DRÁVAI, Tibor (Ilka u. 17/a, Budapest, H-1143, HU)
SÉFER, Lászlóné (Béke u. 21, Bicske, H-2060, HU)
DRÁVAI, Tibor (Ilka u. 17/a, Budapest, H-1143, HU)
SÉFER, Lászlóné (Béke u. 21, Bicske, H-2060, HU)
| Claims 1 . Method for producing building products particularly roof tiles, concrete products, floor tiles, during the method additive material and binding material are mixed in a pre- mixer, wherein pulverized, granulated or shredded thermoplastic waste material is used as binding material, characterized in that said additive material is sand which is mixed in said pre-mixer with said pulverized, granulated or shredded thermoplastic material used as binding material to form a homogeneous mixture; said mixture is filled into a heating apparatus by means of an extruder and melted at a temperature of 150-350°C and under a pressure of 700-1800 kPa; the so obtained mixture is forced out from said apparatus and placed into the mould of the product; then the final shape of the product is formed by pressing; and when pressing is completed, said mould with the product inside is cooled. 2. Method according to claim 1 characterized in that the hardened product is taken out from said mould and further cooled. 3. Method according to claims 1 or 2 characterized in that said extruder is provided with a 2.5-4.5 m long conveyor screw in order to facilitate mixing. 4. Method according to any of claims 1 -3 characterized in that said additive material is first mixed with some paint. 5. Method according to claim 4 characterized in that said paint is in pulverized or liquid form. 6. Method according to any of claims 4-5 characterized in that said paint is resistant to UV radiation. 7. Building product particularly roof tile, concrete product, floor tile characterized in that said product contains 26-32 mass percentage of plastic waste material as binding material and 64.5-72 mass percentage of sand as additive material. 8. Building product according to claim 7 characterized in that said product contains 2- 3.5 mass percentage of paint, advantageously pulverized paint. 9. Building product according to claim 8 characterized in that said paint is resistant to UV radiation. |
PRODUCT FORMED BY THE METHOD
The invention relates to a method for producing building products particularly roof tiles, concrete products, floor tiles. During the method additive material or aggregate and binding material are mixed in a pre-mixer wherein pulverized, granulated or shredded thermoplastic waste material is used as binding material. The invention further relates to the product formed by the method.
Customarily, concrete products are made from classified gravel, sand, cement and water. Depending on the use of the product the quality and the quantity of the additive material and the binding material can be changed. Binding materials are powdery or "pulpy" materials which when mixed with some kind of additive material (gravel and water in case of concrete) become hard like stone through physical or chemical processes so that they can be used for producing building materials.
In our days there is an increasing demand for recycling e.g. plastic packaging materials and other plastic materials since in nature plastic takes a long time to degrade. People use more and more plastics which pollute the environment causing serious consequences. Because of the different materials stored in these plastic packaging materials repeated use of them is not possible.
Therefore destruction or recycling of these materials in some manner is required. Attempts have been made to produce conventional products by replacing the additive material or aggregate by using e.g. polystyrene beads instead of gravel.
Patent application HU 209 263 describes a method and apparatus for making shaped products having wood-like graining of mixed waste plastic wherein selected, agglomerated or ground waste plastic material is used, namely 20-60 mass percentage of polypropylene and/or 10-60 mass percentage of linear polyethylene and/or 10-40 mass percentage of soft polyethylene, 10-40 mass percentage of styrene and/or 10-60 mass percentage of polyethylene-terephthalate - and in a certain case 1-10 mass percentage of polyamide and 0.5-2 mass percentage of PVC waste - which are mixed. Thereafter 0.001-1.5 mass percentage of colouring agent, 0.01-1.3 mass percentage of plasticizer, 0.01-2 mass percentage of stabilizer, and in a certain case 10-20 mass percentage of reinforcing material, advantageously cut fibreglass, and 0.001-0.5 mass temperature between 140-270°C and is filled into a mould having an overflow which can be closed. After filling the mould the overflow is closed and pressing of the melted material is continued for 5-60, advantageously 25-30 seconds under a pressure of 1000-1600 Pa. Then the inlet of the mould is also closed and the mould is cooled down at ambient temperature or it is kept at ambient temperature for at least 30 minutes. Afterwards water-cooling is applied. Finally the product is removed from the mould. In this solution the composition of the plastic materials is essentially determined, the strength of the produced material can be ensured only by expensive reinforcing material which is difficult to treat.
Patent invention HU 225951 describes a method for processing polluted plastic waste material to a matrix product, then to a further processing of this matrix material into composite material preferably building material by adding additives. The characteristics of the process of producing matrix material are as follows: a) The plastic waste material is optionally submitted to preliminary cleaning depending on the pollution, b) The optionally pre-cleaned plastic waste material is loaded into a digesting machine, where the waste material is largely melted and transformed into an almost homogeneous, largely melted mixture under the pressure and temperature developed by the machine, c) The largely melted material is put into a heated mixer, where it is heat treated with intensive stirring, d) The melted material is optionally put into a mould die and matrix material blocks or moulded products made of the matrix material are produced. The characteristics of the production of composite material are that the additive material is added to the matrix material under mixing and heating and products are produced by means of a press.
Here, the final product is essentially produced only from plastic. If composite material is made, the additives are mixed with the already homogenous and melted plastic materials resulting in a mixture quality less good than as if the additives were mixed with the granulated, shredded plastic material before melting. Moreover, production of this kind of composite material is more expensive and the final product is less strong than the composition produced by processing the plastic material and the additive jointly. Patent application CH 610235 describes a casting and process for the production thereof wherein the casting contains at least two different plastics or a plastic and a material different from plastic and granular or pulverulent inorganic material. The casting contains 25 to 70% by weight of plastic, which serves as binder. In order to produce the casting, a mixture of at least two plastics or of a plastic and a material different from plastic is formed. In a stirrer, this mixer is mixed with a granular or pulverulent inorganic material which is heated to a temperature such that one plastic melts and a molten mass is formed from the mixture. From the molten mass, which contains 25 to 70% by weight of molten plastic which serves as binder, the casting is produced in a casting mould. Plastic waste can be used as the plastic and inorganic waste material as the inorganic material.
Here again, the additive material is mixed with the melted plastic material resulting in a less homogeneous material.
Patent application US 2003157297 describes a method and apparatus for forming an article in which thermoplastics materials are used as the binding agent. Materials are shredded in a shredder compressed in a compressing chamber and moulded in a moulding chamber. The thermoplastics material is heated whilst the material is held under compression and then cooled to bind the material together. In one embodiment superheated steam is supplied via tubes having apertures there along. In another embodiment superheated steam is supplied via apertures in side walls of the mould. Blocks formed by the method and apparatus can be used as construction materials etc. and have good structural, thermal and acoustic properties.
The aim and the possible application of this method is significantly different from that of the method of the present invention.
In each of the aforementioned solutions the proportion of plastic used as binding material is essentially larger than in the method of the present invention. The amount of sand they use is smaller than in the method of present invention, for this reason the strength of the products produced by the known methods fall behind the strength of the product made by the method of the present invention.
The aim of the present invention is to provide a method in which the binding material used for producing the building material is not newly made but it is made from recycled plastic waste material and mixed with the known additive materials for producing the building material.
It has been realized that building materials made earlier from concrete, clay, etc. e.g. for roof tiles, floor tiles, kerbs, gutters, etc. can be made from plastic and additives. In this case plastic waste material is used as binding material and sand is used as additive material. Any kind of thermoplastic waste material which can be pressed can be used as binding material.
Accordingly, the present invention is a method for producing building products particularly roof tiles, concrete products, floor tiles. During the method additive material or aggregate and binding material are mixed in a pre-mixer. As binding material pulverized, granulated or shredded thermoplastic waste material is used. The additive material is sand which in order to form a homogeneous mixture is mixed in the pre- mixer with the pulverized, granulated or shredded thermoplastic material used as binding material. The mixture is filled into a heating apparatus by means of an extruder and melted at a temperature of 150-350°C and under a pressure of 700-1800 kPa. The so obtained mixture is forced out from the apparatus and placed into the mould of the product. Then the final shape of the product is formed by pressing. When pressing is completed, the mould with the product inside is cooled.
Advantageously, the hardened product is taken out from the mould and further cooled. The extruder is provided with a 2.5-4.5 m long conveyor screw in order to facilitate mixing.
Preferably, at first the additive material is mixed with some pulverized or liquid paint which is resistant to UV radiation.
Further, the present invention is a building product particularly roof tile, concrete product, floor tile containing 26-32 mass percentage of plastic waste material as binding material and 64.5-72 mass percentage of sand as additive material.
Preferably it contains some pulverized paint which is resistant to UV radiation.
First in the method according to the invention the plastic materials are selected and cleaned e.g. washed preferably by applying large-scale cleaning process. Then the plastic material is dried and cut into small pieces in a shredder. Plastic materials which can be used include (but are not limited to) the following: PE(polyethylene), PP(polypropylene), PA(polyamide), PC(polycarbonate), HDPE(high density polyethylene), ABS, PS(polystyrene), PMMA( plexiglas or acrylic), PVC(polyvinyl chloride), foil. Advantageously they are used in powdery state.
During manufacture pre-coloured plastic granules may also be used which are made from waste material by other companies, e.g. DIREN EXIM (Cluj Napoca, Romania). Mechanical recycling of plastic waste materials is a growing tendency throughout the world. The advantage of purchased granules is that it is selected, the constituent parts are not mixed. A base material which is clear, translucent may be selected thereby the list of products may be made wider. As additive material suitably fine grained sand is used which is available at little cost. As colouring agent pulverized paint advantageously mixed with some material ensuring UV resistance is used.
The additive material is mixed with the pulverized paint in a mixer and a uniform, homogeneous material is formed. Then the binding material, e.g. the pulverous or granulated plastic material is added and mixed to obtain a uniform, homogeneous material. Then this mixture is filled into a heating apparatus by means of an extruder and melting is started at a temperature of 150-350°C under a pressure of 700-1800 kPa. The extruder is instrumental in mixing the binding material and the additive material. To obtain a better result an apparatus provided with at least a 2.5m long extruder screw is used.
The molten mixture is forced out from the apparatus and filled into the mould of the product. The final shape of the product is formed by pressing. When pressing is completed, the mould is cooled and the molten mixture solidifies. Then the product is taken out from the mould and further cooled. After that the shape of the product is fixed. Example: During manufacturing floor tiles 28 mass percentage of pulverized plastic binding material, 69 mass percentage of sand as additive material and 3 mass percentage of paint, advantageously UV resistant paint are mixed in the method described previously, and by melting the binding material a mixture is produced at a temperature of 225°C under a pressure of 1200 kPa. This mixture is filled into moulds of a required shape, and is pressed in a known manner. When pressing is completed the mould is cooled thereby the mixture within the mould becomes solid. The product is taken out from the mould and is entirely cooled down to ambient temperature.
Generally, the products weigh between 2-21 kg and each product can be produced on an average of 80 seconds even by using a simple technology.
The mixing ratio of the used materials depend on their quality and physical state. The proportion of the binding material and the additive material may be different by +/- 5 mass percentage depending on the quality of the additive material (sand).
When colouring of the material is required, in order to achieve the appropriate saturation of colour the amount and the colour of the additive material and the binding material must be considered. Therefore the percentage per unit volume may be different by some mass percentages from the proposed prescription. The desired colour (which may be e.g. fluorescent, too) must be set during trial production according to requirements. The manufacturing process may be made automatic and the manufacturing time may be shortened depending on the type of machine used in the process and which phase is automatized. However, the manufacturing method is essentially the same in each case. The advantage and uniqueness of the method according to the invention is that conventional products can be made by using a new type of binding material together with the known additive material. The products produced by the method according to the invention weigh 35% less than the products of the same type, while their physical properties do not fall behind the physical properties of the products produced in the known manner. The uniqueness of the method according to the invention is that a new type of binding material is used which comes from secondary waste. After re-melting the products may be reprocessed and used again.