Patent Application
20060024603
This application is base upon and claims the benefit of priority from the prior Japanese Patent Application No. 2004-221358 filed on Jul. 29, 2004, the entire contents of which are incorporated herein by reference.
The present invention relates to toner and a manufacturing method thereof used in a dry type electro-photographic apparatus such as a copier and a printer.
In a dry type electro-photographic apparatus, the heating temperature for a fixing device when fixing a toner image on a sheet of paper is lowered, thus the consumption energy of the electro-photographic apparatus can be reduced greatly. Therefore, fixing at a lower temperature is desired strongly and study has been given greatly to improvement of the low temperature fixing property.
As an art for improving the lower temperature fixing property, for example, as disclosed in Japanese Patent Application Publication No. 2003-270853, it is known to use crystalline polyester resin as a binder resin material for toner.
By use of crystalline polyester resin as a binder resin material for toner, toner can be fixed at a lower temperature. However, crystalline polyester resin is hygroscopic, so that when crystalline polyester resin is used as a toner material, the so-called blocking phenomenon that toner makes contact mutually and is condensed occurs, thus a problem arises that the preservation property of toner is reduced. Further, when the hygroscopicity is high, a problem arises that the charging stability of toner in a humid environment is insufficient. Furthermore, in continuous printing, since low temperature fixing toner is apt to be softened, when a sheet of paper is ejected immediately after fixing, a phenomenon that the toner is transferred to the back of another sheet of paper occurs.
When the amount of crystalline polyester is reduced in consideration of these problems, for the improvement of the low temperature fixing property by use of crystalline polyester, sufficient results cannot be obtained.
An object of the present invention is to provide toner which is good in the low temperature fixing property and excellent in the preservation property and charging stability and even in continuous printing, is prevented from transferring to the back.
According to the embodiments of the present invention, there is provided a toner containing binder resin and a coloring agent, wherein the toner comprises a mixture of first toner and second toner which are different in a component of the binder resin from each other and only either of the first toner and the second toner contains crystalline polyester resin.
Further, according to the embodiments of the present invention, there is provided a toner comprising first toner including a main component of binder resin containing at least one of amorphous polyester resin and styrene-acrylic resin and crystalline polyester resin and also containing a coloring agent; and second toner including a main component of binder resin containing at least one of amorphous polyester resin and styrene-acrylic resin and also containing a coloring agent.
Furthermore, according to the embodiments of the present invention, there is provided a toner manufacturing method comprising: obtaining first toner containing a coloring agent, first binder resin, and crystalline polyester resin; obtaining second toner containing a coloring agent and second binder resin different in a component from the first binder resin; adding a first additive to the first toner; adding a second additive different in a component from the first additive to the second toner; and mixing the first toner and the second toner.
Hereinafter, the embodiments of the present invention will be explained.
The toner relating to the embodiments of the present invention is composed of first toner and second toner which are different in the binder resin material from each other.
The first toner contains crystalline polyester resin as binder resin. On the other hand, the second binder resin contains no crystalline polyester resin and is composed of, for example, amorphous polyester resin and styrene acrylic resin.
Hereinafter, the resin material used in the embodiments will be explained first.
(1) Manufacture of Amorphous Polyester Resin a:
50 parts of BPA-PO (propylene oxide additive of bisphenol A), 20 parts of BPA-EO (ethylene oxide additive of bisphenol A), 14 parts of terephthalic acid, 12 parts of dodecenylsuccinic anhydride, 8 parts of anhydrous trimellitic acid, and 5 parts of dibutyltin oxide are mixed and polymerized in a container at 210° C. to 230° C. for eight hours. The container is decompressed slowly and evacuated to 8 kPa, and the polymerization is further continued, and amorphous polyester resin having a softening point of 148° C. is obtained.
(2) Manufacture of Amorphous Polyester Resin b:
75 parts of BPA-PO (propylene oxide additive of bisphenol A), 10 parts of terephthalic acid, 20 parts of fumaric acid, and 5 parts of dibutyltin oxide are mixed and polymerized in a container at 210° C. to 230° C. for eight hours. The container is decompressed slowly and evacuated to 8 kPa, and the polymerization is further continued, and amorphous polyester resin having a softening point of 101° C. is obtained.
(3) Manufacture of Crystalline Polyester Resin:
95 parts of 1,4-butanediol, 5 parts of glycerine, 100 parts of fumaric acid, and 5 parts of hydroquinone are mixed and reacted at 150° C. to 170° C. for five hours, and then the container is heated to 200° C., decompressed slowly to continue the reaction for one hour, and evacuated to 8 kPa, and then the reaction is continued additionally for one hour, and crystalline polyester resin having a melting point of 125° C. is obtained.
(4) Manufacture of Styrene Acrylic Resin:
85 parts of styrene, 15 parts of buthyl acrylate, and 0.2 parts of di-t-buthyl peroxide telephthalate are mixed, and air is replaced with nitrogen, and the parts are polymerized at 85° C. for 10 hours. Thereafter, the parts are polymerized at 95° C. for 3 hours, and after cooling, the reactant is filtered and rinsed, and then dried at 50° C., and styrene acrylic resin having a softening point of 120° C. is obtained.
Further, crystalline polyester resin has a crystalline part in the resin and the crystallinity is generally 50% or lower. Crystalline polyester resin, when heated, has an area where the viscosity is suddenly reduced, while amorphous polyester resin, as the temperature rises, has a wide temperature area where the viscosity is slowly reduced, and in respect of it, amorphous polyester resin and crystalline polyester resin are distinguished from each other.
In addition to the resin materials manufactured in this way, the following articles are prepared.
As wax, two kinds of wax such as vegetable wax (Rice Wax by NS Chemical, Ltd.) and polypropylene wax (NPO55 by Mitsui Chemicals, Inc.) are prepared. As a charging control agent, a Zr complex compound (TN-105 by Hodogaya Chemical Co., Ltd.) is prepared and as a coloring agent, carbon black (NIPEX90 by Degussa Japan Co., Ltd) is prepared.
Using these materials, at the ratios shown in
Next, using the first to sixth toner before an additive is added, various printing toner is manufactured. These toner will be explained as toner relating to the embodiments and comparison examples.
As shown in
As a toner additive, additive set A shown in
And, toner 1 before an additive is added, toner 5 before an additive is added, and additive set A are all put into a mixing bath of a Henschel mixer at a time and a stirring blade in the Henschel mixer is rotated at 30 m/s for 10 minutes. By this method, the mixing of toner and the additive addition process are finished and toner relating to Embodiment 1 is obtained.
As shown in
Similarly to Embodiment 1, toner 1 before an additive is added, toner 5 before an additive is added, and additive set A are mixed in the Henschel mixer and toner relating to Embodiment 2 is obtained.
As shown in
Similarly to Embodiment 1, toner 1 before an additive is added, toner 6 before an additive is added, and additive set A are mixed in the Henschel mixer and toner relating to Embodiment 3 is obtained.
As shown in
Similarly to Embodiment 1, toner 1 before an additive is added, toner 6 before an additive is added, and additive set A are mixed in the Henschel mixer and toner relating to Embodiment 4 is obtained.
As shown in
Similarly to Embodiment 1, toner 2 before an additive is added, toner 5 before an additive is added, and additive set A are mixed in the Henschel mixer and toner relating to Embodiment 5 is obtained.
As shown in
Similarly to Embodiment 1, toner 2 before an additive is added, toner 6 before an additive is added, and additive set A are mixed in the Henschel mixer and toner relating to Embodiment 6 is obtained.
As shown in
Comparison Example 2
100 parts by weight of toner 2 before an additive is added is prepared, and toner 2 before an additive is added and additive set A are mixed in the Henschel mixer similarly to Embodiment 1, and toner relating to Comparison example 2 is obtained.
100 parts by weight of toner 5 before an additive is added is prepared, and toner 5 before an additive is added and additive set A are mixed in the Henschel mixer similarly to Embodiment 1, and toner relating to Comparison example 3 is obtained.
100 parts by weight of toner 6 before an additive is added is prepared, and toner 6 before an additive is added and additive set A are mixed in the Henschel mixer similarly to Embodiment 1, and toner relating to Comparison example 4 is obtained.
Further, the toner relating to Embodiments 1 to 6 and Comparison examples 1 to 4 aforementioned is all manufactured by Manufacturing method 1 among the four manufacturing methods shown in
The evaluation results of the toner relating to Embodiments 1 to 6 and Comparison examples 1 to 4 aforementioned are shown in
For evaluation, 8 parts by weight of the toner relating to each of the embodiments and comparison examples are mixed with 92 parts by weight of ferrite carrier coated with silicone with an average diameter of 40 μm to form a developer. Each developer is mounted in a copier Premage DP4503JPD, which is modified, manufactured by Toshiba Tech, Ltd. and is printed and evaluated.
The evaluation items are indicated below.
(1) Lowest Fixing Temperature:
While raising the temperature of the mixing unit of the copier sequentially to 90° C. to 240° C., according to predetermined image data, a toner image is fixed on a sheet of paper. On the image fixed through the fixing unit, a rubbing member with a load of 300 g having an attached cotton pad moves back and forth 5 times using a fastness testing machine (by Daiei Kagaku Seiki mFG. Co., Ltd.). The image before and after rubbing is measured by a reflection densitometer RD-917 (by Macbeth, Ltd.) and among the image fixing temperatures when the ratios (image density after rubbing/image density before rubbing) of the image before and after rubbing are higher than 70%, the lowest temperature is defined as a lowest fixing temperature. The lowest fixing temperature is preferably 160° C. or lower.
(2) Preservation Property of Toner:
Toner of 20 g relating to each of the embodiments and comparison examples is put into a bottle of 100 cc, is covered with a lid, is fixed to a jig, is put into a thermostatic chamber (BK-42 type by Yamato Scientific Co., Ltd.) set at a water temperature of 55° C., is left as it is for 8 hours, then is tapped 3 times using a powder tester (by Hosokawa Micron Corporation), and is put through a sieve of 42-mesh. Thereafter, the powder tester is vibrated for 10 seconds and the toner amount left on the sieve is measured. When the toner amount measured is 2 g or smaller, it is defined as satisfactory and when the toner amount measured is larger than 2 g, the preservation property is defined as unsatisfactory.
(3) Charging Amount of Toner:
Each toner is mixed with a carrier to form a developer and before using it for printing, a fixed amount is sampled. The sampled developer is put into blow-off charging amount measuring instrument TB-220 (by Kyocera Chemical Corporation) and the initial charging amount is measured. Next, the developer is put into the copier and on the basis of predetermined image data, 50,000 sheets are printed continuously. After continuous printing, the charging amount of the developer is measured in the same way as with the initial charging amount and the initial charging amount is compared with the charging amount after continuous printing. When the difference between the two charging amounts is 5 μC or larger or the absolute value of the charging amount after printing of 50,000 sheets is 10 μC/g or smaller, the chargeability is judged as unsatisfactory and in the other cases, the chargeability is judged as satisfactory.
(4) Image Density:
In the initial state immediately after the developer is put into the copier and printing is started, the solid printed parts of images on three sheets printed are measured by the reflection densitometer and the mean value thereof is defined as image density. After 50,000 sheets are printed continuously, in the same way as in the initial state, the image density is measured. When the image density is 1.3 or higher, it is defined as satisfactory and when the image density is lower than 1.3, it is defined as unsatisfactory.
(5) Scattering of Toner:
After continuous printing of 50,000 sheets, the inside of the copier is observed, and when no soil due to scattering of toner is recognized in the copier, it is assigned O, and when soil due to scattering of toner is recognized in the copier, it is assigned Δ, and when soil due to accumulation of toner is recognized in the copier, it is assigned X.
(6) Sticking of Images:
Continuous printing is executed, and the images passing the fixing unit are stacked up in a paper ejection unit of the copier, are kept as they are, and are cooled down to the room temperature, and then whether the image is transferred to the back of each sheet of paper or not and sheets of paper stick to each other or not are checked. When sticking of sheets of paper or image transfer to the back occurs, X is assigned and in the other cases, O is assigned.
On the other hand, in the toner relating to Comparison examples 1 and 2, although the fixing property is satisfactory, the preservation property and sticking property are bad, and scattering of toner is observed. In the toner relating to Comparison examples 3 and 4, the fixing property is inferior.
From the aforementioned, when the first toner containing crystalline polyester resin is used, it is found that toner having a low fixing temperature is obtained. However, in toner composed of only the first toner, there is a problem imposed in the preservation property and in toner not containing inversely the first toner, the fixing property is inferior.
On the other hand, in a mixture of the first toner and second toner, the balance between the fixing property and the preservation property is superior, and the chargeability is stable, and scattering of toner is little.
The reason seems to be that there exists toner containing no crystalline polyester around toner containing crystalline polyester resin, so that the first toner is prevented from mutual contact, thus the hygroscopicity of the first toner is practically reduced. Therefore, when the first toner and second toner are mixed and used as developer toner, the low temperature fixing improving function originally possessed by crystalline polyester resin is maintained, and the problem of reduction in the chargeability due to the hygroscopicity of crystalline polyester resin is solved, and superior toner can be obtained.
The mixing ratio of the first toner to the second toner is preferably 2:3 to 3:2 or so when the amount of crystalline polyester resin contained in the first toner is 2.5 parts by weight to 50 parts by weight. When the amount of crystalline polyester resin contained in the first toner is smaller than 2.5 parts by weight, the low temperature fixing property improving effect by crystalline polyester resin is insufficient, while when the amount of crystalline polyester resin is larger than 50 parts by weight, the chargeability of the toner is degraded due to the hygroscopicity of crystalline polyester resin. Further, from a view point of preventing the first toner from mutual sticking, the mixing ratio of the first toner to the second toner is preferably closer to 1:1 and the ratio of 2:3 to 3:2 or so is the mixable range.
Next, the toner relating to Embodiments 7 to 10 will be explained.
As shown in
As shown in
As shown in
As shown in
To manufacture the toner relating to Embodiments 7 to 10, similarly to Embodiment 1, the method for mixing all the first toner, second toner, and additive in the Henschel mixer at a time is adopted.
The amount of crystalline polyester resin contained in the toner relating to Embodiments 7 to 10 is also shown in
Further, the results of evaluation of the toner relating to Embodiments 7 to 10 executed in the same way as with Embodiment 1 are shown in
Next, the toner relating to Embodiments 11 to 17 will be explained by referring to
As shown in
As shown in
Each toner finishing the processing of the additive in this way is mixed by the V blender for 5 minutes and toner relating to Embodiment 12 is obtained.
As shown in
As shown in
As shown in
As shown in
As shown in
With respect to the toner additive addition process and mixing process, several methods are conceivable. Namely, (1) a method for mixing the first toner, second toner, and additive all at a time and performing the additive addition process simultaneously with mixing (Manufacturing method 1 shown in
At that time, the device used for the additive addition process and the device used for the mixing process are preferably different from each other and as a device used for the additive addition process, the Henschel mixer, a microspeed mixer, or a turbo-mixer in which the stirring blade rotates at high speed and the mixing speed is high is preferably used. On the other hand, for the mixing process, rather than the Henschel mixer, the V blender or an S blender in which the mixing strength is weak is desirably used. The reason is that when the mixing force at the time of the additive addition process is insufficient, the additive is separated from the toner surface after the processing, and particularly toner containing crystalline polyester resin is easily affected by humidity, thus the long-term stability of the chargeability is impaired. On the other hand, when toner is stirred with strong stirring force at the time of toner mixing, the adhesion state of the additive to the toner surface becomes too strong and the toner fluidity is impaired. From this reason, among Manufacturing methods 1 to 4 shown in
Further, in a method such as Manufacturing method 3, the amount of an additive to each of the first toner and second toner can be changed freely. The first toner containing crystalline polyester resin has high hygroscopicity and the fixable temperature is often lower than that of the second toner. Due to such a difference, toner may not be charged and fixed uniformly. Therefore, in the first toner and second toner, by changing the additive kind and amount, the chargeability and fixing property can be improved. Generally, the amount of additive to the first toner is preferably larger than the amount of additive to the second toner.
Further, the materials used in the present invention are not limited to those described in the embodiments aforementioned and various materials can be used.
Crystalline polyester resin is obtained, for example, by using a monomer containing a carboxylic acid component composed of a multivalent (bivalent or higher) carboxylic acid compound and an alcohol component composed of multivalent (bivalent or higher) alcohol.
As an acid component, fumaric acid, maleic acid, citraconic acid, itaconic acid, glutaconic acid, phthalic acid, isophthalic acid, terephthalic acid, cychlohexanedicarboxylic acid, succinic acid, adipic acid, sebacic acid, and azelaic acid may be used.
As an alcohol component, ethylene glycol, propylene glycol, 1,4-butanediole, 1,3-butanediole, 1,5-pentanediole, 1,6-hexanediole, neopentyl glycol, glycerine, trimethylolethane, and trimethylolpropane may be used.
Particularly, a compound having alkyl radical of carbon number 16 or more or alkenyl radical and a crystalline compound generally in a wax form obtained by condensing and polymerizing an alcohol component containing 80 mol % or more of diole of carbon number 2 to 6 and a carboxylic acid component containing 80 mol % or more of fumaric acid are preferable. These compounds may be used individually or as a mixture of two or more kinds.
As wax, low molecular weight polyethylene, low molecular weight polypropylene, polyoelfin copolymer, polyolefin wax, microcrystalline wax, paraffin wax, carnauba wax, and rice wax may be used.
As a coloring agent, carbon black and organic or inorganic pigments and dyes may be used.
As carbon black, acetylene black, furnace black, thermal black, channel black, and ketchen black may be used.
Further, as pigment, for example, first yellow G, benzidine yellow, indofast orange, Irgazine red, carmine FB, permanent bordeaux FRR, pigment orange R, lithol red 2G, lake red C, rhodamine FB, rhodamine B lake, phthalocyanine blue, pigment blue, Brilliant green, phthalocyanine green, and quinacridone may be used individually or as a mixture.
As a charging control agent, for example, when a coloring agent is carbon black or an achromatic pigment or dye, a metallized azoic compound containing at least one of the group of a complex and a complex salt of iron, cobalt, and chromium may be preferably used. Further, when the coloring agent is a chromatic pigment or dye, a metallized salicylic acid derivative compound containing at least one of the group of a complex and a complex salt of zirconium, zinc, chromium, and boron may be used.
To adjust the flowability and chargeability, inorganic fine particles of 0.2 to 3 wt % can be mixed with toner particles. As such inorganic fine particles, silica, titania, alumina, titaniac acid strontium, and tin oxide may be used individually or as a mixture of two kinds or more.
Use of inorganic fine particles surface-treated by a hydrophobic agent beforehand is preferable from a viewpoint of improvement of the environment stability. Further, with toner particles, in addition to such an inorganic oxide, resin particles with a diameter of 1 μm or smaller may be mixed for improvement of the cleaning property.
Additionally, within a scope which is not deviated from the object of the present invention, the present invention may be modified variously.
As explained above, the toner of the present invention is composed of first toner and second toner which are different in the binder resin from each other and is structured so as to contain crystalline polyester resin only in the first toner, so that good results can be obtained that the low temperature fixing property is satisfactory, and the preservation property and charging stability are superior, and in continuous printing, toner is not transferred to the back of each sheet of paper.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2004-221358 | Jul 2004 | JP | national |
