Abstract:
There is provided a method of finishing a cellulosic fiber-containing textile product with a resin bath based on a water-soluble urethane prepolymer. This treatment provides for improvements in dry and wet creased crease resistance and wash-and-wear properties of cellulosic fiber-containing textile products.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a method for finishing cellulosic fiber-containing textile products. More particularly, the present invention relates to a method of treating a cellulose-containing textile with a resin bath formulated to impart improved crease resistance and wash-and-wear properties thereto. 
     2. Description of the Prior Art 
     Cellulosic fiber is a textile material available readily at low cost from abundant resources and because of its excellent dyeability, hygroscopicity and air permeability, this fiber provides attractive fabrics having good wearing comfort. 
     However, since cellulosic fabrics are generally inadequate in dry crease resistance and wet crease resistance, they become severely creased and wrinkled in use. These creases do not easily recover. Moreover, the wash-and-wear property of cellulosic textile fabrics is also poor. 
     Therefore, there has been a long-standing need for improvements in dry and wet crease resistances and in wash-and-wear property of cellulosic fabrics without detracting from their other inherent desirable properties. In attempts to meet these objectives, formaldehyde reaction products or formaldehyde-containing thermosetting resin precondensates such as urea-formaldehyde, melamine-formaldehyde, ethyleneurea-formaldehyde, glyoxalmonoureine-formaldehyde, etc. have been developed as resin finishing agents for cellulosic fabrics. 
     However, when these resin finishes are used singly in the processing of cellulosic textiles, the free formaldehyde liberated from the textile products tend to cause skin disorders and, therefore, the use of these finishes in the field of clothing is subject to serious limitations. Furthermore, these finishes do not provide fully satisfactory results in regard to dry crease resistance, wet crease resistance, wash-and-wear property and so on. 
     After intensive research undertaken to overcome the above-mentioned disadvantages of the prior art technology, the present inventors arrived at the present invention. 
     SUMMARY OF THE INVENTION 
     This invention relates to a method for finishing a cellulose fiber-containing textile product comprising treating a cellulose-containing textile product with a resin bath containing as an essential ingredient a water-soluble urethane prepolymer having at least two blocked isocyanato groups adapted to regenerate free isocyanato groups within its molecule (hereinafter referred to as a blocked isocyanate-containing water-soluble urethane prepolymer). 
     DETAILED DESCRIPTION 
     The blocked isocyanate-containing water-soluble urethane prepolymer used in accordance with the present invention is exemplified by water-soluble urethane prepolymers each containing at least two isocyanato groups blocked by one or more different blocking agents selected from the group consisting of phenols, oximes, imidazoles and acid sodium sulfite. 
     The water-soluble urethane prepolymer containing at least two isocyanato groups within its molecule is exemplified by water-soluble urethane prepolymers each containing two or more terminal isocyanato groups obtainable by reacting one or more polyether polyols, which are prepared by addition-polymerizing an alkylene oxide component of which ethylene oxide is an essential member with a compound containing at least two active hydrogen groups, or a mixed polyol consisting of a mixture of one or more members of said polyether polyols and one or more other polyols with one or more organic polyisocyanate compounds, and is preferably a water-soluble urethane prepolymer containing three or more terminal isocyanato groups and having a molecular weight of 2,000 to 30,000, an ethylene oxide content of 25 to 65% percent, and a regeneratable isocyanato content of 1 to 6 percent. 
     Outside of the above respective ranges, the hand and wet crease resistance of finished textile products are not as satisfactory as may be desired. 
     The polyether polyols mentioned above are exemplified by the compounds produced by addition-polymerizing a compound containing two or more active hydrogen groups with an alkylene oxide component of which ethylene oxide is an essential member. 
     The above-mentioned compound containing two or more active hydrogen groups includes, among others, polyhydric alcohols and amines. The polyhydric alcohols include diols such as ethylene glycol, propylene glycol, butanediol, hexanediol, octanediol, decanediol, etc.; triols such as glycerol, hexanetriol, trimethylolethane, trimethylolpropane, etc.; and polyols such as erythritol, pentaerithritol, sorbitol, sucrose, and so on. The amines include alkanolamines such as ethanolamine, triethanolamine, triisopropanolamine, tributanolamine, etc.; N-methylamine, ammonia, ethylenediamine, diethylenetriamine, triethylenetetramine, diaminophenylmethane, methylenebis-o-chloroaniline (MOCA), phenylenediamine, xylylenediamine, piperazine, isophoronediamine and so on. 
     The alkylene oxide includes ethylene oxide, propylene oxide, butylene oxide, etc. and ethylene oxide is essential. 
     Examples of said other polyols, are polyoxyalkylene polyols which do not contain ethylene oxide, polyester polyols, silicone polyols, fluorine-containing polyols and so on. 
     These polyoxyalkylene polyols may be produced by addition-polymerizing propylene oxide, butylene oxide or the like with said compound containing active hydrogen groups. 
     The polyester polyols include polycondensates of saturated or unsaturated fatty acids or anhydrides thereof with said polyhydric alcohols, said polyether polyols, said polyoxyalkylene polyols or the like. 
     The silicone polyols and fluorine-containing polyols include, among others, compounds containing a dimethylsiloxane or fluorocarbon unit in the backbone chain and hydroxyl groups at the terminals and/or in the side chain thereof. 
     When said other polyols are mixed with said polyether polyols, their proportions can be optionally chosen. 
     The organic polyisocyanates mentioned above include, among others, tolylene diisocyanate (TDI), diphenylmethane diisocyanate (p-MDI), liquid MDI, crude MDI, and other polyphenylpolymethyl polyisocyanates, hexamethylene diisocyanate (HDI), xylylene diisocyanate (XDI), isophorone diisocyanate (IPDI) and so on. 
     The water-soluble urethane prepolymers can be produced by various methods which are known per se. For example, they can be produced by reacting a polyether polyol or a mixture of such polyether polyol and one or more other polyols with an organic polyisocyanate at a temperature of about 30° to 120° C. for about 30 minutes to 48 hours. 
     The ratio of said polyether polyol or said mixture of said polyether polyol and other polyol or polyols to said organic polyisocyanate is preferably in the range of 1.1 through 2.0 in terms of NCO/active hydrogen group (molar ratio). 
     As the blocking agent used for blocking the free isocyanato groups of such water-soluble urethane prepolymer, there may be mentioned phenols such as phenol, butylphenol, chlorophenol, phenylphenol, etc.; oximes such as methyl ethyl ketoxime, cyclohexane oxime, acetoxime, etc., imidazoles such as imidazole, 2-methylimidazole, 2-ethylimidazole, 2-phenylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, etc., acid sodium sulfite, and so on. These compounds are particularly desirable in view of their compatibility with textile processes, safety, reactivity, and so on. 
     The water-soluble urethane prepolymer having blocked isocyanato groups can be produced by reacting a water-soluble urethane prepolymer with a blocking agent in the presence or absence of a catalyst such as a tertiary amine or a metal compound such as sodium methoxide at a temperature of about 30° to 100° C. 
     In order to ensure the proper viscosity and homogeniety of the reaction system, an inert solvent such as dioxane, methyl-cellosolve acetate, ethylcellosolve acetate, dimethylformamide or the like may be added to the reaction system. 
     The ratio of said blocking agent to said water-soluble urethane prepolymer is one to 1.5 molar equivalents based on the free terminal isocyanato groups of the water-soluble urethane prepolymer. 
     As such a water-soluble urethane prepolymer containing blocked isocyanato groups is heated, the blocking agent is cleaved to thereby regenerate the free isocyanato groups. 
     As a typical method for treating a textile product in accordance with the present invention, a cellulose fiber-containing fabric is treated with a resin bath containing as an essential ingredient said water-soluble urethane prepolymer having blocked isocyanato groups. 
     Thus, a cellulose fiber-containing textile product is immersed in a resin bath containing said water-soluble urethane prepolymer having blocked isocyanato groups, squeezed, dried, and heat-treated at an elevated temperature. 
     In this process, a catalyst that is commonly used in urethane prepolymer reaction is added. 
     In the resin ath employed in the practice of the present invention, there are incorporated the formaldehyde addition product or formaldehyde-containing thermosetting resin precondensate (inclusive of those mentioned hereinbefore) which is commonly used in resin finishes and the corresponding catalyst (e.g. zinc chloride, magnesium chloride, zinc nitrate or an organic amine). 
     In the resin bath, there may also be incorporated various additives which are commonly used in resin finishes, such as softeners, fluorescent whiteners, natural or synthetic sizes, and hygroscopic agents. 
     The cellulose fiber-containing textile product includes, among other, those made of natural cellulose materials such as cotton, linen, etc. regenerated celluloses such as rayon, cuprammonium rayon, etc.; cellulose derivatives rich in unsubstituted hydroxyl groups such as acetate rayon, etc., mixtures or blends of such various cellulosic fibers, mixtures or blends of such cellulosic fibers with synthetic fibers or animal fibers, etc., and includes staples, tows, silvers, yarns, woven fabrics, knitted fabrics, nonwoven fabrics and so on. 
     The cellulose-fiber containing textiles treated in accordance with the present invention have markedly improved properties, in terms of dry crease resistance, wet crease resistance, wash-and-wear property, etc., and the improvement in wet crease resistance is particularly remarkable. 
     Furthermore, the method of the present invention does not require a complicated series of processing steps and is easy to practice. 
     The following examples are intended to illustrate the invention in further detail. It should be understood that in the examples all percents and parts are by weight. 
    
    
     PRODUCTION EXAMPLE 
     To a water-soluble urethane prepolymer was added a solution of a blocking agent in an inert solvent at a temperature within the range mentioned hereinbefore, followed by addition of a catalyst. The reaction was carried out until the free isocyanato groups were no longer detected. Thereafter, the reaction mixture was diluted with water to give a clear water-soluble urethane prepolymer containing blocked isocyanato groups (active component 30%). The reactants and products are shown in Table 1. 
     EXAMPLE 1 
     A 40&#39;S cotton broad cloth was immersed in the resin bath indicated below, squeezed (squeezing rate 70%), dried in a hot air current at 110° C. for 3 minutes, and further heat-treated at 150° C. for 3 minutes. 
     The dry crease resistance, wet crease resistance, tensile strength, tear strength and wash-and-wear property of the resulting finished cloth were determined. 
     As a control example, a similar cloth was similarly treated with a resin bath of the otherwise same composition which lacked the water-soluble urethane prepolymer having blocked isocyanato groups. 
     The results are shown in Table 2. 
     
         ______________________________________Resin bath______________________________________A water-soluble urethane prepolymer                    10    partshaving blocked isocyanato groups(active component 30%)Catalyst: Elastolon catalys 32                    1     part(Daiichi Koyo Seiyaku, tradename)Dimethyloldihydroxyethyleneurea                    7     parts(active component 40%)Catalyst: magnesium chloride                    2     parts(active component 20%)Softner: polyethylene wax emulsion                    2     parts(active component 5%)Water                    78    parts______________________________________ 
    
     EXAMPLE 2 
     A 40&#39;S W cotton plain weave cloth was immersed in the resin bath indicated below, squeezed (squeezing rate 75%), dried in a hot air current at 110° C. (for 3 minutes, and further heat-treated at 150° C. for 3 minutes. 
     The dry crease resistance, wet crease resistance, tensile strength, tear strength and wash-and-wear property of the resulting finished cloth were determined. 
     As a control example, a similar cloth was similarly treated with a resin bath of the otherwise same composition which lacked the water-soluble urethane prepolymer having blocked isocyanato groups. 
     The results are shown in Table 3. 
     
         ______________________________________Resin bath______________________________________A water-soluble urethane prepolymer                     10    partshaving blocked isocyanato groups(effective component 30%)Catalyst: Elastolon catalyt 32                     1     part(Daiichi Koyo Seiyaku, tradename)Dialkoxymethyldihydroxyethyleneurea                     10    parts(active component 45%)Catalyst: zinc nitrate    3     parts(active component 15%)Polyethylene wax emulsion 2     parts(active component 15%)Water                     78    parts______________________________________ 
    
     EXAMPLE 3 
     A 40&#39;S W spun viscose rayon plain weave cloth was immersed in the resin bath indicated below, squeezed (squeezing rate 80%), dried in a hot air current at 100° C. for 2 minutes and further heat-treated at 160° C. for 2 minutes. 
     The dry crease resistance, wet crease resistance, tensile strength, tear strength and wash-and-wear property of the resulting finished cloth were determined. 
     As a control example, a similar cloth was similarly treated with a resin bath of the otherwise same composition which lacked the water-soluble urethane prepolymer having blocked isocyanato groups. 
     The results are shown in Table 4. 
     
         ______________________________________Resin bath______________________________________A water-soluble urethane prepolymer                    5      partshaving blocked isocyanato groups(active component 30%)Catalyst: Elastolon catalys 32                    0.5    part(Daiichi Koyo Seiyaku, tradename)Urea-formaldehyde precondensate                    20     parts(active component 30%)Catalyst: an organic amine                    2      parts(active component 35%)Water                    72.5   parts______________________________________ 
    
     
                                           TABLE 1__________________________________________________________________________ItemUrethane prepolymers containing isocyanato groupsPolyol                                     Isocyanato                                            RegeneratableActive   Total     Organic                   NCO/active   Ethylene                                      content                                            isocyanato                                                    Amount ofhydrogen alkylene          Molec-              polyiso-                   hydrogen                          Mol. wt. of                                oxide in                                      (%) of                                            content                                                    urethanecompound oxide ular              cyanate                   group  urethane                                urethane                                      urethane                                            of urethane                                                    prepolymerType    Type Type       (%)          weight              Type (mol. ratio)                          prepolymer                                prepolymer                                      prepolymer                                            prepolymer                                                    (parts)__________________________________________________________________________No. 1    Glycerin    PO 30 3000              HDI  2      3600  56.86 3.5   3.5     116.8    EO 70No. 2    Glycerin    PO 30 3000              HDI  1.5    8842  25.41 1.9   1.9     210    EO 70    Glycerin    PO 100          5000    Glycerin    PO 90 2000    EO 10No. 3    Tri- EO 100          1000              HDI  1.5    2333  28.28 4.5   4.5     283.5    methylol-    propaneDiethylene glycol          1000adipate__________________________________________________________________________             Item                          Blocking agent/free             Blocking agent                          isocyanato group                                    Inert solvent                                               Catalyst         Type             Type Amount (parts)                           (mol. ratio)                                    Type/amount (parts)                                               Type/amount__________________________________________________________________________                                               (parts)         No. 1             Phenol                  9.2     1.01      Dioxane:   Triethyl-                                    30         amine:                                               0.2         No. 2             p-Butyl-                  15.9    1.01      Dioxane:   Triethyl-             phenol                 100        amine:                                               0.4         No. 3             Methyl                  27.2    1.00      Methyl     --             ethyl                  ethyl             ketoxime               ketone:                                    60__________________________________________________________________________ PO: Propylene oxide EO: Ethylene oxide 
    
     
                                           TABLE 2__________________________________________________________________________ItemType of water- Crease resistancesoluble urethane          (degree)prepolymer contain-          Dry crease                 Wet crease                        Tensile                             Tear Wash-and-wearTest ing blocked          resistance                 resistance                        strength                             strength                                  propertyNo.  isocyanato groups          HL-0             HL-10                 HL-0                    HL-10                        (Kg) (g)  (grade)__________________________________________________________________________1-1  No. 1     272             268 281                    279 14.6 715  3.81-2  No. 2     268             267 282                    271 14.8 738  3.51-3  No. 3     270             264 280                    275 14.6 720  3.8Reference--        240             205 230                    198 15.1 735  2.8exampleBlank--        148             150 150                    159 21.3 980  1.2control(substratefabriconly)__________________________________________________________________________ Laundering conditions: according to JISL-0217-103 HL0, 0 laundering HL10, 10 laundering (drip dry method) Crease resistance: according to JISL-1096C (warp and filling) Tensile strength: according to JISL-1096A (filling direction) Tear strength: according to JISL-1096D (warp direction) Washand-wear property: according to AATCC124-1967T III B The above applies to the examples that follow. 
    
     
                                           TABLE 3__________________________________________________________________________ItemType of water- Crease resistancesoluble urethane          (degree)prepolymer contain-          Dry crease                 Wet crease                        Tensile                             Tear Wash-and-wearTest ing blocked          resistance                 resistance                        strength                             strength                                  propertyNo.  isocyanato groups          HL-0             HL-10                 HL-0                    HL-10                        (Kg) (g)  (grade)__________________________________________________________________________2-1  No. 1     260             256 281                    277 20.7 889  3.52-2  No. 2     263             251 278                    274 20.8 832  3.32-3  No. 3     265             259 282                    274 20.7 799  3.7Reference--        241             213 225                    198 21.4 785  2.1exampleBlank--        169             165 167                    170 28.5 801  1.5control(substratefabriconly)__________________________________________________________________________ 
    
     
                                           TABLE 4__________________________________________________________________________ItemType of water- Crease resistancesoluble urethane          (degree)prepolymer contain-          Dry crease                 Wet crease                        Tensile                             Tear Wash-and-wearTest ing blocked          resistance                 resistance                        strength                             strength                                  propertyNo.  isocyanato groups          HL-0             HL-10                 HL-0                    HL-10                        (Kg) (g)  (grade)__________________________________________________________________________3-1  No. 1     266             261 267                    262 20.9 1580 3.63-2  No. 2     260             252 278                    268 21.0 1605 3.53-3  No. 3     273             270 275                    261 19.9 1585 3.4Reference--        236             209 173                    168 20.0 1520 2.5exampleBlank--        210             205 161                    165 24.3 2218 1control(substratefabriconly)__________________________________________________________________________