JPH01129262A - Toner for electrophotographic development - Google Patents

Abstract

PURPOSE:To obtain a toner having satisfactory fixability at low temp. and offsetting resistance and suitable for high-speed fixing by using polyester resin having a specified wt. average mol.wt., a specified ratio of the wt. average mol.wt. to the number average mol.wt. and a specified glass transition point as a binding resin. CONSTITUTION:When a colorant is dispersed in a binding resin to obtain a toner, polyester resin having 30,000-200,000wt. average mol.wt., >=10 ratio of the wt. average mol.wt. (Mw) to the number average mol.wt. (Mn) and 60-70 deg.C glass transition point is used as the binding resin. By the regulated mol.wt. distribution and glass transition point, the polyester resin satisfies required fixability at low temp., offsetting resistance, heat resistance and shelf stability and a toner for electrophotographic development suitable for high-speed fixing can be obtd.

Description

[Detailed Description of the Invention] [Technical Field] The present invention applies to electrophotography, electrostatic printing, etc.
The present invention relates to toners used to develop latent electrical or magnetic images. More specifically, in the heat roll fixing method, it fixes well at a lower temperature, has good offset properties,
The present invention also relates to a heat-fixable dry toner with excellent fixing properties that does not cause caking or blocking in a developing device or during storage.

[Prior Art] Conventionally, as an electrophotographic method, U.S. Patent No. 2,297°69
A number of methods are known, as described in Japanese Patent Publication No. 1, Japanese Patent Publication No. 42-23,910, and Japanese Patent Publication No. 43-24,748. forming an electrical latent image on a photoreceptor by various means;
Next, the latent image is developed using toner, and if necessary, the toner image is transferred to a transfer material such as paper, and then fixed by heating or pressure to obtain a copy.

Furthermore, various developing methods are known in which an electrical latent image is visualized using toner.

For example, the magnetic brush method described in U.S. Pat. No. 2,874,063, the cascade development method described in U.S. Pat. No. 2,618,552, and U.S. Pat.
A large number of development methods are known, such as the powder method described in No. 776, the fur brush development method, and the liquid development method.

Toners used in these developing methods have conventionally been fine powders in which dyes and pigments are dispersed in natural or synthetic resins. Furthermore, it is also known to use fine developing powder to which a third substance is added for various purposes.

The developed toner image is transferred and fixed onto a transfer material such as paper, if necessary.

Methods for fixing toner images include heating and melting the toner with a heater or heated roller to fuse and assimilate it to the support, softening or dissolving the binder resin of the toner with an organic solvent and fixing it to the support, and applying pressure. A method of fixing toner on a support by using a method is known.

Toner materials are selected to suit each fixing method,
Toners used in a particular fusing method generally cannot be used in other fusing methods.

In particular, the toner used in the conventionally widely used heat fusion fixing method using a heater is used in the heat roller fixing method.

It is almost impossible to apply it to solvent fixing methods, pressure fixing methods, etc. Therefore, toners suitable for each fixing method are being researched and developed.

Various magnetic recording methods are also known in which a magnetic latent image is formed and developed with magnetic toner.

Regarding the process of fixing toner images on paper etc.

Various methods and devices have been developed, but the most common method at present is the so-called heated roll fixing method, which applies heat and pressure simultaneously. This is a method of fixing a toner image on an image-receiving sheet by bringing it into contact with a roller. However, when such a fixing method is used, problems such as so-called offset occur with conventional toner. Offset is an undesirable phenomenon in which a portion of the toner carried on the image receiving sheet is transferred to the roller surface.

As described in Japanese Patent Publication No. 51-23,354, such an offset phenomenon, particularly pot offset, is likely to occur when a low molecular weight resin is used. Therefore, as described in the same publication, it is thought that the offset phenomenon can be prevented to some extent by using a cross-linked resin, but of course, simply using a cross-linked resin will not raise the fixing temperature. Under normal fixing conditions, unfixed areas will occur, causing the problem of low-temperature offset in the unfixed areas.

The roller that comes into contact with the toner image usually has at least a surface layer formed of silicone rubber or fluororesin, which has good releasability, but in order to prevent offset and prevent fatigue on the roller surface, There is also a method of applying mold release oil such as silicone oil. However, the method of applying oil has problems such as the provision of an oil application system, which results in a plurality of fixing devices, and the evaporation of the oil, which causes discomfort to the user. Therefore, it is not preferable to try to prevent offset by coating with oil; rather, the current situation is that it is desired to develop a toner with good offset resistance over a wide fixing temperature range. Of course, in addition to fixing properties, toners also need to be excellent in blocking resistance, developing properties, transferability, cleaning properties, etc., but conventional toners have the following defects: had one or more. That is, many toners that are easily melted by heating tend to cake or aggregate during storage or in a copying machine. Many toners have poor triboelectric properties and flow properties due to environmental humidity changes. In addition, with many toners, the image density obtained changes due to mutual deterioration of the toner, carrier particles, and photosensitive plate due to collisions between toner particles and carrier particles due to repeated development due to continuous use and contact between them and the photosensitive plate surface. Alternatively, the background density increases, reducing the quality of the copy. Therefore, there is a need for a toner that has excellent toner properties and is suitable for the hot roller constant deposition method.

More recently, high-speed fixing has been sought to improve the efficiency of copying operations. In order to increase the fixing speed in conventional heat fixing methods, attempts have been made to lower the softening point of the toner binder resin to facilitate heat fixing. Trouble arises in that the particles agglomerate and cause blocking.

As described above, there is a strong demand for a toner that is suitable for constant fixation on a hot roller at higher speeds, has no roller offset, and has excellent toner properties such as aggregation and blocking.

In order to solve the above problems, Japanese Patent Application Laid-Open No. 61-153
No. 663 proposes a toner containing a crosslinked polyester resin having a specific melting point.

Sufficient low-temperature fixing, offset resistance, and heat-resistant storage stability have not been achieved.

Further, JP-A-61-176948 proposes a polyester resin having a specific molecular weight distribution, but its softening point is 90 DEG C. or higher, and sufficient low-temperature fixability is still not obtained.

[Objective] The present invention overcomes the conventional drawbacks, has a low minimum fixing temperature,
For electrophotographic development that has sufficient offset resistance, can consistently form good visible images over a long period of time, does not cause aggregation, has good heat-resistant storage stability, and is suitable for high-speed fixing. The purpose is to provide toner.

[Structure] As a result of intensive research to achieve the above object, the inventors of the present invention have developed a toner for electrophotographic development in which a colorant is dispersed in a binder resin, in which the binder resin has a weight average molecular weight of 30. ,000-200°000, weight average molecular weight (
The above object is achieved by providing a toner for electrophotographic development characterized by using a polyester resin having a value of Mw)/number average molecular weight (Mn) of 10 or more and a glass transition point of 60 to 70°C. I found out what I can achieve.

The weight average molecular weight (My) and glass transition point (Tg) of the binder resin in the present invention can be obtained by the following measuring method.

Resin My is Waters liquid chromatograph M-6
000A and SIC Intelligence Inch Grater 7000AS, detector RI column 5hodex
It was measured by gel permeation chromatography (GPC) using KF-80M (Showa Denko).

The measurement conditions were a temperature of 25°C, a solvent (tetrahydrofuran) flowing at a flow rate of 1 mQ/min, and a tetrahydrofuran sample solution with a concentration of 0.1 wt% as a sample weight of 40 μQ.
Inject and measure.

When measuring the molecular weight of a sample, the measurement conditions are such that the molecular weight distribution of the sample falls within a range where the logarithm of the molecular weight and the count number of a calibration curve prepared using several types of monodisperse polystyrene standard samples are linear. select. In addition, the reliability of single measurement is NB570 under the above measurement conditions.
6 polystyrene standard sample (Mw=28.8X10', M
n=13.7X104, Mu/Mn=2.11)
Confirm that w/an is 2.11±0.10.

The Tg of the resin is determined using the general differential thermal analysis (DSC) method.
The peak top value was used.

The present invention aims to obtain a resin that satisfies low-temperature fixing properties, anti-offset properties, and heat-resistant storage stability by specifying the polyester resin used in the toner based on its molecular weight distribution and glass transition point. Average molecular weight is 3
If it is less than 0.000, low-temperature fixability is good, but offset resistance and heat-resistant storage stability are insufficient.

If it is more than zoo, ooo, the anti-offset property is good, but the low-temperature fixability is poor, the kneading during production is rough, and the grindability is poor, resulting in poor productivity.

Moreover, when Mw/Mn is smaller than 10, offset resistance becomes poor.

Furthermore, if the Tg is lower than 60°C, low-temperature fixing properties are good, but heat-resistant storage stability and offset resistance are poor, and the toner tends to adhere to the carrier, resulting in insufficient developer durability. . On the other hand, if the temperature is higher than 70°C, low-temperature fixing properties are not good.

From the above, the polyester resin in the present invention is 30.000≦Mw≦200,000 M%l/Mn≧10 60(”C)≦Tg≦70(’C) It is an essential requirement.

The polyester resin used as a binder in the present invention is obtained by polycondensation of alcohol and carboxylic acid, and the alcohols used include polyethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,3- Diols such as propylene glycol, 1,4-butanediol, neopentyl glycol, 1,4-butynediol,
Etherified bisphenols such as 1,4-bis(hydroxymethyl)cyclohexane, bisphenol A, hydrogenated bisphenol A, polyoxyethylated bisphenol A, and polyoxypropylenated bisphenol A; Examples include divalent alcohol units substituted with saturated hydrocarbon groups and other divalent alcohol units.

Examples of carboxylic acids used to obtain polyester resins include maleic acid, fumaric acid, mesaconic acid, citraconic acid, itaconic acid, glutaconic acid, phthalic acid, isophthalic acid, terephthalic acid, cyclohexanedicarboxylic acid, succinic acid, and adipine. acids, cepatic acid, malonic acid.

Divalent organic acid monomers substituted with saturated or unsaturated hydrocarbon groups having 3 to 22 carbon atoms, anhydrides of these acids, lower alkyl esters, dimers of phosphoric acid, and other divalent Organic acid monomers can be mentioned.

In order to obtain a polyester resin used as a binder resin, it is preferable to use not only a polymer containing only the above-mentioned difunctional monomer, but also a polymer containing a component containing a trifunctional or higher polyfunctional monomer. It is. Trivalent or higher polyhydric alcohols (as b-mers) are such polyfunctional monomers.

For example, sorbitol, 1,2,3,6-hexanetetrol, 1,4-salbitane, pentanetriol, dipentaerythritol, tripentaerythritol, sucrose, 1,2,4-butanetriol, 1,2,5-pentane triol, glycerol, 2-methylpropanetriol.

2-methyl-1,2,4-butanetriol, trimethylolethane, trimethylolpropane.

1.3.5-trihydroxymethylbenzene, and others.

Examples of trivalent or higher polycarboxylic acid monomers include 1,2,4-benzenetricarboxylic acid, 1,2,5-benzenetricarboxylic acid, 1,2,4-cyclohexanetricarboxylic acid, 2,5. 7-naphthalene tricarboxylic acid, 1,2,4-naphthalene tricarboxylic acid, 1,2,4
-butanetricarboxylic acid, 1,2.5-hexanetricarboxylic acid, 1,3-dicarboxyl-2-methyl-2-
Examples include methylenecarboxypropane, tetra(methylenecarboxyl)methane, 1,2,7.8-octanetetracarboxylic acid, embol trimer acid, acid anhydrides thereof, and others.

Among the polyesters used in the present invention, those that are particularly useful as a binder resin component are: (A) When the acid component is 100 moQ% as a whole.

(i) 50-85 moQ% aromatic dicarboxylic acid (■)
5-20 moQ% of dicarboxylic acid (m) without phenyl nucleus; 5-20 moQ% of monocarboxylic acid (K) 5-2
Consists of 0moQ% tricarboxylic acid.

(B) When the alcohol component as a whole is 100 moQ%, (i) 80 to 100 moQ% of etherified diphenols (ii) O to 20 moQ% of diol having no phenyl nucleus.

Examples of aromatic dicarboxylic acids include phthalic acid, terephthalic acid, and isophthalic acid. Examples of dicarboxylic acids that do not have a phenyl nucleus include n-dodecenylsuccinic acid, isododecenylsuccinic acid, n-dodecylsuccinic acid, isododecylsuccinic acid, In addition to alkyl or alkenyl succinic acids such as n-octylsuccinic acid, n-octenylsuccinic acid, and n-butylsuccinic acid, fumaric acid, maleic acid, succinic acid, adipic acid, speric acid, azelaic acid, sebacic acid, etc. Can be mentioned.

In addition, monocarboxylic acids include various fatty acids, such as palmitic acid, stearic acid, and oleic acid.
The three-dimensional structure of polyester is adjusted to control low-temperature fixing properties, offset resistance, etc. As a tricarboxylic acid.

Contains trimellitic acid, rosin maleic acid, pyromellitic acid, and their anhydrides to control offset resistance.

Examples of the etherified diphenol include polyoxypropylene (2,2)-2,2-bis(4-hydroxyphenyl)propane and polyoxypropylene (3,3)-
2,2-bis(4-hydroxyphenyl)propane, polyoxyethylene(2,0)-2,2-bis(4-hydroxyphenyl)propane, polyoxypropylene(2
,0)-polyoxyethylene(2,0)-2,2-bis(4-hydroxyphenyl)propane, polyoxypropylene(6)-2,2-bis(4-hydroxyphenyl)propane, etc. can.

Examples of diols without a phenyl nucleus include ethylene glycol, diethylene glycol, propylene glycol, triethylene glycol, tetramethylene glycol, pentamethylene glycol, hexamethylene glycol, heptamethylene glycol, octamethylene glycol, nonamethylene glycol, decamethylene glycol, neo Examples include pentyl glycol.

The polyester used in the present invention desirably has a softening point of 60 to 80°C. If the softening point is higher than 80°C, low-temperature fixing properties will be impaired, and if it is lower than 60°C, offset resistance will be poor.

Moreover, the number average molecular weight is preferably 2000 to 10,000. If it is larger than to or ooo, the low temperature fixing property will be insufficient, and if it is less than 2000, the cohesive force of the toner will be small and the offset resistance will be poor.

In addition, when preparing toner for electrophotographic development, it goes without saying that colorant pigments conventionally used in toners are added to the above-mentioned resin components, and specifically, carbon black, nigrosine dye, lamp Black, Sudan Black SM, First Yellow G, Benzidine Niro, Pigment Niro, India First Orange, Irgazine Red, Valanitroaniline Red, Toluidine Red, Carmine FB, Permanent Holt.
FRR, Pigment Orange R, Resole Red 2
G, Rake Red C, Rhodamine FB, Rhodamine B
Lake, Methyl, Violet B Lake, Phthalocyanine Blue, Pigment Blue, Brilliant Green B, Phthalocyanine Green, Oil Yellow GG, Zapon, First Yellow CGC, Kayaset Y963
, Kayaset YG, Sumi Blast Niro G, Zabon First Orange RR, Oil Scarlet, Sumi Blast Orange G, Orazole Brown B, Pomelo First Scarlet CG, Eisenspiron Red BEH, Oil Pink OP, etc. .

Further, in order to use the toner of the present invention as a magnetic toner, it may contain magnetic powder. As such magnetic powder, materials that are magnetized when placed in a magnetic field are used, such as iron,
These include powders of ferromagnetic metals such as cobalt and nickel, and alloys and compounds such as magnetite, hematite, and ferrite. The content of this magnetic powder is 1 for toner density.
It is 5 to 70% by weight.

Furthermore, polyolefins such as low molecular weight polyethylene and low molecular weight polypropylene, and various natural waxes may be added to the 1-ner in order to improve the releasability from the heat fixing roll.

Further, fine powders such as silica, alumina, titanium oxide, etc. can be added to the toner of the present invention to improve fluidity.

The toner of the present invention is mixed with a carrier made of iron powder, glass beads, etc. to form a two-component developer, but when a magnetic material is incorporated, the toner can be directly used as a one-component developer to develop an electrostatic image. Ru.

Next, some production examples of polyester resins will be shown. These synthetic examples can be carried out by known means.

Production example 1 Terephthalic acid 7 mol succinic acid
1 mole trimellitic acid
1 mole oleic acid
1 mol A mixture of these was heated and stirred at 210°C for about 6 hours, and after the reaction was completed, it was cooled to room temperature and polyester A (Mw
=153,000, My/Mn = 38, Tg =
65°C) was obtained.

Production example 2 Terephthalic acid 6 moles adipic acid 1 mole trimellitic acid
1 mole oleic acid
2 mol ethylene glycol 1 mol The mixture was heated and stirred at 200°C for about 7 hours, and after the reaction was completed, it was cooled to room temperature and polyester B (Mw=55,0
00. Mw/Mn=20, Tg=64°C).

Production example 3 Isophthalic acid 7 mol n-dodecenylsuccinic acid 1 mol trimellitic acid
1.5 mol oleic acid
0.5 mol The mixture was heated and stirred at 220°C for about 6 hours, and after the reaction was completed, it was cooled to room temperature, and polyester C (Mw = 132,000. M%l/Mn = 45,
Tg = 68°C) was obtained.

Production example 4 Terephthalic acid 8 mol maleic acid 1 mol stearic acid
0.5 mole trimellitic acid
0.5 mol The mixture was heated and stirred at 210° C. for about 7 hours, and after the reaction was completed, it was cooled to room temperature to obtain polyester D (lh=185,000. Mw/Mn=29.T
g=63°C) was obtained.

Example 1 Polyester Al: 00 parts Chromium-containing monoazo dye: 0.5 parts Carbon black: 10 parts The mixture having the above composition was thoroughly mixed in a Henschel mixer, and then heated and melted in a two-roll mill at a temperature of 70 to 90°C for about 40 minutes. ,
Cooled to room temperature. The obtained kneaded material is pulverized and classified into 5
A toner with a particle size of ~25 μm was obtained. 0.1 part of colloidal silica (Nippon Aerosil R-972) was added to this toner to prepare a developing toner.

Evaluation of fixing properties, offset resistance, and heat resistant storage stability was performed as follows.

Fixing properties (as minimum fixing temperature (°C)): Fixing roller: Teflon-coated roller, nip width: 4 mm.

When the toner is fixed on the copy paper by changing the temperature of the fixing roller under the fixing condition of linear speed 250 mm/see,
Check the temperature at which the fixation rate reaches 70% using a crockmeter.

To measure the temperature at which offset occurs, a toner image is transferred and fixed by the above-mentioned fixing device, and then a blank transfer sheet is sent to the fixing device under the same conditions to determine whether or not toner stains are deposited on it. The observation operation was repeated while the set temperature of the heat roller of the fixing device was successively increased, and the offset occurrence temperature was determined.

Heat resistant storage life (m); Toner 10 in a glass bottle with an inner diameter of 25 m and a height of 70 + nm
g and left in a constant temperature bath at 50℃ for 24 hours, then
Check the penetration level using a 2530 penetrometer.

The above results are shown in Table-1.

In addition, for 3 parts of this toner, 100 to 250 meshes of ferrite carrier 97 coated with silicone resin were added.
A developing agent was prepared by mixing the two parts.

Next is a copying machine rFT-7030J C equipped with a fixing device whose fixing roller is made of Teflon and whose pressure roller is made of silicone rubber.
At @Glico), the above developer was loaded into the copying machine from which the oil application device had been removed, and the fixing roller temperature was set at 155°C.
A 100,000 copy test was conducted.

As a result, offset development did not occur and a good image was obtained until the end.

Example 2 Polyester 8 100 parts Bontron E-84' 2 parts Rice wax 3 parts C.1, Pigment Red 81 5 parts C.1, Pigment Red 48 3 parts A mixture of the above composition was melted and mixed in the same manner as in Example 1. , crushed, classified, 5~20μ
A red toner of m was obtained.

As in Example 1, 3 parts of this toner was mixed with 97 parts of iron oxide powder carrier TEFV (150 to 250 mesh, manufactured by Nippon Steel Powder) to prepare a developer.

When a 50,000 copy test was conducted using this developer in the same manner as in Example 1, no offset development occurred and good images were obtained to the end.

Furthermore, the fixing quality such as offset property was good as shown in Table 1.

Example 3 100 parts of polyester C 42 parts of Bontron E-84 4 parts of polypropylene 5 parts of C.1, Pigment Blue 15
A blue toner of m was obtained.

As in Example 1, 3 parts of this toner was mixed with 97 parts of a 100-250 mesh ferrite carrier coated with a silicone resin to prepare a developer.

When a 50,000 copy test was carried out using this developer in the same manner as in Example 1, no offset occurred and good images were obtained to the end.

Furthermore, the fixing quality such as offset resistance was good as shown in Table 1.

Example 4 100 parts of polyester D 1 part of chromium-containing monoazo dye 12 parts of carbon black A mixture having the above composition was melt mixed in the same manner as in Example 1, and then pulverized and classified to obtain a black toner of 5 to 25 μm.

As in Example 1, 97 parts of a 100-250 mesh ferrite carrier coated with a silicone resin was mixed with 3 parts of this toner to form a developer.

When a 100,000 copy test was conducted using this developer in the same manner as in Example 1, no offset occurred and good images were obtained to the end.

Furthermore, the fixing quality such as offset quality was good as shown in Table 1.

Comparative Example 1 Polyester E (Mw=35,000. Mw/Mn
= 8.5, Tg = 59°C) of polyester A of Example 1.
The same procedure as in Example 1 was carried out except that .

Regarding the fixing quality, as shown in Table 1, the low-temperature fixability was good, but the offset resistance and heat-resistant storage stability were insufficient. In addition, offset occurred in the same actual machine test as in Example 1, resulting in poor images.

Comparative Example 2 Polyester F (
Mw=286,000. Mw/Mn=48, Tg=
The same procedure as in Example 1 was conducted except that the temperature was 72°C.

As for each quality, as shown in Table 1, offset resistance and heat-resistant storage stability were good, but low-temperature fixability was poor. Further, in a test on an actual machine similar to that in the example, fixing failure occurred and the result was a failure.

Table 1 [Effects] As described above, a toner using a specific polyester resin as defined in the present invention as a binder resin has the following effects.

(1) Good low temperature fixability.

(2) Good offset resistance.

(3) Suitable for high-speed fixing.

Patent applicant Rico Co., Ltd.

Claims (1)

[Claims] 1. In a toner for electrophotographic development in which a colorant is dispersed in a binder resin, the binder resin has a weight average molecular weight of 30,000 to 200,000, a weight average molecular weight /
Number average molecular weight value is 10 or more, glass transition point is 60-7
A toner for electrophotographic development characterized by using a polyester resin having a temperature of 0°C.