JP2007017505A - Method for producing blade for electrophotographic apparatus, blade for the electrophotographic apparatus obtained by the same, and the electrophotographic apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing a blade for an electrophotographic apparatus which realizes proper fluidity in a molding die, allows curing reaction to proceed rapidly in the desired timing, shortens curing time, and ensures stable physical properties. <P>SOLUTION: In the method for producing a blade for an electrophotographic apparatus, when the blade for an electrophotographic apparatus is made of a polyurethane elastomer, obtained by mixing and curing a prepolymer comprising polyisocyanate and polyol and a curing agent comprising polyol and a catalyst; and at least one acid material selected from among an inorganic acid, an inorganic acid derivative and an organic acid derivative is contained in the prepolymer. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a blade used in an electrophotographic apparatus, a manufacturing method thereof, and an electrophotographic apparatus including the same.

  In general, in an electrophotographic apparatus, after transferring to a recording sheet, in order to remove the toner remaining on the photosensitive member and perform copying repeatedly, a cleaning blade in which a blade member is bonded to a support, A blade having an elastic member bonded to a support, such as a developing blade that forms a thin film while frictionally charging toner is provided.

  The cleaning blade is formed by integrating a metal holder that attaches the blade to the apparatus and the like, and a blade member made of an elastic body at one end of the holder, and the blade member has a degree of wear resistance and permanent distortion. For example, polyurethane elastomer is usually used.

  The polyurethane elastomer is produced according to a prepolymer method and a semi-one shot method using a polyisocyanate, a polyol, a chain extender and a catalyst.

  For example, in the case of the prepolymer method, a prepolymer is prepared using a polyisocyanate and a polyol, a chain extender and a catalyst are added to the prepolymer, and then this is injected into a molding die and cured. It is.

  The time from injection into the mold until curing and demolding, that is, the curing time greatly affects the production efficiency. If the curing time is long, the number of molds must be increased, and a huge investment is required. Therefore, various studies have been made to shorten the curing time.

  When trying to shorten the curing time by increasing the amount of catalyst, the catalyst that promotes urethanization such as triethylenediamine or dimethylimidazole, which has been widely used as a catalyst, accelerates the curing reaction immediately after mixing as the amount of catalyst increases. Since the viscosity of the mixed liquid becomes high, the mixed liquid does not move in the mold and the flow becomes insufficient. Moreover, since the urethane residue cured in the mixing chamber of the casting machine is cast in a state of being mixed in the mixed solution, there is a problem that foreign matters are mixed in the molded product.

  For this reason, the applicant of the present application firstly, a prepolymer obtained by partially polymerizing a polyisocyanate and a high molecular weight polyol, a curing agent mainly comprising a polyol, and saturated fatty acid potassium as a curing catalyst, A technology that realizes good fluidity in a mold by curing an isocyanate composition characterized in that it comprises, rapidly progressing the curing reaction at a desired timing, and shortening the curing time. Proposed (see Patent Document 1).

However, when the curing time is shortened, there is a problem that the physical properties of the obtained polyurethane elastomer vary and are not stable unless the conditions of the mold temperature and the curing time are controlled more severely. For this reason, the mold temperature must be within the range of the set temperature ± 5% and the curing time must be within the range of the set time ± 20%, and it is necessary to increase the accuracy, resulting in an increase in the cost of the apparatus.
JP 2002-80552 A

An object of the present invention is for an electrophotographic apparatus that realizes good fluidity in a mold, rapidly advances a curing reaction at a desired timing, shortens a curing time, and stably obtains properties of a polyurethane elastomer. It is to provide a method for manufacturing a blade.
Furthermore, it is providing the braid | blade obtained by the said manufacturing method and the electrophotographic apparatus provided with the same.

  The present invention achieves the object by the following means.

  The first invention according to the present application is the production of a blade for an electrophotographic apparatus comprising a prepolymer obtained by reacting a polyisocyanate and a polyol, and a polyurethane elastomer obtained by mixing and curing a curing agent comprising a polyol and a catalyst. In the method, the prepolymer includes at least one acidic substance selected from an inorganic acid, an inorganic acid derivative, and an organic acid derivative.

  A second invention according to the present application is the method for manufacturing a blade for an electrophotographic apparatus according to claim 1, wherein the one acidic substance is a phosphate ester.

  A third invention according to the present application is the method for producing a blade for an electrophotographic apparatus according to claim 1, wherein the content of the phosphate ester is 15 to 200 ppm with respect to the polyurethane elastomer.

  A fourth invention according to the present application is the method for manufacturing a blade for an electrophotographic apparatus according to claims 1 to 3, wherein the curing agent contains saturated fatty acid potassium.

  A fifth invention according to the present invention is a blade for an electrophotographic apparatus obtained by the above production method.

  A sixth invention according to the present invention is an electrophotographic apparatus provided with the above blade.

  According to the present invention, it is possible to achieve good fluidity in a mold, rapidly advance a curing reaction at a desired timing, shorten a curing time, and obtain a blade for an electrophotographic apparatus having stable physical properties.

Hereinafter, embodiments of the present invention will be described in detail.
The polyurethane elastomer used in the present invention is obtained by mixing and curing a prepolymer obtained by reacting a polyisocyanate and a polyol and a curing agent comprising a polyol and a catalyst.

  Examples of the polyisocyanate include 4,4′-diphenylmethane diisocyanate (MDI), 2,4-tolylene diisocyanate (2,4-TDI), 2,6-tolylene diisocyanate (2,6-TDI), and xylene diisocyanate. (XDI), 1,5-naphthylene diisocyanate (1,5-NDI), p-phenylene diisocyanate (PPDI), hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), 4,4′-dicyclohexylmethane diisocyanate (water) Additive MDI), tetramethylxylene diisocyanate (TMXDI), carbodiimide-modified MDI, polymethylenephenyl polyisocyanate (PAPI) and the like. Among these, it is preferable to use MDI.

  Examples of the polyol include polyester polyols, polyether polyols, caprolactone ester polyols, polycarbonate ester polyols, and silicone polyols, and the number average molecular weight is preferably 1500 to 5000. If it is 1500 or more, the physical properties of the resulting urethane rubber are good, and if it is 5000 or less, the viscosity of the prepolymer is appropriate and handling is preferred.

  A low molecular weight chain extender is used as the polyol. These are introduced on the curing agent side. For example, glycol is used, and as such glycol, ethylene glycol (EG), diethylene glycol (DEG), propylene glycol (PG), dipropylene glycol (DPG), 1,4-butanediol (1,4-BD) ), 1,6-hexanediol (1,6-HD), 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, xylylene glycol (terephthalyl alcohol), triethylene glycol and the like. In addition to the above glycols, polyhydric alcohols are used, and examples of such polyhydric alcohols include trimethylolpropane, glycerin, pentaerythritol, sorbitol, and the like. These may be used alone or in combination of two or more.

  For the prepolymer, an acidic substance selected from inorganic acids, inorganic acid derivatives, and organic acid derivatives is used.

  Examples of inorganic acids include phosphoric acid, hydrochloric acid, sulfuric acid, etc., and derivatives thereof include monoalkyl phosphates such as monomethyl phosphate, monobutyl phosphate, monoisodecyl phosphate, mono (2-ethylhexyl) phosphate, dimethyl phosphate, dibutyl Examples include dialkyl phosphates such as phosphate, diisodecyl phosphate, and di (2-ethylhexyl) phosphate. Moreover, aliphatic sulfonic acids, such as aromatic sulfonic acids, such as p-toluenesulfonic acid, and methanesulfonic acid are mentioned. Examples of the organic acid derivative include acid chlorides such as benzoyl chloride. Among these, phosphate esters such as mono- or dialkyl phosphate are preferable. These may be used alone or in combination of two or more.

  Since acidic substances have the effect of suppressing the reaction of isocyanate, the reaction rate of isocyanate can be lowered and kept constant, so there is no abnormal reaction or rapid local reaction, and a stable reaction is obtained. The physical properties of are stable. When no acidic substance is added, the prepolymer is highly reactive, so the behavior during the curing reaction changes greatly depending on the slight amount of the curing catalyst and the curing temperature, and the physical properties of the resulting urethane elastomer. However, by reducing the reactivity of the prepolymer, it becomes easy to adjust the curing reaction by the curing catalyst, and as a result, a urethane elastomer having stable physical properties can be obtained. Furthermore, the reaction at the time of synthesizing the prepolymer can be stabilized, and further, the storage stability of the prepolymer is also effective.

  The amount of the acidic substance added to the prepolymer is preferably 15 ppm or more and 200 ppm or less with respect to the polyurethane elastomer. More preferably, it is 20 ppm or more and 100 ppm or less. If it is 15 ppm or more, the reactivity can be appropriately reduced, and if it is 200 ppm or less, the reactivity is appropriately maintained, the curing time is appropriate, and the production efficiency can be maintained.

It is preferable that a hardening | curing agent contains a polyol and saturated fatty acid potassium. As the saturated fatty acid potassium, a salt represented by the following general formula (1) is preferable from the viewpoint of slow-acting effect and curing reaction promoting effect;
RCOOK (1)
(In the formula, R is an alkyl group represented by C _n H _{2n + 1} , and n is an integer of 0 to 15, inclusive).
Among the curing catalysts represented by formula (1), from the viewpoint of slow-acting and highest activity, potassium formate, potassium acetate, potassium propionate, potassium butyrate, potassium isobutyrate, potassium valerate, potassium isovalerate, pival Potassium acid, alkyl group linear and branched potassium caproate, alkyl group linear and branched potassium enanthate, alkyl group linear and branched potassium caprylate, alkyl group Is linear and branched potassium pelargonate, alkyl groups are linear and branched potassium caprate, alkyl groups are linear and branched potassium undecanoate, alkyl groups are linear and Branched potassium laurate, alkyl group linear and branched tridecanoic potassium, alkyl group linear Bifurcated potassium myristate, alkyl groups linear and branched potassium pentadecanoate, alkyl groups linear and branched potassium palmitate, alkyl groups linear and branched Preference is given to potassium heptadecanoate, potassium stearate whose alkyl group is linear and branched, and the like. Of these, potassium acetate, potassium caprylate having an alkyl group branched, and the like are preferable.

Furthermore, examples of commercially available products containing a curing catalyst that can be suitably used include trade names DABCO P15 (manufactured by Sankyo Air Products), trade names DABCO K15 (manufactured by Sankyo Air Products), and the like.
DABCO P15 contains 38.4% by mass of a curing catalyst represented by the following formula (2);
CH ₃ COOK (2).
DABCO K15 contains 75% by mass of a curing catalyst represented by the following formula (3);
_{C 4 H 9 CH (C 2} H 5) COOK (3).

  The amount of saturated fatty acid potassium added needs to be carefully optimized in order to produce blades with good properties. That is, in order to sufficiently cure the isocyanate composition, to obtain sufficient mechanical properties and the like of the resulting urethane rubber molded product, and to shorten the curing time, 1 mass ppm or more is preferable with respect to the entire isocyanate composition. More preferred is ppm by mass or more. Further, in order to sufficiently delay the time for starting the isocyanate composition to be cured and to achieve good mixing properties and injectability, 500 mass ppm or less is preferable, and 200 mass ppm or less is more preferable.

  If necessary, two or more kinds of saturated fatty acid potassium may be used as a curing catalyst, and conventionally known curing catalysts such as triethylenediamine (TEDA) and dimethylimidazole (DMIZ) may be used in combination. it can.

  If necessary, additives such as catalysts, pigments, plasticizers, waterproofing agents, antioxidants, ultraviolet absorbers, and light stabilizers can be added to the curing agent.

  The polyurethane elastomer of the blade member according to the present invention can be produced according to the prepolymer method and the semi-one shot method using the above materials.

  The holder used in the present invention may be any holder that is generally used for a blade for an electrophotographic apparatus, and examples thereof include a highly rigid steel plate, a stainless steel plate, a galvanized chromate coated steel plate, and a chromium-free steel plate.

  The adhesive that can be used in the present invention may be a general polyurethane-metal adhesive, and examples thereof include phenol-based and urethane-based adhesives.

  EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to these examples.

Example 1
(Molding of cleaning blade)
A holder was prepared in which a phenolic adhesive was applied to one end of one end of the holder in advance. A cleaning blade forming die composed of an upper die and a lower die was prepared, and placed in a state where one end of one end side of the holder protruded into a cavity for forming a blade portion of the mold.

  296.6 g of 4,4′-diphenylmethane diisocyanate, 703.4 g of polyethylene adipate (PEA) having a number average molecular weight of 2000, 50 mg of 2-ethylhexyl phosphate (mono, dimixture) (47.2 ppm as a polyurethane elastomer) at 80 ° C. The mixture was reacted for 3 hours to obtain a prepolymer having NCO% of 7.00%. Liquid obtained by mixing 39.1 g of 1,4-butanediol, 21.0 g of trimethylolpropane, 0.09 g of DABCO P15 (EG solution of potassium acetate, manufactured by Air Products Japan Co., Ltd.) and 0.18 g of TEDA. The composition was poured into a preheated mold, allowed to undergo a curing reaction, and the cured product was demolded to obtain a cleaning blade. The catalyst amount was adjusted so that the urethane could be removed in 1 minute without deformation of the urethane during the removal.

(Flowability to mold)
When the molded cleaning blade had no flow failure, it was evaluated as ◯, and when it was evaluated as x, there was no flow failure in the cleaning blade.

(hardness)
The hardness after aging (IRHD) was measured based on JIS K 6253 using a Wallace microhardness meter manufactured by Wallace (HW WALLACE). The curing temperature was changed within the range of the set temperature ± 5% and ± 10%, and the magnitude of the variation was determined by the difference between the maximum and minimum hardness at that time. The hardness difference was evaluated as ◎ when the difference was within 1 °, ◯ when it was within 2 °, and × when 3 ° or more. The hardness at ± 5% was 65 to 66 ° and the variation was ◎, and the hardness at ± 10% was 65 to 66 ° and the variation was ◎.

Example 2
The amount of 2-ethylhexyl phosphate (mono, di mixture) was 20 mg (18.9 ppm for polyurethane elastomer), except that P15 was 0.07 g and TEDA was 0.14 g in order to set the curing time to 1 minute. The same operation as in Example 1 was performed. When the flowability to the mold was ◯ and ± 5%, the hardness was 64 to 66 °, the variation was ◯, the hardness when ± 10% was 64 to 66 °, and the variation was ◯.

Example 3
The amount of 2-ethylhexyl phosphate (mono, di mixture) was 200 mg (188.7 ppm for polyurethane elastomer), except that P15 was 0.15 g and TEDA was 0.24 g in order to set the curing time to 1 minute. The same operation as in Example 1 was performed. When the flowability to the mold was ◯ and ± 5%, the hardness was 66 to 67 °, the variation was ◎, and when ± 10%, the hardness was 66 to 67 ° and the variation was ◎.

Comparative Example 1
The same procedure as in Example 1 was carried out except that 2-ethylhexyl phosphate (mono, dimixture) was not added and P15 was changed to 0.06 g and TEDA was set to 0.12 g in order to set the curing time to 1 minute. When the flowability to the mold was ◯ and ± 5%, the hardness was 64 to 66 °, the variation was ○, and when ± 10%, the hardness was 61 to 66 ° and the variation was x.

  In the examples of Table 1, the curing time is as short as 1 minute, and the variation in hardness of the obtained cleaning blade is small even when the curing temperature is in the range of the set temperature ± 10%. For this reason, it is not necessary to maintain the mold temperature with high accuracy, and it is possible to manufacture efficiently at a low apparatus cost. In Comparative Example 1 containing no acidic substance, the curing time is 1 minute, and the hardness variation is small when the curing temperature is the set temperature ± 5%. However, when the curing temperature is ± 10%, the variation is large. For this reason, the curing temperature must be maintained within a range of ± 5%, and high-precision control is required, resulting in a high apparatus cost.

Claims (6)

  In a method for producing a blade for an electrophotographic apparatus comprising a prepolymer obtained by reacting a polyisocyanate and a polyol, and a polyurethane elastomer obtained by mixing and curing a curing agent containing a polyol and a catalyst, an inorganic acid is contained in the prepolymer. A method for producing a blade for an electrophotographic apparatus, comprising at least one acidic substance selected from inorganic acid derivatives and organic acid derivatives. 2. The method for manufacturing a blade for an electrophotographic apparatus according to claim 1, wherein the one acidic substance is a phosphate ester. The method for producing a blade for an electrophotographic apparatus according to claim 2, wherein the content of the phosphate ester is 15 to 200 ppm with respect to the polyurethane elastomer.   4. The method for producing a blade for an electrophotographic apparatus according to claim 1, wherein the curing agent contains saturated fatty acid potassium.   A blade for an electrophotographic apparatus manufactured by the method according to claim 1.   An electrophotographic apparatus comprising the blade according to claim 5.