METHOD FOR THE MANUFACTURE OF ANTIBACTERIAL VISCOSE FILAMENT RAYON AND A PRODUCT OBTAINED USING THAT METHOD

Abstract

The antibacterial viscose rayon, according to the invention, is used for the manufacture of any type of textile articles, including items intended for medical use, ensuring a more lasting antibacterial and antifungal protection due to the uniform distribution of the antibacterial additive throughout the entire volume of the fibre. According to the invention, immediately before spinning, the viscose is mixed and homogenized with an antibacterial additive, and then spun following the classical procedure: the viscose solution, with required and strictly specified parameters is fed under pressure to the spinnerets of the spinning machine from which the cellulose solution enters a spin bath, where as a result of the chemical reactions in course is transformed into fibres subjected afterwards to a subsequent treatment. According to the invention, in the production of dope dyed antibacterial rayon, into the preliminarily prepared suspension composed of one or a couple of pigments, a specified amount of antibacterial additive is introduced, the obtained mix is homogenized and filtered, and then subjected to the classical stages of spinning and subsequent treatments.

Description

SCOPE OF APPLICATION

The present invention concerns a method for the manufacture of antibacterial viscose filament rayon and a product obtained using that method.

PREVIOUS STATE OF THE TECHNOLOGY

The classical technology for production of viscose rayon has not developed much notwithstanding the long time passed since its creation, as the process itself is very conservative and strongly affected by various external and other factors. In general terms, this classical process of spinning performed by different types of spinning machines consists in the following:

Firstly, the cellulose undergoes the so-called mercerization, being processing of the initial pulp with a concentrated solution of sodium hydroxide (NaOH), resulting in alkali cellulose, which afterwards is subjected to destruction, i.e. aging, where the degree of polymerization is decreased. This is followed by temperature reduction and dosing of the alkali cellulose amount for the production of one batch of viscose. The next stage is carbon-disulphide treatment which causes the alkali cellulose to transform into cellulose xanthate, whose most important property is that it is soluble in diluted solutions of sodium hydroxide. The cellulose solution of one batch is mixed and homogenized with the one from the previous and the following batch, deaerated, and filtered to remove the impurities. Then the already cleared viscose solution, with required and strictly specified parameters, is fed under pressure to the spinning machines. Wet spinning is performed by passing the cellulose solution, by means of a dosing pump, through the spinneret holes into the spin bath, where as a result of the chemical reactions the cellulose from the cellulose solution transforms into fibers.

This is followed by washing procedures where the freshly-spun sour rayon is treated with various solutions to clear the residues of the spin bath, the sodium sulfate and sulfur resulted from the chemical reactions during spinning.

The washed semi-finished product is then dried, conditioned, rewound and sent for quality control inspection and packaging as a finished product.

In the production of dope dyed viscose rayon to the viscose solution, prepared for spinning, a preliminarily prepared pigment suspension made of one or a couple of pigments is added. The required quantity of the suspension is dosed into and mixed to homogenization with the viscose, in order the pigment particles to be distributed uniformly through the whole volume of this solution. To the dyed and homogenized solution of the cellulose are further applied the classical stages of spinning, washing, drying, conditioning, rewinding and sent for quality control inspection and packaging as a finished product.

Due to specific needs of the textile industry, textiles with new consumer qualities are required, for example such with a specific degree of antibacterial and antifungal protection. They are obtained by means of an antibacterial additive, which is usually a solution or suspension of the antibacterial substance(s) in water in the presence of specific amounts of equalizers, dispersing agents, wetting agents, softeners, and etc.

In order to obtain antibacterial or antifungal protection, the following types of treatment are known from the established practice:

Textile application by pad—usually carried out on Foulard through an aqueous pad bath. The bath in these cases should be perfectly prepared immediately prior to use, strictly observing the obligatory requirement for continuous stirring in order to maintain a constant degree of dispersion of the dispersion system, in case the antibacterial additive is in the form of dispersion. The usual concentration of the additive used is 0.14 to 0.70% of the fabric weight to be treated, as the treatment itself can be performed by adding to the bath not only the antibacterial additive, but also the rest of the finishing preparations. In such cases though, it is required that preliminary tests be run for determining the compliance of the antibacterial additive with the other substances. The fabric with the antibacterial additive applied is immediately dried and thus the antibacterial additive remains more or less fixed on its surface, i.e. it doesn't reach the cross section of the various fibres used for the manufacture of the fabric. How long the antibacterial effect will last can be determined after performing a couple of washing cycles assessing after each of them the degree of change of the antibacterial protection.

Textile application through exhaust—can be applied to fabrics, especially the ones made only from synthetic fibers. This method also uses a bath in proportion 10:1 or less, at pH 4-8 and exhaust time of at least 30 min. at a temperature of at least 80° C. The use of lower temperatures can significantly reduce the exhaust efficiency. In this method the application of the antibacterial additive is also only on the surface of the woven or knitted fabric. The additional use of equalizers can contribute to the uniform distribution of the antibacterial additive across the entire surface treated.

The main disadvantages of these methods of antibacterial additive application is that the duration of the effect of the antibacterial additive depends solely on the stability of its fixing to the treated surface, as no uniformity of the antibacterial protection can be guaranteed.

Besides, the antibacterial additive is absorbed partially, i.e. a big portion of it remains in the bath after treatment, as the same is then discharged into the waste water. Therefore, the use of these methods means higher expenses for waste water cleansing, as well as ecological problems.

There is a method for obtaining antibacterial rayon with antifungal and antiseptic properties and light fastness, described in JPH09310235/A/. According to the method, from 5 to 10% composition of inorganic compounds with particle size less than 5 micron is blended with the viscose in a mixer, or in the tank before its deaeration at the stage of homogenization of the separate batches of viscose, or in the viscose tank before its deaeration. The obtained mix after all the successive stages of filtration is passed to the spinning department for spinning. The ceramic composition of inorganic compounds is obtained by homogenizing 20-80% serpentine particles/base material/ with 20-80% silica particles and 10-40% of zinc oxide particles followed by a subsequent sintering of the mix.

The disadvantage of this method is the complication of the other processes of viscose preparation—filtering, ripening and even spinning—due to the high concentration of inorganic particles in the viscose composition introduced too early—at the stage of mixing of the viscose solution with the antibacterial ceramic composition.

Furthermore, the early introduction of the antibacterial ceramic additive requires separate flows of movement of the untreated and the mixed with the antibacterial component viscose to the spinning machines, i.e. they require separate flow-lines, if both types of rayon are produced simultaneously.

There is a method for obtaining fibres with antibacterial properties, described in patent application JPH17173711/A/ for obtaining fibres with having antibacterial capability, retaining its antibacterial capability even after washed repeatedly, thus useful for sheets and white overalls by imparting in a specific mode viscose rayon with an anion-carrying high molecular substance and a quaternary ammonium salt compound. An anion-carrying high molecular substance is homogeneously dispersed at 0.01-30% in the viscose rayon and a quaternary ammonium salt compound of the formula R1 is a 8-30C saturated or unsaturated fatty acid residue, formula R2 is a 8-30C saturated or unsaturated fatty acid residue or CH3, didccil dimethyl ammonium chloride is held at 0.001-10 wt % on the surface of the viscose rayon. The fibres obtained by means of this method have the flaws as mentioned above, owing to the surface treatment itself of the already manufactured rayon.

There is a method for the manufacture of fibres with antiseptic properties described in patent application No. CN1779004/A/. The antiseptic additive used is silver mixed with a cellulose sulfonic acid ester. The quantity of the silver is from 0.5% to 5.0% in relation to the weight of the cellulose. This method though is unacceptable for obtaining viscose fibres or rayon, as the silver from the additive reacts with the released during the spinning hydrogen sulphide to silver sulphide, which gives the product a grey shade.

The purpose of the invention is to be suggested a manufacture method for raw bright white and coloured viscose rayon with the aforementioned antibacterial and antifungal properties.

The method developed in accordance with the invention is based on existing classical process of spinning with the addition of more stages, in order to obtain a fibre in which the antibacterial additive is distributed uniformly through the entire volume and cross-section of the rayon. Thus a much more lasting antibacterial and antifungal protection is achieved, without pollution of the waste water.

NATURE OF THE INVENTION

According to the invention, a direct method for direct viscose rayon production with antibacterial properties is suggested, which consists of the following stages:

Firstly, the cellulose undergoes the so-called mercerization, being processing of the initial pulp with a concentrated solution of sodium hydroxide (NaOH), resulting in alkali cellulose, which afterwards is subjected to destruction, i.e. aging, where the degree of polymerization is decreased. This is followed by temperature reduction and dosing of the alkali cellulose amount for the production of one batch of viscose. The next stage is carbon-disulphide treatment which causes the alkali cellulose to transform into cellulose xanthate, whose most important property is that it is soluble in diluted solutions of sodium hydroxide. The cellulose solution of one batch is mixed and homogenized with the one from the previous and the following batch, deaerated, and filtered to remove the impurities. Then the already cleaned viscose solution, with strictly specified parameters, is fed under pressure to the respective number of spinning machines.

According to the invention immediately before spinning, the viscose is mixed with an antibacterial additive, homogenized and spun directly following the classical procedure, that is, the already cleared viscose solution, with strictly specified parameters, is fed under pressure to the spinning machines. Wet spinning is performed by passing the cellulose solution, by means of a dosing pump, through the spinneret holes into the spin bath, where as a result of the chemical reactions the cellulose from the cellulose solution transforms into fibers.

This is followed by washing procedures where the freshly-spun sour rayon is treated with various solutions to clear the residues of the spin bath, the sodium sulfate and sulfur resulted from the chemical reactions during spinning. The washed semi-finished product is then dried, conditioned, rewound and sent for quality control inspection and packaging as a finished product.

According to the invention, in the production of dope dyed viscose rayon to the preliminarily prepared pigment suspension, made of one or a couple of pigments, a specified amount of antibacterial additive is added. Then the required quantity of pigment and antibacterial additive mixed suspension is dosed into and mixed to homogenization with the viscose, in order the pigment particles and the antibacterial additive to be distributed uniformly through the whole volume of the already coloured solution. Wet spinning is performed by passing the already coloured and antibacterial-treated cellulose solution, by means of a dosing pump, through the spinneret holes into the spin bath, where as a result of the chemical reactions the cellulose from the cellulose solution transforms into fibers.

This is followed by washing procedures where the freshly-spun sour rayon is treated with various solutions to clear the residues of the spin bath, the sodium sulfate and sulfur resulted from the chemical reactions during spinning.

The washed semi-finished product is then dried, conditioned, rewound and sent for quality control inspection and packaging as a finished product.

According to the invention, the amount of the antibacterial additive is from 0.01 to 5% in relation to the cellulose quantity in the viscose solution, as in the case of utilization of the additive KW 48 this concentration is from 0.5 to 3.5%.

In addition, according to the invention, the preparation of the antibacterial suspension and its storage are at temperatures ranging from +20° C. to −4° C.

Furthermore, according to the invention the antibacterial suspension is filtered for removal of all particles exceeding the size of 5 microns.

During the performance of the invention, viscose rayon with antibacterial properties is obtained, which can be used for the production of any type of items, including products intended for medical use, as the antibacterial additive is distributed uniformly throughout the entire volume and cross-section of the rayon fibre, which suggests a significantly longer effect, and respectively more lasting antibacterial and antifungal protection.

Besides, the antibacterial additive is 100% utilized and there are no residual and polluting the waste water quantities, which is extremely important from environmental point of view.

In addition to all other advantages, the change of the stage where the antibacterial additive is used gives the possibility for the production of coloured antibacterial viscose rayon by preparing combined recipes for the production of colours, as the antibacterial additive becomes an integral component of the dyeing recipe. The combined pigment and antibacterial suspension is transported to a homogenizing tank and later into the cellulose solution following the innovative mode, and then it is directly subjected to spinning.

SHORT DESCRIPTION OF THE FIGURES ENCLOSED

FIG. 1 illustrates the sequence of the processes of the manufacture of viscose rayon filament according classical technology of manufacturing

FIG. 2 presents dope dyed viscose rayon filament production (10-1) with and without the use of antibacterial additive.

FIG. 3 presents a detailed construction of an original centrifugal spinning machine.

In FIG. 4 a chart presents the recipe for the preparation of the suspension with antibacterial additive, introduced in the cellulose solution in the homogenizer.

In FIGS. 5a and 5b are given the results of external laboratory investigations of antibacterial rayon, manufactured using the method according to the invention.

MODEL PERFORMANCE OF THE METHOD FOR PRODUCTION OF ANTIBACTERIAL VISCOSE RAYON

With reference to FIGS. 1, 2 and 3 a model performance of the method according to the invention is demonstrated.

Firstly, the base cellulose is fed into unit 1 for mercerization—treatment of the initial pulp with a concentrated solution of sodium hydroxide (NaOH), resulting in alkali cellulose, which afterwards in unit 2 is subjected to destruction, i.e. aging, where the degree of polymerization is decreased. In unit 3 temperature reduction takes place, and in unit 4—dosing of the alkali cellulose amount for the production of one batch of viscose. In unit 5 is introduced the next stage—carbon disulphide treatment of the alkali cellulose until obtaining cellulose xanthate, whose most important property is that it is soluble in sodium hydroxide diluted solutions. In units 6 and 7 the solution of cellulose from one batch is mixed and homogenized with the one from the previous and the following batch, deaerated, and then filtered in unit 8 for removal of the impurities.

Then, in case that there is no production of coloured rayon, the viscose solution with requires and strictly defined parameters is fed under pressure to the spinning machines 10 in a pipe collector 38 which is permanently full of cellulose solution under pressure for the prevention of incidence of a gas phase. This collector 38 provides the necessary quantity of cellulose solution to the spinneret for each working position of the rayon spinning machine 10 through the respective dosing pump 22 (FIG. 3). Passed through the spinneret 26 (FIG. 3), the cellulose gets into a spin bath 11 where, as a result of the chemical reactions in course, the cellulose from the cellulose solution is transformed into rayon fibres. Leaving the bath the freshly-spun sour rayon is transported to the centrifuge 29 (FIG. 3). When it is filled up to a specific volume, the fibre between spinning devices 27 and 28 (FIG. 3) is interrupted manually and wound on spinning device 27 only. During that period the centrifuge 29 is stopped, the formed in it rayon cake is taken out and the centrifuge is again put into operation. When the same enters in operating mode, the rayon fibre from spinning device 27 is again transferred to spinning device 28 from where it is led to the centrifuge 29, giving start to the production of the next rayon cake.

Then this is followed by washing procedures in unit 12, where the freshly-spun sour rayon is treated with different solutions, prepared in unit 13, for removal of residues from the spin bath, the sodium sulfate and basic sulfur resulted from the chemical reactions during spinning.

The obtained semi-finished product is then dried, conditioned, rewound and sent for quality control inspection and packaging as a finished product—units 14, 15, 16, 17, 18 and after quality control inspection it is stored in unit 19.

In the production of dope dyed viscose rayon the spinning machine 10 is additionally equipped with an individual or multifunctional system for mass dyeing 10-1 (FIG. 2). In order for such production to be realized, a preliminarily prepared pigment suspension, made of one or a couple of pigments, for one production cycle is transferred and stored in container 30 (FIG. 2).

By means of pump 31 the required amount of the suspension is dosed into the viscose, so the viscose and the pigments are mixed and homogenized in unit 32 (FIG. 2), and as a result the pigment particles are uniformly distributed throughout the entire volume of the already coloured solution. The dyed and homogenized cellulose solution is then fed into a viscose pipe line 38 (FIG. 2) of the spinning machine and passed through the spinnerets into the spin bath in the already described mode.

In the demonstrated performance of the invention for the production of antibacterial viscose rayon by recipe (FIG. 4) the suspension of the antibacterial additive is prepared, i.e. 1.0% in relation to the amount of cellulose to be spun for 24 hours. The calculated quantity of additive is scaled and quantitatively transferred in the suspension preparation container where the required amount of water and other components of the recipe have already been weighted. The prepared suspension is transported to the container 30 of the individual installation for mass dyeing (FIG. 2), after which the feed of the suspension to the homogenizer 32 from the suspension dosing pump 31 is set. This important setting is performed when the viscose pipe collector 38 is filled with the cellulose solution/viscose/ and deaerated. Further follows the spinning as above-described.

After the viscose is mixed with the suspension, whatever it is, as a result of the dilution its parameters are modified:

			Prior to	After
			mixing with	mixing with
			the suspension	the suspension
	viscosity	Sec.	39.0	30.0
	ripening	ml. NH4CL	19.25	17.40
	temperature	° C.	17.0	19.0

The spinning of the viscose solution—antibacterial component complex is performed in the same spin bath, used for spinning of the same viscose solution without such an additive or of the same solution, dyed in mass.

After spinning, the freshly-spun sour antibacterial rayon passes through the processing to which rayon is subjected, spun through all the spinning machines, i.e. these operations are performed in accordance with the approved technological requirements and practice. These treatments include washings with softened water, neutralization with sodium carbonate, desulphoration and again washing with softened water.

The drying and rewinding of the rayon cakes to bobbins with standard weight and size is carried out in the same way and parameters like the rest of rayon yarn manufactured in the classical mode. The only difference is that the rewinding of the antibacterial rayon is performed on separate rewinding machines in order not to mix it with the rest, and it sent to the quality control immediately, after which each bobbin of antibacterial rayon is wrapped in sterile packaging.

The quality control inspection is performed in the same way as with the traditionally manufactured types of viscose rayon.

In FIG. 5b are shown the results from the antibacterial tests of antibacterial rayon, manufactured using the method according to the invention, and in FIG. 5a—the methodology used to determine antibacterial activities, which is not subject of the invention.

The introduction of any type of additives to the viscose solution changes its parameters and especially its ripening speed. That is why, the introduction of the additive in the viscose immediately before its spinning, which is the innovative solution of the suggested method, is one of its essential advantages as compared to the ones already known, because the changes in the parameters of the cellulose solution/viscose/ happen minutes before its direct spinning, which guarantees its stable trouble-free spinning, with no need whatever changes to be made in the rest of the parameters of the spinning process.

Claims

1. Method for the manufacture of antibacterial viscose filament rayon based on following stages: Treatment of the raw cellulose with a concentrated solution of sodium hydroxide, resulting in alkali cellulose which after that is subjected to destruction to reduce its degree of polymerization; reduction of the temperature and dosing of the quantity of alkali cellulose for the production of one batch of viscose; treatment with carbon disulphide until it is transformed into cellulose xanthate which is soluble in diluted solutions of sodium hydroxide, mixing and then filtering for removal of the impurities, deaerating and filtering again after which the already cleared viscose with 8.8% cellulose and 6.4% sodium hydroxide content and ripeness index 18.5-19.5 is fed under pressure to the spinning machines. Wet spinning is performed by passing the cellulose solution, by means of a dosing pump, through the spinneret holes into the spin bath, where as a result of the chemical reactions the cellulose from the cellulose solution transforms into rayon filament yarn; next treatment with various solutions for removal of the residues from the spin bath, resulting from the chemical reactions during spinning; followed by drying, conditioning, rewinding and quality determination, with the main characteristic that antibacterial additive for raw white bright antibacterial viscose filament rayon production is added into ready for spinning viscose, mixed and homogenized with it immediately before its spinning on the spinning machine, after which the rest of the described stages are carried out.

2. A method for the manufacture of antibacterial viscose filament rayon dyed in mass, based on following stages: Treatment of the raw cellulose with a concentrated solution of sodium hydroxide, resulting in alkali cellulose which after that is subjected to destruction to reduce the degree of polymerization; reduction of the temperature and dosing of the quantity of alkali cellulose for the production of one batch of viscose; treatment with carbon disulphide until it is transformed into cellulose xanthate which is soluble in a diluted solution of sodium hydroxide, mixing and then filtering for removal of the impurities, deaerating and filtering again after which the already cleared viscose 8.8% cellulose and 6.4% sodium hydroxide content and ripeness index 18.5-19.5 is fed under pressure to the spinning machines. Wet spinning is performed by passing the dyed in mass cellulose solution, by means of a dosing pump, through the spinneret holes into the spin bath, where as a result of the chemical reactions the cellulose from the cellulose solution transforms into dyed in mass rayon filament yarn; next treatment with various solutions for removal of the residues from the spin bath, the sodium sulphate and the basic sulphur, resulting from the chemical reactions during spinning; followed by drying, conditioning, rewinding and quality determination, with the main characteristic that antibacterial additive and pigment suspension as antibacterial dyed complex for antibacterial and dyed in mass viscose filament rayon production are added together into ready for spinning viscose, mixed and homogenized with it immediately before its spinning on the spinning machine, after which the rest of the above—described operations follows.

3. A method according to claim 1, with the main characteristic that the quantity of the antibacterial additive added Into ready for spinning viscose, mixed and homogenized with it immediately before its spinning on the spinning machine is from 0.01% to 5% in relation to the amount of the cellulose in the viscose solution, respectively in ready made antibacterial rayon filament yarn

4. A method according to claim 1 with the main characteristic that as antibacterial additive ZINC PYRITHIONE is used.

5. A method according to claim 1, with the main characteristic that when antibacterial additive Zinc Pyrithione is added into ready for spinning viscose, mixed and homogenized with it immediately before its spinning on the spinning machine, its amount is between 0.5 and 3.5% in relation to the cellulose content in the viscose solution.

6. Antibacterial viscose filament rayon products row white bright and dyed in mass obtained using the method according to claim 1.

7. Method for the manufacture of antibacterial artificial cellulose fibers with the main characteristic that as antibacterial additive ZINC PYRITHIONE could be used.