JPH03225361A - Liquid developer for electrostatic charge image - Google Patents

Abstract

PURPOSE:To decrease the smells based on hydrocarbon components and to eliminate the need for application of oil on a fixing roll by using a carrier liquid essentially consisting of a silicone solvent and an olefin resin having a specified melt index. CONSTITUTION:This developer is formed by dispersing the toner particles consisting of coloring agents and a resin into the carrier liquid essentially consisting of the silicone solvent and having a high resistance and low dielectric constant. An olefin resin having 25 to 700 melt index (e.g.: an ethylene/vinyl acetate/lauryl methacrylate copolymer) is used as the above-mentioned resin. The powder obtd. by kneading the dispersion of desired pigments with the above-mentioned olefin resin and drying an grinding the mixture is preferably used as the above-mentioned coloring agents.

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 1 of the present invention] An object of the present invention is to reduce hydrocarbon solvent gas generated from copying machines. In addition, in hot roll fixing devices that use liquid developer, it is possible to remove the oil application device to the fixing roll, save the trouble of supplying oil, and furthermore, by mixing a certain proportion of nonflammable liquid, it is possible to prevent flammability. The purpose is to reduce the risks such as (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 silicone solvent as a carrier liquid. The silicone solvent used in the present invention includes KF
96 (Shin-Etsu Silicon), 5H200, 5H344 (Toshi Silicon), TSF451 (Toshiba Silicon), etc. In addition, decamethyltetrasiloxane, octamethyltrisiloxane, etc. may be used. In addition, as aliphatic hydrocarbon solutions, cyclohexane, n-hexane,
Petroleum hydrocarbons such as n-hebutane, n-octane, n-nonane, isooctane, isododecane, ligroin, and mixtures thereof (commercially available products such as Exxon Chemical's Isopar E, G, H, L, V, and Shell Examples include Shellsol 71 and Solupesso 150 (manufactured by Sekiyu Co., Ltd.), and these may be used by appropriately mixing them. To reduce transfer agent, the carrier liquid should be less than 10 cSt, preferably 3 cSt.
St 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 No. of 25 or more.
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
o, of 25 to 700, it is advantageous to 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. be. 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 on the other hand, if it is greater than 700, the toner will have too much fluidity when heated, resulting in poor sharpness. In both cases, the toner becomes more likely to fuse, making it impossible to achieve the objective H of the present invention. 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 (e.g., a carrier). (preferably the same type as the liquid) 10
A wet concentrated toner may be obtained by dispersing with ~100 parts by weight in a dispersing machine such as a ball mill, kedimir, or attritor, and this may be diluted with a high resistance, low dielectric constant carrier liquid containing a silicone solvent as a main component. Furthermore, a thermoplastic resin or a polar swelling 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
/30/10/10) (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 (98haha) (9) Propylene-lauryl methacrylate-methacrylic acid copolymer (70/20/10) (10) Ethylene-acrylic acid-methylpropane triacrylate copolymer (80/1515) (11) Propylene-ethyl laurylate copolymer (50150) Some of these olefin resins with a melt index of 25 to 700 are commercially available, such as EVA 7L/'
/Cus A-701, A-702, 8-703, A-70
4, 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 (all 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 V1 Special Black 15, Special Black 4, and Special Black 4-B (manufactured by Degussa). ),
Mitsubishi #44, #30, MA-11, MA-100 (manufactured by Mitsubishi Carbon), Raven 30, Seaben 40. Inorganic pigments such as Conductex SC (manufactured by Columbia Carbon), Regal 400.660.800 Black Pearl L (manufactured by Cabot), phthalocyanine blue, phthalocyanine green, rhodamine lake, malachite green lake, methyl violet lake, peacock blue lake, naphthol. Green B, Naphthol Green Y, Naphthol Yellow S1, Lysol First Yellow 2G, Permanent Red 4R, Brilliant Firth Oscaret, Hansa Yellow, Benzidine Yellow, Lysol Red, Lake Red C, Lake Red D
1 Brilliant Carmine 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, copal, 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 ('C) Union DYNI 102 Carbide (US) DYNF +02D Y N H10
2 DYNJ 102 DYNK 102 Monsanto (USA) 0RLIZON805
1160R1jZON705 116 0RLIZON 50 126 Philips (USA) MARLEXI005 9
2 Dupont (USA) ALATHON 3 1
03 ALATI (ON 10 96 ALATHON 12 84 ALATHON 14 80 ALATHON +6 95 ALATHON 20 86 ALATHON 22 84 ALATI (ON 25 96) Allied Chemical (US) Mitsubishi Rayon Nippon Gas Chemical Kodak AC Polyethylene 1702 AC Polyethylene 617° 17A AC Polyethylene 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 BR-101 BR-102 BR-107 Nicanol HP-70 Nicanol HP-100 Nicanol HP-120 Epolene N-14 5 Kochu Kasei Evolen E-1596 Sunwax 131-P 108 Sunwax 151-P 107 Sunwax 161-P
111 Sunwax 165-P 10
7 Sunwax 171-P 105 Sunwax E-200102 Sunwax E-30098 Viscole 330-P 152 Viscole
550-P 150 Viscoll TS-200
145 Kuker State Oy) Lt QS-WAX 65
Genuine chemical paraffin wax
40-90 Hoechst PED 52
1 104PED 543 1
10 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, and a softening point of 40 to 180°C, preferably is in the range of 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%) (℃) Evaflex 45 46 94 Evaflex 40 41 98 Evaflex 1
50 33 120 Everflex 210
28 85 Everflex 220
28 90 Everflex 250 28
+35 Everflex 260 28
155 Everflex 310 25
90 Everflex 360 25 18
5 Everflex 410 19 90 Everflex 420 19 +00 Everflex 450 19 135 Everflex 550 14 170 Everflex P-10431470 Everflex P-120712 Everflex P-06076 (u) Made by Toso Product name Vinyl acetate content (wt%) Ultrasen UE-63120 Ultrasen UE-63426 Ultrasen UE-63015 (m) Manufactured by Allied Chemical Company Name Vinyl acetate content (wt%) 400 & 400A! 4402 &
402A 2403 & 403A
14405 11 430 26 (1v) Manufactured by Hoechst Product name Vinyl acetate content (wt%) TEMREV720 25 0 2 Softening point (°C) 2 1 7 Softening point (°C) +02 (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 1-10% 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 flashing methods, for example, a pigment water-containing liquid is thoroughly 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 has a melt index of 25 to 7.
00 olefin resin solution. 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 of Production Examples 2 to 5 were produced in the same manner as in Production Example 1, except that only the raw materials were changed from those shown in Table 1.
The colorants of Production Examples 6 and 7 were produced by simply mixing without using the flushing method. 2. Zigal 400 150 gN-
140600g Evolen E-1450g Modepper 210 50g Nitrohumic acid 10g3, triiron tetroxide
70gN-0903600g Benzoyl peroxide lOg Mogul A
150g N-599600g BR85550g n-hexane 5, alkali blue copolymer modepa-100 of specific example (4) divinylbenzene 00g 50g 00g 0g 0g 6°7° di-butyl peroxide 10g MA-11150g specific example (5) Copolymer 600g BR-10250g Toluene 600g Phthalocyanine Blue 150g Copolymer of Specific Example (10)
600gTSF4600 300gKF-
96300g Examples 1 to 7 20 of each colored powder obtained in Colorant Production Examples 1 to 7
g was added to 100 g of KF96 (manufactured by Shin-Etsu Silicone Co., Ltd., viscosity 3 cSt) together with 50 g of lauryl methacrylate-acrylic acid copolymer resin (polymerization molar ratio 90:10),
After kneading in a ball mill for 72 hours to obtain a concentrated toner, 50 g of this was diluted with 2Q KF96 to prepare a liquid developer. 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. . 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] 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, and it is possible to perform high-speed and low-energy constant fixing in a compact copying machine. It has become possible. Additionally, the amount of hydrocarbon gases generated by copying machines has also been reduced.

Claims (2)

[Claims] (1) In a liquid developer for electrostatic images, in which toner particles made of a colorant and a resin are dispersed in a high-resistance, low-dielectric-constant carrier liquid containing a silicone solvent as the main component, melt is used as the resin component. A liquid developer for electrostatic images, characterized by containing an olefin resin having an 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.