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US3889033A - Transferring paper for electrophotography - Google Patents

Transferring paper for electrophotography Download PDF

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US3889033A
US3889033A US337118A US33711873A US3889033A US 3889033 A US3889033 A US 3889033A US 337118 A US337118 A US 337118A US 33711873 A US33711873 A US 33711873A US 3889033 A US3889033 A US 3889033A
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Prior art keywords
transferring
paper
sec
smoothness
carrier resistance
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US337118A
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Hiroshi Tanaka
Ikuo Soma
Yoshikazu Ito
Masayasu Kamijo
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Canon Inc
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Canon Inc
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    • GPHYSICS
    • G03PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03GELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G7/00Selection of materials for use in image-receiving members, i.e. for reversal by physical contact; Manufacture thereof
    • G03G7/0006Cover layers for image-receiving members; Strippable coversheets
    • G03G7/002Organic components thereof
    • G03G7/0026Organic components thereof being macromolecular
    • G03G7/004Organic components thereof being macromolecular obtained by reactions only involving carbon-to-carbon unsaturated bonds
    • GPHYSICS
    • G03PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03GELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G7/00Selection of materials for use in image-receiving members, i.e. for reversal by physical contact; Manufacture thereof
    • G03G7/0006Cover layers for image-receiving members; Strippable coversheets
    • G03G7/0013Inorganic components thereof
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10TTECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00Stock material or miscellaneous articles
    • Y10T428/25Web or sheet containing structurally defined element or component and including a second component containing structurally defined particles
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10TTECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00Stock material or miscellaneous articles
    • Y10T428/25Web or sheet containing structurally defined element or component and including a second component containing structurally defined particles
    • Y10T428/259Silicic material

Definitions

  • a transferring paper for an electrophotographic process comprising developing an electric latent image with a liquid developer and transferring the image thus developed comprises a base paper and a coating layer produced by coating on the base paper a coating agent composed of 50 500 parts (as solid) of polymer emulsion having a second order transition temperature of from 40C to 25C as a binder and 100 parts of a white inorganic filler at an amount of 2 l0 g./m (as solid), carrier resistance of the resulting transferring surface being 1.5 15 sec., smoothness of the resulting transferring surface being 30 300 sec. and density being 0.75 1.00 g./cm
  • Japanese Patent Publication No. 24077/1970 discloses an electrophotographic method which comprises applying a blanket corona charging to a photosensitive plate composed of a support such as aluminum plate, a photoconductive layer (CdS-binder system etc.) overlying the support and an insulating layer overlying the photoconductive layer, imagewise exposing simultaneously with applying a corona charging of a polarity opposite to that of the blanket corona charging or AC corona charging, applying a blanket irradiation to produce an electric latent image, developing the resulting electric latent image with a liquid developer, and transferring the resulting developed image to a transferring paper.
  • a blanket corona charging to a photosensitive plate composed of a support such as aluminum plate, a photoconductive layer (CdS-binder system etc.) overlying the support and an insulating layer overlying the photoconductive layer
  • imagewise exposing simultaneously with applying a corona charging of a polarity opposite to that of the blanket corona charging or AC cor
  • a transferring paper for transferring a toner image obtained by developing an electric latent image with a dry developing agent has been already known and disclosed in Japanese Patent Publication No. 20152/1966 and others, but such transferring paper can not used for transferring of an image developed with a liquid developer.
  • a new transferring paper for liquid development has been demanded.
  • a transferring paper to which an image obtained by developing an electric latent image on an electrophotographic photosensitive member with a liquid developer is transferred, which comprises a base paper and a coating layer thereon in an amount of 2 g./m composed of 50 500 parts by weight of a polymer having a second order transition temperature of 40C to C and 100 parts by weight of a white inorganic filler, the carrier resistance of the transferring surface being 1.5 to I5 sec., the smoothness of the transferring surface being to 300 sec. according to the measuring method as defined in the specification, and the density being 0.95 to 1.00 g./cm.
  • An object of this invention is to provide a transferring paper of good transferability to which an image obtained by developing an electric latent image on an electrophotographic photosensitive member with a liquid developer is transferred.
  • Another object of this invention is to provide the transferring paper of excellent fixation of a transferred image.
  • a further object of this invention is to provide the transferring paper consuming less amount of a liquid developer andof good drying property.
  • FIG. I shows an apparatus of measuring a carrier resistance
  • FIG. 2 is a graph showing a relation between a carrier resistance and a second order transition temperature (Tg value);
  • FIG. 3 is a graph showing a relation between density of a transferred image and a carrier resistance
  • FIG. 4 is a graph showing a relation between density of a transferred image and smoothness of the surface.
  • Carrier Resistance As a carrier for a liquid developer, there may be used a carrier used in conventional wet developing process for electrophotography and electrostatic "recording.
  • the liquid is a highly electric resistant organic solvent of volume resistivity of higher than 10 Ohm-cm and dielectric constant of less than 3, which does not destroy an electrostatic image, such as paraffin organic solvents, for example, liquid paraffin and liquid is'oparaffin.
  • paraffin organic solvents for example, liquid paraffin and liquid is'oparaffin.
  • isopar'affin organic solvents there may be mentioned lsopar H, G and L supplied by ESSO.
  • carrier resistance in the present invention is a resistance to penetration of a paraffin organic solvent such as, for example, lsopar as used for liquid developer.
  • a carrier liquid penetrates a transferring paper upon transferring so that a sufficient electrophoresis transferring can not be effected and the resulting transferred image is blu'rried. Furthermore, much liquid developer is consumed and drying property is lowered so that there is a problem in practical operation.
  • Degree of carrier resistance is determined by the following method according to the present invention, and an appropriate carrier resistance range is defined by the value determined by the method.
  • a sample for measuring 1 is set to a metal frame 2, and an injector 4 for dropping a carrier liquid is horizontally fixed to a support 6.
  • a micrometer 5 is gradually rotated to drop I drop of a carrier liquid (lsopar G, supplied by ESSO) to a circle of 7 mm in dia. on the sample paper.
  • a stopwatch is actuated and then stopped when the one drop of carrier liquid penetrates over the whole area of the circle 3 of 7 mm. in dia. and the portion of the paper has become transparent.
  • the period of time thus measured is used as a degree of carrier resistance.
  • the distance between the injector needle and the sample surface is about 2 cm.
  • the injector for dropping a carrier liquid is that of 1 cc. or 2 cc. and the needle is a type of 1/3.
  • the volume of one drop under the above mentioned condition is about 0.004
  • the practical degree of carrier resistance as measured by the above mentioned method is from 1.5 to 15 sec., preferred with from about 2 to sec. This will be explained in connection with Examples.
  • Density ,Most important properties of transferring paper are carrier resistance and smoothness. In addition, density of a transferring paper is also important which is related to carrier resistance and smoothness.
  • Density of. paper varies depending upon degree of beating, composition of coating agent, amount of coating agent, conditions of calender or supercalender. In order to improve carrier resistance of a transferring paper, a porous paper is not preferable. As the result of research, it has now been found that density of the transferring paper should be higher than 0.75 g./cm
  • density of transferring paper of good fixation should be less than 1.00 g./cm"., preferred with less than 0.97 g./cm". when the smoothness is lower than 300 sec. and the coating agent of the present invention is employed.
  • Density of paper is calculated according to the following formula,
  • W is a basic weight (g./m determined according to JISP 8124 and T is thickness (mm.).
  • T is determined by using a micrometer according to JISP 8] l8, i.e. a diameter of the smaller one of two planes being about 14 mm.
  • the carrier resistance mainly depends on the film forming state of the surface coating layer, i.e. barrier property, but not on thickness and basic weight of paper as far as the basic weight is in a range of that of usual copying paper.
  • the thickness of the paper affects the carrier resistance.
  • the carrier resistance becomes higher than 2 4 sec. by the effect of thickness of paper and basic weight even when the barrier property of the coating layer itself is not sufficient.
  • the paper used in this invention is usually a paper of basic weight lower than 150 g./m particularly, lower than 100 g./m
  • the coating compositions used in this invention is mainly composed of an inorganic filler and a polymer emulsion binder.
  • a ratio of the inorganic filler to a binder and the second order transition temperature are very important.
  • the polymer emulsion as mentioned above is a general term for the thermoplastic resin emulsions, synthetic rubber latex and the like.
  • conventional coated paper such as printing paper, there are contained of white inorganic fillers and 20 10% of binder (as solid), that is, inorganic fillers are mainly contained.
  • the amount of inorganic filler is usually more than the binder for the purpose of improving the printing property.
  • the transferring paper of the present invention is fundamentally different from conventional coated paper, that is, the amount of polymer emulsion binders (as solid) is more than that of inorganic fillers.
  • the amount of polymer emulsion binders (as solid) is more than that of inorganic fillers.
  • 50 500 parts, preferably 400 parts (as solid) of the polymer emulsion binder is used for 100 parts of the inorganic filler (white).
  • amount of the binder is less than the above mentioned one, the barrier property is low and the carrier resistance is insufficient.
  • the amount of the polymer emulsion binder is more than 500 parts, the resulting coating causes a blocking tendency to the back side of the winding-up paper or the roll surface after coating, and thereby, surface of the coating layer is deteriorated and it is different to obtain a desirable property.
  • white inorganic filler a filler of small particle size, particularly, that which does not have coarse particle larger than 3 microns as far as possible, is preferable.
  • a filler of small particle size particularly, that which does not have coarse particle larger than 3 microns as far as possible, is preferable.
  • clay for coating paper titanium oxide, and calcium carbonate.
  • Tg value second order transition temperature
  • polymer having Tg value of lower than 25C, preferred with lower than 0C polymer is apt to flow when dried after coating. Furthermore, an emulsion of a polymer having lower Tg value easily migrates to the surface of coating and therefore, barrier property and carrier resistance of the resulting paper is improved. When the surface is smoothened by calender, the inorganic filler particles enters the inner portion of the paper layer and the polymer flows by heat and nip pressure to improve barrier property and lessen the penetration of carrier.
  • Tg value is too low such as lower than 40C
  • the coating is sticky even after drying at the above mentioned ratio of binder to inorganic filler, and a part of coating is taken up by the roll surface so that the formation of coating is disturbed.
  • the fixation property becomes remarkably good. This cause is considered as follows. After transferring a visible image, a temperature of about 50C is applied to a paper at a fixation step and therefore, the polymer binder having Tg value of lower than 25C, particularly 0C, is softened by heat to improve the fixing property of toner particles.
  • a small amount of a water soluble polymer may be incorporated to the above mentioned composition comprising a polymer emulsion binder and white filler so long as thermal softening of the polymer binder in the coating is not disturbed.
  • Amount of the water soluble polymer should be adjusted in accordance with Tg value of emulsion binder and the ratio to inorganic filler.
  • the transferring surface of the transferred paper is coated with the above mentioned coating layer, but the non-transferring portion may be optionally coated with a coating other than the above mentioned one.
  • both sides of a transferring paper are used for receiving transferred images, the both sides are also coated with the coating according to the present invention.
  • the relations among carrier resistance as defined by the above mentioned measurement, surface smoothness and density of transferred image are shown inF 1G. 3 and FIG. 4.
  • the black circle line in the figures corresponds to a case of weak squeezing of a liquid developer (i.e. much liquid developer) while the white circle corresponds to a case of strong squeezing of a liquid developer (i.e. little liquid developer).
  • EXAMPLE 1 A mixture of nonionic polyvinyl acetate emulsion and clay (solid ratio, 1:2) was coated on a base paper (60 g./m at an amount of 7 8 g./m (both side, as solid) by on-machine size press and dried, followed by machine calender treatment.
  • the Tg value of emulsion in this case was 30C.
  • the resulting paper had the following properties:
  • sample B having the above mentioned properties were used for transferring under the same conditions as sample A, but satisfactory transferring was not effected.
  • the transferring property and fixing property were excellent.
  • EXAMPLE 3 Transferring papers were prepared by using acrylic series emulsions having Tg value as shown below and compared with each other.
  • the emulsions l 4 in Table 5 above were mixed with an aqueous solution of polyvinylalcohol and clay at a ratio of 5:1:4 (as solid), impregnated in a base paper (60 g./m containing 20% of titanium oxide based on pulp at an amount of 8 g./m and subjected to super calender treatment (for example J, K, L and M). Sample M was further subjected to an intensified super calender treatment to increase the smoothness Table 3 and thus samples N and 0 were produced. Properties Ratio of of these samples are shown in Table 6.
  • Tg value Titanium oxide serves to prevent the formation of a transparency to a great extent when the carrier peney ggy acrylate 22% trates the paper, and in case of samples N and O of 5 60/40 25% good carrier resistance the pinhole is not noticeable. (g) 38' $58 ,g Therefore, the resulting transferring papers are also l suitable for both side transferring.
  • the density was 0.81 0.82 g./cm for each sample.
  • a base paper 54 g./m at E C less than 60-65 X X an amount of about 4 g./m
  • a base paper was preliminarily coated a mixture of vinyl G 25C 3.7-4.2 90-100 0 8 acetate emulsion (Tg value of 35C) and clay (1:7) at H 8C 4.8-5.2 -120 0 2 I 5M5] blocking sticky an amount of about 4 g./m
  • the paper thus coated on both sides was subjected to calender.
  • Table 8 Carrier Binder/clay resistance Smooth Density Transferring ratio (sec.) (sec) (g./cm”.) property Fixing property 700/100 l5.2l7.0 l80200 0.85 O A (very sticky) 500/100 12.5-14.0 l70l90 0.88 O 8 (somewhat sticky) 400/100 11.3-12.5 190-210 0.88 0 100/100 6.5-7.8 230-240 0.93 O 50/100 3.7-4.5 270-290 0.95 O 0 /100 2.5-3.5 320-340 0.98 O A EXAMP 6 in Table 9 below, clay and barium sulfate were mixed at a ratio of 5:4: 1, coated on a base paper (60 g./m at an amount of 5 g./m and subjected to calender treatment. Properties of the resulting transferring paper are shown in Table 9 below.
  • the density was 0.87 g./cm'". in each case.
  • the resulting transferring paper gave a transferred image of sufficient density and sharpness and good fixation.
  • EXAMPLE 7 carrier resistance 5.2 5.8 sec. smoothness 80 85 sec. density 0.85 g./cm".
  • the transferring paper gave a transferred image of sufficient density and sharpness, and the fixation was also excellent.
  • a transferring paper for an electrophotographic process comprising developing an electric latent image with a liquid'developer and transferring the image thus developed to the transferring paper which comprises a base paper and a coating layer produced by coating on the base paper a coating agent composed of -400 parts (as solid) of a polymer emulsion having a second order transition temperature of from 40C to 25C as a binder, and 100 parts of a white inorganic filler of a particle size of less than 3 microns and selected from the group consisting of clay, titanium oxide, calcium carbonate and barium sulfate in the amount of 2-10 g./m (as a solid), carrier resistance of the resulting transferring surface being 1.5-15 sec., smoothness of the resulting transferring surface being 30-300 sec. and density being 0.75-100 g./cm.

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Abstract

A transferring paper for an electrophotographic process comprising developing an electric latent image with a liquid developer and transferring the image thus developed comprises a base paper and a coating layer produced by coating on the base paper a coating agent composed of 50 - 500 parts (as solid) of polymer emulsion having a second order transition temperature of from -40*C to 25*C as a binder and 100 parts of a white inorganic filler at an amount of 2 - 10 g./m2. (as solid), carrier resistance of the resulting transferring surface being 1.5 - 15 sec., smoothness of the resulting transferring surface being 30 300 sec. and density being 0.75 - 1.00 g./cm3.

Description

United States Patent Tanaka et a1.
TRANSFERRING PAPER FOR ELECTROPHOTOGRAPHY Inventors: Hiroshi Tanaka; Ikuo Soma, both of Tokyo; Yoshikazu Ito; Masayasu Kamijo, both of Fuji, all of Japan Canon Kabushiki Kaisha, Tokyo, Japan Filed: Mar. 1, 1973 Appl. No.: 337,118
Assignee:
Foreign Application Priority Data Mar. 3, 1972 Japan 47-22002 U.S. Cl. 428/323; 96/1 R; 96/1 LY; 96/1.4;428/331 Int. Cl D2lh 1/28 Field of Search 96/1 R, 1 LY, 1.4; 117/155 UA, 161 UC,161UD, 161UB,161 UH, 37 LE References Cited UNITED STATES PATENTS 2/1966 Heyl et a1 96/1 R (Sec) June 10, 1975 3,414,410 12/1968 Bartlett et a1 96/] X 3,554,747 1/1971 Dastoor 96/1 X 3,582,321 6/1971 Ueda et a1. 96/1 X 3,642,480 2/1972 Urancken 96/1 X 3,681,069 8/1972 McNamee et al. 96/1 X Primary Examiner-Michael R. Lusignan Attorney, Agent, or Firm-Fitzpatrick, Cella, Harper & Scinto [57] ABSTRACT A transferring paper for an electrophotographic process comprising developing an electric latent image with a liquid developer and transferring the image thus developed comprises a base paper and a coating layer produced by coating on the base paper a coating agent composed of 50 500 parts (as solid) of polymer emulsion having a second order transition temperature of from 40C to 25C as a binder and 100 parts of a white inorganic filler at an amount of 2 l0 g./m (as solid), carrier resistance of the resulting transferring surface being 1.5 15 sec., smoothness of the resulting transferring surface being 30 300 sec. and density being 0.75 1.00 g./cm
5 Claims, 4 Drawing Figures -oi0-'20'0 2'0 4o 60 T VALUE (c) PATENTEDJUH 10 I975 ,889,033 SHEET 1 gran SOLVENT RESISTANCE (sec) 60 10 20 0 2'0 4'0 60 Tg VALUE (c) PATENTEDJUHIO I975 3889-033 SHEET 2 DENSITY OF TRANSFERRED IMAGE L5 2 IO l5 CARRIER RESISTANCE (Sec) LLI IO 50 I00 300 SURFACE SMOOTHNESS Sec) TRANSFERRING PAPER FOR ELECTROPI-IOTOGRAPHY BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a transferring paper for electrophotography used for transferring a developed image obtained by developing an electric latent image produced on an electrophotographic photosensitive member or insulating layer with a liquid developer.
2. Description of the Prior Art Heretofore, there are known methods of transferring to a transferring paper an image obtained by developing an electric latent image formed on an electrophotographic photosensitive member with a liquid developer. For example, Japanese Patent Publication No. 24077/1970 discloses an electrophotographic method which comprises applying a blanket corona charging to a photosensitive plate composed of a support such as aluminum plate, a photoconductive layer (CdS-binder system etc.) overlying the support and an insulating layer overlying the photoconductive layer, imagewise exposing simultaneously with applying a corona charging of a polarity opposite to that of the blanket corona charging or AC corona charging, applying a blanket irradiation to produce an electric latent image, developing the resulting electric latent image with a liquid developer, and transferring the resulting developed image to a transferring paper.
A transferring paper for transferring a toner image obtained by developing an electric latent image with a dry developing agent has been already known and disclosed in Japanese Patent Publication No. 20152/1966 and others, but such transferring paper can not used for transferring of an image developed with a liquid developer. A new transferring paper for liquid development has been demanded.
SUMMARY OF THE INVENTION According to the present invention there is provided a transferring paper to which an image obtained by developing an electric latent image on an electrophotographic photosensitive member with a liquid developer is transferred, which comprises a base paper and a coating layer thereon in an amount of 2 g./m composed of 50 500 parts by weight of a polymer having a second order transition temperature of 40C to C and 100 parts by weight of a white inorganic filler, the carrier resistance of the transferring surface being 1.5 to I5 sec., the smoothness of the transferring surface being to 300 sec. according to the measuring method as defined in the specification, and the density being 0.95 to 1.00 g./cm.
An object of this invention is to provide a transferring paper of good transferability to which an image obtained by developing an electric latent image on an electrophotographic photosensitive member with a liquid developer is transferred.
Another object of this invention is to provide the transferring paper of excellent fixation of a transferred image.
A further object of this invention is to provide the transferring paper consuming less amount of a liquid developer andof good drying property.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. I shows an apparatus of measuring a carrier resistance;
FIG. 2 is a graph showing a relation between a carrier resistance and a second order transition temperature (Tg value);
FIG. 3 is a graph showing a relation between density of a transferred image and a carrier resistance; and
FIG. 4 is a graph showing a relation between density of a transferred image and smoothness of the surface.
DESCRIPTION OF THE PREFERRED EMBODIMENT The present inventors have now found that a transferring paper for images obtained by liquid developing should have the following various properties.
1. Carrier Resistance As a carrier for a liquid developer, there may be used a carrier used in conventional wet developing process for electrophotography and electrostatic "recording. The liquid is a highly electric resistant organic solvent of volume resistivity of higher than 10 Ohm-cm and dielectric constant of less than 3, which does not destroy an electrostatic image, such as paraffin organic solvents, for example, liquid paraffin and liquid is'oparaffin. As commercially available isopar'affin organic solvents, there may be mentioned lsopar H, G and L supplied by ESSO.
What is meant by carrier resistance in the present invention is a resistance to penetration of a paraffin organic solvent such as, for example, lsopar as used for liquid developer. I
When a transferring paper does not have a carrier resistance or have only insufficient carrier resistance, a carrier liquid penetrates a transferring paper upon transferring so that a sufficient electrophoresis transferring can not be effected and the resulting transferred image is blu'rried. Furthermore, much liquid developer is consumed and drying property is lowered so that there is a problem in practical operation.
During transferring, it is desirable to soften a material capable of imparting carrier resistance at the interface between the developer and the liquid carrier and accept a coloring matter such as pigment material from the developer.
When the carrier resistance is too strong, the affinity to a carrier liquid is so lowered that fixation of the transferred image is not good and the transferred image is often smudged by friction even after drying.
As is clear from above, it is necessary that the transferring paper has an appropriate degree of carrier resistance. Degree of carrier resistance is determined by the following method according to the present invention, and an appropriate carrier resistance range is defined by the value determined by the method.
Referring to FIG. 1, a sample for measuring 1 is set to a metal frame 2, and an injector 4 for dropping a carrier liquid is horizontally fixed to a support 6. A micrometer 5 is gradually rotated to drop I drop of a carrier liquid (lsopar G, supplied by ESSO) to a circle of 7 mm in dia. on the sample paper. When the carrier liquid arrives at the sample, a stopwatch is actuated and then stopped when the one drop of carrier liquid penetrates over the whole area of the circle 3 of 7 mm. in dia. and the portion of the paper has become transparent. The period of time thus measured is used as a degree of carrier resistance. The distance between the injector needle and the sample surface is about 2 cm. When a carrier liquid is dropped to a paper having no carrier resistance according to the above mentioned method, the carrier liquid instantly penetrates and spreads to the full size of area for 1 drop. On the contrary, when a sample paper having carrier resistance is used, it takes some time depending upon the degree of carrier resistance that the carrier liquid penetrates and spread to the full size of area for one drop. The injector for dropping a carrier liquid is that of 1 cc. or 2 cc. and the needle is a type of 1/3. The volume of one drop under the above mentioned condition is about 0.004
The practical degree of carrier resistance as measured by the above mentioned method is from 1.5 to 15 sec., preferred with from about 2 to sec. This will be explained in connection with Examples.
2. Smoothness Smoothness of transferring papers having an appropriate degree of carrier resistance has been measured by Bekk tester for paper according to I P81 19 and it has now been found that smoothness ranging from sec. to 300 sec., preferred with 40 sec. to 200 see. is appropriate.
When smoothness of the paper is lower than 30 sec., there occurs irregular transferring to fail to produce a good transferred image unless a large amount of a liquid developer is present, and it takes a long time to dry the liquid developer.
When smoothness is higher than 300 sec., a good transferred image can be obtained by only a small amount of liquid developer, but fixation of the developer after transferred is not good and the image is disadvantageously damaged by friction. This will be further explained by referring to experimental data.
3. Density ,Most important properties of transferring paper are carrier resistance and smoothness. In addition, density of a transferring paper is also important which is related to carrier resistance and smoothness.
Density of. paper varies depending upon degree of beating, composition of coating agent, amount of coating agent, conditions of calender or supercalender. In order to improve carrier resistance of a transferring paper, a porous paper is not preferable. As the result of research, it has now been found that density of the transferring paper should be higher than 0.75 g./cm
preferred with higher than 0.78 g./cm
On the other hand, it has been now further found that density of transferring paper of good fixation should be less than 1.00 g./cm"., preferred with less than 0.97 g./cm". when the smoothness is lower than 300 sec. and the coating agent of the present invention is employed.
In view of the foregoing, preferable density for the transferring paper ranges from 0.75 to 1.00 g./cm
Density of paper is calculated according to the following formula,
density '(g./cm".)
wherein W is a basic weight (g./m determined according to JISP 8124 and T is thickness (mm.). The thickness T is determined by using a micrometer according to JISP 8] l8, i.e. a diameter of the smaller one of two planes being about 14 mm.
In order to obtain an excellent transferring paper of good fixability satisfying carrier resistance and smoothness according to the above mentioned measuring method, it is necessary to provide a coating layer of good film shaping state after coating and drying.
Since, among various solvents, paraffin series solvents g./m as Isopar usually used for liquid developer can particularly easily penetrate a paper layer, the carrier resistance mainly depends on the film forming state of the surface coating layer, i.e. barrier property, but not on thickness and basic weight of paper as far as the basic weight is in a range of that of usual copying paper. At a basic weight higher than 100 g./m the thickness of the paper affects the carrier resistance. At a basic weight higher than 150 g./cm the carrier resistance becomes higher than 2 4 sec. by the effect of thickness of paper and basic weight even when the barrier property of the coating layer itself is not sufficient. On the contrary, sometimes a carrier resistance is higher than 15 sec. though there are given good transferring and fixation. However, the paper used in this invention is usually a paper of basic weight lower than 150 g./m particularly, lower than 100 g./m
The coating compositions used in this invention is mainly composed of an inorganic filler and a polymer emulsion binder. For obtaining satisfactory carrier resistance and smoothness, a ratio of the inorganic filler to a binder and the second order transition temperature are very important. The polymer emulsion as mentioned above is a general term for the thermoplastic resin emulsions, synthetic rubber latex and the like. In conventional coated paper such as printing paper, there are contained of white inorganic fillers and 20 10% of binder (as solid), that is, inorganic fillers are mainly contained. In printing paper, when a binder occupies most portion of the coating surface, the paper has low acceptability to ink. Therefore, the amount of inorganic filler is usually more than the binder for the purpose of improving the printing property.
The transferring paper of the present invention is fundamentally different from conventional coated paper, that is, the amount of polymer emulsion binders (as solid) is more than that of inorganic fillers. For example, 50 500 parts, preferably 400 parts (as solid), of the polymer emulsion binder is used for 100 parts of the inorganic filler (white). When amount of the binder is less than the above mentioned one, the barrier property is low and the carrier resistance is insufficient. On the contrary, when the amount of the polymer emulsion binder is more than 500 parts, the resulting coating causes a blocking tendency to the back side of the winding-up paper or the roll surface after coating, and thereby, surface of the coating layer is deteriorated and it is different to obtain a desirable property. In this case, as white inorganic filler, a filler of small particle size, particularly, that which does not have coarse particle larger than 3 microns as far as possible, is preferable. For example, there may be mentioned clay for coating paper, titanium oxide, and calcium carbonate.
As a polymer'emulsion binder used together with the inorganic filler at the above mentioned ratio, it has been found that a polymer material having a second order transition temperature (Tg value) of from 25C to 40C, preferred with from 0C to 30C, is suitable.
When an emulsion of polymer having Tg value of lower than 25C, preferred with lower than 0C, polymer is apt to flow when dried after coating. Furthermore, an emulsion of a polymer having lower Tg value easily migrates to the surface of coating and therefore, barrier property and carrier resistance of the resulting paper is improved. When the surface is smoothened by calender, the inorganic filler particles enters the inner portion of the paper layer and the polymer flows by heat and nip pressure to improve barrier property and lessen the penetration of carrier.
However, when Tg value is too low such as lower than 40C, the coating is sticky even after drying at the above mentioned ratio of binder to inorganic filler, and a part of coating is taken up by the roll surface so that the formation of coating is disturbed.
When a polymer emulsion having Tg value ranging from 40C to 25C, preferred with from -30C to 0C, is used, the fixation property becomes remarkably good. This cause is considered as follows. After transferring a visible image, a temperature of about 50C is applied to a paper at a fixation step and therefore, the polymer binder having Tg value of lower than 25C, particularly 0C, is softened by heat to improve the fixing property of toner particles.
An example of relation among Tg value, fixation and carrier resistance is shown in Table 1 below and FIG.
A small amount of a water soluble polymer may be incorporated to the above mentioned composition comprising a polymer emulsion binder and white filler so long as thermal softening of the polymer binder in the coating is not disturbed. Amount of the water soluble polymer should be adjusted in accordance with Tg value of emulsion binder and the ratio to inorganic filler. The transferring surface of the transferred paper is coated with the above mentioned coating layer, but the non-transferring portion may be optionally coated with a coating other than the above mentioned one.
However, when both sides of a transferring paper are used for receiving transferred images, the both sides are also coated with the coating according to the present invention. In this case, it is preferable to use a paper containing titanium oxide since an image on the other side is not seen through.
The relations among carrier resistance as defined by the above mentioned measurement, surface smoothness and density of transferred image are shown inF 1G. 3 and FIG. 4. The black circle line in the figures corresponds to a case of weak squeezing of a liquid developer (i.e. much liquid developer) while the white circle corresponds to a case of strong squeezing of a liquid developer (i.e. little liquid developer). In practical use, it is preferable to use in a state of little liquid developer (i.e. strong squeezing) since consumption of the liquid developer is kept low and drying is easy. Therefore, transferring property of a transferring paper is to be judged at the above mentioned strong squeezing state, and the higher the density of transferred image, the better the transferring property.
In FIG. 3, it is clear that the transferring property becomes good as the carrier resistance increases in both cases of white circle and black circle. In case of white circle, the difference of transferring property per difference of carrier resistance is larger than that in case of black circle. Therefore, the carrier resistance as defined above is an important factor for transferring property (particularly, in case of strong squeezing of liquid developer). This support the appropriateness of the above mentioned at an instant of transferring, it is necessary that the surface of the transferring paper has a barrier property and the transferring is effected accurately and uniformly.
The relation among carrier resistance, smoothness and practicability of transferring paper is shown in Table 2.
Table 2 Carrier resistance (sec. Smoothness hi her (sec.) g
01.5 than 15 lower than 30 50 200 200 300 higher than 300 @Very good OGood A Somewhat bad X Not usable The following examples are given for illustrating the present invention.
EXAMPLE 1 A mixture of nonionic polyvinyl acetate emulsion and clay (solid ratio, 1:2) was coated on a base paper (60 g./m at an amount of 7 8 g./m (both side, as solid) by on-machine size press and dried, followed by machine calender treatment. The Tg value of emulsion in this case was 30C. The resulting paper had the following properties:
carrier resistance 1.8 2.2 sec. smoothness (Bekk tester) l 10 sec. density 0.82 gJcm.
der treatment (sample B), the properties were as shown below:
carrier resistance 0.8 1.0 sec. smoothness 25 29 sec. density 0.78 g./cm".
The sample B having the above mentioned properties were used for transferring under the same conditions as sample A, but satisfactory transferring was not effected.
In place of vinyl acetate emulsion used in sample A, there was used a vinyl acetate-butyl acrylate (90:10) copolymer emulsion to produce a transferring paper. The Tg value of the emulsion was 22C. Properties of the resulting transferring paper were:
Carrier resistance 3.8 4.2 sec. smoothness l 120 sec. density 0.82 g./cm".
The transferring property and fixing property were excellent.
EXAMPLE 2 Transferring papers of various Tg values as shown below were prepared by using styrene series emulsion and compared with each other.
EXAMPLE 3 Transferring papers were prepared by using acrylic series emulsions having Tg value as shown below and compared with each other.
The emulsions l 4 in Table 5 above were mixed with an aqueous solution of polyvinylalcohol and clay at a ratio of 5:1:4 (as solid), impregnated in a base paper (60 g./m containing 20% of titanium oxide based on pulp at an amount of 8 g./m and subjected to super calender treatment (for example J, K, L and M). Sample M was further subjected to an intensified super calender treatment to increase the smoothness Table 3 and thus samples N and 0 were produced. Properties Ratio of of these samples are shown in Table 6. copolymer component components Tg value Titanium oxide serves to prevent the formation of a transparency to a great extent when the carrier peney ggy acrylate 22% trates the paper, and in case of samples N and O of 5 60/40 25% good carrier resistance the pinhole is not noticeable. (g) 38' $58 ,g Therefore, the resulting transferring papers are also l suitable for both side transferring.
Table 6 Tg value of Carrier Sample emulsion resistance smoothness Density Transferring Fixing No. ("C (sec.) (sec.) (g./cm".) property property J 99C 17-20 130-150 0.83 A X K 30C 3.8-4.2 150-170 0.85 O A L 25C 4.9-5.3 150-130 0.85 O- O M 27c 8.9-9.5 170-200 0.87 O G) N 27C 10.2-10.8 230-250 0.92 O o -27C 11.5-12.2 320-340 0.94 O A EXAMPLE 4 The emulsions l 5 in Table 3 were mixed with titanium oxide at a ratio of 2 to 1 (by weight, as solid), coated on a base paper (60 g./m at an amount of 3 g./m by off-machine coating, subjected to a calender treatment to produce samples, E, F, G. H, and I, and carrier resistance, smoothness transferring property and fixing property of the resulting samples were measured. The results are shown in Table 4.
The density was 0.81 0.82 g./cm for each sample.
Table 7 Carrier Trans- Samp Composition of Composition Tg value resistance Smooth ferring Fixing No. copolymer ratio (C) (sec.) (sec.) property property P Vinyl acetate- 75/25 8 4.3-4.7 120-130 0 O butyl acrylate 0 do. /40 5 4.5-5.0 130-140 0 R do. 50/50 -14 4.8-5.2 135-145 0 Table 4 EXAMPLE 5 Vinyl acetate-butyl acrylate copolymer emulsion S I Tg vtalue Carrier SmOoth- "l'ra s- F (sample Q, Tg value of -5C) as used in Example 4 was amp e O resistance HESS errmg lXll'lg No. emulsion (sec.) (sec.) property property mixed with clay at a ratio as shown 1n Table 8 bzelow and coated on one side of a base paper (54 g./m at E C less than 60-65 X X an amount of about 4 g./m On the other side of the F {i 7045 A A base paper was preliminarily coated a mixture of vinyl G 25C 3.7-4.2 90-100 0 8 acetate emulsion (Tg value of 35C) and clay (1:7) at H 8C 4.8-5.2 -120 0 2 I 5M5] blocking sticky an amount of about 4 g./m The paper thus coated on both sides was subjected to calender.
Table 8 Carrier Binder/clay resistance Smooth Density Transferring ratio (sec.) (sec) (g./cm".) property Fixing property 700/100 l5.2l7.0 l80200 0.85 O A (very sticky) 500/100 12.5-14.0 l70l90 0.88 O 8 (somewhat sticky) 400/100 11.3-12.5 190-210 0.88 0 100/100 6.5-7.8 230-240 0.93 O 50/100 3.7-4.5 270-290 0.95 O 0 /100 2.5-3.5 320-340 0.98 O A EXAMP 6 in Table 9 below, clay and barium sulfate were mixed at a ratio of 5:4: 1, coated on a base paper (60 g./m at an amount of 5 g./m and subjected to calender treatment. Properties of the resulting transferring paper are shown in Table 9 below.
The density was 0.87 g./cm'". in each case.
Table 9 Copolymer Component Tg value Carrier Transferring component ratio ("C) resistance Smoothness property Fixation ethylene- 4/6 28 4.5 5.0 170 190 O (9 vinyl acetate do. 5/5 39 5.2 5,6 200 220 O O somewhat sticky do. 6/4 49 5.9 6.5 blocking sticky Properties of the resulting sample are as shown below:
carrier resistance 4.0 4.5 sec. smoothness 210 250 sec. density 0.83 g./cm
The resulting transferring paper gave a transferred image of sufficient density and sharpness and good fixation.
EXAMPLE 7 carrier resistance 5.2 5.8 sec. smoothness 80 85 sec. density 0.85 g./cm".
The transferring paper gave a transferred image of sufficient density and sharpness, and the fixation was also excellent.
EXAMPLE 8 Vinyl acetate-ethylene copolymer emulsion as shown l. A transferring paper for an electrophotographic process comprising developing an electric latent image with a liquid'developer and transferring the image thus developed to the transferring paper which comprises a base paper and a coating layer produced by coating on the base paper a coating agent composed of -400 parts (as solid) of a polymer emulsion having a second order transition temperature of from 40C to 25C as a binder, and 100 parts of a white inorganic filler of a particle size of less than 3 microns and selected from the group consisting of clay, titanium oxide, calcium carbonate and barium sulfate in the amount of 2-10 g./m (as a solid), carrier resistance of the resulting transferring surface being 1.5-15 sec., smoothness of the resulting transferring surface being 30-300 sec. and density being 0.75-100 g./cm.
2. A transferring paper according to claim 1 in which the carrier resistance is 2 10 sec.
3. A transferring paper according to claim 1 in which the smoothness is 40 200sec.
4. A transferring paper according to claim 1 in which the second order transition temperature ranges from 30C to 0C.
5. A transferring paper according to claim 1 in which the polymer emulsion is an emulsion selected from the group consisting of polyvinyl acetate, vinyl acetateethylene copolymer, vinyl acetate-acrylic acid ester 00- polymer, styrene-acrylic acid ester copolymer, methacrylic acid ester-acrylic acid ester copolymer, and styrene-butadiene latex.
UNI'II'JD s'm'nss m'naw'r omen CERTIFICATE 01* CORRECTION pa e No, 3,889, 033 Dated June 10, 1975 In fl HIROSHI TANAKA. ET AL It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:
Column 2, line 39 -'blu rri ed" should read -blurred Column 4, line 9 "g./m" should read -such Column 4, line 60, "different" should read -difficult- Column 6, line 57, "Canon (K; should read Canon K.
On the Cover Page, Right Column, 'l i-rie 4 "Urancken" should read Vrancken Signed and Sealed this nineteenlh Day Of August 1975 [SEAL] A nest.
RUTH C. MASON C. MARSHALL DANN ll/(sling ()ff er v i (Hmmmlmur v! Parents and Trademarks

Claims (5)

1. A TRANSFERRING PAPER FOR AN ELECTROPHOTOGRAPHIC PROCESS COMPRISING DEVELOPING AN ELECTRIC LATENT IMAGE WITH A LIQUID DEVELOPER AND TRANSFERRING THE IMAGE THUS DEVELOPED TO THE TRANSFERRING PAPER WHICH COMPRISES A BASE PAPER AND A COATING LAYER PRODUCED BY COATING ON THE BASE PAPER A COATING AGENT COMPOSED OF 100-400 PARTS (AS SOLID) OF A POLYMER EMULSION HAVING A SECOND ORDER TRANSITION TEMPERATURE OF FROM -40*C TO 25*C AS A BINDER, AND 100 PARTS OF A WHITE INORGANIC FILLER OF A PARTICLE SIZE OF LESS THAN 3 MICRONS AND SELECTED FROM THE GROUP CONSISTING OF CLAY, TITANIUM OXIDE, CALCIUM CARBONATE AND BARIUM SULFATE IN THE AMOUNT OF 2-10 G./M2 (AS A SOLID), CARRIER RESISTANCE OF THE RESULTING TRANSFERRING SURFACE BEING 1.5-15 SEC., SMOOTHNESS OF THE RESULTING TRANSFERRING SURFACE BEING 30-300 SEC. AND DENSITY BEING 0.17-100 G./CM3.
2. A transferring paper according to claim 1 in which the carrier resistance is 2 - 10 sec.
3. A transferring paper according to claim 1 in which the smoothness is 40 - 200 sec.
4. A transferring paper according to claim 1 in which the second order transition temperature ranges from -30*C to 0*C.
5. A transferring paper according to claim 1 in which the polymer emulsion is an emulsion selected from the group consisting of polyvinyl acetate, vinyl acetate-ethylene copolymer, vinyl acetate-acrylic acid ester copolymer, styrene-acrylic acid ester copolymer, methacrylic acid ester-acrylic acid ester copolymer, and styrene-butadiene latex.
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WO1998004960A1 (en) * 1996-07-25 1998-02-05 Minnesota Mining And Maufacturing Company Method of providing images on an image receptor medium
US6057394A (en) * 1995-12-05 2000-05-02 Bayer Aktiengesellschaft Thermoplastic compositions with improved X-ray contrast
NL2018013B1 (en) * 2016-12-16 2018-06-26 Xeikon Mfg Nv Digital printing process and printed recording medium

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JPS62198875A (en) * 1986-02-26 1987-09-02 Fuji Xerox Co Ltd Transfer paper for electrophotography
DE19703731A1 (en) * 1997-01-31 1998-08-06 Buelent Oez Process for transferring images to substrates by means of xerography over transfer papers
JP4091637B2 (en) * 2002-11-27 2008-05-28 三菱製紙株式会社 Wet electrophotographic recording sheet
JP2018155864A (en) * 2017-03-16 2018-10-04 北越コーポレーション株式会社 Wet electrophotographic printing paper

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US3414410A (en) * 1964-04-15 1968-12-03 Itek Corp Recording process
US3554747A (en) * 1967-10-27 1971-01-12 Goodyear Tire & Rubber Electrostatic printing material and method of its preparation
US3582321A (en) * 1966-11-25 1971-06-01 Yasuo Ueda Electrophotographic binder plates made from mixtures of water soluble resins
US3642480A (en) * 1968-04-24 1972-02-15 Agfa Gevaert Nv Photographic process and materials used therein
US3681069A (en) * 1966-10-28 1972-08-01 Rohm & Haas Binder plate for use in xerography and process therefor

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US3414410A (en) * 1964-04-15 1968-12-03 Itek Corp Recording process
US3681069A (en) * 1966-10-28 1972-08-01 Rohm & Haas Binder plate for use in xerography and process therefor
US3582321A (en) * 1966-11-25 1971-06-01 Yasuo Ueda Electrophotographic binder plates made from mixtures of water soluble resins
US3554747A (en) * 1967-10-27 1971-01-12 Goodyear Tire & Rubber Electrostatic printing material and method of its preparation
US3642480A (en) * 1968-04-24 1972-02-15 Agfa Gevaert Nv Photographic process and materials used therein

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6057394A (en) * 1995-12-05 2000-05-02 Bayer Aktiengesellschaft Thermoplastic compositions with improved X-ray contrast
WO1998004960A1 (en) * 1996-07-25 1998-02-05 Minnesota Mining And Maufacturing Company Method of providing images on an image receptor medium
NL2018013B1 (en) * 2016-12-16 2018-06-26 Xeikon Mfg Nv Digital printing process and printed recording medium

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JPS5623152B2 (en) 1981-05-29
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DE2310393C3 (en) 1979-06-21
JPS4890534A (en) 1973-11-26

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