Roll or roller – Concentric layered annulus – Specific composition
Reexamination Certificate
2000-05-30
2001-12-11
Cuda Rosenbaum, I (Department: 3726)
Roll or roller
Concentric layered annulus
Specific composition
C492S053000, C492S054000, C219S216000
Reexamination Certificate
active
06328682
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a heat-fixing silicone rubber roller used in copying machines, laser beam printers, fax machines and so forth. More particularly, it relates to a fixing silicone rubber roller having a silicone rubber layer provided on its outer periphery with a fluorine resin layer and/or a fluorine rubber layer.
2. Description of the Prior Art
As fixing rollers used in copying machines, laser beam printers, fax machines and the like, conventionally used are silicone rubber rollers comprising a roller shaft (a mandrel) and a silicone rubber surface layer provided on the former's outer periphery. This is because silicone rubber has toner releasability, heat resistance, compression set and so forth which are superior to those of other rubber materials.
In recent years, as machinery of this type has been made high-speed, oil fusing which feeds silicone oil to the surface of a fixing roller is carry out for the purpose of improving toner releasability. Also, rubber materials are being made to have low hardness so that, at the time of high-speed fixing, fixing width (nip width) can be ensured to increase the time taken for fixing.
However, since the silicone rubber has originally the same quality as the silicone oil and moreover has been made low-hardness, there is a problem that it may be swelled with the silicone oil fused. As a means for solving this problem, fluorine resin and/or fluorine rubber is/are further provided by coating, on the surface of a silicone rubber roller whose surface layer is formed of a silicone rubber or silicone rubber foam having a low hardness, or the above silicone rubber layer is covered with a fluorine resin tube to provide a fluorine resin layer on the outer periphery of the silicone rubber layer.
Such a means brings about a remarkable improvement in service life as fixing rollers. However, the coating of fluorine resin requires a high temperature exceeding the melting temperature of fluorine resin. Also, the coating of fluorine rubber requires high-temperature baking carried out at 300 to 350° C. for 15 minutes to 1 hour after coating. In such a condition of high temperature, however, the silicone rubber layer may deteriorate in part to damage adhesion between the fluorine resin layer or fluorine rubber layer and the silicone rubber layer. Moreover, the fixing roller thus obtained has had a problem on durability. The silicone rubber roller covered with a fluorine resin tube to provide a fluorine resin layer on the outermost layer also has had a problem that the fluorine resin layer (tube) and silicone rubber layer may come off with an increase in the number of paper feed. In particular, those having a low-hardness silicone rubber layer may greatly cause these problems. Accordingly, it has been a pressing need to make development of a fixing silicone rubber roller having a coating layer of fluorine resin and/or fluorine rubber, which has both superior interlaminar adhesion and superior durability.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a fixing silicone rubber roller having a silicone rubber layer provided on its outer periphery with a fluorine resin layer and/or a fluorine rubber layer, having both superior interlaminar adhesion between the fluorine resin layer or fluorine rubber layer and the silicone rubber layer and superior durability of the fixing roller.
To achieve the above object, the present invention provides a heat-fixing silicone rubber roller comprising a roller shaft, a silicone rubber layer provided on the outer periphery of the roller shaft, and at least one of a fluorine resin layer and a fluorine rubber layer, provided on the outer periphery of the silicone rubber layer;
the silicone rubber layer comprising a cured product of a silicone rubber composition comprising:
(A) an organopolysiloxane with an average molecular weight of from 30,000 to 100,000, having in one molecule at least two alkenyl groups bonded to silicon atoms;
(B) an organohydrogenpolysiloxane having in one molecule at least two hydrogen atoms bonded to silicon atoms; the hydrogen atoms bonded to silicon atoms being present in an amount of from 0.1 to 3.0 equivalent weight per one alkenyl group in the component (A); and
(C) a platinum group metal catalyst.
The silicone rubber layer may preferably have a rubber hardness according to JIS K 6249 of 20 or below.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The heat-fixing silicone rubber roller of the present invention is a fixing roller constituted chiefly of a silicone rubber layer and at least one of a fluorine resin layer and a fluorine rubber layer, provided on the outer periphery of the silicone rubber layer. The silicone rubber layer is a specific silicone rubber composition.
Main parts of the fixing roller of the present invention will now be described below.
Silicone Rubber Layer
The silicone rubber layer is provided on the outer periphery of a roller shaft. To form this silicone rubber layer, a liquid addition-curable silicone rubber composition comprising (A) an organopolysiloxane with an average molecular weight of from 30,000 to 100,000, having in one molecule at least two alkenyl groups bonded to silicon atoms; (B) an organohydrogenpolysiloxane having in one molecule at least two hydrogen atoms bonded to silicon atoms (i.e., SiH groups); the hydrogen atoms bonded to silicon atoms being present in an amount of from 0.1 to 3.0 equivalent weight (i. e., from 0.1 to 3.0 atoms) per one alkenyl group in the component (A); and (C) a platinum group metal catalyst, is coated on the outer periphery of a roller shaft made of a metal such as aluminum, iron or stainless steel, followed by heat curing. In this case, in order to improve the adhesion (adhesive power) between the roller shaft and the silicone rubber layer, the roller shaft surface may preferably be beforehand primer-treated with a known primer, in particular, a primer for silicone rubbers.
The silicone rubber layer (i.e., a layer formed of a cured product of the silicone rubber composition) thus obtained preferably has a rubber hardness (JIS K 6249) of 20 or below.
The components that constitute this silicone rubber composition will be detailed below.
(A) Alkenyl Group-containing Organopolysiloxane:
The component-(A) Alkenyl group-containing organopolysiloxane is a known organopolysiloxane usually used as a base polymer for addition-curable silicone rubber compositions. This organopolysiloxane has a viscosity of from 5,000 to 300,000 cP (centipoise) at 25° C., and is a compound represented by the general compositional formula (I): R
a
SiO
(4−a)/2
(wherein R's each represent a substituted or unsubstituted monovalent hydrocarbon group bonded to a silicon atom, and a represents a number of from 1.9 to 2.4, and preferably from 1.95 to 2.05).
In the general compositional formula (I), as examples of the substituted or unsubstituted monovalent hydrocarbon group represented by R, it may include alkyl groups such as a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a tert-butyl group, a pentyl group, a neopentyl group, a hexyl group, a heptyl group, an octyl group, a nonyl group, a decyl group and a dodecyl group; cycloalkyl groups such as a cyclopentyl group, a cyclohexyl group and a cycloheptyl group; alkenyl groups such as a vinyl group, an allyl group, a propenyl group, an isopropenyl group, a butenyl group, an isobutenyl group, a hexenyl group, a cyclohexenyl group and a cycloheptenyl group; aryl groups such s a phenyl group, a tolyl group, a xylyl group, a naphthyl group and a biphenylyl group; aralkyl groups such as a benzyl group, a phenylethyl group, a phenylpropyl group and a methylbenzyl group; and halogen-substituted or cyano-substituted hydrocarbon groups such as a chloromethyl group, a 2-bromoethyl group, 3-chloropropyl group, a 3,3,3-trifluoropropyl group, a chlorophenyl group, a fluorophenyl group, a cyanoethyl group and a 3,3,4,4,5,5,6,6,6-nonafluorohexyl group. These substitu
Cuda Rosenbaum I
Pillsbury & Winthrop LLP
Shin-Etsu Chemical CO LTD
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