Summary of the invention
The present invention finishes take above-mentioned situation as background, to address the above problem as problem, provides a kind of and has good fatigue durability and hardness is low, and can advantageously bring into play the charged roller of desired electric conductivity.
The inventor etc. have repeatedly furtherd investigate the improvement of injection mo(u)lding (module injection molding) technology and have been that epichlorohydrin rubber and/or nitrile rubber (nitrile gum) are (NBR) as the rubber composition of rubber constituent take ionic conductivity rubber, the charged roller that discovery has the conductive elastomer layer of the rubber composition formation of using composition requirement can solve above-mentioned all problems, and then has finished the present invention.
Namely, the object of the present invention is to provide a kind of charged roller, described charged roller arranges the conductive elastomer layer around axis body, it is characterized in that, this conductive elastomer layer is formed by rubber composition, described rubber composition cooperates 0.7~1.0 weight portion peroxide cross-linking agent to form at 100 weight portions in as the epichlorohydrin rubber of ionic conductivity rubber and/or nitrile rubber, in described rubber composition, mismatch electronic conductor, and the ratio that exists of the rubber constituent in this conductive elastomer layer that is obtained by the thermogravimetric quantitative determination is more than 90 % by weight.
One of preferred version of the invention described above charged roller is: the ionic conductivity rubber that consists of above-mentioned rubber composition is epichlorohydrin rubber, with respect to the described epichlorohydrin rubber of 100 weight portions, further cooperates the following ionic conductive agent of 0.5 weight portion.
One of other preferred versions of charged roller of the present invention are: the ionic conductivity rubber that consists of above-mentioned rubber composition is nitrile rubber, and further cooperates the ionic conductive agent of 1~2 weight portion with respect to the described nitrile rubber of 100 weight portions.
In addition, charged roller for the invention described above, advantageously, described conductive elastomer layer is following formation: by at the metal mold-in injection or inject described rubber composition, thereby the layer that is formed by this rubber composition is set around the described axis body on the central shaft in being disposed at the metal pattern with cylindric molding cavity (cavity), again this layer is carried out peroxide crosslinking, thereby form described conductive elastomer layer.
As mentioned above, the conductive elastomer layer of charged roller of the present invention is to form by making the rubber composition that cooperates peroxide cross-linking agent to obtain in the ionic conductivity rubber of regulation carry out peroxide crosslinking, and the ratio that exists by the rubber constituent that obtains by the thermogravimetric quantitative determination is that cross-linking agent more than 90 % by weight consists of, so with present have collaboration the charged roller of the conductive elastomer layer that obtains of the rubber composition of the inorganic fillers such as silicon dioxide (filler) compare, have good fatigue durability, and hardness is low.
In addition, conductive elastomer layer in the above-mentioned charged roller is by using superoxide to replace the present sulfur vulcanization that adds that extensively carries out to form as the peroxide crosslinking of crosslinking chemical, can form the conductive elastomer layer by peroxide crosslinking as mentioned above, help very much to bring into play simultaneously good fatigue durability.
It is that epichlorohydrin rubber and/or nitrile rubber form as the rubber composition of rubber constituent that conductive elastomer layer in the charged roller of the present invention uses with ionic conductivity rubber, above-mentioned epichlorohydrin rubber and nitrile rubber all are the little rubber of specific insulation, so can advantageously present the desired electric conductivity of charged roller.
In addition, when requiring the conductive elastomer layer to have better electric conductivity, can collaboration the rubber composition of ionic conductive agent form the conductive elastomer layer, particularly, in the situation of only using epichlorohydrin rubber as ionic conductivity rubber, use cooperates the ionic conductive agent below 0.5 weight portion with respect to the above-mentioned epichlorohydrin rubber of 100 weight portions and the rubber composition that obtains forms the conductive elastomer layer, perhaps in the situation of only using nitrile rubber, use cooperates the ionic conductive agent of 1~2 weight portion with respect to the above-mentioned nitrile rubber of 100 weight portions and the rubber composition that obtains forms the conductive elastomer layer, can advantageously improve electric conductivity.
In addition, in the conductive elastomer layer that the rubber composition that obtains at present collaboration conductive carbon black forms, for prevent and image carrier surface between sew, must carry out at its axial two ends so-called C face processes, but, the conductive elastomer layer of charged roller of the present invention is as rubber constituent take ionic conductivity rubber, and do not contain the electronic conductors such as conductive carbon black, so the C face that the conductive elastomer layer in the charged roller of the present invention does not need must carry out is in the past processed.
In addition, for the charged roller of the present invention described conductive elastomer layer charged roller that is following formation particularly, not only can bring into play aforesaid good characteristic, and the superficiality of conductive elastomer layer is very good, and needn't carry out grinding or grinding step after crosslinked (sulfuration), and this operation is essential to the conductive elastomer layer made from existing rubber composition.The generation type of above-mentioned conductive elastomer layer is: the central shaft in the metal pattern with cylindric molding cavity (cavity) disposes axis body, by at the metal mold-in injection or inject described rubber composition, thereby the layer that is formed by this rubber composition is set around described axis body, again this layer is carried out peroxide crosslinking, thereby form described conductive elastomer layer.
Embodiment
Therefore, during charged roller constructed in accordance, at first, prepare the axis body (mandrel) that the electric conductor by specified length forms, simultaneously preparation is used for the rubber composition at above-mentioned axis body formation conductive elastomer layer.When preparing above-mentioned rubber composition, as the rubber constituent of major component, use epichlorohydrin rubber and/or nitrile rubber as ionic conductivity rubber.
In the present invention, as epichlorohydrin rubber, can use chloropropylene oxide homopolymer, chloropropylene oxide-ethylene oxide copolymer and on above-mentioned multipolymer further any one in the multipolymer that obtains of copolymerization allyl glycidyl ether etc., in addition, also may be used above-mentioned substance more than two kinds.
May be used above-mentioned one or two or more kinds epichlorohydrin rubber and nitrile rubber (NBR) among the present invention, can also use separately nitrile rubber.
Make the crosslinked crosslinking chemical of above-mentioned epichlorohydrin rubber plasma conducting rubber as being used for, use peroxide cross-linking agent among the present invention.By making ionic conductivity rubber peroxide crosslinking, rather than utilize the sulphur that in the past extensively adopted, thereby make the conductive elastomer layer that obtains and then can make the fatigue durability of charged roller good.
Among the present invention, with respect to 100 weight portion ionic conductivity rubber, with the ratio cooperation peroxide cross-linking agent of 0.7~1.0 weight portion.When the use level of peroxide cross-linking agent is lower than 0.7 weight portion, the crosslinked of ionic conductivity rubber can not carry out fully, the result might make the conductive elastomer layer of gained can not bring into play sufficient fatigue durability, on the other hand, when use level surpasses 1.0 weight portion, might make the hardness of conductive elastomer layer become too high.
As the peroxide cross-linking agent that uses among the present invention, so long as existing known crosslinking chemical all can use.Particularly can enumerate PERHEXA HC; PERHEXA V or PERHEXA C (are trade name; NOF Corp's system) the peroxy ketal class crosslinking chemical such as; PERHEXA 25B; PEROXYMON F; PERCUMYL D; PERBUTYLC; PERHEXYL D or PERBUTYL D (are trade name; NOF Corp's system) the dialkyl peroxide class crosslinking chemical such as; PERBUTYL E; the peroxyesters crosslinking chemicals such as PERBUTYL I or PERBUTYL Z (being trade name, NOF Corp's system); ketone peroxide class crosslinking chemical; the peroxy dicarbonates crosslinking chemical; diacyl peroxide class crosslinking chemical; hydroperoxide type crosslinking chemical etc.Can from above-mentioned known peroxide cross-linking agent, select one or two or more kinds crosslinking chemical to be used according to purpose.
Above-mentioned epichlorohydrin rubber and nitrile rubber as ionic conductivity rubber all is the less rubber of specific insulation, but when requiring to have the charged roller of better electric conductivity, in the rubber composition that is formed by ionic conductivity rubber and peroxide cross-linking agent, further cooperate ionic conductive agent (ionic conduction class conductive agent).
If the use level of above-mentioned ionic conductive agent is very few, then can not show fiting effect, on the other hand, even cooperate a large amount of ionic conductive agents can not significantly improve electric conductivity, the probability of happening that oozes out on the contrary (bleed) increases, so according to suitably definite use levels such as the desired electric conductivity of purpose charged roller.Preferably when the rubber constituent that consists of rubber composition is epichlorohydrin rubber, in rubber composition, cooperate ionic conductive agent with respect to the above-mentioned epichlorohydrin rubber of 100 weight portions with the ratio below 0.5 weight portion, in addition, when the rubber constituent that consists of rubber composition is nitrile rubber, in rubber composition, cooperate ionic conductive agent with respect to the above-mentioned nitrile rubber of 100 weight portions with the ratio of 1~2 weight portion.Need to prove, as spendable ionic conductive agent among the present invention, can enumerate existing known various conductive agents, the perchlorate such as quaternary ammonium salt, lithium perchlorate or potassium perchlorate such as tributyl ethyl ammonium sulfovinate, tetrabutylammonium chloride, Tetrabutylammonium bromide, tetrabutylammonium iodide or TBAP, organic boron complex etc.
But, when making the conductive elastomer layer of charged roller of the present invention, do not use the electronic conductors (electronic conduction class conductive agent) such as conductive carbon black.Because when cooperating above-mentioned conductive carbon black etc. in rubber composition, the hardness of the conductive elastomer layer of gained is risen, fatigue durability worsens.
As mentioned above, the conductive elastomer layer of charged roller of the present invention is to utilize the rubber composition take epichlorohydrin rubber plasma conducting rubber as rubber constituent to form, and mismatches the electronic conductors such as conductive carbon black in the described rubber composition.Therefore, the conductive elastomer layer that forms of the rubber composition of electronic conductor that utilized in the past cooperation, generally for prevent and image carrier surface between sew, must carry out at the axial two ends of above-mentioned elastomer layer so-called C face and process, and the conductive elastomer layer in the charged roller of the present invention does not need to carry out above-mentioned C face processing.
When making the conductive elastomer layer of charged roller according to the present invention, identical with rubber composition in the past, can cooperate crosslinking coagent, crosslinking accelerator or other various adjuvants with respect to above-mentioned ionic conductivity rubber and peroxide cross-linking agent (also comprising as required ionic conductive agent).But only the ratio that exists in the rubber constituent that the crosslinked conductive elastomer layer that obtains of rubber composition is obtained by thermogravimetric quantitative determination (TG) is 90 % by weight when above, just can cooperate above-mentioned adjuvant.
Namely, the conductive elastomer layer of charged roller of the present invention is that the ratio that exists by the rubber constituent that obtains by the thermogravimetric quantitative determination is that cross-linking agent more than 90 % by weight forms, the ratio that exists of rubber constituent is higher than in the past conductive elastomer layer, so have good fatigue durability, hardness also is controlled in than low degree simultaneously.
The ratio that exists of the so-called rubber constituent that obtains by the thermogravimetric quantitative determination calculates according to following methods among the present invention.
At first, sampling obtains sample from the conductive elastomer layer (cross-linking agent under the condition that perhaps condition with formation conductive elastomer layer time is identical that the rubber composition of same composition is crosslinked, that moulding obtains) that the rubber composition peroxide crosslinking is obtained.Use said sample, contained extraction composition in quantitative test sample volatile ingredients such as () trace mineral supplements.Particularly, 1) after the weight of mensuration sample; 2) use acetone etc. as solvent according to soxhlet extraction method (condition: 80 ℃ * 16 hours), from sample, extract volatile ingredient; 3) behind the sample after the air-dry extraction, in being set as 70 ℃ vacuum drier, place and make its drying a night; 4) above-mentioned drying is measured the weight of sample afterwards.Before being extracted by volatile ingredient the weight of sample and extract after the weighing scale of sample calculate volatile ingredient in the sample have a ratio (A[% by weight]).
On the other hand, use thermogravimetric amount determining device (thermobalance) with programming rate: 20 ℃ of/minute other samples that sampling is obtained carry out the thermogravimetric quantitative determination.At this moment, (in the nitrogen stream) is warming up to 600 ℃ by normal temperature under blanket of nitrogen, and (in the air draught) is warming up to 900 ℃ from 600 ℃ under oxidizing atmosphere.Weight under the blanket of nitrogen reduces gasification that part is volatile ingredient contained in the sample and the decomposition of rubber constituent causes, it is that the oxygenolysis of carbon causes that the weight under the oxidizing atmosphere reduces part, is warming up to part residual after 900 ℃ as ash content.Behind the said determination, that utilizes that each weight reduces that part quantitatively reaches " volatile ingredient and rubber constituent ", " carbon divides " " ash content " exists ratio (% by weight).There is a ratio (% by weight) from what the value that exists ratio (A[% by weight]) to obtain of utilizing existing of thermogravimetric quantitative determination quantitative " volatile ingredient and rubber constituent " to deduct volatile ingredient in the sample that is calculated by additive method the ratio was rubber constituent.
So, during charged roller constructed in accordance, use above-mentioned rubber composition, preferably according to injection molding method (module injection molding method), around axis body (mandrel), form rubber composition layer (the conductive elastomer layer before crosslinked).Particularly, the middle mandrel in having the metal pattern of cylindric molding cavity disposes axis body (mandrel), under this state, to metal mold-in injection or injection rubber composition, forms the rubber composition layer around axis body (mandrel).Above-mentioned rubber composition layer is implemented crosslinked operation, obtain thus conductive roll of the present invention.The superficiality of the conductive elastomer layer of the charged roller that obtains as mentioned above is very good.Need to prove that the various conditions during injection mo(u)lding and the temperature conditions when crosslinked etc. depend on composition of rubber composition etc., can suitably select.
Need to prove, can also form protective seam on the surface (outer peripheral face of conductive elastomer layer) of the conductive roll of making as mentioned above as required.This protective seam arranges for suppressing toner to adhere to, be deposited in roller surface etc.; such as can be formed: contain at fluorin modified crylic acid ester resin etc. in the nylon materials such as the resin combination material of fluorine-type resin or N-methoxy nylon etc. and cooperate the conductive agents such as carbon black or metal oxide, make its specific insulation generally reach 1 * 10
5~1 * 10
13Ω cm.Need to prove that such as making above-mentioned protective seam according to known coating methods such as infusion processes, its thickness is suitably set according to the size (diameter, length) of conductive roll, but is generally about 1~20 μ m.
Charged roller in the past is in order to control the resistance of charged roller integral body; improve proof voltage (the anti-property sewed); usually between conductive elastomer layer and above-mentioned protective seam, electric resistance adjusting layer is set; but the conductive elastomer layer of charged roller of the present invention is because take ionic conductivity rubber as rubber constituent, so usually do not need above-mentioned electric resistance adjusting layer.
And the conductive elastomer layer of charged roller obtained above has good fatigue durability, simultaneously hardness is controlled at than low degree.
[embodiment]
Below enumerate several embodiments of the invention, be described more specifically the present invention, self-evident, the present invention is not enumerated any restriction of embodiment described content.In addition, be construed as, the present invention can also be beyond above-mentioned concrete record except following embodiment, only otherwise break away from aim of the present invention, carries out various changes, modification, improvement etc. based on those skilled in the art's knowledge.
At first form different 16 kinds of rubber compositions (rubber composition No.1~16) according to the preparation of the mixing ratio shown in following table 1 and the table 2.Need to prove, use the Epichlomer CG102 (trade name) of DAISO Co., Ltd's system as epichlorohydrin rubber during preparation, use the Nipo13335 (trade name) of Japanese ZEON Co., Ltd. system as nitrile rubber, using the DHT4A (trade name) of Kyowa Chemical Industry Co., Ltd's system is hydrotalcite (hydrotalcite) as plumper, use dicumyl peroxide (trade name: PERCUMYL D, NOF Corp's system) as peroxide cross-linking agent, use quaternary ammonium salt as ionic conductive agent.In addition, in following table 1 and table 2, vulcanization accelerator A represents the Sanceler CZ (trade name) of three new chemical industry Co., Ltd. systems, vulcanization accelerator B represents the Nocceler TRA (trade name) of the emerging chemical industry of imperial palace Co., Ltd. system, and vulcanization accelerator C represents the Nocceler TT (trade name) of the emerging chemical industry of imperial palace Co., Ltd. system.
[table 1]
[table 2]
Use 16 kinds of rubber compositions of preparation, at first, measure following each physical property according to the whole bag of tricks.Its measurement result is shown in following table 3 and table 4 as material behavior.
-rubber divide rate-
The cross-linking agent (sulfide) that use obtains each rubber composition crosslinked (sulfuration) carries out the thermogravimetric quantitative determination as sample according to the method for above-mentioned explanation, and what calculate rubber constituent in the said sample exists ratio (rubber minute rate).
-compression set-
Use each rubber composition 160 ℃ of lower pressurization crosslinked (sulfuration) moulding 30 minutes, obtain being cross-linking agent (sulfide) sample of regulation shape.The sample that use obtains is measured compression set (%) based on JIS-K-6262.
-specific insulation-
Use each rubber composition 160 ℃ of lower pressurization crosslinked (sulfuration) moulding 30 minutes, obtain the sheet sample of thickness 2mm.Silver coating paste on a side surface of the sheet sample that obtains, the electrode (having shielding (guard) electrode) of 10mm * 10mm size is set thus, on the other hand, at the face with the face opposition side that electrode is set opposite electrode is set, be determined at based on the method for putting down in writing among the JIS-K-6911 and apply voltage: two interelectrode resistance under the condition of 100V calculate specific insulation (Ω cm).
Next, use each rubber composition of gained, make in accordance with the following methods charged roller.
That is, preparation has the shaping mould (metal pattern) of the cylindric molding cavity of regulation, and the central shaft in metal pattern is injected rubber composition after disposing axis body (mandrel) in above-mentioned metal pattern.Then, crosslinked (sulfuration) operation of stipulating forms the conductive elastomer layer at axis body thus.And then after the protective seam that the coating of the surface spray of conductive elastomer layer is comprised of 100 weight portion N-methoxy nylon and 8 weight portion conductive carbon blacks forms with resin, make its drying.Use each rubber composition, be produced on as mentioned above mandrel (diameter: have conductive elastomer layer (thickness: 3mm), also have protective seam (thickness: charged roller 10 μ m) on the surface of described conductive elastomer layer 6mm).
To the use that obtains as mentioned above the various physical property of charged roller of each rubber composition, measure, estimate.The evaluation of above-mentioned physical property and mensuration are implemented respectively in accordance with the following methods, and its evaluation (mensuration) result is shown in following table 3 and table 4 in the lump as the roller evaluation result.
-little rubber hardness-
Use atomizing hardness tester (the miniature durometer MD-1 type that adopts the board-like loading mode of single-beam shape spring, macromolecule gauge Co., Ltd. system), under the state of supporting two ends with the V-type wooden unit, make the front end in contact of the probe of the surface of direction of principal axis central portion of each conductive roll of maintenance level and above-mentioned atomizing hardness tester, and then with the loading of 33.85g testing machine is vertically pressurizeed, read immediately scale, measure.
-roller resistance-
As shown in Figure 1, with the loading of regulation with the two ends of the conductive roll made by be pressed in metallic roll (diameter: under the state 24mm), make above-mentioned metallic roll with the rotation number of regulation by direction of arrow rotation among the figure, drive thus conductive roll and rotate.While keeping above-mentioned state (metallic roll and conductive roll are together rotated), the end of conductive roll and metallic roll between apply the voltage of 300V on one side, measure the current value that flows through, obtain resistance value (roller resistance: Ω).
-tired amount, fatigue evaluation-
Metallic roll (diameter: 24mm) the mounting charged roller of making, on the axis body (mandrel) at the two ends of charged roller, apply respectively the loading of 500g, keep this state, in temperature: 40 ℃, humidity: placed for 2 weeks under 95% the atmosphere.Then, from above-mentioned atmosphere, take out charged roller, after 30 minutes, be determined at the depression (mm) that produces on the charged roller surface, as the fatigue amount in indoor placement.In addition, above-mentioned charged roller is installed in real machine (company of Hewlett-Packard (Hewlett-Packard) system, trade name: CNJ3000), utilize the image (test pattern) of this real machine output regulation.The image of visual inspection output carries out fatigue evaluation by the having or not of deforming stripe that the depression (fatigue) by charged roller produces.Need to prove that metewand is as follows.
Zero: do not have deforming stripe in the image of output.
*: there is deforming stripe in the image of output.
-durable pollution evaluation-
The charged roller of making is installed in real machine (Fuji Xerox Co., Ltd. system, trade name: DocuPrint C3530), use above-mentioned real machine, in temperature: 32.5 ℃ * humidity: Type Test (the typewriting rate: 5%) of carrying out 5000 under 83% the environment.Then, take out charged roller from real machine, the tacky state of its surperficial toner of visual inspection or external additive is estimated.Metewand is as follows.
Zero: roller surface substantially do not adhere toner and external additive.
△: roller surface slightly adhere toner or external additive.
*: the roller adhesive surface has toner or the external additive of the degree of appreciable impact image.
-ooze out evaluation-
With the charged roller of making in temperature: 50 ℃ * humidity: after placing for 2 weeks under 90% the atmosphere, visual inspection roller surface has or not to be oozed out.Then, charged roller is installed in real machine (Hewlett-Packard's system, trade name: CNJ3000), utilize the image (test pattern) of this real machine output regulation, the image of visual inspection output.And based on the observations on the roller surface before the image output and the observations of output image, ooze out evaluation.
Metewand is as follows.
Zero: the roller surface has no to be oozed out, and does not exist image bad in the output image.
△: as seen the roller surface is oozed out, but does not exist image bad in the output image.
*: as seen the roller surface is oozed out, and exists image bad in the output image.
[table 3]
[table 4]
By the result of above-mentioned table 3 and table 4 as can be known, the charged roller that obtains according to the present invention (using rubber composition No.1~11 to form the charged roller of conductive elastomer layer) the good fatigue durability of performance, hardness is low simultaneously, confirmed in addition can advantageously bring into play desired electric conductivity by changing the use level of ionic conductive agent.