US4895983A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for producing methylol urea solution and process for producing slow-releasing nitrogenous fertilizer using the same
Assignee: Mitsubishi Chemical Corp
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Filing: 1989-04-13
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Granted: 1990-01-23
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Expires: 2009-04-13
Abstract
Abstract A process for producing a methylol urea solution which comprises carrying out addition reaction between urea and formaldehyde in the presence of water and an alkali, wherein said alkali is a polyphosphoric acid salt; and a process for producing a slow-releasing nitrogenous fertilizer which comprises subjecting the resulting methylol urea solution to dehydration condensation and drying the resulting condensate are disclosed. The methylol urea solution undergoes no substantial pH variation with time either during or after the addition reaction, and the fertilizer obtained therefrom is excellent in slow-releasing properties.
Inventors
- 👤 Kiyoshi Nakayama
- 👤 Hiroshi Aoki
- 👤 Hisato Saitoh
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 10:06
CPC Classifications
C; C05; C05C; C05C9/00; C05C9/02
Claims Analysis
Total Claims: 22
Claim 1
Independent Claim
99 words
A process for producing a methylol urea solution which comprises an addition reaction between urea and formaldehyde in the presence of water and at least one alikali selected from the group consisting of alkali metal salts of pyrophosphoric acid and tripolyphosphoric acid, wherein the addition reaction is carried out at a temperature in the range of room temperature to 100° C. and at a pH of from 7 to 10, using 0.4 to 3moles of the urea to 1 mole of the formaldehyde in the presence of 0.5 to 9%, by weight based on the formaldehyde, of said alkali.
Claim 2
Dependent Claim
99 words
A process for producing a methylol urea solution which comprises an addition reaction between urea and formaldehyde in the presence of water and at least one alikali selected from the group consisting of alkali metal salts of pyrophosphoric acid and tripolyphosphoric acid, wherein the addition reaction is carried out at a temperature in the range of room temperature to 100° C. and at a pH of from 7 to 10, using 0.4 to 3moles of the urea to 1 mole of the formaldehyde in the presence of 0.5 to 9%, by weight based on the formaldehyde, of said alkali.
Claim 3
Dependent Claim
25 words
A process as in claim 1 wherein said alkali is selected from the group consisting of sodium pyrophosphate, potassium pyrophosphate, sodium tripolyphosphate, and potassium tripolyphosphate.
Claim 4
Dependent Claim
21 words
A process as in claim 1, wherein said addition reaction is carried out at a pH of from 8 to 10.
Claim 5
Dependent Claim
23 words
A process as in claim 1, wherein said addition reaction is carried out at a temperature of from 40° C. to 80° C.
Claim 6
Dependent Claim
45 words
A process as in claim 1, wherein a solid urea, an aqueous formaldehyde solution, and at least one kind of alkali selected from the group consisting of sodium pyrophosphate, potassium pyrophasphate, sodium tripolyphosphate, and potassium tripolyphosphate, are used at pH of from 7 to 10.
Claim 7
Dependent Claim
123 words
A process for producing a slow-releasing nitrogenous fertilizer which comprises an addition reaction between urea and formaldehyde in the presence of water and at least one alkali selected from the group consisting of alkali m etal salts of pyrophosphoric acid and tripolyphosphoric acid to prepare a methylol urea solution, carrying out a dehydration condensation of the resulting methylol urea solution and drying the resulting condensate, wherein the addition reaction is carried out at a temperature in the range of room tem,perature to 100° C. and at a pH of from 7 to 10 using 0.4 to 3 moles of the urea to 1 mole of the formaldehyde in the presence of 0.5 to 9% by weight, based on the formaldehyde, of said alkali.
Claim 8
Dependent Claim
123 words
A process for producing a slow-releasing nitrogenous fertilizer which comprises an addition reaction between urea and formaldehyde in the presence of water and at least one alkali selected from the group consisting of alkali m etal salts of pyrophosphoric acid and tripolyphosphoric acid to prepare a methylol urea solution, carrying out a dehydration condensation of the resulting methylol urea solution and drying the resulting condensate, wherein the addition reaction is carried out at a temperature in the range of room tem,perature to 100° C. and at a pH of from 7 to 10 using 0.4 to 3 moles of the urea to 1 mole of the formaldehyde in the presence of 0.5 to 9% by weight, based on the formaldehyde, of said alkali.
Claim 9
Dependent Claim
27 words
A process as in claim 3, wherein said polyphosphoric acid salt is selected from the group consisting of sodium pyrophosphate, potassium pyrophosphate, sodium tripolyphosphate, and potassium tripolyphosphate.
Claim 10
Dependent Claim
20 words
A process as in claim 3, wherein said urea is solid urea and said formaldehyde is an aqueous formaldehyde solution.
Claim 11
Dependent Claim
21 words
A process as in claim 6, wherein a molar ratio of urea, formaldehyde, and water is 1 to 2:1:1.3 to 4.5.
Claim 12
Dependent Claim
21 words
A process as in claim 9, wherein a molar ratio of urea, formaldehyde, and water is 1.1 to 1.6:1:1.5 to 3.
Claim 13
Dependent Claim
21 words
A process as in claim 6, wherein said addition reaction is carried out at a pH of from 8 to 10.
Claim 14
Dependent Claim
23 words
A process as in claim 6, wherein said addition reaction is carried out at a temperature of from 40° C. to 80° C.
Claim 15
Dependent Claim
27 words
A process as in claim 6, wherein said dehydration condensation is carried out in the presence of at least one of a phosphoric acid and citric acid.
Claim 16
Dependent Claim
21 words
A process as in claim 6, wherein said dehydration condensation is carried out at a pH of from 3 to 7.
Claim 17
Dependent Claim
21 words
A process as in claim 14, wherein said dehydration condensation is carried out at a pH of from 4 to 7.
Claim 18
Dependent Claim
23 words
A process as in claim 6, wherein said dehydration condensation is carried out at a temperature of from room temperature to 120° C.
Claim 19
Dependent Claim
23 words
A process as in claim 16, wherein said dehydration condensation is carried out at a temperature of from 40° C. to 110° C.
Claim 20
Dependent Claim
22 words
A process as in claim 6, wherein said drying is carried out at a temperature of from 60° C. to 300° C.
Claim 21
Dependent Claim
22 words
A process as in claim 18, wherein said drying is carried out at a temperature of from 80° C. to 250° C.
Claim 22
Dependent Claim
96 words
A process as in claim 6, wherein a solid urea and an aqueous formaldehyde solution are used in a molar ratio of urea, formaldehyde and water being 1 to 2:1:1.3 to 4.5, in the presence of at least one alkali selected from the group consisting of sodium pyrophosphate, potassium pyrophospahte, sodium tripolyphosphate, and potassium tripolyphosphate, at a pH of from 7.5 to 10 to form methylol urea solution, and the resulting methylol urea is condensed in the presence of at least one of phosphoric acid and citric acid, at a pH of from 3 to 7.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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| 3.5 Years (Year 4) | 1993-01-22 | 1993-07-24 | 1994-01-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-01-22 | 1997-07-24 | 1998-01-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-01-22 | 2001-07-24 | 2002-01-23 | $7700.00 | Window Closed / Lapsed |