Belt for papermarking and process for producing papermaking belt
AssigneeYamauchi Corporation
InventorsAtsuo Watanabe, Takahisa Hikida, Atsushi Watanabe
Life of this patent
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Abstract
A papermaking belt which prevents cracking and inhibits crack growth which includes a reinforcing substrate embedded in a thermosetting polyurethane layer so that the reinforcing substrate and the thermosetting polyurethane layer are integrated with each other and the outer peripheral surface and the inner peripheral surface of the belt are formed by polyurethane layers, the polyurethane layer forming the outer peripheral surface being made of a composition containing a urethane prepolymer having isocyanate groups on its ends and a hardener containing dimethylthiotoluenediamine.
Claims16
A papermaking belt comprising a reinforcing substrate embedded in a thermosetting polyurethane layer including an inner polyurethane layer and an outer polyurethane layer adhering to an outer peripheral surface of said inner polyurethane layer, wherein
- the polyurethane layer forming the outer peripheral surface being made of a composition containing a urethane prepolymer having isocyanate groups on the ends thereof and a hardener containing dimethylthiotoluenediamine, said urethane prepolymer and said hardener being mixed with each other in a ratio setting the value of the equivalent ratio (H/NCO) between active hydrogen groups (H) of said hardener and the isocyanate groups (NCO) of said urethane prepolymer to 1<H/NCO<1.15.
A papermaking belt comprising a reinforcing substrate embedded in a thermosetting polyurethane layer including an inner polyurethane layer and an outer polyurethane layer adhering to an outer peripheral surface of said inner polyurethane layer, wherein
- the polyurethane layer forming said outer peripheral surface is made of a composition containing a urethane prepolymer having isocyanate groups on the ends thereof and a hardener having active hydrogen groups on the ends thereof, said urethane prepolymer and said hardener are mixed with each other in a ratio setting the value of the equivalent ratio (H/NCO) between the active hydrogen groups (H) of said hardener and the isocyanate groups (NCO) of said urethane prepolymer to 1<H/NCO<1.15.
A papermaking belt comprising a reinforcing substrate embedded in a thermosetting polyurethane layer, said thermosetting polyurethane layer including an inner polyurethane layer and an outer polyurethane layer adhering to the outer peripheral surface of said inner polyurethane layer, wherein
- each of said inner polyurethane layer and said outer polyurethane layer being made of a composition containing a urethane prepolymer having isocyanate groups on the ends thereof and a hardener having active hydrogen groups on the ends thereof,
- the composition forming said inner polyurethane layer being prepared by mixing the urethane prepolymer and the hardener with each other in a ratio setting the equivalent ratio (H/NCO) between the active hydrogen groups (H) of the hardener and the isocyanate groups (NCO) of the urethane prepolymer to 0.85≦H/NCO<1, and
- the composition forming said outer polyurethane layer being prepared by mixing the urethane prepolymer and the hardener with each other in a ratio setting the value of said equivalent ratio (H/NCO) to 1<H/NCO<1.15.
A method of manufacturing a papermaking belt including an inner polyurethane layer and an outer polyurethane layer adhering to the outer peripheral surface of said inner polyurethane layer which comprises embedding a reinforcing substrate in a thermosetting polyurethane layer thereby integrating said reinforcing substrate and said thermosetting polyurethane layer with each other, including:
- a first step of hardening a liquid mixture, containing a urethane prepolymer having isocyanate groups on the ends thereof and a hardener having active hydrogen groups on the ends thereof, prepared by mixing the urethane prepolymer and the hardener with each other in a ratio setting the value of the equivalent ratio (H/NCO) between the active hydrogen groups (H) of the hardener and the isocyanate groups (NCO) of the urethane prepolymer to 0.85≦H/NCO<1 at a temperature of 70° C. to 100° C. for forming said inner polyurethane layer;
- a second step of applying a liquid mixture, containing a urethane prepolymer having isocyanate groups on the ends thereof and a hardener having active hydrogen groups on the ends thereof, prepared by mixing the urethane prepolymer and the hardener with each other in a ratio, setting the value of the equivalent ratio (H/NCO) between the active hydrogen groups (H) of the hardener and the isocyanate groups (NCO) of the urethane prepolymer to 1<H/NCO<1.15 onto the outer peripheral surface of said inner polyurethane layer;
- and
- a third step of heating the whole to a temperature of 120° C. to 140° C. for hardening the liquid mixture applied onto the outer peripheral surface of the inner polyurethane layer and forming the outer polyurethane layer while bonding and integrating the inner polyurethane layer and the outer polyurethane layer to and with each other.
A papermaking belt comprising a reinforcing substrate embedded in a thermosetting polyurethane layer including an inner polyurethane layer and an outer polyurethane layer adhering to the outer peripheral surface of said inner polyurethane layer,
- wherein the composition forming said inner polyurethane layer being prepared by mixing a urethane prepolymer and a hardener with each other in a ratio setting the equivalent ratio (H/NCO) between the active hydrogen groups (H) of the hardener and the isocyante groups (NCO) of the urethane prepolymer to 0.85≦H/NCO<1.
Dependencies are inferred from the claim text.