JPS6311951A - Electrophotographic binder resin - Google Patents

Abstract

PURPOSE:To easily and inexpensively produce a toner having excellent fixability and offset preventiveness by incorporating 5-50wt% acetone insoluble compo nent into the toner and specifying the weight average mol.,wt. of the soluble component to <=70,000. CONSTITUTION:The acetone insoluble component is incorporated at 5-50wt%, more preferably 10-30wt.% into the resin. The offset resistance of the toner is not enough if the content thereof is <5wt% and the fixability is not enough if the content exceeds 50wt%. The weight average mol.wt. of the soluble compo nent is preferably <=70,000, more particularly preferably <=50,000. The fixability of the toner is not enough when said mol. wt. exceeds 70,000. A vinyl polymer in which styrene is polymerized at 60-90wt% is preferably used as the resin. The fixability and offset preventiveness are thereby simultaneously attained.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a binder resin for toner for developing electrostatic latent images in electrophotography, electrostatic recording, etc. Methods for developing electrostatic latent images are broadly classified into liquid development methods and dry development methods, and the present invention relates to a binder resin for toner used in the dry development method.

Methods for fixing the developed toner image on a support such as paper include a heat roll method, a flash method, a high frequency heating method, an oven method, a method that uses heat, a method that uses a pressure roll, a method that uses an organic solvent, etc. It has been known. The present invention particularly relates to a binder resin for a toner used in a hot roll fixing system.

(Prior Art) Recently, the thermal roll fixing method is most commonly used in electrophotographic copying machines because it has good thermal efficiency, excellent fixing properties, produces good images, and can be made compact. There is. In particular, for high-speed fixing, a hot roll fixing method is generally used. However, in this fixing method, the toner is softened by heating and becomes sticky, so that a so-called offset phenomenon occurs in which a portion of the toner adheres to the surface of the hot roll.

Conventionally, fixing devices, fixing methods, etc. have been devised in order to prevent this offset phenomenon. For example, as a fixing device, a method is used in which the surface of a heat roll is formed of a material with excellent mold releasability, such as a fluorine-based resin, and the surface is further coated with an anti-offset liquid such as silicone oil. Although this method is extremely effective in preventing the offset phenomenon, the anti-offset liquid is heated and deteriorates, producing a strange odor, and requires a device to supply the anti-offset liquid. The drawbacks are that the copying machine is large in size, the mechanism of the copying machine is complicated, and high precision is required to ensure stability, making it expensive. For this reason, methods are being considered to prevent the offset phenomenon by not requiring any offset prevention liquid or by using only a small amount that does not pose a problem in supplying the liquid. For example, Japanese Patent Application Laid-Open No. 49-65231 describes that the offset phenomenon can be prevented by incorporating a small amount of low molecular weight polypropylene into the toner.

In addition, various studies have been conducted on binders for toner. For example, Japanese Patent Publication No. 51-23354 describes a method using a crosslinkable polymer as a binder resin. Furthermore, Japanese Patent Application Laid-Open No. 50-13465234652 describes a method of using a resin having a large amount distribution as a binder.

Also, JP-A-58-68752, JP-A-58-1
Publication No. 02246 describes a method in which a vinyl polymer obtained by graft copolymerizing a modified epoxy resin having a vinyl group and a polyester resin having a vinyl group is used as a binder.

This method is also effective in preventing the offset phenomenon.

(Problems to be Solved by the Invention) However, when low molecular weight polypropylene is used as an anti-offset agent, the toner tends to become non-uniform, causing fogging and scattering, so it is preferable to limit its use to as little as possible. . Furthermore, when a crosslinkable polymer or a graft copolymer is used, the fixing properties are generally inferior, and this tendency becomes more pronounced especially when fixing is performed at a high speed.

The method of using a resin with a large molecular weight distribution is an excellent method for simultaneously achieving fixing properties and offset prevention.
It is generally not easy to produce such resins;
There is a problem that it is less economical.

Therefore, an object of the present invention is to solve the problems of the prior art and to easily and inexpensively produce a toner that has excellent fixing properties and also has excellent anti-offset properties in a hot roll fixing method. shall be.

(Means for Solving the Problems) The present invention provides an electrophotographic toner containing 5 to 50% by weight of an acetone-insoluble component and having a polymerization average molecular weight of 70,000 or less for the soluble component. Regarding binder resin.

In the present invention, the acetone insoluble content is 5 to 50% in the resin.
% by weight, preferably 10-30% by weight. If the acetone-insoluble content is less than 5% by weight, the offset resistance of the toner will be insufficient, and if it exceeds 50% by weight, the fixing properties will be insufficient.

In this specification, the acetone-insoluble content means what is measured by the following method.

Approximately 1.0 g of resin is weighed out, and about 50 g of A7Tone is added thereto, and the mixture is allowed to stand at 20° C. for 24 hours. This is the JIs standard (p
3801) Pass through the mouth at normal pressure using a Type 5 C quantitative slipper. Subsequently, the mouth residue was washed with about 30 g of acetone, heated at 130° C. for 2 hours, and its weight was weighed. The ratio of the resin used to the mouth residue is defined as the insoluble content.

The acetone solution of the soluble component obtained here is concentrated, and the molecular weight is measured by gel permeation chromatography using a standard polystyrene calibration curve.

In the present invention, the weight average molecular weight of the soluble component is 7000
It is preferably 0 or less, particularly 50,000 or less. If the weight average molecular weight exceeds 70,000, the fixing properties of the toner will be insufficient.

In the present invention, it is preferable to use a vinyl polymer containing 50 to 100% by weight, preferably 60 to 90% by weight of styrene as the resin.

If the amount of styrene copolymerized is less than 50% by weight, the toner will have poor heat melting properties, resulting in insufficient fixing properties.

In the present invention, vinyl monomers other than styrene include α-methylstyrene, p-methylstyrene, p-
Styrene derivatives such as tert-7' tylstyrene and p-chlorostyrene, methacrylic acid, methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, pentyl methacrylate, hexyl methacrylate, heptyl methacrylate, octyl methacrylate, Nonyl methacrylate, decyl methacrylate, undecyl methacrylate, dodecyl methacrylate, glycidyl methacrylate, methoxyethyl methacrylate, propoxyethyl methacrylate, butoxyethyl methacrylate, methoxydiethylene glycol methacrylate, ethoxydiethylene glycol methacrylate, methoxyethylene glycol methacrylate , butoxytriethylene glycol methacrylate, methoxydipropylene glycol methacrylate, phenoxyethyl methacrylate, phenoxydiethylene glycol methacrylate, phenoxytetraethylene glycol methacrylate, benzyl methacrylate, cyclohexyl methacrylate, tetrahydrofurfuryl methacrylate, dicyclo methacrylate pentenyl,
dicyclopentenyloxyethyl methacrylate, N-hinyl-2-pyrrolidone methacrylate, methacrylateryl, methacrylamide, N-methylolmethacrylamide, 2-hydroxyethyl methacrylate, hydroxypropyl methacrylate, hydroxybutyl methacrylate,
2-hydroxy-3-phenyloxypropyl methacrylate, diacetone acrylamide, acrylic acid, methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, pentyl acrylate, hexyl acrylate, heptyl acrylate, acrylic acid octyl,
Nonyl acrylate, decyl acrylate, undecyl acrylate, dodecyl acrylate, glycidyl acrylate,
Methoxyethyl acrylate, propoxyethyl acrylate, butoxyethyl acrylate, methoxydiethylene glycol acrylate, ethoxydiethylene glycol acrylate, methoxyethylene glycol acrylate, butoxytriethylene glycol acrylate, methoxydipropylene glycol acrylate, phenoxyethyl acrylate, Phenoxydiethylene glycol acrylate, phenoxytetraethylene glycol acrylate, benzyl acrylate, cyclohexyl acrylate, tetrahydrofurfuryl acrylate, dicyclopentenyl acrylate, dicyclopentenyloxyethyl acrylate,
N-vinyl-2-pyrrolidone acrylate, hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxybutyl acrylate, 2-hydroxy-acrylate
3-phenyloxypropyl, glycidyl acrylate,
Vinyl monomers having one vinyl group in each molecule, such as acrylonitrile, acrylamide, N-methylol acrylamide, diacetone acrylamide, and vinyl pyridine, are used as the main component, but in addition, divinylbenzene, glycol, methacrylic acid, or acrylic acid are used. reaction products, such as ethylene glycol dimethacrylate, l.

3-butylene gelicol dimethacrylate, 1゜4-butanediol dimethacrylate, 1,5-pentanediol dimethacrylate), 1,6-hexanethiol dimethacrylate, neopentyl glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol Dimethacrylate, polyethylene glycol dimethacrylate, tripropylene glycol dimethacrylate, hydroxypivalic acid neopentyl glycol ester dimethacrylate: J-rate, trimethylolethane trimethacrylate, trimethylolpropane trimethacrylate, pentaerydrift trimethacrylate, pentaerythritol tetramethacrylate , tris methacryloyloxyethyl phosphate, bis(methacryloyloxyethyl) hydroxyethyl isocyanurate, tris(methacryloyloxyethyl) isocyanurate, ethylene glycol diacrylate, 1゜3-butylene glycol diacrylate, 1,4-butanediol diacrylate, 1.5-pentanediol diacrylate, 1.6-hexanediol diacrylate,
Neopentyl glycol diacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, polyethylene glycol diacrylate,
Tripropylene glycol diacrylate, hydroxypivalic acid neopentyl glycol diacrylate, trimethylolethane triacrylate, trimethylolpropane triacrylate, pentaerydrift triacrylate, pentaerydrift tetraacrylate,
Tris acryloxyethyl phosphate, bis(methacryloyloxyethyl) hydroxyethyl isocyanurate, tris(methacryloyloxyethyl) isocyanurate, half ester of glycidyl methacrylate and methacrylic acid or acrylic acid, bisphenol type epoxy resin and methacrylic acid or acrylic acid It is also possible to use vinyl monomers having two or more vinyl groups in one molecule, such as half-esterified products of glycidyl acrylate and methacrylic acid or acrylic acid.

Among these, preferred vinyl monomers having one vinyl group in one molecule include styrene, styrene derivatives, methacrylic esters, acrylic esters, etc. In particular, styrene and alkyl groups with 1 to 5 Preferred are alkyl esters of methacrylic acid or acrylic acid having 5 carbon atoms. 2 in 1 molecule
Among the vinyl monomers having at least 3 vinyl groups, divinylbenzene, dimethacrylates and diacrylates of methylene glycol having 2 to 6 carbon atoms, and the like are preferred.

These monomers are blended so that the total amount is 100% by weight. Among these, two or more nohinyl M' in one molecule
The amount of vinyl monomer having c is preferably 0.1 to 1% by weight. The amount of acetone insoluble matter can be adjusted by adjusting the amount of vinyl monomer used.

The above monomer or monomer mixture can be polymerized by any method such as suspension polymerization, solution polymerization, emulsion polymerization, or bulk polymerization.

The above monomer or monomer mixture may include benzoyl peroxide,
2-ethylhexyl perbenzoate, lauroyl peroxide, acetyl peroxide, isobutyryl peroxide, octanoyl peroxide, tert-butyl peroxide, tert
-butyl peroxide, cumene hydroperoxide, methyl ethyl ketone peroxide, 4,4.6-)limethylcyclohexanone di-tert-butyl peroxykecour, cyclohexanone peroxide, methylcyclohexanone peroxide, acetylacetone peroxide, cyclohexanone di-tert-butyl peroxykecour, Peroxide radical initiators such as 2-octanone di-tert-butyl peroxyketal, acetone di-tert-butyl peroxyketal, diisopropylbenzene hydroperoxide, 2°2'-azobisisobutyronitrile, 2.2°-azobis( 2,4-
dimethylvaleronitrile), 2,2'-azobis(4-
methoxy-2,4-dimethylvaleronitrile), 2.2
”-dimethyl azobisisobutyrate, 1.1°-azobis(
Radical polymerization is carried out using an azobis radical initiator such as cyclohexane-1-carbonitrile).

In the polymerization of vinyl monomers in the present invention, butyl mercaptan, octyl mercaptan, dodecyl mercaptan, methyl 2-mercaptopropionate, ethyl 2-mercaptan,
Mercaptopropionate, butyl 2-mercaptopropionate, octyl 2-mercaptopropionate,
Mercaptans such as pentaerythritol tetra(2-mercaptopropionate), ethylene glycol di(2-mercaptopropionate), glycerin tri(2-mercaptopropionate), chloroform, bromoform, carbon tetrabromide, etc. Radical polymerization molecular weight modifiers such as halogenated hydrocarbons can be used. These molecular weight regulators are used in an amount of 0 to 3% by weight based on the vinyl monomer.

When carrying out aqueous suspension polymerization, partially saponified polyvinyl alcohol, alkylcellulose, hydroxy-alkylcellulose, carpoxyalkylcellulose, polyacrylamide, polyvinylpyrrolidone, polyacrylic acid and its alkali metal salts, polymethacrylic acid and its Water-soluble polymer dispersants such as alkali metal salts, sparingly soluble inorganic dispersants such as calcium phosphate, hydroxyapatite, magnesium phosphate, magnesium pyrophosphate, calcium carbonate, barium sulfate, and hydrophobic silica can be used.

The resin in the present invention is preferably produced by aqueous suspension polymerization from the viewpoint of economy, stability during production, and the like.

The resin in the present invention can be melt-mixed with a colorant and/or magnetic powder, and if necessary, a charge control agent and other additives to form a toner.

Coloring agents include carbon black, iron oxide pigment, phthalocyanine blue, phthalocyanine green, rhodamine 6G lake, watching red strontium, etc.
Conventionally known toners can be used, including toners 91 to 6.
It is appropriately selected and used within the range of 0% by weight.

Examples of magnetic powder include fine metal powders such as iron, manganese, nickel, and cobalt, and ferrites such as iron, manganese, nickel, cobalt, and zinc, with an average particle size of 10μ.
It is preferably 1 μm or less, particularly 1 μm or less, and is usually used in the toner in an amount of 0 to 70% by weight.

As the charge control agent, nigrosine dyes, fatty acid-modified nigrosine dyes, metal-containing nigrosine dyes, metal-containing fatty acid-modified nigrosine dyes, chromium complexes of 3,5-di-tert-butylsalicylic acid, and the like can be used. It is used in an amount of 0 to 20% by weight.

As other additives, silica powder, hydrophobic silica powder, polyolefin, paraffin wax, fluorocarbon compounds, fatty acid esters, partially saponified fatty acid esters, fatty acid metal salts, etc. can be used, and these are usually added to the toner. 0-10% by weight is used.

These materials are mixed, for example, by the following method to produce a toner for developing electrostatic images.

The weighed materials are premixed using a W cone, pre-mixer, Henschel mixer, etc., and then mixed at a temperature that melts the binder using a pressurized nee-goo, Banbury mixer 1 hot roll, extruder, etc. After cooling, it is coarsely pulverized using a feather mill, pin mill, pulverizer, hammer mill, etc., then finely pulverized using jet air, and then sieved using an Akie cut, Alpine classifier, etc., preferably 5 to 30%.
The particle size is adjusted to μm. Note that a fluidity modifier such as silica powder can also be simply mixed.

The toner using the resin of the present invention does not need to contain insoluble matter after being made into a toner.

(Function) Since the polymer of the present invention contains a large amount of a low molecular weight substance having good thermal meltability, it improves the fixing properties of the toner when used as an electrophotographic toner. Further, since the copolymer of the present invention contains a crosslinked polymer having sufficiently high elasticity, it improves the offset resistance of the toner.

(Example) Next, the present invention will be described in detail based on Examples, but the present invention is not limited thereto.

Examples 1 to 3 A stirrer with an H-shaped stirring blade, a cooling tube, a gas introduction tube, and a thermometer were attached to a 31 cylindrical separable flask, and 1200 g of tap water and Supertite-10 were added to the flask.
(trademark of aqueous dispersion of hydroxyapatite manufactured by Nippon Kayaku ■, non-volatile 10%), 0.024 g of sodium dodecylbenzenesulfonate, and 12 g of common salt were added. A flow of N2 gas was started, the mixture was heated to 90''C without stirring, and Polymerization Mixture A shown in Table 1 was added dropwise over a period of 2 hours.

After the dropwise addition, the mixture was kept at 90°C for 2 hours, cooled to 50°C, and 60g of Supertite=10 was added to the suspension polymerization system, followed by the polymerization mixture B shown in Table 1. . Stir as it is at 50℃ for 1 hour, then 85℃ for 1 hour.
℃, 3 hours at 85℃, then 1 hour at 90℃,
Subsequently, the mixture was kept at 96°C for 2 hours, and then cooled to about 40°C to complete the polymerization. Next, 2 Qml of concentrated hydrochloric acid is added to adjust the pH of the aqueous system to 2 or less, and then the mixture is filtered under reduced pressure to obtain polymer beads. Polymer beads are mixed with approximately 500 ml of tap water.
After washing twice, it was dried in a dryer at 50°C for 12 hours.

The compositions of polymerization mixtures A and B and the properties of the polymer beads are shown in Table 1.

Comparative Examples 1 to 3 Polymer beads having the properties shown in Table 2 were produced in the same manner as in Example 1 using polymerization mixtures A and B having the compositions shown in Table 2.

Note that the divinylbenzene used in the examples and comparative examples is a mixture with ethylvinylbenzene containing 156% divinylbenzene.

(Margin below) Table 1 Table 2 *Peak values were measured using a differential scanning calorimeter.

**1.0mX1. A load of 30 kg was measured using a flow tester CFT-500 manufactured by Shimadzu Corporation with a die of Qm.
f/aJ and a temperature increase rate of 3° C./min.

Application Example: 450 g of the copolymer produced in the above example or comparative example.
, carbon black #44 (Mitsubishi Kasei side type) 40g, Viscol 550P (low molecular weight polypropylene, manufactured by Mitsubishi Kasei ■) 10g, oil black BY with glosine dye,
After 25 g of Orient chemical type) was heat-melted and kneaded using a Conida kneader, it was coarsely ground using a hammer mill, and then finely ground using a jet air mill. This was classified and the particle size was 5.
A toner with an average particle size of ~30μ and an average particle size of 14μ was obtained.

Next, 50 g of toner and 950 g of EFV200/300 (amorphous iron oxide powder carrier, Japanese iron powder type) were mixed and sufficiently shaken to prepare a developer.

Up: Gokyo 1 Negative (a) Storage stability Approximately 5 g of the toner was placed on a glass petri dish to a uniform thickness and stored in a constant temperature bath at 55° C. and 90% humidity for 24 hours. This was sieved through a 100-mesh wire mesh, the passing weight was measured, and the weight was evaluated based on the following criteria.

5: 95% by weight or more passed 4 Near 0-95% by weight passed 3: 30-70% by weight passed 2; 5-30% by weight passed 1: 5% by weight or less (b) Fixability and offset resistance Copying machine 5F755 ( A developer was placed in a testing machine modified from a Sharp type, and an unfixed image with the top 1/3 of an A4 size sheet solid black was created.

This unfixed image was tested by changing the temperature in a 10°C range from 100°C to 240°C using a Teflon roll fixing tester and fixing it at a linear speed of 900an/min (A4 size, approximately 30 sheets/min). .

The good fixing temperature was defined as the temperature at which cellophane tape was removed from the fixed black solid area and the image density change rate was 10% or less. In addition, the offset occurrence temperature is 0.2% if the ID of the white paper part where the offset of the black solid part occurs is 0.2% compared to the black solid part.
The temperature was set to above.

(C) Put the actual copying test developer into the copying machine 5F755 (Sharp type),
A continuous copying test of 8,000 sheets was conducted, and the initial image and changes in the image were observed.

The results of toner evaluation are shown in Table 3.

(The following is a blank space) In the case of Comparative Examples 2 and 3, the melt viscosity of the resin was high and the kneading properties were poor.

(Effects of the Invention) The resin of the present invention has good thermal meltability and high elasticity, and has excellent properties as a binder resin for electrophotographic toners. Therefore, by using the resin of the present invention, it is possible to easily and inexpensively produce a toner that has excellent fixing properties in a hot roll fixing system and also has excellent anti-offset properties.

Claims (1)

[Scope of Claims] 1. An electrophotographic toner binder resin containing 5 to 50% by weight of acetone-insoluble components and having a polymerization average molecular weight of soluble components of 70,000 or less. 2. The electrophotographic toner binder resin according to claim 1, which is a vinyl polymer obtained by (co)polymerizing 50 to 100% by weight of styrene.