Patent Publication Number: US-11643762-B2

Title: Knitted fabric with leather fibers and manufacturing method thereof

Description:
FIELD OF THE INVENTION 
     The invention relates to a knitted fabric and a manufacturing method thereof, and more particularly to a knitted fabric with leather fibers and a manufacturing method thereof. 
     BACKGROUND OF THE INVENTION 
     Leather becomes a commonly used craft material nowadays, but leather cannot be decomposed after it is processed and made. As a result, waste leather can only be incinerated and cannot be recycled. 
     With the rising awareness of environmental protection, many companies have tried to recycle waste. Leather reused also has been one of the problems thereof. In one of the existing manufacturing methods, it cuts the waste leather into scraps to form a plurality of leather fibers, and then attaches the plurality of leather fibers to a base yarn to make a leather yarn. However, due to different sizes of the leather fibers, strength of the leather yarn is inferior to that of cotton. Also, a surface of the fabric knitted from the leather yarn is uneven and the strength is obviously insufficient, resulting in the fabric knitted from the leather yarn having an uncomfortable tactile feeling and easily to be damaged. 
     SUMMARY OF THE INVENTION 
     A main object of the invention is to solve the problems of uncomfortable tactile feeling and poor strength of conventional fabrics knitted from leather yarns. 
     In order to achieve the above object, the invention provides a knitted fabric with leather fibers. The knitted fabric comprises a ground yarn layer and a face yarn layer directly connected to the ground yarn layer through double knitting. The bottom yarn layer includes a plurality of first yarn loops, each of the plurality of first yarn loops formed with a plurality of ground yarns. The face yarn layer is directly connected to the ground yarn layer through double knitting, and the face yarn layer includes a plurality of second yarn loops, each of the plurality of second yarn loops formed with at least one face yarn attached with the leather fibers, wherein the leather fibers are obtained from a piece of leather by a pulverization operation, and a course ratio of the face yarn layer to the ground yarn layer is ranged between 1:1.25 and 1:4. 
     In one embodiment, the face yarn includes a base yarn and a polyurethane (PU) layer which is wrapped around a surface of the base yarn and comprises the leather fibers. 
     In one embodiment, the base yarn is made of thermoplastic polyurethane (TPU). 
     In one embodiment, the knitted fabric includes a reinforcing layer provided on a side of the face yarn layer that is not connected to the ground yarn layer. 
     In one embodiment, a plurality of leather textures is formed on the reinforcing layer. 
     In addition to the foregoing, the invention further provides a manufacturing method for a knitted fabric with leather fibers, comprising steps of: 
     step A: double knitting a plurality of ground yarns and at least one face yarn by a flat knitting machine to form the knitted fabric, wherein the face yarn is attached with the leather fibers obtained from a piece of leather by a pulverization operation, and the knitted fabric comprises a ground yarn layer and a face yarn layer, and wherein the ground yarn layer comprises a plurality of first yarn loops respectively formed with the plurality of ground yarns, the face yarn layer comprises a plurality of second yarn loops respectively formed with the face yarn, a course ratio of the face yarn layer to the ground yarn layer is ranged between 1:1.25 and 1:4, and a yarn tension of the face yarn is less than a yarn tension of the ground yarn during knitting by the flat knitting machine; and
         step B: ironing the knitted fabric.       

     In one embodiment, the manufacturing method includes step C: hot pressing the face yarn layer. 
     In one embodiment, the manufacturing method includes step D: disposing a thermoplastic film on the face yarn layer, and hot pressing the thermoplastic film to form a reinforcing layer. 
     In one embodiment, in step D, hot pressing the thermoplastic film by using a leather texture mold to form a plurality of leather textures on the reinforcing layer. 
     In one embodiment, the thermoplastic film is made of polyurethane (PU) material. 
     In one embodiment, the face yarn is manufactured by wrapping a leather slurry around a base yarn and treated with baking, the leather slurry is made by mixing a liquid polyurethane with the leather fibers, and the base yarn is made of a thermoplastic polyurethane (TPU). 
     Accordingly, compared with the conventional technique, the invention has the following features: the invention provides the innovative knitted fabric, and solves the problem that the leather cannot be reused after being discarded. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a schematic diagram of structure of a first embodiment of a knitted fabric of the invention; 
         FIG.  2    is a schematic diagram of structure of a face yarn of the invention; 
         FIG.  3    is a schematic diagram of structure of a second embodiment of the knitted fabric of the invention; 
         FIG.  4    is a schematic diagram of structure of a third embodiment of the knitted fabric of the invention; 
         FIG.  5    is a simplified knitting diagram of the knitted fabric of the invention with a course ratio of 1:1.25; 
         FIG.  6    is a simplified knitting diagram of the knitted fabric of the invention with a course ratio of 1:1.33; 
         FIG.  7    is a first simplified knitting diagram of the knitted fabric of the invention with a course ratio of 1:1.5; 
         FIG.  8    is a second simplified knitting diagram of the knitted fabric of the invention with a course ratio of 1:1.5; 
         FIG.  9    is a simplified knitting diagram of the knitted fabric of the invention with a course ratio of 1:1.67; 
         FIG.  10    is a simplified knitting diagram of the knitted fabric of the invention with a course ratio of 1:1.75; 
         FIG.  11    is a simplified knitting diagram of the knitted fabric of the invention with a course ratio of 1:2; 
         FIG.  12    is a simplified knitting diagram of the knitted fabric of the invention with a course ratio of 1:2.25; 
         FIG.  13    is a simplified knitting diagram of the knitted fabric of the invention with a course ratio of 1:2.33; 
         FIG.  14    is a first simplified knitting diagram of the knitted fabric of the invention with a course ratio of 1:2.5; 
         FIG.  15    is a second simplified knitting diagram of the knitted fabric of the invention with a course ratio of 1:2.5; 
         FIG.  16    is a simplified knitting diagram of the knitted fabric of the invention with a course ratio of 1:2.67; 
         FIG.  17    is a simplified knitting diagram of the knitted fabric of the invention with a course ratio of 1:2.75; 
         FIG.  18    is a simplified knitting diagram of the knitted fabric of the invention with a course ratio of 1:3; 
         FIG.  19    is a simplified knitting diagram of the knitted fabric of the invention with a course ratio of 1:3.25; 
         FIG.  20    is a simplified knitting diagram of the knitted fabric of the invention with a course ratio of 1:3.33; 
         FIG.  21    is a first simplified knitting diagram of the knitted fabric of the invention with a course ratio of 1:3.5; 
         FIG.  22    is a second simplified knitting diagram of the knitted fabric of the invention with a course ratio of 1:3.5; 
         FIG.  23    is a simplified knitting diagram of the knitted fabric of the invention with a course ratio of 1:3.67; 
         FIG.  24    is a simplified knitting diagram of the knitted fabric of the invention with a course ratio of 1:3.75; 
         FIG.  25    is a simplified knitting diagram of the knitted fabric of the invention with a course ratio of 1:4; 
         FIG.  26    is an implementation flow chart of a first embodiment of a manufacturing method of the invention; 
         FIG.  27    is an implementation flow chart of a second embodiment of the manufacturing method of the invention; and 
         FIG.  28    is a schematic diagram of structure of a fourth embodiment of the knitted fabric of the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The detailed description and technical content of the invention are described below with reference to the drawings. 
     Please refer to  FIG.  1    and  FIG.  2   . The invention provides a knitted fabric  10  with leather fibers. The knitted fabric  10  can be used to manufacture a garment, a shoe or a bag. The knitted fabric  10  is basically double knitted by a flat knitting machine (not shown in the figures). In addition, the knitted fabric  10  includes a ground yarn layer  11  and a face yarn layer  12 . The ground yarn layer  11  includes a plurality of first yarn loops  111 , and each of the first yarn loops  111  is formed with a plurality of ground yarns  112 . The face yarn layer  12  is directly connected to the ground yarn layer  11  through double knitting. Double knitting is well-known for those skilled in the art and will not be described herein. In addition, the face yarn layer  12  includes a plurality of second yarn loops  121 , and each of the second yarn loops  121  is formed with at least one face yarn  123  attached with a plurality of leather fibers  122 . Further, the plurality of leather fibers  122  is obtained from a piece of leather by a pulverization operation, and the leather can be a new product or a recycled waste product. The pulverization operation refers to cutting the leather through machinery, and the leather is cut from an original sheet shape into scraps to form the plurality of leather fibers  122 . In addition, sizes of the plurality of leather fibers  122  are not limited to be the same, and thicknesses of the plurality of leather fibers  122  are in a range between 0.5 mm and 2 mm. Furthermore, the face yarn  123  includes the plurality of leather fibers  122  as well as a base yarn  124  to carry the plurality of leather fibers  122 . The base yarn  124  can be selected from different yarns according to implementation requirements which will not be described herein. In one embodiment, the base yarn  124  is made of thermoplastic polyurethane (TPU), which is obtained from recycling wastes with the thermoplastic polyurethane. In addition to the foregoing embodiment, the base yarn  124  can also be made of other environmentally friendly materials. Furthermore, a manufacturing process of the face yarn  123  provides as follows. After the plurality of leather fibers  122  is obtained, the plurality of leather fibers  122  is added to liquid polyurethane (PU) to make a leather slurry, and then the base yarn  124  is placed into the leather slurry with the plurality of leather fibers  122 , so that the plurality of leather fibers  122  and the liquid polyurethane are wrapped around a surface of the base yarn  124 . Subsequently, the base yarn  124  wrapped with the leather slurry is taken out and baking in an appropriate time to form the face yarn  123 . At this time, the face yarn  123  is composed of the base yarn  124  and a polyurethane layer  125 , which is wrapped around an outer surface of the base yarn  124  and comprises the plurality of leather fibers  122 . The aforementioned baking step aims to remove moisture in the face yarn  123 . 
     Considering that the face yarn  123  contains the plurality of leather fibers  122  with different sizes, a problem of poor strength and a risk of being easily damaged would occur, if fabrics knitted by the face yarn  123  thereof. In order to solve the above problems, the ground yarn layer  11  aims to strengthen the structure of the face yarn layer  12  except for being a backside of the knitted fabric  10 . Therefore, a course ratio of the face yarn layer  12  to the ground yarn layer  11  is in a range between 1:1.25 and 1:4, and a yarn tension of the face yarn  123  is less than a yarn tension of the ground yarn  112  when the flat knitting machine is knitting. As shown in  FIG.  1    for a schematic diagram of structure of the knitted fabric  10 , numbers of courses of the ground yarn layer  11  is more than numbers of courses of the face yarn layer  12 . That is to say, numbers of the first yarn loops  111  is more than numbers of the second yarn loops  121 . Under the condition that lengths of the ground yarn layer  11  and the face yarn layer  12  are the same, a yarn loop density of the ground yarn layer  11  is greater than a yarn loop density of the face yarn layer  12 . Here, a stronger knitting structure is formed to solve the problem of poor strength of the face yarn layer  12 . 
     Furthermore, in the invention, the connection between the ground yarn layer  11  and the face yarn layer  12  is not limited to a specific knitting structure to form the knitted fabric  10 . As shown in  FIG.  1   , when two needle beds of the flat knitting machine are knitting, except for the face yarn  123 , at least one of the ground yarns  112  is further fed to one of the two needle beds for knitting the face yarn layer  12 . Thus, the at least one of the ground yarns  112  not only forms the plurality of first yarn loops  111 , but also cooperates with the face yarn  123  to form the plurality of second yarn loops  121 , thereby the ground yarn layer  11  and the face yarn layer  12  are connected realized by the at least one of the ground yarns  112 . In another embodiment as shown in  FIG.  3   , after one part of the plurality of first yarn loops  111  is knitted by the other one of the two needle beds for knitting the ground yarn layer  11 , at least one of the ground yarns  112  and the face yarn  123  are together fed to the needle bed for knitting the ground yarn layer  11  to knit another part of the plurality of first yarn loops  111 . Then, the at least one of the ground yarns  112  and the face yarn  123  are together fed to the needle bed for knitting the face yarn layer  12 , whereby the connection between the ground yarn layer  11  and the face yarn layer  12  are realized by the face yarn  123  and the at least one of the ground yarns  112 . Please refer to another embodiment in  FIG.  4   . The face yarn  123  is further fed to the needle bed for knitting the ground yarn layer  11  in one of knitting strokes, thus the ground yarn layer  11  and the face yarn layer  12  are connected realized by the face yarn  123 . 
     Accordingly, please refer to  FIG.  5   ,  FIG.  6   ,  FIG.  7   ,  FIG.  8   ,  FIG.  9   ,  FIG.  10   ,  FIG.  11   ,  FIG.  12   ,  FIG.  13   ,  FIG.  14   ,  FIG.  15   ,  FIG.  16   ,  FIG.  17   ,  FIG.  18   ,  FIG.  19   ,  FIG.  20   ,  FIG.  21   ,  FIG.  22   ,  FIG.  23   ,  FIG.  24   , and  FIG.  25   , which show simplified knitting of two needle beds  40 ,  41  of the flat knitting machine to meet the requirements that a course ratio of the face yarn layer  12  to the ground yarn layer  11  is in a range between 1:1.25 and 1:4. A structure of the two needle beds  40 ,  41  of the flat knitting machine is well-known in the technical field, so that knitting needles mentioned in the following description have no drawings and referenced numerals.  FIG.  5    is a schematic diagram of one embodiment that a course ratio of the face yarn layer  12  to the ground yarn layer  11  is 1:1.25. Precisely, the course ratio is written as 1:1+(¼). In one stroke, each knitting needle of the needle bed  40  for knitting the face yarn layer  12  stitches the face yarn  123  once; and in the same stroke, each knitting needle of the needle bed  41  for knitting the ground yarn layer  11  stitches one ground yarn  112  once, and a first knitting needle of every four knitting needles thereof further stitches the ground yarn  112  again. Here, in practical knitting and feeding of the embodiment of  FIG.  5   , a yarn tension of the face yarn  123  is preferably set as approximately 1/1.25 times a yarn tension of the ground yarn  112 . 
       FIG.  6    is a schematic diagram of one embodiment that a course ratio of the face yarn layer  12  to the ground yarn layer  11  is 1:1.33, which is an approximate value. Precisely, the course ratio is written as 1:1+(⅓). In one stroke, each knitting needle of the needle bed  40  for knitting the face yarn layer  12  stitches the face yarn  123  once; and in the same stroke, each knitting needle of the needle bed  41  for knitting the ground yarn layer  11  stitches one ground yarn  112  once, and a first knitting needle of every three knitting needles thereof further stitches the ground yarn  112  again. Here, in practical knitting and feeding of the embodiment of  FIG.  6   , a yarn tension of the face yarn  123  is preferably set as approximately 1/1.33 times a yarn tension of the ground yarn  112 . 
       FIG.  7    is a schematic diagram of one embodiment that a course ratio of the face yarn layer  12  to the ground yarn layer  11  is 1:1.5. Precisely, the course ratio is written as 1:1+(½). In one stroke, each knitting needle of the needle bed  40  for knitting the face yarn layer  12  stitches the face yarn  123  once; and in the same stroke, each knitting needle of the needle bed  41  for knitting the ground yarn layer  11  stitches one ground yarn  112  once, and a first knitting needle of every two knitting needles thereof further stitches the ground yarn  112  again. Here, in practical knitting and feeding of the embodiment of  FIG.  7   , a yarn tension of the face yarn  123  is preferably set as approximately 1/1.5 times a yarn tension of the ground yarn  112 . 
       FIG.  8    is a schematic diagram of one embodiment that a course ratio of the face yarn layer  12  to the ground yarn layer  11  is 1:1.5. Precisely, the course ratio is written as 1:1+( 2/4). In one stroke, each knitting needle of the needle bed  40  for knitting the face yarn layer  12  stitches the face yarn  123  once; and in the same stroke, each knitting needle of the needle bed  41  for knitting the ground yarn layer  11  stitches one ground yarn  112  once, and a first knitting needle and a second knitting needle of every four knitting needles thereof further stitch the ground yarn  112  again. Here, in practical knitting and feeding of the embodiment of  FIG.  8   , a yarn tension of the face yarn  123  is preferably set as approximately 1/1.5 times a yarn tension of the ground yarn  112 . 
       FIG.  9    is a schematic diagram of one embodiment that a course ratio of the face yarn layer  12  to the ground yarn layer  11  is 1:1.67, which an approximate value. Precisely, the course ratio is written as 1:1+(⅔). In one stroke, each knitting needle of the needle bed  40  for knitting the face yarn layer  12  stitches the face yarn  123  once; and in the same stroke, each knitting needle of the needle bed  41  for knitting the ground yarn layer  11  stitches one ground yarn  112  once, and a first knitting needle and a second knitting needle of every three knitting needles thereof further stitch the ground yarn  112  again. Here, in practical knitting and feeding of the embodiment of  FIG.  9   , a yarn tension of the face yarn  123  is preferably set as approximately 1/1.67 times a yarn tension of the ground yarn  112 . 
       FIG.  10    is a schematic diagram of one embodiment that a course ratio of the face yarn layer  12  to the ground yarn layer  11  is 1:1.75. Precisely, the course ratio is written as 1:1+(¾). In one stroke, each knitting needle of the needle bed  40  for knitting the face yarn layer  12  stitches the face yarn  123  once; and in the same stroke, each knitting needle of the needle bed  41  for knitting the ground yarn layer  11  stitches one ground yarn  112  once, and a first knitting needle, a second knitting needle, and a third knitting needle of every four knitting needles thereof further stitch the ground yarn  112  again. Here, in practical knitting and feeding of the embodiment of  FIG.  10   , a yarn tension of the face yarn  123  is preferably set as approximately 1/1.75 times a yarn tension of the ground yarn  112 . 
       FIG.  11    is a schematic diagram of one embodiment that a course ratio of the face yarn layer  12  to the ground yarn layer  11  is 1:2. In one stroke, each knitting needle of the needle bed  40  for knitting the face yarn layer  12  stitches the face yarn  123  once; and in the same stroke, two ground yarns  112  are separately stitched once by each knitting needle of the needle bed  41  for knitting the ground yarn layer  11 . Here, in practical knitting and feeding of the embodiment of  FIG.  11   , a yarn tension of the face yarn  123  is preferably set as approximately ½ times a yarn tension of the ground yarn  112 . 
       FIG.  12    is a schematic diagram of one embodiment that a course ratio of the face yarn layer  12  to the ground yarn layer  11  is 1:2.25. Precisely, the course ratio is written as 1:2+(¼). In one stroke, each knitting needle of the needle bed  40  for knitting the face yarn layer  12  stitches the face yarn  123  once; and in the same stroke, two ground yarns  112  are separately stitched once by each knitting needle of the needle bed  41  for knitting the ground yarn layer  11 , and a first knitting needle of every four knitting needles thereof further stitches one ground yarn  112  again. Here, in practical knitting and feeding of the embodiment of  FIG.  12   , a yarn tension of the face yarn  123  is preferably set as approximately 1/2.25 times a yarn tension of the ground yarn  112 . 
       FIG.  13    is a schematic diagram of one embodiment that a course ratio of the face yarn layer  12  to the ground yarn layer  11  is 1:2.33, which is an approximate value. Precisely, the course ratio is written as 1:2+(⅓). In one stroke, each knitting needle of the needle bed  40  for knit the face yarn layer  12  stitches the face yarn  123  once; and in the same stroke, two ground yarns  112  are separately stitched once by each knitting needle of the needle bed  41  for knitting the ground yarn layer  11 , and a first knitting needle of every three knitting needles thereof further stitches one ground yarn  112  again. Here, in practical knitting and feeding of the embodiment of FIG.  13 , a yarn tension of the face yarn  123  is preferably set as approximately 1/2.33 times a yarn tension of the ground yarn  112 . 
       FIG.  14    is a schematic diagram of one embodiment that a course ratio of the face yarn layer  12  to the ground yarn layer  11  is 1:2.5. Precisely, the course ratio is written as 1:2+(½). In one stroke, each knitting needle of the needle bed  40  for knitting the face yarn layer  12  stitches the face yarn  123  once; and in the same stroke, two ground yarns  112  are separately stitched once by each knitting needle of the needle bed  41  for knitting the ground yarn layer  11 , and a first knitting needle of every two knitting needles thereof further stitches one ground yarn  112  again. Here, in practical knitting and feeding of the embodiment of  FIG.  14   , a yarn tension of the face yarn  123  is preferably set as approximately 1/2.5 times a yarn tension of the ground yarn  112 . 
       FIG.  15    is a schematic diagram of one embodiment that a course ratio of the face yarn layer  12  to the ground yarn layer  11  is 1:2.5. Precisely, the course ratio is written as 1:2+( 2/4). In one stroke, each knitting needle for the needle bed  40  for knitting the face yarn layer  12  stitches the face yarn  123  once; and in the same stroke, two ground yarns  112  are separately stitched once by each knitting needle of the needle bed  41  for knitting the ground yarn layer  11 , and a first knitting needle and a second knitting needle of every four knitting needles thereof further stitch one ground yarn  112  again. Here, in practical knitting and feeding of the embodiment of  FIG.  15   , a yarn tension of the face yarn  123  is preferably set as approximately 1/2.5 times a yarn tension of the ground yarn  112 . 
       FIG.  16    is a schematic diagram of one embodiment that a course ratio of the face yarn layer  12  to the ground yarn layer  11  is 1:2.67, which is an approximate value. Precisely, the course ratio is written as 1:2+(⅔). In one stroke, each knitting needle of the needle bed  40  for knitting the face yarn layer  12  stitches the face yarns  123  once; and in the same stroke, two ground yarns  112  are separately stitched once by each knitting needle of the needle bed  41  for knitting the ground yarn layer  11 , and a first knitting needle and a second knitting needle of every three knitting needles thereof further stitch one ground yarn  112  again. Here, in practical knitting and feeding of the embodiment of  FIG.  16   , a yarn tension of the face yarn  123  is preferably set as approximately 1/2.67 times a yarn tension of the ground yarn  112 . 
       FIG.  17    is a schematic diagram of one embodiment that a course ratio of the face yarn layer  12  to the ground yarn layer  11  is 1:2.75. Precisely, the course ratio is written as 1:2+(¾). In one stroke, each knitting needle of the needle bed  40  for knitting the face yarn layer  12  stitches the face yarn  123  once; and in the same stroke, two ground yarns  112  are separately stitched once by each knitting needle of the needle bed  41  for knitting the ground yarn layer  11 , and a first knitting needle, a second knitting needle, and a third knitting needle of every four knitting needles thereof further stitch one ground yarn  112  again. Here, in practical knitting and feeding of the embodiment of  FIG.  17   , a yarn tension of the face yarn  123  is preferably set as approximately 1/2.75 times a yarn tension of the ground yarn  112 . 
       FIG.  18    is a schematic diagram of one embodiment that a course ratio of the face yarn layer  12  to the ground yarn layer  11  is 1:3. In one stroke, each knitting needle of the needle bed  40  for knitting the face yarn layer  12  stitches the face yarns  123  once; and in the same stroke, three ground yarns  112  are separately stitched once by each knitting needle of the needle bed  41  for knitting the ground yarn layer  11 . Here, in practical knitting and feeding of the embodiment of  FIG.  18   , a yarn tension of the face yarn  123  is preferably set as approximately ⅓ times a yarn tension of the ground yarn  112 . 
       FIG.  19    is a schematic diagram of one embodiment that a course ratio of the face yarn layer  12  to the ground yarn layer  11  is 1:3.25. Precisely, the course ratio is written as 1:3+(¼). In one stroke, each knitting needle of the needle bed  40  for knitting the face yarn layer  12  stitches the face yarns  123  once; and in the same stroke, three ground yarns  112  are separately stitched once by each knitting needle of the needle bed  41  for knitting the ground yarn layer  11 , and a first knitting needle of every four knitting needles thereof further stitches one ground yarn  112  again. Here, in practical knitting and feeding of the embodiment of  FIG.  19   , a yarn tension of the face yarn  123  is preferably set as approximately 1/3.25 times a yarn tension of the ground yarn  112 . 
       FIG.  20    is a schematic diagram of one embodiment that a course ratio of the face yarn layer  12  to the ground yarn layer  11  is 1:3.33, which is an approximate value. Precisely, the course ratio is written as 1:3+(⅓). In one stroke, each knitting needle of the needle bed  40  for knitting the face yarn layer  12  stitches the face yarns  123  once; and in the same stroke, three ground yarns  112  are separately stitched once by each knitting needle of the needle bed  41  for knitting the ground yarn layer  11 , and a first knitting needle of every three knitting needles thereof further stitches one ground yarn  112  again. Here, in practical knitting and feeding of the embodiment of  FIG.  20   , a yarn tension of the face yarn  123  is preferably set as approximately 1/3.33 times a yarn tension of the ground yarn  112 . 
       FIG.  21    is a schematic diagram of one embodiment that a course ratio of the face yarn layer  12  to the ground yarn layer  11  is 1:3.5. Precisely, the course ratio is written as 1:3+(½). In one stroke, each knitting needle of the needle bed  40  for knitting the face yarn layer  12  stitches the face yarns  123  once; and in the same stroke, three ground yarns  112  are separately stitched once by each knitting needle of the needle bed  41  for knitting the ground yarn layer  11 , and a first knitting needle of every two knitting needles thereof further stitches one ground yarn  112  again. Here, in practical knitting and feeding of the embodiment of  FIG.  21   , a yarn tension of the face yarn  123  is preferably set as approximately 1/3.5 times a yarn tension of the ground yarn  112 . 
       FIG.  22    is a schematic diagram of one embodiment that a course ratio of the face yarn layer  12  to the ground yarn layer  11  is 1:3.5. Precisely, the course ratio is written as 1:3+( 2/4). In one stroke, each knitting needle of the needle bed  40  for knitting the face yarn layer  12  stitches the face yarns  123  once; and in the same stroke, three ground yarns  112  are separately stitched once by each knitting needle of the needle bed  41  for knitting the ground yarn layer  11 , and a first knitting needle and a second knitting needle of every four knitting needles thereof further stitch one ground yarn  112  again. Here, in practical knitting and feeding of the embodiment of  FIG.  22   , a yarn tension of the face yarn  123  is preferably set as approximately 1/3.5 times a yarn tension of the ground yarn  112 . 
       FIG.  23    is a schematic diagram of one embodiment that a course ratio of the face yarn layer  12  to the ground yarn layer  11  is 1:3.67, which is an approximate value. Precisely, the course ratio is written as 1:3+(⅔). In one stroke, each knitting needle of the needle bed  40  for knitting the face yarn layer  12  stitches the face yarns  123  once; and in the same stroke, three ground yarns  112  are separately stitched once by each knitting needle of the needle bed  41  for knitting the ground yarn layer  11 , and a first knitting needle and a second knitting needle of every three knitting needles thereof further stitch one ground yarn  112  again. Here, in practical knitting and feeding of the embodiment of  FIG.  23   , a yarn tension of the face yarn  123  is preferably set as approximately 1/3.67 times a yarn tension of the ground yarn  112 . 
       FIG.  24    is a schematic diagram of one embodiment that a course ratio of the face yarn layer  12  to the ground yarn layer  11  is 1:3.75. Precisely, the course ratio is written as 1:3+(¾). In one stroke, each knitting needle of the needle bed  40  for knitting the face yarn layer  12  stitches the face yarns  123  once; and in the same stroke, three ground yarns  112  are separately stitched once by each knitting needle of the needle bed  41  for knitting the ground yarn layer  11 , and a first knitting needle, a second knitting needle, and a third knitting needle of every four knitting needles thereof further stitch one ground yarn  112  again. Here, in practical knitting and feeding of the embodiment of  FIG.  24   , a yarn tension of the face yarn  123  is preferably set as approximately 1/3.75 times a yarn tension of the ground yarn  112 . 
       FIG.  25    is a schematic diagram of one embodiment that a course ratio of the face yarn layer  12  to the ground yarn layer  11  is 1:4. In one stroke, each knitting needle of the needle bed  40  for knitting the face yarn layer  12  stitches the face yarns  123  once; and in the same stroke, four ground yarns  112  are separately stitched once by each knitting needle of the needle bed  41  for knitting the ground yarn layer  11 . Here, in practical knitting and feeding of the embodiment of  FIG.  25   , a yarn tension of the face yarn  123  is preferably set as approximately ¼ times a yarn tension of the ground yarn  112 . 
     Please refer to  FIG.  1    and  FIG.  26   , a manufacturing method  20  for the knitted fabric  10  of the invention comprises following steps of: 
     step A  21 : double knitting the plurality of ground yarns  112  and the at least one face yarn  123  by the flat knitting machine to form the knitted fabric  10 ; and 
     step B  22 : ironing the knitted fabric  10 . 
     The invention avoids fabric curling caused by differences in numbers of yarn loops between the face yarn layer  12  and the ground yarn layer  11 , since provides step B  22  that further irons the knitted fabric  10  after the knitted fabric  10  is formed to increase flatness of the knitted fabric  10 . 
     Please refer to  FIG.  2    and  FIG.  27   . Based on the foregoing description, in one embodiment, the face yarn  123  is composed of the base yarn  124  and the polyurethane (PU) layer  125  which is wrapped around the outer surface of the base yarn  124  and comprises the leather fibers  122 . Since the face yarn  123  may shrink after being manufactured, the manufacturing method  20  further includes step C  23 : hot pressing the face yarn layer  12  after ironing the knitted fabric  10 . A heating copper piece or other objects with same functions can be implemented in step C  23  to perform hot pressing. Furthermore, step C  23  practically performs hot pressing on one single side of the face yarn layer  12  to prevent the face yarn  123  from shrinking to causes the knitted fabric  10  curling. 
     Please refer to  FIG.  27    and  FIG.  28   . In one embodiment, the manufacturing method  20  includes step D  24 : disposing a thermoplastic film  30  on the face yarn layer  12 , and hot pressing the thermoplastic film  30  to form a reinforcing layer  31 . In this embodiment, the knitted fabric  10  is hot pressed twice, wherein first is performed in step C  23 , and second is performed in step D  24 . However, there are two different subjects be hot pressed, one is that the face yarn layer  12  is hot pressed in the first hot pressing, and the other is that the thermoplastic film  30  is hot pressed in the second hot pressing. The thermoplastic film  30  after being hot pressed not only improves a strength of the face yarn layer  12 , but also improves a gloss of the face yarn layer  12 , so that the tactile feeling of the face yarn layer  12  is to be smoother, and the knitted fabric  10  is more aesthetic visually. In another embodiment, a mold (not shown in the figures) is applied to hot press on the thermoplastic film  30  in step D  24  to form a plurality of leather textures on the reinforcing layer  31 . Thus, not only the visual aesthetics of the knitted fabric  10  can be enhanced through the foregoing embodiment, but also the strength of the knitted fabric  10  can be enhanced.