Method For Imparting Durable Soil-resistant Finish To Polyamide And Polyester Fabrics And The Treated Fabrics

Abstract

A method of imparting a durable soil-resistant finish to synthetic fabrics selected from the group consisting of polyamide and polyester fabrics comprising padding the fabrics in a treating bath containing 2-10 percent by weight of a polymer hydrosol selected from the group consisting of polymethacrylic acid, polyvinyl alcohol and carboxymethyl cellulose in the form of colloidal dispersion, 0.1-4.0 percent by weight of precondensate resin of a member selected from the group consisting of cyclic ethylene-urea and melamine-formaldehyde resins, and acidic catalyst for these resins, squeezing the treated fabrics with a mangle at a pickup of 40-100 percent, drying the squeezed fabrics at 80.degree.-110.degree. C. and subjecting the fabrics to a high-temperature treatment at 140.degree.-170.degree. C. for 30-40 seconds; washing the resultant fabrics with an aqueous solution containing a detergent maintained at above 40.degree. C., drying and finishing.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention:

This invention relates to a method of imparting soil-resistant finish to knitted or woven fabrics of polyamides or polyesters.

2. Description of the Prior Art

Though synthetic fibers have been remarkably developed in recent years due to their superior properties, there still remain some drawbacks with them in that, for example, they tend to be easily soiled, among others.

In an early stage of studies on soiling of knitted or woven fabrics, efforts were concentrated on analyses of soil components and clarification of adhesion mechanism of soils on cotton and wool, and some soil-resistant finishes were proposed based on the observations obtained. However, a reliable method of soil-resistant finish had not been developed when synthetic fibers appeared, and owing to their property to be easily soiled, the problem of soil resistance was again closed up and it was studied from different standpoints. Nevertheless, there has been found no reliable method of imparting soil-resistant finish to synthetic fibers, particularly against soils by contact. Though there are some effective methods of soil release finish for preventing and inhibiting soil redeposition (which may be referred to as resoiling hereinafter) of polyester/cotton fabrics during laundering, the fundamental concept of these methods is that generally a film of a hydrophilic material is formed on the surface of hydrophobic synthetic fibers to inhibit redeposition of oily soils during laundering. For example, there has been proposed a method wherein polyester fibers are treated with a block copolymer of polyethylene glycol and polyethylene terephthalate. However, the methods proposed heretofore have drawbacks in that they are not effective for preventing resoiling by relatively hydrophilic soils with a tendency to affect adversely, and that the soil resistance of thus-treated fabrics to the soils floating in the air is not improved but affected adversely due to the tacky film formed on the surface thereof. Of course, it will be hardly expected to find a perfect soil-resistant finish effective for all sorts of soils, since the properties of soils adhering on clothes on wearing are so complicated and there will be so many soils having various contradictory properties to each other. Nevertheless, we have concentrated our efforts from the consumer's standpoint to find an effective soil-resistant finish to prevent soils from adhering on the fabrics by contact without having serious adverse influence, and accomplished the present invention.

The conventional methods of soil-resistant finish known heretofore for natural textiles and regenerated cellulose fibers may be classified as follows: (1) chemical modification such as mercerization, acetylation, amino-alkylation, formalation, carboxymethylation, and treatment by urea-formaline resins, (2) application of film-forming agents such as carboxymethyl cellulose, starch, polyvinyl alcohol, gelatine, polyvinyl acetate, acrylic esters, cationic and anionic softening agents, silicon water repellents, and organic fluorides, and (3 ) application of fine-particle fillers such as colloidal silica, alumina, and iron oxide. Although none of these methods affords a decisive and satisfactory soil-resistant effect, some of them, for example, treatment with carboxymethyl cellulose, show a temporary activity to prevent resoiling and the treatment with colloidal silica shows an activity to prevent soil adhesion by contact. However, such effects obtained do not last for a prolonged period of time.

As described above, the concentrated studies on soil resistance of synthetic fibers have just been started and practically no reliable result has been obtained so far. Therefore, there is found no permanent soil-resistant finish which is expected to show any satisfactory effect in practice.

There is no established conclusion as to the soil-resisting effect of antistatic agents and some of them show a soil-resistant effect, though others act adversely depending on the type of the agents. They have been studied only from the aspect of the antistatic activity but not from the aspect of the soil resistance. The same is said with regard to softening agents and there has been known that, for example, polyethylene-, acrylic ester- or silicon-derived softening agents adversely affect soil resistance considerably. The method of imparting a soil-resistant finish to synthetic fibers is now being earnestly studied under such circumstances as mentioned above.

SUMMARY OF THE INVENTION:

The present invention relates to a method of imparting a soil-resistant finish for knitted or woven fabrics of polyamides or polyesters which is particularly effective for preventing soiling by contact. In brief, the present invention is directed to render knitted or woven fabrics more soil resistant and washfast than those which have been achieved, by padding the knitted or woven fabrics with a polymer hydrosol together with cyclic ethyleneurea and/or melamine-formaldehyde resin, squeezing and drying the fabrics, treating them at an elevated temperature and soaping the fabrics thus treated.

In accordance with this invention, there is provided a method of finishing knitted or woven fabrics of polyamides or polyesters which affords excellent soil resistance, particularly to the soiling by contact with dirt under dry conditions, as well as to the resoiling in laundering, and excellent fastness against laundering and drycleaning, free from any adverse effect on the soiling by other types of dirt.

The method of this invention essentially comprises a process comprising padding knitted or woven fabrics of polyester or polyamide fibers in a treating bath containing 2-10 percent by weight of a polymer hydrosol such as polymethacrylic acid, polyvinyl alcohol or carboxyl methyl cellulose in the form of an aqueous colloidal dispersion, 0.1-4.0 percent by weight of precondensate resin of cyclic ethyleneurea and/or melamine-formaldehyde resins, and an acidic catalyst for these resins, squeezing the treated fabrics with a mangle at a pickup of 40-100 percent, drying the squeezed fabrics at 80.degree.-110.degree. C. and subjecting the fabrics to a high-temperature treatment at 140.degree.-170.degree. C. for 30-40 seconds; and washing the resultant fabrics with an aqueous solution containing anionic and/or nonionic detergent maintained at above 40.degree. C., drying and finishing.

In the padding described above, some cationic softening agents such as an acrylamide softening agent may be added to said treating bath in a small amount, e.g., less than 2 percent by weight calculated as a solid component, for the purpose of obtaining a soft touch of the treated fabrics as well as further enhancing the soil resistance.

The knitted or woven fabrics treated as mentioned above exhibit an excellent activity to prevent soils from adhering by contact under dry conditions as well as a good soil-resistant activity to resoiling in washing at home or in drycleaning, and also show excellent fastness against washing and drycleaning.

The principle of the soil-preventing mechanism of the present invention has not been completely clarified theoretically, but it may be believed that the cleavages on the surface of the said fibers into which soils may adhere are previously sealed with fine particles of a colorless polymer to form a barricade against soils thereby preventing adhesion of soils by contact, and the fine particles of the said polymer are simultaneously fixed in the cleavages on the surface of the said fibers chemically and physically so that the barricade is kept resistant to soils in washing. Then, by soaping the fabrics further, not only the quality of the processed article is improved by removal of the excess fine particles of the polymer settled on the surface of the treated fabrics, but also the remarkably durable resistance to soils by contact can be obtained by removing the unreacted precondensate.

In the padding of the method of the present invention, the particle size of the polymer hydrosol is a very important factor and the particles having a size of about 0.5 .mu. give the most effective soil resistance. In practice, it is necessary to use the polymer hydrosol having the particle size ranging from 0.05-5.0 .mu..

The polymer hydrosols referred to herein designate those having particle sizes as set forth above, thus, they are somewhat different from those polymer hydrosols generally and commonly referred to. Namely, a colloid or sol generally meant involves the particle sizes ranging from an upper limit of about 0.2 .mu. to a lower limit of about 5 m.mu., thus, the polymer hydrosol referred to herein designates such colloid or sol involving particle sizes near the upper limited mentioned above, or very fine suspension or dispersion.

Such polymer hydrosols as used herein may be prepared relatively easily, for example, by copolymerizing methacrylic acid with a hydrophilic comonomer or by finely dispersing such hydrophilic material in polymethacrylic acid. Alternatively, when using water-soluble polymers such as polyvinyl alcohol or carboxy methyl cellulose, the hydrosols may be prepared according to such procedures as partial formalization, incomplete saponification, partial conversion into metal salts, or the like.

The deviation of the particle size distribution in the polymer hydrosol used in the method of this invention from the range set forth above inevitably leads to fatal results such as very unsatisfactory soil resistance, adversely affected touch and very poor resistance to washing of finished fabrics.

If the soil resistance were brought about by filling with fine particles, there might be used fine particles of an inorganic material such as SiO.sub.2, however, in reality, there can be obtained merely a temporary effect with these particles. Even if the resin of the present invention is used together with such inorganic materials, there cannot be achieved such a durable soil resistance as that obtained by using the polymer hydrosol of the present invention.

The resins used together with the polymer hydrosol not only affect substantially the durability of the soil resistance of the treated fabrics but also influence directly the soil resistance itself. Moreover, the combination of the polymer hydrosol and the resin is very essential and an indispensable factor in the present invention. The compatibility of the hydrosol with various resins was examined completely, e.g., with respect to water-soluble polyurethane resins, methylated methylol-melamine primary condensation resins, melamine-formaldehyde resins, cyclic ethyleneurea resins, polyacrylic ester resins, polyvinyl acetate resins, polyacrylamide resins, polyethylene resins, silicon resins, phenol resins, oil-soluble polyurethane resins, oil-soluble polyacrylic resins, and isocyanate resins. However, only cyclic ethyleneurea resins and melamine-formaldehyde resins were found to be suitable for the purpose of this invention. When employing these resins together with the polymer hydrosol, the soil resistance of the treated fabrics is increased and is given durability, that is, the soil resistance is not reduced after laundering and drycleaning.

The other resins used together with the polymer hydrosol cannot give such good results. For example, such treatment results in an insufficient adhesive effect on polyesters or polyamides, inferior fastness to washing and drycleaning, and formation of a very tacky film of the resins on which dirts adhere. The adhesive effect and the amount of the resin employed together with the polymer hydrosol greatly affect the soil resistance. An insufficient adhesive effect and tackiness of the film give defects as described above, while, the use of a resin having a higher adhesive effect in an excess amount results in depositions of both the polymer hydrosol and the resin in places other than cleavages on surface of the fibers, and the deposit gives a negative influence on the soil resistance and also gives a rough touch. That is, there are close relations among the types of fibers, cleavage filler and resin used together with the filler. It is necessary that such resin is hard and does not yield tackiness, but possesses an adequate adhesive property. Fine particles other than those of polymer hydrosol, such as silicate, are not suitable as previously described because a suitable resin used together therewith has not been found as yet.

When treating the fabrics with cyclic ethyleneurea resin or melamine-formaldehyde resin along, a remarkable soil resistance cannot be obtained, but a resistance slightly better than that obtained usually may be recognized. When treating the fabrics with cyclic ethyleneurea resin and/or melamine-formaldehyde resins and then treating with the polymer hydrosol, there are gained the soil resistance and its durability similar to those obtained by treating with both above-mentioned agents together.

When treating the fabrics with each of the polymer hydrosol, ethyleneurea resin or melamine-formaldehyde resin of the present invention, respectively alone, the resulting soil resistance and durability thereof is obviously lower than those obtained by treating the fabrics with these agents all together. Considering these facts, it is presumed that there occur some physical and chemical changes to improve the soil resistance and its durability when using these agents together. As previously explained, even when using cyclic ethyleneurea resin or melamine-formaldehyde resin together with fine particles such as SiO.sub.2 which have been considered to have the soil-resisting activity, the soil resistance and durability thereof may not be improved. That is, the increase in the soil resistance and its durability cannot be obtained by using cyclic ethyleneurea resin or melamine-formaldehyde resin together with an already known agent for soil resistance other than the polymer hydrosol of the present invention. Therefore, a durable soil resistance can be gained only by using cyclic ethyleneurea resin and/or melamine-formaldehyde resin together with the polymer hydrosol of the present invention.

The amount of the polymer hydrosol used is in the range of 2-10 percent by weight calculated as concentration of the solid component; and an amount less than specified above only affords insufficient soil resistance. The use of the polymer hydrosol with a higher concentration should be avoided because of sedimentation of the excess fine particles on the surface of the treated fabrics which degrades appearance of the knitted or woven fabrics, and also causes falling off of the fine particles upon handling.

The resin in an amount of less than 0.1 percent by weight calculated as the concentration of the solid component hardly affords a sufficient durability of the soil resistance of the treated fabrics.

A softening agent can be added to the treating bath, as described above, for the purpose of adjusting the touch of the finished fabrics, but, since the soil resistance tends to be greatly deteriorated by the addition of an anionic or ampholytic surfactant, only a specific type of cationic surfactants such as the acrylic amide softening agent can be employed in practice.

The high-temperature treatment after drying is substantially similar to the curing process in the conventional resin processing of fabrics known heretofore, and it is indispensable for obtaining a sufficient durability. The treatment should be performed at temperatures in the range of 140.degree.-170.degree. C., and lower temperatures than specified above only afford an insufficient durability, while higher temperatures leads to deterioration in the properties of the finished fabrics, such as dyeing fastness, thus, the temperature should be maintained in the range set forth above.

A brief explanation has been given above with regard to the soaping in the posttreatment, and so far as the detergent used therefore is concerned, either anionic or nonionic surfactants may be employed, and the most important point in this treatment is to use the detergents adequately and sufficiently to remove the excess fine particles of the high polymer and the unreacted precondensate from the surface of the finished fabrics.

EXAMPLE 1

A dyed cloth of woolly Tetron (polyester) fabrics was padded in a bath obtained according to the following formulation with 70 percent pickup, dried at 105.degree. C., and cured at 150.degree. C. for 40 seconds. Then, soaping in a bath of 3 g./liter of a sodium sulfate of higher alcohol manufactured by Daiichi Kogyo Co. was carried out at 60.degree. C. for 20 minutes with a winch, followed by water rinsing, drying and finishing. The soil resistance of the treated cloth is shown in table 1.

Components Aqueous colloidal dispersion of polymethacrylic acid in a concentration of 20 % by weight 10 parts Precondensate of cyclic ethyleneurea in a2 parts ration of 50 % by weight Organic amine catalyst in a concentration of 20 % by weight 0.2 part Acrylic amide softening agent in a concentration of 60 % by weight 3 parts Water 84.8 parts --------------------------------------------------------------------------- Table 1

soil adsorption Resoiling Resoiling by contact (A) (B) __________________________________________________________________________ Untreated cloth 65 % 40 % 95 % Treated cloth 10 % 35 % 50 % Treated cloth after dry-cleaning five times 15 % 37 % 58 % __________________________________________________________________________

Soil adsorption by contact in table 1 was measured as follows:

The soils in a home vacuum cleaner were collected and filtered through cloth to obtain soil powder, which was used as a soiling agent. The agent and cloth specimens were weighed so that the weight ratio may be 1:2, and were put together into a polyethylene bag blown 200 times with air, and sealed; then, the bag was shaken up in a tumbler drier for 30 minutes. The specimens were removed and the surfaces were lightly padded three times by hand. Then, the soil degree of the surface of the specimen was measured.

Resoiling (A) was measured as follows:

A soiling agent was prepared by mixing the soils collected from a home vacuum cleaner employed above with an oil mixture consisting of 15 percent stearic acid, 15 percent oleic acid, 15 percent hardened oil, 15 percent olive oil, 10 percent cetyl alcohol, 25 percent solid paraffin, and 5 percent cholesterol, in a ratio of 1:1; 20 grams of the soiling agent were weighed, and after adding 3 grams of an anionic detergent, a domestic detergent manufactured by Kao Soap Co., the mixture was mixed with 1,000 cc. of water. Into the thus-prepared bath, cloth specimens were immersed and stirred at 40.degree. C. for 10 minutes, water rinsed, and dried. The soil degree of the soiled cloth specimen was measured.

Resoiling (B) was measured as follows:

Cloth specimens were immersed and stirred in an aqueous bath consisting of 1 gram of carbon black, 9 grams of olive oil, and 20 g./liter of a sodium sulfate of higher alcohol manufactured by Daiichi Kogyo Co., at 50.degree. C. for 5 minutes, water rinsed and dried. The soiled specimens thus treated were then observed.

The soil degree was measured by using a spectro-reflectometer. The reflectivity of the magnesium oxide plate at the dominant wavelength of 530 m.mu. was assumed as 100 and the reflectivity of cloth specimen was measured three times for piled six specimens, and the average soil degree was obtained according to the following equation:

R.sub.o - R.sub.s / R.sub.o .times. 100= Soil degree

wherein

R.sub.o : the reflectivity of the specimen before soiled;

R.sub.s : the reflectivity of the specimen after soiled.

EXAMPLE 2

A dyed cloth of Tetron Astralen Jersey was padded in a bath of the following formulation, dried, cured at 160.degree. C. for 30 seconds, and then soaped with 3 g./liter of a nonionic detergent manufactured by Daiichi Kogyo Co., at 60.degree. C. for 20 minutes with a winch, dried and finished. The soil resistance of thus-treated specimens is shown in table 2.

Components Colloidal dispersion of polyvinyl alcohol in a concentration of 10 % by weight 40 parts Precondensate of a melamine-formaldehyde resin in a concentration of 50 % by weight 3 parts Ammonium chloride (catalyst) 0.1 part Water 56.9 parts --------------------------------------------------------------------------- Table 2

Soil Degree Soil adsorption Resoiling Resoiling by contact (A) (B) __________________________________________________________________________ Untreated cloth 62 % 45 % 93 % Treated cloth 14 % 30 % 52 % Treated cloth after washing with an electric washing machine 20 % 30 % 60 % __________________________________________________________________________

EXAMPLE 3

A dyed Nylon elastic fabric (cashmere) was padded in a 3 percent solution of precondensate of cyclic ethyleneurea (50 percent) and dried. The said fabric was padded in a bath of the following formulation, dried, soaped with 3 g./liter of the sodium sulfate of a higher alcohol referred to hereinbefore and 1 g./liter of the nonionic detergents referred to hereinbefore at 60.degree. C. for 20 minutes with a winch, and then water rinsed and dried to be finished.

Components Aqueous colloidal dispersion of Poly-methacrylic acid in a concentration of 20 % by weight 10 parts Aqueous colloidal dispersion of carboxymethyl cellulose in a concentration of 10 % by weight 10 parts Precondensate of ethyleneurea in a concentration of 50 % by weight 2 parts Precondensate of melamine-formaldehyde resin 1.5 parts Organic amine catalyst in a concentration of 20 % by weight 0.5 parts Water 76 parts

The soil resistance of the treated cloth specimen is shown in table 3. --------------------------------------------------------------------------- TABLE 3

Soil adsorption Resoiling Resoiling by contact (A) (B) __________________________________________________________________________ Untreated cloth 72 % 28 % 89 % Treated cloth 16 % 18 % 72% Treated cloth after washing 15 times 21 % 21 % 75 % __________________________________________________________________________

EXAMPLE 4

A scoured woolly Tetron fabric (cashmere) was padded in a bath of the following formulation and after drying, cured at 160.degree. C. for 40 seconds; then, it was dyed at an elevated temperature under a high pressure, as usual, and dried to be finished.

Components Aqueous colloidal dispersion of polymethacrylic acid in a concentration of 20 % by weight 15 parts Aqueous colloidal dispersion of polyvinyl alcohol in a concentration of 5 % by weight 5 parts Precondensate of cyclic ethyleneurea in a concentration of 50 % by weight 3 parts Organic amine catalyst in a concentration of 20 % by weight 1 part Water 76 parts

The soil resistance of the said fabric was excellent as seen in table 4. --------------------------------------------------------------------------- TABLE 4

Soil adsorption Resoiling Resoiling by contact (A) (B) __________________________________________________________________________ Untreated cloth 67 % 37 % 96 % Treated cloth 45 % 30 % 70 % Treated cloth after washing 10 times 47 % -- -- Treated cloth after dry-cleaning 10 times 46 % -- -- __________________________________________________________________________

The washfastness of the said fabric was measured as follows:

The fabric was treated 10 times in a cycle consisting of stirring in an electric washing machine in a bath containing 2 g./liter of an anionic detergent, at 40.degree. C. for 10 minutes and water rinsing for 5 minutes. The fastness to drycleaning was measured after treating the fabric similarly to the treatment in a usual laundry.

The fabrics treated according to the present invention have other advantageous properties such as an excellent resistance to pilling, which is one of the defects of synthetic fibers.

Claims

1. A method of imparting a durable soil-resistant finish to synthetic fabrics selected from the group consisting of polyamide and polyester fabrics comprising padding the fabrics in a treating bath consisting essentially of 2-10 percent by weight of a polymer hydrosol selected from the group consisting of polyvinyl alcohol and carboxymethyl cellulose in the form of a colloidal dispersion, the particles of said hydrosol having a particle size in the range of 0.05-5.mu.; 0.1-4.0 percent by weight of precondensate resin of at least a member selected from the group consisting of cyclic ethyleneurea and melamine-formaldehyde resins, and an acidic catalyst for these resins, squeezing the treated fabrics with a mangle at a pickup of 40-100 percent, drying the squeezed fabrics at 80.degree.-110.degree. C. and subjecting the fabrics to a temperature of from 140.degree. to 170.degree. C. for 30 to 40 seconds; washing the resultant fabrics with an aqueous solution containing a detergent

2. A method of claim 1, wherein the particles of said hydrosol have a

4. A method of claim 1, wherein the hydrosol is a carboxymethyl cellulose.

6. A method of claim 1, wherein the hydrosol is a melamine-formaldehyde

7. A synthetic fabric selected from the group consisting of polyamide and polyester fabrics which has been treated by the method of claim 1.