Patent Publication Number: US-2022213621-A1

Title: Method for preparing spun leather yarn using leather fiber, and spun leather yarn prepared according to preparation method

Description:
TECHNICAL FIELD 
     The present invention relates to a method for preparing spun leather yarn using leather fiber, and spun leather yarn prepared according to the preparation method. 
     BACKGROUND ART 
     Natural leather is a tough shell wrapping an animal body, and widely used in various fields, such as bags, shoes, furniture, and others, due to its excellent physical properties. Natural leather is separated from the animal body and is manufactured into a product through chemical and physical processes. Among various processes, a process of cutting the natural leather according to a desired design of the product is essential. However, the cutting process produces a great deal of leather waste, and most of the leather waste is incinerated and buried. So, it comes to the fore as a serious environment issue. Therefore, it is necessary to study and develop various recycling methods of leather waste. 
     So, the inventors of the present invention studied spun leather yarn utilizing leather waste, and found out it was possible to manufacture high-quality spun leather yarn, which can be manufactured as fabrics, knitted goods, and lace goods, which have the nature of leather, can replace existing leather materials, which have been used in bags, athletic shoes, and the like, can be produced without being affected by seasons, and has warmth retention and general flame retardancy, which are the properties of natural leather. Accordingly, the inventors completed this invention. 
     In connection with the above, Japanese Patent Laid-open Publication No. 11-021600 discloses a manufacturing method of bulky regenerated leather. 
     DISCLOSURE 
     Technical Problem 
     Accordingly, the present invention has been made in an effort to solve the above-mentioned problems occurring in the prior arts, and it is an object of the present invention to provide a method for preparing spun leather yarn using leather fiber. 
     The technical problem to be solved by the present invention is not limited to the technical problem as mentioned above, and another technical problem, which is not mentioned, could be clearly understood by those having ordinary skill in the art to which the present invention pertains based on the description below. 
     Technical Solution 
     To achieve the above objects, the present invention provides a method for preparing spun leather yarn using leather fiber including the steps of: mixing leather fiber, common fiber, and polymer fiber to prepare mixed fiber; putting water and woolen oil into the mixed fiber, and mixing them; putting an anti-static agent into the mixed fiber into which water and woolen oil have been put, and mixing them; and spinning the mixed fiber into which the anti-static agent is put to prepare spun leather yarn. 
     Moreover, the leather fiber is obtained from leather waste, and the leather waste may be flaky scraps. 
     Furthermore, the common fiber is one selected from groups of cellulose-based natural fiber, protein-based natural fiber, mineral-based fiber, cellulose-based artificial fiber, protein-based artificial fiber, rubber-based fiber, inorganic fiber, and acetate-based fiber. 
     Additionally, the polymer fiber is one selected from groups of polyamide-based fiber, polyester-based fiber, polyurethane-based fiber, polyurea-based fiber, polyacryl-based fiber, polyvinyl alcohol-based fiber, polyvinyl chloride-based fiber, polyvinylidene chloride-based fiber, polypropylene-based fiber, polyethylene-based fiber, polystyrene-based fiber, and polyfluoroethylene-based fiber. 
     In addition, the leather fiber, the common fiber, and the polymer fiber are mixed at the rate of 40 parts by weight to 80 parts by weight of common fiber, and 20 parts by weight to 60 parts by weight of polymer fiber on the basis of 100 parts by weight of leather fiber. 
     The water and the woolen oil are mixed at the rate of 5 parts by weight to 10 parts by weight of water and 2 parts by weight to 10 parts by weight of woolen oil on the basis of 100 parts by weight of the mixed fiber. 
     1 part by weight to 5 parts by weight of the anti-static agent is put on the basis of 100 parts by weight of the mixed fiber. 
     Each of the step of putting water and woolen oil into the mixed fiber and mixing them, and the step of putting an anti-static agent into the mixed fiber into which water and woolen oil have been put and mixing them further includes a step of aging the mixed fiber for 8 hours to 15 hours after mixing. 
     The step of preparing spun leather yarn includes steps of: carding the mixed fiber, into which the anti-static agent is put, using a carding machine to prepare sliver; and applying twist and draft to the sliver to prepare spun leather yarn. 
     The carding machine includes a worker speed controller to control the speed of the worker. 
     The sliver manufactured by the carding machine is 15 mm or more in length. 
     After the step of manufacturing the sliver, the step of manufacturing the spun leather yarn further includes: a combing step of removing foreign matters from the sliver; a drawing step of producing a single strand of the sliver after the combing step; and drawing the sliver again after the drawing step and roving the sliver. 
     The drawing step is carried out using a roller having a plurality of wire fillets, and an interval between the plurality of wire fillets is 0.01 mm to 1 mm. 
     The drawing step is carried out by spraying water in order to prevent static electricity. 
     The method for preparing spun leather yarn using leather fiber further includes a covering step after the step of manufacturing spun leather yarn. 
     Advantageous Effects 
     The spun leather yarn prepared using leather fiber manufactured according to an embodiment of the present invention enables the manufacture of fabrics, knitted goods, and lace goods, which have the nature of leather, thereby being capable of being effectively used for various fashion applications. 
     In addition, the spun leather yarn prepared using leather fiber manufactured according to an embodiment of the present invention can replace existing leather materials, which have been used in bags, athletic shoes, and the like, and thus is not affected by material supply in accordance with seasonal changes, and accordingly, the economic effect thereof is excellent. Moreover, the spun leather yarn has warmth retention and general flame retardancy, which are the properties of natural leather, and thus is of very high quality. 
     It should be understood that the effects of the present invention are not limited to the above-mentioned effects, and includes all effects derivable from the configuration of the present invention described in the detailed description or claims of the present invention. 
    
    
     
       DESCRIPTION OF DRAWINGS 
         FIG. 1  is a schematic diagram illustrating a method for preparing spun leather yarn using leather fiber according to an embodiment of the present invention. 
         FIG. 2  is schematic diagram illustrating a structure of a carding machine according to an embodiment of the present invention. 
     
    
    
     BEST MODE 
     Hereinafter, preferred examples or embodiments of the present invention will be described in detail. However, the present invention can be implemented in various forms, is not limited to the preferred embodiments disclosed herein. 
     Example: Manufacturing Spun Leather Yarn Using Leather Fiber According to an Embodiment of the Present Invention 
     Spun leather yarn was manufactured using a method of manufacturing spun leather yarn using leather fiber according to an embodiment of the present invention. 
     First, a leather crusher destroyed bonding of leather fiber after impurities of leather waste were shaken off. After that, a leather scutcher separated leather fiber from the leather waste of which leather fiber bonding was destroyed. 
     Next, 40 parts by weight of rayon and 60 parts by weight of nylon on the basis of 100 parts by weight of the separated leather fiber were mixed to prepare mixed fiber. After that, 8 parts by weight of water and 5 parts by weight of woolen oil on the basis of 100 parts by weight of the mixed fiber were put and mixed, and then, the mixed fiber was aged for twelve hours. After that, 2 parts by weight of anti-static agent on the basis of 100 parts by weight of the mixed fiber was put and mixed, and then, the mixed fiber was aged for twelve hours. 
     Next, the aged mixed fiber was spun to prepare spun leather yarn. In this instance, the spun leather yarn was manufactured under a condition that a carding machine is adjusted to be reduced 40% in worker speed and to have temperature of 30° C. and humidity of 65% so as to manufacture the spun leather yarn. 
     Comparative Example 1: Preparation of Natural Fiber 
     Cotton being sold in the market was obtained. 
     Comparative Example 2: Preparation of Regenerated Fiber 
     Rayon being sold in the market was obtained. 
     Comparative Example 3: Preparation of Synthetic Fiber 
     Nylon being sold in the market was obtained. 
     Experimental Example: Measurement of Physical Properties of Spun Leather Yarn 
     The physical properties of the spun leather yarn manufactured according to the Example of the present invention, and the physical properties of the cotton, the rayon, and the nylon prepared in the comparative examples 1 to 3 were measured, and then, the results were recorded in the following Table 1. 
     
       
         
           
               
               
               
               
               
               
             
               
                 TABLE 1 
               
               
                   
               
               
                   
                   
                 Example  
                 Compar- 
                 Compar- 
                 Compar- 
               
               
                   
                   
                 of the  
                 ative 
                 ative 
                 ative 
               
               
                   
                   
                 present 
                 Example  
                 Example  
                 Example 
               
               
                   
                   
                 invention 
                 1 
                 2 
                 3 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
               
            
               
                 Ductility 
                 Dry  
                 24.83 
                 4 
                 18 
                 28 
               
               
                 (%) 
                 condition 
                   
                   
                   
                   
               
               
                   
                 Wet  
                 25.5 
                 — 
                 24 
                 36 
               
               
                   
                 condition 
                   
                   
                   
                   
               
            
           
           
               
               
               
               
               
            
               
                 Elastic recovery rate 
                 92.3 
                 75 
                 82 
                 100 
               
               
                 (%) 
                   
                   
                   
                   
               
               
                 Antibiotic action 
                 Excellent 
                 Very bad 
                 Very bad 
                 Good 
               
               
                   
               
            
           
         
       
     
     As shown in the Table 1, the spun leather yarn manufactured according to the Example of the present invention showed excellent ductility and elastic recovery, and especially, showed excellent antibiotic action by showing excellent antibacterial rate as a result of an antibacterial test. 
     MODE FOR INVENTION 
     Hereinafter, the present invention will be described in more detail. However, embodiments or examples of the present invention may be implemented in several different forms, and are not limited to the embodiments described herein. In addition, the present invention will be defined only by the scope of the appended claims. 
     Additionally, the terminology used herein is for the purpose of describing particular embodiments or examples only and is not intended to limit the present invention. As used herein, the singular forms are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be understood that the terms “comprise”, “include”, “have”, etc. in the whole specification of the present invention mean that other components are not excluded unless explicitly described otherwise, and other components may in fact be included. 
     In a first aspect of the present invention, provided is a method for preparing spun leather yarn using leather fiber including the steps of: mixing leather fiber, common fiber, and polymer fiber to prepare mixed fiber; putting water and woolen oil into the mixed fiber, and mixing them; putting an anti-static agent into the mixed fiber into which water and woolen oil have been put, and mixing them; and spinning the mixed fiber into which the anti-static agent is put to prepare spun leather yarn. 
     Hereinafter, referring to  FIG. 1 , the method for preparing spun leather yarn using leather fiber according to the first aspect of the present invention will be described in detail step by step.  FIG. 1  is a schematic diagram illustrating a method for preparing spun leather yarn using leather fiber according to an embodiment of the present invention. 
     First, according to an embodiment of the present invention, the method for preparing spun leather yarn using leather fiber includes a step (S 100 ) of mixing leather fiber, common fiber, and polymer fiber to prepare mixed fiber. 
     In the embodiment of the present invention, the leather fiber is obtained from leather waste, and the leather waste may be flaky scraps. The flaky form may be a flat type having a long shaft and a short shaft. If scraps of the leather waste are used, because the scraps have a predetermined length, spun leather yarn of a thread type can be manufactured easily. In this instance, the long shaft and the short shaft of the flaky form may be respectively 250 mm to 450 mm, and may have the same length. In the meantime, the leather fiber includes 8 wt % to 10 wt % of water on the basis of the gross weight of the leather fiber. As described above, because the leather fiber contains a small quantity of water, the next processes can be carried out smoothly to manufacture spun leather yarn. 
     In an embodiment of the present invention, leather fiber can be obtained from the leather waste through the following steps of: destroying bonding between leather fiber of leather waste using a leather crusher; and separating the leather fiber from the leather waste, of which leather fiber bonding was destroyed, using a leather scutcher. In this instance, the leather crusher is to destroy the bonding between the leather fiber of the leather waste by crushing the leather waste, and the crushing may be carried out by a well-known crushing method, but must be carried out by a crushing method which is strong enough to destroy the bonding between leather fiber. Moreover, the leather scutcher is used to separate the leather fiber from the leather waste of which leather fiber bonding was destroyed. For instance, the leather scutcher may separate the leather fiber from the leather waste using the heavy weight of the leather fiber. 
     In an embodiment of the present invention, the common fiber may be one selected from groups of cellulose-based natural fiber, protein-based natural fiber, mineral-based fiber, cellulose-based artificial fiber, protein-based artificial fiber, rubber-based fiber, inorganic fiber, and acetate-based fiber. The polymer fiber may be one selected from groups of polyamide-based fiber, polyester-based fiber, polyurethane-based fiber, polyurea-based fiber, polyacryl-based fiber, polyvinyl alcohol-based fiber, polyvinyl chloride-based fiber, polyvinylidene chloride-based fiber, polypropylene-based fiber, polyethylene-based fiber, polystyrene-based fiber, and polyfluoroethylene-based fiber. 
     In an embodiment of the present invention, in more detail, the common fiber or the polymer fiber may be at least one selected from groups of nylon, kapok, flax, ramie, hemp, jute, manila, abaca, sisal hemp, coir, sheep wool, goat wool, cashmere, camel wool, alpaca, rabbit fur, vicuna wool, llama wool, cultivated silk, wild silk, asbestos, metal fiber, glass fiber, rock wool, slag wool, carbon fiber, rayon, lanital, soylon fiber, ardil fiber, uicara fiber, casein fiber, acetate, acetylated rayon fiber, chlorinated rubber, hydrochlorinated rubber, amilan, rilsan, purlon L, terylene, tetron, dacron, kodel, vycron, spandex, lycra, vycron, purlon U, urylon, glasslon, orlon, acrilan, creslan, exlan, vonnel, cashmilon, verel, dynel, kanekalon, vinylon, vinyon, teviron, Pesse, saran, krehalon, herculon, pylen, revon, hizex, Algil, Salon, and Teflon. However, the above kinds of the common fiber or the polymer fiber are enumeration of desirable examples, and all kinds of the common fiber can be used with no specific limitation without affecting the objects and effects of the present invention. 
     In the embodiment of the present invention, the leather fiber, the common fiber, and the polymer fiber are mixed at the rate of 40 parts by weight to 80 parts by weight of common fiber, and 20 parts by weight to 60 parts by weight of polymer fiber on the basis of 100 parts by weight of leather fiber. Preferably, the common fiber, and the polymer fiber are mixed at the rate of 50 parts by weight to 70 parts by weight of common fiber, and 30 parts by weight to 50 parts by weight of polymer fiber on the basis of 100 parts by weight of leather fiber. More preferably, the common fiber, and the polymer fiber are mixed at the rate of 60 parts by weight of common fiber, and 40 parts by weight of polymer fiber on the basis of 100 parts by weight of leather fiber. If the mixing rate of the common fiber and the polymer fiber is higher than the rate, because the content of the leather fiber is relatively low, texture of leather may get worse. Furthermore, If the mixing rate of the common fiber and the polymer fiber is lower than the above rate, because the content of the leather fiber is relatively high, the leather fiber, the common fiber, and the polymer fiber are not mixed well, and spinning is not performed well in the spinning step since the content of basic filaments is too small. 
     Next, in an embodiment of the present invention, the method for preparing spun leather yarn using leather fiber includes a step (S 200 ) of putting water and woolen oil into the mixed fiber, and mixing them. 
     In the embodiment of the present invention, the water and the woolen oil are to increase a mixing rate of the leather fiber, the common fiber, and the polymer fiber. The water and the woolen oil are mixed at the rate of 5 parts by weight to 10 parts by weight of water and 2 parts by weight to 10 parts by weight of woolen oil on the basis of 100 parts by weight of the mixed fiber. Preferably, the water and the woolen oil are mixed at the rate of 7 parts by weight to 9 parts by weight of water and 3 parts by weight to 7 parts by weight of woolen oil on the basis of 100 parts by weight of the mixed fiber. More preferably, the water and the woolen oil are mixed at the rate of 8 parts by weight of water and 5 parts by weight of woolen oil on the basis of 100 parts by weight of the mixed fiber. If less than 5 parts by weight of water is put and less than 2 parts by weight of woolen oil is put on the basis of 100 parts by weight of the mixed fiber, because the content of the water and the woolen oil is too low, the leather fiber, the common fiber, and the polymer fiber are not mixed well. In addition, if more than 10 parts by weight of water is put and more than 10 parts by weight of woolen oil is put on the basis of 100 parts by weight of the mixed fiber, because the content of the water and the woolen oil is too high, the spun leather yarn manufactured in the next step may not show the texture of leather. 
     Next, in an embodiment of the present invention, the method for preparing spun leather yarn using leather fiber includes a step (S 300 ) of putting an anti-static agent into the mixed fiber into which water and woolen oil have been put, and mixing them. 
     In the embodiment of the present invention, the anti-static agent is put in order to increase a mixing rate of the leather fiber, the common fiber and the polymer fiber. 1 part by weight to 5 parts by weight of the anti-static agent is put on the basis of 100 parts by weight of the mixed fiber. Preferably, 1 part by weight to 3 parts by weight of the anti-static agent is put on the basis of 100 parts by weight of the mixed fiber. More preferably, 2 parts by weight of the anti-static agent is put on the basis of 100 parts by weight of the mixed fiber. If less than 1 part by weight of water is put, because the content of the anti-static agent is too low, the leather fiber, the common fiber, and the polymer fiber are not mixed well. In addition, if more than 5 parts by weight of anti-static agent is put, because the content of the anti-static agent is too high, the spun leather yarn manufactured in the next step may not show the texture of leather. 
     In an embodiment of the present invention, the step (S 200 ) of putting water and woolen oil into the mixed fiber and mixing them, and the step (S 300 ) of putting an anti-static agent into the mixed fiber into which water and woolen oil have been put and mixing them may be carried out at the same time. However, if the steps are carried out in order, the mixing rate of the leather fiber, the common fiber, and the polymer fiber may be increased. 
     In an embodiment of the present invention, each of the step (S 200 ) of putting water and woolen oil into the mixed fiber and mixing them, and the step (S 300 ) of putting an anti-static agent into the mixed fiber into which water and woolen oil have been put and mixing them may further include a step of aging the mixed fiber for 8 hours to 15 hours after mixing. In this instance, preferably, the aging step may be carried out for 10 hours to 14 hours. More preferably, the aging step may be carried out for 12 hours. That is, in each step, the mixed fiber is aged for a predetermined period of time after the water, the woolen oil, and the anti-static agent are put and mixed, so that the mixing rate of the leather fiber, the common fiber, and the polymer fiber is increased. 
     In an embodiment of the present invention, the method for preparing spun leather yarn using leather fiber may repeat the steps of: (S 100 ) mixing leather fiber, common fiber, and polymer fiber to prepare mixed fiber; (S 200 ) putting water and woolen oil into the mixed fiber, and mixing them; (S 300 ) putting an anti-static agent into the mixed fiber into which water and woolen oil have been put, and mixing them, several times. Preferably, the method for preparing spun leather yarn using leather fiber may repeat the steps (S 100 ), (S 200 ), and (S 300 ) four times. In this instance, the method for preparing spun leather yarn using leather fiber includes: a first mixing step of first mixing 40 wt % to 60 wt % of mixed fiber on the basis of the gross weight of the mixed fiber to be manufactured; a second mixing step of adding and mixing 20% to 30% of the gross weight of the mixed fiber to be manufactured; a third mixing step of adding and mixing 10% to 20% of the gross weight of the mixed fiber to be manufactured; and a fourth mixing step of adding and mixing 5% to 10% of the gross weight of the mixed fiber to be manufactured. That is, fibers to be mixed are added and mixed at a predetermined ratio in several steps, so that the leather fiber can be evenly mixed with the common fiber and the polymer fiber. However, the repeated number is not limited to four, and may be five, six or more. 
     Next, in an embodiment of the present invention, the method for preparing spun leather yarn using leather fiber includes a step (S 400 ) of spinning the mixed fiber into which the anti-static agent is put to prepare spun leather yarn. Referring to  FIG. 2 , the step (S 400 ) of spinning the mixed fiber into which the anti-static agent is put to prepare spun leather yarn will be described in more detail. 
     In the embodiment of the present invention, the step (S 400 ) of preparing spun leather yarn includes steps of: carding the mixed fiber, into which the anti-static agent is put, using a carding machine  101  which brushing the mixed fiber in the direction of grains to prepare sliver; and applying twist and draft to the sliver to prepare spun leather yarn. 
     In the embodiment of the present invention, carding is a mixing step to mix the mixed fiber at uniform mixing rate. Through the carding step, the mixed fiber is separated into several strands, impurities or foreign matters contained in the mixed fiber are removed, and the mixed fiber is concentrated into a web having required weight per unit area. In detail, the mixed fiber is supplied to a roller covered with wire fillets rotating at rapid speed by a lattice to be opened thin. The mixed fiber which is opened thin is supplied to a drum (doffer) covered with wire fillets rotating at slow speed, so that a web having a predetermined weight can be formed while the mixed fiber passes through the drum. In this instance, the carding machine  101  includes a worker  110  for performing opening. In the present invention, the carding machine  101  may further include a worker speed controller  210  for controlling speed of the worker  110 . Referring to  FIG. 2 , the worker speed controller  210  may be mounted inside a cylinder illustrated in the drawing so as to control speed of the worker  110  according to the length of the mixed fiber supplied to the carding machine. Meanwhile, preferably, the speed of the worker  110  is controlled to be reduced by about 30% to 50% in comparison with the normal speed of a conventional worker. That is, because the speed of the worker  110  is lower than the speed of the conventional worker, the mixed fiber which is relatively shorter in length is uniformly transferred along the worker  110  without being scattered outside the worker so as to form the web. 
     In the embodiment of the present invention, the sliver manufactured by the carding machine is 15 mm or more in length, preferably, is 20 mm or more in length, and more preferably, is 31 mm or more in length. If the sliver manufactured by the carding machine is less than 15 mm, the mixed fiber cannot be manufactured in the form of yarn, and so, the spun leather yarn cannot be manufactured. 
     In an embodiment of the present invention, after the step of manufacturing the sliver, the step (S 400 ) of manufacturing the spun leather yarn further includes: a combing step of removing foreign matters from the sliver; a drawing step of producing a single strand of the sliver after the combing step; and drawing the sliver again after the drawing step and roving the sliver. 
     The combing step is to remove foreign matters contained in the sliver, align fiber, and arrange fine hairs. In this instance, the combing step is carried out on a wooden plate in the conventional art, but if the combing step is carried on the wooden plate, the sliver or the web transferred from the carding machine may be torn. Therefore, preferably, the combing step is carried out on a rubber plate in order to prevent the sliver or the web from being torn. Moreover, an input amount of the sliver put into the combing step is about 50% of the input amount of sliver in the conventional method. So, the method of manufacturing the spun leather yarn further according to the present invention can increase an output of spun leather yarn and can manufactured spun leather yarn having uniform thickness (uniformity) since a break of the sliver is prevented. 
     In the embodiment of the present invention, the drawing step is to manufacture a single strand of the sliver, and is carried out using a roller having a plurality of wire fillets. In this instance, an interval between the plurality of wire fillets is 0.01 mm to 1 mm, preferably, 0.05 mm to 0.5 mm, and more preferably, 0.1 mm. Furthermore, the number of revolutions of the roller having the wire fillets is 120 rpm to 130 rpm. Meanwhile, the drawing step is carried out by spraying water in order to prevent static electricity. 
     In the embodiment of the present invention, the roving step is to rove the sliver by drawing again and rubbing the sliver after the drawing step, and may includes a step of separating the sliver in the same thickness. 
     In the embodiment of the present invention, the step of applying twist and draft to the sliver to prepare spun leather yarn is to release the sliver into the thickness of yarn by applying strength and uniformity to the sliver. That is, the step of applying twist and draft to the sliver is a process to make the sliver have a desired thickness by drawing it, concentrate and snarl the fiber by applying twist, and apply strength by providing friction between the fibers. In this instance, the twist number of the fiber is 400 TM to 1,000 TM, and the thickness is 10 yarn count, 15 yarn count, 20 yarn count, or 25 yarn count. 
     In the embodiment of the present invention, the step (S 400 ) of manufacturing spun leather yarn may be carried out at temperature of 20° C. to 40° C. and at humidity of 50% to 80%, preferably, at temperature of 25° C. to 35° C. and at humidity of 60% to 70%, since the mixed fiber may be scattered into the air during the spinning step due to the short length of the mixed fiber. If the mixed fiber is spun at the temperature and at the humidity, the spinning work can be carried out without scattering of the mixed fiber so as to easily manufacture spun leather yarn. 
     In an embodiment of the present invention, the method of manufacturing spun leather yarn may further include a covering step after the step (S 400 ) of manufacturing spun leather yarn. 
     In the embodiment of the present invention, the covering step is carried out to reinforce physical properties, such as tensile strength and flexible rate, and is started from a step of holding the prepared spun leather yarn on a covering machine after winding of the prepared spun leather yarn is finished. Yarn used in the covering step may be 30 denier to 150 denier polyester. Alternatively, nylon or functional yarn, such as high stretch yarn, high shrinkage yarn, or bulky yarn, may be used for the yarn used in the covering step. S-shaped covering or Z-shaped covering may be used as a covering method, or a double covering which the S-shaped covering and the Z-shaped covering are performed at the same time may be carried out. In case of the double covering, after the covering step, the covered yarn has a shape close to alphabet S. The covering step may include a step of twisting the yarn additionally. In this instance, preferably, the twist number is 100 TM to 250 TM. 
     EXPLANATION OF REFERENCE NUMERALS 
     
         
         
           
               101 : carding machine 
               110 : worker 
               210 : worker speed controller 
           
         
       
    
     INDUSTRIAL APPLICABILITY 
     The spun leather yarn prepared using leather fiber manufactured according to an embodiment of the present invention enables the manufacture of fabrics, knitted goods, and lace goods, which have the nature of leather, thereby being capable of being effectively used for various fashion applications. 
     Moreover, the spun leather yarn prepared using leather fiber manufactured according to an embodiment of the present invention can replace existing leather materials, which have been used in bags, athletic shoes, and the like, and thus is not affected by material supply in accordance with seasonal changes, and accordingly, the economic effect thereof is excellent. Moreover, the spun leather yarn has warmth retention and general flame retardancy, which are the properties of natural leather, and thus is of very high quality. 
     It should be understood that the effects of the present invention are not limited to the above-mentioned effects, and includes all effects derivable from the configuration of the present invention described in the detailed description or claims of the present invention.