JPH0862894A - Toner for developing electrostatic image and method for fixing toner image using the same - Google Patents

Abstract

PURPOSE: To obtain a toner fixable at a low temp., ensuring a wide fixing region and giving an image which is not made defective even by folding and the sticking and peeling of an adhesive material. CONSTITUTION: This toner contains vinyl resin and a colorant. mol.wt. distribution by the gel permeation chromatography of the THF-soluble component of the vinyl resin has the max. value in each of the mol.wt. ranges of 5,000-50,000 and 200,000-2,000,000 and the min. value in the mol.wt. range of 50,000-200,000, the ratio between the high mol.wt. component whose mol.wt. is above the min. value and the low mol.wt. component whose mol.wt. is below the min. value is 15:85 to 50:50 and the low mol. wt. component contains 5-50wt.% alkyl (meth)acrylate having >=8C alkyl group.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrostatic image developing toner, and more particularly to an electrostatic image developing toner which is excellent in fixability and offset resistance and which can prevent a fixing film from being stained.

[0002]

2. Description of the Related Art As a performance required for an electrostatic image developing toner, not only that relating to image quality such as density and resolution, but also that a wide fixing temperature can be set and good fixing property It is also important that the offset property is excellent and the photoconductor and the image are not contaminated, and that they are fixed to the photoconductor and the fixing film so as not to shorten their lives.

For the purpose of such fixing property, particularly fixing property at low temperature, anti-offset property and anti-filming property, attempts have been made to control the molecular weight distribution of the binder resin in the toner and to adjust the composition. It has been done.

For example, in JP-A-56-16144, the molecular weight distribution of the binder resin of the toner is 1,000-80,000.
And the molecular weights of 100,000 to 2,000,000 have maximum values. Although this is excellent in pulverizability during production, image quality, fixing property, and resistance to filming and fusion resistance to the photoreceptor, since the cohesive force and viscosity of the low molecular weight component in the molten state are low, Offset resistance is inferior, and during long-term image formation, the amount of toner adhering to the heat fixing roller increases, and even if roller cleaning or wave cleaning cannot be sufficiently scraped off, there is a problem that image stains occur. there were. Also, JP 1-17
No. 2844 describes that the molecular weight distribution has maximum values in the molecular weight ranges of 3,000 to 5,000 and 150,000 to 2,000,000, and the peak area on the high molecular weight side is 40 to 60%. This uses a large amount of high molecular weight components, but since the molecular weight on the low molecular weight component side is small, the cohesive force and viscosity in the molten state are small, the offset resistance is insufficient, and the mechanical strength of the toner is low. When used as a weak, especially two-component developer, there is a drawback that toner is excessively pulverized by the stirring in the developing device and adheres to the carrier surface, the charging performance is lowered, and fog occurs.

Further, it is preferable to use a monomer having a crystalline alkyl group having 14 or more carbon atoms as a monomer, and polymerize the monomer so that the side chain has high crystallinity to obtain a binder resin. No. 48-79639. This is effective for filming resistance, but in order to increase the crystallinity of the side chain, a high proportion of the monomer having a crystalline alkyl group must be used, and therefore, the pulverizability during production should be improved. And the productivity is poor, and the fixability at low temperatures is lacking. Further, in JP-A-5-237787, a thermoplastic resin and a wax are used as a binder resin, and the thermoplastic resin has a high molecular weight of styrene- (meth) acrylate having an alkyl (meth) acrylate component having 11 to 20 carbon atoms. Those comprising a copolymer and a styrene component and a low molecular weight copolymer of a (meth) acrylate component are described. According to this, styrene-having an alkyl (meth) acrylate component having 11 to 20 carbon atoms-
Since it contains a high molecular weight copolymer of (meth) acrylate, the dispersibility of wax such as polyolefin is improved,
Filming and toner fusion on the photoconductor are prevented, and a toner having a wide offset width is obtained. However, since the (meth) acrylate component having a long side chain is contained as a high molecular weight component, the hardness of the high molecular weight component is increased, the pulverizability during the production of the toner is reduced, the productivity is poor, and the viscosity of the toner is low. Although the elastic properties are increased, the low temperature fixability is decreased, and the dispersibility in high molecular weight components such as wax is improved, but the dispersibility in low molecular weight components is not improved and the wax dispersion in the toner becomes non-uniform. However, there is a drawback that the toner easily scatters, fogging, and toner spillage occur.

As described above, in reality, no conventional toner can meet all the requirements such as low temperature fixing property, offset resistance and filming resistance in addition to image quality.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and firstly, it is possible to fix the toner at a low temperature and to widen the fixing area so that it can be bent or tacky. An object of the present invention is to provide a toner that does not cause a defect in an image even if the product is peeled off after being attached. Secondly, it is to provide a toner which is less likely to be over-pulverized in the developing device and which does not cause fog or toner scattering. Thirdly, it is to provide a toner which has good offset resistance, does not adhere to the fixing film, and does not shorten the life of the fixing film.

[0008]

Means for Solving the Problems The above object of the present invention is to provide gel permeation chromatography (hereinafter, also referred to as GPC) containing a vinyl resin and a colorant, and a tetrahydrofuran-soluble component of the vinyl resin. .), The molecular weight distribution is in the range of 5,000-50,000 and 200,000-
Each has a maximum in the range of 2,000,000 and a molecular weight of 50,00.
It has a minimum value in the range of 0 to 200,000, and the ratio of a high molecular weight component having a molecular weight larger than the minimum value to a low molecular weight component having a smaller molecular weight than the minimum value is 15/85 to 50/50, and the low molecular weight. The component is an alkyl acrylate or alkyl methacrylate having an alkyl group of 8 or more carbon atoms
A toner for developing an electrostatic image containing 50% by weight, and a heating member fixedly supported, and a pressing member that is pressed against the heating member and is in close contact with the heating member through a film, reveals the toner. And a toner image fixing method of fixing an image on a recording material under pressure and heat.

That is, the inventors of the present invention optimize the molecular weight distribution of the binder resin of the toner, and introduce a long-chain alkyl group into the low molecular weight component to entangle the low molecular weight components with each other to improve the mechanical strength. The present invention has been accomplished in consideration of imparting both low temperature fixability, offset resistance and filming resistance.

Hereinafter, the present invention will be described in detail.

One of the constitutions of the toner of the present invention is that the binder resin has a maximum molecular weight distribution by GPC in a molecular weight range of 5,000 to 50,000 and a molecular weight range of 200,000 to 2,000,000. If it has a value, the viscoelasticity at the time of melting becomes small, and the offset resistance of the toner decreases. In this case, since the mechanical strength is weak, the toner is excessively pulverized by stirring in the developing machine, which causes fog and toner scattering. Particularly when used as a two-component developer, the toner adheres to the surface of the carrier to lower the charging performance and cause fog. In the present invention, since the maximum value is in the molecular weight range of 5,000 to 50,000, the fixability is improved. And this low molecular weight component is 5 to 50% by weight of alkyl acrylate and / or alkyl methacrylate having an alkyl group having 8 or more carbon atoms.
By containing it, the mechanical strength becomes strong, and the toner is not excessively pulverized by stirring in the developing machine. Therefore,
It is possible to achieve both low-temperature fixability, offset resistance, and filming resistance. In addition, the introduction of a long-chain alkyl group also enhances the compatibility with the high molecular weight component, so that a resin component, a colorant, and various additives can be uniformly dispersed in the toner, and excellent charging characteristics and Agglomeration resistance can be obtained.

As the alkyl acrylate and alkyl methacrylate having an alkyl group having 8 or more carbon atoms,
N-octyl acrylate, 2-octyl acrylate, n-nolyl acrylate, decyl acrylate, n-dodecyl acrylate, tetradecyl acrylate, hexadecyl acrylate, stearyl acrylate, n-octyl methacrylate,
N-decyl methacrylate, n-hexadecyl methacrylate,
Stearyl methacrylate and the like can be mentioned. Preferably, by adopting one having an alkyl group having 8 to 20 carbon atoms, it is possible to obtain the effects of over-pulverization prevention property, anti-offset property, and toner fixing property. Less than 5% by weight and /
Alternatively, when the alkyl group has less than 8 carbon atoms, the above effect cannot be obtained because it is estimated that there is no entanglement of low molecular weight components.

Further, by having a maximum value in the molecular weight range of 200,000 to 2,000,000, the offset resistance is improved and the molecular weight of 5
By having a minimum value in the range of 0,000 to 200,000 and the ratio H / L of the high molecular weight component H and the low molecular weight component L having a higher molecular weight than this minimum value being 15/85 to 50/50, low temperature fixing of the toner It is possible to achieve a good balance between the properties, offset resistance and crushability.

The maximum molecular weight, the minimum molecular weight, the ratio of the high molecular weight component and the low molecular weight component according to the molecular weight distribution of the present invention are determined by gel permeation chromatography (GP).
It was measured by C). Specifically, the efflux counts such as the maximum and minimum values shown in the obtained GPC chart are calculated by using a calibration curve (logarithm of molecular weight and efflux counts are linear with several monodisperse polystyrene standard samples. Range) to determine the molecular weight. The ratio H / L of the high molecular weight component H and the low molecular weight component L is the molecular weight of 5 on the GPC chart.
It can be calculated from the ratio of the area on the high molecular weight side to the area on the low molecular weight side of the minimum value in the range of 000 to 200,000. An example of the GPC chart is shown in FIG.

Other vinyl-based monomers constituting the vinyl-based resin of the present invention include styrene-based monomers, acrylic acid ester-based monomers, methacrylic acid ester-based monomers, and vinyl ester-based monomers. It is preferable to use the body or the like.

As the other monomer, a polyfunctional monomer may be used as a crosslinking agent. As a polyfunctional crosslinking agent,
Examples thereof include divinylbenzene, divinylnaphthalene, ethylene glycol dimethacrylate, ethylene glycol diacrylate, triallyl cyanurate and the like. By using a cross-linking agent, a cross-linking structure can be introduced into the molecular structure, the viscoelastic property during melting is improved and the offset resistance is improved. The use of a cross-linking agent is preferably incorporated into the high molecular weight component.
The polyfunctional monomer is preferably used in an amount of 0 to 25% by weight of the monomer. If it exceeds 25% by weight, the crosslinking reaction proceeds too much, the softening temperature of the toner rises, and the fixing property deteriorates.

The vinyl resin of the present invention may be obtained by any production method such as bulk polymerization method, solution polymerization method, suspension polymerization method and emulsion polymerization method as long as it satisfies the requirements of the present invention. Two or more polymerization methods may be combined for synthesis, but the solution polymerization method, suspension polymerization method, and emulsion polymerization method are preferable from the viewpoint of easy control of the molecular weight distribution.

For example, in order to obtain the vinyl resin of the present invention by a solution polymerization method, a polymer of a low molecular weight component having a maximum value in the range of 5,000 to 50,000 and a molecular weight distribution.
Polymers of high molecular weight components having a maximum value in the range of 200,000 to 2,000,000 are separately synthesized and mixed, or the first stage polymerization for producing one of the polymers is carried out, and then the other polymer is mixed. It can be obtained by dissolving in a monomer giving a coalescence and carrying out the second stage polymerization.

The glass transition point of vinyl resin is 50 to 100
C., especially 50 to 85.degree. C. are preferred. The glass transition point is measured by a differential scanning calorimeter. Specifically, the temperature is raised from 0 ° C. to 100 ° C. at a heating rate of 10 ° C./min, left at that temperature for 3 minutes, and then cooled to 0 ° C. at a falling rate of 10 ° C./min. Then, the temperature was raised again to 100 ° C at a heating rate of 10 ° C / min, and the intersection of the extension line of the baseline at that time and the tangent line showing the maximum slope between the rising part of the endothermic peak and the peak was taken as the glass transition point. To do.

The softening point of the vinyl resin is preferably 100 to 150 ° C. The softening point is measured with a high-performance flow tester "CFT-500C" (manufactured by Shimadzu Corporation). Specifically, when the diameter of the die pores is 1 mm, the length of the die is 1 mm, the load is 20 kg / cm ² , and the heating rate is 6 ° C / min, 1 cm ³ of the sample is melted and flowed out. The temperature corresponding to ½ of the outflow end point from the start point is the softening point.

As the colorant used for the toner, carbon black, nigrosine dye, aniline blue, calcoil blue, chrome yellow, ultramarine blue, quinoline yellow, DuPont oil red, methylene blue chloride, phthalocyanine blue, malachite green, lamp black, Examples include rose bengal and magnetite, and a mixture thereof can also be used. The content of these colorants is preferably 0.5 to 20% by weight in the toner.

A release agent may be added to the toner of the present invention, if necessary.
You may contain a magnetic powder, a charge control agent, a fluidizing agent, etc.

As the release agent, any of those conventionally used can be used. Specific examples thereof include low molecular weight polypropylene, low molecular weight polyethylene, olefins such as ethylene-propylene copolymer, microcrystalline wax, carnauba wax, sazol wax, paraffin wax, and the like, and two or more kinds may be used in combination. . The amount of the release agent added is preferably 1 to 10% by weight.

As the magnetic powder, any of those conventionally used can be used. Specifically, it is a ferromagnetic element or an alloy or compound containing them, and examples thereof include compounds such as magnetite and ferrite, metals such as iron, cobalt, nickel and manganese, and alloys thereof. Good. The content of the magnetic powder is usually 20 to 60% by weight in the toner.

Examples of the charge control agent include salicylic acid derivatives and azo metal complexes. The amount added is preferably 0.01 to 10% by weight in the toner.

Examples of the fluidizing agent include fine particles of inorganic oxide such as silica, titania and alumina. Further, these inorganic fine particles are preferably hydrophobized with a silane coupling agent or a titanium coupling agent. The addition amount of these is preferably 0.01 to 10% by weight in the toner.

The toner image fixing method of the present invention uses the above-mentioned toner of the present invention, which comprises a fixedly supported heating element and a pressure member which is in pressure contact with the heating element and is in close contact with the heating element via a film. It is characterized in that the visible image is fixed on the recording material under pressure and heat. The toner of the present invention is excellent in fixability at low temperature, anti-offset property, and anti-filming property. Therefore, when the toner of the present invention is used in this fixing method, it is possible to obtain excellent quality for a long time without shortening the life of the fixing film. You can get an image of.

The heating element has a smaller heat capacity than the conventional heating roller and has a linear heating part, and the maximum temperature of the heating part is 100 to 300.
The one having a temperature of ℃ is preferable because it is a fixing through a film.

The film used preferably has a thickness of 1 to
100 μm heat resistant sheet, such as polyester,
Polyethylene terephthalate, tetrafluoroethylene
-Perfluoroalkyl vinyl ether copolymers, polymer sheets of polytetrafluoroethylene, polyimide, polyamide, etc., metal sheets of aluminum etc., laminate sheets composed of metal sheets and polymer sheets, etc. It is preferable to have a low resistance layer.

As the pressing member, a member such as a pressing roller having an elastic layer having good releasability such as silicon rubber, which is used for ordinary toner image fixing, may be used.

[0031]

The present invention will be described in detail below with reference to examples, but the embodiments of the present invention are not limited thereto.

Example 1 << Synthesis of Resin >> Vinyl resin-1 18 parts by weight of toluene, 12 parts by weight of styrene, 6 parts by weight of butyl acrylate and 0.06 part by weight of benzoyl peroxide were charged into a 5 l separable flask, and toluene was refluxed. Polymerization was carried out at a temperature for 2 hours to carry out a first stage polymerization reaction (synthesis of high molecular weight component). Further, a mixture of 100 parts by weight of toluene, 85 parts by weight of styrene, 10 parts by weight of butyl acrylate, 5 parts by weight of hexadecyl acrylate and 5.0 parts by weight of benzoyl peroxide was charged into this separable flask, and the mixture was similarly refluxed under toluene for 2 hours. Polymerization was carried out to carry out the second stage polymerization (synthesis of low molecular weight component). After that, aging was carried out while maintaining the temperature at the time of synthesis for 0.5 hour, and toluene was distilled off to obtain vinyl resin-1. The resin thus obtained had a softening point of 130 ° C and a glass transition point of 58 ° C.

Vinyl resin-2 In a 5 l separable flask, 65 parts by weight of styrene, 10 parts by weight of methyl methacrylate, 15 parts by weight of butyl acrylate,
Stearyl methacrylate 10 parts by weight, benzoyl peroxide 4.
0 part by weight was charged, and a polymerization reaction (low molecular weight component) was performed for 2 hours under reflux of toluene. Toluene was distilled off to obtain a low molecular weight component.

Further, a reaction vessel equipped with a distillation column, a stirrer and a thermometer was charged with 400 parts by weight of distilled water containing 3 parts by weight of polyvinyl alcohol and 4 parts by weight of sodium sulfate, and the stirring speed was 100 rpm. It was stirred at. Next, 100 parts by weight of the low-molecular weight component obtained above was dissolved in 30 parts by weight of styrene, 2 parts by weight of α-methylstyrene, 6.5 parts by weight of butyl acrylate, and 1.3 parts by weight of divinylbenzene. The rotation speed was 300 rpm, the temperature inside the vessel was raised to 90 ° C., and suspension polymerization was carried out for 3 hours. After that, a Liebig cooling tube was attached, a silicone-based defoaming agent was added, the temperature inside the container was raised to 100 ° C., and residual monomers were removed. The temperature inside the container was cooled to 90 ° C., 8 parts by weight of caustic soda was charged into the container, and the container was kept for about 30 minutes. Further, it was cooled to room temperature, the resin was taken out, and dried at 50 ° C. for 24 hours in a vacuum constant temperature dryer to obtain vinyl resin-2. The softening point of the obtained resin is 145.
The glass transition point was 61 ° C.

[0035] to obtain a vinyl resin -3,5～8 in the same manner as the vinyl resins -1 with a monomer composition shown in the vinyl resin -3,5～8 Table 1.

[0036] to obtain a vinyl resin -4,9 in the same manner as the vinyl resin -2 monomer compositions shown in the vinyl resin -4,9 Table 1.

[0037]

[Table 1]

<< Production of Toner >> 100 parts by weight of vinyl resin,
100 parts by weight of magnetic fine powder, 3 parts by weight of low molecular weight polypropylene and 0.5 part by weight of negatively charged monoazo dye are put in a V-type mixer and mixed for 20 minutes, and a twin-screw extruder PCM-30 (made by Ikegai Steel Works) Was melted and kneaded. After cooling, the product was coarsely pulverized by a Wiley mill to obtain a 2 mm mesh pass product, further finely pulverized by a supersonic jet mill, and fine powder of 5 μm or less was removed by an air classifier to obtain colored fine particles having a volume average particle diameter of 8.5 μm.

To 100 parts by weight of the colored fine particles, 0.9 parts by weight of hydrophobic silica fine particles were added and mixed with a V-type mixer to obtain toners 1 to 4 of the present invention and comparative toners 1 to 5. .

<< Measurement of local maximum molecular weight (LP) of low molecular weight component, local maximum molecular weight (HP) of high molecular weight component and H / L >> Tetrahydrofuran-soluble component of binder resin was extracted from toner, and gel permeation was performed. -Measured by chromatography.

<Evaluation of pulverizability of toner> The feed amount when finely pulverized to 7.5 μm with a supersonic jet mill during toner production was measured, and a feed amount of 20 g / sec or more was ⊚, 10 to 20 g / sec.
Seconds were marked with ◯, and 10 g / s or less were marked with x.

<< Actual Photograph Test >> The fixing device of a commercially available laser beam printer LBP-SX (manufactured by Canon Inc.) was modified into the following configuration.

An electrostatic latent image is formed with a primary charge of -600 V, a developer layer on a developer carrier containing a photosensitive drum and a magnet is set in a non-contact manner with a gap of 300 μm, and an AC bias (frequency) is applied. It was applied to the developing drum as 1800 Hz, maximum peak-to-peak voltage 1200 V) and DC bias (voltage −400 V).

The heating and fixing device was constructed as shown in FIG. 2, and the surface temperature of the temperature detecting element 4 of the heating element 1 was set to 140 ° C. and the rotation speed between the heating element 1 and the pressure roller 8 was set to 24 mm / sec.

As the heat-resistant sheet, a 50 μm-thick polyimide film having a low-resistance release layer in which a conductive substance is dispersed in polytetrafluoroethylene was used on the contact surface with the transfer material.

Under these conditions, a print test for forming a developer image by the reversal development method on a continuous 3000 sheets at a print speed of 4 sheets (A4) / min was carried out at room temperature and normal humidity (20 ° C., 60% RH). The images were evaluated for the following items. or,
At the same time, the appearance of the surface of the fixing film was observed and its durability was evaluated.

(A) Evaluation of printed image-Fixing property The end portion of the obtained fixed toner image is strongly bent with a finger, and the fixed image of this portion is exposed with a rubbing tester to a constant load (50 g / cm) with a cloth. ² ) was applied and rubbed 10 times back and forth, and the rate of decrease (%) in image density before and after rubbing the image at the edge was evaluated with a microdensitometer. A reduction rate of 0-5%
(Excellent), 5-10% is good (good), 10-20% is fair (good), 20
% Or more was defined as x (impossible).

Offset resistance: A sample image with an image area ratio of about 5% is printed out,
The degree of stain on the image after printing 3000 sheets was visually evaluated. The non-occurrence was rated as ⊚, a slight occurrence (practical acceptable) as ◯, and the occurrence (impracticable) as x.

Image Density After printing 3000 sheets on ordinary plain paper for copiers (75 g / m ² ), evaluation was made based on how much image density was maintained. Image density 1.4 or higher is ◎ (excellent), 1.2 to 1.4 is ○
(Good), 1.0 to 1.2 were evaluated as Δ (acceptable), and less than 1.0 was evaluated as x (impossible).

Image quality: Toner scattering, fog, roughness, etc. were visually evaluated.
Very good cases were marked with ⊚, good cases were marked with ◯, practical cases were marked with ∆, and practical cases were marked with x.

(B) Durability / Surface Property of Fixing Film The appearance of scratches and scrapes on the surface of the fixing film after the printout test was visually evaluated. A very good case with no scratches and scrapes was marked with ⊚, a good case with almost no scratches and scrapes was marked with ◯, a case where scratches and scrapings were slightly but practical was marked with Δ, and a case where practical use was not possible was marked with x.

Residual Toner Adhesion Status The toner adhesion status on the surface of the fixing film after the printout test was visually evaluated. Very good case where toner adhesion did not occur was evaluated as ⊚, good case where toner adhesion did not occur was evaluated as ◯, slight toner adhesion was possible but practical use was evaluated as Δ, and practical application was not evaluated as x.

The above results are shown in Table 2.

[0054]

[Table 2]

[0055]

According to the present invention, there is provided a toner excellent in fixing property, anti-offset property and filming resistance and capable of obtaining a high-quality image.

[Brief description of drawings]

FIG. 1 is an example of a gel permeation chromatography chart of tetrahydrofuran-soluble matter.

FIG. 2 shows an example of a heat fixing device according to the method of the present invention.

[Explanation of symbols]

 1 Low heat capacity linear heating element 2 Alumina substrate 3 Resistance material 4 Temperature measuring element 5 Fixing film 6 Driving roller 7 Driven roller 8 Pressure roller 9 Recording material 10 Unfixed toner 11 Inlet side guide H High molecular weight component L Low molecular weight component

Claims (2)

[Claims] 1. A molecular weight distribution by gel permeation chromatography containing a vinyl resin and a colorant, wherein the tetrahydrofuran soluble component of the vinyl resin has a molecular weight range of 5,000 to 50,000 and a molecular weight of 200,000 to 2,000, 00
Each has a maximum value in the range of 0 and a molecular weight of 50,000 to 200,0
The minimum value in the range of 00, the ratio of the high molecular weight component having a molecular weight larger than the minimum value to the low molecular weight component having a smaller molecular weight than the minimum value is 15/85 to 50/50, and the low molecular weight component is 5 to 50 alkyl acrylate and / or alkyl methacrylate having an alkyl group having 8 or more carbon atoms
A toner for developing an electrostatic image, characterized in that the toner is contained in a weight percentage. 2. The toner image according to claim 1 is recorded by a fixedly supported heating element and a pressure member that is pressed against the heating element and is in close contact with the heating element through a film. A method for fixing a toner image, which comprises fixing the material under pressure and heat.