SCOPE OF APPLICATION

The present invention concerns a method and an installation for the production of viscose rayon directly dyed in mass in two colours simultaneously, obtaining viscose rayon with contrast and gradating colours or colour mixtures.

PREVIOUS STATE OF THE TECHNOLOGY

In general, coloured viscose rayon can be obtained through surface dyeing of the finished rayon, or by means of the method called dyeing in mass - being dyeing of viscose fibers and rayon as early as the process of their manufacture. The dyed in mass rayon stands out with greater brightness, saturation, brilliance and colour fastness compared to the surface dyed ones.

There is a method for the manufacture of dyed in mass viscose rayon, which in general consists in the following:

Firstly, the initial (cellulose) pulp undergoes the so-called mercerization, being processing 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 strictly required and specified parameters, is fed under pressure for spinning.

For the production of viscose rayon dyed in mass, to the viscose solution ready for spinning, a preliminarily prepared in an individual dyeing installation pigment suspension made of one or a couple of pigments is added. The required quantity of the suspension is dosed into the viscose, mixed and homogenized with it , so that the pigment particles be distributed uniformly through the entire volume of this solution. The dyed and homogenized cellulose solution, with uniformly distributed pigment or pigment particles throughout its entire volume, is fed under pressure through a pipe collector and dozed by means of dozing pumps to the spinnerets of the spinning machine

The dyed in mass viscose solution by means of dozing pumps passes through the spinneret holes into a spin bath, where as a result of the chemical reactions in course, the dyed in mass cellulose transforms into fibres.

Leaving the spin bath, the freshly-spun cellulose is passed to the placed in each working position first and second spinning devices, and then transported and arranged in a centrifuge at the same working position. When the centrifuge is filled up to a specific volume, the rayon fiber between the first and the second spinning device is interrupted and wound only on the first spinning device. Meanwhile, the first centrifuge 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 fiber from the first spinning device is again transferred to the second spinning device from where it is led to the centrifuge giving start to the production of the next rayon cake.

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 obtained rayon cake as a semi-finished product is then dried, conditioned, rewound, subjected to quality control inspection and packaging as a finished product.

The disadvantage of this method of application is that only one type and only one colour of viscose rayon on all working positions of a spinning machine can be produced simultaneously.

In the established practice, there is an installation for production of viscose rayon directly dyed in mass including the following units, connected serially for performance of a range of specified technological operations: mercerization unit, aging unit, unit for temperature reduction, a dosing unit for the amount of the alkali cellulose needed for the production of one batch of rayon; carbon-disulphide treatment unit - treatment of the alkali cellulose with carbon-disulphide to obtain cellulose xanthate, units for mixing of the cellulose solution from one batch to the one from the previous and the following batch to homogenization and deaeration, filtering unit for removal of the impurities.

In order to obtain coloured rayon, in a connected to the spinning machine individual dyeing installation a pigment suspension is preliminarily prepared, which for the planned production cycle is stored in a special tank, it is dosed by means of a pump into the viscose and the mixture enters a homogenizer and thus the pigment or pigment particles are distributed uniformly throughout the entire volume of the viscose solution. The dyed after the homogenization cellulose solution is fed under pressure through a pipe collector for spinning to the spinning machine. To the pipe collector are joined a definite number of working positions. Through a separate for each working position dosing pump, the viscose solution is fed to the spinnerets. The dosing pumps, powered by a common power shaft, dose for spinning one and the same amount of undyed or dyed in mass viscose to each spinneret, respectively towards every working position. After flowing out from the spinneret holes the freshly-spun viscose rayon, dyed in mass, through the spinning devices is transported and arranged in the centrifuge. When it is filled up to a specific volume, the rayon fiber between the first and the second spinning device is interrupted and wound only on the first spinning device. Meanwhile, the centrifuge at this working position 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 fiber from the first spinning device is again transferred to the second spinning device from where it is led to the centrifuge, giving start to the production of the next rayon cake.

This is followed by washing procedures where in a washing unit the freshly-spun viscose 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 obtained semi-finished product is centrifuged, dried, conditioned, wound and sent for quality control inspection to be packed as a finished product and then stored.

Since the dosing pumps are actuated by a common power shaft, to all working positions one and the same quantity of undyed or dyed in mass viscose is fed for spinning, which means that from all working positions of the classical spinning machine is simultaneously being produced only one type and only one colour of viscose rayon.

Similar installations are deemed to be efficient in the production of large batches of dyed in mass rayon in one colour . With time and mostly due to a change in the demand and the market conditions, this concept had to be revised. The development of sufficiently perfected systems for dosing of the pigment suspensions, and the improvement of the measuring devices provided for possibilities to construct smaller systems for dyeing in mass to obtain the required colour uniformity in the production of smaller batches of coloured viscose rayon. The production of small quantities of dyed in mass rayon though continues to be burdened by bigger expenses due to the frequent change of colours and the related to it logistic, technological and technical operations and cleanings.

The purpose of the invention is to suggest a method and an installation for direct production of viscose rayon dyed in mass simultaneously in two contrasting or gradating colours or colour mixtures on one and the same spinning machine.

NATURE OF THE INVENTION

According to the invention, a method and installation for direct production of bicolour dyed in mass viscose rayon is suggested, including the following stages: the initial (cellulose) pulp undergoes mercerization, processing with a concentrated solution of sodium hydroxide (NaOH), resulting in alkali cellulose, which afterwards is subjected to destruction, i.e. aging, to decrease the degree of polymerization. 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 viscose solution, with strictly required and specified parameters, is mixed with a preliminarily prepared pigment suspension composed of one or a couple of pigments, the mix is homogenized causing the pigment particles to be distributed uniformly throughout the entire volume of this solution, which under pressure is fed for spinning through the first pipe collector.

According to the invention a second spinning line is introduced to the same spinning machine, including a second pipe collector, as the viscose solution dosing pumps joined to the second pipe collector are actuated by the same electromotor and common power shaft powering the dosing pumps of the first pipe collector and operating synchronously with it. The cellulose solution is fed under pressure to the second pipe collector appurtenant to a second, independently operating, individual dyeing installation. According to the invention, the dosing pumps feeding viscose for spinning to the spinnerets are thus supplied with viscose for spinning from the separate pipe collectors in two dying lines, as a pair of neighbour working positions are supplied respectively by the first and the second pipe collectors one after another, as a result of which in the two neighbour working positions differently coloured viscose fiber is directly spun. Thus, with the introduction of the second line for dying in mass, simultaneously in half of the working positions a viscose solution in one colour is spun, and in the other half- dyed in another colour .

Furthermore, according to the invention, the spun on the neighbour working positions differently dyed-in-mass viscose fibers rather than being processed independently by the first spinning devices of the respective working positions, are joined and passed on together to only the first spinning device of the first working position. Then the two already combined differently coloured fibers are transferred together to the second spinning device of the first working position and after that in the first centrifuge. As a result of this innovative spinning, the bicolour fiber is obtained directly still at the first spinning device, and after adjustment of the physical and mechanical parameters, the bicolour fiber is passed only to the first centrifuge from which after a definite period of time a viscose rayon cake dyed in two colours simultaneously is taken out. After a careful selection of colours and recipes, including white colour, are obtained contrasting or a mixture of gradating colours.

Further, the classical washing procedures are applied 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 obtained semifinished product is dried, conditioned, rewound and subjected to quality control inspection before being packed as a finished product.

The installation, performing the method according to the invention, includes the following units, connected serially to carry out the indicated technological operations: mercerization unit, aging unit, temperature reduction unit, a dosing unit for the amount of the alkali cellulose needed for the production of orte batch of rayon. In a carbon-disulphide treatment unit the alkali cellulose is treated with carbon-disulphide to obtain cellulose xanthate. In separate units the cellulose solution from one batch is mixed and homogenized with the one from the previous and the following batches, deaerated and then cleared from impurities in a filtering unit.

In order to obtain dyed-in-mass rayon, to the spinning machine is connected a first individual dyeing installation for individual or group mass dying, including a storage tank for a preliminarily prepared pigment suspension, a pigment suspension dosing pump and a homogenizer, connected to the first pipe collector of the spinning machine to which a specific number of working positions are joined. According to the invention, to the first pipe collector of the spinning machine a second pipe collector for viscose is added, as the viscose solution dosing pumps, joined to the second pipe collector, are actuated by the same electromotor and a common power shaft which powers also the dosing pumps to the first pipe collector operating synchronously with it. The second pipe collector is connected to a second independently operating individual dyeing installation, as the dosing pumps feeding viscose for spinning to the spinnerets, for each pair of neighbour working positions are supplied with viscose for spinning by the different pipe collectors in the following way: the dosing pump at the first working position is fed with viscose by the first pipe collector, and the neighbour to it, i.e. the dosing pump at the second working position is supplied with viscose by the second pipe collector. The same is repeated for all other pairs of working positions. By this spinning method in half of the working positions a dyed in mass viscose solution in one colour is spun, and in the other half - a dyed in mass solution in another colour, thus obtaining a bicolour viscose fiber.

Additionally, according to the invention, the spun in the neighbour working positions differently dyed fibers rather than being taken independently by the first and the second spinning devices, are joined and passed on together to only the first spinning device at the first spinning position. Then, the two already combined differently dyed rayon fibers are transferred together to the second spinning device of the first working position and to the centrifuge at the same first working position, thus obtaining the bicolour fiber still on the first spinning device, and after the adjustment of the physical and mechanical parameters, is transferred into a centrifuge from which after a certain period of time a rayon cake directly dyed in two colours is taken out.

Further, the installation includes connected serially the already known washing units - for treatment of the freshly-spun viscose rayon with various solutions to clear the residues of the spin bath, the sodium sulfate and sulfur resulted from the chemical reactions during spinning; a unit for centrifugation of the already washed semi-finished product, a drying unit, a conditioning unit, a rewinding unit, a quality control unit and a storage unit.

The advantage of the suggested method and installation is that the bicolour viscose rayon is produced directly during spinning, which enhances the possibilities for the manufacture of fancy textiles and knitted articles, as well as different types of fancy yarns. In addition, there are practically no limitations as to the type or the colour mixtures for the application of this method. SHORT DESCRIPTION OF THE FIGURES ENCLOSED

Figure 1 illustrates the sequence of the processes in the classical production of dyed in mass viscose filament rayon .

Figure 2 presents an individual dyeing installation used for viscose dyeing in mass.

Figure 3 presents a part of the installation for the production of dyed in mass viscose rayon, illustrating the classical technology for spinning of coloured in mass viscose rayon.

Figure 4 presents a part of a unit for spinning of bicolour viscose rayon according to the invention.

Figure 5 presents a part of the installation for production of bicolour viscose rayon, according to the invention, showing an innovative way of spinning at two neighbour working positions of the spinning machine resulting into the production of bicolour viscose fiber directly dyed in mass .

MODEL PERFORMANCE OF THE INVENTION

According to Figure I, the installation for the production of dyed in mass viscose rayon includes the following units, where the processes for obtaining coloured viscose rayon are realized: unit 1 for mercerization - treatment of the initial pulp (cellulose) with a concentrated solution of sodium hydroxide, unit 2 - for aging where as a result of the process of destruction alkali cellulose is obtained, i.e. the degree of polymerization is decreased, unit 3 - temperature reduction, unit 4 - dosing of the alkali cellulose amount for the production of one batch of viscose, unit 5 - for carbon-disulphide treatment of the alkali cellulose to obtain cellulose xanthate, units 6 and 7 - for mixing of the cellulose solution of one batch to the one from the previous and the following batch and deaeration, unit 8 - filtering to remove the impurities.

Unit 9, for the preparation of a dyeing suspension, is connected to spinning machine 10. After the spinning, the freshly-spun viscose rayon is treated in unit 12 with various solutions, prepared in unit 13 to remove the residues from the spin bath 11 after the spinning.

Further, following the process for obtaining coloured viscose rayon, serially connected are units 14, 15, 16, 17 and 18 for centrifugation, drying, conditioning, rewinding, quality control inspection and packing as finished production to be stored in unit 19.

In order to obtain coloured rayon, to the spinning machine 10 an individual dyeing installation 10-1 is connected for individual or group dyeing in mass. As shown in Figure 2, it includes a pigment suspension storage tank 30, pigment suspension dosing pump 31, a control unit 34 for the dosing pump 31, a homogenizer 32, where the pigment(s) particles are mixed and distributed uniformly throughout the entire volume of the viscose solution and geared electromotors 35 to the homogenizer 32 and the suspension tank. From the main pipe collector 36 the cellulose solution passes into the homogenizer 32 through a local pipe line 37. The already dyed after the homogenization solution fills up under pressure a pipe collector 38, which supplies the working positions of the spinning machine 10.

Then a part of the installation for dyed-in-mass viscose rayon production according to the classical technology for spinning is presented on Fig.3 . Dozing pumps 22.1 and 22.2 doze the coloured viscose solution respectively to the first and the second working positions. The freshly-spun through spinnerets 26 viscose rayon at the presented two working positions passes through the first - 27.1 and 27.2 and the second 28.1 and 28.2 spinning devices to the first and second centrifuges 29.1 and 29.2 where the freshly-spun coloured rayon is collected.

According to the invention, a part of the unit for spinning of bicolour viscose rayon is presented on Fig 4, where a new pipe collector is added. The first and the additional second pipe collector 38.1 and 38.2 with differently dyed viscose solution, supply respectively dosing pumps 22.1 and 22.2 at the first and second working positions. According to the invention, dosing pump 22.1 is fed by the first pipe collector 38.1, and dosing pump 22.2 - by the second pipe collector 38.2.

A part of the installation for production of bicolour viscose rayon and the innovative procedure for spinning of bicolour viscose rayon according to the invention, showing two working positions for bicolour rayon spinning is presented in / Fig. 5/. According to the invention dosing pump 22.1 is fed with viscose for spinning by the first pipe collector 38.1, and dosing pump 22.2 - by the added second pipe collector 38.2. The dyed in mass viscose fibers from both working positions are joined in the first spinning device 27.1 at the first working position and by means of the second spinning device 28.1 at the same working position are passed to the centrifuge 29.1 of the first working position in order to obtain a rayon cake composed of two differently dyed viscose fibers.

The processes running in the suggested installation and method for production of bicolour viscose rayon, dyed in mass according to the invention, are as follows:

The preliminarily prepared pigment suspension, which during the production cycle is stored in tank 30 (Fig.2), is dosed using pump 31 to the viscose and the mixture is passed into homogenizer 32 (Fig. 2), where the particles of the pigment(s) are distributed uniformly throughout the entire volume of the viscose solution. The already dyed after the homogenization cellulose solution is fed under pressure to pipe collector 38 (Fig.2) of the spinning machine, to which a specific number of working positions are added. Through individual for each working position dosing pumps, the viscose solution is fed under pressure to the spinnerets.

According to the invention, to the already existing pipe collector 38.1 is introduced a second one 38.2, combined with a second installation for individual dyeing in mass, actuated in the same mode as the first pipe collector, Fig.4. The cellulose solution from pipe collector 37 under pressure is passed simultaneously to two installations for individual dyeing. The dyed in one colour viscose solution is passed to the first pipe collector 38.1, and the dyed in the other colour - to the second pipe collector 38.2, Fig.4. According to the invention, dosing pumps 22.1 and 22.2, supplying viscose for spinning to the spinnerets, are fed with viscose for spinning by the different pipe collectors in the following way: dosing pump 22.1 is supplied with viscose by the first pipe collector 38.1, and the neighbouring to it pump 22.2 which corresponds to working position 2, is fed with viscose by the second pipe collector 38.2. The same is repeated for working positions 3 and 4 and for each successive pair of working positions. The realization of this innovative scheme enables to half of the working positions of the spinning machine to be supplied with undyed or dyed in one colour viscose, and to the rest of every other position - viscose dyed in another colour. In practice this means that in the neighbour spinning positions a differently dyed viscose fibers is being spun.

Passed through the spinnerets 26, the cellulose solution is led into a spin bath 11, where as a result of the chemical reactions in course the cellulose from cellulose solution is transformed into rayon fibers. Then the freshly-spun cellulose is transferred and arranged in a centrifuge 29.1. When it is filled up to a specific level, the filament between spinning devices 27.1 and 28.1 is interrupted and wound only on the first spinning device 27.1. Meanwhile, the first centrifuge 29.1 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 filament from spinning device 27.1 is again transferred to spinning device 28.1 from where it is led to centrifuge 29.1, giving start to the production of the next rayon cake.

The adjustment of the suspension dosing pumps takes place after both pipe collectors are filled up with the cellulose solution and deaerated. The dosing pumps in the positions with odd numbers are connected and are supplied with viscose by the first pipe collector 38.1. The dosing pumps at the even-numbered positions are connected to the second pipe collector 38.2 and fed with viscose, dyed in a colour different from the one of the viscose in the first pipe collector 38.1. The working positions are consecutively spun observing the fresh -spun rayon fibers spinning mode as shown in Fig.5. The fibers in working positions 1 and 2, dyed in different colours, are joined at the first spinning device 27.1 to the first working position, they are transferred together to the second spinning device 28.1 of the same working position, and transported to the centrifuge 29.1 at the same first working positions. Centrifuge 29.2 at the second working position is not operating. When 29.1 is filled up to a specific volume , the bicolour rayon fiber between spinning devices 27.1 and 28.1 is interrupted, the rayon cake is taken out, and then again through spinning device 28.1 is transferred in the already emptied centrifuge of the same working position 1. These actions are periodically repeated until the production of the planned quantities of bicolour rayon is finished. Spinning device 28.2 and centrifuge 29.2 are not in operation.

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

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

The obtained bicolour rayon cakes are rewound on bobbins with the usual weight and size in the same way and parameters as the rayon cakes produced using the classical dying in mass technology. The quality control of bicolour rayon shade uniformity is carried out in the same way as with the single-colour dyed viscose rayon according to the approved colour standard.

After a careful selection of colours and recipes, including white, contrast and gradating colour mixtures are obtained, which enhances the possibilities for production of fancy yarns and textiles.