JPH01142561A - Liquid developing agent for electrostatic photography - Google Patents

Abstract

PURPOSE:To prevent the generation of an offset phenomenon when a heat-roll fixing system which has the high heat efficiency and is capable of rapid fixing, is used, by incorporating at least an alkaline salt of a polyolefin or a polyolefin copolymer in the title agent. CONSTITUTION:A toner comprising a colorant and a binding resin as main components is dispersed in an aliphatic hydrocarbon solvent, and the alkaline salt of the polyolefin or the polyolefin copolymer is incorporated in the liquid developing agent, especially in the toner. In the case, all of binding resin may be composed of alkaline salt of the polyolefin and/or the polyolefin copolymer, but the alkaline salt is incorporated in the liquid developer in an amount of 10-90wt.%, preferably 40-80wt.%, based on the total amount of the biding resin. Thus, the heat-roll fixing of the toner is permitted, without generating the offset phenomenon, resulting the easy rapid fixing of the toner.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to an electrophotographic liquid developer used in electrophotography, electrostatic recording, electrostatic printing, and the like.

[Prior art]

Toner fixing methods include (i) an oven fixing method in which the toner is passed through a heated atmosphere using an electric heater; (ii)
A hot roll fixing method in which the image is passed between a pair of rolls, at least one of which is a heated roll, and (2) a pressure fixing method in which the image is passed between a pair of rigid rolls at room temperature are known.

Each of these fixing methods has its advantages and disadvantages, but
Among them, in the hot roll fixing method (ii) above, the surface of the heating roll and the toner image holding surface on the fixing substrate come into pressure contact, so that the toner image is fused onto the fixing substrate (transfer paper, etc.). Because it has high thermal efficiency and can fix quickly, it is especially suitable for image forming apparatuses intended for high-speed copying.

Very suitable. For this reason, most copying machines that use liquid developers have conventionally adopted an oven fixing method, but in recent years more and more examples have adopted a heated roll fixing method.

However, in this hot roll fixing method, the toner is brought into pressure contact with the heated roll surface in a heated molten state, so a part of the toner adheres to the roll surface and then re-adheres to the fixing substrate, staining the image (so-called It has the disadvantage that it tends to cause a phenomenon called the "offset phenomenon".

〔the purpose〕

The first object of the present invention is to provide a new liquid developer (liquid developer for electrostatography) that does not cause an offset phenomenon when using a hot roll fixing method that has high thermal efficiency and is capable of high-speed fixing. . A second object of the present invention is to provide a liquid developer with excellent fixing properties.A third object of the present invention is to provide a liquid developer with good dispersion stability.

〔composition〕

The present invention relates to an electrostatographic liquid developer comprising a toner mainly composed of a colorant and a resin dispersed in an aliphatic hydrocarbon carrier liquid, which contains at least an alkali salt of a polyolefin or a polyolefin copolymer. It is characterized by certain things.

By the way, the inventors of the present invention have diligently researched and examined liquid developers that allow high-quality copies to be obtained without causing offset development using a hot roll fixing method, and have found that certain It has been confirmed that the above object can be achieved by adding an alkali salt of a polyolefin or polyolefin copolymer having specific properties.

The present invention has been made based on this.

The present invention will be explained in more detail below.

As mentioned earlier, when heat fixing is performed using a conventional liquid developer (wet toner), some carrier liquid is present in the toner, so the toner particles dissolve in the carrier liquid and swell, forming the toner. The cohesive force of the layer decreases and 'hot offset' tends to occur.Also, there is a tendency for the toner layer to fuse with metallic heating rollers.In this regard, dry type developer (dry type toner) does not heat the silicone oil. Measures have been taken to prevent the toner from melting on the fixing roller by coating the roller or using a Teflon roller.However, since a carrier liquid is used in copying operations using liquid developer, such There is no practice of applying silicone oil to the heating roller or using a Teflon roller as the heating roller.

The electrostatic photographic liquid developer of the present invention has a toner mainly composed of a colorant and a binder resin as a carrier liquid (aliphatic hydrocarbon solvent).
It takes the form of being dispersed inside, and if necessary, a polarity control agent or the like is further added.

As described above, the liquid developer, particularly the toner, contains an alkali salt of a polyolefin or a polyolefin copolymer, and the polyolefin or copolymer thereof contains at least a carboxyl group or a basic group. For example, carboxyl groups include acrylic acid, methacrylic acid, maleic acid, maleic anhydride, itaconic acid, fumaric acid, etc., and basic groups include vinylpyridine, vinylpyrrolidone, etc. Dimethylamine is an alkali salt.

Examples include amine salts such as diethylamine, triethylamine, and ethanolamine, and pyridine, quinoline, morpholine, and ammonium salts, which convert polyolefins or copolymers thereof into alkali salts. In addition, when the copolymer itself contains the above-mentioned basic group, it is not necessary to use it as an alkali salt. However, in this specification, a copolymer containing such a basic salt as a 7mer is also treated as an alkali salt of a polyolefin copolymer.

Note that Na, Ca, Zn, Fe, and Zr.

Alkali salts such as AI, Mg, Ni, etc. are also conceivable, but in such a case, the polyolefin or its copolymer becomes an ionomer resin, making it unsuitable for use as an electrophotographic developer. The reason seems to be that the crosslinked structure becomes strong and does not disperse well in highly insulating liquids.

Some of the alkali salts of the polyolefin or polyolefin copolymer according to the present invention are listed below. In addition, () after the polymer or copolymer here
The numerical values described therein are the weight proportions (wt%) of the copolymer compositions.

(8) Triethylamine salt of polyethylene oxide (9) Pyridine salt of polyethylene oxide (13) Ethylene-methacrylic acid copolymer (9515)
Examples of inorganic pigments used in ethanolamine salt colorants include carbon blacks such as Furnace Black, Acetylene Black, and Channel Black; commercially available products such as Printex G, Printex V, Special Black 15, Special Black 4, and Special Black. 4-B (manufactured by Degussa)
, Mitsubishi #44. $30, MA-11, MA-10
0 (Mitsubishi Carbon), Raven 30, Raven 40,
Examples include Conductex SC (manufactured by Columbia Carbon), Regal 400.660,800, and Black Pearl L (manufactured by Cabot). Inorganic white pigments such as zinc oxide, titanium oxide, and silicon oxide can also be exemplified.

Organic pigments include Phthalocyanine Blue, Phthalocyanine Green, Rhodamine Lake, Malachite Green Lake, Methyl Violet Lake, Peacock Blue Lake, Narator Green B, and Permanent Red 4R.
, Hansa yellow, benzidine yellow, and thioindigolet.

In the present invention, organic pigments may be used alone, inorganic pigments may be used alone, or they may be used in a mixed system.

As the resin for coating the pigment, the above-mentioned alkali salts of polyolefins or copolymers thereof are used. Although all of the binder resin can be an alkali salt of the polyolefin and/or an alkali salt of the polyolefin copolymer, 10 to 90% by weight of the entire binder resin is preferably 4% by weight.
It is desirable that the alkali salt is used in an amount of 0 to 80% by weight. Resins other than this alkal salt include polyolefin and acrylic resin.

Examples include rosin-modified resins, styrene-butadiene resins, epoxy resins, polyester resins, natural resins, paraffin wax, and other resins.

For example, paraffin wax and polyolefin include the following.

Manufacturer Name: E Pattern Softening Point Allied Chemical AC Polyethylene 1702
85℃AC polyethylene 617,617A 1
02AC polyethylene 9, 9 A 117A
C polyethylene 430 60AC polyethylene 405 96AC polyethylene 401
102AC polyethylene 540 108AC
Polyethylene 580 108 Kodatsu
Evolen N-14105 Evolen
E-1596 Sanyo Chemical Sunwax 131-P
108 Sunwax 151-P 10
7 Sunwax 161-P 111 Sunwax 165-P 107 Sunwax
171-P 105 Sunwax E-2
50P 102 Sunwax E-300P
98 genuine chemicals paraffin wax
40-90℃ Hoechst PED52 Engineering 1o4 PED 543 110PED
153 99 cheap crude oil
Neowax L 105 Neowax E 100 The liquid developer of the present invention has a form in which a toner mainly composed of these colorants and a specific resin is dispersed in a carrier liquid.
Representative examples of aliphatic hydrocarbon solvents include isododecane,
n-hexane, etc., and commercially available products include Shellsol-71 manufactured by Shell Oil Company, Isopar G manufactured by Exxon Company,
Examples include H, E, L, and so on.

A liquid developer is generally prepared by mixing 0.3 to 3 parts by weight of a binder resin (part or all of the binder resin is an alkali salt of a polyolefin or a copolymer thereof) to 1 part by weight of a colorant. This is then sufficiently dispersed in the presence of 10 to 20 parts by weight of an aliphatic hydrocarbon carrier liquid using a dispersing machine such as an attritor, a ball mill, or a kedimir to obtain a concentrated toner, as required.

This may be diluted 5 to 10 times with a similar solvent (aliphatic hydrocarbon).

In this case, the alkali salt dispersion (resin dispersion) of the specific polyolefin or polyolefin copolymer described above can be used as is as the binder resin and solvent. In addition, when preparing a concentrated toner, if necessary, other resins other than the alkali salt of polyolefin and/or alkali salt of polyolefin copolymer according to the present invention, metallic soap, lecithin, linseed oil, high grade It is also possible to add a polarity control agent such as a fatty acid, but since the alkali salt in the present invention has strong polarity and good dispersion stability, good results are expected even without the addition of a polarity control agent. I can do it.

As the colorant, ordinary inorganic or organic pigments may be used as described above, but preferably pigment particles are dispersed down to primary particles to further improve gradation, resolution, image density, etc. For this purpose, it is effective to use a coloring agent produced by the Francing method.

The flancing method involves putting a pigment or a water-containing paste of the pigment together with a resin solution or resin in a kneader called a flasher, mixing well, and in this process, the water existing around the pigment is replaced by the resin solution or resin. This is taken out of the kneader, the aqueous phase is discarded, and the pigment is mixed and dispersed in the resin solution or resin by heating or at room temperature, which is then dried, the solvent is removed, and the resulting lump is pulverized. be. This material will be referred to as a "flushing colorant" in the present invention. Note that it is also possible to take measures such as removing water and solvent under reduced pressure while mixing in a kneader. In the flushing process, by kneading not only the pigment but also the dye into a slurry with water, almost the same results as the pigment can be obtained. Therefore, in the present invention, the dye to be subjected to the flushing process is also used as a toner component. is possible. The ratio of colorant (dye/pigment) and resin when flushing is 100 parts by weight of resin to 1 part dye/pigment.
0 to 60 parts by weight is suitable. Furthermore, it is particularly advantageous to carry out the flushing treatment in the presence of humic acid, humic acid salts (Na salt, NH salt, etc.) or humic acid derivatives. The amount of humic acids added is 0% of the dye and pigment aqueous solution.
．． Approximately 1 to 30% by weight is appropriate.

As the resin used for flushing, any binder resin that has conventionally been used as a binder resin for wet toners can be used, but in particular, the alkali salt of polyolefin and/or the alkali salt of polyolefin copolymer according to the present invention can be used. is suitable.

Some examples of the production of colorants subjected to flushing treatment are as follows.

Colorant production example-1 200g of water and 2 humic acid ammonium salts in a gallon kneader
Carbon (Mitsubishi #44) 250 in 0g well dissolved
g was added and thoroughly mixed and dispersed in a kneader.

Next, the ethylene-maleic acid copolymer (9
Add 750 g of triethylamine salt of
The mixture was heated to 0° C. and mixed, and water was separated.

After further mixing at about 120° C. for 4 hours, the mixture was vacuum dried, cooled, and crushed to obtain a flushing colorant.

Colorant production example-2 200g of water and carbon (Mogal A,
(manufactured by Columbia Carbon) 250g.

After 6 well mixed and dispersed in the kneader, Sunwax 1
300 g of 51P and 300 g of the pyridine salt of the ethylene-ethyl acrylate-acrylic acid copolymer (60/30/10) described above in (2) were added, and the mixture was heated and kneaded at about 150°C. After further mixing at 120° C. for 2 hours, the mixture was vacuum dried, cooled, and pulverized to produce a flushing colorant.

Following the procedure of Colorant Production Example-1, the flushing colorants of the following Examples (Colorant Production Examples) 3 to 10 are prepared as follows (Table-1).
Manufactured as follows.

(Margin below) Next, examples and comparative examples will be shown.

Example 1 Flushing colorant (colorant production example-1) 50 parts by weight Isopar H (
Put 200 parts by weight (manufactured by EXXSON) into a ball mill 2
After 4 hours of dispersion, 300 parts by weight of Isopar H was further added and dispersed for 1 hour to obtain a concentrated toner. 200 g of this concentrated toner was diluted with Isopar HIQ to prepare a liquid developer.

Example 2 The same procedure as in Example 1 was carried out using 60 parts by weight of the pyridine salt of the ethylene-ethyl acrylate-acrylic acid copolymer of (2) above, 100 parts by weight of carbon black (Tugal 400, manufactured by Kabotsu 8), and 100 parts by weight of Isopar H. A liquid developer was prepared.

Example 3 A liquid developer was prepared in exactly the same manner as in Example 1, except that the colorant was replaced with that of Colorant Production Example-4.

Example 4 A liquid developer was prepared using 50 parts by weight of Printex (manufactured by Degussa Carbon) and 0 parts by weight of Isopar H3O in the same manner as in Example 1 (however, the developer was dispersed in an attritor for 10 hours).

Comparative Example Ethylene-maleic acid copolymer (9515) was replaced with triethylamine salt of ethylene-maleic acid copolymer (9515).
A comparative liquid developer was prepared in the same manner as in Example 1 except that 515) was used.

These liquid developers are stored in the developing section of an electrophotographic copying machine (Ricoh CT5058), and the fixing heater o
After producing an image using ff, the non-offset area was examined using a fusing tester. The results are shown in the table below (Table 2).

Table 2 Also, when the alkali salt of the polyolefin or polyolefin copolymer of the present invention was used as a binder resin for dry toner, good results were obtained similarly to the above.

〔effect〕

According to the developer of the present invention, hot roller fixing is possible without causing an offset phenomenon, and high-speed fixing is facilitated. This is because the alkali salt of the polyolefin or polyolefin copolymer used in the present invention has the effect of dispersing toner particles into small particles, and also has excellent drying properties, making it difficult for them to adhere to the heating roller of a copying machine. It seems to be.

The liquid developer of the present invention is capable of fixing with high sharpness without bleeding or the like even by a flash fixing method.

Claims (1)

[Scope of Claims] 1. A liquid developer comprising a toner mainly composed of a colorant and a resin dispersed in an aliphatic hydrocarbon carrier liquid, which contains at least an alkali salt of a polyolefin or a polyolefin copolymer. A liquid developer for electrostatic photography, characterized in that: 2. The electrostatic photographic liquid developer according to claim 1, wherein the colorant is produced by a flushing method using an alkali salt of a polyolefin or a polyolefin copolymer.