US 3211805 A
Description (OCR text may contain errors)
United States Patent 3,211,805 WATER-SOLUBLE TEXTILE RESIN FINISH William F. Herbes, Bridgewater Township, Somerset County, and Raymond Polansky, Middlesex, N.J., as-
siguors to American Cyanamid Company, New York,
N .Y., a corporation of Maine N0 Drawing. Filed May 17, 1961, Ser. No. 110,622
5 Claims. (Cl. 260'849) This application is a continuation-in-part of our copending application Serial No. 732,815, filed May 5, 1958, and now abandoned.
The present invention relates to a Water-soluble textile resin finish, the process for preparing the same and to the process for finishing textile materials therewith. More particularly, the present invention relates to a novel method for preparing water-soluble melamine-formaldehyde-ethylene urea-formaldehyde resinous mixtures, the mixtures themselves, and the process for treating textiles therewith.
Alkylated methylol melamine resins, and more particularly water-soluble methylated methylol melamine resins, have been prepared heretofore. Many of the prior art procedures, such as those described in US. Patent No. 2,529,856, have disclosed the preparation of methylated methylol melamines in more or less specific terms, and have described methods for the preparation of such products having varying degrees of substitution ranging from monomethyl monomethylol melamine to hexamethyl hexamethylol melamine.
Frequently, prior art references refer to the reaction products so prepared as being highly stable and infinitely soluble in water. In practice, it has been found that by adhering to the conditions described in such disclosures, many infinitely water-soluble melamine resins can be so prepared, as for example, trimethyl trimethylol melamine, tetramethyl pentamethylol melamine and the like. However, it has been our experience that when these teachings were applied to the preparation of a substantially fully alkylated, substantially fully methylolated melamine, the resulting product did not possess the necessary degree of water solubility and stability for a good textile resin.
For many of the uses of such reaction products as, for example, in the field of surface coatings, laminating resins and the like, the qualities of water solubility and stability are not important. This is due to the fact that in most instances the melamine resins employed in the preparation of such compositions are cut or employed in organic solvent mediums, as for example, xylene, benzene and the like.
The reasons for the poor water solubility and stability characteristics of these substantially fully alkylated, substantially fully methylolated melamine resins of the prior art have been speculated upon a number of occasions. A strong body of opinion supports the theory that these deficiencies are developed in the product when it is attempted to obtain full alkylation because of the conditions employed during alkylation.
Melamine-formaldehyde resins having varying degrees of substitution, both as methylolated products and as alkylated methylol melamine resinous materials have been widely disclosed and widely employed for purposes of finishing textile materials. The use of such resins on cellulosic textile fabric have a number of important advantages. Thus, for example, they impart excellent shrinkage control and wrinkle resistance to textile materials and particularly cellulosic textile materials and have excellent durability. Still further, such textile materials treated with melamine-formaldehyde textile finishing resins do not suffer from marked deficiencies in tensile 3,211,805 Patented Get. 12, 1965 strength when scorched, subsequent to chlorine bleaching. A disadvantage of the melamine-formaldehyde condensate textile finishing resins is, however, that when employed on white goods which are repeatedly subjected to chlorine bleaching, that after a substantial number of washes, the textile fabric begins to yell-ow as a result of chlorine retention.
In order to avoid the disadvantages of yellowing following chlorine bleaching, which resulted when methylated methylol melamine resins were used, recourse was had to the use of ethylene urea type resins. This product had the advantage that it did not discolor white cellulosic fabric treated therewith after bleaching with chlorine and further that it could be used at high concentrations to obtain excellent wrinkle resistance without imparting stiffness, particularly on rayon fabric. The ethylene urea type resin, however, had the disadvantage that it gave a substantially greater loss in tensile strength than melamine resins when a fabric treated therewith was subjected to scorching after chlorine bleaching.
Several attempts have been made heretofore in the prior art to produce formulations of both the melamineformaldehyde condensate type resin and the ethylene urea-formaldehyde type resin to provide compositions which, when applied to cellulosic textile fabrics, minimized the deficiencies of these individual resinous materials. As witness to prior art efforts in this area, US. Patents Nos. 2,690,404 and 2,804,402 may be noted. In each of these references, mixtures or blends of polymethylol melamines and dimethylol ethylene urea are prepared with the components being present in critical proportions.
These mixtures as described in the above referred to US. patents are not without limitation. Thus, for example, even within the optimum conditions defined by these references, fabrics treated therewith are subject to yellowing due to chlorine retention upon repeated and extended washing due to the melamine component and the tensile strength likewise suffers when finished fabric so treated is scorched after repeated and extended washing in the presence of chlorine bleach due to the presence of the ethylene urea-formaldehyde condensate component of the resinous mixture.
The effect of this continuing to yellow after repeated and extended laundering in the presence of chlorine is in part the result of the nature of the melamine-formaldehyde component used in these compositions or condensates. Thus, for example, the references illustrate such known methylated methylol melamine condensates as the trimethyl trimethylol melamine and the pentamethyl pentamethylol melamine. While the yellowing may be diminished by increasing the ethylene urea content of the formulation, the presence of increased amounts of ethylene urea results in an undesirable increase in tensile strength loss of the fabric, when the latter is scorched following chlorine bleaching.
Accordingly, it is an object of the present invention to provide a process 'for preparing a substantially fully etherified, substantially fully methylolated melamine-ethylene urea-formaldehyde resinous composition characterized by infinite solubility in water and excellent stability.
It is a further object of the present invention to provide such a composition which, when applied to cellulose containing textile materials results in a material which is substantially free from discoloration due to chlorine retention, even though the melamine component is present in a substantial amount, and which is characterized by good tensile strength when scorched after chlorine bleaching, even though the ethylene urea component is present in a substantial amount.
Another object of the present invention is to provide a process for the finishing of textile materials, and in particular cellulose-containing textile materials, with such a resinous composition whereby good shrinkage control and wrinkle resistance are obtained with minimum deleterious effects of discoloration and loss of tensile strength of the treated fabric clue to chlorine retention.
A still further object of the present invention is to provide a textile fabric containing cellulosic materials finished with the novel resins of this invention.
These and other objects and advantages of the present invention will become more apparent from the detailed description set forth hereinbelow.
In accordance with one aspect of the present invention, a process is provided for preparing a water-soluble, substantially fully etherified, substantially fully methylolated melamine, ethylene urea-formaldehyde textile finishing composition. This process comprises preparing a substantially fully methylolated melamine by reacting relative mole ratios of -1 mole of melamine and an excess of formaldehyde represented by an amount between about 8 and 20 moles of formaldehyde as paraformaldehyde at a temperature between 30 and 80 C. at a pH between 7 and 11 in the presence of at least 6 moles of methanol until the clear solution is formed and the reaction is complete, as determined by the amount of free formaldehyde present. Thereafter, sufficient additional methanol is added to the reaction mixture to make a total of at least moles of methanol therein, after which the pH of said mixture is adjusted to a value of below 4 and said mixture is stirred while maintaining a temperature between 15 and 60 C. until a complete solution is obtained.
Thereafter, the pH of the reaction mixture is adjusted to a value between about 8 and 10 and the mixture vacuum concentrated to a desired solids content, said vacuum concentration being for purposes of removing excess formaldehyde and methanol. Ethylene urea in an amount up to about 1.2 moles is added and reacted with the excess formaldehyde at a temperature of between and 80 C. until reaction is complete.
In a copending application, Serial No. 732,814, filed May 5, 1958, an improved substantially fully etherified, substantially fully methylolated melamine resin is described. Such materials may be prepared by at least two general methods, each of which has certain shortcomings. Thus, a two-kettle process may be employed in which a substantially fully methylolated melamine is isolated. Such a process results in the eliminating of substantial amounts of excess formaldehyde and etherification is carried out in 'a second operation, using the isolated intermediate. In 'a second procedure, a one-kettle process, a substantially fully methylolated melamine is not isolated before the .etherification step, and consequently the product contains considerable amounts of free formaldehyde. A twokettle process has the advantage of giving a product containing essentially no free formaldehyde, but such a process is more expensive than that of the second. The onekettle process, although less expensive, results in a product containing undesirably large amounts of free formaldehyde. Said amount of free formaldehyde is sufficient to render the resin unattractive commercially because of obnoxious odors which are produced. In efforts to reduce the free formaldehyde to an acceptable level of, say, less than 3%, based on total composition as by vacuum concentration, the solubility in water of the resin is impaired.
The substantially fully etherified, substantially fully methylolated melamines prepared in accordance with the procedures described above in the above referred to copending application may be employed in preparing the resinous finishing compositions of this invention by mechanically blending this product with the hereinafter described amounts of ethylene urea-formaldehyde condensate, but such blending is objectionable processwise, as costs are increased or the product is unsatisfactory due to the presence of excess formaldehyde. Thus, in accordi ance with the present invention, the novel finishing compositions are preferably prepared, in general, in accordance with the one-kettle process described in the aboveidentified copending application. By employing this procedure, these shortcomings are readily overcome.
The composition of this invention may be characterized as a mixture comprising on a relative mole basis 1 mole of a substantially fully etherified, substantially fully methylolated melamine and from between about 0.6 and about 1.2 moles of an ethylene urea-formaldehyde condensate, preferably dimethylol ethylene urea. Preferably, the mole ratios on a relative basis are 1 mole of the melamine component and between 0.8 and 1.0 mole of the ethylene urea component.
The product of this invention is preferably characterized as a reaction mixture, referring to the product prepared by the addition of ethylene urea to the melamine condensate, whereby free formaldehyde present reacts with the ethylene urea to form the methylol condensate.
The resinous composition of this invention is further characterized by infinite solubility in water and excellent stability characteristics, even though the melamine component is a substantially fully etherified, substantially fully methylolated product, and is always present in the mixture in substantial amounts.
More specifically in accordance with the present invention, melamine and paraformaldehyde are reacted in relative mole ratios of from 1 to about 8 to 1 to 20 and preferably in mole ratios of 1 to 8 to 1 to 12, respectively. In these mole ratios, the paraformaldehyde is expressed as monomeric formaldehyde. These reactants are heated in a suitable reaction vessel in the presence of methanol at a pH of between 7 and 11, and preferably between 8 and 10 at a temperature of between 30 and C., and preferably between 60 and 80 C. until the reaction is complete as evidenced by free formaldehyde determination.
The amount of methanol added during the methylolation of the melamine should be at least 6 moles and preferably at least 8 moles of alcohol per mole of melamine in the reaction mixture. It is esesntial that at least 6 moles of alcohol be added in order to achieve a stirrable reaction mixture.
After methylolation is complete, the substantially fully methylolated melamine is etherified. This is accomplished by the addition of sufficient methanol to make a total of between 10 and 20 moles and preferably between 12 and 18 moles per mole of melamine. As will appear more clearly hereinafter, it is sometimes desirable during etherification to add certain monoalkyl ethers of diethylene glycol and ethylene glycol in an amount of at least 0.1
mole and preferably between about 0.25 and 1 mole per mole of melamine, though up to 2.5 moles may be employed.
Thereafter, the pH of the reaction mixture is adjusted to a value of below 4 with a suitable acid and preferably to a value below 3.5, and the mixture is stirred at a temperature of between 15 and 60 C. and preferably between 30 and 50 C., until complete solution is obtained. Usually, about one hours time is required for alkylation. Thereafter, the pH of the reaction mixture is adjusted to between 8 and 10 with an alkaline material such as caustic soda, potassium hydroxide, sodium carbonate, sodium bicarbonate and the like, and the solution is concentrated in vacuo. The remaining syrup contains free formaldehyde, the amount depending upon the quantity of paraformaldehyde used in the methylolation step, and the extent of vacuum concentration, whereby a portion of the free formaldehyde is removed from the reaction mixture.
After vacuum concentration sufiicient ethylene urea is added to the reaction mixture of the etherified, methylolated melamine to combine with a major portion of the free formaldehyde and to give the dimethylol ethylene urea. Preferably, not over 1.0 moles of ethylene urea per mole of melamine should be employed, though amounts up to about 1.2 moles of ethylene urea per mole of melamine have been employed with satisfactory results. At this stage, it may be desirable to add sufiicient water with the ethylene urea to achieve a desired solids content in the final product.
After the addition of the ethylene urea, the reaction mixture is stirred at a temperature between 30 and 80 C. and preferably at a temperature between 50 and 70 C. until the reaction between the ethylene urea and formaldehyde is completed, as determined by free formaldehyde determination. Thereafter, the pH of the reaction mixture is adjusted to a value of between 7 and 9 with any suitable alkaline material, and the solution is cooled and filtered, as for example at a temperature of between about 30 and 40 C.
It will be seen that the above-defined process is basically or essentially a one-pot process in which the methylolation stage is carried out in the presence of an alcohol, preferably methanol, while employing paraformaldehyde. By employing these components and under the above conditions, it becomes unnecessary to isolate the substantially fully methylolated melamine before the etherification step, in view of the comparatively small amount of water in the reaction medium. It should be noted that the upper limit on the amount of alcohol employed in the reaction medium during methylolation is not critical, and that if desired the total alcohol charge may be charged initially, as opposed to the double charge described above, and illustrated in more detail hereinbelow, though the latter is preferred.
As indicated herein-above, the etherification may be carried out with methanol alone or in conjunction with certain monoalkyl ethers of diethylene glycol and ethylene glycol. Although highly satisfactory products are obtained employing methanol alone, the use of relatively small amounts of one of the above-identified ethers, which have boiling points higher than that of methanol, results in a process advantage in that it facilitates the concentration of the final product substantially. Employing the ether, the alcohol is completely removed and more importantly the free formaldehyde content is reduced to a point where the recommended amount of ethylene urea will be sufficient for combining with substantially all of the remaining free formaldehyde.
Although methanol or methyl alcohol is the definitely preferred alcohol, employed in the present process, it is believed that other saturated aliphatic alcohols containing from 2 to 4 carbon atoms, such as ethanol, the propyl alcohols, the butyl alcohols or mixtures of these, may be employed with some measure of success.
The monoalkyl ethers of diethylene glycol which may be employed contain from 1 to 4 carbon atoms in the alkyl group. Thus, for example, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, secondary butyl and tertiary butyl ethers of diethylene glycol may be employed, as well as mixtures of said ethers. Of these ethers, the ethyl ether of diethylene glycol is preferred. The monoalkyl ethers of ethylene glycol employable include those wherein the alkyl group contains 1 to 3 carbon atoms or mixtures thereof as represented by methyl, ethyl, propyl, isopropyl and ethylene glycol.
Preparatory to the etherification of the substantially fully methylolated melamine, the pH of the reaction mixture is adjusted to a pH value below 4 and preferably below 3.5. This may be accomplished by employing any of a number of suitable acidic catalysts, as for example sulfuric, hydrochloric, nitric, phosphoric, oxalic and toluene sulfonic acids. Nitric acid is preferred, partic ularly when sodium hydroxide is employed as the alkaline catalyst during methylolation, for reasons that will appear more clearly hereinafter.
The amount of acid employed not only determines the pH of the reaction mixture, but also largely influences 6 the time required to achieve complete etherification. In general, longer reaction times are required when minimum amounts of acid are employed and conversely shorter reaction periods are required when maximum amounts of acid catalysts are employed.
As indicated hereinabove, the amount of acid catalyst added is an amount sufficient to adjust the pH to a value below 4 and preferably below 3.5. Defined on a mole basis, per mole of melamine, the amount of acid employed should be from between about 0.05 and 0.30 per mole of melamine and preferably from between 0.08 and 0.16 per mole of melamine.
The substantially fully etherified and substantially fully methylolated melamine is preferably vacuum concentrated in order to remove excess methanol and some of the free formaldehyde, preferably by employing known vacuum concentration techniques. Experience has shown that the final internal temperature of the melamine reaction product should be about C. employing a vacuum of from 25 to 26 inches of mercury.
The expression 25 to 26" of mercury and similar ex pressions as they are used herein, refer to commercial dial gauge readings. In principle, these readings are ob tained as follows. A hollow tube is connected from an opening in the container, the vacuum in which it is to be measured, to the upper end of a vertical glass tube, the lower end of which is in a pool of mercury. As a vacuum pump exhausts the air from the container and the glass tube, atmospheric pressure forces mercury up the said tube. The height to which the mercury rises is the measure of the vacuum in the container, which in the present instance has been read in inches.
When an ether of a suitable glycol is not employed, the vacuum concentration is more difficult, since the presence of the ether serves to make the reaction mixture more fluid at 7080 C. when most of the methanol has been removed. However, the concentration can be accomplished without using the ether and with a final internal temperature of about 80 C. Under these conditions, the concentrated product has a viscosity of 5000- 6000 centipoises at 25 C., whereas with the ethyl ether the viscosity was 800-1400 centipoises at 25 C. As previously stated, the termination of the vacuum concentration at a temperature lower than 80 C. produces a concentrate containing more free formaldehyde. The presence of increased amounts of formaldehyde in the concentrate is undesirable, since this would require increased usage of ethylene urea to reduce the formaldehyde content to an acceptable level, say less than 3%, based on the total product weight, and thus the tensile strength of the resulting finished textile material would be adversely affected.
Although it is recommended that approximately 1.0 mole of ethylene urea per mole of melamine resin be used, experimental evidence indicates that usage as high as about 1.2 moles of ethylene urea are also satisfactory. However, it is known that dimethylol ethylene urea causes a greater strength loss due to chlorine retention than the fully etherified, fully methylolated melamine. In the above referred to US. patents, namely, 2,690,404 and 2,804,402, it is essential that the resin mixture contain more moles of ethylene urea than melamine in order to minimize discoloration due to chlorine retention. Employing the substantially fully etherified, substantially fully methylolated resin of the present invention, which of itself results in substantially no discoloration due to chlorine retention when compared with other known melamineformaldehyde condensates, it will be apparent that the principal shortcoming resides in the loss of tensile strength due to chlorine retention as a result of the ethylene ureaformaldehyde component being present in the mixture.
In accordance with the present process, the substantially fully etherified, substantially fully methylolated melamine is concentrated in order to reduce excess free formaldehyde and methanol. This concentration is never such as will adversely affect the solubility of the product, nor reduce the free formaldehyde content to an extent such that the ethylene urea added cannot be fully converted to dimethylol ethylene urea. In this connection, at the time of the addition of ethylene urea, the concentrated melamine reaction product may contain as high as about 15% free formaldehyde based on the weight of the total reaction mixture, though preferably much less, but an amount sufficient to fully methylolate the ethylene urea. After the methylolation of the ethylene urea, the reaction mixture normally will contain from traces of formaldehyde to a maximum of about 2%, based on the weight of the total reaction mixture.
By the expression substantially fully methylolated melamine as it is used herein, it is meant a product which contains a minimum of 5.8 moles of combined formaldehyde per mole of melamine and preferably up to 6 combined moles of formaldehyde per mole of melamine.
By the expression substantially fully etherified as it is employed herein, it is meant that at least 5.6 of the available methylol groups on the melamine have been reacted, with methanol, and if employed, the selected monoalkyl ethers of diethylene glycol and ethylene glycol. In this connection, the etherifying groups are methyl or principally methyl, with one mole of the melamine condensate containing up to 2.5 moles of alkoxyethoxyethyl and/or alkoxyethyl groups, and preferably from between about 0.25 and about 1 mole of such groups, the remaining etherifying group being methyl.
By the expression excellent stability and similar expressions as they are employed herein, it is meant stability in aqueous solution in all concentrations for at least 12 weeks at 12 and 37 C.
By the expression infinite solubility as it and similar expressions are employed herein, it is meant that the present resin composition is readily and easily soluble and dilutable in water in all proportions and that solutions containing the resin in all proportions remain clear.
The resin composition of this invention is applied to textile materials and preferably textile materials containing at least 50% cellulose, in order to impart shrinkage control and a high degree of wrinkle resistance thereto, without discoloration due to chlorine retention from re-' peated chlorine-containing washings and minimum loss of tensile strength also due to chlorine retention.
By the term cellulosic material as that term is employed herein, it is meant fibers, yarns, filaments, formed fabric, whether woven or non-woven, felted or otherwise formed, containing at least 50% of cellulose fiber prepared from cotton, rayon, linen, flax and other cellulosic materials. These cellulosic textile materials may be employed in combination with other non-cellulosic materials, as for example, they may be blended with other natural or synthetic fibers, as for example, wool, nylon, acrylic and polyester fibers, and the like.
The resins of this invention may be applied to textile materials, preferably a formed cellulosic containing fabric, with a suitable curing catalyst. The resinous composition and catalyst may be applied by any conventional technique, such as immersion, padding, spraying and the like and followed, where necessary, by squeezing, hydroextraction or similar processes, in order to affix the desired amount of resin solids onto the fabric.
The method of application should be such that from about 1 to about 25%, and in some instances higher amounts of the resinous product of this invention, based on the weight of the fabric, are deposited thereon. Within certain limits, the amount of resin applied depends upon the particular type of fabric being treated. Thus, when treating fabric consisting of fibrous cellulosic materials, the concentration of the order of from about 1 to 25% and more, particularly from 3 to resin solids, based on the dry weight of the fabric, may be employed.
The catalyst utilized may be free acid, acid salts, alkanolamine salts and the like. The concentration of catalyst employed may range from about 0.1 to about or higher, based on the weight of the resin solids, depending upon the particular catalyst type employed. Thus, for example, from between about 0.1 and about 10% of a free acid, such as phosphoric, tartaric, oxalic or the like, may be employed, while in the case of ammonium chloride amounts of from between 0.5 and about 10% are used. In the case of amine salts, including alkanolamine salts, such as diethanolamine hydrochloride, from about 1.0 to about 10% are most useful, while with respect to salts such as magnesium chloride, amounts of between about 5 and 25% have been successfully employed. In all instances, the concentration of the catalyst is based on the weight of the resin solids employed.
Following the application of the resin and curing catalyst to the textile fabric, the material is subject to drying and curing operations to effect the properties of shrinkage control and wrinkle resistance. The drying and curing operation may be carried out in a single step or in separate steps. The temperatures at which the drying and curing operations are effective vary widely and are infiuenced to some extent by the type of catalyst employed. Normally, the range of temperature extends from about 180 F. to about 450 F. or even higher. Generally speaking, the time of the drying and/ or curing operation is inversely proportional to the temperature employed, and of course is influenced by whether or not separated or combined drying and curing steps are employed.
Generally, when drying and curing is carried out in a combined operation, a time of from about 1 minute to about 10 minutes may be employed at temperatures from about 450 to 250 F., respectively. When the fabric has been dried preliminary to curing, curing times of the order of 5 minutes to about A minute at a temperature of from between 250 and 450 B, respectively, have been successfully employed.
In order to better illustrate the present invention, the following examples are given primarily by way of illustration. No specific details or enumerations contained therein should be construed as limitations on the present invention except insofar as they appear in the appended claims. All parts and percentages contained therein are by weight unless otherwise specifically designated.
EXAMPLE 1 Into a suitable reaction vessel there were charged 189 parts (1.5 moles) of melamine, 300 parts (9.4 moles) of methanol and approximately 3 parts of 80% triethanolamine. After adding 495 parts (15 moles) of formaldehyde as 91% paraformaldehyde at C., the reaction mixture was heated to 70 C. over approximately 30 minutes and held at 70 C. for an additional two hours.
To this reaction mixture, there were added 338 parts (10.6 moles) of methanol, approximately 18 parts (0.18 mole) of concentrated sulfuric acid, and 100 parts (0.75 mole) of the monoethyl ether of diethylene glycol. These charges were made while the reaction mixture was at a temperature of 30 C.
After stirring at 30 C. for minutes, the pH was adjusted to 8.9 with a sodium hydroxide solution. The reaction mixture was filtered and the filtrate (1192 parts, representing an 81% recovery, equivalent to 1.22 moles of melamine) was concentrated in vacuo. The residue Weighed 770 parts and contained 77.5% solids. The product also contained 12.5% free formaldehyde equivalent to 96 parts or 3.2 moles.
Into a suitable reaction vessel, 259 parts of the above product, equivalent to 0.411 mole of melamine and containing 1.08 moles of free formaldehyde, and 83.6 parts of a 40% solution of ethylene urea (0.389 mole) were heated at C. for 15 minutes. After cooling at 30 C. the reaction mixture was filtered. The light colored vis- EXAMPLE 2 Into a suitable reaction vessel, there was charged 4070 parts (127 moles) of methanol, 2000 parts (15.9 moles) of melamine and 40 parts of 80% triethanolamine. At 40 C. and a pH of 9.5, there were added 5200 parts (158 moles) of formaldehyde as 91% paraformaldehyde. The reaction mixture was heated to 70 C. and held for two hours at 70 C., whereupon the pH was 8.4. After cooling to 70 C., 4070 parts (127 moles) of methanol, 1050 parts (7.9 moles) of the monoethyl ether of diethylene glycol and 195 parts (2.0 moles) of 100% sulfuric acid were added. The reaction mixture was stirred for 1 hour at 40 C. and pH equaling 3.7, and thereafter 410 parts of 10 N sodium hydroxide solution were added to produce a pH of 9.0.
The charge was concentrated in vacuo to a viscosity on a Gardner-Holdt scale of X at C. which is equivalent to 1200-1400 centipoises at 25 C. The pH was 7.7. After adding 2000 parts of a 60% ethylene urea suspension (1200 parts ethylene urea or 14 moles) and 1500 parts of water, the charge was stirred at 60-65" C. for 0.5 hour. The charge, after cooling to 40 C. was filtered.
The product contained approximately 69.4% solids, had a pH of 8.8 and a free formaldehyde content of less than 1.8%. It was infinitely dilutable with water and had excellent stability. The viscosity at 25 C. was 67 centipoises.
EXAMPLE 3 Into a suitable reaction vessel there was charged 189 parts (1.5 moles) of melamine, 384 parts (12.0 moles) of methanol and approximately 3 parts of 80% triethanolarnine. After adding 495 parts (15 moles) of formaldehyde as 91% paraforrnaldehyde at 40 C., the reaction mixture was heated to 70 C. over approximately minutes and held at 70 C. for two hours.
To this reaction mixture, at approximately 40 C., there was added 384 parts (12.0 moles) of methanol and 100 parts (0.75 mole) of the monoethyl ether of diethylene glycol. At C. there was added 12.8 parts (0.142 mole) of 70% nitric acid to produce a pH of 3.2. After stirring at C. for 1 hour, the pH was adjusted to 8.7 with sodium hydroxide solution. The reaction mixture, 1580 parts, was concentrated in a vacuum of 25-26 inches of mercury to a final internal temperature of 80 C. The residue weighed 772 parts.
772 parts of the above product, 175 parts of a 66% solution of ethylene urea, and 150 parts of water were stirred at 60 C. for 30 minutes. After cooling to 40 C. the solution was filtered. It was clear at 10 C., 12 C., 25 C., 37 C. and 50 C. after four weeks.
EXAMPLE 4 Various ratios of sulfuric acid to melamine were used in the etherification step following the general procedure set forth in Example 1.
These results are recorded in Table I hereinbelow.
Table I hereinabove illustrates that in order for the etherification to be complete and for the malamine reac- 10 tion product to be clear and infinitely dilutable, the pH of the reaction mixture during etherification should be a value of less than 4.
EXAMPLE 5 A mixture of 768 parts (24 moles) of methanol, 378 parts (3 moles) of melamine, 990 parts of formaldehyde (30 moles) as 91% paraformaldehyde and approximately 6 parts of triethanolamine were heated at 70 C. for 2 hours. The resulting mixture had a pH of 8.2. After cooling to 35 C. there was added 36 parts (0.36 mole) of concentrated sulfuric acid and 768 parts (24 moles) of methanol. The reaction mixture having a pH of 3.55 was stirred for 1 hour at 40 C. The pH was then adjusted to 9.0 to 9.5 with a solution of caustic soda. By concentrating 3025 parts to an internal temperature of C. with a vacuum of 26 inches of mercury, 1329 parts of syrup having a pH of about 8.0, a viscosity of 5680 centipoises, 10.5% free formaldehyde and 92.4% solids was obtained.
A portion (665 parts) of the above materials, equivalent to 1.5 moles of malamine was mixed with 189 parts of a 60% solution of ethylene urea (1.32 moles) and 176 parts of water. The mixture was stirred at 60 C. for 0.5 hour. The final product obtained by filtering at 40 F. contained 72.5% solids, 1.3% free formaldehyde, a pH of 9.0 and a viscosity of 50 centpoises. The solution was clear after storage at 12 C., 25 C. and 37 C. for one month. Crystals of sodium sulfate appeared at- -8 C.
EXAMPLE 6 A batch of concentrated fully etherified hexamethylol melamine resin, in which methanol and a relatively small amount, 0.5 mole per mole of melamine, of the monoethyl ether of diethylene glycol was used in the etherification step, was divided into three equal portions. Each portion was reacted with ethylene urea using the amount indicated below.
The results are indicated in Table II hereinbelow.
Table II Moles of EU per mole 1. 00 Less than 2%. 1. 12 D0. 1. 25 Do.
All were infinitely soluble in water and characterized by excellent stability.
EXAMPLE 7 In Table III hereinbelow, 7.5% of the resin solids indicated were applied to 80 x 80 cotton cloth, using 12% of magnesium chloride as an accelerator on the weight of the resin solids in the bath. The so treated fabric was then dried and cured for 1.5 minutes at 350 F.
The wrinkle recovery as reported therein was measured on a Monsanto wrinkle recovery tester, following the tentative method 66-56, described on page 139 of the 1956 Technical Manual and Yearbook of the American Association of Textile Chemists and Colorists, volume 32.
The tensile strength was measured on a Scott tensile tester according to the A.S.T.M. standards. The tear strength was measured by the standard Elmendorf test.
The yellowing index is calculated by the equation:
Yellowing index=70 1 R577 where R and R are reflectance values obtained on a recording spectrophotometer, using a magnesium carbonate block as a reference standard at the wave lengths of 455 m and 577 mg, respectively.
The strength loss due to chlorine retention was measured by the tentative test method 6952, described on page 103 of the above-identified reference.
The washings under Wrinkle Recovery were carried out at 212 F. by the procedure described on page 106 of the 1956 Technical Manual and Yearbook of the American Association of Textile Chemists and Colorists, volume 32.
The washing under Yellowing Index was done in a Laundromat washer using a 15-minute wash cycle at 140 F. in a solution containing 0.01% soap and 0.02% available chlorine at a liquor to cloth ratio of 7 to 1. Following bleaching, the fabrics were rinsed in water at 140 F. for three 5-minute cycles and then tumble dried at from 140 F. to 145 F. for 30 minutes.
The wash under Chlorine Retention was a process wash.
T able III *Pad bath prepared using 3% Deceresol NI (reaction product of nonylphenol and 9 moles of ethylene oxide) on the weight of the resin as dispcrsing agent.
A B C D E Wrinkle Recovery (degrees)- Initial 146 278 258 243 258 After 6 washes... 157 252 212 216 236 Grab Tensile Strength: Total W+F, lb 82 51 49 54 50 CHLORINE RETENTION Initial Tensile Strength:
Before chlorine 89 53 64 64 54 After chlorine. 85 45 61 65 56 Percent loss 4 15 5 O Tensile Strength After Wash:
Before chlorine 85 53 57 62 56 After chlorine. 83 49 55 62 58 Percent loss.- 2 8 4 0 0 Yellowing Index:
Initial 1. 1 0.4 1. 4 1. 2 1.6 After 25 washes..- 0.1 1. 4 7. 5 3.1 2. 9 Han std v. 51. equal v. 51. fuller fuller Table III hereinabove illustrates, among others, two important things: that the composition of the present invention imparts excellent wrinkle resistance, does not result in tensile strength loss in the fabric after chlorine bleaching (even though ethylene urea is present) and results in substantially less discoloration due to chlorine retention than do mixtures of other melamine resins and ethylene urea.
EXAMPLE 8 In Table IV, 5% resin solids from the three batches prepared according to Example 6 having different dimethylol ethylene urea content were applied to 80 X 80 cotton cloth, using 12% of magnesium chloride on the weight of resin solids in the bath, and curing for 1.5 minutes at 350 F.
The tests and washes applied to the treated fabrics were the same as those employed in Example 7 with one exception. The washes under Chlorine Retention were done by the more rigorous procedure used for washes under Wrinkle Recovery, namely, washing at 212 F. This is equivalent to a Sanforize wash. The remaining portion of the chlorine scorch test was done as described in Example 7.
1 2 Table IV 6A 6B 6C Wrinkle Recovery:
Initial (W+1) 252 257 243 After 0 washes 223 220 225 Grab tensile strength: Total W+F, 1b...- 59 61 G0 Elmendorf Tear Strength: Total W+F, lb. 1. 88 1. l. 73
CHLORINE RETENTION Initial Tensile Strength:
Before chlorine 58 58 60 After chl0rine 52 54 55 Percent; loss 10 7 8 Tensile Strength After Was Before chlorine. 57 58 58 After chlorine.-. 59 G7 55 Percent loss 0 0 5 Yellowing Index:
Ini 1.4 1.3 1.4
After 25 washes..- 2. 6 2.8 2. 6 Hand. standard equal equal Table IV illustrates the effect of varying the amount of the ethylene urea component in the reaction mixture with respect to the melamine component. It will be seen that even though the wash test employed for the chlorine retention test was severe, within the limits of this invention, the tensile strength and yellowing index values recorded are superior. It should further be noted that when the ethylene urea content exceeds the upper limit, noticeable losses in tensile strength are recorded.
It will be noted in the above illustrative examples that triethanolamine is the alkaline catalyst normally employed during methylolation of the melamine. This is because triethanolamine is a highly satisfactory and desirable alkaline catalyst in view of its stability, whereby it is able to maintain a substantially uniform alkaline pH within the alkaline range required for methylolation. While it will appear reasonably evident that other known alkaline catalyst materials may be employed, it has been found that when the alkaline catalyst employed during methylolation is an alkali metal hydroxide and particular- 1y sodium hydroxide, and that when the acidic catalyst employed during etherification is nitric acid, that the resulting reaction mixture is superior, particularly with respect to its yellowing index, as well as other properties. These particular and narrower aspects of the present invention will be illustrated hereinafter.
EXAMPLE 9 Into a suitable reaction vessel, there were charged 4070 parts (127 moles) of methanol and 37 parts of a 30% solution of sodium hydroxide. At a pH of 11.5 there was charged 52-00 parts (158 moles) of formaldehyde as 91% paraformaldehyde. The reaction mixture was heated to 46-48" C. and at pH 10.2 there was charged 2000 'parts (15.9 moles) of melamine. The reaction mixture was heated to reflux (78-80 C.) for one hour, whereupon the pH was 9.0. After cooling to about 70 C., 4070 parts (127 moles) of methanol, 1050 parts (7.9 moles) of the monoethyl ether of diethylene glycol, and parts (1.71 moles) of 71% nitric acid were added to produce a pH of about 2. The reaction mixture was stirred for one hour at 40 C. and thereafter 182 parts of 10 N sodiumhydroxide solution were added to produce a pH of 9.0.
The reaction mixture was concentrated in vacuo until a temperature reached 80 C. and the distillate amounted to 1900 parts. The pH was 7.2. After adding 2800 parts of a 60% ethylene urea suspension and 1700 parts of water, the charge was stirred at 6065 C. for 0.5 hour. The pH was adjusted to 8.2 with a 10 N solution of sodium hydroxide and the charge, after cooling to 40 C., was filtered.
The product contained approximately 69.8 solids at a pH of 8.2 and afree formaldehyde content of about 2%. It was infinitely dilutable with Water and characterized by 5 excellent stability. Its viscosity at 25 C, was 30 poises.
13 EXAMPLE 10 The same general procedure as that employed in Example 9 was followed herein, with the exception that 3000 parts of a 40% ethylene urea suspension and 700 parts of water were added during the methylolation of the ethylene urea and the charge Was stirred at 60 C. for 0.5 hour. Then 4700 parts of water were added.
The product contained approximately 51% solids.
EXAMPLE 11 In Table V hereinbelow 6% of the resin solids obtained from the batches prepared in accordance with Example 2, Example 9 and Example 10, were applied to 80 x 80 cotton percale, using 12% magnesium chloride as an ac- Celerator based on the weight of the resin solids in the bath. The treated fabric was then dried and cured for 2 minutes at 350 C.
The tests and washes applied to the treated fabrics were the same as those applied in Example 7, with the following exceptions: the 160 F. and 180 F. washes under Yellowing Index were carried out by the proce dure described as Test Method 14-53 on page 106 of the 1956 Technical Manual and Yearbook of the American Association of Textile Chemists and Colorists, volume 32, using temperatures of 160-180 F., respectively, with Tide, a synthetic detergent, employed in place of soap, with 0.02% of available chlorine in the wash liquor.
Table V hereinabove illustrates that when the alkaline catalyst employed during methylolation is specifically sodium hydroxide, and the acidic catalyst employed during alkylation is nitric acid, in the process of this invention (Examples 9 and 10), that a product resulting in an improved and superior yellowing index is provided. This superior improvement is of the order of at least 30%.
EXAMPLE 12 In Table VI below 6% of the indicated resin solids were applied to 80 x 80 cotton percale using 12% magnesium chloride on the weight of the resin solids in the bath. The treated fabric was then dried and cured for 2 minutes at 350 F. The tests and washes applied to the treated fabric were the same as those employed in Example 11.
' Table VI Dimethylol ethylene urea Hexamethyl hexamethylol melamine (Solution achieved with dispersing agent) Product of Example 10 Product of Example 2 Yellowing Index:
Initial After 25 Washes at 140 C After Washes at 160 C In addition to illustrating that the resinous reaction product prepared in accordance with the procedure of Example is superior in yellowing index after both 25 Washes at 140 C. and after 5 washes at 160 C., with respect to the resinous mixture prepared in accordance with Example 2, Table VI further illustrates that the reaction mixture prepared in accordance with Example 10 in which the alkaline catalyst is sodium hydroxide and in which the acidic catalyst is nitric acid, is superior with respect to hexamethyl hexamethylol melamine and is more closely comparable to ethylene urea with respect to yellowing index than any melamine-containing blend heretofore known.
In addition to the superior yellowing index achieved by the reaction mixture of the present invention, when the above-identified alkaline and acid catalyst are employed in the process of manufacture, this particular resinous reaction mixture is characterized by improved resistance to soiling, with respect to blends prepared in accordance with Example 2. The improved resistance to soiling of this reaction mixture is more clearly illustrated when white cellulosic fabrics finished with the resin prepared in accordance with Example 2 and the resin prepared in accordance with Example 10 are laundered in the presence of synthetic soil. In such a laundering procedure, a cellulosic fabric treated with the former is characterized by a tendency to more readily absorb the synthetic soil (soiling) than that finished with the latter. This same superiority is noted to a lesser degree under actual laundering conditions.
EXAMPLE 13 Three different melamine resins identified as follows: Resin A-a substantially fully methylated, substantially fully methylolated melamine, Resin Ba tris(methoxymethyl) dimethylol melamine, and Resin C-a tris (methoxymethyl) melamine, were employed in combination with dimethylol ethylene urea in three different mole ratios. These were: EU component to melamine component of 0.66, 1.40 and 3.00. Only the first of these ratios, namely 0.66, is within applicants claimed mole ratio range.
A total of nine applications were made employing the various blends. These applications were made on x 80 bleached cotton percale so as to apply 5% resin solids based on the dry weight of the fabric, and the applied resin was cured for 1 /2 minutes at 350 F. The catalyst was 12% of magnesium chloride based on the resin solids in the pad bath.
All applications of the above combination of resins resulted in acceptable wrinkle recovery values. However, insofar as their yellowing indices and strength loss due to chlorine retention, the composition contemplated by the present invention was dramatically superior, as will be seen in Table VII hereinbelow.
In Table VII the results reported under Yellowness Index were determined as described in Example 7 hereinabove after one wash employing oxalic acid and chlorine. In this wash the finished cloth in a 40:1 liquor to cloth ratio was washed at F. for 10 minutes in 2% of oxalic acid. It is thereafter rinsed and at the same liquor to cloth ratio is washed in .15 available chloride at F. for 20 minutes. The so washed fabric is then rinsed, dried, conditioned and tested. The strength loss due to chlorine retention was determined in accordance with the procedure referred to in Example 7 after 5 washes at 200 F.
Table VII Yellowness Index AATCC Chlorine Retention Ration After 1 Oxalic Resin (EU:MEL.) Acid-Chlorine After 5 x 200 F.
Wash Washes In. 01. Percent So. So. T.S. Loss 1. 0.66 11. 6 34 29 15 Resin A.-. 2. 1.40. 11.6 38 20 49 3. 3.00 9. 9 40 17 58 4. 0.66 16. 5 38 27 29 Resin B 5. 1.40. 16.2 39 22 44 6. 3.00- 13. 5 39 22 44 7. 0.66- 24. 0 44 10 77 Resin C- 8. 1.40 22. 4 41 11 73 9. 3.00..- 17.3 40 11 73 Table VII above clearly demonstrates that application 1 of the Resin A group is dramatically superior, both with respect to the yellowing index and strength loss due to chlorine retention. This application, application 1, employed a composition contemplated by this invention, while applications 29 employ compositions outside the scope of the instant invention.
While the products prepared in accordance with copending application Serial No. 732,814 require the presence of a monoalkyl ether of diethylene glycol or a monoalkyl ether of ethylene glycol as these terms are defined hereinabove, during the etherification step in order to obtain a suitable soluble product characterized by good stability, such modification does not appear to be necessary insofar as the present complex resinous composition is concerned. The reason for this difference in behavior may be that in the present invention a slight amount of polymerization has occurred, which tends to give stability to the final product without affecting solubility. This is believed to be true and to be supported by the fact that a physical mixture of a hexarnethyl ether of hexamethylol melamine and a dimethyl ethylene urea are not completely soluble in each other and is characterized by poor stability.
Whether a selected glycol monoalkyl ether is employed or not, the resinous reaction product of this invention may be characterized as substantially monomeric, meaning .that the product is essentially monomeric in nature and if polymer is present, the amount or extent is insufiicient to adversely affect the solubility and stability characteristics of the product.
The resinous composition of the present invention may be employed with other textile finishing resins, either thermosetting or thermoplastic, to improve the durability of such finishes or to modify the hand or other characteristics of the finished fabric. Thus, for example, the resinous product of this invention may be employed with ureaformaldehyde resins, various other cyclic ureas, as for example, 1,2-propylene urea-formaldehyde resins, 1,3-propylene urea-formaldehyde resins, guanamine-formaldehyde resins and their alkylated derivatives. Among the thermoplastic resins which may be mentioned are homopolymers and copolymers of lower alkylacrylates, such as methyl acrylates, ethyl acrylates, methyl methacrylates, butyl methacrylates or copolymers of these or their equivalents with styrenes, including ring and chain substituted styrenes, acrylonitrile, polyvinyl chloride, and the like. In addition, the resinous mixture of this invention may be employed with softeners, stiffeners, lubricants, dicyanamide and other conventional treating bath components, where compatible.
1. A process for preparing an infinitely water-soluble, substantially fully etherified, substantially fully methylolated melamine-ethylene urea-formaldehyde textile finishing resin characterized by excellent stability and suitable for use in imparting shrinkage control and wrinkle recovery to cellulose containing textile material, with minimum deleterious effects due to chlorine retention, which comprises reacting relative mole ratios of one mole of melamine and an excess of formaldehyde in an amount'between 8.0 and moles of formaldehyde as paraformaldehyde at a temperature between C. and 80 C. and at a pH between 7 and 11 in the presence of at least 6 moles of methanol until a clear solution is formed and reaction is complete, adding sufiicient additional methanol to the reaction mixture to make a total of at least 10 moles of said methanol in the reaction mixture, adjusting the pH of the reaction mixture to a value below 4, stirring said mixture at a temperature of between 15 and 60 C. until a complete solution is obtained, adjusting the pH of the solution to between 8 and 10, adding from between 0.6 and 1.2 moles of ethylene urea, reacting said ethylene urea and said excess formaldehyde to form dimethylol ethylene urea at a temperature between 30 C. and C. until reaction is complete.
2. A process according to claim 1 in which from between 0.25 and 1.0 moles of a monoalkyl ether of diethylene glycol, wherein the alkyl group contains 1 to 4 carbon atoms, is added to the reaction mixture prior to the adjustment of the pH thereof to below 4.
3. A process according to claim 2 in which the monoalkyl ether of diethylene glycol is the monoethyl ether of diethylene glycol.
4. A process for preparing an infinitely water-soluble, substantially fully etherified, substantially fully methylolated melamine-ethylene urea-formaldehyde textile finishing resin characterized by excellent stability and suitable for use in imparting shrinkage control and wrinkle recovery to cellulose containing textile material, with minimum deleterious effects due to chlorine retention, which comprises reacting relative mole ratios of one mole of melamine and an excess of formaldehyde in an amount between 8.0 and 20 moles of formaldehyde as paraformaldehyde at a temperature between 30 C. and 80 C. and at a pH maintained between 7 and 11 with sodium hydroxide in the presence of at least 6 moles of methanol until a clear solution is formed and reaction is complete, adding sufiicient additional methanol to the reaction mixture to make a total of at least 10 moles of said methanol in the reaction mixture, adjusting the pH of the reaction mixture to a value below 4 with nitric acid, stirring said mixture at a temperature of between 15 and 60 C. until a complete solution is obtained, adjusting the pH of the solution to between 8 and 10, adding from between 0.6 and 1.2 moles of ethylene urea, reacting said ethylene urea and said excess formaldehyde to form dimethylol ethylene urea at a temperature between 30 C. and 80 C. until reaction is complete.
5. An infinitely water-soluble, stable textile finishing resin composition containing on a relative mole basis 1 mole of a substantially fully etherified, substantially fully methylolated melamine, said etherified methylol melamine having at least 5.8 methylol groups and at least 5.6 etherifying groups, and from between.0.6 and 0.8 mole of dimethylol ethylene urea, said etherifying groups being principally methyl with up to about 2.5 of said groups being selected from the group consisting of alkoxyethoxyethyl wherein alkoxy contains 1 to 4 carbon atoms and alkoxyethyl, wherein alkoxy contains 1 to 3 carbon atoms.
10/59 Scott 260.69
MURRAY TILLMAN, Primary Examiner.
LEON J. BERCOVITZ, Examiner.