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US4055550A
Expired / Lapsed
US
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Continuous process for the production of partially blocked isocyanates
Assignee: Cargill Inc
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Filing: 1976-12-08
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Granted: 1977-10-25
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Expires: 1996-12-08
Abstract
Abstract A method for manufacturing partially blocked isocyanate curing agents in which a polyisocyanate and a blocking agent for the polyisocyanate are separately and continuously metered into a reaction zone in predetermined nonstoichiometric proportion under reaction conditions, and in which the reaction mixture is continuously withdrawn from the reaction zone to provide a partially blocked isocyanate curing agent product. The partially blocked isocyanate curing agent product may be continuously reacted with a polyhydroxy resin coating precursor at a temperature below the unblocking temperature of the blocking agent in respect of the polyisocyanate to provide a heat curable powder coating composition.
Inventors
- 👤 K. A. Pai Panandiker
- 👤 David E. Tweet
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 18:52
CPC Classifications
C; C08; C08G; C08G18/00; C08G18/06; C08G18/70; C08G18/72; C08G18/80; C08G18/8061; C08G18/807; C08G2150/00; C08G2150/20
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
133 words
A method for manufacturing partially blocked isocyanate curing agents which are the reaction product of a polyfunctional isocyanate and a blocking agent for the isocyanate which is capable of splitting from the curing agent at elevated temperature to regenerate isocyanate functionality, comprising the steps of separately and continuously metering a polyisocyanate and a blocking agent for said polyisocyanate into a reaction zone in predetermined stoichiometric isocyanate excess to provide a reaction mixture in the reaction zone at reaction temperature, continuously withdrawing the reaction mixture from said reaction zone to provide a partially blocked isocyanate curing agent reaction product after maintaining said reaction mixture in the reaction zone for a time sufficient to reduce the free isocyanate content of the reaction product to at least a predetermined level indicating substantial completion of the reaction.
Claim 2
Independent Claim
133 words
A method for manufacturing partially blocked isocyanate curing agents which are the reaction product of a polyfunctional isocyanate and a blocking agent for the isocyanate which is capable of splitting from the curing agent at elevated temperature to regenerate isocyanate functionality, comprising the steps of separately and continuously metering a polyisocyanate and a blocking agent for said polyisocyanate into a reaction zone in predetermined stoichiometric isocyanate excess to provide a reaction mixture in the reaction zone at reaction temperature, continuously withdrawing the reaction mixture from said reaction zone to provide a partially blocked isocyanate curing agent reaction product after maintaining said reaction mixture in the reaction zone for a time sufficient to reduce the free isocyanate content of the reaction product to at least a predetermined level indicating substantial completion of the reaction.
Claim 3
Dependent Claim
24 words
A method in accordance with claim 1 wherein said blocking agent is selected from the group consisting of epsilon caprolactam, and methyl ethyl ketoxime.
Claim 4
Dependent Claim
27 words
A method in accordance with claim 1 wherein said polyisocyanate is selected from the group consisting of isophorone diisocyanate, toluene diisocyanate, isocyanate polyol prepolymers and mixtures thereof.
Claim 5
Dependent Claim
15 words
A method in accordance with claim 1 wherein said isocyanate is an isocyanate polyol prepolymer.
Claim 6
Dependent Claim
43 words
A method in accordance with claim 1 wherein a polyol is metered into said reaction zone simultaneously with said polyisocyanate and said blocking agent and wherein said excess isocyanate functionality is calculated to account for the reaction of said polyisocyanate with said polyol.
Claim 7
Dependent Claim
33 words
A method in accordance with claim 1 wherein said reaction mixture is maintained in said reaction zone for a period of time in the range of from about 15 to about 300 seconds.
Claim 8
Dependent Claim
27 words
A method in accordance with claim 1 wherein said reaction zone is maintained at a temperature in the range of from about 250 to about 400° F.
Claim 9
Dependent Claim
59 words
A method in accordance with claim 1 wherein said partially blocked isocyanate reaction product is further reacted with a hydroxy functional coating composition polymer at a temperature below the unblocking temperature of said blocking agent in respect of said polyisocyanate to produce a thermosettable coating composition, and wherein said coating composition is powdered to provide a powder coating composition.
Claim 10
Dependent Claim
23 words
A method in accordance with claim 1 wherein a catalyst is employed to generate a peak reaction exotherm reaction in the reaction zone.
Claim 11
Dependent Claim
30 words
A method in accordance with claim 1 wherein a reaction temperature above the unblocking temperature of said blocking agent in respect of said polyisocyanate is maintained in said reaction zone.
Claim 12
Dependent Claim
33 words
A method in accordance with claim 1 wherein an effective reaction time and temperature below the unblocking temperature of said blocking agent in respect of said polyisocyanate is maintained in said reaction zone.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1980-10-24 | 1981-04-25 | 1981-10-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-10-24 | 1985-04-25 | 1985-10-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-10-24 | 1989-04-25 | 1989-10-25 | $7700.00 | Window Closed / Lapsed |