Elastic body for blade and cleaning blade having the elastic body

Abstract

The object of the present invention is to provide a cleaning blade with excellent durability. As a solution, the present invention provides an elastic body for a blade, the contact portion of which contains polyurethane containing reactive silicone, and the reactive silicone has a phenyl group and two or more active hydrogen groups.

Description

[Technical Field]

[0001] The present invention relates to an elastic body for a blade used in an electrophotographic apparatus, and a cleaning blade having the elastic body for a blade. [Background technology]

[0002] Electrophotographic devices such as copiers, printers, facsimiles, and multifunction devices use blades such as cleaning blades, developing blades, conductive blades, polishing blades, and coating blades. A blade consists of an elastic body and a support member, and the elastic body is usually made of thermosetting polyurethane with appropriate hardness and elasticity. In recent years, there has been a demand for longer life for components such as blades in electrophotographic devices to reduce the frequency of photosensitive unit replacement. Furthermore, elastic materials for blades are also required to contribute to the long life of the entire system by preventing filming (adhesion) of toner and external additives onto the photosensitive drum and reducing wear on the photosensitive drum.

[0003] In order to extend the life of the blade, methods have been proposed for increasing the hardness of the contact portion that contacts the photosensitive member, etc. For example, Patent Document 1 proposes an elastic body in which the edge layer (contact portion) and the base layer (back portion) are made of different polyurethane materials, and only the edge layer is made to have a high hardness. Also, Patent Document 2 proposes an elastic body in which only the image carrier contact portion of an elastic body made of a single polyurethane is impregnated with an isocyanate compound, and only the image carrier contact portion is made to have a high hardness. Furthermore, in Patent Document 3, the present applicant has proposed a cleaning blade that uses polyurethane urea using a specific diaminobenzoic acid ester-based curing agent, and that has higher hardness and durability than other polyurethanes or polyurethane ureas. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 4818945 [Patent Document 2] Japanese Patent Application Laid-Open No. 2005-156696 [Patent Document 3] Japanese Patent Application Publication No. 2019-197175 Summary of the Invention [Problem to be solved by the invention]

[0005] An object of the present invention is to provide a cleaning blade having excellent durability. [Means for solving the problem]

[0006] The means for solving the problems of the present invention are as follows. 1. The contact portion contains polyurethane containing reactive silicone, The elastic body for blades is characterized in that the reactive silicone has a phenyl group and two or more active hydrogen groups. 2. The elastic body for blades according to 1., wherein the reactive silicone further comprises a methoxy group. 3. The elastic body for a blade according to 1. or 2., wherein the back surface portion contains a polymer compound having a different composition from that of the contact portion. 4. A cleaning blade, characterized in that the elastic body for a blade according to any one of 1. to 3. is attached to a support member. [Effects of the Invention]

[0007] The elastic body for blades of the present invention has excellent durability. [Brief explanation of the drawings]

[0008] [Figure 1] 10 is a schematic diagram of an elastic body for a blade in which the contact portion and the back surface portion have different compositions. DETAILED DESCRIPTION OF THE INVENTION

[0009] ·Elastic material for blades The contact portion of the elastic body for blades (hereinafter also referred to simply as "elastic body") of the present invention contains polyurethane containing reactive silicone, and this reactive silicone has a phenyl group and two or more active hydrogen groups. The size of the blade elastic body is not particularly limited, but for example, the width is about 5 mm to 20 mm, and the thickness is about 1 mm to 3 mm. The length of the elastic body is selected appropriately depending on the width of the paper to be printed, but for example, when used for A4 size paper, it is about 220 mm.

[0010] In the blade elastic body of the present invention, the abutting portion contains a polyurethane containing a specific reactive silicone. Specifically, the abutting portion is made of a cured material composition containing at least a polyol, a polyisocyanate, and a reactive silicone. The blade elastic body of the present invention may be made entirely of a cured material composition of a single composition, or the back portion may be made of a cured material composition of a different composition from the abutting portion. When the back portion is made of a cured material composition of a different composition from the abutting portion, the polymer compound contained in the material composition constituting the back portion is preferably one that can form a covalent bond with the polyurethane contained in the abutting portion, specifically, polyurethane, polyurea, or polyurethane urea.

[0011] FIG. 1 shows a schematic diagram of an elastic body for a blade, the contact portion and the back surface of which have different compositions. Examples of elastic bodies for blades 1 in which the contact portion 11 and the back portion 12 have different compositions include a structure in which the contact portion 11 is provided on the entire surface of one of the elastic bodies for blades 1 (for example, FIG. 1A), and a structure in which the contact portion 11 is provided along only one long side of the elastic body for blades 1 (for example, FIG. 1B). When the contact portion 11 and the back portion 12 have different compositions, it is preferable that the contact portion 11 and the back portion 12 have different colors in order to improve workability and reduce work errors when joining the elastic body for blades 1 to a support member.

[0012] Polyol The polyol may be any polyol used as a polyurethane material, without any particular limitation, such as polyether polyol, polyester polyol, polycarbonate polyol, etc. Two or more compatible polyols may also be used in combination. The number-average molecular weight of these polyols is preferably 1,000 or more and 4,000 or less.

[0013] Examples of polyether polyols include polyethylene glycol, polypropylene glycol, and polytetramethylene glycol.

[0014] Examples of polyester polyols include those obtainable by reacting dicarboxylic acids with glycols in accordance with conventional methods. Examples of dicarboxylic acids include aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, and 2,6-naphthalenedicarboxylic acid, aliphatic dicarboxylic acids such as adipic acid, azelaic acid, and sebacic acid, hydroxycarboxylic acids such as hydroxybenzoic acid, and ester-forming derivatives thereof. These may be used alone or in combination of two or more. Examples of glycols include aliphatic glycols such as ethylene glycol, 1,4-butanediol, diethylene glycol, neopentyl glycol, 3-methyl-1,5-pentanediol, 1,9-nonanediol, and triethylene glycol, alicyclic glycols such as 1,4-cyclohexanedimethanol, aromatic diols such as p-xylenediol, and polyoxyalkylene glycols such as polyethylene glycol, polypropylene glycol, and polytetramethylene glycol. These may be used alone or in combination of two or more.

[0015] Other polyester polyols include, for example, those obtainable by ring-opening polymerization of lactone using a diol as an initiator. Examples of diols include ethylene glycol, propylene glycol, 1,3-propylene glycol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, neopentyl glycol, diethylene glycol, 4-oxa-2,6-heptanediol, 4-oxaheptane-1,7-diol, 1,10-decanediol, etc. These may be used alone or in combination of two or more. Examples of lactones include β-propiolactone, γ-butyrolactone, δ-valerolactone, ε-caprolactone, β-methyl-δ-valerolactone, etc. These may be used alone or in combination of two or more.

[0016] Examples of polycarbonate polyols include reaction products of dialkyl carbonates and diols. Examples of dialkyl carbonates include dialkyl carbonates such as dimethyl carbonate and diethyl carbonate, diaryl carbonates such as diphenyl carbonate, and alkylene carbonates such as ethylene carbonate. These may be used alone or in combination of two or more.

[0017] Examples of diols include 1,4-butanediol, diethylene glycol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 2-methyl-1,8-octanediol, 1,9-nonanediol, 1,10-dodecanediol, 2-ethyl-1,6-hexanediol, 3-methyl-1,5-pentanediol, 2,4-dimethyl-1,5-pentanediol, neopentyl glycol, 1,3-cyclohexanediol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, 2,2'-bis(4-hydroxycyclohexyl)-propane, etc. These may be used alone or in combination of two or more.

[0018] Polyisocyanate As the polyisocyanate, any polyisocyanate that is used as a polyurethane material can be used without any particular limitation, and examples thereof include 4,4'-diphenylmethane diisocyanate (MDI), 1,5-naphthalene diisocyanate (NDI), 4,4'-dicyclohexylmethane diisocyanate (hydrogenated MDI), carbodiimide-modified MDI, 2,4-tolylene diisocyanate (2,4-TDI), 2,6-tolylene diisocyanate (2,6-TDI), 3,3'-bitrylene-4,4'-diisocyanate, and 3,3'-dimethyldiphenylmethane. Examples of the isocyanate include diisocyanates such as 4,4'-tolylene diisocyanate, 2,4-tolylene diisocyanate uretidinedione (a dimer of 2,4-TDI), metaphenylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, orthotolidine diisocyanate, xylene diisocyanate, paraphenylene diisocyanate, and lysine diisocyanate; triisocyanates such as triphenylmethane-4,4',4"-triisocyanate; and polymeric MDI. These may be used alone or in combination of two or more.

[0019] Reactive silicone The reactive silicone used in the present invention has a phenyl group and two or more active hydrogen groups. The number of these functional groups means the number of functional groups per molecule, and if the number of functional groups per molecule varies, it means the average value. The reactive silicone has a phenyl group, which improves compatibility with polyurethane, and the silicone moieties are less likely to aggregate in the polyurethane. The reactive silicone preferably has one or more phenyl groups, more preferably has 1.5 or more phenyl groups, and even more preferably has two or more phenyl groups. The reactive silicone has an active hydrogen group that reacts with an isocyanate group to form a urethane bond or urea bond, which is then incorporated into the polyurethane. Examples of the active hydrogen group include a hydroxyl group, an amino group, an imino group, a carboxyl group, a urethane group, and a urea group. Among these, the hydroxyl group and the amino group are preferred because they provide excellent physical properties to the resulting polyurethane. The reactive silicone preferably has 2.5 or more active hydrogen groups, more preferably 3 or more active hydrogen groups, even more preferably 3.5 or more active hydrogen groups, and even more preferably 4 or more active hydrogen groups.

[0020] The elastic body for blades of the present invention is excellent in the friction-reducing effect derived from the silicone moiety because the reactive silicone is less likely to aggregate.Furthermore, the elastic body for blades of the present invention is excellent in durability because the reactive silicone is fixed in the polyurethane by forming a covalent bond, allowing the friction-reducing effect to be maintained for a long period of time. In the present invention, the amount of reactive silicone added is not particularly limited as long as it does not impair the effects of the present invention, but it is preferable to add, for example, 0.1 to 10% by weight based on the total amount of polyurethane.

[0021] Furthermore, the reactive silicone used in the present invention preferably contains methoxy groups, which can undergo dehydration condensation to form covalent bonds between methoxy groups in the silicone or with hydroxyl groups in the polyurethane, and are therefore expected to further improve durability. The reactive silicone preferably has one or more methoxy groups, more preferably has 1.5 or more methoxy groups, and even more preferably has two or more methoxy groups.

[0022] Hardener As the curing agent, either an alcohol-based curing agent or an amine-based curing agent, or both, can be used. Note that the curing agent is optional and may not be used. Examples of alcohol-based curing agents include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 2-methyl-1,3-propanediol, 2-butyl-2-ethyl-1,3-propanediol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol (2,2-dimethyl-1,3-propanediol), 2-isopropyl-1,4-butanediol, and 3-methyl-2,4-pentanediol. 2,4-pentanediol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 2-methyl-2,4-pentanediol, 2,4-dimethyl-1,5-pentanediol, 2,4-diethyl-1,5-pentanediol, 1,5-hexanediol, 1,6-hexanediol, 2-ethyl-1,3-hexanediol, 2-ethyl-1,6-hexanediol, 1,7-heptanediol, 3,5-heptane Examples include aliphatic dihydric alcohols such as diol, 1,8-octanediol, 2-methyl-1,8-octanediol, 1,9-nonanediol, and 1,10-decanediol; alicyclic dihydric alcohols such as cyclohexanedimethanol (e.g., 1,4-cyclohexanedimethanol), cyclohexanediol (e.g., 1,3-cyclohexanediol, 1,4-cyclohexanediol), and 2-bis(4-hydroxycyclohexyl)-propane; and trihydric or higher polyhydric alcohols such as trimethylolethane, trimethylolpropane, hexitols, pentitols, glycerin, polyglycerin, 1,2,6-hexanetriol, 1,2,4-butanetriol, sorbitol, pentaerythritol, dipentaerythritol tetramethylolpropane, triethanolamine, and triisopropanolamine, and these may be used alone or in combination. Among these, 1,4-butanediol is preferred as the dihydric alcohol, and trimethylolpropane is preferred as the trihydric alcohol.

[0023] Examples of amine-based curing agents include diamines such as ethylenediamine, hexamethylenediamine, diethyltoluenediamine, isophoronediamine, 3,3'-dichloro-4,4'-diaminodiphenylmethane, and 4-chloro-3,5-diaminobenzoic acid isobutyl, and one or more of these can be used.

[0024] ·catalyst Furthermore, a catalyst can be used to accelerate the curing reaction. The catalyst is not particularly limited as long as it accelerates the urethanization of a hydroxyl group and an isocyanate group, or the ureaization of an amino group and an isocyanate group, and examples thereof include trialkylamines such as triethylamine; tetraalkyldiamines such as N,N,N',N'-tetramethyl-1,3-butanediamine; aminoalcohols such as dimethylethanolamine; ethoxylated amines; ethoxylated diamines; ester amines such as bis(diethylethanolamine) adipate; triethylenediamine; cyclohexylamine derivatives such as N,N-dimethylcyclohexylamine; morpholine derivatives such as N-methylmorpholine and N-(2-hydroxypropyl)-dimethylmorpholine; piperazine derivatives such as N,N'-diethyl-2-methylpiperazine and N,N'-bis-(2-hydroxypropyl)-2-methylpiperazine; and amine compounds such as dibutyltin di Dialkyltin compounds such as laurate and dibutyltin di(2-ethylhexoate); organic tin compounds such as stannous 2-ethylcaproate and stannous oleate; organic bismuth compounds such as bismuth 2-ethylhexanoate and bismuth neodecanoate; saturated fatty acid alkali metal salts, which are salts of saturated fatty acids such as formic acid, acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, lauric acid, myristic acid, pentadecylic acid, palmitic acid, margaric acid, and stearic acid with alkali metals such as lithium, sodium, potassium, rubidium, cesium, and francium; and temperature-sensitive catalysts such as diazabicyclononene (DBN), diazabicycloundecene (DBU), and phenolic resin salts thereof, octylate salts, stearates, oleates, formates, and p-toluenesulfonates.

[0025] Other ingredients The resin composition for forming the polyurethane contained in the contact portion may contain additives such as fillers, stabilizers, reactivity-promoting catalysts, softeners, processing aids, mold release agents, antifoaming agents, and flame retardants, as needed.

[0026] In the polyurethane contained in the contact portion of the elastic body for blades of the present invention, the molar ratio of the active hydrogen groups of the polyol, reactive silicone, and curing agent to the isocyanate groups of the polyisocyanate or prepolymer is preferably 0.8 or more and 1.0 or less, more preferably 0.85 or more and 0.98 or less, and even more preferably 0.85 or more and 0.95 or less.

[0027] The method for manufacturing the elastic body for blades of the present invention is not particularly limited, and it can be manufactured by centrifugal molding, the methods disclosed in Japanese Patent Publication Nos. 4018033, 4820161, and 4974490 filed by the present applicant, or the like. The molding method may be any of the one-shot method, the prepolymer method, and the pseudo-prepolymer method.

[0028] In the one-shot method, polyol, polyisocyanate, curing agent, catalyst, etc. are charged all at once and cured to produce a molded product of thermosetting polyurethane urea. In the prepolymer method, a polyol is reacted with a stoichiometrically equivalent or excess amount of polyisocyanate to prepare a prepolymer having an isocyanate group at its terminal, and a predetermined amount of a curing agent, catalyst, etc. is mixed therewith to cure the prepolymer, thereby producing a molded product of thermosetting polyurethane urea. In the pseudo-prepolymer method, a portion of the polyol is mixed in advance with a curing agent, and a prepolymer is prepared from the remaining polyol and polyisocyanate. The prepolymer is then mixed with a mixture of the polyol, curing agent, catalyst, etc., which has been mixed in advance, and cured to produce a molded thermosetting polyurethane urea body.

[0029] The elastic body for blades of the present invention preferably has an International Rubber Hardness (IRHD) of 60 or more and 100 or less at the contact portion. The elastic body for a blade of the present invention preferably has a resilience measured in accordance with JIS K 7312-1996 of 10% or more and 60% or less.

[0030] A blade can be manufactured by attaching the elastic material for a blade of the present invention to a support member made of metal or the like. The use of the blade of the present invention is not particularly limited, and it can be used as a cleaning blade, a developing blade, a conductive blade, a polishing blade, a coating blade, etc. Among these, the elastic material for a blade of the present invention is suitable for use as a cleaning blade because of its excellent durability. [Example]

[0031] "Prepolymer Production Example 1" Polycaprolactone (Daicel Corporation, Placcel 220, hydroxyl value 56.1 mgKOH / g) was used as the polyol. This was dehydrated under reduced pressure at 110°C for 2 hours. 83.5 parts by weight of 4,4'-diphenylmethane diisocyanate (MDI) (Tosoh Corporation, Millionate MT) was added as the polyisocyanate to 100 parts by weight of this polyol, and the mixture was reacted at 80°C for 3 hours in a nitrogen atmosphere to obtain a prepolymer with an NCO% of 13.0.

[0032] "Example 1" 100 parts by weight of the prepolymer was vacuum degassed at 75°C, and 43.9 parts by weight of a similarly degassed polyol (Daicel Corporation, PLACCEL 220) was added. 7.2 parts by weight of a reactive silicone (Shin-Etsu Chemical Co., Ltd., X-48-1903S, hydroxyl value 112 mgKOH / g) having one or more phenyl groups, two or more hydroxyl groups, and one or more methoxy groups was then added. 9.5 parts by weight of a 75:25 (by weight) mixture of 1,4-butanediol and 1,1,1-trimethylolpropane was added as a curing agent. The mixture was stirred with an agitator, poured into a centrifugal molding machine at 150°C, demolded after 1 hour, post-crosslinked at 120°C for 12 hours, and aged at room temperature for 7 days to obtain a 1.9 mm thick sheet.

[0033] "Example 2" A 1.9 mm thick sheet was obtained in the same manner as in Example 1, except that the reactive silicone was a silicone having one or more phenyl groups and two or more amino groups (X-22-9409, manufactured by Shin-Etsu Chemical Co., Ltd., functional group equivalent: 670 g / mol) and the amount of curing agent was as shown in Table 1.

[0034] "Comparative Example 1" A sheet having a thickness of 1.9 mm was obtained in the same manner as in Example 1, except that no reactive silicone was added and the amount of curing agent was as shown in Table 1. "Comparative Example 2" A 1.9 mm thick sheet was obtained in the same manner as in Example 1, except that the reactive silicone was a silicone having two or more hydroxyl groups (DOWSIL (registered trademark) BY 16-201, manufactured by Dow-Toray Industries, Inc., functional group equivalent weight 750 g / mol) and the amount of curing agent was as shown in Table 1.

[0035] [Table 1]

[0036] The sheets obtained in the examples and comparative examples were cut to form elastic bodies for blades, which were then bonded to a metal support made of a steel plate having a thickness of 2.0 mm with a dimer acid-based hot melt adhesive to prepare cleaning blades.

[0037] <Durability evaluation> The cleaning blade was attached to a color printer (DocuPrint C4000d, manufactured by Fujifilm Business Innovation Co., Ltd.) and a paper feed test was conducted at 28°C and 85% RH. Durability was evaluated by the number of sheets passed before image defects due to toner slipping through caused by damage to the blade edge occurred. Specifically, when the blade edge is damaged, toner slips through the damaged area, causing the toner to adhere to the charging roller and stain it. The areas of the charging roller where toner has adhered are not charged, resulting in white spots in the image. The results are shown in Table 2. [Table 2]

[0038] Image defects due to blade damage occurred after 10,000 sheets of the blade elastomer obtained in Comparative Example 1, which did not contain reactive silicone, and after 50,000 sheets of the blade elastomer obtained in Comparative Example 2, which contained reactive silicone without a phenyl group. In contrast, the elastic body for a blade according to the present invention obtained in the example of the present invention was able to print over 200,000 sheets without any image defects. [Explanation of symbols]

[0039] 1. Blade elastic body 11 Contact part 12 Back section

Claims

1. the contact portion contains polyurethane containing reactive silicone, The elastic body for blades is characterized in that the reactive silicone has a phenyl group, a methoxy group, and two or more active hydrogen groups.

2. 2. The elastic body for a blade according to claim 1, wherein the back surface portion contains a polymer compound having a different composition from that of the contact portion.

3. 3. A cleaning blade, comprising: the elastic body for a blade according to claim 1 or 2 attached to a support member.

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