JP2753616B2 - Cleaning blade - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a cleaning blade used in an electrophotographic copying machine or the like.

[Conventional technology]

The electrophotographic copying machine is provided with a photosensitive drum having a photoconductor surface layer, the outer peripheral surface of the photosensitive drum is uniformly charged, and then the outer peripheral surface is exposed through a copy image of the copy object. An electrostatic latent image is formed on the outer peripheral surface, a toner image is formed by attaching toner to the electrostatic latent image, and copying is performed by transferring the toner image to copy paper or the like. After the copying, the toner remains on the outer peripheral surface of the photosensitive drum, so that it is necessary to remove the residual toner. As one of the removing methods, a cleaning blade method has been put to practical use. As shown in FIG. 3, the cleaning blade is configured by attaching a plate-shaped blade member 4 to the upper end of a metal plate-shaped holding member 3 with a flange 2 in a longitudinal direction. As shown in FIG. 4, the blade member 4 is attached to the opening edge of the toner collecting box 5, and the blade member 4 is pressed against the surface of the photosensitive drum 6 rotating in the direction of the arrow to scrape the residual toner 7 into the toner collecting box 5. It is like that. The blade member 4 is excellent in mechanical strength such as abrasion resistance and the like.
Since the durability of 4a is quite excellent, it is generally possible to use functional groups with isocyanates having 2.0 functional groups (MDI, TDI, etc.) and polyols with 2.0 functional groups (polyethylene adipate, polycaprolactone ester, etc.). A prepolymer having a radix of 2 is prepared, and a glycol (1,
A soft urethane resin made by adding a curing agent such as 4-butanediol or trimethylolpropane) and injecting it into a plate-shaped molding cavity of a molding die and curing it is used.

[Problems to be solved by the invention]

However, when a blade member is formed using a prepolymer having a functional group number of 2.0 as described above, the formed blade member is likely to adhere to a molding die. There is a problem that undulation occurs in the direction and the dimensional accuracy is deteriorated, and a problem that a long time is required for the production due to a long curing time of the prepolymer. Further, it is also required to further improve the durability of the edge portion. Therefore, an attempt was made to use a prepolymer having a number of functional groups of 3.0.
5,000 cps at ℃), making it difficult to inject into the mold (because the gap of the blade member forming space in the mold is as small as about 1 mm). However, when this prepolymer was injected into the mold with considerable difficulty and a trial production of a blade member was performed, the hardness of the blade member itself increased, thereby improving the demoldability and dimensional accuracy.
Due to the material being in a so-called crimped state or tearing during use, the durability of the lip portion was reduced and the number of copies decreased.

The present invention has been made in view of such circumstances,
(2) An object of the present invention is to provide a cleaning blade which is extremely rich in durability, has high dimensional accuracy, is easy to manufacture, and can be manufactured in a short time.

[Means for solving the problem]

In order to achieve the above object, a cleaning blade according to the present invention includes a plate-like blade member having an edge formed on one side edge along a longitudinal direction for removing toner adhered to a photosensitive drum; In a cleaning blade provided with a plate-like holding material provided on the other side edge of the blade member, the plate-like blade member is configured using a prepolymer having a functional group number of 2.02 to 2.5, which is composed of isocyanate and polyol. Take.

[Action]

The present inventors have conceived from the results of the above-mentioned trial production that if the number of functional groups in the range of more than 2.0 and less than 3.0 is used, a good blade member may be obtained. Conducted research. That is, a material having a number of functional groups of 2.0 or more is mixed or a material having a number of functional groups of 2.0 is mixed.
A mixture of the above-mentioned material and a material having a functional group number of 2.0 or more was used to prepare various prepolymers having a functional group number in the range of more than 2.0 to less than 3.0, and a blade member was formed using these materials, and various tests were conducted. As a result, when a prepolymer having a functional group number of 2.02 to 2.5 is used, the prepolymer can be relatively easily injected into the mold within this range, and the demolding property and dimensions of the obtained blade member can be reduced. It was found that the precision was considerably improved compared to the case of using a prepolymer having 2.0 functional groups, and that the curing time of the prepolymer itself could be shortened. In particular, within the above range of the number of functional groups,
The inventors have found that the エ durability (compared with the tear strength), which should be deteriorated when a prepolymer having a large number of functional groups is originally used, is specifically increased, and reached the present invention.

Therefore, "edge durability" means durability against damage to the edge by repeated use,
In other words, it means the durability to breakage of the edge portion.

The cleaning blade of the present invention comprises a plate-like blade member and a plate-like holding material (see FIG. 3). The plate-like blade member has a prepolymer having a functional group number of 2.02 to 2.5, a curing agent, Is obtained by using

The prepolymer having the number of functional groups of 2.02 to 2.5 is, for example, as follows: (isocyanate having 2.0 functional groups) + (polyol having 2.0 functional groups) + (isocyanate having 3.0 or more functional groups) :( isocyanate having 2.0 functional groups) + (Polyol having 2.0 functional groups) + (polyol having 3.0 or more functional groups).

MDI (diphenylmethane-4,4'-diisocyanate) and TDI
(Tolylene diisocyanate) and the like.

Examples of the polyol having a functional group number of 2.0 include polyethylene adipate, polycaprolactone ester,
Examples include polyester polyols such as polyethylene butylene adipate and polyether polyols such as polyoxypropylene glycol.

As the isocyanate having a functional group number of 3.0 or more,
Modified MDI and the like.

Examples of the polyol having the number of functional groups of 3.0 or more include branched polyethylene adipate.

The mixing ratio of the isocyanate (A) having 2.0 functional groups, the polyol (B) having 2.0 functional groups, and the polyol or isocyanate (C) having 3.0 or more functional groups is A / B / C = 5/100 on a weight basis. It is preferable to set the ratio between / 50 and 50/100/5.

Further, examples of the curing agent include a mixture of 1,4-butanediol and trimethylolpropane. The amount of the curing agent is preferably set to 4 to 8 parts by weight based on 100 parts by weight of the prepolymer.

Further, as the plate-like holding material for holding the blade member made of the above prepolymer, a metal material is usually used, and among them, a stainless steel material is used.

That is, conventionally, a prepolymer was made using a material having both functional groups of 2.0, whereas the present invention
The most distinctive feature is that a material having a number of functional groups of 2.0 and a material having a number of functional groups of 3.0 or more are mixed, and the number of functional groups of the obtained prepolymer is controlled in the range of 2.02 to 2.5. In addition,
The value of 2.02-2.5, which is the number of functional groups of the prepolymer, is
This is the theoretical average number of functional groups per molecule when mixing the various raw materials having the number of functional groups of 2.0 or more.

The manufacture of the blade member according to the present invention is performed, for example, as follows. First, a prepolymer having a functional group number of 2.02 to 2.5 is prepared by the method described above.
Next, a curing agent is added to the prepolymer and mixed well. This mixed solution is poured into a mold for forming a blade member, and heated at an appropriate temperature (about 150 ° C.) for 1 to 4 hours. As a result, the liquid mixture is thermoset in the mold and formed on the blade member. Next, the formed blade member is taken out of the mold and used. The characteristics such as the releasability and dimensional accuracy of the blade member obtained in this manner,
Table 1 below shows comparisons between the conventional blade member (conventional product) and the blade member made of a prepolymer having a functional group of 3.0 (comparative product).

From Table 1 above, it can be seen that the product of the present invention has improved releasability, durability, and dimensional accuracy as compared with the conventional product. In addition, it can be seen that the comparative example product has improved releasability and dimensional strength as compared with the conventional example product, but has a lower tear strength and Etsu durability. In this case, the tear strength and the Etsu durability are similar characteristics. The edge durability is evaluated by the number of copies until the edge of the blade member is damaged. FIG. 1 shows the relationship between the above-mentioned durability (number of copies) and the number of functional groups of the prepolymer. Thus, it can be seen that when the number of functional groups of the prepolymer is in the range of 2.02 to 2.5, the durability is dramatically improved.

 Next, the present invention will be described based on embodiments.

Example 1 A prepolymer was prepared by mixing 100 parts by weight of polyethylene adipate having 2.0 functional groups (hereinafter abbreviated as "parts"), 18 parts of MDI having 2.0 functional groups, and 12 parts of modified MDI having 3.0 functional groups, respectively. Then, 5 parts of a hardening agent comprising a mixture of 1,4-butanediol and trimethylolpropane was added thereto and mixed to prepare a molding material, which was poured into a molding die and heated at a temperature of 150 ° C. for 2 hours. After being heated and cured, it was removed from the mold to obtain a blade member. In addition,
The number of functional groups of the above prepolymer was 2.5.

Example 2 A prepolymer was prepared by mixing 50 parts of polyethylene adipate having 2.0 functional groups, 50 parts of polyethylene adipate having 3.0 functional groups, and 30 parts of MDI having 2.0 functional groups. Otherwise, a blade member was obtained in the same manner as in Example 1 above. The number of functional groups of this prepolymer was 2.5.

Example 3 A prepolymer was prepared by mixing 80 parts of polyethylene adipate having 2.0 functional groups, 20 parts of polyethylene adipate having 3.0 functional groups, and 30 parts of MDI having 2.0 functional groups, and the heating time was set to 4 hours. . Otherwise, a blade member was obtained in the same manner as in Examples 1 and 2. In this case, the number of functional groups of the prepolymer was 2.2.

(Comparative example)

A prepolymer was prepared by mixing 100 parts of polyethylene adipate having 3.0 functional groups and 30 parts of modified MDI having 3.0 functional groups. Then, 7 parts of a curing agent composed of a mixture of 1,4-butanediol and trimethylolpropane was added thereto and mixed. The mixture was poured into a mold and heated at a temperature of 150 ° C. for 1 hour. And a blade member was obtained. The number of functional groups in the above prepolymer was 6.0.

[Conventional Example 1] A prepolymer was prepared by mixing 100 parts of polyethylene adipate having 2.0 functional groups and 30 parts of MDI having 2.0 functional groups.
Then, 5.5 parts of a hardening agent composed of a mixture of 1,4-butanediol and trimethylolpropane was added thereto and mixed. The mixture was poured into a mold and heated at a temperature of 150 ° C. for 6 hours. And a blade member was obtained. The number of functional groups of the above prepolymer was 2.0.

[Conventional Example 2] A blade member was obtained in the same manner as in Conventional Example 1 except that the heating time was changed to 4 hours. In this case, the number of functional groups of the prepolymer was 2.0.

Using the above example, comparative example and conventional example,
Dimensional failure rate and breaking strength were tested. The results are shown in Table 2 below.

From the results in Table 2 above, the product of the example is compared with the conventional product,
The production (heating) time is greatly reduced, and the tear strength is improved. On the other hand, in the case of the conventional product, when the manufacturing time is forcibly shortened, the tear strength is reduced and the dimensional defect rate is significantly increased. In addition, although the production time of the comparative example product is shortened, as described above, casting is difficult,
Further, there is a disadvantage that the product itself is reduced. In addition, the Etsu durability of the product of the above example is as shown in Table 1, and is particularly excellent.

FIG. 2 shows a modification of the shape of the blade member.
This blade member is formed thick on the upper side and thin on the lower side. More specifically, the blade member 8 has a length a of 8 mm and a thickness b of the thick portion on the upper side.
2.8 mm, the thickness c of the thin portion on the lower side is set to 1 mm, and the length d of the thin portion is set to 1.2 mm. By forming in this way, the stiffness of the edge portion 8a is strengthened, so that the toner can be scraped off satisfactorily, and the generation of abnormal noise due to the buckling can be prevented.

In addition, the number of functional groups of the prepolymer used for manufacturing the blade member is set to 2.02 to 2.5, and the more preferable range is 2.1 to 2.2.

〔The invention's effect〕

As described above, the present invention uses a prepolymer having a functional group number of 2.02 to 2.5 as a molding material of the blade member, so that the releasability of the blade member is improved as compared with the blade member having a functional group number of 2.0. The dimensional accuracy of the blade member is also improved. Further, within the above functional group number range,
The viscosity of the prepolymer is within the proper range for casting (2800 cps
Since the prepolymer is maintained in the following conditions, the prepolymer can be easily injected into the mold, and the curing time can be shortened, so that the time required for production can be considerably shortened.
Further, within the above range of the number of functional groups, the durability, which should be worse when the number of functional groups is larger, finally becomes specifically higher, so that when it is used, the effect of greatly increasing the number of copies can be obtained. Become.

[Brief description of the drawings]

FIG. 1 is a curve diagram showing the relationship between the edge durability and the number of functional groups of the cleaning blade of the present invention, FIG. 2 is an explanatory diagram of the use state of another embodiment, FIG. 3 is a perspective view of a conventional example, FIG. 4
The figure is an explanatory view of the state of use. 3 ... plate-like holding material, 6 ... photosensitive drum, 7 ... residual toner, 8 ... blade member, 8a ...

Claims (2)

(57) [Claims] 1. A plate-shaped blade member having an edge formed on one side edge along a longitudinal direction for removing toner attached to a photosensitive drum, and another edge of the plate-shaped blade member. A cleaning blade provided with a plate-like holding member, wherein the plate-like blade member is formed using a prepolymer having a functional group number of 2.02 to 2.5, which is composed of isocyanate and polyol. 2. The cleaning blade according to claim 1, wherein said isocyanate comprises an isocyanate having a functional group of 2.0 and an isocyanate having a functional group of 3.0 or more.