JP2019045774A - Cleaning blade and method for manufacturing the same - Google Patents

Abstract

To provide a cleaning blade comprising a polyurethane elastic body having a hardness uniformly increased with (meth)acrylate resin at a tip ridge part.SOLUTION: A cleaning blade comprises a polyurethane elastic body used for an image forming apparatus using an electrostatic transfer process, and the polyurethane elastic body has a hard segment in an amount of 31 to 50 weight%, has an inter-crosslinking molecular weight of 4000 to 16000, and includes a layer mixed with (meth)acrylate resin at a portion including a tip ridge part.SELECTED DRAWING: None

Description

  The present invention relates to a cleaning blade for removing residual toner on the surface of a photosensitive member in an image forming apparatus using an electrostatic transfer process such as a plain paper copying machine, a plain paper facsimile, and a laser beam printer, and a manufacturing method thereof.

  Conventionally, in an image forming apparatus utilizing an electrostatic transfer process, unnecessary residual toner adhering to the surface after transfer of a toner image to transfer paper or an intermediate transfer member is removed by a cleaning device as a cleaning means. As a cleaning member used for such cleaning means, one using a strip-shaped cleaning blade is generally known. The cleaning blade is made of a polyurethane elastic material or the like, and the base end of the cleaning blade is supported by a support member, the leading edge portion is pressed against the peripheral surface of the image carrier, and the toner remaining on the image carrier is clamped. Scrape and remove.

  In recent years, a polymerized toner, which is a fine particle toner, is used in an image forming apparatus for sharpening an image, and when the polymerized toner is used, cleaning failure occurs due to slight wear of the cleaning blade. Much more stringent cleanability than before is required.

  In the following Patent Document 1, the polyurethane elastic body is impregnated with the (meth) acrylate compound in the method of manufacturing the cleaning blade in which the elastic blade is formed by impregnating and curing the (meth) acrylate compound in part of the polyurethane elastic body. After that, by optimizing the solvent for washing and removing the (meth) acrylate compound remaining on the surface of the polyurethane elastic body, a technique is described that suppresses the occurrence of the difference in hardness of the obtained elastic blade and the generation of surface irregularities. .

  Further, in Patent Document 2 below, in a cleaning blade having an elastic blade formed by impregnating and curing a (meth) acrylate compound in part of a polyurethane elastic body, the parallel swelling ratio is 200 when immersed in cyclohexanone. Techniques have been described that use% or more polyurethane elastomers.

Unexamined-Japanese-Patent No. 2015-158654 JP, 2016-148791, A

  However, in any of the above-mentioned patent documents, optimization studies of the polymer properties of the polyurethane elastic body impregnated with the (meth) acrylate compound have not been sufficiently conducted, and as a result, the hardness of the polyurethane elastic body other than the tip ridge portion is increased. It has been found that it is difficult to achieve a well-balanced improvement in the hardness of the polyurethane elastic body at the tip ridge portion and the sufficient hardness.

  The present invention has been made in view of the above-described circumstances, and an object thereof is to provide a polyurethane elastic body having a high hardness as a whole, while uniformly hardening the portion including the tip ridge portion with a (meth) acrylate resin. It is in providing a cleaning blade.

  The above object can be achieved by the present invention as described below. That is, the present invention is a cleaning blade including a polyurethane elastic body used in an image forming apparatus utilizing an electrostatic transfer process, wherein the polyurethane elastic body has a hard segment amount of 31 to 50% by weight and a molecular weight between crosslinks of 4000. The present invention relates to a cleaning blade including a mixed layer with a (meth) acrylate resin in a portion including 1 to 16000 and including a tip ridge portion.

  The cleaning blade according to the present invention uses a polyurethane substrate having a hard segment amount of 31 to 50% by weight and a molecular weight between crosslinks of 4000 to 16000, and the portion including the tip ridge portion is impregnated with a (meth) acrylate compound. And polymerizing and resinifying it, the portion including the edge ridge portion is provided with a polyurethane elastomer modified with (meth) acrylic resin. As a result, since not only the portion including the tip ridge portion but also the entire polyurethane elastic body is made high in hardness, it is possible to particularly suppress deformation such as curling of the cleaning blade during the cleaning operation. For this reason, the cleaning blade according to the present invention is particularly excellent in the cleaning performance.

  The present invention also relates to a method of manufacturing a cleaning blade having a polyurethane elastic body used in an image forming apparatus utilizing an electrostatic transfer process, wherein the hard segment amount is 31 to 50% by weight, and the molecular weight between crosslinks is 4000 to 16000. Step I of forming a polyurethane substrate, Step II of impregnating a portion including the tip ridge portion of the substrate with a curable composition containing a (meth) acrylate compound, and washing at least the impregnated portion of the substrate And removing the curable composition remaining on the surface of the impregnated portion of the substrate, curing the curable composition impregnated on the substrate, and curing the curable composition in the portion including the tip ridge portion (meth) And a step IV of forming a polyurethane elastic body including a mixed layer with an acrylate resin. According to this manufacturing method, it is possible to manufacture a polyurethane elastic body having a high hardness as a whole, not only the portion including the tip ridge portion, and finally, a cleaning blade having particularly excellent cleaning performance is manufactured. be able to.

  The cleaning blade according to the present invention comprises a support made of a metal plate, a polyurethane elastic body, and an adhesive layer for adhering the support and the polyurethane elastic body.

  The polyurethane substrate to be a material of the polyurethane elastomer can be produced by polymerizing a diisocyanate compound, a difunctional polyol, a crosslinking agent consisting of a trifunctional alcohol, and a chain extender consisting of a glycol.

  As a diisocyanate compound, known compounds can be used, and aromatic diisocyanates such as 4,4'-diphenylmethane diisocyanate (MDI), 2,4-toluene diisocyanate (2,4-TDI), hexamethylene diisocyanate, hydrogenation Examples thereof include aliphatic or alicyclic diisocyanate compounds such as MDI. Among these, MDI is preferably used in consideration of the cleaning characteristics of the cleaning blade, in particular, the edge chipping resistance.

  As the bifunctional polyol, for example, polyester polyol, polyether polyol and the like can be exemplified, but in the present invention, it is particularly preferable to use a bifunctional polyester polyol. As a bifunctional polyester polyol, one or two or more low molecular weight glycols such as ethylene glycol, propylene glycol, butanediol, pentanediol, hexanediol, cyclohexanedimethanol, neopentyl glycol and the like and glutaric acid, adipic acid, pimelic acid A condensation polymer with one or more of suberic acid, sebacic acid, dimer acid, hydrogenated dimer acid or other dicarboxylic acids and oligomer acids, propiolactone using a low molecular weight glycol as an initiator, ε-caprolactone, Examples thereof include ring-opened polymers obtained by ring-opening addition of cyclic esters such as valerolactone.

  Among the above-exemplified bifunctional polyester polyols, the use of polycaprolactone polyol, which is a ring-opening polymer of ε-caprolactone, is particularly preferable. Polycaprolactone polyols are produced by the ring-opening addition of ε-caprolactone using low molecular weight glycol as an initiator in the presence of a catalyst, but in particular a stannous halide as a catalyst, more preferably stannous chloride as a catalyst The polycaprolactone polyol used as is preferable because a cleaning blade having a narrow molecular weight distribution and excellent edge chipping resistance is obtained. As a polycaprolactone polyol of narrow molecular weight distribution, there is a Plaxel-N series (such as Plaxel 220N) as a commercial item. The number average molecular weight of the difunctional polyester polyol is preferably 1000 to 4000, and more preferably 2000 to 4000.

  In the present invention, the polyurethane substrate may be produced by reacting a diisocyanate compound, a difunctional polyol, a crosslinking agent consisting of a trifunctional alcohol, and a chain extender consisting of a glycol in one step. It is preferable to manufacture by the prepolymer method which makes a functional polyol react beforehand. Such prepolymer method will be described later.

  The trifunctional alcohol acts as a crosslinker, and compounds known in the polyurethane art can be used without limitation. Specifically, trimethylol alkanes such as glycerin and trimethylol propane are exemplified. Among these, the use of trimethylolpropane is particularly preferable because a polyurethane elastic body having a stable cross-linked structure can be formed, with the three hydroxyl groups having the same reactivity.

  As chain extenders, known compounds in the technical field of polyurethane can be used without limitation, and for example, low molecular weight glycols such as ethylene glycol, propylene glycol, butanediol, pentanediol, hexanediol, cyclohexanedimethanol, neopentyl glycol and the like Can be mentioned. Among these, the use of 1,4-butanediol is particularly preferred.

In the present invention, a polyurethane elastic body having a hard segment content of 31 to 50% by weight and a molecular weight between crosslinks of 4000 to 16000 is used as the polyurethane elastic body constituting the cleaning blade. The hard segment amount Hs (wt%) is the average molecular weight and weight ratio of the diisocyanate compound respectively Ma and a, the number average molecular weight and weight ratio of the bifunctional polyol each Mb and b, the average molecular weight of the crosslinker consisting of the trifunctional alcohol The weight ratio can be represented by the following formula (1), where Mc and c, and the average molecular weight and weight ratio of glycol are Md and d, respectively.
Hs (wt%) = 100 [a-1.5 Ma (c / Mc) + d] / (a + b + c + d) (1)

  In the present invention, the hard segment amount Hs of the polyurethane elastomer is preferably set to 31 to 50% by weight, and preferably 31.5 to 48% by weight.

The cross-link molecular weight Mc of the polyurethane elastomer is likewise the average molecular weight and weight ratio of the diisocyanate compound respectively Ma and a, the number average molecular weight and weight ratio of the bifunctional polyol respectively Mb and b, and the crosslinker of the trifunctional alcohol The average molecular weight and weight ratio can be represented by the following formula (2) when Mc and c, and the average molecular weight and weight ratio of glycol are Md and d, respectively.
Mc = (a + b + c + d) / (c / Mc) (2)

  In the present invention, it is preferable to set the molecular weight between crosslinks of the polyurethane elastic body to 4000 to 16000, and it is preferable to set it to 4000 to 15000.

  A polyurethane polymerization catalyst may be used when producing a polyurethane substrate to be a material of the polyurethane elastomer. Such polymerization catalysts include organic tin catalysts such as dibutyltin dilaurate and tin octylate, triethylenediamine, N-methylmorpholine, N, N, N ', N'-tetramethylethylenediamine, N, N, N', N '-Tetramethylhexamethylenediamine, 1,8-diazabicyclo [5,4,0] undecen-7 (DBU), bis (N, N-dimethylamino-2-ethyl) ether, bis (2-dimethylaminoethyl) Examples thereof include tertiary amine catalysts such as ether, metal carboxylate catalysts such as potassium acetate and potassium octylate, and imidazole catalysts. Among these, use of a tertiary amine catalyst is preferred.

  The method for producing a cleaning blade according to the present invention comprises the step I of forming a polyurethane substrate having a hard segment amount of 31 to 50% by weight and a molecular weight between crosslinks of 4000 to 16000, and a portion including the front end ridge portion of the substrate A process II of impregnating a curable composition comprising a (meth) acrylate compound, and washing at least the impregnated part of the substrate to remove the curable composition remaining on the surface of the impregnated part of the substrate Including step III, and curing the curable composition impregnated in the base material to form a polyurethane elastic body including a mixed layer with a (meth) acrylate resin in a portion including the tip ridge portion. It features. Below, each process is demonstrated.

  The production of the polyurethane substrate can be carried out by known methods, for example, a prepolymer production process for producing an isocyanate prepolymer or an isocyanate pseudo prepolymer by reacting a difunctional polyol and a diisocyanate compound, an isocyanate prepolymer or an isocyanate. A mixing step of mixing the pseudo prepolymer with a component containing a crosslinking agent and a chain extender to form a reactive composition, a molding step of molding the reactive composition into a predetermined shape using a mold, etc., molding When the body is in the form of a sheet, it can be manufactured by a manufacturing step (step I) including a cutting step of cutting the sheet into a predetermined blade shape. The polyurethane substrate (and the polyurethane elastic body in which the mixed layer with (meth) acrylate resin is formed in the portion including the tip ridge portion) is molded into a blade shape, and in the present invention, the member to be cleaned such as an image carrier The surface opposite to is called the lower surface, and the surface of the tip including the tip ridge line part is called the tip surface.

  In Step II, the portion of the substrate containing the front ridge portion is impregnated with a curable composition containing a (meth) acrylate compound. As the (meth) acrylate compound, di (meth) acrylate having a functional group number of 2 can be suitably used, and for example, an alicyclic di (meth) acrylate compound such as tricyclodecanedimethanol di (meth) acrylate is It is usable. If necessary, a curable composition is prepared by appropriately mixing a (meth) acrylate compound with a photoradical polymerization initiator and a solvent. As a method of impregnating the curable composition into the substrate, for example, a dipping method in which the substrate is dipped from the tip ridge portion in a liquid bath containing the curable composition can be used. The degree to which the substrate is immersed in the liquid bath containing the curable composition to form the mixed layer can be appropriately changed depending on the product shape and the required characteristics, for example, the ridge line of the tip of the substrate The entire surface including the tip, and a portion of 3 mm ± 1 mm from the tip ridge portion in the lower surface may be immersed in the curable composition, and the immersion portion may be used as a mixed layer.

  In step III, at least the impregnated portion of the substrate is washed to remove the curable composition remaining on the surface of the substrate. As a method of removing the curable composition remaining on the surface of the substrate, for example, a dipping method in which at least the impregnated portion of the substrate is immersed in a liquid bath containing an organic solvent such as cyclohexane as a cleaning solution can be used. After immersion, an air drying step or a wiping step with a sponge or the like may be carried out, if necessary.

  In step IV, the curable composition impregnated in the substrate is cured to form a polyurethane elastic body including a mixed layer with a (meth) acrylate resin in the portion including the tip ridge portion. As a curing method of the curable composition, for example, a method of photopolymerizing a (meth) acrylate compound in the curable composition by irradiating ultraviolet light can be mentioned. After step IV, if necessary, heat curing and heat drying using an oven may be performed.

  By the above method, it is possible to manufacture a polyurethane elastic body including a mixed layer with a (meth) acrylate resin in a portion including the tip ridge portion. The obtained polyurethane elastic body is adhered to a support such as a metal fitting using an adhesive or the like, and is used as a cleaning blade unit for assembly of a copying machine or the like.

  Hereinafter, examples that specifically show the configuration and effects of the present invention will be described. In addition, the evaluation item in an Example etc. measured as follows.

(1) Martens Hardness Martens hardness was measured using a Martens hardness tester (Microhardness tester FISCHERSCOPE HM2000 manufactured by Fischer Instruments Co., Ltd.) on a polyurethane substrate and a polyurethane elastic body having a thickness of 2 mm manufactured below. . Specifically, the Martens hardness was measured by pressing the Vickers quadrangular pyramid indenter of a Martens hardness tester from the sheet surface in the vertical direction with a load of 1.0 mN / 10s. The results are shown in Table 1.

(2) Number Average Molecular Weight The number average molecular weight was measured by GPC (gel permeation chromatography), and converted to standard polystyrene.
GPC apparatus: Shimadzu Corporation LC-10A
Column: Three columns of Polymer Laboratories (PLgel, 5 μm, 500 Å), (PLgel, 5 μm, 100 Å), and (PLgel, 5 μm, 50 Å) are connected and the flow rate used: 1.0 ml / min
Concentration: 1.0 g / l
Injection volume: 40 μl
Column temperature: 40 ° C
Eluent: Tetrahydrofuran

(3) Hardness The hardness of the polyurethane elastic body was measured at 23 ° C. in accordance with JIS-K6253.

Examples 1 to 3, Comparative Example 1
43.12 by weight ratio of 4,4-diphenylmethane diisocyanate (p-MDI) (molecular weight 250.25) and lactone-based polyol PCL 220 N (number average molecular weight 2000, manufactured by Daicel Chemical Industries, Ltd.) which is a bifunctional polyol; By reacting in a ratio of 98, an isocyanate group-containing pseudo prepolymer was produced. Lactone-based polyol PCL 240 CP (number average molecular weight 4000, manufactured by Daicel Chemical Industries, Ltd.), which is a bifunctional polyol having a total content of 100 parts by weight of the isocyanate group-containing pseudoprepolymer, and trimethylolpropane (molecular weight 134) .17) By mixing and reacting 1,4-butanediol (molecular weight 90.12) in the proportions described in Table 1, a polyurethane substrate (thickness 2 mm, length 317.6 mm, width 11.5 mm) is obtained. Manufactured (Step I). Table 1 shows the hard segment amount Hs and the inter-crosslinking molecular weight Mc of the polyurethane substrate (= polyurethane elastomer finally produced).

  80% by weight of tricyclodecanedimethanol diacrylate (trade name "A-DCP", manufactured by Shin-Nakamura Chemical Co., Ltd.) as a (meth) acrylate compound, Irgacure 184 as a photo radical polymerization initiator (manufactured by Ciba Specialty Chemicals) Immersing the portion including the front end ridge portion of the polyurethane substrate obtained in step I in the curable composition containing 5% by weight of cyclohexanone and 15% by weight of cyclohexanone as a solvent, and including the front end ridge portion of the polyurethane substrate The part was impregnated with the curable composition (Step II). The immersion time (impregnation time) of the polyurethane substrate in the curable composition was 15 minutes, 30 minutes, and 60 minutes.

  Next, the impregnated portion of the polyurethane substrate was washed to remove the curable composition containing the (meth) acrylate compound remaining on the surface of the substrate (Step III). Furthermore, the impregnated portion including the front end ridge portion of the polyurethane substrate was irradiated with ultraviolet light of wavelength 365 nm and impregnated in the polyurethane substrate using 1.5 KW mini-grandage ECS-1511U manufactured by Eye Graphics Co., Ltd. ( By curing the meta) acrylate compound, a polyurethane elastic body including a mixed layer with a (meth) acrylate resin was formed in a portion including the tip ridge portion (Step IV).

  Martens hardness (pre-impregnated Martens hardness) of the polyurethane substrate obtained in step I, Martens hardness of a polyurethane elastic body manufactured by impregnating the curable composition in the polyurethane substrate for 15 minutes, 30 minutes, 60 minutes, and before impregnation The increase rate of Martens hardness of the polyurethane elastic body as compared is shown in Table 1.

  From the results of Table 1, polyurethane elastic bodies in which a mixed layer with a (meth) acrylate resin was formed on a polyurethane substrate having a hard segment amount of 31 to 50% by weight and a molecular weight between crosslinks of 4000 to 16000 (Examples 1 to 3) In the case of), not only the portion including the tip ridge portion but also the entire polyurethane elastic body is hardened. Therefore, it is understood that the cleaning performance is excellent.

Claims (2)

A cleaning blade comprising a polyurethane elastic body used in an image forming apparatus utilizing an electrostatic transfer process, comprising:
The polyurethane elastic body is characterized in that the hard segment amount is 31 to 50% by weight, the molecular weight between crosslinks is 4000 to 16000, and a mixed layer with (meth) acrylate resin is included in a portion including the tip ridge portion. Cleaning blade. A method of manufacturing a cleaning blade comprising a polyurethane elastic body used in an image forming apparatus utilizing an electrostatic transfer process, comprising:
Forming a polyurethane substrate having a hard segment content of 31 to 50% by weight and a molecular weight between crosslinks of 4000 to 16000,
A step II of impregnating a portion including the leading edge portion of the substrate with a curable composition containing a (meth) acrylate compound;
Cleaning at least the impregnated portion of the substrate to remove the curable composition remaining on the surface of the impregnated portion of the substrate;
Cleaning the curable composition impregnated in the base material, and forming a polyurethane elastic body including a mixed layer with a (meth) acrylate resin in a portion including a tip ridge portion; How to make a blade.