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Publication numberWO2004056545 A1
Publication typeApplication
Application numberPCT/EP2003/013957
Publication date8 Jul 2004
Filing date9 Dec 2003
Priority date20 Dec 2002
Also published asEP1656241A1, WO2004056545A8, WO2004056545B1
Publication numberPCT/2003/13957, PCT/EP/2003/013957, PCT/EP/2003/13957, PCT/EP/3/013957, PCT/EP/3/13957, PCT/EP2003/013957, PCT/EP2003/13957, PCT/EP2003013957, PCT/EP200313957, PCT/EP3/013957, PCT/EP3/13957, PCT/EP3013957, PCT/EP313957, WO 2004/056545 A1, WO 2004056545 A1, WO 2004056545A1, WO-A1-2004056545, WO2004/056545A1, WO2004056545 A1, WO2004056545A1
InventorsFranco Lico
ApplicantLico S.P.A.
Export CitationBiBTeX, EndNote, RefMan
External Links: Patentscope, Espacenet
A method for manufacturing products made of rigid and plasticised pvc, in particular tubes, section bars, cables and calendered elements
WO 2004056545 A1
Abstract
The invention refers to a method for manufacturing products made of rigid and plasticised PVC, in particular tubes, section bars, cables and hot rolled elements, where the method is articulated in a single passage, completely continuous with two possible outcomes depending on whether it is applied to extrusion or calendering processes.
Claims  (OCR text may contain errors)
Patent claims
1. A method for manufacturing products made of rigid and plasticised PVC in particular tubes, section bars, cables and calendered elements, characterised in that the method comprises a single passage, completely continuous with two possible outcomes depending on whether it is applied to extrusion or calendering processes.
2. The method as claimed in claim 1 , characterised in that raw materials (1 ) are stored separately and are proportioned (2) according to two different processes.
3. The method as claimed in claims 1 and 2, characterised by a continuous volumetric or gravimetric proportioning of a pre-mixture of solids and a pre-mixture of liquids, fed distinctly into a continuous turbo mixer (3 in
Fig. 2).
4. The method as claimed in claims 1 and 2, characterised by a continuous, volumetric or gravimetric proportioning, but separate proportioning of solids and liquids (Fig. 3).
5. The method as claimed in any of claims 1 to 4, characterised in that inside a turbo mixer (3) runs a constant and homogeneous flow of raw materials which, in their path towards discharge point, are accurately mixed.
6. The method as claimed in claim 5, characterised in that depending on the final product, the output of the turbo mixer (3) directly feeds a continuous extruder (4) for the production of tubes, section bars or cables, or a calender (5) for the production of films, sheets or plates.
7. Product manufactured according to the method as claimed in any of the claims 1 to 6.
Description  (OCR text may contain errors)

Method for manufacturing products made of rigid and plastic PVC, in particular tubes, section bars, cables and calendered elements

The preparation of PVC mixtures with continuous process has for decades been a pressing problem for those who deal with this polymer. Different solutions have been proposed in the past, but none of them has been able to find widespread industrial use.

More than any other thermoplastic polymer, PVC resin requires a very accurate statistical distribution of the individual components such as plasticiser, stabiliser, lubricator, modifier and pigment in their polymeric matrix, before starting the thermal process of gelling. The good pre-dispersion of these components, therefore, is the primary condition to obtain a good final compound or extruded product.

To date, this step in PVC transformation is achieved solely by discontinuous processes, based on hot/cold rapid mixers or on slow heated mixers.

State of the art (Fig. 1 )

Depending on the final outcome of the production process, tubes, section bars, cables, calendered elements, the traditional method comprises different steps within a discontinuous process.

A. Dry-blend preparation

The raw materials, solid (resins, stabilising charges, additives) and liquid (plasticisers, stabilisers etc.), stored separately (1 ), are proportioned "in charges" (2): volumetrically, on one or more batch scales; individually in gravimetric fashion inside the mixer. The slow-speed or high-speed mixer (3) is always heated to a variable temperature and it serves the purpose of mixing all agents to the PVC resin. It will work the material loaded by the proportioning devices for a given residence and process period, to be subsequently emptied of the mixture and re-start the cycle receiving the raw material from weighing. The mixture, called dry-blend, moves to a cooler (4) which brings it to the correct temperature for the following process.

B. Intermediate granulation

The dry-blend moves from the cooler to a volumetric or gravimetric proportioning device (5) which will feed the compounder for granulation (6). The PVC granule is then transferred to the intermediate storage sites or to be sacked.

C. Cable extrusion

The PVC granule is transported from storage to a pre-heater (8), wherefrom the extruder of the cable (9) is fed by gravity, to increase its productivity.

D. Tube or section bar extrusion

This extrusion process can take place using PVC compounded in granules (see process C) or stored dry-blend (10) at the output of the cooler. From storage, the dry-blend is transported onto the extrusion line, proportioned in volumetric or gravimetric fashion (11) inside the continuous extruder (12) to produce a tube or section bar.

E. Calendering:

The dry-blend is proportioned in volumetric or gravimetric fashion (13) inside a continuous mixer (14) which directly feeds the calender (15) without granulating the PVC.

The task of the invention is to obtain a continuous method for manufacturing products made of rigid or plasticised PVC, in particular tubes, pipes, section bars, cables.

The method described herein comprises a single passage, completely continuous, but with two possible outcomes depending on whether it is applied to extrusion processes (tubes, section bars, cables) or calendering processes (wires, plates, etc.). it starts from the separate storage of the raw materials (1 ), which can be proportioned (2) according to two different methods:

- continuous volumetric or gravimetric proportioning of a pre-blend of solids (powders, granules, ground, compacted material and all kinds of grain size) and a pre-blend of liquids, distinctly fed inside the Continuous Turbo Mixer (Figure 2),

- continuous, volumetric or gravimetric but separate proportioning (Figure 3) of each individual solid or liquid material (however, compatible liquids can be pre-mixed).

Solids and liquids feed in two separate and distinct flows the Continuous Turbo Mixer (3) which disperses and diffuses all solid and liquid agents on the PVC resin and mixes them with the charges. Inside the mixer there is a constant and homogeneous flow of raw materials which, in their path towards the discharge point, are accurately mixed. What distinguishes and elevates the Continuous Turbo Mixer to the ideal machine for blends that are sensitive to shear and temperature, such as the dry blends of rigid or plasticised PVC, is the possibility of working the materials without transferring energy by mechanical friction and hence without inducing an uncontrolled rise in temperature. The absence of friction on the material to be blended will also prevent the formation of agglomerates (from additives, stabilisers and low-melting point products) in the dry blend, which comprise the quality of the final product.

The Continuous Turbo Mixer may be heated or cooled depending on the formulation.

Depending on the final product, the output of the Continuous Turbo Mixer may directly feed a continuous extruder (4) for the production of tubes, section bars or cables, or a calender (5) for the production of films, sheets, plates etc.

The advantages of the method according to the invention overcome the defects of the discontinuous processes of the prior art and are essentially qualitative and economic quantitative in nature.

The Continuous Turbo Mixer assures an excellent quality of the dry blend, free from agglomerates and polluting impurities, which are the inevitable residue of any blend obtained in batches. This is due to the absence of stagnation and pollution points, and to the fact that a short residence time and the absence of friction do not allow the components to become degraded (by friction and compaction, heat).

For the manufacturing of plasticised PVC, the proportioning-blending system according to the invention allows to homogenise different concentrations of plasticiser on resin. Equally accurate and efficient is the homogeneous diffusion of liquid agents in minimum quantity, such as stabilisers and, for example, colour pastes.

The method of the invention allows 2 different reasons for energy saving in the production of the dry-biend of rigid or plasticised PVC.

1. The Continuous Turbo Mixer allows to mix constant flows of raw materials, enormously reducing the volume of the mixing chamber and organs relative to a traditional slow or fast batch mixer. The result is a corresponding reduction in installed power.

2. In the case of cable production, the cable extruder may be fed directly with dry-blend at the desired temperature, thereby eliminating the need to pre- heat the PVC granules.

Given the short time of permanence of the products in the mixer, it may be decided at any time to stop the plant without wasting even a minimum quantity of raw material. The mixer has no areas of stagnation of the material: all that it is fed is transported to the output in the motion created by the rotating shaft. If the chamber of the mixer retains a very thin layer of residual product, it can easily be removed by feeding it only neutral resin for a far shorter time than required by a traditional mixer.

The efficient distribution capability in the blend translates into a reduction in the quantity of extremely costly additives and stabilisers which in the discontinuous process, due to the difficulty in their dispersion in the blend, are fed in excess quantities.

A traditional automated discontinuous installation can develop according to two widely employed designs: 1. vertically, for a height of over twenty meters and through several floors, allowing to manage the flow of raw materials and the passage of the PVC blend solely by gravity along the various discontinuous transformation stages, 2. otherwise, the vertical development of the building may be moderated, but the material will have to be boosted or brought back to a certain elevation passing from a transformation phase to another (storage, proportioning, mixing/cooling, compounding).

The method of the invention needs installations with moderate vertical development, variable between eight and ten meters and a single floors, whereby the raw materials and the semi-finished product are moved by gravity until the extrusion, granulation or calendering step.

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
EP0611250A1 *28 Jan 199417 Aug 1994ICMA SAN GIORGIO S.p.A.Extrusion method and plant
EP0709172A1 *7 Sep 19951 May 1996POMINI S.p.A.Apparatus for continuously feeding extrusion and/or rolling machines with viscous material such as rubber and the like coming from discontinuous-cycle machines
EP0775718A2 *21 Nov 199628 May 1997UNION CARBIDE CHEMICALS & PLASTICS TECHNOLOGY CORPORATIONProcess for preparing elastomeric compounds from granular elastomers and polymers
GB817981A * Title not available
GB1134167A * Title not available
US4698378 *20 Dec 19826 Oct 1987Buss AgProcedure for the continuous production of free flowing and homogenous mixtures of plastic materials with admixtures
US4889673 *6 Dec 198826 Dec 1989Toyoda Gosei Co., Ltd.Process for preparing polyvinyl chloride material used for extrusion molding
Non-Patent Citations
Reference
1 *[Online] 2001, , XP002276812 Retrieved from the Internet: URL:http://www.polymer-age.co.uk/k1/k1comp ound.htm#Continuous%20mixer%20now%20has%20 melt%20pump%20discharge> [retrieved on 2003-04-05] page 3
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
WO2009114761A3 *13 Mar 200921 Apr 2011Dow Global Technologies Inc.Improved process for shaping polymeric articles
US852982129 Jan 201010 Sep 2013Dow Global Technologies LlcPolymeric compositions and filled TPO articles having improved aesthetics
US870931613 Mar 200929 Apr 2014Dow Global Technologies LlcProcess for shaping polymeric articles
Classifications
International ClassificationB29K27/06, B29B7/00, B29C31/02, B29B7/60, B29C47/10
Cooperative ClassificationB29B7/60, B29C47/0023, B29L2031/707, B29B7/007, B29C47/0026, B29C47/1063, B29K2105/0044, B29C47/0021, B29L2023/00, B29C47/1018, B29K2105/0038, B29K2027/06, B29C47/0019, B29K2105/0005, B29C31/02, B29C47/366
European ClassificationB29C47/10L, B29C47/10H, B29B7/60, B29B7/00B5
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