METHOD AND EQUIPMENT TO CONVERT RIGID PVC

Abstract: By according to the invention to use a method to recycling of rigid PVC, can the problems by removal of this waste be met. The method is that rigid PVC divides to chips (14) and is mixed with new PVC-resin (12), to which there is added a certain number of plasticizers (13), which mixture is compressed and melted until it is extruded through a tool (7, 8) and pelletized (9). Thereby this method produced material (15) can be used to production of new products, as it has physical properties corresponding to new PVC and furthermore can have greater softness.

Description: Method and Equipment to convert riged PVC The Level of the Technic The invention involves a method to convert riged PVC, which is divided in a grinding mill to a chip, into recyclable PVC, and a production unit to carry out the meth Hard or riged PVC is used in great extension both to technical articles, as pipes and sheets, and to packing objects as cups, bottles and similar.articles. The increasing use of riged PVC and the considerable quβntityof waste from the production in form of off-cutε etc. means that there is created a big waste problem as far as riged PVC is concerned, which in principle is searched solved either by that the waste is disposed of by incenerati or depositing or by recycling in prepared form. These possibilities give, however, reasons to considerable inconveniences. When PVC is incinerated, there is builted hydrochloric acid due to the content of chlorine, which contributes to the acidation of the environment. To reduce this acid escape there has to be carried out environmental investments of dkr. 2.00 per kilo PVC. Recycling of riged PVC is made difficult owing to the fact that it compels the addition of various additives, which causes very pure mechanical properties, especially the tensile strengh, which will be unacceptβbly poor. Experiments with various additives, which should be able to improve the properties of the recycled PVC show, however, th it only causes lightly improvements, and that the material will be more expensive than new PVC. Rigid PVC can practically only be recycled as riged PVC with reduced physical properties. This is due to the fact that riged PVC can not absorb plastizicer, which are high- boiling esthers of an oillik consistency, which releases between chainmolecules and solves its mutual polar binding so that there is made a more soft PVC. However, these plastizicers can not be mix to a sufficient extend in chips of riged PVC, while the plastizicers smoothe of the individual particles, which for instance can be of comminuted riged PVC-sheet, which slippery surface can not hold the plastizecerβ. This results in a unhomogeneous distribution of the plasti¬ zicers in the compound with the result, that the final product will be unhomogeneous with strongly variating pro¬ perties. Advantages by the Invention By according to the invention to use a procedure where the riged PVC-chips mixe with a PVC-resin and a plastizecer and if necessary stabilisers, after which this compound is mel¬ ted and stranded for after this to be pelletized on incident ally a usually known way, it turns out surprisingly, that the final product turns out homogenioυs soft and becomes physical properties, which completely correspond to the new softer PVC the explanation of this is, that the plastizicer can be absor in the single PVC resin particles in such a quantity and ex¬ tension, that PVC particles by the mixture can surround the single riged PVC particles. This means, that there is hap¬ pening partly a homogeneous distribution of the compound so that the hard PVC particles are added plastizicers by a surprisingly good distribution and compressed of rigid and flexible PVC in the melt, which hereafter can be pelle¬ tized. The result is that there by the procedure according the invention can be obtained both recycling of rigid PVC and softening of the PVC. By this there can be assured a rationally and environmentally advantageous recycling of rigid PVC and the environmental advantageous recycling of rigid PVC and the environmental damages a inceneration is causing can be completely avoided. By, as mentioned in claim 2, analysing the chemical com. pound of the rigid PVC, there can be added a specific com¬ pound of the new PVC and plastizicer, which results in a specific compound of the final recycled material. By this there can be recycled defined flexible PVC materials from riged PVC. At last it is convenient, as mentioned in claim 3, to use a production unit, where there is used known equipment, because the procedure by this can be completed in a practica and rational way. The Drawing A description of the procedure and a unit to carry this out accordin to the invention will be closer described in the following passage with reference to the drawing where fig. 1 shows a diagram of a unit to caary out the procedure fig. 2 shows a PVC recin particle with plastizicer, and fig. 3 shows a part of a chip of riged PVC. A description of the Procedure On fig. 1 is shown an exampel of a unit to recycling of rige PVC. As shown with an arrow 1 from the left the waste or the chip of riged PVC is supplied f. enstance in form of a sheet. This sheet is pressed through a grinding mill 2, where it is divided, so that it can be lead in the following mixture. After this the divided material 14 is conveyed to a silo 3, which can be used as temporary stock of the material IA. A register 4 regulates the flow to the nexct phase, viz. the mixing. The mixing is done in a mixer 6, where the divided rigid PVC 14 is added. Depending on the sort of and thereby the compound of the riged PVC 14, is produced a mixture 5, as shown with the arrow, pointing downwards, which mixture 5, is added to the mixer 6. The mixture 5 contents a known quantity of new PVC resin, which together with the plasticizer and if necessary other additives, as stabilizor, colour etc. 0 The mixing is carried out at a temperature around 120 C after which the compound is cooled down to around 80 C, before it is conveyed from the mixer via a register 4 and conveyed to an extruder with a εocalled driwing screw 7 where the material is compressed and heated to melting, so t it can be extruded through a tool 6. The extruded material passes a cutter 9 to pelletlze the material. This granulate is after this conveyed to a silo 11, where it is cooled in a ordinary known wa . From here, by a register 4 can the final recycled PVC- material 15 be siloed and used in a production just similar to a new PVC-material. The procedure will after this be described. By the receipt of the riged PVC material 1 is the recipi informed or the compound analysed and it is determined, which final compound 15, which is prefered produced. After this defined quantity new PVC-resin is estimated and it is calculated, how big a quantity plastizicer, which should be added the resin. The purpose by this will appear on fig. 2 and 3. On fig. 2 is shown a heavyly magnifyed picture of a new PVC resin 12, to which is added plastizicer 13, which can be obtained in a rather great quantity in fluent scape, while it will be absorbed and by that fixed at the grain, which i shown on the drawing. This is the explanation why the procedure according to the invention can recycle riged PVC, why the plastizicer 13 wil not be able to stick in a similar way on riged PVC material which is shown on fig 3. The plastizicer 13 will however slip off the PVC materials slippery surface, and thereby it will be prevented to be distributed equally on and between the divided material 14, in the mixer 6. This makes it possible, that there can. be adeed a surplus of plastizicer 13 to the resin 12, which during the mixing will stick to the specific riged PVC-particles 14 in such an extend, that the resin 12 with the plastizicer 13 will be homogeneous distributed in the compound with the riged PVC. This homogeneous compound will after that be compressed and heated to melting level around 180 C and after that granulated through a perferated tool 8, which can be a perfo rated disc, and thereby granulated by the tool 9. After the cooling is the final product of the discribed mixture, which can be a more soften PVC with specific improv properties. The invention is discribed in accordance with recycling of rigid PVC-sheet, but it is included in the invention limits also to use the procedure and the equipment to the recycling of other riged PVC-products, which hereby will be able to be recycled due to the possible improved properti and at a price which is more competitive compared with new PVC, at least when it is considered that there are no waste problems neither in connection with incineration nor depositing.

Claims: P a t e n t C l a i m 1. The procedure of transformation of riged PVC which is divided preferably in a grinding mill to chips, to recycable PVC, CHARACTERIZED by the divided rigid PVC chips (14) after this is mixed with a PVC-resin (12) and a plastizicer (13) and if necessary stabilizers, after which this compound (.12,13,14) is melted and stranded, for thereafter to be granulated in an incidentally ordinary known procedure. 2. The procedure according to claim 1, CHARACTERIZED by the riged PVC-chips (14) are analysed, after which the quantity of the PVC resin (12), plastizicer (13) and if nec¬ essary stabilizers arc determined and are added (5) in order to secure a defined compound of the recycable PVC (15). 3. Equipment to be used in the procedure according to claim CHARACTERIZED by it includes a grinding mill (2), and a mixer (6) and a perferated tool with a driving screw and a granulating tool (9).

Inventors: HOERUP MICHAEL WILHJELM, HOERUP, MICHAEL, WILHJELM
Applicants: HOERUP MICHAEL WILHJELM, HOERUP, MICHAEL, WILHJELM
Application year: 1995
Main classification: C08J3
IPC codes: C08J11, C08L27