Patent Application
20080027184
The present invention will next be described in detail by way of examples.
Caprolactone (PCL) (molecular weight: 2,000) (100 parts (unless otherwise specified, the unit “part(s)” is on the basis weight)) and 3,3-dimethylphenyl-4,4-diisocyanate (TODI) (35 parts) were mixed. 3,5-Dimethylthio-2,4-toluenediamine (DMTDA) and trimethylolpropane (TMP), serving as cross-linking agents, were added to the mixture such that the α value and tri-functional cross-linking agent content (molar ratio) of the cross-linking agent were adjusted to 0.95 and 0.2, respectively. The mixture was allowed to react, to thereby form a polyurethane. The formed polyurethane solid was cut to provide test samples and test cleaning blades of Example 1.
Caprolactone (PCL) (molecular weight: 2,000) (100 parts) and the mixture of MDI and TODI (0.4:0.6 in a weight ratio) (40 parts) were mixed. 3,5-Dimethylthio-2,4-toluenediamine (DMTDA) and TMP, serving as cross-linking agents, were added to the mixture such that the α value and tri-functional cross-linking agent content (molar ratio) of the cross-linking agent were adjusted to 0.95 and 0.4, respectively. The mixture was allowed to react, to thereby form a polyurethane. The formed polyurethane solid was cut to provide test samples and cleaning blades of Example 2.
The procedure of Example 2 was repeated, except that the mixture of MDI and TODI (0.5:0.5 in a weight ratio) (35 parts) were used, and 3,5-dimethylthio-2,4-toluenediamine (DMTDA) and TMP, serving as cross-linking agents, were added to the mixture such that the α value and tri-functional cross-linking agent content (molar ratio) of the cross-linking agent were adjusted to 0.95 and 0.2, respectively, to thereby provide test samples and test cleaning blades of Example 3.
The procedure of Example 2 was repeated, except that the mixture of MDI and TODI (0.7:0.3 in a weight ratio) (35 parts) were used, and 3,5-dimethylthio-2,4-toluenediamine and TMP, serving as cross-linking agents, were added to the mixture such that the α value and tri-functional cross-linking agent content (molar ratio) of the cross-linking agent were adjusted to 0.95 and 0.2, respectively, to thereby provide test samples and test cleaning blades of Example 4.
The procedure of Example 2 was repeated, except that the mixture of MDI and TODI (0.8:0.2 in a weight ratio) (35 parts) were used, and 3,5-dimethylthio-2,4-toluenediamine (DMTDA) and TMP, serving as cross-linking agents, were added to the mixture such that the α value and tri-functional cross-linking agent content (molar ratio) of the cross-linking agent were adjusted to 0.95 and 0.2, respectively, to thereby provide test samples and test cleaning blades of Comparative Example 1.
The procedure of Example 1 was repeated, except that MDI (35 parts) was used instead of TODI, and 3,5-dimethylthio-2,4-toluenediamine (DMTDA) and TMP, serving as cross-linking agents, were added to the mixture such that the α value and tri-functional cross-linking agent content (molar ratio) of the cross-linking agent were adjusted to 0.95 and 0.2, respectively, to thereby provide test samples and test cleaning blades of Comparative Example 2.
The procedure of Example 2 was repeated, except that the mixture of MDI and TODI (0.5:0.5 in a weight ratio) (50 parts) were used, and butanediol (BD) and TMP, serving as cross-linking agents, were added to the mixture such that the α value and tri-functional cross-linking agent content (molar ratio) of the cross-linking agent were adjusted to 0.95 and 0.2, respectively, to thereby provide test samples and test cleaning blades of Comparative Example 3.
The procedure of Example 1 was repeated, except that MDI (60 parts) was used instead of TODI, and BD and TMP, serving as cross-linking agents, were added to the mixture such that the α value and tri-functional cross-linking agent content (molar ratio) of the cross-linking agent were adjusted to 0.95 and 0.2, respectively, to thereby provide test samples and test cleaning blades of Comparative Example 4.
The procedure of Example 1 was repeated, except that MDI (40 parts) was used instead of TODI, and BD and TMP, serving as cross-linking agents, were added to the mixture such that the α value and tri-functional cross-linking agent content (molar ratio) of the cross-linking agent were adjusted to 0.95 and 0.3, respectively, to thereby provide test samples and test cleaning blades of Comparative Example 5.
The procedure of Example 1 was repeated, except that MDI (50 parts) was used instead of TODI, and BD and TMP, serving as cross-linking agents, were added to the mixture such that the α value and tri-functional cross-linking agent content (molar ratio) of the cross-linking agent were adjusted to 0.95 and 0.4, respectively, to thereby provide test samples and test cleaning blades of Comparative Example 6.
The test samples of the Examples and the Comparative Examples were evaluated in terms of raw material moldability and surface state. The term “surface state” refers to the surface state of a test sample and was evaluated with the ratings “◯” (surface state without any problem) and “X” (problematic surface state). The “raw material moldability” was evaluated with the ratings “◯” (no problem during molding) and “X” (problems during molding).
The physical properties of the test samples of Examples 1 to 4 and Comparative Examples 4 to 6 were determined as follows. Rubber hardness (JIS A) at 25° C. was determined in accordance with JIS K6301. Tensile strength at 100% elongation (100% modulus), tensile strength at 200% elongation (200% modulus), and tensile strength at 300% elongation (300% modulus) were determined in accordance with JIS K6251. Tensile strength and elongation at break were determined in accordance with JIS K6251. Tear strength was determined in accordance with JIS K6252. Young's modulus (25% elongation) was determined in accordance with JIS K6254. Rebound resilience (Rb) at 25° C. was determined by means of a Lubke pendulum rebound resilience tester in accordance with JIS K6301. Rebound resilience (Rb) was determined also at 10° C. to 50° C., whereby temperature dependency thereof was evaluated. Peak temperature of tan δ (1 Hz) was determined by means of a thermal analyzer, EXSTAR 6000DMS viscoelastic spectrometer (product of Seiko Instruments Inc.). The results are shown in Table 1.
All the test samples of Examples 1 to 4 exhibited excellent raw material moldability and surface state, a hardness (JIS A) of 90° or higher, and a rebound resilience of 41% or higher. Consequently, the cleaning blade members falling within the scope of the present invention have high hardness and exhibit high rebound resilience.
In addition all the test samples also exhibited large 100% modulus, 200% modulus, and 300% modulus; an elongation at break of 300% or higher; a high tear strength, and other excellent mechanical strength values. The test samples exhibited considerably small variation in rebound resilience with temperature, and a tan δ (1 Hz) peak temperature of 10° C. or lower. Consequently, the cleaning blade members falling within the scope of the present invention exhibit excellent mechanical characteristics and maintain reliable performance against changes in the environment.
In contrast, in Comparative Examples 1 and 2, a polyurethane composition containing no TODI or containing TODI in an amount lower than the above-specified amount was allowed to react. Therefore, the composition was foamed possible due to excessively high reaction rate, and test samples could not be formed. In Comparative Example 3, although a polyurethane composition containing TODI but no diamino compound could be molded without any problem, spherulites were observed on a surface of a test sample formed through molding.
In Comparative Examples 4 to 6, although polyurethane compositions containing no TODI nor a diamino compound could be molded without any problem and provided test samples each having no surface problem, the produced test samples were unsatisfactory in terms of mechanical strength such as elongation at break or tensile strength, rebound resilience, and tan δ peak temperature. Furthermore, variation in rebound resilience with temperature was large.
Each of the cleaning blades of Examples 1 to 4 and Comparative Examples 3 to 6 was adapted in an actual apparatus (product of Fuji Xerox, Docu Center color 400) and pressed against a photoconductor, and the photoconductor was continuously rotated at a circumferential speed of 125 mm/sec for 60 minutes under LL conditions (10° C., 35%), NN conditions (23° C., 55%), or HH conditions (30° C., 85%), while no paper sheet was conveyed. After completion of the operation, the wear condition of an edge portion of the cleaning blade under HH conditions was observed under a laser microscope, and the amount of wear was microscopically determined. The wear was evaluated by average cross-section area of wear portions in accordance with the following ratings: ◯ (<10 μm2), Δ (10 to 20 μm2), and X (≧20 μm2). Generation of squeaky sounds was aurally checked and was evaluated in accordance with the following ratings: ◯ (no squeaky sounds generated) and X (squeaky sounds generated). Each cleaning blade was evaluated in terms of performance of cleaning a photoreceptor with the following ratings: ◯ (excellent cleaning performance) and X (cleaning incomplete). The above tests were performed under the following conditions, and the results are shown in Table 2.
Microscope: VK-9500 (KEYENCE Corporation), magnification: ×50
Mode: Ultra-depth color profiling
Optical zoom: ×1.0
Measurement pitch: 0.10 μm
Measurement points: 5 points per cleaning blade (i.e., points 20 mm from the respective ends, points 80 mm from the respective ends, and the center point)
Under all tested conditions, the cleaning blade members of Examples 1 to 4 did not generate squeaky sound and exhibited excellent wear resistance and cleaning performance.
In contrast, the cleaning blade member of Comparative Example 4 exhibited poor wear resistance under all tested conditions, possibly due to an elongation at break of 300% or less, and no cleaning performance under the LL and HH conditions. The cleaning blade member of Comparative Example 5, which exhibited large variation in rebound resilience with temperature, failed to exhibit cleaning performance under the LL conditions, and generated squeaky sounds and exhibited poor wear resistance and no cleaning performance under the HH conditions. The cleaning blade member of Comparative Example 6, which exhibited a high tan δ (1 Hz) peak temperature, failed to exhibit cleaning performance under the LL conditions, and generated squeaky sounds and exhibited poor wear resistance and no cleaning performance under the HH conditions.
The tests carried out hereinabove have revealed that the cleaning blade member of the present invention exhibits excellent wear resistance and can be suitably employed under any conditions without performance variation with temperature.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2006-205367 | Jul 2006 | JP | national |
| 2007-187482 | Jul 2007 | JP | national |
