Application of Xanthan Gum as a Pre-Treatment and Sharpness Evaluation for Inkjet Printing on Polyester

Inkjet printing on polyester fabric displays versatile environmental advantages. One of the significant benefits of inkjet printing is a dramatic enhancement of the printing quality. In this study, xanthan gum—a bio-based thickening agent accompanied by several salts—was adopted for the pretreatment of polyester fabric aiming at improving the sharpness and color depth of inkjet printed patterns. The influences of four metal salts (NaCl, KCl, CaCl2 and MgCl2) on inkjet printing performance were studied. More importantly, a quantitative method for evaluating the sharpness of an inkjet printed pattern was established according to the characteristics of anisotropy and isotropy of diffusion and adsorption of ink droplets on a fiber surface. Results showed that xanthan gum along with a low dosage of bivalent salts can significantly improve the color depth (K/S value) and sharpness of the printed polyester fabrics. It is feasible to evaluate the sharpness of inkjet printed polyester fabrics using a five-stage system, selecting the inkjet ellipse coefficient (T) and inkjet ellipse area (S), which can provide a quantitative and rapid evaluation method for defining inkjet printing.


Introduction
Inkjet printing technology has been widely applied in the textile field due to its ability to do short runs of production and lower cost advantages, when compared to conventional dyeing and printing processes [1]. Inkjet printing is becoming more important and more popular for polyester fiber printing. As a surface modification technique, the pretreatment of polyethylene terephthalate (PET) fibers for inkjet printing is very important. It increases the color intensity, enlarges the color gamut, improves the color fastness, and also plays an important role in the determination of the printing accuracy of inkjet printing [2,3]. In general, PET fibers for inkjet printing are surface modified with atmospheric-pressure air/He plasma [4] and a commercial pretreatment agent [2]. By considering the environment protection issues, the eco-friendly natural materials such as xanthan gum [5], chitosan or chitosan derivative [6], and β-cyclodextrin (β-CD) [7] are widely applied for the surface modification of PET fibers prior to inkjet printing. With application of these pretreatment agents, great improvements have been achieved in inkjet printing on PET fibers. However, the accuracy of printing is still not to the desired quality level. The pretreatment agents have a great influence on the diffusion shape and printing accuracy [8] by affecting the ink droplet spreading behavior and the trajectory of droplets [9,10].
Xanthan gum is a microbial polysaccharide branched structure consisting of a (1-4)-linked-β-d glucose backbone with ionic side chains. Low concentration of xanthan solution can display a thixotropic flow behavior [11,12]. Xanthan gum has been widely used in medicine, food technology, chemical industry, textile and other fields [13][14][15][16], due to its desirable thickening, suspension, thermal K/S value measurements of the printed PET fabric were obtained using a spectrophotometer (Ultra Scan XE, Hunter-Lab., Reston, VA, USA). The spectrophotometer was set to exclude specular reflection with a large aperture (D65 and 10° observer). K/S values with different wavelengths ranging from 400 to 700 nm within the visible spectrum and measured at 10 nm intervals were calculated according to Equation (1), then summed up as the K/S average value after four tests. The higher the K/S value, the higher the dye-uptake will be, resulting in better color yield. K/S = (1-R) 2

/ 2R
(1) where K is equal to the absorption coefficient; S is equal to the scattering coefficient; and R is equal to the reflectance of the colored sample. The rubbing fastness test was performed according to the standard (ISO 105-X12:2016) using Model 670 type friction fastness machine (James H and Heal Co., Halifax, West Yorkshire, England). The washing fastness test of the printed fabric was performed according to the standard (ISO 105-C02:2013) using wash fastness tester (Roaches International Co., Leek, Staffordshire, England). The light fastness test was performed according to the standard (AATCC TM16-2004) using ATLAS CT 3000+ Weather-Ometer / Fade-Ometer (Atlas Material Testing Technology, Chicago, IL, USA). The light source was Xenon-Arc exposure for 40 h. The air permeability test was performed according to the standard (ISO 9237:1995) using a YG461 air permeability tester (Nantong Hongda experiment instruments co. LTD, Jiangsu, China). The test area of the sample was 20 cm 2 , and air pressure was kept at 100 Pa.
Outline sharpness of the printing samples were examined using a 3D ultra-depth of field microscope (Vhx-5000, Keyence Co., Osaka, Japan). The line widths of the printed lines in both warp and weft directions were specified as 1.5 pounds. The practical widths were photographed by 3D K/S value measurements of the printed PET fabric were obtained using a spectrophotometer (Ultra Scan XE, Hunter-Lab., Reston, VA, USA). The spectrophotometer was set to exclude specular reflection with a large aperture (D 65 and 10 • observer). K/S values with different wavelengths ranging from 400 to 700 nm within the visible spectrum and measured at 10 nm intervals were calculated according to Equation (1), then summed up as the K/S average value after four tests. The higher the K/S value, the higher the dye-uptake will be, resulting in better color yield. (1) where K is equal to the absorption coefficient; S is equal to the scattering coefficient; and R is equal to the reflectance of the colored sample. The rubbing fastness test was performed according to the standard (ISO 105-X12:2016) using Model 670 type friction fastness machine (James H and Heal Co., Halifax, West Yorkshire, England). The washing fastness test of the printed fabric was performed according to the standard (ISO 105-C02:2013) using wash fastness tester (Roaches International Co., Leek, Staffordshire, England). The light fastness test was performed according to the standard (AATCC TM16-2004) using ATLAS CT 3000+ Weather-Ometer / Fade-Ometer (Atlas Material Testing Technology, Chicago, IL, USA). The light source was Xenon-Arc exposure for 40 h. The air permeability test was performed according to the standard (ISO 9237:1995) using a YG461 air permeability tester (Nantong Hongda experiment instruments co. LTD, Jiangsu, China). The test area of the sample was 20 cm 2 , and air pressure was kept at 100 Pa.
Outline sharpness of the printing samples were examined using a 3D ultra-depth of field microscope (Vhx-5000, Keyence Co., Osaka, Japan). The line widths of the printed lines in both warp and weft directions were specified as 1.5 pounds. The practical widths were photographed by 3D ultra-depth of field microscope and Pinnalce Studio Version 8.0 Software (Keyence Co., Osaka, Japan) with a magnification of 100 multiples. The line widths of the collected images are measured at 20 points in the warp and weft directions, respectively, and the average of the line widths is calculated. Figure 2 shows the preparation process of the saline xanthan gum and ink drop experiment. First, PET fabric was treated with a saline xanthan gum solution. Then, refer to the testing method of water absorbency of textiles (JIS L 1907-2010, Japanese Industrial Standard). The fabric was suspended, the four corners of the textile stretched to ensure that the fabric is kept in the stretched tile state. By using home-made micro-separator, the ink (10 µL) drops one centimeter vertically over the fabric. After the ink had completely absorbed for 30 min, the PET fabric was dried at 110 • C for 3 min. Finally, the length of the long axis (L a , cm) and the short axis (L b , cm) forming the ink mark ellipse are determined.  Figure 2 shows the preparation process of the saline xanthan gum and ink drop experiment. First, PET fabric was treated with a saline xanthan gum solution. Then, refer to the testing method of water absorbency of textiles (JIS L 1907-2010, Japanese Industrial Standard). The fabric was suspended, the four corners of the textile stretched to ensure that the fabric is kept in the stretched tile state. By using home-made micro-separator, the ink (10 μL) drops one centimeter vertically over the fabric. After the ink had completely absorbed for 30 min, the PET fabric was dried at 110 °C for 3 min. Finally, the length of the long axis (La, cm) and the short axis (Lb, cm) forming the ink mark ellipse are determined. According to the characteristics of anisotropy and isotropy of the adsorption and diffusion of ink droplets on the fabric surface, the sharpness of inkjet printing can be characterized by the length of the long axis, the length of the short axis and the area of the inkblot ellipse formed after the ink was completely absorbed.

Ink Drop Experiment and New Methods for the Definition of Inkjet Printing
After the ink was completely absorbed by the fabric, the formation of the ink ellipse coefficient (T) and the area of the ink ellipse (S, cm 2 ) were measured by the length of the long axis (La, cm) and the short axis (Lb, cm).
The new outline sharpness of the inkjet ink pattern samples were evaluated by the inkblot ellipse coefficient (T) and inkblot ellipse area (S).
The calculation is shown in Equation (2) and Equation (3). The data was tested 20 times and the results are averaged.
La was the long axis of the inkblot ellipse (it was typically in the weft direction of the fabric), cm. Lb was the short axis of the inkblot ellipse (it was typically in the warp direction of the fabric), cm. When the surface properties of the fabric in the warp and weft directions are isotropic, the closer the blot ellipse coefficient (T) is to 1.0, the better the definition of droplet adsorption and diffusion. The sharpness of droplet adsorption diffusion was evaluated according to the inkblot ellipse coefficient (T) and inkblot ellipse area (S). The evaluation criteria consist of five grades, with Grade 1 being the lowest and Grade 5 being the highest.
Grade 1, Sp ≥ Su, the definition rating is the poorest. Grade 2, Sp < Su, 0 < T ≤ 0.70, poor clarity rating. Grade 3, Sp < Su, 0.70 < T ≤ 0.80, medium clarity rating. Grade 4, Sp < Su, 0.80 < T ≤ 0.95, good definition rating. According to the characteristics of anisotropy and isotropy of the adsorption and diffusion of ink droplets on the fabric surface, the sharpness of inkjet printing can be characterized by the length of the long axis, the length of the short axis and the area of the inkblot ellipse formed after the ink was completely absorbed.
After the ink was completely absorbed by the fabric, the formation of the ink ellipse coefficient (T) and the area of the ink ellipse (S, cm 2 ) were measured by the length of the long axis (L a , cm) and the short axis (L b , cm).
The new outline sharpness of the inkjet ink pattern samples were evaluated by the inkblot ellipse coefficient (T) and inkblot ellipse area (S).
The calculation is shown in Equations (2) and (3). The data was tested 20 times and the results are averaged.
L a was the long axis of the inkblot ellipse (it was typically in the weft direction of the fabric), cm. L b was the short axis of the inkblot ellipse (it was typically in the warp direction of the fabric), cm.
When the surface properties of the fabric in the warp and weft directions are isotropic, the closer the blot ellipse coefficient (T) is to 1.0, the better the definition of droplet adsorption and diffusion. The sharpness of droplet adsorption diffusion was evaluated according to the inkblot ellipse coefficient (T) and inkblot ellipse area (S). The evaluation criteria consist of five grades, with Grade 1 being the lowest and Grade 5 being the highest.
Sp was the area of the pretreated fabric droplet (cm 2 ), Su was the area of the untreated fabric droplet (cm 2 ).  The impact of bivalent salts (Ca 2+ and Mg 2+ ) on the K/S value of inkjet printed fabric was significantly larger than that of monovalent salts (Na + and K + ). With the increase of salt concentrations, the K/S value of inkjet printed fabric increases. Table 1 shows a relationship the K/S value (y) and salt concentration (x/mol.L -1 ). The K/S value has a relationship with salt concentration (x/mol.L -1 ), y = x/(C1 + C2·x) + C0. The variance test shows that the decision coefficient (R 2 ) is close to 1, the F value is bigger, and the p-value is very small. It shows that the matched curve of mathematical mode is reliable. When the concentration of salt ranged from 0.01 to 0.2 mol/L, the K/S value showed a significant increase compared with salt-free xanthan gum solutions. When the salt concentration continued to increase from 0.2 to 0.5 mol/L, C1 was small, and C1 + C2·x ≈ C2·x, the change of K/S value of salt was small. As the K/S value decreases, the order of the cation salts is Ca 2+ > Mg 2+ > Na + > K + . It could be that XG solution behaved like a pseudo-plasticity fluid and the relationship between its viscosity and shear rate could be described by the power-law model. The concentration of XG solution had little influence on the linear viscoelastic range [26]. The apparent viscosity and viscoelasticity of XG solutions decrease with the addition of inorganic cations [27]. Xanthan's viscoelastic and morphological properties may be tuned by addition of surfactants and salt [28]. Compared with the unsalted XG, NaCl and CaCl2 tended to produce a more drastic decrease of apparent viscosities of XG dispersions than KCl and MgCl2 [29]. Chloride and formate potassium brines not only increase the viscosity of the solution but also extend the shear thinning behavior to temperatures near 200 °C, however, the ordered conformation still dominates the rheological behavior [30]. The water absorption of XG/WCS (water chestnut starch) solution was improved drastically by the addition of NaCl [31]. It illustrates that xanthan gum with bivalent salt, which is easy to absorb and permeates with low viscosity, is more suitable for the pretreatment of inkjet printing. In addition, the salt has the effect of reducing the potential of the fiber surface and the double layer, which can help to reduce the electrostatic repulsion of the dye with the fabric surface (xanthan The impact of bivalent salts (Ca 2+ and Mg 2+ ) on the K/S value of inkjet printed fabric was significantly larger than that of monovalent salts (Na + and K + ). With the increase of salt concentrations, the K/S value of inkjet printed fabric increases. Table 1 shows a relationship the K/S value (y) and salt concentration (x/mol.L -1 ). The K/S value has a relationship with salt concentration (x/mol.L -1 ), y = x/(C 1 + C 2 ·x) + C 0 . The variance test shows that the decision coefficient (R 2 ) is close to 1, the F value is bigger, and the p-value is very small. It shows that the matched curve of mathematical mode is reliable. When the concentration of salt ranged from 0.01 to 0.2 mol/L, the K/S value showed a significant increase compared with salt-free xanthan gum solutions. When the salt concentration continued to increase from 0.2 to 0.5 mol/L, C 1 was small, and C 1 + C 2 ·x ≈ C 2 ·x, the change of K/S value of salt was small. As the K/S value decreases, the order of the cation salts is Ca 2+ > Mg 2+ > Na + > K + . It could be that XG solution behaved like a pseudo-plasticity fluid and the relationship between its viscosity and shear rate could be described by the power-law model. The concentration of XG solution had little influence on the linear viscoelastic range [26]. The apparent viscosity and viscoelasticity of XG solutions decrease with the addition of inorganic cations [27]. Xanthan's viscoelastic and morphological properties may be tuned by addition of surfactants and salt [28]. Compared with the unsalted XG, NaCl and CaCl 2 tended to produce a more drastic decrease of apparent viscosities of XG dispersions than KCl and MgCl 2 [29]. Chloride and formate potassium brines not only increase the viscosity of the solution but also extend the shear thinning behavior to temperatures near 200 • C, however, the ordered conformation still dominates the rheological behavior [30]. The water absorption of XG/WCS (water chestnut starch) solution was improved drastically by the addition of NaCl [31]. It illustrates that Polymers 2019, 11, 1504 6 of 12 xanthan gum with bivalent salt, which is easy to absorb and permeates with low viscosity, is more suitable for the pretreatment of inkjet printing. In addition, the salt has the effect of reducing the potential of the fiber surface and the double layer, which can help to reduce the electrostatic repulsion of the dye with the fabric surface (xanthan gum), promotes the absorption and fixation of the dye with the fibers, and also improves the dry rubbing fastness grade and apparent color gain of the dye. Under the optimal pretreatment condition, the K/S of treated PET fabric using 0.1 mol/L CaCl 2 and 0.3% xanthan gum was higher than that of treated PET fabric only using 0.3% xanthan gum, it can be calculated that K/S increased by 26.99%. The color fastness grade of treated PET fabric using CaCl 2 and xanthan gum was 4-5 (dry rubbing), 4 (wet rubbing), 4-5 (washing), 5 (light), respectively. The higher dry rubbing fastness grade was achieved with treated PET fabric using CaCl 2 than that using only xanthan gum (dry rubbing fastness grade was 4). Other color fastness grade was the same as using CaCl 2 and xanthan gum, using only xanthan gum, respectively. Figure 4 shows the weight ratio and air permeability (Figure 4a), FTIR spectrum ( Figure 4b) and SEM image (Figure 4c) of printed fabric treated with the xanthan gum pretreatment and finally washing. gum), promotes the absorption and fixation of the dye with the fibers, and also improves the dry rubbing fastness grade and apparent color gain of the dye. Under the optimal pretreatment condition, the K/S of treated PET fabric using 0.1 mol/L CaCl2 and 0.3% xanthan gum was higher than that of treated PET fabric only using 0.3% xanthan gum, it can be calculated that K/S increased by 26.99%. The color fastness grade of treated PET fabric using CaCl2 and xanthan gum was 4-5 (dry rubbing), 4 (wet rubbing), 4-5 (washing), 5 (light), respectively. The higher dry rubbing fastness grade was achieved with treated PET fabric using CaCl2 than that using only xanthan gum (dry rubbing fastness grade was 4). Other color fastness grade was the same as using CaCl2 and xanthan gum, using only xanthan gum, respectively.  When PET fibers were prepared using CaCl2 and xanthan gum, the weight ratio of the adsorbed xanthan gum and air permeability of fibers was 4.36%, and 241.7 mm/s, respectively (Figure 4a). Figure 4b and Figure 4c clearly show that sample A has the characteristic peak at 3400 cm -1 , which is When PET fibers were prepared using CaCl 2 and xanthan gum, the weight ratio of the adsorbed xanthan gum and air permeability of fibers was 4.36%, and 241.7 mm/s, respectively (Figure 4a). Figure 4b,c clearly show that sample A has the characteristic peak at 3400 cm −1 , which is assigned to the O-H stretching of xanthan gum, and the polymer film of xanthan gum is adhesive on the treated fiber surfaces. When PET fibers were applied in the post-treatment, the weight ratio and air permeability of fibers were 0.48%, and 311.6 mm/s, respectively. It was indicated that water soluble xanthan gum is easily washed away from the fabric during the post-treatment washing process. Xanthan gum did not affect the microstructural characterization of PET fibers, due to the water solubility and ease of washing. In fact, the amounts of xanthan gum were washed away 88.96% during post-treatment. The air permeability of fibers was almost the same as untreated PET fibers (air permeability was 313.3 mm/s).

Effect of Salt Concentration on the K/S Value of Inkjet Printing
Xanthan gum is shown to be minimally retained when observed by SEM images of the fibers, i.e. the relatively smooth surfaces which are visualized on sample B. The sample B characteristic peak of O-H stretching of xanthan gum disappears. Therefore, it does not have an adverse influence on PET fibers, which retain the porous nature of the fabric after post-treatment. assigned to the O-H stretching of xanthan gum, and the polymer film of xanthan gum is adhesive on the treated fiber surfaces. When PET fibers were applied in the post-treatment, the weight ratio and air permeability of fibers were 0.48%, and 311.6 mm/s, respectively. It was indicated that water soluble xanthan gum is easily washed away from the fabric during the post-treatment washing process. Xanthan gum did not affect the microstructural characterization of PET fibers, due to the water solubility and ease of washing. In fact, the amounts of xanthan gum were washed away 88.96% during post-treatment. The air permeability of fibers was almost the same as untreated PET fibers (air permeability was 313.3 mm/s). Xanthan gum is shown to be minimally retained when observed by SEM images of the fibers, i.e. the relatively smooth surfaces which are visualized on sample B. The sample B characteristic peak of O-H stretching of xanthan gum disappears. Therefore, it does not have an adverse influence on PET fibers, which retain the porous nature of the fabric after post-treatment. Figure 5 and Figure 6 show the printed lines width in the warp and weft directions on the pretreatment with four kinds of saline xanthan gum. Salt concentration was 0-0.5 mol/L, respectively.

Effect of Salt Concentration on the Outline Sharpness of Inkjet Printing
The printed lines in the warp direction were narrower than those in the weft direction. Due to the difference between fabric structure and capillary effect, the ink droplet infiltration along the latitudinal direction is more serious, and the width of the latitudinal ink droplet decreases more obviously under the action of salt, but the meridional direction still has better printing sharpness than the latitudinal direction.  The printed lines on the pretreated fiber using bivalent salt were narrower than those using monovalent salt both in the warp and weft directions. When the salt concentration is low (0.01-0.1 mol/L), the line width in warp direction improved 8.89-9.83% (CaCl2), 4.81-11.12% (MgCl2), the line width in the weft direction improved 28.17-48.78% (CaCl2), 28.75-43.97% (MgCl2), respectively. When the salt concentration continues to increase, the line width in the warp direction improved  The printed lines in the warp direction were narrower than those in the weft direction. Due to the difference between fabric structure and capillary effect, the ink droplet infiltration along the latitudinal direction is more serious, and the width of the latitudinal ink droplet decreases more obviously under the action of salt, but the meridional direction still has better printing sharpness than the latitudinal direction.
The printed lines on the pretreated fiber using bivalent salt were narrower than those using monovalent salt both in the warp and weft directions. When the salt concentration is low (0.01-0.1 mol/L), the line width in warp direction improved 8.89-9.83% (CaCl 2 ), 4.81-11.12% (MgCl 2 ), the line width in the weft direction improved 28.17-48.78% (CaCl 2 ), 28.75-43.97% (MgCl 2 ), respectively. When the salt concentration continues to increase, the line width in the warp direction improved more distinctly than those in the weft direction using monovalent salts. However the line width in the weft direction improved more distinctly than those in the warp direction using bivalent salts. When the salt concentration is high (0.4-0.5 mol/L), the line width in the warp and weft directions improved a small amount. It could be that when PET fibers were treated using the saline XG solution, the salt leant the fabric surface a certain positive charge, which slowed down the seepage of ink drops caused by electrostatic repulsion among xanthan gum, fabric and dye, and improved the fiber surface's adhesion to the ink. The salt ions reduce the surface tension of the fabric, which makes it difficult for the ink droplets to spread on the fiber surface, and the area of the formed ink droplets is significantly less than that of the untreated fabric [20,32]. In the process of inkjet printing, the ink droplets are ejected from the nozzle, and the area formed by the ink droplets on the fabric lessens due to the effect of salt, which is conducive to the infiltration of the ink droplets into the fiber, and slowing down the infiltration of the ink droplets along the warp and weft directions, which results in decreased sharpness of the printing pattern [8,25,33].

New Evaluation Method of Outline Sharpness for Inkjet Printing
In general, outline sharpness and the surface appearance of inkjet printing fabrics are very important, however it is difficult to quantify the outline sharpness with data. There has not been any studies about the outline sharpness, besides the line width of actual inkjet printing. Table 2 shows the results of the ink drop experiment and line width of actual inkjet printing. As shown in Table 2, there is a significant difference in the adsorption and diffusion of ink drops in the warp and weft directions when the ink drops are directly dropped on the surface of the fabric. We clarify the definition of inkjet printing for five grades.
Grade 1, the definition rating of the fiber is the poorest. L a and L b are 2.5, and 1.5 cm, respectively. The inkblot ellipse area (S) is 2.94 cm 2 (>2.86 cm 2 , untreated fiber). Line widths of actual printing in the warp and weft directions are 1353.3, and 551.3 µm, respectively. The definition rating of the treated-fiber is also the poorest, the definition of the inkjet printing is Grade 1.
Grade 2, the definition rating of the treated fiber is due to the poor clarity rating. Compared to Grade 1, the L a , L b and inkblot ellipse area are decreased, and the line widths of the actual printing in the warp and weft directions are also decreased. The range of L a , L b , T (the blot ellipse coefficient) and S are 1.9-2.4 cm, 1.  In general, outline sharpness and the surface appearance of inkjet printing fabrics are very important, however it is difficult to quantify the outline sharpness with data. There has not been any studies about the outline sharpness, besides the line width of actual inkjet printing. Table 2 shows the results of the ink drop experiment and line width of actual inkjet printing. As shown in Table 2, there is a significant difference in the adsorption and diffusion of ink drops in the warp and weft directions when the ink drops are directly dropped on the surface of the fabric. We clarify the definition of inkjet printing for five grades.  In general, outline sharpness and the surface appearance of inkjet printing fabrics are very important, however it is difficult to quantify the outline sharpness with data. There has not been any studies about the outline sharpness, besides the line width of actual inkjet printing. Table 2 shows the results of the ink drop experiment and line width of actual inkjet printing. As shown in Table 2, there is a significant difference in the adsorption and diffusion of ink drops in the warp and weft directions when the ink drops are directly dropped on the surface of the fabric. We clarify the definition of inkjet printing for five grades.

New Evaluation Method of Outline Sharpness for Inkjet Printing
In general, outline sharpness and the surface appearance of inkjet printing fabrics are very important, however it is difficult to quantify the outline sharpness with data. There has not been any studies about the outline sharpness, besides the line width of actual inkjet printing. Table 2 shows the results of the ink drop experiment and line width of actual inkjet printing. As shown in Table 2, there is a significant difference in the adsorption and diffusion of ink drops in the warp and weft directions when the ink drops are directly dropped on the surface of the fabric. We clarify the definition of inkjet printing for five grades.

New Evaluation Method of Outline Sharpness for Inkjet Printing
In general, outline sharpness and the surface appearance of inkjet printing fabrics are very important, however it is difficult to quantify the outline sharpness with data. There has not been any studies about the outline sharpness, besides the line width of actual inkjet printing. Table 2 shows the results of the ink drop experiment and line width of actual inkjet printing. As shown in Table 2, there is a significant difference in the adsorption and diffusion of ink drops in the warp and weft directions when the ink drops are directly dropped on the surface of the fabric. We clarify the definition of inkjet printing for five grades. in decreased sharpness of the printing pattern [8,25,33].

New Evaluation Method of Outline Sharpness for Inkjet Printing
In general, outline sharpness and the surface appearance of inkjet printing fabrics are very important, however it is difficult to quantify the outline sharpness with data. There has not been any studies about the outline sharpness, besides the line width of actual inkjet printing. Table 2 shows the results of the ink drop experiment and line width of actual inkjet printing. As shown in Table 2, there is a significant difference in the adsorption and diffusion of ink drops in the warp and weft directions when the ink drops are directly dropped on the surface of the fabric. We clarify the definition of inkjet printing for five grades. slowing down the infiltration of the ink droplets along the warp and weft directions, which results in decreased sharpness of the printing pattern [8,25,33].

New Evaluation Method of Outline Sharpness for Inkjet Printing
In general, outline sharpness and the surface appearance of inkjet printing fabrics are very important, however it is difficult to quantify the outline sharpness with data. There has not been any studies about the outline sharpness, besides the line width of actual inkjet printing. Table 2 shows the results of the ink drop experiment and line width of actual inkjet printing. As shown in Table 2, there is a significant difference in the adsorption and diffusion of ink drops in the warp and weft directions when the ink drops are directly dropped on the surface of the fabric. We clarify the definition of inkjet printing for five grades. slowing down the infiltration of the ink droplets along the warp and weft directions, which results in decreased sharpness of the printing pattern [8,25,33].

New Evaluation Method of Outline Sharpness for Inkjet Printing
In general, outline sharpness and the surface appearance of inkjet printing fabrics are very important, however it is difficult to quantify the outline sharpness with data. There has not been any studies about the outline sharpness, besides the line width of actual inkjet printing. Table 2 shows the results of the ink drop experiment and line width of actual inkjet printing. As shown in Table 2, there is a significant difference in the adsorption and diffusion of ink drops in the warp and weft directions when the ink drops are directly dropped on the surface of the fabric. We clarify the definition of inkjet printing for five grades. due to the effect of salt, which is conducive to the infiltration of the ink droplets into the fiber, and slowing down the infiltration of the ink droplets along the warp and weft directions, which results in decreased sharpness of the printing pattern [8,25,33].

New Evaluation Method of Outline Sharpness for Inkjet Printing
In general, outline sharpness and the surface appearance of inkjet printing fabrics are very important, however it is difficult to quantify the outline sharpness with data. There has not been any studies about the outline sharpness, besides the line width of actual inkjet printing. Table 2 shows the results of the ink drop experiment and line width of actual inkjet printing. As shown in Table 2, there is a significant difference in the adsorption and diffusion of ink drops in the warp and weft directions when the ink drops are directly dropped on the surface of the fabric. We clarify the definition of inkjet printing for five grades. droplets are ejected from the nozzle, and the area formed by the ink droplets on the fabric lessens due to the effect of salt, which is conducive to the infiltration of the ink droplets into the fiber, and slowing down the infiltration of the ink droplets along the warp and weft directions, which results in decreased sharpness of the printing pattern [8,25,33].

New Evaluation Method of Outline Sharpness for Inkjet Printing
In general, outline sharpness and the surface appearance of inkjet printing fabrics are very important, however it is difficult to quantify the outline sharpness with data. There has not been any studies about the outline sharpness, besides the line width of actual inkjet printing. Table 2 shows the results of the ink drop experiment and line width of actual inkjet printing. As shown in Table 2, there is a significant difference in the adsorption and diffusion of ink drops in the warp and weft directions when the ink drops are directly dropped on the surface of the fabric. We clarify the definition of inkjet printing for five grades. significantly less than that of the untreated fabric [20,32]. In the process of inkjet printing, the ink droplets are ejected from the nozzle, and the area formed by the ink droplets on the fabric lessens due to the effect of salt, which is conducive to the infiltration of the ink droplets into the fiber, and slowing down the infiltration of the ink droplets along the warp and weft directions, which results in decreased sharpness of the printing pattern [8,25,33].

New Evaluation Method of Outline Sharpness for Inkjet Printing
In general, outline sharpness and the surface appearance of inkjet printing fabrics are very important, however it is difficult to quantify the outline sharpness with data. There has not been any studies about the outline sharpness, besides the line width of actual inkjet printing. Table 2 shows the results of the ink drop experiment and line width of actual inkjet printing. As shown in Table 2, there is a significant difference in the adsorption and diffusion of ink drops in the warp and weft directions when the ink drops are directly dropped on the surface of the fabric. We clarify the definition of inkjet printing for five grades. difficult for the ink droplets to spread on the fiber surface, and the area of the formed ink droplets is significantly less than that of the untreated fabric [20,32]. In the process of inkjet printing, the ink droplets are ejected from the nozzle, and the area formed by the ink droplets on the fabric lessens due to the effect of salt, which is conducive to the infiltration of the ink droplets into the fiber, and slowing down the infiltration of the ink droplets along the warp and weft directions, which results in decreased sharpness of the printing pattern [8,25,33].

New Evaluation Method of Outline Sharpness for Inkjet Printing
In general, outline sharpness and the surface appearance of inkjet printing fabrics are very important, however it is difficult to quantify the outline sharpness with data. There has not been any studies about the outline sharpness, besides the line width of actual inkjet printing. Table 2 shows the results of the ink drop experiment and line width of actual inkjet printing. As shown in Table 2, there is a significant difference in the adsorption and diffusion of ink drops in the warp and weft directions when the ink drops are directly dropped on the surface of the fabric. We clarify the definition of inkjet printing for five grades. surface's adhesion to the ink. The salt ions reduce the surface tension of the fabric, which makes it difficult for the ink droplets to spread on the fiber surface, and the area of the formed ink droplets is significantly less than that of the untreated fabric [20,32]. In the process of inkjet printing, the ink droplets are ejected from the nozzle, and the area formed by the ink droplets on the fabric lessens due to the effect of salt, which is conducive to the infiltration of the ink droplets into the fiber, and slowing down the infiltration of the ink droplets along the warp and weft directions, which results in decreased sharpness of the printing pattern [8,25,33].

New Evaluation Method of Outline Sharpness for Inkjet Printing
In general, outline sharpness and the surface appearance of inkjet printing fabrics are very important, however it is difficult to quantify the outline sharpness with data. There has not been any studies about the outline sharpness, besides the line width of actual inkjet printing. Table 2 shows the results of the ink drop experiment and line width of actual inkjet printing. As shown in Table 2, there is a significant difference in the adsorption and diffusion of ink drops in the warp and weft directions when the ink drops are directly dropped on the surface of the fabric. We clarify the definition of inkjet printing for five grades.    (1) Observe definition: (worst clarity rating ), direction improved 8.89-9.83% (CaCl2), 4.81-11.12% (MgCl2), the line proved 28.17-48.78% (CaCl2), 28.75-43.97% (MgCl2), respectively. ontinues to increase, the line width in the warp direction improved he weft direction using monovalent salts. However the line width in ore distinctly than those in the warp direction using bivalent salts. high (0.4-0.5 mol/L), the line width in the warp and weft directions uld be that when PET fibers were treated using the saline XG solution, certain positive charge, which slowed down the seepage of ink drops ion among xanthan gum, fabric and dye, and improved the fiber he salt ions reduce the surface tension of the fabric, which makes it spread on the fiber surface, and the area of the formed ink droplets is he untreated fabric [20,32]. In the process of inkjet printing, the ink ozzle, and the area formed by the ink droplets on the fabric lessens is conducive to the infiltration of the ink droplets into the fiber, and f the ink droplets along the warp and weft directions, which results rinting pattern [8,25,33].   The length of the ink drops and line width of actual printing in the weft direction are large, while the length of the ink drops and line width of actual printing in the warp direction are short. The fabric presented has obvious anisotropy in warp and weft directions, which mainly affects the orientation and organizational structure of fibers [34]; the ink was elliptical and the T value was low. The salt, especially the bivalent salt, can significantly reduce the length of the ink blots in the warp and weft directions of the fabric. The ink area decreased, the ink shape changed to a circular shape, and the T value tended to 1.0. When the bivalent salt concentration is 0.1-0.5 mol/L, the warp and weft of fabric are isotropic, the lengths of warp and weft ink are equal, and the T value is 1.0. Therefore, the "short axis/long axis" value of ink droplets forming ink blots is introduced as an index to characterize the definition of inkjet printing ink droplets, which can quantify the influence of pretreatment on the definition of inkjet printing. By considering the difference of ink absorption and diffusion between pretreated and untreated fabric surface properties, the index of ink absorption and diffusion area was introduced. When the S of pretreated cloth is larger than untreated cloth, it is impossible to improve the sharpness of inkjet printing. And the S of pretreated cloth smaller than untreated cloth is a sufficient condition to improve the sharpness of inkjet printing. Table 3 shows that the clarity of drop is intrinsically related to the sharpness of the inkjet printing. this can be observed clearly as the "long/short axis shaft" value can reflect the latitude and longitude inkjet printing to the size of anisotropy, and also conforms to the observer the definition estimation results of the visual design style, thus establishing that the drops of clarity rating method is feasible. This provides a new method for quantitative evaluation of inkjet printing resolution. Table 3. Results of the ink drop experiment, grade of definition and pattern of actual printing.

Definition of Grades T Pattern I Pattern II Definition of Marginal Definition of Internal
Grade 1 0.60 presented has obvious anisotropy in warp and weft directions, which mainly affects the orientation and organizational structure of fibers [34]; the ink was elliptical and the T value was low. The salt, especially the bivalent salt, can significantly reduce the length of the ink blots in the warp and weft directions of the fabric. The ink area decreased, the ink shape changed to a circular shape, and the T value tended to 1.0. When the bivalent salt concentration is 0.1-0.5 mol/L, the warp and weft of fabric are isotropic, the lengths of warp and weft ink are equal, and the T value is 1.0. Therefore, the "short axis/long axis" value of ink droplets forming ink blots is introduced as an index to characterize the definition of inkjet printing ink droplets, which can quantify the influence of pretreatment on the definition of inkjet printing. By considering the difference of ink absorption and diffusion between pretreated and untreated fabric surface properties, the index of ink absorption and diffusion area was introduced. When the S of pretreated cloth is larger than untreated cloth, it is impossible to improve the sharpness of inkjet printing. And the S of pretreated cloth smaller than untreated cloth is a sufficient condition to improve the sharpness of inkjet printing. Table 3 shows that the clarity of drop is intrinsically related to the sharpness of the inkjet printing. this can be observed clearly as the "long/short axis shaft" value can reflect the latitude and longitude inkjet printing to the size of anisotropy, and also conforms to the observer the definition estimation results of the visual design style, thus establishing that the drops of clarity rating method is feasible. This provides a new method for quantitative evaluation of inkjet printing resolution. presented has obvious anisotropy in warp and weft directions, which mainly affects the orientation and organizational structure of fibers [34]; the ink was elliptical and the T value was low. The salt, especially the bivalent salt, can significantly reduce the length of the ink blots in the warp and weft directions of the fabric. The ink area decreased, the ink shape changed to a circular shape, and the T value tended to 1.0. When the bivalent salt concentration is 0.1-0.5 mol/L, the warp and weft of fabric are isotropic, the lengths of warp and weft ink are equal, and the T value is 1.0. Therefore, the "short axis/long axis" value of ink droplets forming ink blots is introduced as an index to characterize the definition of inkjet printing ink droplets, which can quantify the influence of pretreatment on the definition of inkjet printing. By considering the difference of ink absorption and diffusion between pretreated and untreated fabric surface properties, the index of ink absorption and diffusion area was introduced. When the S of pretreated cloth is larger than untreated cloth, it is impossible to improve the sharpness of inkjet printing. And the S of pretreated cloth smaller than untreated cloth is a sufficient condition to improve the sharpness of inkjet printing. Table 3 shows that the clarity of drop is intrinsically related to the sharpness of the inkjet printing. this can be observed clearly as the "long/short axis shaft" value can reflect the latitude and longitude inkjet printing to the size of anisotropy, and also conforms to the observer the definition estimation results of the visual design style, thus establishing that the drops of clarity rating method is feasible. This provides a new method for quantitative evaluation of inkjet printing resolution. presented has obvious anisotropy in warp and weft directions, which mainly affects the orientation and organizational structure of fibers [34]; the ink was elliptical and the T value was low. The salt, especially the bivalent salt, can significantly reduce the length of the ink blots in the warp and weft directions of the fabric. The ink area decreased, the ink shape changed to a circular shape, and the T value tended to 1.0. When the bivalent salt concentration is 0.1-0.5 mol/L, the warp and weft of fabric are isotropic, the lengths of warp and weft ink are equal, and the T value is 1.0. Therefore, the "short axis/long axis" value of ink droplets forming ink blots is introduced as an index to characterize the definition of inkjet printing ink droplets, which can quantify the influence of pretreatment on the definition of inkjet printing. By considering the difference of ink absorption and diffusion between pretreated and untreated fabric surface properties, the index of ink absorption and diffusion area was introduced. When the S of pretreated cloth is larger than untreated cloth, it is impossible to improve the sharpness of inkjet printing. And the S of pretreated cloth smaller than untreated cloth is a sufficient condition to improve the sharpness of inkjet printing. Table 3 shows that the clarity of drop is intrinsically related to the sharpness of the inkjet printing. this can be observed clearly as the "long/short axis shaft" value can reflect the latitude and longitude inkjet printing to the size of anisotropy, and also conforms to the observer the definition estimation results of the visual design style, thus establishing that the drops of clarity rating method is feasible. This provides a new method for quantitative evaluation of inkjet printing resolution. presented has obvious anisotropy in warp and weft directions, which mainly affects the orientation and organizational structure of fibers [34]; the ink was elliptical and the T value was low. The salt, especially the bivalent salt, can significantly reduce the length of the ink blots in the warp and weft directions of the fabric. The ink area decreased, the ink shape changed to a circular shape, and the T value tended to 1.0. When the bivalent salt concentration is 0.1-0.5 mol/L, the warp and weft of fabric are isotropic, the lengths of warp and weft ink are equal, and the T value is 1.0. Therefore, the "short axis/long axis" value of ink droplets forming ink blots is introduced as an index to characterize the definition of inkjet printing ink droplets, which can quantify the influence of pretreatment on the definition of inkjet printing. By considering the difference of ink absorption and diffusion between pretreated and untreated fabric surface properties, the index of ink absorption and diffusion area was introduced. When the S of pretreated cloth is larger than untreated cloth, it is impossible to improve the sharpness of inkjet printing. And the S of pretreated cloth smaller than untreated cloth is a sufficient condition to improve the sharpness of inkjet printing. Table 3 shows that the clarity of drop is intrinsically related to the sharpness of the inkjet printing. this can be observed clearly as the "long/short axis shaft" value can reflect the latitude and longitude inkjet printing to the size of anisotropy, and also conforms to the observer the definition estimation results of the visual design style, thus establishing that the drops of clarity rating method is feasible. This provides a new method for quantitative evaluation of inkjet printing resolution. more distinctly than those in the weft direction using monovalent salts. However the line width in the weft direction improved more distinctly than those in the warp direction using bivalent salts. When the salt concentration is high (0.4-0.5 mol/L), the line width in the warp and weft directions improved a small amount. It could be that when PET fibers were treated using the saline XG solution, the salt leant the fabric surface a certain positive charge, which slowed down the seepage of ink drops caused by electrostatic repulsion among xanthan gum, fabric and dye, and improved the fiber surface's adhesion to the ink. The salt ions reduce the surface tension of the fabric, which makes it difficult for the ink droplets to spread on the fiber surface, and the area of the formed ink droplets is significantly less than that of the untreated fabric [20,32]. In the process of inkjet printing, the ink droplets are ejected from the nozzle, and the area formed by the ink droplets on the fabric lessens due to the effect of salt, which is conducive to the infiltration of the ink droplets into the fiber, and slowing down the infiltration of the ink droplets along the warp and weft directions, which results in decreased sharpness of the printing pattern [8,25,33].

New Evaluation Method of Outline Sharpness for Inkjet Printing
In general, outline sharpness and the surface appearance of inkjet printing fabrics are very important, however it is difficult to quantify the outline sharpness with data. There has not been any studies about the outline sharpness, besides the line width of actual inkjet printing. Table 2 shows the results of the ink drop experiment and line width of actual inkjet printing. As shown in Table 2, there is a significant difference in the adsorption and diffusion of ink drops in the warp and weft directions when the ink drops are directly dropped on the surface of the fabric. We clarify the definition of inkjet printing for five grades. more distinctly than those in the weft direction using monovalent salts. However the line width in the weft direction improved more distinctly than those in the warp direction using bivalent salts. When the salt concentration is high (0.4-0.5 mol/L), the line width in the warp and weft directions improved a small amount. It could be that when PET fibers were treated using the saline XG solution, the salt leant the fabric surface a certain positive charge, which slowed down the seepage of ink drops caused by electrostatic repulsion among xanthan gum, fabric and dye, and improved the fiber surface's adhesion to the ink. The salt ions reduce the surface tension of the fabric, which makes it difficult for the ink droplets to spread on the fiber surface, and the area of the formed ink droplets is significantly less than that of the untreated fabric [20,32]. In the process of inkjet printing, the ink droplets are ejected from the nozzle, and the area formed by the ink droplets on the fabric lessens due to the effect of salt, which is conducive to the infiltration of the ink droplets into the fiber, and slowing down the infiltration of the ink droplets along the warp and weft directions, which results in decreased sharpness of the printing pattern [8,25,33].

New Evaluation Method of Outline Sharpness for Inkjet Printing
In general, outline sharpness and the surface appearance of inkjet printing fabrics are very important, however it is difficult to quantify the outline sharpness with data. There has not been any studies about the outline sharpness, besides the line width of actual inkjet printing. Table 2 shows the results of the ink drop experiment and line width of actual inkjet printing. As shown in Table 2, there is a significant difference in the adsorption and diffusion of ink drops in the warp and weft directions when the ink drops are directly dropped on the surface of the fabric. We clarify the definition of inkjet printing for five grades. and organizational structure of fibers [34]; the ink was elliptical and the T value was low. The salt, especially the bivalent salt, can significantly reduce the length of the ink blots in the warp and weft directions of the fabric. The ink area decreased, the ink shape changed to a circular shape, and the T value tended to 1.0. When the bivalent salt concentration is 0.1-0.5 mol/L, the warp and weft of fabric are isotropic, the lengths of warp and weft ink are equal, and the T value is 1.0. Therefore, the "short axis/long axis" value of ink droplets forming ink blots is introduced as an index to characterize the definition of inkjet printing ink droplets, which can quantify the influence of pretreatment on the definition of inkjet printing. By considering the difference of ink absorption and diffusion between pretreated and untreated fabric surface properties, the index of ink absorption and diffusion area was introduced. When the S of pretreated cloth is larger than untreated cloth, it is impossible to improve the sharpness of inkjet printing. And the S of pretreated cloth smaller than untreated cloth is a sufficient condition to improve the sharpness of inkjet printing. Table 3 shows that the clarity of drop is intrinsically related to the sharpness of the inkjet printing. this can be observed clearly as the "long/short axis shaft" value can reflect the latitude and longitude inkjet printing to the size of anisotropy, and also conforms to the observer the definition estimation results of the visual design style, thus establishing that the drops of clarity rating method is feasible. This provides a new method for quantitative evaluation of inkjet printing resolution. and organizational structure of fibers [34]; the ink was elliptical and the T value was low. The salt, especially the bivalent salt, can significantly reduce the length of the ink blots in the warp and weft directions of the fabric. The ink area decreased, the ink shape changed to a circular shape, and the T value tended to 1.0. When the bivalent salt concentration is 0.1-0.5 mol/L, the warp and weft of fabric are isotropic, the lengths of warp and weft ink are equal, and the T value is 1.0. Therefore, the "short axis/long axis" value of ink droplets forming ink blots is introduced as an index to characterize the definition of inkjet printing ink droplets, which can quantify the influence of pretreatment on the definition of inkjet printing. By considering the difference of ink absorption and diffusion between pretreated and untreated fabric surface properties, the index of ink absorption and diffusion area was introduced. When the S of pretreated cloth is larger than untreated cloth, it is impossible to improve the sharpness of inkjet printing. And the S of pretreated cloth smaller than untreated cloth is a sufficient condition to improve the sharpness of inkjet printing. Table 3 shows that the clarity of drop is intrinsically related to the sharpness of the inkjet printing. this can be observed clearly as the "long/short axis shaft" value can reflect the latitude and longitude inkjet printing to the size of anisotropy, and also conforms to the observer the definition estimation results of the visual design style, thus establishing that the drops of clarity rating method is feasible. This provides a new method for quantitative evaluation of inkjet printing resolution. 28.75-43.97% (MgCl2), respectively. When the salt concentration continues to increase, the line width in the warp direction improved more distinctly than those in the weft direction using monovalent salts. However the line width in the weft direction improved more distinctly than those in the warp direction using bivalent salts. When the salt concentration is high (0.4-0.5 mol/L), the line width in the warp and weft directions improved a small amount. It could be that when PET fibers were treated using the saline XG solution, the salt leant the fabric surface a certain positive charge, which slowed down the seepage of ink drops caused by electrostatic repulsion among xanthan gum, fabric and dye, and improved the fiber surface's adhesion to the ink. The salt ions reduce the surface tension of the fabric, which makes it difficult for the ink droplets to spread on the fiber surface, and the area of the formed ink droplets is significantly less than that of the untreated fabric [20,32]. In the process of inkjet printing, the ink droplets are ejected from the nozzle, and the area formed by the ink droplets on the fabric lessens due to the effect of salt, which is conducive to the infiltration of the ink droplets into the fiber, and slowing down the infiltration of the ink droplets along the warp and weft directions, which results in decreased sharpness of the printing pattern [8,25,33].

New Evaluation Method of Outline Sharpness for Inkjet Printing
In general, outline sharpness and the surface appearance of inkjet printing fabrics are very important, however it is difficult to quantify the outline sharpness with data. There has not been any studies about the outline sharpness, besides the line width of actual inkjet printing. Table 2 shows the results of the ink drop experiment and line width of actual inkjet printing. As shown in Table 2, there is a significant difference in the adsorption and diffusion of ink drops in the warp and weft directions when the ink drops are directly dropped on the surface of the fabric. We clarify the definition of inkjet printing for five grades.

Ink Drop Experiment Line Width of Actual Printing La (cm) Lb (cm) T S (cm 2 ) Warp (μm) Weft (μm) Observe
Grade 1  monovalent salt both in the warp and weft directions. When the salt concentration is low (0.01-0.1 mol/L), the line width in warp direction improved 8.89-9.83% (CaCl2), 4.81-11.12% (MgCl2), the line width in the weft direction improved 28.17-48.78% (CaCl2), 28.75-43.97% (MgCl2), respectively. When the salt concentration continues to increase, the line width in the warp direction improved more distinctly than those in the weft direction using monovalent salts. However the line width in the weft direction improved more distinctly than those in the warp direction using bivalent salts. When the salt concentration is high (0.4-0.5 mol/L), the line width in the warp and weft directions improved a small amount. It could be that when PET fibers were treated using the saline XG solution, the salt leant the fabric surface a certain positive charge, which slowed down the seepage of ink drops caused by electrostatic repulsion among xanthan gum, fabric and dye, and improved the fiber surface's adhesion to the ink. The salt ions reduce the surface tension of the fabric, which makes it difficult for the ink droplets to spread on the fiber surface, and the area of the formed ink droplets is significantly less than that of the untreated fabric [20,32]. In the process of inkjet printing, the ink droplets are ejected from the nozzle, and the area formed by the ink droplets on the fabric lessens due to the effect of salt, which is conducive to the infiltration of the ink droplets into the fiber, and slowing down the infiltration of the ink droplets along the warp and weft directions, which results in decreased sharpness of the printing pattern [8,25,33].

New Evaluation Method of Outline Sharpness for Inkjet Printing
In general, outline sharpness and the surface appearance of inkjet printing fabrics are very important, however it is difficult to quantify the outline sharpness with data. There has not been any studies about the outline sharpness, besides the line width of actual inkjet printing. Table 2 shows the results of the ink drop experiment and line width of actual inkjet printing. As shown in Table 2, there is a significant difference in the adsorption and diffusion of ink drops in the warp and weft directions when the ink drops are directly dropped on the surface of the fabric. We clarify the definition of inkjet printing for five grades. and organizational structure of fibers [34]; the ink was elliptical and the T value was low. The salt, especially the bivalent salt, can significantly reduce the length of the ink blots in the warp and weft directions of the fabric. The ink area decreased, the ink shape changed to a circular shape, and the T value tended to 1.0. When the bivalent salt concentration is 0.1-0.5 mol/L, the warp and weft of fabric are isotropic, the lengths of warp and weft ink are equal, and the T value is 1.0. Therefore, the "short axis/long axis" value of ink droplets forming ink blots is introduced as an index to characterize the definition of inkjet printing ink droplets, which can quantify the influence of pretreatment on the definition of inkjet printing. By considering the difference of ink absorption and diffusion between pretreated and untreated fabric surface properties, the index of ink absorption and diffusion area was introduced. When the S of pretreated cloth is larger than untreated cloth, it is impossible to improve the sharpness of inkjet printing. And the S of pretreated cloth smaller than untreated cloth is a sufficient condition to improve the sharpness of inkjet printing. Table 3 shows that the clarity of drop is intrinsically related to the sharpness of the inkjet printing. this can be observed clearly as the "long/short axis shaft" value can reflect the latitude and longitude inkjet printing to the size of anisotropy, and also conforms to the observer the definition estimation results of the visual design style, thus establishing that the drops of clarity rating method is feasible. This provides a new method for quantitative evaluation of inkjet printing resolution. and organizational structure of fibers [34]; the ink was elliptical and the T value was low. The salt, especially the bivalent salt, can significantly reduce the length of the ink blots in the warp and weft directions of the fabric. The ink area decreased, the ink shape changed to a circular shape, and the T value tended to 1.0. When the bivalent salt concentration is 0.1-0.5 mol/L, the warp and weft of fabric are isotropic, the lengths of warp and weft ink are equal, and the T value is 1.0. Therefore, the "short axis/long axis" value of ink droplets forming ink blots is introduced as an index to characterize the definition of inkjet printing ink droplets, which can quantify the influence of pretreatment on the definition of inkjet printing. By considering the difference of ink absorption and diffusion between pretreated and untreated fabric surface properties, the index of ink absorption and diffusion area was introduced. When the S of pretreated cloth is larger than untreated cloth, it is impossible to improve the sharpness of inkjet printing. And the S of pretreated cloth smaller than untreated cloth is a sufficient condition to improve the sharpness of inkjet printing. Table 3 shows that the clarity of drop is intrinsically related to the sharpness of the inkjet printing. this can be observed clearly as the "long/short axis shaft" value can reflect the latitude and longitude inkjet printing to the size of anisotropy, and also conforms to the observer the definition estimation results of the visual design style, thus establishing that the drops of clarity rating method is feasible. This provides a new method for quantitative evaluation of inkjet printing resolution. especially the bivalent salt, can significantly reduce the length of the ink blots in the warp and weft directions of the fabric. The ink area decreased, the ink shape changed to a circular shape, and the T value tended to 1.0. When the bivalent salt concentration is 0.1-0.5 mol/L, the warp and weft of fabric are isotropic, the lengths of warp and weft ink are equal, and the T value is 1.0. Therefore, the "short axis/long axis" value of ink droplets forming ink blots is introduced as an index to characterize the definition of inkjet printing ink droplets, which can quantify the influence of pretreatment on the definition of inkjet printing. By considering the difference of ink absorption and diffusion between pretreated and untreated fabric surface properties, the index of ink absorption and diffusion area was introduced. When the S of pretreated cloth is larger than untreated cloth, it is impossible to improve the sharpness of inkjet printing. And the S of pretreated cloth smaller than untreated cloth is a sufficient condition to improve the sharpness of inkjet printing. Table 3 shows that the clarity of drop is intrinsically related to the sharpness of the inkjet printing. this can be observed clearly as the "long/short axis shaft" value can reflect the latitude and longitude inkjet printing to the size of anisotropy, and also conforms to the observer the definition estimation results of the visual design style, thus establishing that the drops of clarity rating method is feasible. This provides a new method for quantitative evaluation of inkjet printing resolution. especially the bivalent salt, can significantly reduce the length of the ink blots in the warp and weft directions of the fabric. The ink area decreased, the ink shape changed to a circular shape, and the T value tended to 1.0. When the bivalent salt concentration is 0.1-0.5 mol/L, the warp and weft of fabric are isotropic, the lengths of warp and weft ink are equal, and the T value is 1.0. Therefore, the "short axis/long axis" value of ink droplets forming ink blots is introduced as an index to characterize the definition of inkjet printing ink droplets, which can quantify the influence of pretreatment on the definition of inkjet printing. By considering the difference of ink absorption and diffusion between pretreated and untreated fabric surface properties, the index of ink absorption and diffusion area was introduced. When the S of pretreated cloth is larger than untreated cloth, it is impossible to improve the sharpness of inkjet printing. And the S of pretreated cloth smaller than untreated cloth is a sufficient condition to improve the sharpness of inkjet printing. Table 3 shows that the clarity of drop is intrinsically related to the sharpness of the inkjet printing. this can be observed clearly as the "long/short axis shaft" value can reflect the latitude and longitude inkjet printing to the size of anisotropy, and also conforms to the observer the definition estimation results of the visual design style, thus establishing that the drops of clarity rating method is feasible. This provides a new method for quantitative evaluation of inkjet printing resolution.

Conclusions
The pre-treatment of polyester fabric with xanthan gum and salt can improve the color depth and printing clarity of inkjet printing, and the divalent salt can obtain higher K/S values and printing clarity. The optimal pretreatment condition was 0.3% xanthan gum paste and 0.1 mol/L calcium chloride. K/S increased by 26.99% compared with those using only 0.3% xanthan gum paste.
Pretreatment on fabric with xanthan gum and salt can significantly affect the fabric surface diffusion and adsorption performance, which affects the fabric and fiber surface of both isotropic and anisotropic surfaces. Using the five level system, the method of ink elliptical coefficient (T) and the ink ellipse area (S) to evaluate the pretreatment of polyester fabric inkjet printing sharpness is feasible. The evaluation method is as follows: Grade 1, Sp ≥ Su, the definition rating was the poorest, Grade 2, Sp < Su, 0 < T ≤ 0.70, poor clarity rating, Grade 3, Sp < Su, 0.70 < T ≤ 0.80, the clarity rating is medium, Grade 4, Sp < Su, 0.80 < T ≤ 0.95, the clarity rating is good, Grade 5, Sp < Su, 0.95 < T ≤ 1.0, the clarity rating is excellent.

Conclusions
The pre-treatment of polyester fabric with xanthan gum and salt can improve the color depth and printing clarity of inkjet printing, and the divalent salt can obtain higher K/S values and printing clarity. The optimal pretreatment condition was 0.3% xanthan gum paste and 0.1 mol/L calcium chloride. K/S increased by 26.99% compared with those using only 0.3% xanthan gum paste.
Pretreatment on fabric with xanthan gum and salt can significantly affect the fabric surface diffusion and adsorption performance, which affects the fabric and fiber surface of both isotropic and anisotropic surfaces. Using the five level system, the method of ink elliptical coefficient (T) and the ink ellipse area (S) to evaluate the pretreatment of polyester fabric inkjet printing sharpness is feasible. The evaluation method is as follows: Grade 1, Sp ≥ Su, the definition rating was the poorest, Grade 2, Sp < Su, 0 < T ≤ 0.70, poor clarity rating, Grade 3, Sp < Su, 0.70 < T ≤ 0.80, the clarity rating is medium, Grade 4, Sp < Su, 0.80 < T ≤ 0.95, the clarity rating is good, Grade 5, Sp < Su, 0.95 < T ≤ 1.0, the clarity rating is excellent.

Conclusions
The pre-treatment of polyester fabric with xanthan gum and salt can improve the color depth and printing clarity of inkjet printing, and the divalent salt can obtain higher K/S values and printing clarity. The optimal pretreatment condition was 0.3% xanthan gum paste and 0.1 mol/L calcium chloride. K/S increased by 26.99% compared with those using only 0.3% xanthan gum paste.
Pretreatment on fabric with xanthan gum and salt can significantly affect the fabric surface diffusion and adsorption performance, which affects the fabric and fiber surface of both isotropic and anisotropic surfaces. Using the five level system, the method of ink elliptical coefficient (T) and the ink ellipse area (S) to evaluate the pretreatment of polyester fabric inkjet printing sharpness is feasible. The evaluation method is as follows: Grade 1, Sp ≥ Su, the definition rating was the poorest, Grade 2, Sp < Su, 0 < T ≤ 0.70, poor clarity rating, Grade 3, Sp < Su, 0.70 < T ≤ 0.80, the clarity rating is medium, Grade 4, Sp < Su, 0.80 < T ≤ 0.95, the clarity rating is good, Grade 5, Sp < Su, 0.95 < T ≤ 1.0, the clarity rating is excellent.

Conclusions
The pre-treatment of polyester fabric with xanthan gum and salt can improve the color depth and printing clarity of inkjet printing, and the divalent salt can obtain higher K/S values and printing clarity. The optimal pretreatment condition was 0.3% xanthan gum paste and 0.1 mol/L calcium chloride. K/S increased by 26.99% compared with those using only 0.3% xanthan gum paste.
Pretreatment on fabric with xanthan gum and salt can significantly affect the fabric surface diffusion and adsorption performance, which affects the fabric and fiber surface of both isotropic and anisotropic surfaces. Using the five level system, the method of ink elliptical coefficient (T) and the ink ellipse area (S) to evaluate the pretreatment of polyester fabric inkjet printing sharpness is feasible. The evaluation method is as follows: Grade 1, Sp ≥ Su, the definition rating was the poorest, Grade 2, Sp < Su, 0 < T ≤ 0.70, poor clarity rating, Grade 3, Sp < Su, 0.70 < T ≤ 0.80, the clarity rating is medium, Grade 4, Sp < Su, 0.80 < T ≤ 0.95, the clarity rating is good, Grade 5, Sp < Su, 0.95 < T ≤ 1.0, the clarity rating is excellent.

Conclusions
The pre-treatment of polyester fabric with xanthan gum and salt can improve the color depth and printing clarity of inkjet printing, and the divalent salt can obtain higher K/S values and printing clarity. The optimal pretreatment condition was 0.3% xanthan gum paste and 0.1 mol/L calcium chloride. K/S increased by 26.99% compared with those using only 0.3% xanthan gum paste.
Pretreatment on fabric with xanthan gum and salt can significantly affect the fabric surface diffusion and adsorption performance, which affects the fabric and fiber surface of both isotropic and anisotropic surfaces. Using the five level system, the method of ink elliptical coefficient (T) and the ink ellipse area (S) to evaluate the pretreatment of polyester fabric inkjet printing sharpness is feasible. The evaluation method is as follows: Grade 1, Sp ≥ Su, the definition rating was the poorest, Grade 2, Sp < Su, 0 < T ≤ 0.70, poor clarity rating, Grade 3, Sp < Su, 0.70 < T ≤ 0.80, the clarity rating is medium, Grade 4, Sp < Su, 0.80 < T ≤ 0.95, the clarity rating is good, Grade 5, Sp < Su, 0.95 < T ≤ 1.0, the clarity rating is excellent.

Conclusions
The pre-treatment of polyester fabric with xanthan gum and salt can improve the color depth and printing clarity of inkjet printing, and the divalent salt can obtain higher K/S values and printing clarity. The optimal pretreatment condition was 0.3% xanthan gum paste and 0.1 mol/L calcium chloride. K/S increased by 26.99% compared with those using only 0.3% xanthan gum paste.
Pretreatment on fabric with xanthan gum and salt can significantly affect the fabric surface diffusion and adsorption performance, which affects the fabric and fiber surface of both isotropic and anisotropic surfaces. Using the five level system, the method of ink elliptical coefficient (T) and the ink ellipse area (S) to evaluate the pretreatment of polyester fabric inkjet printing sharpness is feasible. The evaluation method is as follows: Grade 1, Sp ≥ Su, the definition rating was the poorest, Grade 2, Sp < Su, 0 < T ≤ 0.70, poor clarity rating, Grade 3, Sp < Su, 0.70 < T ≤ 0.80, the clarity rating is medium, Grade 4, Sp < Su, 0.80 < T ≤ 0.95, the clarity rating is good, Grade 5, Sp < Su, 0.95 < T ≤ 1.0, the clarity rating is excellent. Pattern I, 30 mm × 30 mm, 1.5 pound, 720 dpi × 720 dpi. Pattern II, 30 mm × 15 mm, 720 dpi × 720 dpi.

Conclusions
The pre-treatment of polyester fabric with xanthan gum and salt can improve the color depth and printing clarity of inkjet printing, and the divalent salt can obtain higher K/S values and printing clarity. The optimal pretreatment condition was 0.3% xanthan gum paste and 0.1 mol/L calcium chloride. K/S increased by 26.99% compared with those using only 0.3% xanthan gum paste.
Pretreatment on fabric with xanthan gum and salt can significantly affect the fabric surface diffusion and adsorption performance, which affects the fabric and fiber surface of both isotropic and anisotropic surfaces. Using the five level system, the method of ink elliptical coefficient (T) and the ink ellipse area (S) to evaluate the pretreatment of polyester fabric inkjet printing sharpness is feasible. The evaluation method is as follows: