CA2041264A1 - Low molecular weight urea-formaldehyde reaction products and process for the preparation thereof - Google Patents

Low molecular weight urea-formaldehyde reaction products and process for the preparation thereof

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Publication number
CA2041264A1
CA2041264A1 CA 2041264 CA2041264A CA2041264A1 CA 2041264 A1 CA2041264 A1 CA 2041264A1 CA 2041264 CA2041264 CA 2041264 CA 2041264 A CA2041264 A CA 2041264A CA 2041264 A1 CA2041264 A1 CA 2041264A1
Authority
CA
Canada
Prior art keywords
urea
formaldehyde
reaction
molecular weight
low molecular
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Abandoned
Application number
CA 2041264
Other languages
French (fr)
Inventor
Michael Worsley
Kenneth M. Worsley
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Individual
Original Assignee
Individual
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Individual filed Critical Individual
Priority to CA 2041264 priority Critical patent/CA2041264A1/en
Publication of CA2041264A1 publication Critical patent/CA2041264A1/en
Abandoned legal-status Critical Current

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Abstract

"LOW MOLECULAR WEIGHT UREA-FORMALDEHYDE
REACTION PRODUCTS AND PROCESS FOR THE PREPARATION THEREOF"

ABSTRACT OF THE DISCLOSURE

Low molecular weight urea-formaldehyde reaction products are provided. Such products exhibit cold water solubility. They find use as a sustained nitrogen-release source for animals and plants. A three-stage process is provided for preparing the reaction products. The first stage comprises reacting urea and formaldehyde in an alkaline, alcoholic solution. Then the solvent is distilled off to form a melt. In the final stage the melt is polymerized to form the cold water soluble, low molecular weight reaction product.

Description

2Q~126~
1 Field of the Invention 2 The present invention relates to a urea-formaldehyde 3 reaction product for use as a sustained nitrogen-release source 4 and to a process for the preparation thereof.

BACKGROUND OF THE INVENTION
6 Ammonia-based fertilizers have long been utilized as 7 means for augmenting the nitrogen availability within the nitrogen cycle. Deleteriously, however, bacterial oxidation of 9 the ammonia therein converts it initially to nitrite and then to nitrate before it can be utilized by the plants. As is well 11 known in the art, nitrites are toxic. The nitrates are usually 12 lost as a nitrogen source by leaching out and ultimate reduction 13 to nitrogen.
14 In order to eliminate such nitrification processes, urea has long been used as a slow, or sustained, nitrogen-16 release source. However, the enzyme urease is present in the 17 soil. Urease is functional to convert urea to ammonia extremely 18 rapidly.
19 Similarly, urea has been utilized as an ammonium source for ruminants. But, urease is also present in the rumen of such 21 animals. Rapid release of ammonia within the rumen will cause 22 the animal undue distress, and therefore is not desirable.
23 In order to circumvent the problems associated with 24 urea the prior art processes have provided various condensation products of the reaction between urea and formaldehyde 26 (hereinafter referred to as the urea-formaldehyde reaction).
27 The reaction of urea with formaldehyde and the 28 resultant products are well documented.

1 The reaction products will vary depending upon the 2 reaction conditions. Under basic conditions the yield of 3 methylol compounds predominates. Under acidic conditions, 4 methylene-bonded compounds are produced.
U.S. Patent 3,759,687, issued to A. Nobell, and U.S.
6 2,644,806, issued to M. A. Kise, exemplify the prior art 7 teachings on the urea-formaldehyde reaction undertaken in aqueous 8 solution and the properties of the condensation products thereof.
9 It will be readily appreciated that such condensation products comprise urea-formaldehyde polymers having high 11 molecular weights. The control of the degree of polymerization 12 however, is difficult using these prior art processes.
13 Typically, the polymer chains may comprise from 4 to 7 urea 14 units. It is undesirable to have such high molecular weight polymers because bacteria have difficulty in breaking down 16 polymer chains which contain more than 4 or 5 urea units therein.
17 Additionally, such compositions exhibit solubility only in hot 18 water. Therefore, when these prior art compositions are utilized 19 as, for example, fertilizers, in order to be effective they must be ploughed into the ground.
21 There exists, therefore the need for a sustained 22 nitrogen-release urea-formaldehyde product possessing the 23 following characteristics:
24 - low molecular weight polymer chains preferably containing no more than four urea units; and 26 - cold water solubility whereby the need for 27 ploughing the product in would be eliminated as 28 the product would go into solution readily in rain 29 water or the like;

2~1 2~
1 and for a process characterized by the following:
2 - simplicity;
3 - inexpensiveness; and 4 - imparting a degree of controllability to the polymerization process.

6 DESCRIPTIO~ QF__THE DRAWINGS
7 Figure 1 is a plot of the concentration of ammonia in 8 the rumen of sheep verses time which is included to demonstrate 9 the slow release properties of the products of the present invention.

12 In accordance with the present invention it has been 13 discovered that if the reaction between urea and formaldehyde is 14 conducted under alkaline conditions (preferably utilizing either NaOH or KOH) in an alcohol (specifically ethanol or methanol) it 16 is possible, within limits, to control the degree of 17 polymerization, and thereby provide low molecular weight reaction 18 products which are substantially cold water soluble. By cold 19 water æoluble is meant soluble at 20C.
Advantageously, by utilizing either of said alcohols 21 as the reaction media it is possible to recover substantially all 22 the alcohol for recycling. Additionally, the reaction is 23 conducted at a lower temperature than in the aqueous reactions, 24 with concomitant reduction in heating costs.
Broadly stated, the invention is a process for 26 preparing a urea-formaldehyde condensation reaction product for 27 use as a sustained nitrogen-release source, comprising the steps 2~ 21~
l of: (a) reacting urea and at least one of gaseous formaldehyde 2 and solid paraformaldehyde in an alkaline non-aqueous solution 3 of methanol or ethanol with heat, the molar ratio of urea to 4 formaldehyde or paraformaldehyde being in the range of between about 2.1:1 - 3:1; (b) distilling off the methanol or ethanol 6 solvent to thereby yield a low melting point mixture in molten 7 form; (c) adding an acid or acid-producing substance to the melt 8 and heating the mixture to a temperature in the range of about 9 110C until solidification thereof takes place; and (d) further heating the product of step (c) to remove the water of reaction 11 to thereby yield a urea-formaldehyde reaction product comprising 12 urea, diureaformaldehyde, triureaformaldehyde and cold water 13 insoluble urea formaldehyde resin.

The invention involves a three-stage process. The 16 process is defined by the following reactions:
17 O heat O 0 18 NH2-C-NH2 + CH2O OH? NH2-C-NH-CH2OH + NH2-C-NH2 (1) EtOH/MeOH

21 Q heat 0 22 0 U H+ U a 23 NH2-C-NH-CH2OH + NH2-C-NH2 ~NH2-C-NH-CH2-NH-C-NH2 +

O O O

26 NH2-C-NH-CH2-NH-C-NH-CH2-NH-C-NH2 (2) 27 In the first stage of the process urea and gaseous 28 formaldehyde or paraformaldehyde are reacted in a non-aqueous, 2 ~ ~
1 alkaline, alcoholic solution to form methylol urea and urea as 2 outlined in reaction 1 supra.
3 The reactants are of commercial grade. The ratio of 4 urea to formaldehyde or paraformaldehyde is critical to ensure formation of the desired reaction products. The ratio of urea 6 to formaldehyde (or paraformaldehyde) should be in the range of 7 between 2.1:1 to about 3:1 because the product would be insoluble 8 at less than 2 to 1.
9 The alcohol utilized in the process must be ethanol or methanol. The concentration of alcohol would be 4 mls of alcohol 11 to each gm of urea.
12 The base is utilized as a reaction catalyst. The base 13 can be selected from either sodium hydroxide or potassium 14 hydroxide. The concentration of the hydroxide should be in the range of about 0.5% or sufficient to adjust the alcohol solution 16 pH to between about 10 - 12 and maintain the alkalinity of the 17 solution until the last stage of the process. In the absence of 18 the base the reaction produces, undesirably, large amounts of hot 19 water insoluble adducts.
The reaction is conducted at the temperature of the 21 boiling point of the particular alcohol solvent.
22 The reaction of the first stage is carried out as 23 follows.
24 The urea is first added to the alcohol solution made alkaline by addition of the hydroxide thereto. The formaldehyde 26 or paraformaldehyde is added gradually with heating until 27 reaching the boiling point of the alcohol. The amount of alcohol 28 utilized is sufficient to permit the solvation of the urea at 29 this temperature. The urea gradually dissolves as the methylol - 2~:1. 2~
1 groups are formed. Upon addition of all the para or formaldehyde 2 at the solvent boiling point all the urea should be in solution.
3 The first stage reaction yields approximately 50 ~ percent methylol urea and slightly more than 50 percent urea.
The second stage of the process comprises distilling 6 off the alcohol, leaving a low melting point solid in the form 7 of a melt. Vacuum may optionally be used to remove the alcohol.
8 The temperature is controlled to leave the solid as a melt. It 9 will be noted that by recovering the alcohol being evaporated off, it may be recycled.
11 The third staye of the process involves raising the 12 melt to an elevated temperature and adding an acid or acid-13 producing substance thereto, to form the diureaformaldehyde and 14 higher molecular weight polymer chain compounds. The formed solid is heated further to drive off the water of reaction.
16 Specifically, the melt from the second stage is heated 17 to a temperature of about 110C. This temperature is selected 18 to ensure fluidity of the melt and a rapid reaction with the 19 acid. It will be noted that if the temperature is increased the content of hot water insoluble urea formaldehyde resin formed 21 will deleteriously increase concomitantly.
22 An acid or acid-releasing substance is added to the 23 melt with rapid stirring. The addition of the former initiates 24 the reaction of the methylol groups with the excess unreacted urea. The acid may be a mineral acid, for example hydrochloric.
26 Alternatively, an organic acid, for example, glacial acetic acid 27 or an acid-releasing substance such as ammonium chloride may be 28 utilized. The amount of acid should be sufficient to neutralize 29 the base. The amount of acid utilized has been found to 2 ~

1 accelerate the rate of polymerlzation to the final product.
2 However, the reaction will take place, albeit less rapidly 3 without the addition of an acid-releasing substance. For 4 example, with addition 1 gm. of ammonium chloride to 100 gm urea at 110C , solidification will take place within five minutes.
6 The formed solid is then heated to a temperature of 7 130C to drive off the water of reaction and produce the final 8 product.

9 Example I
100 gm of urea were added to a solution containing 400 11 ml methanol and 1 ml of concentrated potassium hydroxide. 23.8 12 gm of paraformaldehyde were added with heating until the boiling 13 point of methanol, 65C, was reached. Boiling was continued 14 until all of the urea went into solution. The solvent was then evaporated leaving a melt. The melt was heated to 110C for a 16 period of approximately 2 minutes and 1 gm of ammonium chloride 17 in 3 ml of water was added with rapid stirring. Upon 18 solidification, the solid was heated to 130C to drive off the 19 water of the reaction.
Analysis of the solid showed the nitrogen content was 21 as follows:
22 % N = 42.3 23 Results 24 25 gm of the solid were ground and added to 500 ml water. The solution was heated to boiling, filtered and the solid 26 dried and weighed. The solution was cooled to room temperature 27 and filtered. The solid product was dried and weighed.

~ ~9 ~

1 The solid product was tested to determine its 2 solubility.
3 % solubility in hot water = 90 4 % solubility in cold water = 79 Example II
6 100 gm of urea were added to a solution containing 400 7 ml ethanol and 1 ml of concentrated potassium hydroxide. 22.2 8 gm of paraformaldehyde were added slowly with heating until the 9 boiling point of ethanol (78.3C) was achieved. The solution was heated until all the urea went into solution. The solvent was 11 evaporated, leaving a melt. The melt was heated to 110C for 12 about 2 minutes and 1 ml of glacial acetic acid was added with 13 rapid stirring. Upon solidification, the product solid was 14 heated to 130C to drive off the water of the reaction.
Analysis of the solid showed the nitrogen content was 16 as follows:
17 % N = 42.6 18 Results 19 25 gm of the solid were ground and added to 500ml water. The solution was heated to boiling and filtered. The 21 solid was dried and weighed. The solution was cooled to room 22 temperature and filtered. The solid was dried and weighed.
23 The solid product was tested to determine its 24 solubility:
% solubility in hot water = 92 26 % solubility in cold water = 82 1 Example III
2 The following table presented herebelow provides 3 characterization data of the urea-formaldehyde reactlon products 4 produced in accordance with the process of the invention. An analysis of a commercial product prepared by a area-formaldehyde 6 reaction process which was carried out using aqueous conditions 7 is provided for comparison purposes. As well, theoretical values 8 calculated from statistical distribution at the 2.1:1 urea to 9 formaldehyde ratio are indicated.
All constituent values are given as percent of total 11 nitrogen.

12 ~atio of Reactants Urea MDU DMTU
13 Theoretical 28 25 19 28 14 Commercial 27 25 14.6 29.5 Product 16 2.1:1 UF
17 Invention 26.7 39.7 12.2 21.4 18 Product 19 Commercial 34 25 10.6 24.5 Product 21 2.25:1 UF
22 Invention 32.4 34.7 11.5 21.4 23 Product 24 where UF is parts of urea to formaldehyde MDU is diureaformaldehyde 26 DMTU is triureaformaldehyde 27 CWIN is cold water insoluble urea-formaldehyde 28 resin

Claims (3)

1. A process for preparing a urea-formaldehyde condensation reaction product for use as a sustained nitrogen-release source comprising the steps of:
(a) reacting urea and at least one of gaseous formaldehyde and solid paraformaldehyde in an alkaline solution of methanol or ethanol with heat, said molar ratio of urea to formaldehyde or paraformaldehyde being in the range of between about 2.1:1 - 3:1;
(b) distilling off the methanol or ethanol solvent to thereby yield a low melting point mixture in molten form;
(c) adding an acid or acid-producing substance to the melt and heating the mixture to a temperature in the range of about 110°C until solidification thereof takes place; and (d) further heating the product of step (c) to remove the water of reaction to thereby yield a urea-formaldehyde reaction product comprising urea, diureaformaldehyde, triureaformaldehyde and cold water insoluble urea-formaldehyde resin.
2. The process as set forth in claim 1 wherein said alkali used to prepare the alkaline solution of methanol or ethanol comprises sodium hydroxide or potassium hydroxide.
3. The process as set forth in claim 1 wherein:
the pH in step (a) is maintained in the range 10 - 12 and the reaction is conducted at a temperature substantially equal to the boiling point of alcohol.
CA 2041264 1991-04-25 1991-04-25 Low molecular weight urea-formaldehyde reaction products and process for the preparation thereof Abandoned CA2041264A1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CA 2041264 CA2041264A1 (en) 1991-04-25 1991-04-25 Low molecular weight urea-formaldehyde reaction products and process for the preparation thereof

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CA 2041264 CA2041264A1 (en) 1991-04-25 1991-04-25 Low molecular weight urea-formaldehyde reaction products and process for the preparation thereof

Publications (1)

Publication Number Publication Date
CA2041264A1 true CA2041264A1 (en) 1992-10-26

Family

ID=4147476

Family Applications (1)

Application Number Title Priority Date Filing Date
CA 2041264 Abandoned CA2041264A1 (en) 1991-04-25 1991-04-25 Low molecular weight urea-formaldehyde reaction products and process for the preparation thereof

Country Status (1)

Country Link
CA (1) CA2041264A1 (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8591983B2 (en) 2006-12-21 2013-11-26 Lignotech Usa, Inc. Bypass protection for protein and starch in animal feed

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8591983B2 (en) 2006-12-21 2013-11-26 Lignotech Usa, Inc. Bypass protection for protein and starch in animal feed

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