Patent Publication Number: US-4734313-A

Title: Coated plastic sheet made of pp non-woven and its manufacturing method

Description:
The present invention relates to plastic sheets made with a base layer made of a non-woven fabric of polyproplene. 
     DESCRIPTION OF THE PRIOR ART 
     At present plain woven fabric, knitted fabric or non-woven made of fibers is used as base layer for plastic sheets. One or more plastic layers is bonded to the base layer to form a plastic sheet. The methods of manufacture include: 
     (1) A base fabric is pasted, dried and then bonded to one or more layers of foamed or unfoamed plastic films, foamed and finally embossed. Polyvinyl chloride is used frequently. 
     (2) A paper stencil is coated with a layer of non-foaming material, a layer of foamable material, a layer of paste, base fabric is adhered to it before foaming. The pattern of the paper stencil may be the pattern of its surface, or it may be embossed separately. The material used is polyvinyl chloride or polyurethane. 
     (3) A base fabric is coated with a layer of polyurethane resin. This method gives a wet type polyurethane sheet after thermosetting and rinsing. 
     The products made by the above methods have the following defects: 
     (1) The base fabric is discolored and weakened during foaming at high temperature, and consequently, the flexibility of the finished products is not satisfactory. The use of plain woven fabric results in yarn breaking during processing and cutting because it is composed of warp and weft yarns. 
     (2) The paper stencil is indispensable for the method with coating by means of paper stencil but the rate of production is low and this step involves an additional cost. 
     (3) There is a pollution problem due to the solvent required in making wet type PU sheet, the rate of production is low and the cost is high. 
     (4) The base fabric made of fibers or artificial fibers is heavy and consequently the finished product is heavy. 
     THE PRESENT INVENTION 
     A polypropylene (PP) spray spinning type non-woven base fabric is used. A polyvinyl chloride (PVC) film is applied to cover first the entire surface, and then a coating is applied as the uppermost layer to form a plastic sheet made of non-woven PP. 
    
    
     DESCRIPTION OF THE DRAWINGS 
     By reference to the drawings, 
     FIG. 1 illustrates a method of film spraying according to the present invention; Numeral 1 is a PP Non-Woven Fabric; Numeral 2 is a PVC Film Layer; Numeral 3 is a T-Mold; Numeral 4 is an Adhesion Roll; Numeral 5 is a Cooling Roll; Numeral 6 is the Semi-finished product. 
     FIG. 2 illustrates a method of coating according to the present invention; Numeral 7 is a Feeder Wheel; Numeral 8 is the Embossed Coating Roll; Numeral 9 is the backing wheel; Numeral 10 is a Drying Oven; Numeral 11 is a Cooling Wheel-A: Wheel Type coating; B: Embossed Coating; C: Rotary Screen Coating. 
     FIG. 3 illustrates the structure of the finished product according to the present invention: (1) PP Non-Woven; (2) PVC Film Layer; (3) Coating Plastisol Layer. 
    
    
     FIG. 1 illustrates the step of spraying the film; FIG. 2 illustrates the coating step and FIG. 3 illustrates the product of the present invention. The PP non-woven 1 is used as a base fabric of the plastic sheet. The method of manufacture consists of heating fiber-grade PP resin to melt and then spray them to form a web, and finally, thermoset to form PP non-woven fabric. It has the merit of being PP-light, water repellent and economical. Further, since continuously sprayed fiber-yarn will break when cut and since pores exist on the sprayed fibers, a film extruded from a PVC resin of a particular formula by means of T-Mold must be spread on it as a filler 2 or coating layer as shown in FIG. 3. The uppermost layer is a coating on which a pattern may be embossed or printed to form a plastic sheet as shown in FIG. 3. 
     The formulations used in the present invention are: 
     
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Granules for                                                              
PVC Film Spraying                                                         
PVC resin       50-100 parts                                              
VC-VAC (vinyl chloride-                                                   
                 0-50 parts per 100 parts of resin                        
vinyl acetate) copolymer                                                  
Plasticizer     50-100 parts per 100 parts of resin                       
Stabilizer       3-9 parts per 100 parts of resin                         
Lubricant        0-1 parts per 100 parts of resin                         
Dye              0-6 parts per 100 parts of resin                         
Plastisol uppermost layer                                                 
PVC resin       60-100 parts                                              
Thermoplastic Rubber                                                      
                 0-40 parts per 100 parts of resin                        
Plasticizer      0-100 parts per 100 parts of resin                       
Stabilizer       1-5 parts per 100 parts of resin                         
Filler           0-50 parts per 100 parts of resin                        
Dye              5-20 parts per 100 parts of resin                        
______________________________________                                    
 
    
     The method of manufacture according to the present invention is described below: 
     Method in each step: 
     1. PP Non-Woven 
     PP, fiber-grade--(a) Melting; (b) Extrusion; (c) Spray Spinning; (d) Thermal Setting--the product is PP Non-woven fabric 
     2. PVC granules for PVC film spreading 
     The PVC resin and other components are extruded, the product is granulated and granules for film spreading are obtained. 
     3. Plastisol 
     The components of the formulation are mixed to form a paste. Then they are placed in a container by means of the Feeder Roll. Coating is carried out with the coating roller partially or totally. The product is dried and gelled to give PVC Coating. 
     The process of manufacture is described in FIGS. 1 and 2: 
     Granules for PVC Film for Spreading-Film Extrusion by T-Mold PP Spun Non-Woven--PVC Film for Spreading, Overall PVC Plasticizer Preparation--PVC Plastisol Coating, partially or totally--Heating/Gelling--Cooling--Surface treatment by Embossing--Finished product. 
     The PP Non-Woven is made of PP resin, fiber-grade. The PP resin is heated and melted, sprayed by a spinning head to form continuous filaments which are evenly sprayed on a web to form a sheet, bonded to form a non-woven sheet with thermal embossing roll. The density and thickness of the non-woven sheet is controlled by spraying speed to meet different quality requirements, and different dyes can be added to form PP non-woven of different colors. 
     The granules for film spreading are prepared with a particular formula to suit extrusion with melting and T-mold. The components, after mixing in the proper proportions, are granulated by PVC granulator to suit film spreading. 
     The Non-woven PP sheet is placed on the feeder of a film spreading machine and extended to a T-mold. The granules for film spreading are heated to 190°-210° C., extruded by the T-mold to form a film covering the PP non-woven. 
     The plastisol prepared in compliance with the particular formulation is then coated on the PP non-woven sheet. The plastisol is adhered to a rubber feeder roll and then transferred to an embossed coating roll which coats the plastisol on the film covered non-woven sheet. The non-woven sheet after coating is sent into a drying oven with a temperature of 100°-150° C. for drying and gelling. After cooling and setting, it is finished or embossed to form a coated plastic sheet made of non-woven PP sheet (see FIG. 1 and 2). 
     A wide choice of non-woven PP with thickness from 0.1 mm to 0.6 mm and density from 14 g/m 2  to 100 g/m 2  can be used to meet the thickness requirement of the finished product. The proportion of VC-VAC copolymer in the granules for the film to be spread may be adjusted within a range of 0-50 parts per 100 parts of resin. The thickness of the film to be spread is from 0.02 mm to 0.15 mm to meet different requirement. 
     The preferred embodiments according to the present invention is described below: 
     (1) Non-woven PP sheet of 75 g/m 2  is used. It is entirely sprayed to apply a film of 0.1 mm by extrusion of the granules of PVC film at 190° C. by means of a T-mold to form a base sheet with a thickness of 0.45 mm. The base sheet is then coated with a PVC plastisol to a thickness of 0.15 mm by means of the embossed coating roller. After drying and gelling in a drying oven at a temperature of 100° C.-150° C., cooling and setting, the surface is subjected to a finishing treatment with a surface treating agent. Finally, it is subjected to inspection, cutting and packing for form the finished product with a thickness of 0.6 mm at 50 yards per roll for further processing by handbag manufacturers. 
     (2) Non-woven PP sheet of 50 g/m 2  is used. It is entirely sprayed to apply a film of 0.15 mm by extrusion of granules for PVC film spreading at 200° C. by means of a T-mold in order to form a base sheet with a thickness of 0.35 mm. The base sheet is then coated with a PVC plastisol to a thickness of 0.20 mm by means of a wheel type coating machine. After drying and gelling in a drying oven at a temperature of 100° C.-150° C., cooling and setting, a surface finishing treatment is applied by means of embossing and printing. Finally, it is inspected, cut and packed to rolls of 60 yards each and has a thickness of 0.5 mm-0.55 mm for further processing by handbag/luggage manufacturers. 
     (3) PP non-woven sheet of 75 g/m 2  is used. Water-based or oil-based ink or paste is applied to the surface completely, or it is dyed to fill its pores in order to form a base sheet 0.4 mm thick. A rotary screen coating roller is then used to apply PVC plastisol in a certain pattern to form embossed pattern. After drying and gelling in a drying oven at a temperature of 100° C.-150° C., cooling and setting, it is inspected, cut and packed in rolls of 50 yards each and has a thickness of 0.5 mm-0.6 mm for further processing by handbag manufacturers.