JP4420322B2 - Cleaning blade member - Google Patents

Description

  The present invention relates to a cleaning blade member, and in particular, cleaning that removes toner on a toner image carrier that forms a toner image such as a photoreceptor or a transfer belt in electrophotography and then transfers the toner image to a transfer material. The present invention relates to a blade member.

  In general, in an electrophotographic process, a cleaning blade for removing toner is used to repeatedly use an electrophotographic photosensitive member or a transfer belt, and polyurethane is used for the cleaning blade member. This is because polyurethane has good abrasion resistance, has sufficient mechanical strength without adding a reinforcing agent, and is non-staining.

  However, it is known that the physical properties of polyurethane have temperature dependence. The temperature dependence appears particularly in the resilience and is a problem in cleaning. That is, when the impact resilience is lowered at a low temperature, a cleaning failure is caused.

  Thus, an electrophotographic rubber member has been developed that has sufficiently stable rebound resilience even when the environment changes and can be used as a highly functional cleaning blade (see, for example, Patent Document 1). Since the temperature inside the device is likely to rise as the device becomes more compact in recent years, there is an increasing demand for reducing the temperature dependence of the resilience.

  In addition, since the high resilience is deformed and cleaned so as to vibrate between the elastically deformed state by contact and the undeformed state, particularly when the cleaning blade member is also intended for an elastic body such as a transfer belt. Is required to have low impact 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, amorphous 2,4-diethyl-1,5-pentanediol as a polyol which is a raw material of the polyurethane.

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

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

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

  In addition, the polyurethane disk used for the false twisting unit of the drawing false twisting machine which consists of the polyurethane rubber prepared from the polyol which has polycarbonate polyol as a main component is invented (refer patent document 2). However, it is a resin or polyurethane close to resin, and has insufficient physical properties as an elastic body that can be used as a cleaning blade member. Further, a thermoplastic cleaning blade based on polycarbonate diol has been invented (see Patent Document 3). However, since it is not three-dimensionally crosslinked, it is considered that the properties such as creep and stress relaxation are inferior.

According to a first aspect of the present invention for solving the above problems, in a cleaning blade member used in a cleaning unit for removing attached toner, a polycarbonate diol having at least one selected from nonanediol and methyloctanediol as a base diol, The polyurethane is formed using a polyisocyanate and a crosslinking agent containing a short-chain diol and a short-chain triol, and the polyurethane has a 100% permanent elongation of 3% or less, a 200% modulus of 90 kg / cm ² or more, ΔRb represented by the following formula when the tear strength is 60 kg / cm or more and the rebound resilience Rb _T25 at 25 ° C. is 30% or less, and the rebound resilience Rb at 10 ° C. and 50 ° C. is Rb _T10 and Rb _T50 , respectively. For cleaning blade member characterized by being 40% or less That.

[Equation 1]
ΔRb (%) = Rb _T50 −Rb _T10

  According to a second aspect of the present invention, in the first aspect, the crosslinking agent mainly comprises at least one short-chain diol of propanediol and butanediol and at least one short-chain triol of trimethylolethane and trimethylolpropane. The cleaning blade member is characterized by being a component.

  According to a third aspect of the present invention, in the first or second aspect, the polycarbonate diol blended with nonanediol: methyloctanediol = 65: 35 to 15:85 (weight ratio) is used as a base diol. A cleaning blade member characterized by

  According to a fourth aspect of the present invention, in any one of the first to third aspects, the polycarbonate diol uses 1,9-nonanediol and 2-methyl-1,8-octanediol as a base diol. In the cleaning blade member.

  According to the present invention, it is possible to provide a cleaning blade member having high strength and extremely low resilience. Moreover, since polycarbonate diol is used, it is a cleaning blade excellent in heat resistance.

  The present invention realizes a cleaning blade member having high strength and low rebound resilience by using polyurethane using a highly crystalline polycarbonate diol.

That is, the present invention relates to a polyurethane formed by using a polycarbonate diol having at least one selected from nonanediol and methyloctanediol as a base diol, a polyisocyanate, and a crosslinking agent containing a short-chain diol and a short-chain triol. Then, 100% permanent elongation is 3% or less, 200% modulus is 90 kg / cm ² or more, tear strength is 60 kg / cm or more, rebound resilience Rb _T25 at 25 ° C. is 30% or less, 10 ° C. and 50 ° C. Based on the knowledge that ΔRb represented by the above formula when the rebound resilience Rb is Rb _T10 and Rb _T50 , respectively, is 40% or less and can be suitably used for a cleaning blade member. Since the tear strength is as high as 60 kg / cm or more, the cleaning blade member is excellent in wear resistance. The tensile strength can be 300 kg / cm ² or more.

  Unlike polyurethane made from polyester polyol or caprolactone polyester polyol obtained by reacting adipic acid and diol component, the cleaning blade member of the present invention has rubber properties such as 100% permanent elongation and 200% modulus even at high temperatures. The cleaning blade member of the present invention can be suitably used in a wide temperature range because it is maintained and the temperature dependence of the impact resilience is low. Furthermore, since it is a polycarbonate diol having at least one selected from nonanediol and methyloctanediol as a base diol, the resilience does not have a minimum value between 10 and 50 ° C., that is, has no glass transition point. The rubber characteristics can be maintained even at a low temperature, and it can be used favorably as a cleaning blade for a long time even at a low temperature. Further, since it has ultra-low resilience, it is deformed so as to remove toner while being in sliding contact with the object to be cleaned in a deformed state of the cleaning blade, and thus is particularly suitable as a cleaning blade member for an elastic body such as a transfer belt. Can be used.

  First, in the present invention, polycarbonate diol is used as the long-chain polyol. The polycarbonate diol can be obtained by reacting a diol component with a dialkyl carbonate. In the present invention, the diol component (base diol) is at least one selected from nonanediol (ND) and methyloctanediol (MOD). Use. When both nonanediol and methyloctanediol are used, it is preferably used in a weight ratio of 65:35 to 15:85. Further, in order to make the cleaning property at a low temperature particularly good, it is preferable to use 1,9-nonanediol and 2-methyl-1,8-octanediol.

  The polyisocyanate to be reacted with the polycarbonate diol preferably has a relatively non-rigid molecular structure. For example, 4,4′-diphenylmethane diisocyanate (MDI), 2,6-toluene diisocyanate (TDI), 1,6- Examples include hexane diisocyanate (HDI). Particularly preferred is MDI.

  As the crosslinking agent, it is necessary to use at least a short-chain diol and a short-chain triol. When an aromatic alcohol or amine is used as the cross-linking agent, the resulting polyurethane becomes a resin or a property close to that of a resin and is not an elastic body that can be used as a cleaning blade member. On the other hand, if only a short-chain diol is used as a cross-linking agent, the permanent elongation becomes large and cannot be used as a cleaning blade member. Therefore, in order to improve characteristics such as creep and stress relaxation, three-dimensional cross-linking is performed. The short chain triol is also required.

  The short-chain diol is not particularly limited, but preferably has at least one of propanediol (PD) and butanediol (BD). Here, 1,3-propanediol is representative as propanediol, and 1,4-butanediol is representative as butanediol, and 1,3-propanediol and 1,4-butanediol are performance and cost. However, the present invention is not limited to this. The short-chain triol is not particularly limited, but preferably has at least one of trimethylolethane (TME) and trimethylolpropane (TMP). Of course, two or more kinds of short-chain diols and short-chain triols may be mixed and used. The blending ratio of the main component of the crosslinking agent is not particularly limited, but is preferably short chain diol: short chain triol = 50: 50 to 95: 5, more preferably 60:40 to 90:10 by weight ratio. is there.

  Polyurethane is produced by blending and reacting the above-mentioned polycarbonate diol and crosslinking agent with polyisocyanate. For the reaction, a general method for producing polyurethane 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 is obtained, but is not limited by the production method.

  In the present invention, in addition to the above-mentioned predetermined polycarbonate diol, other long-chain polyols can be used in 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 long-chain polyol in the polyurethane is preferably 60 to 80% by weight.

  When the polyurethane of the present invention is used, a cleaning blade member having ultra-low rebound resilience and excellent physical properties can be obtained.

  As described above, according to the present invention, it is possible to provide a cleaning blade member having ultra-low rebound resilience and excellent physical properties.

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

Example 1
As a base diol, polycarbonate diol using a blend of 65:35 of 1,9-nonanediol and 2-methyl-1,8-octanediol, MDI and 1,3-propanediol / The trimethylolpropane mixed solution was blended with the aim of a hardness of 75 ° and reacted to obtain polyurethane, and a test sample and a cleaning blade were produced. The polycarbonate diol in the polyurethane was about 60% by weight.

(Example 2)
A test sample and a cleaning blade were produced in the same manner as in Example 1 except that a 1,4-butanediol / trimethylolpropane mixed solution was used as a crosslinking agent.

(Example 3)
A test sample and a cleaning blade were produced in the same manner as in Example 1 except that the blending was performed with the aim of a hardness of 70 °.

Example 4
A test sample and a cleaning blade were produced in the same manner as in Example 2 except that the blending was performed aiming at a hardness of 70 °.

(Example 5)
A test sample and a cleaning blade were prepared in the same manner as in Example 1 except that the base diol was a blend of 1,9-nonanediol and 2-methyl-1,8-octanediol at 15:85. Manufactured.

(Example 6)
A test sample and a cleaning blade were prepared in the same manner as in Example 3 except that the base diol was a blend of 1,9-nonanediol and 2-methyl-1,8-octanediol at 15:85. Manufactured.

(Comparative Example 1)
A test sample and a cleaning blade were produced by reacting an ε-caprolactone-based polyester diol with MDI and a 1,4-butanediol / trimethylolpropane mixed solution as a crosslinking agent to form a polyurethane. The polyester diol in the polyurethane was about 60% by weight.

(Comparative Example 2)
A polyester diol is obtained from 2,4-diethyl-1,5-pentanediol and adipic acid, and this polyester diol is reacted with MDI and 1,4-butanediol / trimethylolpropane mixed liquid as a crosslinking agent. Test samples and cleaning blades were made of polyurethane. The polyester diol in the polyurethane was about 60% by weight.

(Comparative Example 3)
Polycarbonate diol using 1,6-hexanediol as the base diol, 1,5-naphthalene diisocyanate (NDI), and 1,4-butanediol / trimethylolpropane mixed solution as a cross-linking agent were reacted to form a polyurethane, which was tested. Samples and cleaning blades were manufactured. The polycarbonate diol in the polyurethane was about 60% by weight.

(Test Example 1)
About the test sample of each Example and each comparative example, at 23 degreeC, the Young's modulus is 25% elongation by JIS K6254, tensile strength at 100% elongation (100% Modulus), tensile strength at 200% elongation ( 200% Modulus), tensile strength and elongation at break were measured according to JIS K6251, tear strength was measured according to JIS K6252, and 100% permanent elongation was measured according to JIS K6262. In addition, the rubber hardness (Hs) is measured at 10 ° C. to 50 ° C. according to JIS K6253 using a Lüpke-type rebound resilience test device based on JIS K6255, and the temperature dependence is also evaluated. did. The results are shown in Table 1-1, Table 1-2, FIG. 1 and FIG.

  From this result, the test samples of Examples 1 to 6 have ultra-low rebound resilience and good general physical properties such as strength as compared with those of Comparative Examples 1 to 3, and the temperature dependence of rebound resilience is 40. It was found to be as small as less than%. It was also confirmed that the temperature dependence of the hardness of the example was excellent as in the comparative example.

  On the other hand, in Comparative Example 1 using caprolactone as a raw material, sufficient low rebound resilience was not obtained. In addition, the polyurethane of low rebound resilience by the method of disturbing the molecular structure of Comparative Example 2 was insufficient in strength such as tensile strength and 200% modulus. It was found that Comparative Example 3 cannot be used as a cleaning blade member because the permanent elongation is extremely large when NDI is used as the isocyanate.

(Test Example 2)
The cleaning blades of Examples 1 to 6 and Comparative Examples 1 to 3 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 under each environment, 10000 sheets of plain paper A4 vertical (print output of only the outer frame) was passed through, and the printed paper was observed. ○: No cleaning, Δ: Occasional white streaks and black spots were observed, and ×: Frequent white streaks and black spots were observed. In addition, the amount of change (wear width) in the length of the cleaning blade before and after passing paper was also obtained. The results are shown in Table 2-1 and Table 2-2.

  As a result, Examples 1 to 6 had good cleaning properties in all environments, a small wear width, and excellent durability. On the other hand, Comparative Example 1 had poor LL cleaning properties and a large wear width. Further, Comparative Example 2 had poor cleaning properties and a large wear width, and Comparative Example 3 had poor cleaning properties in all environments.

[Table 1-1]

[Table 1-2]

[Table 2-1]

[Table 2-2]

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

Claims (4)

A cleaning blade member used in a cleaning unit for removing adhering toner includes a polycarbonate diol having at least one selected from nonanediol and methyloctanediol as a base diol, a polyisocyanate, a short-chain diol, and a short-chain triol. The polyurethane is formed using a crosslinking agent, and the polyurethane has a 100% permanent elongation of 3% or less, a 200% modulus of 90 kg / cm ² or more, a tear strength of 60 kg / cm or more, and a repulsion at 25 ° C. A cleaning blade member having an elastic Rb _T25 of 30% or less, and ΔRb represented by the following formula when the rebound resilience Rb at 10 ° C. and 50 ° C. is Rb _T10 and Rb _T50 , respectively, is 40% or less.
[Equation 1]
ΔRb (%) = Rb _T50 −Rb _T10 2. The cleaning blade according to claim 1, wherein the cross-linking agent is mainly composed of at least one short-chain diol of propanediol and butanediol and at least one short-chain triol of trimethylolethane and trimethylolpropane. Element. 3. The cleaning blade member according to claim 1, wherein the polycarbonate diol is a base diol blended with nonanediol: methyloctanediol = 65: 35 to 15:85 (weight ratio). 4. The cleaning blade member according to claim 1, wherein the polycarbonate diol uses 1,9-nonanediol and 2-methyl-1,8-octanediol as a base diol.

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