JP3666331B2 - Cleaning blade - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a cleaning blade for removing toner remaining on the outer peripheral surface of a photosensitive drum such as an electrophotographic copying machine.
[0002]
[Prior art]
As an electrophotographic copying machine, an electrostatic latent image is formed on the outer peripheral surface by uniformly charging the outer peripheral surface of the photosensitive drum and then exposing the outer peripheral surface via a copy image of the copy. In general, the electrostatic latent image is of a type in which a charged toner is attached to form a toner image and transferred to a copy paper to copy.
[0003]
In such an electrophotographic copying machine, after the toner image is transferred, the toner remains on the outer peripheral surface of the photosensitive drum, so that it is supported on the outer peripheral surface of the photosensitive drum by, for example, a plate-like holder 22 as shown in FIG. A cleaning blade 21 is slidably contacted, and residual toner is scraped off and removed.
[0004]
As the elastic body used for the cleaning blade 21, a polyurethane resin excellent in mechanical properties such as abrasion resistance is used. However, when such a cleaning blade 21 made of polyurethane resin is used for a long period of time, the edge portion of the cleaning blade 21 that comes into sliding contact with the photosensitive drum is worn, and the residual toner cannot be removed satisfactorily. There is.
[0005]
Therefore, in order to improve the wear resistance of the cleaning blade 21, various attempts have been made as a method for reducing the friction of the polyurethane resin surface. For example, a method of coating the surface of a polyurethane resin (JP-A-4-260084, JP-A-4-212190, etc.), or a method of dispersing a lubricant in the polyurethane resin (JP-A-7-306616, JP-A-Hei. No. 5-158389, JP-A-5-173464, etc.).
[0006]
[Problems to be solved by the invention]
However, the method of coating the surface of the polyurethane resin is effective in reducing the initial friction, but the edge of the cleaning blade that is in sliding contact with the photosensitive drum may be worn or chipped if used for a long time. For this reason, there is a problem that excellent edge accuracy cannot be obtained over a long period of time and cleaning failure occurs. Moreover, the method of dispersing the lubricant requires a new process such as a process of uniformly dispersing and mixing the lubricant inside the polyurethane resin, and thus cannot improve the production efficiency. is there. Further, at this time, when the solid lubricant is dispersed, there is a problem that the viscosity of the polyurethane composition for forming the cleaning blade is increased, and the processability is deteriorated. On the other hand, when the liquid lubricant is dispersed, there is a problem in that the image is adversely affected by bleeding out of the liquid lubricant.
[0007]
The present invention has been made in view of such circumstances, and an object thereof is to provide a cleaning blade having excellent wear resistance and chipping resistance.
[0008]
[Means for Solving the Problems]
To achieve the above object, the cleaning blade of the present invention takes a polyisocyanate, a polyol, a structure that consists of the cured product of the polyurethane composition containing a diamino compound you express by the following structural formula (1) .
[0009]
[Chemical formula 2]
[0010]
The inventors of the present invention have made extensive studies in order to obtain a cleaning blade having excellent wear resistance and chipping resistance. As a result, conventionally, a polyurethane was produced by a curing (crosslinking) reaction between an isocyanate and an OH group. As a result, the specific diamino compound (2,2 ′, 3,3′-tetrachloro- 4,4′- By using this diamino compound (2,2 ', 3,3'-tetrachloro-4,4'-diaminodiphenylmethane ) in combination with diaminodiphenylmethane) to form a polyurethaneurea structure, elasticity is achieved. The inventors have found that the hardness and hardness are in an appropriate range, and that wear and chipping of the edge of the cleaning blade are less likely to occur particularly at high temperatures, and the present invention has been achieved.
[0011]
When the content of the diamino compound (2,2 ′, 3,3′-tetrachloro-4,4′-diaminodiphenylmethane) is set within a specific range, the good low temperature cleaning property is maintained. In addition, wear resistance and chipping resistance at high temperatures are improved.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Next, an embodiment of the present invention will be described.
[0013]
For example, as shown in FIG. 1, the cleaning blade of the present invention comprises a polyurethane composition cured body 1, is supported by a plate-like holder 2, and is used for the use.
[0014]
As the material for forming the polyurethane composition cured body 1, a polyisocyanate, a polyol and a polyurethane composition containing represented Ru diamino compound by the following structural formula (1) is used.
[0015]
[Chemical 3]
[0016]
The polyisocyanate is not particularly limited. For example, 4,4′-diphenylmethane diisocyanate (MDI), 2,4-tolylene diisocyanate (2,4-TDI), 2,6-tolylene diisocyanate (2 , 6-TDI), 3,3′-vitrylene-4,4′-diisocyanate, 3,3′-dimethyldiphenylmethane-4,4′-diisocyanate, 2,4-tolylene diisocyanate uretidinedione (2,4- TDI dimer), 1,5-naphthylene diisocyanate, metaphenylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, 4,4'-dicyclohexylmethane diisocyanate (hydrogenated MDI), carbodiimide-modified MDI, orthotoluidine diisocyanate, Examples thereof include diisocyanates such as silylene diisocyanate, paraphenylene diisocyanate and lysine diisocyanate methyl ester, triisocyanates such as triphenylmethane-4,4 ′, 4 ″ -triisocyanate, and polymeric MDI. These may be used alone or in combination of two or more. Among these polyisocyanates, MDI is preferably used from the viewpoint of wear resistance.
[0017]
The polyol used together with the polyisocyanate is not particularly limited, and examples thereof include polyester polyols such as polyester diol and polyester triol, polyether polyols such as polycaprolactone, polycarbonate, polyoxytetramethylene glycol, and polyoxypropylene glycol. Can be given. These may be used alone or in combination of two or more.
[0018]
As the polyester polyol, a hydroxyl polyester polyol produced from a polybasic organic acid and a polyol and having a hydroxyl group as a terminal group is preferably used. Examples of the polybasic organic acids include saturated fatty acids such as oxalic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, isosebacic acid, maleic acid, fumaric acid and the like. Obtained by dimerization of saturated fatty acids, dicarboxylic acids such as aromatic acids such as phthalic acid, isophthalic acid, and terephthalic acid, acid anhydrides such as maleic anhydride and phthalic anhydride, dialkyl esters such as dimethyl terephthalate, and unsaturated fatty acids. And dimer acid. Examples of the polyol used together with the polybasic organic acid include diols such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, butylene glycol, neopentyl glycol, 1,6-hexylene glycol, Examples include triols such as methylolethane, trimethylolpropane, hexanetriol, and glycerin, and hexaols such as sorbitol.
[0019]
Moreover, as said polyether polyol, what is manufactured by ring-opening polymerization or copolymerization of cyclic ether is used suitably. Examples of the cyclic ether include ethylene oxide, propylene oxide, trimethylene oxide, butylene oxide, α-methyltrimethylene oxide, 3,3′-dimethyltrimethylene oxide, tetrahydrofuran, dioxane, dioxamine and the like.
[0020]
And in this invention, as a polyol used with the said polyisocyanate, a polybutylene adipate (PBA) is used suitably from a viewpoint of abrasion resistance among said series.
[0021]
The number average molecular weight (Mn) of the polyol used with the polyisocyanate is preferably in the range of 1500 to 3000, particularly preferably 1500 to 2500. That is, if the Mn of the polyol is less than 1500, the properties of the resulting cleaning blade tend to be reduced, and conversely if the Mn exceeds 3000, the workability tends to deteriorate.
[0022]
As the specific diamino compound used together with the polyisocyanate and the polyol, 2,2 ′, 3,3′-tetrachloro-4,4′-diaminodiphenylmethane represented by the following structural formula (1) is used. .
[0023]
[Formula 4]
[0024]
The content of the specific diamino compound (2,2 ′, 3,3′-tetrachloro-4,4′-diaminodiphenylmethane) is preferably set in the range of 1 to 10% by weight of the entire polyurethane composition. Particularly preferably, it is 3 to 7% by weight. That is, if the content of the specific diamino compound is less than 1% by weight, a sufficient effect due to the diamino compound cannot be obtained. Conversely, if the content exceeds 10% by weight, the tan δ peak temperature rises and cleaning at a low temperature is performed. This is because the tendency to be inferior is seen.
[0025]
The polyurethane composition used as the material for forming the cured polyurethane composition 1 includes polyisocyanate, polyol, and a specific diamino compound (2,2 ′, 3,3′-tetrachloro-4,4′-diaminodiphenylmethane. In addition, a chain extender, a catalyst, a foaming agent, a surfactant, a flame retardant, a colorant, a filler, a plasticizer, a stabilizer, a release agent, and the like can be appropriately mixed and used.
[0026]
Examples of the chain extender include 1,4-butanediol (1,4-BD), ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, hexanediol, 1,4-cyclohexanediol, and 1,4-cyclohexane. Examples include polyols having a molecular weight of 300 or less, such as dimethanol, xylene glycol, triethylene glycol, trimethylolpropane (TMP), glycerin, pentaerythritol, sorbitol, and 1,2,6-hexanetriol. These may be used alone or in combination of two or more.
[0027]
Examples of the catalyst include amine compounds such as tertiary amines and organometallic compounds such as organotin compounds. Of these, amine compounds are preferably used.
[0028]
Examples of the tertiary amine include trialkylamines such as triethylamine; tetraalkyldiamines such as N, N, N ′, N′-tetramethyl-1,3-butanediamine; aminoalcohols such as dimethylethanolamine; Ethoxylated amines; Ethoxylated diamines; Ester amines such as bis (diethylethanolamine) adipate; Triethylenediamine; Cyclohexylamine derivatives such as N, N-dimethylcyclohexylamine; N-methylmorpholine, N- (2-hydroxypropyl)- Morpholine derivatives such as dimethylmorpholine; piperazine derivatives such as N, N′-diethyl-2-methylpiperazine, N, N′-bis- (2-hydroxypropyl) -2-methylpiperazine, and the like.
[0029]
Examples of the organic tin compound include dialkyltin compounds such as dibutyltin dilaurate and dibutyltin di (2-ethylhexoate), stannous 2-ethylcaproate, stannous oleate, and the like.
[0030]
In the present invention, the mixing ratio (molar ratio) of the diol such as 1,4-butanediol and the specific diamino compound is set in the range of diol / diamino compound = 95/5 to 40/60. The diol / diamino compound is preferably 80/20 to 50/50. That is, when the molar ratio of the diamino compound is less than 5, sufficient effects due to the diamino compound cannot be obtained. Conversely, when the molar ratio of the diamino compound exceeds 60, the tan δ peak temperature rises and cleaning at a low temperature is performed. This is because the tendency to be inferior is seen.
[0031]
The cleaning blade of the present invention can be produced according to a conventional method using each of the above materials. Specifically, it can be produced according to a prepolymer method, a semi one-shot method, or a one-shot method. Of these, the semi-one shot method is preferably used from the viewpoint of excellent workability.
[0032]
In accordance with the semi-one shot method, the cleaning blade of the present invention is manufactured, for example, as follows. That is, first, the above polyisocyanate and polyol are prepared, both are mixed in an appropriate mixing ratio, and reacted under appropriate reaction conditions to prepare a urethane prepolymer (main agent liquid). On the other hand, the above polyol and a specific diamino compound, if necessary, a chain extender, a catalyst, and the like are prepared, blended at an appropriate blending ratio, and mixed under an appropriate mixing condition to prepare a curing agent solution. Next, the main agent liquid and the curing agent liquid are blended and mixed at an appropriate blending ratio, and the mixed liquid is injected into a cleaning blade molding die on which the plate-like holder 2 is held to react and cure. Let And the obtained hardening body is taken out from a shaping | molding die, and is processed into a defined shape. In this way, a cleaning blade integrally formed with the plate-like holder 2 as shown in FIG. 1 can be obtained.
[0033]
In the cleaning blade thus obtained, the tan δ peak temperature in the cured body is preferably 10 ° C. or less, and particularly preferably in the range of 1.0 to 10 ° C. That is, when the tan δ peak temperature exceeds 10 ° C., the low temperature cleaning property tends to deteriorate. The tan δ peak temperature is one of dynamic viscoelastic characteristics, and is a temperature at which the maximum (peak) of tan δ (loss tangent) measured by a dynamic viscoelasticity measuring instrument is reached.
[0034]
As shown in FIG. 1, the cleaning blade of the present invention is not necessarily formed integrally with the plate-like holder 2, and may be adhered to the surface of the plate-like holder 2 later, for example. .
[0035]
Next, examples will be described together with comparative examples.
[0036]
[Example 1]
[Preparation of main agent liquid (urethane prepolymer)]
MDI (manufactured by Nippon Polyurethane Industry Co., Ltd., Millionate MT) was used for 48 parts by weight (hereinafter referred to as “part”) of PBA (N4010, Mn: 2000 manufactured by Nippon Polyurethane Industry Co., Ltd.) that had been degassed in vacuo at 80 ° C. ) 52 parts were added and reacted at 80 ° C. for 3 hours under a nitrogen atmosphere to obtain a main agent liquid (urethane prepolymer having an NCO group at the terminal).
[0037]
(Preparation of curing agent solution)
First, 2,2 ′, 3,3′-tetrachloro-4 represented by the above formula (1) as a specific diamino compound with respect to 85 parts of PBA (N4010 manufactured by Nippon Polyurethane Industry Co., Ltd., Mn: 2000), 43.1-Diaminodiphenylmethane (13.1 parts) was added, and the mixture was heated at 150 ° C. for 1 hour under a nitrogen atmosphere to dissolve the diamino compound in PBA. Subsequently, 3.5 parts of 1,4-butanediol (1,4-BD), 4 parts of trimethylolpropane (TMP), and triethylenediamine (manufactured by Sankyo Air Products Co., Ltd., DABCO) as a catalyst were added to this dissolved product. Blended so that the concentration in the cured product is 100 ppm, mixed under nitrogen atmosphere at 80 ° C. for 1 hour, then vacuum degassed and dehydrated at 80 ° C. for 1 hour, so that an OH group is added to the terminal The hardening | curing agent liquid which has was prepared.
[0038]
[Production of cleaning blade]
First, a cleaning blade molding die was prepared, a plate-like holder was placed at a predetermined position of the die, and preheated to 140 ° C. Next, the above main agent liquid (liquid temperature: 70 ° C.) and curing agent liquid (liquid temperature: 70 ° C.) were blended at a weight ratio of 100: 105.6, and mixed with a stirring blade for 30 seconds while being vacuum degassed. Then, it was poured into the mold and cured by reacting at 140 ° C. for 30 minutes to obtain a cured product. Thereafter, the mold was removed and formed into a predetermined shape using a knife to obtain the intended cleaning blade.
[0039]
[Example 2]
A base solution was prepared in the same manner as in Example 1 except that PBA was changed to 43 parts and MDI was changed to 57 parts. A curing agent solution was prepared in the same manner as in Example 1, except that PBA was changed to 87 parts, diamino compound was changed to 6.7 parts, and 1,4-BD was changed to 7.2 parts. Then, a cleaning blade was prepared in the same manner as in Example 1 using these main agent liquid and curing agent liquid. In addition, the compounding ratio of the main agent liquid and the curing agent liquid was a main agent liquid: curing agent liquid = 100: 104.9 in weight ratio.
[0040]
[Example 3]
A main agent solution was prepared in the same manner as in Example 1 except that PBA was changed to 41 parts and MDI was changed to 59 parts. The curing agent was the same as in Example 1 except that PBA was changed to 84 parts, diamino compound was changed to 1.9 parts, 1,4-BD was changed to 9.6 parts, and TMP was changed to 4.3 parts. A liquid was prepared. Then, a cleaning blade was prepared in the same manner as in Example 1 using these main agent liquid and curing agent liquid. In addition, the compounding ratio of the main agent liquid and the curing agent liquid was a main agent liquid: curing agent liquid = 100: 99.8 in weight ratio.
[0041]
[Example 4]
A base solution was prepared in the same manner as in Example 1 except that PBA was changed to 43 parts and MDI was changed to 57 parts. The curing agent was the same as in Example 1 except that PBA was changed to 83 parts, diamino compound to 23.3 parts, 1,4-BD to 4.2 parts, and TMP to 2.6 parts. A liquid was prepared. Then, a cleaning blade was prepared in the same manner as in Example 1 using these main agent liquid and curing agent liquid. In addition, the compounding ratio of the main agent liquid and the curing agent liquid was a main agent liquid: curing agent liquid = 100: 113.1 in weight ratio.
[0042]
[Comparative Example 1]
A curing agent solution was prepared in the same manner as in Example 1 except that the diamino compound was not blended and the amount of 1,4-BD was increased to 7 parts instead. And using this hardening | curing agent liquid, it carried out similarly to Example 1, and produced the cleaning blade. In addition, the compounding ratio of the main agent liquid and the curing agent liquid was a main agent liquid: curing agent liquid = 100: 96 in a weight ratio.
[0043]
[Comparative Example 2]
A curing agent solution was prepared in the same manner as in Example 2 except that the diamino compound was not blended and the amount of 1,4-BD was increased to 9 parts instead. And using this hardening | curing agent liquid, it carried out similarly to Example 2, and produced the cleaning blade. In addition, the compounding ratio of the main agent liquid and the curing agent liquid was a main agent liquid: curing agent liquid = 100: 100 in a weight ratio.
[0044]
Using the cleaning blades of the example product and the comparative product obtained in this way, each characteristic was evaluated according to the following criteria. These results are also shown in Table 1 below.
[0045]
[High temperature and high humidity (H / H) environment]
(Image evaluation)
Each cleaning blade was incorporated into a commercially available laser printer (LBP), and initial and 30,000 images were printed in A3 size in an H / H environment (35 ° C. × 85% RH). Then, a case where there was no problem in the image and a fine line could be clearly imaged was evaluated as a case where a large number of o, fogging, white spots, etc. occurred and there were practical problems.
[0046]
(Abrasion amount)
The amount of wear at the edge of the cleaning blade after the above 30,000 images were printed was observed at a magnification of 2000 using a scanning electron microscope. Then, the cross-sectional area (U μm ² ) of the worn portion and the unit length (V μm) of the edge portion were measured, and the wear amount (W μm ³ ) was calculated from W = U × V. In addition, it can be said that it is excellent in abrasion resistance, so that this amount of wear is small.
[0047]
(Chip resistance)
The presence or absence of chipping on the edge of the cleaning blade after the above 30,000 images were printed was observed with a microscope at a magnification of 500 times. Then, the case where there was no chip was evaluated as ◯, and the case where there was a chip was evaluated as x.
[0048]
[Low temperature and low humidity (L / L) environment]
(Image evaluation)
Each cleaning blade was incorporated into a commercially available laser printer (LBP), and 6000 sheets were printed in A3 size in an L / L environment (15 ° C. × 10% RH). And, when there is no problem in the image and fine lines can be clearly drawn, ○, fogging, white spots, etc. occur slightly, but when there is no practical problem, Δ, fogging, white spots, etc. occur in large quantities. Then, those having practical problems were evaluated as x.
[0049]
[Tan δ peak temperature]
Each cleaning blade was molded and measured to 1.5 mm × 1.5 mm × 30.0 mm to prepare a sample. This sample was set on a DVE rheospectr made by Rheology so that the gap between the chucks of the tension jig was 20.0 mm, a sine wave distortion with a displacement amplitude of ± 10 μm and a frequency of 10 Hz was applied, and −20 ° C. to 50 ° C. Tan δ (loss tangent) in the range of ° C. was measured every 1 ° C. at a temperature rising rate of 3 ° C./min. The temperature at which the value of tan δ was maximum (peak) was defined as the tan δ peak temperature.
[0050]
[Table 1]
[0051]
From the results in Table 1 above, all of the examples have good images after printing 30,000 sheets under H / H environment, and the wear amount after printing 30,000 sheets is small and chipping occurs. It was confirmed that they did not.
[0052]
On the other hand, it can be seen that all the comparative products are remarkably inferior in the image after 30,000 sheets are printed in the H / H environment. When the amount of wear after chipping 30,000 sheets and the state of chipping were observed, the amount of wear was large and it was confirmed that chipping occurred.
[0053]
【The invention's effect】
As described above, the cleaning blade of the present invention has a polyurethane urea structure formed by curing using a specific diamino compound (2,2 ′, 3,3′-tetrachloro-4,4′-diaminodiphenylmethane). Therefore, the elasticity and hardness are within the appropriate ranges. As a result, wear and chipping of the edge portion of the cleaning blade are unlikely to occur particularly at high temperatures, and thus excellent wear resistance and chipping resistance are provided. In addition, since the dent centering on the central portion in the length direction of the cleaning blade is eliminated and the ears at both ends are eliminated, the dimensional accuracy is improved. Therefore, when the durability test is performed with the cleaning blade of the present invention incorporated in an actual machine, an excellent image can be obtained.
[0054]
When the content of the diamino compound (2,2 ′, 3,3′-tetrachloro-4,4′-diaminodiphenylmethane) is set within a specific range, good low temperature cleaning property is maintained. In addition, wear resistance and chipping resistance at high temperatures are improved.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view showing an example of a cleaning blade of the present invention.
FIG. 2 is a partially broken configuration diagram showing an example of a conventional cleaning blade.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Polyurethane composition hardening body 2 Plate-shaped holder

Claims (2)

A cleaning blade, wherein the polyisocyanate, a polyol, that a cured body of a polyurethane composition containing a diamino compound you express by the following structural formula (1).
  The cleaning blade according to claim 1, wherein the content of the diamino compound is set in a range of 1 to 10% by weight of the entire polyurethane composition.