US3723377A - Process of reducing formaldehyde odor of aqueous mixtures containing methylolated carbamates - Google Patents

Abstract

PROCESS FOR REDUCING FORMALDEHYDE ODOR OF AQUEOUS MIXTURES CONTAINING METHYLOLATED CARBAMATES COMPRISING THE STEPS OF MIXING SUCH AQUEOUS MIXTURES WITH 4,5-DIHYDROXY-2-IMIDAZOLIDONE AND/OR ITS METHYLOLATED AND/ OR ALKYLATED DERIVATIVES. THE PROCESS RESULTS IN AQUEOUS MIXTURE CONTAINING METHYLOLATED CARBAMATES AND METHYLOLATED 4,5-DIHYDROXY-2-IMIDAZOLIDINONE, AS SUCH OR IN ALKYLATED FORM, HAVING A FREE FORMALDEHYDE CONTENT OF NOT MORE THAN ABOUT 1.0 WEIGHT PERCENT.

Description

United States Patent O 3,723,377 PROCESS OF REDUCKNG FORMALDEHYDE ODOR OF AQUEOUS MIXTURES CONTAIN- IN G METHYLOLATED CARBAMATES Myrtle Joanuespangler, Danville, Va., assignor to Dan River Inc., Danville, Va. No Drawing. Filed Dec. 18, 1968, Ser. No. 784,935 Int. Cl. D06rn 15/58, 15/54; C08g 32/28 US. Cl. 260-294 R 9 Claims ABSTRACT OF THE DISCLOSURE Process for reducing formaldehyde odor of aqueous mixtures containing methylolated carbamates comprising the steps of mixing such aqueous mixtures with 4,5-dihydroxy-2-imidazolidinone and/or its methylolated and/ or alkylated derivatives. The process results in aqueous mixtures containing methylolated carbamates and methylolated 4,5-dihydroxy-2-imidazolidinone, as such or in alkylated form, having a free formaldehyde content of not more than about 1.0 weight percent.

BACKGROUND OF THE INVENTION (a) Field of the invention The present invention relates to novel processes for reducing formaldehyde odors of aqueous mixtures containing methylolated carbamates to render such mixtures more suitable in uses such as the treatment of textiles for the purpose of imparting wrinkle resistance, crease and shape retention, stifiness and/ or other special effects.

(b) Description of the prior art In the preparation of aqueous mixtures of methylolated carbamates, the carbamate, e.g., an alkyl carbamate, is conventionally heated in an aqueous medium with formaldehyde to form the nitrogen-bonded methylol groups. The greater degree of methylolation, the greater the efiiciency of the methylolated carbamate in imparting the desired properties to the subsequently treated fabric. In order to achieve as full a methylolation as possible a large molar excess of formaldehyde is usually employed. As a result, free formaldehyde in amounts of weight percent or higher remains in the aqueous mixture.

Methylolated carbamates could be highly valuable agents for the treatment of textiles except for the uncomfortable, obnoxious, and unwholesome odors given off during its application to the textile. Fabrics treated with methylolated carbamates as compared to conventionally used textile resins of the same type are Whiter, i.e., undergo less yellowing, and are less sensitive to weakening during acid washes, such as those employed by commercial laundries. However, the odor problem has severely limited the use of methylolated carbamates on fabrics and prevented the full obtainment of the advantages of such materials.

SUMMARY OF THE INVENTION The present invention provides methods for substantially eliminating the odor problem associated with aqueous mixtures containing methylolated carbamates and permits the utilization of such mixtures to their fullest advantage. The methods of this invention provide for the reduction of formaldehyde odor of aqueous mixtures containing methylolated carbamates by heating such mixtures in the presence of 4,5-dihydroxy-2-imidazolidinone or its methylolated and/or alkylated derivatives.

The present invention also provides novel aqueous mixtures of methylolated carbamates and methylolated 4,5- dihydroxy-2-imidazolidinones, as such or in alkylated Patented Mar. 27, 1973 form, containing not more than about 1.0 weight percent free formaldehyde.

The invention is applicable to all types of methylolated carbamates employable in the treatment of fabrics. Such methylolated carbamates include methylolated derivatives of: alkyl carbamates, such as, methyl, ethyl, propyl, isopropyl, butyl and isobutyl carbamates; hydroxyalkyl carbamates, such as, hydroxyethyl and hydroxypropyl carbamates; alkoxyalkyl carbamates, such as, ethoxyethyl, methoxyethyl, ethoxyisopropyl, butoxyhexyl, and stearoxyethyl carbamates; polyoxyalkylene carbamates, such as,

and alkoxypolyoxyalkylene carbamates, such as,

Alkyl-O(GxHzxO) CNH wherein Alkyl designates an alkyl group preferably having 1 to 6 carbon atoms, x is an integer of 2 to 4 and n is an integer of 2 or more, preferably 2 to 100.

Stated as a formula the methylolated carbamates employed include methylolated derivatives of carbamates of the formula:

ROCNH2 wherein R is a monovalent hydrocarbon radical such as alkyl, preferably having 1 to 6 carbon atoms, cycloalkyl such as cyclohexyl, aryl Such as phenyl, aralkyl such as benzyl or alkaryl such as cresyl or tolyl; or a substituted monovalent hydrocarbon group substituted, for example, with the hydroxy group, alkoxy groups, preferably having 1 to 6 carbon atoms, aryloxy groups such as phenoxy,

cycloalkyloxy groups such as cyclohexyloxy, aralkoxy groups such as benzyloxy, or alkaryloxy groups such as tolyloxy; or groups of the formula:

wherein R is a monovalent hydrocarbon group or a substituted monovalent hydrocarbon group as defined "above and x and n are integers as defined above. The methylolated derivatives include those having one N- methylol group and those having two N-methylol groups per molecule as well as mixtures thereof.

These carbamates are well known in the art and are described in such patents as US. Pats. 3,402,989 and 3,391,181; British Pat. 309,108; French Pat. 1,030,430; and articles by Arceneaux et al. appearing on pages 37 through 41 of the American Dyestuif Reporter dated Oct. 30, 1961, and on pages 45 through 46 of the American Dyestuff Report dated Oct. 15, 1962.

Methylolation procedures, also, are well known and can be c-aried out with aqueous formaldehyde in aqueous solutions or with paraformaldehyde under anhydrous conditions. The methylolation is usually carried out to the fullest extent possible so as to result in a more eflicient product. To accomplish this large molar excesses of formaldehyde are used.

4,5 dihydroxy-Z-imidazolidinone, hereinafter called DHEU, and its methylolated derivatives, e.g., 1,3-dimethylol-4,5-dihydroxy 2 imidazolidinone, hereinafter called DMDHEU, are described in US. Pats. Nos. 2,731,472, 2,764,573 and 2,731,364. The precursors of this composition are urea and glyoxal and these can be used as such in this invention. It is also possible to employ alkylated derivatives of this composition such as are described in US. Pats. Nos. 2,764,573, 3,049,446 and 3,029,164; German Pats. Nos. 1,171,437 and 1,171,438

and copending applications, Ser. Nos. 584,957 and 584,958 filed Oct.'7, 1966, now both abandoned. It is also possible to use the procursors of the alkylated derivatives, namely a mixture of urea, glyoxal and an alkanol or a mixture of 4,5-dihydroxy-2-imidazolidinone and an alkanol. When precursors are employed the stoichiometric amounts can be used or reasonable excesses of one of the precursors can be used or, where three precursors are used, excesses of one or two of the precursors can be employed.

The amount of DHEU, or methylolated or alkylated DHEU, added depends largely upon the amount of free formaldehyde present in the methylolated carbamate mixture. It has been found that one mol of DHEU and/or alkylated derivative, added or capable of being formed for each 2 mols of free formaldehyde, i.e., 0.5 mol of DHEU per mol of free formaldehyde, reduces the free formaldehyde content down to 0.4 weight percent or less and substantially eliminates the formaldehyde odor. Lesser amounts, for example, down to 0.5 mol per 2 mols of free formaldehyde, reduce the free formaldehyde, i.e., 0.25 mol of DHEU per mole of free formaldehyde, to a lesser extent and can be used to advantage, especially in those treatments where small amounts of formaldehyde odor an be tolerated. More than 1 mol per 2 mols of free formaldehyde can be used without deleterious effects. If desired, partly methylolated DHE'U or its derivatives can be used or additional formaldehyde can be added to methylolate any amounts of DHEU, or its derivatives, present over and above the level of 1 mol per 2 mols of free formaldehyde.

There are at least two methods available for measuring free formaldehyde in methylolated carbamate mixtures. The DeJong method is described in Rec. Trav. Chim., 71, 643-890, 1952, and involves an iodometric titration.

The direct titration method of measuring free formaldehyde involves the measurement of the amount of sodium hydroxide released when sodium sulfite is added to and reacts with free formaldehyde of the methylolated carbamate solution:

CH O+Na SO +H O NaOH+CH NaSO OH In this procedure, 15 grams of the methylolated carbamate solution are diluted to 150 grams with distilled water to form a test sample. Fifty grams of the sample are mixed with ice and pH is adjusted to 9.3 with aqueous sodium hydroxide. Fifty ml. of an aqueous sodium sulfite solution (120 g./liter) having a pH of 9.3 is cooled and added to the chilled sample. The pH of the resulting solution increases because of the liberation of sodium hydroxide by reaction of formaldehyde with sodium sulfite. The solution then is titrated back to pH 9.3 with 0.5 N HCl aqueous solution. The percent free formaldehyde is calculated from the amount of HCl solution needed to adjust pH to 9.3.

The mechanism producing the reduction or substantial elimination of formaldehyde odor cannot be easily explained. A phenomenon has been observed in the unexpected substantial decrease in free formaldehyde when free formaldehyde in aqueous mixtures of fully methylolated DHEU, i.e., DMDHEU, and added Formalin were determined by the direct titration method. It was found that aqueous mixtures which should theoretically contain various amounts of free formaldehyde up to about 7.1 weight percent because of the Formalin added, actually contained far less free formaldehyde as actually determined by direct titration. The 7.1 weight percent level, in the mixtures tested, corresponds to a mol ratio of about 2 mols formaldehyde added via the Formalin per mol of DMDHEU. Above the approximate 7.1 weight percent level the expected amounts of free formaldehyde were observed. At first, a complexing theory Was propounded but was later discarded. After considerable effort, the phenomenon still has not been satisfactorily explained.

The temperature of forming the aqueous mixtures of methylolated carbamate and DHEU or its methylolated or methylated derivative is at least F. and preferferably in the range of about 100 F. to about 140 F. and the initial pH is preferably adjusted to about 4.0 to about 9.5.

Another significant advantage in the process of the present invention is the surprising reduction in volatility of the methylolated carbamate which is especially useful in the application and handling of the more volatile methylolated carbamates, such as methylolated methyl carbamates.

The compositions produced by the process of this invention are aqueous mixtures containing about 25 to about 95 mol percent of a methylolated carbamate and about 5 to about 75 mol percent of methylolated 4,5- dihydroxy-2-imidazolidinone and not more than about 1.0 weight percent free formaldehyde. Preferably, the resulting compositions contain 55 to 95 mol percent methylolated carbamate and 5 to 45 mol percent methylolated 4,5-dihydroxy-Z-imidazolidinone. These novel compositions are characterized by no objectionable formaldehyde odor.

As used herein the terms methylolated carbamate and methylolated 4,5-dihydroxy-2-imidazolidinone" cover N-monomethylolated and N,N-dimethylolated derivatives as well as mixtures thereof.

Application of the compositions produced according to processes of this invention to fabrics is accomplished by any of the many well known methods. Well known curing catalysts and other additives such as softeners can be incorporated into the compositions before application by the fabric. The compositions are very useful for imparting wrinkle resistance and/ or crease retention to cellulosic fabrics such as cotton and blends of cotton with synthetic fibers, especially polyester fibers. After application to the fabric, the composition can be fully cured, partly cured or substantially uncured. When fully cured, wrinkle and crease resistance are imparted. When partly cured or substantially uncured, the fabric can be shaped and fabricated into an article such as a garment and then post-cured to impart wrinkle resistance to some areas and shape retention, such as durable creases and pleats, to other areas.

DESCRIPTION OF SPECIFIC EMBODIMENTS The following examples are presented wherein, unless otherwise specified, parts and percentages are on a weight basis. Free formaldehyde contents were measured by the direct titration method.

EXAMPLE 1 An aqueous mixture containing 5000 parts of methyl carbamate and 9200 parts of a 37% aqueous solution of formaldehyde was prepared and the pH was adjusted to about 10.3 to 10.6 with 26 parts of 50% aqueous sodium hydroxide. The mixture was heated at about to F. for about one hour to result in an aqueous mixture of methylolated methyl carbamate containing about 3.2 weight percent or about 15.2 mols of formaldehyde as measured by the direct titration method. The combined formaldehyde was calculated to be about 98.3 mols and, based on such calculations, the solution contained about 31.6 mols of the dimethylolated derivative and about 35.1 mols of the monomethylolated derivative.

At the end of the above mentioned period of one hour at 130 to 135 F., 7670 parts of a 43% solids aqueous solution of 1,3-dimethylol-4,5-dihydroxy-2-imidazolidinone was added to the above mentioned aqueous mixture of methylolated methyl carbamate. The resulting mixture was cooled to 100 F. and filtered.

The resulting composition was computed to have about 78.3 mol percent of methylolated methyl carbamate including 21.7 mol percent of methylolated 4,5-dihydroxy- Z-imidazolidinone. It contained about 0.7% free formaldehyde as determined by the direct titration method and about 52% solids by vacuum drying. When applied to a 50:50 cotton-polyester fabric no objectionable odor ensued. The composition was partially cured on the fabric and a permanent press garment was made from the partially cured fabric. In addition to reduced odor, the fabric treated with the composition showed less discoloration on curing, lower chlorine retention damage, better soil release properties and less yellowing on extended chlorine bleaching, than fabrics treated with each of the resin components alone.

EXAMPLE 2 An aqueous mixture was prepared from 150 grams methyl carbamate crystals (2 mols) and 410 grams of a 37% aqueous formaldehyde solution (5 mols of formaldehyde). The pH of the resulting mixture was about 4 at C. The pH was raised to about 9.8 by adding 0.6 gram of 50% aqueous sodium hydroxide. The temperature of the resulting aqueous mixture was raised to 60 C. over a period of one hour and held this temperature for an additional hour. Then the mixture was cooled to 30 C. and was found to have a pH of about 9.3 and a free formaldehyde content of about 8.58% (48 grams, 1.6 mols of formaldehyde) as determined by direct titration. The combined formaldehyde was calculated to be about 3.4 mols and, based on such calculations, the mixture contained about 1.4 mols of dimethylol methyl carbamate and about 0.6 mol of monomethylol methyl carbamate.

About 180 grams (1.52 mos) of 4,5-dihydroxy-2- imidazolidinone crystals were added to the mixture, and the mixture was heated to about 40 C. Its temperature then increased to 57 C. exothermically and the mixture was then held at this temperature for one hour. Thereafter, it was cooled to approximately room temperature and was found to have a pH of 6.1 and a free formaldehyde content of about 0.42% by the direct titration method. The final composition, based on calculations, contained about 1.4 mols N,N-dimethylol methyl carbamate, about 0.6 mol N-monomethylol methyl carbamate, about 1.5 mols 1,3-dimethylol-4,5-dihydroxy2- imidazolidinone and about 0.104 mol free formaldehyde.

EXAMPLE 3 The same aqueous mixture of methyl carbamate and formaldehyde was prepared as described in Example 2, except that 0.7 gram of 50% aqueous sodium hydroxide was added to raise the pH to about 10. The resulting mixture was heated for 35 minutes to 60 0., held at this temperature for an additional hour and then cooled to 30 C. The resulting mixture was found to have a pH of 9.9 and 10.56% (59.2 grams, 1.98 mols) of free formaldehyde as determined by the direct titration method. The combined formaldehyde was calculated to be about 3.02 mols and, based on such calculations, the mixture contained about 1.02 mols dimethylol methyl carbamate and about 0.98 mol of monomethylol methyl carbamate. About 180 grams (1.52 mols) of 4,5-dihydroxy-2- imidazolidinone crystals were added to the mixture and the mixture was heated to 51 C. over a period of 45 minutes. Thereafter, the mixture was held at a temperature of 43 C. for an additional hour. The resulting mixture was cooled to about room temperature and was found to have a pH of 7.1 and a free formaldehyde content of about 0.12% as determined by the direct titration method. The final composition, based on calculations, contained about 1.02 mols N,N-dimethylol methyl carbamate, 0.98 mol N-monomethylolmethyl carbamate, about 0.9 mol 1,3-dimethylol-4,S-dihydroxy-Z-imidazolidinone and about 0.03 mol free formaldehyde.

EXAMPLE 4 As an illustration of the previously mentioned phenomenon, several aqueous solutions were prepared con- TABLE I.WEIGHT PERCENT FREE FORMALDEHYDE Theory Found Solution number:

Another series of test were performed in a similar manner using different amounts of formaldehyde set forth in Table II below under the heading Theory and using about 33.5 weight percent of the methylated N,N- dimethylol-4,5-dihydroxy-2-imidazolidinone prepared in accordance with composition A of Example 2 of copending application Ser. No. 584,957, filed Oct. 7, 1966, in place of the DMDHEU used in solutions 1 to 13 above. The free formaldehyde content of each solution as actu ally determined by the direct titration method was measured and the values obtained are listed in Table II below under the heading Found.

TABLE II.WEIGHT PERCENT FREE FORMALDEHYDE In each case where free formaldehyde was added, far less free formaldehyde was found than the amount added, up to approximately 7%.

EXAMPLE 5 An aqueous mixture (about 762 wt. pts.) containing 3 moles of methyl carbamate and 6.75 moles of formaldehyde was prepared and pH was adjusted to about 10.5. The mixture was reacted at about 55 C. for about four minutes to result in an aqueous mixture of N,N-dimethylol methyl containing 7 weight percent or about 1.8 mols of formaldehyde as measured by the direct titration method. The combined formaldehyde was calculated to be about 4.95 mols and, based on such calculations, the solution contained about 1.95 mols of the dimethylolated derivative and about 1.05 mols of the monomethylolated derivative.

One mol of glyoxal (40 wt. percent aqueous solution) and one mol of urea were then added and the pH was adjusted to 9.0. The mixture was held at 50 C. for three hours and allowed to age overnight. At the end of this time the pH had dropped to 6.3 and the amount of free formaldehyde had dropped to about 0.4 weight percent or about 0.13 mol.

The resulting composition was computed to have 75 mol percent of methylolated methyl carbamate including 1.95 mols of N,N-dimethylol methyl carbamate, and 1.05 mols of N-methylol methyl carbamate, and 25 mol percent of methylolated 4,5-dihydroxy-Z-imidazolidinone including 0.67 mol of N,N' dimethylol-4,5-dihydroxy-2- imidazolidinone and 0.33 mol of N-methylol-4,5-dihydroxy-2-imidazolidinone, When applied to a 50:50 cotton-polyester fabric no objectionable odor ensued. The composition was partially cured on the fabric and a permanent press garment was made from the partially cured fabric.

EXAMPLE 6 An aqueous solution was prepared containing 55 weight parts of Formalin (37% aqueous formaldehyde), 22.5 weight parts methyl carbamate and 1.4 weight parts of 50% aqueous sodium hydroxide. The pH of the resulting solution reached about 104:0.1. The solution was maintained at 55 C. for forty-five minutes to methylolate the carbamate after which time it contained 9.5 weight percent free formaldehyde.

Thereafter, 12.0 weight parts of a 40% aqueous glyoxal solution, 5.0 weight parts of urea, and 1.2 weight parts of aqueous sodium carbamate were added. The pH was adjusted to 9.3. The resulting solution was maintained at 55 C. for 2% hours and the pH dropped to a point in the range of 7.3 to 7.6 during this period. The free formaldehyde content was measured and found to be 0.5 to 0.6 weight percent.

Twenty-five weight parts of water were added to the solution to reduce the solids content down to 44 percent. The pH of the diluted solution was in the range of 7.0 ot 7.5 and it contained 0.4 to 0.5 weight percent free formaldehyde.

The resulting solution was computed on the basis of full methylolation of the carbamate to have about 78.2 mol percent of methylolated methyl carbamate, about 21.8 mol percent of methylolated 4,5-dihydroxy-2-imidazolidinone. When applied to a 50:50 cotton-polyester fabric no objectionable odor ensued. The composition was partially cured on the fabric and a permanent press garment was made from the partially cured fabric.

What is claimed is:

1. Method of reducing odor due to free formaldehyde in an aqueous mixture containing methylolated carbamate obtained by reacting in an aqueous medium formaldehyde with a carbamate selected from the group consisting of a carbamate of the formula:

wherein R is a member selected from the group consisting of alkyl having 1 to 6 carbon atoms, cyclohexyl, hydroxyalkyl having 1 to 6 carbon atoms and alkoxyalkyl wherein each of the alkoxy and allyl contains 1 to 6 carbon atoms, and a carbamate of the formula:

wherein R is a member selected from the group consisting of hydrogen and alkyl having 1 to 6 carbon atoms, x is an integer of 2 to 4 and n is an integer of 2 to 100, said method comprising mixing said aqueous mixture with at least 0.5 mol of 1,3-dimethylol-4,S-dihydroxy-Z-imidazolidinone and methylated derivatives thereof per 2 mols of free formaldehyde in said aqueous mixture, and heating the resultant mixture at an initial pH of from 9.0 to 9.9 and a temperature of at least F.

2. Method as claimed in claim 1 wherein said imidazolidinone is present in an amount up to 1 mol per 2 mols of free formaldehyde in said aqueous mixture.

3. Method as claimed in claim 1 wherein said resultant mixture is heated at a temperature of about 100 F. to about F.

4. Method as claimed in claim 1 wherein methylolated carbamate is methylolated alkyl carbamate.

5. Method as claimed in claim 4 wherein said methylolated carbamate is methylolated methyl carbamate.

6. Method as claimed in claim 1 wherein said methylolated carbamate is methylolated alkoxyalkyl carbamate.

7. Method as claimed in claim 6 wherein said methylolated carbamate is methylolated ethoxyethyl carbamate.

8. Method as claimed in claim 1 wherein said imidazolidinone is 1,3 dimethylol-4,5-dihydroxy-2-imidazolidinone.

9. Method as claimed in claim 1 wherein said imidazolidinone is methylated 1,3 dimethylol-4,5-dihydroxy 2- imidazolidinone.

References Cited UNITED STATES PATENTS 3,052,570 9/1962 Polansky et a1 260-84 21 3,219,632 11/1965 Frick et al. 260-72 b 3,369,858 2/1968 Lourigan et al. 8-116.3 3,391,181 7/1968 Scheuerl 8-116.3 3,402,989 9/1968 Canter et al. 8-116.3 3,416,880 12/1968 Kullman et al. 8-116.3 3,425,208 2/1969 Shippee et al 8116.3 3,454,423 7/1969 Cohen, et al. 117-1394 3,497,471 2/1970 Cohen et al. 260-29.4 3,590,100 6/1971 Weiland 8-116.3

OTHER REFERENCES Reid et al.: American Dyestuif Reporter, vol. 59, No. 6, pp. 26-28, 32 and 34 (1970).

GEORGE F. LESMES, Primary Examiner J. CANNON, Assistant Examiner US. Cl. X.R.

2-243; 8-115.7, 116.3, DIG 14; 38-144; 117-139.4, 138.8 F, 161 LN; 260-72 B, 849