JP3136833B2 - Heat and pressure fixing toner - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a toner used for developing electrophotography and the like. More particularly the present invention relates to a toner for heating and pressurizing fixing which is fixed by the application of heat and pressure.

[0002]

2. Description of the Related Art In the process of developing an image such as an electrophotograph on copying paper, fixing is performed in order to convert an unstable toner image transferred on the copying paper into a stable permanent image.
This is a step in which the toners and the toner and the copy paper are strongly linked and fixed. As fixing means, heat and pressure,
Pressure, light and the like. In the field of electrophotographic copying, heat efficiency is good, and high speed is possible.
A fixing method using heat and pressure using a heat roll is mainly used.

In the fixing method using heat and pressure, an unfixed image passes between heat rollers and is heated and pressed.
In this process, the toner melts, enters the fibers of the paper, and is fixed. At this time, if the toner is excessively melted, the image is crushed at the time of fixing, and it is difficult to reproduce fine lines and the like. In addition, poor fixability causes offset and the like. Also,
In order to preserve a copied image, it is desired that the image has high fixing strength and excellent vinyl chloride resistance.

Various attempts have been made mainly to select a binder resin in order to improve the fixability of the toner. However, in order to improve the fixability of the toner, the clarity of the image, or the storage property of the toner, the use of a resin has been attempted. The required characteristics do not always match, and none satisfy all the requirements. From the viewpoint of adding an additive to the toner other than selecting the resin, for example, a hardener and a curable compound encapsulated in separate capsules are added to the toner, and the capsule is crushed when pressurized and cured. JP-A-58-95353 discloses a method in which an agent and a curable compound are reacted and polymerized. In this method, a capsule A containing a curable compound such as isocyanate and a capsule B containing a curing agent such as an active hydrogen donor are mixed with a developer, and both capsules are crushed by pressure during fixing to cause a curing reaction. The method relates to a toner that is fixed by pressure.

[0005]

SUMMARY OF THE INVENTION In view of the above circumstances, it is an object of the present invention to provide a toner having excellent fixability, and excellent offset resistance and vinyl chloride resistance.

[0006]

That is, the present invention provides a wet type
Granulated by granulation method, resin, colorant, polyisocyanate
Isocyanate group relates to a toner for heat-pressure fixing comprising a polyvalent isocyanate derivative and an active hydrogen donor is protected by a blocking agent of the sulfonate compound.

The curable compound used in the present invention is a polyvalent isocyanate derivative in which the isocyanate group of the polyvalent isocyanate is protected by a blocking agent. As the polyvalent isocyanate, diisocyanates: m-phenylene diisocyanate, p-phenylene diisocyanate, 2,6-
Tolylene diisocyanate, 2,4-tolylene diisocyanate, naphthalene-1,4-diisocyanate, diphenylmethane-4,4'-diisocyanate, 3,3'-
Dimethoxy-4,4'-biphenyl diisocyanate,
3,3′-dimethyldiphenylmethane-4,4′-diisocyanate, xylylene-1,3-diisocyanate,
4′-diphenylpropane diisocyanate, trimethylene diisocyanate, hexamethylene diisocyanate, propylene-1,2-diisocyanate, butylene-1,2-diisocyanate, ethylidene diisocyanate, cyclohexylene-1,2-diisocyanate,
Cyclohexylene-1,4-diisocyanate, toluylene diisocyanate, triphenylmethane diisocyanate, etc., triisocyanate: 4,4 ′, 4 ″ -triphenylmethane triisocyanate, polymethylene polyphenyl isocyanate, etc., tetraisocyanate:
Polyisocyanate prepolymer such as 4,4'-dimethylphenylmethane-2,2 ', 5,5'-tetraisocyanate: hexanetriol adduct of hexamethylene isocyanate, catechol adduct of 2,4-tolylenediisocyanate And hexanetriol adduct of tolylene diisocyanate, trimethylolpropane adduct of tolylene diisocyanate, and trimethylolpropane adduct of xylylene diisocyanate.

The isocyanate group is a very reactive functional group, which reacts immediately when active hydrogen such as -NH ₂ or -OH is present, but does not react if protected with a blocking agent. In the present invention, the isocyanate group of the polyvalent isocyanate is protected by a blocking agent which is released at a certain temperature and added to the toner, and the isocyanate group is released by heating at the time of fixing to form a polymer with an active hydrogen donor. Things.

As blocking agents for protecting isocyanate groups, lactams, phenols, amides, sodium acid sulfite, aromatic secondary amines, tertiary alcohols,
Heterocyclic compounds, hydrocyanic acid, sulfite, and the like. Specifically, lactams: β-propiolactam, γ-butyrolactam (2-pyrrolidone), δ-valerolactam (piperidone), ε-caprolactam, heptactam, α-pyridone, etc., and derivatives or substituted products thereof, Phenols: phenol, naphthol, hydroxyanthracene, resorcin, hydroquinone, catechol, p-hydroxybenzoic acid, o, m, p-cresol, o, m, p-chlorophenol, o, m, p-aminophenol, o, m, p-nitrophenol, salicylic acid, eugenol, isoeugenol, anethole,
Vanillin, thymol, safrole, 4-n-hexylresorcinol, 2,4-dichlorophenoxyacetic acid and the like, and derivatives or substitutes thereof, amides or imides: benzamide, butylamide, N-ethylacetanilide, benzanilide, aceto-p- Toluidide,
Phthalimide, etc., and derivatives or substituted products thereof, sodium acid sulfite, sodium hydrogen sulfate, aromatic secondary amine: N-methylaniline, N-ethylaniline, dibenzylamine, diphenylamine, 1,2-dihydroquinoline, indole And their derivatives or substitutions, tertiary alcohols: tert-butyl alcohol and derivatives or substitutions, hydrocyanic acid, sulfites: sodium sulfite, lead sulfite, barium sulfite, nickel sulfite, copper sulfite, etc., and derivatives or substitutions thereof Body, heterocyclic compounds: pyrrole, carbazole,
Examples include pyrazole, imidazole, purine, and the like, and derivatives or substitutes thereof.

The case where ε-caprolactam is used as the blocking agent will be described. As shown in the following formula, the isocyanate and the blocking agent react at around 80 ° C. to produce a curable compound. When the curable compound is heated to around 150 ° C., the blocking agent is released and the isocyanate group is released.

[0011]

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Free isocyanate groups react immediately with active hydrogen to form polymers. If the polyvalent isocyanate protected by ε-caprolactam is contained in the toner,
At the same time as the toner transferred to the paper is melted by heating and enters the paper fibers, the isocyanate is liberated and polymerized with the active hydrogen donor to form a polymer as the paper fibers are involved. High fixing strength can be obtained.

The polyvalent isocyanate derivative used in the present invention is preferably one in which all of the isocyanate groups are protected by a blocking agent, but may have one free isocyanate group per molecule. Those having two or more free isocyanate groups in one molecule are not used in the toner of the present invention because they undergo a polymerization reaction with active hydrogen in the production process.

The active hydrogen donor (curing agent) of the present invention is preferably a compound containing a plurality of active hydrogens, which does not volatilize or sublime at the fixing temperature of the resin. Specifically, polyamines: ethylenediamine, tetramethylenediamine ,
Pentamethylenediamine, hexamethylenediamine, p
-Phenylenediamine, m-phenylenediamine, 2-
Hydroxytrimethylenediamine, diethylenetriamine, triethylenetetraamine, diethylaminopropylamine, tetraethylenepentamine, amine adducts of epoxy compounds and the like, piperazine: piperazine, 2-
Polyols and polythiols such as ethylpiperazine and 2,5-dimethylpiperazine: ethylene glycol, diethylene glycol, polyethylene glycol,
Propylene glycol, glycerin, pentaerythritol, trimethylolpropane, 1,4-butanediol, catechol, resorcinol, hydroquinone,
1,2-dihydroxy-4-methylbenzene, 1,3-dihydroxy-5-methylbenzene, 3,4-dihydroxy-1-methylbenzene, 2,4-dihydroxy-1-
Ethylbenzene, 1,3-naphthalenediol, 1,5-
Naphthalenediol, 2,3-naphthalenediol, 2,
7-naphthalenediol and polythiol.

In the toner of the present invention, the polyvalent isocyanate derivative having an isocyanate group protected by a blocking agent is 0.2 to 5 parts by weight, preferably 0.5 to 1.0 part by weight, per 100 parts by weight of the binder resin. Contains parts by weight. The content of the polyvalent isocyanate derivative which is a curable compound is 0.2
If the amount is less than 5 parts by weight, the effect of the present invention cannot be obtained, and if the content of the polyvalent isocyanate derivative is more than 5 parts by weight, the fixing property is undesirably deteriorated.

The active hydrogen donor as a curing agent is contained in an amount of 1 to 1.1 times the equivalent of the polyvalent isocyanate derivative. If the amount of the active hydrogen donor is less than the equivalent of the polyvalent isocyanate derivative, the polyvalent isocyanate does not completely react and the fixability deteriorates, and if the amount is more than 1.1 times the equivalent, the environment resistance of the fixed toner image deteriorates. Not preferred. In the toner of the invention, the blocking agent comes off from the isocyanate at the same time as the resin melts at around 150 ° C., and undergoes a polymerization reaction with the active hydrogen donor. For this reason, a relatively low molecular weight resin, which could not be used conventionally because of the occurrence of offset or the collapse of the image due to excessive melting of the toner, can also be used as a binder resin to obtain a finer image. Can be.

As the resin contained in the toner of the present invention, those having a softening point of about 70 to 150 ° C. and a glass transition point of about 55 to 100 ° C. are preferably those commonly used as binder resins in ordinary toners. Used for For example, styrene resin, (meth) acrylic resin, olefin resin, polyester resin, amide resin, carbonate resin, polyether, thermoplastic resin such as polysulfone,
Alternatively, oligomers or prepolymers of thermosetting resins such as epoxy resins, urea resins, urethane resins, and the like, and copolymers and polymer blends thereof may be used. For example, not only those in a complete polymer state as in a thermoplastic resin, but also those in an oligomer or prepolymer state as in a thermosetting resin, and further include a partial prepolymer and a crosslinking agent in the polymer Etc. are also included. Particularly preferred resins are styrene resins, (meth) acrylic resins,
It is a polyester resin.

The molecular weight of the binder resin is a number average molecular weight.
(Mn), weight average molecular weight (Mw), and Z average molecular weight (Mz)
And 1000 ≦ Mn ≦ 1500, 40 ≦ Mw /
Mn ≦ 70, 200 ≦ Mz / Mn ≦ 500, and as a number average molecular weight (Mn), 2000 ≦ Mn ≦ 7
It is desirable to use what is 000.

The toner of the present invention can be used as an oilless fixing toner. In this case, it is desirable to use a resin having a glass transition point of 55 to 80 ° C., a softening point of 80 to 150 ° C., and further containing 5 to 20% by weight of a gel component as the binder resin. .

In one embodiment of the toner of the present invention, when the binder resin is a resin having active hydrogen, the multivalent resin which is not protected by heating during fixing can be used without adding an active hydrogen donor. The resin itself melted by the isocyanate is cross-linked, and a polymer is formed so as to envelop the paper fibers, so that the effects of the present invention can be obtained. At this time, a half block in which one isocyanate group of the polyvalent isocyanate is reacted with active hydrogen of the resin and the remaining isocyanate group is protected by a blocking agent may be used.

The colorant contained in the toner of the present invention is not particularly limited, and various known organic and inorganic pigments and dyes of various colors can be used. Usually, it is desirable to use 1 to 20 parts by weight, more preferably 2 to 10 parts by weight, based on 100 parts by weight of the binder resin. That is, if the amount is more than 20 parts by weight, the fixability of the toner is reduced, while if the amount is less than 1 part by weight, a desired image density may not be obtained.

In the toner of the present invention, particles comprising the above polyvalent isocyanate derivative, active hydrogen donor, binder resin, colorant and other additives are granulated in a wet system. In the pulverization method in which a binder resin, a colorant, and other additives are melt-kneaded, and the kneaded material is pulverized and classified, a blocking agent is separated from an isocyanate group due to a high production process, and free isocyanate is converted into active hydrogen. Since it reacts with the donor, it is unsuitable for the toner production method of the present invention.

As a method for granulating the toner particles in the wet method, any known wet granulation method can be used as long as the temperature range is such that the blocking agent is not released from the isocyanate group. The method may include a polymerization process such as a suspension polymerization method or an emulsion polymerization method, or may be a granulation method by melt dispersion such as a suspension method.

In the case of the suspension polymerization method, a polymerizable monomer which can form a resin component as a binder, a polymerization initiator, a polymerization composition containing a colorant and other additives, a polyvalent isocyanate derivative and Granulation is performed by suspending the active hydrogen donor in a non-solvent medium and polymerizing it.

In the case of the emulsion polymerization method, the particle size distribution is good but only very fine particles can be obtained by general emulsion polymerization. Therefore, it is preferable to use a method known as a seed polymerization method. That is, a part of the polymerizable monomer and the polymerization initiator are added to an aqueous medium or an aqueous medium obtained by adding an emulsifier, and the mixture is stirred and emulsified. Thereafter, the remaining polymerizable monomer is gradually dropped to obtain fine particles. Using the particles as seeds, the polyvalent isocyanate derivative of the present invention,
The polymerization is carried out in polymerizable monomer droplets containing an active hydrogen donor, a colorant and other additives.

In addition, as a wet granulation method including a polymerization process, a soap-free emulsion polymerization method, a microcapsule method (interfacial polymerization method, in-situ polymerization method, etc.), a non-aqueous dispersion polymerization method, and the like are known. .

In the case of the suspension method, a coloring agent, a polyvalent isocyanate derivative, an active hydrogen donor and other additives are blended with a resin component as a binder and melted. Suspended in the granulation.

The average particle diameter of the toner particles thus granulated in a wet process is desirably 1 to 15 μm, and particularly preferably 2 to 10 μm. After granulating (hereinafter referred to as “toner base material”), it is preferable to add organic or inorganic fine particles to the obtained toner particles.

As the organic or inorganic fine particles in this case, for example, those which function alone or in combination as a charge controlling agent, a fluidizing agent, magnetic particles, an anti-offset agent, a cleaning aid, and the like may be used. However, when these additives are provided in the toner particles, it is not always necessary to make all kinds of additives adhere and exist as fine particles on the surface of the toner particles, and some of them are blended together with the binder resin and the colorant. It is also possible to incorporate the same type of additive in the toner particles, and it is also possible to adopt a mode in which the same type of additive is incorporated in the toner particles and adheres to the surface of the toner particles as fine particles.

The magnetic substance added when preparing the magnetic toner includes magnetite, γ-hematite,
Alternatively, there are various ferrites.

Specific examples of the anti-offset agent used for improving the fixing property of the toner include various waxes, especially low molecular weight polypropylene, polyethylene, or
Oxidized polyolefin waxes such as polypropylene and polyethylene, and natural waxes such as carnauba wax are preferably used.

As the fluidizing agent, various metal oxides such as silica, aluminum oxide, titanium oxide and magnesium fluoride are used alone or in combination.

As cleaning aids, the above-mentioned inorganic fine particles as fluidizing agents, metal soaps such as stearates,
Fluorine, silicon, styrene- (meth) acrylic,
Various synthetic resin fine particles such as benzoguanamine, melamine, and epoxy are used.

The charge control agent is not particularly limited as long as it can give a positive or negative charge by triboelectric charging, and various organic or inorganic charge control agents can be used.

The fixing temperature of the toner of the present invention varies depending on the type of the resin or the blocking agent used. If the temperature is too low, the isocyanate group is not released at the time of fixing. Cause. If the temperature is too high, it causes high temperature offset. Therefore, it is preferable to carry out the reaction in a range from about the softening point of the resin to about 20 ° C. higher than the temperature at which the blocking agent is released and the isocyanate groups are regenerated. The pressure at which the toner is fixed is not particularly limited, but may be 0.5 to 5.0 kg / cm ² which is in a range used in a normal copying machine.

Hereinafter, the present invention will be described with reference to examples. Production of Toner Resin Solution I Component・ Low molecular weight polyester resin 20 g (Mw = 15,000, Mn = 6,000) ・ Methylene chloride 80 g ・ Carbon black (Mogal L, manufactured by Cabot Corporation) 2 g ・ Bontron E-84 0.8 g (manufactured by Orient Chemical Industries)

After the low molecular weight polyester resin is completely dissolved in methylene chloride, carbon black is used as a coloring agent using a wet bead mill (Eiger Motor Mill: manufactured by Eiger Japan), and Bontron E- is used as a charge control agent.
84 was dispersed to obtain a resin solution I.

[0038]Polyvalent isocyanate derivative curable compound
(Compound A) 4,4'-diphenylmethane in 300 ml of carbon tetrachloride
Dissolve 10 g (0.04 mol) of isocyanate,
Furthermore, 9 g (0.08 mol) of ε-caprolactam was dissolved.
Let it go. While stirring this solution, gradually raise the temperature from room temperature.
And reacted at 85 ° C. for 2 hours. The reaction formula is shown below.
You:

[0039]

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After the completion of the reaction, the solvent was evaporated to obtain crystals of a crude reaction product. The recrystallization purification was performed twice to obtain the compound (A)
15 g was obtained (79% yield).

Example 1 0.2 g of a polyvalent isocyanate derivative (Compound A) and 0.05 g of hexamethylenediamine as an active hydrogen donor (curing agent) were added to 100 g of the resin solution I, and dispersed in a bead mill. Solution II was obtained. 100 g of resin solution II
Was added to an aqueous dispersion obtained by dissolving 2 g of Metroose 65SH-50 (manufactured by Shin-Etsu Chemical Co., Ltd.) and 2 g of sodium lauryl sulfate in 200 ml of water using a homomixer (manufactured by Tokushu Kika Kogyo Co., Ltd.) at room temperature for 10 minutes at 3,800 per minute. The emulsion was emulsified and dispersed by rotation to obtain an o / w emulsion. The homomixer was replaced with a stirring blade having four blades, and methylene chloride was distilled off while stirring at 600 rpm for 3 hours at 40 to 45 ° C. to obtain an aqueous suspension of toner particles.

The aqueous suspension from which methylene chloride had been completely removed was allowed to stand for 24 hours, and the supernatant was removed by decantation. 200 ml of the above aqueous dispersion was added thereto,
After stirring, decantation was further repeated twice to wash and separate fine particles having a size of 2 to 3 μm or less. The obtained solid content was washed twice with a washing solution of methanol / water (5/5) and filtered twice, and then dispersed again in a methanol / water (5/5) solution.
To obtain a toner by performing spray dried 0m ³ / min). The obtained toner had an average particle size of 6.0 μm.

[0043] Except for changing only the addition amount and the addition amount of hexamethylenediamine is a curing agent of Example 2-4 Compound A (polyisocyanate derivative) in the same manner as described above, preparing the toners of Examples 2-4 did.

Comparative Example 1 Resin solution I without adding compound A and active hydrogen donor
Was prepared in the same manner as in Example 1 except that the toner was emulsified and dispersed as it was.

Comparative Example 2 A toner was prepared in the same manner as in Example 1 except that 0.1 g of 4,4'-diphenylmethane isocyanate (a polyvalent isocyanate not blocked with a blocking agent) was added instead of Compound A. . In this comparative example, a polymerization reaction occurred in the emulsifying and dispersing step, so that dispersion was not possible, and toner particles could not be produced.

To each of the toners of Examples 1 to 4 and Comparative Example 1, 0.2% by weight of hydrophobic silica R-974 (manufactured by Nippon Aerosil Co., Ltd., volume average particle size: 16 μm) was added, and a Henschel mixer (Mitsui Miike Kako) was added. (Manufactured by Kiki Co., Ltd.) at 3000 rpm for 1 minute.

Carrier preparation component parts by weight polyester resin 100 (softening point 123 ° C., glass transition temperature 65 ° C.
HV40) ・ Fe—Zn ferrite fine particles 500 (manufactured by TDK, MFP-2) ・ Carbon black 2 (manufactured by Mitsubishi Kasei Industries, MA # 8)

The above materials were sufficiently mixed and pulverized by a Henschel mixer, and then extruded and kneaded (PCM-3) set at a cylinder section of 180 ° C. and a cylinder head section of 170 ° C.
0, manufactured by Ikegai Iron and Steel Co., Ltd.). The kneaded product was left to cool, finely pulverized using a feather mill (FP-3A, manufactured by Fuji Sangyo Co., Ltd.), and classified using a classifier to obtain a carrier having an average particle diameter of 60 μm.

The post-treated toner and carrier are
Mixing was performed so that the toner / carrier ratio was 5/95 to obtain a two-component developer. Using this developer, the following tests were conducted to examine the fixability, storage stability, and offset resistance.

Fixing test 1 The center of a 30 mm × 30 mm solid image copied by a copying machine (EP5400, manufactured by Minolta Camera Co., Ltd.) is folded in two, and this is folded between two rollers in contact with a contact width of 4 mm. Caught. The roller was rotated in reverse by applying a load of 6 kg, and image defects were observed. The image densities before and after the fixability test were measured. Table 1 shows the fixing temperatures at which images having an image density of 70% or more of the image density before the test were obtained.

Fixing Test 2 A solidity tester (DAIEI KAGAK)
An image defect was observed by reciprocating 20 times with a load of 1 kg on a NR-100 type Rubbing Tester manufactured by U SEIKI CORPORATION. The image densities before and after the fixability test were measured in the same manner as above, and the fixing temperature at which an image having an image density of 70% or more after the fixability test was obtained is shown in Table 1.

Storage test After standing at 50 ° C. and 50% humidity for 17 hours, the sieve residue after sieving with a 42 μm mesh was measured. In the table, a circle indicates a case where the sieve residue is 5% or less.

Low-temperature offset and high-temperature offset When copying the solid image, the temperature at which toner stains adhered to the fixing roller was measured. The results are shown in Table 1.

[0054]

[Table 1]

[0055]

The toner of the present invention has good fixability and storability. Also, it has excellent resistance to high temperature offset. In addition, a resin having a low molecular weight can be used as a binder resin, and a polymerization reaction of a curable compound and a curing agent occurs simultaneously with the melting of the resin at the time of fixing. Excellent low-temperature fixability can be achieved.

Continued on the front page (72) Inventor Hiroki Nagai Osaka International Building Minolta Camera Co., Ltd. 2-3-13 Azuchicho, Chuo-ku, Osaka-shi, Osaka In-house (72) Inventor Junji Machida 2-chome Azuchicho, Chuo-ku, Osaka-shi, Osaka No. 3-13 Osaka Kokusai Building Minolta Camera Co., Ltd. In-house (56) References JP-A-64-44953 (JP, A) JP-A-64-38757 (JP, A) JP-A-4-212169 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) G03G 9/08

Claims (3)

(57) [Claims] 1. A granulated by wet granulation, resins, colorants, heat and pressure isocyanate groups of the polyvalent isocyanate compound comprising a polyvalent isocyanate derivative and an active hydrogen donor is protected by a blocking agent fixing use <br/> toner. 2. An active hydrogen granulated by a wet granulation method.
, Colorant and polyvalent isocyanate compound having
Isocyanate groups protected by a blocking agent
For heat and pressure fixing containing polyvalent isocyanate derivative
toner. 3. The blocking agent is ε-caprolactam.
3. The toner for heat and pressure fixing according to claim 1 or 2.