JPS607437A - Pressure fixable magnetic toner - Google Patents

Abstract

PURPOSE:To enhance dispersibility and stability against environmental conditions by mixing the magnetic particles on the surface of which a specified monomer has been polymerized, with a binder deformable with pressure. CONSTITUTION:A pressure-deformable binder, such as stearic or plamitic acid, is mixed with the magnetic particles, such as Fe3O4 or Fe2O3, coated with a polymer obtained by polymerizing on the surfaces of the particles a monomer represented by the formula shown here in which R is H or methyl, and R<1> is >=8C alkyl or alkenyl; such as n-octyl acrylate or 2-ethylhexyl acrylate. To polymerize the monomer on the surface of said particles, they are dispersed into water heated to 60-100 deg.C, and a polymn. initiator and the monomer are added to react it for 2-10hr with heating and polymer encapsulated magnetic particles can be obtained. They are mixed with the binder in a ratio of (30-60):(70-40) by weight and subjected to melting, kneading, and then, pulverizing.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic toner for pressure fixing having excellent dispersibility and good environmental stability of images.

Conventionally, magnetic toners for pressure fixing have been produced by mixing magnetic powder, optionally with various additives, and a binder component that can be deformed by pressure, for example, by a pulverization method or a spray dryer method.

However, there are still many drawbacks to this method of producing magnetic toner.Due to the poor dispersibility of the binder component and magnetic powder, the particle components after pulverization are not homogeneous, resulting in the production of magnetic toner. The amount of charge varies significantly depending on the usage environment.
As a result, image stability may become unstable. or,
Magnetic powder exposed from the surface of the magnetic toner may adversely affect development and transfer characteristics. In order to compensate for these drawbacks, a method has been proposed in which magnetic powder is coated with various resins in advance, so-called polymer encapsulation.
At present, these shortcomings have not yet been overcome.

The present invention aims to overcome the drawbacks caused by poor dispersibility of magnetic powder, and as a result of intensive studies in line with this purpose, the present inventors have found that long-chain acrylate is added to the surface of magnetic powder particles. By compressing the system 11i'71 and encapsulating it in a polymer, it was discovered that a polymer-encapsulated magnetic powder with good dispersibility could be obtained, and the present invention was completed.

(R is hydrogen or a methyl group, It is an alkyl group or an alkenyl group with 8 carbon atoms, and -) is polymerized on the particle surface, resulting in a magnetic powder that can be deformed by pressure. (R is hydrogen or a methyl group, B is an alkyl group or alkenyl group having 8 or more carbon atoms)
The monomers having the structure are acrylics such as n-octyl acrylate, 2-ethylhexyl acrylate, lauryl acrylate, tridecyl acrylate, stearyl acrylate, oleyl acrylate, linole acrylate, acrylic, and acrylate. Acid esters, n-octyl methacrylate,
2-ethylhexyl methacrylate, lauryl methacrylate, tridecyl methacrylate, stearyl methacrylate,
Methacrylic acid esters such as oleinomethacrylate, linol methacrylate, and surun methacrylate can be used alone or in combination of two or more of them.

In addition, monomers copolymerizable with the above monomers can be used as copolymerization components, for example, the general formula It is an argyl group, an alkenyl group, a cyclohexyl group, a benzyl group, having less than 8 carbon atoms, So-called acrylic esters or methacrylic esters which are alkoxyalkyl groups, hydroxyalkyl-dialkylaminoalkyl groups, aromatic vinyl soles such as styrene, paramethylstyrene, vinyltoluene, α-methylstyrene, vinyl acetate, Vinyl ethers such as vinyl propionate, vinyl chloride, vinylidene chloride, etc., rosin (vinyl monomer, nitrile vinyl monomers such as acrylonitrile, metacyclonitrile, amide monomers such as acrylamide, methacrylamide, dimethyl acrylamide, etc.) polymers, acrylic IN!, methacrylic acid, fumaric acid, itaconic acid, maleic acid
11 is a hydrogen or methyl group, 1t is a carbon number 8, is an alkyl group or an alkenyl group), and the proportion of the monomer used is 60 or more by weight of the total monomers used,
Particularly preferably, it is 70% by weight or more.

In addition, examples of the magnetic powder used in the present invention include 4.3 chichi oxide, 3.2 chichi oxide, iron zinc oxide, iron cadmium oxide, iron magnesium oxide, chichi powder, cobalt powder, nickel powder, soft ferrite, etc. Can be used alone or in combination
It can also be used in combination with the inside or above. Among them, a magnetic powder particularly suitable for the purpose of the present invention is 4.3: Dredkachitsu.

Furthermore, the binder deformable by pressure used in the present invention includes stearic acid, palmitic acid, and mimetic acid.
Higher fatty acids such as lauric acid and capric acid, higher aliphatic alcohols such as palmityl alcohol and stearyl alcohol, higher fatty acid metals such as aluminum stearate, magnesium stearate, zinc stearate, and salivary acid palmitate. Salts, higher fatty acid esters such as stearic acid glyceride, higher fatty acid amides such as octadecaneamide, hexadecanamide, tetradecaneamide, dodecanamide, octanamide, hexanamide, etc. Higher fatty acids binders such as beeswax, whalebone Animal wax such as wax, carnauba wax, palm wax,
Plant waxes such as wood wax, petroleum waxes such as paraffin wax and microcrystalline wax, wax binders such as synthetic waxes such as low molecular weight polyethylene and low molecular weight polypropylene, rosin, hydrogenated rosin, and rosin ester. rosin derivatives such as drying oil-type or semi-drying oil-type alkyds, rosin-modified alkyds, phenol-modified alkyds, alkyd resins such as styrenated alkyds, epoxy-modified phenolic resins, phenolic resins such as natural resin-modified phenolic resin III, amino Resin, silicone resin, polyurethane, urea resin, condensation resins such as polyester, copolymer oligomer of acrylic acid and long-chain alkyl acrylate, acrylic acid and 1% ffil
i Copolymerized oligomer with alkyl methacrylate, copolymerized oligomer with methacrylic acid and long-chain alkyl acrylate, copolymerized oligomer with methacrylic acid and long-chain alkyl methacrylate, copolymerized oligomer with styrene and long-chain alkyl acrylate, styrene and long-chain oligomer Copolymerized oligomers with chain alkyl methacrylates, ethylene-vinyl acetate copolymers, ethylene-vinyl alkyl ether copolymers, ethylene-maleic anhydride copolymers, vinyl resins such as polystyrene, polyvinyl acetate, and polyvinyl chloride; Polymers such as acrylic acid, polymethacrylic acid, and their diesters, rubbers such as isobutylene rubber, styrene-butadiene rubber, and nitrile rubber, polyolefins such as polyethylene and polypropylene, and ethylene-vinyl alkyl ether copolymers are used. Among these binders, it is preferable to use at least one type of high-grade aliphatic binder or wax-based binder from the viewpoint that the toner particles do not solidify at room temperature and can be deformed by pressure. Other types of binders are used in combination as required.

Next, as a method for polymerizing the monomer on the particle surface of the magnetic powder, the magnetic powder is usually dispersed in water and
Raise the temperature to 100°C, add a polymerization initiator and monomer,
Usually, fj removal is employed, in which the magnetic powder is heated for 2 to 10 hours to polymerize a monomer on the long side of the magnetic powder particles, dehydrated, and dried to obtain a polymer-encapsulated magnetic powder. In this case, the polymerization initiators used include, for example, potassium persulfate, ammonium persulfate, slight hydrogen oxide, and azobiscyanovalerate, and the amount added is generally 0.1 to 10 volts per monomer. The weight is 1 to 5, preferably 1 to 5. Regarding the monomer that is polymerized on the surface of the magnetic powder particles, -: 0.5 to 30% by weight (ζ is 0.5 to 30% by weight) to the magnetic powder used.
and preferably 1 to 10% by weight.

The polymer proceeds on the surface of the magnetic powder particles and forms a ring on the surface of the magnetic powder, but at the same time, some polymerization may also occur outside the long surface μ of the magnetic powder particles. The higher the proportion of 7f', the higher the proportion of polymerization on surfaces other than the surface of magnetic particles. do not. The amount of the monomer polymerized on the surface of the magnetic powder particles can be determined by dehydrating and drying the magnetic powder particles after the polymerization reaction in the above-mentioned water suspension state, and then adding an organic compound with a dissolving power such as acetone or tetrahydrofuran. After washing with a solvent to remove the polymer that is not bonded to the magnetic powder particles, it can be quantitatively determined by elemental analysis, and the dispersibility improves when this ratio is 0.3 weight factor or more to the magnetic powder. has been confirmed, sometimes 1% by weight
It is preferable to set it as above.

However, in actual use, polymerized polymer may exist on surfaces other than the surface of the magnetic powder particles (therefore, it is not necessary to wash the magnetic powder particles with an organic solvent).

30 to 600 to 60% by weight of the polymer encapsulated magnetic powder obtained as described above, and 0 to 4% of the binder darts described above.
The magnetic toner for pressure fixing of the present invention can be obtained by mixing with a zero weight meter, melting and cross-mixing, and then pulverizing the mixture. Additionally, additives can be added to the magnetic toner of the present invention for various purposes. Examples of such additives include metal complexes, charge control agents such as nigrosine, lubricating compounds such as polytetrafluoroethylene, and plasticizers such as dicyclohequinulfthalate. Furthermore, the magnetic toner of the present invention is mixed with carrier particles such as iron powder, glass beads, nickel powder, ferrite powder, etc., as required, and used as a developer for a drowsy latent image. It can also be used in combination with fine hydrophobic colloidal silica powder for the purpose of improving the free flow and mobility of the powder, and fine particles of a polishing agent such as cerium atomide for toner consolidation. .

The magnetic toner for pressure fixing configured in this way has a constant amount of toner in any single-use environment, which has not been achieved with the prior art, and always provides a clear image. , development performance and fixing performance are stable even when copying a large number of sheets.

The method of the present invention will be specifically explained below using a report and an actual case.

Production Example 1 Put 10 liters of distilled water and 300 liters of 4.3 iron oxide (r (P'I"-manufactured by 500 111 Kogyo) into a 21-sized three-day flask, and disperse in 9. and 4 liters.The internal temperature 70℃
After the temperature was raised to 0.75 g, 0.75 g of potassium persulfate was added as a heavy metal initiator, and 7.5 g of lauryl methacrylate and methacrylic I! I! 22 ethylhexyl (7.59 g) was mixed and added dropwise in 30 minutes using a dropping funnel. After completion of the dropwise addition, polymerization is carried out at 70°C for 2 hours, and then the temperature is further raised to 80°C and polymerization is carried out for 2 hours. After cooling, P was removed and the cake was dried, and free polymer and unreacted monomers of 4.3 oxidized chichichu were removed with acetone to obtain polymer-encapsulated 4.3 oxidized chichichu. As a result of elemental analysis of this 4.3 iron oxide and converting the amount of polymer from its carbon content, it was confirmed that the amount of adhesion was 2.0% by weight compared to 4.3.

Production Example 2 Monomer tJ polymerized by the same polymerization method as Production Example 1
Polymerization was carried out with the amounts of E being 1.17 g of lauryl methacrylate and 1.0 g of 2-ethylhexyl methacrylate. Polymer-encapsulated 4.3 iron oxide was obtained by the same procedure as in Production Example 1 below. The material to be cleaned at this time was 0.5 heavy bite.

Production Example 3 Using the same monopolymerization method as in Production Example 1, the monomers to be polymerized were mixed with 3 g of lauryl methacrylate and methacrylic NI.
/2 ethylhexyl (3 g).

Polymer encapsulation 4 was performed in the same manner as in Production Example 1.
．． Trioxide chichi was obtained. The amount of coating at this time was 1.2 tons.

41 Intermediate E2 Li 4 Polymerization was carried out using the interstitial polymerization method as in Production Example 1, using 10.5 g of oleyl methacrylate, 3.0 g of styrene, and 1.5 g of methacrylic acid as the monomers to be polymerized. Polymer encapsulation 4.
Obtained 3 cities. The amount of adhering acid at this time was 2.3% by weight.

Production Example 1 Polymerization was carried out using the same polymerization method as in Production Example 1 to obtain 15% monomer and monomer methyl methacrylate. The following is the same as Production Example 1! According to the conditions, 4.3 oxide was obtained by encapsulation with reformer. The coating amount at this time was 3.0
It was @'4r%.

Production Example 2 Polymerization was carried out using the same polymerization method as in Production Example 1, using normal butyl methacrylate 15 as the monomer and monomer to be polymerized. Polymer-encapsulated 4.3 iron oxide was obtained by the same operation as in the full production process.

The coating amount at this time was 2.9% by weight.

Example 1 Polymer encapsulation obtained in Production Example 1 4.3 Chichi Oxide 600 heavy acid wax (trade name, Microcrystalline Wax manufactured by Mobile Sekiyu) 300 heavy acid ethylene-vinyl acetate copolymer resin (trade name, Evaflex 2)
20, Mikata Polychemical) 40 parts by weight Metal complex dye (trade name, Zapon Fast Black B, C, 1, A)
c1dBlack63, BA8 F+E'M') 2
Heavy Acid Part The above materials were thoroughly mixed in a mixer and melted and kneaded at 150° C. using a single roll and two rolls. After the kneaded material is left to cool naturally, it is coarsely ground with a coarse grinder, then finely ground with a jet mill, and further separated and sucked using an air classifier to obtain a particle size of 10 to 20μ.
A magnetic toner was obtained.

Example 2 Polymer encapsulation obtained in Production Example 2 4.3 Chichi Oxide 60-weight back wax (trade name, Microcrystalline Wax, Mobil Oil M) 30-weight 1 part ethylene-vinyl acetate copolymer resin (trade name, Evaflex 2
20, Mikata Polychemical) 40 Heavy 'Q' metal complex dye (@product name, Zapon Fast Black B, C8I,
Ac1d 131ack63, manufactured by B A 81”)
2 parts by weight of ingredients listed below! An amphoteric toner was obtained in the same manner as in Blood Example 1.

Example 3 Polymer encapsulation obtained in Production Example 3 4.3 Iron oxide 600 heavy acid wax (trade name, Microcrystalline wax, manufactured by Mopil Petroleum) 30 heavy: Yellow lead ethylene-vinyl acetate (polymerized fat (product) Name, Evaflex 220, made by Mikata Polychemical) 4 (lti% part metal lead metal complex dye name, Zapon Fast Black B, (, I
, Ac1d 63, L3AS turbidity) Double acid part A magnetic toner was obtained using the above materials in the same manner as in 4 rows (2).

Example 4 Polymer encapsulation obtained in Production Example 4 4.3 Iron oxide 60 parts by weight 4 1 parts by weight (trade name, Microcrystalline Wax, manufactured by Mopil Petroleum) 30 parts by weight Ethylene-vinyl acetate copolymer resin (product) Name: Evaflex 2
201 manufactured by Mitsui Polychemicals) 40 heavy metal complex dyes (product name, Zapon Fast Black B, C, I, Ac
1d Black B, manufactured by BASF) Double acid part A magnetic toner was obtained using the above material in the same manner as in Example 1.

Example 5 Polymer encapsulated 4.3 iron oxide obtained in Preparation Example 1
60 overlapping polyethylene (product name: Hiwax 220P.

(manufactured by Mikata Petrochemical) 40 parts by weight ethylene-ethyl acrylate copolymer resin (trade name, A
-704, Mikata Polychemical) 40 parts by weight Metal complex 1
Dye (product name, Zapon Fast Black B, C, 1,
Ac1d 131ack 63, manufactured by BASF) 2 parts by weight The above material was subjected to the same operation as in Example 1 to obtain a magnetic toner.

Comparative Example 1 4.3 parts by weight of Chichi Oxide (trade name, EP'r-500, manufactured by Toda Kogyo) 60 parts wax (product name, Microcrystalline Wax, manufactured by Mopil Petroleum) 30 parts by weight Ethylene-vinyl acetate copolymer resin (Product name: Evaflex 2
20, made by Sankata Polychemical) 4 (1 knee-i% part metal complex dye (trade name, Zapon Fast Black B, (, I
, Ac1d Black63, manufactured by BASF) 2 layers 1
A magnetic toner was obtained using the above materials in the same manner as in Example 1.

Comparative Example 2 Polymer encapsulation encapsulated in Comparative Production Example 1 4.3 iron oxide 60 tons 14 parts wax (trade name, Microcrystalline Wax, manufactured by Mopil Petroleum) 30 parts ethylene-vinyl acetate copolymer resin (trade name , Evaflex 2
20, three pieces made of polychemical) 40'! Eibe Metal Complex Dye (Product Name, Zapon Fast Black B, CJ, Ac
1d Black 63, manufactured by BASF) 2 parts by weight Test Method and Results: Using the above material, a magnetic toner was obtained in the same manner as in Example 1.

Using the magnetic toner obtained in Example 1.2.3.4.5 and Ratio Series 1.2.3, an unfixed image was obtained by copying on a commercially available product, developing it using a hawk, and transferring it. When this was fixed using a steel roll pressure fixing device that applied a force of 15 kg/d, it was possible to obtain an image with extremely good fixing properties (no capri). A copy test was conducted under the conditions of 25°C, 65% RH, 35°C, 85°C, 11.H, and the charge amount and image density were determined at the initial stage, at 5,000 sheets, and at 10,000 sheets.The results are shown in Table 1. ,
As shown by these results, in the example of the present invention, there was no change in the amount of charge and no change in image flexibility even after the 10,000-sheet durable copy test. On the other hand, in the comparative example, the charge amount changed widely and the image density also decreased widely.

Comparative Example 3 Polymer encapsulation 1% in Comparative Preparation Example 2 4.3
Iron oxide 60 parts wax (product name, Microcrystalline wax, manufactured by Mopil Oil) 30 parts ethylene-vinyl acetate copolymer resin (product name, Evaflex 2)
20, manufactured by March 2 Polychemical) 40 overlapping parts Metal complex dye (trade name, Zapon Fast Black I3, C, I,
Ac1d Black 63 (manufactured by BASF) Double clear part A magnetic toner was obtained using the above material in the same manner as in Example 1.

Claims (1)

[Claims] Magnetic powder obtained by polymerizing a monomer represented by (where 几 is hydrogen or a methyl group, and d is an alkyl group or alkenyl group having 8 or more carbon atoms) on the particle surface is deformed by pressure. Magnetic toner for pressure fixing mixed with a suitable binder.