JPH0314345B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a toner for developing electrostatic images formed in electrophotography, electrostatic printing, electrostatic recording, and the like. [Prior Art] The process of developing an electrostatic image is a process in which charged fine particles are attracted by electrostatic attraction and adhered to the surface of an electrostatic image support, thereby visualizing the electrostatic image. The image visualized in the developing step may be fixed on the support as it is, but usually it is transferred to another support such as transfer paper and then fixed. It is generally advantageous to use a heat fixing method to fix the toner image formed in the developing process or the image to which this is transferred, and this heat fixing method includes the following steps:
There are non-contact heat fixing methods such as oven fixing and contact heat fixing methods such as heated roller fixing. The contact heat fixing method is superior in that it has high thermal efficiency and has the advantage of requiring less power consumption. However, this method has a serious problem of occurrence of an offset phenomenon. This is a phenomenon in which a portion of the toner constituting the image adheres to the surface of the heat roller during fixing, and this is transferred again to the transfer paper or the like that is fed next, staining the image. Conventional methods for preventing this offset phenomenon include a method of applying release oil such as silicone oil to the surface of a heat roller while fixing the toner, and a known method of providing the toner itself with anti-offset properties. ing. The latter method is superior in that the structure of the fixing device is simple because a silicone oil application mechanism or the like is not required, and maintenance such as replenishment of silicone oil is not required. Therefore, the offset phenomenon occurs when the temperature of the heat roller increases, and therefore, the higher the minimum temperature at which the offset phenomenon occurs (hereinafter referred to as "offset occurrence temperature"), the better the non-offset property is. It can be called toner, but in order for toner to be fixed, it must be heated to a temperature above its softening point. Therefore, in an actual heat roller fixing device, the temperature of the heat roller is lower than that of the toner. The temperature is set at a specific temperature within the fixable temperature range, which is above the softening point and below the offset generation temperature. Therefore, toners with a fixable temperature as low as possible and an offset generation temperature as high as possible, that is, a toner with a wide fixable temperature range, are preferable. In order for the toner to have such preferable characteristics, the binder resin of the toner is required to have both appropriate viscosity and appropriate elasticity when melted.
Conventionally, for such binder resins, the weight average molecular weight (Mw) is compared to the number average molecular weight (Mn).
A vinyl polymer resin having a ratio Mw/Mn of 3.5 or more has been proposed. However, with this method, it is difficult to obtain a toner with a wide fixable temperature range even if the offset generation temperature is high due to the high softening point of the high molecular weight vinyl polymer.
It's not completely satisfying. On the other hand, JP-A-50-44836 proposes a method of using a crosslinked polymer as a binder resin for toner. However, although this method is advantageous in raising the offset generation temperature, it has a limit in lowering the fixing temperature.
It's not completely satisfying. [Object of the Invention] An object of the present invention is to provide a toner for developing electrostatic images that has a low fixable temperature and a high offset generation temperature, and therefore has a wide fixable temperature range. Another object of the present invention is to provide a toner for developing electrostatic images that has good developability and is capable of forming high-density images. Still another object of the present invention is to form a device that is less likely to generate spent toner, less likely to cause carrier contamination, has good non-filming properties on a photoreceptor, and forms stable images over a long period of time in continuous image formation. An object of the present invention is to provide a toner for developing electrostatic images that can be used to develop electrostatic images. [Structure of the Invention] The above object is achieved by an electrostatic image developing toner characterized by containing a polyester containing a diol component of spiroglycol represented by the following general formula []. General formula [] However, in the formula, R ₁ , R ₂ , R ₃ , and R ₄ are each the same or different branched or straight-chain alkyl groups having 1 to 4 carbon atoms, and each of l, m, n, and p is 1 or The integer 2, x and y each represent an integer from 1 to 4. In the present invention, a spiro ring-containing polyester obtained by condensation polymerization of an alcohol consisting of spiroglycol represented by the general formula [] and a carboxylic acid is used as a binder resin, and a colorant and necessary additives are added to the binder resin. to form a toner for developing electrostatic images. Among the various spiroglycols represented by the above general formula [], 3,9-bis(1,1-dimethyl-2-hydroxyethyl)-2,4,8,10- is particularly represented by the following structural formula. Tetraoxa[5.5]undecane is preferred. Structural formula As the alcohol for obtaining the polyester used as the binder resin of the toner in the present invention, only one or two or more of the spiroglycols represented by the above-mentioned spiroglycols may be used. Glycols and other alcohols can also be used in combination. Examples of other alcohols include ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,3
- Diols such as propylene glycol, 1,4-butanediol, neopentyl glycol, 1,4-butenediol, 1,4-bis(hydroxymethyl)cyclohexane, and bisphenol A, hydrogenated bisphenol A, polyoxy Examples include etherified bisphenols such as ethyleneated bisphenol A and polyoxypropylenated bisphenol A, and other dihydric alcohol monomers. Examples of carboxylic acids include maleic acid, fumaric acid, mesaconic acid, citraconic acid, itaconic acid, glutaconic acid, phthalic acid, isophthalic acid, terephthalic acid, cyclohexanedicarboxylic acid, succinic acid, adipic acid, sebacic acid, malonic acid, Examples include anhydrides of these acids, dimers of lower alkyl esters and linoleic acid, and other divalent organic acid monomers. The polyester used in the present invention includes:
In addition to the above-mentioned polymer made only of difunctional monomers, trifunctional or higher polyfunctional monomers may be mixed and used, if necessary. Examples of the trivalent or higher polyhydric alcohols which are such polyfunctional monomers include sorbitol, 1,2,3,6-hexanetetrol, 1,4-sorbitan, pentaerythritol, dipentaerythritol, and tripentaerythritol. Erythritol, sucrose, 1,2,4-butanetriol, 1,2,5-pentanetriol, glycerol, 2-methylpropanetriol, 2-methyl-1,2,4-butanetriol, trimethylolethane, trimethylolpropane ,1,3,
5-trihydroxymethylbenzene and others can be mentioned. Examples of trivalent or higher polycarboxylic acids include 1,2,4-benzenetricarboxylic acid, 1,2,
5-benzenetricarboxylic acid, 1,2,4-cyclohexanetricarboxylic acid, 2,5,7-naphthalenetricarboxylic acid, 1,2,4 naphthalenetricarboxylic acid, 1,2,4-butanetricarboxylic acid, 1,2,5 -hexanetricarboxylic acid, 1,
Examples include 3-dicarboxyl-2-methyl-2-methylenecarboxylpropane, tetra(methylenecarboxyl)methane, 1,2,7,8-octanetetracarboxylic acid, and acid anhydrides thereof. The toner particles of the toner of the present invention usually contain a colorant and, if necessary, additives, and in the case of a magnetic toner, a magnetic substance is contained together with the colorant or in place of the colorant. Coloring agents include carbon black, nigrosine dye (CI No. 50415B), and aniline blue (CI No.
50405), Calco Oil Blue (CINo.azoec
Blue3), Chrome Yellow (CINo.14090), Ultramarine Blue (CINo.77103), DuPont Oil Red (CINo.26105), Quinoline Yellow (CI
No.47005), methylene blue chloride (CINo.
52015), Phthalocyanine Blue (CINo.74160),
Malachite Green Oxalate (CINo.
42000), lampblack (CI No. 77266), rose bengal (CI No. 45435), mixtures thereof, and others. These colorants need to be contained in a sufficient proportion to form a visible image of sufficient density, and are usually contained in a proportion of about 1 to 20 parts by weight per 100 parts by weight of the binder. The magnetic material may be a ferromagnetic metal or alloy such as iron, cobalt, or nickel, including ferrite and magnetite, or a compound containing these elements, or a material that does not contain a ferromagnetic element but is subjected to appropriate heat treatment. Alloys that become ferromagnetic, such as manganese-copper-aluminum,
Mention may be made of a type of alloy called Heusler alloy containing manganese and copper, such as manganese-copper-tin, or chromium dioxide, among others. These magnetic substances are uniformly dispersed in the binder in the form of fine powder with an average particle size of 0.1 to 1 micron. The content is 20 to 70 parts by weight per 100 parts by weight of toner.
Preferably it is 40 to 70 parts by weight. In the toner of the present invention, an anti-offset agent can be contained in the toner particles, and examples of the anti-offset agent include polyolefins, fatty acid metal salts, fatty acid esters, partially saponified fatty acid esters, higher fatty acids, higher alcohols,
Examples include liquid or solid paraffin wax, amide wax, polyhydric alcohol ester, silicone varnish, and aliphatic fluorocarbon. Such offset inhibitors may be used alone or in combination of two or more. The polyolefin is, for example, a resin such as polypropylene, polyethylene, or polybutene, and has a softening point of 80 to 180°C, preferably 100°C when measured by the ring and ball method specified in JIS K 2531-1960.
~160℃. Examples of the fatty acid metal salts include metal salts of maleic acid and zinc, magnesium, calcium, etc.; metal salts of stearic acid and zinc, cadmium, barium, lead, iron, nickel, cobalt, copper, aluminum, magnesium, etc.; Dibasic lead stearate; metal salts of oleic acid with zinc, magnesium, iron, cobalt, copper, lead, calcium, etc.; metal salts of palmitic acid with aluminum, calcium, etc.; lead caprylate; lead caproate; linole Examples include metal salts of acid with zinc, cobalt, etc.; calcium ricinoleate; metal salts of ricinoleic acid with zinc, cadmium, etc., and mixtures thereof. Examples of the fatty acid ester include ethyl maleate, butyl maleate, methyl stearate, butyl stearate, cetyl palmitate, and ethylene glycol montanate. Examples of the partially saponified fatty acid ester include partially saponified calcium esters of montanic acid. Examples of the higher fatty acids include dodecanoic acid, lauric acid, myristic acid, palmitic acid, stearic acid,
Mention may be made of oleic acid, linoleic acid, ricinoleic acid, arachidic acid, behenic acid, lignoceric acid, ceracoleic acid, and mixtures thereof.
Examples of the higher alcohol include dodecyl alcohol, lauryl alcohol, myristyl alcohol, palmityl alcohol, stearyl alcohol, aracyl alcohol, and behenyl alcohol. Examples of the paraffin wax include natural paraffin, microwax, synthetic paraffin, and chlorinated hydrocarbons. Examples of the amide wax include stearic acid amide, oleic acid amide, palmitic acid amide, lauric acid amide, behenic acid amide, methylene bis stearamide, ethylene bis stearamide, and the like. Examples of the polyhydric alcohol ester include glycerin stearate, glycerin ricinolate, glycerin monobehenate, sorbitan monostearate, propylene glycol monostearate, and sorbitan triolate. Examples of the silicone varnish include methyl silicone varnish, phenyl silicone varnish, and the like. Examples of the aliphatic fluorocarbons include low polymer compounds of tetrafluoroethylene and hexafluoropropylene, and fluorine-containing surfactants described in JP-A-53-124428. The proportion of these anti-offset agents to the binder is usually 0.5 to 20% by weight, preferably 1 to 10% by weight. Further, an appropriate property improving agent can be added to the toner particles. Here, the characteristic improver improves the toner's fluidity, non-filming property, that is, the property of not causing filming caused by a part of the toner adhering to the surface of the carrier or electrostatic image, pulverizability, charging property, etc. This includes resins. Preferably used resins are:
For example, styrenes such as styrene and parachlorostyrene, vinylnaphthalene, such as vinyl chloride,
Vinyl esters such as vinyl bromide, vinyl fluoride, vinyl acetate, vinyl propionate, vinyl benzoate, vinyl butyrate, such as methyl acrylate, ethyl acrylate, n-butyl acrylate,
Methylene aliphatic carboxylic acid esters such as isobutyl acrylate, dodecyl acrylate, n-octyl acrylate, 2-chloroethyl acrylate, phenyl acrylate, methyl α-chloroacrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate acrylonitrile, methacrylonitrile, acrylamide, vinyl ethers such as vinyl methyl ether, vinyl isobutyl ether, vinyl ethyl ether, vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone, etc., such as N-vinylpyrrole, N-vinylcarbazole , N-vinyl compounds such as N-vinylindole and N-vinylpyrrolidone, and homopolymers obtained by polymerizing other monomers, or by copolymerizing a combination of two or more of these monomers. Copolymers or mixtures thereof, or non-vinyl resins such as non-vinyl thermoplastic resins such as rosin-modified phenol-formalin resins, oil-modified epoxy resins, polyurethane resins, cellulose resins, polyether resins, or the above-mentioned vinyl-based resins. Mention may be made of mixtures with resins. These resins can be contained in a content ratio of 70% by weight or less of the binder, as long as the effects of the present invention are not impaired. In the toner of the present invention, fine powder of hydrophobic silica can be mixed as a fluidity improver. Preferred examples include "Aerosil R972" and "Silica D-17" manufactured by Nippon Aerosil Co., Ltd. Also, fatty acid metal salts can be added,
As the offset preventive agent, the same fatty acid metal salts as already mentioned can be used. The mixing ratio of each of these is 0.01 to 10% by weight based on the toner particles. [Effects of the Invention] Since the toner of the present invention is as described above, the polyester constituting the binder resin contains a spiro ring derived from an alcohol, and due to the presence of this spiro ring which provides rigid physical properties, The polyester exhibits a high modulus of elasticity and a low viscosity when melted, without particularly increasing the crosslink density, so that the toner according to the invention has a low softening point and excellent non-offset properties. . That is, the toner has a low fixable temperature and a high offset generation temperature, and therefore has a wide fixable temperature range, ensuring good fixing and alleviating severe constraints on fixing. Examples of the present invention will be described below, but the present invention is not limited thereto. Synthesis example 1 166g of terephthalic acid and structural formula Polyester A was obtained by reacting 243 g of spiroglycol shown by 12.4 g of ethylene glycol at 200°C while monitoring the reaction at the softening point.
was manufactured. The ring and ball softening point (according to the method of JISK 2531-1960; the same applies hereinafter) of this polyester A was 130°C. Synthesis Example 2 166g of isophthalic acid, 213g of spiroglycol and 23g of propylene glycol used in Synthesis Example 1
Polyester B having a ring and ball softening point of 127°C was produced by reacting at 200°C in the same manner as in Synthesis Example 1. Synthesis Example 3 166g of terephthalic acid, 213g of spiroglycol used in Synthesis Example 1, and 12.4g of ethylene glycol
Polyester C having a ring and ball softening point of 132° C. was produced by reacting in the same manner as in Synthesis Example 1 using 7 g of pentaerythritol and 7 g of pentaerythritol. Example 1 100 parts by weight of polyester A, 7 parts by weight of carbon black, and 3 parts of polypropylene "Viscol 660p" (manufactured by Sanyo Chemical Co., Ltd.) as an offset prevention agent.
A toner of the present invention having an average particle size of 10.5 microns was produced by a conventional method including mixing parts by weight, grinding, grinding, and classification steps. This will be referred to as "Sample 1". Example 2 A toner of the present invention was produced in the same manner as in Example 1 except that polyester B was used instead of polyester A. This will be referred to as "Sample 2." Example 3 A toner of the present invention was produced in the same manner as in Example 1 except that polyester C was used instead of polyester A. This will be referred to as "Sample 3." Experimental Example 1 A developer was prepared by mixing 95 parts by weight of an iron powder carrier with 5 parts by weight of each of Samples 1 to 3 produced in Examples 1 to 3. Then, a heated roller whose surface layer is made of Teflon (polytetrafluoroethylene manufactured by Dupont) and a silicone rubber “KE-” surface layer are used.
Each of the above-mentioned developers was applied to an electrophotographic copying machine "U-BixV" (manufactured by Konishiroku Photo Industry Co., Ltd.) equipped with a fixing device consisting of a pressure roller formed with "1300RTV" (manufactured by Shin-Etsu Chemical Co., Ltd.), A toner image formed by ordinary electrophotography is transferred onto plain paper, and the fixing is performed while varying the set temperature of the heat roller of the fixing device to determine the fixable temperature and offset generation temperature. Ta. The results are shown in Table 1.

[Table] Experimental Example 2 In addition, when we conducted a long-run copying test of 100,000 times using each of Samples 1 to 3, we found that there was no stain on the fixing roller, and the image quality was free from background stains and backside stains, and the image quality was high. An image similar to the initial image with excellent gradation was stably obtained until the end.

Claims (1)

[Scope of Claims] 1. A toner for developing an electrostatic image, comprising a polyester containing a diol component of spiroglycol represented by the following general formula []. General formula [] However, in the formula, R ₁ , R ₂ , R ₃ , and R ₄ are each the same or different branched or straight-chain alkyl groups having 1 to 4 carbon atoms, and each of l, m, n, and p is 1 or an integer of 2,
x and y each represent an integer from 1 to 4. 2. Claim 1, wherein spiroglycol is 3,9-bis(1,1-dimethyl-2-hydroxyethyl)-2,4,8,10-tetraoxa[5.5]undecane represented by the following structural formula: The electrostatic image developing toner described above.