JP3385133B2 - Addition-curable silicone rubber composition for heat fixing roller and heat fixing roller using the same - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an addition-curable silicone rubber composition, and more particularly to an addition-curable silicone rubber composition having excellent thermal conductivity and suitable for a heat fixing roller for electrostatic recording, and the use thereof. It relates to a heat fixing roller.

[0002]

2. Description of the Related Art Conventionally, a fixing roller used in an electrophotographic apparatus such as a PPC is a PPC to which a toner pattern is attached.
A heat roller for press-fitting and fixing the toner in the paper fiber structure by thermocompressing the paper or a pressure roller for backing up the heat roller.Since heat resistance is required, silicone rubber excellent in heat resistance is used. It was commonly used as a material.

Particularly when a heat roller is used, in order to shorten the waiting time at the time of starting the machine, and
From the viewpoint of energy saving of the machine itself, 1.0 × 10 ^-3 c
al / cm · sec · ° C or higher, especially 1.5 × 10 ⁻³ ca
Since it is necessary to use a heat roller having a high thermal conductivity of 1 / cm · sec · ° C. or higher, silicone rubber excellent in thermal conductivity has been required.

However, since the thermal conductivity of silicone rubber itself is not high, a method of adding a filler having high thermal conductivity is generally used. In addition, silica is usually used as a filler in silicone rubber as a filler from the viewpoint of reinforcement, but addition of silica results in 1.5 × 1.
If the thermal conductivity of 0 ^-3 cal / cm · sec · ° C or more is to be exhibited, a considerable amount of silica must be added, so that the strength of the silicone rubber decreases. Therefore,
When a heat fixing roller is manufactured by using silica as a heat conductive filler, there is a drawback that the heat conductivity of the silicone rubber is not sufficient.

Therefore, in order to satisfy a higher level of thermal conductivity, a method of adding a metal oxide such as alumina, magnesium oxide or beryllium oxide to an addition-curing type silicone rubber (Japanese Patent Laid-Open No. 50-2349). Japanese Patent Publication No. 55-22891 and Japanese Patent Publication No. 63-251466.
Issue) is also being considered.

In this case, 2.0 × 10 ^-3 cal / cm
・ Although a very high level of thermal conductivity of sec / ° C or higher can be expressed, the releasability for releasing toner and abrasion resistance for recording paper required for the fixing roller for electrostatic recording are not sufficient. There was a drawback to say. Therefore, an addition-curable silicone rubber composition having a high level of thermal conductivity and an excellent release durability of toner, which is suitable for a heat fixing roller including a heat roller for an electrostatic recording device, is obtained. Development was desired.

[0007]

Therefore, as a result of intensive investigations by the present inventors on a silicone rubber composition having high thermal conductivity and toner release durability, a large amount of alumina was added to enhance the thermal conductivity. On the other hand, they have found that by adding a spherical tetrafluoroethylene resin, it is possible to enhance the release durability for toner and the abrasion resistance of rollers for recording paper, and arrived at the present invention.

Accordingly, the first object of the present invention is to provide an addition-curable silicone rubber composition for a heat fixing roller, which is excellent in thermal conductivity, abrasion resistance for recording paper and releasing durability for toner. To provide. A second object of the present invention is to provide a heat fixing roller suitable for an energy saving type electrostatic recording device.

[0009]

Means for Solving the Problems The above-mentioned various objects of the present invention include (1) an organopolysiloxane containing at least two aliphatic unsaturated hydrocarbon groups bonded to a silicon atom in the molecule; A main component is a composition comprising an organohydrogenpolysiloxane containing at least two hydrogen atoms bonded to silicon atoms; (3) alumina; and (4) spherical tetrafluoroethylene resin. And an addition curable silicone rubber composition for a heat fixing roller, and
Achieved by a heat fixing roller using it.

The first component used in the silicone rubber composition of the present invention, the organopolysiloxane containing at least two aliphatic unsaturated hydrocarbon groups bonded to silicon atoms in the molecule, is the main component of the present invention. It is a component. Here, as a specific example of the organopolysiloxane, a compound represented by the following general composition formula (1) can be used.

R ¹ _a R ² _b SiO _{[4- (a + b)] / 2} (1) wherein R ¹ in the above formula is a monovalent aliphatic unsaturated hydrocarbon group,
R ² is an unsubstituted monovalent hydrocarbon group other than the aliphatic unsaturated hydrocarbon group, and a and b are 0 <a ≦
1, 1 ≦ b <3, 1 <a + b <3, preferably 0.0001 ≦ a ≦ 0.2, 1.8 ≦ b ≦ 2.2, 1.
It is a number that satisfies 8 ≦ a + b ≦ 2.25.

The above R ¹ is an aliphatic unsaturated hydrocarbon group having 2 to 8 carbon atoms, particularly 2 to 4 carbon atoms, and preferable R 1 is
Examples of ¹ include alkenyl groups such as vinyl group, allyl group, propenyl group, isopropenyl group, butenyl group, isobutenyl group and hexenyl group. Of these, a vinyl group is particularly preferable.

Further, R ² preferably has 1 to 12 carbon atoms, and particularly preferably 1 to 8 carbon atoms. Specific examples of R ² include, for example, methyl group, ethyl group, propyl group,
Isopropyl group, butyl group, isobutyl group, tert-
Examples thereof include an alkyl group such as a butyl group, a hexyl group, a cyclohexyl group and an octyl group, an aryl group such as a phenyl group and a tolyl group, an aralkyl group such as a benzyl group and a phenylethyl group. Of these, a methyl group is particularly preferable.

Further, in the above general formula (1), R
¹ and R ² may be different or the same,
It is necessary that at least two aliphatic unsaturated hydrocarbon groups such as vinyl groups are contained in one molecule. This aliphatic unsaturated group may be a silicon atom at the end of the molecular chain, or a silicon atom in the molecular chain,
From the viewpoint of the curing rate and the physical properties of the cured product, it is preferably one bonded to a silicon atom at the end of the molecular chain.

The above-mentioned organopolysiloxane may have a linear, branched or cyclic skeleton, but normally, the main chain is basically composed of repeating diorganosiloxane units. It is generally a linear diorganopolysiloxane having a molecular chain terminal blocked with a triorganosiloxy unit. The degree of polymerization of the organopolysiloxane (that is, the number of silicon atoms in the molecule) is usually 50 to 20,000, preferably 100 to 15.0.
It is about 00.

The second component used in the silicone rubber composition of the present invention is at least two hydrogen atoms (ie, SiH groups) bonded to silicon atoms in the molecule, preferably 3 hydrogen atoms.
The organohydrogenpolysiloxane containing one or more is a component that serves as a crosslinking agent for the organopolysiloxane of the first component, and as a specific example thereof, a compound represented by the following general composition formula (2) is used. it can.

R ³ _d H _c SiO _{[4- (c + d)] / 2} (2) wherein R ³ in the above formula is a substituted or unsubstituted monovalent hydrocarbon group, , C and d are each 0.002 ≦ c
≦ 1, 0.8 ≦ d ≦ 2.2, 0.8 <c + d <3, preferably 0.01 ≦ c ≦ 1, 1 ≦ d ≦ 2.2,
It is a number that satisfies 1.8 ≦ c + d ≦ 2.5.

The above R ³ has 1 to 10 carbon atoms.
12, especially 1-8 carbon atoms excluding aliphatic unsaturated groups
Is preferably an unsubstituted monovalent hydrocarbon group, and specific examples thereof include methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, tert-butyl group, hexyl group, cyclohexyl group and octyl group. Examples of the alkyl group, phenyl group, aryl group such as tolyl group, benzyl group, aralkyl group such as phenylethyl group, alkenyl group such as vinyl group, allyl group, propenyl group, etc. Those having 1 to 6 are preferable.

The second component, organohydrogenpolysiloxane, may have a linear, branched, or cyclic skeleton, as in the first component, and may have a hydrodiorganosiloxy unit and SiO _2. It may be a resinous product having a three-dimensional network structure containing units and optionally containing triorganosiloxy units, hydromonoorganosiloxane units and / or diorganosiloxane units. The hydrogen atom bonded to the silicon atom (SiH group) in this organohydrogenpolysiloxane may be located at the end of the molecular chain or in the molecular chain,
At least 2, preferably 3 or more are contained in the molecule.

The degree of polymerization (that is, the number of silicon atoms in the molecule) is preferably in the range of 3 to 300, more preferably 4 to 150, and the amount of the hydrogen atom bonded to the silicon atoms in this component is set. (That is, the SiH group) and the unsaturated hydrocarbon group bonded to the silicon atom in the first component have a molar ratio of
The amount is 10: 1 to 1:10, particularly 3: 1 to
The amount is preferably 1: 3.

Alumina, which is the third component used in the silicone rubber composition of the present invention, is an important component for exhibiting high thermal conductivity, and any type of intermediate alumina, calcined alumina, fused alumina, etc. can be used. However, calcined alumina and fused alumina are preferable from the viewpoint of surface activity. The shape is not particularly limited, and may be amorphous or spherical.

The amount of alumina added is preferably 100 to 500 parts by weight, and particularly preferably 150 to 350, based on 100 parts by weight of the total amount of the first and second components.
Parts by weight. If it is less than 100 parts by weight, high thermal conductivity cannot be exhibited, and if it exceeds 500 parts by weight, physical properties of silicone rubber are adversely affected.

Further, although the roll material obtained from the composition of the present invention has improved abrasion resistance, even if abrasion occurs in the heat fixing roll, for example, the central portion and the end portion of the roll after passing the paper. It is necessary for the entire roll to wear uniformly without any difference in diameter. This is a very important property for roll materials, and when uneven wear occurs,
Paper wrinkles are generated, and the durability of the roll is greatly reduced. The particle size of alumina is important to make the wear property of the roll material uniform,
Therefore, the average particle size of alumina used in the present invention is 0.
It is preferably 1 to 40 μm, particularly 1 to 25 μm
Is preferred. If it is 0.1 μm or less, the viscosity before curing and the compression set after curing will be affected, resulting in uneven wear. If it is 40 μm or more, the strength of the silicone rubber itself will be insufficient. .

The spherical tetrafluoroethylene resin which is the fourth component used in the silicone rubber composition of the present invention improves the wear resistance and release durability of the roller. That is, when the composition of the present invention is molded as a roller, the spherical tetrafluoroethylene resin appears on the surface of the roller to form appropriate hemispherical irregularities. Further, since the tetrafluoroethylene resin itself has slipperiness, the slipperiness of the roller surface is remarkably improved due to this property and the above-mentioned unevenness. Therefore, by selecting the average particle diameter and the addition amount within a certain range, it is possible to suppress abrasion due to the recording paper without impairing other physical properties such as heat resistance, and it is also possible to improve the releasability for releasing the toner.

It is important that the tetrafluoroethylene resin used in the present invention has a spherical shape, and if it has another shape, for example, a rough and amorphous shape, the slipperiness of the surface is adversely affected. Its average particle size is 0.1
The thickness is preferably ˜20 μm, and particularly preferably 2 to 15 μm. If it is smaller than 0.1 μm, it is not possible to form appropriate irregularities on the surface, and if it exceeds 20 μm, the irregularities on the surface are too large and the slipperiness of the roll surface tends to be adversely affected.

The addition amount of the above-mentioned tetrafluoroethylene resin is preferably 1 to 50 parts by weight, particularly 30 to 50 parts by weight based on 100 parts by weight of the total amount of the first component and the second component.
It is preferably part by weight. If the amount is less than 1 part by weight, the surface of the roll cannot be appropriately roughened, and if it exceeds 50 parts by weight, the physical properties of the silicone rubber are adversely affected.
It is also disadvantageous in terms of cost.

Since the addition-curable silicone rubber composition of the present invention is crosslinked by a hydrosilylation reaction (addition reaction) to form a rubber-cured product, it is necessary as another component in the composition for the reaction. Platinum-based compounds, for example, platinum, platinum chloride, chloroplatinic acid, platinum group metal compounds such as vinyl siloxane complex and alcohol-modified solutions thereof, or (addition reaction) catalysts such as rhodium-based compounds and palladium-based compounds In an ordinary catalytic amount, for example, 0.1 to 1,000 pp as platinum, palladium, or rhodium metal with respect to the first component organopolysiloxane.
m, especially in the range of about 1 to 500 ppm.

Further, a reaction control agent such as an acetylene compound, a phosphorus compound, a nitrile compound, a carboxylate, a tin compound, a mercury compound and a sulfur compound may be added within a range that does not adversely affect the composition of the present invention. Further, if necessary, silica fine particles, a filler such as calcium carbonate,
Silicone-based resins, carbon black, conductive zinc white, conductive agents such as metal powder, reinforcing materials such as nitrogen-containing compounds, iron oxide, and heat-resistant agents such as cerium oxide, adhesiveness imparting agents and thixotropy imparting agents, etc. Can also be appropriately mixed.

The addition-curable silicone rubber composition of the present invention is coated on the core metal of a fixing roller for an electrostatic recording device used for PPC, facsimile, etc., and is cured by heating to fix the toner to release the toner. Extremely durable,
It is possible to obtain a heat fixing roller for an electrostatic recording device.

[0030]

The silicone rubber obtained by curing the addition-curable silicone rubber composition of the present invention is not only excellent in thermal conductivity, but also when it is used in a heat fixing roll, it has abrasion resistance and separation. Since it has good mold durability and evenly wears when worn, it is extremely useful as a coating material for fixing rollers and heat rollers of electrostatic recording devices such as PPCs and facsimiles.

[0031]

EXAMPLES The present invention will be described in more detail below with reference to examples, but the present invention is not limited thereto.
In addition, "%", "degree of polymerization" and "part" described below
Unless otherwise specified, it means "% by weight", "weight average degree of polymerization" and "parts by weight".

Example 1. 100 parts of dimethylpolysiloxane with vinyl dimethylsiloxy groups blocked at both ends (polymerization degree 350, vinyl value 0.0065 mol / 100 g), fumed silica 10 parts, alumina AS-40 (trade name of Showa Denko KK: average particle size) 12 μm spherical alumina) 2
80 parts, methylhydrogenpolysiloxane (polymerization degree 17, Si—H equivalent 0.00528 mol / g) 7 parts, platinum catalyst (Pt concentration 1%) 0.2 part, and 1-ethynyl-1 as a reaction control agent. -Mixing 0.1 part cyclohexanol, then KTL as spherical tetrafluoroethylene resin
-8N (trade name of Kitamura Co., Ltd .: average particle size 5 μm)
30 parts were added to prepare the composition of the present invention.

The obtained composition was vacuum degassed and then injected into an internal mirror-finished cylindrical mold into which a roll cored bar coated with an alkoxysilane-based primer was inserted using an injection molding machine. After heat curing at 10 ° C. for 10 minutes, secondary vulcanization was performed at 200 ° C. for 4 hours to obtain a rubber roller for heat fixing having a thickness of 2 mm. The hardness of the obtained rubber roller (based on A of JIS K 6301), tensile strength (kg / cm ² ), elongation (%), dynamic friction coefficient precision measuring device DFPM type (trade name of Kyowa Kagaku Co., Ltd.) The coefficient of dynamic friction and the number of sheets until offset are measured, and further, LASERSCAN DIAMETER LS-3060T (KEYEN
CE product name), the initial diameter of the rubber roller, the diameter of the roll end of the rubber roller after use, the diameter of the paper end of the rubber roller after use, and the rubber after use. The results of measuring the diameter of the roll central portion of the roller are as shown in Table 1 and FIG.

[0034]

[Table 1]

Example 2. Alumina A used in Example 1
A composition was prepared in exactly the same manner as in Example 1 except that 280 parts of alumina WA # 700 (trade name of Fujimi Incorporated Co., Ltd.) was used instead of S-40, and heat fixing was performed in the same manner. The rubber roller was obtained and the measurement results are as shown in Table 1.

Comparative Example 1. KTL-8 used in Example 1
A heat-fixing rubber roller was obtained in exactly the same manner as in Example 1 except that N was not added, and the obtained rubber roller was measured in exactly the same manner as in Example 1 and the results are shown in Table 1.
As shown in.

Comparative Example 2. Instead of the spherical tetrafluoroethylene resin KTL-8N used in Example 1, 30 parts of amorphous tetrafluoroethylene resin KTL-610 (trade name of Kitamura Co., Ltd .: average particle size 10 μm) was added. In the same manner as in Example 1, a composition was prepared, a rubber roller for heat fixing was obtained in the same manner, and the measurement results were as shown in Table 1.

[0038]

[Brief description of drawings]

FIG. 1 is a diagram showing a change in outer diameter of a roll after use.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁷ Identification code FI G03G 15/20 102 G03G 15/20 102 (72) Inventor Masanobu Miyakoshi 1 Hitomi, Matsuida-cho, Usui-gun, Gunma 10 Shinetsu Chemical Industry (56) Reference JP-A-57-149354 (JP, A) JP-A-58-219259 (JP, A) JP-A-62-47673 (JP, A) JP-A-62-47673 (JP, A) JP 62-256863 (JP, A) JP-A-3-269472 (JP, A) JP-A-4-164741 (JP, A) JP-A-6-287451 (JP, A) JP-A-4-328163 (JP , A) JP 6-95545 (JP, A) JP 7-179767 (JP, A) JP 8-11243 (JP, A) JP 8-311344 (JP, A) JP 8-319425 (JP, a) (58 ) investigated the field (Int.Cl. ^7, D Name) C08L 83/00 - 83/16 C08K 3/00 - 13/08 B41J 13/076 G03G 15/20

Claims (5)

(57) [Claims] 1. An organopolysiloxane containing (1) at least two aliphatic unsaturated hydrocarbon groups bonded to silicon atoms in the molecule; (2) At least two hydrogen atoms bonded to silicon atoms in the molecule. An addition-curable silicone rubber composition for a heat fixing roller, which comprises a composition comprising an organohydrogenpolysiloxane to be contained; (3) alumina; and (4) spherical tetrafluoroethylene resin as a main component. object. 2. The molar ratio of the hydrogen atom bonded to the silicon atom in the second component and the aliphatic unsaturated hydrocarbon group bonded to the silicon atom in the first component is 10: 1 to 1:10. Item 1. An addition-curable silicone rubber composition for a heat fixing roller according to item 1. 3. The addition-curable silicone rubber composition for a heat fixing roller according to claim 1, wherein the alumina content is 100 to 500 parts by weight based on 100 parts by weight of the total amount of the first component and the second component. object. 4. The content of the spherical tetrafluoroethylene resin is 1 to 100 parts by weight after the total amount of the first component and the second component.
The addition curable silicone rubber composition for a heat fixing roller according to claim 1, which is 50 parts by weight. 5. A heat fixing roller for an electrostatic recording device, comprising a roller core metal coated with silicone rubber,
A heat-fixing roller, characterized in that the silicone rubber is obtained by curing the addition-curable silicone rubber composition according to any one of claims 1 to 4.