JP2003073440A - Rubber member for electrophotographic use - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rubber member for an electrophotographic use, which has impact resilience sufficiently stable even under the conditions of varying environment, enabling it to apply as a functional cleaning blade and the like. SOLUTION: A rubber elastic body composed of a polyurethane obtained by using a polyester polyol having a number average molecular weight of 500-5,000 and also having in the range of 2-8 mmol/g of ester concentration defined by the formula: ester concentration (mmol/g)=(mol number of ester group)/(weight of polyester polyol), is used as the rubber member for an electrophotographic use.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic rubber member used in a cleaning section, a charging section, a developing section, a transfer section, a sheet feeding section, etc. of an electrophotographic method, and more particularly to a photoconductor or a photoreceptor in the electrophotographic method. Such as a transfer belt, a cleaning member that removes toner on a toner image carrier that forms a toner image and then transfers the toner image onto a transfer material, a developing member used in a developing unit, and a charging member that charges a photoconductor. The present invention relates to a rubber member for electrophotography.

[0002]

2. Description of the Related Art Generally, in an electrophotographic process, at least each process of charging, exposing, developing, transferring and cleaning is performed on an electrophotographic photosensitive member. In such an electrophotographic process, a cleaning member that forms a toner image and then removes the toner on the toner image carrier that transfers the toner image to a transfer material, a developing member used in the developing unit, and a charging member that charges the photoconductor. For example, polyurethane is used.

This is because polyurethane has good abrasion resistance, has sufficient mechanical strength without adding a reinforcing agent, etc., and is non-staining.

[0004]

However, it is known that the physical properties of polyurethane have temperature dependence. The temperature dependence particularly appears in impact resilience, which is a problem in cleaning when a cleaning blade made of polyurethane is used. That is, when the impact resilience decreases at low temperature, cleaning becomes poor, and when the impact resilience increases at high temperature, problems such as chipping of edges and squeaking occur.

By the way, due to the recent improvement in image quality in electrophotographic technology, the particle size of the toner has been reduced, and a blade with higher functionality has been desired.

In view of such circumstances, the present invention provides an electrophotographic rubber member which has a sufficiently stable impact resilience even when the environment changes and can be used as a highly functional cleaning blade or the like. It is an issue.

[0007]

The first aspect of the present invention for solving the above-mentioned problems is to have a number average molecular weight of 500 to 5000 and an ester concentration defined by the following formula of 2 to 8 mmol / g.
A rubber member for electrophotography, which is a rubber elastic body made of polyurethane obtained by using a polyester polyol in the above range as a long-chain polyol.

[0008]

## EQU3 ## Ester concentration (mmol / g) = (number of moles of ester group) / (weight of polyester polyol)

A second aspect of the present invention is the rubber member for electrophotography according to the first aspect, wherein the polyester polyol is obtained by dehydration condensation of a diol component and a dibasic acid. It is in.

A third aspect of the present invention is the same as the first aspect, wherein the polyester polyol is a lactone obtained by copolymerizing lactones or dehydration-condensing the diol component and dibasic acid during dehydration condensation. It is a rubber member for electrophotography, characterized in that it is a product in which types are added to each other.

A fourth aspect of the present invention is the rubber member for electrophotography according to any one of the first to third aspects, characterized in that the long chain polyol in the polyurethane is 60 to 80% by weight. is there.

According to a fifth aspect of the present invention, in any one of the first to fourth aspects, the minimum impact resilience in the temperature range of -20 ° C to 60 ° C of the rubber elastic body is 0 ° C or less. And a rubber member for electrophotography.

In a sixth aspect of the present invention, in any one of the first to fifth aspects, when the impact resilience of the rubber elastic body at 10 ° C. and 50 ° C. is Rb _T10 and Rb _T50 , respectively, The expressed ΔRb is 55% or less, in the electrophotographic rubber member.

[0014]

[Formula 4] ΔRb (%) = Rb _T50 −Rb _T10

A seventh aspect of the present invention is the rubber elastic body according to any one of the first to sixth aspects, in which the impact resilience at 10 ° C. is 15% or more and the impact resilience at 50 ° C. is 70% or less. The rubber member for electrophotography is characterized by being present.

An eighth aspect of the present invention is any one of the first to seventh aspects, wherein the rubber elastic body has a hardness according to JIS A
The rubber member for electrophotography is characterized in that it is 50 to 90 °.

According to a ninth aspect of the present invention, in any one of the first to eighth aspects, the polyurethane uses a polyester polyol having an ester concentration in the range of 6 to 8 mmol / g. It is a characteristic rubber member for electrophotography.

A tenth aspect of the present invention is the same as the ninth aspect, wherein the polyurethane is a long chain polyol composed of the polyester polyol, and a polyisocyanate.
A rubber member for electrophotography, comprising a short-chain polyol having a molecular weight of less than 500.

An eleventh aspect of the present invention is the same as the tenth aspect, wherein the main component of the long-chain polyol is condensation of at least one of 1,9-nonanediol and methyl-1,8-octanediol with adipic acid. According to another aspect of the present invention, there is provided a rubber member for electrophotography, which is a polyester polyol.

The twelfth aspect of the present invention is the tenth or eleventh aspect.
In the above aspect, the rubber component for electrophotography is characterized in that the main component of the polyisocyanate is diphenylmethane diisocyanate.

A thirteenth aspect of the present invention is the electrophotographic rubber member according to any one of the tenth to twelfth aspects, wherein the main component of the short chain polyol is 1,3-propanediol. is there.

A fourteenth aspect of the present invention is the electrophotographic rubber member according to any one of the tenth to thirteenth aspects, wherein the short-chain polyol contains trimethylolethane.

A fifteenth aspect of the present invention is the rubber member for electrophotography according to any one of the first to fourteenth aspects, which has a blade shape.

In the present invention, the number average molecular weight is 500 to 500.
0 and the ester concentration defined in the above formula is 2 to 8 mmo
Polyurethane obtained by using a polyester polyol in the range of 1 / g is used as a rubber elastic material.

That is, the present invention has an ester concentration of 2 to
If the polyurethane is a polyester polyol having an ester concentration of 8 mmol / g, which is lower than the conventionally used polyol, the temperature dependence of impact resilience is reduced,
In addition, it is based on the knowledge that the impact resilience in the low temperature region can be secured to some extent, and the rise in the impact resilience in the high temperature region can be suppressed to reduce edge chipping and the like. Particularly, those having an ester concentration of 6 to 8 mmol / g are suitable for achieving both mechanical strength and temperature dependence such as impact resilience.

As the polyol having such a predetermined ester concentration, it is preferable to use a polyester polyol obtained by dehydration condensation of a diol component and a dibasic acid, rather than a caprolactone diol which has been conventionally used as a standard. I found it good. However, even if a polyol other than the polyester polyol obtained by the dehydration condensation of the diol component and the dibasic acid is used, the above-mentioned characteristics can be obtained as long as the ester concentration falls within the predetermined range described above.

Examples of the predetermined polyester polyol used in the present invention include ethylene glycol, butanediol, hexanediol, nonanediol, decanediol, 3-methyl-1,5-pentanediol, neopentyl glycol and 2,4-diethyl. Diols such as 1,5-pentanediol, butylethylpropanediol, 1,9-nonanediol, 2-methyl-1,8-octanediol, and adipic acid, azelaic acid, sebacic acid, dimer acid, hydrogenated dimer acid And the like, which have an ester concentration satisfying the above-mentioned conditions in combination with a dibasic acid. Specifically, nonanediol adipate, 2-methyl-1,8-octanediol adipate, decanediol adipate, hexanediol azelate, nonanediol azelate, 2-methyl-1,8-octanediol azelate, decanediol. Azelate, butanediol sebacate, hexanediol sebacate, nonanediol sebacate, 2
-Methyl-1,8-octanediol sebacate, decanediol sebacate, dimer acid ester of various glycols, hydrogenated dimer acid ester and the like can be mentioned. It is also possible to combine several diols and dibasic acids.

Further, lactones such as ε-caprolactone and δ-valerolactone can be polyadded or copolymerized within the range of the above-mentioned conditions. That is, a polyol obtained by copolymerizing lactones into a random copolymer during dehydration condensation of a diol component and a dibasic acid, or polyadding lactones to the dehydrated condensation product It can also be used. By using lactones in this way, the impact resilience at low temperatures can be further improved.

Particularly preferred in terms of performance and cost are polyester polyols obtained by dehydration condensation of diols such as 1,9-nonanediol and methyl-1,8-octanediol with adipic acid. Of course, it is also possible to suitably use those containing these as main components and substituting some of them with other glycols or dibasic acids. here,
Methyl-1,8-octanediol is an octanediol having a methyl group at a position other than 1 or 8, and a typical one is 2-methyl-1,8-octanediol, but it is not limited to this. Not something.

As the polyisocyanate to be reacted with the polyester polyol, 2,6-toluene diisocyanate (TDI), 4,4'-diphenylmethane diisocyanate (MDI), paraphenylene diisocyanate (PPDI), 1,5-naphthalene diisocyanate ( NDI), 3,3-dimethyldiphenyl-4,
4'-diisocyanate (TODI) etc. can be mentioned. Especially, M and M are suitable in terms of performance and cost.
It is DI.

In order to produce polyurethane using the above-mentioned polyester polyol, polyisocyanate is blended with the polyester polyol and the short chain polyol as the chain extender and reacted. 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 it provides a polyurethane excellent in strength and abrasion resistance, but is not limited by the manufacturing method.

Here, the short-chain polyol has a number average molecular weight of 500 or less, and for example, main chain carbon atoms such as ethylene glycol, 1,3-propanediol and 1,4-butanediol have 2 to 2 carbon atoms. 12 straight-chain glycols; diols having a side chain of 12 or less carbon atoms such as neopentyl glycol and 3-methyl-1,5-pentanediol; 12 or less carbon atoms such as 3-allyloxy-1,2-propanediol Diols having unsaturated groups; and C20 containing aromatic rings such as 1,4-bis (hydroxyethoxy) benzene and paraxylene glycol
The following diols, alicyclic diols such as cyclohexanediol and cyclohexanedimethanol, triols such as trimethylolethane, trimethylolpropane and glycerin, and tetrafunctional or higher functional polyols such as pentaethritol and sorbitol. be able to. Of course, two or more kinds of these short chain polyols may be mixed and used.

Particularly suitable in terms of performance and cost are 1,4-butanediol and 1,3-propanediol. In particular, 1,3-propanediol exhibits an even greater effect when combined with a polyol having an ester concentration of 6 to 8 mmol / g. Further, it is preferable to use trimethylolethane together as a trifunctional or higher functional polyol that is added to improve properties such as creep and stress relaxation.

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

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

The rubber hardness of the rubber-like elastic material of the present invention is JI.
S A is preferably 50 to 90 °.

When the polyurethane of the present invention is used, the mechanical properties required as a rubber member for electrophotography are maintained, and the temperature dependence of impact resilience becomes extremely small,
In particular, it is suitable for use as a rubber member for electrophotography such as a cleaning blade.

[0038]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below based on Examples.

Example 1 A polyester polyol having a molecular weight of 2000 was obtained from 1,9-nonanediol and adipic acid. The ester concentration in the polyester polyol is 6.8 mmol / g.

A thermosetting polyurethane was prepared by using this polyester polyol, MDI and a 1,4-butanediol / trimethylolpropane mixed solution as a chain extender to prepare a test sample and a cleaning blade. The polyester polyol in polyurethane was about 65% by weight.

Example 2 A polyester polyol having a molecular weight of 2000 was obtained from hexanediol and hydrogenated dimer acid. The ester concentration in the polyester polyol is
It is 3.0 mmol / g.

A test sample and a cleaning blade were manufactured in the same manner as in Example 1 except that this polyester polyol was used. The polyester polyol in polyurethane was about 65% by weight.

(Example 3) 1,9-nonanediol / 2
-Methyl-1,8-octanediol (molar ratio 65/3
A polyester polyol having a molecular weight of 2000 was obtained from 5) and adipic acid. The ester concentration in the polyester polyol is 6.8 mmol / g.

A thermosetting polyurethane was prepared by using this polyester polyol, MDI and a 1,3-propanediol / trimethylolethane mixed solution as a chain extender to prepare a test sample and a cleaning blade. The polyester polyol in polyurethane was about 65% by weight.

Example 4 25% by weight of ε-caprolactone was copolymerized in Example 3 to obtain a polyester polyol having a molecular weight of 2000. The ester concentration in the polyester polyol is 7.3 mmol / g.

A thermosetting polyurethane was prepared by using this polyester polyol, MDI and a 1,3-propanediol / trimethylolethane mixed solution as a chain extender to prepare a test sample and a cleaning blade. The polyester polyol in polyurethane was about 65% by weight.

(Comparative Example 1) A test sample and a cleaning blade were produced in the same manner as in Example 1 except that a polyester polyol having a molecular weight of 2000 and consisting of ethylene glycol and adipic acid (ester concentration 11.3 mmol / g) was used. . The polyester polyol in polyurethane was about 65% by weight.

Comparative Example 2 A polyester diol having a number average molecular weight of 2000 (caprolactone A: ester concentration 8.5 mmol / g) obtained by using ethylene glycol as an initiator and adding ε-caprolactone thereto was used. A test sample and a cleaning blade were manufactured in the same manner as in Example 1. The polyester polyol in polyurethane was about 65% by weight.

Comparative Example 3 A polyester diol having a number average molecular weight of 1500 (caprolactone B: ester concentration 7.6 mmol / g) obtained by adding ε-caprolactone to dodecanediol as an initiator was used. A test sample and a cleaning blade were manufactured in the same manner as in Example 1. The polyester polyol in polyurethane was about 65% by weight.

Test Example 1 With respect to the test samples of Examples and Comparative Examples, the impact resilience at 0 ° C. to 50 ° C. was measured to evaluate the temperature dependence. The results are shown in Table 1 and FIG.
Shown in. The impact resilience was determined by a Rupke-type impact resilience test device based on JIS K6255. Further, the rubber hardness was determined according to JIS K6253.

From these results, the test samples of Examples 1 to 4 have remarkably small temperature dependence of impact resilience and ΔRb of 55% or less, as compared with those of Comparative Examples 1 to 3.
It was found that the impact resilience at 10 ° C. was 15% or more and the impact resilience at 50 ° C. was 70% or less.

[0052]

[Table 1]

(Test Example 2) Using the cleaning blades of the respective examples and comparative examples, the cleaning characteristics were set to LL (1
0 ℃ 15% RH), NN (23 ℃ 50% RH), HH
Evaluation was performed under each condition (35 ° C., 85% RH), and the edge wear state was observed. The cleaning property was measured using a spherical polymerization toner having an average particle size of 6 μm. The results are shown in Table 2. Moreover, the data of each impact resilience are also shown.

From these results, the cleaning blades of Examples 1 to 4 exhibited stable cleaning characteristics against temperature changes, good cleaning characteristics at low temperatures, and good edge durability at high temperature use. I understood. These samples have ΔRb of 55% or less,
The impact resilience at ℃ is 15% or more and the impact resilience at 50 ℃ is 70
% Or less.

On the other hand, Comparative Example 1 having a high ester concentration
In, the edge was in good condition of wear, but cleaning at low temperature was poor. This sample has a ΔRb of 55%
As shown below, the impact resilience at 10 ° C. was less than 15%.

In Comparative Example 2, it was found that cleaning at high temperature was difficult. In this sample, ΔRb is 64%, and the impact resilience is highly dependent on temperature.
The impact resilience at ℃ was over 70%.

Further, in Comparative Example 3, the ester concentration was 8
Although it is a polyurethane using a polyester polyol smaller than mmol / g, good cleaning could not be performed. In this sample, ΔRb was 38% and the temperature dependence of impact resilience was relatively small, and the impact resilience at 50 ° C. was less than 70%, but the minimum impact resilience was 20 ° C. and higher than 0 ° C.

From these results, it is clear that the conventional toner having a relatively large particle size and a crushed shape has a good cleaning property, whereas the polyester urethane made of polyethylene adipate or polycaprolactone has a small particle size and a true particle size. Sufficient cleaning properties are not obtained for toner with high sphericity, and it is better to use polyurethane satisfying the conditions of the present invention for toner with such small particle size and high sphericity. It was found that the following characteristics were obtained.

[0059]

[Table 2]

Regarding the cleaning characteristics in the table, ◯ means good cleaning, and x means no cleaning. The wear state of the edge is indicated by OK for uniform wear that does not hinder the image and NG for non-uniform wear such as missing that causes a defect in the image.

[0061]

As described above, according to the present invention,
It is possible to provide a rubber member for electrophotography which has a sufficiently stable impact resilience even when the environment changes and can be used as a highly functional cleaning blade or the like.

[Brief description of drawings]

FIG. 1 is a graph showing the results of test examples.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Noriko Abe             2-3-3 Shirate, Tsurumi-ku, Yokohama-shi, Kanagawa               Hokushin Industry Co., Ltd. (72) Inventor Mika Sakata             2-3-3 Shirate, Tsurumi-ku, Yokohama-shi, Kanagawa               Hokushin Industry Co., Ltd. (72) Inventor Shuhei Noda             2-3-3 Shirate, Tsurumi-ku, Yokohama-shi, Kanagawa               Hokushin Industry Co., Ltd. F term (reference) 2H077 AD13 AD23 FA22 GA02                 2H134 GA01 GB02 HD04 HD05 HD19                       KD08 KD09 KH04 KH05 KH15                 2H200 FA01 FA08 FA09 FA10 HA02                       HA28 HB14 HB45 HB47 JA02                       JA25 JA27 LB13 LB35 LB37                       MA03 MA11 MA17 MA20 MC01                       MC02 MC03 MC05 MC18                 4J034 AA01 AA06 BA03 BA07 DA01                       DB03 DC50 DF14 DF15 DF16                       DF20 DF24 HA01 HA06 HA07                       HC11 HC12 HC22 HC52 HC54                       HC64 HC67 HC71 QB14 QB15                       RA14

Claims (15)

[Claims] 1. A rubber elastic body made of polyurethane obtained by using a polyester polyol having a number average molecular weight of 500 to 5,000 and an ester concentration defined by the following formula in the range of 2 to 8 mmol / g as a long chain polyol. A rubber member for electrophotography, which is characterized by: ## EQU1 ## Ester concentration (mmol / g) = (number of moles of ester group) / (weight of polyester polyol) 2. The rubber member for electrophotography according to claim 1, wherein the polyester polyol is obtained by dehydration condensation of a diol component and a dibasic acid. 3. The polyester polyol according to claim 1, wherein the polyester polyol is obtained by copolymerizing lactones during dehydration condensation of a diol component and a dibasic acid or by dehydration condensation of lactones. A rubber member for electrophotography, which is characterized in that 4. The method according to claim 1, wherein the long chain polyol in the polyurethane is 60 to 80% by weight.
A rubber member for electrophotography, characterized in that 5. The electrophotographic rubber according to claim 1, wherein the rubber elastic body has a minimum impact resilience value of 0 ° C. or less in a temperature range of −20 ° C. to 60 ° C. Element. 6. The rebound resilience at 10 ° C. and 50 ° C. of the rubber elastic body according to claim 1, respectively.
_{When T10} and Rb _T50 , ΔRb represented by the following formula
Of 55% or less is a rubber member for electrophotography. [Formula 2] ΔRb (%) = Rb _T50 −Rb _T10 7. The impact resilience at 10 ° C. of the rubber elastic body according to claim 1, which is 15% or more, and 5
A rubber member for electrophotography, which has a impact resilience at 0 ° C. of 70% or less. 8. The rubber member for electrophotography according to claim 1, wherein the rubber elastic body has a hardness of 50 to 90 ° according to JIS A. 9. The polyurethane according to claim 1, wherein the polyurethane has an ester concentration of 6 to 8 mmol / g.
A rubber member for electrophotography, characterized by using a polyester polyol in the range of. 10. The electrophotographic rubber member according to claim 9, wherein the polyurethane is composed of a long chain polyol composed of the polyester polyol, a polyisocyanate, and a short chain polyol having a molecular weight of less than 500. . 11. The main component of the long chain polyol according to claim 10, wherein the main components are 1,9-nonanediol and methyl-
A rubber member for electrophotography, which is a polyester polyol obtained by condensation of at least one of 1,8-octanediol and adipic acid. 12. The rubber member for electrophotography according to claim 10, wherein the main component of the polyisocyanate is diphenylmethane diisocyanate. 13. The method according to claim 10, wherein
A rubber member for electrophotography, wherein the main component of the short-chain polyol is 1,3-propanediol. 14. The method according to claim 10, wherein
The rubber member for electrophotography, wherein the short-chain polyol contains trimethylolethane. 15. The rubber member for electrophotography according to claim 1, which has a blade shape.