith. Is valid. Like the anti-curl layer, such an anti-static layer can be formed by appropriately selecting from a wide range of materials and methods.

[0062]

The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the invention is limited thereto. “Parts” and “%” in Examples and Comparative Examples
Represents "part by weight of solid content" and "% by weight" unless otherwise specified.

Example 1 Formation of Porous Toner Receiving Layer A water-dispersible polyurethane resin-containing liquid (solid content: 30% by weight) having the following composition was prepared, and a continuous foaming machine (Aikosha Seisakusho Co., Ltd.) was prepared. Made, Turbo Hop TW-7
0), stirring speed 1500 rpm, expansion ratio 2.
Foaming treatment was performed at 0 times. Composition of resin mixture 100 parts of water-dispersible polyurethane resin (manufactured by Zeneca Corporation, trade name: NeoRez R-9679) Higher fatty acid amide-based foam stabilizer 5 parts (manufactured by San Nopco Co., trade name: DC-100A) 3 parts of carboxymethyl cellulose for adjustment (for thickening) (manufactured by Daiichi Kogyo Seiyaku Co., Ltd., trade name: AG gum) Immediately after subjecting the foamed resin mixture to a foaming treatment, a basis weight of 75 g / m ² was obtained. The surface of the high-quality paper was coated using an applicator bar so that the coating amount after drying was 10 g / m ^2, and dried to form a porous toner receiving layer. Composition of resin mixture liquid for forming curl prevention layer Resin: 100 parts by oxidation-modified starch (manufactured by Oji Cornstarch Co., Ltd., trademark: Oji Ace C) Crosslinking agent: dimethylol urea (manufactured by Showa Denko KK, trademark: Papyrol J-) 001) 25 parts of a resin mixture having the above composition (solid content, 6% by weight) was dried on a back surface of a high-quality paper having the porous toner receiving layer formed on the back surface thereof using a Mayer bar, and then dried. Coating was performed so that the coating amount was 2 g / m ^2, and the coating was dried to form an anti-curl layer, thereby producing a transfer sheet.

Example 2 Formation of Porous Toner Receiving Layer A porous toner receiving layer was formed in exactly the same manner as in Example 1. Formation of anti-curl layer In place of the resin mixture of the anti-curl layer of Example 1, the foamed resin mixture of the porous toner receiving layer of Example 1 was subjected to a foaming treatment, and then the porous toner receiving layer was immediately formed. On the back side of the high-quality paper formed on the front side, using an applicator bar, apply so that the coating amount after drying is 10 g / m ^2, and dry to form an anti-curl layer. Produced.

Example 3 Formation of Porous Toner Receiving Layer In the composition of the resin mixture of the porous toner receiving layer, a water-dispersible polyurethane resin (trade name: NeoR, manufactured by Zeneca Corporation) was used.
ezR-9679) instead of water-dispersible polyurethane resin (trade name: HUX-381, manufactured by Asahi Denka Kogyo KK)
And a porous toner receiving layer was formed in the same manner as in Example 1 except that the expansion ratio was changed from 2.0 times to 3.0 times. Formation of an anti-curl layer An anti- curl layer was formed in exactly the same manner as in Example 1,
A transfer sheet was prepared.

Example 4 Formation of Porous Toner Receiving Layer A porous toner receiving layer was formed in exactly the same manner as in Example 3. Composition of Pigment Dispersion Forming Anti-Curl Layer Pigment: Clay (trade name: UW-90, manufactured by Ryosan Corporation) 100 parts Dispersant: (trade name: Caribbean L-400, manufactured by Sanyo Chemical Industry Co., Ltd.) 0 .2 parts Resin: SBR latex (manufactured by Nippon Zeon Co., Ltd., trade name: PT-1004A) 25 parts Antifoaming agent (manufactured by San Nopco, trade name: SN deformer 521) 0.1 part Pigment dispersion having the above composition The liquid (solid content: 16% by weight) was applied to the back surface of the high-quality paper having the porous toner receiving layer formed on the surface thereof using a Meyer bar so that the coating amount after drying was 5 g / m ^2. And dried to form an anti-curl layer to prepare a transfer sheet.

Example 5 Formation of Porous Toner Receiving Layer In the composition of the resin mixture of the porous toner receiving layer, an aqueous dispersion type polyurethane resin (NeoRez, manufactured by Zeneca Corporation) was used.
R-9679) was replaced by a water-dispersible polyurethane resin (IP-27, manufactured by Dainippon Ink and Chemicals, Incorporated), except that a porous toner receiving layer was formed in the same manner as in Example 1. Produced. Formation of an anti-curl layer An anti- curl layer was formed in exactly the same manner as in Example 1,
A transfer sheet was prepared.

Example 6 Formation of Porous Toner Receiving Layer A porous toner receiving layer was formed in exactly the same manner as in Example 5. Formation of an anti-curl layer An anti- curl layer was formed in exactly the same manner as in Example 4,
A transfer sheet was prepared.

Example 7 Formation of Porous Toner Receiving Layer In the composition of the resin mixture of the porous toner receiving layer, an aqueous dispersion type polyurethane resin (trade name: NeoR, manufactured by Zeneca Corporation) was used.
ez R-9679), a water-dispersed polyurethane resin (trade name: Bondic 1850NS, manufactured by Dainippon Ink and Chemicals, Inc.) was used, and the expansion ratio was changed from 2.0 times to 1.4 times. Except for the above, Example 1 was used.
A porous toner receiving layer was formed in the same manner as described above. Formation of an anti-curl layer An anti- curl layer was formed in exactly the same manner as in Example 1,
A transfer sheet was prepared.

Example 8 Formation of Porous Toner Receiving Layer In the resin mixture composition of the porous toner receiving layer, carboxymethylcellulose for adjusting glossiness (for thickening) (trade name: AG gum, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) ) Is replaced with a polyacrylic acid-based polymer (manufactured by San Nopco Co., Ltd., trade name: Modicol V) as an additional polymer for adjusting glossiness (for thickening)
DS), and a porous toner receiving layer was formed in the same manner as in Example 3 except that the expansion ratio was changed from 3.0 times to 2.0 times. Formation of an anti-curl layer An anti- curl layer was formed in exactly the same manner as in Example 1,
A transfer sheet was prepared.

Example 9 Formation of Porous Toner Receiving Layer In the resin mixture composition of the porous toner receiving layer, carboxymethylcellulose for adjusting glossiness (for thickening) (trade name: AG gum, manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.) ) Is replaced with a polyether compound (manufactured by San Nopco Co., Ltd., trade name: SN Thickener 61) as an additional polymer for adjusting glossiness (for thickening).
A porous toner receiving layer was formed in the same manner as in Example 1 except that 2) was used and the expansion ratio was changed from 2.0 times to 3.0 times. Formation of an anti-curl layer An anti- curl layer was formed in exactly the same manner as in Example 1,
A transfer sheet was prepared.

Example 10 Formation of Toner Receiving Layer In the same manner as in Example 3, except that in the composition of the resin mixture for the porous toner receiving layer, carboxymethyl cellulose for gloss control (for thickening) (trade name: AG gum) , Manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) to form a porous toner receiving layer. Formation of an anti-curl layer An anti- curl layer was formed in exactly the same manner as in Example 1,
A transfer sheet was prepared.

Comparative Example 1 Formation of Toner Receiving Layer The resin mixture of the porous toner receiving layer of Example 1 was applied on a surface of a high-quality paper having a basis weight of 75 g / m ² without foaming.
Using an applicator bar, the coated amount after drying is 10 g
/ M ² and dried to form a toner receiving layer. Formation of an anti-curl layer An anti- curl layer was formed in exactly the same manner as in Example 1,
A transfer sheet was prepared.

[0074]Comparative Example 2 Formation of porous toner receiving layer Water dispersion in the resin mixture composition of the porous toner receiving layer
Type polyurethane resin (manufactured by Zeneca Corporation, trademark: NeoR)
ez R-9679) instead of water-dispersed polyurethane
Resin (manufactured by Zeneca Corporation, trademark: NeoRez R-9)
000), except that Example 000 was used.
To form a porous toner receiving layer. Formation of anti-curl layer An anti-curl layer was formed in exactly the same manner as in Example 1,
A transfer sheet was prepared.

Preparation of Color Toner A cyan color toner was prepared by adding 1 part by weight of a charge control agent and 3 parts by weight of a cyan pigment to 96 parts by weight of a polyester resin. Further, the magenta toner, the yellow toner, and the black toner were prepared in the same manner as described above, except that the magenta pigment, the yellow pigment, and the black pigment were used instead of the cyan pigment used for the cyan toner. The volume average particle diameter D50 of these cyan toner, magenta toner, yellow toner, and black toner was 7 μm.

Evaluation method The characteristics of the water-dispersible polyurethane resin used in each of Examples 1 to 7 and Comparative Examples 1 and 2, and the resulting transfer sheet having a porous toner receiving layer were as follows. The measurement and evaluation were performed by the method, and the evaluation results of the transfer sheet are shown in Tables 1 and 2.

(1) Heat Fusion in Heat Seal Test
Starting temperature On one side of high quality paper (Xerox L paper, manufactured by Fuji Xerox Co., Ltd.), a water-dispersed polyurethane resin liquid is applied using a Mayer bar so that the coating amount after drying is 12 g / m ^2. The coated paper was dried, and a 5 × 10 cm section was cut from the obtained coated paper. An uncoated high quality paper section of the same size as that described above is prepared in advance, one surface thereof is overlapped with the coated surface of the polyurethane resin liquid coated section, and the overlapped sample is placed in a thermal gradient tester (Toyo Seiki Co., Ltd. 2) were pressed under heating (pressurization: 3 kg / cm ² , pressurization time: 5).
Seconds). The heating and compression test was conducted at a heating temperature of 50 to 180.
The procedure was repeated in steps of 5 ° C up to ° C. When a piece of high-quality paper was slowly peeled off from the sample that was heated and pressed at each temperature,
The minimum temperature at which destruction of the paper layer on the surface of the high-quality paper due to adhesion with the polyurethane resin at the interface was defined as the heat fusing start temperature in the heat seal test.

(2) Tetrahydrofuran Insoluble Residual Rate A water-dispersed polyurethane resin liquid was applied to a glass plate (10 cm square).
The resultant was cast on the above, dried at 20 ° C. and a relative humidity of 65%, and further dried in a hot air drier at 120 ° C. for 2 hours to produce a polyurethane film having a thickness of 200 μm ± 10 μm. After immersing 0.5 g of the film in 50 ml of tetrahydrofuran solution at 25 ° C. for 24 hours,
After filtration through a 00 mesh filter cloth, the weight of the residue on the filter cloth was measured, and the percentage of the value obtained by dividing the value by the initial weight of 0.5 g was defined as the tetrahydrofuran-insoluble residual rate of the polyurethane resin.

(3) Measurement of Expansion Ratio The weight of 100 ml of the resin-containing liquid (stock solution) before the expansion treatment was determined by
The foaming ratio was calculated by dividing by the weight of 100 ml of the resin-containing liquid containing bubbles after the foaming treatment.

(4) Method of Measuring Pore Diameter The pore diameter of the surface of the porous toner receiving layer was determined by taking a photograph of the surface of the toner receiving layer using a scanning electron microscope or an optical microscope, The outline of the fine pores is accurately drawn on a transparent film with a black pen, etc., and the information of the outline of the pores is optically read by a drum scanner (trademark: 2605 type drum scan densitometer, manufactured by Abe Design). This was measured using an image analyzer (trade name: Luzex III, manufactured by Nireco). Since the shape of the fine pores formed on the surface of the porous toner receiving layer is not always a perfect circle, the pore diameter is converted into a circle equivalent diameter based on the area within the contour of the pore obtained by image analysis. Displayed.

(5) Picture Test The picture transfer test was performed at 22 ° C. and 55% by applying the above-described transfer sheet and color toner to an electrophotographic apparatus. The drawing conditions are as follows: the toner amount at the input halftone dot area ratio of 100% on the transfer sheet;
The electrophotographic apparatus was adjusted so that g / cm ² , yellow, magenta, and cyan became 0.65 mg / cm ² , respectively. In addition, the evaluation chart used for the drawing has primary colors of yellow, magenta, and cyan, secondary colors of red, green, and blue, and a tertiary color of yellow, magenta, and cyan. Those whose halftone dot area ratio changed from 0 to 100% were used.

(6) Glossiness of Porous Toner Receiving Layer Surface
(%) The glossiness of the surface of the porous toner layer is Jls Z8741.
Using a digital variable-angle gloss meter (manufactured by Nippon Denshoku) according to
The gloss at an incident angle of 75 degrees was measured.

(7) Maximum value of image glossiness and gloss difference (maximum
(High glossiness-lowest glossiness) (%) The image glossiness is such that after the image of the chart is transferred onto a transfer sheet, a portion including a blank portion and showing the highest glossiness and the lowest glossiness are shown. About the part, Jls
Using a digital variable-angle gloss meter (manufactured by Nippon Denshoku) in accordance with Z 8741, the gloss at an incident angle of 75 degrees is measured, the maximum gloss and the minimum gloss of the image area are determined, and the difference between the two is defined as the gloss difference. Notation.

(8) Image Peeling Prevention Property The image peeling prevention property was determined by transferring the image of the chart onto a transfer sheet and then peeling off the solid black image portion as follows. That is, the transfer sheet on which the image has been transferred is left for 24 hours in an environment of 20 ° C. and 65 RH%, and then the transfer sheet is folded with its image portion inside so as to be perpendicular to the line structure. And weight 3 on it
A metal roll having a width of 4.5 cm and a width of 4.5 cm was reciprocated once to form a fold. The transfer sheet was immediately spread, rubbed five times with tissue paper along the fold, and the peeling of the toner at the fold was observed with a magnifying glass. The above measurement was performed 10 times, and when image peeling equivalent to that of JD paper of Fuji Xerox Co., Ltd. was produced, the image was evaluated as B. If it was better, it was evaluated as A, and if it was worse, it was evaluated as C. A and B were passed, and C was rejected.

(9) Static Friction Coefficient and Its Standard Deviation The static friction coefficient of 20 transfer sheets was measured by the horizontal method of JIS-P8147, the average value (static friction coefficient) was obtained, and the sample (data) ) The standard deviation δ was determined.

(10) Blocking Resistance A 10-cm square stainless steel plate having a mirror-finished surface
Ten transfer sheets cut to a cm square are overlapped so that the porous toner receiving layer and the back surface of the sheet-like support are in contact with each other, and 50 g or 200 g of the transfer sheet per 1 cm ^{2 of} the transfer sheet is placed thereon. A mirror-finished stainless steel plate (10 cm square) and a weight were placed so that a load was applied. The layered material in this state is kept at 50 ° C. and a relative humidity of 80%.
And then peeled off the porous toner receiving layer and the back surface of the sheet-like support by hand. The degree of peeling was evaluated in three stages of A, B and C in order from good to bad. Were evaluated as follows. A and B were passed, and C was rejected. A: No peel resistance at all and extremely excellent in practical use B: Very little peel resistance, but no damage to the porous toner receiving layer and no practical problem in recording performance C: High peel resistance, breaks the porous toner receiving layer and is not suitable for practical use

(11) Evaluation of Running Property Twenty-five transfer sheets (A3 size) having a porous toner receiving layer and an anti-curl layer were conditioned under an environment of 20 ° C. and 65% relative humidity for 24 hours, and then copied. Machine (Acolor93)
5, Fuji Xerox Co., Ltd.)
Five sheets were set, and continuous copying was performed. The above-mentioned continuous copying was repeated 10 times, and there was no runnability problem such as an accident in which two or more transfer sheets were fed at the time of paper feeding or an accident in which the printed transfer sheet was jammed at the time of paper ejection. The case was designated as A, the case where double feed or paper jam occurred only once was designated as B, and the case where double feed or paper jam occurred two or more times was designated as C. A and B were passed, and C was rejected.

[0088]

[Table 1]

[0089]

[Table 2]

As shown in Tables 1 and 2, the electrophotographic transfer sheet of the present invention has uniform surface gloss and low image gloss in an image formed by an electrophotographic copying machine (printer). It is excellent in granularity, has no image peeling, and has excellent blocking resistance. Further, the transfer sheet of the present invention showed good running properties in a copying machine (printer).

[0091]

According to the transfer sheet of the present invention, in an image transferred by a copying machine and a printer for electrophotography, the surface gloss of the image is uniform, the image gloss can be suppressed low, and the graininess is excellent. Further, it is an electrophotographic transfer sheet having excellent image peeling resistance, and excellent blocking resistance and running properties, and is extremely useful in practice.

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Yo Nakamura 1-10-6 Shinonome, Koto-ku, Tokyo Inside Oji Paper Co., Ltd. Shinonome Research Center (72) Inventor Masaru Kato 1-10-6, Shinonome, Koto-ku, Tokyo (72) Inventor Ryosuke Nakanishi 2274 Hongo, Ebina-shi, Kanagawa Prefecture Fuji Xerox Co., Ltd.Ebina Business Center (72) Inventor Kiyoshi Hosoi 2274 Hongo, Ebina-shi, Kanagawa Prefecture Fuji Xerox Co., Ltd.Ebina Business Inside

Claims (10)

[Claims] 1. An electrophotographic transfer sheet having a sheet-like support and a porous toner receiving layer formed on at least one surface of the support and having a large number of fine pores and receiving toner. When a plurality of the electrophotographic transfer sheets are superimposed on each other, the JI
An electrophotographic transfer sheet, wherein a standard deviation of a static friction coefficient according to S-P8147 (horizontal method) is 0.05 or less. 2. The electrophotographic transfer sheet according to claim 1, wherein the coefficient of static friction is in a range of 0.2 to 0.9. 3. The transfer sheet for electrophotography according to claim 1, wherein an anti-curl layer is formed on the back surface of the sheet-like support. 4. The method according to claim 1, further comprising the step of:
The glossiness (75 °) based on lsZ8741 is 10
The transfer sheet for electrophotography according to claim 1, which is 30%. 5. The method according to claim 1, wherein the porous toner-receiving layer is provided with a bubble-containing resin liquid prepared by mechanically stirring a resin-containing liquid containing a water-dispersible polyurethane resin as a main component. The electrophotographic transfer sheet according to claim 1, wherein the transfer sheet for electrophotography is formed by coating and drying on the top, and having a large number of fine pores. 6. The average pore diameter of the fine pores on the surface of the porous toner receiving layer is 0.5 to 50 μm.
The transfer sheet for electrophotography according to claim 1. 7. The porous resin-containing liquid for a toner receiving layer further contains an additional polymer, and the compatibility parameter of the additional polymer is 3.0 to 10.3 or less than the compatibility parameter of the water-dispersible polyurethane resin. The transfer sheet for electrophotography according to claim 5, which is 0 higher. 8. The heat-sealing start temperature of the water-dispersed polyurethane resin in a heat seal test is from 90 to 150.
The transfer sheet for electrophotography according to claim 5, wherein the transfer temperature is ° C. 9. The method according to claim 9, wherein the water-dispersible polyurethane resin comprises 30
9. A glass transition temperature of -100 ° C.
The transfer sheet for electrophotography according to 1. 10. The water-dispersed polyurethane resin forms it into a film, and is dissolved in a tetrahydrofuran solvent.
The electrophotographic transfer sheet according to any one of claims 5, 8 and 9, which exhibits an insoluble residual ratio of 60 to 100% by weight when immersed at 5 ° C for 24 hours.