Patent Grant
12130585
The present disclosure relates to an electrophotographic developer set comprising a toner and a powder adhesive functioning as an adhesive, and with which an electrostatic latent image is developed on a recording material by using an electrophotographic system to form a toner image and an adhesive portion by the powder adhesive, and the powder adhesive. The present disclosure also relates to a method for producing a bonded product by using the above electrophotographic developer set.
Conventionally, when making a paper bag on which different information is printed for each individual with a printer or a copier, a method of setting a pre-made paper bag in the printer or copier and printing on the paper bag has been used. The resulting problem arising when performing printing on a paper bag and on plain paper at the same time is that it takes time and effort to change the paper used in the printer from the paper bag to plain paper every time the print target is changed, or printing is performed on a wrong print target.
To address the above problems, a method has been proposed in which, in addition to image formation with toner by using an electrophotographic system, an adhesive portion derived from a pigment-free powder adhesive is also formed for paper bonding. A further method has been proposed in which printing on plain paper in accordance with the above method is simultaneously accompanied by processing of the plain paper into a paper bag. A toner set of a toner and a powder adhesive used in the method has been proposed.
Japanese Patent Application Publication No. 2006-171607 proposes an image forming method for forming an image and an adhesive portion by using an adhesive toner such that a lower limit temperature of an appropriate fixing temperature of the adhesive toner is lower than that of a toner used for image formation.
Japanese Patent Application Publication No. 2008-170659 proposes a powder adhesive for an electrophotographic system, wherein this powder adhesive having a cyclic polyolefin resin as a basic structure.
Japanese Patent Application Publication No. 2019-167471 proposes an adhesive material for an electrophotographic system, wherein this material using a styrene resin and a (meth)acrylate ester resin.
In the method described in Japanese Patent Application Publication No. 2006-171607, it is disclosed that by using an adhesive toner that a lower limit temperature of an appropriate fixing temperature of the adhesive toner is lower than that of a toner used for image formation, it is possible to melt the adhesive toner at a temperature at which the toner used for image formation is not melted.
However, strong adhesive strength may fail to be obtained in a case where a paper bag is produced, in accordance with the above method, by forming a toner image portion of toner and an adhesive portion of a powder adhesive on the paper, followed by overlaying of paper, with the toner image portion and the adhesive portion facing inward, and by melting of the adhesive portion. It has been further found that in a case where the adhesive portion is sufficiently melted by heating in order to obtain strong adhesive strength, a phenomenon (print transfer) may occur in that the image portion melts, whereupon part of the image portion is transferred to the paper opposite, hence it is difficult to achieve both print transfer and strong adhesive strength.
The powder adhesives disclosed in Japanese Patent Application Publication Nos. 2008-170659 and 2019-167471 are used in applications that involve stripping of the adhesive portion, and accordingly do not afford an adhesive strength strong enough to allow producing a paper bag.
The present disclosure provides an electrophotographic developer set comprising a toner and a powder adhesive, with which print transfer is unlikely and strong adhesive strength can be obtained, and a method for producing a bonded product using the electrophotographic developer set.
An electrophotographic developer set comprising
The present disclosure succeeds thus in providing an electrophotographic developer set comprising a toner and a powder adhesive, in which print transfer is unlikely, and which boasts strong adhesive strength, and a method for producing a bonded product using the electrophotographic developer set. Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings.
In the present disclosure, the notations “from XX to YY” and “XX to YY” representing a numerical range denote, unless otherwise stated, a numerical value range that includes the lower limit and the upper limit thereof, as endpoints.
In a case where numerical value ranges are described in stages, the upper limits and the lower limits of the respective numerical value ranges can be combined arbitrarily.
Further, methods for measuring physical properties will be described hereinbelow.
First, an example of a method for producing a paper bag by an electrophotographic system using an electrophotographic developer set comprising the above toner and powder adhesive will be described hereinbelow.
Initially, a toner image portion of toner and an adhesive portion made of powder adhesive are formed on the paper (forming step) using an electrophotographic system. To produce then a paper bag, the whole is heated to thereby fix (fixing step) the toner image portion and the adhesive portion on the paper, and then paper is overlaid so as to sandwich the adhesive portion, with further heating to melt the adhesive portion and thereby elicit bonding (bonding step). The paper overlaying method may involve folding of the paper or laying of a different piece of paper.
The inventors found that lowering adhesiveness between the toner and paper is important in order to prevent print transfer of an toner image portion in the bonding step. On the other hand, enhancing adhesiveness between the powder adhesive and paper is important in order to achieve strong adhesive strength. The inventors conducted diligent studies aimed at overcoming the above tradeoff in performance.
The present disclosure relates an electrophotographic developer set comprising
Print transfer suppression and strong adhesiveness could both be achieved by controlling the physical properties of the developer set so as to lie in the above ranges. Concerning the underlying reasons for this, the inventors focused on interactions between ester groups in the waxes contained in the toner and the powder adhesive, and hydroxyl groups in cellulose which is the main material of paper, and conjectured the following.
Multiple hydroxyl groups are present on the surface of cellulose, the hydroxyl groups being bonded to each other by hydrogen bonds, to thereby form paper as a result. Accordingly, the affinity between the powder adhesive and cellulose increases when the powder adhesive contains a large amount of ester groups capable of forming hydrogen bonds with hydroxyl groups. Thanks to this increase in affinity, wettability between the powder adhesive and cellulose improves, and the rate at which the powder adhesive permeates into the paper increases. Adhesiveness between the powder adhesive and the paper is improved as a result.
Waxes exhibit low viscosity when melted and accordingly the rate of wax permeation into the paper is likely to be improved when a large amount of ester groups is introduced into the wax. Therefore, in a case where a wax having a large amount of ester groups introduced therein is added to a powder adhesive, the wax permeates rapidly into the paper and, along with this, the totality of the powder adhesive permeates likewise into the paper; this results in greatly improved adhesiveness between the powder adhesive and paper.
On the other hand, waxes generally have low polarity and low affinity towards polar groups such as hydroxyl groups. Therefore, adding to a toner, or to a powder adhesive, a wax having a small amount of ester groups introduced thereinto results rather in hindered permeation of the toner or powder adhesive into the paper, and in lowered adhesiveness with paper.
In view of the above considerations, where Ea (mmol/g) denotes an ester group concentration of the wax contained in the toner, it is necessary that Ea lies in the range from 0.00 to 2.45 to lower the ester group concentration of the wax contained in the toner. Adhesiveness between the toner and paper can be reduced, and accordingly the occurrence of print transfer become less likely, by prescribing Ea to be 2.45 or lower.
Further, where Eb (mmol/g) denotes an ester group concentration of wax contained in the powder adhesive, it is necessary that Eb is 2.50 or higher to increase the ester group concentration of wax contained in the powder adhesive. By setting Eb to be 2.50 or higher, the adhesiveness between the powder adhesive and paper can be increased, and strong adhesive strength is obtained as a result. By setting Eb to be 3.60 or lower, it becomes possible to prevent excessive permeation of the powder adhesive into the paper, so that strong adhesive strength can be obtained as a result.
More preferably, Ea is from 0.00 to 1.95, and Eb is from 2.60 to 3.40.
To achieve both print transfer suppression and strong adhesive strength, where Na (mass %) denotes content of wax in the toner and Nb (mass %) denotes content of wax in the powder adhesive, it is necessary that a wax amount ratio Nb/Na is 0.80 or higher.
Setting herein Nb/Na is to be 0.80 or higher signifies that the amount of wax contained in the powder adhesive is larger than the amount of wax contained in the toner, or is not too small an amount. Hence, the endothermic quantity of the toner can be made smaller than the endothermic quantity of the powder adhesive. Therefore, the heat imparted by the fixing unit in the bonding step is robbed less readily during melting of the toner, and melting of the powder adhesive is less likely to be hindered.
The powder adhesive and paper can be bonded firmly as a result. When Nb/Na is increased, heat is robbed during melting of the powder adhesive, which hinders as a result melting of the toner; in consequence, adhesiveness between the toner and paper is lower, and print transfer suppression and strong adhesive strength can thus be combined.
Nb/Na is preferably from 1.00 to 6.00, more preferably from 1.10 to 2.50.
A compound having a molecular weight of 3000 or less and an endothermic peak of 80 J/g or more as measured by differential scanning calorimetry (DSC) is defined as a wax in the present disclosure.
Preferably, Ea and Eb satisfy
0.50≤Eb−Ea≤3.40.
The larger the difference between the Ea and the Eb, the higher is the level at which there can be achieved both the effect of lowering adhesiveness between the toner and paper, and the effect of increasing adhesiveness between the powder adhesive and paper. More preferably, Eb−Ea is from 0.70 to 3.40.
The above Ea and Eb can be controlled on the basis of the types and amount ratios of the waxes contained in the toner and the powder adhesive. Further, the above Na and Nb can be controlled on the basis of the amounts of the waxes contained in the toner and the powder adhesive.
The wax contained in the powder adhesive preferably contains at least one selected from the group consisting of ester waxes represented by Formulae (1) and (2) below.
In the formulae, 1 represents a positive integer from 2 to 12 (preferably from 2 to 4), and n and m each independently represent a positive integer from 12 to 20 (preferably from 14 to 20). Further, p represents a positive integer from 2 to 10 (preferably from 2 to 4), and q and r each independently represent a positive integer from 11 to 21 (preferably from 14 to 20).
The ester waxes represented by Formula (1) and (2) have a linear structure, and hence crystallize readily and exhibit a high degree of crystallinity in the powder adhesive. A powder adhesive of yet better durability can be accordingly obtained. In consequence, contamination of a developing member or the like is unlikely to occur, even in mass printing. The positions of the ester groups in the ester wax represented by Formula (1) and the ester wax represented by Formula (2) are close to each other, therefore the waxes interact strongly with hydroxyl groups in cellulose. In consequence, permeation of the powder adhesive into the paper is readily promoted as a result, and stronger adhesive strength can be achieved.
More preferably, the ester wax is a compound represented by Formula (1), of which 1 represents 2, and n and m each independently represent a positive integer of 14 to 20. More preferably, the wax contained in the powder adhesive contains the ester wax represented by Formula (1), and in Formula (1), 1 represents 2, and n and m each independently represent a positive integer of 14 to 20.
When 1 represents 2 and n and m each independently represent a positive integer of 14 to 20 in Formula (1), the positions of the two ester groups in the molecule are close to each other, and accordingly the wax crystallizes yet more readily, and a powder adhesive of yet higher durability can be obtained. More preferably, n and m each independently are from 16 to 20.
Preferably, the wax contained in the powder adhesive further contains a chain saturated hydrocarbon having a peak carbon number from 20 to 70 (preferably from 30 to 60). The above chain saturated hydrocarbon crystallizes faster than the above ester wax, and acts as a crystal nucleating agent for the ester wax. As a result, the crystallinity of the ester wax is increased, and a powder adhesive of yet better durability can be obtained.
The peak carbon number is a value resulting from dividing a peak value of molecular weight of the chain saturated hydrocarbon, obtained in a molecular weight measurement, by 14, which is the formula mass of CH2.
A content Nb1 of the ester wax in the powder adhesive is preferably from 8.0 mass % to 20.0 mass %, more preferably from 8.0 mass % to 15.0 mass %, and yet more preferably from 9.0 mass % to 12.0 mass %.
A content Nb2 of the chain saturated hydrocarbon having a peak carbon number from 20 to 70 in the powder adhesive is preferably from 0.1 mass % to 5.0 mass %, more preferably from 0.5 mass % to 3.0 mass %.
Preferably, the above Nb1 and Nb2 satisfy
2.00≤Nb1/Nb2≤25.00.
More preferably, Nb1/Nb2 is from 3.00 to 7.00.
Such a powder adhesive can be suitably used in electrophotographic processes, and allows obtaining strong adhesiveness.
Preferably, the content Nb of wax in the powder adhesive is from 8.0 mass % to 20.0 mass %. When Nb lies in the above range it becomes possible to prevent excessive permeation of the powder adhesive into paper, while improving adhesiveness between the powder adhesive and paper. Stronger adhesiveness is achieved as a result.
More preferably, Nb is from 10.0 mass % to 17.0 mass %, and yet more preferably from 10.0 mass % to 15.0 mass %.
Preferably, the content Na of wax in the toner is from 2.0 mass % to 15.0 mass %. The endothermic quantity of the toner can be curtailed, while lowering the adhesiveness between the toner and paper, by virtue of the fact that Na lies within the above range. Print transfer and strong adhesiveness both can be achieved at a yet higher level as a result.
More preferably, Na is from 5.0 mass % to 13.0 mass %, and yet more preferably from 5.0 mass % to 10.0 mass %.
The wax used in the toner is not particularly limited as long as it satisfies the above ester group concentration, and known waxes can be used herein. Specific examples of the wax include the following.
Hydrocarbon waxes (for instance petroleum waxes and derivatives thereof such as paraffin wax, microcrystalline wax and petrolatum; montan wax and derivatives thereof; hydrocarbon waxes and derivatives thereof obtained in accordance with the Fischer-Tropsch method; and polyolefin waxes and derivatives thereof such as polyethylene and polypropylene); natural waxes and derivatives thereof such as carnauba wax and candelilla wax; as well as ester waxes.
The term derivatives encompasses herein oxides, block copolymers with vinylic monomers, and graft-modified products.
Preferably, the wax contained in the toner is at least one selected from the group consisting of hydrocarbon waxes and ester waxes.
As the ester wax there can be used a monoester compound containing one ester bond per molecule, and a diester compound containing two ester bonds per molecule, and also multifunctional ester compounds such as trifunctional ester compounds containing three ester bonds per molecule, tetrafunctional ester compounds containing four ester bonds per molecule and hexafunctional ester compounds containing six ester bonds per molecule.
Preferably among the foregoing, the wax contains at least one compound selected from the group consisting of monoester compounds and diester compounds.
Specific examples of monoester compounds include waxes composed mainly of a fatty acid ester, such as carnauba wax and montan wax; waxes obtained by deacidifying part or the entirety of an acid component from a fatty acid ester, such as deacidified carnauba wax; waxes obtained through hydrogenation of vegetable oils; methyl ester compounds having a hydroxyl group; and saturated fatty acid monoesters such as stearyl stearate and behenyl behenate.
Specific examples of diester compounds include dibehenyl sebacate, nonanediol dibehenate, behenyl terephthalate and stearyl terephthalate. The wax may contain other known waxes, besides the above compounds. The waxes may be used as a single type alone; alternatively, two or more types may be used concomitantly.
The wax contained in the toner is preferably a saturated fatty acid monoester. Preferably, for instance, the toner contains an ester compound of a monoalcohol having 18 to 24 carbon atoms and a monocarboxylic acid having 18 to 24 carbon atoms. Behenyl behenate is more preferable.
Preferably the powder adhesive and the toner both contain at least one compound selected from the group consisting of monoester compounds and diester compounds.
Monoester compounds and diester compounds tend to exhibit a higher degree of crystallinity and a larger endothermic quantity than hydrocarbon waxes and trifunctional or higher ester compounds. When the powder adhesive and the toner satisfy the above conditions, it becomes therefore easier to match the melting behavior of the wax at the time of melting of the powder adhesive and the toner in the bonding step, and the effect derived from the above physical properties is readily brought out.
The thermoplastic resins contained in the toner and the powder adhesive are not particularly limited.
For instance, there can be used known thermoplastic resins such as polyester resins, vinyl resins, acrylic resins, styrene-acrylic resins, polyethylene, polypropylene, polyolefins, ethylene-vinyl acetate copolymer resins, and ethylene-acrylic acid copolymer resins. The toner and the powder adhesive may include a plurality of these resins. Further, the thermoplastic resins contained in the toner and the powder adhesive may be identical or may be different.
Preferably, the thermoplastic resins are a polyester resin or a styrene-acrylic resin, more preferably a styrene-acrylic resin, Preferably, the thermoplastic resins contained in the toner and the powder adhesive include at least one selected from the group consisting of polyester resins and styrene-acrylic resins, and include more preferably a styrene-acrylic resin. The content of the styrene-acrylic resin in the thermoplastic resins is preferably 50 mass % to 100 mass %, more preferably 80 mass % to 100 mass %, and yet more preferably 90 mass % to 100 mass %.
A known polyester resin can be used as the polyester resin.
Specific examples include dibasic acids and derivatives thereof (carboxylic acid halides, esters, and acid anhydrides) and condensed polymers of dihydric alcohols. If necessary, trivalent or higher polybasic acids and derivatives thereof (carboxylic acid halides, esters, and acid anhydrides), monobasic acids, trihydric or higher alcohols, and monohydric alcohols may be used.
Examples of the dibasic acid include aliphatic dibasic acids such as maleic acid, fumaric acid, itaconic acid, oxalic acid, malonic acid, succinic acid, dodecylsuccinic acid, dodecenylsuccinic acid, adipic acid, azelaic acid, sebacic acid, decane-1,10-dicarboxylic acid, and the like; aromatic dibasic acids such as phthalic acid, tetrahydrophthalic acid, hexahydrophthalic acid, tetrabromophthalic acid, tetrachlorophthalic acid, chlorendic acid, humic acid, isophthalic acid, terephthalic acid, 2,6-naphthalenedicarboxylic acid, and the like; and the like.
Examples of the dibasic acid derivatives include carboxylic acid halides, esters and acid anhydrides of the above-mentioned aliphatic dibasic acid and aromatic dibasic acid.
Meanwhile, examples of the dihydric alcohol include acyclic aliphatic diols such as ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, diethylene glycol, dipropylene glycol, triethylene glycol, neopentyl glycol, and the like; bisphenols such as bisphenol A, bisphenol F, and the like; alkylene oxide adducts of bisphenol A such as bisphenol A ethylene oxide adduct, bisphenol A propylene oxide adduct, and the like; aralkylene glycols such as xylylene diglycol and the like; and the like.
Examples of the trivalent or higher polybasic acid and anhydrides thereof include trimellitic acid, trimellitic anhydride, pyromellitic acid, pyromellitic anhydride, and the like.
Examples of the polymerizable monomer capable of forming the styrene-acrylic resin include styrene-based monomers such as styrene, α-methylstyrene, and divinylbenzene; unsaturated carboxylic acid esters such as methyl acrylate, butyl acrylate, methyl methacrylate, and 2-hydroxyethyl methacrylate, t-butyl methacrylate, and 2-ethylhexyl methacrylate; unsaturated carboxylic acids such as acrylic acid and methacrylic acid; unsaturated dicarboxylic acids such as maleic acid; unsaturated dicarboxylic acid anhydrides such as maleic anhydride; nitrile vinyl monomers such as acrylonitrile; halogen-containing vinyl monomers such as vinyl chloride; nitrovinyl monomers such as nitrostyrene; and the like. These can be used alone or in combination of two or more.
The unsaturated carboxylic acid ester is preferably an alkyl (meth)acrylate ester with 1 to 8 (more preferably 2 to 6) carbon atoms in the alkyl group. Preferably, the styrene-acrylic resin is a copolymer of styrene and an alkyl (meth)acrylate ester with 1 to 8 (more preferably 2 to 6) carbon atoms in the alkyl group.
The content of the thermoplastic resin in the powder adhesive is preferably from 75.0 mass % to 92.0 mass %, more preferably from 80.0 mass % to 90.0 mass %.
The content of the thermoplastic resin in the toner is preferably from 75.0 mass % to 92.0 mass %, more preferably from 80.0 mass % to 90.0 mass %.
An ester group concentration Ec1 of the thermoplastic resin contained in the toner or an ester group concentration Ec2 of the thermoplastic resin contained in the powder adhesive each is preferably from 0.00 mmol/g to 2.50 mmol/g, and more preferably from 1.50 mmol/g to 2.20 mmol/g.
Prescribing the above range signifies lowering the ester group concentration of the thermoplastic resin. By prescribing the above range, the ester groups in the thermoplastic resin do not readily hinder interactions between the ester groups of the wax and the hydroxyl groups of paper, and as a result the effects of print transfer suppression and strong adhesive strength can be attained more readily.
A difference between the ester group concentration of the thermoplastic resin contained in the toner and the ester group concentration of the thermoplastic resin contained in the powder adhesive is preferably from 0.00 mmol/g to 1.50 mmol/g, more preferably from 0.00 mmol/g to 0.50 mmol/g. The effects of print transfer suppression and strong adhesive strength can be attained more readily thanks to the closeness of the ester group concentrations of the thermoplastic resins contained in the toner and the powder adhesive.
The ester group concentration of the thermoplastic resins can be controlled on the basis of the types and amount ratios of the monomers used in the thermoplastic resins.
The toner and the powder adhesive may include a colorant. Examples of the colorant include a black colorant, a yellow colorant, a magenta colorant, and a cyan colorant.
The black colorant is exemplified by carbon black.
Examples of the yellow colorant include yellow pigments represented by monoazo compounds; disazo compounds; condensed azo compounds; isoindolinone compounds; isoindoline compounds; benzimidazolone compounds; anthraquinone compounds; azo metal complexes; methine compounds; allylamide compounds, and the like. Specific examples include C. I. Pigment Yellow 74, 93, 95, 109, 111, 128, 155, 174, 180, 185, and the like.
Examples of the magenta colorant include magenta pigments represented by monoazo compounds; condensed azo compounds; diketopyrrolopyrrole compounds; anthraquinone compounds; quinacridone compounds; basic dye lake compounds; naphthol compounds; benzimidazolone compounds; thioindigo compounds; perylene compounds, and the like. Specific examples include C. I. Pigment Red 2, 3, 5, 6, 7, 23, 48:2, 48:3, 48:4, 57:1, 81:1, 122, 144, 146, 150, 166, 169, 177, 184, 185, 202, 206, 220, 221, 238, 254, and 269, C. I. Pigment Violet 19 and the like.
Examples of the cyan colorant include cyan pigments represented by copper phthalocyanine compounds and derivatives thereof; anthraquinone compounds; basic dye lake compounds, and the like. Specific examples include C. I. Pigment Blue 1, 7, 15, 15:1, 15:2, 15:3, 15:4, 60, 62, and 66.
Further, various dyes conventionally known as colorants can be used together with the pigment.
The amount of the colorant in the toner is preferably from 1.0% by mass to 20.0% by mass.
The content of the colorant in the powder adhesive is preferably from 0.0 mass % to 1.0 mass %.
The toner and the powder adhesive may contain known materials such as a charge control agent, a charge control resin and a pigment dispersant, as needed.
As the case may require, the toner and the powder adhesive may be mixed with an external additive or the like to adhere to the surface of the toner or the powder adhesive.
Examples of the external additive include inorganic fine particles selected from silica fine particles, alumina fine particles and titania fine particles, and complex oxides of the foregoing. Examples of complex oxides include silica aluminum fine particles and strontium titanate fine particles.
The content of the external additive in the toner is preferably from 0.01 mass % to 10.0 mass %, more preferably from 0.1 mass % to 4.0 mass %.
The content the external additive in the powder adhesive is preferably from 0.01 mass % to 10.0 mass %, more preferably from 0.1 mass % to 4.0 mass %.
The difference between the amount of the external additive in the toner and the amount of the external additive in the powder adhesive is preferably from 0.0% by mass to 2.5% by mass, and more preferably from 0.0% by mass to 2.0% by mass.
A ratio of the content of the external additive in the toner and the content of the external additive in the powder adhesive (content of external additive in toner: content of external additive in powder adhesive) is preferably 1.0:8.0 to 8.0:1.0, more preferably 1.0:4.0 to 4.0:1.0, and yet more preferably 1.0:2.0 to 2.0:1.0.
The glass transition temperatures (Tg) of the toner and of powder adhesive are preferably from 45° C. to 60° C., respectively. Within the above range, the toner or powder adhesive can be suitably used in an electrophotographic process, and the effects of print transfer suppression and strong adhesive strength can be brought out at a yet higher level.
The difference between the Tg of the toner and the Tg of the powder adhesive is preferably from 0° C. to 10° C., more preferably from 0° C. to 7° C. Thanks to the closeness between the Tg of the toner and the Tg of the powder adhesive, the molten states of the foregoing in the bonding step can be brought close to each other, and accordingly the effects of print transfer suppression and strong adhesive strength can be readily elicited. The Tg of the toner and Tg of the powder adhesive can be controlled on the basis of the type and amount ratio of the monomers used in the thermoplastic resins of the toner and of the powder adhesive, or on the basis of the types and amount ratios of the waxes that are used.
The weight-average particle diameter (D4) of the toner is preferably from 4.0 μm to 15.0 μm. Within the above range the molten state in the bonding step can be made uniform, and accordingly a toner can be obtained that is yet less likely to exhibit print transfer.
The weight-average particle diameter (D4) of the powder adhesive is preferably from 4.0 μm to 20.0 μm. Within the above range, the thickness of the adhesive portion can be made sufficiently large while uniformizing the molten state in the bonding step, so that a stronger adhesive strength can be obtained as a result.
Further, a difference between the weight-average particle diameter (D4) of the toner and the weight-average particle diameter (D4) of the powder adhesive is preferably from 0.0 μm to 5.0 μm. Thanks to the closeness of the weight-average particle diameters (D4) of the toner and of the powder adhesive, the molten states of the foregoing in the bonding step can be brought close to each other, and accordingly the effects of print transfer suppression and strong adhesive strength can be readily elicited. The weight-average particle diameters (D4) of the toner and the powder adhesive can be controlled on the basis of the production methods of the toner and of the powder adhesive.
Preferably, the peak molecular weight of a main peak in both the toner and the powder adhesive is from 10,000 to 40,000. Within the above range, the toner or powder adhesive can be suitably used in an electrophotographic process, and the effects of print transfer suppression and strong adhesive strength can be brought out at a yet higher level.
Preferably, the difference between the peak molecular weight of the toner and the peak molecular weight of the powder adhesive is from 0 to 15,000. By virtue of the fact that the peak molecular weights of the toner and the powder adhesive are close to each other, the molten states of the foregoing in the bonding step can be brought close to each other, and accordingly, the effects of print transfer suppression and strong adhesive strength can be readily elicited. The peak molecular weight can be controlled on the basis of the production conditions of the thermoplastic resins of the toner and the powder adhesive.
The toner or powder adhesive can be produced in accordance with a known method, such as pulverization, suspension polymerization, emulsification aggregation or dissolution suspension; the production method is not particularly limited herein.
Preferably, the powder adhesive is a powder adhesive comprising a thermoplastic resin, a compound represented by above Formula (1), of which 1 represents 2, and n and m each independently represent a positive integer of 14 to 20, and a chain saturated hydrocarbon having a peak carbon number of 20 to 70, wherein
Such a powder adhesive can be suitably used in electrophotographic processes, and allows obtaining strong adhesiveness.
Preferably, Nb1 is from 8.0 mass % to 15.0 mass %, more preferably from 9.0 mass % to 12.0 mass %. More preferably, Nb2 is from 0.5 mass % to 3.0 mass %.
More preferably, Nb1/Nb2 is from 3.00 to 7.00.
Specifically described hereinbelow is an example of an image forming apparatus and a processing device for performing bonding process of paper, which an electrophotographic developer containing a toner and a powder adhesive can be suitably used.
Overall Apparatus Configuration
First, the overall configuration of the image forming apparatus will be described with reference to
First, the internal configuration of the apparatus body 10 will be described. As shown in
The sheet cassette 8 is retractably inserted into the housing 19 at the bottom of the apparatus body 10, and accommodates a large number of sheets P. The sheets P accommodated in the sheet cassette 8 are fed from the sheet cassette 8 by a feeding member such as a feeding roller, and are transported by a transport roller 8a in a state of being separated one by one by a pair of separating rollers. It is also possible to feed the sheets set on an open tray 20 (
The image forming unit 1e is a tandem type electrophotographic unit provided with four process cartridges 7n, 7y, 7m, and 7c, a scanner unit 2, and a transfer unit 3. The term process cartridge denotes a unit in which multiple components involved in the image forming process are integrally and replaceably configured into a unit.
The apparatus body 10 is provided with a cartridge support portion 9 supported by the housing 19, and the process cartridges 7n, 7y, 7m, and 7c are detachably mounted on mounting portions 9n, 9y, 9m, and 9c provided in the cartridge support portion 9. The cartridge support portion 9 may be a tray member that can be pulled out from the housing 19.
The process cartridges 7n, 7y, 7m, and 7c have a substantially common configuration except for the types of powders accommodated in four powder accommodating portions 104n, 104y, 104m, and 104c. That is, each process cartridge 7n, 7y, 7m, and 7c includes a photosensitive drum 101 as an image bearing member, a charging roller 102 as a charging device, powder accommodating portions 104n, 104y, 104m, and 104c that accommodate powders, and a developing roller 105 that performs development using the powder.
Of the four powder accommodating portions, the three powder accommodating portions 104y, 104m, and 104c on the right side in the figure accommodate yellow, magenta and cyan printing toners Ty, Tm, and Tc, respectively, as toners (first powder) for forming a visible image on the sheet P. Meanwhile, a powder adhesive Tn, which is a powder (second powder) for performing a bonding process after printing, is accommodated in the powder accommodating portion 104n on the leftmost side in the figure.
The powder accommodating portions 104y, 104m, and 104c are all examples of the first accommodating portion that accommodates the printing toner, and the powder accommodating portion 104n is an example of the second accommodating portion that accommodates the powder adhesive. Further, the process cartridges 7y, 7m, and 7c are all examples of the first process unit that forms a toner image using a printing toner, and the process cartridge 7n is an example of the second process unit that forms an image of a powder adhesive in a predetermined application pattern.
When printing a black image such as text, the image is expressed in process black in which yellow (Ty), magenta (Tm), and cyan (Tc) toners are superimposed. However, for example, a fifth process cartridge that uses a black printing toner may be added to the image forming unit 1e so that the black image can be expressed by the black printing toner. Such options are not limiting, and the type and number of printing toners can be changed according to the application of the image forming apparatus 1.
The scanner unit 2 is arranged below the process cartridges 7n, 7y, 7m, and 7c and above the sheet cassette 8. The scanner unit 2 is an exposure means for irradiating the photosensitive drum 101 of each process cartridge 7n, 7y, 7m, and 7c with laser light G and writing an electrostatic latent image.
The transfer unit 3 includes a transfer belt 3a as an intermediate transfer body (secondary image bearing member). The transfer belt 3a is a belt member wound around a secondary transfer inner roller 3b and a tension roller 3c, and faces the photosensitive drum 101 of each process cartridge 7n, 7y, 7m, and 7c on the outer peripheral surface.
On the inner peripheral side of the transfer belt 3a there are arranged primary transfer rollers 4, at positions corresponding to respective photosensitive drums 101. Further, a secondary transfer roller 5 as a transfer means is arranged at a position opposing the secondary transfer inner roller 3b. A transfer nip 5n between the secondary transfer roller 5 and the transfer belt 3a is a transfer section (secondary transfer section) in which the toner image is transferred from the transfer belt 3a to the sheet P.
The first fixing unit 6 is arranged above the secondary transfer roller 5. The first fixing unit 6 is a heat fixing type fixing unit having a heat roller 6a as a fixing member and a pressure roller 6b as a pressing member. The heat roller 6a is heated by a heat generating element such as a halogen lamp, a ceramic heater or a heating mechanism of induction heating type. The pressure roller 6b is pressed against the heat roller 6a by an urging member such as a spring, and generates a pressurizing force that pressurizes the sheet P passing through the nip portion (fixing nip 6n) of the heat roller 6a and the pressure roller 6b.
The housing 19 is provided with a discharge port 12 (first discharge port), which is an opening for discharging the sheet P from the apparatus body 10, and a discharge unit 34 is arranged in the discharge port 12. The discharge unit 34, which is a discharge means, uses a so-called triple roller having a first discharge roller 34a, an intermediate roller 34b, and a second discharge roller 34c.
Further, a switching guide 33, which is a flap-shaped guide for switching the transport path of the sheet P, is provided between the first fixing unit 6 and the discharge unit 34. The switching guide 33 is rotatable around a shaft portion 33a so that a tip 33b reciprocates in the direction of arrow c in the figure.
The apparatus body 10 is provided with a mechanism for performing double-sided printing.
A motor (not shown) is connected to the discharge unit 34 and configured so that the rotation direction of the intermediate roller 34b can be forward and reverse. Further, a double-sided transport path 1r is provided as a transport path connected in a loop to a main transport path 1m. The sheet P where an image has been formed on the first surface while passing through the main transport path 1m is nipped and transported by the first discharge roller 34a and the intermediate roller 34b with the switching guide 33 which is rotated clockwise.
After the rear end of the sheet P in the traveling direction passes through the switching guide 33, the switching guide 33 rotates counterclockwise, the intermediate roller 34b reverses, and the sheet P is reversely transported to the double-sided transport path 1r. Then, an image is formed on the second surface of the sheet P while the sheet P passes through the main transport path 1m again with the front and back reversed.
The sheet P after double-sided printing is nipped and transported by the intermediate roller 34b and the second discharge roller 34c with the switching guide 33 rotated counterclockwise, and is discharged from the apparatus body 10.
Further, the transport path passing through the transport roller 8a, the transfer nip 5n, and the fixing nip 6n in the apparatus body 10 constitutes the main transport path 1m in which an image is formed on the sheet P. The main transport path 1m extends from the bottom to the top through one side in the horizontal direction with respect to the image forming unit 1e when viewed from the main scanning direction (the width direction of the sheet perpendicular to the transport direction of the sheet transported along the main transport path 1m) at the time of image formation.
In other words, the apparatus body 10 is a so-called vertical transport type (vertical path type) printer in which the main transport path 1m extends in a substantially vertical direction. When viewed in the vertical direction, the first discharge tray 13, the intermediate path 15, and the sheet cassette 8 overlap each other. Therefore, the moving direction of the sheet when the discharge unit 34 discharges the sheet P in the horizontal direction is opposite to the moving direction of the sheet when the sheet P is fed from the sheet cassette 8 in the horizontal direction.
Further, from the viewpoint of
Bonding Unit
As shown in
Further, the post-processing unit 30 is provided with a first discharge tray 13 for rotatably holding the tray switching guide 13a, an intermediate path 15, and a second discharge tray 35. The first discharge tray 13 is provided on the upper surface of the post-processing unit 30, and is located on the top face (
The post-processing unit 30 has a positioning portion (for example, a convex shape that engages with a concave portion of the housing 19) for positioning the housing 39 with respect to the housing 19 (first housing) of the apparatus body 10. Further, the post-processing unit 30 is provided with a drive source and a control unit separate from the apparatus body 10, and the connector 36 of the post-processing unit 30 and the connector 37 of the apparatus body 10 are joined together to electrically connect the post-processing unit to the apparatus body 10. As a result, the post-processing unit 30 is brought into an operating state based on a command from the control unit provided in the apparatus body 10 by using the electric power supplied through the apparatus body 10.
Process Cartridge
As described above, the process cartridges 7n, 7y, 7m, and 7c have substantially the same configuration except for the types of powders accommodated in the four powder accommodating portions 104n, 104y, 104m, and 104c. Here, the process cartridge 7n will be described as a representative cartridge.
The photosensitive drum 101 is rotatably attached to the photosensitive member unit CC via a bearing (not shown). Further, the photosensitive drum 101 is rotationally driven in the clockwise direction (arrow w) in the figure according to the image forming operation by receiving the driving force of the drive motor as a driving means (driving source) (not shown). Further, in the photosensitive member unit CC, the charging roller 102 and a cleaning member 103 for charging the photosensitive drum 101 are arranged around the photosensitive drum 101.
The developing unit DT is provided with the developing roller 105 as a developer carrying member that comes into contact with the photosensitive drum 101 and rotates counterclockwise (arrow d) in the figure. The developing roller 105 and the photosensitive drum 101 rotate so that their surfaces move in the same direction at the facing portion (contact portion).
Further, a developer supply roller 106 (hereinafter, simply referred to as “supply roller”) as a developer supply member that rotates in the clockwise direction (arrow e) in the drawing is arranged in the developing unit DT. The supply roller 106 and the developing roller 105 rotate so that their surfaces move in the same direction at the facing portion (contact portion).
The supply roller 106 acts to supply a powder adhesive (the printing toner in the case of process cartridges 7y, 7m, and 7c) onto the developing roller 105 and to peel off the powder adhesive (the printing toner in the case of process cartridges 7y, 7m, and 7c) remaining on the developing roller 105 from the developing roller 105.
Further, a developing blade 107 as a developer regulating member that regulates the layer thickness of the powder adhesive (the printing toner in the case of process cartridges 7y, 7m, and 7c) supplied on the developing roller 105 by the supply roller 106 is arranged in the developing unit DT.
The powder adhesive (the printing toner in the case of process cartridges 7y, 7m, and 7c) is stored as powder in the powder accommodating portion 104n. Further, a rotatably supported transport member 108 is provided in the powder accommodating portion 104n. A stirring member 108 rotates in the clockwise direction (arrow f) in the figure to stir the powder stored in the powder accommodating portion 104n and transports the powder to the developing chamber 109 provided with the developing roller 105 or the supply roller 106.
Here, the photosensitive member unit CC and the developing unit DT can also be configured as separate photoconductive unit cartridge and developing unit cartridge to enable detachable attachment thereof to the image forming apparatus body. Further, the units can also be configured as a powder cartridge that has only the powder accommodating portion 104 and the transport member 108 and is detachable from the apparatus body.
Image Forming Operations
Next, the image forming operations performed by the image forming apparatus 1 will be described with reference to
When image data to be printed and a print execution command are input to the image forming apparatus 1, the control unit of the image forming apparatus 1 starts a series of operations (image forming operations) for transporting the sheet P to form an image, and if necessary, for performing post-processing with the post-processing unit 30. In the image forming operations, first, as shown in
The process cartridges 7n, 7y, 7m, and 7c are sequentially driven in parallel with the feeding of the sheet P, and the photosensitive drum 101 is rotationally driven in the clockwise direction (arrow w) in the figure. At this time, the photosensitive drum 101 is uniformly charged on the surface by the charging roller 102.
Further, the scanner unit 2 irradiates the photosensitive drum 101 of each process cartridge 7n, 7y, 7m, and 7c with a laser beam G modulated based on the image data to form an electrostatic latent image on the surface of the photosensitive drum 101. Next, the electrostatic latent image on the photosensitive drum 101 is developed as a powder image by the powder borne on the developing rollers 105 of each process cartridge 7n, 7y, 7m, and 7c.
The powder adhesive layer formed by the powder adhesive Tn on the photosensitive drum 101 by the development is different from the toner image (normal toner image) of the printing toner for recording an image such as a figure and text on the sheet P in that the powder adhesive layer is not intended to transmit visual information. However, in the following description, the layer of the powder adhesive Tn formed in a shape corresponding to an application pattern by the electrophotographic process in order to apply the powder adhesive Tn to the sheet P in a predetermined application pattern is also handled as a “toner image”.
The transfer belt 3a rotates in the counterclockwise direction (arrow v) in the figure. The toner image formed in the process cartridges 7n, 7y, 7m, and 7c is primarily transferred from the photosensitive drum 101 to the transfer belt 3a by the electric field formed between the photosensitive drum 101 and the primary transfer roller 4.
The toner image that is borne on the transfer belt 3a and has reached the transfer nip 5n is secondarily transferred by the electric field formed between the secondary transfer roller 5 and the secondary transfer inner roller 3b to the sheet P that has been transported along the main transport path 1m.
After that, the sheet P is transported to the first fixing unit 6 to undergo heat fixing treatment. That is, when the sheet P passes through the fixing nip 6n, the toner image on the sheet P is heated and pressurized, so that the printing toners Ty, Tm, and Tc and the powder adhesive Tn are melted and then fixed, so that an image fixed to the sheet P is obtained.
Regardless of whether single-sided printing or double-sided printing is performed, the sheet P discharged from the apparatus body 10 is nipped between the intermediate roller 34b and the second discharge roller 34c, as shown in
In the first route R1 shown in
In the second route R2 shown in
An intermediate path 15 is provided between the first fixing unit 6 and the folding device 31 in the second route R2. The intermediate path 15 is a sheet transport path that passes through the upper surface portion (top surface portion) of the image forming apparatus 1 and extends substantially parallel to the first discharge tray 13 below the first discharge tray 13. The intermediate path 15 and the first discharge tray 13 are inclined upward in the vertical direction toward the folding device 31 in the horizontal direction. Therefore, the inlet of the folding device 31 (guide roller pair (31c and 31d) described hereinbelow) is located vertically above the outlet (the nip of the intermediate roller 34b and the second discharge roller 34c) of the apparatus body 10.
The folding device 31 has four rollers: a first guide roller 31c, a second guide roller 31d, a first folding roller 31a, and a second folding roller 31b, and a draw-in portion 31e. The first guide roller 31c and the second guide roller 31d are a pair of guide rollers that nip and transport the sheet P received from the transfer path (intermediate path 15 in the present embodiment) on the upstream side of the folding device 31. The first folding roller 31a and the second folding roller 31b are a pair of folding rollers that feed out the sheet P while bending the sheet.
A spacing M (
The folding process performed by the folding device 31 will be described with reference to
First, the front end q of the sheet P fed out from the discharge unit 34 is pulled into the guide roller pair (31c and 31d) as shown in
As the sheet P is pulled in by the guide roller pair (31c and 31d), the front end q advances to the back of the draw-in portion 31e while sliding in contact with the wall 31g. Eventually, the front end q abuts against an end portion 31h of the draw-in portion 31e as shown in
Where the sheet P is further pulled in by the guide roller pair (31c and 31d) from the state shown in
Here, a depth N (
The folding device 31 described above is an example of folding means, and for example, a folding mechanism that forms a crease by pressing a blade against the sheet P and pushing it into the nip portion of the roller pair may be used. Further, the contents of the folding process are not limited to folding in half, and for example, a folding mechanism that executes Z folding or tri-folding may be used.
Since the folding device 31 is configured of a rotating roller and a fixed draw-in portion 31e, the drive mechanism can be simplified as compared with a folding mechanism using a reciprocating blade. Further, since the folding device 31 may be provided with a draw-in portion 31e having a depth N of half the sheet length in addition to the four rollers, the post-processing unit 30 can be miniaturized.
The sheet P that has passed through the folding device 31 is transported to the second fixing unit 32 as shown in
The pressure roller 32a is pressed against the heat roller 32a by an urging member such as a spring and generates a pressurizing force that pressurizes the sheet P passing through the nip portion (bonding nip) of the heat roller 32b and the pressure roller 32a.
The sheet P folded by the folding device 31 is bonded in the folded state by undergoing a bonding process (second heat fixing to the image surface coated with the powder adhesive Tn) by the second fixing unit 32. That is, when the sheet P passes through the bonding nip, the powder adhesive Tn on the sheet P is heated and pressurized in a remelted state, so as to adhere to the facing surface (in the folded state, the surface facing the image surface of the sheet P onto which the toner image of the powder adhesive Tn has been transferred). Then, when the powder adhesive Tn cools and hardens, the image surface and the facing surface of the sheet P are joined (bonded) using the powder adhesive Tn as an adhesive.
As shown in
The joining location of the folded sheet P can be changed by the application pattern of the powder adhesive Tn on the sheet P.
Further, the image forming apparatus 1 can output any of the deliverables illustrated in
For example, when the deliverables of
The image recorded by the image forming apparatus 1 using the printing toner can include a format (unchanged portion) when using preprint paper and a variable portion such as personal information. Therefore, it is possible to output the deliverable bonded by the bonding process from the base paper such as blank paper which is not the preprinted paper as described above. However, the image forming apparatus 1 can also be used in applications in which the preprinted paper is used as a recording medium and the printing process and bonding process of the variable portion are performed.
Method for Producing a Bonded Product (Deliverable)
The method for producing a bonded product is a method for producing a bonded product resulting from bonding at least one sheet of paper via an adhesive portion by using the above electrophotographic developer set, wherein
The bonded product may be in the form obtained by folding and bonding one sheet of paper via an adhesive portion, or in the form obtained by bonding two sheets of paper via an adhesive portion. The bonded product has, for example, a bag-like or tubular form.
When paper is bonded via an adhesive portion, the surface A on which the adhesive portion is present will be present on two surfaces in the bonded product, but the adhesive portion formed by the powder adhesive may be formed on at least one of the two surfaces.
For instance, an image portion and an adhesive portion are formed on at least one of the surfaces of the paper that constitutes the surface A, as in step (A). An adhesive portion is formed on one of the surfaces of the paper that constitutes the surface A while an image portion is formed on the other surface, as in step (B).
In a case where the bonded product is produced from a single sheet of paper, the toner image portion of toner and the adhesive portion of the powder adhesive may be formed on at least one of the surfaces of the paper. A toner image portion may or may not be formed on the other surface of the paper.
In a case where two sheets of paper are bonded together to produce a bonded product, a toner image portion and an adhesive portion may be formed on the surface of one of the paper sheets constituting the surface A, in step (A). A toner image portion or an adhesive portion may or may not be formed on the other paper sheet.
In a case where a bonded product is produced through bonding of two sheets of paper, an adhesive portion is formed on the surface of one of the paper sheets constituting the surface A, and the toner image portion is formed on the surface of the other paper sheet constituting the surface A, in step (B).
Either the toner image portion or the adhesive portion may be formed first; alternatively, both the toner image portion and the adhesive portion may be formed simultaneously. Forming and fixing of the image portion and forming and fixing of the adhesive portion can be performed for instance using the above-described image forming apparatus. A known electrophotographic method can be resorted to.
After the toner image portion and the adhesive portion have been formed, in the case of one sheet of paper, the paper is folded to sandwich the adhesive portion, and in the case of two sheets of paper, these are stacked to sandwich the adhesive portion. Then, the paper is bonded by heating to melt the adhesive portion, and a bonded product (deliverable) is obtained. Such a bonding step can be performed by using, for example, the above-mentioned image forming apparatus or sheet processing device.
Methods for measuring physical properties are described hereinbelow.
Method for Identifying the Molecular Structure of Thermoplastic Resins and Waxes, and Measuring the Content Na of Wax in the Toner, the Content Nb of Wax in the Powder Adhesive, and the Content of Thermoplastic Resin in the Powder Adhesive or the Toner
A pyrolysis-gas chromatography mass spectrometer (hereafter pyrolysis GC/MS) and NMR are used for identification of the molecular structure of the thermoplastic resins and waxes, and for measurement of the content Na of wax in the toner, and the content Nb of wax in the powder adhesive.
In pyrolysis GC/MS, it is possible to determine the monomers that make up the total amount of resin in a sample and determine the peak area of each monomer, but for quantification, the peak intensity of a sample with a known concentration as a reference needs to be standardized. Meanwhile, in NMR, it is possible to determine and quantify the constituent monomers without using a sample having a known concentration.
Therefore, depending on the situation, the constituent monomers are determined by comparing the spectra of both NMR and pyrolysis GC/MS.
Specifically, when the amount of the resin component insoluble in deuterated chloroform, which is an extraction solvent at the time of NMR measurement, is less than 5.0% by mass, quantification is performed by NMR measurement.
Meanwhile, when the resin component insoluble in deuterated chloroform, which is an extraction solvent at the time of NMR measurement, is present in an amount of 5.0% by mass or more, NMR and pyrolysis GC/MS measurements are performed, and pyrolysis GC/MS measurement is performed for deuterated chloroform insoluble matter.
In this case, first, NMR measurement is performed for deuterated chloroform soluble matter to determine and quantify the constituent monomers (quantification result 1). Next, pyrolysis GC/MS measurement is performed on the deuterated chloroform soluble matter, and the peak area of the peak attributed to each constituent monomer is determined. Using the quantification result 1 obtained by NMR measurement, the relationship between the amount of each constituent monomer and the peak area of pyrolysis GC/MS is determined.
Next, pyrolysis GC/MS measurement of deuterated chloroform insoluble matter is performed, and the peak area of the peak attributed to each constituent monomer is determined. Based on the relationship between the amount of each constituent monomer obtained by measuring the deuterated chloroform soluble matter and the peak area of pyrolysis GC/MS, the constituent monomer in deuterated chloroform insoluble matter is quantified (quantification result 2).
Then, the quantification result 1 and the quantification result 2 are combined to obtain the final quantification result of each constituent monomer. Specifically, the following operations are performed.
(1) A total of 50 mg of toner or powder adhesive is precisely weighed in an 8 mL glass sample bottle, 1 mL of deuterated chloroform is added, a lid is closed, and the components is dispersed and dissolved by an ultrasonic disperser for 1 h. Then, filtration is performed with a membrane filter having a pore diameter of 0.4 μm and the filtrate is collected. At this time, the deuterated chloroform insoluble matter remains on the membrane filter.
(2) 1H-NMR measurement is performed on the filtrate, and the spectrum is attributed to each constituent monomer in the resin to obtain a quantitative value.
(3) Where the deuterated chloroform insoluble matter needs to be analyzed, it is analyzed by pyrolysis GC/MS. If necessary, derivatization treatment such as methylation is performed.
NMR Measurement Conditions
In the present disclosure the ester group concentration is defined as the number of ester groups (mmol/g) contained in a wax per molecular weight. The ester group concentrations Ea and Eb in the wax are calculated on the basis of the molecular structure of the wax, obtained in accordance with the above measurements, and the content of the wax in the toner and the powder adhesive.
The ester group concentration Ea of wax contained in the toner is calculated as
Ea=1000×aa/na (mmol/g),
Similarly, the ester group concentration Eb of wax contained in the powder adhesive is calculated as
Eb=1000×ab/nb (mmol/g),
Further, Ea and Eb for a case where a plurality of waxes is present are calculated as average values resulting from multiplying respective contents as coefficients as follows.
In a case for instance where there are present three types of wax, namely waxes 1 to 3, Ea is calculated in accordance with the formula below, where Ea1 denotes the ester group concentration and Na1 the content of wax 1, Ea2 denotes the ester group concentration and Na2 the content of wax 2, and Ea3 denotes the ester group concentration and Na3 the content of wax 3.
Ea=Ea1×(Na1/(Na1+Na2+Na3))+Ea2×(Na2/(Na1+Na2+Na3))+Ea3×(Na3/(Na1+Na2+Na3))
In this case the number of waxes that may be used simultaneously is not limited. Also, Eb is calculated similarly to the above formula.
Method for Calculating the Ester Group Concentration of a Thermoplastic Resin
Where Ec denotes the ester group concentration of a thermoplastic resin, Ec is calculated on the basis of the molecular structure and mass ratio of the constituent monomers for the thermoplastic resin, obtained in the above measurement.
The ester group concentration Ec of the thermoplastic resin is given by
Ec=1000×ac/nc (mmol/g),
In a case where the thermoplastic resin is composed of a plurality of monomers, the ester group concentration is similarly determined for each monomer.
From the ester group concentration of each monomer and the respective content (mass %) of the structure derived from each monomer in the thermoplastic resin, the ester group concentration is calculated by multiplying respective contents as respective coefficients as follows.
For instance, Ec for a thermoplastic resin made up of a structure derived from three types of monomer, namely monomers 1 through 3, is calculated on the basis of the formula below, where Ec1 is the ester group concentration and Nc1 the constituent ratio (mass % in the thermoplastic resin) of monomer 1, Ec2 is the ester group concentration and Nc2 the constituent ratio of monomer 2, and Ec3 is the ester group concentration and Nc3 the constituent ratio of monomer 3.
Ec=Ec1×(Nc1/(Nc1+Nc2+Nc3))+Ec2×(Nc2/(Nc1+Nc2+Nc3))+Ec3×(Nc3/(Nc1+Nc2+Nc3))
The number of monomers that may be used simultaneously in this case is not limited.
In a case where the thermoplastic resin contains a plurality of resins, the ester group concentration is calculated as an average value obtained by multiplying contents (mass %) as respective coefficients, similarly to the calculation example of ester group concentration of a wax.
Method for Measuring Glass Transition Temperature (Tg)
The glass transition temperature (Tg) of the thermoplastic resin and so on is measured using a differential scanning calorimeter “Q1000” (manufactured by TA Instruments). The melting points of indium and zinc are used for temperature correction of the device detector, and the heat of fusion of indium is used for the correction of calorific value.
Specifically, 1 mg of the sample is precisely weighed, placed in an aluminum pan, and an empty aluminum pan is used as a reference. Using a modulation measurement mode, the measurement is performed in the range of 0° C. to 100° C. at a temperature rise rate of 1° C./min and a temperature modulation condition of ±0.6° C./60 sec. Since the specific heat change is obtained in the temperature rise process, the intersection of the line between the midpoint of a baseline from before to after the specific heat change and the differential thermal curve is defined as the glass transition temperature (Tg).
Method for Measuring Weight Average Particle Diameter (D4) of Powder Adhesive and Toner
The weight-average particle diameter (D4) is calculated as follows.
A precision particle size distribution measurement device operating on the aperture impedance method and equipped with a 100 μm aperture tube “Coulter Counter Multisizer 3” (registered trademark, manufactured by Beckman Coulter Co., Ltd.) aperture impedance method is used as a measuring device. The attached dedicated software “Beckman Coulter Multisizer 3 Version 3.51” (manufactured by Beckman Coulter Co., Ltd.) is used for setting the measurement conditions and analyzing the measurement data. The measurement is performed with 25,000 effective measurement channels.
A solution obtained by dissolving special grade sodium chloride in ion-exchanged water to a concentration of 1.0%, for example, “ISOTON II” (manufactured by Beckman Coulter Co., Ltd.) can be used as an electrolytic aqueous solution to be used for the measurement.
The dedicated software is configured as follows prior to the measurement and analysis.
On the “Change Standard Measurement Method (SOMME)” screen of the dedicated software, the total count number in the control mode is set to 50,000 particles, the measurement number is set to 1, and the Kd value is set to a value obtained using “Standard Particles 10.0 μm” (manufactured by Beckman Coulter Co., Ltd.). The threshold and noise level are automatically set by pressing the “Threshold/Noise Level Measurement Button”. Further, the current is set to 1,600 μA, the gain is set to 2, the electrolyte to ISOTON II, and a check is entered for “Flash the Aperture Tube After Measurement”.
On the “Conversion Setting from Pulse to Particle Diameter” screen of the dedicated software, the bin interval is set to a logarithmic particle diameter, the particle diameter bins are set to 256 particle diameter bins, and the particle diameter range is set from 2 μm to 60 μm.
The specific measurement method is as follows.
(1) 200.0 mL of the electrolytic aqueous solution is placed in a 250 mL glass round-bottomed beaker dedicated to Multisizer 3, the beaker is set on a sample stand, and stirred counter-clockwise at a rate of 24 rotations per second of the stirrer rod. Then, contamination and air bubbles in the aperture tube are removed by the “Flash the Aperture Tube” function of the dedicated software.
(2) 30.0 mL of the electrolytic aqueous solution is placed in a 100 mL glass flat-bottomed beaker. 0.3 mL of a diluted solution obtained by three-fold by mass dilution of “CONTAMINON N” (a 10% aqueous solution of a pH 7 neutral detergent for cleaning precision measurement instruments, comprising a nonionic surfactant, an anionic surfactant, and an organic builder; manufactured by Wako Pure Chemical Industries, Ltd.) with ion-exchanged water is added thereto as a dispersant.
(3) An ultrasonic dispersing unit “Ultrasonic Dispersion System Tetora 150” (produced by Nikkaki Bios Co., Ltd.), which has an electrical output of 120 W and is equipped with two built-in oscillators with an oscillation frequency of 50 kHz disposed so that their phases are displaced by 180 degrees, is prepared. 3.3 L of ion-exchanged water is poured into the water tank of the ultrasonic dispersing unit, and 2.0 mL of the CONTAMINON N is added into the water tank.
(4) The beaker of (2) above is set in a beaker fixing hole of the ultrasonic dispersing unit, and the ultrasonic dispersing unit is operated. Then, the height position of the beaker is adjusted to maximize the resonance state of the surface of the aqueous electrolytic solution in the beaker.
(5) 10 mg of the measurement sample is added bit by bit and dispersed in the aqueous electrolytic solution in the beaker of (4) above while irradiating the aqueous electrolytic solution with ultrasonic waves. Then, the ultrasonic dispersion treatment is continued for another 60 seconds. During the ultrasonic dispersion, the temperature of water in the water tank is adjusted, as appropriate, to be from 10° C. to 40° C.
(6) The aqueous electrolytic solution of (5) above, in which the toner particles have been dispersed, is added dropwise with a pipette into the round-bottom beaker of (1) above placed in a sample stand, and the measurement concentration is adjusted to 5%. Measurements are performed until the number of measured particles reaches 50,000.
(7) The measurement data is analyzed with the dedicated software included with the device, and the weight-average particle diameter (D4) is calculated. The weight-average particle diameter (D4) is the “Average Diameter” on the “Analysis/Volumetric Statistical Value (Arithmetic Average)” screen when the dedicated software is set to graph/vol %.
Method for Measuring Molecular Weight Distribution and Peak Molecular Weight
A molecular weight distribution and peak molecular weight are measured by gel permeation chromatography (GPC), as follows.
First, the measurement sample is dissolved in tetrahydrofuran (THF). Then, the obtained solution is filtered through a solvent-resistant membrane filter “Myshori Disc” (manufactured by Tosoh Corporation) having a pore diameter of 0.2 μm to obtain a sample solution. The sample solution is adjusted so that the concentration of the fraction soluble in THF is 0.8% by mass. This sample solution is used for measurement under the following conditions.
For calculating the molecular weight of the sample, a molecular weight calibration curve created using standard polystyrene resins (for example, trade name “TSK standard polystyrene F-850, F-450, F-288, F-128, F-80, F-40, F-20, F-10, F-4, F-2, F-1, A-5000, A-2500, A-1000, and A-500”, manufactured by Tosoh Corporation) is used. From the obtained molecular weight distribution, the largest peak is used as the main peak, and the molecular weight value of this peak is used as the peak molecular weight.
Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited to these examples. In the examples, the parts are based on mass unless otherwise specified.
The composition and physical properties of the wax used for examples and comparative examples are shown in Table 1.
In the table, HNP-9 is a hydrocarbon wax produced by Nippon Seiro Co., Ltd. (having a peak carbon number of 33).
Production Example of a Polyester Resin
Into a reaction vessel equipped with a stirrer, a thermometer, a nitrogen introduction tube, a dewatering tube and a pressure-reducing device there were added 1.00 mol of terephthalic acid, 0.65 mol of a propylene oxide 2 mol adduct of bisphenol A, and 0.35 mol of ethylene glycol, in molar ratio, as monomers, with heating up to a temperature of 130° C. while under stirring. Thereafter, 0.52 parts of tin(II) 2-ethylhexanoate as an esterification catalyst were added to 100.00 parts of the above monomers, the temperature was raised to 200° C., and condensation polymerization was carried out up to a desired molecular weight.
Further, 3.00 parts of trimellitic anhydride were added to 100.00 parts of the above monomer mixture, to obtain a polyester resin.
The obtained polyester resin had a peak molecular weight of 12,000, a glass transition temperature (Tg) of 75° C., an acid value of 8.2 mgKOH/g, and an ester group concentration of 5.41 mmol/g.
Production Example of Powder Adhesive 1
A mixture resulting from mixing the above materials was kept at 60° C., and was stirred at 500 rpm using T. K. Homomixer (by Tokushu Kika Kogyo Co., Ltd.), to elicit uniform dissolution and prepare a polymerizable monomer composition.
Meanwhile, 850.0 parts of a 0.10 mol/L-Na3PO4 aqueous solution and 8.0 parts of 10% hydrochloric acid were added into a vessel provided with a high-speed stirring device CLEARMIX (by M Technique Co. Ltd.), the revolutions were adjusted to 15,000 rpm, and the temperature was raised to 70° C. Then 127.5 parts of a 1.0 mol/L-CaCl2) aqueous solution were added thereto, to prepare an aqueous medium that contained a calcium phosphate compound.
The above polymerizable monomer composition was charged into the aqueous medium, followed by addition of 7.0 parts of t-butyl peroxypivalate as a polymerization initiator, and granulation for 10 minutes while keeping revolutions at 15,000 rpm/min. Thereafter, the stirrer was changed from a high-speed stirrer to a propeller stirring blade, and the reaction was carried out at 70° C. for 5 hours while under reflux, after which the liquid temperature was adjusted to 85° C., and the reaction was left to proceed for a further 2 hours.
Once the polymerization reaction was over, the obtained slurry was cooled, and hydrochloric acid was further added to the slurry to adjust the pH to 1.4, whereupon the mixture was stirred for 1 hour to thereby dissolve a calcium phosphate salt.
Thereafter, the slurry was washed with water in an amount of thrice the amount of the slurry, with filtration and drying, followed by classifying to yield powder adhesive particles.
Thereafter, 2.0 parts of silica fine particles (number-average particle diameter of primary particles: 10 nm; BET specific surface area: 170 m2/g) having undergone a hydrophobic treatment using dimethyl silicone oil (20 mass %) were added, as an external additive, to 100.0 parts of the powder adhesive particles, and the whole was mixed using a Mitsui Henschel mixer (by Mitsui Miike Engineering Corporation), at 3,000 rpm for 15 minutes, to yield Powder adhesive 1.
Production Examples of Powder Adhesives 2 to 13 and 15 to 18
Powder adhesives 2 to 13 and 15 to 18 were obtained in the same way as in the production example of Powder adhesive 1, except that the type and addition amount of the waxes were changed as shown in Table 2.
In the table, EVA denotes an ethylene-vinyl acetate copolymer resin (ULTRASEN 685, by Tosoh Corporation).
Production Example of Powder Adhesive 14
The above materials were premixed in a Henschel mixer (by Nippon Coke & Engineering Co., Ltd.) and were then melt-kneaded in a twin-screw kneading extruder (by Ikegai Corp.: model PCM-30).
The obtained kneaded product was cooled, coarsely pulverized using a hammer mill, and then pulverized using a mechanical crusher (T-250, by Turbo Kogyo Co., Ltd.); the obtained finely pulverized powder was classified using a multi-grade classifier relying on the Coanda effect, to yield powder adhesive particles having a weight-average particle diameter (D4) of 5.8 μm.
Thereafter, 2.0 parts of silica fine particles (number-average particle diameter of primary particles: 10 nm; BET specific surface area: 170 m2/g) having undergone a hydrophobic treatment using dimethyl silicone oil (20 mass %) were added, as an external additive, to 100.0 parts of the powder adhesive particles, and the whole was mixed using a Mitsui Henschel mixer (by Mitsui Miike Engineering Corporation) at 3,000 rpm for 15 minutes to yield Powder adhesive 14.
The above materials were premixed in a Henschel mixer (by Nippon Coke & Engineering Co., Ltd.) and were then melt-kneaded in a twin-screw kneading extruder (by Ikegai Corp.: model PCM-30).
The obtained kneaded product was cooled, coarsely pulverized using a hammer mill, and then pulverized using a mechanical crusher (T-250, by Turbo Kogyo Co., Ltd.); the obtained finely pulverized powder was classified using a multi-grade classifier relying on the Coanda effect, to yield powder adhesive particles having a weight-average particle diameter (D4) of 9.0 μm.
Thereafter, 2.0 parts of silica fine particles (number-average particle diameter of primary particles: 10 nm; BET specific surface area: 170 m2/g) having undergone a hydrophobic treatment using dimethyl silicone oil (20 mass %) were added, as an external additive, to 100.0 parts of the powder adhesive particles, and the whole was mixed using a Mitsui Henschel mixer (by Mitsui Miike Engineering Corporation) at 3,000 rpm for 15 minutes to yield Powder adhesive 19.
Production Example of Powder Adhesive 20
Preparation of a Core Resin Particle Dispersion Liquid
The above components were mixed and dissolved to prepare a solution.
Meanwhile, 10 parts of an anionic surfactant (DOWFAX 2A1 by The Dow Chemical Company) were dissolved in 250 parts of ion-exchanged water, and the above solution was then added, with dispersion and emulsification in a flask (monomer emulsion A).
Further, 1 part of the anionic surfactant (DOWFAX 2A1 by The Dow Chemical Company) was similarly dissolved in 555 parts of ion-exchanged water, and the resulting solution was placed in a polymerization flask.
A reflux tube was set in the polymerization flask, and the polymerization flask was heated in a water bath up to 75° C. and held at that temperature, while under slow stirring and under injection of nitrogen.
Then a solution resulting from dissolving 9 parts of ammonium persulfate in 43 parts of ion-exchanged water was added dropwise over 20 minutes into the polymerization flask via a metering pump, followed by dropwise addition of the monomer emulsion A over 200 minutes via a metering pump.
Thereafter, the polymerization flask was held at 75° C. for 3 hours while under continued stirring, and first-stage polymerization was terminated. As a result, there was obtained a core resin particle dispersion liquid precursor having a volume-average particle diameter of 190 nm, a glass transition temperature of 53° C. and a weight-average molecular weight of 33,000.
Next, the temperature was lowered to room temperature, and thereafter 600 parts of 2-ethylhexyl acrylate and 850 parts of ion-exchanged water were added to the polymerization flask, with slow stirring for 2 hours. Thereafter, the temperature was raised to 70° C. while under continued stirring, and 4.5 parts of ammonium persulfate and 110 parts of ion-exchanged water were added dropwise over 20 minutes via a metering pump. Thereafter, the polymerization flask was held for 3 hours while under continued stirring, and polymerization was terminated.
As a result of the above process, there was obtained a core resin particle dispersion liquid having a volume-average particle diameter of 260 nm, a weight-average molecular weight of 200,000, and solid component amount of 33 mass %.
Preparation of a Shell Resin Particle Dispersion Liquid
The above components were mixed and dissolved to prepare a solution.
Meanwhile, 10 parts of an anionic surfactant (DOWFAX 2A1 by The Dow Chemical Company) were dissolved in 250 parts of ion-exchanged water, and the above solution was then added, with dispersion and emulsification in a flask (monomer emulsion A).
Further, 1 part of the anionic surfactant (DOWFAX 2A1 by The Dow Chemical Company) was similarly dissolved in 555 parts of ion-exchanged water, and the resulting solution was placed in a polymerization flask.
A reflux tube was set in the polymerization flask, and the polymerization flask was heated in a water bath up to 75° C., and was held at that temperature, while under slow stirring and under injection of nitrogen.
Then a solution resulting from dissolving 9 parts of ammonium persulfate in 43 parts of ion-exchanged water was added dropwise over 20 minutes into the polymerization flask via a metering pump, followed by dropwise addition of the monomer emulsion A over 200 minutes via a metering pump.
Thereafter, the polymerization flask was held at 75° C. for 3 hours while under continued stirring, and first-stage polymerization was terminated. As a result, there was obtained a shell resin particle dispersion liquid having a volume-average particle diameter of 190 nm, a glass transition temperature of 53° C., a weight-average molecular weight of 33,000, and solid component amount of 42 mass %.
Production of a Powder Adhesive
(DOWFAX 2A1, by The Dow Chemical Company)
The above components, as a core forming material, were charged into a 3 L reaction vessel equipped with a thermometer, a pH meter and a stirrer, and the pH was adjusted to 3.0 by addition of 1.0% nitric acid at a temperature of 25° C.; thereafter, 23 parts of a prepared aqueous solution of aluminum sulfate were added to be dispersed for 6 minutes while under dispersing at 5,000 rpm using a homogenizer (Ultra-Turrax T50, by IKA Japan K.K.).
Thereafter, a stirrer and a mantle heater were set in the reaction vessel, and the vessel was heated while under stirring. Once the volume-average particle diameter reached 5.0 μm, the temperature was maintained, and 170 parts of the shell resin particle dispersion liquid as a shell forming material were charged into the reaction vessel. After holding for 30 minutes, pH was adjusted to 9.0 using a 1% aqueous solution of sodium hydroxide. Thereafter the temperature was raised to 90° C., and the vessel was held at 98° C. After holding for 10.0 hours, the vessel was cooled down to 30° C. using cooling water. Thereafter, the slurry was washed with water in an amount of thrice the amount of the slurry, with filtration and drying, followed by classifying to yield powder adhesive particles having a weight-average particle diameter (D4) of 5.9 μm.
Thereafter, 2.0 parts of silica fine particles (number-average particle diameter of primary particles: 10 nm; BET specific surface area: 170 m2/g) having undergone a hydrophobic treatment using dimethyl silicone oil (20 mass %) were added, as an external additive, to 100.0 parts of the powder adhesive particles, and the whole was mixed using a Mitsui Henschel mixer (by Mitsui Miike Engineering Corporation) at 3,000 rpm for 15 minutes to yield Powder adhesive 20.
The physical characteristics of the obtained Powder adhesives 1 to 20 were measured in accordance with the above methods. The results are given in Table 3.
Production Example of Toner 1
(C. I. Pigment Blue 15:3, by Dainichiseika Color & Chemicals Mfg. Co., Ltd.)
The above materials were placed in an Attritor (by Mitsui Miike Engineering Corporation), and were dispersed at 220 rpm for 5 hours, using zirconia particles having a diameter of 1.7 mm, to yield a pigment dispersion liquid.
The above materials were mixed and added to the pigment dispersion liquid. The obtained mixture was kept at 60° C., and was stirred at 500 rpm using T. K. Homomixer (by Tokushu Kika Kogyo Co., Ltd.), to elicit uniform dissolution, and prepare a polymerizable monomer composition.
Meanwhile, 850.0 parts of a 0.10 mol/L-Na3PO4 aqueous solution and 8.0 parts of 10% hydrochloric acid were added into a vessel provided with a high-speed stirring device CLEARMIX (by M Technique Co. Ltd.), the revolutions were adjusted to 15,000 rpm, and the temperature was raised to 70° C. Then 127.5 parts of a 1.0 mol/L-CaCl2) aqueous solution were added thereto to prepare an aqueous medium that contained a calcium phosphate compound.
The above polymerizable monomer composition was charged into the aqueous medium, followed by addition of 7.0 parts of t-butyl peroxypivalate as a polymerization initiator, and granulation for 10 minutes while keeping revolutions at 15,000 rpm. Thereafter, the stirrer was changed from a high-speed stirrer to a propeller stirring blade, and the reaction was carried out at 70° C. for 5 hours while under reflux, after which the liquid temperature was adjusted to 85° C., and the reaction was left to proceed for a further 2 hours.
Once the polymerization reaction was over, the obtained slurry was cooled, and hydrochloric acid was further added to the slurry to adjust the pH to 1.4, whereupon the mixture was stirred for 1 hour to thereby dissolve a calcium phosphate salt.
Thereafter, the slurry was washed with water in an amount of thrice the amount of the slurry, with filtration and drying, followed by classifying to yield a toner particle.
Thereafter, 2.0 parts of silica fine particles (number-average particle diameter of primary particles: 10 nm; BET specific surface area: 170 m2/g) having undergone a hydrophobic treatment using dimethyl silicone oil (20 mass %) were added, as an external additive, to 100.0 parts of the toner particle, and the whole was mixed using a Mitsui Henschel mixer (by Mitsui Miike Engineering Corporation) at 3,000 rpm for 15 minutes to yield Toner 1.
Production Example of Toners 2 to 11
Toners 2 to 11 were obtained in the same way as in the production example of Toner 1, except that the type and addition amount of the wax were changed, as shown in Table 4.
The physical characteristics of the obtained Toners 1 to 11 were measured in accordance with the above methods. The results are given in Table 5.
Respective developer sets were prepared using the obtained powder adhesives and toners, in the combinations given in Table 6. Developer sets 1 to 22 were used as examples, and Developer sets 23 to 29 were used as comparative examples.
The performance of the obtained Developer sets 1 to 29 was evaluated in accordance with the following methods. All evaluations were performed in a normal-temperature, normal-humidity environment (25° C./50% RH); the paper used was GFC-081 (81.0 g/m2) (by Canon Marketing Japan Inc.). The results are given in Table 7.
Evaluation of Adhesive Strength and Print Transfer
A commercially available Canon laser beam printer LBP712Ci was used to prepare a sample image for evaluation. By changing the software, the printer was modified so that it could work even if all the cartridges were not set. In addition, the laid-on level of powder adhesive and the toner (mg/cm2) could be adjusted arbitrarily.
The toner contained in the cyan cartridge of LBP712Ci was extracted, and the cartridge was filled with 150 g of the toner of each developer set and set in the cyan station. Further, the toner contained in the black cartridge was extracted, and the cartridge was filled with 150 g of the powder adhesive of each developer set, and set in the black station.
Using this printer, as illustrated in
Further, the powder adhesive was printed at a laid-on level of 0.5 mg/cm2 on a 4 cm area by opening a front end margin of 8 cm on another paper (image B).
The obtained image A was cut to a width of 3 cm to obtain sample A. Similarly, the image B was cut to obtain sample B.
Bonding of a Sample Image for Evaluation
As illustrated in
Evaluation of Adhesive Strength
A Tencilon universal testing machine RTG-1225 (manufactured by A & D Co., Ltd.) was used to evaluate the adhesive strength. A parallel tightening type jaw was used as a jig, and the samples laminated as shown in
Evaluation of Print Transfer
Each sample after peeling as described above was evaluated for print transfer through measurement of the density of the toner that migrated onto the paper side originally having no toner printed thereon. A reflectometer (“REFLECTOMETER MODEL TC-6DS” by Tokyo Denshoku Co., Ltd.) was used for measuring density. The reflectance Dr (%) of the print transfer portion and the reflectance Ds (%) of a white background portion of the paper were measured, and a calculation was performed in accordance with the formula below.
Print transfer density (%)=Dr(%)−Ds(%)
The lower this value, the greater is the degree to which print transfer can be suppressed.
Evaluation of Durability
An image having image coverage of 1% was outputted in 15,000 prints, using a printer in which the above-mentioned toners and powder adhesives were set. After output of the image, the cartridge filled with the powder adhesive was taken out and disassembled, and the number of vertical streaks appearing on the developing roller was ascertained using an optical microscope. A smaller number of vertical streaks entails a lower likelihood of member contamination, and better durability.
While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.
This application claims the benefit of Japanese Patent Application No. 2020-130345, filed Jul. 31, 2020, which is hereby incorporated by reference herein in its entirety.
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| 2020-130345 | Jul 2020 | JP | national |
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