US2617744A - Treatment of nonwoven cellulosic fabrics with urea resin colloids - Google Patents

Description

wov'en cellulosic fabrics.

relates to a method for increasing the tensile, strength of non-woven cellulosic fabrics wherein" substantially all the fibers are oriented in one" Patented Nov. 11, 1952 UNITED STATES. PATENT OFFICE TREATMENT OF NONWOVEN CELLULOSIC FABRICS WITH UREA RESIN COLLOIDS James K. Dixonyltivrside, Conn., assignor to American Cyanamid Company, New York, N. Y., a corporation of Maine No Drawing. Application October 26, 1949,

7 Serial N0. 123,793

1 Claim. (cum-e5) This invention relates to the treatment of nondirection. V

I haverecently discovered that the application of cationic aminotriazine-aldehyde resin acid colloids such as, for example, an acetic acid col: 1016. of methylated trimethylol melamine, to 'un-" woven cellulosic fabrics increases their tensile j strength. Processes for so treating unwoven cellulosic fabrics are described and claimed in my copending applications; Serial No. 123,792 filed October 2 6, 1949,'entitled Treatment of Non- Woven Cellulosic Fabrics with Weak Acid AminotriazineResin Colloids, and Serial No. 123,795

filed October 26, 1949, entitled Treatment of Non-Woven Cellulosic Fabrics with Modified Acid Resin Colloids, and now abandoned.

a It is an object of the present invention to provide a process for treating non-woven cellu losic fabricswherein the fibers are substantially all oriented in one direction.

It is another object of the present invention to provide a process for treating non-wovencotton fabric in which substantially all of the cotton fibers are oriented in one direction.

Another object oi the present invention is to provide a process for treating non-woven viscose fabric in which substantially all of the viscose fibers are oriented in one direction.

Still another object of the present invention is to provide a process for the treatment of nonwoven fabrics containing a mixture of cotton j More particularly, it

and viscose fibers substantially all of which are oriented in a single direction. 7

A further object of the present invention is the production of a non-woven cellulosic fabric of increased tensile strength.

It is a further object of the present invention to increase the. tensile strength of non-woven cellulosic fabrics in which substantially all of the fibers are oriented in one direction, the increase occurring both in the direction of the fibers and in-the direction perpendicular 'to that'of the The above and other objects are attained by treating a fabric composed of substantially unidirectionally oriented, non-woven cellulosic fibers with a colloidal aqueous solution of a polymerized aldehyde condensation product of a carbamido.

compound such as urea.

The invention will be described in greater detail in conjunction with the following specific examples in which proportions are given in parts by weight unless otherwise noted. The examples are merely illustrative and it is not intended that the scope of the invention be limited by the details therein set forth.

EXAMPLE 1 A non-woven fabric known as cotton Masslinn is used in this and certain of the following examples. The cotton fibers in Masslinn are substantially all oriented in one direction, and the parallelized fibers are bonded together at intervals in a direction perpendicular to the direction of the fibers with a thermoplastic resin of the polyvinyl acetate type, the resin constituting generally from about 6%-10% of the weight of the fabric. Although the tensile strength of Masslinn will depend to a degree upon the way in which it is mechanically processed or treated, it will be Resin Designation Resin Description ResinA Acetic acid colloid of ammonia modified I urea-formaldehyde resin. Resin B Tetraethylenepentamine mo difi e 1 urea R C formaldehyde resin colloid.

65111 Bicsllligtg modified urea-formaldehyde resin The wetted out samples are i Tensile Strength Percent m Resin Add on Warp Fill It is believed that the resin colloid solution extracts and/or redistributes the polyvinyl-acetateresin binder present in Mas'slinn This theory seems to be borne out by the fact, as will be demonstrated in a later example,'that-'when new woven fabric containing no resin binder is simif larly treated with a resin colloid solution there appears to be a linear relationshipbetween resin pick-up and increased tensile strength. Furtheremore it is believed to explain the slight apparent decreases in warp tensile strength which'are sometimes observed. In SliCh instances, however, there. is;.an over-alt increasei in tensilestrength sinczthat in the fill direction increases propertion'ately" far' more' thanr thafiJOff the warp may decrease.

Similar treatment ofi Massli'nn: with-' non col- 1oidal2- dimethylol: urea and an; acid-liberating... catalysts decreases: the tensile strength: of the:- :Eabtic:

In this example a non-woven cotton' mate-- rial composed of substantially unidirectionally oriented fibers with-nrrresirr binder is used instead of Masslinn. Since the material has very little tensile strength in the dry state and even less}- when wet, it may be desirable to support itduring..--the; application of; resin thereto;

Samples of the: nonwoven material aresupported? on sheets. oftin; plated soft steel 0-.012- inch; thick having a smooth. surfaceeand resin colleid-;-solutions are carefully poured thereover; Thetin.sheets with the so wetted out-t-samples are then passed threugh. squeeze: rolls asin- Example l. The materia lis stripped; from the-sheets-andq cured by heating. for about fi-lo'minutesl at: about. 140 C.

The: result of: tensile strengthmeasurements; name. samples. off-treated: material are set forth in the. following' tablez 1 Tensile Percent Resinv Strengthen 'lbstlfill as, for example, by glacial acetic acid, are treat- 75 5 minutes.

4 ed as described in the foregoing examples with urea resin colloids.

Preparation of resin A 60 parts urea (1 mol) 243 parts 37% aqueous formaldehyde (3 mols) 38.5 parts ammonium acetate (0.5 mol) The formaldehyde is adjusted to a pH of about 8.5, the urea is dissolved therein, and the solution is heated at'70- C. forlflminute's; The ammonium acetate is then added,-and the reaction mixture is heated to boiling and boiled gently for A noticeable viscosity increase occurs. The cationic resin colloidal solution obtained contains 3 l'%- resin solids.

Preparation of resin B 0'-.'7'5-part trietha-nolamine 20.0 parts urea 2-.ojparts tetraethylenepentamine 2.8 parts hydrochloric acid (specific gravity 1.19) 7.l parts water 4.4 parts 10% aqueous sodium hydroxide The formaldehyde andtriethanolamiiie are charged into a kettle and well stirred. The urea is added and aftermixing the-solution, which has a'pH of about 9;6-8:8, heated by s'tearjnby 3' parts of wa'te'rlj Thetemperature-rises my about C. 'duringthisad'dition due to the heat-- andasolution of' the hydrochloric "acid in 3 1 parts ofwater is added; The remaining Water is'also added. The temperatureiof thereaction" is again brought to about 70"-' C; andmaintained at that temperature for one hour. Te'n' minutes'a'fte'r the addition of tlie'. acid, the"pI-I'1of the mixture is.

about 2.4 and it gradually} drops to. 1.7 -1.81" Aft er the hour reactiontli'e reaction'productis cooled downv by cooling watentb; 55 C. and immediately neutralized by slowjaiddition of the sodium hydroxidesolution. After. further coolingito about 20-25" C. thei'p'H of ther'esin i'sadjusted to 618 7.0. The resin: syrup obtainedin" whielrthe molar ratio of'formaldehyde to ureais 2.5-:1

contains about 45% man solids." This ane-ebased only" on the resin-forming "ingredients and ignores salts and minorringredient's;

Preparation of resin 6 7175; parts. 37%; aeueaus tormaldehyd 40.5; parts sod'iuni-.mtabis'ul'fite' 236"par.tsfurea j 2.8 parts 10% aqueous 'seaium'Hydroxide: 1.1 parts 36% hydrochloricacid 2.2 parts triethanolamine.

The sodium metabisulfitei-andl urear are dise solved in the formalin and the' pH of the somtibii isadjusted mea ae byithe addition; ofithe: sodium hydroxide solution; The-mixture 'isfhea-te ed torefiux and refiux'edsfor thirtyminutesa: Hy-' droc'hloric acid is theniaddedito lower" the": pH

of the's'oluti'on at 310-315". In'order to compensate: for the heat of dilution of the acid it is adviser ble t'o. coolv the: solution-to about 80 C; before the acidi is added}: The'reaction mixture is 11r-- ther refluxed for one hour, cooled to -85 C.

As the reaction is exothermic'some' and maintained at that temperature. The visc'osity of the resin syrup will increase steadily and when it reaches around 200 centipoises measured by the Gardner-Holdt method the reaction is stopped by addition of the triethanolamine. The resin is cooled to room temperature and additional triethanolamine is added if necessary to adjust the pH to 8.0-8.5.

-:.\The resin solution in' which the formaldehydeurea mol ratio is 2.25:1 contains about 54% resin solids. This figure is based on the-resin-forming ingredients including the sodium metabisulfite and does not include salts and minor ingredients. w

In general, whenever the monomer of a carbamide-aldehyde resin can be converted to a polymer which lends itself to the formation of a colloidal solution of the polymerized resin, the resin is found to impart an appreciable improvement in the tensile strength of non-woven cellulosic fabrics, both in the direction of the fiber and in the direction perpendicular to that of the fiber. Most of the resins which I have found useful are cationic in nature and since these appear to eifect the largest increase in tensile strength they constitute the preferred embodiment of my invention. However, anionic type resins (Example 1, resin 0) are also useful.

In addition toResin B, other alkylene polyamine modified carbamide resins such as those modified with ethylene diamine, diethylene triamine, triethylene tetramine, etc., may be used.

. Moreover, colloidal solutions of guanidine modified carbamide resins, pyridine modified carbamide resins, carbamide resins modified with glycols, amino alcohols, etc., are also useful.

Suitably modified aldehyde condensation products of carbamides including urea, thiourea, N- hydrocarbon substituted ureas and thioureas such as N -methyl urea, N-phenyl urea, N-benzyl urea, N-ethyl thiourea, N-phenyl thiourea, N- benzyl thiourea, etc., wherein each amino nitrogen atom contains at least one hydrogen atom attached thereto are contemplated as coming within the scope of the present invention.

Carbamide resins modified with amino sulfonic acids such as sulfanilic acid or with aminocarboxylic acids such as fi-alanine or with hydroxycarboxylic acids such as salicyclic acid may be substituted for the bisulfite modified resin C.

The aboveresins are prepared by known methods as illustrated by the preparations of resins A, B and C set forth in detail.

Aldehydes other than the formaldehyde of the examples, such as formaldehyde-yielding materials including paraformaldehyde and hexamethlyenetetramine, benzaldehyde, furfural, acetaldehyde, paraldehyde, etc., may be used.

Resin colloids containing hydrochloric or other strong acid may not be used in the process of the present invention since they do not improve the tensile strength of the non-woven cellulosic fabrics.

In order to obtain the optimum effect of the present invention, the non-woven cellulosic fabricis so treated with the acid resin colloids that from about 0.5% to 25% by weight of resin solids, based on the dry weight of the fabric, will be deposited therein. Actually there is no real lower limit since incorporation of any small amount of,

the resin will increase the tensile strength to some degree but for practical purposes a lower pick-up than 0.5% will not increase the tensile strength appreciably. Higher pick-ups than 25%, however, produce undesirable properties such as excessive stiffness and harsh feel, and accordingly the upper limit is a real and practical one. I i

The invention is not limited to any particular method offimpregnation of the non-woven fabric which may be immersed in a resin solution and the excess resin removed or which may be sprayed with a resin solution if necessary. or if desired. In any event special care in handling must be taken in view of the. extremely low tensile strength of the untreated non-woven fabrics, particularly when they are wet. I, In the examples the resin-impregnated fabrics are dried and cured at about 140 C. for from 6-10 minutes. This is merely a matter of convenience since the acidcolloid produces thesame tensile strength increase at much lower curing temperatures. Even air drying is suiiicient, and therefore little or no heat curing is really necessary in order to obtain in the fabric a resin polymer with desirable binding properties. Generally speaking, however, the impregnated fabric will be allowed to dry at temperatures ranging from about 65-400 F.

Non-woven fabrics composed of substantially unidirectionally oriented cellulosic fibers, when treated according to the process of the present invention, are likely to possess a harsh and somewhat stiif hand, this effect being dependent upon the resin concentration and increasing with increased add-on or dry pick-up of the resin. There are several ways of improving the appearance and hand of the fabric.

In the first place, the acid colloid resins may be printed onto non-woven fabrics in much the same manner as the manufacturers of Masslinn apply the resin binder.

Another method involves lap calendering of dried non-woven fabrics treated with the resin colloids to: soften the hand.

Moreover, the resin colloid treated non-woven fabrics may be hot calendered. A soft, yet firm, v

hand results.

A fourth remedy involves addition to the resin colloid of a textile softener such as, for example, the reaction product of from 5.5-6.5 mols of ethylene oxide with one mol of a mixture of the octadecylamine salt of N-octadecyl carbamic acid and the octadecyl guanidine salt of N-octadecyl carbamic acid as described in U. S. Patent No. 2,427,242. The softening agent appears to make the surface feel less harsh.

It is an advantage of the present invention that non-woven fabric which has been treated with a resin colloid may be dyed or pigment printed. Moreover, the treatment of the present process animalizes the fabric so that it may be dyed with acid dyestuffs.

The treated fabrics of the present invention may :be coated to obtain interesting and useful articles. Other uses for my resin treated nonwoven fabrics are as folows: towels, napkins, doilies, dish cloths, table cloths, drapery materials, wall covering, pipe covering, milk filters, cheese press cloths, ribbon, chemical filters, etc. If they are heat pressed to a stiffness, the fabrics are useful in the manufacture of lampshades, lintless wiping cloths, etc.

Use of my resin colloid treated non-woven fabrics as the plies of a laminate results in the production, of a laminated product of improved fiexural strength, flexural modulus, hardness and tensile strength and decreased water absorbency when compared with one made up of plies of untreated non-woven fabric.

wer mm I ALDIOCGSSWhiChT consists-- of immersing: 92211011?" woven fabric composed of substantially unid1:-

rotationally orientedootton' and; viscosezfibers" in eqiml proportionsdn a; neutral. colloidal aqueous; solutioni off ai-cationiai'po'lymerized modifidmreai fovmafidehyde condensation productzprepared; by reaiotm'gi 6718' parts df formalim 20: parts: of:- urea; fiil t's by'weightofltetraiethylnepnfimmn' "e1:

uni a'eidi conditions for more: than?" 11/; hours .10 at '70 dgr'ees' centi'zmd 'and then neutralizing;

the reaction proflmxniemzttor squeezing; the

afiidwint of condensation prodilct on the fabrid.

to I3 percent: of the div weight of fabric); the'r 'e v Ma is-substantiallyincreased;

and; 10'? minutes 1- dry: ihei-= fazbrim andjcllrewthev' condensatiom-producm to; a; :water -ins olublor sum.

and-dap' acalenderi-ngith'evdnied fabrica-tozsoitnzthe hand-:whereby thvfill tensile-stnengthoiithafiabfi Number Name Dato. l