GB2153399A - Discoloration-resistant fabrics - Google Patents

Abstract

A fabric treated with a quaternary ammonium base-containing organosilicone, in which the quaternary ammonium cations are at least partially capped by an anionic surfactant. The product can have good discoloration-resistance combined with good anti-microbial properties.

Description

SPECIFICATION Discoloration-resistant Fabrics The present invention relates to discoloration-resistant, anti-microbial fabrics.

The atmosphere contains various micro-organisms, such as fungi and bacteria, which are harmful to the human body and to fabrics. For instance, fungi and bacteria grow and propagate on a wide range of fabrics such as clothes and bedroom fabrics, and various house and outside fabric products, using as nutrients the components of human sweat, foods and/or drinks which have adhered to the fabrics. As a result, the fabrics may be caused to smell or be discoloured, the effect of the excreta of the micro-organisms, or embrittle. The growth may be harmful to the human body, particularly on fabrics such as socks, underwear, casual wear, sheets and bedcovers.

It is known to make fabrics resistant to micro-organisms by treating them with organic tin or mercury compounds, halogenated phenols, quaternary ammonium salt-containing cationic surfactants and quaternary ammonium base-containing vinyl polymers. However, these treatments are not necessarily satisfactory, owing to their toxicity, problems associated with treatment and environmental pollution, lack of durability and a tendency to cause fabric discoloration (or at least a failure to resist microbial discoloration).

For example, JPA45485/1981 discloses the treatment of a fabric with a quaternary ammonium base-containing cationic surfactant, of low toxicity. However, the treated fabrics have low durability and poor hand. Further, fabrics containing a fluorescent whitening dye are unsuitable for treatment in this manner, because most such dyes contain an anionic group; the fluorescent effect is thus lost on treatment, causing yellowing of the product.

A fabric according to the present invention has been treated with a quaternary ammonium base-containing organosilicone, the quaternary ammonium cation being at least partially sealed with an anionic surfactant. Such a fabric may be obtained by treatment with the organosilicone and subsequent at least partial sealing, with an anionic surfactant.

Fabrics of the invention can have good resistance to discoloration, good durability in washing, good resistance to yellowing and reduction in whiteness, good moisture-absorbence, good hand and good anti-microbial activity.

The quaternary ammonium base-containing organosilicone which is used in the present invention may be, for example, a diorganopolysiloxane having a siloxane unit containing a quaternary ammonium base, obtained by converting a group containing a tertiary amine, e.g. a dialkylaminoalkyl group, into the corresponding quaternary ammonium group.For example, the organosilicone may have the formula (R)3SiR'N+(R2)n(R3)3~nX- wherein the R's are independently selected from C12o alkyl, hydroxy, C1~20 alkoxy, C2~18 alkanoyl and halogen, provided that at least two R's are other than hydroxy and alkyl; R' is a divalent Cl-2o hydrocarbon radical, optionally containing oxygen and/or nitrogen (which may be substituted) atoms; each R2 is, independently, C,-6 alkyl; each R3 (if present) is, independently, C12o alkyl, C22o alkenyl or C7-1O aralkyl; n is 1,2 or 3; and X- is an anion.Examples of R1 are-CH2-, -(CH2)2-, (CH2)-, -(OH2)6-, -(CH2)18-, phenylene such as 1,4-phenylene (defined herein as Ph), phenylalkylene such as-Ph-CH2- or -Ph-Ph-CH2-, -(OH2)2-(OH2)2-, -(CH2)2-CHOH-(CH2)2-, -(OH2)2-O-OH2-OHOH-OH2-, -(OH2)-NH-(OH2)2- and -(OH2)2-N(O2H5)-(OH2)2-. When R3 is aralkyl, it may be, for example, benzyl or phenethyl. X may be chlorine or bromine.

Preferred organosilicones for use in the invention have the formula [(CH30)3Si(CH2)3N(R')2CmH2m+,]+CI- II wherein R' is CH3 (preferred) or C2H5 and m is 16, 17, 18, 19 or 20.

These organosilicone compounds can form a film coating on fibres in suitable fabrics. On treatment, the quaternary ammonium cation is introduced into the fabric by reaction of the compound and active hydrogen atoms in the fibres. This provides activity against various fungi such asAspergillus niger (bread mould), Penicillia (green mould),Aspergillus oryzae, Chaetomium and Rhizopus nigricans, and bacteria such as Escherichia coli, Staphylococcus aureus, Corynebacterium, Bacilli and Micrococci.

The fabric which is treated in the present invention may have various fibre components. They may be natural fibres such as those of cotton, hemp, wool or silk, regenerated fibres such as those of viscose rayon, polynosic rayon or copper ammonium rayon, semi-synthetic fibres such as acetate fibres, promix fibres such as protein-acrylonitrile fibres, or individual, mixed or conjugate fibres of synthetic fibres such as polyamide, acryl, polyester or polyolefin fibers), and further various threads, textiles, non-woven fabrics, rugs, sewn products which are obtained from the above fabrics. Besides, composite products of these fibers and other materials are also included.

These fabrics are firstly treated with the organisilicone as mentioned above in a usual manner, for example, treatment in an aqueous solution of the organosilicone; treatment in a pad bath, followed by drying; treatment by spraying the aqueous solution, followed by drying; treatment in a pad bath, followed by steam treatment; among which the treatment in an aqueous solution is particularly suitable. After the treatment, the fabrics may optionally be subjected to heat treatment. In case of the treatment in an aqueous solution, it is usually carried out by dipping the fabrics to be treated in a bath (liquor ratio, 1:5100 by weight) at a temperature of from room temperature to 80"C, preferably 40 to 70"C, for 30 minutes or longer, by which the fabrics exhaust the organosilicone sufficiently.After the exhaustion treatment, the fabrics are dried with hot air of 80"C or higher. The organosilicone is adhered onto the fibers of the fabrics in an amount of 0.1 to 3% by weight (as the solid components), preferably 0.5 to 1% by weight, based on the weight of the fabrics. In the treatment with an organosilicone, there may be used also perfluoroaikyl-containing water or oil repellants, organopolysiloxanes containing no quaternary ammonium cation or polyether-polyester block copolyester stainproofing agents.

The fabrics thus treated merely with the organosilicone have excellent antimicrobial activities and have excellent durability of the activities even after washing at home or dry cleaning, but do not show sufficient durability when they are exposed to severe sterilization treatment such as treatment with chlorine (50 ppm) at 70"C for 10 minutes which is usually done in hospitals or in case of high temperature treatment in autoclave. Moreover, when whitening products, such as fluorescent dyed cellulose fiber products are treated with the organosilicone, the products show occasionally lowering of whiteness or yellowing during storage thereof to result in significant lowering of the product value. This reason is not made clear, but is assumed that it is caused by bad compatibility between the compound and the fluorescent dyes.Besides, mere treatment with the organosilicone is not suitable for towels, sheets or underwear because the fabrics become hydrophobic. These drawbacks can be eliminated by further treatment with an anionic surfactant.

Thus, it is essential in the present invention to treat the organosilicone-treated fabrics with an anionic surfactant. The anionic surfactant used in the present invention may be, for example, an alkali metal C,3~19 alkanoate, an alkali metal C8~18 alkanol sulphate, an alkali metal C8~20 alkylsulphonate, a sulphated oil such as sulphated castor oil, a sulphonated fatty acid ester, a C8~20 olefin sulphate, an alkali metal p-(C1015 alkyl)-benzenesulphonate, an alkali metal (C34 alkyl)naphthalenesulphonate, a C82O paraffin sulphonate such as sodium oleymethyltauride or C17H35CO-N(CH)-CH2CH2SO3Na (avai;;able as Igepon T, manufactured by IG), a dialkali metal C8~,8 alkylphosphate, or an alkali metal di-(C1 -18 alkyl)phosphate. Particular examples of suitable sulphonated fatty acid esters are sulphonated fatty acid esters of the formula R4-CH(SO3M)-COOR5 and sulphosuccinates of the formula R8OOC-CH(SO3M)-CH2-COOR7, wherein M is an alkali metal, R4, Rs and R7 are the same or different C1-,, alkyl groups and R5 is allyl or C,~18 alkyl. The sulphosuccinate may be, for example, sodium dioctyl sulphosuccinate (available as Aerosol OT, manufactured by ACC).

The alkali metal aikanoates and sulphonated fatty acid esters, especially the sulphosuccinates, are preferred in view of their beneficial effect on yellowing prevention and moisture-absorbency. If desired, two or more anionic surfactants may be used in combination.

The amount of anionic surfactant which is used is sufficient to seal at least part, preferably at least 50% and more preferably all, of the cationic groups in the organosilicone. Usually, there are from 0.5 to 2 equivalents of the anionic group with respect to the cationic group. The moisture- and sweat-absorbence of the treated products may be improved by the use of an excess amount of anionic surfactant, i.e. an amount more than sufficient to seal the cationic groups, e.g. a factor of at least 0.5 more than that necessary for sealing or sufficient to give from 1.5 to 2 equivalents of anionic groups to cationic groups.

The fabric should be treated with the organosilicone and the anionic surfactant in that order. It appears that, even if the fabrics are simultaneously treated with both treating agents in the same bath, no desired effect can be obtained.

The treatment with an anionic surfactant is also carried out in the same manner as in the treatment with an organosilicone, i.e. by dipping in a solution of an anionic surfactant or by the treatment in a pad bath.

However, when the treatment of fabrics with an organosilicone is carried out by dipping in a solution thereof (dipping method), it is preferable to do the treatment with an anionic surfactant in such a manner that, after the organosilicone is sufficiently exhausted to the fibers of fabrics, an anionic surfactant and optionally other salts and additives are added to the same bath, and the organosilicone-treated fabrics are treated in said bath for several minutes to several tens of minutes. Thus, in such a manner, the operation is so simple and no special equipment is required. This is also one of the advantages of the present invention.

On the other hand, when the treatment of fabrics with an organosilicone is done by pad method, the treatment with an anionic surfactant is also preferably carried out by the pad method, followed by drying.

However, the method of the present invention is not limited to such treatment manners, but it may also be adopted to do the treatments is such a manner that the treatment with an organosilicone is done by the dipping method and the subsequent treatment with an anionic surfactant is done by the pad method, and vice versa.

The fabrics treated with an anionic surfactant of the present invention is also advantageously improved in anti-chlorine property.

The present invention is illustrated by the following examples but is not construed to be limited thereto.

EXAMPLE 1 Cotton-milling knit fabric which was scoured, bleached and fluorescent-dyed was charged in a water in a wince dyeing machine (liquor ratio, 1:20), to which Dow Corning 5700 (formula ll: m=18, R'=CH3; 1.2 % based on the weight of the fabric, abbreviation: owf) was added portionwise over a period of 10 minutes while running the machine. The bath temperature was raised to 50"C over a period of 15 minutes, and the fabric was treated at the temperature for 15 minutes. After adding thereto soap (1.2% owf), the treatment was continued for 15 minutes. After the treatment, the fabric was dehydrated by centrifugation and dried at 1200C with a short loop dryer, by which the sterilization treatment was effected.For comparison purpose, a reference fabric was obtained by repeating the above procedure except that no soap was used.

The fabrics thus treated were tested as to their whiteness, light fastness and durability. The. whiteness was tested by measuring L, a and b with a colorimeter (manufactured by Nippon Denshoku K.K.) and evaluated based on the data. The light fastness was measured by irradiating the fabrics with a fadeometer for 1,3 and 5 hours, and the discoloration was compared. The durability was measured by subjecting the fabrics to be tested to washing 50 times with a home-washing machine, followed by treating with an aqueous solution of 50 ppm of sodium hypochlorite at 70"C for 10 minutes and then subjecting the test sample thus treated to assessment of antimicrobial activities by the anti-fungal activity measuring method as set forth in Japanese Industrial Standard (JIS) Z-291 1.The results are shown in Table 1, wherein 0: excellent, A: good and x: bad.

As is shown in the table, the fabric subjected to the antimicrobial treatment without soap showed higher b value and less whiteness in comparison with a non-treated fabric (fluorescent dyed fabric), and showed easier discoloration within a short period of time in the irradiation with a fadeometer, and further showed less antimicrobial activities in the treatment with 50 ppm sodium hypochlorite solution at 70"C for 10 minutes while showed good antimicrobial activites in the 50 times washing with home washing machine. On the contrary, the fabric subjected to the sterilization treatment using soap showed neither lowering of whiteness nor difference in light fastness in comparison with a non-treated fabric, and further showed excellent durability of antimicrobial activities even after the treatment with sodium hypochlorite solution.

Properties Light Antimicrobial Whiteness Resistance Activities Non- Wash- Cl ing treat Test Fabrics L a b 1 her 3hr 5hr treated x50 ing Non-treated 92.6 3.7 -6.4 4--5 4 3--4 x x x (fluorescent dyed) Treatment 92.2 2.9 -3.9 3 3 3 0 O x-A without soap Treatment 92.9 3.0 -6.3 4--5 4 34 0 0 0 using soap EXAMPLE 2 Poiyester jersy which was refined, pre-set and dyed was dipped in the same aqueous solution of a quaternary ammonium base-containing organosilicone as used in Example land the temperature was raised to 60"C, and then treated for 20 minutes. To the bath was added a sulfonated fatty acid ester (sodium isopropyl a-sulfostearate) (1% owf), and then it was treated for 10 minutes, dehydrated and dried. The product thus treated was tested as to the durability of antimicrobial activities in the same manner as described in Example 1. When the properties of the product treated in the bath added with the sulfonated fatty acid ester and that without using the sulfonated fatty acid ester.As a result, the former product did not show lowering of the antimicrobial activities even after the treatment with sodium hypochlorite.

EXAMPLE 3 Cotton woven fabric which was desized, refined, mercerized and fluorescent-dyed was dipped in a 1.5% by weight aqueous solution of a quaternary ammonium base-containing organosilicone (formula II: m=17, R'=C2H5) in a pad bath, and squeezed to about 70% in pick-up rate with a padder, and then dried to give a sterilized product adhered with about 1% owf organosilicone. The product thus treated was subjected to padding with an aqueous solution containing 0 to 5% by weight of a dialkylsulfosuccinate (i.e. sodium dioctyl sulfosuccinate, Aerosol OT, manufactured by ACC) and then dried. The relation of the adhered amount of the dialkylsulfosuccinate, whiteness (b value) and water-absorbability was measured. The results are shown in the accompanying drawing.The water-absorbability was measured by dropping water drops on the fabric thus treated while keeping it horizontally, and then counting the time till the dropped water was diffused and disappeared (wicking).

As is clear from the results, the product treated without the dialkylsulfosuccinate showed higher b value and less whiteness and was also inferior in the water-absorbability. On the other hand, when the adhered amount of the dialkylsulfosuccinate became to the same 1% owf as the amount of the organosilicone, the whiteness became equilibrium and the product showed excellent whiteness. Besides, the wicking properties became also better with increase of the amount of the anionic surfactant.

Moreover, the antimicrobial activities of the fabrics thus treated were also tested by a bioassay method, i.e. by impregnating the fabrics with a solution containing a prescribed amount of a gram-negative bacteria, allowing to stand the fabric at the same temperature as that of human body for a fixed period of time, and then measuring the number of bacteria, whereby the increase or decrease of the number of bacteria being compared. As a result, the non-treated fabric showed increase in the bacterial number, but the fabric subjected to the antimicrobial treatment showed decrease of the bacterial number. The fabric treated by the present invention showed excellent antimicrobial activities (with decrease of 95% or more of the bacterial number) regardless the treatment with the dialkylsulfosuccinate. However, when the product having less than 0.5 % owf in the adhered amount of the dialkylsulfosuccinate was treated with 500 ppm sodium hypochlorite aqueous solution at 70"C for 10 minutes as in Example 1, it showed decrease of bacterial number to less than 50%, while it could keep good durability of antimicrobial activities by the 50 times washing with a home washing machine. Thus, this also showed that the after-treatment is necessary for the durability of the antimicrobial effect.

Claims (7)

1. Afabrictreated with a quaternary ammonium base-containing organosilicone, in which the quaternary ammonium cations are at least partially capped by an anionic surfactant.

2. A fabric according to claim 1, in which the organo-silicone has the formula (R)3SiRaN+(R2)n(R3)3~nX- wherein one R is C120 alkyl, hydroxy, C,~20 alkoxy, C2~,8 alkanoyl or halogen and the other R's are, independently, C,~20 alkoxy, C2~,8 alkanoyl or halogen; R' is a divalent Cut~20 hydrocarbon radical, optionally containing oxygen and/or nitrogen (which may carry a substituent) atoms; each R2 is, independently, C16 alkyl; each R3 (if present) is, independently, C,~20 alkyl, C220 alkenyl or C7~,0 aralkyl; n is 1, 2 or 3; and X- is an anion.

3. A fabric according to claim 1, in which the organo-silicone has the formula [(CH30)3Si(CH2)3N(CH3)2CmH2m+1]+Cl II wherein m is an integer of from 16 to 20.

4. A fabric according to any preceding claim, in which the anionic surfactant is an alkyl metal C12-18 alkanoate or a sulphonated fatty acid ester.

5. A fabric according to claim 4, in which the anionic surfactant is an alkali metal di(C~18 alkyl)sulphosuccinate.

6. A process for preparing a fabric according to any preceding claim, which comprises sequential treatment with the organosilicone and the anionic surfactant.

7. A process according to claim 6, substantially as described in any of the Examples.