JPH0727277B2 - Developer - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a developer that visualizes an electric latent image or electric signal in electrophotography, electrostatic recording, etc., and is improved in fixing property, cleaning property, temporal stability, and the like. The present invention relates to powder developers generally called toner and dry ink.

2. Description of the Related Art Generally, a typical recording method using a developer composition called by a name such as toner or dry ink is an electrophotographic method. Therefore, the electrophotographic method will be described as an example.
In electrophotography, an electrostatic latent image formed on the surface of a photoconductive photoreceptor is developed with charged colored fine particles called toner,
Then, recording is performed by transferring the toner image onto paper or the like and further fixing the toner with heat, pressure, solvent, or the like. The toner is composed of polymer substances, colorants, other additives, etc., and is usually fine particles of about 1 μm to about 30 μm. Its characteristics are that the physical properties of the binder resin, which is the largest constituent component of the toner, are Greatly reflected. In order to fix the toner with lower energy, both in the case of heat fixing and in the case of pressure fixing, the polymer material as the binder resin has a relatively low molecular weight and a low glass transition temperature and softening point. Is preferred. From the viewpoint of toner productivity, it is preferable that the binder resin has a low molecular weight. However, if a polymer material having a relatively low molecular weight or a polymer material having a wide molecular weight distribution containing a low molecular weight component is used as the binder resin of the toner, various troubles will be induced when the toner is repeatedly used. .

For example, in the case of a two-component developer, the toner is likely to stick to the surface of the carrier particles, the life of the developer is shortened, and the image quality is deteriorated. Even in the case of a one-component developer that does not use a carrier, the toner is likely to stick to the developing device and filming, which causes a variation in image quality. Further, when cleaning the toner remaining on the photoconductor, the toner is easily filmed on the photoconductor or the cleaner, and the reliability of the electrophotographic recording device such as a printer is greatly impaired. Further, in the contact type fixing method such as the heat roll fixing method, offset of toner to the fixing device becomes a problem. Furthermore, problems such as storage stability of the hard copy, that the hard copy after printing easily sticks to other things such as a film, are likely to occur. It is often attempted to introduce a polar group into the toner binder resin for the purpose of controlling the charge of the toner, but since the polar group generally increases the adhesiveness, the problems such as filming described above are further promoted. Will be done.

Therefore, in order to achieve both processing performance and stability over time, be careful not to excessively reduce the molecular weight of the binder resin of the toner, and further add external additives such as silica and releasable components such as silicone oil and wax to the toner. The current situation is to deal with it by using it as an internal additive.

Problems to be Solved by the Invention However, these methods are not always effective in improving the initial performance, and it is difficult to uniformly control the dispersed state of the additive, which causes a new trouble. Will end up. Therefore, the initial performance of the toner and the long-term stability with time cannot be controlled to a level that can be sufficiently satisfied.

Therefore, an object of the present invention is to provide initial performance and initial stability in terms of (1) fixability, (2) cleaning property, (3) charging, developing property, (4) filming resistance, deterioration resistance and (5) storage stability. It is to provide a developer having good stability over time.

Means and Actions for Solving Problems As a result of intensive studies by the present inventor, a polymer having a higher aliphatic chain at a molecular chain end by polymerizing a monomer in the presence of a polymerization initiator containing a higher aliphatic chain. It was found that the above-mentioned problems can be improved or eliminated by producing the above-mentioned product and containing it as a binder resin component of the toner, and completed the present invention.

Therefore, the developer of the present invention is produced by polymerization of a monomer in the presence of a polymerization initiator containing a higher aliphatic chain and has a higher aliphatic chain at the terminal of the molecular chain, and has a number average molecular weight of 10,000 or less. It is characterized in that the coalescence is contained as a binder resin component of the toner. Here, the higher aliphatic chain means an aliphatic group having about 6 or more carbon atoms. Therefore, the polymer having a higher aliphatic chain at the molecular chain end in the present invention has an aliphatic group having about 6 or more carbon atoms at one or both ends of the polymer chain constituting the polymer. In addition, in aliphatic homo- and copolymers such as polyethylene or polypropylene, not only the molecular chain terminals but all the molecular chains are naturally composed of aliphatic chain components. Aliphatic polymers consisting of only aliphatic chains,
It is not included in the category of polymers having a higher aliphatic chain at the terminal of the molecular chain in the present invention.

Further, for example, an aliphatic polymer such as polyethylene polypropylene, a block copolymer of an aliphatic compound such as paraffin wax and a styrene resin, an acrylic resin, a diene resin, a polyester, stearic acid, stearyl alcohol, or the like. Styrene-based resins, acrylic resins, polyesters and the like whose terminals are modified with a higher aliphatic compound contain a higher aliphatic chain component at the end of the molecular chain, and thus, as in the case of the polymer of the present invention, It can be used to achieve the above object. However, these polymers have drawbacks in their production method. For example, although a living block method can provide a homogeneous block copolymer, it is extremely difficult to produce it on an industrial scale and at low cost. In addition, the block copolymer and the terminal-modified polymer as described above can be obtained by various polymer reactions, coupling reactions, and mechanochemical reactions, but a homogeneous reaction cannot be expected, and therefore a homogeneous product Is difficult to obtain. Therefore, these are not included in the category of the polymer having a higher aliphatic chain at the terminal of the molecular chain in the present invention.

The polymer having a higher aliphatic chain at the terminal of the molecular chain in the present invention can be industrially synthesized at low cost by polymerizing a monomer in the presence of a polymerization initiator containing a higher aliphatic chain.

The polymerization initiator is decomposed and, after radical formation, is finally incorporated into the polymer as a molecular chain terminal constituent of the polymer.Therefore, when a polymerization initiator containing a higher aliphatic chain is used, The polymer having a higher aliphatic chain component can be obtained in an extremely homogeneous state at a low cost, and the degree of freedom in molecular design becomes very high, which is convenient for the present invention.

As the polymerization initiator, azo-based, peroxide-based substances, etc. are known, but in the present invention, basically any structure of the polymerization initiator is a polymerization initiator containing a higher aliphatic chain. Can be used even. When the polymerization initiator effectively used in the present invention is exemplified by a peroxide type compound as a representative example, for example, dimyristyl peroxydicarbonate, t-hexyl peroxy neodecanoate,
Examples thereof include t-hexyl peroxylaurate, di-2-ethylhexyl peroxydicarbonate, octanoyl peroxide, decanoyl peroxide, lauroyl peroxide, stearoyl peroxide, myristoyl peroxide.

The amount of the polymerization initiator used in the present invention may be various amounts depending on the number average molecular weight of the obtained polymer. That is, in the present invention, since the higher aliphatic chain component of the polymerization initiator is incorporated at the end of each molecular chain, the lower the number average molecular weight of the target polymer, the higher the content concentration of the higher aliphatic chain. Will be higher. Therefore,
In the present invention, the number average molecular weight of the obtained polymer, depending on the type of the monomer, it is possible to use various amounts, for example, in the case of obtaining a styrene polymer number average molecular weight 3000 ~ 4000, If a few wt% of the polymerization initiator is used with respect to the monomer, the content of the higher aliphatic chain in the obtained polymer is the same as that in the case where a low-molecular weight polypropylene wax is added to the polymer, for example, about 2%. It becomes the content.

In the present invention, the polymer having a higher aliphatic chain at the terminal of the molecular chain is an acrylic acid alkyl ester such as styrene, methyl acrylate, butyl acrylate, 2-ethylhexyl acrylate or methyl methacrylate, n-
It is preferable to contain methacrylic acid alkyl ester such as butyl methacrylate as a monomer component in order to comprehensively control the toner characteristics. If necessary, α-
Styrene derivatives such as methylstyrene, aminostyrene, vinyltoluene, chlorostyrene, vinylbenzene sulfonate, anionic monomers such as acrylic acid, methacrylic acid, maleic anhydride, dimethylaminoethyl methacrylate, vinyl pyridine, etc., Alternatively, cationic monomers such as quaternary chlorides, dienes such as butadiene and isoprene, and other vinyl polymerizable monomers in general can be contained as a comonomer component.

Further, in the present invention, in order to bring out the effect sufficiently, it is desirable to set the number average molecular weight (Mn) of the polymer having a higher aliphatic chain at the terminal of the molecular chain to 10,000 or less. The value of the number average molecular weight (Mn) is the number average molecular weight calculated when measuring the molecular weight distribution by the GPC method, and means the molecular weight value based on the polystyrene.

Generally, when a polymer having a low molecular weight is used as the toner binder resin, as described above, it is advantageous in terms of fixability and a toner manufacturing method, but filming and sticking are likely to occur, and there is a problem in stability over time of the toner and the system. Prone to On the other hand, in a polymer in which a higher aliphatic chain that is a releasing component is present at the end of the molecular chain, the lower the number average molecular weight of the polymer, the higher the proportion of the higher aliphatic portion, and therefore the release The effect as a sexual component becomes remarkable. Therefore, it is not necessary to specify the molecular weight of the polymer having a higher aliphatic chain at the terminal of the molecular chain thereof in the present invention, from the viewpoint that the higher aliphatic chain, which is a releasing component, can be stably dispersed in the toner. Although not always necessary, it is desired that the number average molecular weight be about 10,000 or less, and more preferably about 5,000 or less for the above reason. The glass transition temperature (T
g) or softening point is about 50 ℃ or higher, preferably about 55 ℃
To about 75 ° C is desirable.

In the present invention, the binder resin of the toner may be composed of only the polymer, but if necessary, a styrene resin, an acrylic resin, a polyester, an epoxy resin,
Polyamides, polyurethanes and urethane compounds, petroleum resins, silicone resins, fluororesins, phenolic resins, polyethylene, polypropylene, ethylene / vinyl acetate copolymers, paraffin waxes, ester waxes and other conventionally known natural and synthetic homopolymers and copolymers. You may use together a polymer, a polymer alloy, waxes, etc.

In the toner, if necessary, carbon black, magnetite, colorants such as organic chromatic dyes, charge control agents, conductivity control agents, antioxidants, magnetic powders, release agents,
Various additives such as a reinforcing filler can be contained.

Further, well-known external additives for toner such as silica, carbon black, alumina, titanium oxide, zinc oxide, fine polymer powder, tin oxide, boron nitride, higher fatty acid and derivatives thereof such as metal salts thereof can be used.

The toner according to the present invention can be produced by any method such as a kneading and pulverizing method, a spray dry method, a direct polymerization method, and the like. It can also be used as an agent. When magnetic powder is mixed in the toner and used as a magnetic toner, not only the development and visualization of an electric latent image but also a magnetic latent image such as a magnetographer can be developed.

Action The binder resin of the toner in the present invention, as described repeatedly,
A polymer having a relatively low molecular weight (number average molecular weight Mn of about 10,000 or less) having a higher aliphatic chain of about 6 or more carbon atoms at the end of its molecular chain, and its effect as a releasing component of the higher aliphatic chain. As a result, even when the polymer itself has a low molecular weight and filming or sticking trouble is likely to occur, these problems can be improved or eliminated.
Substantially, since each higher molecular weight chain has a higher aliphatic chain, the dispersion of the higher aliphatic component in the toner is uniform at the molecular level, and the toner characteristics, system characteristics, and temporal stability are Improve dramatically.

Regarding the fixability, not only the binder resin of the present invention itself effectively works to improve the fixability rheologically, but also polypropylene, polyethylene, wax,
Oilless heat roll fixing is possible without internally adding silicone oil or the like to the toner. It was also confirmed that the cleaning property of the toner was extremely good.

Furthermore, when waxes, oils, olefin polymers, compounds having a higher aliphatic group, etc. are added to the toner,
Improve the dispersibility of those additives.

Examples Hereinafter, the effects and contents of the present invention will be described with reference to representative examples, but of course the present invention is not limited to these examples.

In the examples, “parts” means “parts by weight” unless otherwise specified.

Example 1 ○ Polystyrene resin polymerized with lauroyl peroxide as a polymerization initiator (Mn (number average molecular weight): 4,800, Mw
(Weight average molecular weight): 11,500) 50 parts ○ Styrene / butyl acrylate copolymer (Mn: 16,00
0, Mw: 43,000) 40 parts ○ Carbon black 10 parts Average particle diameter d50 by melt-kneading, pulverizing and classifying the above components
= 10 μm toner was obtained. 0.8 wt% of fine powder of hydrophobic silica was added to this toner, and the toner was further combined with a ferrite carrier having a particle diameter of about 80 μm coated with a polymethylmethacrylate copolymer to prepare a developer composition.

About the obtained developer composition, Fuji Xerox Co., Ltd.
A running test was carried out on a FX-2300 copier made by the company. The results are shown in Table 1.

Comparative Example 1 ○ 50 parts polystyrene resin (Mn: 4,100, Mw: 10,800) polymerized with azobisisobutyronitrile as a polymerization initiator ○ 40 parts styrene / butyl acrylate copolymer (same as Example 1) ○ carbon black 10 parts Toner having an average particle diameter d50 = 10 μm was treated in the same manner as in Example 1 except that the polystyrene resin in Example 1 was replaced with a polystyrene resin polymerized with azobisisobutyronitrile as a polymerization initiator. (A) was obtained.

○ 50 parts polystyrene resin (Mn: 6,300, Mw: 14,200) polymerized with di-t-butyl peroxide as a polymerization initiator ○ 40 parts styrene / butyl acrylate copolymer (same as Example 1) ○ 10 parts carbon black A toner having an average particle diameter d50 = 10 μm was treated in the same manner as in Example 1 except that the polystyrene resin in Example 1 was replaced with a polystyrene resin polymerized with di-t-butyl peroxide as a polymerization initiator. b) was obtained.

Toners (a) and (b) were made into a two-component developer by the same method as in Example 1, and both were subjected to a running test with an FX-2300 copying machine manufactured by Fuji Xerox Co., Ltd. The results are shown in Table 1.

Example 2 50 parts styrene / n-butyl methacrylate / acrylic acid copolymer (Mn: 4,700, Ww: 28,000) polymerized with stearoyl peroxide as a polymerization initiator ○ Styrene / n-butyl methacrylate copolymer (Mn :13
5,000, Mw: 482,000) 50 parts ○ Metallic dye 2 parts ○ Carbon black 10 parts The above components were treated in the same manner as in Example 1 to obtain a toner having an average particle diameter of 12 μm. To this toner, 0.7% of hydrophobic silica fine powder was added and mixed, and a developer was prepared by combining it with a ferrite carrier coated with a modified silicone resin and having a particle size of about 70 μm. Fuji Xerox Co., Ltd. FX-2830 Copier 200 The initial running test of continuous copying was performed. The results are shown in Table 2.

Comparative Example 2 Styrene / n-butyl methacrylate / acrylic acid copolymer polymerized with stearoyl peroxide of Example 2 50
Part was replaced with 50 parts of a low molecular weight styrene / n-butyl methacrylate / acrylic acid copolymer (Mn: 5,300, Mw: 32,000) polymerized with benzoyl peroxide as a polymerization initiator, and in the same manner as in Example 2 By processing, a toner (a) having an average particle size of 12 μm was obtained.

Add 2 parts of lower molecular weight polypropylene of the above composition,
Kneading, pulverizing and classifying in the same manner as in Example 1, average particle size 12 μm
Toner (b) was prepared. Using these toner (a) and toner (b), a two-component developer having the same formulation as in Example 2 was prepared, and a running test was conducted by the same method.
The results are shown in Table 2.

Example 3 1.0 wt% of hydrophobic silica fine powder was added to the toner of Example 2 to prepare a one-component developer.

Comparative Example 3 Toner (a) of Comparative Example 2 was added with 1.0 wt% of hydrophobic silica fine powder.
% And mixed to prepare a toner used as a one-component developer.

A running test was conducted on the toners of Example 3 and Comparative Example 3 with a modified FX-2300 copying machine equipped with the one-component developing machine shown in FIG. 1, and the toner of Comparative Example-3 had a running test of about 3000 sheets. Then, the image density decreased, and further, the fog increased, and abnormalities such as uneven development were observed. When the toner in the copying machine was inspected, toner filming was found on the toner carrier, the layer regulating member and the like in the developing machine. When the toner was observed with an electron microscope, pulverization and agglomeration of coarse particles were simultaneously progressing. During the test, cleaning trouble occurred, and at that time, some toner filming was observed on the surface of the photoconductor and the blade cleaner part.

On the other hand, the toner of Example-3 was subjected to the running test of 10,000 sheets,
There was no abnormality, and a good copy of the image was always obtained.

In the copying machine of FIG. 1, 1 is an electrostatic latent image carrier,
2 is a developing machine, 3 is a hopper, 4 is color toner, 5 is a toner carrier, 6 is a bias power source, 7 is a toner layer regulating member, 8 is a power source, and 9 is an electrostatic latent image. The toner carrier 5 is composed of a composite roll of carbon black / glass fiber / thermosetting resin and has an electric resistivity of about 10 ¹⁰ Ωcm. The pressure was applied at about 1 kg / cm ² .

Further, the distance between the toner carrier 5 and the electrostatic latent image carrier 1
The toner carrier was set to 300 μm, the peripheral speed was 100 mm / sec, a DC bias was 300 V, an AC bias was 1.8 KVp _- p, and a current of 2.5 KHz was applied to develop.

Example 4 styrene / dimethylaminoethyl methacrylate / butyl acrylate copolymer polymerized with decanoyl peroxide (Mn: 6,700, Mw: 23,000) 50 parts ○ quaternary ammonium salt 1 part ○ ferrosoferric oxide fine powder 50 parts The above components were melt-kneaded, pulverized and classified to obtain a magnetic toner having a particle size of 9 μm. Add carbon black powder to this toner
0.7 wt% was added externally to prepare a magnetic one-component toner. Running test of this toner with a magnetic one-component developing machine and a modified FX-2300 copier equipped with a negatively chargeable organic photoconductor,
During the 00-sheet repeated copying test, excellent image quality was obtained.

Example 5 A styrene / 2-ethylhexyl acrylate / maleic anhydride copolymer (Mn: 8,800, Mw: 43,00) polymerized with dimyristyl peroxydicarbonate as a main polymerization initiator.
0) 80 parts ○ Styrene / 2-ethylhexyl acrylate / divinylbenzene copolymer (gel fraction ~ 70%) 20 parts ○ Polyethylene wax 2 parts ○ Carbon black 10 parts The above components are kneaded, crushed, classified, and average particle size A toner having a diameter of 12 μm was prepared. To this toner, a fine powder of hydrophobic silica was added.
7wt%, 0.5wt% methylmethacrylate modified resin fine powder
External mixing was performed, and a ferrite carrier having a particle diameter of 80 μm coated with a methyl methacrylate copolymer was further added to obtain a two-component developer.

This developer was tested for continuous copying of 200,000 sheets with an FX-2830 copier, and it was possible to obtain extremely stable and good image quality that did not change with the environment and time. The fixing and cleaning properties were of course good, and no other abnormalities were observed.

Example 6 O-Methylstyrene / styrene / butyl acrylate copolymer (Mn: 2,6) polymerized with lauroyl peroxide
00, Mw: 7,100) 50 parts ○ Styrene / butyl acrylate copolymer (same as in Comparative Example 1) 40 parts ○ Carbon black 10 parts ○ Contained dye 2 parts Toner having a particle size of 9 μm after kneading, pulverizing and classifying the above components Was prepared. 1.0 wt% of hydrophobic silica fine powder was added to this toner.
%, And 1.0 wt% of fine powder of methyl methacrylate-modified resin were externally added and mixed, and a two-component developer was prepared using ferrite having a particle size of 70 μm as a carrier.

This developer was loaded into the FX-2300 copying machine described above, and a running test was conducted on 20,000 sheets continuously, but very good image quality was obtained. The minimum fixing temperature was 145 ° C, and the fixing property was also very good.

EFFECTS OF THE INVENTION The developer composition of the present invention has a higher aliphatic group at the end of a molecular chain produced by polymerization of a monomer in the presence of a polymerization initiator containing a higher aliphatic chain as a binder resin component of the toner. Since a polymer having a number average molecular weight of 10,000 or less is used,
Toner fixing property, cleaning property, charging. It has excellent initial performance and stability over time in terms of developability, filming resistance, deterioration resistance and storage stability. In particular, the polymer having a higher aliphatic chain at the terminal of the molecular chain is one selected from styrene, acrylic acid alkyl ester and methacrylic acid alkyl ester, or two kinds of styrene and acrylic acid alkyl ester or methacrylic acid alkyl ester. The above-mentioned effects are excellent when the compound has a number average molecular weight of 10,000 or less.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view of a developing portion of a copying machine using running tests of the developer compositions of Example 3 and Comparative Example 3. 1 ... Electrostatic latent image holder, 5 ... Toner carrier, 7 ... Toner layer regulating member.

Claims (2)

[Claims] 1. A toner having a number average molecular weight of 10,000 or less and having a higher aliphatic chain at a terminal of a molecular chain, which is produced by polymerizing a monomer in the presence of a polymerization initiator containing a higher aliphatic chain. A developer containing the binder resin component as described above. 2. The polymer having a higher aliphatic chain at the terminal of the molecular chain is one selected from styrene, acrylic acid alkyl ester and methacrylic acid alkyl ester, or styrene and acrylic acid alkyl ester or methacrylic acid alkyl ester. The developer according to claim 1, wherein the developer contains two kinds as a monomer component.