CN111158227A

CN111158227A - Transfer roller with stable resistance value and preparation method thereof

Info

Publication number: CN111158227A
Application number: CN202010097155.7A
Authority: CN
Inventors: 周巍峙
Original assignee: Pingtian Rubber & Plastic Hardware Products Shenzhen Co ltd
Current assignee: Pingtian Rubber & Plastic Hardware Products Shenzhen Co ltd
Priority date: 2020-02-17
Filing date: 2020-02-17
Publication date: 2020-05-15

Abstract

The invention discloses a transfer roller with stable resistance value and a preparation method thereof. The invention changes the existing single-layer semiconductive elastic layer into a double-layer structure, and the solid elastic layer of the outer layer has no holes, so that the defect caused by large holes is avoided, no holes are formed, no dust is accumulated, and the dust accumulation can seriously influence the printing quality. In summary, the transfer roller with the structure is an ideal transfer roller, and is suitable for high-grade printer types, high-speed printer types and printer types with high requirements on service life.

Description

Transfer roller with stable resistance value and preparation method thereof

Technical Field

The invention relates to the technical field of printing and copying, in particular to a transfer roller with stable resistance value and a preparation method thereof.

Background

A transfer roll, which is a semiconductive elongated roll product, is required in both printers and copiers, and is generally composed of a core shaft (typically a metal shaft) and a foamed elastic layer. The foamed elastic layer requires uniform foamed cells, and the cell thickness cannot exceed 200 μm. The transfer roller is also an important part for determining the quality of print quality as one of the core parts, and the quality of the foamed elastic layer directly affects the quality of print image quality. The foam body has a surface with holes after all, and dust is inevitably dropped during placement or operation, which affects the potential risk of dropping the print and, of course, the service life.

For example, the utility model CN200820147174 discloses a device for forming a conductive roller foam rubber layer, and the invention CN200810141786 discloses a method and device for forming a conductive roller foam rubber layer, the foamed conductive roller is made by in-mold foaming, and the in-mold foaming has the described problems, "because of the influence of environment, the central spindle in the middle part receives a large amount of heat, the temperature is high, the heat is concentrated and not easy to be dissipated, and at the two ends of the mold, the heat conduction is not only along the circumferential direction, but also along the vertical section, the heat is conducted outwards, the heat is easy to be dissipated, thereby the two ends of the mold are transferred upwards, the heat of the lower forming mold is reduced compared with the middle part, thus, the conductive foam rubber is not uniformly heated, and the foaming multiplying power is also uniform. "it is known that the image quality is seriously affected by the non-uniformity of the conductivity due to the non-uniformity of the foaming ratio and the non-uniformity of the conductivity.

To this end, an invention patent No. 201811604328.9 previously filed by the present applicant discloses a conductive roller with stable resistance value and a method for manufacturing the same, the conductive roller comprising a core shaft of an inner layer, an elastic layer of a middle layer and a coating layer of a surface, the elastic layer being formed by mixing a base material and an auxiliary material. The scheme is that the foaming is extruded and foamed, the foaming is in a mould, the hot air is directly vulcanized and foamed after being extruded, and the material is uniformly heated due to the flowing hot air around the foaming body, particularly the foaming multiplying power of the foaming body in the circumferential direction and the transverse direction is uniform and consistent, the thickness of foaming holes is uniform and consistent, and the electrical conductivity of the foaming body can also reach consistency. The circumferential and transverse resistance circumferential multiplying power can be controlled within 1.1 times, and the requirement of the product on 1.3 times is strictly met. However, in order to solve the problem of the pores on the surface of the foam, although the elastic layer of the middle layer is provided with the coating layer, the coating layer has limited protection on the foam with pores on the surface, and the service life of the foam is still affected.

Further, an invention patent granted with publication number CN101533243B discloses a toner transporting section comprising a vulcanized rubber composition provided at least on an outermost layer thereof, the vulcanized rubber composition containing: weakly conductive carbon black, highly conductive carbon black, an inorganic filler (composed of at least one metal oxide selected from the group consisting of titanium oxide, aluminum oxide, and silica), and a rubber component in which the above components are mixed. The invention is a developing shaft in a printer, and has the functions of enabling carbon powder to be charged in a friction mode and keeping attraction force of the charged carbon powder. The idea of the designed semiconductive rubber formula is that the added conductive carbon black conducts electricity, the carbon black conducts electricity electronically, and the electronic conduction has the defects of uneven local resistance and large resistance change due to different voltages. Such defects do not constitute a printing problem in the development axis, but have a great influence when applied to a transfer roller.

Disclosure of Invention

The following presents a simplified summary of embodiments of the invention in order to provide a basic understanding of some aspects of the invention. It should be understood that the following summary is not an exhaustive overview of the invention. It is not intended to determine the key or critical elements of the present invention, nor is it intended to limit the scope of the present invention. Its sole purpose is to present some concepts in a simplified form as a prelude to the more detailed description that is discussed later.

In order to solve the technical problem, the foaming body is provided with a semiconductive solid elastomer layer on the outer layer of the foaming body. The materials selected for making the elastic layer are largely divided into two categories based on their conductive properties: firstly, the main material is non-conductive, such as EPDM and silica gel, the conductivity is realized by adding an electronic conductive material, the defects are that the material is difficult to be uniformly mixed, the resistance is difficult to be stabilized in a narrow range, the uniformity of the product resistance is also seriously influenced, the printing quality is realized based on the uniform resistance condition, and thus, the printing quality is difficult to be ensured due to the non-uniformity; secondly, the main body material has certain conductivity, such as ECO and NBR, and the conductivity of the main body material is based on ion conductivity, so that the main body material has the advantage that the resistance value can be very accurate and uniform. The invention selects the second main body material for the outer layer solid elastomer layer, thereby providing guarantee for uniform resistance.

According to one aspect of the application, a transfer roller with stable resistance value is provided, which comprises an inner core shaft, a middle foaming elastic layer wrapped outside the core shaft and an outer solid elastic layer wrapped outside the foaming elastic layer, wherein the foaming elastic layer is formed by mixing a base material and an auxiliary material, the base material is a combination of ECO and NBR or EPDM or SBR, the auxiliary material comprises an inorganic filler, a vulcanizing agent, an accelerant and a conductive agent, when the base material is the combination of ECO and NBR, the ECO accounts for 20-80% of the whole weight of the base material, the NBR accounts for 80-20%, and when the base material is EPDM, the EPDM accounts for 100%; when the substrate is SBR, the SBR accounts for 100 percent. The outer-layer entity elastic layer is formed by mixing a base material and an auxiliary material, wherein the base material is a combination of ECO and NBR, the auxiliary material comprises an inorganic filler, a vulcanizing agent, an accelerant and a conductive agent, the ECO in the base material accounts for 20-80% of the total weight of the base material, and the NBR accounts for 80-20% of the total weight of the base material.

Preferably, the conductive agent of the foamed elastic layer and/or the conductive agent of the outer solid elastic layer is alkyl trimethyl ammonium perchlorate, and the conductive agent accounts for 1-5% of the total weight of the base material and the auxiliary material. The alkyl trimethyl ammonium perchlorate salt is a stable resistance material which can stabilize the resistance of the elastic layer.

The conductive agent of the foaming elastic layer and/or the conductive agent of the outer solid elastic layer is conductive carbon black, and the conductive agent accounts for 10-28% of the total weight of the base material and the auxiliary material. The conductive carbon black is an electronic conductive agent which has little dependence on the environment and little dependence on humidity.

The conductive agent of the foamed elastic layer and the conductive agent of the outer solid elastic layer are realized by different conductive agents, for example, the conductive agent of the foamed elastic layer adopts alkyl trimethyl ammonium perchlorate, and the conductive agent of the outer solid elastic layer adopts conductive carbon black.

The mandrel of the transfer roller is in interference fit with the foaming elastic layer, namely the outer diameter of the mandrel of the inner layer is 0.2-0.5mm larger than the inner diameter of the foaming elastic layer of the middle layer.

The foamed elastic layer of the transfer roller is in interference fit with the outer solid elastic layer, namely the outer diameter of the foamed elastic layer of the middle layer is 0.2-0.5mm larger than the inner diameter of the outer solid elastic layer.

Preferably, the bulk resistance value (bulk resistance) of the outer solid elastic layer is between 0.1M Ω and 100M Ω. Further preferably, the volume resistance value of the foamed elastic layer is smaller than that of the outer solid elastic layer.

Further, the overall volume resistance of the transfer roller is 0.1 M.OMEGA.to 100 M.OMEGA..

Furthermore, the thickness range of the foaming elastic layer is 2-6 mm. The thickness range of the outer layer entity elastic layer is 0.5-2 mm. The hardness range of the foaming elastic layer is ASKER C25-50 degrees. The hardness range of the outer layer entity elastic layer is Shore A25-60 degrees. The whole hardness range of the transfer roller is ASKER C25-50 degrees.

Preferably, the outer layer solid elastic layer is also provided with a surface coating, and the surface coating is a polyamine ester coating.

Wherein the surface roughness of the transfer roller is Ra0.4-1 μm.

According to another aspect of the present application, there is provided a method of manufacturing a transfer roller having a stable resistance value, including: mixing the materials according to the formula requirement of the transfer roller, mixing the materials → cleaning the mandrel → extruding and forming the middle foaming layer → extruding and forming the outer layer solid elastomer layer → foaming tubes, cutting the solid tubes → sleeving the foaming layer on the mandrel → grinding → sleeving the outer layer on the foaming layer → baking → grinding → dip coating → cutting off the two ends.

By adopting the scheme, the transfer roller with the special structure and the preparation method thereof have long service life and can keep good printing under various environment change conditions. The invention has the beneficial effects that: the product structure is three layers, the core shaft of the inner layer, the middle layer is a foaming layer, the outer layer is a solid elastomer layer, and the surface is provided with a coating. The base material of the foaming layer can be ECO/NBR or EPDMS material, and the base material of the solid elastomer layer is ECO and NBR mixed material. The inner core shaft only provides necessary conductivity (the resistance value is necessarily lower than that of the outer core shaft) and enough low hardness so as to keep necessary deformation, a specific proportion of a conductive agent is specially added into the foaming layer, and the formula is optimized and improved, the conductive agent is alkyl trimethyl ammonium perchlorate, is a stable resistance material and can stabilize the resistance of the elastic layer, and the conductive roller processed and manufactured by the material has stable conductivity; the outer solid elastomer layer particularly uses conductive carbon black as an electronic conductive agent, has low environmental dependency, low humidity dependency, and small change in energization rise, and can maintain good print quality even when printed under various environmental change conditions and also maintain good print quality even when printed for a long time. The invention changes the existing single-layer semiconductive elastic layer into a double-layer structure, and the solid elastic layer of the outer layer has no holes, so that the defect caused by large holes is avoided, no holes are formed, no dust is accumulated, and the dust accumulation can seriously influence the printing quality. In summary, the transfer roller with the structure is an ideal transfer roller, and is suitable for high-grade printer types, high-speed printer types and printer types with high requirements on service life.

The invention adopts a semiconductive rubber material as a base material, and the conductive material rubber material has a semiconductive function during synthesis, so that the material does not have a local nonuniform phenomenon due to the function during synthesis. The conductive base of the rubber material is ion conduction, and the ion conduction is stable under different voltages, so that good and stable semiconductor functions can be obtained. In addition, patent CN101533243B also describes that the hardness of the conductive carbon black increases with the increase of the amount of the conductive carbon black, and the hardness is too high, which is also disadvantageous for the use of the product, so that the present invention adopts a double-layer structure, the inner layer foaming layer can obtain sufficient softness, and the outer layer foaming body can ensure that the surface of the product is free of voids, thereby ensuring the uniformity of the working surface and the printing quality. Besides the semi-electric performance, the foaming layer is added with foaming materials to realize the cross-linking foaming of the materials in the forming process. Of course, the foaming and the vulcanization crosslinking can be simultaneously carried out by matching the sulfur speed of different vulcanizing agents so as to realize the simultaneous foaming and vulcanization.

Drawings

The invention may be better understood by referring to the following description in conjunction with the accompanying drawings, in which like reference numerals are used throughout the figures to indicate like or similar parts. The accompanying drawings, which are incorporated in and form a part of this specification, illustrate preferred embodiments of the present invention and, together with the detailed description, serve to further explain the principles and advantages of the invention. In the drawings:

FIG. 1 is a schematic view showing the structure of an embodiment of a transfer roller according to the present invention, in which the resistance value is stable and the long life is maintained; wherein, the corresponding reference numbers of each part are as follows: 1. a mandrel; 2. a foamed elastic layer; 3. outer solid elastic layer, 4, surface coating.

Detailed Description

Embodiments of the present invention will be described below with reference to the accompanying drawings. Elements and features depicted in one drawing or one embodiment of the invention may be combined with elements and features shown in one or more other drawings or embodiments. It should be noted that the figures and description omit representation and description of components and processes that are not relevant to the present invention and that are known to those of ordinary skill in the art for the sake of clarity.

Referring to fig. 1, the transfer roller with stable resistance value of the present invention comprises an inner core shaft 1, a middle foamed elastic layer 2 wrapped outside the core shaft 1, an outer solid elastic layer 3 wrapped outside the foamed elastic layer 2, and a surface coating layer 4 coated outside the outer solid elastic layer 3.

Wherein, the foaming elastic layer 2 is formed by mixing a base material and an auxiliary material, the base material can be a combination of ECO and NBR, and can also be realized by EPDM or SBR, the auxiliary material comprises inorganic filler, vulcanizing agent, accelerant and conductive agent, when the base material is the combination of ECO and NBR, the ECO accounts for 20-80% of the whole weight of the base material, the NBR accounts for 80-20%, when the base material is EPDM, the EPDM accounts for 100%; when the substrate is SBR, the SBR accounts for 100 percent. The conductive agent is realized by alkyl trimethyl ammonium perchlorate, and accounts for 1-5% of the total weight of the base material and the auxiliary material.

The outer layer entity elastic layer 3 is formed by mixing a base material and an auxiliary material, wherein the base material is a combination of ECO and NBR, the auxiliary material comprises an inorganic filler, a vulcanizing agent, an accelerant and a conductive agent, the ECO in the base material accounts for 20-80% of the total weight of the base material, and the NBR accounts for 80-20% of the total weight of the base material. The conductive agent is realized by conductive carbon black, and the conductive agent accounts for 10-28% of the total weight of the base material and the auxiliary material.

The surface coating 4 is a polyurethane coating, and can be coated on the surface of the outer layer entity elastic layer 3 by adopting a dip coating or spray coating mode.

The following table shows 6 specific example formulations for making the above transfer roller:

note that the symbols for evaluation of pictorial representation have the following meanings, ◎ super excellent, ○ good, △ general, and Xbad.

The processing flow of 6 cases as listed above is: extruding an inner layer (foaming elastic layer) and foaming and vulcanizing for shaping, cutting off a foaming pipe, grinding the foaming pipe, extruding an outer layer (an outer layer solid elastic layer), cutting off the outer layer, sleeving the foaming pipe into a shaft core, sleeving the outer layer on the foaming layer, grinding the outer layer, dip-coating, baking a surface coating, cutting off two ends, and checking a finished product.

As described in examples 1, 2 and 3, the inner substrate is EPDM, the outer substrate is NBR + ECO, the amount of amine salt added in the formulation of the outer layer is 1.5 parts, 2.0 parts and 3.0 parts, and the overall resistivity is 1.05, 1.055 and 1.053, while the corresponding example 4, 5 and 6, the inner NBR + ECO foamed layer has overall resistivity of 1.03, 1.032 and 1.031, which is smaller than the overall resistivity change, i.e. the resistivity is uniform, and the inner EPDM foamed layer may be electron conductive and the electron conductivity is more difficult to disperse, so the difference of the resistivity is larger. But it is only in the inner layer, and the influence is limited, and its outer layer is NBR + ECO, and the material itself has conductivity, and is ion-conductive, and this type of conductivity is uniform. Therefore, the resistance multiplying power of 6 implementation cases is within 1.3 of the industry requirement.

In the 6 cases, the amount of amine salt added is small in the rise of energization when the amount of amine salt added is large, and the rise of energization is small even when the amount of amine salt added is constant, and the image evaluation corresponding thereto is general in the case of HH. This may be that the HH condition resistance itself is small, and in addition, the resistance becomes small at the energization resistance, which is disadvantageous for printing. This is also seen from the results of the continuous printing test, and the increase in the amount of the amine salt to some extent leads to the adverse effect of printing. Therefore, the amount of the amine salt to be added is controlled within a certain range.

As is known, the problem of surface powder accumulation can be solved in printing, and many poor printing can be solved, but the actual situation is that the powder accumulation condition exists on the surface more or less as long as printing is carried out, and if the foam is pure foam, the accumulated powder falls into holes due to pores, and is accumulated for a long time, the conductive effect and the hardness degree of the foam can be changed, so that the printing is influenced. And the solid material and the surface external coating are not easy to accumulate powder. The powder accumulation condition of the powder is substantially improved in the 6 cases.

In the

above cases

1, 2 and 3, the inner layer of EPDM is a foamed conductive material, and the outer layer is NBR + ECO conductive material, but the EPDM conductive material has a smaller resistance than the outer layer conductive material. In the above cases 4, 5 and 6, the inner layer is NBR + ECO foam, the outer layer is NBR + ECO conductive material, and the resistance of the inner layer foam conductive material is lower than that of the outer layer conductive material. That is, the overall resistance is controlled by the outer layer.

The inner layer of the

aforementioned cases

1, 2 and 3 is EPDM, which is inexpensive, and has a cost advantage compared with cases 4, 5 and 6.

The outer coating of the

cases

1, 2, 3, 4, 5 and 6 can be a polyurethane coating or a polyurethane coating with teflon powder added.

To illustrate the effectiveness of the present application, comparative experimental cases are now listed in the following table:

comparative example 1 shows that the transfer roller is a single-layer EPDM foam, and since the EPDM is conductive, an electron conductive material is added, and the electron conductive material is difficult to disperse, and the product resistivity ratio is 2.18, all the defects were evaluated because only a single layer is exposed to the outside of the foamed cells, and dust is likely to accumulate in the cells. The powder accumulation condition is not good.

As can be seen from comparative example 2, it is also a single layer NBR/ECO foam, because the material itself has semiconductive, all aspects of the performance can reach the product requirements. Therefore, this example is also a production example of a conventional transfer roller. However, the defects that the foam holes are exposed and dust is easy to fall are overcome, and the defect directly results in that the printing service life is not too long, namely the continuous printing effect is not good.

The situation of comparative example 2 is effectively solved in the subsequent comparative examples. Since the latter comparative examples are of a two-layer construction, the inner layer being a foam and the outer layer being a solid elastomeric layer, equivalent to a protective layer.

Comparative example 3 is an inner EPDM foamed layer and an outer NBR/ECO solid layer, but the evaluation of the coating at room temperature and high temperature was not good because the amount of amine salt added was 5 parts, and this is also shown in comparative example 7. Therefore, the amount of the amine salt added cannot exceed 5 parts.

Comparative example 4 was identical to the case shown in the table except that the hardness of the inner layer was lowered and the overall hardness of the product was lowered. The image effect is not optimal for HH. This may be low hardness, high friction coefficient under HH condition, large resistance to paper, and affect image quality, but not so much.

Comparative example 5, as in the case of table, is excellent in all aspects, and is described in table one.

Comparative example 6 is identical to the case of the table, and the hardness of the inner layer is high and the overall hardness is high. The hardness of the material is high, and the hardness is higher under the LL environment, so that the deformation adaptability of the material is influenced, and the image effect is influenced. Therefore, the hardness of such products should not be too high.

In the foregoing description of specific embodiments of the invention, features described and/or illustrated with respect to one embodiment may be used in the same or similar way in one or more other embodiments, in combination with or instead of the features of the other embodiments.

It should be emphasized that the term "comprises/comprising" when used herein, is taken to specify the presence of stated features, elements, steps or components, but does not preclude the presence or addition of one or more other features, elements, steps or components.

While the present invention has been disclosed above by the description of specific embodiments thereof, it should be understood that all of the embodiments and examples described above are illustrative and not restrictive. Various modifications, improvements and equivalents of the invention may be devised by those skilled in the art within the spirit and scope of the appended claims. Such modifications, improvements and equivalents are also intended to be included within the scope of the present invention.

Claims

1. A transfer roller with a stable resistance value, characterized in that: the core shaft comprises an inner layer, a middle layer of foaming elastic layer wrapped outside the core shaft and an outer layer of entity elastic layer wrapped outside the foaming elastic layer;

the foamed elastic layer is formed by mixing a base material and an auxiliary material, wherein the base material is a combination of ECO and NBR or EPDM or SBR, the auxiliary material comprises an inorganic filler, a vulcanizing agent, an accelerant and a conductive agent, when the base material is the combination of ECO and NBR, the ECO accounts for 20-80% of the whole weight of the base material, the NBR accounts for 80-20%, and when the base material is EPDM, the EPDM accounts for 100%; when the base material is SBR, the SBR accounts for 100 percent;

the outer-layer entity elastic layer is formed by mixing a base material and an auxiliary material, wherein the base material is a combination of ECO and NBR, the auxiliary material comprises an inorganic filler, a vulcanizing agent, an accelerant and a conductive agent, the ECO in the base material accounts for 20-80% of the total weight of the base material, and the NBR accounts for 80-20% of the total weight of the base material.

2. The transfer roller of claim 1, wherein: the conductive agent of the foaming elastic layer is alkyl trimethyl ammonium perchlorate, and the conductive agent accounts for 1-5% of the total weight of the base material and the auxiliary material.

3. The transfer roller of claim 1, wherein: the conductive agent of the outer layer solid elastic layer is conductive carbon black, and the conductive agent accounts for 10-28% of the total weight of the base material and the auxiliary material.

4. The transfer roller of claim 1, wherein: the mandrel of the transfer roller is in interference fit with the foaming elastic layer, and the foaming elastic layer is in interference fit with the outer-layer entity elastic layer.

5. The transfer roller of claim 1, wherein: the volume resistance value of the outer solid elastic layer is between 0.1M omega and 100M omega.

6. The transfer roller of claim 1, wherein: the volume resistance value of the foaming elastic layer is smaller than that of the outer solid elastic layer.

7. The transfer roller of claim 1, wherein: the overall volume resistance of the transfer roller is between 0.1M omega and 100M omega.

8. The transfer roller of claim 1, wherein: the thickness range of foaming elastic layer is 2 ~ 6mm, the thickness range of outer entity elastic layer is 0.5 ~ 2 mm.

9. The transfer roller of claim 1, wherein: the outer layer solid elastic layer is also provided with a surface coating.

10. A method for manufacturing a transfer roller with stable resistance value is characterized in that: compounding according to the formulation requirements of the transfer roller as claimed in claims 1 to 9, the raw materials are subjected to rubber mixing → washing mandrel → extrusion of the intermediate foam layer → extrusion of the outer layer of the solid elastomer layer → foam tube, cutting of the solid tube → nesting of the foam layer in the mandrel → grinding → nesting of the outer layer in the foam layer → baking → grinding → dip coating → cutting of both ends.