JP2014066859A - Charging member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a charging member capable of enhancing chargeability for charging a target to be charged, having high durability of the surface against powder contamination and having good resistance against sagging.SOLUTION: A charging member R to be assembled in an electrophotographic image forming apparatus has a surface layer 1. The surface layer 1 contains a surface-modified polymer in a matrix polymer, the surface-modified polymer comprising a polymer having an amino group and a silicone group in the molecule. The surface-modified polymer can include a first polymerization unit based on a first compound having an amino group in the molecule and a second polymerization unit based on a second compound having a silicone group in the molecule. The first compound and the second compound preferably include a (meth)acryl group in the respective molecules.

Description

  The present invention relates to a charging member.

  Conventionally, a charging member has been used to charge an object to be charged. For example, image forming apparatuses such as electrophotographic copying machines, printers, and facsimiles using charged images form latent images by exposing image data to a charged latent image carrier, development, transfer to a transfer medium, fixing, etc. Image formation is performed through the above steps. In the latent image forming step, a roll-shaped charging member is widely used to charge a latent image carrier such as a photoconductor. The charging member is pressed against the latent image carrier, and a voltage is applied to the charging member in a state where a contact portion (so-called nip portion) is formed between them. Thereby, discharge occurs in the gap portion around the contact portion, and the surface of the latent image carrier can be charged.

  The charging member is formed, for example, by impregnating a surface treatment liquid containing an isocyanate compound and a coupling agent that reacts with the isocyanate compound into a surface layer portion of an elastic layer made of conductive silicone rubber in Patent Document 1. A charging roll having a surface treatment layer is disclosed.

JP 2009-138190 A

However, conventionally known charging members have the following problems.
In recent years, downsizing of devices such as image forming apparatuses in which charging members are incorporated has been progressing. As one measure for downsizing the apparatus, downsizing of a power source for applying a voltage to the charging member has been studied. However, when the power source is reduced in size, the upper limit of the voltage that can be applied to the charging member is lowered, so that it is difficult to ensure sufficient discharge in the gap portion around the contact portion. Therefore, it is difficult to sufficiently charge a charged body such as a latent image carrier using a conventional charging member as it is.

  Further, the charging member is often used in the presence of powder, such as toner or toner external additive. These powders tend to adhere to the surface of the charging member as dirt. The attached portion causes a reduction in charging ability of the portion. Therefore, it is desirable that the charging member has durability against powder contamination.

  Further, the charging member is used in a state in which it is in contact with a charged body such as a photoconductor for a long time. For this reason, when the charging member has poor settling resistance, dent marks due to contact with the member to be charged tend to remain on the surface of the charging member. This dent mark causes a reduction in the charging ability of the portion. Therefore, it is desired that the charging member has a good anti-sag property.

  The present invention has been made in view of the above-mentioned background, and can increase the charging ability for charging a member to be charged, has high durability against powder stains on the surface, and has excellent anti-sag properties. It was obtained by trying to provide.

One aspect of the present invention is a charging member used to charge an object to be charged,
In the charging member, the matrix polymer has a surface layer containing a surface-modified polymer composed of a polymer having an amino group and a silicone group in the molecule.

  The surface layer of the charging member contains a surface-modified polymer composed of a polymer having an amino group and a silicone group in the molecule in the matrix polymer. Therefore, the charging member can charge the object to be charged not only by normal charging by discharge in the gap around the contact part with the object to be charged but also by friction at the contact part. Therefore, the charging member can raise the charging ability for charging the object to be charged accordingly. Further, since the charging due to friction is not charging due to a discharge phenomenon, the charging member is not easily affected by the level of applied voltage due to downsizing of the power source or the like. For this reason, the charging member tends to exhibit a high charging capability as compared with the conventional charging member. Further, since the charging member has the surface layer, powders such as toner and toner external additives are difficult to adhere as dirt, and have high durability against powder dirt. Moreover, since the said surface layer has favorable sag resistance, the said charging member can exhibit favorable sag resistance. Therefore, the charging member is unlikely to have a dent mark due to contact with the member to be charged on the surface, and it is easy to suppress a decrease in charging ability due to this.

  As described above, according to the present invention, it is possible to provide a charging member capable of raising the charging ability for charging a member to be charged, having high durability against powder stains on the surface, and having good sag resistance.

It is the figure which showed typically the charging member of the Example. It is the figure which showed the II-II cross section in FIG.

  The charging member can be suitably used in a state in which the surface of the member, which is the surface of the member, is pressed against the surface of the member to be charged and a contact portion is formed between the two. The charging member can be suitably used in the presence of powder such as toner or toner external additive. This is because in these cases, the above-described effects can be sufficiently exhibited.

  Specific examples of the object to be charged include a latent image carrier in an electrophotographic image forming apparatus that uses a charged image (claim 8). In this case, it is advantageous to form a good image over a long period of time. Specific examples of the electrophotographic image forming apparatus include an electrophotographic copying machine using a charged image, a printer, a facsimile, a multifunction peripheral, a POD (Print On Demand) apparatus, and the like.

  Here, the charging member has a surface layer containing a surface-modified polymer composed of a polymer having an amino group and a silicone group in the molecule in the matrix polymer.

  The matrix polymer plays an important role as a polymer component that forms the basic skeleton of the surface layer. The matrix polymer is not particularly limited as long as it can play the above role, and various resins or rubbers can be used. These can be used alone or in combination of two or more, and an optimum material can be selected in consideration of flexibility, wear resistance and the like.

  Examples of the resin include various thermoplastic resins and mixed polymers of thermoplastic resins and thermosetting resins. Specific examples of the resin include polyamide resins such as N-methoxymethylated nylon, urethane resins, urethane silicone resins, urethane fluororesins, polyimide resins, (meth) acrylic resins, (meth) acrylic silicone resins, Fluorine resin, acetal resin, alkyd resin, polyester resin, polyether resin, carbonate resin, phenol resin, epoxy resin, polyvinyl alcohol, polyvinyl pyrrolidone, carboxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose and other cellulosic resins, polyacrylamide, polyethylene Oxide, polyethylene glycol, polypropylene glycol, polyvinyl methyl ether, polyamine, polyethyleneimine, casein, gelatin, starch And copolymers thereof, olefin resins such as polyethylene, polypropylene and copolymers with other olefin monomers, vinyl chloride resins, styrene resins such as polystyrene and acrylonitrile-styrene copolymer resins, vinyl chloride Polyvinyl acetal resins such as vinyl acetate copolymer resins and polyvinyl butyral resins, and derivatives or modified products thereof, polyisobutylene, polytetrahydrofuran, polyaniline, acrylonitrile-butadiene-styrene copolymer (ABS resin), polyisoprene, polybutadiene, etc. Polydienes, polysiloxanes such as polydimethylsiloxane, polysulfones, polyimines, polyacetic anhydrides, polyureas, polysulfides, polyphosphazenes, polyketones, polyphenylenes, Halo olefins, and the like can be exemplified derivatives thereof, a melamine resin. Specific examples of the rubber (including elastomer) include acrylonitrile-butadiene rubber (NBR), butadiene rubber (BR), styrene-butadiene rubber (SBR), butyl rubber (IIR), and chloroprene rubber (CR). And hydrin rubber (ECO, CO), isoprene rubber (IR), urethane rubber (U), silicone rubber (Q), ethylene-propylene-diene rubber (EPDM), natural rubber (NR), polyurethane elastomer and the like. . Of these, polyamide resins, urethane resins, polyurethane elastomers, urethane silicone resins, and the like can be preferably used from the viewpoint of suppressing damage to the charged body by improving the flexibility of the surface layer.

  On the other hand, the surface-modified polymer contained in the matrix polymer plays an important role as a component for modifying the surface of the surface layer and exhibiting the above-described effects. The surface-modified polymer may include a first polymer unit based on a first compound having an amino group in the molecule and a second polymer unit based on a second compound having a silicone group in the molecule (claims). 2). Specifically, the surface-modified polymer can be composed of a copolymer containing the first polymer unit and the second polymer unit, preferably a block copolymer.

  In this case, an amino group can be introduced into the molecule of the surface modified polymer by the first polymerized unit, and a silicone group can be introduced by the second polymerized unit. Therefore, it becomes easy to adjust the amount of amino groups and silicone groups in the surface-modified polymer by changing the proportion of each polymerized unit. Therefore, in this case, there is an advantage that it is easy to balance the increase in charging ability, the improvement in durability against powder dirt, and the anti-sag property.

  The surface-modified polymer can include one or more different first polymerized units, one or two or more different second polymerized units. The first compound may be any of a monomer, an oligomer, and a polymer as long as it is an organic compound. From the viewpoint of good reactivity during polymerization, a monomer or oligomer is preferable, and a monomer is particularly preferable. As long as the said 2nd compound is an organic compound, any of a monomer, an oligomer, and a polymer may be sufficient. From the viewpoint of good reactivity during polymerization, a monomer or oligomer is preferable, and an oligomer is particularly preferable.

  Moreover, the said 1st compound and 2nd compound can contain an unsaturated bond in a molecule | numerator (Claim 3). In this case, there is an advantage that a copolymerization reaction is easily performed when the surface-modified polymer is produced. As said unsaturated bond, what is contained in a (meth) acryl group, an allyl group, a vinyl group etc. can be used, for example.

  Moreover, the said 1st compound and the 2nd compound can be made into the structure (A) which further has a (meth) acryl group in a molecule | numerator specifically, (Claim 4). In this case, there is an advantage that a copolymerization reaction is easily performed when the surface-modified polymer is produced. In the present application, “(meth) acryl” means both acrylic and methacrylic.

  In addition to the configuration (A) described above, the first compound further has a (meth) acryl group in the molecule, and the second compound further has an azo group in the molecule ( B). Also in this case, there is an advantage that a copolymerization reaction is easily performed when the surface-modified polymer is produced.

  As said 1st compound, the (meth) acryl monomer which has an amino group in a molecule | numerator, the (meth) acrylamide monomer which has an amino group in a molecule | numerator etc. can be illustrated, for example.

  Specific examples of the first compound include dimethylaminopropyl (meth) acrylamide, dimethylaminomethyl (meth) acrylamide, dimethylaminoethyl (meth) acrylamide, dimethylaminobutyl (meth) acrylamide, dimethylaminohexyl ( (Meth) acrylamide, dimethylaminoheptyl (meth) acrylamide, dimethylaminooctyl (meth) acrylamide, diethylaminopropyl (meth) acrylamide, diphenylaminopropyl (meth) acrylamide, aminopropyldimethyl (meth) acrylamide, hydroxyaminopropyldimethyl (meth) Acrylamide, diaminomethyl (meth) acrylamide, triaminopropyl (meth) acrylamide, diethyl (meth) acrylamide (Meth) acrylamide, and the like can be exemplified isopropyl (meth) acrylamide.

  Specific examples of the first compound include compounds represented by the following formula 1.

However, in Formula 1, R ¹ represents a hydrogen atom or a methyl group. R ² represents an aliphatic hydrocarbon group having 1 to 7 carbon atoms or an aromatic hydrocarbon group. R ³ and R ⁴ represent an aliphatic hydrocarbon group having 1 to 20 carbon atoms, a phenyl group, a hydrogen atom or a hydroxyl group.

  Examples of the second compound include a silicone compound having a (meth) acryl group in the molecule and a silicone compound having an azo group in the molecule.

  As the silicone compound having a (meth) acryl group in the molecule, specifically, a (meth) acryl-modified silicone compound is preferable from the viewpoints of reactivity, improvement in durability against powder stains, and resistance to settling. It can be illustrated as a thing. Particularly preferably, it can be a silicone compound (silicone oil or the like) represented by the following formula 2.

However, in the formula 2, ^{R 1} represents an alkyl group having 1 to 10 carbon atoms. Preferably it represents a methyl group. R ² and R ³ each represent an alkyl group having 1 to 10 carbon atoms, preferably a methyl group. X represents a (meth) acryl group. n is preferably from 1 to 135 (number average molecular weight of about 170 to 10,000), more preferably from 10 to 50 (number average molecular weight of from about 1000 to 4000), from the viewpoint of improving durability against powder stains and resistance to settling. Represents a positive number.

  Further, as the silicone compound having an azo group in the molecule, specifically, from the viewpoint of good reactivity at the time of polymerization, improvement of durability against powder dirt, resistance to dripping, etc., the following formula 3 It can be set as the silicone compound represented.

However, in Formula 3, X ¹ and X ² represent units based on compounds containing the same or different siloxane bonds.

  The surface-modified polymer may contain 1 to 98 mol% of the first polymer unit based on the first compound and 0.1 to 10 mol% of the second polymer unit based on the second compound. In this case, the above effect can be ensured. Further, by adjusting the proportion of each polymerized unit of the surface-modified polymer within the above range, it is possible to control the balance between the increase in charging ability, the improvement in durability against powder stains, and the anti-sag property. In addition, the ratio of the said 1st polymerization unit and a 2nd polymerization unit is a total ratio including the polymerization unit, when there exists a polymerization unit based on the 1st polymerization unit, a 2nd polymerization unit, and the other compound mentioned later further. Can be selected to be 100 mol%. However, the polymerization initiator is excluded.

  The ratio of the first polymerization unit is preferably 1.2 mol% or more, more preferably 1.4 mol% or more, and further preferably 1.6 mol% or more, from the viewpoint of sufficiently obtaining the effect of raising the charging ability. it can. In addition, the ratio of the first polymerization unit is preferably 97.5 mol% or less, more preferably 97 mol% or less, and still more preferably, from the standpoint of improving durability against powder dirt and facilitating securing of sag resistance. It can be 96.5 mol% or less. On the other hand, the ratio of the second polymerization unit is preferably 0.13 mol% or more, more preferably 0.15 mol% or more, from the viewpoint of improving durability against powder dirt and facilitating securing of sag resistance. Preferably it can be 0.18 mol% or more. The proportion of the second polymer unit is preferably 8 mol% or less, more preferably 7 mol% or less, and even more preferably 6 mol% or less from the viewpoint of reaction controllability. The ratio of the above polymerized units can be measured by pyrolysis GC / MS analysis, NMR analysis or the like.

  In addition to the first polymer unit and the second polymer unit, the surface-modified polymer may contain one or more polymer units based on other compounds as a polymerization component.

  In addition, as long as the said other compound is an organic compound, any of a monomer, an oligomer, and a polymer may be sufficient. From the viewpoint of good reactivity during polymerization, a monomer or oligomer is preferable, and a monomer is particularly preferable.

  As said other compound, the monomer etc. which have a fluorine-containing group in a molecule | numerator etc. can be illustrated, for example. Preferably, from the viewpoint of polymerization reactivity and the like, it may further have a (meth) acryl group in the molecule. The above “fluorine-containing group” refers to a group containing fluorine atom (including —F). When this is used, it becomes possible to further have a fluorine-containing group as a functional group other than an amino group and a silicone group in the molecule of the surface-modified polymer. Therefore, the releasability of powder such as toner on the surface of the surface layer can be improved.

  Specific examples of the fluorine-containing group include a fluoroalkyl group, a fluoroalkylalkylene oxide group, a fluoroalkenyl group, and a fluorine group (—F). These can be used alone or in combination of two or more. Among these, as the fluorine-containing group, a fluoroalkyl group (preferably having about 4 to 12 carbon atoms) can be suitably used. This is because there are advantages such as easy introduction into the monomer molecule. In the fluoroalkyl group, all hydrogen atoms of the alkyl group may be fluorinated (fully fluorinated) or may include a part that is not fluorinated (partially fluorinated). Particularly preferably, the fluoroalkyl group is a perfluoroalkyl group. This is because there is an advantage that the amount of fluorine atoms in the polymer can be increased, and the releasability of powder such as toner can be easily improved.

  Specific examples of the monomer having a fluorine-containing group in the molecule include 2,2,2-trifluoroethyl (meth) acrylate and 2,2,3,3,3-pentafluoropropyl (meth). Acrylate, 2- (perfluorobutyl) ethyl (meth) acrylate, 2- (perfluorohexyl) ethyl (meth) acrylate, 2- (perfluorooctyl) ethyl (meth) acrylate, 2- (perfluorodecyl) ethyl ( (Meth) acrylate, 2- (perfluoro-3-methylbutyl) ethyl (meth) acrylate, 2- (perfluoro-5-methylhexyl) ethyl (meth) acrylate, 2- (perfluoro-7-methyloctyl) ethyl ( (Meth) acrylate, 1H, 1H, 3H-tetrafluoropropyl (meth) acrylate 1H, 1H, 5H-octafluoropentyl (meth) acrylate, 1H, 1H, 7H-dodecafluoroheptyl (meth) acrylate, 1H, 1H, 9H-hexadecafluorononyl (meth) acrylate, 1H-1- (trif Oromethyl) trifluoroethyl (meth) acrylate, 1H, 1H, 3H-hexafluorobutyl (meth) acrylate, 3-perfluorobutyl-2-hydroxypropyl (meth) acrylate, 3-perfluorohexyl-2-hydroxypropyl (Meth) acrylate, 3-perfluorooctyl-2-hydroxypropyl (meth) acrylate, 3- (perfluoro-3-methylbutyl) -2-hydroxypropyl (meth) acrylate, 3- (perfluoro-5-methylhexyl) ) -2-Hydro Shipuropiru (meth) acrylate, 3- (such as perfluoro-7-methyl-octyl) -2-hydroxypropyl (meth) acrylate can be exemplified.

  Other examples of the other compound include, for example, a compound having at least one of a (meth) acryl group or a vinyl group, methyl (meth) acrylate, ethyl (meth) acrylate, (meth) acrylic acid A butyl etc. can be illustrated. When these are used, there are advantages such as easy control of the molecular weight of the surface-modified polymer.

  Other examples of the above compound include ethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, trimethylolpropane tri (Meth) acrylate, ditrimethylolpropane tetra (meth) acrylate, glycerol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, alkoxytitanium tri (meth) acrylate, 1,6-hexanediol di (meth) acrylate, 2 -Methyl-1,8-octanediol di (meth) acrylate, 1,9-nonanediol di (meth) acrylate, 1,10-decanediol di (meth) acrylate, tricyclodecane dimethyl Nord di (meth) acrylate, dioxane glycol di (meth) acrylate, 2-hydroxy-1-acryloyloxy-3-methacryloyloxypropane, 2-hydroxy-1,3-di (meth) acryloyloxypropane, 9,9-bis [4- (2- (meth) acryloyloxyethoxy) phenyl] fluorene, undecylenoxyethylene glycol di (meth) acrylate, bis [4- (meth) acryloylthiophenyl] sulfide, bis [2- (meth) acryloyl Examples thereof include thioethyl] sulfide, 1,3-adamantanediol di (meth) acrylate, 1,3-adamantane dimethanol di (meth) acrylate, and the like. When these are used, it becomes easy to make a branched polymer structure. Therefore, there are advantages such that the surface-modified polymer is likely to be unevenly distributed on the surface of the surface layer, and the surface-modifying effect is likely to increase.

  The surface-modified polymer may contain all or part of the polymerization initiator. Examples of the polymerization initiator include a polymer having an azo group such as dimethyl 1,1'-azobis (1-cyclohexanecarboxylate).

  The polymer structure of the surface modified polymer is not particularly limited. The surface-modified polymer can have, for example, a linear or branched polymer structure. The surface-modified polymer preferably has a highly branched structure (claim 7).

  In this case, as compared with the case where the polymer structure is linear, it is advantageous for further raising the charging ability, improving the durability against powder stains, and exhibiting the settling resistance. This is because the highly branched structure of the surface-modified polymer allows amino groups and silicone groups to be effectively present on the surface of the surface layer, thereby increasing the above-described surface layer surface modification effect. The “highly branched structure” is a polymer structure in which a number of branches are positively introduced into the molecular structure, unlike a linear (linear or string-like) polymer structure. This is called a hyper-branch structure.

  The surface layer may contain 0.5 to 20 parts by mass of the surface-modified polymer with respect to 100 parts by mass of the matrix polymer. In this case, the above-described operational effects can be ensured.

  The content of the surface-modified polymer is preferably 0.75 parts by mass or more, more preferably 1 part by mass or more from the viewpoint of obtaining a sufficient effect by addition. In addition, the content of the surface-modified polymer is preferably 15 parts by mass or less, more preferably 10 parts by mass or less, and still more preferably, from the viewpoints of compatibility with the matrix polymer, suppression of bleeding from the matrix polymer, cost, and the like. It can be 8 parts by mass or less. The content of the surface-modified polymer is determined by extracting the extract with a solvent, pyrolyzing GC / MS analysis and NMR analysis of the extract, and specifying the structure of the surface-modified polymer. It can be measured by MS analysis or the like.

The surface layer may further contain a conductive agent in the matrix polymer. Specific examples of the conductive agent include carbon-based conductive materials such as carbon black, carbon nanotube, and graphite, barium titanate, c-TiO ₂ , c-ZnO, and c-SnO ₂ (where c- is conductive). Exemplifying electronic conductive agents such as conductive metal oxides or metal nanoparticles, ionic conductive agents such as quaternary ammonium salts, borates, perchlorates, ionic liquids, etc. Can do.

  The surface layer may contain various additives such as a reaction catalyst, a filler, a coupling agent, a dispersant, a leveling agent, a crosslinking agent, and a crosslinking aid in the matrix polymer as necessary. Can do. These can be used alone or in combination of two or more.

The volume resistivity of the surface layer is preferably about 1 × 10 ⁴ to 1 × 10 ¹¹ Ω · cm, more preferably 1 × 10 ⁵ to 1 from the viewpoint of improving charging ability and suppressing charging variation. It can be set to about × 10 ¹⁰ Ω · cm. The thickness of the surface layer is preferably about 1 to 100 μm, more preferably about 1 to 30 μm, and still more preferably about 3 to 15 μm, from the viewpoint of suppressing damage to the surface of the charging member and suppressing damage to the charged body. be able to.

  In the charging member, the configuration below the surface layer is not particularly limited. However, considering the ease of application to an image forming apparatus, the charging member is preferably configured in a roll shape. In this case, specifically, the charging member includes, for example, a shaft body, an elastic layer made of a conductive rubber elastic body formed along the outer peripheral surface of the shaft body, and the outer peripheral surface of the elastic layer. And the surface layer formed as described above. In addition, an elastic layer can be comprised from 1 layer or 2 layers or more.

  Specifically, as the shaft body, for example, a solid body (core metal) made of a metal (including an alloy) such as stainless steel, aluminum, or iron, a hollow body, a solid body made of conductive or non-conductive plastic, Examples thereof include a hollow body, a solid body made of conductive or non-conductive plastic, and a metal body plated with a hollow body.

  Examples of the rubber material constituting the elastic layer include hydrin rubber (ECO, CO), isoprene rubber (IR), butadiene rubber (BR), styrene-butadiene rubber (SBR), acrylonitrile-butadiene rubber (NBR), ethylene- Examples include propylene-diene rubber (EPDM), urethane rubber (U), and silicone rubber (Q).

  For the rubber material, the above-mentioned conductive agent, lubricant, filler, extender, reinforcing material, processing aid, curing agent, vulcanization accelerator, cross-linking agent, cross-linking aid, antioxidant, plasticizer, UV absorption Various additives such as additives, pigments, silicone oils, auxiliaries, and surfactants can be added as appropriate.

The volume resistivity of the elastic layer is preferably about 1 × 10 ² to 1 × 10 ¹⁰ Ω · cm, more preferably 1 × 10 ³ from the viewpoints of improving charging ability and suppressing material destruction due to energization. It can be set to about ˜1 × 10 ⁹ Ω · cm. Further, the thickness of the elastic layer is preferably about 0.2 to 20 mm, more preferably about 0.5 to 10 mm, from the viewpoint of improving recovery from deformation due to contact with the object to be charged and suppressing material destruction due to energization. Preferably, it can be about 1 to 5 mm.

The charging member according to the embodiment will be specifically described with reference to the drawings.
As shown in FIGS. 1 and 2, the charging member R according to the embodiment is incorporated in an electrophotographic image forming apparatus. The charging member R has a surface layer 1. Specifically, the charging member R of this example further includes a conductive shaft body 2 and an elastic layer 3 made of a conductive rubber elastic body formed along the outer peripheral surface of the shaft body 2. doing. However, both end portions of the shaft body 2 are projected from both end surfaces of the elastic layer 3. A surface layer 1 is formed along the outer peripheral surface of the elastic layer 3.

  The surface layer 1 contains a surface-modified polymer composed of a polymer having an amino group and a silicone group in the molecule in the matrix polymer.

  Specifically, the surface-modified polymer has a first polymer unit based on a monomer (first compound) having an amino group and a (meth) acryl group in the molecule, a silicone group and a (meth) acryl group in the molecule. It consists of a copolymer containing the 2nd polymerization unit based on the compound (2nd compound) which has. The first polymer unit in the surface-modified polymer is in the range of 1 to 98 mol%, and the second polymer unit is in the range of 0.1 to 10 mol%. The surface-modified polymer is contained in the range of 0.5 to 20 parts by mass with respect to 100 parts by mass of the matrix polymer. The surface-modified polymer has a linear or highly branched structure (hyperbranched structure). Note that a conductive agent is added to the surface layer 1 in order to impart conductivity.

Hereinafter, a charging roll sample as a charging member according to the example and a charging roll sample of a comparative example were prepared and evaluated. An experimental example will be described.
(Experimental example)
<Preparation of surface modified polymer>
Each surface-modified polymer to be contained in the surface layer matrix polymer was prepared as follows.
・ Surface modified polymer A
In a 200 mL reaction flask, 15 g (96 mmol) of dimethylaminopropylacrylamide (manufactured by Kojin Co., Ltd.) and a (meth) acrylate-modified silicone compound (manufactured by Shin-Etsu Chemical Co., Ltd., “X-22-174DX”) 92 g (0.2 mmol), 0.38 g (3.8 mmol) of methyl methacrylate (manufactured by Junsei Chemical Industry Co., Ltd.), dimethyl 1,1′-azobis (1-cyclohexanecarboxylate) (Wako Pure Chemical Industries, Ltd.) Co., Ltd., “VE-73”) 1.24 g (4 mmol) and methyl ethyl ketone (MEK) 26.9 g were charged and bubbled with nitrogen for 5 minutes with stirring. Polymerized for 7 hours.
Next, 51.8 g of MEK was charged to obtain a solution containing the surface-modified polymer A having a solid content of 30%. The surface-modified polymer A is based on a first polymer unit based on a (meth) acrylamide monomer (first compound) having an amino group in the molecule and a (meth) acrylate-modified silicone compound (second compound) in the molecule. It is a linear copolymer containing a 2nd polymerization unit.

・ Surface modified polymer B
In the synthesis of the surface-modified polymer A, 10.55 g (67.6 mmol) of dimethylaminopropylacrylamide, 7.46 g (1.6 mmol) of (meth) acrylate-modified silicone compound, 3.09 g (30.8 mmol) of methyl methacrylate A solution containing the surface-modified polymer B having a solid content of 30% was obtained in the same manner. The surface-modified polymer B is based on a first polymer unit based on a (meth) acrylamide monomer (first compound) having an amino group in the molecule and a (meth) acrylate-modified silicone compound (second compound) in the molecule. It is a linear copolymer containing a 2nd polymerization unit.

・ Surface modified polymer C
In the synthesis of the surface modified polymer A, 0.28 g (1.8 mmol) of dimethylaminopropylacrylamide, 22.59 g (4.9 mmol) of (meth) acrylate-modified silicone compound, 9.34 g (93.3 mmol) of methyl methacrylate. A solution containing the surface-modified polymer C having a solid content of 30% was obtained in the same manner except that. The surface-modified polymer C is based on a first polymer unit based on a (meth) acrylamide monomer (first compound) having an amino group in the molecule and a (meth) acrylate-modified silicone compound (second compound) in the molecule. It is a linear copolymer containing a 2nd polymerization unit.

・ Surface modified polymer D
In the synthesis of the surface-modified polymer A, 15.02 g (96.2 mmol) of dimethylaminopropylacrylamide, 0.88 g (0.2 mmol) of a (meth) acrylate-modified silicone compound, 0.34 g (3.4 mmol) of methyl methacrylate In addition, except that 0.08 g (0.2 mmol) of 2- (perfluorohexyl) ethyl acrylate (manufactured by Daikin Industries, Ltd., “R-1620”) was added, A solution containing 30% surface modified polymer D was obtained. The surface-modified polymer D is based on a first polymer unit based on a (meth) acrylamide monomer (first compound) having an amino group in the molecule and a (meth) acrylate-modified silicone compound (second compound) in the molecule. It is a linear copolymer including a second polymer unit and a polymer unit based on a monomer having a fluoroalkyl group in the molecule.

・ Surface modified polymer E
A 300 mL reaction flask was charged with 87 g of toluene, and nitrogen was poured for 5 minutes while stirring, and the flask was heated until the internal liquid was refluxed (approximately 110 ° C.).
On the other hand, in another 200 mL reaction flask, 12 g (76.79 mmol) of the dimethylaminopropylacrylamide, 0.74 g (0.21 mmol) of the (meth) acrylate-modified silicone compound, and ethylene glycol dimethacrylate (Shin Nakamura Chemical Co., Ltd.). Ltd., “1G”) 3.96 g (20 mmol), 0.31 g (3 mmol) of the above methyl methacrylate, 6.21 g (20 mmol) of the above dimethyl 1,1′-azobis (1-cyclohexanecarboxylate), Then, 87 g of toluene was charged, and nitrogen was introduced for 5 minutes while stirring to perform nitrogen substitution, followed by cooling to 0 ° C. in an ice bath.
Next, the contents in the 200 mL reaction flask were added dropwise to the refluxed toluene in the 300 mL reaction flask using a dropping pump over 30 minutes. After completion of the dropwise addition, the mixture was aged for 1 hour.
Next, this reaction solution was added to 555 g of hexane / toluene (mass ratio 4: 1) to precipitate the polymer in a slurry state.
The slurry was then filtered under reduced pressure, redissolved using 42 g of tetrahydrofuran (THF), and a THF solution of this polymer was added to 555 g of hexane to reprecipitate the polymer in a slurry state.
Next, this slurry was filtered under reduced pressure and vacuum-dried to obtain 13.6 g of a surface-modified polymer E which was the target product of white powder.
The surface-modified polymer E is based on a first polymer unit based on a (meth) acrylamide monomer (first compound) having an amino group in the molecule and a (meth) acrylate-modified silicone compound (second compound) in the molecule. It is a copolymer having a hyperbranched structure (hyperbranched structure) containing a second polymer unit.

・ Surface modified polymer F
In a 200 mL reaction flask, 23 g (5 mmol) of the above (meth) acrylate-modified silicone compound, 9.5 g (95 mmol) of the above methyl methacrylate, and 1.24 g of the above dimethyl 1,1′-azobis (1-cyclohexanecarboxylate). (4 mmol) and 26.9 g of MEK were charged, and bubbling with nitrogen was performed for 5 minutes while stirring, and then polymerization was performed at an internal liquid temperature of 80 ° C. for 7 hours.
Next, 51.8 g of MEK was charged to obtain a solution containing the surface-modified polymer F having a solid content of 30%. The surface-modified polymer F is a linear copolymer containing a second polymerization unit based on a (meth) acrylate-modified silicone compound (second compound) in the molecule, and has an amino group in the molecule (meta ) No first polymerized units based on acrylamide monomer (first compound).

・ Surface modified polymer G
In a 200 mL reaction flask, 13.99 g (89.6 mmol) of the dimethylaminopropyl acrylamide, 0.23 g (0.5 mmol) of the 2- (perfluorohexyl) ethyl acrylate, and 0.99 g of the methyl methacrylate (9 0.9 mmol), 1.24 g (4 mmol) of dimethyl 1,1′-azobis (1-cyclohexanecarboxylate) and 26.9 g of MEK, and bubbling with nitrogen for 5 minutes while stirring, For 7 hours at a temperature of 80 ° C.
Next, this reaction solution was added to 662 g of hexane to precipitate a polymer, the supernatant was decanted, and the residue was redissolved in 54 g of THF.
Next, a THF solution of this polymer was added to 662 g of hexane to precipitate the polymer in a slurry state.
Next, this slurry was filtered under reduced pressure and vacuum-dried to obtain 12.1 g of a surface-modified polymer G which was a target product of white powder. The surface-modified polymer G is a linear copolymer containing a first polymer unit based on a (meth) acrylamide monomer (first compound) having an amino group in the molecule, and (meth) acrylate in the molecule. It does not contain the second polymer unit based on the modified silicone compound (second compound).

・ Surface modified polymer H
In a 100 mL reaction flask, 12.97 g (30 mmol) of 2- (perfluorohexyl) ethyl acrylate, 7 g (70 mmol) of methyl methacrylate, and dimethyl 1,1′-azobis (1-cyclohexanecarboxylate) 1 .24 g (4 mmol) and 26.9 g of MEK were charged and bubbled with nitrogen for 5 minutes while stirring, and then polymerized at an internal liquid temperature of 80 ° C. for 7 hours.
Next, this reaction solution was added to 662 g of hexane to precipitate a polymer, the supernatant was decanted, and the residue was redissolved in 54 g of THF.
Next, a THF solution of this polymer was added to 662 g of hexane to precipitate the polymer in a slurry state.
Subsequently, this slurry was filtered under reduced pressure and vacuum-dried to obtain 6.0 g of a surface-modified polymer H which is a target product of white powder. The surface-modified polymer H is a linear copolymer containing a polymer unit based on a monomer having a fluoroalkyl group in the molecule, and a (meth) acrylamide monomer having an amino group in the molecule (first compound) Neither the 1st polymerization unit based on (2) nor the 2nd polymerization unit based on a (meth) acrylate modified silicone compound (2nd compound) is contained in the molecule | numerator.

Table 1 shows a list of the surface-modified polymer blends.

<Preparation of surface layer forming material>
As shown in Table 2 below, 100 parts by mass of N-methoxymethylated nylon (manufactured by Nagase ChemteX Corp., “Tresin EF30T”) and trimethylol melamine (crosslinking agent) (manufactured by Sumitomo Chemical Co., Ltd., “ Sumikaflex M3 ") 30 parts by mass, electronic conductive agent (carbon black) (Ketjen Black International Co., Ltd.," Ketjen Black EC ") 15 parts by mass, and the prescribed types and prescribed amounts shown in Table 2 Each surface-modified polymer was blended, and this was added to 500 parts by mass of a methanol-toluene mixed solution (methanol: toluene = 7: 3) and mixed and stirred. Thereby, each surface layer forming material used for preparation of the charging roll samples 1-11 was prepared.

<Preparation of charging roll sample>
Epichlorohydrin-ethylene oxide-allyl glycidyl ether copolymer (manufactured by Nippon Zeon Co., Ltd., “HYDRIN T3106”), 1 part by mass of trioctadecyl ammonium perchlorate, and zinc oxide (Mitsui Metal Mining Co., Ltd.) 5 1 part by mass of stearic acid (manufactured by Kao Corporation, “Lunac S-30”) and 0.5 part by mass of a vulcanization accelerator (manufactured by Ouchi Shinsei Chemical Co., Ltd., “Noxeller DM”) 1 part by weight of sulfur (manufactured by Tsurumi Chemical Co., Ltd., “Sulfax PTC”), 0.5 part by weight of a vulcanization accelerator (manufactured by Ouchi Shinsei Chemical Co., Ltd., “Noxeller TT”), A material for forming an elastic layer was prepared by blending 0.5 part by mass of a vulcanization accelerator (manufactured by Ouchi Shinsei Chemical Co., Ltd., “Noxeller TRA”) and kneading using a roll.

  A solid cylindrical iron bar with a diameter of 6 mm was prepared as a shaft, and an adhesive was applied to the outer peripheral surface. After this shaft body was set in the hollow space of the roll molding die, the prepared elastic layer forming material was poured into the hollow space, vulcanized at 170 ° C. for 50 minutes, and demolded. Thereby, a roll-shaped elastic layer (thickness 1.75 mm) was formed along the outer peripheral surface of the shaft body.

  Next, each of the prepared surface layer forming materials was applied to the outer peripheral surface of the elastic layer by a dip coating method, and then heat treated at 150 ° C. for 50 minutes to form a surface layer (thickness 15 μm). Thereby, it has a surface layer along the outer peripheral surface of the elastic layer, and the surface layer includes the charge roll samples 1 to 11 having a two-layer structure containing each surface-modified polymer shown in Table 2 in the matrix polymer. Produced.

<Evaluation>
−Charging capacity−
A state in which the prepared charge roll sample is incorporated in a cartridge of a color laser printer (manufactured by Ricoh Co., Ltd., “IPSIO SP C310”), and the photosensitive member and the charge roll sample are brought into contact with each other in a 23 ° C. × 53% RH environment. Then, a DC-1200 V voltage was applied to the charging roll sample while rotating the photoconductor and the charging roll sample at 60 rpm. A probe of a surface electrometer (manufactured by Trek Japan Co., Ltd., “MODEL-370”) is placed at a position rotated 90 degrees in the circumferential direction of the photoconductor from the position of the charging roll sample and 2 mm away from the photoconductor. The surface potential (charge amount) at the center of the photoreceptor was measured in the dark. When the average value of the measured waveform of the second round exceeds -550V, the charging ability is excellent as "A", and when it is from -520V to -550V or less, the charging ability is good as "B", less than -520V In the case of “C”, the charging ability is not sufficient.

-Durability against powder contamination-
The charging roll sample was attached to a color laser printer (“IPSIO SP C310”, manufactured by Ricoh Co., Ltd.), and 10,000 printing tests were performed in a 15 ° C. × 10% RH environment. In the printing test, cyan toner was used, and the printing rate was a 5% chart. After the printing test, the charging roll sample is removed from the printer, and the toner and toner adhering to a predetermined portion (axial width: 30 mm × circumferential length: 1/3 of the entire circumference) near the center of the charging roll sample. The external additive was wiped off. Thereafter, the charged roll sample was attached to the printer again, and a predetermined image (600 dpi dot pattern: halftone image) was output. Thereafter, the output image was visually observed. In the case where there is no image unevenness between the image corresponding to the toner and the external additive adhering portion and the image corresponding to the wiping portion, the toner and the external toner additive hardly adhere as dirt, and It was set as “A” as being excellent in durability against body dirt. When there is slight image unevenness between the image corresponding to the toner and the toner additive adhering portion and the image corresponding to the wiping portion, but the toner and the toner external additive are contaminated. Although it may adhere, it is within an allowable range, and “B” is given as being excellent in durability against powder dirt. When there is a clear image unevenness between the image corresponding to the toner and toner external additive adhering portion and the image corresponding to the wiping portion, the toner and toner external additive easily adhere as dirt, and the powder “C” was assigned as being inferior in durability to dirt.

-Sag resistance-
The prepared charging roll sample was placed on a metal drum (diameter: 24 mm), a load of 700 g was applied to the shafts at both ends of the charging roll sample, and the temperature was kept at 40 ° C. and humidity 95% while maintaining the state. For 4 weeks. Then, after taking out the charging roll sample from the above atmosphere and leaving it in the room for 30 minutes, the charging roll sample was removed from a color laser printer (“RIO”, “IPSIO”).
SP C310 ") and a predetermined image (600 dpi dot pattern: halftone image) was output. Thereafter, the output image was visually observed, and image evaluation was performed based on the degree of white streaks (image streaks) in the image due to the dents (sagging) of the charging roll sample. The case where there was no image streak due to the dent of the charging roll sample in the image was designated as “A” as being excellent in anti-sagging property. Although the image streaks due to the dent of the charging roll sample appeared thin in the image, but was within the allowable range, it was designated as “B” because the settling resistance was good. A case where image streaks due to the dents of the charging roll sample appeared clearly in the image was designated as “C” as being inferior to the settling resistance.

The detailed configuration and evaluation results of each charging roll sample are shown in Table 2 below.

According to Table 2, the following can be understood.
That is, the charging roll of Sample 8 does not contain any surface-modified polymer in the surface layer matrix polymer. Therefore, it can be seen that the charging roll of Sample 8 is inferior in all of charging ability, durability against powder stains on the surface, and resistance to settling.

  The charging roll of Sample 9 has a surface-modified polymer F having no amino group in the molecule and having a silicone group. Therefore, it can be seen that the charging roll of Sample 9 is inferior in charging ability and sag resistance although it has durability against powder contamination on the surface.

  The charging roll of the sample 10 uses a surface-modified polymer G having an amino group in the molecule but not having a silicone group. Therefore, it can be seen that the charging roll of sample 10 is inferior in durability against powder stains on the surface, although the charging ability and sag resistance are improved as compared with the charging roll of sample 8.

  The charging roll of the sample 11 uses the surface-modified polymer H having no amino group and no silicone group in the molecule and having a fluoroalkyl group in the molecule. However, as described above, it can be seen that only the fluoroalkyl group cannot simultaneously satisfy the charging ability, the durability against powder contamination on the surface, and the anti-sag property.

  On the other hand, the charging rolls of Sample 1 to Sample 7 all contain a specific surface-modified polymer having an amino group and a silicone group in the molecule in the surface layer matrix polymer. Therefore, the surface of the charging rolls of Sample 1 to Sample 7 is modified, and amino groups and silicone groups can exist on the surface of the surface.

  The charging rolls of Sample 1 to Sample 7 can charge the photoconductor not only by normal charging due to discharge in the gap around the contact portion with the photoconductor but also by friction at the contact portion. Therefore, it can be seen that the charging rolls of Sample 1 to Sample 7 can increase the charging capability for charging the photosensitive member, and have a high charging capability. The charging due to friction is not charging due to a discharge phenomenon, and is not easily affected by the level of applied voltage due to downsizing of the power source or the like. Therefore, it can be said that the charging rolls of Sample 1 to Sample 7 easily exhibit high charging ability. Further, since the charging rolls of Sample 1 to Sample 7 have the predetermined surface layer, powders such as toner and toner external additives are difficult to adhere as dirt, and have high durability against powder dirt. You can see that Further, the charging rolls of Sample 1 to Sample 7 can exhibit good settling resistance because the surface layer has good settling resistance. Therefore, it can be seen that the charging rolls of Sample 1 to Sample 7 are unlikely to leave a dent mark due to contact with the photoreceptor on the surface, and a decrease in charging ability due to this is suppressed, and a good image can be formed. Depending on the type of matrix polymer, if the surface polymer surface is selectively removed by washing the surface with a solvent that can dissolve the matrix polymer, the surface modified polymer is applied to the surface layer surface. Since it becomes easy to expose, the said effect can be made still more reliable.

  Further, when comparing the results of the charging rolls of Sample 1 to Sample 6, by adjusting the content of the surface-modified polymer with respect to the matrix polymer or changing the ratio of the above polymerized units in the surface-modified polymer, each characteristic can be changed. It can be seen that these balances can be controlled while maintaining both.

  Moreover, when the results of the charging rolls of Sample 3 to Sample 7 are compared, it is understood that each characteristic can be further improved by making the polymer structure of the surface-modified polymer a highly branched structure (hyperbranched structure). . This is because an amino group and a silicone group can be effectively present on the surface of the surface layer, and the effect of modifying the surface of the surface layer is increased.

  Moreover, the charging rolls of Sample 1 to Sample 7 use a compound having a (meth) acryl group in addition to the functional group in the molecule as a compound used for the polymerization reaction of the surface-modified polymer. Therefore, there exists an advantage which is easy to perform a copolymerization reaction at the time of preparation of a surface modification polymer.

  As mentioned above, although the Example of this invention was described in detail, this invention is not limited to the said Example, A various change is possible within the range which does not impair the meaning of this invention.

R charging roll 1 surface layer 2 shaft body 3 elastic layer

Claims (8)

A charging member used for charging a member to be charged,
A charging member comprising a surface layer containing a surface-modified polymer composed of a polymer having an amino group and a silicone group in a molecule in a matrix polymer. The charging member according to claim 1,
The surface-modified polymer includes a first polymer unit based on a first compound having an amino group in the molecule and a second polymer unit based on a second compound having a silicone group in the molecule. Element. The charging member according to claim 2,
The charging member, wherein the first compound and the second compound include an unsaturated bond in a molecule. The charging member according to claim 2 or 3,
The charging member, wherein the first compound and the second compound have a (meth) acryl group in a molecule. The charging member according to any one of claims 2 to 4,
The charging member according to claim 1, wherein the surface-modified polymer contains 1 to 98 mol% of the first polymer unit and 0.1 to 10 mol% of the second polymer unit. The charging member according to any one of claims 1 to 5,
A charging member comprising 0.5 to 20 parts by mass of the surface-modified polymer with respect to 100 parts by mass of the matrix polymer. The charging member according to any one of claims 1 to 6,
The charging member according to claim 1, wherein the surface-modified polymer has a highly branched structure. The charging member according to any one of claims 1 to 7,
The charging member is a latent image carrier in an electrophotographic image forming apparatus using a charged image.

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