JPS5929258A - Thermofixable dry type toner - Google Patents

Abstract

PURPOSE:To obtain the titled toner superior in offset resistance and having a wide fixable temp. range, by incorporating a >=2 valent metallic org. compd. and a specified nonlinear low m.p. polyester. CONSTITUTION:A binder resin (A) made of nonlinear low m.p. polyester having 50-80 deg.C glass transition point, 60-130 deg.C softening point, and 10-60 acid value is obtained by reacting acid components consisting of (a) 10-25wt% succinic acid (anhydride) substd. by 6-18C alkyl, (b) 10-30wt. >=3-valent polycarboxylic acid, such as trimellitic acid, and/or >=3-valent polyol, such as sorbitol, and (c) >=50mol% aromatic carboxylic acid, such as terephthalic acid, with (d) etherified diphenols. Then, the component (A) and 0.2-4wt% >=2-valent metallic org. comd., such as calcium acetate, and when needed, together with colorant, fine magnetic particles, etc., and finely pulverized.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is applicable to electrophotography, electrostatic printing, etc.
This invention relates to a toner for developing a latent image or a magnetic latent image. More specifically, the present invention relates to a heat-fixable dry toner that has excellent low-temperature fixability and offset resistance in a heat roller fixing system.

Conventionally, as an electrophotographic method, U.S. Patent No. 2,297,6
Although many methods are known, such as those disclosed in Japanese Patent Publication No. 91, Japanese Patent Publication No. 42-23910, and Japanese Patent Publication No. 43-24728, they generally utilize a photoconductive substance and apply electrical current to a photoreceptor by various means. A static acid latent image is formed by forming an image, and then a static acid latent image is developed by adhering toner on the latent image, and if necessary, after transferring the toner image to a transfer material such as paper, heating, pressurization, solvent vapor, etc. The object is obtained by fixing the image.

The toner used in development is generally a thermoplastic resin mixed with a colorant and pulverized to a finely dispersed diameter. As thermoplastic resins, polystyrene resins,
Polyester resins, epoxy resins, acrylic resins, urethane resins, and copolymer resins thereof are widely used.

Carbon black is most widely used as a colorant, and iron oxide-based black magnetic powder is often used as a part of the magnetic toner.

Various methods and devices have been developed for fixing toner on paper, etc., but methods using heat are often used, and an oven fixing method is one example. However, in recent years, there has been a demand for more efficient and energy-saving copying work, and as copying machines have become smaller and faster, the hot roller constant fixing method, which is a pressure-contact heating method that is advantageous in terms of thermal efficiency, has come to dominate the market. In this method, the toner image on the paper is brought into direct pressure contact with the heat roller, and is extremely advantageous in terms of thermal efficiency, and is most suitable for increasing speed in terms of the fixability of the toner on the paper. However, on the other hand, this method has a serious problem: if the heat roller is kept at a temperature where the toner is fixed, the toner will adhere not only to the paper but also to the surface of the heat roller, and as copying is repeated, the toner will adhere to the surface of the heat roller. This eliminates the so-called offset phenomenon that contaminates the non-image areas of images.

Various measures have been investigated for fixing devices and toner to solve or alleviate such problems, but no satisfactory solution has been achieved.

As a fixing device, the surface of the heated roller is coated with a material such as deflon or silicone, which has good mold releasability. However, there are problems in terms of cost and practicality, such as the complexity of the fixing device due to the provision of the oil coating system.

Furthermore, in order to improve the releasability of the toner, a method of adding a wax such as low molecular weight polyethylene or polypropylene is also used. However, in order to prevent optical offset, it is necessary to add a considerable amount, which results in adverse effects such as increased cohesiveness of the toner, decreased durability due to worsened fluidity, and destabilized charging characteristics. Another method is to improve the binder resin, for example,
Japanese Patent Application No. 23354 proposes a toner using a crosslinked polymer as a binder resin. If this method is followed, the offset resistance and I-immediate coiling resistance of the body are significantly improved, but on the other hand, when the degree of crosslinking is increased, the fixed rot point increases. In addition, crosslinked polymers have difficulty dispersing pigments and are difficult to be compatible with other polymers, so it is difficult for toners that use crosslinked polymers as a binder resin to obtain good development characteristics. There are drawbacks. Moreover, in order to achieve high-speed fixing, it is necessary to reduce the molecular weight of the resin and lower the softening point, which is contradictory to measures to improve offset resistance. Moreover, this inevitably lowers the glass transition point of the resin, and causes undesirable blocking of the toner during storage.

However, in conventional low-speed and medium-speed machines that do not require low-temperature fixing, process measures such as improving the fixing device and toner improvements, such as crosslinking and release additives, are recommended. This did not pose a problem on a practical level due to appropriate countermeasures. (-However, the above-mentioned dilemma has basically not been resolved, and at present it is not possible to obtain a toner that can be fixed from a very low temperature but has good offset and blocking resistance over a wide fixing temperature range. It is.

Recently, low-molecular-weight, non-quality polyester resins and epoxy resins have been attracting attention as materials suitable for low-temperature fixing. Among them, attempts to use polyester resin as a binder for toner were made, for example, in Japanese Patent Publication No. 1268-1268.
It is known from Publication No. 0, etc.

According to these descriptions and experimental studies conducted by the inventors, the fixing temperature of toners using polyester resin as a binder is generally lower than that of other materials such as styrene-acrylic resins, which have been widely used in the past. Although it can be lowered, the offset resistance is on the verge of being improved, but has not yet been achieved.

The main approach to prevent offset in toners containing polyester resin as the main binder has been to mix trivalent or higher polyols and polyacids to make the polymer skeleton nonlinear, as typified by Japanese Patent Publication No. 52-25420. The aim is to impart rubber elastic properties to the resin and improve offset properties during fixing and melting, and the inventors have also studied various examples of these, and it is true that these non-linear properties This is more effective in improving offset resistance, but as with crosslinking in styrene, if non-linearization is performed until sufficient offset resistance is achieved, the fixing point will increase [7 Otherwise, you will not be able to take advantage of the low-temperature fixing properties of polyester resins. Also, unlike the case of crosslinking styrene systems, when polyester systems undergo non-linearization or reticulation, the acid value and hydroxyl value of the resulting resin greatly increase under the same reaction conditions. This increases the moisture resistance and causes deterioration of moisture resistance.

In this way, when considering various properties other than offset resistance, there is naturally a limit to the nonlinearity of polyester.

Still, there is an idea in JP-A-56-1.16041 that aims to improve the offset during melting by mixing a polyvalent metal compound with a polyester resin and giving it a cross-linked structure with metal ions to give the resin all the rubber elastic properties. It is disclosed in the publication No. The present inventors also focused on this technology [7. We investigated various metal compounds, and although it is certainly effective in preventing offset with the heated roller, it is not quite as effective as most metal compounds. must be added,
This appears to be due to an increase in the heat capacity of the toner, but a defect appears in that the constant A point increases considerably.

As mentioned above, the measures of making the polymer nonlinear and metal crosslinking have the drawback of raising the fixing point, which is basically not suitable for low-temperature fixing. As a result of repeated studies on various polyesters, the present inventors found that C
1. By introducing a soft segment into the polymer skeleton, we have developed a dry toner that can be fixed at a constant temperature with a hot roller and has low temperature fixability and does not induce the above-mentioned defects even if it is made non-linear or cross-linked with metal.

In particular, it has been found that the combination of non-linearization and metal crosslinking does not cause the adverse effects of >g when carried out alone, and that there is a significant offset improvement property. Therefore, applying oil to the heated roller (5) etc. is an epoch-making method in that it is extremely mechanical and can ensure sufficient offset resistance even without applying oil at all.

An object of the present invention is to provide a toner that can be sufficiently fixed at a lower temperature, can save energy, and is particularly suitable for high-speed fixing.

A further object of the present invention is to provide a toner ((-1) which has extremely good anti-offset properties and has a wide fixable temperature range from low to high temperatures.

A further object of the present invention is to provide a storage-stable toner that does not cause blocking or agglomeration even in a copying machine or in a relatively high-temperature atmosphere.

A further object of the present invention is to provide a toner that maintains stable chargeability over a wide range of hot water temperatures and has excellent development characteristics.

Its characteristics are that in bis-based polyesters based on etherified diphenols, aromatic acids, especially terephthalic acid, are used as the main component;
Even if it becomes non-linear, it has little negative effect on I51 resistance, and by adding a small amount of divalent or higher organometallic compound, offset resistance can be effectively improved. By introducing a specific alkyl-substituted succinic acid into the polyester skeleton as a soft segment, it is possible to effectively prevent nonlinearization and an increase in the fixation point due to metal crosslinking.

The reason for this, according to the present inventors' speculation, is that the degree of freedom of the functional groups is increased to some extent, and the remaining COOH groups and O
It is believed that reducing the H groups improves moisture resistance. Moreover, C0 to C18 as a soft segment
Because the alkyl group can be incorporated into the main chain (1.), the toughness of the resin itself will not be impaired because it is introduced into the main chain as a branch. When Xtt is incorporated, it becomes similar to linear polyester, and although the fixing point is certainly lowered, the resin becomes brittle, and even when hot melted, the viscous properties become stronger, and it is thought that the anti-offset property will also deteriorate.

The soft segment component used in the polyester of the present invention is preferably an anhydride of phosphoric acid or phosphoric acid having an argyl trading group of C0 to CIM, which effectively lowers the fixing point and has a remarkable effect of improving moisture resistance. there were. It is necessary to contain 10 to 25% of Jusha in polyester,
More preferably, the content is 15 to 20% by weight. If it is less than 10% by weight, it becomes difficult to effectively lower the fixation point, and conversely, if it is more than 25% by weight, there is a strong tendency for blocking during storage.

In addition, as the non-linear component, aromatic or other trivalent or higher polycarboxylic acids, such as trimellitic acid, pyromellitic acid, cyclohexane tricarboxylic acid (di
d, 2,5.7-naphthalene tricarbon iL1,2.
4-naphthalenetricarboxylic acid, 1,2.4-butanetricarboxylic acid, 1゜2.5-hexanetricarboxylic acid,
1,3-dicarboxyl-2-methylenecarboxylpropane, 1,3-dicarboxyl-2-methyl-2-
Methylenecarboxylpropane, tetra(methylenecarboxyl)methane, 1,2,7.8-octanetetracarboxylic acid and their anhydrides can be used. Further, trivalent or higher polyols may be added, such as nrubitol, 1.2.3.6-hexanethetol, 1,4-sorbitan, pentaerythritol, dipentaerythritol, tripentaerythritol, 1-sucrose, 1,2.4-
Menotatriol, glycerin, 2-methylpropanetriol, 2-methyl-1,2,4-butanetriol, trimethylolethane, trimethylolpropane, 1
, 3.5-)rihydroxymethylbenzene, etc. can be used. These non-linear components are polycarboxylic acids,
It is preferable that the polyol is contained in the polyester in an amount of 10 to 30% by weight, and preferably up to 5% by weight.

If the content of polycarboxylic acid is 30% or more or the content of polyols is 5% or more by weight, tit and moisture resistance will deteriorate, and conversely, if the total content of polycarboxylic acid and polyol is less than 10% by weight, nonlinearization will be insufficient. The offset resistance deteriorates.

In addition to the above, the main acid components of the polyester of the present invention include aromatic dicarboxylic acids or g-like anhydrides, and other dicarboxylic acids. 5Qmo1 in the ingredients
% or more must be aromatic dicarboxylic acids □.

Examples of aromatic dicarboxylic acids include terephthalic acid, isophthalic acid, phthalic acid, diphenyl-11, p'-dicarboxylic acid, naphthalene-2,7-dicarboxylic acid, naphthalene-2,6-dicarboxylic acid, diphenylmethane-13.P
'-Dicarboxylic acid benzophenone-4,4'-dicarboxylic acid, 1,2-diphenoxyethane-P-, P-
Dicarboxylic acids and the like can be used, with terephthalic acid being particularly preferred. Other acids that can be used include maleic acid, fumaric acid, glitaric acid, cyclohexanecarboxylic acid, succinic acid, malonic acid, and adipic acid. Furthermore, the diol as the main component is preferably ethoxylated or propoxylated etherified diphenols.

The polyester used in the present invention has a glass transition temperature of 5
Preferably, the temperature is 0 to 80°C, and the softening point is 60 to 130°C. If the glass transition temperature is less than 50° C. or the softening point is less than 60° C., the resulting toner tends to block during storage, resulting in practical defects. On the other hand, if the glass transition temperature exceeds 80.degree. C. or the softening point exceeds 130.degree. C., excessive heat loss is required during fixing, so that the desired low-demand fixing properties are likely to be impaired.

The polyester used in the present invention has an acid value of 10 to 60,
The feminine value is 20 to 50, but if the value is less than 10, the metal crosslinking will be insufficient and the offset resistance will be poor, and if it is more than 60? , 1 Moisture resistance deteriorates.

Further, the polyvalent organometallic compound used in combination with the polyester is one that can react with the carboxyl group in the polyester, such as salts such as magnesium acetate, calcium acetate, basic aluminum acetate, calcium stearate, and lead stearate. ; Alkoxides such as aluminum isopropoxide, aluminum-〇-butokind, aluminum methoxide; Chelate compounds such as aluminum acetylacetonate, nickel acetylacetonate, iron acetylacetonate; and various other metal complexes.

Among them, the acetylacetone metal complex has a remarkable crosslinking reaction with the polyester used in the present invention, and is extremely effective.

In the present invention, the mixing ratio of the polyvalent organometallic compound to the polyester is preferably 0.2 to 4%, and if it is less than 0.2%, there is a cone in the offset resistance.

A charge control agent, a colorant, and a fluidity modifier may be added to the toner of the present invention as necessary, and the charge control agent and fluidity modifier may be mixed (externally added) with the toner. May be used. Examples of charge control agents include metal-containing dyes and nigrosine, conventionally known dyes and pigments can be used as colorants, and fluidity modifiers include colloidal silica and fatty acid metal salts. .

Furthermore, if it is desired to obtain a magnetic toner, magnetic fine particles may be added to the toner. Does it exhibit magnetism as a magnetic substance?
Any material that can be magnetized may be used, such as fine metal powders such as iron, manganese, nickel, cobalt, and chromium, ferrite, alloys and compounds of manganese, and other ferromagnetic alloys such as magnetite, which are conventionally known as magnetic materials. You can use what is listed.

Furthermore, in order to further improve the releasability from the heat fixing roll, the present invention will be explained in detail by using low molecular weight polyethylene, manufacturing examples, and examples.

[Production Example 1] Production method of polyester resin A Polyoxypropylene C2,2)-2,2-bis(4-hydroxyphenyl)propane 1810F and sorbitol 11O
f is a thermometer and a stirrer.

Place in a fourth round bottom flask equipped with a glass inlet tube and a flow down condenser. Nitrogen gas is introduced through the glass inlet tube to stir the polymer blend and create an inert atmosphere in the reaction vessel.

Next, while stirring, the temperature was heated to 50°C, and terephthalic acid 8309,) limellitic acid 4201, and succinic acid 645y having an alkyl substituent having 8 carbon atoms were added to the reaction vessel, and after reacting at 210°C for 5 hours, the temperature was gradually increased. Reduce the pressure to about 100
The reaction was carried out using ml-IP, and the reaction was terminated when the softening point of the resin reached 100°C.

The resulting resin had a glass transition temperature of 65°C and an acid value of 30.0.
, number average molecular weight is 6,700, weight average molecular weight is 73,
It was 700.

[Production Example 2] Production method of Polyester B The same procedure as in Production Example 1 was repeated except that sorbitol and trimellitic acid were not added, and the reaction was terminated when the softening point of the resin reached 95°C. The resulting resin has a glass transition temperature of 5
The temperature was 8°C, the acid value was 24.0, the number average molecular weight was 4,300, and the weight average molecular weight was 25,800.

[Production Example 3] Manufacturing method of polyester resin C In Production Example 1, succinic acid having an alkyl substituent having 8 carbon atoms was not added, and the other things were the same, but even if the reaction time and reaction temperature were varied, the acid value remained the same. The reaction was terminated when the acid value did not decrease and the acid value reached 75. The obtained resin had a glass transition temperature of 85°C, a softening point of 142.5°C, and a number average molecular weight of 8,600. The weight average molecular weight was 11,600.

[Production Example 4] Production method for polyester D In Production Example 1, the amount of succinic acid having an alkyl substituent having 8 carbon atoms was added to 1032? , trimellitic acid 21
The reaction was completed in the same manner except that the acid value of the resin reached 20. The resulting resin has a glass transition temperature of 43°C.
The softening point was 83° C., the number average molecular weight was 13,800%, and the weight average molecular weight was 30,400.

[Example 1] The above-treated mixture was heated and kneaded at 150°C for 15 minutes with a hot roll, allowed to cool, and then crushed, further pulverized with a Jet-Mi Il crusher, and then classified with an Albine classifier to determine the average particle size. A finely ground product with a constant particle size distribution of 10-12μ was obtained. Colloidal silica (It-972
) was added in an amount of 0.3 parts by weight to prepare a developing toner.

[Example 2] A toner for imaging was prepared in the same manner as in Example 1 except that aluminum isopropoxide was used instead of iron acetylacetonate.

[Comparative Example 1] A toner for imaging was prepared in the same manner as in Example 1 except that iron acetylacetonate was not added.

[Comparative Example 2] A toner for imaging was obtained in the same manner as in Example 1 except that 10 parts of iron acetylacetonate were added.

[Comparative Example 3] A toner for imaging was prepared in the same manner as in Example 1 except that polyester B was used instead of polyester.

[Comparative Example 4] A developing toner and U were prepared in the same manner as in Example 1 except that polyester C was used instead of polyester A.

[Comparative Example 5] A toner for imaging was prepared in the same manner as in Example 1 except that polyester D was used instead of polyester.

[Comparative Example 6] A toner for imaging was prepared in the same manner as in Example 1 except that styrene butyl acrylate copolymer was used instead of polyester A. The fixing performance was evaluated using NP-400) (E, when the fixing unit of the copying machine was taken out and the temperature of the heat roller was 100℃~
Controllable up to 250℃ and linear speed of 100 to 500 ++
+n/ S'C'j uses a separate fixing device that can be changed to 5T.

The nip +lJ was set at 85 mm, and the surface of the heated roller was coated with Teflon, and the offset properties and fixing point were evaluated without applying oil. To evaluate the blocking property, Toner 202 was placed in a constant temperature bath at 50°C.
After being allowed to stand for 4 hours and allowed to cool at room temperature, the degree of agglomeration was evaluated.

The above results are summarized in Table 1.

When an oil applicator was installed on an NP-400RE copying machine and the toner of Example 1.2 was used to continuously produce 000 images, a clear image with no capri was obtained at the maximum hour. The fixing properties and anti-offset properties were also satisfactory.

Regarding offset resistance in particular, when the heated roller was observed at the end of the experiment, almost no toner fusion was observed. In addition, blocking and agglomeration did not occur often in the developer hopper and during storage.

Comparison column 1. 3. When a similar experiment was conducted with toner No. 5, the fixing performance was good, but with toner No. 5 of Comparative Example 1, the fixing performance was good.
Toner starts to fuse to the heat roller from 00 sheets, 1.0
An offset appeared in the 115i image when printing 00 sheets. In the toner of Comparative Example 3, an offset appeared in the image after 500 sheets were printed. Furthermore, with the toner of Comparative Example 5, an offset appeared in the image after 800 sheets were printed. The toner of Comparative Example 4 was heated to 35°C.
After being left in a high-temperature environment of 85% It.H for 24 hours, both sides were taken out, resulting in low image formation and image smearing. The toner of Comparative Example 2, 4.6 was heated to 9 at a temperature of 5°C.
When images were continuously printed on up to 9 images, the images were clear and good, but the fixability was insufficient. With the toner of Comparative Example 2, the toner peeled off from the paper after the 90th image was rubbed lightly by hand, while with the toner of Comparative Example 4 the same phenomenon occurred after the 50th image, and with the toner of Comparative Example 6 after the 16th image. presented. Furthermore, the toner of Comparative Example 2 had unstable developability even at normal temperature and normal humidity F, and images appeared thin, uneven, etc.

-3;

Claims (1)

[Claims] An organometallic compound having a valence of 2 or more: (5) Succinic acid substituted with an alkyl group having 6 to 18' carbon atoms in an amount of 10 to 25% by weight based on the binder resin, or an anhydride thereof, (81
An acid consisting of trivalent or higher polycarboxylic acids and/or trivalent or higher polyols, aromatic dicarboxylic acids accounting for 50 mol% or more of the total acid component (Q), and (1) etherified diphenols. A heat fixable dry toner containing a non-linear, low melting point polyester having a valence of 10 to 60.