New toner additive and toner composition containing the same

Abstract

The toner additive composition of the present invention contains tin oxide as a core component and can be used as a substitute for conventional titanium dioxide (TiO2), and therefore can comply with future titanium dioxide use and environmental regulations. In addition, the toner additive composition and the toner composition containing the same contain a silane compound and aluminum hydroxide as shell components, thereby reducing the amount of triboelectric charge, improving the ghost phenomenon, and increasing image density to improve print quality. In particular, when the aluminum hydroxide is used within a specific content range, the effect of improving print quality can be further enhanced.

Description

[Technical field]

[0001] The present invention relates to a toner external additive and a toner composition containing the same, and the toner external additive is characterized in that the toner external additive has a core-shell structure in which the core contains tin oxide and the shell simultaneously contains aluminum hydroxide and a silane-based compound. [Background technology]

[0002] Toner, which is a developing material for laser printers, generally includes toner base particles and toner external additives that are coated on all or part of the surface of the toner base particles. The toner external additives are important components that affect print quality by being coated on the toner base particles and controlling triboelectric charge stability, environmental stability, powder flowability, etc.

[0003] Titanium dioxide (TiO2) was used as the main ingredient of conventional toner additives, but in October 2019, the EU amended the Commission Delegated Regulation (EU) 2020 / 217 to include titanium dioxide with a particle size of 10 microns or less, which was previously considered to be a carcinogen. Specifically, the main content of the regulation is that if titanium dioxide is contained in a toner at 1% by weight or more, a warning message about inhalation must be displayed on the surface of the packaging paper. The above amendments are scheduled to be applied to toner compositions containing titanium dioxide and their additives in October 2021, and the need for alternative materials to titanium dioxide has arisen.

[0004] Referring to Figure 1, which is a diagram of discharged charge amount according to the metal ion electronegativity of metal oxides, silica (SiO2), alumina (Al2O3), and iron oxide (Fe3O4) are known as alternative materials to titanium dioxide (TiO2), which is a main component of toner external additives and forms the core. However, tin dioxide (SnO2) can be selected from the viewpoint of exhibiting an electronegativity similar to that of titanium dioxide.

[0005] In relation to a toner composition and additives using tin oxides including tin dioxide, U.S. Patent No. 5,135,832 (registered on August 4, 1992) relates to a colored toner composition, and in detail, it discloses that the toner composition includes a core material encapsulated by a polymer shell containing a metal oxide, a binder resin, a pigment, etc., and that the core material can be surface-treated to be hydrophobic with a silane compound.

[0006] Furthermore, U.S. Patent No. 5,783,345A (registered on July 21, 1998) relates to an image forming method, and in detail discloses that a developing layer formed on a roller rotating body contains a carrier and a toner, and that the toner is composed of conductive inorganic fine particles such as titanium oxide and tin oxide, and can be surface-treated with a silane coupling agent.

[0007] Furthermore, Korean Patent Registration No. 10-0427201 (published on April 17, 2004) relates to a magnetic toner, and in detail, it discloses that the magnetic toner comprises a binder resin, magnetic toner particles including a magnetic powder, and inorganic fine powder, the inorganic fine powder may comprise zinc oxide, tin oxide, etc., and the inorganic fine powder may be subjected to a hydrophobic surface treatment with a silane-based substance.

[0008] However, in the technical field of toner compositions, particularly toner external additives, to which these prior art documents pertain, research and development is being conducted on titanium dioxide alternatives as a core component, and at the same time, research and development is also required on post-treatment techniques that can impart functionality and improve physical properties to the titanium dioxide alternatives, since these techniques affect the printing quality of toner compositions containing the external additives. Summary of the Invention [Problem to be solved by the invention]

[0009] In order to solve such problems, the toner additive composition of the present invention, which is composed of a core and a shell, aims to satisfy environmental regulations by containing tin oxide as a substitute for titanium dioxide (TiO2), which is the core component.

[0010] In addition, the toner external additive composition and the toner composition containing the same maintain excellent durability by containing a silane compound as one component of the shell that covers all or part of the core, and contain aluminum hydroxide as another component to reduce the amount of triboelectric charge, thereby improving the ghost phenomenon (an image defect that occurs when the toner has an excessively high triboelectric charge, which makes it difficult for the toner to move from the developing roller to the OPC, and as a result, the toner cannot move sufficiently to the paper), thereby increasing image density and improving print quality. [Means for solving the problem]

[0011] In order to achieve the above object, the present invention provides a toner external additive, characterized in that it contains particles composed of a core containing tin oxide and a shell in which a silane-based compound and aluminum hydroxide cover all or part of the core.

[0012] In one embodiment of the present invention, the silane-based compound may be an alkoxysilane, specifically an alkyltrialkoxysilane, and more specifically an isobutyltriethoxysilane.

[0013] In another embodiment of the present invention, the toner external additive has a tin oxide content of 40 to 89.95% by weight, a silane compound content of 10 to 50% by weight, and an aluminum hydroxide content of 0.05 to 10% by weight.

[0014] The present invention provides a method for producing a toner external additive composition, comprising the steps of: (A) dropping tin oxide particles into a solution containing a silane-based compound and stirring the solution to obtain tin oxide particles coated with a silane-based compound; and (B) dropping the tin oxide particles coated with the silane-based compound obtained in step (A) into a solution containing aluminum hydroxide and stirring the solution to obtain toner external additive particles.

[0015] In another embodiment of the present invention, there is provided a toner composition comprising 0.1 to 1.5 parts by weight of the toner external additive according to the present invention relative to 100 parts by weight of toner base particles.

[0016] The present invention also provides a method for producing a toner composition, comprising: (a) emulsion-polymerizing a polymer latex using a resin monomer, mixing the polymer latex with a pigment dispersion, a wax dispersion, and an aggregating agent, and then carrying out an aggregation and coalescence process to produce toner base particles; (b) sorting the toner base particles, washing and drying the particles; and (c) adding the toner external additive according to the present invention to the toner base particles. Effect of the Invention

[0017] The toner external additive of the present invention contains tin oxide as a core component and can be used as a substitute for conventional titanium dioxide (TiO2), so that it can comply with future titanium dioxide use and environmental regulations.

[0018] In addition, the toner composition containing the toner external additive of the present invention has excellent durability, improves the ghost phenomenon, and increases image density to improve print quality. [Brief description of the drawings]

[0019] [Figure 1] 1 shows a diagram of the discharged charge amount depending on the electronegativity of the metal ion of a metal oxide. [Diagram 2]FIG. 13 is a diagram showing an image chart printed to check whether or not a ghost phenomenon occurs according to Experimental Example 3. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Generally, the nomenclature used herein is that which is well known and commonly used in the art.

[0021] Furthermore, in describing the present invention, if it is determined that a detailed description of related publicly known technology may unnecessarily obscure the gist of the present invention, the detailed description will be omitted.

[0022] The respective features of the various embodiments of the present invention may be partially or fully combined or combined with each other, and may be technically interlocked and driven in various ways, and each embodiment may be implemented independently of each other or may be implemented together in relation to each other.

[0023] The toner external additive of the present invention will be described in detail below.

[0024] The present invention relates to a toner external additive, characterized in that it contains external additive particles composed of a core containing tin oxide and a shell in which a silane compound and aluminum hydroxide cover all or part of the core. When the toner external additive is contained in a toner composition, the external additive particles are attached to toner base particles, thereby improving print quality.

[0025] The tin oxide is a main component of the core constituting the particles in the toner external additive composition, and is a metal oxide represented by the following chemical formula 1. (chemical formula 1) Sn x O y (However, y / x is in the range of 1 to 2.)

[0026] Referring to FIG. 1, which is a graph showing the amount of discharged charge according to the electronegativity of metal ions of metal oxides, silica (SiO2), alumina (Al2O3), and iron oxide (Fe3)O4 are known as substitutes for titanium dioxide (TiO2), but tin dioxide (SnO2), which has a similar electronegativity to titanium dioxide, is preferably used.

[0027] Meanwhile, the silane-based compound is a component of a shell that covers all or part of the core constituting the particles in the toner external additive composition, and contributes to improving environmental stability including durability.

[0028] The silane-based compound includes alkoxysilane. Examples of the alkoxysilane include ethyltriethoxysilane, ethyltrimethoxysilane, ethyltri-n-propoxysilane, isobutyltriethoxysilane, isobutyltrimethoxysilane, isobutyltriacetoxysilane, n-hexyltrimethoxysilane, vinyltriethoxysilane, phenyltrimethoxysilane, octylmethyldiisopropoxysilane, lauryltrimethoxysilane, 2-ethylhexyltrimethoxysilane, octyltriethoxysilane, dodecyltribromosilane, tetradecyltrimethoxysilane, hexadecyltriethoxysilane, and octadecyltriethoxysilane. Trialkoxysilane is preferred, and isobutyltriethoxysilane is most preferred.

[0029] When an alkoxysilane is used as the silane compound, the degree of hydrophobicity of the external additive is increased, so that the durability and environmental resistance of the toner can be effectively improved.

[0030] The aluminum hydroxide (Al(OH)3), which is a technical feature of the present invention, is another component of the shell that covers all or part of the core constituting the particles in the toner external additive composition together with the silane compound. When the toner external additive particles containing the aluminum hydroxide are attached to the toner mother particles, the amount of triboelectric charge generated between the particles in the toner composition is reduced, improving the ghost phenomenon, and the image density is increased to improve the print quality.

[0031] In the toner external additive according to the present invention, the content of the tin oxide is in the range of 40 to 89.95% by weight, the content of the silane compound is in the range of 10 to 50% by weight, and the content of the aluminum hydroxide is in the range of 0.05 to 10% by weight, and more preferably, the content of the tin oxide is in the range of 53 to 79.9% by weight, the content of the silane compound is in the range of 20 to 40% by weight, and the content of the aluminum hydroxide is in the range of 0.1 to 7% by weight.

[0032] If the content of the silane-based compound is less than 10 wt%, the hydrophobicity of the external additive is reduced, resulting in poor environmental resistance of the toner. If the content of the silane-based compound is more than 50 wt%, the excessive amount of the silane-based compound is added, resulting in poor economic efficiency.

[0033] In addition, if the content of the aluminum hydroxide is less than 0.05% by weight, the toner composition containing the aluminum hydroxide has a problem that the LL environmental charge due to friction is high, causing a ghost phenomenon, reducing image density and deteriorating print quality. If the content of the aluminum hydroxide exceeds 10% by weight, the amount of aluminum hydroxide is excessive relative to the tin oxide core, reducing the coating efficiency and economy of the core, and the amount of frictional charge is excessively reduced, resulting in an excessive increase in image density and an excessive increase in toner consumption.

[0034] From another viewpoint, the present invention provides a method for producing a toner external additive composition. In addition, in the method for producing a toner external additive composition described below, all of the above-mentioned toner external additive compositions can be used, but repeated description will be omitted to avoid losing the essence of the present invention.

[0035] In addition, the present invention may provide a method for producing a toner external additive composition, the method including: (A) introducing tin oxide particles into a solution containing a silane-based compound and stirring the solution to obtain tin oxide particles coated with a silane-based compound; and (B) dropping the tin oxide particles coated with the silane-based compound obtained in (A) into a solution containing aluminum hydroxide and stirring the solution to obtain toner external additive particles.

[0036] After coating the tin oxide particles in step (A) or (B), a washing and drying process may be optionally performed, and the washing and drying process may be performed according to a known washing and drying method after coating of metal oxides.

[0037] The method for producing the toner external additive composition of the present invention is merely described as an embodiment in which the silane compound is coated with aluminum hydroxide in succession, and is not limited to the order of the sequential coating. In another embodiment of the present invention, the order of the sequential coating may be changed to sequentially coat the silane compound with aluminum hydroxide, or a simultaneous coating of a mixed solution of the aluminum hydroxide and the silane compound may be performed.

[0038] The present invention also relates to a toner composition, characterized in that the toner external additive according to the present invention is contained in an amount of 0.1 to 1.5 parts by weight based on 100 parts by weight of the toner base particles.

[0039] In the toner composition, when the toner external additive according to the present invention is contained in an amount of less than 0.1% by weight, there is a problem that the durability maintenance and triboelectric charge reduction effects cannot be exhibited, and when the toner composition is contained in an amount of more than 1.5% by weight, there is a problem that the durability maintenance and triboelectric charge reduction effects relative to the amount added are not further improved, making it uneconomical.

[0040] The toner base particles determine the shape, diameter and particle size of the toner particles, and contain a polymer latex resin, a pigment and a wax as a base material to which the toner external additives are attached. The content of the toner base particles may be 90 to 98% by weight with respect to 100% by weight of the entire toner composition.

[0041] The polymer latex resin is a matrix resin of the toner mother particles, and any known latex resin can be used. Examples of common materials for latex resin include polyester resin, polyester resin mixture, polyester copolymer resin, and styrene-acrylate resin.

[0042] The pigment is a component for coloring the toner composition, and one or more pigments selected from black, cyan, magenta, and yellow can be used.

[0043] The wax is a component that improves the releasability between the photosensitive roller and the toner when the toner is transferred and fixed to an image receptor such as printing paper. The type of wax that can be used includes, but is not limited to, at least one of polyethylene wax, polypropylene wax, silicon wax, paraffin wax, synthetic ester wax, carbauna wax, and metallocene wax.

[0044] In addition, other additives may be included as additional components that impart functionality required to the toner. The types of the other additives may include UV stabilizers, antifungals, bactericides, charge control agents, gloss modifiers, antioxidants, etc. For example, hydrophobic silica, strontium titanate, polymer beads, etc. may be used. The content of the other additives may be in the range of 1 to 9% by weight with respect to 100% by weight of the entire toner composition.

[0045] From another viewpoint, the present invention provides a method for producing a toner composition. Although all of the above-mentioned toner compositions can be used in the method for producing a toner composition described below, repeated description will be omitted in order to avoid losing the essence of the present invention. The present invention provides a method for producing a toner composition, comprising the steps of: (a) emulsion-polymerizing a polymer latex using a resin monomer, mixing the polymer latex with a pigment dispersion, a wax dispersion, and an aggregating agent, and then carrying out an aggregation and coalescence process to produce toner base particles; (b) sorting the toner base particles, washing and drying the particles; and (c) attaching the toner external additive according to the present invention to the toner base particles.

[0046] In the step (a), the toner base particles are prepared by mixing a solvent, a pigment dispersion, a wax dispersion and a flocculant with a polymer latex prepared by an emulsion polymerization process.

[0047] The solvent may be water, an aqueous solution or an organic solvent, preferably water.

[0048] The flocculant may be a metal salt containing Si and Fe, and preferably polysilica iron (PSI) can be used.

[0049] The step (b) is a step of washing and drying the toner base particles, in which the toner base particles prepared in the step (a) are washed with a washing solvent and dried after removing the macroparticles.

[0050] The removal of the large particles from the toner base particles can be performed by a known filtering device and method, and the washing and drying steps can also be performed by a known device and method.

[0051] The step (c) is a step of finally obtaining a toner composition by adding a toner external additive to the dried toner base particles recovered in the step (b).

[0052] The toner external additive includes those derived from the above-mentioned toner external additive composition and the toner external additive composition produced by the method for producing the toner external additive composition. EXAMPLES

[0053] The present invention will be described in more detail below with reference to preferred examples. However, it will be obvious to those skilled in the art that these examples are provided to more specifically explain the present invention and do not limit the scope of the present invention.

[0054] <Production Examples 1 to 7 and Comparative Production Examples 1 to 3: Production of Toner External Additive Compositions> Tin dioxide (SnO2) was added to a solution containing isobutyltriethoxysilane (IBTES), stirred, filtered and dried to obtain tin dioxide particles coated with isobutyltriethoxysilane. The obtained tin dioxide particles coated with isobutyltriethoxysilane were added to a solution containing aluminum hydroxide (Al(OH)3) and stirred to prepare toner additive particles. The contents of tin dioxide (SnO2), aluminum hydroxide (Al(OH)3) and isobutyltriethoxysilane (IBTES) are as shown in Table 1.

[0055] [Table 1]

[0056] <Examples 1 to 7 and Comparative Examples 1 to 3: Production of toner compositions> A latex resin was emulsion-polymerized, and the latex resin was mixed with a solvent, a pigment dispersion, a wax dispersion, a flocculant, and hydrophobic silica as another additive to produce toner base particles, which were then filtered to select the toner base particles. The toner base particles were then washed and dried. A toner composition was produced by adding a toner external additive derived from any one of the toner external additive compositions of Production Examples 1 to 7 and Comparative Production Examples 1 to 3 to the toner base particles. The contents of the toner base particles, the toner external additive, and the hydrophobic silica are as shown in Table 2 below.

[0057] [Table 2]

[0058] <Experimental Example 1: Measurement of powder fluidity> After 3 g of the toner composition of the examples and comparative examples was left for 2 hours under N / N environmental conditions of 23° C. and 55% relative humidity, 2 g of the toner composition was loaded on the top of a sieve consisting of an upper part (53 μm), a middle part (45 μm), and a lower part (38 μm). Then, the amplitude was fixed to Dial 3, and vibration was applied for 40 seconds. When the vibration stopped, the weight of the toner composition remaining in the upper part, middle part, or lower part having the corresponding diameter of the sieve was measured to measure the powder flowability, and the results are shown in Table 3 below. The powder flowability was calculated according to the following formula. [(m(53μm)×5 / 5+m(45μm)×3 / 5+m(38μm)×1 / 5)÷m(initial)]×100 *m (diameter): weight (g) of the toner composition remaining in the upper, middle or lower portion of the sieve having the specified diameter *m (initial): weight (g) of the toner composition initially loaded on the top of the sieve

[0059] <Experimental Example 2: Analysis of LL environmental charge> The toner composition and carrier of the examples and comparative examples were placed in a 50 ml container in amounts of 7 g and 93 g, respectively, and left for 10 hours under LL environmental conditions of 10° C. and 10% relative humidity, and then mixed for 10 minutes using a tumbler mixer. 1 g of the toner composition and carrier mixture was left in the LL environmental chamber for 5 minutes, and then placed in a cell of an Epping Q / M meter charge analyzer, and charge analysis was performed for 90 seconds. The weight of the cell after charge analysis was measured, and the initial weight was entered to derive the charge value, which is shown in Table 3 below.

[0060] <Experimental Example 3: Image chart analysis to determine whether ghosting occurs or not> Using the toner compositions of the Examples and Comparative Examples, an image chart for checking ghost development was printed, and then the occurrence of ghost development was confirmed.

[0061] The criteria for judging whether or not the ghost phenomenon occurred was as follows: when observing with the naked eye from a distance of about 30 cm from the image chart, if no ghost phenomenon was observed by any observer, it was judged as "excellent," if the ghost phenomenon was only slightly visible to some observers, it was judged as "good," and if the ghost phenomenon was clearly observed by all observers, it was judged as "poor."

[0062] The printed image chart is shown in Figure 2, where the area where the ghost phenomenon occurred is indicated by a dotted box. The analysis results of the image chart to determine whether the ghost phenomenon occurred are shown in Table 3 below.

[0063] <Experimental Example 4: Measurement of Image Density> 100 g of the toner compositions of the Examples and Comparative Examples were filled into a toner cartridge of a laser printer (model name: C-3010), and the image density of the pattern chart printed at regular intervals was measured using a SpectroEye colorimetric analysis device. The results are shown in Table 3 below.

[0064] <Experimental Example 5: Evaluation of durability> 100g of the toner compositions of the examples and comparative examples were filled into the toner cartridge of a laser printer (model name: C-3010), and the entire amount was printed out for the guaranteed number of pages of the laser printer to check whether a streak phenomenon occurred in the printing direction. The streak phenomenon occurs when the durability of the toner composition is poor, and the toner composition cannot withstand the pressure (stress) inside the cartridge, becoming fused or solidified, causing a streak defect in the printing direction.

[0065] The durability evaluation criteria were as follows: if no stripes were found with the naked eye in the printing direction on any of the prints out of the guaranteed print count, it was judged as "excellent"; if stripes were found in 5 points or less per page, it was judged as "average"; and if stripes were found in 10 points or more per page, it was judged as "poor".

[0066] The results of the durability evaluation are shown in Table 3 below.

[0067] [Table 3]

[0068] Referring to Table 3, it was confirmed that the toner compositions of Examples 1 to 7 had a lower LL environmental charge amount, which is an index of triboelectric charge amount, compared to the toner compositions of Comparative Examples 1 to 3, and therefore the ghost phenomenon was improved, the image density was increased, and the print quality was improved.

[0069] In particular, in the toner compositions of Examples 1 to 5, as the content of aluminum hydroxide increased, the LL environmental charge amount decreased, the ghost phenomenon was improved, and the image density increased.

[0070] Referring to the durability evaluation results in Table 3, it can be seen that the toner compositions of Examples 1 to 7 maintain excellent durability compared to Comparative Examples 1 to 3, even though some of the silane-based compounds used to coat the external additive particles in the compositions are replaced with aluminum hydroxide.

[0071] The above-described embodiment of the present invention should not be construed as limiting the technical idea of ​​the present invention. The scope of protection of the present invention is limited only by the matters described in the claims, and a person having ordinary skill in the technical field of the present invention may improve or modify the technical idea of ​​the present invention in various forms. Therefore, such improvements and modifications will also fall within the scope of protection of the present invention as long as they are obvious to a person having ordinary skill in the art.

Claims

1. a core comprising tin oxide, with the proviso that said core does not contain strontium titanate; 1. A toner external additive comprising particles comprising a silane-based compound and a shell in which aluminum hydroxide covers all or a part of the core.

2. 2. The toner external additive according to claim 1, wherein the silane compound is an alkoxysilane.

3. 2. The toner external additive according to claim 1, wherein the silane compound is an alkyltrialkoxysilane.

4. 2. The toner external additive according to claim 1, wherein the silane compound is isobutyltrialkoxysilane.

5. 2. The toner external additive according to claim 1, wherein the content of the tin oxide is in the range of 40 to 89.95% by weight, the content of the silane compound is in the range of 10 to 50% by weight, and the content of the aluminum hydroxide is in the range of 0.05 to 10% by weight.

6. A method for producing the toner external additive according to any one of claims 1 to 5, comprising the steps of: (A) adding tin oxide particles to a solution containing a silane-based compound and stirring the solution to obtain tin oxide particles coated with the silane-based compound; (B) dropping the silane-based compound-coated tin oxide particles obtained in (A) into a solution containing aluminum hydroxide and stirring the solution to obtain toner additive particles.

7. With respect to 100% by weight of the entire toner composition, 6. A toner composition comprising the external toner additive according to claim 1 in an amount of 0.1 to 1.5% by weight.

8. (a) emulsion-polymerizing a polymer latex using a resin monomer, mixing the polymer latex with a pigment dispersion, a wax dispersion, and an aggregating agent, and then carrying out an aggregating and coalescing process to prepare toner base particles; (b) separating the toner base particles, washing and drying the particles; (c) adding the external toner additive according to any one of claims 1 to 5 to the toner base particles.

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