Abstract:
A fabric structure is constructed having a fabric base sheet, a viscidity layer, a polymeric back layer, and a protective layer. The polymeric back layer is prepared from SBC (styrenic block copolymer) for the advantage of low specific gravity and preventing the drawback of PVC or the like that pollutes the environment when disposed off. The protective layer is prepared from PU series or modified SBC (styrenic block copolymer) series agent. When the fabric structure used to make a bag, the front surface of the fabric base sheet is disposed outside the bag and the surface of the protective layer is disposed inside the bag.

Description:
FIELD OF THE INVENTION 
     The present invention relates generally to products of bags and cases, and more particularly to a fabric structure for making bags and the like and the manufacturing method thereof. 
     BACKGROUND OF THE INVENTION 
     Various fabric materials have been developed for use in making travel bags, sports bags, backpacks, and the like for the advantage of lightweight, comfortable touch, ease of processing, and low cost. In early days, fabric sheet materials were directly used to make bags through cutting and stitching procedures. However, because a single layer of fabric sheet material is not waterproof, it is not acceptable to most consumers. In order to eliminate this problem, a polymeric backing layer is needed. Conventionally, PVC (polyvinyl chloride) is used for the polymeric backing layer. However, when burned, PVC produces dioxin and other toxic gases that are harmful to the human beings and the environment. Due to this pollution problem, PVC is not the best choice for making the polymeric backing layer. Further, due to high specific gravity (about 1.3), PVC is not suitable for making lightweight bags. Other polymeric materials including PE (polyethylene), EVA (ethylene-vinyl-acetate copolymer), or the combination of PE and EVA may be used for making the polymeric backing layer. However, these materials have low flexibility and poor touch. When folded up, a permanent fold line may be left. Due to the mentioned drawbacks, these materials are rarely used for making bags and cases. 
     SUMMARY OF THE INVENTION 
     The primary object of the present invention is to provide a fabric structure for making bags and the like, which uses SBC (styrenic block copolymer) for the polymeric backing layer instead of potential pollutants such as PVC. 
     It is another object of the present invention to provide a fabric structure, which has high flexibility. 
     It is another object of the present invention to provide a fabric structure, which has a low specific gravity suitable for making lightweight bags and the like. 
     It is still another object of the present invention to provide a fabric structure, which is waterproof and, has a nice touch. 
     It is still another object of the present invention to provide a fabric structure, which has its protective layer prepared subject to the desired color. 
     To achieve the above mentioned objects of the present invention, the fabric structure comprises a fabric base sheet, the fabric base sheet having a front surface adapted to be disposed on the outside of the bag to be made and a back surface; a polymeric backing layer containing SBC (styrenic block copolymer), the polymeric backing layer having a front bonding surface bonded to the back surface of the fabric base sheet and a back surface; and a protective layer prepared from a surface treatment agent and coated on the polymeric backing layer, the protective layer having an inner surface bonded to the back surface of the polymeric backing layer and an outer surface adapted to be disposed to the inside of the bag to be made. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a sectional view of a fabric structure constructed according to a preferred embodiment of the present invention. 
     FIG. 2 is a block diagram explaining the fabrication flow of the fabric structure according to the preferred embodiment of the present invention. 
     FIG. 3 is a schematic drawing showing the polymeric backing layer being bonded to the fabric base sheet by means of co-extrusion coating procedure. 
     FIG. 4 is a schematic drawing showing the steps of surface treating and finished product rolling-up according to the preferred embodiment of the present invention. 
     FIGS. 5A and 5B are schematic drawings showing how to apply a viscidity layer on the surface of the fabric base sheet and how the polymeric backing layer is bonded to the fabric base sheet by means of extrusion coating procedure. 
     FIGS. 6A and 6B are schematic drawings showing how to apply a viscous layer on the surface of the fabric base sheet and how the polymeric backing layer is bonded to the fabric base sheet by means of calendering backing procedure. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to FIG. 1, a fabric structure  1  of a preferred embodiment of the present invention is shown comprised of a fabric base sheet  10 , a viscous layer  20 , a polymeric backing layer  30 , and a protective layer  40 . 
     The fabric base sheet  10  is a woven fabric of nylon or polyester, having a front surface  11  and a back surface  12 . 
     The viscous layer  20  is prepared subject to a particular formula containing SBC (styrenic block copolymer), viscosity improver, additive, and processing oil or butanone. The prepared bonding material is evenly applied to the fabric base sheet  10 , forming the desired viscidity layer  20 . The viscous layer  20  has a first surface  21  and a second surface  22 . The first surface  21  of the viscous layer  20  is bonded to the back surface  12  of the fabric base sheet  10 . 
     The polymeric backing layer  30  is prepared from a mixture containing SBC (styrenic block copolymer), processing oil, plastics, and additive. SBC can be obtained from either or a combination of the following four items: 
     (1) SBS (styrene-butadiene-styrene block copolymer); 
     (2) SEBS (styrene-ethylene-butylene-styrene block copolymer); 
     (3) SIS (styrene-isoprene-styrene block copolymer); 
     (4) SEPS (styrene-ethylene-propylene-styrene block copolymer). 
     The polymeric backing layer  30  is coated on the viscous layer  20 , having a front bonding surface  31  and a back surface  32 . The front surface  31  of the polymeric backing layer  30  is bonded to the second surface  22  of the viscous layer  20 . 
     The protective layer  40  is prepared from a PU (urethane polymer) surface treatment agent and coated on the polymeric backing layer  30 , having an inner surface  41  and an outer surface  42 . The inner surface  41  of the protective layer  40  is bonded to the back surface  32  of the polymeric back layer  30 . The PU surface treating agent contains polyurethane resin, DMF (dimethyl formamide), MEK (methyl ethyl ketone), TOL (toluene), silica, and silicone oil. Further, pigment may be added to the surface treatment agent to provide a colored protective layer. 
     The aforesaid statement describes the construction of the fabric structure  1 . When used to make bags or the like, the front surface  11  of the fabric base sheet  10  is exposed to the outside, and the outer surface  42  of the protective layer  40  faces the inside of the finished product. 
     The advantages of the fabric structure  1  are outlined hereinafter. 
     (1) Because the polymeric backing layer  30  contains mainly SBC (styrenic block copolymer), the fabric structure  1  eliminates the problem of producing dioxin as encountered in conventional PVC (polyvinyl chloride) based fabric materials when burned. 
     (2) Because the additive used in the SBC-based polymeric backing layer  30  to change the physical properties of the SBC-based polymeric backing layer  30  does not contain any heavy metals, it does not cause pollution to the environment and, enables the physical properties of the SBC-based polymeric backing layer  30  to be easily adjusted to facilitate the performance of further processing procedure. 
     (3) Because the SBC-based polymeric backing layer  30  provides good flexibility and elasticity, the fabric structure  1  prevents the formation of a fold line, which is commonly seen in conventional plastic back materials (PE, EVA) when folded up). 
     (4) Because the specific gravity of SBC is about 0.9, lower than the specific gravity 1.3 of PVC, it fits the demand of making finished products as light as possible. 
     (5) The SBC-based polymeric backing layer  30  is waterproof, providing the function of fixing and reinforcing the construction of the fabric material. 
     (6) The PU protective layer  40  prevent the SBC-based polymeric backing layer  30  from becoming viscous when hot during delivery, keeping the surface of the fabric structure  1  dry for stitching and comfortable for touching and, preventing the surface of the fabric structure  1  from been covered with scratches. 
     (7) The PU protective layer  40  can be added with pigment during its preparation, so as to provide the desired color without further complicated and expensive dying procedure. No pigment is needed when making the PU protective layer  40  transparent. 
     Referring to FIG. 2, the fabrication of the fabric structure  1  includes the steps of preparing the fabric base sheet preparation, applying polymeric backing layer onto the base sheet, bonding the polymeric backing layer and the base sheet together, applying surface treatment agent to the polymeric backing-layer to from a protective layer, and rolling the finished product up. Various manufacturing methods are outlined hereinafter. 
     Please refer to FIG. 3, as it discloses how a viscous layer and a polymeric backing layer are formed on a fabric base sheet by means of a so-called co-extrusion coating procedure. As shown in FIG. 3, SBC-based polymeric back material  101  is prepared containing SBC (100 PHR), processing oil (0˜120 PHR), plastics (0˜100 PHR), and additive (0˜20 PHR), and viscous material  102  is prepared containing SBC (100 PHR), processing oil (0˜25 PHR), viscosity improver (0˜120 PHR), and additive (0˜20 PHR). The SBC-based polymeric material  101  and the viscous material  102  are separately fed into a lamination machine and heated at different temperatures and treated through respective fusion, cutting, and mixing procedures, and then delivered to a respective T-mold  103  through a respective fluid path. The temperature for the polymeric backing layer material is set at about 80˜200° C., or preferably at 170˜180° C., so as to obtain melt flow index within 5˜18 g/10 min and, to achieve better wetting effect. The temperature for the viscous material is set at about 80˜200° C., or preferably at 180˜200° C. 
     The SBC-based polymeric backing layer material  101  and the viscous material  102  are gathered in the T-mold  103  at about 3 mm˜5 mm from the output port of the T-mold  103 , so that the SBC-based polymeric back material  101  and the viscous material  102  are fused together and squeezed into a SBC-based polymeric backing layer  104 . The thickness of the SBC-based polymeric backing layer  104  is within about 0.05 mm˜0.6 mm, The SBC-based polymeric back layer  104  is then covered on a fabric base sheet  106  being delivered from an anterior roller set (including a preheating roller)  105 , and then delivered with the fabric base sheet  106  through an impression roller set  107  (including a silicon rubber roller  107   a  and an impression roller  107   b ), and then continuously delivered forwards through a posterior cooling roller set  108 . When cooled down, the desired semi-finished fabric material is obtained. The method of using a roller to preheat or cool down the sheet material is to heat the roller, or to deliver freezing water through the roller. Because the application of the heater or freezing water is not within the scope of the present invention, no further detailed description is necessary. 
     Referring to FIG. 4, during the step of surface treating, the semi-finished fabric material thus obtained is inserted in between a sheet-transfer roller  401  and an applicator roller  402 , and then delivered forwards through a baking oven  404  and then rolled up by a rolling-up roller  405 . The applicator roller  402  is partially dipped in a PU (urethane polymer) surface treatment fluid  403 . When passing through the gap in between the sheet-transfer roller  401  and an applicator roller  402 , the SBC-based polymeric backing layer  104  of the semi-finished sheet material is evenly coated with a layer of PU (urethane polymer) surface treatment fluid  403  by the applicator roller  402 . When passed through the baking oven  404 , the layer of PU (urethane polymer) surface treatment fluid  403  is dried. When dried, the solvent which is contained in the PU surface treatment fluid is volatilized, and the solid content forms a protective layer on the finished fabric material (fabric structure), and the rolling-up roller  405  is rotated to roll up the finished fabric material (fabric structure). 
     The aforesaid PU (urethane polymer) surface treatment fluid  403  contains PU resin 5˜15 wt %, DMF (dimethyl formamide) 20˜40 wt %, MEK (methyl ethyl ketone) 20˜40 wt %, TOL (toluene) 20˜40 wt %, silica 0˜5 wt %, and silicone oil 0˜3%. The aforesaid solvent includes DMF, MEK, and TOL. The aforesaid solid content includes PU resin, silica, and silicone oil. Further, pigment may be added to the PU (urethane polymer) surface treatment fluid  403  to change the color of the backing layer. The content of pigment is about 0˜15 wt %. 
     Further, modified SBC surface treatment fluid may be used instead of the aforesaid PU surface treatment fluid  403 . The modified SBC surface treatment fluid includes two types, namely, the silicone-based modified SBC surface treatment fluid and the wax-based SBC surface treatment fluid. The former contains SBC 5˜30 wt %, silicone 0.5˜10 wt %, IPA (isophthalic acid) 1˜7 wt %, TPT (tetraisopropyl titanate) 0.1˜0.5 wt %, and toluene 60˜90 wt %. The later contains SBC 5˜30 wt %, wax and toluene 60˜90%. The wax used herein can be PE wax or Teflon wax, and its content is within about 1˜5 wt %. 
     Of course, pigment may be added to the modified SBC surface treatment fluid to produce the desired color of protective layer. 
     Either of PU (urethane polymer) surface treatment fluid or modified SBC surface treatment fluid can achieve the desired protective layer having scratch-protective smooth features. 
     FIG. 5 shows an alternate form of the fabrication process for making the desired fabric structure. This alternate form employs an extrusion coating process. As shown in FIG. 5A, the fabric base sheet  201  is delivered over at least one applicator roller  202 , which applies a viscous material  203  to one surface of the fabric base sheet  201 . Further, a scraper  202   a  is used with each applicator roller  202 , and adapted to remove excessive amount of viscous material  203  from the corresponding applicator roller  202 . The viscous material  203  contains SBC (100 PHR), viscosity improver (0˜120 PHR), additive (0˜20 PHR), and MEK (100˜500 PHR). When coated with the viscous material  203 , the fabric base sheet  201  is delivered forwards through a baking oven  204 , enabling the solvent in the viscous material to be volatized. When dried, the fabric base sheet  201  coated with the viscous layer is rolled up for further polymeric backing layer bonding. As shown in FIG. 5B, SBC-based polymeric backing material  205  is prepared containing SBC (100 PHR), processing oil (0˜120 PHR), plastics (0˜100 PHR), and additive (0˜20 PHR). The prepared SBC-based polymeric backing material  205  is then supplied to a lamination machine and heated to about 170˜180° C. to achieve a melt flow index of 5˜18 g/10 min. The molten fluid of the prepared SBC-based polymeric backing material  205  is well mixed and propelled to a T-mold  206  and squeezed out of the output port of the T-mold  206 , forming a continuous sheet of SBC-based polymeric backing film  207 . The continuous sheet of SBC-based polymeric backing film  207  is then covered on the viscous layer  203  of the fabric base sheet  201  which has been delivered from an anterior roller set  208 . After pressure bonding, the continuous sheet of SBC-based polymeric backing film  207  and the fabric base sheet  201  are fastened together, forming the a semi-finished product (fabric structure), which is cooled down through a posterior roller set  209 , and then treated through a PU (urethane polymer) surface treatment (same as that shown in FIG.  4 ). 
     FIG. 6 shows another alternate form of the fabrication process for making the desired fabric structure. This alternate form employs a so-called calendering backing procedure. As shown in FIG. 6A, the fabric base sheet  301  is delivered over at least one applicator roller  302 , which applies a viscous material  303  to one surface of the fabric base sheet  301 . Further, a scraper  302   a  is used with each applicator roller  302 , and adapted to remove excessive amount of viscous material  303  from the corresponding applicator roller  302 . The viscous material  303  contains SBC (100 PHR), viscosity improver (0˜120 PHR), additive (0˜20 PHR), and MEK (100˜500 PHR). When coated with the viscous material  303 , the fabric base sheet  301  is delivered forwards through a baking oven  304 , enabling the solvent in the viscous material to be volatized. When dried, the fabric base sheet  301  coated with viscous layer is rolled up for further polymeric backing layer bonding. As shown in FIG. 6B, SBC-based polymeric backing material  305  is prepared containing SBC (100 PHR) processing oil (0˜120 PHR), plastics (0˜100 PHR), and additive (0˜20 PHR). The prepared SBC-based polymeric backing material  305  is heated to achieve a melt flow index of at least 3 g/10 min. The molten fluid of the prepared SBC-based polymeric backing material  305  is processed into a continuous sheet of SBC-based polymeric backing film  307  through a roller set  306 , which is controlled at the temperature of about 90˜160° C. The continuous sheet of SBC-based polymeric backing film  307  is then delivered through a pressure-bonding roller set  308  and bonded to the viscous layer of the fabric base sheet  301 . After pressure bonding, the continuous sheet of SBC-based polymeric backing film  307  and the fabric base sheet  301  are fastened together, forming the a semi-finished product (fabric structure), which is cooled down through a cooling roller set  309 , and then treated through a PU (urethane polymer) surface treatment (same as that shown in FIG.  4 ).