GB2135328A

GB2135328A - Method of manufacturing articles from paint sludge

Info

Publication number: GB2135328A
Application number: GB08404096A
Authority: GB
Inventors: Carlo Rovini
Original assignee: RECYCLING SpA
Current assignee: RECYCLING SpA
Priority date: 1983-02-25
Filing date: 1984-02-16
Publication date: 1984-08-30
Also published as: DE3406749A1; ES8502713A1; FR2541598A1; ES529877A0; BR8400909A; IT1171003B; IT8367217A0; GB2135328B; FR2541598B1; GB8404096D0

Abstract

Paint sludge is mixed with thermoplastic and/or thermohardening resins and optionally with a filler and/or reinforcing material, and hot-extruded to form an intermediate product. This is then used for the production of manufactured articles.This allows paint sludge to be recovered economically on an industrial scale and provides articles having good physical properties. Examples of such articles are panels, sheets, tubes, containers for the electronics industry, and irrigation pipes and unions, which may be formed from such resins as ABS, polystyrene, polyolefin, polyamide, phenolic urea and melamine resins.

Description

SPECIFICATION Method four manufacturing articles from paint sludge The present invention relates to a method for manufacturing articles from paint sludge. It is known that industrial painting processes, such as spraying, dipping and electrostatic processes, produce enor mousquantitiesofwastewhich isforthe most part collected in the form of a sludge in aqueoussuspen- sion.

The disposal of such sludges has always posed considerable problems ofan ecological and economic nature. For example, the high percentage of solvents, the evolution of acrid and troublesome fumes, and the presence of polluting substances in the ashes have made their destruction bycalcining expensive and not very safe.

The most simple solution currently used involves the discharge ofthe sludges into suitable reinforced concrete vessels which, when completely filled, are sealed by concrete lids and buried. Clearly, this involves considerable expense without any economic return.

There have been several attempts to use the sludge, after suitable drying and the addition of suitable binders, for the production of panels similarto chipboard but the poor mechanical strength of such panels,togetherwith the high cost ofthe necessary plant, have in effect prevented application on an industrial scale.

The object of the present invention is to provide a method for the industrial recovery of paint sludge which results in a useableproductandthusan economic return.

According to the present invention, there is provided a method for manufacturing articles from paint sludge, including the steps of mixing the sludge with at leastonetype of resin chosen from a thermoplastic resin and a thermohardening resin, hot-extruding the mixture to form a half-product, and working the half-productto produce a manufactured article.

Thethermoplasticandthermohardening resins may be selected from ABS, polystyrene, polypropylene, polyethylene, polyamide, phenolic resins, ureic resins, melamine resins and the like. A reinforcing material chosen from vegetable or synthetic fibres, fibre-glass, mineral wool and the like and/or a powdered filler selected from talc, gypsum, calcium carbonate, silica, olivine, wood4lour and the like may be added to the paint sludge in addition to the resin.

The hot-extrusion step ensures that the various components are homogenised, and eliminates most of the water and solvents contained in the mixture.

The intermediate product or half-product resulting from the hot extrusion step may be conditioned at a temperature of between 50 and 1 30"C, possibly in a vacuum,to complete the elimination ofthe solvents and improve its formability, prior to the working step.

In the subsequent working step, the half-product is processed, according to the type of manufactured articles to be produced (panels, sheets, tubes or products of any other type or shape), by rolling, drawing, extrusion or mouiding (with our without injection) attemperatures of between 1 000C and 260"C.

The manufactured articles obtained bythe method of the present invention are characterised by very good mechanical strength, very good resistance to atmospheric agents, and very good dimensional characteristics.

Three ways of performing the method according to the present invention will now be described byway of example.

Example 1 A mixture is made comprising paint sludge, 30% silica flour and 30% ABS resin and this mixture is then extruded at a temperature of 1 90"C to provide a half-product. The half-product is conditioned at 70"C forfour hours in a vacuum and is subsequently injection-moulded to form containers forthe electronics industry which pass all the type-approval tests.

Example 2 A mixture containing paint sludge, 40% phenolic and 25% mineral wool is extruded at 70"C to form a half-product which, after conditioning at 60'Cfor three hours, is hot-extruded to produce irrigation pipes and unions.

Example3 A mixture of 50% paint sludge, 40% phenolic resin and 10% vegetable fibres is extruded and conditioned and then used to form flat panels.

It is to be noted that all percentages indicated in the present specification and claims are percentages by weight.

1. Methodformanufacturing articlesfrom paint sludge, including the steps of mixing the sludge with at least one type of resin chosen from a thermoplastic resin and a thermohardening resin, hot-extruding the mixture to form a half-product, and working the half-product to produce a manufactured article.

2. Method according to Claim 1, in which at least one material chosen from a filler material and a reinforcing material is added to the mixture of sludge and resin priortothe hot-extrusion step.

3. Method according to Claim 1, in which between 10% and 70% resin is added to the paint sludge.

4. Method according to Claim 2, in which the mixture includes between 5% and 40% filler material.

5. Method according to Claim 2 or Claim 4, in which the mixture includes between 5% and 40% reinforcing material. 6. Method according to Claim 1, in which the hot-extruded half-product is conditioned at a temperature of between 50"C and 1 30 C prior to the working step.

7. Method according to Claim 6, in which the conditioning is carried out in a vacuum.

8. Method according to Claim 1, in which the half-product is worked at temperatures of between 1 000C and 260"C by a process chosen from rolling, drawing, extrusion and moulding.

9. Method for manufacturing articles from paint sludge, substantially as herein described.

10. An article whenever manufactured by the method ofanyforegoing claim.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Method four manufacturing articles from paint sludge The present invention relates to a method for manufacturing articles from paint sludge. It is known that industrial painting processes, such as spraying, dipping and electrostatic processes, produce enor mousquantitiesofwastewhich isforthe most part collected in the form of a sludge in aqueoussuspen- sion. The disposal of such sludges has always posed considerable problems ofan ecological and economic nature. For example, the high percentage of solvents, the evolution of acrid and troublesome fumes, and the presence of polluting substances in the ashes have made their destruction bycalcining expensive and not very safe. The most simple solution currently used involves the discharge ofthe sludges into suitable reinforced concrete vessels which, when completely filled, are sealed by concrete lids and buried. Clearly, this involves considerable expense without any economic return. There have been several attempts to use the sludge, after suitable drying and the addition of suitable binders, for the production of panels similarto chipboard but the poor mechanical strength of such panels,togetherwith the high cost ofthe necessary plant, have in effect prevented application on an industrial scale. The object of the present invention is to provide a method for the industrial recovery of paint sludge which results in a useableproductandthusan economic return. According to the present invention, there is provided a method for manufacturing articles from paint sludge, including the steps of mixing the sludge with at leastonetype of resin chosen from a thermoplastic resin and a thermohardening resin, hot-extruding the mixture to form a half-product, and working the half-productto produce a manufactured article. Thethermoplasticandthermohardening resins may be selected from ABS, polystyrene, polypropylene, polyethylene, polyamide, phenolic resins, ureic resins, melamine resins and the like. A reinforcing material chosen from vegetable or synthetic fibres, fibre-glass, mineral wool and the like and/or a powdered filler selected from talc, gypsum, calcium carbonate, silica, olivine, wood4lour and the like may be added to the paint sludge in addition to the resin. The hot-extrusion step ensures that the various components are homogenised, and eliminates most of the water and solvents contained in the mixture. The intermediate product or half-product resulting from the hot extrusion step may be conditioned at a temperature of between 50 and 1 30"C, possibly in a vacuum,to complete the elimination ofthe solvents and improve its formability, prior to the working step. In the subsequent working step, the half-product is processed, according to the type of manufactured articles to be produced (panels, sheets, tubes or products of any other type or shape), by rolling, drawing, extrusion or mouiding (with our without injection) attemperatures of between 1 000C and 260"C. The manufactured articles obtained bythe method of the present invention are characterised by very good mechanical strength, very good resistance to atmospheric agents, and very good dimensional characteristics. Three ways of performing the method according to the present invention will now be described byway of example. Example 1 A mixture is made comprising paint sludge, 30% silica flour and 30% ABS resin and this mixture is then extruded at a temperature of 1 90"C to provide a half-product. The half-product is conditioned at 70"C forfour hours in a vacuum and is subsequently injection-moulded to form containers forthe electronics industry which pass all the type-approval tests. Example 2 A mixture containing paint sludge, 40% phenolic and 25% mineral wool is extruded at 70"C to form a half-product which, after conditioning at 60'Cfor three hours, is hot-extruded to produce irrigation pipes and unions. Example3 A mixture of 50% paint sludge, 40% phenolic resin and 10% vegetable fibres is extruded and conditioned and then used to form flat panels. It is to be noted that all percentages indicated in the present specification and claims are percentages by weight. CLAIMS

5. Method according to Claim 2 or Claim 4, in which the mixture includes between 5% and 40% reinforcing material.

6. Method according to Claim 1, in which the hot-extruded half-product is conditioned at a temperature of between 50"C and 1 30 C prior to the working step.

10. An article whenever manufactured by the method ofanyforegoing claim.