JP3011638B2 - Color image forming method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention retransfers a powder image obtained in an apparatus for forming an image using a charged powder, such as an electrophotographic apparatus and an electrostatic recording apparatus, to another final transfer material. And a method for forming a color image.

[0002]

2. Description of the Related Art Conventionally, it has been widely known to transfer an image to a three-dimensional object using a transfer picture technique. For example, a water-soluble paste represented by dextrin is coated on a base material such as paper. The required image is formed on this coating film using acrylic ink by screen printing, etc., and the paper having this image is immersed in water to dissolve the dextrin, and the acrylic ink image floating in water is converted into a three-dimensional object such as a ceramic. 2. Description of the Related Art A hydraulic transfer method for transferring a sheet by hydraulic pressure is widely known. An example of direct application of the transfer paper used in this method to electrophotography is Muto Kogyo's Templin. This transfer material is made of dextrin film on rice paper as a transfer material,
After applying this to an electrophotographic apparatus to form a toner image on the dextrin surface, the transfer material is passed through an organic solvent capable of softening the resin in the toner, and the retransfer medium to be retransferred to the toner image After giving adhesion to
After the transfer material is brought into close contact with the retransfer medium so that the toner image faces the retransfer medium, water is applied from the back surface of the paper to dissolve the dextrin film and transfer only the toner image.

However, in a transfer material formed by forming a water-soluble coating film on such an opaque paper, not only is it difficult to perform positioning at the time of retransfer, but also due to the influence of moisture in the atmosphere,
The transfer material surface is softened before image formation, which causes a problem that the softened dextrin adheres to a photosensitive drum or the like in an electrophotographic apparatus. Further, as described above, since the sheet is sensitive to moisture in the air, it greatly expands and contracts with respect to the amount of moisture, causing an unnecessary curl of the transfer material to be left unnecessarily.

[0004] To solve the above two problems,
No. 086 proposes a retransfer material using polyvinyl alcohol which is a saponified product of vinyl acetate instead of dextrin. The transfer material proposed here is a material in which a silicone resin is coated on paper, and a material obtained by mixing a silicone antifoaming agent with Nissuka Chemical's Casesol O-5 is applied. After a toner image is formed on this coating film by an electrophotographic apparatus, the caseol film is peeled off from the base material and superposed so that the toner image faces the retransfer medium.

By applying heat and pressure, the resin in the toner image is softened to obtain an adhesive force to the retransfer medium, and after cooling, 80% of ethyl alcohol is applied from the back surface of the casesol film.
% Of the aqueous solution to reduce the adhesive strength between the casesol film and the toner image, thereby completing the retransfer.

According to this method, there is an advantage that the thin film having the toner image is peeled off from the base material, so that the film becomes substantially transparent and the alignment is easy.

[0007]

However, in the above-mentioned conventional example, the temperature at the time of re-transfer is too high because the heating and pressurizing at the time of transfer are not restricted, so that the toner image is completely fixed to the casesol film. High-temperature offset, or low-temperature offset, such as insufficient retransferability due to too low, occurred, and a sufficiently good color image could not be obtained.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a color image forming method for preventing a high-temperature offset and a low-temperature offset during retransfer and forming a sufficiently good color image on a transfer medium.

[0009]

That is, according to the present invention, an image transferred by an electrophotographic method to a transfer material having a polyvinyl alcohol layer on a support is fixed once, and a release layer is formed on another transfer medium again. This is a color image forming method in which only a toner is transferred without providing, and a fixing temperature at the time of retransfer is lower than a first fixing temperature. With this configuration, high-temperature offset and low-temperature offset are prevented, and a sufficiently good color image is formed on the transfer medium.

The present invention also provides a method of fixing an image transferred by an electrophotographic method once to a transfer material having a polyvinyl alcohol layer on a support, and again providing only a toner without providing a release layer on another transfer medium. In the color image forming method for transferring the image, the fixing temperature at the time of retransfer is lower than the first fixing temperature,
The color image forming method is characterized in that the pressure during retransfer is lower than the pressure during the first fixing. With this configuration, high-temperature offset and low-temperature offset are prevented, and a sufficiently good color image is formed on the transfer medium.

[0011]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a transfer picture transfer for electrophotography used in the present invention.
FIG. 2 is a schematic sectional view illustrating a layer configuration of the copying material 1. 11 is transfer material
Medium or high quality plain paper, which is the base material for coating 1.
Alternatively, one or both sides of these papers may be filled with resin
Coated paper, and polyethylene terephthalate
A heat-resistant film such as a sheet is used. For paper, the grammage is
30g / m^Two More preferably, 45 g / m^Two More than
preferable. 30g / m ^Two If the paper is less than
However, it is difficult to ensure the transportability of electrophotographic equipment.
No. The grammage is 200 g / m^Two The following is preferable, and 15
0 g / m^Two The following is more preferred. 200g / m^Two Beyond
In this case, the rigidity of the base paper is too high, resulting in poor transportability.
easy. In addition, this base paper is suitable for electrophotographic equipment.
In order to maintain image transferability, inorganic materials such as sodium chloride
0.2 to 4% by weight of a salt is added, and its volume resistance value is 20
10 hours after standing for 24 hours at 65 ° C and 65% RH⁸ -10^Ten
It is preferably adjusted to Ω · cm. In addition,
When a film material is used for the film,
In the case of PET film of the axial stretch heat-resistant type, its thickness
Preferably 50 μm or more, 75 μm or more and 150 μm
The following is more preferred. Furthermore, this film
Cationic or nonionic surfactant on B surface on surface
An antistatic layer made of⁸ 
-10¹²Ω / □ (20 ℃, 65% RH)
Preferably.

Reference numeral 12 denotes an adhesive layer, which is provided to prevent the release layer 13 and the transfer layer 14 to be applied later from easily peeling off in the electrophotographic apparatus. Examples of the material used include an aqueous acrylic emulsion, a water-soluble acrylic, a water-soluble polyester, 6.6 nylon, and polyacrylonitrile. When paper is the base material, all of the above materials can be used. However, in the case of a resin film such as PET, the material should be sorted out to obtain a sufficient adhesive strength depending on the base material. In the case of PET or the like, a water-soluble polyester is preferable, and a type in which the water resistance after drying of the coating film is improved by adding ammonium chloride at the time of forming the coating film is preferable.

A release layer 13 is mainly composed of polyvinyl alcohol, which is a saponified product of polyvinyl acetate, and preferably has a saponification degree of 90% or more. Also,
When polyvinyl alcohol having a saponification degree of less than 90% is used, it is also possible to use a mixture containing a small amount of a water-soluble silicone resin as a release agent. However, it is difficult to use polyvinyl alcohol having a saponification degree of less than 70% in terms of water resistance.

The mutual material selection between the release layer 13 and the adhesive layer 12 is also affected by the adhesive strength, and at least 90 ° peeling at an adhesive strength of 1.degree. The transfer layer 14 and the release layer 1 are preferably at least 5 g / cm.
The thickness is preferably 4 g / cm or less so that the film is not broken when the retransferred film layer 3 is peeled off from the substrate.

Next, with respect to the transfer layer 14, this layer receives a toner image by an electrophotographic apparatus, holds the toner image at least until a re-transfer step is performed by heating, and has sufficient It is required to have excellent toner release performance. Further, it is also required to have sufficient water resistance as compared with the prior art. That is, it is necessary that water permeability is excellent while ensuring the solvent permeability during retransfer. Specifically, a transfer layer is formed by mixing polyvinyl alcohol obtained by saponifying polyvinyl acetate of 95% or more with polyvinyl alcohol obtained by lowering polyvinyl acetate by 90% or less. The mixing ratio is preferably such that the content of polyvinyl alcohol having a high degree of saponification of 95% or more is 10% by weight or more, more preferably 25% by weight or more, as a solid content ratio. If less than 10% by weight, 90
% Or less of the low saponification degree polyvinyl alcohol strongly appears, and the surface layer may be melted out in a high temperature environment, which may contaminate members in the electrophotographic apparatus. Furthermore, high saponification degree polyvinyl alcohol is 7
If it exceeds 5% by weight, the arrangement of the linear polymers forming the membrane itself becomes highly regular like a cellulose membrane, and the shrinkage of the membrane with respect to a change in the amount of water in the air may increase. That is, the high saponification degree polyvinyl alcohol is more preferably 25% by weight or more and 75% by weight or less as a solid content ratio. If necessary, a cationic or nonionic antistatic agent can be added to the transfer layer 14 to improve electrophotographic transferability. As the amount of the antistatic agent, a target surface specific resistance value of 10 ⁸ to 10 ¹² Ω /
It should be adjusted so that it becomes □. Further, an inorganic white pigment such as a silica powder may be mixed in order to ensure paper transportability.

Regarding the thickness of each layer, the adhesive layer 12 is preferably a thin layer so as not to cause splitting of the film.
It is preferably from 10 μm to 10 μm. If it is less than 2 μm, unevenness tends to occur, and if it exceeds 10 μm, in-layer peeling tends to occur.

The release layer 13 has a role of a primer layer of the transfer layer 14 and a role of achieving sufficient peeling at an interface between the transfer layer 14 and the adhesive layer 12, and its thickness is preferably 2 μm or more and 6 μm or less. If it exceeds 6 μm, shrinkage of this layer due to moisture appears strongly and curling is likely to occur, and if it is less than 2 μm, unevenness tends to occur.

The thickness of the transfer layer 14 is preferably 10 μm or more. If it is thinner than this, insufficient strength such as breakage of the film when peeled from the substrate is likely to occur. Also, 50
μm or less is preferred. If the thickness is larger than this, the film after peeling becomes hard, and the reproducibility of the curved surface at the time of retransfer tends to decrease.

Next, the electrophotographic toner applicable to the transfer picture transfer material used in the present invention will be described in detail. fundamentally,
Electrophotographic toner containing dyes and pigments such as yellow, cyan, magenta, etc. in addition to carbon black as binder resin mainly composed of resins such as styrene-acryl copolymer, styrene-butadiene copolymer, epoxy and polyester can be used It is. Among them, the color toners described below are ones in which the color according to the present invention can further bring out the effects of the image forming method.

The toner powder for the color electrophotographic apparatus is
It is necessary that the toner has good meltability and color mixing when heat is applied, and a sharp melt toner having a low softening point and a short melting time is preferable.

By using a sharp-melt toner, the color reproduction range of a copy can be widened and a color copy faithful to a multicolor image of a document can be obtained satisfactorily.

Such a sharp-melt toner includes, for example, a binder resin such as a polyester resin or a styrene-acrylic resin, a colorant (a dye, a sublimable dye),
The toner is manufactured by melt-kneading, pulverizing and classifying a charge control agent and the like. If necessary, an external addition step of adding various external additives to the toner may be added.

The color toner preferably uses a polyester resin as the binder resin in consideration of the fixing property and the sharp melt property. The sharp melt polyester resin is a polymer compound having an ester bond in the main chain of a molecule synthesized from a diol compound and a dicarboxylic acid. In particular,

[0025]

Embedded image (Wherein R is an ethylene or propylene group, x,
y is a positive integer of 1 or more, and the average value of x + y is 2 to 10. A) a bisphenol derivative or a substituted product thereof as a diol component and a carboxylic acid component comprising a divalent or higher carboxylic acid or an acid anhydride thereof or a lower alkyl ester thereof (for example, fumaric acid, maleic acid, maleic anhydride, Phthalic acid, terephthalic acid,
A polyester resin obtained by co-condensation polymerization with at least trimellitic acid and pyromellitic acid) is more preferable because it has sharp melting characteristics.

The softening point of the sharp melt polyester resin is preferably from 60 to 120 ° C. FIG. 2 shows the softening point characteristics of the toner containing the sharp melt polyester resin as a binder resin.

Using a flow tester CFT-500 type (manufactured by Shimadzu Corporation), a die (nozzle) diameter of 0.5 mm,
A plunger descent-temperature curve of toner drawn when a 50 kg extrusion load is applied to a thickness of 1.0 mm, the preheating time is 300 seconds, the preheating time is 300 seconds, and the temperature is increased at a constant speed of 5 ° C./min ( (Hereinafter referred to as a softening S-shaped curve). The toner used as the sample is a fine powder precisely weighed 1 to 3 g, and the cross-sectional area of the plunger is 10 cm ² . The softening S-shaped curve is as shown in FIG. As the temperature rises at a constant speed, the toner is gradually heated and starts to flow (plunger descent A → B). When the temperature is further increased, the toner in the molten state flows out greatly (B → C → D), the plunger descent stops, and the process ends (D → E).

The height H of the S-shaped curve indicates the total amount of outflow, and H /
The temperature T ₀ corresponding to the C point 2 indicates the softening point of the toner.

Such a sharp-melt toner or resin is defined as having a temperature at which the melt viscosity is 10 ⁵ , T ₁ ,
When the temperature at which 5 × 10 ⁴ cp is indicated is T ₂ , T ₁ = 90 to 150 ° C. | ΔT | = | T ₁ −T ₂ | = 5
A resin that satisfies the condition of 30 ° C.

A sharp-melt toner or resin having such a temperature-melt viscosity characteristic is characterized in that the viscosity thereof is extremely sharply reduced by heating. Such a decrease in viscosity causes appropriate mixing between the uppermost toner layer and the lowermost toner layer, and furthermore, sharply increases the transparency of the toner layer itself and causes good color-reduction mixing.

As a transfer medium as a final transfer material, paper,
Cloths, metals, heat-resistant plastics, ceramics such as tiles and the like are used.

Next, specific examples of the present invention will be described.

Example 1 An unfixed image was formed on the transfer layer 14 of the transfer picture transfer material 1 shown in FIG. 1 by CLC700 manufactured by Canon Inc., and the image was transferred to an oven at 160 to 180 ° C. for 30 minutes.
Leave to set for 2 seconds. The softening point of the toner for CLC700 is 100 ° C. The release layer 13 provided so as to be easily peeled off from the transfer layer 14 on which the toner is placed and the adhesive layer 12 is peeled off from the base material 11, and the portion on which the toner is placed is placed down on the transfer target. Here, it specifically covers a sheet metal used for a body of a car or the like. Then, hot pressing is performed at about 110 ° C. for 10 seconds. At this time, since air enters between the sheet metal and the polyvinyl alcohol layer, air is removed by rubbing with paper such as silbon paper.
These steps are repeated two or three times. After these steps, the transfer layer 14 is softened with a mixed solution of about 20% water and about 80% ethyl alcohol. In this way, the toner image was transferred to the sheet metal of the transfer medium at a transfer efficiency of about 100%, and a sufficiently good image was obtained.

Comparative Example 1 When the oven-fixed image obtained in Example 1 is retransferred, hot pressing at a temperature exceeding 180 ° C. causes a high-temperature offset. 100 ° C
Even when hot pressing is performed at a lower temperature, the toner image is not sufficiently transferred to the transfer medium.

Example 2 An unfixed image obtained in the same manner as in Example 1 was transferred to a transfer picture material 1 using a heat roller type fixing device 3 as shown in FIG. . FIG. 3 will be described below.

Reference numeral 31 denotes a fixing roller, and 32 denotes a pressure roller, each of which has a halogen heater 3 as a heat source.
1a and 32b, and rotate by pressing against each other.

When the transfer material 1 carrying the toner image T on the fixing roller 31 side is conveyed in the direction of the fixing device 3, and then the transfer material 1 is conveyed while being held between the fixing rollers 31 and 32, During that time, the toner image T on the transfer material 1 is heated and pressed, and is melted and fixed on the transfer material 1 to be fixed. The fixing is performed at a fixing temperature of 170 ° C. and a pressure of about 2 kg / cm ^2.
Do with.

The fixed toner image T is hot-pressed at 110 ° C. in the same manner as in the first embodiment. At this time, the pressure of the press machine is 0.2 kg / cm ² .

The retransferred toner image T was very good, and a transferred image having a transfer efficiency of about 100% was obtained.

[Comparative Example 2] When the hot roller-fixed image obtained in Example 2 is retransferred, if hot pressing is performed at a temperature exceeding 180 ° C, high-temperature offset occurs. Also, 100
Even if hot pressing is performed at a temperature lower than ℃, the toner image T is not sufficiently transferred to the transfer medium.

Example 3 An unfixed image obtained in the same manner as in Example 1 was transferred using a film-type heat-fixing fixing device 4 as shown in FIG. Things. FIG. 4 will be described below.

Reference numeral 47 denotes a heat-resistant fixing film in the form of an endless belt. The left driving roller 48, the right driven roller 49, the driving roller 48 and the driven roller 4
A low-heat-capacity linear heating element 50 as a heating element disposed below 9 is suspended between the three members 48, 49, 50 parallel to each other.

The driven roller 49 also serves as a tension roller for the endless belt-shaped fixing film 47.
The fixing film 47 serves as a recording material carrying on its upper surface an unfixed toner image T conveyed from an image forming unit (not shown) at a predetermined peripheral speed in a clockwise direction accompanying the clockwise rotation of the driving roller 48. Is rotated at the same peripheral speed as the transfer speed of the transfer material 1 without wrinkles, meandering, and speed delay.

Reference numeral 51 denotes a pressure roller having a rubber elastic layer of silicone rubber or the like having good releasability as a pressure member. The pressure roller 51 sandwiches the descending film portion of the endless belt-shaped fixing film 47 and heats the sheet. The lower surface of the body 50 is pressed against the lower surface of the body 50 by a biasing means (not shown) with a total pressure of, for example, 4 to 7 kg, and rotates counterclockwise in the forward direction of the transfer material 1 in the transport direction. The pressure roller 51 is a silicone rubber roller having an outer diameter of 30 mm and a thickness of 7 mm, which is formed concentrically and integrally with the outer periphery of a cored bar by molding.

The heating element 50 is a low-heat-capacity linear heating element whose longitudinal direction is a direction (width direction of the film) that intersects with the surface movement direction of the fixing film 47, and includes a heater substrate 52, an energized heating resistor (heating element) 53. , A temperature measuring element 54, etc., which are fixedly supported by being attached to and held by a heater support 55.

In the film-type heat fixing device having such a configuration, the transfer material 1 carrying the unfixed toner image T on the upper surface
Is transported between the fixing film 47 and the pressure roller 51, the heating is performed by the heating element 50 to perform fixing. Fixing is performed at a fixing temperature of 170 to 180 ° C. and a pressure of about 0.4.
Perform at 5 kg / cm ² .

The fixed toner image T is hot-pressed at 110 ° C. in the same manner as in the first embodiment. At this time, the pressure of the press machine is 0.2 kg / cm ² .

The retransferred toner image was very good, and a transferred image having a transfer efficiency of about 100% was obtained.

[Comparative Example 3] When the film-type heat-fixed image obtained in Example 3 is retransferred, hot pressing at a temperature exceeding 180 ° C. causes a high-temperature offset. Also, 1
Even if hot pressing is performed at a temperature lower than 00 ° C., the toner image T is not sufficiently transferred to the transfer medium.

[0050]

As described above, according to the present invention,
By lowering the fixing temperature at the time of retransfer from the first fixing temperature, high-temperature offset and low-temperature offset can be prevented, and a sufficiently good color image can be formed on the transfer medium.

Further, according to the present invention, by lowering the fixing temperature and pressure during retransfer from the fixing temperature and pressure during first transfer, high-temperature offset and low-temperature offset can be prevented, and a sufficiently satisfactory color can be obtained. An image can be formed on a transfer medium.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a copy transfer material used in the present invention.

FIG. 2 is a dissolution characteristic diagram of a toner preferably used in the present invention.

FIG. 3 is a schematic sectional view of a fixing device used in a second embodiment.

FIG. 4 is a schematic sectional view of a fixing device used in a third embodiment.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 transfer picture transfer material 3 heat roller fixing device 4 film heat fixing device 11 base material 12 adhesive layer 13 release layer 14 transfer layer 31 fixing roller 32 pressure roller 47 fixing film 50 heating element 51 pressure roller T toner image

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G03G 7/00

Claims (12)

(57) [Claims] 1. A color in which an image transferred by an electrophotographic method is once fixed on a transfer material having a polyvinyl alcohol layer on a support, and only a toner is transferred again without providing a release layer on another transfer medium. A color image forming method, wherein the fixing temperature at the time of retransfer is lower than the first fixing temperature. 2. The color image forming method according to claim 1, wherein the difference between the first fixing temperature and the fixing temperature at the time of retransfer is 5 to 100 ° C. 3. The color image forming method according to claim 1, wherein the fixing temperature at the time of retransfer is higher than the softening point of the toner. 4. The color image forming method according to claim 1, wherein the support is paper or PET film. 5. The color image forming method according to claim 1, wherein the transfer medium is selected from paper, cloth, metal, heat-resistant plastic and ceramics. 6. A color in which an image transferred by an electrophotographic method is once fixed to a transfer material having a polyvinyl alcohol layer on a support, and only the toner is transferred again without providing a release layer on another transfer medium. A color image forming method, wherein the fixing temperature during retransfer is lower than the first fixing temperature, and the pressure during retransfer is lower than the pressure during first fixing. 7. The color image forming method according to claim 6, wherein a difference between the first fixing temperature and the fixing temperature at the time of retransfer is 5 to 100 ° C. 8. The color image forming method according to claim 6, wherein the pressure at the time of retransfer is equal to or less than 1/2 of the pressure at the time of first fixing. 9. The color image forming method according to claim 6, wherein the fixing temperature at the time of retransfer is higher than the softening point of the toner. 10. The color image forming method according to claim 6, wherein the support is paper or PET film. 11. The color image forming method according to claim 6, wherein the transfer medium is selected from paper, cloth, metal, heat-resistant plastic and ceramics. 12. The color image forming method according to claim 6, wherein the transfer medium is a ceramic such as paper, cloth, metal, heat-resistant plastic, or tile.