JPS59160153A - Electrostatic photographic liquid developer - Google Patents

Abstract

PURPOSE:To obtain a liquid developer capable of forming an image high in density and quality by dispersing a toner composed essentially of a pigment and a specified resin in a liquid carrier. CONSTITUTION:The toner for use in an electrostatic photographic liquid developer to be dispersed into a liquid carrier is composed essentially of a pigment, such as phthalocyanine blue or Bordeaux 10B, and a copolymer resin of a monomer A of formula I and at least one of monomers B of formulae II-VI in which X is H or methyl; R is 6-20C alkyl and Y is COOH or CH2COOH. The monomer A is soluble in the liquid carrier and capable of dissolving the monomer B, and the monomer B has a carboxylic group. Said copolymer resin is obtained by heat polymerizing the monomers A, B. The toner contains a base, such as methylamine or systeine, in an amt. of 0.05-1.0g per 100g of said resin. As the liquid carrier, petroleum derived aliphatic hydrocarbons and perchloroethylene, etc. high in insulating property and low in dielectric constant are used.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a liquid developer for electrostatography, and particularly to a highly charged liquid developer for transfer type copying machines with excellent dispersion stability and transferability.

BACKGROUND ART In general, a liquid developer for electrostatography consists of (1) a pigment that is dispersed in a dispersion medium and moves to the image surface of the electrostatic tank by electrophoresis under the influence of the image tm to form a visible image; (2) a dispersion medium. (3) A low-conductivity carrier liquid that transports the pigment particles near the latent image surface so that they are within the effective range of the image electric field; (4) a pigment coating that adsorbs or coats onto the surface of pigment particles to change the chargeability of the particles or provide fixation of the pigment particles to the support after development; and (5) a charge control agent for adjusting the stability of pigment particles.

Conventionally, this type of liquid developer has been prepared by coating dyes, thermoplastic resins, rubbers, etc. on pigments such as Chikarazen Black, and then using dispersion stabilizers such as alkyd resins and acrylic resins. A toner obtained by adding a polymer compound such as a copolymer resin and further adding an organic acid metal salt such as naphthenic acid salt as a charge 1 control agent is used as a carrier liquid 1 (a dispersion is known). .

However, conventional liquid developers (a) have poor redispersibility even if they have good dispersion stability, and toner sediment accumulates in the developer tank, causing spot-like abnormal images; (b) high-speed printing Since the density of toner particles is low, the toner adhesion band on the photoreceptor drum is insufficient, resulting in a decrease in image density and color-free property, as well as smearing and bleeding.(c) Conductivity of the carrier liquid The rate is regulated by the conductivity of the resin, but if the conductivity is high, the image density will decrease, and if the conductivity is low, the image density will be reduced by the Gino 9-thrower (a device for removing excess developed toner) and the scraper in contact with it. This has the disadvantage that a friction zone N1 is formed between the rollers and the toner particles are affected, resulting in abnormal images.

Regarding (b), a method of increasing the toner particle size may be considered, but on the other hand, good resolution and gradation cannot be obtained.

Purpose An object of the present invention is to control the electrical conductivity of the carrier liquid within an appropriate range, and toner particles that generate a high charge to provide high concentration,
Our goal is to provide a liquid developer that can produce high-quality images.

Structure: In an electrostatic photographic liquid developer prepared by dispersing a toner mainly composed of pigment and resin in a carrier liquid having high insulating properties and low dielectric constant, 1, the resin has the following general formula (wherein, , -CH3, R is 0nH2r+
++ t 6≦n≦20) (hereinafter referred to as monomer A) and the following general formula % formula % (2 (in these formulas, X represents H, -0Hs, Y is -0
00)], , -"represents 0H2000H) (hereinafter referred to as Nanatsumer-B). It is characterized by this.

Monomer A is a vinyl monomer that is soluble in a nonpolar solvent (carrier liquid) and can dissolve monomer B. Examples of this monomer include n-hexyl acrylate, n-hexyl methacrylate, n-hebutyl acrylate, 2-ethylhexyl methacrylate, lauryl acrylate, lauryl methacrylate, dodecyl methacrylate, dodecyl acrylate, stearyl acrylate, stearyl methacrylate, etc. .

Monomer B is a carboxyl group-containing vinyl monomer (acid monomer), and includes acrylic acid, methacrylic acid, itaconic acid (anhydride), maleic acid (anhydride), fumaric acid, vinylbenzoic acid, cinnamic acid, crotonic acid, etc. Can be mentioned.

Ku to obtain a resin with these monomers, monomer A
and B may be thermally polymerized in the presence of a polymerization initiator such as benzoyl peroxide or lauroyl peroxide.

Note that, as long as Monomer A is contained in the resin in an amount of 30 mol 4 or more, the object of the present invention can also be achieved with a copolymer of Monomer A and other vinyl monomers copolymerized. Other vinyl monomers include styrene or its derivatives (chlorostyrene, butylstyrene, etc.), vinyltoluene, vinyl acetate, acrylonitrile, methacrylonitrile and the like. If monomer A is 30 mot% or more, the uniform will be sufficiently dissolved in the non-aqueous solvent, but when copolymerizing completely insoluble monomers such as methyl methacrylate and styrene, monomer A is 50 ma
It is preferable to set it to 1% or more.

The toner is mainly composed of the above-mentioned resin and the pigment described below, and in the present invention, a base is added to the toner in order to make the toner generate a sufficient amount of charge. In a liquid developer, since the Se photoreceptor drum is charged with a positive potential, the toner particles must be negatively charged. In order to obtain negatively charged toner particles, it is preferable to use a resin containing a cardaxyl group, such as 0H3000H-+ in an aqueous solvent.
0H3000+H" ノ, 1: Sea urchin ionizes. However,
Since it is difficult to ionize in a non-aqueous solvent, sufficient charge cannot be generated. Therefore, if a base that acts as a proton acceptor is added, ionization will be promoted and the amount of charge on the toner particles will increase.

In this way, the amount of η charge generated by the toner is greatly influenced by the dielectric constant of the resin, the dissociation constant of the acid monomer, and the dissociation constant of the total 7 bases, but the conductivity of the liquid developer is 2 Since the conductivity of the base-added toner is preferably from IX10" to IX10=S arm-'
It is desirable to do so. The amount of base added should be determined so as to satisfy this condition, and usually 100g of resin
It is in the range of 0.052 to 1.02 per unit. If the amount is too small, the necessary conductivity of the toner cannot be obtained, and if the amount is too large, the image density will decrease and the running characteristics will deteriorate.

Examples of the base include 2-aminoethanol, jetanolamine, triethanolamine, ethylamine, diethylamine, triethylamine, ethylenediamine, cyclohexylamine, tris(hydroxymethyl)methylamine, butylamine, 16-hexanediamine, hexylamine, diethylamine, methylamine, Dimethylamine, trimethylamine, aniline, chloroaniline,
Dinitroaniline, dimethylaniline, nitroaniline, methylaniline, benzylamine, methylbenzylamine, chrysin, imidazole, pygyridyl, pyridine, aminopyridine, dimethylpyridine, trimethylpyridine, methylpyridine, pyridoxine, pyrrolidine, piperazine, piperidine, benzo imidazole, purine,
Examples include cysteine and the like.

Examples of carbon black and organic pigments used in the present invention include the following. As carbon black, furnace black, acetylene black, channel black, etc. can all be used, and commercially available products include Printex G1 Special i Rack 15, Special Black 4, Special Black 4-B (Texa M), Mitsubishi≠44, Temple 30, MA711
, MA-100 (manufactured by Mitsubishi Carbon), Raven 30° Raven 40, Conductex So (manufactured by Columbia Kazen), Regal s 00° 400
．． 600 and Black Knoll L (manufactured by Casette) are known.

Examples of organic pigments include phthalocyanine sol, phthalocyanine green, sky blue, rhodamine lake, malachite green lake, methyl ζ iolet lake,
Peacock Sol-Lake, Naf) = Le Clean B1 Naphthol Clean Y2 Naphthol Yellow 81 Lysol F-St Yellow 2G1 Nogichi Manfu Trend 4
R, Brilliant Fast Scarlet, Hansa Yellow, Vengeshiie 0-1 Linur Red, Lake Red C5 Lake Reid D5 Brilliant Carbon 6B,
Nozo-Manent Red F5 R, Pigment Scarlet 3. B and Zeldor 10B.

In the present invention, polyolefins, copolymer resins with polyolefins, waxes, etc. can also be used, and commercially available products include the following.

Union Power - Noguid eli DYNI
102DYNF
Io2DYNH102 DYNJ 102I)YN
K 102 Monsando (US) OR, LIZON 805 116705
116 50 126 Phillips (US), MARLEX 1005
92 Du Pont (USA) ALATI-1ON
-3103 Manufacturer Product name Softening point ('C
) DuPont (USA) ALATHON 10 96
12 84 14 80 16 95 20 86 22 84 25 96 Allied Chemical (USA) AC Polyethylene 1702
85617.617A 102 9, 9A 117 430 60 405 96 401 102 540 10B 580 1.08 Sanyo Kasei Sunwax 131-P
108151-P 107 161-P 111 165-P 107 171-P 105 To make a liquid image agent, resin, pigment, and wax are mixed in the presence of a petroleum-based aliphatic hydrocarbon or halogenated aliphatic hydrocarbon solvent. The toner may be sufficiently dispersed using a dispersion method such as a Zeel mill, a motion mill, a sand mill, an attritor, etc. to form a concentrated toner, and then the toner may be diluted with a similar solvent (carrier liquid). At this time, the face f4/resin has a cross circulation ratio of 10.1~115o, and the pigment/wax has a mold agent ratio of 110~J150.
It is desirable that it be within the range of .

Carrier liquids include petroleum-based aliphatic hydrocarbons with high insulation properties (electrical resistance of 10ΩG or more) and low dielectric constants (dielectric constant of 3'F or more), n-hexane, ligroin, n-hebutane, n-pentane, isododecane. , isooctane, etc., as well as their halogen derivatives, such as carbon tetrachloride, .--chloroethylene, etc. Incidentally, the commercially available petroleum aliphatic hydrocarbons include Isopar E5, Itsunomy 01 Aituno-L, Isopar 1-1, and Isopar 1-1 manufactured by Exxon.
Isopar includes 1 Naphtha Black 6, Tsurpez 100, etc. These may be used alone or in combination.

Example 1 <Resin A> 11 reflux, 150 in a 4 flask with tJa
-() (manufactured by Exxon) 2 (prepare l Or)
, OO'C'f, and N2 gas was blown into the flask to make the flask atmosphere inert. Among these, lauryl methacrylate (LMA)
100 n-butyl methacrylate (n-BM
A) 20 f2-ethylhexyl methacrylate (2-EHMA) 3or stearyl methacrylate (BMA) 4
5r acrylic acid 52 benzoyl peroxide (BPO)! M' was added dropwise over 1 hour, and the polymerization reaction was completed 5 hours after dropping. The polymerization rate at this time was 950%, and the viscosity was 5.
00 cp (20°C).

<Developer A> Carzen Black (Carbon Black 4 = 44 Mitsubishi Kasei M) 9. oy polypropylene (manufactured by Sanyo Chemical Co., Ltd.)
5. Of Phthalocyanine Green LL < Sanyo Shikisha jJl 0.1 Above Resin A
7 (1 alkaline blue
0.1L? Triethylamine (base)
0111SO-0 (manufactured by Exxon)
3505' was dispersed in a small Zeal Mill 1 (12 hours at 15 to 20°C to obtain a concentrated toner. This was further added to 150-G200 and dispersed for 1 hour to obtain cross-agent A).

Example 2 <Resin B> 180-G containing resin was made into Isopar I ((300r),
Further, Resin B was synthesized in the same manner except that the reaction composition was changed to the following.

SMA
150f chrycidyl methacrylate) (GMA)
20F Acrylic Acid IBM' Methyl Methacrylate (MMA) x
sr lauroyl peroxide (LPO)
The polymerization rate with 8P was 97.0, and the viscosity was 12
00cp (20°C).

Developer B> Carzen Black (Mogal A) 9.
(H'P-ethylene (320MP, manufactured by Mitsui Oil Co., Ltd.)
302 Fukuro Cyanine Green C Mountain M Shikisha fJ! ,
] 0.3 SF Alkali Sol-012 Said Resin B 70f2-ethanolamine (base), 0.05F triethylamine (base) 0.0iI
SO-0300? Diluted l5O-0200F was dispersed in the same manner as developer A to obtain developer B.

The results of measuring the electrical conductivity of Developers A and B are shown in the table below. The table below also shows the results of copying using each of the 'Q and I components using a wet high-speed copying machine (DT-5300 manufactured by Ricoh). For comparison, the results obtained when the base was removed from Developers A and B are also shown.

Effects As is clear from the above evaluations, by using the developer of the present invention, good image quality with high image density can be obtained, and the image quality is not affected by the smoothness of the paper and deterioration in image quality is small even with repeated copying.

Claims (1)

[Scope of Claims] 1. In an electrostatic photographic liquid developer in which a toner mainly composed of pigment and resin is dispersed in a carrier liquid having high insulating property and low dielectric constant, the resin has the following general formula: (In the formula, X represents H, -0H3, R is -On HH
l + + (6≦n≦20). ) A monomer represented by the following general formula (in these formulas, X represents H, -OH, and Y represents 1000) (, -0H2000H). 1. A liquid developer for electrostatic photography, characterized in that the toner contains a base, using a copolymer obtained by polymerizing the same.