JPH03197971A - Toner for developing electrostatic charge image - Google Patents

Abstract

PURPOSE:To obtain the toner which is excellent in fixability and non- offsettability by using a binder resin consisting of a specific vinyl polymer formed by reaction of a polymerizable vinyl monomer and a crosslinking agent. CONSTITUTION:A toluene-insoluble three-dimensional crosslinking structure is formed in the vinyl monomer formed by subjecting the polymerizable vinyl monomer constituting the binder resin and a mixture contg. the crosslinking agent and a coloring agent to suspension polymn. in such a manner that the crosslinking agent makes partial crosslinking reaction with the polymerizable vinyl monomer. The binder resin is so formed as to consist of the vinyl polymer of 3,000 to 12,000 number average mol. wt. contg. 3 to 30wt.% toluene-insoluble component. This binder resin does not, therefore, contain the intermediate mol. wt. component to exert adverse influence on the fixability and the non- offsettability and is constituted of only the low mol. wt. vinyl polymer formed partially with the three-dimensional crosslinking structure. The fixability and the non-offsettability are improved in this way.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is a method for developing an electrostatic charge image formed on the surface of a photoconductive photoreceptor in electrophotography, electrostatic recording, electrostatic printing, etc. More specifically, it is a toner for developing an electrostatic image suitable for a contact heating fixing method using a heat roller fixing method or the like.

[Conventional technology and its problems]

Conventionally, toners used to develop electrostatic images are composed of components such as a binder resin, a colorant, and optionally a charge control agent, magnetic powder, or other additives. The general manufacturing method is to premix these components and then take them out as a toner with a desired particle size range through the steps of melting and kneading, pulverization, and classification.

On the other hand, in order for the toner to be preferably used in the heated roller constant adhesion method, it must be softened at a relatively low temperature and reliably fused onto the fixing sheet (excellent in fixing properties);
In addition, important properties are required such as the fact that toner does not adhere to the heating roller even when the temperature of the heating roller is relatively high (excellent non-offset properties). As the binder resin, which is a constituent component, ■ a mixed polymer of a low molecular weight polymer component with excellent fixing properties and a high molecular weight polymer component with excellent non-offset properties, ■ a low molecular weight polymer component with non-offset properties. It is said that it is preferable to use a mixed polymer with a crosslinked polymer component having excellent properties, (1) a low molecular weight polymer formed by partially forming a crosslinked structure, etc.; For information on JP-A-55-6895 and JP-A-54-114245, etc., for ■, see JP-A-58-88558, etc., and for 50-448
These are disclosed in Publication No. 36 and the like.

[Problem that the invention seeks to solve]

In the conventional toner manufacturing method described above, toner particles are manufactured through a melt-kneading process, so molecules of the high molecular weight polymer component or crosslinked polymer component in the binder resin or the crosslinked structure part of the low molecular weight polymer There is a problem in that the effect of improving the non-offset property of the obtained toner is small because the chains are broken by the mechanical action during melt-kneading and partially transfer to intermediate molecular weight components that worsen the non-offset property.
In addition, if the mixing amount of the high molecular weight polymer component or crosslinked polymer component or the proportion of the crosslinked part in the low molecular weight polymer is increased in order to enhance the effect of improving non-offset property, the generation of intermediate molecular weight components will also be increased accordingly. In addition, the mechanical action during melt-kneading changes depending on the molecular weight of the polymer component, degree of crosslinking, and melt-mixing conditions (temperature, kneading speed, etc.). Therefore, there is a problem that the generation of intermediate molecular weight components is not constant and it is difficult to stabilize toner characteristics.

Therefore, at present, the mixing ratio of low molecular weight polymer components and high molecular weight polymer components or crosslinked polymer components is adjusted to maintain a balance so that the decrease in fixing properties and non-offset properties is as small as possible. It's not too much,
It's not completely satisfying.

In addition, especially in the case of the mixed polymer described in (1) above, the crosslinked polymer component can exhibit its effect with a smaller amount than the high molecular weight polymer, but it has poor compatibility with the low molecular weight polymer component. Therefore, it is difficult to uniformly mix the toner into the low molecular weight polymer by melt-kneading, resulting in a toner with non-uniform components.

Therefore, an object of the present invention is to solve the problem of poor fixing properties and non-offset properties in conventional toners, and to provide a binder that does not contain intermediate molecular weight components that adversely affect fixing properties and non-offset properties. The object of the present invention has been achieved by providing an electrostatic image developing toner containing a resin as a constituent component.

[Means to solve the problem]

The toner for developing electrostatic images provided by the present invention (hereinafter referred to as the "toner of the present invention") comprises a metal-filled material containing at least a polymerizable vinyl monomer constituting a binder resin, a crosslinking agent, and a colorant. Toner particles for developing electrostatic images obtained by suspension polymerization, in which the binder resin in the toner particles contains a toluene insoluble content of 3 to 30% by weight, have a number average molecular weight (hereinafter referred to as r M n J). )3,000~12,
000 vinyl polymer.

The toner of the present invention having the above structure differs from toners obtained by conventional melt-kneading methods, in that the binder resin contained in the toner particles does not contain intermediate molecular weight components that adversely affect fixing properties and non-offset properties. Since it is composed only of a low molecular weight vinyl polymer which has partially formed a three-dimensional crosslinked structure, the low molecular weight polymer component effectively acts on the fixing property, and the crosslinked polymer component effectively acts on the non-offset property.

Hereinafter, the toner of the present invention will be explained in detail.

Muvinyl monomer: The polymerizable vinyl monomer used in the present invention is a component that constitutes most of the binder resin of the toner through polymerization. Specific examples of the vinyl monomer include styrene, 0-2m- or p-vinyl monomer. - Styrenes such as styrene and their derivatives; α-methylene aliphatic monocarboxylic acid esters such as methyl methacrylate, ethyl methacrylate, butyl methacrylate, and 2-ethylhexyl methacrylate; methyl acrylate, ethyl acrylate, These polymerizable vinyl monomers include acrylic esters such as butyl acrylate and 2-ethyl acrylate, and these polymerizable vinyl monomers can be used alone or in combination of two or more types.

m: The crosslinking agent used in the present invention partially crosslinks with the polymerizable vinyl monomer to form a toluene-insoluble three-dimensional crosslinked structure in the formed vinyl polymer,
This is a component for imparting preferable non-offset properties to the toner obtained by this, and the crosslinking agent is a compound having two or more copolymerizable unsaturated groups in one molecule, such as ethylene glycol di(meth) 〉Acrylate, alkylene or di- or polyalkylene glycol di(meth)acrylate such as polyethylene glycol di(meth)acrylate, butanediol di(meth)acrylate; Meth)acrylates; divinylbenzene, etc. are mentioned.

Symptom 1: As mentioned above, the binder resin used in the toner of the present invention is a vinyl polymer containing a three-dimensional crosslinked structure insoluble in toluene formed by the reaction of a polymerizable vinyl monomer and a crosslinking agent. By using a binder resin containing such a toluene-insoluble content, the toner obtained has good thermal melting properties, particularly excellent non-offset properties. However, if this toluene-insoluble content is too large or too small, it is impossible to obtain a toner with excellent fixing properties and non-offset properties, which is the objective of the present invention. It should be in the range of ~30% by weight. In other words, if the toluene insoluble content is less than 3% by weight, no improvement in non-offset properties can be expected; on the other hand, if it exceeds 30% by weight, the non-offset properties will be good but the thermal melting properties will deteriorate. Adversely affects fixation.

In addition, the vinyl polymer component in the binder resin (excluding the toluene-insoluble portion) is a component for imparting good fixing properties to the obtained toner, and the vinyl polymer component is a component that imparts good fixing properties to the resulting toner. The Mn as determined by chromatography should be in the range 3,000 to 12,000. The reason is that when Mn is less than 3,000, the melt viscosity when used as a binder resin becomes too low, resulting in poor non-offset properties, while when Mn is greater than 12,000, defects such as poor fixing properties occur.

In addition, the copolymerization ratio of the polymerizable vinyl monomer and crosslinking agent to obtain a binder resin whose toluene insoluble content and Mn values are within the above specific ranges depends on the type of polymerizable vinyl monomer and crosslinking agent used, or Although it is extremely difficult to specify the amount because it varies depending on the type of polymerization initiator used in the crosslinking reaction and the polymerization conditions, it is generally 95 to 99.8% by weight of the polymerizable vinyl monomer and 0.2% by weight of the crosslinking agent.
5% by weight, especially the former 97.5% to 9% by weight.
Preferably, it is 9.5% by weight and the latter 0.5-2.5% by weight.

"Wataru 1: The coloring agent used in the present invention is not particularly limited and can be selected from a wide range. For example, carbon black, surface-treated grafted carbon black, calco oil blue (C, 1 , Naazoee
Blue 3), DuPont Oillet (C, 1,
Nα26+05>, malachite green offsalate (C, I, Na 42000), quinoline yellow (C, I, N (147005), rose bengal (C
, I, Nn45435), nigrosine-stained F4 (C
, I, Na 504158), phthalocyanine blue (C, I, N(174160), ultramarine blue (C,1,Nα77103), lamp black (
C, I, Na 77266), and mixtures thereof. These colorants are blended in a proportion necessary to form a visible image with sufficient concentration, and are usually 1 to 10 parts by weight per 100 parts by weight of the polymerizable monomer constituting the binder resin.
20 parts by weight are used, preferably within the range of 2 to 7 parts by weight.

One power: "νI Meng: The toner of the present invention includes the above-mentioned polymerizable vinyl monomer crosslinking agent,
A desired amount of a coloring agent and an appropriate polymerization initiator are thoroughly mixed and dispersed using a high-speed stirring device such as a homomixer or a homogenizer to prepare a mixture, and this mixture is mixed with a slightly water-soluble inorganic fine powder as a dispersant. It is obtained by suspending the polymer particles in an aqueous dispersion medium with stirring and carrying out suspension polymerization according to a conventional method. After removing the poorly water-soluble inorganic dispersant, the polymer particles are collected by an appropriate method such as filtration, decantation, centrifugation, etc., and dried to obtain a toner.

Polymerization initiators that can be used in the suspension polymerization include 2,2'-azobis-(2,4-dimethylvaleronitrile), 2,2'-azobisisobutyronitrile, 1,1'-azobis- -(cyclohexane-1-carbonitrile), 2,2'-azobis-4-methoxy2,
Examples include azo polymerization initiators such as 4-dimethylvaleronitrile; peroxide polymerization initiators such as benzoyl peroxide, methyl ethyl ketone peroxide, and lauroyl peroxide; each of these polymerization initiators may be used alone. However, two or more types of polymerization initiators may be used in combination in order to impart desired properties to the resulting toner.

In addition, examples of poorly water-soluble inorganic powders that can be used as a dispersant when carrying out suspension polymerization include tertiary calcium phosphate, magnesium phosphate, calcium sulfate, magnesium carbonate, calcium carbonate, hydroxyapatite, etc. .

In addition to the polymerizable vinyl monomer, crosslinking agent, and colorant described above, the toner of the present invention requires various additives commonly used in the electrophotographic industry for the purpose of improving the characteristics of the resulting toner. It can be added as appropriate.

For example, for the purpose of further improving anti-offset properties, substances with mold release properties may be used, such as higher fatty acids or metal salts of higher fatty acids, natural or synthetic waxes, higher fatty acid esters, or partially saponified products thereof. , alkylene bis fatty acid amides, fluororesins, silicone resins, etc. may also be blended. The blending amount is generally 1 to 100 parts by weight of polymerizable monomer and crosslinking agent.
The amount can be within the range of 10 parts by weight, and in the case of a -component toner, magnetic powder can be used together with each component including the polymerizable vinyl monomer.

Examples of magnetic powders that can be used include ferrite, magnetite, iron, cobalt, nickel, and other ferromagnetic metals or alloys, or compounds containing these elements, or materials that do not contain ferromagnetic elements but undergo appropriate heat treatment. Examples of alloys that exhibit ferromagnetism when subjected to ferromagnetism include alloys called Heusler alloys containing manganese and copper, such as manganese-copper-aluminum and manganese-copper-tin, or chromium dioxide. .

These magnetic substances are uniformly dispersed in the toner particles in the form of fine powder with an average particle size within the range of 0.1 to 1 micron.
The amount is generally 20 parts by weight per 100 parts by weight of the polymerizable monomer.
-70 parts by weight, preferably 40-70 parts by weight.

〔Example〕

Hereinafter, the present invention will be explained in more detail based on Examples. In addition, the copolymerization ratio or mixing ratio of each component in the examples is expressed in parts by weight unless otherwise specified.

Example-1 Styrene 80g 1 Butyl acrylate 20g, Crosslinking agent (
1,3-butylene glycol dimethacrylate) 1.7
g, and carbon black (manufactured by Mitsubishi Kasei Corporation, MA-4
0) using an attritor, and further added 2,2'-azobisisobutyronitrile 6 as a polymerization initiator.
g was added to prepare a polymerizable and nil monomer mixture.

Separately, a dispersion medium was prepared by adding 20 g of tertiary calcium phosphate and 1 g of sodium alkylnaphthalene sulfonate to 1 kg of ion-exchanged water.

The above polymerizable and nyl monomer mixture was added to the above dispersion medium, and suspension polymerization was carried out at 90°C for 1 hour under stirring at 3500 rpm using a disperser type dispersion machine to complete the polymerization of the monomer mixture. cooling the reaction product;
After removing tertiary calcium phosphate adhering to the surface of the reaction product with nitric acid, a toner was produced through the following steps: dehydration, washing, dehydration, and drying.

The toner characteristics of the toner obtained as described above were evaluated by the following method, and the results are shown in Table 1 below.

1-Plate-1-U (1) Molecular weight and molecular weight distribution: Dissolve 0.05 g of toner particles in 25 ml of tetrahydrofuran, measure the solution portion by gel permeation chromatography, and calculate based on the molecular weight of standard polystyrene. .

(2) Toluene insoluble matter: Put 1 g of toner and 5 g of filter aid (Radiolite #700, manufactured by Showa Kagaku Kogyo Co., Ltd.) into a 200 cc Erlenmeyer flask, add 100 cc of toluene, dissolve by shaking for 3 hours, and filter. Toluene insoluble fraction is reduced by weight%
) to measure.

(3) Fixing properties and non-offset properties: 5 g of toner and iron oxide powder carrier (manufactured by Nippon Tetsuko Co., Ltd., F-1)
00) was mixed with 100g, applied on paper using a simple magnetic brush method using a magnet, and passed through a heated roller of fluorocarbon resin/silicone resin (180℃) to form a mixture of 200n1 and 100g.
w/sec) and evaluate non-offset properties.

Further, a surface to which the toner is fixed is tested using a fastness tester using a soft bat, and the fixability is evaluated based on the image density before and after the test.

Comparative Example-1 80 g of styrene, 20 g of butyl acrylate, 3 g of 1,3-butylene glycol dimethacrylate, and 2.
A monomer mixture consisting of 6 g of 2'-azobisisobutyronitrile was polymerized by the same suspension polymerization method as in Example 1 above to produce a binder resin (Mn = 8,300, toluene insoluble content = 50%).

Next, Mitsubishi carbon black MA-4 was added to this binder resin.
After premixing by adding 5 g of 0.0, the mixture was melt-kneaded (temperature: 150° C., 70 rpm for 10 minutes), crushed, and classified according to a conventional method to obtain a toner having a particle size of about 13 μm.

The above toner was evaluated in the same manner as in Example-1,
The results are shown in Table 1 below.

Example 2 80 g of styrene, 20 g of butyl acrylate, 1.2 g of 1,3-butylene gellicol dimethacrylate, and 5 g of carbon black (manufactured by Mitsubishi Chemical Corporation, MA-100) were mixed using an attritor. Further, 8 g of 2,2'-azobis-(2,4-dimethylvaleronitrile) was added as a polymerization initiator to prepare a polymerizable vinyl monomer mixture, and the mixture was then subjected to suspension polymerization in the same manner as in Example 1 to obtain a toner. get (
However, the polymerization conditions were 70° C. x 2 hour leap), and then the evaluation was performed.

The evaluation results are shown in Table 1 below.

Example-3 80 g of styrene, 20 g of butyl acrylate, 1.7 g of 1,3-butylene glycol dimethacrylate, and
A polymerizable vinyl monomer mixture was prepared by mixing 5 g of carbon black (manufactured by Mitsubishi Kasei Corporation, MA-40) using an attritor, and then adding 4 g of 2,2'-azobisisobutyronitrile as a polymerization initiator. The following Example-1
Suspension polymerization was carried out at 85° C. for 2 hours in the same manner as above to obtain a toner. The evaluation results are shown in Table 1 below.

Example 4 80 g of styrene, 20 g of butyl acrylate, 1.4 g of 1,3-butylene glycol dimethacrylate, and 5 g of carbon black (manufactured by Mitsubishi Chemical Corporation, MA-40) were mixed using an attritor, Further Table-1 A compound was prepared and heated at 90°C in the same manner as in Example-1.
Suspension polymerization was carried out for 1 hour to obtain a toner. The evaluation results are in the table below.
Shown in 1.

Example 5 80 g of styrene, 20 g of butyl acrylate, 2.1 g of 1,3-butylene glycol dimethacrylate.

And carbon black (manufactured by Mitsubishi Kasei Corporation, MA-40)
A polymerizable vinyl monomer mixture was prepared by mixing 5 g using an attritor and further adding 6 g of 2,2'-azobisisobutyronitrile as a polymerization initiator. Suspension polymerization was carried out at 90° C. for 1 hour to obtain a toner. The evaluation results are shown in Table 1 below.

(Margins below) Symbols in the table above Fixability (Image density = percentage of toner particles remaining on the fixing surface) 20 - Image density over 80%, Δ: Image density 60-80%, ×: Image density Less than 60%, non-offset property: O: No offset phenomenon was observed on the fixing roller or the paper surface, which was very good. Δ: A slight offset phenomenon was observed on either the fixing roller or the paper surface, which was not suitable for practical use. No problem, ×
An offset phenomenon was observed on the fixing roller and on the paper surface, making it impractical. [Effects of the Invention] The toner for developing electrostatic images provided by the present invention is a mixture consisting of a polymerizable monomer, a crosslinking agent, and a colorant. Since it is obtained by suspension polymerization, the binder resin contained in the toner particles does not contain any intermediate molecular weight components that adversely affect fixing properties and non-offset properties. It has much superior toner properties compared to the conventional toner.

Claims (2)

[Claims] (1) Toner particles for developing electrostatic images obtained by suspension polymerization of a mixture containing at least a polymerizable vinyl monomer constituting a binder resin, a crosslinking agent, and a colorant, wherein A toner for developing electrostatic images, wherein the binder resin is a vinyl polymer having a number average molecular weight of 3,000 to 12,000 and containing 3 to 30% by weight of toluene insoluble matter. (2) The binder resin is a polymerizable vinyl monomer of 95 to
The toner for developing an electrostatic image according to claim 1, comprising 99.8% by weight of a crosslinking agent and 5 to 0.2% by weight of a crosslinking agent.