JP3320109B2 - Silicone rubber composition for rolls used in copiers and printers - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a silicone rubber composition,
In particular, the present invention relates to a silicone rubber composition suitable for a developing roll used for a toner developing portion of a copying machine or a laser beam printer (LBP), a toner conveying roll, and the like.

[0002]

2. Description of the Related Art A developing roll and a toner conveying roll used in a copying machine of an electrophotographic copying machine and a developing portion of LBP toner are excellent in heat resistance, cold resistance and low compression set characteristics. Therefore, an alkenyl group-containing organopolysiloxane containing at least two silicon-bonded alkenyl groups in one molecule, an organohydrogen containing at least two silicon-bonded hydrogen atoms in one molecule. Genpolysiloxane, carbon black for making the composition semiconductive with a resistance value of 10 ³ Ωcm to 10 ⁹ Ωcm, and alkenyl groups in the alkenyl group organopolysiloxane and hydrogen atoms of the organohydrogenpolysiloxane (≡ And a platinum-based catalyst for performing an addition reaction with SiH groups).

However, the rubber roll made of the silicone rubber transports the toner with a degree of unevenness of the surface state of the rubber roll and / or an electrical transport force, and transfers the transported toner to a photosensitive drum (OPC). Therefore, there is a problem that a difference occurs in the toner conveying force due to a subtle difference in the degree of unevenness of the roll surface.

[0004]

For this reason, the surface roughness and the shape of the unevenness of the rubber roll surface are controlled by means of grinding or the like, and the rubber roll surface is controlled by such grinding or the like. Even if the roughness and unevenness of the surface are delicately controlled by adjusting the grinding conditions, the rubber roll obtained in this way will wear out over a long period of time, and the surface condition of the rubber roll (surface roughness) There is a drawback that the ability of the unevenness changes with time to reduce its ability.

[0005]

SUMMARY OF THE INVENTION The present invention relates to a silicone rubber composition for a roll of a copier / printer which can solve such problems and drawbacks, comprising an alkenyl group-containing organopolysiloxane, A semi-conductive addition reaction-curable silicone rubber composition comprising an organohydrogenpolysiloxane, carbon black and a platinum-based catalyst is added dropwise to water maintained at a high temperature and having an average particle diameter of 1 to 500 µm by dropping. It is characterized in that it is formed by adding a sulfur-cured spherical silicone ball and a silane coupling agent and injecting into a mold to mold.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present inventors have conducted various studies to develop a rubber roll that does not change over time even after long-term use. As a result, a silicone rubber composition for producing this rubber roll was developed. Conventionally known addition reaction-curable type, which has an average particle size of 1 to 500 μm
If the spherical particles of m and the silane coupling agent are added, the surface roughness of the rubber roll made from this silicone rubber composition, the shape of the unevenness, etc. are controlled, and this does not change with time even after long use. Therefore, according to this, it has been confirmed that this can be used for a long time as a developing roll and a toner transporting roll, and it has been confirmed that the spherical particles and the silane coupling agent used here can be used. The present invention was completed by conducting research on the amount of addition, etc. This will be described in more detail below.

The present invention relates to a silicone rubber composition, and more particularly to a silicone rubber composition for producing a developing roll, a toner conveying roll and the like, which comprises an alkenyl group-containing organopolysiloxane, an organohydrogenpolysiloxane. Spherical silicone vulcanized and cured by dropping into semi-conductive addition-reaction-curable silicone rubber composition comprising carbon black and platinum-based catalyst, having an average particle size of 1 to 500 μm, and kept at high temperature It is characterized by being formed by adding a ball and a silane coupling agent, and being molded by injecting into a mold.When a rubber roll is manufactured using this silicone rubber composition, Is given an appropriate surface roughness and unevenness. Advantage is provided that can use while.

[0008] The silicone rubber composition of the present invention is a semiconductive addition-curable composition. The reason for making this silicone rubber curable by addition reaction is that it is generally known that an addition reaction curable silicone rubber composition is used for extrusion molding. This is because the productivity is higher and the cost is lower than when using a batch method such as compression molding using a mold or injection molding.Therefore, compression molding or injection molding using a special mold is used. In this case, due to the difference in the flow of rubber at the upper and lower joints of the mold, this part has a higher rubber hardness than the other parts, and the resistance value is abnormal, and the rubber is easily chipped due to overcure However, these problems can be solved by extrusion molding using an addition-curable silicone rubber composition.

Accordingly, this is an alkenyl group-containing organopolysiloxane in which the first component has at least two alkenyl groups bonded to silicon atoms in one molecule, for example, dimethylvinylsilyl at both ends of the molecular chain. Group-blocked dimethylpolysiloxane, dimethylsiloxane-methylvinylsiloxane copolymer, methylphenylsiloxane-methylvinylsiloxane copolymer blocked at both molecular chain terminals by methylphenylvinylsilyl group, Methyl (3,3,3-trifluoropropyl) polysiloxane blocked with a vinylsilyl group may be used.

The organohydrogenpolysiloxane as the second component used herein has at least two hydrogen atoms (≡SiH groups) bonded to silicon atoms in the molecule. Examples are methylhydrogenpolysiloxane in which both ends of the molecular chain are blocked with a trimethylsilyl group, dimethylsiloxane / methylhydrogensiloxane copolymer in which both ends of the molecular chain are blocked with a trimethylsilyl group, tetramethylhydrogencyclotetrasiloxane, etc. However, the amount of the component is 0.3 to 30 parts by weight based on 100 parts by weight of the first component.

Next, the carbon black used as the third component is used as a conductivity-imparting agent for making the silicone rubber composition of the present invention semiconductive. It may be of such kind and particle size, and the semiconductive resistance region is 10 ³ Ωcm to 10 ⁹ Ωcm.
It is desirable that If the total amount of the first component and the second component is less than 2 parts by weight with respect to the total amount of 100 parts by weight, even if carbon black having high conductivity is used, it is difficult to obtain the resistance region, and carbon black is contained in the binder. Is difficult to disperse uniformly, resulting in the disadvantage of causing uneven resistance. If the amount exceeds 75 parts by weight, the processability and general physical properties of the composition are reduced, so that the range is 2 to 75 parts by weight, preferably 5 to 50 parts by weight. It is preferable to use parts by weight.

The platinum-based catalyst used as the fourth component used herein is the same as the alkenyl group in the first component described above but also the second component.
A catalyst for promoting an addition reaction with a hydrogen atom (≡SiH group) in the component, which may be a known catalyst, and thus includes platinum black, platinum sponge, platinum (II) chloride, chloroplatinic acid Chloroplatinic acid and a monohydric alcohol, a complex of chloroplatinic acid with an olefin or vinyl siloxane, platinum bisacetoacetate, a palladium-based catalyst, a rhodium-based catalyst, and the like. May be 1 to 1,000 ppm.

The silicone rubber composition contains an appropriate amount of fumed silica, wet silica, a reinforcing filler obtained by hydrophobating them, an organic nitrogen compound,
It is optional to add an additional reaction rate retarder such as an alkyne compound or an organic tin compound, a conductive fiber, a conductive metal or metal oxide, a heat resistance improver, a pigment, and other auxiliary materials.

The silicone rubber composition for a roll of a copying machine / printer of the present invention is obtained by adding a spherical silicone ball as a spherical particle and a silane coupling agent to the above silicone rubber composition. When the average particle diameter is less than 1 μm, the toner is liable to be non-uniformly dispersed, so that it is difficult to obtain a rubber roll surface having a uniform unevenness, and the rubber roll surface has too small unevenness. The conveyance amount and the conveyance force are reduced, and as a result, the density of the image when printing is reduced. On the other hand, if the average particle diameter exceeds 500 μm, the unevenness on the surface of the rubber roll becomes too large, so that the toner transport amount and the transport force are increased, and the image density when printing is consequently increased. The average particle size is 1 to 500 μm
m, but the preferred range of the average particle size is 1 to 100 μm.

The spherical particles may be of any type as long as they have a spherical shape, such as spherical silica, spherical silicone balls, spherical carbon or those having a hollow structure. When used in applications that come into contact with photosensitive drums (OPCs), these should be silicone balls or hollow particles rather than hard particles to prevent the spherical particles from damaging the OPC. Is good.

When the amount of the spherical particles is less than 5 parts by weight, based on 100 parts by weight of the above-mentioned addition-reaction-curable silicone rubber composition, the dispersion density of the granular particles is too low, so that the toner conveying force is weakened. If the amount is more than 200 parts by weight, the workability will deteriorate and the general physical properties will decrease.
The range may be in parts by weight, but the preferred range is 5 to 5.
100 parts by weight.

The silane coupling agent used here may be a known one, such as vinyltrichlorosilane, vinyltris (β-methoxyethoxy) silane, vinyltrimethoxysilane, vinyltriethoxysilane,
γ-methacryloxypropyltrimethoxysilane, β-
(3,4-epoxycyclohexyl) ethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, N-β (acinoethyl) -γ-aminopropylmethoxysilane, N- β (asinoethyl) -γ-aminopropylmethyldimethoxysilane, γ-aminopropyltriethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, γ-mercaptopropylmethoxysilane, γ-chloropropyltrimethoxysilane, etc. Is done.

Regarding the effect of the addition of the silane coupling agent, when the silane coupling agent is not added, the adhesion between the spherical particles in the present composition and the rubber is insufficient, and the rubber roll made from the rubber roll with time is The spherical particles are changed and fall off from the surface of the rubber composition, and when toner or the like enters the place where the spherical particles fall off and printing is performed, a cause such as bleeding is caused.When a silane coupling agent is added, Since the adhesion between the spherical particles and the rubber component is sufficient, the above-mentioned problem of the spherical particles falling off is prevented, and the silane coupling agent is also involved in the adhesiveness between the core metal and the rubber. There is also an effect that there is no need to provide an adhesive layer on gold and bond the rubber layer and the core metal.

If the amount of the silane coupling agent is less than 0.2 parts by weight per 100 parts by weight of the addition-curable silicone rubber composition, the amount of the rubber layer and the spherical particles and / or the rubber composition and the core metal may be reduced. Adhesive strength tends to be low, 10
When the amount is more than the weight part, the tackiness of the rubber composition becomes large, and the processability may be remarkably reduced.
The range may be 10 parts by weight, but the preferred range is
0.5 to 5 parts by weight.

In the silicone rubber composition to which the spherical particles and the silane coupling agent are added, the spherical particles have an average particle diameter of 1 to 500 μm and have an appropriate hardness. Since it is intended to improve the adhesive force between the spherical particles and the rubber layer and / or the adhesive force between the rubber composition and the core metal, when a roll is manufactured from the silicone rubber composition to which the rubber composition is added, Since the roll has a moderate surface roughness and irregularities on its surface, it is useful as a roll for developing a copier and a roll for transporting toner, and has the advantage that it does not change over time even when used for a long time. Given.

[0021]

Next, examples of the present invention and comparative examples will be described. Example 100 parts by weight of silicone raw rubber, KE-78VBS [trade name of Shin-Etsu Chemical Co., Ltd.], 40 parts by weight of carbon black and thermal black [trade name of Asahi Carbon Co., Ltd.], fumed silica filler Aerosil 200 [trade name, manufactured by Nippon Aerosil Co., Ltd.] 25 parts by weight, average particle size 20μ
m, and kneaded with a pressure kneader to prepare a silicone rubber composition, and then a silane coupling agent KBM50
3 [Shin-Etsu Chemical Co., Ltd. product name] 4.0 parts by weight was added and kneaded with a mixing roll. The silicone rubber ball is a low-temperature curable liquid addition reaction type silicone rubber, KE-106 LTV (trade name, manufactured by Shin-Etsu Chemical Co., Ltd.). 100 parts by weight of a curing catalyst, G-RG (trade name, manufactured by the company)
10 parts by weight were added, and this was dropped into a 20-cm-high liquid bath filled with water maintained at 97 ° C. and vulcanized and cured.

Next, 2.5 parts by weight of a complex salt of chloroplatinic acid and vinyl siloxane was added to the silicone rubber composition, and the mixture was poured into a cylindrical cavity together with a stainless steel or iron shaft to form a 20 mmφ diameter. A rubber roll was made, heat treated at 200 ° C. for 2 hours in a gear oven, and ground to an outer diameter of 18.0 mm with a cylindrical grinder under the grinding conditions shown in Table 1, and the surface roughness as shown in Table 1 was obtained. Was obtained, and a printing test was carried out using these rubber rolls. All of these gave an initial proper image, and the results were 10,000
When a sheet passing test was performed, there was no significant difference in image quality between the sheets.

[0023]

[Table 1]

Comparative Example A silicone rubber composition was prepared in the same manner as in the above example except that the particulate particles / silicone rubber ball and the silane coupling agent were not added, and a silicone rubber composition was prepared. After making a rubber roll in the same manner and post-heat treatment in the same manner, grinding was performed to an outer diameter of 18.0 mm with a cylindrical grinder under the grinding conditions shown in Table 2, and a rubber roll having a surface roughness as shown in Table 2 was obtained. Therefore, when a printing test was carried out using this, bleeding occurred during printing at the initial stage under the conditions 1 and 3, and under the conditions 2 and 4, a proper image was obtained at the initial stage in the printing test. However, in the paper-passing test, bleeding occurred on 3,000 sheets, and the image quality was significantly reduced.

[0025]

[Table 2]

[0026]

Industrial Applicability The present invention relates to a silicone rubber composition, and more particularly to a silicone rubber composition which is suitable for producing a developing roll, a toner transporting roll, and the like used for a copier or an LBP toner developing portion. This is, as described above, a semiconductive addition reaction-curable silicone rubber composition comprising an alkenyl group-containing organopolysiloxane, an organohydrogenpolysiloxane, carbon black, and a platinum-based catalyst, having an average particle size of 1%. ~
It is formed by adding a silane coupling agent and a spherical silicone ball vulcanized and cured by dripping into water kept at a high temperature of 500 μm, and is molded by injection into a mold. However, when a rubber roll is manufactured from the silicone rubber composition thus produced, the rubber roll has an appropriate surface roughness and irregularities, and is considered to be useful as a developing roll and a toner conveying roll of a copying machine. In addition, this has the advantage that it does not change over time, even if used for a long time.

────────────────────────────────────────────────── ─── Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI // (C08L 83/07 C08L 83:05) 83:05) C08K 5/54 (56) References JP-A-2-41362 ( JP, A) JP-A-62-263256 (JP, A) JP-A-5-239361 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C08L 83/00-83/16

Claims (1)

(57) [Claims] 1. A semiconductive addition-reaction-curable silicone rubber composition comprising an alkenyl group-containing organopolysiloxane, an organohydrogenpolysiloxane, carbon black and a platinum-based catalyst, having an average particle size of 1 to 50.
By dropping into 0 μm hot water
Molded by adding a vulcanized and cured spherical silicone ball and a silane coupling agent and injecting it into a mold
Roll sheet <br/> silicone rubbers composition copiers and printers characterized and Dearuko.