Thermal roller fixing device for thermally fixing a toner image in electronic copying machines

A thermal fixing device for thermally fixing a toner image held on the front side of a recording sheet, which comprises:

• a heating roller provided to confront the toner image of the sheet and including a silicone rubber layer at lest a surface portion of which is constructed so as to substantially exclude silica;
• and
• a pressing member provided to confront the back side of the recording sheet for making pressure contact with said heating roller through the sheet when the recording sheet si transported between the heating roller and the pressing member,
• wherein at least the surface portion of the silicone rubber layer is formed of a silicone rubber compound which contains:
• (A) diorgano-polysiloxane expressed by the equation (1);
• R.sup.1.sub.a Si.sub.(4-a)/2 (where R.sup.1 expresses homogeneous or heterogeneous, nonsubstituted or substituted monohydrocarbon group or hydroxide group, and is a number between 1.98-2.02);
• and
• (B) organopolysiloxane containing R.sup.2.sub.3 SiO.sub.1/2 units (wherein R.sup.2 is a homogeneous or heterogeneous, nonsubstituted or substituted monohydrocarbon group, hydrolyzable group, hydroxide group, or hydrogen atom-selecting group or atom) and SiO.sub.2 units in a molar ratio of 0.5-1.5, wherein the .tbd.SiOH group contained a single molecule is 0.2 moles/100 g or less.

A thermal fixing device for thermally fixing a toner image held on the front side of a recording sheet, which comprises:

• a heating roller provided to confront the toner image of the sheet and including a silicone rubber layer at least a surface portion of which is constructed so as to substantially exclude silica;
• and
• a pressing member provided to confront the back side of the recording sheet for making pressure contact with said heating roller through the sheet when the recording sheet is transported between the heating roller and the pressing member,
• wherein at least the surface portion of the silicone rubber layer is formed of a silicone rubber compound which contains:
• (a) diorganopolysiloxane containing two or more unsaturated aliphatic hydrocarbon groups bonded to the silicone atom(s) in a single molecule, as expressed by the equation (1);
• R.sup.1.sub.2 Si.sub.(4-a)/2 (where R.sup.1 stresses homogeneous or heterogeneous, nonsubstituted or substituted monohydrocarbon group or hydroxide group, and a is a number between 1.98-2.02)
• (b) organopolysiloxane containing R.sup.2.sub.3 SiO.sub.1/2 units (wherein R.sup.2 is a homogeneous or heterogeneous, nonsubstituted or substituted monohydrocarbon group, hydrolyzable group, hydroxide group, or hydrogen atom-selecting group or atom) and SiO.sub.2 units in a molar ratio of 0.5-1.5, and containing one or more .tbd.SiOH.dbd.CH.sub.2 group in a single molecular together with .tbd.SiOH group is 0.01 moles/100 g or less in a single molecule, and the .tbd.SiX group (wherein X is a hydrolyzable group) is 0.01 moles/100 g or less;
• and
• (c) organohydrogenpolysiloxane containing two or more hydrogen atoms bonded to silicone atom(s) in a single molecule.

A thermal fixing device for thermally fixing a toner image held on the front side of the recording sheet, which comprises:

• a heating roller provided to confront the toner image of the recording sheet and including a silicone rubber layer at least a surface portion of which is formed of a silicone rubber compound which contains:
• (A) diorganopolysiloxane expressed by the equation (1);
• R.sup.2.sub.a Si.sub.(4-a)/2 (where R.sup.1 expresses homogeneous or heterogeneous, nonsubstituted or substituted monohydrocarbon group or hydroxide group, and a is a number between 1.98-2.02);
• and
• (B) organopolysiloxane containing R.sup.2.sub.3 Si0.sub.1/2 units (wherein R.sup.2 is a homogeneous or heterogeneous, nonsubstituted or substituted monohydrocarbon group, hydrolyzable group, hydroxide group, or hydrogen atom-selecting group or atom) and SiO.sub.2 units in a molar ratio of 0.5-1.5, wherein the .tbd.SiOH group contained a single molecule is 0.2 moles/100 g or less;
• and
• a pressing member provided to confront the back side of the recording sheet for making pressure contact with said heating roller through the sheet when the recording sheet is transported between the heating roller and the pressing member.

A thermal fixing device for thermally fixing a toner image held on the front side of the recording sheet, which comprises:

• a heating roller provided to confront the toner image of the recording sheet and including a silicone rubber layer at least a surface portion of which is formed of a silicone rubber compound which contains:
• (a) diorganopolysiloxane containing two or more unsaturated aliphatic hydrocarbon groups bonded to the silicone atoms(s) in a single molecule, as expressed by the equation (1);
• R.sup.1.sub.a Si.sub.(4-a)/2 (where R.sup.1 expresses homogeneous or heterogeneous, nonsubstituted or substituted monohydrocarbon group or hydroxide group, and a is a number between 1.98-2.02);
• (b) organopolysiloxane containing R.sup.2.sub.3 SiO.sub.1/2 units (wherein R.sup.2 is a homogeneous or heterogeneous, nonsubstituted or substituted monohydrocarbon group, hydrolyzable group, hydroxide group, or hydrogen atom-selecting group or atom) and SiO.sub.2 units in a molar ratio of 0.5-1.5, and containing one or more .tbd.SiOH.dbd.CH.sub.2 group in a single molecule together with .tbd.SiOH group is 0.01 moles/100 g or less in a single molecule, and the .tbd.SiX group (wherein X is a hydrolyzable group) is 0.01 moles/100 g or less;
• and
• (c) organohydrogenpolysiloxane containing two or more hydrogen atoms bonded to silicone atom(s) in a single molecule;
• and
• a pressing member provided to confront the back side of the recording sheet for making pressure contact with said heating roller through the sheet when the recording sheet is transported between the heating roller and the pressing member.