1981
Znd. Eng. Chem. Res. 1992,31, 1981-1984 Treybal, R. E. Liquid Extraction. In Chemical Engineer's Handbook, 5th ed.; Perry, R. H.,Chilton, C. H.,Eds.; McGraw-Hill: New York, 1973; Section 15. Wardell, J. M. Gas Chromatographic Analyses of Acetic Acid Production Wastewaters and Selection of Solvents for Extraction of the Carboxylic Acids. M.S.Thesis, University of California at Berkeley, 1976. Wardell, J. M.; King, C. J. Solvent Equilibria for Extraction of Carbxylic Acids from Water. J. Chem. Eng. Data 1978,23,144. Watson, E. K.; Rickelton, W. A.; Robertson, A. J.; Brown, T. J. A Liquid Phosphine Oxide: Solvent Extraction of Phenol, Acetic Acid and Ethanol. Solvent Eztr. Zon Ezch. 1988,6 (2), 207. Wise, D. L.; Augenstein, D. An Evaluation of the Bioconversion of Woody Biomass to Calcium Acetate Deicing Salt. Solar Energy 1988,41 (51, 453.
Won, K. W. Phase Equilibria for Extraction of Organic Solutes from Aqueous Waste Streams. Ph.D. Dissertation, University of California at Berkeley, 1974. Xu, J.-G.; Yu, W.; Tian, H.-S.; Su, Y.-F. Removal of Acids from Aqueous Solution of Glyoxal. International Solvent Extraction Conference, Moscow, Conference Papers; USSR Academy of Sciences:, Moscow, 1988; Vol. 3, p 298. Yang, S. T.; White, S. A.; Hsu, S.-T. Extraction of Carboxylic Acids with Tertiary and Quaternary Amines: Effect of pH. Znd. Eng. Chem. Res. 1991,30,1335-1342.
Received for review April 16, 1992 Accepted May 11, 1992
GENERAL RESEARCH Finishing Additives in Treatments of Cotton Fabrics for Durable Press with Polycarboxylic Acids? B. A. Kottes Andrews* Southern Regional Research Center, Mid South Area, Agricultural Research Service, U. S. Department of Agriculture, New Orleans, Louisiana 701 79
Billie J. Collier School of Human Ecology, Louisiana State University, Baton Rouge, Louisiana 70803
Recent activities by regulatory agencies that have limited the amount of formaldehyde that can be released by textiles have led to research on nonformaldehyde finishing for durable press. At the Southern Regional Research Center, we have discovered polycarboxylic acids as replacements for the currently-used methylol amide agents which give finishes that can release formaldehyde over the life of the textile. The ester finishes from these polycarboxylic acids, while as durable to home laundering as those from methylol amide agents, do not produce the same handle as the traditional ether finishes. Incorporation of certain finishing additives in the fiiish can improve the handle as well as enhance other textile properties. Optimization of pad baths and reaction conditions, and textile performance of the finished fabrics will be discussed.
Introduction At the Southern Regional Research Center (SRRC) we have found that certain polycarboxylic acids will esterify the cellulose hydroxyls of cotton to produce smooth drying
In this study, we have investigated the effect of inexpensive additives, both reactive and thermoplastic, that change fabric handle, on textile properties of fabrics finished with BTCA or citric acid (CA).
textiles (Welch, 1988; Welch and Andrews, 1989a,b; Andrew et al., 1989). With the proper catalysis,ester f d e s from butanetetracarboxylic acid (BTCA) are as durable to home laundering as those from amidomethyl ether counterparts (Welch, 1990). Others have extended these findings to pilot scale processing (Brotherton et al., 1989; Brodmann, 1990). Also, with proper catalysis, citric acid can be used to produce cotton fabrics with acceptable durable press levels (Andrews, 1990). One failure of the polycarboxylic acid-finished fabrics, however, has been the noticeable lack of a smooth, crisp hand associated with fabrics finished with methylol amide-based agents.
Experimental Section
'Presented, in part, at the 1990 Gulf Coast Textile Chemistry Conference of the Gulf Coast Section, American Association of Textile Chemists and Colorists, Dallas, T X , March 1-2, 1990.
Q888-5885/ 9212631- 198l$03.oO/Q
The fabric was an 80 X 80 cotton print cloth, desized, scoured, and bleached, weighing 3.2 oz/yd2. Butanetekacarboxylic acid and citric acid were obtained as reagent grade chemicals from Aldrich Chemical Co. [Names of companies or commercial products are given solely for the purpose of providing specific information; their mention does not imply endorsement by the U. S. Department of Agriculture over others not mentioned.] Sodium hypophoephite monohydrate catalyst was obtained from Baker Chemical Co.as a reagent grade chemical. The polycarboxylic acids and catalyst were used as 6% solids concentration of the aqueous padding solutions. The reactive additives, poly(oxyethy1eneglycols) (PEG) of molecular weight 400,600, and 1O00, glycerol (GLY), and diethylene glycol (DEG) were also reagent grade 1992 American
Chemical Society
1982 Ind. Eng. Chem. Res., Vol. 31, No. 8, 1992
chemicals from Aldrich Chemical Co. A nonionic-emulsified polyethylene (PE), an ethylene/vinyl acetate copolymer (E/VA), two polyacrylates described by the manufacturer as "self-reacting" (PA, PA/AN), and a starch ether (SE) were obtained as commercial products from National Starch & Chemical Corp. The harder polyacrylate (PA/AN), with the higher T4, contained a small amount of acrylonitrile. A nonionic-emulsified polypropylene (PP)was obtained as a commercial product from Seydel-Wooley Co. Pad bath concentrations of the additives are noted in the text and figures. Fabric treatments were carried out on a laboratory scale. Fabric samples were padded with two dips and two nips to approximately 90% wet pick up. After the padding step, the fabrics were dried at 85 "C for 5 min and cured at 180 "C for 90 s in forced draft ovens. The cured fabrics were washed and tumble dried one time according to AATCC test method 124 (washing procedure IV, drying procedure A) before testing. Current AATCC and ASTM testa were used to evaluate the appearance, strength, toughness, and hand properties of the fabrics (American Association of Textile Chemists and Colorists, 1989; American Society of Testing and Materials, 1985). Three specimens per fabric treatment were evaluated; results are reported as the mean of three determinations. Wrinkle recovery angle was measured in the warp and filling direction; tearing strength, breaking strength, and Stoll flex abrasion were measured in the warp direction. Mean standard deviations for these properties were 4.3 (wrinkle recovery angle), 13.7 (tearing strength), 2.1 (breaking strength), and 8.2 (Stoll flex abrasion). The definition of hand in the AATCC Evaluation Procedure 5, Fabric Hand, Subjective Evaluation of, in AATCC Technical Manual 1992, is, "the tactile sensations or impressions which arise when fabrics are touched, squeezed, rubbed or otherwise handled." There is no ordinal scale associated with this procedure. For assessment of the surface characteristics of the fabrics, selected unwashed specimens representing the finishes and additives used were tested on the Kawabata surface tester. The coefficient of friction, mean deviation of the coefficient of friction, and the mean deviation of surface roughness were measured in the warp direction. Five values for the face and five values for the back were determined. The bending rigidity and bending hysteresis were also measured.
Results and Discussion Table I shows the influence of increasing concentration of selected polyols on textile properties of cotton print cloth finished with 6% BTCA and 6% NaH2P02*H20 catalyst. Polyols can be esterified by polycarboxylic acids to produce a network finish in the fabric. The extent and density of the network are controlled by the functionality of the carboxylic acid as well as the functionality and molecular weight of the polyols. The two higher molecular weight PEGS, 600and 1O00, increased the wrinkle recovery angle as the concentration of PEG was increased. These additives were observed to improve the smoothness of the hand of the fabrics. PEG 400 had little influence, and diethylene glycol (DEG) decreased the wrinkle recovery angle as the concentration of glycol was increased beyond 4% ; competition with cellulose hydroxyls is operative. The response of the durable press rating to PEG is somewhat different. Only PEG 600 increased the durable press rating initially. All other PEG'S decreased the durable press rating beyond the lowest concentrations of the additive. The decrease in the durable press rating with the increase in pad bath concentration of poly(ethy1ene
Table I. Properties of Cotton Fabrics Finished with 6 % BTCA and Polsolsa Stoll flex glycol,
7%
durable condn wrinkle tearing breaking abrasion press recovery angle, strength, strength, resistance, rating deg (w+O g (w) lb (w) cycles
DEG 2 4 6 8 10
4.0 3.5 3.2 3.0 3.0
260 261 254 246 248
2 4 6 8 10
4.0 3.7 3.5 3.5 3.2
263 266 262 271 266
2 4 6 8 10
4.5 4.5 4.0 3.7 3.5
27 1 273 280 290 300
2 4 6 8 10
4.0 4.0 3.7 3.5 3.5
275 287 295 299 307
0
4.0
260
427 467 487 493 513
25 25 31 31 29
36 49 66 67 62
24 26 25 27 25
27 37 37 51 55
24 25 25 26 28
24 27 29 49 56
407 447 567 493 493
22 25 23 27 23
27 28 29 35 45
No Additive 547
31
50
PEG 400 440 427 433 453 433
PEG 600 493 393 433 447 513
PEG lo00
ow = warp; f = fill.
glycol) is not unexpected. It is well-known that, although polymer additives can increase fabric resiliency, their presence can distort the fabric symmetry as uneven dimensional changes occur during laundering. There was an initial decrease in tearing strength as glycol was added to the pad bath and then a rise as the system was flooded with polymer. However, tearing strength levels never reached those of the fabric finished without glycols. Addition of the long chain polyols (MW 1 400) produced an overall decrease in the breaking strength. With diethylene glycol (MW = 106), however, the breaking strength increased at the higher glycol pad bath levels. It is known that the lower molecular weight glycols compete with cotton itself for cellulose cross-linkers. Such competition produces decreased cross-linking and the resultant lowered appearance properties noted above with less of a reduction in breaking strength. Stoll flex abrasion also followed the pattern of an initial decrease at the 2 % additive level followed by an increase. At molecular weighta I600,the number of cycles to failure for fabric finished without glycol was exceeded at higher concentrations of additive. Nonreactive hand modifiers required lower concentrations of additive than did the polyols; higher concentrations produced excessive fabric stiffness. The vinyl acetate/ethylene, polyacrylate, and starch ether additives visibly flattened the fabric surface. Table I1 shows the influence on textile properties of these hand m a i e r s and of the polyethylene and polypropylene softeners. All increased wrinkle recovery angle but the starch ether produced the least increase. The starch ether is a more rigid polymer and does not provide fiber to fiber lubrication as do the hydrocarbon derivatives and therefore does not enhance wrinkle recovery. Durable press ratings were unchanged by these additives. The benefits of lubrication can be seen in the tearing strength data also. Only the softeners, polyethylene and
Ind. Eng. Chem. Res., Vol. 31, No. 8, 1992 1983 Table 11. Properties of Cotton Fabrics Finished with 6% BTCA and Nonreactive Additives Stoll flex durable condn wrinkle tearing breaking abrasion additive, press recovery angle, strength, strength, resistance, % rating deg (w+D g (w) Ib (w) cycles Polyethylene 36 4.0 279 693 25 0.5 4.0 286 667 26 39 1.0 33 4.0 286 673 23 2.0 42 4.0 282 673 29 4.0 0.5 1.0 2.0 4.0
4.0 4.0 4.0 4.0
Polypropylene 271 673 284 647 284 667 285 667
27 25 25 25
35 24 22 22
0.5 1.0 2.0 4.0
4.0 4.0 4.0 4.0
Vinyl Acetate/Ethylene 277 540 287 540 299 520 299 520
31 27 30 30
43 45 62 62
0.5 1.0 2.0 4.0
Self-Cross-Linking Polyacrylate/Acrylonitrile 4.0 269 567 40 4.0 274 547 38 4.0 277 553 39 4.0 278 547 40
39 41 45 42
Self-Reactive Polyacrylate 278 587 280 587 291 553 285 573
37 37 38 38
53 55 73 64
4.0
4.0 4.0 4.0
Starch Ether 266 540 265 540 270 533 267 513
29 32 32 33
54 60 39 46
0
4.0
No Additive 260 547
31
50
0.5
1.o
2.0 4.0 0.5 1.0 2.0
4.0 4.0 4.0 4.0 4.0
polypropylene, produced a marked increase in tearing strength over treatments without additive, the polyacrylate without acrylonitrile imparted a lesser increase. The handbuildera, vinyl acetate/ethylene and starch ether, actually decreased this property at pad bath concentrations 12%. Breaking strength and stoll flex abrasion did not respond in the same way as tearing strength. The softeners decreased the breaking strength. With Stoll flex abrasion, the starch ether produced an increase in resistance at the lower concentrations and the vinyl acetate/ethylene and softer polyacrylate produced an increase at the higher concentrations. The polyethylene, polypropylene, and harder polyacrylate produced an overall decrease in resistance. Because citric acid, an inexpensive polycarboxylic acid that is approved for food use, shows promise as an esterification cross-linking agent for cellulose, it was of interest to compare additive influence in treatments with BTCA and with citric acid (CA). Comparisons for poly01 additives at a 2% pad bath concentration level are seen in Table III. This additive concentration was selected for comparison because it was the lowest concentration to improve handle while maintaining good appearance properties with the least adverse influence on strength/toughness properties. At the optimum additive concentrations, wrinkle recovery angles are lower for citric acid than for BTCA treatments. This pattern reflects that from treatments without additive. Also, the lower molecular weight polyols with a high functionality to molecular weight ratio, such as diethylene glycol and glycerol, did not improve the wrinkle recovery angle in citric acid-treated fabrics, just as they did not improve this property in BTCA-treated fabrics. The po-
Table 111. Comparison of Glycols in Treatments with BTCA and CA condn wrinkle tearing breaking Stoll flex glycol, recovery angle, strength, strength, abrasion 4% deg (w+D I(w) lb (w) resistance, cycles Citric Acid GLY 246 660 35 83 244 547 37 DEG 86 PEG 400 254 520 34 51 257 500 36 PEG 600 66 PEG lo00 246 513 34 62 245 560 36 17 none GLY DEG PEG 400 PEG 600 PEG lo00 none
257 260 263 271 275 260
BTCA 607 427 440 493 407 547
33 25 24 24 22 31
52 36 27 24 27 50
Table IV. Comparison of Nonreactive Additives in Treatments with BTCA and CA Stoll flex condn wrinkle tearing breaking additive, recovery angle, strength, strength, abrasion 90 deg (w+O g (w) lb (w) resistance, cycles Citric Acid 284 560 34 77 VA/E(4.O) 246 547 37 86 SE(l.O) PA/AN(l.O) 247 600 39 113 PA 266 600 39 160 272 547 37 86 PE(0.5) 41 259 507 36 PP(0.5) 245 560 36 77 none VAIE(4.O) SE(l.O) PA/AN(1.0) PA(l.0) PE(0.5) PP(0.5) none
299 265 274 280 285 277 260
BTCA 520 540 547 587 687 673 547
30 32 38 37 26 27 31
62 60 41 55 28 35 50
lyob did not have a markedly adverse effect on the tearing strength in treatments with CA. The breaking strength was not appreciably changed by the poly01 additives to the citric acid treatments but, with the exception of glycerol, was lowered by the additives to the BTCA treatments. The lower molecular weight polyols increased resistance to the Stoll flex abrasion in the citric acid-treated fabric but not in the BTCA-treated fabric. In fact, the polyols had an overall adverse effect on the Stoll flex abrasion in BTCA-finished fabric. Comparisons were also made for nonreactive additives in treatments with BTCA and citric acid. The nonreactive additives were used in the optimum concentrations for each additive, as noted in parentheses in Table IV. As with treatments containing polyols as additives, wrinkle recovery angles in fabrics from treatments with nonreactive additives were also lower for the citric acid than for the BTCA treatments. For both acids, the starch ether was least effective in improving this appearance property. The tearing strength of the citric acid-treated fabrics was not improved by the softeners, polyethylene and polypropylene, as it was with the BTCA treatments. The soft polyacrylate elastomer, however, improved the tearing strength for both acid treatments. The breaking strength was increased appreciably only by the polyacrylates as additives to the citric acid treatments. Stoll flex abrasion in both acid treatments was decreased by addition of polypropylene and in BTCA treatment by addition of polyethylene and the polyacrylate/acrylonitrile additives. The nonelastomeric additives known to increase fabric handle, vinyl acetate/ethylene and starch ether, did not have a deleterious effect on abrasion resistance in
1984 Ind. Eng. Chem. Res., Vol. 31, No. 8, 1992 Table V. Surface Properties of Cotton Fabrics with Selected Finishes and Additives finish BTCA BTCA BTCA BTCA BTCA BTCA BTCA BTCA DMDHEU untreated fabric
additive none PEG lo00 PEG 600 vinyl acetate/ ethylene copolymer vinyl acetate/ ethylene copolymer" starch ether high T gpolyacrylate low T gpolyacrylate none
MIUa MMDb
SMD,' Wm
0.0334 0.0286 0.0304 0.0324
5.69 5.85 5.67 5.49
0.238 0.0286
5.57
0.229 0.234 0.273 0.198 0.203
5.83 5.60 5.61 5.51 5.68
0.226 0.254 0.240 0.226
0.0346 0.0294 0.0306 0.0308 0.0268
"Coefficient of friction. bMean deviation of friction. deviation of roughness. Alternate source.
'
Mean
either of the acid treatments. Instrumental Evaluation of Fabric Surface The results of the measurement of surface properties are presented in Table V. The coefficient of friction was lowest for the unfinished fabrics and those finished with dimethyloldihydroxyethyleneurea (DMDHEU). The highest friction value was exhibited by the fabric finished with BTCA and the low Tqpolyacrylate. An analysis of variance treating each fabric as a separate group showed that the DMDHEU and unfinished fabrics had significantly lower values than all of the BTCA-finished fabrics, while the fabric treated with the low T polyacrylate was significantly higher. Although the BTC!A-finished fabrics with the other additives did not show a consistent pattern of differences, the PEG-modified fabrics did have somewhat higher friction values. The surface roughness of the fabrics varied with the type of additive used. The BTCA-finished fabrics finished with vinyl acetate/ethylene copolymer and polyacrylates were smoother, as indicated by lower values of the mean deviation of surface roughness. As noted above, these fabrics were also observed to have a smoother appearance. The vinyl acetate/ ethylene additives gave smoothness values similar to that of fabrics treated with DMDHEU, while the polyacrylab additives gave slightly higher values. The roughest fabrics were the BTCA-finished fabrics with the PEG lo00 modifier and the starch ether and the unmodified BTCA. These three fabrics were rougher than the unfinished fabric. In terms of overall surface properties, the DMDHEUfinished fabric and the BTCA-finished fabric with the vinyl acetate/ethylene modifiers appeared to be the best. However, if the modifier is making the fabric smoother, it is important to determine if it is also making it stiffer. The fabrics modified with the vinyl acetate/ethylene copolymer had bending rigidities of 0.18-0.20gf-cm2/cm (gf = gram force) compared to 0.14gf-cm2/cmfor unfinished fabric and 0.12 gf-cm2/cmfor BTCA-finished fabric with no modifier. The stiffest fabric was that treated with the starch ether. It had a bending rigidity of 0.39 gf.cm2/cm. The bending hysteresis results were similar to the bending rigidities. Summary In general, the hand modifiers do not adversely alter other textile properties when used at the minimum levels that reduce raspy hand. The glycols of molecular weight I400 either did not influence or decrease the wrinkle recovery angle; glycols of molecular weight 1 600 increased
this property. Vinyl acetate/ ethylene, polyacrylates, polyethylene, and polypropylene ale0 increased the wrinkle recovery angle; starch ether had little or no influence. Although polyols decreased the durable press ratings, the higher molecular weight PEG'S,those that improve handle, produced the least decrease. The nonreactive additives did not alter the durable press levels. Tearing strength was adversely affected by the glycols. The softeners, polyethylene and polypropylene, increased this property, and the hand builders, vinyl acetate/ ethylene and starch ether, had little appreciable effect; polyacrylates increased the tearing strength. The nonelastomeric softeners, in general, did not improve the breaking strength. Stoll flex abrasion resistance was decreased initially by both the polyols and thermoplastic additives; the polyols and harder polyacrylate then increased resistance at the higher concentrations of additive. On the other hand, the softer polyacrylate and starch ether also increased abrasion resistance initially. In general, Kawabata analysis showed that the surface chmactistics of BTCA-treated fabric became more similar to those of DMDHEU-treated fabrics by addition of vinyl acetate/ethylene polymers to the pad bath. Polyacrylate additives also decreased surface roughness of BTCAtreated fabrics. In comparisons between BTCA and citric acid finishing, lower appearance and higher strength and toughness properties oculd be seen to reflect lower croas-linking levels in citric acid-treated fabrics both with and without additives. Acknowledgment We thank Mary Frances Perkins and Raymond S. Richard for the textile tests. Registry NO.BTCA, 1703-58-8;CA, 77-92-9;PEG, 25322-68-3; GLY,56-81-5;DEG, 111-46-6;PE, 9002-884;E/VA, 24937-78-8; PP, 9003-07-0.
Literature Cited American Aaaociation of Textile Chemists and Colorists. AATCC Technical Manual; AATCC: Research Triangle Park, NC, 1989; Vol. 64. American Society for Testing and Materials, Committee D-13. ASTM Standards on Textile Materials; ASTM Philadelphia, PA, 1985. Andrews, B. A. Kottes. Nonformaldehyde DP Finishing of Cotton with Citric Acid. Text. Chem. Color. 1990,22 (9),63. Andrews, B. A. Kottes; Welch, C. M.; Morrell, B. J. Efficient Ester Crosslink Finishing for Formaldehyde-Free Durable P r e s Cotton Fabrics. Am. Dyest. Rep. 1989, 78 (6),15. Brodmann, G. L. Performance of Nonformaldehyde Cellulose Reactanta. Text. Chem. Color. i990,22 (ll),13. Brotherton, D. L.; Fung, K. W.; Addison, A. L. An Alternative Zero Formaldehyde Durable Press System Book Pap.-Znt. Conf. Exhib., AATCC 1989, 170. Welch, C. M. Tetracarboxylic Acids as Formaldehyde-Free Durable Press Finishing Agents Part I Catalyst, Additive and Durability Studies. Text. Res. J. 1988, 58 (8),480. Welch, C. M. Durable Press Finishing without Formaldehyde. Text. Chem. Color. 1990, 22 (5), 13. Welch, C. M.; Andrews, B. A. Kottes. Catalysts and Processes for Formaldehyde-Free Durable Press Finishing of Cotton Textiles with Polycarboxylic Acids. U.S.Patent 4,820,307,1989a. Welch, C. M.; Andrews, B. A. Kottes. Eeter Crosslink A Route to High Performance Nonformaldehyde Finishing of Cotton. Text. Chem. Color. 1989b,21 (2),13.
Receiued for reuieur April 30, 1991 Revised manuscript receiued April 7, 1992 Accepted May 26,1992
