CA1248709A - Process for improving polymer fiber properties and fibers produced thereby - Google Patents
Process for improving polymer fiber properties and fibers produced therebyInfo
- Publication number
- CA1248709A CA1248709A CA000430762A CA430762A CA1248709A CA 1248709 A CA1248709 A CA 1248709A CA 000430762 A CA000430762 A CA 000430762A CA 430762 A CA430762 A CA 430762A CA 1248709 A CA1248709 A CA 1248709A
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- Prior art keywords
- fibers
- monomer
- polymerization
- solution
- acid
- Prior art date
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Classifications
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- D—TEXTILES; PAPER
- D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
- D06M—TREATMENT, NOT PROVIDED FOR ELSEWHERE IN CLASS D06, OF FIBRES, THREADS, YARNS, FABRICS, FEATHERS OR FIBROUS GOODS MADE FROM SUCH MATERIALS
- D06M14/00—Graft polymerisation of monomers containing carbon-to-carbon unsaturated bonds on to fibres, threads, yarns, fabrics, or fibrous goods made from such materials
- D06M14/08—Graft polymerisation of monomers containing carbon-to-carbon unsaturated bonds on to fibres, threads, yarns, fabrics, or fibrous goods made from such materials on to materials of synthetic origin
- D06M14/12—Graft polymerisation of monomers containing carbon-to-carbon unsaturated bonds on to fibres, threads, yarns, fabrics, or fibrous goods made from such materials on to materials of synthetic origin of macromolecular compounds obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds
- D06M14/14—Polyesters
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- D—TEXTILES; PAPER
- D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
- D06M—TREATMENT, NOT PROVIDED FOR ELSEWHERE IN CLASS D06, OF FIBRES, THREADS, YARNS, FABRICS, FEATHERS OR FIBROUS GOODS MADE FROM SUCH MATERIALS
- D06M14/00—Graft polymerisation of monomers containing carbon-to-carbon unsaturated bonds on to fibres, threads, yarns, fabrics, or fibrous goods made from such materials
- D06M14/08—Graft polymerisation of monomers containing carbon-to-carbon unsaturated bonds on to fibres, threads, yarns, fabrics, or fibrous goods made from such materials on to materials of synthetic origin
- D06M14/10—Graft polymerisation of monomers containing carbon-to-carbon unsaturated bonds on to fibres, threads, yarns, fabrics, or fibrous goods made from such materials on to materials of synthetic origin of macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
Abstract
PROCESS FOR IMPROVING POLYMER FIBER
PROPERTIES AND FIBERS PRODUCED THEREBY
Abstract of the Disclosure A method is provided for treating polyester, and acrylic polymer fibers or fibrous structures made thereof to permanently improve the antistatic, hygroscopic, dye receptive, soil release, inter-fiber adhesion and bonding properties of the fibers and structures. The method involves contacting the fibers with an aqueous solution containing at least one unsaturated monomer and having an acid pH and a temperature between about 60°C and about 100°C. After allowing the solution to uniformly disperse among the fibers, so that the monomer intimately contacts the fiber surfaces, polymerization of the monomer on the fiber surfaces is initiated by a polymerization initiator for the monomer, and the polymerization is continued for a sufficient time to allow substantial graft polymerization of the monomer on the fibers to modify the surface proper-ties of the fibers. The fibers are preferably scoured prior to the treatment process, and after polymerization the fibers are rinsed to remove acid and excess homopolymer prior to dyeing and/or further processing of the fibers.
The fibers may be in the form of knitted, woven or non-woven fabrics, and may include mixtures of fibers such as acrylic yarns and nylon filaments or polyester and cotton staple fiber blends.
PROPERTIES AND FIBERS PRODUCED THEREBY
Abstract of the Disclosure A method is provided for treating polyester, and acrylic polymer fibers or fibrous structures made thereof to permanently improve the antistatic, hygroscopic, dye receptive, soil release, inter-fiber adhesion and bonding properties of the fibers and structures. The method involves contacting the fibers with an aqueous solution containing at least one unsaturated monomer and having an acid pH and a temperature between about 60°C and about 100°C. After allowing the solution to uniformly disperse among the fibers, so that the monomer intimately contacts the fiber surfaces, polymerization of the monomer on the fiber surfaces is initiated by a polymerization initiator for the monomer, and the polymerization is continued for a sufficient time to allow substantial graft polymerization of the monomer on the fibers to modify the surface proper-ties of the fibers. The fibers are preferably scoured prior to the treatment process, and after polymerization the fibers are rinsed to remove acid and excess homopolymer prior to dyeing and/or further processing of the fibers.
The fibers may be in the form of knitted, woven or non-woven fabrics, and may include mixtures of fibers such as acrylic yarns and nylon filaments or polyester and cotton staple fiber blends.
Description
PROCESS FOR IMPROVING POLYMER FIBER
- PKOPERTIES_AND FIBERS PRODUCED THEREBY
Field of the Invention The present invention relates to the treatment of polymer fibers to permanently and substantially improve their hygroscopic, antistatic, dye recep~ive and soil re-lease properties, as well as altering the hand of such fibers. More particularly, the invention relates to the treatment of polyester and acrylic fibers to improve thier surface propertiesO
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Background of the Invention With the advent of technology to produce synthetic fibers that serve mankind not only by being more economical and stronger than natural fibers, but also by freeing up much needed agricultural land that heretofore had been needed to grow vast quantities of natural fibers, came a quest for a process that would impart to these synthetic fibers the same beneficial qualities possessed by natural fibers. The major quality that synthetic fibers lack, the one attribute that would make them cool and comfortable like the natural fibers, is the ability to substantially absorb moisture.
Throughout this application the terms "absorb" and "absorption" will be used to refer generally to ~he hygro-scopic properties of the fibers and fabrics made therefrom.
However, it will be understood that these terms refer to related hygroscopic properties such as adsorption, moisture transport, wicking, wettability, etc. Thus, although the term 'ladsorption" may be more appropriate for re~erring to the attraction of water to the outer surfaces of fibers per se, and the term "absorption" may be more appropriate for referring ~o the dispersal of moisture in the interstices between the fibers of a fabric, the term 'iabsorption" will be used for convenience to refer to both phenomena.
The present invention satisfies this much sought after quest and provides to synthetic fibers qualities once attributable only to natural fibers such as signifi-cant water absorbency, superior dye receptivity and anti-static qualities. At the same time, the present invention allows for the production of synthetic fibers that have superior soi~ release qualities.
It has been known in the prior art to attempt to graft-polymerize water-soluble monomers such as acrylic acid, acrylamide and N~N'-methylene-bis-acrylamide (NBA) onto fibers to impart antistatic and water absorption properties to the fibers. However, such attempts at graft polymerization have been problematic due to the inability , ;
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to obtain substantial or even any graft polymerization, difficulties in controlling the process conditions and the tendency to form large amounts of homopolymers. Excess homopolymers adhere to the inner walls of the processing equipment thus causing both a time and labor-consuming clean-up job. Also, disposal of the residue solution containing a large amount of homopolymers is a source of industrial pollution. Fabrics thus treated in an environ-ment of excessive homopolymers have their surfaces coated with a thick homopolymer layer which imparts moisture absorption and antistatic properties to the fibers.
Unfortunately, these properties are not permanent and are lost within about ten washings. Furthermore, exces-sive homopolymers tend to cause blotching on treated fab-rics which interferes with acceptable commercial dyeing and results in inerior treated fabrics.
In an alternative polymerization process that com-prises impregnating fibers with a solution containing a monomer and a polymerization initiator, such as peroxide or persulfate, and heating them, it takes a long period of time to start and advance the polymerization reaction;
moreover, the polymers that adhere to fibers are removed quite easily by washing so that their antistatic and moisture-absorption properties can no longer be retained.
Still another process involves applying a water-soluble vinyl monomer together wi~h a polymerization initiator to fibrous structures and heating them in a non-solvent of the monomer, such as hydrocarbons or the like. Such process has problems of industrial hygiene and workability including solvent recovery.
UOS. Patent 3,313,591 describes a process of graft polymerizing ethylenically unsaturated monomers to poly-carbonamides to improve various properties of the polymer structure. According to that process, polymerization initiators are eliminated and heat is used as the sole ~raft initiator for producing the free radicals necessary for graft polymerization.
~`1 .. ~ ~ill. _ ; f A more recent attempt to cure the deficiency in the prior art is disclosed in U.S. Patent ~,135,877 to Aikawa et al. This patent discloses a process of graft polymerizing certain selected vinyl monomers to poly-amides or fiber structures. According to the process described in that patent, polymerization initiators are eliminated and heat is used as in the Tanner method of U.S. Patent 3,313,591, but the aqueous treating solution also contains an acid.
Other patents disclosing the gra~t polymerization of monomers to polyamides and other polymer structures include Unites States Patents 3,097,185; 3,099,631;
3,252,880 and 3,278,639. However, the methods of these patents involve the use of ionizing radiation in the formation of a polymer melt in order to effect graft polymerization.
While many of these processes of the prior art re-sult in improved antistatic, hygroscopic and dye receptive properties in the polymer, they have not been entirely successful commercially due to the difficulties in ob-taining permanent and substantial results and other pro-cessing difficulties due to excessive formation of homo-polymers which are difficult to remove from the final product and process equipment. Furthermore, some prior art methods require high concentrations of monomer, rather than low concentrations of monomer; and other prior art methods require long periods of time.
The possibility of improving such properties of synthetic fabrics in general, includin~ but not limited to polyamides, polyesters and acrylics, is important since many of ~hese fabrics exhibit characteristically undesirable properties such as static cling, poor water absorbency and poor dye recep~ivity. Hence, the commercial acceptance of many synthetic fabrics has been severely limited. Hereto-fore, I am aware of no commercially successful process which has resulted in a treated fiber having substantially improved antis~atic, hygroscopic and dye receptive proper-ties which are permanent and can withstand repeatedwashings.
Canadian patent application S.N. 430,740 discloses a method of treating polymer fibers c~ntaining active hydro-gen atoms, particularly nylon, which are not naturally ab-sorbent and are subject to static electricity problems. Ihe methcd of that inven-tion is also beneficial to enhance the properties of absor-bent fibers such as co~ton. Treating a blend consisting of cotton and synthetic fibers in accordance with ~hat method may allow the use of less cotton in the blend to achieve a comparable fabric. However, that method was not previously thought to be applicable to polyester or acrylic fibers.
Summary of the Invention According to the present invention, polymer fibers or fibrous structures made thereof (hereinafter simply referred to as ~polymer fibers") comprising polyester or acrylic polymers are treated with a heated acidic solution of at least one unsaturated monomer, followed by polymer-ization of the monomer with a polymerization initiator in order to modify the surface characteristics of the polymer fibers. The treatment process comprises essentially three steps: (1) contacting the fibers with an aqueous solu tion having a pH below 7 and a temperat~re between about 60C nd about 100C and containing at least one unsatur ated monomer. The solution is preferably agitatèd or forced to flow among the fibers for a sufficient time to allow uniform dispersal and intimate contact of the mono-mer with the fiber surfaces; (2) thereafter initiating polymerization of the monomer on the fiber surfaces using a polymerization initiator, such as a persulfate or per-oxide compound; and (3) continuing the polymerization for a sufficient time to allow substantial graft polymeri-zation of the monomer on the fiber surfaces to modify the surface characteristics of the polymer ibers.
The fibers are preferably immersed in the ~reating solution, usually in the form of a knitted, woven or non-7~
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wov~n fabric, and many variations are possible in the orderof addition of the various components to the treating solu-tion. A preferred monomer for use in the invention is N,NI-methylene-bis-acrylamide. The pH of the solution may be adjusted by addition of an acid or by use of an acid mon-omer. The treatment is preferably carried out at low concentrations of monomer and polymerization initiator and for short periods of time so as to avoid as much as possible substantial homopolymerization of the monomer.
The fibers are preferably scoured prior to the treat-ment process to clean the fibers and remove surface chemi-cals which may interfere with the graft polymerization of the monomer on the fiber surfaces. Dyeing of the fibers is preferably carried out after the treatment process and after rinsing the fibers to remove acid and excess homo-polymers which would otherwise interfere with the dyeing.
The fibers resulting from the process of the pre-sent invention have substantially improved water absorbency, dye receptivity, antistatic, soil release and inter-fiber adhesion and bonding properties and fabric hand. The fibers so treated by the present invention will retain their enhanced properties even when subject to many vigorous washings.
Detailed Description of the Invention Polymer fibers to which the present invention is directed include conventional polyester, and acrylic polymers, and combinations of these polymer fibers with other synthetic and/or natural fibers. Nonlimiting exam-ples of natural fibers which may be combined with the polyester, and acrylic polymer fibers include wool, cotton and silk. Non-limiting examples of synthetic polymer fibers which may be combined with the polyester, and/or acrylic fibers include nylon, acetate and cellulosic fibers, e.g., rayon.
The subject invention concerns the treating of polymer fibers per se and fibrous structures made thereof.
The term "fibrous structures" includes continuous fila-ments, multifilament threads, ba~ts, st~ple fibers, woven ' 7q~
or knitted fabrics and non-woven fabrics, and the like composed of at least one kind of the fibers mentioned above. As used herein, the term "polymer fibers" will be understood to include fibrous structures such as the above and others. Wherever the present disclosure refers to fiber surfaces or in~imate contact of the monomer with fiber surfaces or like expressions, it will be understood that the individual fibers o~ filaments are being referred to, such that contact and attachment of the monomer and graft polymer is with the surfaces of individual filaments of a multifilament thread or bundle, for example.
Polyester is ~he generic name for a fiber manu-factured either as a staple fiber or continuous filament in which the fiber-forming substance is any long chain synthetic polymer composed of at least 85% by weight of an ester of a dihydric alcohol and tereph~halic acid. The most common polyester fibers available in the United States are made of polyethylene terephthalate, and are available for example under the trademarks ~DACRON'I of E~Io duPont de Nemours & Co. and "FORTREL" of ICI United States, Inc. and Celanese Chemical Co. Polyester fibers are available as filament yarn, staple fibers and fiber to~s and are often combined with other fibers such as cotton and wool~ For example, much clothing is made from yarns which are a blend of polyester and cotton staple fibers. Fabrics made from such polyester fibers and fiber combinations are commonly used for making many types of outerwear, including dresses, suits, shirts, etc.
Polyesters form excellent fabrics and can he produced very cheaply on a mass production basis, but polyesters suffer from many drawbacks. Polyesters lack the ability bo si~nificantly absorb water and are subject bo s~atic electricity prbbl~ms.
By treating polyester fibers according to the process of the present invention, a most useful fabric is formed which has very good water absorbing, dye receptive and antistatic properties which are retained after many wa ~ings.
Acrylic is the generic name for fibers in which the fiber-forming substance is any long chain synthetic poly-mer composed of at least 85% by weight of acrylonitrile units (-CH2CH(CN)-). Such fibers are available in various types of staple fibers and tow, and are commercially avail-able under the trademarks "ORLON" of E. I. duPont de Nemours, & Co. and "CRESLAN" of American Cyanamid Co, for example.
Acrylic fibers for wearing apparel are usually blended with other fibers such as wool, or formed into yarns which are then knitted with other stron~er synthetic fibers or fila~
ments, such as nylon.
As with polyesters and other synthetic fibers, acry-lics lack the ability to significantly absorb water and are subject to static. By treating acrylic fibers according to the process of the present invention, fabrics are obtained which have excellent water-absorbing, dye receptive and anti-static properties which are retained after many wash-ings. As indicated in Canadian patent application S.N.
430,740, such surface characteristics are also improved in the other synthetic and natural fibers which may be combined with acrylics and/or polyesters.
The process of the present invention differ~ from those of the prior art in that polymerization of the mono-mer to be graft polymerized onto the polymer fibers is de-layed until there has been intimate con,tact of the monomer with the surface of the polymer fiber. Thus, while appli-cant does not wish to be bound by any particular theory or mechanism of reaction, it is believed that the-unsaturated monomer first attaches to ~he polymer chain on a molecule by molecule basis in the presence of acid and heat~ There-after, whe~ the polymerization is initiated by addition or activation of a polymerization initiator9 the monomer begins to polymerize so that there is chain addition uf monomer to the single monomer additions initi~lly graf~ed onto the polymer fibers. If significant homopolymerization of the monomer takes place prior to attachment of the mono-me~ to the fibers, most of it will simply be washed off the fibers so that there will be no significant permanent improvement in the surface properties of the fibers.
Accordingly, the first step of the method according to the present invention comprises the formation of an aqueous treating solution with dissolved monomer havin~ an acidic pH ~i.e. below about 7) and heated to a temperature of about 60C to about 100C and preferably in the range of about 70C to 90C. While temperatures above 100C are possible, they make processing more difficult and may make subsequent polymerization difficult to control.
Similarly, temperatures below about 60C may be possible but would usually result in a processing takin~ too long a time to be feasible commercially.
It is not necessary that the temperature be constant throughout the first step or throughout the process. For example, the treating solution could be formed at ahout 70C, or such temperature as will allow ready dissolving of the monomer and/or acid in the solution, and then the temperature could be raised to the desired level for poly-merization just prior to initiation of polymerization. The temperature would then be maintained at whatever level is necessary to obtain the optimum speed and degree of poly-merization. For example, the temperature could be raised to about 85C or 90C at the end of the first step and maintained at that temperature for the remainder of the treatment process.
The acid, monomer, fabric and heat may be combined in the first step of the treatment process in virtually any desired order, so long as all four of these elements are present prior to initiatin~ polymerization for a suf-ficient time to allow uniform dispersal and intimate con-tact of the monomer with the fiber surfaces. For exampler the order of combination in the first step may be any of the following: (1) addition of acid and monomer ~o water, addition of a delayed initiator (to be ac~ivated in the second step), and heating to ~he desired temperature; (2~
addition of monomer and a delayed initiator to water, addi-r tion of acid and heating to the desired temperature; (3)addition of monomer to water, heating to desired tempera-ture and addition of acid and delayed initiator; or (4) addition of acid monomer to water, addition of delayed initiator and heating to desired temperature. Other pos-sible orders of carrying out the first step will be evident to those skilled in the art based on the present disclo-sure.
Such uniform dispersal and intimate contact may be assisted by various forms of agitation of flow of the aqueous treating solution around and between the fiber surfaces. For example, in the case of the trea~ment of fibers in the form of fabric piece goods, agitation may be accomplished by the paddles in a conventional paddle tub.
Alternatively, for ~ibers in the form o~ fabrics which are processed in the form of rolls on a beam, the aqueous treating solution may be circulated around and through the beam by conventional pressure means.
The time necessary for attaining uniform dispersal and intimate conta~ will va y with the particular method o~ contacting the fibers with the aqueous solution. Al-though it is possible that the aqueous solution could be contacted with the fibers by spraying, padding, dipping or other means, it is most preferable to immerse the fibers in a bath formed by the aqueous solution. Using such immer-sion techniques, relatively short periods of time are necessary before polymerization may begin. For exampley about 10 minutes is usually suficient with adequate agi-tation or circulation of the aqueous solution.
After uniform dispersal and intimate contact has been achieved, polymerization of ~he monomer on the fibers may be commenced with the use of a suitable polymerization ini-tiator such as peroxide or persulfate compounds which are known in the art. The particular initiator selected wili depend upon the particular polymer fiber, the particular monomer used and the speed or other conditions of the poly-merization desired. If desired, the initiator may be a~d-ed during the first step so long as it is not activateduntil uniform dispersal and in~imate contact of the mono-mer with the fiber surfaces are acheived. The initiation of polymerization may then be carried out, such as by raising the temperature, changing the pH or changing some other condition which will activate the initiator.
Finally, the polymerization is allowed to continue until there has been substantial graft polymerization of the monomer on the polymer fibers to modify the surface properties of the fibers. Generally, a rather low degree of polymerization is desireable, since excessive poly-merization will result in large amounts of homopolymer in the fibers and in the pro~ess equipment, which must be cleaned and washed out after comple~ion of the process.
Therefore, it is preferable to avoid polymerization which significantly clouds the treating solution, and such small polymers as will remain in solution are preferred.
To this end, it is preferable to carry out the pro-cess of the present invention using very low concentrations of monomer, such as in the range of about 0.01 to about 1.0 weight percent of the total solution and preferably about 0.02 to 0.5 weight percent of the solution. Such low con-centrations allow easy control of ~he polymerization re-action so tha-t a relatively clear solution is maintained throughout the process, and the processing equipment and fibers treated may be easily cleaned and washed out.
Although applicant has not been able to accurately measure the exact amount of graft polymerization added onto the polymer fibers, it appears that optimum pro~
cessing according to the present invention results in the permanent add-on of about 0.1 weight percent or less of graft polymer based upon the weight of the polymer ~iber.
While the process of the present invention may be used at any o~ a number of stages during ~he usual pro-cessing of polymer fibers or fabrics or other s~ructures made from such fibers, it has been found pre~erable to use ~the process before the dyeing of the fibers or before 37~
there is any treatment of the fibers which would result in encapsulation or coating of the fiber surface. Thus, it is usual practice to encapsulate or "lock on" the dye or other fiber treatment chemicals, and such coatings will often interfere with the addition of the monomer to the polymer fiber. To the extent that there would still be addition, this would be gradually washed off through many washings.
Therefore, it is preferable that the fibers be scoured (e.g. washed with detergent) and rinsed prior to carrying out the treatment process of the present invention in order to remove dirt and other chemicals which may be present on the fibers. The process may then be carried out befcre dyeing or even in the dye bath but before the after treat-ment to set the dye. However, it is preferable to drain the treating solution and rinse the fibers before dyeing, in order to remove acid and excess homopolymer, which may interfere with reaction of the dye with the dye sites on the surface of the polymer fibers.
Whereas many of the teachings of the prior art such as Aikawa and Tanner involved the treating of fibers in the absence of polymerization initiators to avoid homo~
polymerization, the presen~ invention employs polymeriza~
tion initiators. Polymerization initiators are generally of four basic types, namely, peroxides, persulfides, acids and ceric compounds.
Non-limiting examples of polymerization initiators that may possibly be utilized in this invention inalude inorganic peroxides, e.g., hydrogen peroxide, barium perox-ide, magnesium peroxide, etc., and the various organiG
peroxy compounds illustrative examples of which ar@ the dialkyl peroxides, e.g., diethyl peroxide, dipropyl perox-ide, dilauryl peroxide, dioleyl peroxide, dis~earyl perox-ide, di-(tert.-butyl) peroxide and di-(tert.-amyl) peroxide, such peroxides often being designated as e~hyl, propyl, lauryl, oleyl, ~tearyl, tert.-butyl and tert.-amyl per-oxides; the alkyl hydrogen peroxides, e.g~ r tertO-butyl .
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~ r r hydrogen peroxide (tert.-butyl hydroperoxide), tert.-amyl hydrogen peroxide (tert.-amyl hydroperoxide), etc.; sym-metrical diacyl peroxides, for instance peroxides which commonly are known under such names as acetyl peroxide, propionyl peroxide, lauroyl peroxide, stearoyl peroxide, malonyl peroxide, succinyl peroxide, phthaloyl peroxide, benzoyl peroxide, etc.; fatty oil acid peroxides, e.g., coconut oil acid peroxides, etc.; unsymmetrical or mixed diacyl peroxides, e.g., acetyl benzoyl peroxide, pro-pionyl benzoyl peroxide, etc.; terpene oxides, e.g., ascaridole, etc.; and salts of inor~anic peracids, e.g., ammonium persulfate and potassium persulfate.
When fibers are treated according to this invention, the reaction ~ay also be initiated by ceric ions, for example, in the form of ceric salts such as ceric nitrate, ceric sulfate, ceric ammonium nitrate, ceric ammonium sulfate, ceric ammonium pyrophosphate, ceric iodate, and the like.
Non-limiting examples of suitable acids for use in the present invention include hydrochloric, phosphoric, sulfuric, nitric, acetic, formic, oxalic, tartaric, mono chloroacetic, dichloroacetic, trichloroacetic and similar acids. Formic and hydrochloric acid have been found to be particularly suitable in carryiny out the present inven-tion. It is possible that an acid can function as both a catalyst and initiator, e.~., formic acid.
Non-limiting examples of unsaturated types o~ mono-mers that may possibly be utilized in this invention in-clude N,N'methylene-bis-acrylamide (C~2(NHCOCH:CH2)2), N,N'-(1,2 dihyroxyethylene)-bis-acrylamide, acrylamide, acrylic acid, 2-propyn-1-ol, crotonic acid, tetraethylene glycol, styrene, alpha-methyl styrene, l,l-diphenyl ethy lene, alpha-vinyl naphthalene, vinylpyridine, 2-chloro-2j3-butadiene, methacrylic acid, methacrylamide, N methylol-acrylamidel N-methyl-N-vinyl ~ormamide, N-vinyl p~rroli-done, 3-, ~- or 5-methyl-N-vinyl pyrrolidone, vinyl o~y-ethylformamide, methyl acrylate, ethyl acrylate, octyl 3~
methyl methacrylate, vinylacrylate, acrylonitrile, meth-acrylonitrile, acrylyl chloride, vinyl methyl ketone, methallylalcohol, acrolein, methacrolein, vinyl acetate, p-vinyl phenyl acetate, methylmethacrylate, vinyl chloride, vinylidene chloride, p-chlorostyrene, 2,5-dichlorostyrene, 1,1,7-trihydro-perfluoroheptyl acrylate, methyl alpha-chloroacrylate, acrylyl cyanide, styrene sulfonic acid, salts and esters of styrene sulfonic acid and glycidyl methacrylate. The preferred monomers are N,N'-methylene-bis-acrylamide (NBA) and N,N'(1,2 dihydroxyethylene)-bis-acrylamide.
A monomer may function as an acid. NBA, for example, is slightly acidic in aqueous solution. It is also pos-sible to use specially modifled monomer which can provide special characteristics to the fibers, or fabrics made therefrom, such as crease sotness, lubricity (e.g. by in-cluding silicon groups on the monomer), adhesion, optical brigh~ness, anti-bacterial, anti-fungal or anti-mildew properties, etc.
In a preferred embodiment of this invention with the monomer utilized selected from the group consisting of NBA and N,N'(1,2 dihyroxyethylene)-bis-acrylamide, the polymerization step of the process is conducted for a period of time between about 0u5 minu~es and about 2 hours, preferably between about l.0 minute and about 30 minutes.
The amount of initiator in the treating solution is between about lX10-4 weight percent and 5.0 weight percent.
The particular concentrations of the monomer, acid and the initiator in the treating solution will vary wide-ly depending upon such fac~ors as the nature of the par-ticular monomer, acid and initiator, the time and temper-ature of the treatment, and the nature and form of the fiber being treated. While certain concentrations may be fairly essential for a particular monomer, acid and initi-ator under a given set of treatment conditions, applicant cannot give general ranges which would apply to all mono-mers, acids and initiators under all conditionst but those of ordinary skill in the ar~ will be able to optimize the concentrations by routine experimentation on the basis of the present disclosure.
Attaining the desired degree of treatment according to this invention would depend on the strength of the initiator and the concentration of the monomer and acid.
Thus, for example, a strong initiator, one that is inher-ently strong and/or having a high concentration of initi-ator, would require a lower monomer concentration. Con-versely, a weak initiator, one that is inherently-weak and/or having a low concentration of initiator, would require a higher monomer concentration. In the latter case, the treatment according to this invention can be controlled by draining the initiator containing solution from the fabric once the desired extent of polymerization has been achieved.
After polymerization begins, such polymerization being a function of the concentration and type of the acidr the unsatured monomer, fabric, initiator and the speed and type of the equipment being used, the fibers are allowed to remain in solution at the required temperature long enough to assure that uniform graft polymerization ("substantial polymerization") has occurred, such time usually not exceeding 30 minutes. The fibers can then be rinsed to neutralize the pH and remove excess homopoly-mers, if any.-The invention will now be described in greater de-tail by reference to the following specific, non-limiting examples:
Examples I
Athletic socks made of 75% acrylic ~ORLON) yarns and 25% nylon filaments were treated in a paddle-type dye tub containing 150 liters of water. Fity ml of 33% HCl and 50 ml of about 88% formic acid were added to water heated to 160F (71C~, and 56 grains of MBA were then dissolved in the wa~er. Less than one pound of acrylic athletic socks was immersed in the solution, and the ~emperature was rapidly raised to 185F (85C) and held there for 10 minutes~
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Twenty-five grans of potassium persulfate was added, and three minutes after the addition a milky precipi~ate ap-peared. Ten minutes after the addition of persulfate, the tub was drained and the socks were rinsed wi~h fresh wa~er.
Example II
The process ~f Example I was repeated with less than a pound of single knit fabric made of textured DACRON poly-ester (150 denier, 34 filament).
Testing Of Sam~les I and II
Polyester and acrylic samples processed according to Examples I and II were put through fifty home launderings with household detergent. Each set of ten wash cycles consisted of seven normal cycles with 30 grams of "Fab"
home laundry detergent in a 10 pound capacity "Kenmore"
home washer set on warm water wash, followed by three normal cycles set on warm water with no detergent.
Vertical wicking of samples was tested after drying after each set of ten wash cycles as follsws: Samples were cut at different times and vertical wicking was tested by cutting a strip of fabric, suspending one end in water, and measuring distance wicked above the surface. Polyester readings were made at two minutPs, and acrylic rea~ings were made at five minutes. Controls were untreated acrylic and polyester. The result~ are ~abulated in Tables I and II below.
POLYESTER VERTICAL WICXING
WASHING CONTROL TREATED
CYCLES ~cm) (çm) 0 4.S
0 4.2 0 4.5 0 5.5 *Trade mark 3~
TABLE II
_ .. . .. _ ACRYLIC VERTICAL WICKING
WASHING CONTROL TREATED
CYCLES (cm) ~cm) 3.5 10.~
3.2 ~ 10.5 3.6 10.2 3.4 10.0 3.5 9.0 3.5 9.1 In addition to the above-demonstrated hygroscopic properties, the fabrics treated in Examples I and II had excellent hand and feel characteristics, improved dyeabil-ity, good antistatic properties and generally improved surface properties.
The present invention may be embodied in other spe-cific forms wi~hout departing from the spirit or essential attributes ~hereof and, accordingly, reference should be made to the appended claims, rather than to the foregoing specification, as indicating the scope of the invention.
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- PKOPERTIES_AND FIBERS PRODUCED THEREBY
Field of the Invention The present invention relates to the treatment of polymer fibers to permanently and substantially improve their hygroscopic, antistatic, dye recep~ive and soil re-lease properties, as well as altering the hand of such fibers. More particularly, the invention relates to the treatment of polyester and acrylic fibers to improve thier surface propertiesO
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Background of the Invention With the advent of technology to produce synthetic fibers that serve mankind not only by being more economical and stronger than natural fibers, but also by freeing up much needed agricultural land that heretofore had been needed to grow vast quantities of natural fibers, came a quest for a process that would impart to these synthetic fibers the same beneficial qualities possessed by natural fibers. The major quality that synthetic fibers lack, the one attribute that would make them cool and comfortable like the natural fibers, is the ability to substantially absorb moisture.
Throughout this application the terms "absorb" and "absorption" will be used to refer generally to ~he hygro-scopic properties of the fibers and fabrics made therefrom.
However, it will be understood that these terms refer to related hygroscopic properties such as adsorption, moisture transport, wicking, wettability, etc. Thus, although the term 'ladsorption" may be more appropriate for re~erring to the attraction of water to the outer surfaces of fibers per se, and the term "absorption" may be more appropriate for referring ~o the dispersal of moisture in the interstices between the fibers of a fabric, the term 'iabsorption" will be used for convenience to refer to both phenomena.
The present invention satisfies this much sought after quest and provides to synthetic fibers qualities once attributable only to natural fibers such as signifi-cant water absorbency, superior dye receptivity and anti-static qualities. At the same time, the present invention allows for the production of synthetic fibers that have superior soi~ release qualities.
It has been known in the prior art to attempt to graft-polymerize water-soluble monomers such as acrylic acid, acrylamide and N~N'-methylene-bis-acrylamide (NBA) onto fibers to impart antistatic and water absorption properties to the fibers. However, such attempts at graft polymerization have been problematic due to the inability , ;
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to obtain substantial or even any graft polymerization, difficulties in controlling the process conditions and the tendency to form large amounts of homopolymers. Excess homopolymers adhere to the inner walls of the processing equipment thus causing both a time and labor-consuming clean-up job. Also, disposal of the residue solution containing a large amount of homopolymers is a source of industrial pollution. Fabrics thus treated in an environ-ment of excessive homopolymers have their surfaces coated with a thick homopolymer layer which imparts moisture absorption and antistatic properties to the fibers.
Unfortunately, these properties are not permanent and are lost within about ten washings. Furthermore, exces-sive homopolymers tend to cause blotching on treated fab-rics which interferes with acceptable commercial dyeing and results in inerior treated fabrics.
In an alternative polymerization process that com-prises impregnating fibers with a solution containing a monomer and a polymerization initiator, such as peroxide or persulfate, and heating them, it takes a long period of time to start and advance the polymerization reaction;
moreover, the polymers that adhere to fibers are removed quite easily by washing so that their antistatic and moisture-absorption properties can no longer be retained.
Still another process involves applying a water-soluble vinyl monomer together wi~h a polymerization initiator to fibrous structures and heating them in a non-solvent of the monomer, such as hydrocarbons or the like. Such process has problems of industrial hygiene and workability including solvent recovery.
UOS. Patent 3,313,591 describes a process of graft polymerizing ethylenically unsaturated monomers to poly-carbonamides to improve various properties of the polymer structure. According to that process, polymerization initiators are eliminated and heat is used as the sole ~raft initiator for producing the free radicals necessary for graft polymerization.
~`1 .. ~ ~ill. _ ; f A more recent attempt to cure the deficiency in the prior art is disclosed in U.S. Patent ~,135,877 to Aikawa et al. This patent discloses a process of graft polymerizing certain selected vinyl monomers to poly-amides or fiber structures. According to the process described in that patent, polymerization initiators are eliminated and heat is used as in the Tanner method of U.S. Patent 3,313,591, but the aqueous treating solution also contains an acid.
Other patents disclosing the gra~t polymerization of monomers to polyamides and other polymer structures include Unites States Patents 3,097,185; 3,099,631;
3,252,880 and 3,278,639. However, the methods of these patents involve the use of ionizing radiation in the formation of a polymer melt in order to effect graft polymerization.
While many of these processes of the prior art re-sult in improved antistatic, hygroscopic and dye receptive properties in the polymer, they have not been entirely successful commercially due to the difficulties in ob-taining permanent and substantial results and other pro-cessing difficulties due to excessive formation of homo-polymers which are difficult to remove from the final product and process equipment. Furthermore, some prior art methods require high concentrations of monomer, rather than low concentrations of monomer; and other prior art methods require long periods of time.
The possibility of improving such properties of synthetic fabrics in general, includin~ but not limited to polyamides, polyesters and acrylics, is important since many of ~hese fabrics exhibit characteristically undesirable properties such as static cling, poor water absorbency and poor dye recep~ivity. Hence, the commercial acceptance of many synthetic fabrics has been severely limited. Hereto-fore, I am aware of no commercially successful process which has resulted in a treated fiber having substantially improved antis~atic, hygroscopic and dye receptive proper-ties which are permanent and can withstand repeatedwashings.
Canadian patent application S.N. 430,740 discloses a method of treating polymer fibers c~ntaining active hydro-gen atoms, particularly nylon, which are not naturally ab-sorbent and are subject to static electricity problems. Ihe methcd of that inven-tion is also beneficial to enhance the properties of absor-bent fibers such as co~ton. Treating a blend consisting of cotton and synthetic fibers in accordance with ~hat method may allow the use of less cotton in the blend to achieve a comparable fabric. However, that method was not previously thought to be applicable to polyester or acrylic fibers.
Summary of the Invention According to the present invention, polymer fibers or fibrous structures made thereof (hereinafter simply referred to as ~polymer fibers") comprising polyester or acrylic polymers are treated with a heated acidic solution of at least one unsaturated monomer, followed by polymer-ization of the monomer with a polymerization initiator in order to modify the surface characteristics of the polymer fibers. The treatment process comprises essentially three steps: (1) contacting the fibers with an aqueous solu tion having a pH below 7 and a temperat~re between about 60C nd about 100C and containing at least one unsatur ated monomer. The solution is preferably agitatèd or forced to flow among the fibers for a sufficient time to allow uniform dispersal and intimate contact of the mono-mer with the fiber surfaces; (2) thereafter initiating polymerization of the monomer on the fiber surfaces using a polymerization initiator, such as a persulfate or per-oxide compound; and (3) continuing the polymerization for a sufficient time to allow substantial graft polymeri-zation of the monomer on the fiber surfaces to modify the surface characteristics of the polymer ibers.
The fibers are preferably immersed in the ~reating solution, usually in the form of a knitted, woven or non-7~
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wov~n fabric, and many variations are possible in the orderof addition of the various components to the treating solu-tion. A preferred monomer for use in the invention is N,NI-methylene-bis-acrylamide. The pH of the solution may be adjusted by addition of an acid or by use of an acid mon-omer. The treatment is preferably carried out at low concentrations of monomer and polymerization initiator and for short periods of time so as to avoid as much as possible substantial homopolymerization of the monomer.
The fibers are preferably scoured prior to the treat-ment process to clean the fibers and remove surface chemi-cals which may interfere with the graft polymerization of the monomer on the fiber surfaces. Dyeing of the fibers is preferably carried out after the treatment process and after rinsing the fibers to remove acid and excess homo-polymers which would otherwise interfere with the dyeing.
The fibers resulting from the process of the pre-sent invention have substantially improved water absorbency, dye receptivity, antistatic, soil release and inter-fiber adhesion and bonding properties and fabric hand. The fibers so treated by the present invention will retain their enhanced properties even when subject to many vigorous washings.
Detailed Description of the Invention Polymer fibers to which the present invention is directed include conventional polyester, and acrylic polymers, and combinations of these polymer fibers with other synthetic and/or natural fibers. Nonlimiting exam-ples of natural fibers which may be combined with the polyester, and acrylic polymer fibers include wool, cotton and silk. Non-limiting examples of synthetic polymer fibers which may be combined with the polyester, and/or acrylic fibers include nylon, acetate and cellulosic fibers, e.g., rayon.
The subject invention concerns the treating of polymer fibers per se and fibrous structures made thereof.
The term "fibrous structures" includes continuous fila-ments, multifilament threads, ba~ts, st~ple fibers, woven ' 7q~
or knitted fabrics and non-woven fabrics, and the like composed of at least one kind of the fibers mentioned above. As used herein, the term "polymer fibers" will be understood to include fibrous structures such as the above and others. Wherever the present disclosure refers to fiber surfaces or in~imate contact of the monomer with fiber surfaces or like expressions, it will be understood that the individual fibers o~ filaments are being referred to, such that contact and attachment of the monomer and graft polymer is with the surfaces of individual filaments of a multifilament thread or bundle, for example.
Polyester is ~he generic name for a fiber manu-factured either as a staple fiber or continuous filament in which the fiber-forming substance is any long chain synthetic polymer composed of at least 85% by weight of an ester of a dihydric alcohol and tereph~halic acid. The most common polyester fibers available in the United States are made of polyethylene terephthalate, and are available for example under the trademarks ~DACRON'I of E~Io duPont de Nemours & Co. and "FORTREL" of ICI United States, Inc. and Celanese Chemical Co. Polyester fibers are available as filament yarn, staple fibers and fiber to~s and are often combined with other fibers such as cotton and wool~ For example, much clothing is made from yarns which are a blend of polyester and cotton staple fibers. Fabrics made from such polyester fibers and fiber combinations are commonly used for making many types of outerwear, including dresses, suits, shirts, etc.
Polyesters form excellent fabrics and can he produced very cheaply on a mass production basis, but polyesters suffer from many drawbacks. Polyesters lack the ability bo si~nificantly absorb water and are subject bo s~atic electricity prbbl~ms.
By treating polyester fibers according to the process of the present invention, a most useful fabric is formed which has very good water absorbing, dye receptive and antistatic properties which are retained after many wa ~ings.
Acrylic is the generic name for fibers in which the fiber-forming substance is any long chain synthetic poly-mer composed of at least 85% by weight of acrylonitrile units (-CH2CH(CN)-). Such fibers are available in various types of staple fibers and tow, and are commercially avail-able under the trademarks "ORLON" of E. I. duPont de Nemours, & Co. and "CRESLAN" of American Cyanamid Co, for example.
Acrylic fibers for wearing apparel are usually blended with other fibers such as wool, or formed into yarns which are then knitted with other stron~er synthetic fibers or fila~
ments, such as nylon.
As with polyesters and other synthetic fibers, acry-lics lack the ability to significantly absorb water and are subject to static. By treating acrylic fibers according to the process of the present invention, fabrics are obtained which have excellent water-absorbing, dye receptive and anti-static properties which are retained after many wash-ings. As indicated in Canadian patent application S.N.
430,740, such surface characteristics are also improved in the other synthetic and natural fibers which may be combined with acrylics and/or polyesters.
The process of the present invention differ~ from those of the prior art in that polymerization of the mono-mer to be graft polymerized onto the polymer fibers is de-layed until there has been intimate con,tact of the monomer with the surface of the polymer fiber. Thus, while appli-cant does not wish to be bound by any particular theory or mechanism of reaction, it is believed that the-unsaturated monomer first attaches to ~he polymer chain on a molecule by molecule basis in the presence of acid and heat~ There-after, whe~ the polymerization is initiated by addition or activation of a polymerization initiator9 the monomer begins to polymerize so that there is chain addition uf monomer to the single monomer additions initi~lly graf~ed onto the polymer fibers. If significant homopolymerization of the monomer takes place prior to attachment of the mono-me~ to the fibers, most of it will simply be washed off the fibers so that there will be no significant permanent improvement in the surface properties of the fibers.
Accordingly, the first step of the method according to the present invention comprises the formation of an aqueous treating solution with dissolved monomer havin~ an acidic pH ~i.e. below about 7) and heated to a temperature of about 60C to about 100C and preferably in the range of about 70C to 90C. While temperatures above 100C are possible, they make processing more difficult and may make subsequent polymerization difficult to control.
Similarly, temperatures below about 60C may be possible but would usually result in a processing takin~ too long a time to be feasible commercially.
It is not necessary that the temperature be constant throughout the first step or throughout the process. For example, the treating solution could be formed at ahout 70C, or such temperature as will allow ready dissolving of the monomer and/or acid in the solution, and then the temperature could be raised to the desired level for poly-merization just prior to initiation of polymerization. The temperature would then be maintained at whatever level is necessary to obtain the optimum speed and degree of poly-merization. For example, the temperature could be raised to about 85C or 90C at the end of the first step and maintained at that temperature for the remainder of the treatment process.
The acid, monomer, fabric and heat may be combined in the first step of the treatment process in virtually any desired order, so long as all four of these elements are present prior to initiatin~ polymerization for a suf-ficient time to allow uniform dispersal and intimate con-tact of the monomer with the fiber surfaces. For exampler the order of combination in the first step may be any of the following: (1) addition of acid and monomer ~o water, addition of a delayed initiator (to be ac~ivated in the second step), and heating to ~he desired temperature; (2~
addition of monomer and a delayed initiator to water, addi-r tion of acid and heating to the desired temperature; (3)addition of monomer to water, heating to desired tempera-ture and addition of acid and delayed initiator; or (4) addition of acid monomer to water, addition of delayed initiator and heating to desired temperature. Other pos-sible orders of carrying out the first step will be evident to those skilled in the art based on the present disclo-sure.
Such uniform dispersal and intimate contact may be assisted by various forms of agitation of flow of the aqueous treating solution around and between the fiber surfaces. For example, in the case of the trea~ment of fibers in the form of fabric piece goods, agitation may be accomplished by the paddles in a conventional paddle tub.
Alternatively, for ~ibers in the form o~ fabrics which are processed in the form of rolls on a beam, the aqueous treating solution may be circulated around and through the beam by conventional pressure means.
The time necessary for attaining uniform dispersal and intimate conta~ will va y with the particular method o~ contacting the fibers with the aqueous solution. Al-though it is possible that the aqueous solution could be contacted with the fibers by spraying, padding, dipping or other means, it is most preferable to immerse the fibers in a bath formed by the aqueous solution. Using such immer-sion techniques, relatively short periods of time are necessary before polymerization may begin. For exampley about 10 minutes is usually suficient with adequate agi-tation or circulation of the aqueous solution.
After uniform dispersal and intimate contact has been achieved, polymerization of ~he monomer on the fibers may be commenced with the use of a suitable polymerization ini-tiator such as peroxide or persulfate compounds which are known in the art. The particular initiator selected wili depend upon the particular polymer fiber, the particular monomer used and the speed or other conditions of the poly-merization desired. If desired, the initiator may be a~d-ed during the first step so long as it is not activateduntil uniform dispersal and in~imate contact of the mono-mer with the fiber surfaces are acheived. The initiation of polymerization may then be carried out, such as by raising the temperature, changing the pH or changing some other condition which will activate the initiator.
Finally, the polymerization is allowed to continue until there has been substantial graft polymerization of the monomer on the polymer fibers to modify the surface properties of the fibers. Generally, a rather low degree of polymerization is desireable, since excessive poly-merization will result in large amounts of homopolymer in the fibers and in the pro~ess equipment, which must be cleaned and washed out after comple~ion of the process.
Therefore, it is preferable to avoid polymerization which significantly clouds the treating solution, and such small polymers as will remain in solution are preferred.
To this end, it is preferable to carry out the pro-cess of the present invention using very low concentrations of monomer, such as in the range of about 0.01 to about 1.0 weight percent of the total solution and preferably about 0.02 to 0.5 weight percent of the solution. Such low con-centrations allow easy control of ~he polymerization re-action so tha-t a relatively clear solution is maintained throughout the process, and the processing equipment and fibers treated may be easily cleaned and washed out.
Although applicant has not been able to accurately measure the exact amount of graft polymerization added onto the polymer fibers, it appears that optimum pro~
cessing according to the present invention results in the permanent add-on of about 0.1 weight percent or less of graft polymer based upon the weight of the polymer ~iber.
While the process of the present invention may be used at any o~ a number of stages during ~he usual pro-cessing of polymer fibers or fabrics or other s~ructures made from such fibers, it has been found pre~erable to use ~the process before the dyeing of the fibers or before 37~
there is any treatment of the fibers which would result in encapsulation or coating of the fiber surface. Thus, it is usual practice to encapsulate or "lock on" the dye or other fiber treatment chemicals, and such coatings will often interfere with the addition of the monomer to the polymer fiber. To the extent that there would still be addition, this would be gradually washed off through many washings.
Therefore, it is preferable that the fibers be scoured (e.g. washed with detergent) and rinsed prior to carrying out the treatment process of the present invention in order to remove dirt and other chemicals which may be present on the fibers. The process may then be carried out befcre dyeing or even in the dye bath but before the after treat-ment to set the dye. However, it is preferable to drain the treating solution and rinse the fibers before dyeing, in order to remove acid and excess homopolymer, which may interfere with reaction of the dye with the dye sites on the surface of the polymer fibers.
Whereas many of the teachings of the prior art such as Aikawa and Tanner involved the treating of fibers in the absence of polymerization initiators to avoid homo~
polymerization, the presen~ invention employs polymeriza~
tion initiators. Polymerization initiators are generally of four basic types, namely, peroxides, persulfides, acids and ceric compounds.
Non-limiting examples of polymerization initiators that may possibly be utilized in this invention inalude inorganic peroxides, e.g., hydrogen peroxide, barium perox-ide, magnesium peroxide, etc., and the various organiG
peroxy compounds illustrative examples of which ar@ the dialkyl peroxides, e.g., diethyl peroxide, dipropyl perox-ide, dilauryl peroxide, dioleyl peroxide, dis~earyl perox-ide, di-(tert.-butyl) peroxide and di-(tert.-amyl) peroxide, such peroxides often being designated as e~hyl, propyl, lauryl, oleyl, ~tearyl, tert.-butyl and tert.-amyl per-oxides; the alkyl hydrogen peroxides, e.g~ r tertO-butyl .
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~ r r hydrogen peroxide (tert.-butyl hydroperoxide), tert.-amyl hydrogen peroxide (tert.-amyl hydroperoxide), etc.; sym-metrical diacyl peroxides, for instance peroxides which commonly are known under such names as acetyl peroxide, propionyl peroxide, lauroyl peroxide, stearoyl peroxide, malonyl peroxide, succinyl peroxide, phthaloyl peroxide, benzoyl peroxide, etc.; fatty oil acid peroxides, e.g., coconut oil acid peroxides, etc.; unsymmetrical or mixed diacyl peroxides, e.g., acetyl benzoyl peroxide, pro-pionyl benzoyl peroxide, etc.; terpene oxides, e.g., ascaridole, etc.; and salts of inor~anic peracids, e.g., ammonium persulfate and potassium persulfate.
When fibers are treated according to this invention, the reaction ~ay also be initiated by ceric ions, for example, in the form of ceric salts such as ceric nitrate, ceric sulfate, ceric ammonium nitrate, ceric ammonium sulfate, ceric ammonium pyrophosphate, ceric iodate, and the like.
Non-limiting examples of suitable acids for use in the present invention include hydrochloric, phosphoric, sulfuric, nitric, acetic, formic, oxalic, tartaric, mono chloroacetic, dichloroacetic, trichloroacetic and similar acids. Formic and hydrochloric acid have been found to be particularly suitable in carryiny out the present inven-tion. It is possible that an acid can function as both a catalyst and initiator, e.~., formic acid.
Non-limiting examples of unsaturated types o~ mono-mers that may possibly be utilized in this invention in-clude N,N'methylene-bis-acrylamide (C~2(NHCOCH:CH2)2), N,N'-(1,2 dihyroxyethylene)-bis-acrylamide, acrylamide, acrylic acid, 2-propyn-1-ol, crotonic acid, tetraethylene glycol, styrene, alpha-methyl styrene, l,l-diphenyl ethy lene, alpha-vinyl naphthalene, vinylpyridine, 2-chloro-2j3-butadiene, methacrylic acid, methacrylamide, N methylol-acrylamidel N-methyl-N-vinyl ~ormamide, N-vinyl p~rroli-done, 3-, ~- or 5-methyl-N-vinyl pyrrolidone, vinyl o~y-ethylformamide, methyl acrylate, ethyl acrylate, octyl 3~
methyl methacrylate, vinylacrylate, acrylonitrile, meth-acrylonitrile, acrylyl chloride, vinyl methyl ketone, methallylalcohol, acrolein, methacrolein, vinyl acetate, p-vinyl phenyl acetate, methylmethacrylate, vinyl chloride, vinylidene chloride, p-chlorostyrene, 2,5-dichlorostyrene, 1,1,7-trihydro-perfluoroheptyl acrylate, methyl alpha-chloroacrylate, acrylyl cyanide, styrene sulfonic acid, salts and esters of styrene sulfonic acid and glycidyl methacrylate. The preferred monomers are N,N'-methylene-bis-acrylamide (NBA) and N,N'(1,2 dihydroxyethylene)-bis-acrylamide.
A monomer may function as an acid. NBA, for example, is slightly acidic in aqueous solution. It is also pos-sible to use specially modifled monomer which can provide special characteristics to the fibers, or fabrics made therefrom, such as crease sotness, lubricity (e.g. by in-cluding silicon groups on the monomer), adhesion, optical brigh~ness, anti-bacterial, anti-fungal or anti-mildew properties, etc.
In a preferred embodiment of this invention with the monomer utilized selected from the group consisting of NBA and N,N'(1,2 dihyroxyethylene)-bis-acrylamide, the polymerization step of the process is conducted for a period of time between about 0u5 minu~es and about 2 hours, preferably between about l.0 minute and about 30 minutes.
The amount of initiator in the treating solution is between about lX10-4 weight percent and 5.0 weight percent.
The particular concentrations of the monomer, acid and the initiator in the treating solution will vary wide-ly depending upon such fac~ors as the nature of the par-ticular monomer, acid and initiator, the time and temper-ature of the treatment, and the nature and form of the fiber being treated. While certain concentrations may be fairly essential for a particular monomer, acid and initi-ator under a given set of treatment conditions, applicant cannot give general ranges which would apply to all mono-mers, acids and initiators under all conditionst but those of ordinary skill in the ar~ will be able to optimize the concentrations by routine experimentation on the basis of the present disclosure.
Attaining the desired degree of treatment according to this invention would depend on the strength of the initiator and the concentration of the monomer and acid.
Thus, for example, a strong initiator, one that is inher-ently strong and/or having a high concentration of initi-ator, would require a lower monomer concentration. Con-versely, a weak initiator, one that is inherently-weak and/or having a low concentration of initiator, would require a higher monomer concentration. In the latter case, the treatment according to this invention can be controlled by draining the initiator containing solution from the fabric once the desired extent of polymerization has been achieved.
After polymerization begins, such polymerization being a function of the concentration and type of the acidr the unsatured monomer, fabric, initiator and the speed and type of the equipment being used, the fibers are allowed to remain in solution at the required temperature long enough to assure that uniform graft polymerization ("substantial polymerization") has occurred, such time usually not exceeding 30 minutes. The fibers can then be rinsed to neutralize the pH and remove excess homopoly-mers, if any.-The invention will now be described in greater de-tail by reference to the following specific, non-limiting examples:
Examples I
Athletic socks made of 75% acrylic ~ORLON) yarns and 25% nylon filaments were treated in a paddle-type dye tub containing 150 liters of water. Fity ml of 33% HCl and 50 ml of about 88% formic acid were added to water heated to 160F (71C~, and 56 grains of MBA were then dissolved in the wa~er. Less than one pound of acrylic athletic socks was immersed in the solution, and the ~emperature was rapidly raised to 185F (85C) and held there for 10 minutes~
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Twenty-five grans of potassium persulfate was added, and three minutes after the addition a milky precipi~ate ap-peared. Ten minutes after the addition of persulfate, the tub was drained and the socks were rinsed wi~h fresh wa~er.
Example II
The process ~f Example I was repeated with less than a pound of single knit fabric made of textured DACRON poly-ester (150 denier, 34 filament).
Testing Of Sam~les I and II
Polyester and acrylic samples processed according to Examples I and II were put through fifty home launderings with household detergent. Each set of ten wash cycles consisted of seven normal cycles with 30 grams of "Fab"
home laundry detergent in a 10 pound capacity "Kenmore"
home washer set on warm water wash, followed by three normal cycles set on warm water with no detergent.
Vertical wicking of samples was tested after drying after each set of ten wash cycles as follsws: Samples were cut at different times and vertical wicking was tested by cutting a strip of fabric, suspending one end in water, and measuring distance wicked above the surface. Polyester readings were made at two minutPs, and acrylic rea~ings were made at five minutes. Controls were untreated acrylic and polyester. The result~ are ~abulated in Tables I and II below.
POLYESTER VERTICAL WICXING
WASHING CONTROL TREATED
CYCLES ~cm) (çm) 0 4.S
0 4.2 0 4.5 0 5.5 *Trade mark 3~
TABLE II
_ .. . .. _ ACRYLIC VERTICAL WICKING
WASHING CONTROL TREATED
CYCLES (cm) ~cm) 3.5 10.~
3.2 ~ 10.5 3.6 10.2 3.4 10.0 3.5 9.0 3.5 9.1 In addition to the above-demonstrated hygroscopic properties, the fabrics treated in Examples I and II had excellent hand and feel characteristics, improved dyeabil-ity, good antistatic properties and generally improved surface properties.
The present invention may be embodied in other spe-cific forms wi~hout departing from the spirit or essential attributes ~hereof and, accordingly, reference should be made to the appended claims, rather than to the foregoing specification, as indicating the scope of the invention.
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Claims (24)
1. A method of treating polymer fibers selected from the group consisting of polyester and acrylic polymers to improve the hygroscopic, dye receptive and other surface properties of the fibers, comprising the steps of:
(a) contacting the fibers in the absence of a polymerization initiator with an aqueous solution heated to a temperature between about 60-100°C, containing at least one unsaturated monomer under acidic conditions, and agitating said solution for about 10 minutes to allow uniform dispersal and intimate contact of the monomer with the fiber surfaces;
(b) thereafter initiating polymerization of the monomer on the fibers by means of a polymerization initiator for the monomer; and (c) continuing the polymerization of the monomer on the fiber until substantial polymerization has occurred to modify surface properties of the fibers.
(a) contacting the fibers in the absence of a polymerization initiator with an aqueous solution heated to a temperature between about 60-100°C, containing at least one unsaturated monomer under acidic conditions, and agitating said solution for about 10 minutes to allow uniform dispersal and intimate contact of the monomer with the fiber surfaces;
(b) thereafter initiating polymerization of the monomer on the fibers by means of a polymerization initiator for the monomer; and (c) continuing the polymerization of the monomer on the fiber until substantial polymerization has occurred to modify surface properties of the fibers.
2. A method according to Claim 1 wherein the pH of the aqueous solution is established and maintained below about 7 by addition of acid in step (a).
3. A method according to Claim 1 wherein the pH of the aqueous solution is established and maintained below about 7 by using an acidic monomer.
4. A method according to Claim 1 wherein the pH of the solution is maintained below about 7 and the temperature of the solution is maintained between about 60°C and 100°C
during steps (b) and (c).
during steps (b) and (c).
5, A method according to Claim 1 wherein the polymerization is continued for a period not exceeding about 30 minutes.
6. A method according to Claim 1 wherein said fibers are scoured and rinsed prior to step (a).
7. A method according to Claim 1 wherein said fibers are rinsed and dyed after step (c).
8. A method according to Claim 1 wherein the solution is heated in step (a) to a temperature of about 70°C to about 90°C.
9. A method according to Claim 1 wherein step (c) is continued for about 10 minutes followed by draining the solution and rinsing the fibers with fresh water.
10. A method according to Claim 1 wherein the fibers are in the form of a knitted, woven or non-woven fabric.
11. A method according to Claim 10 wherein said fabric comprises a mixture of acrylic yarn and nylon filaments.
12, A method according to Claim 10 wherein said fabric comprises yarns which are a blend of polyester and cotton staple fibers.
13. A method according to Claim 1 wherein the fibers are treated as follows:
(a) immersing said fibers in an aqueous solution at about 70°C containing about 0.01 weight percent. hydrochloric acid, about 0.03 weight percent formic acid and about 0.04 weight percent N,N'-methylene-bisacrylamide, rapidly raising the temperature of the solution to about 85°C and agitating the fibers in the solution for about 10 minutes;
(b) thereafter adding about 0.02 weight percent potassium persulfate to the solution to initiate polymerization; and (c) continuing the polymerization for about 10 minutes, followed by draining the solution from the fibers and rinsing the fibers in water, all weight percents being on the basis of percentage by weight of the total solution.
(a) immersing said fibers in an aqueous solution at about 70°C containing about 0.01 weight percent. hydrochloric acid, about 0.03 weight percent formic acid and about 0.04 weight percent N,N'-methylene-bisacrylamide, rapidly raising the temperature of the solution to about 85°C and agitating the fibers in the solution for about 10 minutes;
(b) thereafter adding about 0.02 weight percent potassium persulfate to the solution to initiate polymerization; and (c) continuing the polymerization for about 10 minutes, followed by draining the solution from the fibers and rinsing the fibers in water, all weight percents being on the basis of percentage by weight of the total solution.
14. The method of Claim 1 which further comprises rinsing said fibers or fibrous structures after substantial polymerization has occurred to neutralize the pH and remove any excess homopolymers.
15. The method of Claim 1 wherein said initiator is selected from the group consisting of peroxides, persulfates, acids and ceric salt compounds.
16. The method of Claim 1 wherein said monomer is selected from the group consisting of N/N'-methylene-bis-acrylamide; N,N'-(1,2-dihydroxyethylene)-bis-acrylamide;
salts of N,N'-methylene-bis-acrylamide, salts of N,N'-(1,2-dihydroxyethylene)-bis-acrylamide;
acrylic acid, 2-propyl-1-ol; crotonic acid and tetraethylene glycol diacrylate.
salts of N,N'-methylene-bis-acrylamide, salts of N,N'-(1,2-dihydroxyethylene)-bis-acrylamide;
acrylic acid, 2-propyl-1-ol; crotonic acid and tetraethylene glycol diacrylate.
17. The method of Claim 1 wherein the amount of said monomer is between about 0.01 weight percent and about 1.0 weight percent based on the total weight of said solution.
18. The method of Claim 1 wherein the amount of said monomer is between about 0.02 weight percent and about 0.5 weight percent based on the total weight of said solution.
19. The method of Claim 1 wherein said polymerization has a duration of between about 0.5 minutes and about 2.0 hours.
The method of Claim 1 wherein said polymerization has a duration of between about 1.0 minute and about 30 minutes.
21. The method of Claim 1 wherein said acid is selected from the group consisting of formic, hydrochloric, phosphoric, sulfuric, nitric, acetic, oxalic, tartaric, monochloroacetic, dichloroacetic and trichloroacetic.
22. The method of Claim 1 wherein said solution is agitated during steps (a), (b) and (c).
23. The improved polymer fiber product produced by the method of Claim 1, 10 or 11.
24. The improved polymer fiber product produced by the method of Claim 12 or 13.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US39073282A | 1982-06-21 | 1982-06-21 | |
| US390,732 | 1982-06-21 | ||
| US06/426,498 US4743267A (en) | 1982-06-21 | 1982-09-29 | Process for improving polymer fiber properties and fibers produced thereby |
| US426,498 | 1982-09-29 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1248709A true CA1248709A (en) | 1989-01-17 |
Family
ID=27013260
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000430762A Expired CA1248709A (en) | 1982-06-21 | 1983-06-20 | Process for improving polymer fiber properties and fibers produced thereby |
Country Status (2)
| Country | Link |
|---|---|
| US (1) | US4743267A (en) |
| CA (1) | CA1248709A (en) |
Families Citing this family (14)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5154727A (en) * | 1981-01-07 | 1992-10-13 | Intera Corporation | Process for improving polymer fiber properties and fibers produced thereby |
| US4904265A (en) * | 1988-09-09 | 1990-02-27 | Boehringer Mannheim Corporation | Cementless acetabular implant |
| US5407728A (en) * | 1992-01-30 | 1995-04-18 | Reeves Brothers, Inc. | Fabric containing graft polymer thereon |
| US5486210A (en) | 1992-01-30 | 1996-01-23 | Reeves Brothers, Inc. | Air bag fabric containing graft polymer thereon |
| US5882356A (en) * | 1992-10-21 | 1999-03-16 | Courtaulds Fibres (Holdings) Limited | Fibre treatment |
| GB9304887D0 (en) * | 1993-03-10 | 1993-04-28 | Courtaulds Plc | Fibre treatment |
| US5540964A (en) * | 1994-03-25 | 1996-07-30 | Intera Technologies, Inc. | Moisture transport cast lining material for use beneath an orthopedic cast, being in the form of a fabric and consisting essentially of synthetic hydrophobic fibers or a blend of synthetic hydrophobic fibers and a second different fiber |
| US5487942A (en) * | 1994-04-28 | 1996-01-30 | Nippon Sanmo Sensyoku Co., Ltd. | Carboxyl group-modified acrylonitrile fiber and process of producing same |
| DE69428980D1 (en) * | 1994-04-29 | 2001-12-13 | Nippon Sanmo Sensyoku Co Ltd | Carboxy group modified cellulose or acrylic fibers and process for making the same |
| GB9410912D0 (en) * | 1994-06-01 | 1994-07-20 | Courtaulds Plc | Fibre treatment |
| US5591516A (en) * | 1995-06-07 | 1997-01-07 | Springs Industries, Inc. | Durable, pill-resistant polyester fabric and method for the preparation thereof |
| US6316373B1 (en) | 1996-04-26 | 2001-11-13 | William Kenneth Alexander | Expandable breathable laminate |
| US5855623A (en) * | 1996-09-20 | 1999-01-05 | Intera Technologies, Inc. | Process for improving polyamide, acrylic, aramid, cellulosic and polyester properties, and modified polymers produced thereby |
| US20070044255A1 (en) * | 2005-08-25 | 2007-03-01 | Mohawk Brands, Inc. | Increasing receptivity for acid dyes |
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| GB770766A (en) * | 1953-12-01 | 1957-03-27 | Calico Printers Ass Ltd | Improvements relating to the anti-static treatment of synthetic products |
| US2784052A (en) * | 1954-04-23 | 1957-03-05 | Du Pont | Process of preparing waterproof films, fabrics, filaments, and yarns of regenerated cellulose containing within a waterproof addition polymer and products produced therefrom |
| US3005730A (en) * | 1954-10-25 | 1961-10-24 | Jr Clay E Pardo | Shrinkproofing of wool with n, n'-methylene bis-acrylamide polymerized in situ and the modified wool |
| LU34305A1 (en) * | 1955-04-29 | |||
| NL128624C (en) * | 1955-05-31 | |||
| BE553541A (en) * | 1955-12-19 | |||
| BE561742A (en) * | 1956-10-18 | |||
| NL229381A (en) * | 1957-07-08 | |||
| US3092512A (en) * | 1957-10-31 | 1963-06-04 | Table ii | |
| US2959565A (en) * | 1958-01-29 | 1960-11-08 | Dow Chemical Co | Compositions comprising graft copolymers of certain monomeric polyglycol esters of acrylates and methacrylates on superpolyamide substrates |
| US3083118A (en) * | 1958-03-04 | 1963-03-26 | Tee Pak Inc | Method of depositing a polymer of olefinically unsaturated monomer within a polymeric material and the resulting product |
| NL246911A (en) * | 1958-03-06 | |||
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| US3097185A (en) * | 1958-07-29 | 1963-07-09 | Dow Chemical Co | Graft copolymers comprised of certain acrylamide and methacrylamide monomers on polyvinyllactams and improved acrylonitrile polymer compositions obtainable therewith |
| FR1235424A (en) * | 1959-05-26 | 1960-07-08 | Usines Chimique Rhone Poulenc | Process for grafting polymerizable monomers onto polyvinyl alcohol objects |
| US3236584A (en) * | 1960-03-23 | 1966-02-22 | Edward F Degering | Graft polymerization on a paper base by ionizing radiation |
| US3202541A (en) * | 1960-08-31 | 1965-08-24 | Du Pont | Process for impregnating fabrics with aqueous polymeric impregnating composition |
| US3218117A (en) * | 1961-08-02 | 1965-11-16 | American Cyanamid Co | Polypropylene fibers and method for preparing same |
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| US3297471A (en) * | 1965-04-08 | 1967-01-10 | Du Pont | Acrylic or methacrylic acid grafting copolymerized on nylon and forming salt of said graft |
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| JPS6017869B2 (en) * | 1979-05-31 | 1985-05-07 | カネボウ株式会社 | Processing method for fibers or fiber structures |
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-
1982
- 1982-09-29 US US06/426,498 patent/US4743267A/en not_active Expired - Lifetime
-
1983
- 1983-06-20 CA CA000430762A patent/CA1248709A/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| US4743267A (en) | 1988-05-10 |
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