Title of Invention

A PROCESS FOR RECYCLING OF PET BOTTLE WASTES INTO FIBRES

Abstract

ABSTRACT The invention relates to the establishment of a complete process technology for spinning PET(Poly Ethylene Terephthalate ) bottles into staple fibres either in its pure form or in blends with polyester fibre wastes. According to this process there is categorisation of PET bottle wastes, collection of PET waste bottles, separation of other plastics from PET, cutting of PET bottles and finally cleaning of soiled PET bottles Then the PET grinded flakes are converted into chips by densification Finally there is melt spinning of densified bottle wastes into staple fibres involving drying, crystallisation, extrusion, winding, drawing, finish application, crimping and cutting.

Full Text

Form - 2 THE PATENTS ACT, 1970 (39001970) COMPLETE SPECIFICATION {see section 10) rule13 TITLE: A process for recycling of PET bottle wastes into fibres APPLICANT THE SYNTHETIC AND ARTSILK MILLS' RESEARCH ASSOCIATION sasmira Sasmira Marg, Worli, Mumbai-400025, India. The following specification particularly describes the nature of this invention and the manner in which it is to be performed: Background for the invention Polyester has been used as a fibre in textile and related applications since 1950s. 7-10% waste is generated during manufacturing of fibres. The wastes have been traditionally recycled to produce coarse staple fibres. These fibres have limited applications as they are of poor quality in terms of properties and have high variability. Presently the recycling industry in India is also plagued by limited availability of raw material since the major fibre producers are going in for in-house chemical recycling. However, there is a new kind of polyester waste, which may be looked up as an alternative raw material for recycling. This material the omnipresent PET bottles which are being increasingly used in packaging a variety of products like soft drinks, mineral water, cosmetics, pharmaceuticals etc. In India, production of PET bottle grade resin is presently 70 Kilo Tonnes per annum and the quantum is expected to double in another three years period. Apart from the obvious benefit of getting continuous supply of raw material to recyclers, recycling PET bottles is also necessary to prevent serious ecological and community health problems, which may spurt if these non-biodegradable wastes are left in the garbage. However the technology of recycling PET bottles differs in many ways from that of recycling fibre grade polyesters. These differences may be attributed to certain differences in molecular weight, presence of co monomer in PET bottles and presence of other contaminants. However blending of PET bottle wastes with fibre wastes is possible as both are forms of same polymer, the polyester. The technology for recycling PET bottle wastes, if made available to the Indian industry, will not only provide a much cheaper source for producing staple fibres but improve processing of fibre grade wastes also. Besides, such recycling will minimise ecological hazards posed by these non-degradable bottles. The steps involved in total technology of processing PET bottles into staple fibres and subsequently into nonwovens can be identified as under: I PET bottle collection II Preparatory processes • Sorting • Grinding • Washing • Densification III Fibre spinning (or Moulding etc.) involving • Drying • Spinning • Post spinning operations Incorporating the above system it would be possible to improve the processing of fibre grade polyester wastes as well as produce superior fibres out of pure PET bottle wastes. z Summary of the invention This invention relates to the establishment of a complete process technology for spinning PET (Poly Ethylene Terephthalate) bottles into staple fibres either in its pure form or in blends with polyester fibre wastes. The invention relates to and covers • A methodology for categorisation of PET bottle wastes • A methodology for collection of PET bottle wastes from various sources • Methods for sorting other materials from the PET bottle waste stock • Method for shredding the bottles into flakes • Method of washing different kinds of waste • Methods for preparing the grinded flakes for spinning by Densification • Process for blending the densified flakes with fibre wastes • Optimised process conditions for spinning the densified flakes into staple fibres and post spinning operations. The-objectives of this invention and related specifications is elaborated as below First qbj«etiVe S Y-p■ Methodology of categorisation of PET bottle wastes The objective of this invention is to standardise methodology for categorising the PET bottles prior to their collection. The categorisation is required to ensure production of superior quality fibres and minimise efforts in sorting, washing etc. The categorisation is based on the broad outlines provided as below: • Wastes generated at bottle manufacturer, preform manufacturer, which may be identified as superior (Category A) source requiring very little sorting, washing etc. • Post consumer wastes like mineral water bottles, soft drinks bottles etc, which are easy to recover in bulk, from frequent users like • Railways, commercial flights • Hotels, restaurants • Hospitals • Household Presumably, these PET bottles are used once only and require little cleaning. Nevertheless, these bottles may require sorting and washing and hence may be classified as Category B. 3 • The wastes mentioned below may require more efforts in sorting and washing and can be put in Category C. viz. • Post consumer but heavily soiled wastes • Household wastes • Bottles found in the dumps • Coloured bottles collected by any method as above are to be categorised as Category D and have to be processed separately. SECOND OBJECTIVE Step' Methodology of collection of PET waste bottles Scheme I relates to Collection of bottles from bottle manufacturers and frequent user of bottles like hotels etc (Category A & B respectively). The task involves a mobile van fitted with a Grinder (described subsequently) of 30-100 kg/hr. capacities. The bottles are collected at the source and the labels, caps are manually removed and put directly into the grinder from where flakes drop into a container. The stock is conveyed directly to recycling plants for further processing. Scheme II relates to collecting PET bottles at public places like stations, bus stands, parks, tourist spots and even street corners. The collection starts with the user putting the bottles into the bin labelled PET Bottles only, after removing the caps and labels, which can be put into the other bin. From the bin the bottles may be collected and distributed in a manner similar to scheme I. However chances of other contaminants is higher in this case and physical sorting may be required at the recycling plant. Scheme III relates to collection of soiled bottles. As stated already category C wastes should be avoided as they may require large-scale washing and sorting efforts. The collection of such wastes begins with a van similar to scheme I above but equipped with a manually operated crusher only. The crushed bottles are transported to centres, where facilities exist for efficient sorting, grinding and washing. The cleaned stocks thus created can be shipped to recycling plants. Scheme IV relates to collection of coloured bottles by one of the schemes as above. THIRD OBJECTIVE Step To establish a method for separation of other plastics from PET in the collected stock as above. For some of the bottles collected as above it is necessary to remove all other plastics before further processing. The objective relates to sorting of bottles before grinding or 4 after grinding. This invention covers the manual separation of objects such as caps, cap liners, labels and bottle seals at the time of collection. This invention covers the separation of PET bottles from Polypropylene caps; cap liners by float tanks or sinkers (floatation method). The working of float tanks would be clearer from the following description. To handle bulk quantity, tanks of dimensions 100 ft x 100 ft x 100ft can be used; more precisely multiple tanks of 25 ft x 25 ft x 25ft may be opted. More exactly tanks of 12x6x4 ft may be suitable. The tank body may be of concrete, wood or any metal or may be made of steel. The process involves filling up the said tank with water to 3/4ths of the height. The PET material in bottle, grinded flake or in any other form is put into the tank. The tank is stirred well and allowed to settle for duration of about 5-25 minutes. The material floating on the water can be separated manually or by suitable implements. The invention also covers separation of cellulosic materials like labels etc. by centrifuge-based machines like air cyclones, hydrocyclones and similar devices. FOURTH OBJECTIVE Step to establish a method for cutting PET bottles hitherto referred as Grinding. Grinding machineries are used to break the PET bottles into flakes of irregular shapes of dimensions lcm-2cm. The grinder has a feeding hopper through which the bottles are fed. The bottles come into contact with fast moving metallic blades and cut into pieces and fall into a container located at the bottom. A schematic diagram of a grinder is shown in Figure 1. FIFTH OBJECTIVE Step To establish a methodology for cleaning of soiled PET bottles Washing is required to remove all dust contaminants and adhesives etc, from the bottle. This is required to facilitate production of better quality fibres. It is also to be noted that as discussed earlier different categories of feedstock may require different washing routines. Post consumer PET bottle flakes can be subjected to different washing routines. The PET bottle flake stocks have to be observed visually for extent of soiling, Oil and grease marks. Based on the quality of the stock the following sequence of operations may be chosen. 5" Sequence of washing operations: A. Washing with hot water or soap water solutions from room temperature to 100 °C for 15 mins to 1 hour at material to liquor ratio of 1:2 to 1: 20. B. Washing as per A followed by washing in glacial acetic acid (50-98% assay) and then with detergent (like Lissapol D or any other suitable detergent) and anhydrous Soda ash(MOgpl). C. Washing as per A followed by soaking in sulphuric acid (30-90% v/v) and then with detergent & Soda ash. D. Treated as per B followed by treatment with optical whitener (ultrawhite RN- 0.1%- 1% owm) at pH of 4-8 at temperatures of 60-120 °C for 15-120 minutes. SIXTH OBJECTIVE Step Conversion of PET grinded flakes into chips (popcorn) by the process hitherto referred as Densification The flakes obtained by grinding and washing is to be converted into a feedstock suitable for feeding into extruder. Densification is the step where grinded flakes are converted into spinnable popcorn like flakes. The machinery used for densification is shown in Figure 2 below. A set of stationary blades is situated at the bottom of the densifier chamber. Another set of blades is mounted on a central rotating shaft. The material is subjected to high friction between the blades and gets heated up to temperatures in excess of polyester's softening temperature. At this point water is added from the top when PET quenches up into hard popcorns. The material is unloaded by opening the door situated near the bottom. SEVENTH OJE€TTVE: ' Proposed technology for melt spinning of the densified PET bottle flakes into useful textile fibres. A schematic diagram of the spinning set up is depicted in Figure 3. The densified flakes are starting materials for this process. The materials may be mixed in specified proportions with the other grades of polyester like Fibre grade (FG) wastes. Alternatively the blending may be carried out at densification stage also. Drying of these materials is done at temperatures between 100- 250 °C for one to four hours, more exactly between 250- 300 °C for one to two hours in rotary screw type dryer or any suitable device. The temperature used in drier is on the higher side to ensure that crystallization of the material is achieved. Further the drier should have facility for material circulation inside to facilitate uniform heat transfer. This may be achieved by rotor blades placed inside or some other means. The material after drying is Unloaded to the screw conveyor and conveyed to the hopper of the screw extruder. The screw extruder may have the following specification. Extruder type L/D ratio Screw rpm Zones rftrougftput No. of spinning heads Screen changer No of holes in Spinneret Spinneret diameter Extrusion temperature Quenching Quenching length Winding speed Screw extruder of dia 50 to 100 mm more Precisely of diameter 70 to 80 mm 15 to 50 and more precisely between 25-35 in the range 35-70 more precisely 45-55 4-8 zones more precisely 6 30 -200 more precisely 5O-100 Kgs. 1-20 more closely 5-12 double filter or any suitable mesh of size 10- 80 or more precisely 30-50 mesh/inch 300-1200 more precisely 500-700 0.2 to 2 mm more accurately 0.6-1.2mm Adjusted as required, range 200-3 50°C more precisely 250-300 °C. waterjet/air or any other means of cooling 1-20 mts more precisely 10mts-12mts. 300-2000 m/min more closely 600m/min- lOOOm/min The filaments collected on the bobbin are stored separately for further processing or automatically conveyed to the fibre drawing line. The sequence of drawing, finish application, crimping and cutting in a continuous drawing line are shown in Figure 4. The tows of individual packages are passed over the creels made by suitable arrangements and combined into a bigger tow. The drawing of these tows can be a single stage or multi stage drawing with conditions as given below. POST SPINNING LINE Creel capacity Drawing type Drawing Temperature Draw rollers Draw ratio Finish bath temperature Crimper type Drying temperature Cutter 100-1000 more precisely 400-600 Single stage or multi stage 35 -120 °C or more closely 60-95 °C 3 - 11 or more closely 5-9 in each set 2.5 to 6.5 or more closely 3.5-5.5 30-95 °C or more closely 75-90 °C Stuffer box or any suitable type 45-250 °C or more closely 150-195 °C Lumen or any suitable cutter The drawn tow may then be passed through a finish bath containing silicone finish of 5-100 jpl concentration along with additives like anti static agents, etc. Then it passes 7 through a set of rollers for expressing excess finish out and washed before running into stuffer box where crimping may be imparted. The tow then passes through a set of seven annealing chambers and three cooling chambers. Subsequently the tow may be conveyed to a cutter and drops onto a vertical conveyor, which lifts it to a baling machine and formed into bales. The fibres produced as above can be converted into useful end products by either spinning them into yarns followed by weaving, knitting or braiding or by converting them into nonwovens. The products thus produced may undergo specific finishing steps to obtain a number of end products such as blankets, filling layer, carpet, filter fabrics, automotive moulded carpets, geotextiles, shoe linings etc. This is an embodiment of invention. Several modifications are possible, which will be considered within the ambit and spirit of this invention. Example : 400 kg of PET bottle wastes were collected, grinded using the grinder the caps, cap liners and labels were removed using float tanks. Washing of flakes was carried out using soap solution at 100 °C for 15 minutes in tanks. The flakes were dried overnight and put into densifier and water added to the material inside densifier after running for 20 minutes. Densified flakes were collected and dried at 195 °C for 2 hrs. the densified flakes had intrinsic viscosity of 0.757 and crystallinity of 45.6%. Extrusion of densified flakes was carried out with a 74 mm screw extruder at 75 kg/h output through a 600 hole spinneret. The as spun fibre tow was collected on bobbins at winding speeds of 680 m/min. 100 such bobbins each weighing 4 kg was creeled onto the fibre line for post spinning operations. The tows were passed through two sets of draw rollers and drawn to draw ratio of 4.5 at temperatures of 85 °C, applied with finish and crimped on stuffer box. The crimped tow was then passed through annealing chambers at 180 °C, cooled, cut and formed into bales. The staple fibres produced have a tenacity of 5.2 gm/den (CV % of 10.1) and elongation at break of 154.2 %. We claim 1. A process for recycling of PET bottle wastes to obtain staple fibres of superior properties, the process steps are} grading the PET bottle wastes as per their level of contaminants; separating other materials like caps, cap liners, labels etc. from the bottle wastes; grinding bottle wastes using suitable grinder into flakes of irregular size of approximate lto 2 cms; washing the said bottle wastes by: washing with hot water or soap water solutions from room temperature to 100 °C for 15 mins to 1 hour at material to liquor ratio of 1:2 to 1: 20. (process A); washing as per process A followed by washing in glacial acetic acid (50-98% assay) and then with detergent (like Lissapol D or any other suitable detergent) and anhydrous Soda ash (l-10gpl). (processB); washing as per process A followed by soaking in sulphuric acid (30-90% v/v) and then with detergent & Soda ash; treated as per process B followed by treatment with optical whitener (ultrawhite RN-0.1%-1% owm) at pH of 4-8 at temperatures of 60-120 °C for 15-120 minutes ; densification of washed flakes, conversion of said grinded bottle waste flakes into dense popcorn like densified flakes using a non-melting process on a machinery, which subjects it to friction between a set of moving and fixed blades ; blending of bottle wastes with polyester fibre wastes in proportions from 5 -100% by weight of bottle wastes; drying of said blended bottle wastes on a suitable dryer and said drying being carried out at temperatures between 150-200 °C and said drying being carried out for 2 to 4 hours; extruding said dried wastes into tows, step comprising screw extruders of diameter 70-80 mm and outputs 50- 100 kgs per hour and said extrusion being carried out at temperatures of 250-300 °C and winding said extruded tows using suitable winders at speeds of 300- 2000 m/min ; 1 drawing wound tows, steps comprising of drawing said tows between two sets of rollers to draw ratios of 3.5 to 5.5 at temperatures of 60-95 °C with finish application carried out at temperatures of 75-90 ° C; crimping, annealing and cutting of said tows into fibres on conventional equipment. 10 2. A process as claimed in claim 1 for separation of caps, liners, labels from the bottles by float tanks. 3. A process as claimed in claim 1 in which densification process step consisting of conversion of grinded bottle waste flakes into dense popcorn like flakes using a non-melting process.

Documents:

109-mum-2002-abstract.doc

109-mum-2002-abstract.pdf

109-mum-2002-claim(31-08-2004).doc

109-mum-2002-claim.doc

109-mum-2002-claims(cancelled).pdf

109-mum-2002-claims.doc

109-mum-2002-correspondence(ipo).pdf

109-mum-2002-correspondence.pdf

109-mum-2002-description(granted).doc

109-mum-2002-description(granted).pdf

109-mum-2002-drawing.pdf

109-mum-2002-form 1.pdf

109-mum-2002-form 19.pdf

109-mum-2002-form 2(31-08-2004).doc

109-mum-2002-form 2(title page).pdf

109-mum-2002-form 2granted).pdf

109-mum-2002-form 3.pdf

109-mum-2002-form-2(garanted).doc

109-mum-2002-pct document.pdf

109mum-2002-cancelled pages(31-8-2004).pdf

109mum-2002-claims(granted)-(31-08-2004).pdf

109mum-2002-correspondence(31-08-2004).pdf

109mum-2002-correspondence(ipo)-(31-08-2004).pdf

109mum-2002-drawing(31-08-2004).pdf

109mum-2002-form 1(7-02-2002).pdf

109mum-2002-form 19(18-6-2003).pdf

109mum-2002-form 2(granted)-(31-08-2004).pdf

109mum-2002-form 3(7-02-2002).pdf

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