JPH0680464B2 - Positively chargeable toner for electrostatic image development - Google Patents

Description

The present invention relates to a toner for developing an electrostatic charge image, and more particularly to a positively charged toner used in electrophotography and the like.

Conventionally, developing methods in electrophotography, electrostatic recording and the like are roughly classified into a dry developing method and a wet developing method. The former is further divided into a method of using a two-component developer and a method of using a one-component developer. Among the two-component developing methods, there are a magnet brush method using an iron powder carrier, a cascade method using a bead carrier, and a fur brush method using a fur, depending on the type of carrier that conveys toner.

In the two-component developing method, a mixed developer of carrier particles and toner particles is inevitably used, and the toner particles are usually consumed in a much larger amount than the carrier particles due to the progress of the developing process. It inherently has the drawbacks that the density of the suspended image changes and the density of the suspended image fluctuates, and the image quality is deteriorated due to deterioration of the carrier particles, which are difficult to be consumed, due to long-term use.

Further, if toner that does not become triboelectrically charged is generated due to a change in the toner carrier mixing ratio, the toner indiscriminately contacts the surface to be developed, that is, the image area and the non-image area, and this causes the toner even to the non-image area. There is a problem in that the particles tend to adhere to form so-called ground fog and stain easily occurs.

Further, since the substantially non-magnetic toner can be restrained only by electrostatic attraction or physical adhesive force, there is a tendency that the inside of the apparatus or the image is often soiled due to scattering or spilling.

The object of the present invention is to provide a toner capable of maintaining positive triboelectrification property which is sufficiently stable against environmental fluctuations such as fluctuation of mixing ratio of toner and carrier and temperature / humidity, except for the above-mentioned problems. Is.

Further, it is an object of the present invention to provide a toner that has less tendency to contaminate an image due to scattering of toner and the like.

Another object of the present invention is to provide a toner having good pulverizability, high productivity, mechanical strength, and high durability.

Another object of the present invention is to provide a toner that does not damage or contaminate the surface of the photoconductor.

That is, an object of the present invention is an electrostatic charge image developing toner containing at least a positively chargeable resin having a positively chargeable triboelectrification characteristic, an organic carboxylate, and a low triboelectrification resin. ) 0.1 to 5 parts by weight of the organic carboxylate is contained with respect to 100 parts by weight of the positively chargeable resin, and the positive triboelectric charge of the positively chargeable resin composition containing the organic carboxylate is contained. The characteristics are improved as compared with the positively chargeable resin, and (b) when the triboelectric charge amount of the positively chargeable resin is T ₁ (μc / g), the friction of the low frictionally chargeable resin is Charge amount T ₂ (μc /
g) is a resin satisfying the formula | T ₂ | ≦ 1/5 | T ₁ |, to provide a positively chargeable toner for electrostatic image development.

In the developing method using the toner and the carrier, the interaction between the toner and the carrier becomes extremely important.
That is, in order for the toner to be uniformly charged, the frictional charging between the toner and the carrier must be fast, and the quantity must be large to some extent. However, if the amount is too large, it is difficult to separate from the carrier during development,
Image density is reduced. Further, even if the toner seems to be uniformly charged apparently, there is a possibility that the background fogging and the toner scattering may increase due to the presence of the toner having a microscopic variation in the triboelectric charge amount and the toner having the charge leakage. .

That is, as a result of intensive studies to solve the above-mentioned problems, the present invention has found that the use of a toner satisfying the above-mentioned conditions gives good results.

That is, the triboelectrification ability of the standard positively chargeable resin is locally enhanced by the addition of an organic acid salt such as a fatty acid salt to improve the electrification ability by the contact friction with the carrier and at the same time it can be regarded as substantially neutral. It is considered that the whole is diluted by the addition of and the excessive charge amount is prevented from being retained, so that the chargeability is stabilized and balanced.

Further, with this configuration, the hardness and brittleness of the toner can be adjusted appropriately, so that it is extremely easy to improve the durability and prevent damage and contamination of the surface of the photoconductor.

As the positively chargeable resin used in the present invention, a resin having positive chargeability with respect to a conductor such as metal or metal oxide can be used. In general, acrylate derivatives such as dimethylaminoethyl acrylate, diethylaminoethyl acrylate, dibutylaminoethyl acrylate, N-ethyl-N-phenylaminoethyl acrylate, and dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, dibutylaminoethyl methacrylate, N- Homopolymers of amino acrylic monomers such as methacrylate derivatives such as ethyl-N-phenylaminoethyl acrylate, or styrene monomers such as styrene, cross styrene, vinyl toluene, acrylic acid, acrylic acid ester, methacrylic acid, methacrylic acid ester, etc. Of acrylic monomers, acrylonitrile, butadiene, ethylene, prorylene, etc. with one or more monomers Is used.
Since the positively chargeable resin is a standard for the positively chargeable property of the toner, it is preferable to contain 30% by weight or more of the binder resin in the toner. Further, as the organic acid salt used in the present invention, it is possible to use an acid salt which improves the positive triboelectrification property of the resin by adding 2 parts by weight or less to 100 parts by weight of the positively chargeable resin. Generally, a metal soap derived from a fatty acid having 12 to 30 carbon atoms, a sulfonate or the like is used, and preferably a fatty acid metal salt having 12 to 30 carbon atoms such as lauric acid, palminic acid, stearic acid or naphthenic acid is used. Such saturated fatty acid metal salts or unsaturated fatty acid metal salts such as oleic acid are used. The amount of organic acid salt added is generally 0.1 per 100 parts by weight of the positively chargeable resin in the toner.
-5 parts by weight is preferred. If the amount is less than the above range, the compatible dispersion of the toner constituents is insufficient, resulting in a phenomenon such as a decrease in the aggregation fluidity of the toner, a decrease in the triboelectric chargeability and charge controllability of the toner, and the like. On the other hand, if it is more than this, the compatible dispersion of the toner constituents is sufficiently carried out, but under high humidity,
A toner agglomeration phenomenon, a concentration reduction phenomenon in durability, and the like occur.

The resin used in the present invention, which can be regarded as substantially neutral, has a triboelectric charge amount T _{2 of} that of the positively chargeable resin To ₁ , Those satisfying the following conditions are used.

Generally, polystyrene, poly-p-chlorostyrene,
Homopolymers of styrene such as polyvinyltoluene and its substitution products; styrene-p-crossstyrene copolymers, styrene-propylene copolymers, styrene-vinyltoluene copolymers, styrene-vinylnaphthalene copolymers, styrene-acrylics. Methyl acid copolymer, styrene-ethyl acrylate copolymer, styrene-butyl acrylate copolymer, styrene-octyl acrylate copolymer, styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer , Styrene-butyl methacrylate copolymer, retylene-α-chloromethyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-
Vinyl methyl ether copolymer, styrene-vinyl ethyl ether copolymer, styrene-vinyl ethyl ketone copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-acrylonitrile-indene copolymer, styrene- Styrene-based copolymers such as maleic acid copolymers; polymethyl methacrylate, polybutyl methacrylate, polyvinyl chloride, polyvinyl acetate, polyethylene, polypropylene, polyester, polyurethane, polyamide, epoxy resin, polyvinyl butyral, polyacrylic acid resin, Rosin, modified rosin,
Terpene resins, phenol resins, aliphatic or alicyclic hydrocarbon resins, aromatic petroleum resins, chlorinated paraffins, paraffin waxes and the like can be used alone or in combination.
Among them, polystyrene, styrene-acrylic copolymer, styrene-butadiene copolymer, epoxy resin, polyester resin and the like are particularly preferable. The content of the neutral resin may be an appropriate amount depending on the type and amount of the positively chargeable resin and the organic acid salt, but generally 5 to 70% by weight of the total binder resin.
Is preferred. If it is less than this, the diluting effect as a neutral resin is insufficient, and if it is more than this, the positive charging property of the toner is offset.

In the toner, any suitable pigment or dye can be used as a colorant. For example, there are known dyes and pigments such as carbon black, iron black, phthalocyanine blue, ultramarine blue, quinacridone, and benzidine yellow.

Further, as a charge control agent, an amino compound, a quaternary ammonium compound and an organic dye, particularly a basic dye and a salt thereof, benzyldimethyl-hexadecyl ammonium chloride, decyl-trimethyl ammonium chloride, nigorosine base, nigrosine hydrochloride, safranine γ and crystal. A biolate, a metal-containing dye, a salicylic acid metal-containing compound or the like may be added. Further, magnetic powder may be added to the extent that the effects of the present invention are not impaired.

Further, magnetic powder may be added to the extent that the effects of the present invention are not impaired.

The toner composition described above may be used as a developer by a generally used mixing-pulverizing method, or may be used as a wall material or a core material of a microcapsule developer, or both.

As the carrier used in the present invention, for example, surface-oxidized or unoxidized metals such as iron, nickel, cobalt, manganese, chromium, rare earths, and alloys or oxides thereof can be used. Moreover, there is no particular limitation in the manufacturing method.

Then, the carrier surface may be treated with a resin or dye / pigment, a charge control agent, a fluidity control agent or the like, which may be adhered alone or in plural.

Here, the method for measuring the triboelectric charge amount of the positively chargeable resin and the positively chargeable resin containing an organic acid salt and the neutral resin will be described in detail with reference to the accompanying drawings.

First, the number average particle size of each resin powder is 9 to 11μ by a Coulter counter manufactured by Coulter Co., and the volume average particle size is 13 to 15μ, 6.35μ or less is 20 number% or less, and 20.2μ or more is It adjusts so that it can be considered that the particle size is substantially equal to or less than 15% by weight.

Next, the triboelectric charge amount of each sample is measured using the apparatus shown in FIG. First, a conductive screen 13 of 400 mesh (the size can be changed so that magnetic particles do not pass through) 13 at the bottom
Amorphous iron powder with no special treatment on the surface between the resin powder whose particle size is 200-300 mesh and the resin powder whose frictional charge is to be measured in a metal measuring container 12 with Of the mixture (developer) in a weight ratio of 1: 9 is put in a lid 14 made of metal. At this time, the total weight of the measurement container 2 is weighed and set as W ₁ (g). Next, in the suction device 11 (at least the portion in contact with the measurement container 2 is an insulator), suction is performed from the suction port 17 and the air flow rate control valve 16 is adjusted to bring the pressure of the vacuum gauge 15 to 70 mmHg. In this state, suction is sufficiently performed (for about 1 minute) to remove the resin powder by suction. The potential of the electrometer 19 at this time is V (volt). Here, 18 is a capacitor, and the capacity is C (μF). In addition, the total weight of the measuring container after suction is weighed and is W ₂ (g). The frictional charge amount T (μC / g) of this resin powder is calculated by the following equation.

However, the measurement conditions are 23 ° C and 50% RH.

Next, the present invention will be described in more detail based on examples.
The number of parts is part by weight.

〔Example〕

First, resin I as a positively chargeable resin, II as a fatty acid salt,
I chose III and IV. The triboelectric charge amount of the positively chargeable resin and the positively chargeable resin composition containing 2 parts of the fatty acid salt with respect to 100 parts of the positively chargeable resin was measured in advance by a predetermined method. The results are shown in Table I.

Further, the triboelectric charge amounts of the neutral resins V, VI, VII and VIII were measured in the same manner. The results are shown in Table 2.

Table 3 shows the results of each Example and Comparative Example in which these materials were combined.

Example 1 A Canon copying machine NP-5000 was modified so that a negative positive charge image could be formed and used for copying in this experiment.

Next, resin I 50 parts, zinc palmitate II 1 part, resin V50
Part and carbon black 3 parts were used to prepare a positively chargeable toner having an average particle size of 8 μm. This toner satisfies the conditions of the present invention (| T ₂ | <| T ₁ | / 5). 10 parts of this toner was mixed with 100 parts of an irregular shaped iron powder carrier having a particle size of 200 to 300 mesh, and the mixture was put into the above copying machine and developed. The obtained copied image was good without any fog or unevenness. Further, even when the toner was replenished properly and the durability was increased to 10,000 sheets, the photosensitive drum was not contaminated or damaged, and the image was not changed. Moreover, the image quality did not deteriorate even in the special environment of 15 ° C, 10% RH, 35 ° C, 90% RH. further,
After running, there was almost no toner spillage or scattering.

[Example 2] A positively chargeable toner having an average particle diameter of 9 µ and comprising 70 parts of resin I, 1 part of zinc naphthenate III, 30 parts of resin VI, and 5 parts of phthalocyanine pigment and satisfying the conditions of the present invention was prepared and used. When performed in the same manner as in Example 1, similarly good results were obtained.

Comparative Example 1 Example 2 was repeated except that sodium laurate IV which did not satisfy the conditions of the present invention was used in place of zinc naphthenate III.
As a result, the charging ability was drastically lowered and a decent image could not be obtained. Further, after the endurance, the toner scattering was severe.

Comparative Example 2 Instead of Resin VI, Resin VII (| T ₂ which does not satisfy the conditions of the present invention
When the same procedure as in Example 2 was carried out except that |> | T ₁ | / 5) was used, the chargeability of the toner was too high, and an image with a large density unevenness was obtained.

[Example 3] Resin I 80 parts, zinc naphthenate IIIH 1.5 parts, resin VIII 20 parts,
The same good results were obtained when the same procedure as in Example 1 was carried out except that a positively chargeable toner having an average particle diameter of 8 μ and satisfying the conditions of the present invention consisting of 5 parts of phthalocyanine pigment was used.

[Brief description of drawings]

FIG. 1 is an explanatory view showing a triboelectric charge amount measuring device according to the present invention. In the figure, 11 is a suction device, 12 is a measuring container, 13 is a conductive screen, 15 is a vacuum gauge, 16 is an air flow control valve, 17 is a suction port, and 18 is a condenser.

 ─────────────────────────────────────────────────── --Continued from the front page (56) Reference JP-A-59-223448 (JP, A) JP-A-58-37652 (JP, A) JP-A-53-5633 (JP, A) JP-A-54- 143647 (JP, A) JP 59-189351 (JP, A) JP 59-195664 (JP, A) JP 59-137955 (JP, A)

Claims (1)

[Claims] 1. A toner for developing an electrostatic charge image, which comprises at least a positively chargeable resin having a positively chargeable triboelectric charging characteristic, an organic carboxylate, and a low triboelectrification resin, comprising: (a) the positive charge The organic carboxylate is contained in an amount of 0.1 to 5 parts by weight based on 100 parts by weight of the chargeable resin, and the positive triboelectric charging property of the positively chargeable resin composition containing the organic carboxylate is (B) When the triboelectric charge amount of the positively chargeable resin is T ₁ (μc / g), the triboelectric charge amount T of the low triboelectric chargeable resin is T. ₂ (μc /
g) satisfies the formula | T ₂ | ≦ 1/5 | T ₁ |, a positively chargeable toner for developing an electrostatic charge image.