CA1132827A - Electrophotographic toner comprising particles of a specific size distribution - Google Patents
Electrophotographic toner comprising particles of a specific size distributionInfo
- Publication number
- CA1132827A CA1132827A CA307,348A CA307348A CA1132827A CA 1132827 A CA1132827 A CA 1132827A CA 307348 A CA307348 A CA 307348A CA 1132827 A CA1132827 A CA 1132827A
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- microns
- weight
- toner
- less
- particles
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- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
- G03G9/00—Developers
- G03G9/08—Developers with toner particles
- G03G9/0819—Developers with toner particles characterised by the dimensions of the particles
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- General Physics & Mathematics (AREA)
- Developing Agents For Electrophotography (AREA)
Abstract
ELECTROPHOTOGRAPHIC TONER
Abstract A toner material for use in developing images in an electrostatographic device is disclosed. The toner particles are initially classified according to a size distribution wherein less than 15% by weight are greater than 16 microns, between 7 and 15% by weight are less than 5 microns the remainder being from 5 to 16 microns and wherein the median particle size by weight is from 8 to 12 microns.
The toner is used in a developer mix with carrier particles, and preferably the toner carrier mix is equilibrated such that the action of the developer mix and the machine provide a toner particle size distribution wherein less than 12% by weight are greater than 16 microns, between 15 and 30% by weight are less than 5 microns, the remainder being from 5 to 16 microns, and wherein the median particle size by weight is between 6.5 and 9.5 microns. An equilibrated toner particle distribution is also disclosed.
Abstract A toner material for use in developing images in an electrostatographic device is disclosed. The toner particles are initially classified according to a size distribution wherein less than 15% by weight are greater than 16 microns, between 7 and 15% by weight are less than 5 microns the remainder being from 5 to 16 microns and wherein the median particle size by weight is from 8 to 12 microns.
The toner is used in a developer mix with carrier particles, and preferably the toner carrier mix is equilibrated such that the action of the developer mix and the machine provide a toner particle size distribution wherein less than 12% by weight are greater than 16 microns, between 15 and 30% by weight are less than 5 microns, the remainder being from 5 to 16 microns, and wherein the median particle size by weight is between 6.5 and 9.5 microns. An equilibrated toner particle distribution is also disclosed.
Description
`: :
`
19 Background of the Invention This invention relates generally to size classi~
21 fied small particles, and more specifically to size classi-22 fication of electrostatographic toner particles, and thei~
23 use adamixed with carrier particles in the electrophoto-24 graphic copying process.
In electrophotography, a photoconductor is charged 26 and then exposed imagewise to light. In the area o~ the 27 photoconductor exposed to light, the charge dissipates or 28 decays while the dark areas retain the èlectrostatic charge.
977066 *
~13Z8Z7 1 The diEference in the charge levels between the
`
19 Background of the Invention This invention relates generally to size classi~
21 fied small particles, and more specifically to size classi-22 fication of electrostatographic toner particles, and thei~
23 use adamixed with carrier particles in the electrophoto-24 graphic copying process.
In electrophotography, a photoconductor is charged 26 and then exposed imagewise to light. In the area o~ the 27 photoconductor exposed to light, the charge dissipates or 28 decays while the dark areas retain the èlectrostatic charge.
977066 *
~13Z8Z7 1 The diEference in the charge levels between the
2 areas exposed to light and the dark areas prod-lces electri-
3 cal fields therebetween. Thereafter, the resultant latent
4 electrostatic image on the photoconductor is developed by
5 depositing small colored particles, which are known as toner
6 particles having a charge so as to be directed by the electri-
7 cal fields to the image areas of the photoconductor to
8 develop the electrostatic image.
9 A number of means are known for developing the
10 latent electrostatic image by the application of the toner
11 particles. One of these is known as cascade development and
12 is described in U.S. Patent No. 2,638,552 to Wise. Another
13 means is known as the magnetic brush process. This method
14 is described in U.S. Patent No. 2,874,063 to r7reig~
In each of the cascade and magnetic brush develop-16 ment processes, a two component developer material is 17 utilized. The developer material comprises a mixture of 18 small toner particles and relatively large carrier particles.
19 The toner particles are held on the surfaces of the rela-20 tively large carrier particles by electrostatic forces which 21 develop from the contact between the toner and carrier 22 particles producing triboelectric charging of the toner and 23 the carrier to opposite polarities. When the developer 24 material is moved into contact with the latent electrostatic 25 image of the photoconductor, the toner particles are attracted 26 to the latent image.
27 The toner and carrier particles of the developer 28 material are specially made and processed so that the toner 1~3Z8Z7 1 obtains the correct charge polarity and magnitude of charge 2 to insure that the toner particles are preferentially 3 attracted to the desired image areas of the photoconductor.
4 The toner particles are then transferred electrostatically to the desired copy sheet, after which the transferred image 6 of toner particles is fused by heat and/or pressure to 7 produce the final product of a fused copy of the desired 8 image.
9 One of the problems encountered is to provide the best possible quality of a final image on the copy sheet.
11 This is generally referred to as copy quality. Copy quality 12 includes such things as image clarity, i.e., clear delineation 13 of lines; uniform darkness of the image areas; background 14 quality, i.e., grayness or lack of it in the background lS areas; and other somewhat intangible eatures that go toward 16 making a good "quality" copy.
17 Other factors that merit consideration in the 18 developing process vis-a-vis toner is the overall utilization 19 of toner per copy. Of course from an economic point of view the less toner used per any given image the better. Also in 21 a system in which unused toner is cleaned from the air by 22 use of a filter, it is important to minimize the amount of 23 unused toner to thereby extend the life of the filter.
24 Further, when heat fusing is used it is desirable to provide an image that will have the best possible heat 26 transfer characteristics to minimize the amount of heat 27 needed to fuse the image. This is important not only from i~3Z8Z7 1 an energy point of view, but also with more rapid heat 2 transfer by the toner, the fusing time or temperature can be 3 reduced.
4 All of these factors play important roles in 5 developing an optimum toner particle.
6 One of the principal contributing characteristics 7 of the toner particles in achieving optimum results in the 8 above-noted areas is the size and size distribution of the 9 toner particles. This fact in itself is well known, and 10 there have been several prior art proposals for various lI systems of toner particle classification.
12 U.S. Patent No. 3,674,736 to Sherman et al discloses 13 pigmented polymer particles suitable "for use as toner...
14 and as developers for electrostatic process," and the method
In each of the cascade and magnetic brush develop-16 ment processes, a two component developer material is 17 utilized. The developer material comprises a mixture of 18 small toner particles and relatively large carrier particles.
19 The toner particles are held on the surfaces of the rela-20 tively large carrier particles by electrostatic forces which 21 develop from the contact between the toner and carrier 22 particles producing triboelectric charging of the toner and 23 the carrier to opposite polarities. When the developer 24 material is moved into contact with the latent electrostatic 25 image of the photoconductor, the toner particles are attracted 26 to the latent image.
27 The toner and carrier particles of the developer 28 material are specially made and processed so that the toner 1~3Z8Z7 1 obtains the correct charge polarity and magnitude of charge 2 to insure that the toner particles are preferentially 3 attracted to the desired image areas of the photoconductor.
4 The toner particles are then transferred electrostatically to the desired copy sheet, after which the transferred image 6 of toner particles is fused by heat and/or pressure to 7 produce the final product of a fused copy of the desired 8 image.
9 One of the problems encountered is to provide the best possible quality of a final image on the copy sheet.
11 This is generally referred to as copy quality. Copy quality 12 includes such things as image clarity, i.e., clear delineation 13 of lines; uniform darkness of the image areas; background 14 quality, i.e., grayness or lack of it in the background lS areas; and other somewhat intangible eatures that go toward 16 making a good "quality" copy.
17 Other factors that merit consideration in the 18 developing process vis-a-vis toner is the overall utilization 19 of toner per copy. Of course from an economic point of view the less toner used per any given image the better. Also in 21 a system in which unused toner is cleaned from the air by 22 use of a filter, it is important to minimize the amount of 23 unused toner to thereby extend the life of the filter.
24 Further, when heat fusing is used it is desirable to provide an image that will have the best possible heat 26 transfer characteristics to minimize the amount of heat 27 needed to fuse the image. This is important not only from i~3Z8Z7 1 an energy point of view, but also with more rapid heat 2 transfer by the toner, the fusing time or temperature can be 3 reduced.
4 All of these factors play important roles in 5 developing an optimum toner particle.
6 One of the principal contributing characteristics 7 of the toner particles in achieving optimum results in the 8 above-noted areas is the size and size distribution of the 9 toner particles. This fact in itself is well known, and 10 there have been several prior art proposals for various lI systems of toner particle classification.
12 U.S. Patent No. 3,674,736 to Sherman et al discloses 13 pigmented polymer particles suitable "for use as toner...
14 and as developers for electrostatic process," and the method
15 of making such toners. This patent claims material having
16 an average particle diameter within the range of from about
17 1 to 30 microns (NMD) and a GSD of less than about 1.5. sy
18 extrapolation and the use of Gaussian distribution this can
19 be related to a particular size distribution.
~.erman Offenlegungsschrift 2,522,771 (unexamined 21 published patent application) filed May 22, 1975 and pub-22 lished December 11, 1975 assigned to Xerox, discloses toner 23 particles which essentially have the same distribution as 24 those of the Sherman et al patent. This r~erman reference 25 discloses toner with a size distribution by number or pop-26 ulation wherein less than 30% of the particles are less than 27 5 microns, about 25% are between 8 and 12 microns, and less 28 than 5% are greater than about 20 microns. This ~,erman 11~2~3~7 1 reference also discloses a fine index ratio of less than 2 about 2.50 and a coarse index ratio of less than about 1.50.
3 Summary of the Invention 4 According to the present invention, a size classi-5 fied toner material is provided which has a particle size 6 distribution as follows:
7 less than 15% by weight are greater than 16 8 microns, from 7 to 15% by weight are less than 5 microns, 9 the remainder are from 5 to 16 microns, the median particle 10 size by weight being from 8 to 12 microns.
11 The toner particles are mixed with carrier par-12 ticles to form a developer for use in an electrostatic 13 copying process. The toner as used in a magnetic brush type 14 developer in the presence of carrier while running against 15 the photoconductor surface, will result in equilibration of 16 the toner particle size distribution and will preferably 17 generate the following size distribution:
18 Median by weight 6.5 - 9.5~
19 % by weight < 5~ 15.0 - 30.0%
~ by weight > 16~ <12.0 %
21 In even more particular aspects the size distribu-22 tion of the particles of the original toner is as follows:
23 less than 2~ by weight are greater than 16 microns, 24 between 9 and 15% by weight are less than 5 microns, the 25 remainder are from 5 to 16 microns, the average particle 26 size being from 8.5 to 9.5 microns.
27 Description of the Preferred ~mbodiments 28 It has been found that by utilizing toner classi-29 fied according to this invention, greatly improved results 11328'~7 1 are realized as compared to conventional toner in the areas 2 of copy quality, filter life, toner utili~ation, and fusing 3 quality. Standard or conventional toner, as exemplified by - 4 that used in IBM Series III Copier/Duplicator ls classified 5 as follows:
6 0.8~ + 0.4% by weight less than 5 microns, about 7 35% by weight greater than 16 microns, less than 0.5% by 8 weight greater than 32 microns, the median particle size by g weight being 13.6 + 0.6 microns. In measuring size distri-10 bution a Coulter counter is utilized in a conventional 11 manner.
12 In order to compare toners, examples of various 13 toners were prepared with size distribution as shown in 14 Table I.
Table I
16 Example IExample IIExample III
17 Median Particle Size 13.5~ 11.0~ 8.5u by Weight Percent by Weight .8% 7.1~ 11.8%
19 Less Than 5~
~.erman Offenlegungsschrift 2,522,771 (unexamined 21 published patent application) filed May 22, 1975 and pub-22 lished December 11, 1975 assigned to Xerox, discloses toner 23 particles which essentially have the same distribution as 24 those of the Sherman et al patent. This r~erman reference 25 discloses toner with a size distribution by number or pop-26 ulation wherein less than 30% of the particles are less than 27 5 microns, about 25% are between 8 and 12 microns, and less 28 than 5% are greater than about 20 microns. This ~,erman 11~2~3~7 1 reference also discloses a fine index ratio of less than 2 about 2.50 and a coarse index ratio of less than about 1.50.
3 Summary of the Invention 4 According to the present invention, a size classi-5 fied toner material is provided which has a particle size 6 distribution as follows:
7 less than 15% by weight are greater than 16 8 microns, from 7 to 15% by weight are less than 5 microns, 9 the remainder are from 5 to 16 microns, the median particle 10 size by weight being from 8 to 12 microns.
11 The toner particles are mixed with carrier par-12 ticles to form a developer for use in an electrostatic 13 copying process. The toner as used in a magnetic brush type 14 developer in the presence of carrier while running against 15 the photoconductor surface, will result in equilibration of 16 the toner particle size distribution and will preferably 17 generate the following size distribution:
18 Median by weight 6.5 - 9.5~
19 % by weight < 5~ 15.0 - 30.0%
~ by weight > 16~ <12.0 %
21 In even more particular aspects the size distribu-22 tion of the particles of the original toner is as follows:
23 less than 2~ by weight are greater than 16 microns, 24 between 9 and 15% by weight are less than 5 microns, the 25 remainder are from 5 to 16 microns, the average particle 26 size being from 8.5 to 9.5 microns.
27 Description of the Preferred ~mbodiments 28 It has been found that by utilizing toner classi-29 fied according to this invention, greatly improved results 11328'~7 1 are realized as compared to conventional toner in the areas 2 of copy quality, filter life, toner utili~ation, and fusing 3 quality. Standard or conventional toner, as exemplified by - 4 that used in IBM Series III Copier/Duplicator ls classified 5 as follows:
6 0.8~ + 0.4% by weight less than 5 microns, about 7 35% by weight greater than 16 microns, less than 0.5% by 8 weight greater than 32 microns, the median particle size by g weight being 13.6 + 0.6 microns. In measuring size distri-10 bution a Coulter counter is utilized in a conventional 11 manner.
12 In order to compare toners, examples of various 13 toners were prepared with size distribution as shown in 14 Table I.
Table I
16 Example IExample IIExample III
17 Median Particle Size 13.5~ 11.0~ 8.5u by Weight Percent by Weight .8% 7.1~ 11.8%
19 Less Than 5~
20 Percent by Weight 30.0~ 15.0% 1.0%
Greater Than 16
Greater Than 16
21
22 Each of the toners was formulated of a mixed resin system which
23 is used for toner in the IBM Series III Copier. Example I
24 is representative of conventional prior art toner, and
25 Examples II and III are examples of toner according to this
26 invention.
27 About one part by weight of toner of each of the
28 examples was mixed with about 99 parts by weight of a con-
29 ventional carrier, formed of a coating of PTFE on steel BO977066 - ~ _ 1 shot, formed according to the teaching of U.S. Patent No.
2 3,947,271. Each mixture was placed in a conventional copy 3 machine, of a type commercially available, known as IBM
4 Series III Copier/Duplicator, and copies were made. Toner was added to each mixture to maintain an essentially con-6 stant toner concentration. The toner/carrier mix was run 7 10,000 copies to bring the toner particle size in the mix to 8 equilibrium. This equilibration of the toner particle size 9 results from the action of the toner, carrier, and photo-conductor during machine operations and actually alters the 11 particle size until it reaches essentially an "equilibrium"
12 point, at a relatively constant toner concentration, after 13 which the size distribution will remain essentially con-14 stant. This break-in or equilibration of the toner is desirable, since it provides more uniform copy quality than 16 a developer which has only the initially sized toner dis-17 tribution. Furthermore, the copy quality achieved with an 18 equilibrated bin mix is more representative of machine 19 performance than an unequilibrated mix. The equilibrated values for each example are shown in Table II below.
21 Table II
22 Example I Example II Example III
23 Median Particle Size 11.0~ 9.0~ 7.0 by Weight Percent by Weight 14.0% 17.0% 28.0%
Less Than 5~
26 Percent by Weight 24.0% 11.0% 1.0%
Greater Than 16~
27 Following the break-in period, additional copies 29 were run to test the copy quality. The following tests were 1 performed to determine the copy quality, and performance of 2 the toner.
3 Background Quality 4 The background quality of the copies was measured 5 with an S-4 Brightness Tester and Colorimeter manufactured 6 by Diano Corporation. This unit is used to measure the 7 reflectance of a surface. Results are reported as the 8 percent of change in reflectance of the paper before and 9 after making a copy. Generally a background measurement 10 resulting from a change in the reflectance of the paper of 11 more than about 1.5~ is objectionable, and is unacceptable 12 copy quality due to high background.
13 Recycle Rate 14 The copy machine is equipped with a filter to 15 clean the recycled toner. This is a physical cleaning 16 device, and the life of the device is inversely proportional 17 to the recycle rate. In other words, the lower the recycle 18 rate the better the toner performance. Recycled toner is 19 that which was deposited onto the photoconductor but not 20 transferred to the copy sheet.
21 Toner Yield 22 Toner yield is the number of copies made at a 23 given optical density per pound of toner used.
24 Optical Density Optical density is the measurement of the "solid~
26 ness" or "fill" of the image lines on the copy sheet after 27 fusing.
1~3Z8Z7 1 Fused Quality of Offset Master 2 Offset master papers are a difficult substrate on 3 which to fuse toner. The fuse quality test for offset 4 master papers consists of making copy on offset master paper 5 and then judging qualitatively the adhesion of the toner 6 image to the substrate.
7 Table III below summarizes the results of the 8 optical density, background quality, recycle rate, toner 9 yield, and fuse quality tests which were performed on copies 10 made while using toner described in the three above examples.
11 Table III
12 Example I Example II Example III
13 Optical Density 00.95 01.15 01.15 14 Background 01.20 00.90 00.90 15 Recycle Rate (mg/copy) 30.00 22.00 14.00 16 Toner Yield (copies/lb) 14.00 17.00 25.00 17 Fuse Quality of Unacceptable Acceptable Superior Offset Master 19 It can be seen from the table above that Example 20 III is by far the best toner, Example II is the next best and 21 Example I is the worst. It will be noted that even Example 22 II which is at the limits of the ranges of the invention is 23 a significant improvement over the prior art toner as exempli-24 fied in Example I. Indeed the background is significantly 25 less, there is substantially less toner recycled, a higher 26 yield of copies per pound of toner is obtained, and the 27 toner forms an acceptable offset master whereas the toner of 28 Example I does not. These benefits are even more improved 29 with the toner of Example III.
BO977066 - 9 _ :~328Z7 1 These results show that toner, as initially added 2 or utilized in a developer mix should have a size distribution 3 wherein less than 15~ by weight are greater than 16 microns 4 in size, between 7 and 15% are less than 5 microns in size, 5 the remainder being from 5 to 16 microns in size and wherein 6 the median size by weight is from 8 to 12 microns. More 7 preferably the size distribution should be less than 2% by 8 weight being greater than 16 microns, between 9 and 15% by g weight being less than 5 microns, the remainder being from 5 10 to 16 microns, with the median size by weight being from 8.5 11 to 9.5 microns. These size distributions relate to the size 12 distribution of fresh and unused toner. The equilibrated 13 size distribution after break-in should be as follows:
14 Median by weight 06.5 - 09.5 ~ by weight < 5~` 15.0 - 30.0 16 % by weight > 16~ 12.0 17 The reasons for such improvement are not all 18 completely understood, but it is believed that the following -19 factors contribute significantly.
Reflection is a measurement which indicates back-21 ground quality and the unaided eye can see particles on the 22 background. By reducing the number of particles greater 23 than 16~, the number of particles which are observable to 24 the unaided eye is reduced significantly, thus producing a 25 better background appearance.
26 The recycle rate is believed to be reduced in the 27 following manner: Since there are fewer large particles, 28 and the particles are more nearly equal in size, the particles 1 will receive more nearly equal electrostatic charges. Large 2 particles have lower charge-to-mass ratios and are less 3 responsive to force fields in development and transfer;
4 hence, they tend not to adhere as readily, and thus will 5 more readily be removed and recycled. Further, it is known 6 that large particles have a greater tendency to dust onto 7 the background area because of their low charge-to-mass 8 ratio. Therefore the lower the number of particles greater 9 than 16~ the lower the recycle rate will be.
With respect to more efficient toner utilization, 11 copy is made "black" by the application of a layer of toner 12 particles which is held by electrostatic attraction. The 13 depth of the layer plays no part in the "blackness" of the 14 copy as long as the area of the substrate covered is equiva-15 lent. Thus, one can use a layer of "thinner" particles, 16 rather than "thicker" particles, and therefore the weight 17 or volume of toner used to produce an image on the substrate 18 will be less per layer of particles. By reducing the number 19 of particles greater than 16 microns in size, the weight of 20 particles per layer will be reduced, and will thus result in 21 increasing the number of copies per pound of toner.
22 With respect to fuse quality of offset printing 23 masters, the quality of the printing is greatly improved 24 with toner of the presént invention. It is believed that 25 this is rélated to better heat transfer characteristics. It 26 is theorized that the thinner layers of the particles of the 27 present invention will provide a shorter heat path than the 28 thicker particles of the prior art. This will improve the 11328~7 1 ~use quality characteristics of the toner and wi11 result in 2 better adhesion of the toner to the substrate. This property 3 is also significant with other substrates, allowing more 4 rapid fusin~ than that which is achievable with thicker layers of toner particles.
6 It has been found that within the narrow limits, 7 outstanding copy quality is obtained, having marked improve-8 ment over conventional prior art toner and excellent toner 9 utilization is obtained. ~owever, as the broadest limits are approached, especially as the number of particles larger 11 than 16 microns in size approaches the upper limits, the 12 copy quality improvement over conventional particle size ~3 distributions becomes less significant. Even so, within the 14 broad limits, substantially improved toner is achieved.
Within the narrow limits, and especially with the number of 16 particles of less than 16 microns in size being less than 17 2%, outstanding copy quality is obtained.
1~ While the invention has been particularly shown 19 and described with reference to preferred enbodiments thereof, it will be understood by those skilled in the art that various 21 changes in form and details may be made therein without 22 departing from the spirit and scope of the invention.
2 3,947,271. Each mixture was placed in a conventional copy 3 machine, of a type commercially available, known as IBM
4 Series III Copier/Duplicator, and copies were made. Toner was added to each mixture to maintain an essentially con-6 stant toner concentration. The toner/carrier mix was run 7 10,000 copies to bring the toner particle size in the mix to 8 equilibrium. This equilibration of the toner particle size 9 results from the action of the toner, carrier, and photo-conductor during machine operations and actually alters the 11 particle size until it reaches essentially an "equilibrium"
12 point, at a relatively constant toner concentration, after 13 which the size distribution will remain essentially con-14 stant. This break-in or equilibration of the toner is desirable, since it provides more uniform copy quality than 16 a developer which has only the initially sized toner dis-17 tribution. Furthermore, the copy quality achieved with an 18 equilibrated bin mix is more representative of machine 19 performance than an unequilibrated mix. The equilibrated values for each example are shown in Table II below.
21 Table II
22 Example I Example II Example III
23 Median Particle Size 11.0~ 9.0~ 7.0 by Weight Percent by Weight 14.0% 17.0% 28.0%
Less Than 5~
26 Percent by Weight 24.0% 11.0% 1.0%
Greater Than 16~
27 Following the break-in period, additional copies 29 were run to test the copy quality. The following tests were 1 performed to determine the copy quality, and performance of 2 the toner.
3 Background Quality 4 The background quality of the copies was measured 5 with an S-4 Brightness Tester and Colorimeter manufactured 6 by Diano Corporation. This unit is used to measure the 7 reflectance of a surface. Results are reported as the 8 percent of change in reflectance of the paper before and 9 after making a copy. Generally a background measurement 10 resulting from a change in the reflectance of the paper of 11 more than about 1.5~ is objectionable, and is unacceptable 12 copy quality due to high background.
13 Recycle Rate 14 The copy machine is equipped with a filter to 15 clean the recycled toner. This is a physical cleaning 16 device, and the life of the device is inversely proportional 17 to the recycle rate. In other words, the lower the recycle 18 rate the better the toner performance. Recycled toner is 19 that which was deposited onto the photoconductor but not 20 transferred to the copy sheet.
21 Toner Yield 22 Toner yield is the number of copies made at a 23 given optical density per pound of toner used.
24 Optical Density Optical density is the measurement of the "solid~
26 ness" or "fill" of the image lines on the copy sheet after 27 fusing.
1~3Z8Z7 1 Fused Quality of Offset Master 2 Offset master papers are a difficult substrate on 3 which to fuse toner. The fuse quality test for offset 4 master papers consists of making copy on offset master paper 5 and then judging qualitatively the adhesion of the toner 6 image to the substrate.
7 Table III below summarizes the results of the 8 optical density, background quality, recycle rate, toner 9 yield, and fuse quality tests which were performed on copies 10 made while using toner described in the three above examples.
11 Table III
12 Example I Example II Example III
13 Optical Density 00.95 01.15 01.15 14 Background 01.20 00.90 00.90 15 Recycle Rate (mg/copy) 30.00 22.00 14.00 16 Toner Yield (copies/lb) 14.00 17.00 25.00 17 Fuse Quality of Unacceptable Acceptable Superior Offset Master 19 It can be seen from the table above that Example 20 III is by far the best toner, Example II is the next best and 21 Example I is the worst. It will be noted that even Example 22 II which is at the limits of the ranges of the invention is 23 a significant improvement over the prior art toner as exempli-24 fied in Example I. Indeed the background is significantly 25 less, there is substantially less toner recycled, a higher 26 yield of copies per pound of toner is obtained, and the 27 toner forms an acceptable offset master whereas the toner of 28 Example I does not. These benefits are even more improved 29 with the toner of Example III.
BO977066 - 9 _ :~328Z7 1 These results show that toner, as initially added 2 or utilized in a developer mix should have a size distribution 3 wherein less than 15~ by weight are greater than 16 microns 4 in size, between 7 and 15% are less than 5 microns in size, 5 the remainder being from 5 to 16 microns in size and wherein 6 the median size by weight is from 8 to 12 microns. More 7 preferably the size distribution should be less than 2% by 8 weight being greater than 16 microns, between 9 and 15% by g weight being less than 5 microns, the remainder being from 5 10 to 16 microns, with the median size by weight being from 8.5 11 to 9.5 microns. These size distributions relate to the size 12 distribution of fresh and unused toner. The equilibrated 13 size distribution after break-in should be as follows:
14 Median by weight 06.5 - 09.5 ~ by weight < 5~` 15.0 - 30.0 16 % by weight > 16~ 12.0 17 The reasons for such improvement are not all 18 completely understood, but it is believed that the following -19 factors contribute significantly.
Reflection is a measurement which indicates back-21 ground quality and the unaided eye can see particles on the 22 background. By reducing the number of particles greater 23 than 16~, the number of particles which are observable to 24 the unaided eye is reduced significantly, thus producing a 25 better background appearance.
26 The recycle rate is believed to be reduced in the 27 following manner: Since there are fewer large particles, 28 and the particles are more nearly equal in size, the particles 1 will receive more nearly equal electrostatic charges. Large 2 particles have lower charge-to-mass ratios and are less 3 responsive to force fields in development and transfer;
4 hence, they tend not to adhere as readily, and thus will 5 more readily be removed and recycled. Further, it is known 6 that large particles have a greater tendency to dust onto 7 the background area because of their low charge-to-mass 8 ratio. Therefore the lower the number of particles greater 9 than 16~ the lower the recycle rate will be.
With respect to more efficient toner utilization, 11 copy is made "black" by the application of a layer of toner 12 particles which is held by electrostatic attraction. The 13 depth of the layer plays no part in the "blackness" of the 14 copy as long as the area of the substrate covered is equiva-15 lent. Thus, one can use a layer of "thinner" particles, 16 rather than "thicker" particles, and therefore the weight 17 or volume of toner used to produce an image on the substrate 18 will be less per layer of particles. By reducing the number 19 of particles greater than 16 microns in size, the weight of 20 particles per layer will be reduced, and will thus result in 21 increasing the number of copies per pound of toner.
22 With respect to fuse quality of offset printing 23 masters, the quality of the printing is greatly improved 24 with toner of the presént invention. It is believed that 25 this is rélated to better heat transfer characteristics. It 26 is theorized that the thinner layers of the particles of the 27 present invention will provide a shorter heat path than the 28 thicker particles of the prior art. This will improve the 11328~7 1 ~use quality characteristics of the toner and wi11 result in 2 better adhesion of the toner to the substrate. This property 3 is also significant with other substrates, allowing more 4 rapid fusin~ than that which is achievable with thicker layers of toner particles.
6 It has been found that within the narrow limits, 7 outstanding copy quality is obtained, having marked improve-8 ment over conventional prior art toner and excellent toner 9 utilization is obtained. ~owever, as the broadest limits are approached, especially as the number of particles larger 11 than 16 microns in size approaches the upper limits, the 12 copy quality improvement over conventional particle size ~3 distributions becomes less significant. Even so, within the 14 broad limits, substantially improved toner is achieved.
Within the narrow limits, and especially with the number of 16 particles of less than 16 microns in size being less than 17 2%, outstanding copy quality is obtained.
1~ While the invention has been particularly shown 19 and described with reference to preferred enbodiments thereof, it will be understood by those skilled in the art that various 21 changes in form and details may be made therein without 22 departing from the spirit and scope of the invention.
Claims (11)
1. An electrostatographic toner material com-prising particles having the following size distributions:
less than 15% by weight being greater than 16 microns in size, from 7 to 15% by weight being less than 5 microns in size, the remainder being from 5 to 16 microns in size, the particle median size by weight being from 8 to 12 microns.
less than 15% by weight being greater than 16 microns in size, from 7 to 15% by weight being less than 5 microns in size, the remainder being from 5 to 16 microns in size, the particle median size by weight being from 8 to 12 microns.
2. An electrostatographic toner material according to claim 1 wherein less than 2% by weight are greater than 16 microns in size, from 9 to 15% by weight are less than 5 microns in size, the median particle size by weight being from 8.5 to 9.5 microns.
3. An electrostatographic toner according to claim 1 wherein the median particle size by weight is between 8.5 and 9.5 microns.
4. An electrostatographic toner according to claim 1 wherein there is less than 2% by weight of particles greater than 16 microns.
5. An electrostatographic toner according to claim 1 wherein from 9 to 15% by weight are less than 5 microns.
6. A developer mix for electostatographic copying comprising toner particles and carrier particles of opposite triboelectric charges, said toner particles having the following size distribution:
less than 15% by weight being greater than 16 microns in size, from 7 to 15% by weight being less than 5 microns, the remainder being from 5 to 16 microns, the median particle size by weight being from 8 to 12 microns.
less than 15% by weight being greater than 16 microns in size, from 7 to 15% by weight being less than 5 microns, the remainder being from 5 to 16 microns, the median particle size by weight being from 8 to 12 microns.
7. A developer mix according to claim 6 wherein the toner particle size distribution is less than 2% by weight greater than 16 microns, from 9 to 15% by weight less than 5 microns, the median particle size by weight being from 8.5 to 9.5 microns.
8. A developer mix according to claim 6 wherein the median toner particle size by weight is between 8.5 to 9.5 microns.
9. A developer mix according to claim 6 wherein there is less than 2% by weight of toner particles greater than 16 microns.
10. A developer mix according to claim 6 wherein there is from 9 to 15% by weight of toner particles less than 5 microns.
11. In an electrostatic developing process, wherein a mix of toner and carrier particles are provided and applied to a photoconductor to develop a latent electro-static image thereon, and wherein the developed image is transferred to a copy sheet, the improvement which comprises, maintaining a developer mix having toner particles therein equilibrated to the following size distribution;
less than 12% by weight greater than 16 microns, from 15 to 30% by weight less than 5 microns, the remainder from 5 to 16 microns, the median toner particle size by weight being between 6.5 and 9.5 microns.
less than 12% by weight greater than 16 microns, from 15 to 30% by weight less than 5 microns, the remainder from 5 to 16 microns, the median toner particle size by weight being between 6.5 and 9.5 microns.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US84817377A | 1977-11-03 | 1977-11-03 | |
| US848,173 | 1977-11-03 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1132827A true CA1132827A (en) | 1982-10-05 |
Family
ID=25302556
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA307,348A Expired CA1132827A (en) | 1977-11-03 | 1978-07-13 | Electrophotographic toner comprising particles of a specific size distribution |
Country Status (7)
| Country | Link |
|---|---|
| EP (1) | EP0001785B1 (en) |
| JP (1) | JPS598822B2 (en) |
| AR (1) | AR223330A1 (en) |
| BR (1) | BR7807248A (en) |
| CA (1) | CA1132827A (en) |
| DE (1) | DE2861483D1 (en) |
| IT (1) | IT1160021B (en) |
Families Citing this family (25)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CA1147192A (en) * | 1978-04-06 | 1983-05-31 | John L. Webb | Electrostatographic developer including toner of diameter between 3 and 15 microns and carrier of diameter between 15 and 65 microns |
| DE2965939D1 (en) * | 1978-10-02 | 1983-08-25 | Xerox Corp | Electrostatographic processing system |
| JPS5792341A (en) * | 1980-11-29 | 1982-06-08 | Toshiba Corp | Fur brush developing method |
| JPS62174931U (en) * | 1986-04-26 | 1987-11-06 | ||
| JPH0743349B2 (en) * | 1986-06-02 | 1995-05-15 | 富士写真フイルム株式会社 | Gel sheet for electrophoresis |
| JPS62284364A (en) * | 1986-06-03 | 1987-12-10 | Fuji Xerox Co Ltd | Image forming method |
| JP2791013B2 (en) * | 1986-10-17 | 1998-08-27 | キヤノン株式会社 | Method and apparatus for producing triboelectric toner for developing electrostatic images |
| JPH0760273B2 (en) * | 1987-10-26 | 1995-06-28 | キヤノン株式会社 | Magnetic developer |
| JP2763318B2 (en) * | 1988-02-24 | 1998-06-11 | キヤノン株式会社 | Non-magnetic toner and image forming method |
| JP2603287B2 (en) * | 1988-02-29 | 1997-04-23 | キヤノン株式会社 | Frictional magnetic toner |
| JP2866088B2 (en) * | 1988-02-29 | 1999-03-08 | キヤノン株式会社 | Developer for developing electrostatic images |
| JPH0810342B2 (en) * | 1988-02-29 | 1996-01-31 | キヤノン株式会社 | Image forming method and image forming apparatus |
| JP2692935B2 (en) * | 1988-02-29 | 1997-12-17 | キヤノン株式会社 | Image forming method and image forming apparatus |
| JP2769814B2 (en) * | 1988-02-29 | 1998-06-25 | キヤノン株式会社 | Magnetic toner for developing electrostatic images |
| US4904558A (en) | 1988-03-08 | 1990-02-27 | Canon Kabushiki Kaisha | Magnetic, two-component developer containing fluidity improver and image forming method |
| JP2598128B2 (en) * | 1989-04-28 | 1997-04-09 | キヤノン株式会社 | Image forming device |
| US5424810A (en) * | 1991-09-13 | 1995-06-13 | Canon Kabushiki Kaisha | Magnetic toner, magnetic developer, apparatus unit, image forming apparatus and facsimile apparatus |
| US5637432A (en) * | 1992-06-01 | 1997-06-10 | Canon Kabushiki Kaisha | Toner for developing electrostatic image comprising titanium oxide particles |
| DE69313518T2 (en) * | 1992-06-08 | 1998-02-19 | Canon Kk | Imaging processes |
| US5512402A (en) * | 1993-05-20 | 1996-04-30 | Canon Kabushiki Kaisha | Carrier for electrophotography, two-component type developer, and image forming method |
| JP2992924B2 (en) * | 1993-06-28 | 1999-12-20 | キヤノン株式会社 | Color toner and method of manufacturing the same |
| DE69519055T2 (en) | 1994-06-22 | 2001-05-31 | Canon K.K., Tokio/Tokyo | Carriers for electrophotography, two-component developers and methods for image production |
| CA2151988C (en) | 1994-06-22 | 2001-12-18 | Kenji Okado | Carrier for electrophotography, two component-type developer and image forming method |
| EP1158366B1 (en) | 2000-05-23 | 2006-06-14 | Ricoh Company, Ltd. | Two-component developer, container filled with the two-component developer, and image formation apparatus |
| JP2006126724A (en) | 2004-11-01 | 2006-05-18 | Sharp Corp | Toner for electrostatic image development, and image forming apparatus and method using toner |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CA944106A (en) * | 1970-01-12 | 1974-03-26 | Reprographic Materials | Agglomeration of pigment particles and compositions utilizing same |
| GB1497731A (en) * | 1974-05-30 | 1978-01-12 | Xerox Corp | Classified toner particles for electrostatographic developers |
-
1978
- 1978-07-13 CA CA307,348A patent/CA1132827A/en not_active Expired
- 1978-10-19 DE DE7878101178T patent/DE2861483D1/en not_active Expired
- 1978-10-19 EP EP78101178A patent/EP0001785B1/en not_active Expired
- 1978-10-25 AR AR274216A patent/AR223330A1/en active
- 1978-10-30 JP JP53132741A patent/JPS598822B2/en not_active Expired
- 1978-10-31 IT IT29273/78A patent/IT1160021B/en active
- 1978-11-01 BR BR7807248A patent/BR7807248A/en unknown
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5472054A (en) | 1979-06-09 |
| EP0001785B1 (en) | 1981-12-30 |
| AR223330A1 (en) | 1981-08-14 |
| JPS598822B2 (en) | 1984-02-27 |
| DE2861483D1 (en) | 1982-02-18 |
| IT7829273A0 (en) | 1978-10-31 |
| BR7807248A (en) | 1979-05-15 |
| EP0001785A1 (en) | 1979-05-16 |
| IT1160021B (en) | 1987-03-04 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |