JP2004292809A - Cleaning blade member - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cleaning blade member which has an ultra-low ball drop repulsion and excellent mechanical strengths as well as a small temperature-dependence of a rubber hardness. <P>SOLUTION: The cleaning blade member for use in a cleaning part to remove the toner on a toner-sticking body, comprises the polyurethane obtained by reacting the both of the polyester polyol with a molecular weight of 1,500-3,800 which is obtained by dehydration condensation of a 6C or 9C diol and either adipic acid or sebacic acid and of a polyisocyanate, with the crosslinker containing as the main components at least one of propanediol and butanediol and at least one of trimethylolethane and trimethylolpropane and containing 25 % by weight or more of trifunctional polyol. The above polyurethane has a ball drop repulsion at 25°C (Rb<SB>T25</SB>)of 35 or less as well as has a ball drop repulsion at 50°C (Rb<SB>T50</SB>) of 60 or less, and furthermore letting the hardness Hs at 10°C and 50°C being Hs<SB>T10</SB>and Hs<SB>T50</SB>respectively, ΔHs expressed by the formula: ΔHs(°)=Hs<SB>T10</SB>-Hs<SB>T50</SB>is 3° or less. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cleaning blade member, and more particularly to a cleaning blade for removing a toner on a toner image carrier, such as a photoreceptor or a transfer belt, in which a toner image is formed in an electrophotographic method and thereafter transferring the toner image to a transfer material Regarding members.

  Generally, in an electrophotographic process, at least each of charging, exposure, development, transfer, and cleaning processes is performed on an electrophotographic photosensitive member. In such an electrophotographic process, polyurethane is used for a cleaning blade member for removing a toner on a toner image carrier that forms a toner image and thereafter transfers the toner image to a transfer material. This is because polyurethane has good abrasion resistance, has sufficient mechanical strength without adding a reinforcing agent and the like, and is non-staining.

  However, it is known that the physical properties of polyurethane have temperature dependence. The temperature dependence is particularly manifested in rebound resilience, which is a problem in cleaning. That is, when the rebound resilience decreases at a low temperature, the cleaning becomes poor, and when the rebound resilience increases at a high temperature, there is a problem of chipping or squealing of the edge.

  Therefore, a rubber member for electrophotography has been developed which has a sufficiently stable rebound resilience even when the environment changes and can be used as a high-performance cleaning blade or the like (for example, see Patent Document 1). Since the temperature inside the device is likely to increase with the recent downsizing of the device, such a reduction in the temperature dependence of the rebound resilience is increasingly demanded.

  In addition, in the case of a cleaning blade member which is also intended for an elastic body such as a transfer belt, it is deformed so as to vibrate between an elastically deformed state and an undeformed state upon contact with high resilience and cleaning. Is required to have low rebound resilience. In order to obtain such a low resilience polyurethane, there is a method in which the molecular structure is disturbed by using, for example, non-crystalline 2,4-diethyl-1,5-pentanediol as a polyol which is a raw material of the polyurethane.

  However, when polyurethane having low rebound resilience by such a method of disturbing the molecular structure is used as a cleaning blade member, the mechanical strength is insufficient.

European Patent Application Publication No. 1180731 (paragraph numbers [0008] to [0013] etc.) Japanese Patent No. 3254006 (paragraph number [0007] etc.) JP-A-8-36338 (paragraph number [0064] etc.)

  In view of such circumstances, an object of the present invention is to provide a cleaning blade member having ultra-low rebound resilience, excellent mechanical strength, and low temperature dependence of rubber hardness.

According to a first aspect of the present invention, there is provided a cleaning blade member used for a cleaning unit for removing toner on a toner adhering body, wherein the cleaning blade member includes a diol having 6 or 9 carbon atoms and adipic acid or sebacic acid. A polyester polyol having a molecular weight of 1500 to 3800 and a polyisocyanate obtained by dehydration condensation with at least one of propanediol and butanediol and at least one of trimethylolethane and trimethylolpropane as a main component, and a trifunctional polyol. A polyurethane obtained by reacting with a crosslinking agent containing not less than 25% by weight, wherein the polyurethane has a rebound resilience Rb _T25 at 25 ° C. of 35 or less and a rebound resilience Rb _{T50 at} 50 ° C. of 60 or less; 10 ° C and 50 ° C When the degrees Hs was _{Hs T10} and _{Hs T50,} respectively, [Delta] Hs represented by the following formula, it is in the cleaning blade member, characterized in that at 3 ° or less.

[Equation 1]
ΔHs (°) = Hs _T10 −Hs _T50

  According to a second aspect of the present invention, in the first aspect, ΔRb (%) which is a difference between the maximum value and the minimum value of the rebound resilience Rb (%) at 10 ° C to 50 ° C is 40 or less. The cleaning blade member is a feature.

  A third aspect of the present invention is the cleaning blade member according to the first or second aspect, wherein a main component of the polyisocyanate is diphenylmethane diisocyanate.

  A fourth aspect of the present invention is the cleaning blade member according to any one of the first to third aspects, wherein the rubber hardness is 60 to 85 ° according to JIS A.

  A fifth aspect of the present invention is the cleaning blade member according to any one of the first to fourth aspects, wherein a 100% permanent elongation is 2.4% or less.

A sixth aspect of the present invention is the cleaning blade member according to any one of the first to fifth aspects, wherein the 200% modulus is 160 kg / cm ² or more.

  According to the present invention, it is possible to provide a cleaning blade member having low rebound resilience and reduced temperature dependency of hardness while maintaining excellent characteristics such as high strength of a conventional polyurethane.

That is, in the present invention, there are various substances as raw materials for polyurethane, and various polyurethanes can be used. However, a specific combination of diols having 6 or 9 carbon atoms and adipic acid or sebacic acid is used. A polyester polyol having a molecular weight of 1500 to 3800 obtained by dehydration condensation with a dibasic acid and a polyisocyanate are prepared by mixing at least one of propanediol and butanediol and at least one of trimethylolethane and trimethylolpropane as main components and When a polyurethane obtained by reacting with a crosslinking agent containing 25% by weight or more of a functional polyol is obtained, the rebound resilience Rb _T25 at 25 ° C and low rebound resilience is 35 or less, and the rebound resilience Rb _{T50 at} 50 ° C is 60 or less, Low temperature dependence of hardness and wide Cleaning of the photoreceptor or the like in degrees region is based on the finding that it is possible. Furthermore, this polyurethane is excellent in tensile strength and tear strength, etc., and has high strength, and is composed of a conventional polyurethane obtained from a polyol or caprolactone diol obtained by dehydration condensation of a conventional diol component and adipic acid or the like. The cleaning blade member also has the characteristic of high strength.

  First, the polyester polyol used as the long-chain polyol in the present invention is obtained by dehydrating and condensing a diol having 6 or 9 carbon atoms with a dibasic acid such as adipic acid or sebacic acid. That is, a diol having 6 carbon atoms such as 1,6-hexanediol and 2-methyl-1,5-pentanediol, or a carbon number such as 1,9-nonanediol and 2-methyl-1,8-octanediol. 9 is obtained by dehydration condensation of any of the diols with any one of dibasic acids selected from adipic acid and sebacic acid. It is preferable to combine adipic acid with the diol of Formula 9.

  Here, typically, a polyol obtained by dehydrating and condensing a mixture of 1,9-nonanediol and 2-methyl-1,8-octanediol with adipic acid, 1,6-hexanediol and 2-methyl-1 A polyol obtained by dehydration-condensation of a mixture of 1,5-pentanediol and sebacic acid, a polyol obtained by dehydration-condensation of a mixture of 1,9-nonanediol and 2-methyl-1,8-octanediol and sebacic acid, Examples thereof include, but are not limited to, polyols obtained by dehydrating and condensing a mixture of 6-hexanediol and 2-methyl-1,5-pentanediol with adipic acid. In addition, although each polyol may be used alone instead of a mixture, it is preferable to use a mixture of a linear diol and a branched diol, and the mixing ratio is such that the linear is 60 to 70% by weight of the whole. It is preferable that the amount be as small as possible. It is not preferable to use a mixture of C6 and C9. This is because the mechanical properties are reduced.

  Examples of the polyisocyanate to be reacted with the polyester polyol include 2,6-toluene diisocyanate (TDI), 4,4′-diphenylmethane diisocyanate (MDI), paraphenylene diisocyanate (PPDI), 1,5-naphthalene diisocyanate (NDI), 3-dimethyldiphenyl-4,4'-diisocyanate (TODI) and the like can be mentioned. Particularly, MDI is preferable in terms of performance and cost.

  The crosslinking agent is a mixture of at least one of bifunctional propanediol (PD) and butanediol (BD) as a main component and at least one of trifunctional trimethylolethane (TME) and trimethylolpropane (TMP). The mixture preferably contains at least 25% by weight of a trifunctional polyol. This is for realizing low rebound resilience. Note that 1,3-propanediol is typical as propanediol, and 1,4-butanediol is typical as butanediol, and 1,3-propanediol and 1,4-butanediol are not suitable for performance and cost. However, the present invention is not limited to this.

  A polyurethane is produced by blending a polyisocyanate with the polyester polyol and the crosslinking agent described above and reacting them. For the reaction, a general polyurethane production method such as a prepolymer method or a one-shot method can be used. The prepolymer method is suitable for the present invention because a polyurethane having excellent strength and abrasion resistance can be obtained, but is not limited by the production method.

  In addition, in the present invention, in addition to the above-described predetermined polyester polyol, other long-chain polyols can be used in combination within a range that does not impair the effects of the present invention. It is preferably 90 to 30% by weight in the long-chain polyol.

  In the polyurethane used in the present invention, the content of the long-chain polyol in the polyurethane is preferably 60 to 80% by weight.

  When the polyurethane of the present invention is used, while maintaining the mechanical properties required as a cleaning blade member, the temperature dependence of rebound resilience and hardness becomes extremely small, and stable performance can be exhibited from low to high temperatures. It can be a cleaning blade member.

That is, the cleaning blade of the present invention has low rebound resilience and a rebound resilience Rb _T25 at 25 ° C. of 35 or less and a rebound resilience Rb _{T50 at} 50 ° C. of 60 or less. ΔRb (%), which is the difference between the maximum and minimum values of the rebound resilience Rb (%) at 10 ° C. to 50 ° C., is 40 or less. Here, the peak of rebound resilience is 10 ° C. or less.

  The cleaning blade of the present invention has a rubber hardness of 60 to 85 ° according to JIS A, but has a small temperature dependency of the hardness, and the above-mentioned ΔHs is 3 ° or less.

Further, it is preferable that the cleaning blade of the present invention has a characteristic that a 100% permanent elongation is 2.4% or less and a 200% modulus is 160 kg / cm ² or more.

  As described above, according to the present invention, it is possible to provide a high-performance cleaning blade member having low rebound resilience and having a small change in hardness due to an environment.

  Hereinafter, the present invention will be described based on examples.

(Example 1)
1,9-Nonanediol and 2-methyl-1,8-octanediol were mixed at a ratio of 65:35, and adipic acid was dehydrated and condensed to obtain a polyester polyol having a number average molecular weight of 2,000. A test sample and a cleaning blade were manufactured by using this polyester polyol, MDI, and a 1,3-propanediol / trimethylolethane mixed solution (TME: 40% by weight) as a crosslinking agent to form a thermosetting polyurethane. The polyester polyol in the polyurethane was about 65% by weight.

(Example 2)
A test sample and a cleaning blade were manufactured in the same manner as in Example 1, except that a 1,3-propanediol / trimethylolethane mixed solution (TME was 30% by weight) was used as a crosslinking agent. The polyester polyol in the polyurethane was about 65% by weight.

(Example 3)
A test sample and a cleaning blade were produced in the same manner as in Example 1, except that a 1,3-propanediol / trimethylolethane mixed solution (TME was 25% by weight) was used as a crosslinking agent. The polyester polyol in the polyurethane was about 65% by weight.

(Example 4)
1,9-nonanediol and 2-methyl-1,8-octanediol were mixed at a ratio of 15:85, and sebacic acid was dehydrated and condensed to obtain a polyester polyol having a number average molecular weight of 2,000. A test sample and a cleaning blade were produced by using this polyester polyol, MDI, and a 1,3-propanediol / trimethylolpropane mixed solution (TMP: 40% by weight) as a crosslinking agent to form a thermosetting polyurethane. The polyester polyol in the polyurethane was about 65% by weight.

(Example 5)
A test sample and a cleaning blade were produced in the same manner as in Example 4, except that a 1,3-propanediol / trimethylolpropane mixture (TMP was 30% by weight) was used as a crosslinking agent. The polyester polyol in the polyurethane was about 65% by weight.

(Example 6)
Sebacic acid was dehydrated and condensed with 1,6-hexanediol to obtain a polyester polyol having a number average molecular weight of 2,000. A test sample and a cleaning blade were manufactured by using this polyester polyol, MDI, and a 1,3-propanediol / trimethylolethane mixed solution (TME: 40% by weight) as a crosslinking agent to form a thermosetting polyurethane. The polyester polyol in the polyurethane was about 65% by weight.

(Example 7)
A test sample and a cleaning blade were produced in the same manner as in Example 6 except that a 1,3-propanediol / trimethylolethane mixed solution (TME was 30% by weight) was used as a crosslinking agent. The polyester polyol in the polyurethane was about 65% by weight.

(Comparative Example 1)
A polyester polyol having a molecular weight of 2,000 was obtained using 2,4-diethyl-1,5-pentanediol and adipic acid. Using this polyester polyol, a polyester polyol, MDI, and a 1,4-butanediol / trimethylolpropane mixed solution (TMP: 30% by weight) as a cross-linking agent are used to disturb the molecular structure to obtain low rebound resilience. A test sample and a cleaning blade were manufactured using the obtained thermosetting polyurethane. The polyester polyol in the polyurethane was about 65% by weight.

(Comparative Example 2)
A thermosetting polyurethane was prepared by using an ε-caprolactone-based polyester polyol and a mixed solution of MDI and 1,4-butanediol / trimethylolpropane (30% by weight of TMP) as a cross-linking agent. Manufactured. The polyester polyol in the polyurethane was about 65% by weight.

(Comparative Example 3)
A test sample and a cleaning blade were prepared by reacting polyhexamethylene carbonate diol as a polycarbonate diol with 1,3-propanediol / trimethylolethane mixed solution (20% by weight of TME) as an MDI and a cross-linking agent to form a polyurethane. Manufactured. The polycarbonate diol in the polyurethane was about 60% by weight.

(Comparative Example 4)
A test sample and a polyester resin were prepared in the same manner as in Example 1 except that the same polyester polyol as in Example 1 was used, and a 1,4-butanediol / trimethylolethane mixed solution (TME was 20% by weight) was used as a crosslinking agent. A cleaning blade was manufactured. The polyester polyol in the polyurethane was about 65% by weight.

(Comparative Example 5)
Adipic acid was dehydrated and condensed with 1,4-butanediol to obtain a polyester polyol having a number average molecular weight of 2,000. A test sample and a cleaning blade were produced by using this polyester polyol, MDI, and a 1,4-butanediol / trimethylolpropane mixed solution (TMP: 40% by weight) as a crosslinking agent to form a thermosetting polyurethane. The polyester polyol in the polyurethane was about 65% by weight.

(Comparative Example 6)
A test sample and a cleaning blade were produced in the same manner as in Comparative Example 5, except that a 1,4-butanediol / trimethylolpropane mixture (TMP was 30% by weight) was used as a crosslinking agent. The polyester polyol in the polyurethane was about 65% by weight.

(Comparative Example 7)
1,6-hexanediol and neopentanediol were mixed at 70:30, and adipic acid was dehydrated and condensed to obtain a polyester polyol having a number average molecular weight of 2,000. A test sample and a cleaning blade were produced by using this polyester polyol, MDI, and a 1,4-butanediol / trimethylolpropane mixed solution (TMP: 40% by weight) as a crosslinking agent to form a thermosetting polyurethane. The polyester polyol in the polyurethane was about 65% by weight.

(Comparative Example 8)
A test sample and a cleaning blade were manufactured in the same manner as in Comparative Example 7, except that a 1,4-butanediol / trimethylolpropane mixed solution (TMP was 30% by weight) was used as a crosslinking agent. The polyester polyol in the polyurethane was about 65% by weight.

(Comparative Example 9)
1,4-butanediol and ethylene glycol were mixed at a ratio of 60:40, and adipic acid was dehydrated and condensed to obtain a polyester polyol having a number average molecular weight of 2,000. A test sample and a cleaning blade were produced by using this polyester polyol, MDI, and a 1,4-butanediol / trimethylolpropane mixed solution (TMP: 40% by weight) as a crosslinking agent to form a thermosetting polyurethane. The polyester polyol in the polyurethane was about 65% by weight.

(Comparative Example 10)
A test sample and a cleaning blade were produced in the same manner as in Comparative Example 9 except that a mixed solution of 1,4-butanediol / trimethylolpropane (TMP was 30% by weight) was used as a crosslinking agent. The polyester polyol in the polyurethane was about 65% by weight.

(Test Example 1)
For each of the test samples of Examples and Comparative Examples, rebound resilience at 10 ° C. to 50 ° C. was measured to evaluate the temperature dependence. The rebound resilience (Rb) was determined by a Lupke type rebound resilience tester based on JIS K6255. Further, the rubber hardness (Hs) was measured at 10 ° C. to 50 ° C. in accordance with JIS K6253, and the temperature dependency was evaluated. Further, at 23 ° C., the Young's modulus was increased by 25% according to JIS K6254, and the tensile strength at 100% elongation (100% Modulus), the tensile strength at 200% elongation (200% Modulus), the tensile strength and the cutting strength The elongation at the time was measured according to JIS K6251, the tear strength was measured according to JIS K6252, and the 100% permanent elongation was measured according to JIS K6262. The results are shown in Tables 1 and 2, and FIG.

  Further, the cleaning blades of Examples 1 to 7 and Comparative Examples 1 to 10 were attached to a laser beam printer (LBP), and LL (10 ° C. × 30% RH), NN (23 ° C. × 55% RH), HH (30 ° C.) (80% RH) for 24 hours in each environment (seasoning), and then pass 10,000 sheets of plain paper A4 length (print output of the outer frame only) under each environment and observe the image output The cleaning performance was evaluated as ○: no stain, Δ: occasional white streak or black spot stain, ×: frequently observed white streak or black spot stain. In addition, the amount of change (wear width) in the length of the cleaning blade before and after paper passing was also determined. The results are shown in Tables 1 and 2.

  From these results, Examples 1 to 7 using a polyester polyol obtained by dehydrating and condensing a diol having 9 carbon atoms and adipic acid and using a bifunctional and trifunctional mixture crosslinking agent having a trifunctional ratio of 25% by weight or more were used. The test sample had a low rebound resilience as compared to Comparative Example 4 having a trifunctional ratio of 20% by weight and Comparative Example 2 of polycaprolactone, and achieved 35% or less at 25 ° C and 60% or less at 50 ° C. Examples 1 to 7 were also excellent in mechanical properties, and had a small temperature dependency of hardness, ΔHs of 3 ° or less. Although Comparative Example 1 using a polyol having a structure that disturbed the molecular structure had low rebound resilience, mechanical properties, particularly 200% Modulus, were small, and Comparative Example 3 using a carbonate-based polyol had a low rebound resilience. The peak was convex downward. That is, the minimum value of the rebound resilience was in a range higher than 10 ° C. Further, Comparative Examples 5 to 8, which do not have 6 or 9 carbon atoms, have low rebound resilience, but have a large temperature dependency of rebound resilience and a low modulus, so that they have a large amount of wear and cannot be used as a cleaning blade. Was. Comparative Examples 9 to 10 have low rebound resilience, but have a large temperature dependence of hardness and a large 100% permanent elongation, and therefore have a problem that environment fluctuation is large and life is short.

It is a graph which shows the temperature dependence of rebound resilience.

Claims (6)

A cleaning blade member used for a cleaning unit for removing toner on a toner adhering body, comprising a polyester polyol having a molecular weight of 1500 to 3800 obtained by dehydration condensation of a diol having 6 or 9 carbon atoms with adipic acid or sebacic acid. Obtained by reacting a polyisocyanate with a crosslinking agent containing at least one of propanediol and butanediol and at least one of trimethylolethane and trimethylolpropane as main components and containing at least 25% by weight of a trifunctional polyol. The polyurethane has a rebound resilience Rb _T25 at 25 ° C. of 35 or less and a rebound resilience Rb _{T50 at} 50 ° C. of 60 or less, and the hardness Hs at 10 ° C. and 50 ° C. of the polyurethane is Hs _T10 and Hs, respectively. _T5 A cleaning blade member characterized in that ΔHs represented by the following formula is 3 ° or less when ₀ is set.
[Equation 1]
ΔHs (°) = Hs _T10 −Hs _T50 2. The cleaning blade member according to claim 1, wherein ΔRb (%), which is a difference between the maximum value and the minimum value of the rebound resilience Rb (%) at 10 ° C. to 50 ° C., is 40 or less. 3. The cleaning blade member according to claim 1, wherein a main component of the polyisocyanate is diphenylmethane diisocyanate. The cleaning blade member according to any one of claims 1 to 3, wherein the rubber hardness is 60 to 85 in JIS A. The cleaning blade member according to any one of claims 1 to 4, wherein the 100% permanent elongation is 2.4% or less. The cleaning blade member according to any one of claims 1 to 5, wherein the 200% modulus is 160 kg / cm ² or more.

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