JPH0641434A - Silicone rubber composition - Google Patents

Abstract

PURPOSE:To provide the silicone rubber composition desirable for the production of, e.g. a toner development roll or a toner carrying roll used in the development part of a duplicating machine or an LBP. CONSTITUTION:The composition is prepared by adding spherical particles of a mean particle diameter of 1-500mum to an organic peroxide-reaction typed semiconductive silicone rubber composition comprising a diorganopolysiloxane, a reinforcing filler, carbon black and a nonacylic organic peroxide.

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 producing a developing roll, a toner transporting roll, etc. used in a toner developing portion of a copying machine or a laser beam printer (LBP).

[0002]

2. Description of the Related Art A developing roll and a toner transporting roll used in a copying machine of an electrophotographic copying machine and a toner developing portion of an LBP have excellent heat resistance, cold resistance and low compression set characteristics. Therefore, the roll made of this silicone rubber conveys the toner by the degree of unevenness of the surface state of this roll and / or the electric conveying force, and conveys the conveyed toner to the photosensitive drum (OP
Since it is a mechanism of transferring to C), there is a problem that a difference in the degree of unevenness of the roll surface causes a difference in toner conveying force.

[0003]

Therefore, for this roll, the surface roughness of the roll surface, the shape of the irregularities, etc. are controlled by means such as grinding, and the surface of the roll is ground by this grinding or the like. Even if the roughness and the shape of the unevenness are delicately controlled by adjusting the conditions during grinding, the roll surface thus obtained will wear when the roll obtained in this way is used for a long time, and the surface condition of the roll (surface roughness However, there is a drawback in that the shape of the unevenness changes with time and thus its ability decreases.

[0004]

SUMMARY OF THE INVENTION The present invention relates to a silicone rubber composition capable of solving the above problems and drawbacks, which comprises diorganopolysiloxane, reinforcing silica filler, carbon black and The organic peroxide-reactive semiconductive silicone rubber composition comprising a non-acyl organic peroxide has an average particle size of 1 to 500.
It is characterized by adding spherical particles of μm.

[0005]

That is, as a result of various investigations by the inventors of the present invention to develop a silicone rubber roll which does not change with time even after long-term use, the present inventors have found that this is a silicone rubber for producing this rubber roll. The composition is a conventionally known organic peroxide reaction type, but by adding spherical particles having an average particle size of 1 to 500 μm to the composition, the surface roughness of a roll made from this silicone rubber composition can be obtained. It was found that the shape of the unevenness is controlled, and that it does not change over time after long-term use, and thus it can be used for a long time as a developing roll and a toner conveying roll. After confirming that, the present invention was completed by conducting research on the type and addition amount of the spherical particles used here. This will be described in more detail below.

[0006]

The present invention relates to a silicone rubber composition, particularly a silicone rubber composition for producing a developing roll, a toner conveying roll and the like, which comprises a diorganopolysiloxane, a reinforcing silica filler and carbon black. And an organic peroxide-reactive semiconductive silicone rubber composition comprising a non-acyl organic peroxide and spherical particles having an average particle size of 1 to 500 μm. However, when a roll is manufactured using this silicone rubber composition, the roll is given appropriate surface roughness and unevenness, and this does not change over time even if used for a long time. The advantage of being able to

In general, the silicone rubber composition of the present invention is usually molded under pressure by a method such as compression molding, injection molding, transfer molding, etc., and when these molding methods are used, a spherical shape is obtained. When the particles fall off from the obtained molded product, the toner may enter from the dropped off parts and the quality of the printing may be greatly deteriorated.However, when the molding is carried out under sufficient pressure, the toner may be included in the composition. The adhesive force between the spherical particles and the rubber composition is increased, which has the advantage that problems such as falling of the spherical particles from the rubber composition due to aging can be solved. A reactive type is used.

Therefore, the first component is a diorganopolysiloxane, which is rubbery at room temperature.
A diorganopolysiloxane having at least two alkenyl groups in one molecule is preferable, and examples thereof include dimethylsiloxane / methylvinylsiloxane copolymer and dimethylsiloxane / methylphenylsiloxane.
Methyl vinyl siloxane copolymer, methyl (3,3,3
-Trifluoropropyl) siloxane / methyl vinyl siloxane copolymer, dimethyl siloxane / methyl allyl siloxane copolymer and the like are exemplified. These have silanol groups, trimethyl silyl groups, dimethyl vinyl silyl groups, methyl phenyl vinyl at the molecular chain terminals. It is said to be blocked with a silyl group.

The reinforcing silica filler as the second component used here is added to improve the physical properties of the silicone rubber, and examples thereof include fumed silica and wet silica. However, these may be those whose surface is treated with silane, siloxane or the like to make them hydrophobic. The addition amount may be in the range of 20 to 60 parts by weight with respect to 100 parts by weight of the above diorganosiloxane.

Next, the carbon black as the third component used here is used as a conductivity-imparting agent for making the silicone rubber composition of the present invention semiconductive. It is preferable that the resistance region of semiconductivity is 10 ³ Ωcm to 10 ⁹ Ωcm, although the kind and particle size may be the same. If it is less than 10% by weight, it is difficult to set this resistance region even if highly conductive carbon black is used, and it is difficult to uniformly disperse the carbon black in the binder, resulting in the disadvantage that resistance unevenness occurs. %, The processability and general physical properties of the composition will be deteriorated, so the addition amount should be in the range of 2-75% by weight, preferably 5-50% by weight.

The non-acyl organic peroxide as the fourth component used here is a curing agent for curing the silicone rubber composition. However, if this is an acyl-based one such as benzoyl peroxide or 2,4-dichlorobenzoyl peroxide, the vulcanization inhibition may be caused by carbon black in the silicone rubber composition, so a non-acyl-based one may be used. It is necessary to use dicumyl peroxide, di-t-butyl peroxide, 2,5-dimethyl-2,5 (t-butylperoxy) hexane, 2,5
-Dimethyl-2,5-di (t-butylperoxy) hexene and the like are exemplified. The activation energy of this compound is preferably 33 kcal / mol or more, and the addition amount may be in the range of 0.2 to 5.0% by weight with respect to dimethylsiloxane as the first component.

It is optional to add a predetermined amount of auxiliary material such as conductive fiber, conductive metal or metal oxide, heat resistance improver and pigment to the silicone rubber composition.

The silicone rubber composition of the present invention is obtained by adding spherical particles to the above-mentioned silicone rubber composition. If the average particle diameter of the spherical particles is less than 1 μm, the particles will be non-uniformly dispersed. Therefore, it is difficult to obtain a roll surface having a uniform uneven state, and since the unevenness of the roll surface is too small, the toner transport amount and transport force are reduced, resulting in an image when printed. The density of the particles becomes thin, and this is the average particle size of 500μ.
If it exceeds m, concavities and convexities on the roll surface become too large on the contrary, so that the toner conveyance amount and conveyance force become large, and as a result, the image density at the time of printing becomes high. There is, therefore, an average particle size of 1 to 500
The average particle size is preferably in the range of 1 to 100 μm.

The spherical particles may be any particles having a spherical shape, and examples thereof include spherical silica, spherical silicone rubber balls, spherical carbon, and particles having a hollow structure thereof. When the roll is to be used in contact with a photosensitive drum (OPC), in order to prevent the spherical particles from damaging the OPC, it is preferable to use silicone rubber balls or particles having hollows rather than hard particles. Good to do.

If the amount of the spherical particles is less than 5 parts by weight based on 100 parts by weight of the above-mentioned organic peroxide-reactive silicone rubber composition, the dispersion density of the granular particles is too low, and the toner carrying force is low. It tends to be weak, and if it is more than 200 parts by weight, the processability tends to be poor and general physical properties tend to deteriorate, so the range may be 5 to 200 parts by weight, but the preferred range is 5 to 100 parts by weight. .

The silicone rubber composition to which the spherical particles are added may be molded under pressure such as compression molding, injection molding, transfer molding, etc. to obtain a molded product, which may be molded at 150 to 250 ° C. It is preferable to remove the decomposition residue of the organic peroxide and the low molecular weight siloxane by secondary heating with hot air vulcanization for 24 hours. Since this silicone rubber composition has spherical particles having an average particle size of 1 to 500 μm and has an appropriate hardness, when a roll is produced from the silicone rubber composition to which the spherical particles are added, Has a suitable surface roughness and unevenness on its surface, and is therefore useful as a developing roll for a copying machine and a toner transporting roll, which gives the advantage that it does not change over time even if used for a long time. To be

[0017]

EXAMPLES Next, examples and comparative examples of the present invention will be described. Example Organic peroxide reactive type silicone rubber compound K
100 parts by weight of E-78VBS [trade name of Shin-Etsu Chemical Co., Ltd.], 40 parts by weight of carbon black thermal black [trade name of Asahi Carbon Co., Ltd.], fumed silica filler, Aerosil 200 [Japan Aerosil] Co., Ltd. product name] 2
5 parts by weight and 20 parts by weight of spherical particles / silicone rubber balls having an average particle size of 20 μm [trade name of Shin-Etsu Chemical Co., Ltd.] were added and kneaded with a pressure kneader to prepare a silicone rubber composition. The silicone rubber ball used here is a low temperature curable addition reaction type silicone rubber, KE-.
106 Add 10 parts by weight of curing catalyst C-RG [product name of the same company] to 100 parts by weight of LTV [product name of Shin-Etsu Chemical Co., Ltd.] and fill it with water held at 97 ° C with a height of 20 cm. It was dropped one by one in the liquid tank and vulcanized and cured.

Then, the silicone rubber composition was
5-dimethyl-2,5-bis (t-butylperoxy)
After adding 1.5 parts by weight of hexane, pour this into a cylindrical cavity together with a stainless or iron shaft to make a roll with a diameter of 20 mm, and place it in a gear oven.
After heat-treating at 00 ° C for 2 hours and grinding with a cylindrical grinder under the grinding conditions shown in Table 1 to an outer diameter of 18.0 mm, a roll having the surface roughness shown in Table 1 was obtained. When a printing test was performed using this, all of them gave an initial proper image, and when a 13,000 sheet passing test was performed on this, there was no significant difference in image quality. It was

[0019]

[Table 1]

Comparative Example A silicone rubber composition was prepared in the same manner as in Example 1 except that the particulate particles / silicone rubber balls in the above Example were not added, and a roll was prepared in the same manner as in Example 1 Similarly, after the post-heat treatment, a cylindrical grinder was used to grind to an outer diameter of 18.0 mm under the grinding conditions shown in Table 2, and a roll having the surface roughness shown in Table 2 was obtained. When a printing test was conducted with the conditions, conditions 1 and 3 caused bleeding at the time of printing at the initial stage, and conditions 2 and 4 gave a proper image at the initial stage in the printing test. In a paper test, image bleeding occurred at 3,000 sheets and the image quality was significantly degraded.

[0021]

[Table 2]

[0022]

INDUSTRIAL APPLICABILITY The present invention relates to a silicone rubber composition, and more particularly to a silicone rubber composition suitable for producing a developing roll, a toner transporting roll and the like used in the developing part of a toner of a copying machine or LBP. As described above, this is an average of organic peroxide-reactive semiconductive silicone rubber compositions composed of diorganopolysiloxane, reinforcing silica filler, carbon black and non-acyl organic peroxide. It is characterized by adding spherical particles having a particle size of 1 to 500 μm. When a silicone rubber roll is produced from the silicone rubber composition thus produced, this roll has an appropriate surface roughness. Since it has unevenness and unevenness, it is useful as a developing roll and a toner conveying roll of a copying machine. Advantage that does not cause a change is given.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location C08K 5/14 7/22

Claims (1)

[Claims] 1. An organic peroxide-reactive semiconductive silicone rubber composition comprising a diorganopolysiloxane, a reinforcing silica filler, carbon black and a non-acyl organic peroxide having an average particle size of A silicone rubber composition comprising spherical particles of 1 to 500 μm added.