JP2942841B2 - Liquid developer for electrostatic image - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[Industrial fields]

The present invention relates to a hot roll fixing liquid developer used for electrophotography, electrostatic recording, electrostatic printing, and the like.

[Prior art]

As a liquid developer for heat roll fixing roll,
Nos. 301966 to 301969 and 64-50062 to 50067 and 64
-52167 and 64-142560 to 142561.
Since these are carrier liquids mainly composed of aliphatic hydrocarbons, the oil of the aliphatic hydrocarbons is discharged out of the copying machine, and silicone oil must be supplied for application to a fixing roll. There have been problems such as a complicated copying machine and an increase in the number of consumables.

[Object of the present invention]

An object of the present invention is to reduce a hydrocarbon solvent gas generated from a copying machine. Also, in a hot roll fixing device using a liquid developer, it is possible to remove the oil applying device to the fixing roll, to save the trouble of oil supply, and to mix the non-flammable liquid agent at a certain ratio to cause ignition. The purpose is to reduce the dangers such as.

Configuration of the Invention

In recent years, a hot roll fixing method has been proposed as a fixing method of a liquid developer having high thermal efficiency and capable of high-speed fixing. If a hydrocarbon solvent is used as the carrier liquid and this fixing method is adopted, the amount of solvent gas emitted per unit number will slightly decrease compared to the conventionally used atmosphere fixing method, but it will be possible to copy many sheets at high speed. When this occurs, a large amount of solvent gas is generated. Further, in order to increase the releasability between the toner layer and the fixing roll, it was necessary to apply silicone oil. An object of the present invention is to improve the above-mentioned drawbacks by adding a fluorine-based solvent as a carrier liquid, increase the cohesive force of the toner, and prevent so-called "hot offset". Fluorinated solvents used in the present invention include Fluorinert FC-77, FC-40, FC-43, FC-70 (all manufactured by Sumitomo 3M), Aflud, E-10, E-16 and E-18. (Manufactured by Asahi Glass Co., Ltd.). Silicone solvents that may be used at the same time include KF96 (Shin-Etsu Silicon), SH200, SH344 (Toray Silicon), TSF451 (Toshiba Silicon), and other decamethyltetrasiloxane, octamethyltrisiloxane, etc. May be used. Also, cyclohexane as an aliphatic hydrocarbon solution,
Petroleum hydrocarbons such as n-hexane, n-heptane, n-octane, n-nonane, isooctane, isododecane, ligroin, and mixtures thereof (as commercial products, Isopar E, G, H, L, K, manufactured by Exxon Chemical Co., Ltd.) V, Shell Sole 71, Solbesso 150, etc., manufactured by Shell Sekiyu KK). In order to reduce the transfer solvent, the carrier liquid should be 10 cSt or less, preferably 3 cSt or less. In the present invention, a polyolefin or a polyolefin copolymer having an acid value of 0.5 to 50 and a melt viscosity at 200 ° C. of 50 to 15,000 cp as means for increasing the cohesive strength of the toner is used. By the way, the present inventors have studied and studied a liquid developer for obtaining a high quality copy without causing an offset phenomenon by a hot roll fixing method, and as a result, a polyolefin having a specific property in the liquid developer is obtained. Or the addition of a polyolefin copolymer achieves the object, and furthermore, good transfer at a low temperature is possible. Hereinafter, the present invention will be described in more detail. As mentioned earlier, the toner particles of a conventional liquid developer swell due to the presence of some carrier liquid, which reduces the cohesive force, resulting in "hot offset" during thermal fixing of the transferred image.
And the toner tends to fuse to the metallic heating roll. In the case of a dry developer, in order to eliminate these defects, means for applying silicone oil to a heating roll or using a Teflon roll to prevent the toner from fusing to a fixing roll are employed. However, in a copying operation using a liquid developer, since a carrier liquid is used, such silicone oil is not applied to a heating roll or a Teflon roll is used as a heating roll. The electrostatic image liquid developer of the present invention is prepared by using a binder resin, a colorant, and a carrier liquid (a mixed liquid of a fluorine-based solvent, an aliphatic hydrocarbon solvent and / or a silicon-based solvent) as main components. If necessary, a polarity control agent or the like is further added. The liquid developer of the present invention has an acid value of 0.5 to 5 as described above.
0, contains a polyolefin or a polyolefin copolymer having a melt viscosity at 200 ° C. of 50 to 15,000 cp, and if the polyolefin or the polyolefin copolymer has an acid value of 0.
If it is less than 5, the specific charge (Q / M) of the toner decreases, and the transferability of the toner to the substrate to be fixed (transfer paper) deteriorates. Conversely, if the acid value exceeds 50, the storability of the toner deteriorates, and the toner solidifies during storage at a high temperature. On the other hand, if the melt viscosity at 200 ° C. is 50 cp or less, the toner layer penetrates to the back side of the transfer paper due to heating, so that the so-called double-sided copy that copies on both sides of the transfer paper becomes difficult to see, and between toners. The adhesive strength of the resin decreases, and the fixability becomes poor. Also, 200
When the melt viscosity at 15.degree. C. is 15.000 cp or more, it is difficult for the toner to thermally fuse at the time of fixing, so that it is difficult to fix at a low temperature or high speed which is economically preferable. Satisfying these conditions, polyolefins according to the present invention, or some of the polyolefin copolymers,
Table 1 shows the results. In addition, the numerical value described in parentheses after the copolymer in the table is the weight ratio (% by weight) of the polymer. Examples of inorganic pigments used as colorants include furnace black, acetylene black, and carbon black.
Channel Black, PRINTEX G as a commercial product,
PRINTEX V, Special Black 15, Special Black 4, Special Black 4-B (made by Degussa), Mitsubishi # 44, # 30, MA-11, MA-100 (made by Mitsubishi Carbon), Raven 30, Raven 40, Conductex SC
(Manufactured by Columbia Carbon), Regal 400, 660, 800
Black Pearl L (manufactured by Cabot Corporation) and the like. Further, 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, nattole green B, permanent red 4
R, Hansa Yellow, Benzidine Yellow, Thioindigolet and the like. In the present invention, an organic pigment alone or an inorganic pigment alone may be used, or a mixture of these may be used. As the resin for coating the pigment (binder resin), the acid value mentioned above is 0.5 to 50 (preferably 1 to 30), and the melt viscosity at 200 ° C. is 50 to 15,000 cp (preferably 100 to 10,000 cp). Polyolefin, or a polyolefin copolymer is used, other, general polyolefin, acrylic resin, rosin modified resin, styrene-butadiene resin, natural resin, paraffin wax, other resins as long as the present invention is not hindered Used mixed. Therefore, the specific polyolefin or polyolefin copolymer (acid value is 0.5 to 50, 2
The ratio of melt viscosity at 00 ° C. of 50 to 15,000 cp) is suitably about 10 to 90% by weight. This ratio can be similarly applied to a liquid developer using a kneading or flushing colorant described later. Here, among the other resins, for example, paraffin wax and polyolefin include those shown in the following table. In general, a liquid developer is prepared by mixing 0.3 to 3 parts by weight of a binder resin with respect to 1 part by weight of a coloring agent, and mixing the mixture with an attritor in the presence of 10 to 20 parts by weight of an aliphatic hydrocarbon carrier liquid.
Concentrated toner is sufficiently dispersed by a dispersing machine such as a ball mill or a Keddy mill to form a concentrated toner, and if necessary, a high-resistance low-dielectric constant comprising a mixed liquid of a fluorine-based solvent and an aliphatic hydrocarbon solvent and / or a silicon-based solvent. It may be diluted 5 to 10 times with the above solvent. In this case, a dispersion (resin dispersion) containing at least one of the above-mentioned specific polyolefin or polyolefin copolymer as the binder resin and the solvent can be used as it is. Further, at the time of preparing the concentrated toner, if necessary, a polar controlling agent such as a resin other than the binder resin according to the present invention, a metal soap, lecithin, linseed oil, and higher fatty acids may be added to the mixture. However, since the toner containing the polyolefin or polyolefin copolymer of the present invention has strong polarity and good dispersion stability, good results can be expected without adding a polarity controlling agent. As the colorant, ordinary inorganic or organic pigments may be used as described above, but it is particularly preferable to disperse the pigment particles up to the primary particles, and to further improve the gradation, resolution, image density, and the like. It is effective to use a coloring agent treated by a flushing method. The flushing method is a method in which a pigment or a water-containing paste of a pigment is put together with a resin solution or a resin in a kneader called a flasher and mixed well at room temperature or under heating (water present around the pigment in this process is reduced by the resin solution or the resin). Will be replaced.) This is taken out of the kneader, the aqueous phase is discarded, the mixture which has been further kneaded and dispersed under heating or at room temperature is dried, the solvent is removed, and the obtained mass is pulverized. This is referred to as "flushing pigment" in the present invention. In addition, an allowance for removing water and the solvent under reduced pressure while kneading with a kneader may be adopted. In the flushing process, not only the pigment but also the dye is kneaded with water in a muddy state, so that almost the same result as the pigment can be obtained. In the present invention, the dye to be flushed can be used as the toner component. It is. The ratio of the dye / pigment to the resin at the time of flashing is 10 parts / dye to 100 parts by weight of the resin.
~ 60 parts by weight is suitable. It is particularly advantageous to carry out the flushing treatment in the presence of humic acid, humates (Na salt, NH ₄ salt, etc.) or humic acid derivatives. The amount of the humic acids to be added is suitably about 0.1 to 30% by weight of the aqueous solution of the dye and pigment. As the resin used for the flushing, any resin which has been conventionally used as a binder resin for a wet toner can be applied. In particular, the specific resin (acid value of 0.5 to 50, 200 ° C.) in the present invention is applicable. The polyolefin or the polyolefin copolymer having a melt viscosity of 50 to 15,000 cp is preferable. Colorant Production Example-1 200 g of water in a gallon kneader, ammonium humate 20
g dissolved well in carbon black (Mitsubishi # 44) 250
g was mixed and dispersed well in a kneader. Next, 750 g of the ethylene-vinylpyridine-maleic acid copolymer (90/5/5) of (1) in Table 1 was added, and heated and mixed at about 180 ° C. to separate water. Furthermore, after kneading at about 180 ° C for 4 hours, vacuum drying, cooling,
Pulverized to obtain a flushing colorant. Colorant Production Example-2 200 g of water in a gallon kneader, ammonium humate 20
250 g of carbon black (Mogal A, manufactured by Colombia Carbon Co., Ltd.) was added to the dissolved g, and mixed and dispersed well in a kneader. Next, 300 g of sun wax 151P and the above Table-1
300 g of the ethylene-ethyl acrylate-acrylic acid copolymer (90/5/5) in (2) was added and heated and mixed at about 150 ° C. Further, after kneading at about 150 ° C. for 2 hours, vacuum drying, cooling and pulverization were performed to obtain a flushing colorant. Colorant Production Examples 3 to 10 The formulations in Table 3 below were treated according to the procedure of Colorant Production Example 1 to produce colorants.

【Example】

In the following examples, "parts" represents "parts by weight". Example 1 Colorant of Colorant Production Example-1 50 parts Lauryl methacrylate / methyl methacrylate / methacrylic acid / glycidyl methacrylate (80/10 /
5/5) Isopar H 20% solution of copolymer 100 parts KF96L-1.5 200 parts were dispersed in a ball mill for 24 hours, and then KF96L-1.5
Was added and dispersed for 1 hour to obtain a concentrated toner. 200 g of this was diluted with Fluorinert FC-771,
A liquid developer was used. Example 2 60 parts of polyethylene oxide (5) in the above Table 1 stearyl methacrylate / methyl methacrylate /
Methacrylic acid / hydroxymethyl methacrylate (85/7
/ 4/4) Copolymer Isopar H 10% solution 200 parts Carbon black (Mitsubishi Carbon MH-100) 50 parts Acue E-18 100 parts was used to prepare a liquid developer in the same manner as in Example 1. Example 3 A liquid developer was prepared in exactly the same manner as in Example 1, except that the colorant was changed to that of Colorant Production Example-6. Example 4 80 parts of an ethylene-methacrylic acid copolymer (95/5) of (9) in Table 1 was kneaded with 120 parts of carbon black (Regal 400 manufactured by Cabot Corporation) at 120 ° C. for 2 hours using a two-roll mill. And pulverized to obtain a colorant. A liquid developer was prepared in the same manner as in Example 1 except that 100 parts of the above colorant, 100 parts of Aclude E-10 were used. The results of examining various characteristics using the above liquid developer are shown in the following table. As is evident from the above results, even if oil is not applied to the fixing roll by the developer of the present invention, a temperature range within a range in which the hot roll can be fixed without causing an offset phenomenon can be obtained, and the hot roller can be fixed. You can see that. Further, the developer of the present invention is capable of performing high-sharpness fixing without image bleeding even by a flash fixing method. In a closed room, continuous copying was performed using a test copying machine, and the solvent gas concentration was measured.The result was 300 to 360 ppm for the developer using only Isopar H as the carrier liquid, whereas the development according to the present invention Each of the preparations was halved to 80 to 150 ppm.

【effect】

By using the developer of the present invention, hot roll fixing can be performed without causing an offset phenomenon without applying oil to the fixing roll, and high-speed, low-energy fixing can be performed with a compact copying machine. . Also, the amount of hydrocarbon-based gas generated from the copying machine was reduced.

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Hidemi Uematsu 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd. (58) Field surveyed (Int. Cl. ⁶ , DB name) G03G 9 / 13

Claims (2)

(57) [Claims] A toner liquid comprising a colorant and a resin is dispersed in a high-resistance low-dielectric-constant carrier liquid comprising a mixed liquid of a fluorine-based solvent, an aliphatic hydrocarbon solvent and / or a silicone-based solvent. Liquid developer for electrostatic images comprising:
Liquid development for an electrostatic image, characterized by containing at least one of a polyolefin having an acid value of 0.5 to 50 and a melt viscosity at 200 ° C. of 50 to 15,000 cp as a resin component, or a polyolefin copolymer. Agent. 2. The toner is produced by kneading a pigment as a colorant and a polyolefin or a polyolefin copolymer having an acid value of 0.5 to 50 and a melt viscosity at 200 ° C. of 50 to 15,000 cp. The liquid developer for an electrostatic image according to claim 1, wherein