JPH11133650A - Electrophotographic recording sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an electrophotographic recording sheet with a receptive layer for forming a toner image which does not cause offsetting even in a fixing system using no silicone oil while maintaining compatibility with a toner. SOLUTION: When a recording sheet is obtd. by disposing a receptive layer 12 for forming a toner image on at least one face on a substrate film 11, a reaction product of a polyoxyalkylene polyol and an org. polyisocyanate is incorporated into the receptive layer 12 to obtain the objective 1st electrophotographic recording sheet or a reaction product of a polyoxyalkylene polyol, an org. polyisocyanate and a polymer having -OH,-COOH or -NH2 groups at molecular terminals or in a side chain is incorporated into the receptive layer 12 to obtain the objective 2nd electrophotographic recording sheet.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic recording sheet, and more particularly, to a method in which silicone oil is not used for a fixing roller during heating and pressure fixing to prevent deterioration of image quality and further improve transparency. Can be higher,
The present invention relates to an electrophotographic recording sheet that can be suitably used as an OHP film.

[0002]

2. Description of the Related Art In an electrophotographic system, when a toner is fixed on a recording sheet, a system in which the toner is heated by a fixing roller and pressure-fixed to a receiving resin layer on a film is generally used. At this time, if the receiving layer softens earlier than the toner, an offset phenomenon in which the receiving layer adheres to the fixing roller and moves is likely to occur. That is, problems such as a fine wavy fixed image, turbidity of the projected image, and softening of the receiving layer resin and winding around the fixing roller occur. In order to prevent the offset of the toner, a measure is generally taken to always apply silicone oil to the fixing roller to lower the affinity with the toner and the receiving layer.

[0003] Also, plastic-based substrates, especially OH
When a color image is recorded for P use, it is general that a receptor layer having a high affinity for toner is applied in order to improve transparency. Thereby, the toner is embedded in the receiving layer in a semi-molten state at the time of fixing, so that unevenness is eliminated and a clear image can be obtained when the OHP sheet is transmitted through the projector. At this time, the receiving layer applied by the effect of the silicon oil is also prevented from being offset. In recent years, as quality requirements for images have increased, O
The need for an oil-less fixing system is increasing due to the silicone oil feeling of the HP sheet itself, image deterioration due to oil, and environmental problems. However, as described above, at present, in the case of an OHP sheet provided with a receiving layer, problems such as fusing to a roller at the time of fixing and cohesive failure of the receiving layer itself to impair transparency are caused.

Accordingly, various proposals have been made in the past to solve this problem. For example, JP-A-9-17
In Japanese Patent No. 1265, the flow start temperature of the polymer resin of the image receiving layer is set to be 0 to 10 ° C. higher than that of the binder resin of the toner to be fixed, and the inclination angle of the toner with the image receiving layer (the cut line drawn on the toner) (The angle between the film and the film surface) is 40 degrees or less. However, actually, the surface temperature of the fixing roller is 130 ° C to 16 ° C.
0 ° C, the flow start temperature of the image receiving layer resin is 80 ° C to 90 °
It is described that C is preferable. At that temperature, the resin of the image receiving layer flows, so that offset is likely to occur. Also,
In Japanese Patent Application Laid-Open No. 9-160278, for the same purpose, for the same purpose, a toner receiving layer contains a thermoplastic resin having a glass transition temperature of 70 ° C. or lower and a release agent, and the release agent is a silicone oil or a fluorine-based oil. Consists of oil. However, when the toner is embedded in the receiving layer, it is difficult for the toner binder and the silicone oil to be compatible with each other, so that it is difficult to obtain high image quality. Further, Japanese Patent Application Laid-Open No. 9-152736 proposes an image receiving layer comprising a thermoplastic resin and a specific plasticizer. In this case, too, the plasticizer in the receiving layer tends to cause offset because the toner is embedded, and the image quality may be degraded by the plasticizer.

[0005]

SUMMARY OF THE INVENTION Accordingly, the present invention has a receiving layer for forming a toner image in which the receiving layer does not cause offset even in a fixing system using no silicone oil, while maintaining compatibility of the toner. It was made to propose an electrophotographic recording sheet.

Conventionally, the receiving layer has a weight average molecular weight of 15,
A linear polyester resin having a molecular weight distribution of about 000 and a narrow molecular weight distribution has been selected. However, they cause cohesive failure due to their properties under fixing without silicone oil.
Therefore, it has been studied to crosslink using an organic polyisocyanate to form a network polymer. However, this simply causes the resin in the receiving layer to harden and hinders the embedding of the toner. When irregularities occur in the highlight portion at the time and the OHP sheet is transmitted through the projector, darkening, that is, graying occurs.

[0007]

Means for Solving the Problems A first aspect of the present invention to solve the above-mentioned problems is to provide a recording sheet provided with a receiving layer for forming a toner image on at least one surface on a base film. An electrophotographic recording sheet, wherein the receiving layer contains a reaction product of a polyoxyalkylene polyol and an organic polyisocyanate.
Since such an electrophotographic recording sheet is used, offset is prevented.

[0008] A second aspect of the present invention to solve the above problems is a recording sheet provided with a receptor layer for forming a toner image on at least one surface on a base film,
The receiving layer has a polyoxyalkylene polyol, an organic polyisocyanate, and -O
H, -COOH, the electrophotographic recording sheet, which is characterized by containing the reaction product of a polymer having a -NH ₂ group there. Because it is such an electrophotographic recording sheet,
Offset is prevented.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The recording sheet for electrophotography of the present invention is provided with a receiving layer for forming a toner image on at least one side of a base film. 1 to 5 are diagrams showing an embodiment of the present invention. FIG. 1A shows an embodiment in which a receiving layer 12 for forming a toner image is provided on one side of a base film 11, and FIG.
An embodiment in which the receiving layer 12 is provided through the substrate will be described. FIG. 2A shows an embodiment in which receiving layers 12a and 12b for forming toner images are provided on both surfaces of a base film 11,
FIG. 2B shows an embodiment in which receiving layers 12a and 12b are provided via charge control layers 13a and 13b. FIG. 3 shows an embodiment in which the charge control layer 13 is provided on the receiving layer 12, and FIG.
FIG. 5 shows an embodiment in which receiving layers 12a and 12b are provided on both surfaces and charge control layers 13a and 13b are provided thereon. FIG. An embodiment is shown in which a back layer 14 and a charge control layer 13 are provided on the other surface of a material film. The back layer 14
In order to improve the transportability, a filler is added to give a slip property.

The base film used in the present invention includes:
Polyester such as polyethylene terephthalate and polyethylene naphthalate, cellulose esters such as nitrocellulose, cellulose acetate, cellulose acetate butyrate, and various plastic films such as polysulfone, polyphenylene oxide, polystyrene, polymethacrylate, polycarbonate, polyolefin, and polyvinyl chloride. Alternatively, a sheet, synthetic paper (polyolefin-based, polystyrene-based), high-quality paper, art paper, coated paper, cast-coated paper, or the like can be used, and those having a thickness of 50 to 200 μm obtained from these materials in handling are preferably used. If the heat resistance temperature is lower than 100 ° C, deformation occurs when heat-fixed.
The above materials are preferred. When the electrophotographic recording sheet of the present invention is used as an OHP sheet, it is preferable to use a transparent one of the above-mentioned base films, particularly one having a parallel line transmittance of 70% or more.

Further, a laminate formed by combining any of the above-mentioned base films can also be used. As an example of a typical laminate, there is a synthetic paper of cellulose cellulose and synthetic paper or a cellulose film and plastic film or sheet. The thickness of these base sheets may be arbitrary, and for example, is generally about 50 to 300 μm. When the substrate film as described above has a poor adhesion to a receptor layer formed on its surface, it is preferable to apply a primer treatment or a corona discharge treatment to its surface. Further, the receiving layer formed on the substrate film has an appropriate surface electric resistance (usually,
Range of 1 × 10 ⁸ to 1 × 10 ¹³ Ω / □; 23 ° C., 50
% Environment), so that the receiving layer contains a surfactant, a conductive polymer, or a conductive filler, or the lower layer of the receiving layer in order to adjust the surface resistance of the substrate itself. Alternatively, it is preferable to provide a charge control coating layer on the upper layer.

As the charge control layer 13, for example, a surfactant such as alkylbenzene imidazole sulfonate, naphthalene sulfonate, carboxylate sulfonate, phosphate quaternary ammonium salt or the like is dissolved in an appropriate solvent, A conductive polymer such as polyaniline fluoride or polythiophene dissolved in water or alkaline water, or a metal oxide fine particle doped with ZnO, SnO ₂ , In ₂ O ₃ , Al ₂ O ₃ or the like is dissolved in a water-soluble polyester or water-soluble polyester. Those dispersed in a binder such as a hydrophilic epoxy resin, polyvinyl alcohol, hydroxyethyl cellulose, hydroxymethyl cellulose, carboxymethyl cellulose, or polyacrylic acid can be used as a coating agent.

The receiving layer 12 provided on the surface of the base film for forming a toner image is for receiving the toner transferred from the fixing roll and maintaining the formed toner image. The invention according to claim 1 of the present invention is characterized in that the receiving layer contains a reaction product of a polyoxyalkylene polyol and an organic polyisocyanate. Oxyalkylene polyol and organic polyisocyanate and -OH, -COOH,-
It is characterized by containing a reaction product with a polymer having an NH ₂ group. The receiving layer may contain other resin compositions, but it is preferable that the above-mentioned composition is mainly used.

The polyoxyalkylene polyol used in the present invention is obtained, for example, by subjecting an active hydrogen compound to addition polymerization of an alkylene oxide in the presence of a catalyst, followed by a general method such as an ion exchange method, a neutralization filtration method and an adsorption method. It is obtained by removing the catalyst by a known purification method, and has a number average molecular weight of 100 to 10,000, preferably 100 to 10,000.
5,000. Such active hydrogen compounds include ethylene glycol having two or more active hydrogen groups,
Polyhydric alcohols such as propylene glycol, 1,4-butanediol, glycerin, trimethylolpropane, pentaerythritol, dipentaerythritol, sorbitol, sucrose, tris- (2-hydroxyethyl) isocyanurate, monoethanolamine, ethylenediamine; Examples thereof include amine compounds such as diethylenetriamine, 2-ethylhexylamine and hexamethylenediamine, and phenolic active hydrogen compounds such as bisphenol-A, hydroquinone and hydrogenated products thereof.

As the alkylene oxide, for example,
Examples include ethylene oxide, propylene oxide, and butylene oxide. When these alkylene oxides are addition-polymerized to the active hydrogen compound, they may be homopolymerized or copolymerized, and the order of addition may be any order. Further, as a catalyst used at the time of addition polymerization, a basic catalyst such as sodium methylate, sodium hydroxide, potassium hydroxide, and lithium carbonate is generally used, but a Lewis acid catalyst such as boron trifluoride, trimethylamine, An amine-based catalyst such as triethylamine is also useful, and the amount of the catalyst used may be about the same as a commonly used amount. Particularly preferred polyoxyalkylene polyols in the present invention include those having the structures of the following general formulas A to F.

[0016]

Embedded image

Examples of the organic polyisocyanate for crosslinking the polyol include 2,4-tolylene diisocyanate (2,4-TDI), 2,6-tolylene diisocyanate (2,6-TDI), and 4,4 '. -Diphenylmethane diisocyanate (MDI), xylylene diisocyanate (XDI), hexamethylene diisocyanate (HMDI), isophorone diine cyanate (IP
DI), triphenylmethane tridiisocyanate, tris (isocyanatephenyl) thiophosphate, lysine ester triisocyanate, 1,8-diisocyanate-4-isocyanatomethyloctane,
11-undecanetritoisocyanate, 1,3,6-
Hexamethylene triisocyanate, bicycloheptane triisocyanate, isocyanate adduct type, burette type, trimer type, isocyanurate-bound HMDI, trimethylolpropane TDI
Examples thereof include a 3-mol adduct or a mixture thereof.

In the invention according to the _second aspect, the resin which can be used as a polymer having -OH, -COOH, -NH2 at a molecular terminal or a side chain is a polyester resin, a phenoxy resin, a polyamide resin, a polyvinyl chloride resin. And acrylic resins and their modified silicones. When a polyester resin is used in combination, a polyester resin synthesized from a diol component containing a bisphenol derivative as a main component and a carboxylic acid component selected from the group consisting of a carboxylic acid, an acid anhydride thereof, or a lower alkyl ester thereof is used. It is preferably used. As the diol component,
For example, polyoxypropylene (2,2) -2,2-bis (4-hydroxyphenyl) propane, polyoxypropylene (3,3) -2,2-bis (4-hydroxyphenyl) propane, polyoxyethylene (2 , 0) -2,
2-bis (4-hydroxyphenyl) propane, polyoxypropylene (2,0) -polyoxyethylene (2,
0) -2,2-bis (4-hydroxyphenyl) propane, polyoxypropylene (6) -2,2-bis (4-
(Hydroxyphenyl) propane and the like. In some cases, other polyols such as polyoxypropylene (12) -2,2-bis (4-hydroxyphenyl) propane and polyoxyphenylethylene (3)
-2,2-bis (4-hydroxyphenyl) propane,
Ethylene glycol, diethylene glycol, propylene glycol, triethylene glycol, tetramethylene glycol, hexamethylene glycol, heptamethylene glycol, octamethylene glycol, nanomethylene glycol, decamethylene glycol, neopentyl glycol, p-xylylene glycol, m-xylylene Glycol, 1,4-cyclohexanedimethanol, 1,4-cyclohexanediethanol, 1,4-cyclohexanediol, 1,3-cyclohexanedimethanol, glycerin, polyoxyethylene (6) glycerin, polyoxypropylene (12) pentaerythritol And the like can be added in an amount of about 10 mol% or less in the polyol component. Further, as the carboxylic acid component, for example, n
-Dodecenyl succinic acid, isododecenyl succinic acid, n-
In addition to alkyl or alkenyl succinic acids such as dodecyl succinic acid, isododecyl succinic acid, n-octyl succinic acid, n-octenyl succinic acid, n-butyl succinic acid, fumaric acid, phthalic acid, maleic acid, succinic acid, adipic acid, Examples include suberic acid, azelaic acid, sebacic acid, terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, and the like. These may be used alone or in combination of two or more.

The molar ratio of the polyoxyalkylene polyol to the resin having -OH, -COOH and -NH ₂ is preferably in the range of 1:10 to 10: 1. The organic polyisocyanate is composed of all functional groups (-OH, -COO) of the contained resin and polyoxyalkylene polyol.
H, —NH ₂ ), it is preferable to add 0.8 to 1.2 times the number of functional groups. When the reaction is completed at an early stage, it is advantageous to use a catalyst. For example, organometallic catalysts such as dibutyltin dilaurate (DBTDL), dibutyltin diacetate (DBTA), phenylmercury propionate, lead octenoate, triethylenediamine, N, N'-dimethylpiperazine, N-methylmorpholine, tetramethylguanidine And amine catalysts such as triethylamine.

The recording sheet for electrophotography of the present invention is provided on at least one surface of the base sheet as described in (1) above.
Polyoxyalkylene polyols and organic polyisocyanates and other necessary additives, for example, release agents, crosslinkers,
Curing agent, catalyst, thermal release agent, ultraviolet absorber, antioxidant,
Those added light stabilizer and the like, or (2) a molecular end or side chain, -OH, -COOH, a polymer having a -NH ₂ group and a polyoxyalkylene polyol, organic polyisocyanate and other necessary additives, For example, release agents,
A dispersion obtained by dissolving a crosslinking agent, a curing agent, a catalyst, a heat releasing agent, an ultraviolet absorber, an antioxidant, a light stabilizer and the like in an appropriate organic solvent or dispersing in an organic solvent or water. For example, it can be obtained by applying and drying by a forming means such as a gravure printing method, a screen printing method, and a reverse roll coating method using a gravure plate to form a toner receiving layer. In the recording sheet for electrophotography of the present invention, since the above composition is crosslinked with a flexible polyoxyalkylene polyol in the coating and drying steps, it has a softer structure than the conventional crosslinked product of the polyester composition alone. Thus, a composition having high toner receptivity but less likely to cause offset can be formed.

The toner-receiving layer formed as described above may have any thickness, but may have a thickness of about half the particle size of the toner, generally 0.5 to 10 μm, preferably 1 to 5 μm. is there. In the receiving layer, inorganic fillers such as titanium oxide, zinc oxide, kaolin clay, calcium carbonate, and finely powdered silica, acrylic particles, and fluorine-based particles are used for the purpose of preventing sticking of recording sheets together and imparting transportability with a machine. particle,
An organic filler such as an olefin may be added. The particle size is 0.1 μm to 10 μm and 0.1% based on the resin of the receiving layer.
An addition amount of about 5% by weight is preferable.

[0022]

Next, the present invention will be described more specifically with reference to Reference Examples, Examples and Comparative Examples. In the following description, parts and% are based on weight unless otherwise specified. [Examples 1 to 11] As base material sheet, thickness 100 μm
A polyethylene terephthalate film ("Lumirror Q80D" manufactured by Toray Industries, Inc.) was used, and a coating solution (Table 1) having the following coating solution composition (11 types) was blended on one surface thereof with a formulation of (Table 2). Using a gravure roll coat, the composition was coated so as to have a thickness of 4 μm when dried, dried at 120 ° C. for 5 minutes and cured to obtain an electrophotographic recording sheet of the present invention. Coating liquid composition;

[Table 1]

The composition ratio of the above-mentioned coating liquid composition is as shown in Table 2 (% by weight), and 100 parts of each of the above-mentioned coating solution compositions is based on dibutyltin dilaurate (isocyanate curing catalyst),
0.1 parts, silica particles (particle diameter 5 μm) 100% resin content
All were added at a rate of 1% by weight.

[Table 2]

Comparative Examples 1 to 3 A polyethylene terephthalate film having a thickness of 100 μm (“Lumirror Q80D” manufactured by Toray Industries, Inc.) was used as a base material sheet. The coating solution was applied using a gravure roll coat at a ratio of a dried film thickness of 4 μm. 110 ° for Comparative Example (1) and Comparative Example (2)
C, drying for 1 minute, 120 ° for Comparative Example (3)
C and dried for 5 minutes to obtain a recording sheet for electrophotography of Comparative Example. (1) Comparative Example 1 Linear polyester resin (MW 15000) (terephthalic acid + propylene oxide-modified bisphenol A) 30 parts Silica particles (particle size 5 μm) 0.3 parts MEK / toluene = 1 / 1 70 parts (2) Comparative Example 2 Compound (MW 1540) having a structure of general formula F (R: C ₂ H ₄ ) 30 parts Silica particles (particle size 5 μm) 0.3 parts MEK / toluene = 1 / 1 70 parts (3) Comparative Example 3 Linear polyester resin (MW 15000) (terephthalic acid + propylene oxide-modified bisphenol A) 30 parts Organic polyisocyanate 1 part Silica particles (particle diameter 5 μm) 0.3 parts MEK / Toluene = 1/1 70 parts Dibutyltin dilaurate (isocyanate catalyst) 0.1 part

In each of the above Examples and Comparative Examples, the polyoxyalkylene polyol was manufactured by Sanyo Chemical Co., Ltd., the linear polyester resin was manufactured by Nippon Synthetic Chemical Co., Ltd., and the phenoxy resin was manufactured by Tomoe Industries Co., Ltd. Stuff,
The organic polyisocyanate (Coronate HX) is manufactured by Nippon Polyurethane Industry.

After the receiving layers of Examples 1 to 11 and Comparative Examples 1 to 3 were formed, a resistance control layer having the following composition was applied to the front and back surfaces of the recording sheet by a gravure direct coating method.
Dry for 5 minutes. Thereafter, at 23 ° C., 50% R.C.
H. The environment was adjusted so that the surface electrical resistivity was 1 × 10 ¹⁰ Ω / □. Composition of coating solution for resistance control layer Cationic surfactant Chemistat 7300 (manufactured by Sanyo Chemical Industries, Ltd.) 1 part IPA 100 parts

The recording sheets obtained in Examples 1 to 10 and Comparative Examples 1 to 3 were evaluated by the following self-made color laser beam printer (LBP). (1) Printer conditions Toner binder A linear polyester resin (terephthalic acid + propylene oxide-modified bisphenol A) was used as a binder. In addition, (MW = 15000, Tg: 62 ° C., softening point: 100 ° C. Fixing roller Silicon rubber Hardness 80 ° Surface temperature at the time of fixing 150 ° C. Linear pressure 4 kg / A4 width Speed 10 cm / sec

(2) Evaluation method Offset of the receiving layer The occurrence of cohesive failure of the receiving layer after fixing the toner was observed. ○: No problem ×: Offset gray due to cohesive failure Between 0 and 100%, a highlight pattern between 10 and 30% of a yellow single color print printed with a gradation pattern in 5% increments is transmitted through a projector. The degree of darkening was visually evaluated. : Vivid yellow △: Slightly gray + mixed color of vivid yellow ×: Gray

(3) Evaluation results

[Table 3]

As shown in the above evaluation results, Examples (1) to
In the case of (11), no offset occurred. Also,
Graying was also good except that Example (4) was slightly grayed. On the other hand, in the case of the comparative example, offsets occurred in (1) and (2), and in the comparative example (3) in which no offset occurred, graying occurred.
The parallel line transmittance of the recording sheet (manufactured by Nippon Denshoku Industries)
Was 85% or more in each of the examples.

[0031]

According to the electrophotographic recording sheet of the present invention, the receptor layer for forming a toner image is formed of a reaction product of a polyoxyalkylene polyol and an organic polyisocyanate, or a polyester and a polyoxyalkylene polyol and an organic polyisocyanate. Since it contains a reaction product with polyisocyanate, a flexible toner receiving layer can be formed, and a receiving layer in which offset is prevented while maintaining compatibility of the toner can be formed. Further, in the recording sheet for electrophotography of the present invention, since compatibility with the toner and affinity are good, it is not necessary to apply silicone oil to the fixing roller to reduce the affinity with the toner, It is possible to record an image without image deterioration and a feeling of silicone oil due to silicone oil.

[Brief description of the drawings]

FIG. 1 is a diagram showing an embodiment of an electrophotographic recording sheet of the present invention.

FIG. 2 is a view showing another embodiment of the electrophotographic recording sheet of the present invention.

FIG. 3 is a view showing another embodiment of the electrophotographic recording sheet of the present invention.

FIG. 4 is a view showing another embodiment of the electrophotographic recording sheet of the present invention.

FIG. 5 is a view showing another embodiment of the electrophotographic recording sheet of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 electrophotographic recording sheet 11 base film 12 receptor layer for forming toner image 13 charge control layer 14 back layer

Claims (4)

[Claims] 1. A recording sheet provided with a receiving layer for forming a toner image on at least one side on a base film, wherein the receiving layer contains a reaction product of a polyoxyalkylene polyol and an organic polyisocyanate. A recording sheet for electrophotography, comprising: 2. A recording sheet provided with a receiving layer for forming a toner image on at least one surface thereof on a base film, wherein the receiving layer has a polyoxyalkylene polyol, an organic polyisocyanate and a molecular terminal or side chain,
-OH, -COOH, electrophotographic recording sheet characterized by containing the reaction product of a polymer having a -NH ₂ group. 3. The polyoxyalkylene polyol is a numerical value satisfying a number average molecular weight of 100 to 5,000, and is at least one compound having a structure represented by the following general formulas AF. Claim 1 and Claim 2
The electrophotographic recording sheet according to the above. Embedded image 4. The recording sheet for electrophotography according to claim 1, wherein the recording sheet has a parallel line transmittance of 70% or more.