JPH03225363A - Liquid developer for electrostatic charge image - Google Patents

Abstract

PURPOSE:To decrease the evaporation of the hydrocarbon solvent in the developer from a copying machine and to eliminate the need for application of oil on a fixing roll b y dispersing toner particles contg. a specific olefin resin into a specific carrier liquid mixture. CONSTITUTION:This developer is formed by dispersing the toner particles consisting of the resin (A) and coloring agents (B) into the carrier liquid consisting of the liquid mixture composed of a fluorine solvent and an aliphat. hydrocarbon solvent and/or silicone solvent and having a high resistance and low dielectric constant. An olefine resin having 25 to 700 melt index (e.g.: ethylene/vinyl acetate/lauryl methacrylate copolymer) is compounded as the component (A). The powder obtd. by kneading the dispersion of desired pigments with the above-mentioned polyolefin resin and drying and grinding the mixture is preferably used as the component B.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field] The present invention relates to a liquid developer for hot roll fixing used in electrophotography, electrostatic recording, electrostatic printing, and the like.

[Prior art 1: As a liquid developer for a heat roll fixing roll,
-301966 to 301969, 64-500
No. 62-50067, No. 64-52167, No. 64-
142560-142561, etc. Since these are carrier liquids mainly composed of aliphatic hydrocarbons, the aliphatic hydrocarbon gas is discharged outside the copying machine, and silicone oil must be supplied to apply to the fixing roll. There were problems such as the copying machine becoming more complex and the number of consumables increasing.

(Objective of the present invention) An object of the present invention is to reduce hydrocarbon solvent gas generated from copying machines. In addition, in a hot roll fixing device using a liquid developer, it is possible to remove the oil application device to the fixing roll, eliminate the trouble of oil supply, and furthermore, by mixing a certain proportion of nonflammable liquid. The purpose is to reduce risks such as ignition.

(Structure of the Invention) In recent years, hot roll fixing has been proposed as a fixing method for liquid developers that has high thermal efficiency and is capable of high-speed fixing. If a hydrocarbon solvent is used as the carrier liquid and this fixing method is adopted,
Compared to conventional atmospheric fixing, the amount of solvent gas emitted per unit number of sheets is slightly reduced, but a large amount of solvent gas is generated when a large number of sheets are copied at high speed. Also,
It was necessary to apply silicone oil to improve the releasability between the toner layer and the fixing roll. The present invention aims to improve the above-mentioned drawbacks, increase the cohesive force of the toner, and prevent so-called ``hot offset'' by incorporating a fluorine-based solvent as a carrier liquid.

Fluorinated solvents used in the present invention include Fluorinert FC-77, FC-40, FC-43, FC-70
(Manufactured by 3M Company), Afroud, E-10, E-1
6, E-18 (manufactured by Asahi Glass Co., Ltd.), and the like. In addition, examples of silicone-based solvents that may be used at the same time include KF96 (Shin-Etsu Silicon), 5H200, 5H344.
(Toshiba Silicon), TSF451 (Toshiba Silicon), etc. In addition, decamethyltetrasiloxane, octamethyltrisiloxane, etc. may be used. In addition, as an aliphatic hydrocarbon solution, petroleum hydrocarbons such as cyclohexane, n-hexane, n-hebutane, n-octane, n-nonane, isooctane, isododecane, ligroin, and mixtures thereof (commercially available products manufactured by Exxon Chemical Co., Ltd. Isopar E, G, H, L, V, Shell Sol 71 manufactured by Shell Oil Co., Ltd., Solupesso 1501, etc.) are mentioned, and these are used by appropriately mixing them. To reduce the transfer agent, the carrier liquid should be less than 1Ocst, preferably 3Ocst.
cSt or less is preferable.

The liquid developer for electrostatic images according to the present invention is characterized in that the toner particles contain an olefin resin having a melt index of 25 to 700.

Here, the melt index value is a value measured at 160±0.4° C. under a load of 2.160±log.

By the way, the present inventors have determined that the image density in electrophotography,
As a result of various studies to improve resolution, fixing performance, set-off prevention, etc., we found that the melt index was between 25 and 700.
If this olefin resin is used as a binder for toner,
It has been found that the above objectives can be fully achieved. That is, polyolefin resin has a melt index NO0 of 25~
High molecular weight ones with a relatively high melt viscosity of 700 are
Colorants can be produced by kneading organic pigments and carbon black with this at high temperatures, so pigments such as carbon black can be mixed with 1
The secondary particles are dispersed, and therefore copies with high image density and glossy image areas can be obtained. In addition, since the toner does not flow during the fixing process, it is not only possible to obtain copies with excellent resolution and sharpness.
Copy fixing properties are also good. The present invention has been made based on these considerations.

To explain the present invention in more detail below, the olefin resins having a melt index of 25 to 700 used in the present invention include those having polar groups such as carboxyl groups, hydroxyl groups, glycidyl groups, and amino groups in their molecular chains; It has a partially crosslinked structure due to a crosslinking agent or a radical initiator. Melt index N of olefin resin
In order to obtain an O0 of 25 to 700, it is advantageous to, for example, copolymerize the polyolefin with a monomer having a polar group, add a crosslinking agent to give the polymer a crosslinked structure, or use a combination of these. .

Olefin resins with a melt index number of 25 to 700 have such a structure, so when they are used as toner particles together with pigments, the toner particles have good dispersibility and are dispersed in a carrier. When developed toner particles are dispersed in a liquid and enter a fixing process, rapid plasticity due to heat is less likely to occur. Therefore, it is difficult to fuse to the fixing roll. On the other hand, in a cooled and solidified state, the fixability increases due to the high molecular weight. Furthermore, since these toner particles are coated with a polar polymer, they have excellent development characteristics and transferability, resulting in high image density and improved resolution. If the melt index value is less than 25, the toner will have poor fluidity when heated, and if it is greater than 700, the toner will have too much fluidity when heated, resulting in poor sharpness and poor thermal rollability. The toner tends to fuse, making it impossible to achieve the object of the present invention.

In order to prepare a liquid developer for the developer of the present invention, 0.1 to 20 parts by weight of an olefinic resin having a melt index of 25 to 700, preferably 1 to 10 parts by weight, is added to 1 part by weight of the pigment as a dispersion medium (for example, a carrier). (preferably the same type as the liquid) 10
~100 parts by weight are dispersed in a dispersing machine such as a ball mill, Keday mill, or attritor to form a wet concentrated toner, which is then mixed with a high-resistance, low-resistance toner consisting of a mixed liquid of a fluorine-based solvent, an aliphatic hydrocarbon solvent, and/or a silicone-based solvent. It may be diluted with a carrier liquid having a dielectric constant.

Further, a thermoplastic resin and a polarity control agent may be added as necessary.

Specific examples of the olefin resin having a melt index of 25 to 700 used in the present invention are shown below. Note that the numerical values written in parentheses after the copolymers are the molar ratios of those polymer constituents.

(1) Ethylene-vinyl acetate-lauryl methacrylate copolymer (60/30/10) (2) Ethylene-vinyl acetate-methyl methacrylate dimethylaminoethyl methacrylate copolymer (50/30/10)
30/10/10) (3) Ethylene-vinyl acetate ethyl acrylate divinylbenzene copolymer (50/20/20/10)
(4) Ethylene-ethyl acrylate-phthalic anhydride copolymer (96/2/2) (5) Propylene-vinyl acetate-lauryl methacrylate copolymer (60/30/10) (6) Propylene-vinyl acetate-acrylic Acid copolymer (
60/9/31) (7) Ethylene-ethyl acrylate-maleic acid copolymer (95/2.5/2.5) (8) Ethylene-ethyl acrylate-acrylic acid copolymer (98/]/1) (9) Propylene-lauryl methacrylate-methacrylic acid copolymer (70/20/IQ) (10) Ethylene-acrylic acid-methylpropane triacrylate copolymer (80/1575) (11) Propylene-ethyl laurylate copolymer Polymer (50150) Some of these olefin resins with a melt index of 25 to 700 are commercially available, such as Evaflex A-701, A-702, A-703, A-704,
A-705, A-706, A-707, A-708, A
-709, A-710, N-410, N-035, N-
010, N-903, N-549, N-1214, N-
1525, N-925 (both manufactured by Mitsui Polychemical Co., Ltd.), and the like.

The colorants used in the present invention include furnace black, acetylene black, channel black as carbon black, and commercially available products as Printex G, Printex V, Special Black 15, Special Black 4, and Special Black 4-B (Degussa Co., Ltd.). manufactured by),
Mitsubishi #44, #30. MA-11. Inorganic pigments such as MA-100 (manufactured by Mitsubishi Carbon), Raven 30, Raven 40, Conductex SC (manufactured by Columbia Carbon), Zigal 400.660.800 Blackvar L (manufactured by Cabot), phthalocyanine blue, phthalocyanine green , Rhodamine Lake, Malachite Green Lake, Methyl Violet Lake, Peacock Blue Lake, Naphthol Green B1 Naphthol Green Y, Naphthol Yellow S Yurisole Fast Yellow 2G, Permanent Red 4R, Brilliant Firth Oskaret, Hansa Yellow, Benzidine Yellow, Rysol Red, Lake Red C, Lake Red D
, Brilliant Carmino 6B, Permanent Red F5
Examples include organic pigments such as Pigment Scarlet 3B and Bordeaux 10B.

In the present invention, within the scope of the purpose of the present invention,
Some of the olefin resins with a melt index of 25 to 700 can be used, for example, natural resin-modified carbonic acid resin, natural resin-modified maleic acid resin, dammar, kovar, shellac, gum rosin, hardened rosin, ester gum, glycerin ester-modified maleic acid resin, styrene. Butadiene resins, ethylene-vinyl acetate copolymers, polyolefins other than olefin resins with a melt index of 25 to 700, and copolymers with polyolefins (these generally have a molecular weight of about 5.000 or less and a melt index of NO 0).
1,000 or more), it is possible to partially replace it with wax or the like.

Examples of commercially available resins (including waxes) include the following.

Manufacturer Product name Softening point (℃) Union DYNI +02 Carbide (US) DYNF +02DYNH+02 DYNJ +02 DYNK +02 Monsando (US) 0RLIZON805 1
160RLIZON705 116 0RLIZON 50 126 Philips (USA) MARLEXI005 9
2 Dupont (USA) ALATHON 3 1
03 Allied Chemical (USA) Mitsubishi Rayon ALATHON 10 ALATHON +2 ALATHON 14 ALATHON 16 ALATHON 20 ALAT)ION 22 ALATHON 25 AC Polyethylene 1702 AC Polyethylene 617゜17A ^C Poly Ethylene 9,9A AC polyethylene 430 AC polyethylene 405 AC polyethylene 401 AC polyethylene 540 AC polyethylene 580 BR-30 BR-80 BR-90 BR-95 Nippon Gas Chemical Kodak Kouninari-Car BR-101 BR-102 BR-107 Nikanol HP-70 Nikanol HP-100 Nikanol HP-120 Epolene N-14 Epolene E-15 Sunwax 131-P Sunwax 151, P Sunwax +61-P Sunwax 165-P Sunwax 171-P Sunwax E-200 Sunwax E-300 Viscole 330-P Viscole 550-P Viscole TS-200 State Oil 5-WAX 5 Genuine Chemical Paraffin Wax
40-90 Hoechst PED 521 104 PED 543 110 Among these resins, ethylene-vinyl acetate copolymer (with a vinyl acetate content of 1.0 to 50% by weight, preferably 10 to 40% by weight), It is desirable to use one having a softening point in the range of 40 to 180°C, preferably 60 to 120°C. Commercial products of such ethylene-vinyl acetate copolymers are listed below.

(i) Product name of products manufactured by Mitsui DuPont Chemical Company
Vinyl acetate Softening point content (wt%) (℃) 694 198 33 120 885 890 28 135 8155 Evaflex 45 Evaflex 40 Evaflex 150 Evaflex 210 Evaflex 220 Evaflex 250 Evaflex 260 Evaflex 310 25 Evaflex 360 25 EVAFLEX 410 19 EVAFLEX 420 19 EVAFLEX 450 19 EVAFLEX 550 14 EVAFLEX P-104314 EVAFLEX P-120712 EVAFLEX P-06076 (il) Manufactured by Toso Corporation Product name Vinyl acetate softening point Ultrasen U E-63120 Ultrasen UE -63426 Ultrasen UE-63015 (iii) Made by Allied Chemical Co., Ltd. Product name
Vinyl acetate softening point 400 & 400A 4 402 & 402A 403 & 403A 14
106405 1
1 95430
26 60 (iv) Manufactured by Hoechst Product name Vinyl acetate Softening point content (wt%
) (℃) TEMREV720 25 102 (v
) Manufactured by BASF Product name Vinyl acetate Softening point content (wt%)
) (°C) In addition, a fluororesin can be added to the colorant to improve water repellency and oil repellency, thereby increasing offset resistance. As the fluororesin, MODEPA-200,2 manufactured by NOF Corporation is used.
Block copolymers of fluorine segments such as 10, 100, and 110 are preferred. The amount added is preferably 1 to 10% by weight based on the colorant.

By the way, a more desirable toner can be obtained by further containing humic acid, humic acid salts/or humic acid derivatives as toner constituents. In other words, if these humic acids are added to a toner together with an olefin resin with a melt index of 25 to 700, the pigment itself will not be dispersed due to its compatibility with other resins and its high melt viscosity when heated and mixed. Not only this, but also the dispersion and blending of the obtained colorant with other resins becomes easier. Humic acids are alkali-soluble amorphous polymeric organic acids contained in young coals such as peat and lignite. Humic acids are broadly classified into natural products and artificial products, and their industrial products are CH
There are two types: CHA type, CHN type, and acid type, and salt type such as Na, NH, etc., and any of them can be used in the present invention.

Since humic acid, humic acid salts and/or humic acid derivatives are well adsorbed to pigments, they are advantageous for finely dispersing pigments down to primary particles and for improving dispersion stability (long-term storage).

The liquid developer of the present invention mainly consists of a toner, at least a colorant, and an olefin resin with a melt index of 25 to 700, but more preferably, the colorant contains a pigment, an olefin resin with a melt index of 25 to 700, and the necessary It is produced by the flushing method by adding humic acids according to the conditions.

In these flushing methods, for example, a pigment water-containing liquid is well stirred in a kneader called a flasher together with a solution of an olefin resin having a melt index of 25 to 700 and a humic acid added as necessary. As a result, water existing around the pigment is replaced by an olefin resin solution having a melt index of 25 to 700. The water is discarded from the kneader, and the pigment dispersed in the olefin resin solution having a melt index of 25 to 700 is dried to remove the solvent and obtain a lump. Colorant powder is then obtained by crushing this mass.

Next, production examples of colorants and examples of the present invention will be shown.

Colorant production example 1 Water 500g Carbon black (Printex G) 150g Humic acid
Flasher a mixture consisting of 10g
After stirring well, add Evaflex A-70150.
0g of toluene and 500g of toluene were added to the flasher and kneaded. Subsequently, the mixture was heated and depressurized to remove water and solvent, thereby obtaining a mass of colorant having a volatile content of 1%. This was ground in a stone mill to obtain a powder of 1 to 5 μm.

Colorant Production Examples 2 to 7 Colorant powders in Production Examples 2 to 5 were produced in the same manner as in Production Example 1, except that only the raw materials were changed to those shown below, and in Production Examples 6 and 7, the flushing method was used. The colorant was produced by simply mixing without mixing.

Production example 2 Zigal 400 150 gN-1406
00g Evolen E-1450g Modepper 210 50g Nitrohumic acid 10g Triiron tetroxide 0g -0903 Benzoyl peroxide Mogul A -399 BH355 Copolymer of n-hexane alkaline blue specific example (4) Modepper-100 Divinylbenzene di-t-butyl Peroxide A-11 Copolymer of Specific Example (5) R-102 Copolymer of Toluene Phthalocyanine Blue Specific Example (1O) TSF4600 60'Og 10g 50g 00g 0g 00g 50g 00g 0g 0g 0g 50g 00g 0g 00g 50g 00g 00g FC-110 300g Examples 1 to 7 20 of each colored powder obtained in Colorant Production Examples 1 to 7
g was added to 100 g of Fluorinert FC-77 along with 50 g of lauryl methacrylate-acrylic acid copolymer resin (polymerization molar ratio 90:10), and milled with a ball mill to 72 g.
After kneading for a period of time to make a concentrated toner, 50g of this was mixed for 2Q.
A liquid developer was prepared by diluting it with Fluorinert FC-77.

When these seven types of liquid developers were used for copying with a commercially available electrophotographic copying machine (Coby CT-5085 manufactured by Ricoh Co., Ltd., heat roll fixing machine), the results shown in Table 2 below were obtained. Ta.

Table 2 As is clear from the above results, the developer of the present invention provides a temperature within the temperature range that allows hot roller fixation without an offset phenomenon, and has a high image attitude, high resolution, and high heat roller fixability. there were. Also, there was little odor from the copying machine.

[Effect 1] By using the developer of the present invention, it is possible to perform hot roll fixing without applying oil to the fixing roll and without causing an offset phenomenon, allowing a compact copying machine to achieve high speed and constant fixation with low energy. It has become possible. Additionally, the amount of hydrocarbon gases generated by copying machines has also been reduced.

Claims (2)

[Claims] (1) Toner particles made of a colorant and resin are dispersed in a carrier liquid of high resistance and low dielectric constant made of a mixed liquid of a fluorine-based solvent, an aliphatic hydrocarbon solvent, and/or a silicone-based solvent. A liquid developer for electrostatic images, characterized in that the resin component contains an olefin resin having a melt index of 25 to 700. (2) The liquid developer for electrostatic images according to claim 1, wherein the developer contains a colorant, and the colorant is produced by using a pigment and an olefin resin having a melt index of 25 to 700.