JPH0344293B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a heat-fixing toner used in electrophotography, electrostatic recording, electrostatic printing, etc. Generally, in electrophotography, an electrostatic charge image is formed on a photoconductive material (ZnO photoreceptor, Se photoreceptor, organic photoconductor, etc.), and then the electrostatic charge image is developed using a toner. The statue remains as it is, or
After being transferred onto a transfer sheet such as plain paper, the image is fixed to obtain the final image. As this type of toner, generally used are, for example, resin-based toners that are mixed with magnetic carrier particles and used as a two-component developer, and single-component magnetic toners that are mainly comprised of resin and magnetic powder. . Toner image fixing methods include an oven fixing method in which the toner image is passed through a heated atmosphere using an electric heater;
A heat roll fixing method in which the image is passed between a pair of rolls, at least one of which is a heating roller, and a pressure fixing method in which the image is passed between a pair of rigid rolls at room temperature are known. Among these fixing methods, the heat roll fixing method is
Since the heating roll surface and the toner image holding surface on the fixing substrate come into pressure contact, thermal efficiency is extremely high and fixing can be performed quickly, making it extremely suitable for image forming apparatuses that aim for high-speed copying in particular. It is. However, this hot roll fixing system has the drawback of being susceptible to the so-called offset phenomenon. That is, during fixing, the toner constituting the image comes into pressure contact with the surface of the heating roll in a heated and molten state, so some of the toner is transferred to the surface of the heating roller, and this is transferred again onto the substrate to be fixed, staining the image. It is a phenomenon. As a way to prevent this offset phenomenon,
For example, the surface of the heating roll is made of a material with heat resistance and low surface energy, such as fluororesin or silicone rubber, and then an offset prevention liquid such as silicone oil is supplied to the surface to form a thin film of the liquid. A method of coating the roll surface has been used.
This method requires an extra device for supplying the liquid, and also has drawbacks such as emitting an odor when the silicone oil or the like is heated. Another method for preventing the offset phenomenon is to provide the toner with anti-offset performance to obtain a good fixed image without causing offset, even without supplying an anti-offset liquid such as silicone oil. It is being Several toners have been proposed that are suitable for this type of fixing method. For example, Special Publication No. 52-3304, No. 52-3305,
No. 57-52574, No. 53-155655 and No. 58-12580
Each of these publications describes a toner containing a colorant, a styrene resin, and a specific release agent. Furthermore, Japanese Patent Publication No. 55-6895 describes a toner containing an α,β-unsaturated ethylenic monomer as a constituent unit and a resin having a molecular weight distribution within a predetermined range as a main resin component. ing. Furthermore, JP-A-56-1952, JP-A No. 57-37353, JP-A No. 57-171345
Toners for hot roll fixing containing a polyester resin have also been proposed, as described in the following publications: However, according to the above-mentioned known toner,
Although it is somewhat satisfactory in terms of high offset resistance and low fixing temperature, further improvements have been desired. In addition, as a matter of course, toners are required to have excellent developability, transferability, anti-blocking properties, and cleaning properties in addition to fixing properties, but known toners do not always adequately meet these properties. I couldn't meet it. For example, toners containing polyester resins have a problem in that they tend to cause charged aggregation because this resin is strongly negatively charged. Additionally, toners that easily melt at relatively low temperatures when heated, or toners that contain a relatively large amount of polyolefin with a low secondary transition temperature as a release agent, tend to cause blocking during storage or in copying machines. . SUMMARY OF THE INVENTION An object of the present invention is to provide a toner for heat fixing that eliminates the above-mentioned drawbacks of the prior art, has excellent offset resistance and fixing properties, and provides a high quality fixed image. The toner for heat fixing of the present invention is a toner for heat fixing that is used in a heat roll method and contains at least a resin, a colorant, and a release agent, and the resin includes a diol component and a divalent or trivalent or higher valent polyvalent component. a polyester resin consisting of a carboxylic acid or a derivative thereof, α,
It consists of a styrene-acrylic copolymer containing β-unsaturated ethylene monomer as a constituent unit and a xylene formaldehyde resin, and the polyester resin and the styrene-acrylic copolymer are mixed in a ratio of 50 to 30:50 to The toner is characterized in that the xylene-formaldehyde resin is blended at a weight ratio of 70% (however, a total of 100 parts by weight), and the xylene-formaldehyde resin is contained in an amount of 1 to 10% by weight in the total amount of the toner. The toner for heat fixing according to the present invention has excellent offset resistance and developability because it contains the above-mentioned polyester resin and styrene-acrylic resin. Furthermore, xylene formaldehyde resin has the unique property of having a lower melt viscosity than other thermoplastic resins with similar softening points.
The toner of the present invention has good fixing properties while maintaining excellent offset resistance and blocking resistance.
The above excellent properties cannot be sufficiently exhibited by each material alone, but can be exhibited synergistically by the mixed system of the polyester resin, styrene-acrylic resin, mold release agent, and xylene formaldehyde resin of the present invention. Details of each resin will be described below. In order to prevent offset in the heat fixing method using a hot roll, the molecular weight distribution of the resin, that is, the value of weight average molecular weight (hereinafter referred to as Mw)/number average molecular weight (hereinafter referred to as Mn) (hereinafter referred to as molecular weight distribution)
It is well known that it is necessary to increase the On the other hand, in the case of styrene-acrylic copolymer,
Resins synthesized by ordinary polymerization methods often have a molecular weight distribution of 2.0 or more (as measured by gel permeation chromatography, hereinafter the same), and many have an offset prevention effect. Therefore, in the present invention, a styrene-acrylic copolymer having a molecular weight distribution of 2.0 or more (preferably 4.0 or more) is used as one of the resin components. Examples of the α/β-unsaturated ethylenic monomer for forming the styrene/acrylic copolymer used in the present invention include styrene, 0-methylstyrene, p-methylstyrene, α-methylstyrene, p -ethylstyrene, 2,4-dimethylstyrene, p-n-butylstyrene, p-tert-butylstyrene, p-n-hexylstyrene, p-n
-octylstyrene, p-n-nonylstyrene,
Styrenes such as p-n-decylstyrene, p-n-dodecylstyrene, p-methoxystyrene, p-phenylstyrene, p-chlorostyrene, 3,4-dichlorostyrene, vinylnaphthalenes,
Methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, propyl acrylate, n-octyl acrylate, dodecyl acrylate, lauryl acrylate, acrylic acid 2
-ethylhexyl, stearyl acrylate, 2-chloroethyl acrylate, phenyl acrylate,
Methyl α-chloroacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-octyl methacrylate,
Examples include α-methylene aliphatic monocarboxylic acid esters such as dodecyl methacrylate, stearyl methacrylate, phenyl methacrylate, dimethylaminoethyl methacrylate, and diethylaminoethyl methacrylate. In the present invention, copolymers of the above-mentioned styrenes and α-methylene aliphatic monocarboxylic acid esters can be used;
Number average molecular weight is 10000~50000, molecular weight distribution is 3~
30 is preferred, particularly a weight average molecular weight of 150,000 to 270,000, a number average molecular weight of 25,000 to 35,000, and a number average molecular weight of 4 to 35,000.
Those having a molecular weight distribution of 15 are effective. However, when using a crosslinked resin, it is of course effective even if the resin exceeds this range. Next, in the heat fixing method using a heated roll, a toner is required that has an offset prevention effect and can be fixed at as low a temperature as possible in order to facilitate high-speed fixing. Polyester resin is known as a resin that satisfies these conditions, and is used in the present invention together with the above-mentioned styrene-acrylic copolymer. The polyester resin used in the present invention includes a specific diol component, a divalent carboxylic acid or its lower alkyl ester, and a trivalent or higher polyvalent resin, such as those described in JP-A No. 57-37353. A polyhydric carboxylic acid or its derivative product, which is a mixture with a carboxylic acid or its anhydride, and the content of the trivalent or higher polycarboxylic acid or its acid anhydride is 30 to 80 mol% of the acid component. Condensation-polymerized polyester resins are suitable. In the present invention, among the above polyester resins, the weight average molecular weight is 5000 to 100000 (more preferably
15,000 to 30,000), a number average molecular weight of 5,000 to 20,000, and a molecular weight distribution of 5 to 20 (preferably 6 to 12). However, in the case of crosslinked polyester resins, molecular weights outside the above range are also effective. Note that the polyester resin is effective in preventing toner from adhering to a vinyl chloride sheet (so-called vinyl chloride contamination) when a fixing substrate holding a fixed toner image is placed under the sheet. The blending ratio of the above-mentioned styrene-acrylic copolymer A and polyester resin B is A:B in terms of weight ratio.
=30-85: The range is preferably 70-15, and the more preferred range is 50-70:50-30 (however, the total amount is 100 parts by weight). The toner containing the above-mentioned styrene-acrylic copolymer, polyester resin, and mold release agent has excellent offset resistance, but it is necessary to further improve the fixability at relatively low temperatures. Heat roll fixing automatically adjusts the fixing temperature, but when fixing at high speed on a substrate that contains a relatively high amount of moisture, the temperature of the fixing roll temporarily drops, resulting in poor fixing performance. There was also the problem that cold offsets were likely to occur. Therefore, in the present invention, xylene formaldehyde resin is used as a part of the resin in order to maintain the offset resistance of the toner and improve the fixability at relatively low temperatures. Xylene formaldehyde resin is a resin manufactured using xylene and formalin as main raw materials, and is represented by the following general formulas (a) to (d), for example. That is, it is a resin in which meta-xylene is chemically bonded through methylene bonds, ether bonds, acetal bonds, etc. This 100% xylene resin can also be used as a modified xylene resin reacted with monobasic or polybasic acids, unsaturated fatty acids, phenols, and amines. By containing this xylene resin or modified xylene resin in an amount of 1% to 15% in the total weight of the toner, it is possible to improve the fixing performance without reducing the offset resistance of the toner. Another effect of using xylene resin is that it improves the pulverization properties when producing toner by a melt-kneading-pulverization process. However, if the content of xylene resin exceeds 10%, the softening point of xylene resin will be relatively low (80-90%).
(degrees Celsius), the blocking resistance is lowered and the toner is more likely to be crushed, resulting in an increase in the amount of fine powder, which in turn causes the problem of lowering the toner yield. Therefore, in the present invention, the content of xylene formaldehyde resin in the total amount of toner is set to 1 to 10% by weight. Further, in the present invention, in order to improve the offset resistance of the toner, a release agent is contained in the total amount of the toner in an amount of 1 to 15% by weight. As the mold release agent used in the present invention,
Aliphatic resins, fatty acid metal salts, higher fatty acids,
Although there are known aliphatic compounds such as fatty acid esters or partially saponified products thereof, aliphatic resins with a low molecular weight (weight average molecular weight of 1,000 to 10,000) are particularly effective. Specifically, one or a combination of two or more of low molecular weight polypropylene, low molecular weight polyethylene, paraffin wax, and low molecular weight olefin polymers consisting of olefin units having 4 or more carbon atoms are suitable. Any suitable pigment and/or dye may be used as a colorant in the toner according to the present invention. For example, carbon black, aniline blue, calco oil blue, chrome yellow, ultramarine blue, Dupont oil red, quinoline yellow, methylene blue chloride, phthalocyanine blue, methylene, malachite green oxalate, lamp black, rose bengal and other known ones. can be mentioned. In place of some or all of the above dyes in the toner of the present invention, known magnetic material powders such as iron oxides such as magnetite, hematite, and ferrite, magnetic metals such as cobalt, nickel, and manganese, and their alloys are used. However, the toner may be made magnetic. When using as a one-component magnetic toner,
It is appropriate that the magnetic powder be contained in an amount of 20 to 80% by weight based on the total amount of the toner. The toner of the present invention is
Of course, it can also be used as a two-component developer (however, magnetic powder may be included in the toner) by mixing it with a known carrier such as iron powder, ferrite powder, or glass beads. Furthermore, the toner image formed on the fixing sheet using the toner of the present invention does not require the use of a hot roll with an anti-offset liquid applied to the surface of the toner image.
Good hot roll fusing is possible without offset, but the hot roll for fixing is, for example, a metal roll whose surface is coated with a fluororesin such as tetrafluoroethylene resin, or a hard silicone rubber. You can use the ones that have been formed. Example 1 Styrene-n-butyl methacrylate (Mw=
220000, Mn=20000, Tg=60℃), polyester resin (resin described in Synthesis Example 1 of JP-A No. 57-37353), rosin-modified xylene aldehyde resin (Liganite Lignol R-70), polypropylene (Sanyo Eight types of toners shown in Table 1 were created according to the following process using the following raw materials: Viscol 550P (manufactured by Kasei), charge control agent (Bontron E81, manufactured by Orient Chemical), and carbon black (#44, manufactured by Mitsubishi Kasei). . First, the raw materials were sufficiently kneaded at a temperature of 140℃ using a pressure kneader, cooled and solidified, and then ground using a jet mill to obtain an average particle size of 12 μm.
The toner was obtained. In addition, the amount of triboelectric charge of these toners was measured using an iron powder carrier (manufactured by Nippon Steel Powder) using a Toshiba Chemical TB-200 measuring machine.
Measurement of the amount of charge against EFV200/300) is also the first
Shown in the table. Eight types of developers were prepared by mixing 5 parts by weight of each of the above toners with 95 parts by weight of iron powder carrier (EFV200/300 manufactured by Nippon Steel Powder), and these developers were used in commercially available electrophotographic copying machines. When the images were evaluated, the results shown in Table 2 were obtained.

【table】

【table】

[Table] (Note) ○: Good, △: Slightly poor, ×: Poor As is clear from Table 2, all toners have good offset resistance, but No. 7 toner, which does not contain xylene resin, has poor fixation. I wasn't sexual enough.
Also, vinyl chloride (Maponyl manufactured by Okamoto Riken Rubber)
Adhesion to low polyester content
Toners No. 5 and 6 were inferior, but other toners were good. Example 2 Styrene-acrylate copolymer (Mw=
150000, Mn=31000, Tg=62℃), polyester resin (resin described in Synthesis Example 2 of JP-A No. 57-37353), polypropylene (Viscol 550P manufactured by Sanyo Kasei), xylene formaldehyde resin (manufactured by Lignite, Lignol) Eight types of toners shown in Table 3 were prepared using the following raw materials: R-70) and magnetic powder (EPT500 manufactured by Toda Kogyo) according to the following process. First, the raw materials were thoroughly kneaded at a temperature of 140°C using a pressure kneader, solidified by cooling, and then finely ground using a jet mill. Next, 0.6 parts by weight of finely powdered silica (Aerosil R972, manufactured by Nippon Aerosil Co., Ltd.) was added to the finely pulverized powder, and the mixture was dry mixed at room temperature, and then passed through a hot air stream at 150° C. in the form of a spray for heat treatment. Next, 0.5 parts by weight of finely powdered silica was added and mixed, followed by classification to obtain a magnetic toner having a particle size of 5 to 20 μm. Using these magnetic toners, image evaluation was performed using an experimental copying machine using a selenium photoreceptor with an outer diameter of 120 mm, and the results shown in Table 4 were obtained. The development is
A magnet roll with symmetrical 12-pole magnetization and a magnetic force of 600G on a stainless steel sleeve with an outer diameter of 31.4mmφ and the sleeve were placed in the same direction as the photoreceptor (however, in the developing gap) at 1200r, p, and m, respectively.
and 100 rpm, and the developer gap and doctor gap are 0.45 mm and 0.45 mm, respectively.
I set it to 0.35mm. For fixing, use a fixing machine equipped with a heated roll whose surface is coated with Teflon (product name), and heat the roll surface to 170°C.
The fixing speed was mm/sec.

【table】

【table】

[Table] (Note) ○: Good, △: Slightly poor, ×: Poor As is clear from Table 4, the image density of all toners except No. 9 is acceptable for practical use, but they do not contain xylene resin. Toner No. 15 still had insufficient fixing properties. Further, toner No. 14 with a low polyester content had poor vinyl chloride stain resistance. Reference Example In No. 3 toner of Example 1, four types (No. 17 to 20) toner was created. The content of xylene formaldehyde resin in these toners is 10 parts by weight (No. 17), 12 parts by weight (No. 18), 15 parts by weight (No. 19), and 18 parts by weight (No. 20).
It was hot. Image evaluation was performed using the above toner under the same conditions as in Example 1. The results are shown in Table 5.

[Table] As is clear from Table 5, toners with high xylene formaldehyde resin content (No. 18 to 20)
In this case, blocking resistance and yield decrease. As described above, the toner for heat fixing according to the present invention has good offset resistance, fixing property, and vinyl chloride stain resistance, and can provide high-quality images.

Claims (1)

[Claims] 1. In a heat fixing toner containing at least a resin, a colorant, and a release agent and used in a hot roll method, the resin is a polyester comprising a diol component and a divalent or trivalent or higher polyvalent carboxylic acid or a derivative thereof. It consists of a resin, a styrene-acrylic copolymer containing an α,β-unsaturated ethylenic monomer as a constituent unit, and a xylene formaldehyde resin, and the polyester resin and the styrene-acrylic copolymer are Blended at a weight ratio of 30:50 to 70 (however, the total is 100 parts by weight),
A toner for heat fixing, characterized in that the xylene formaldehyde resin is contained in an amount of 1 to 10% by weight based on the total amount of the toner.