JPH06126896A - Fluororesin-coated elastic roll - Google Patents

Abstract

PURPOSE:To provide a fluororesin-coated elastic roll in which a boundary peeling, adhesive collapse do not occur during using and which can increase its life due to excellent stress crack resistance. CONSTITUTION:A fluororesin-coated elastic roll is formed by forming a silicone rubber elastic layer on a roll-like core, providing an adhesive layer made of addition reaction type self-adhesive silicone rubber thereon and then coating an outermost layer with fluororesin of tetrafluoroethylene-hexafluoropropylene copolymer having 2.0 or less of melt flow rate (ASTMD 2116).

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a fluororesin-coated elastic roll, and in particular, does not cause interfacial peeling or adhesive destruction during use,
The present invention relates to a fluororesin-coated elastic roll that has a long life due to its excellent stress crack resistance.

[0002]

2. Description of the Related Art As an elastic roll used as a fixing roll or a pressure roll in a fixing device such as an electronic copying machine,
Usually, a silicone rubber elastic layer provided on a cored bar on a roll and a fluorine resin coating layer formed by using an adhesive is used. Conventionally, as such an elastic roll, an inner surface of a fluororesin coating layer is subjected to an etching treatment and then a primer is applied to the elastic roll, which is adhered to a silicone rubber elastic layer using an adhesive composed of a condensation curing type RTV silicone rubber. An elastic roll made of the above is known (Japanese Patent Publication No. 47-20747), and an elastic roll obtained by adhering a silicone elastic layer and a fluororesin coating layer with an adhesive made of a fluororesin-containing latex is also known ( JP-A-61-38957).

[0003]

However, since the adhesiveness of this fluororesin-coated elastic roll is lacking in stability and the durability is poor, the present inventors have added a silicone rubber roll layer and a fluororesin coating layer. It was found that if a reactive silicone rubber is bonded as an adhesive layer, the bonding is stable and high durability is obtained (see Japanese Patent Application Laid-Open No. 4-17332). However, as the fluororesin, tetrafluoroethylene-hexafluoroethylene It has been found that when a polymer is used, this resin layer cannot be used for a long time when used as a roll of an electronic copying machine because the resin layer is easily cracked by stress and heat.

[0004]

SUMMARY OF THE INVENTION The present invention relates to a fluororesin-coated elastic roll which solves the above disadvantages and drawbacks, in which a silicone rubber elastic layer is formed on a cored bar on the roll, and the elastic layer is formed thereon. After forming an adhesive layer made of addition reaction type self-adhesive silicone rubber, the outermost layer is coated with a fluororesin made of tetrafluoroethylene-hexafluoropropylene copolymer having a melt flow rate of 2.0 or less. To do.

That is, as a result of various investigations by the present inventors to develop a fluororesin-coated elastic roll having improved stress crack resistance and long life, a silicone rubber elastic layer is formed on a roll-shaped core metal. If an addition reaction type self-adhesive silicone rubber layer is provided on this, and a fluororesin made of a tetrafluoroethylene-hexafluoropropylene copolymer having a melt flow rate of 2.0 or less is further coated thereon, It was found that an elastic roll with improved stress crack resistance and a significantly improved life can be obtained, and the silicone rubber elastic layer, the addition reaction type self-adhesive silicone rubber, and the fluororesin layer used here are found. The present invention has been completed by conducting research on configurations and processing methods thereof. This will be described in more detail below.

[0006]

The present invention relates to a fluororesin-coated elastic roll, in which a silicone rubber elastic layer is formed on a roll-shaped core metal, and an adhesive layer made of an addition reaction type self-adhesive silicone rubber is formed thereon. After being provided, the outermost layer is characterized by being coated with a fluororesin made of tetrafluoroethylene-hexafluoropropylene copolymer having a melt flow rate of 2.0 or less. Since the elastic roll has improved resistance to stress cracking, it has an advantage that the life is greatly extended.

The fluororesin-coated elastic roll of the present invention comprises a cored bar provided with a silicone rubber elastic layer, an addition reaction type self-adhesive silicone rubber layer and a fluororesin layer. The silicone rubber elastic layer formed on the cored bar is not particularly limited, and any known silicone rubber may be used. This requires diorganopolysiloxane with a filler and other additives. A cured product of the silicone rubber composition blended accordingly may be mentioned.

Examples of the diorganopolysiloxane used here include dimethylpolysiloxane, methylvinylpolysiloxane, methylphenylpolysiloxane,
Starting with 3,3,3-trofluoropropylmethylpolysiloxane, there are various copolymers composed of various siloxy units and siloxane units constituting them.

Further, as the filler used here,
For example, famed silica, precipitated silica, hydrophobic silica, carbon black, titanium dioxide, ferric oxide, aluminum oxide, zinc oxide, quartz powder, diatomaceous earth, calcium silicate, talc, bentonite, asbestos,
Examples include glass fibers and organic fibers, and one or more of these may be mixed. Further, as the additive other than the filler, one kind or two or more kinds among various kinds can be blended.

The type of curing of this silicone rubber composition is not limited at all, and therefore, this is an organic peroxide curing type, which is a hydrocarbon type catalyst of Si-H bond and aliphatic unsaturated bond with a platinum group metal catalyst. It may be an addition reaction curable type that uses a relation reaction or various condensation curable types.However, when using a condensation curable type silicone rubber, the adhesive layer (b) may be a catalyst depending on the type of condensation catalyst used. Poor curing can occur due to poisons, so it is preferable to use organic peroxide curing type or addition reaction curing type.

In order to form this silicone rubber elastic layer on the cored bar, a silicone rubber unvulcanized product containing a curing agent is required on the cored bar to which a primer has been applied in advance, if necessary. It can be carried out by molding into the above shape, curing, and then polishing to a predetermined outer dimension. Typical primers used include, for example, Shin-Etsu Chemical Co., Ltd.'s primers NO.16 and NO.18B (trade name) which are usually used for adhesion of silicone rubber and metal.

The unvulcanized silicone rubber can be molded on the core metal by a molding method such as pressure molding, injection molding, extrusion molding, or casting method. Usually, a metal such as aluminum or iron or an alloy thereof is used.

Next, the addition reaction type self-adhesive silicone rubber formed on the silicone rubber elastic layer serves as an adhesive layer for adhering the silicone rubber elastic layer and a fluororesin layer described later. Since this is an addition reaction type, (a) alkenyl group-containing diorganopolysiloxane, (b) organohydrogenpolysiloxane, (c) platinum-based curing catalyst and (d) ) The adhesiveness-imparting agent is an essential component, and if necessary, the filler and the additive used in the silicone rubber elastic layer of (a) are appropriately blended.

The (a) diorganopolysiloxane containing an alkenyl group is preferably one containing at least two alkenyl groups bonded to a silicon atom in one molecule. Examples of such an alkenyl group include a vinyl group and an allyl group, and a vinyl group is preferable.
Further, the other organic group bonded to the silicon atom is preferably a monovalent hydrocarbon group having 10 or less carbon atoms, for example, an alkyl group such as a methyl group, an ethyl group, a propyl group, a butyl group, a phenyl group, and a tolyl group. Groups such as aryl groups, chloromethyl groups, 3,3,3-trifluoropropyl groups, and other hydrocarbon groups in which some or all of the hydrogen atoms have been replaced with halogen atoms, and the like. Groups are preferred. A straight-chain diorganopolysiloxane containing these alkenyl groups and monovalent hydrocarbon groups having 10 or less carbon atoms is preferable. The alkenyl group may be present in the molecular chain of the diorganopolysiloxane or at both ends of the molecular chain, and the content thereof is preferably 0.05 to 10 mol% in the total organic groups.

Since this (b) organohydrogenpolysiloxane is a cross-linking agent which cures the composition by addition reaction with the alkenyl group in the diorganopolysiloxane of (a) above, at least two per molecule are included. Although it is necessary to have a SiH group, its molecular structure may be linear, cyclic or branched. The amount of this organohydrogenpolysiloxane used is the molar ratio [Si-H group] / [alkenyl group] of the Si-H groups contained therein and the alkenyl groups in the diorganopolysiloxane of (a).
Is preferably in the range of 0.5 to 5.

The (c) platinum-based catalyst may be a known one, and examples thereof include chloroplatinic acid, alcohol-modified chloroplatinic acid, chloroplatinic acid-olefin complexes, and vinylsiloxane complexes. The amount used is usually about 1 to 100 ppm with respect to the component (a).

Since the (d) adhesiveness-imparting agent used here is for imparting self-adhesiveness to this addition reaction type siloxane composition, it contains a functional group which imparts adhesiveness. It is preferably a silicon compound. Examples of such a functional group include an epoxy group, an alkoxy group, a vinyl group, a SiH group and the like, and a group containing two or more of these functional groups in one molecule is particularly preferable.

Further, examples of the silicon compound containing such a functional group include:

[Chemical 1]

[Chemical 2]

[Chemical 3]

[Chemical 4]

[Chemical 5] Etc. are exemplified, and the addition amount of these is usually the above (a).
It may be 0.1 to 5 parts by weight with respect to 100 parts by weight of the diorganopolysiloxane as a component, but when this contains a Si-H bond or an alkenyl group as a functional group, the total amount in the adhesiveness-imparting agent is The molar ratio of the amount of Si-H groups [(b) + (d)] to the total amount of alkenyl groups [(b) + (d)] in the adhesive agent is preferably 0.5 to 20. Outside the range, the mechanical properties of the adhesive will be impaired.

It should be noted that this may contain a filler and other additives, all of which may be known ones, such as those exemplified in (a) the silicone rubber elastic layer. In general, the compounding amount may be 5 to 100 parts by weight per 100 parts by weight of the diorganopolysiloxane of the component (a).

The hardness (JIS K 6301) of the addition-curable silicone rubber composition used for this adhesive layer after curing is equivalent to the hardness of the silicone rubber elastic layer described above in order to obtain sufficient adhesion durability. It is preferable to use a higher one. For example, the hardness of the silicone rubber elastic layer depends on the use or specifications, but is usually about 20 to 70,
The hardness of the adhesive layer after curing is preferably in the range of 30-80. The hardness can be adjusted by the structure of the organohydrogenpolysiloxane (b), which is a crosslinking agent, or the addition amount of the filler.

As a method of applying the addition-curable silicone rubber composition used for this adhesive layer on the silicone rubber elastic layer, for example, the addition-curable silicone rubber composition is diluted with an organic solvent and the solution is spray-coated. There is also a method of applying by dip application. Examples of such an organic solvent include toluene, xylene, 1,1,1-trichloroethane, tetrachloroethylene, etc., but when this is a liquid type, it is applied onto the elastic layer by knife coating, load coating, etc. You may.
The thickness of the adhesive layer formed here is preferably 0.1 to 0.3 mm, because if it is too thin, the adhesive strength will decrease, and if it is too thick, the layer thickness may lack uniformity.

When a uniform adhesive layer is formed by spray coating, a silicone rubber elastic layer on the core metal is used.
It is recommended to preheat to 50 to 80 ° C, because the solvent in the adhesive solution evaporates quickly on the surface of the elastic layer of silicone rubber, so the addition-curable silicone rubber composition tends to become fine particles and the solvent evaporates. The heat of vaporization generated at this time also has an effect of preventing the adsorption of water on the surface of the silicone rubber elastic layer, which causes a decrease in adhesive strength. When an addition-curable silicone rubber composition having a high viscosity is used, it is preferable to buff the surface of the layer after applying the adhesive in order to improve the surface smoothness.

In the fluororesin-coated elastic roll of the present invention, after the addition reaction type self-adhesive silicone rubber layer is provided on the above-mentioned silicone rubber elastic layer, the fluororesin is coated on this layer. Is a tetrafluoroethylene-hexafluoropropylene copolymer (hereinafter abbreviated as FEP resin).

However, the FEP resin also has a melt flow rate (g / 10 minutes; 372 ° C., load 5,000) specified by ASTM D2116.
If g) is 2.0 or more, the MIT bending life as a durability stress cracking property evaluation of the resin itself is usually 7,000 to 1
It became 5,000 cycles, and when a FEP film was stuck on a silicone rubber elastic body in a form close to the actual configuration of a copying machine roll and subjected to a De Mettia type bending test, cracks occurred at about 100 to 5,000 cycles, but When the melt flow rate is 2.0 or less, the MIT flex life of the stress crack resistance evaluation is about 7
Since it was found that no cracks were generated even after about 30,000 cycles under the condition of 175 ° C., it was found that the melt flow rate of this FEP resin was 2.0 or less. Required to be done.

The fluororesin coating layer is formed by coating the powder coating or dispersion and curing or baking the fluororesin, or by using the fluororesin in a tube shape,
There is a method of coating this by processing it into a film, but it is preferable to use a tube from the viewpoint of the strength and uniformity of this coating layer. This is a heat-shrinkable type because of the ease of coating work and the stability of adhesion. Although it is preferable to use a tube, in order to bring out the characteristics of the fluororesin tube, the inner surface of the FEP resin tube which is in contact with the adhesive may be previously etched with sodium-naphthalene or the like.

The thickness of the FEP resin tube used here is preferably 0.03 to 1.0 mm, but it may be properly selected depending on the intended use of the elastic roll to be obtained. When the adhesive layer is coated with this FEP resin tube, the FEP resin is thermally shrunk by a heating means such as a hot air gun or a dryer, and the air is removed at the same time to complete the formation of the FEP resin coating layer. In order to make the roll surface of this product smooth, pressure bonding may be performed from above the FEP resin tube with a pressure bonding roll.

The FEP resin-coated elastic roll is preferably heat-treated in order to cure the adhesive and strengthen the adhesion between the silicone rubber elastic layer and the inner surface of the FEP resin tube. It may be performed at 150 ° C for 30 to 60 minutes.

The fluororesin-coated elastic roll of the present invention thus produced can be used in a fixing device such as an electronic copying machine. In this case, a silicone rubber elastic layer and F are used.
Depending on the combination with the thickness of the EP resin tube, this can be used for both the fixing roll and pressure roll,
For example, when used for a fixing roll, it is usually preferable to set the thickness of the silicone rubber elastic layer to 0.1 to 0.5 mm and the thickness of the fluororesin tube to 0.03 to 0.1 mm. The silicone rubber elastic layer has a thickness of 5 to 10 mm, and the fluororesin tube has a thickness of 0.05 to 1.
It is preferably 0 mm.

[0029]

EXAMPLES Next, examples and comparative examples of the present invention will be described. Example Silicone primer No. 16 [trade name of Shin-Etsu Chemical Co., Ltd.] was applied on an aluminum cored bar (outer diameter 84 mmφ, length 350 mm) which is the core of the roll, and silicone rubber compound KE was applied on it. -7010u [trade name of Shin-Etsu Chemical Co., Ltd.] 100 parts by weight and 0.5 parts by weight of organic peroxide: 2,5-dimethyl-2,5-di (tert-butylperoxy) hexane as a vulcanizing agent The mixed material is heat-molded by press vulcanization using a mold, and then an outer diameter of 99.8 mm is obtained with a polishing machine.
When polishing to φ to form a silicone rubber elastic layer,
The rubber strength of this silicone rubber elastic layer was 50.

Further, diorganopolysiloxane compound KE-164u [trade name of Shin-Etsu Chemical Co., Ltd.] 100 parts by weight, the following methylhydrogenpolysiloxane

[Chemical 6] 1.5 parts by weight, 0.1 parts by weight of chloroplatinic acid in isopropanol, (Pt concentration is 1% by weight) and an adhesion promoter of the following formula

[Chemical 7] 1.0 part by weight was uniformly dissolved using 800 parts by weight of tetrachloroethylene as a solvent and mixed to prepare an addition reaction type self-adhesive silicone rubber composition as an adhesive layer.

Then, this composition was applied to the surface of the silicone rubber elastic layer preheated to 70 ° C. by using a spray gun while rotating a roll to form an adhesive layer, which was left to stand and air-dried. , The solvent was volatilized, but when the thickness of this adhesive layer was measured with a laser length measuring device,
It was 0.2 mm. The molar ratio of SiH groups and vinyl groups in the addition reaction type silicone rubber composition prepared here:
When [SiH group] / [vinyl group] was measured, this was
It was 4.0, and the rubber hardness after curing was 60 when a cured sheet was separately formed from the same composition under the same conditions and measured.

On the other hand, for the fluorine-based resin layer, a heat-shrinkable resin tube having an inner diameter of 106 mmφ and a thickness of 0.20 mm was made from FEP resin manufactured by Junkosha Co., Ltd., which has a melt flow rate of 1.2, and the inner surface thereof was made of sodium-naphthalene. Etching treatment was carried out with a tetrahydrofuran solution. Then, the heat-shrinkable FEP resin tube is coated on the surface of the adhesive layer obtained by applying the addition reaction type self-adhesive silicone rubber to the silicone rubber elastic layer obtained above, and then heating with a hot air gun to obtain the heat-shrinkable property. The FEP resin tube was heat-shrinked, allowed to stand in a dryer at 150 ° C for 30 minutes, and after cooling, the outer diameter of the roll obtained was measured using a laser measuring device. It was 100.8 to 100.9 mmφ. The eccentricity was measured to be 0.1 mm or less when the swing width of the laser measuring device when the outer diameter was measured by rotating the roll while supporting it with a bearing.

Next, when this fluororesin-coated roll was mounted and used as a pressure roll of an electronic copying machine, the abrasion of the FEP resin-coated layer due to the edge of the paper was 0.1.
It can be used for a long period of time until the offset exceeds mm, and in this case, the adhesive layer was not peeled off and sufficient durability was exhibited.

However, for comparison, a fluororesin-coated roll was prepared by treating in the same manner as in the example except that the FEP resin used in the example had a melt flow rate of 4.0. When it was used as a pressure roll of an electronic copying machine in the same manner as above, in this case, even though the wear of the FEP resin coating layer was 0.03 mm or less and offset did not occur yet, the FEP resin coating portion of the roll was cracked. Occurred, and it grew due to the shear of the roll nip and cracked, and the function of the pressure roll could not be fulfilled.

[0035]

The present invention relates to a fluororesin-coated elastic roll, which has a silicone rubber elastic layer formed on a roll-shaped core metal as described above, and an addition reaction type self-adhesive silicone rubber formed thereon. After providing an adhesive layer consisting of, the outermost layer is coated with a fluororesin consisting of tetrafluoroethylene-hexafluoropropylene copolymer having a melt flow rate of 2.0 or less. Since the fluororesin used here has a melt flow rate of 2.0 or less, the life of the elastic roll has been significantly extended by improving the stress crack resistance of this elastic roll, making it a practical pressure roll for electronic copying machines. Sometimes the target number of durable sheets can be achieved, interface peeling and adhesive destruction do not occur during use, and the smoothness of the roll surface Becomes one with the advantage that it becomes what may accuracy Le diameter.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Reference number within the agency FI Technical display location G03G 15/20 103 // B29K 27:12 83:00 105: 22 (72) Inventor Makoto Sato Gunma 1 Hitomi, Oita, Matsuida-cho, Usui-gun, Shizuoka, Shin-Etsu Chemical Co., Ltd. Silicon Silicon Electronic Materials Research Laboratory (72) Inventor Takeshi Hashimoto 1-ji, Hitomi, Matsuida-cho, Usui-gun, Gunma Shin-Etsu Chemical Co., Ltd. Silicone Electronic Materials Technology In the laboratory

Claims (1)

[Claims] 1. A silicone rubber elastic layer is formed on a roll-shaped cored bar, an adhesive layer made of an addition reaction type self-adhesive silicone rubber is provided on the elastic layer, and then a melt flow rate (ASTM D2116) is applied to the outermost layer. Is 2.0 or less, and a fluororesin-coated elastic roll coated with a fluororesin made of a tetrafluoroethylene-hexafluoropropylene copolymer.