JP3344233B2 - Silicone rubber composition for feeding roll or developing roll, and feeding roll and developing roll - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a silicone rubber composition capable of controlling the surface of a roll to be positively charged when a paper feed roll or a developing roll is manufactured, and particularly, to a feed capacity when a paper feed roll is used. The present invention relates to a paper feeding roll and a developing roll which are capable of suppressing a decrease in frictional force during aging while maintaining durability and, when used as a developing roll, are excellent in various functions such as giving excellent toner chargeability.

[0002]

2. Description of the Related Art As a rubber material for office machines, there are a paper feed roll material and a development roll material. Various materials such as urethane, ethylene propylene, and natural rubber have been used, and composite materials thereof have also been proposed.

[0003] However, at present, in these materials, the characteristics required of the paper feed material (high friction with paper,
There is no material which sufficiently satisfies low hardness, especially maintenance of high frictional force due to aging, and the development of a material excellent in these characteristics is desired.

On the other hand, in a developing method using a negative toner, a positively charged material is required for a developing roll in contact with the toner in order to further increase the negative charge of the toner.

Japanese Patent Application Laid-Open No. Sho 59-126576 proposes a pressure roll containing silica treated with a silane coupling agent in order to prevent offset. Not suggested.

The present invention has been made in view of the above circumstances,
It is an object of the present invention to provide a silicone rubber composition for a feed roll or a development roll capable of controlling the roll surface to have a positive charge property, and a feed roll and a development roll in which a cured layer of the composition forms at least the outermost surface. .

[0007]

Means for Solving the Problems and Embodiments of the Invention The present inventors have made intensive studies in order to achieve the above object, and as a result, have as a main component an organopolysiloxane represented by the following average composition formula (1). By adding a positively chargeable reinforcing silica having a specific surface area of 10 m ² / g or more to the silicone rubber composition, the silicone rubber composition is cured by an addition reaction using an organohydrogenpolysiloxane and a platinum-based catalyst in combination. Agent, or organic peroxide catalyst, it can be cured, and the cured product becomes a positively charged material.Furthermore, if a paper feed roll is made using this silicone rubber composition,
The paper powder does not adhere to the roll surface during durability, and it is possible to maintain a high surface frictional force. In addition, when used as a developing roll, the toner can be efficiently negatively charged at the time of contact with the toner. The present inventors have found that a silicone rubber composition that is most suitable for a paper feed roll and a developing roll used in office machines and the like can be obtained, and have accomplished the present invention.

Accordingly, the present invention relates to a silicone rubber composition used for forming at least the outermost surface of a paper feed roll or a developing roll, wherein (i) (A) an organo-organic compound represented by the following average composition formula (1): 100 parts by weight of polysiloxane R ¹ SiO _{(4-n) / 2} (1) (wherein R ¹ is the same or different unsubstituted or substituted monovalent hydrocarbon group, and n is 1.98 to 2) (B) 5 to 70 parts by weight of a positively chargeable reinforcing silica having a specific surface area of 10 m ² / g or more (C) A curing agent containing an organic peroxide catalyst as a curing agent. (Ii) 100 parts by weight of an organopolysiloxane represented by the following average composition formula (1) R ¹ SiO _{(4-n) / 2} (1) Wherein R ¹ is the same or different unsubstituted or substituted monovalent hydrocarbon group And the content of the aliphatic unsaturated group in R ¹ is 0.001 to 5 mol% .n is a positive number of 1.98 to 2.02.) (B) Specific surface area of 10 m ² / g or more 5 to 70 parts by weight of a positively chargeable reinforcing silica of (C) a silicone rubber composition comprising: a curing agent comprising a combination of an organohydrogenpolysiloxane and a platinum-based catalyst; A feed roll or a development roll having a cured layer of the silicone rubber composition on the outermost surface is provided.

Hereinafter, the present invention will be described in more detail. The organopolysiloxane as the component (A) of the silicone rubber composition of the present invention has the following average composition formula R ¹ SiO _{(4-n) / 2} (1) ( In the formula, R is the same or different, unsubstituted or substituted monovalent hydrocarbon group, and n is an integer of 1.98 to 2.02).

Here, in the above formula (1), R ¹ is
Preferably an unsubstituted or substituted monovalent hydrocarbon group having 1 to 10 carbon atoms, more preferably 1 to 8, for example, an alkyl group such as a methyl group, an ethyl group, a propyl group, a butyl group,
Vinyl group, allyl group, butenyl group, alkenyl group such as hexenyl group, cycloalkyl group such as cyclohexyl group,
Aryl groups such as phenyl group and tolyl group, and groups selected from chloromethyl group, trifluoropropyl group, cyanoethyl group, and the like, in which some or all of the hydrogen atoms of these groups are substituted with halogen atoms, cyano groups, and the like. Can be In this case, when the curing agent is an organic peroxide, an aliphatic unsaturated group is not necessarily required, but in the case of an organohydrogenpolysiloxane and a platinum-based catalyst, R ¹ represents an aliphatic unsaturated group (for example, an alkenyl group). It is necessary to have at least two. The content of the aliphatic unsaturated group in R ¹ is
0.001 to 5 mol%, especially 0.025 to 0.5 mol%
It is desirable that Also, n is 1.98 to 2.02
Is a positive number.

The organopolysiloxane of the above formula (1) is basically linear, but may be branched or a mixture of one or more compounds having different molecular structures. Has an average degree of polymerization of 100 to 10,000,
In particular, it is preferably in the range of 3,000 to 8,000.

The above-mentioned organopolysiloxane generally comprises one or more selected organohalosilanes (co).
It can be obtained by hydrolysis or by ring-opening polymerization of a cyclic polysiloxane (such as a siloxane trimer or tetramer) using an alkaline or acidic catalyst.

Next, the positively chargeable reinforcing silica powder as the second essential component of the silicone rubber composition is essential for obtaining the characteristics of the present invention. The specific surface area is 10 m ² / g or more, preferably 50
４００400 m ² / g. Specific surface area is 10m ²
/ G, the mechanical strength of the cured product is reduced.

The above positively chargeable reinforcing silica can be obtained, for example, by subjecting fumed silica (negatively charged) conventionally known as an additive of silicone rubber to aminosilane treatment. There is no particular limitation on the processing method and material as long as it is positively charged when mixed with reduced iron powder by using an apparatus for measuring the chargeability of the powder.

When the above-mentioned positively chargeable reinforcing silica is obtained by treating fumed silica (negatively charged) with aminosilane, specifically, for example, Aerosil A-200 (Nippon Aerosil Co., Ltd., It can be obtained by treating a negatively charged fumed silica having a surface area of 200 m ² / g). (C ₂ H ₅ O) ₃ Si (CH ₂ ) ₃ NH ₂ (CH ₃ O) ₃ Si (CH ₂ ) ₃ NH ₂ (CH ₃ O) ₃ Si (CH ₂ ) ₃ N (CH ₃ ) ₂ (CH ₃ O) ₃ Si (CH ₂ ) ₃ NH (n-Bu) n-B
u: n-butyl group (CH ₃ O) ₃ Si (CH ₂ ) ₃ NH (CH ₂ ) ₂ NH ₂

Further, positively chargeable silica developed for the purpose of improving the fluidity of the toner, for example, RA-200, RA-200H, RA-200HS manufactured by Nippon Aerosil Co., Ltd. can also be used.

The amount of the positively chargeable reinforcing silica is as follows:
100 parts of the first component organopolysiloxane (parts by weight,
The same applies hereinafter) to 5 to 70 parts, preferably 10 to 50 parts.
If the amount is less than 5 parts, the addition amount is too small to obtain a sufficient reinforcing effect, and furthermore, sufficient charging characteristics cannot be obtained. If the amount exceeds 70 parts, processability deteriorates, and mechanical strength increases. Will decrease.

As the curing agent of the component (C), a conventionally known curing agent corresponding to the crosslinking reaction mechanism of the silicone rubber composition can be used. Specifically, an organic peroxide which is a kind of a crosslinking agent, for example, benzoyl peroxide, 2,
4-dichlorobenzoyl peroxide, p-methylbenzoyl peroxide, 2,4-dicumyl peroxide, 2,5-dimethyl-bis (2,5-t-butylperoxy) hexane, di-t-butyl peroxide ,
t-butyl perbenzoate and the like. The amount of the organic peroxide to be added is preferably 0.1 to 5 parts with respect to 100 parts of the organopolysiloxane (A).

When the organopolysiloxane of the component (A) has two or more alkenyl groups directly bonded to a silicon atom, two or more sulfur atoms per molecule are used as a curing agent.
The silicone rubber composition can be cured by using an organohydrogenpolysiloxane having an iH group and performing crosslinking by these addition reaction (hydrosilylation reaction).

In this case, the organohydrogenpolysiloxane may be linear, branched or cyclic, but preferably has a degree of polymerization of 300 or less. Specifically, a diorganopolysiloxane whose terminal is blocked by a dimethylhydrogensilyl group, a copolymer of a dimethylsiloxane unit and a methylhydrogensiloxane unit, a dimethylhydrogensiloxane unit (H (CH
_{3) 2} SiO _0.5 units) and the low viscosity fluid consisting of SiO ₂ units, 1,3,5,7 hydrogen 1,3,
5,7-tetramethylcyclotetrasiloxane, 1-propyl-3,5,7-trihydrogen-1,3,
5,7-tetramethylcyclotetrasiloxane, 1,5
-Hydrogen-3,7-dihexyl-1,3,5
7-tetramethylcyclotetrasiloxane and the like.

The organohydrogenpolysiloxane as the curing agent is such that the hydrogen atom of the SiH group is 50 relative to the alkenyl group of the organopolysiloxane of the component (A).
Preferably, it is used in a proportion of up to 500 mol%.

The addition reaction between the alkenyl group-containing organopolysiloxane and the organohydrogenpolysiloxane involves addition of a known platinum catalyst. Specifically, platinum alone, a platinum compound, a platinum composite, Platinic acid, alcohol compounds of chloroplatinic acid, aldehyde compounds, ether compounds, and complexes with various olefins are exemplified. The amount of the platinum-based catalyst is from 1 to 2,0 as platinum atoms based on the organopolysiloxane (A).
It is preferable to be within the range of 00 ppm.

The silicone rubber composition according to the present invention may contain other optional components in addition to the above essential components, if necessary, as long as the effects of the present invention are not impaired. Specifically, as an optional component, a filler such as ground quartz, calcium carbonate, or silicone powder may be added as an extender, or conductivity may be imparted by blending conductive carbon black or the like. Further, an inorganic or organic blowing agent may be added to form the sponge. Examples of the foaming agent include azobisisobutyronitrile, dinitropentamethylenetetramine, benzenesulfone hydrazide and the like, and the addition amount thereof is preferably in the range of 3 to 10 parts with respect to the silicone rubber compound. When a foaming agent is added to the composition of the present invention, a sponge-like silicone rubber can be obtained.

Further, it is optional to add various additives such as a colorant and a heat resistance improver, a reaction controlling agent, a release agent and a dispersant for a filler to the composition of the present invention, if necessary. However, diphenylsilanediol, various alkoxysilanes, silanol group-containing low molecular weight siloxanes and the like used as the filler dispersant are preferably kept to a minimum amount so as not to impair the effects of the present invention.

The silicone rubber composition of the present invention has a platinum-containing material for making it flame-retardant and fire-resistant.
Known additives such as a platinum compound and titanium dioxide, platinum and manganese carbonate, platinum and γ-Fe ₂ O ₃ , ferrite, mica, glass fiber and glass flake may be added.

The silicone rubber composition of the present invention is kneaded with the above-mentioned components using a mixer generally used for rubber, such as a Banbury mixer, a kneader, an intermixer, or a two-roll mixer. If necessary, it can be obtained by performing a heat treatment. In this case, for example, the base compound is prepared by previously mixing the first component, organopolysiloxane, and the second component, positively chargeable reinforcing silica, and the like. The curing agent of the third component may be added to and mixed with this.

The silicone rubber composition thus obtained can be molded and cured for various applications by various molding methods such as mold pressure molding and extrusion molding. In this case, the curing conditions may be appropriately selected depending on the curing method, the curing agent, the thickness of the roll, and the like, but usually 100 to 200 ° C. for 1 to 30 minutes in the case of mold pressing, and 100 in the case of extrusion. At about 400 ° C. for several seconds to about 10 minutes. If necessary, secondary vulcanization (post-cure) may be performed at 200 to 250 ° C. for about 1 to 10 hours.

The silicone rubber composition of the present invention is formed as a paper feed roll and a development roll. The roll can be produced by a known method. However, the silicone rubber composition of the present invention preferably forms at least the outermost surface of the roll, thereby effectively exhibiting the effects of the feed roll and the developing roll. Can be done. For example, a silicone rubber layer of the silicone rubber composition of the present invention is formed on a roll core, or one or two or more rubber layers are formed with another rubber material on a roll core, and the uppermost layer is formed. It is preferable to form a silicone rubber layer using the silicone rubber composition of the present invention.

[0029]

By forming a paper feed roll or a development roll from the cured product of the silicone rubber composition of the present invention, it is possible to control the positive charging property of the roll surface, and to supply the rubber roll of the present invention. If it is used as a paper roll, it suppresses the reduction in frictional force during durability while maintaining the transport capacity, and can withstand long-term use.If it is used as a development roll, it is possible to construct a system with excellent toner charging properties. is there.

[0030]

EXAMPLES The present invention will be described in detail below with reference to examples and comparative examples, but the present invention is not limited to the following examples. All parts in each example are parts by weight. [Example 1] A rubbery organopolysiloxane comprising 99.825 mol% of dimethylsiloxane units, 0.15 mol% of methylvinylsiloxane units and 0.025 mol% of dimethylvinylsiloxane units and having an average degree of polymerization of about 5,000. 100 parts of siloxane, 3 parts of diphenylsilanediol as a dispersant, 4 parts of dimethylpolysiloxane having terminal silanol group (degree of polymerization n = 10), and specific surface area of 200 m
40 parts of ² / g of positively charged silica RA-200HS (manufactured by Nippon Aerosil Co., Ltd.) was added and heat-treated for 2 hours to prepare a base compound I.

To 100 parts of the above base compound, 1.3 parts of 2,5-dimethyl-2,5-di (t-butylperoxy) hexane was added as a curing agent, and a roll A having a diameter of 16 mm was formed. The molding temperature was 165 ° C./10 minutes, and the molding pressure was 30 kgf / cm ² .

Comparative Example 1 A base compound II was prepared in the same manner as in Example 1 except that 40 parts of negatively charged silica Erosil-200 (having a specific surface area of 200 m ² / g manufactured by Nippon Aerosil Co., Ltd.) was added as silica. A silicone rubber roll B was obtained in the same manner as in Example 1.

Example 2 10 parts of electrified acetylene black (manufactured by Denki Kagaku Co., conductive carbon) was added to the base compound I obtained in Example 1, and C-
19A (Shin-Etsu Chemical Co., Ltd., platinum catalyst) 1.0 part, C-
19B (manufactured by Shin-Etsu Chemical Co., Ltd., organohydrogenpolysiloxane) (2.5 parts) was added, and a silicone rubber roll C was obtained in the same manner as in Example 1.

Comparative Example 2 The same carbon and curing agent as in Example 2 were added to the base compound II obtained in Comparative Example 1 to obtain a silicone rubber roll D.

The obtained silicone rubber roll was heated at 200 ° C.
After キ ュ hour post-cure, the friction coefficients of the rolls A and B were measured at the initial stage and after 10,000 sheets were passed, and compared.

After the rolls C and D came into contact with the one-component negative toner, the chargeability of the toner was measured by a blow-off charging method. Table 1 shows the above results. From the results shown in Table 1, it is recognized that the roll of the present invention is excellent as a feed roll and a developing roll.

[0037]

[Table 1]

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI // B29K 83:00 B29K 83:00 (72) Inventor Masayuki Yoshida 1-chome, Matsuida-cho, Usui-gun, Gunma Prefecture 10 Shinetsu Chemical Industry (56) References JP-A-59-126576 (JP, A) JP-A-63-298354 (JP, A) (58) Fields studied (Int. Cl. ⁷ , DB Name) C08L 83/00-83/16 C08K 5/14 C08K 3/36

Claims (4)

(57) [Claims] 1. A silicone rubber composition used to form at least the outermost surface of a paper feed roll or a development roll, wherein (A) 100 parts by weight of an organopolysiloxane represented by the following average composition formula (1): R ¹ SiO _{(4-n) / 2} (1) (wherein, R ¹ is the same or different unsubstituted or substituted monovalent hydrocarbon group, and n is a positive number of 1.98 to 2.02) (B) 5 to 70 parts by weight of a positively chargeable reinforcing silica having a specific surface area of 10 m ² / g or more (C) a curing agent containing an organic peroxide catalyst and a necessary amount of curing. Silicone rubber composition. 2. A silicone rubber composition used for forming at least the outermost surface of a paper feed roll or a developing roll, wherein (A) 'is an organopolysiloxane represented by the following average composition formula (1): 100 parts by weight R ¹ SiO _{(4-n) / 2} (1) (wherein R ¹ is the same or different unsubstituted or substituted monovalent hydrocarbon group, and the content of the aliphatic unsaturated group in R ¹ is 0) 0.001 to 5 mol%, n is a positive number of 1.98 to 2.02.) (B) 5 to 70 parts by weight of positively chargeable reinforcing silica having a specific surface area of 10 m ² / g or more ( C) A silicone rubber composition comprising a curing agent containing a necessary amount of a curing agent obtained by using an organohydrogenpolysiloxane and a platinum-based catalyst together as a curing agent. 3. A paper feed roll wherein the cured product layer of the silicone rubber composition according to claim 1 or 2 forms at least the outermost surface. 4. A developing roll in which a cured product layer of the silicone rubber composition according to claim 1 forms at least the outermost surface.