Fixing roller

A fixing roller which is constructed by bonding in layers a heat resistant adhesive layer, a heat and oil resistant layer, a heat and oil resistant adhesive layer and an offset preventing layer to a core, wherein the offset preventing layer is formed before the solvent of the heat and oil resistant adhesive layer has been completely evaporated, and at least one component material of the heat and oil resistant adhesive layer is of a kind similar to the component materials of both the heat and oil resistant elastic layer and the offset preventing layer so that the peeling off of the offset preventing layer is obviated.

BACKGROUND OF THE INVENTION 
This invention relates to a roller for fixing toner images deposited on a 
photosensitive paper or transfer paper by heat fusing. 
The conventional fixing roller which is formed by bonding in layers a heat 
resistant adhesive layer, a heat and oil resistant elastic layer and an 
offset preventing layer to the outer surface of a core, and other 
conventional fixing roller which is formed by bonding in layers a heat 
resistant adhesive layer, a heat resistant elastic layer, an adhesive 
layer of being both oil resistant and adhesive, and an offset preventing 
layer to the outer surface of a core, has a shortcoming of the offset 
preventing layer easily peeling off the heat resistant elastic layer since 
the offset preventing layer is prone to be caused to swell by an offset 
preventing oil which is coated on the outer surface of the offset 
preventing layer. 
SUMMARY OF THE INVENTION 
It is therefore an object of the invention to provide a fixing roller which 
is capable of removing the above-mentioned shortcoming. 
In a fixing roller according to the present invention, the following are 
bonded to a core in layers in the following order: a heat resistant 
adhesive layer, a heat and oil resistant elastic layer, a heat and oil 
resistant adhesive layer, and an offset preventing layer. 
The offset preventing layer on the heat and oil resistant adhesive layer is 
formed before the solvent of the heat and oil resistant adhesive layer has 
been evaporated. Furthermore, at least one component of the heat and oil 
resistant adhesive layer is similar in properties to the components of 
said heat and oil resistant elastic layer and the offset preventing layer. 
The fixing roller according to the present invention has a feature that the 
offset preventing layer does not peel off since it is caused to adhere 
strongly to the heat and oil resistant elastic layer through the heat and 
oil resistant adhesive layer.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
In a fixing roller according to the invention, 1.mu. to 500.mu. thick heat 
resistant adhesive layer 2 is formed on the outer surface of a core 1, and 
on the outer surface of the heat resistant adhesive layer 2 is formed 
1.mu. or thicker heat and oil resistant elastic layer 3, and on the outer 
surface of the layer 3 is formed 1.mu. or thicker heat and oil resistant 
adhesive layer 4, and on the outer surface of the heat and oil resistant 
adhesive layer 4 is formed 1.mu. or thicker offset preventing layer 5 
before the solvent of the adhesive layer 4 is completely evaporated, and 
of the component materials which make up the heat and oil resistant 
adhesive layer 4, at least one component material is of a kind similar to 
the materials which make up the heat and oil resistant elastic layer 3 and 
the offset preventing layer 5. 
The core 1 is made of iron, copper, stainless steel, aluminium or glass in 
a hollow cylindrical shape or in a solid cylindrical shape as shown in the 
FIGURE. 
The heat resistant adhesive layer 2 can be made of adhesives for use with 
silicone resin base elastic materials or fluorine containing materials, 
adhesives for use with resin base elastic materials, or adhesives for use 
with rubber base elastic materials for the like. However, of these 
adhesives, the adhesives for use with rubber base elastic materials, such 
as silastic 733 and silastic 142 (commercial name), are preferable. 
The heat and oil resistant elastic layer 3 is composed of silicone fluoride 
rubber, and fluorine-contained rubber, such as silastic LS-63U and 3M-made 
Viton. The heat and oil resistant adhesive layer 4 is composed of silastic 
733, silastic 142, silastic LS-63U (commercial name) or fluorine base 
elastic materials dissolved in an organic solvent, such as toluene and 
ethyl acetate. Ordinary silicone rubber is not resistant to silicone oil. 
Silicone fluoride rubber and fluorine base rubber are resistant to 
silicone oil, while ordinary silicone rubber is resistant to silicone 
fluoride oil and fluorine-contained oil or the like. Also ordinary 
silicone rubber is oil resistant to fatty acid modified silicone oil 
containing ordinary vegetable oil, ethylene glycol, propylene glycol or 
carboxylic acid modified silicone oil. 
The offset preventing layer 5 is composed of room temperature vulcanized 
silicone rubber, for example, KE 12 and KE 112 (commercial name) dissolved 
in the organic solvent. Both types of room temperature vulcanized rubbers, 
namely bond-type and addition-type, can be used equally. 
The heat resistant adhesive layer 2, the heat and oil resistant elastic 
layer 3 and the heat and oil resistant adhesive layer 4 are formed by 
spraying the respective materials thereof on a supporting member or by 
immersing the supporting member in the respective materials. The heat and 
oil resistant elastic layer 3 can be formed by ordinary press 
vulcanization or a mold method emplying room temperature vulcanized 
silicone rubber. The offset preventing layer 5 is formed by coating 
component materials thereof or by pouring the materials into a given 
cavity before the solvent of the heat and oil resistant adhesive layer 4 
is completely evaporated, followed by air drying or heating. When the 
above mentioned heat and oil resistant adhesive layer 4 is composed of 
silastic 733 or silastic 142 (commercial name), and the offset preventing 
layer 5 is composed of silicone rubber, the offset preventing layer 5 must 
be formed in ordinary atmosphere within 24 hours, preferably in 1 to 5 
hours, after the heat and oil resistant adhesive layer 4 has been formed. 
For example, when the heat and oil resistant adhesive layer 4 is 
approximately 100.mu. thick and it is dried by air drying in ordinary 
atmosphere, it is necessary to form the offset preventing layer 5 within 
24 hours after the heat and oil resistant adhesive layer 4 has been 
formed. Furthermore, when approximately 100.mu. thick heat and oil 
resistant adhesive layer 4 is heated to dryness, it is necessary to form 
the offset preventing layer 5 within less than 24 hours after the heat and 
oil resistant adhesive layer has been formed. 
The reason why the above-mentioned method is adopted is that even if the 
heat and oil resistant elastic layer 3 is formed by utilizing silicone 
fluoride rubber, and the offset preventing layer 5 is formed by coating 
room temperature vulcanized silicone rubber on the outer surface of the 
layer 3, the offset preventing layer 5 does not adhere to the heat and oil 
resistant elastic layer 5 at all. Furthermore, when, silicone rubber, 
which is not resistant to silicone oil, is dissolved in the solvent and 
coated as an adhesive, on the heat and oil resistant elastic layer 3, and 
the offset preventing layer 5 is formed thereon, the offset preventing 
layer 5 adheres very well. However, when an oil for offset prevention 
permeates the above-mentioned adhesive layer, the offset preventing layer 
5 peels off. 
A belt-shaped member can be used as a supporting member 1 for the 
above-mentioned layers. 
EXAMPLE 1 
Heat resistant adhesive layer 2 was formed on a roll-shaped core by 
employing silastic 733 (commercial name), and then heat and oil resistant 
elastic layer 3 was formed thereon by ordinary press vulcanization 
employing silicone fluoride rubber or silastic LS-63U, and on the layer 3 
was formed heat and oil resistant adhesive layer 4 by employing silastic 
733 dissolved in the organic solvent. In approximately one hour, offset 
preventing layer 5 was formed by employing KE 12 dissolved in the orginaic 
solvent, followed by air drying for not less than 24 hours. The offset 
preventing layer did not peel off the thus prepared roller even if the 
roller was heated to 200.degree. C. and was coated with a silicone oil 
(commercial name KF 96) for preventing offset. 
EXAMPLE 2 
As in Example 1, heat resistant adhesive layer 2, and heat and oil 
resistant elastic layer 3 were formed. Then heat and oil resistant 
adhesive layer 4 was formed by employing silastic L8-63U dissolved in the 
organic solvent. As in Example 1, when the thus prepared roller was heated 
to 200.degree. C. and coated with KF 96, the offset preventing layer 5 did 
not peel off.