JPH11231571A - Nonmagnetic one-component developing toner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a negative-charging nonmagnetic one-component developing toner which can form a high-quality image even when the toner is repeatedly used without causing the contamination of the toner on a carrying member and a layer thickness regulating member. SOLUTION: This toner consists of resin particles essentially comprising a binder resin, a coloring agent and a negative-charging charge controlling agent. A positive-charging silica subjected to hydrophobic treatment and a negative-charging silica subjected to hydrophobic treatment are deposited on the surface of the resin powder particles. The deposition amt. Wp pts.wt. and the saturated charge amt. Qp μc/g of the positive-charging silica and the deposition amt. Wn pts.wt. and the saturated charge amt. Qn μc/g of the negative- charging silica to 100 pts.wt. of the resin powder satisfy the relation of the formula.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a toner used in an image output device such as a copying machine or a printer.

[0002]

2. Description of the Related Art In a non-magnetic one-component developing method, toner is carried on a conveying member surface by an electrostatic force of toner and a conveying member, is conveyed to a developing position, and develops a latent image on a photoreceptor surface. In order to generate an electrostatic force between the toner and the conveying member, a layer thickness regulating member in contact with the conveying member is often used, and when the toner passes between the layer thickness regulating member and the conveying member, the toner Will be charged. In order to charge the toner instantaneously and uniformly, it is important to make the toner thinner, and the member also controls the toner layer at the same time. Therefore, if the conveying member and the layer thickness regulating member are contaminated with the toner, the toner on the conveying member cannot be controlled to a desired charge amount, which causes an increase in fog and density unevenness such as white stripes.

Hitherto, to reduce toner contamination, an increase in the amount of external silica has been proposed. This is intended to prevent fusion of toner components due to frictional heat generated when the toner passes between the conveying member and the layer thickness regulating member, but it cannot sufficiently prevent toner contamination.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a negatively-chargeable non-magnetic material which can provide a high-quality image even when used repeatedly without causing toner contamination on a conveying member and a layer thickness regulating member.
Provided is a toner for component development.

[0005]

According to the present invention, there is provided a developing apparatus having at least a conveying member for carrying and conveying a non-magnetic one-component developing toner and a layer thickness regulating member provided in pressure contact with the conveying member. A toner to be used, wherein the toner is a binder resin, a colorant, a surface of a resin powder containing a negatively chargeable charge controlling agent as essential components, at least a hydrophobically treated positively chargeable silica and a negatively chargeable silica. By attaching
To prevent toner fusion to the conveying member and the layer thickness regulating member. Further, when the addition amounts of the positively chargeable silica and the negatively chargeable silica are Wp and Wn, and the absolute values of the saturated charge amounts thereof are | Qp | and | Qn |, the following expression (1) is satisfied. By adopting a silica external addition method, a conveying member,
It has been found that an image having high image density and less fog can be obtained without toner fusion to the layer thickness regulating member.

[0006]

(Equation 2)

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.
As the binder resin used in the toner of the present invention, an alcohol component such as a dialcohol component, a polyester resin obtained from a polyhydric alcohol component and a carboxylic acid component such as a dicarboxylic acid component, a polycarboxylic acid component, or a part thereof A polyester resin such as a polyester resin having a urethane bond, or a thermoplastic resin known as a binder for a conventional non-magnetic one-component toner such as a styrene acrylic copolymer is used. From the viewpoint of storage stability of the toner, these binder resins are preferably binder resins having a glass transition point of 55 ° C. or higher, and preferably have an acid value of 40 or lower. If the acid value exceeds 40, the moisture resistance deteriorates, which is not preferable. More preferably, it is 20 or less.

[0008] Colorants used in the toner of the present invention include any suitable pigments or dyes conventionally used in toners. Pigments such as carbon black,
Examples include aniline black, acetylene black, naphthol yellow, hansa yellow, rhodamine lake, alizarin lake, red bengala, phthalocyanine blue, and indanthrene blue. These pigments are used in an amount necessary and sufficient to maintain the optical density of the fixed image, and are usually added in an amount of 0.1 to 20 parts by weight, preferably 0.2 to 10 parts by weight, based on 100 parts by weight of the binder resin. You. As a dye,
Examples include azo dyes, anthraquinone dyes, xanthene dyes, methine dyes, and the like. These dyes are generally added in an amount of 0.1 to 20 parts by weight, preferably 0.3 to 10 parts by weight, based on 100 parts by weight of the binder resin.

As the negatively chargeable charge controlling agent, for example, an organic metal complex or a chelate compound is effective. An azo-based metal complex, an acetylacetone metal complex, an aromatic hydroxycarboxylic acid, an aromatic dicarboxylic acid, an aromatic mono- and poly-organic complex are preferable. Examples thereof include carboxylic acids and metal salts thereof, anhydrides, esters, and phenol derivatives such as bisphenol.
These charge control agents are generally added in an amount of 0.1 to 10 parts by weight, preferably 0.5 to 5 parts by weight, based on 100 parts by weight of the binder resin. Exceeding the upper limit of the above range causes poor charging and causes deterioration in image quality due to fogging and the like, and a charge amount less than the lower limit does not provide a sufficient charge amount, lowering the image density,
There is a problem that the image density is not stable when a large number of continuous copies are made. The resin powder may contain a release agent such as polypropylene wax or polyethylene wax.

The resin powder may be obtained by melt-kneading, pulverizing and classifying the binder resin, the colorant, the negative charge control agent, and the like, or the colorant, the negative charge control and the like during polymerization of the binder resin. It may be obtained by a polymerization method containing an agent or the like. In order to attach the positively chargeable silica and the negatively chargeable silica described below to the surface of the resin powder, it is sufficient to attach the positively chargeable silica and the negatively chargeable silica using a stirrer such as a Henschel mixer or a super mixer. May be attached to the surface of the resin powder in a weak state called a glare, or a state in which a part of the positively chargeable silica and the negatively chargeable silica is buried and fixed inside the resin powder. In addition to the positively chargeable silica and the negatively chargeable silica, inorganic fine particles such as alumina, titania, and zinc oxide, and conductive fine particles such as carbon black may be attached to the surface of the resin particles.

As the hydrophobicized negatively chargeable silica and positively chargeable silica used in the present invention, commercially available ones can be used, but the relational expression between the saturated charge amount and the amount of adhesion to the toner surface is given by (1). It is necessary to select silica that satisfies the expression and determine its amount in order to obtain an image with high image density and less fog. (1) Value of central term Wn × | Q
When n | / Wp × | Qp | is smaller than 7, fog increases, and when n | / Wp × | Qp | is larger than 30, the toner is fused to a conveying member (hereinafter, referred to as a sleeve) or a layer thickness regulating member (hereinafter, referred to as a blade). Easy to wear. Further, the amount of the positively chargeable silica needs to be more than 0.025 parts by weight with respect to 100 parts by weight of the resin powder, and if it is less than 0.025 parts by weight, the effect of preventing fusion of the toner is not recognized. The upper limit is determined from the formula (1) from the amount of the negatively chargeable silica and the amount of the saturated charge. The amount of the negatively chargeable silica may be determined in consideration of the fluidity of the toner, but is preferably 0.02 to 1 part by weight, more preferably 0.5 to 0.9 part by weight.

The reason why toner fusion does not occur when negatively chargeable silica and positively chargeable silica are used together within the scope of the present invention has not been completely elucidated. Since the polarity is opposite to the normal charge polarity (negative charge in the case of the present invention), the toner to which only the negatively chargeable silica is attached easily adheres firmly to the blade or the sleeve. It is considered that the frictional force at the time of passing increases, and as a result, toner fusion occurs.

However, if the positively chargeable silica is added within the scope of the present invention, a portion of the toner surface that is neutrally charged or positively charged is formed, and this portion exerts a roller action, so that the toner is The applied frictional force is weakened. As a result, it is considered that the toner is prevented from fusing, and since there is no generation of an extremely large positive charge amount, the toner is unlikely to cause fog, density loss, and toner scattering.

As the negatively chargeable silica, known silica obtained by subjecting hydrophilic silica to a hydrophobic treatment with a silane compound such as hexamethylenedisilazane or dimethyldichlorosilane, dimethylsilicone oil, or various modified silicone oils can be used. As the positively chargeable silica, use is made of known silica obtained by subjecting hydrophilic silica to an amino-modified silicone oil, a quaternary ammonium compound, or the like, or performing a hydrophobic treatment and a positive charge imparting treatment with various silane compounds together with these positive treatment agents. It is possible.

The positively chargeable and negatively chargeable silica having an average primary particle diameter of about 10 to 50 nm is preferably used because of its high toner fluidity-providing effect, and has a methanol wettability value of at least 40 as a measure of hydrophobicity. preferable.
More preferably, it is 45 or more. If it is less than 40, the toner charging in a high-temperature environment is undesirably reduced.

The optimum total addition amount of the positively chargeable silica and the negatively chargeable silica cannot be unconditionally determined by the particle size distribution of the toner or the fluidity of the resin powder before silica addition. In the case of a toner having a size of 9 μm, the amount is preferably 0.2 to 2 parts by weight based on 100 parts by weight of the resin powder. More preferably, it is 0.4 to 1.5 parts by weight. If it exceeds 2 parts by weight, environmental stability and fixability tend to decrease, which is not preferable.

A method for measuring the saturated charge amounts Qpμc / g and Qnμc / g of the positively and negatively chargeable silica will be described. The positively or negatively chargeable silica is sieved with a 150 mesh sieve, and the silica that has passed 150 mesh is used for the measurement. Carrier (Powdertech: FSL)
1020) 99.8 g and 0.2 g of silica for measurement are added to 150
22-24 ° C / 57-62% R
Leave for 10 hours in an atmosphere adjusted to H. Thereafter, the polybin is set on a rotating device of constant rotation, and then the polybin is rotated under this atmosphere to perform mixing and stirring. In the mixing process, the charge amount of the silica is measured three times every five minutes from the beginning by a blow-off charge amount measuring device, and the average value of the three times is rounded to the nearest whole number to obtain the charge amount during the stirring time. .
Since the charge amount of silica becomes maximum at a certain point in time series and thereafter decreases, the maximum charge amount in the stirring and mixing process is defined as the saturated charge amount in the present invention. A 400 mesh mesh is used as a stainless steel net used for separating the carrier and silica when measuring with a blow-off charge amount measuring device.

[0018]

The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the invention is limited thereto.

<Production of Resin Powder A> Polyester resin (Tg = 63 ° C., Mn = 3900, Mw = 48300, THF insoluble content = 13%) 100 parts by weight Carbon black (Cabot Corporation: Regal 400R) 5.5 parts by weight Part Negatively chargeable charge control agent (Orient Chemical Co., Ltd .: S-34) 1.3 parts by weight Polypropylene wax 1.5 parts by weight (Sanyo Chemical Industries Co., Ltd .: Viscol 550P) After uniformly mixing the above materials, an extruder And kneaded well. After cooling, pulverization and classification were performed, and the volume average diameter was 9.5 μm.
Resin powder A was obtained.

<Example of Negatively Chargeable Hydrophobic Silica> Silica A (methanol wettability value = 48, dimethyldichlorosilane treatment, specific surface area 110 m ² / g) Saturated charge amount Qn = −320 μc / g Silica B (methanol wettability value = 80, hexamethylene disilazane treatment, specific surface area 140 m ² / g) Saturated charge amount Qn = −490 μc / g

<Example of Positively Chargeable Hydrophobic Silica> Saturated charge amount Qp Silica C (manufactured by Clariant Japan: HVK2115) +130 μc / g Silica D (manufactured by Clariant Japan Co., Ltd .: H3050EP) +380 μc / g Silica is adhered to the resin powder A by a Henschel mixer as shown in Table 1 to prepare toners of Examples and Comparative Examples. ), A print test is performed, and image density (ID), fog (B
G), the presence or absence of toner fusion was confirmed. The test environment conditions are 22-25 ° C./55-65% RH. In the print test, a character chart having a printing rate of about 6% was repeatedly printed. The presence or absence of toner fusion was confirmed by printing a halftone image (A4 size). The results of the actual test are shown in Table 2. The image density (ID) is the reflection density of a solid image measured by Macbeth RD-914, and the fog (BG) is the difference in hunter whiteness of the non-image portion between the paper before printing and the same paper after printing. Show.

[0022]

[Table 1]

[0023]

[Table 2]

[0024]

As is apparent from the results of the above comparative study, the toner of the present invention is subjected to a hydrophobic treatment on the surface of a resin powder containing a binder resin, a colorant and a negatively chargeable charge control agent as essential components. A favorable charge amount can be obtained by the addition of the positive and negative chargeable silica, and in particular, 7 ≦ Wn × | Qn
| / Wp × | Qp | ≦ 30, the one-component developing toner can be used in both the actual printing test and after 7000 sheets.
The toner was not adhering to the sleeve and was suitable.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Atsushi Miyamoto 3-1 Yomoe Tomoecho, Shizuoka City, Shizuoka Pref.

Claims (2)

[Claims] 1. A surface of a resin powder containing a binder resin, a colorant and a negatively chargeable charge controlling agent as essential components, at least a positively chargeable silica subjected to a hydrophobic treatment and a negatively chargeable silica subjected to a hydrophobic treatment. With respect to 100 parts by weight of the resin powder, the amount of the positively chargeable silica is Wp part by weight and the amount of the saturated charge is Qpμc / g, and the amount of the negatively chargeable silica is Wn part by weight and the amount of the saturated charge is 100 parts by weight. A toner for non-magnetic one-component development, which satisfies the following expression (1) when Qnμc / g is satisfied. (Equation 1) 2. The non-magnetic one-component developing toner according to claim 1, wherein the methanol wettability of the positively chargeable silica and the negatively chargeable silica is 40 or more.