CA1059708A

CA1059708A - Urea-glyoxal-formaldehyde cellulose reactant

Info

Publication number: CA1059708A
Application number: CA197,180A
Authority: CA
Inventors: Tsai H. Chao
Original assignee: American Cyanamid Co
Current assignee: Wyeth Holdings LLC
Priority date: 1973-05-02
Filing date: 1974-04-09
Publication date: 1979-08-07
Also published as: US3903033A

Abstract

A B S T R A C T

A process for preparing stable aqueous solutions of a water-soluble urea-formaldehyde-glyoxal condensation product in which urea, glyoxal and formaldehyde are reacted under very slightly acidic conditions of pH and at a temper-ature of from 40 to 90°C., further reacted under more acidic conditions of pH and at a temperature of from 40 to 90°C., and then adjusted to very slightly acidic conditions of pH.

Description

, 991 ~597~a3 1 This invention relates to a process for the prepara-tion of a cellulose reactant composition to impart durable press properties to cellulosic textile materials.
1,3-Dimethylol-4,5-dihydroxy-2-imidazolidinone has the following structural formula:

HOCH2-N/ \N-CH20H
CH CH
OH OH
The above imidazolidinone has become a valuable tex-tile finishing agent particularly for use as a crease-proofin~
agent on cellulosic textile materials including blends of such materials with other fibers such as polyamides and polyesters.
Although it may be employed as a conventional crease-proofing finish, its present commercial importance is as a post-cure crease-proofing finish.
There are various processes for preparing 1,3-dimeth-ylol-4,5-dihydroxy-2-imidazolidinone from urea, glyoxal and for-maldehyde. In one, urea and glyoxal are reacted under alkalineconditions to produce 4,5-dihydroxy-2-imidazolidinone, which is then reacted with formaldehyde under neutral or alkaline condi-tions. In another process, urea and formaldehyde are reacted under alkaline conditions to produce dimethylol urea which is then reacted with glyoxal under alkaline conditions to form the imidazolidinone. The product of the first-mentioned process, is reported to be dark brown and is said to discolor cloth un-less the intermediate monourein is purified before it is reactsd with formaldehyde. In still another process, urea and glyoxal are reacted at a pH of from 3.8-4.2, followed by reaction with formaldehyde at a pH of 7.0-7.5.

In the above processes the yield is often low and .~

~5~70~3 the products contain large amounts of unreacted formaldehyde and glyoxal.
In some cases the product has been found to be unstable as evidenced by discoloration on aging. In other processes, urea and formaldehyde are re-acted with glyoxal in one step to form the imidazolidinone.
In the processes of the prior art the end products have a defi-ciency in that the fabrics treated therewith release high levels of formal-dehyde before curing thereby causing pollution and a hazardous condition in the immediate environment of the employees of the finishing company.
We have reduced this hazard significantly by using ~he water-soluble urea-formaldehyde-glyoxal condensation products of our invention.
The invention is a process for preparing a textile finish com-position of an aqueous solution of a water-soluble urea-formaldehyde-glyoxal condensation product and the composition and the use of the composition on textiles to produce a curable finish having a low level of emission of formaldehyde which when cured imparts desirable durable press properties to the textile materials thus treated.
The invention provides a process for preparing aqueous solutions of a water-soluble urea-formaldehyde-glyoxa:L cond~sation product containing 1,3-dimethylol-4,5-dihydroxy-2-imidazolidinone, sometimes referred to as dimethylol monourein or dimethylol dihydroxyethyleneurea, that are character-ized by low levels of formaldehyde released by fabric treated ~herewith and which are effective as durable press agents for cellulosic textile materials.
The invention provides a process for preparing an aqueous solution of a water-soluble urea-formaldehyde-glyoxal condensation product character-ized by reacting in an aqueous medium about 1.0 mole of urea, about 1.0 mole of glyoxal and less than 2.0 moles of formaldehyde at a pH maintained between 6.2 and 6.7 and at a temperature of 40 to 90C. until the formation of 1,3-dimethylol-4,5-dihydroxy-2-imidazolidinone is essentially completed; adding an acidic material to the reaction solution to adjust the pH between 2.0 and 3.0; maintaining the pH between 2.0 and 3.0 and at a temperature between 40C. and 90C. for a period of at least 0.5 to 3.0 hours and adding a base to the solution to adjust the final pH of the solution to between 5.0 and

- 2 -.. . .

~L05917~
7Ø The preferred proportion of formaldehyde is about 1.4 to about 1.9 moles per mole of urea. The period for maintaining the temperature at a pH
of 2 to 3 may be increased to more than 3 hours, but to no particular ad-vantage. The free formaldehyde content of the product initially ranges from about 0.2% to about 1.0% on the weight of the solution but after several days it decreases to about 0.2% to 0.5%.
The reaction is preferably carried out in water and the formalde-hyde used may be the commercial 37% or 44% formaldehyde solutions or para-formaldehyde.
In carrying out the process of the invention, certain features of the process of the invention are critical to obtaining successfully the im-provement in the resulting product compositions. Thus, there are two critical features which are necessary, that is first, the reaction using a reduced amount of formaldehyde below the theoretical amount of 2 moles per mole of urea; and secondly, the maintenance of the temperature at about 40 to 90C.
at a pH of 2 to 3, preferably 2.2 to 2.8, for a period of at least 0.5 hours prior to adjusting the p~l to between about 5.0 and 7.0 for carrying out the third step of the reaction.
Preferably in the first step of the process relative amounts of 1 mole of urea and 1 mole of glyoxal as a 40% aqueous solution are reacted with between 1.7 and 1.9 moles of formaldehyde as a 44% aqueous solution at a pH between 6.2 and 6.6 at a temperature between 55 and 65C. until the amount of unreacted or free formaldehyde is about 0.5% to 1.0% by weight of the reaction mixture. It has been found convenient to maintain the temper-ature of the reaction mixture until the desired percentage of free formal-dehyde is attained, the free formaldehyde content being determined by con-ventional analytical procedures. The pH can be conveniently maintained at 6.2 to 6.6 by the dropwise additions of 6.7% aqueous sodium bicarbonate as needed. When the first step of the process is finished the solution is normally cooled.
In the second step of the process the Ph is preferably adjusted by the addition of an acidic material such as citric acid to a pH value ~ 1~5~7CI\8 between 2.4 and 3.0 and the temperature is raised to 60C. and held between 55 and 65C. for a period of at least 1.5 to 3.0 hours. The solution is then cooled to about 25C. and in the third step of the process the pH of the final product is adjusted to a value between 5.0 and 7.0 Examples of the acidic material useful for adjustment of the pH
in the second step of the process to a pH of about 2 to 3 include: organic carboxylic acids such as citric, tartaric7 gluconic, oxalic, malic, and the like; inorganic acids may also be used such as hydrochloric, nitric and the like although the use of carboxylic acids is generally preferred.
In accordance with another aspect of the invention there is pro-vided an aqueous solution of a urea-formaldehyde-glyoxal condensation product as defined above and characterized as a colourless composition containing 1,3-dimethylol-4,5-dihydroxy-2-imida~olidinone having between 1.6 and 1.9 moles of combined formaldehyde per mole of combined, urea, plus water and about 5% of dissolved salts with less than 0.5% free formaldehyde based on the weight of product, and a pH between 6.0 and 7Ø As stated above, the free formaldehyde should be less than 0.5% and preferably less than 0.2%
on the weight of the product.
According to another aspect of the invention there is provided a process for producing a curable low formaldehyde releasing finish on cellu-losic textile materials characterized by applying the aqueous solution as defined in the preceding paragraph, an accelerator and a surface active agent to a cellulosic textile; drying the treated textile, and pressing the dried textile at elevated temperatures.
Preferably the amount of water-soluble urea-formaldehyde-glyoxal condensation product applied to the textile material is in the range of 1%
to 15% based on the weight of the fabric, and there is included an accelerator in the form of zinc nitrate used at between 5.5% and 16.5% based on the weight of the condensation product. The preferred drying temperature of a so-treated textile is between 175F and 250F, and the preferred pressing and curing temperature is between 300F and 420F. Still more preferably, the amount of condensation product employed is between 3% and 8% based on ~ - 4 -~5g~

the welght of the fabric, and a surface active agent is included in an amount of between 0.075% and 1% based on the weight of the fabric. Under these conditions the amount of zinc nitrate accelerator is preferably be-tween 9.5% and 12.5% based on the weight of the condensation product, the drying temperature between 200F.and 225F., and the curing temperature be-tween 320F. and 380F.
The textile treating compositions obtained by the process of this invention are stable almost ...-I
- 4a -597~

1 colorless solutions and are readily dilutable with water in all proportions.
The products of this invention are useful in impart-ing durable press properties to cellulosic textile materials and as such may be applied to such materials by any of the conven-tional procedures used in the textile industry. Thus, they may be applied by padding, dipping, spraying, immersing and the like. The products of this invention are superior to the dur-able press products of the prior art processes from the stand-point of the low levels of formaldehyde released from cellulosicmaterials prior to the conventional curing procedures. The low emission of formaldehyde after the drying operation and prior to the final curing step is an important improvement in post -cure durable press processing. The product of this invention may be employed with other textile agents and auxiliaries such as surface active agents, softeners, brighteners, odorants and other crease-proofing agents.
The nonionic surface active agent used in the exam-ples is the condensation product of nonylphenol with an average of 9.5 moles of ethylene oxide. Other suitable nonionic sur~
factants can also be used, such as other alkyl aryl polyethylene glycol ethers and ethylene oxide adducts of straight chain al-cohols.
In order to illustrate the present invention the fol-lowing examples are given primarily by way of illustration butare not to be construed as limitative. All parts and percent-ages are by weight unless otherwise specifically designated.
Example 1 To a suitable reaction vessel equipped with a stirrer and pH electrodes there is added 79.65 parts (1.165 moles) of 44% formalin, 8.85 parts of water, and 93.5 parts (0.65 mole) of 40~ aqueous glyoxal. Sufficient sodium bicarbonate, about ~5~7108 8 parts of 6.8% aqueous sodium bicarbonate, is added while stirring to provide a pH of 6.2-6.6, followed by 39.0 parts (0.65 mole) of urea. The temperature of the reaction is raised to 50C. and the temperature is allowed to rise to about 60C. and is maintained at this level for 3-3/4 hours. During the 3-3/4 hour period, additional ~mounts of sodium bicarbonate are added as 6.8% aqueous sodium bicarbonate in order to maintain the pH at 6.2-6.6. Thus a total of 28 parts of 6.8% sodium bicarbonate is added during the 3-3/4 hour period.
The reaction mixture is cooled to about 40C. and 8.9 parts of an-hydrous citric acid is added to provide a pH of 2.7. The temperature is then raised to 60C. ~ 2C. The reaction mixture is then stirred at pH 2.7 for 3 hours at 60C. and the pH is then ad~usted to 6.2-6.6 by the addition of 50%
aqueous sodium hydroxide. The reaction mixture is then diluted with water to give a total weight of 270 parts.
The product is an aqueous solution of 1,3-dimethylol-4,5-dihydroxy-2-imidazolidinone containing about 45% solicls and 0.7% of unreacted formalde-hyde. After storage at room temperature for several days the solution contains 0.3% of unreacted formaldehyde.
Example 2 Comparison of Formaldehyde Release Two aqueous pad baths were prepared, the first containing 30% aqueous solution of 1,3-dimethylol-4,5-dihydroxy-2-imidazolidinone prepared by the pro-cess of the invention and the second by a modification of the formaldehyde ratio and holding time to represent the prior art. Applications were made by a conventional procedure to a 65/35 blend of polyester cotton (poplin fab-ric) with a 70% expression using 6% zinc nitrate as accelerator and 0.1% non-ionic as surfactant (Deceresol* NI) dried to about 5% moisture.

* trademark - a nonionic polyether alcohol surfactant ~'~ -6-"--` 11D5~7C~8 1 Using a standard formaldehyde release test (AATCC
112-1972, Levi Strauss Modification) the formaldehyde release in ppm of fabric was determined in each instance. The results are shown in the following table.

Formaldehyde Reiease ppm of fabric . (Avg of 2 observations) Product of Example 1 1127 Product of process using a 2.0 to 1.0 ratio of formaldehyde to urea, no holding time (prior art) - 1342 Exam~le 3 Two aqueous pad baths (C ~ D) were prepared each containing 25~ of aqueous solution.of 1,3-dimethylol-4,5-dihy-droxy-2-imidazolidinone prepared by the process of this inven-tion and modifications (A & B) of the formaldehyde ratios and holding times to represent the prior art as shown in Table 1 ~L05970~3 Q) td C' ~; _~ ,, Lr~ ~ o ,. .
_ C~
~ P;~l ~ _,~ o ~ ~ ,~
cd rd N U~ O r(~
_~ Il~ Ll~ ~1 _ C

a) ~ o U~ o ~ ~ P r~ ~ ~i ~
P ~
a N
1:4 h ~ O O ~ O
~ `.` $ ~o ~.

~1 m ~$ Fq c~ ~
~3

3 ~597~8 ~ he pad baths were applied by standard paddi~g procedure to 65/35 pol~ester~cotton shirting ~abric obtain-i~g a 70% wet pick-up. ~he fabrics, containing about 30%
on the weight of the fabric o~ aqueous solution Or 1,3-di-methylol-4,5-dihydroxy-2-imidazolidinone were dried 1.5 minutes at 225F. and anal~zed.~or ppm formaldehyde release on the weight of the fabric. ~he results shown in ~able I demonstrate that a combination of a lower-formalde-~yde/urea mole ratio and holding the mixture at a low pH
for a period of time is necessar~ to produce a composition which greatly reduces the ppm of formaldeh~de released from the fabrics treated therewith.
_xam~le 4 Pad baths were prepared, (~) containi~g an aque-ous solution of 1,3-dimethylol-4,5-dihydro~y-2-imida~oli-dine prepared by the process of the invention and (B) a prior art produot described below~ Applications were then made by conventional procedures to 65/35 polyester cotton shirting and the durable press result was noted using a standard AATCC test as well as the yellowing to scorch test, AA~C test. ~
In addition, for evaluation of formaldehyde re-~lease effects, the compositio~s were applied by conventionalprocedures to polyester-cotton poplin; and to 1034 cotton twill. ~valuation for ~ormaldeh~de release was the~ made according to method AA~CC 112-1972, ~evi Strauss modifica-tio~0 Bath Composition: 25% reactant; 5% accelerator;
0.1h surfactant at pH 4.3 Bath ~
Product of t~e Inventio~, similar to Example 1.
~ormaldehyde/~l~oxal ratio of ~.8 to 1; held ~ hours at 60 C. at a p~ at 60 C~
~ 9 _ ~059708 ~ath B
~ ~. .
Prior art product, formaldehyde/glyoxal ratio o~
2 to 1, no holding time.
Table II

(25% reactant) Durable Press A?pearance 1 i~ash2 .Jashes Bath A
(Process of the Invention) 2.8 3.1 Bath B 301 3~1 _able III
Yellowing to Scorch 400~.
In ial A~ter Chlorine 30" 60" 90" 30" 60" 90"
Bath A 4.75 4.50 4.00 4.75 4.50 4.00 (Process of the Invention) Bath B 4.75 4.50 4.00 ~.75 4.50 ~.00 ~hus, satisfactor~ durable press appearance as well as scorch resistance is retained by the new reacta~t.
Table IV
.~9~
. (25% reactant) For~aldehyde, ppm of fabric (Avg. of two obser~a-tions) Polyester/Cotton 1~34 Cotton ~ twill _ .
Bath A
(Process of the 396 502 30Invention) Bath B 8Ul 1,000 ~ rom the results above, it is evident that there is a great improvement when the process of the in~entio~ is ~L~59~8 used to prepare the reactant in that there is a substantial decrease in release of formaldeh~de with the new product but at the same time the durable press and ~ellowing to scorch properties are reta1ned.

Claims

The embodiments of the invention in which an exclusive or priv-ilege is claimed are defined as follows:

1. A process for preparing an aqueous solution of a water-soluble urea-formaldehyde-glyoxal condensation product characterized by reacting in an aqueous medium about 1.0 mole of urea, about 1.0 mole of glyoxal and less than 2.0 moles of formaldehyde at a pH maintained between 6.2 and 6.7 and at a temperature of 40° to 90°C. until the formation of 1,3-dimethy-lol-4,5-dihydroxy-2-imidazolidinone is essentially completed;
adding an acidic material to the reaction solution to adjust the pH between 2.0 and 3.0; maintaining the pH between 2.0 and 3.0 and at a temperature between 40°C. and 90°C. for a period of at least 0.5 to 3.0 hours and adding a base to the solution to adjust the final pH of the solution to between 5.0 and 7. n .

2. A process according to Claim 1 wherein the mole ratios of formaldehyde employed relative to one mole of urea and one mole of glyoxal are between 1.7 and 1.9, the acidic material is an organic carboxylic acid, the pH of the reaction solution is adjusted with the acid to a pH between 2.4 and 3.0 and maintained at that pH range at a temperature between 55°C.
and 65°C. for a period of at least 1.5 to 3 hours.

3. A process according to Claim 2 wherein the car-boxylic acid is a citric acid.

4. A process according to Claim 3 wherein the mole ratios of formaldehyde employed relative to one mole of urea and one mole of glyoxal is about 1.8, the pH is adjusted to be-tween 6.2 and 6.6 at a temperature maintained between 50°C. and 60°C. for a period of 3-3/4 hours, citric acid is added to the reaction solution to lower the pH to between 2.2 and 2.8, the pH is maintained between 2.2 and 2.8 and the temperature between 55°C. and 65°C. for a period of 3 hours, and sodium hydroxide is added to the solution to adjust the pH between 6.2 and 6.6.

5. An aqueous solution of a urea-formaldehyde-glyoxal condensation product prepared according to the process of claim 1 and characterized as a colourless composition containing 1,3-dimethylol-4,5-dihydroxy-2-imidazolidi-none having between 1.6 and 1.9 moles of combined formaldehyde per mole of combined urea, plus water and about 5% of dissolved salts with less than 0.5% free formaldehyde based on the weight of product, and a pH between 6.0 and 7Ø

6. A process for producing a curable low formaldehyde releasing finish on cellulosic textile materials characterized by applying the aqueous solu-tion of claim 5, an accelerator and a surface active agent to a cellulosic textile; drying the treated textile, and pressing the dried textile at ele-vated temperatures.

7. A process according to claim 6 wherein the cellulosic textile is treated with a single aqueous solution of the water-soluble urea-formaldehyde-glyoxal condensation product and the accelerator is zinc nitrate.

8. A process according to claim 7 wherein the surface active agent is a nonionic material.

9. A process according to claim 8 wherein the amount of the water-soluble urea-formaldehyde-glyoxal condensation product applied to the cellu-losic textile are in the range of 1% and 15% based on the weight of the fabric, the amount of zinc nitrate is between 5.5% and 16.5% based on the weight of the condensation product, the drying temperature is between 175°F and 250°F.
and the pressing and curing temperature is between 300°F and 420°F.

10. A process according to claim 9 wherein the amount of water-soluble urea-formaldehyde-glyoxal condensation product and surface active agent is in the range of from 3.0% and 8.0% and between 0.075% and 1% respectively, based on the weight of the fabric, the amount of zinc nitrate employed is between 9.5% and 12.5% based on the weight of the condensation product, the drying temperature is between 200°F and 225°F., and the curing temperature is be-tween 320°F. and 380°F.