NL2010047C2

NL2010047C2 - Plastic material comprising fly ash as a filler, method for preparing such material and use of fly ash as a filler in plastic materials.

Info

Publication number: NL2010047C2
Application number: NL2010047A
Authority: NL
Inventors: Richard Roderick Achterberg
Original assignee: Achterberg Trading Company B V
Priority date: 2012-12-21
Filing date: 2012-12-21
Publication date: 2014-06-24

Description

PLASTIC MATERIAL COMPRISING FLY ASH AS A FILLER, METHOD FOR PREPARING SUCH MATERIAL AND USE OF FLY ASH AS A FILLER

IN PLASTIC MATERIALS

5

TECHNICAL FIELD OF THE INVENTION

The present invention relates to plastic materials comprising a plastic matrix, which plastic matrix comprises an inorganic filler, which filler comprises fly ash.

10

BACKGROUND OF THE INVENTION

Fly ash has been produced for many years in coal-fired power stations in great quanties. Nowadays, besides coals other kinds of fuels are used in power stations, such 15 as biological material (e.g. wood) or house waste. However, also these alternative fuels for power stations produce fly ash.

Fly ash consists of three main fractions. The first fraction of particles present in fly ash are the so called plerospheres, which have a size between 100 and 300 pm. These particles consist of a relatively thick outer coating filled with fly ash pearls 20 therein. A second fraction is formed by the so called cenospheres, which are light weight, inert, hollow spheres made largely of silica and alumina and which are filled with air or inert gas. The third and last fraction of fly ash is formed by spheres consisting primarily of siliciumoxide (S1O2) and aluminiumoxide (AI2O3), which spheres have a size of 1 to 100 pm.

25 Generally, fly ash is considered to be a waste product and its uses are relatively limited. For example, fly ash is used for landfill or minefill. Another application is to use fly ash as a filler in cement and concrete. However, up till now it has not been possible to economically use fly ash as a high quality and high performance filler in for example plastic products. In order to prepare a high performance filler which is safe 30 and has acceptable physical characteristics, the fly ash has to be subjected to a very laborious and expensive process. In US 5047145 a process for increasing the industrial value of fly ash derived from coals has been described. This process is very expensive and renders fly ash fractions which are not very useful for use as a filler in plastic 2 materials. Especially if relatively large amounts of filler are used the properties, such as tensile strength, yield strength, elongation and Young’s modulus of the plastic material prepared from the fly ash according to US 5047145 are relatively poor.

In view of the above, a need exists to prepare and use fly ash which can be used 5 as a high performance filler, for example as a filler for plastic materials, which filler provides excellent properties to the plastic and is comparable with other, non fly ash, fillers and which filler is relatively cheap to produce and does not comprise high levels of hazardous components which may leak from the plastic material.

10 SUMMARY OF THE INVENTION

A first aspect of the present invention relates to a plastic material comprising a plastic matrix and 1 to 70 wt% of an inorganic filler, wherein the filler comprises 50-100% of fly ash particles having an average particle size of 1 - 50 pm.

15 As has been shown in the experimental part of the present application, the plastic material according to the present invention shows comparable properties to other fillers commonly used in plastic materials. Furthermore, by means of the use of the fly ash fraction according to the present invention it is possible to re-use a large portion of the fly-ash such that the burden on the environment is reduced.

20 The fly ash particles having an average particle size of 1-50 pm as used in the present invention have been obtained from for example power- or thermal powerplants which use as fuel: company waste, consumer waste, coals (brown and black), biomass and coal mixed with biomass. One of the advantages of the fraction of particles of fly ash according to the present invention is that they comprise a relatively low amount of 25 hazardous materials which may leak from the plastic material once it is used in a filler.

Furthermore, as has been shown in more detail in the experimental part of the present invention, the fraction of fly ash according to the present invention can be used as a high performance filler for plastics, which filler is comparable to other fillers commonly used in plastics.

30 A second aspect of the present invention relates to a method for preparing a plastic material according to any of the previous claims, comprising the step of: i) providing a thermoplastic or thermosetting basic material; ii) mixing on a total weight basis 1-70 wt% of an inorganic filler with the plastic basic 3 material and allowing the plastic material obtained to set, wherein the inorganic filler comprises 50 - 100 wt% of fly ash particles having an average particle size of 1-50 pm.

A third aspect of the present invention relates to the preparation of granules from the plastic obtained with the above mentioned method as well as to the granules as 5 such. Such granules are generally provided in bulk packaging to manufactures preparing plastic articles. Preferred methods for preparing such plastic articles are rotational molding and injection molding.

A fourth aspect of the present invention relates to the use of fly ash having an average particle size of 1 - 50 pm as an inorganic filler in a plastic material.

10

DEFINITIONS

The term ufly ash” as used herein has its normal scientific meaning and refers to the ashes produced by power stations after burning coal (brown and/or black), company 15 waste, consumer waste, biomass or a combination of any of these fuels.

The term “average particle size” as used herein has its normal scientific meaning as has been described in the ISO standard 9276-5.

The term “inorganic filler” as used herein has its normal scientific meaning and refers to material which is added to a binder material, such as plastics, to lower the 20 consumption of the more expensive binder material or to adjust the properties of the mixtured material. Furthermore, the filler comprises on a weight basis at least 50% inorganic constituents and is therefore considered an inorganic filler.

The term “absolute density” as used herein has its normal scientific meaning and refers to the mass per unit volume (e.g. kg per m3) of a substance.

25

DETAILED DESCRIPTION OF THE INVENTION

A first aspect of the present invention relates to a plastic material comprising a plastic matrix, and 1 to 70 wt% of an inorganic filler, wherein the filler comprises 50-30 100% of fly ash particles having an average particle size of 1 - 50 pm.

As has been shown in the experimental part of the present application, the plastic material according to the present invention shows comparable properties to other high performance fillers commonly used in plastic materials. Furthermore, by 4 means of the use of the fly ash fraction according to the present invention it is possible to re-use a large portion of the fly-ash such that the burden on the environment is reduced.

The fly ash particles having an average particle size of 1-50 pm as used in the 5 present invention have been obtained from the burning of coal (brown and/or black), company waste, consumer waste, biomass or a combination of any of these fuels. One of the advantages of this fraction of particles is that they comprise a relatively low amount of hazardous materials which may leak from the plastic material once it is used in a filler. Furthermore, the physical properties the fly ash comprising filler according 10 to the present invention provides to plastic materials is comparable to other high performance fillers commonly used in plastics, such as talc or chalk.

The particle size distribution is preferably such that at least 50% of the fly ash particles fall within the range of l-50pm, more preferably at least 70%, more preferably at least 80%, most preferably at least 90%.

15 The fly ash particles used in the present invention are preferably directly obtained from a modern power supply. Due to the fact that modem power supplies have a considerably better efficiency of burning of the coals and/or other fuels (typically 95 or higher, preferably 98% or higher, more preferably 99% or higher) and for reasons that they have a dedicated separation of the usable and needed fly-ash particles, the 20 process for obtaining the fly ash fraction as used in the present invention has become economically viable.

Furthermore, due to this dedicated separation the density of the fly ash particles according to the invention will be relatively high. Hence, the absolute density of the fly ash particles will be relatively high compared to fly ash particles obtained from old 25 power stations having a considerably lower efficiency of burning (typically 50-90%), while the size of the fly ash particles has reached his optimum. This has a favorable effect when the fraction of particles is used as a filler in for example plastic materials.

The fly ash particles as used in the present invention have, when obtained from the buring of coals in a modem power supply, preferably an alkali content below 3% 30 (measured according to NEN-EN 196-2)and a soluble sulphate content below 1 mg/kg (measured according to NEN-EN 450-1+1:2007]

Preferably, the fly ash particles have an average particle size of 1 - 30 pm, preferably 1 - 20 pm. In this regard it is particularly preferred when the size 5 distribution is such that at least 50% of the particles fall within this range, more preferably at least 70%, more preferably at least 80%, most preferably at least 90%.

The fly as particles in the inorganic filler as used in the present invention comprises on a weight basis at least 50% inorganic constituents, such as 5 siliciumdioxide (SIO2), aluminiumoxide (AI2O3). Typically the fly ash particles according to the present invention when derived from the burning of coals have the following composition Table 1:

Table 1: composition of fly ash particles fraction (l-50pm) derived from 10 coal only

Constituent Mean (wt%) Range (wt%)

Silicium dioxide (S1O2) 50 43-70

Aluminium oxide (AI2O3) 25 19-31

Iron oxide (F62()3) 7 2-11

Calcium oxide (CaO) 3 0.3-7

Magnesium oxide (MgO) 2 0.2-4

Potassium and sodium 3 0.1-4 oxide (K20, Na20)

Sulphur dioxide, 2.5 1-3 titaniumdioxide, phophorpentaoxide (S02, T1O2, P205)

Carbon 5 3-11

The inorganic filler comprises preferably 70 - 100% of fly ash particles. In a preferred embodiment of the present invention, the inorganic filler comprises 80-100% of fly ash particles. Besides fly ash particles it is possible to include in the inorganic 15 filler other inorganic constituents such as for example calcium carbonate (CaCCh).

The fly ash particles used in the inorganic filler of the present invention preferably have an absolute density of 2200 to 3000 kg/m3. More preferably the absolute density of the particles is preferably 2500 to 3000 kg/m3, more preferably 2800 to 3000 kg/m3.

6

As stated above, the plastic material according to the present invention comprises a plastic matrix with distributed therein an inorganic filler, which filler comprises the claimed fraction of fly ash particles. The plastic material according to the present invention preferably comprises 5 to 80 wt%, more preferably 10 to 75 wt%, 5 most preferably 20-35 wt% or 60-75 wt% of the inorganic filler.

In a particularly preferred embodiment of the present invention the plastic material comprises 20 to 50 wt% of the inorganic filler, wherein the inorganic filler comprises 80 - 100 wt% fly ash particles, and wherein the fly ash particles have an average particle size of l-50pm, preferably 1-20 pm.

10 The plastic matrix comprises thermoplastic polymers and/or thermosetting polymers. Preferred thermoplastic polymers are polyethylenes, polypropylenes, polyallomers, polyimide’s, polyamide-imides, polysulfones, polystyrene, vinyl’s, acrylonitrile-butadiene-styrene, acetals, acrylics, aramids, cellulosic’s, ionomers, nylons, parylenes, polyaryl ether, polyaryl sulfone, polycarbonates, polyesters, 15 polyethylene sulfide.

Prefered thermosetting plastics are alkyd, diallyl phthalates, epoxies, melamines, phenolics, polybutadienes, polyesters, silicones and urea’s. Preferably elastomeric thermoset polyolefin’s are used.

More preferably the plastic matrix comprises thermoplastic polyolefin’s such as 20 polyethylene, polypropylene, polymethylpentene, polybutene.

In special embodiments of the present invention it also possible that the plastic matrix of the plastic article according to the present invention comprises a combination of the above mentioned thermoplastic and thermoset plastic polymers.

A second aspect of the present invention relates to a method for preparing a 25 plastic material according to any of the previous claims, comprising the step of: i) providing a thermoplastic or thermosetting basic material; ii) mixing on a total weight basis 1-70 wt% of an inorganic filler with the plastic basic material and allowing the plastic material obtained to set, wherein the inorganic filler comprises 50 - 100 wt% of fly ash particles having an average particle size of 1-50 pm.

30 By means of the above mentioned method it is possible to prepare a plastic material which comprises the claimed fraction of fly ash particles. This way, it is possible to re-use fly ash without reducing the physical properties such as tensile strength, elongation at break and Young’s modulus of the plastic material obtained, or 7 the items formed therefrom, when compared with other fillers used in plastic materials such as chalk or talc.

The thermoplastic or thermosetting basic material may be any of the polymers mentioned above, or a combination thereof 5 Preferably, the thermoplastic basic material is a polyolefin, such as polyethylene, polypropylene, polymethylpentene, polybutene.

If a thermosetting basic material is used, the thermosetting basic material is preferably alkyd, diallyl phthalate, epoxy, melamine, phenolic, polybutadiene, polyester, silicone, urea or a combination thereof.

10 Preferably, the thermoplastic or thermosetting basic material is heated prior to the mixing with the anorganic filler. However, also during heating the inorganic filler may be added to the thermoplastic or thermosetting basic material, this is generally referred to as compounding. During addition of the inorganic filler the mixture is preferably stirred such that an evenly distribution of the inorganic filler in the matrix is 15 obtained.

In a subsequent step, the plastic material obtained is preferably granulated into granules. The granules preferably have a largest diameter or length of 1 to 5 mm. This is particularly suitable if thermoplastic polymers are used as the basic material. The granules are packaged in containers or bags and distributed to customers which may 20 remold the granules and form plastic objects thereof, for example by means of injection molding.

A third aspect of the present invention relates to granules obtainable by the above mentioned method.

A fourth aspect of the present invention relates to the use of the plastic material 25 described above, or granules thereof in rotational molding or injections molding. This way, a large variety of plastic articles may be formed from the plastic material according to the present invention or from the granules prepared thereof.

A last aspect of the present invention relates to the use of fly ash having an average particle size of l-50pm as an inorganic filler in a plastic material.

30 The invention will now be further illustrated by way of the following non limiting examples.

8

EXAMPLE

In this example the different properties of a plastic article prepared from polypropylene with different fillers has been examined. The following process was 5 used for preparing the plastic material.

As a base material polypropylene was used, the polypropene was heated and the filler was added while stirring using side feeders with gravimetrical dosing. After the filler was thoroughly mixed through the polypropylene granules were prepared from the plastic material by means of using a double screw extruder with underwater 10 granuling. This way the following plastic granules were prepared: I. polypropylene granules with 30 wt.% of an inorganic filler comprising 100% fly ash particles, which particles have an average particle size of 30 pm and wherein at least 80% of the particles is smaller than 50 pm (example according to the invention); 15 II. Polypropylene granules with a basic inorganic filler comprising 30 wt% of talc (magnesium silicate) (compartive example); and III. Polypropylene granules with basic inorganic filler comprising 30% of chalk 20 (calcium carbonate) )compartive example).

From these granules a plastic rod was prepared (10*5*1 cm) by means of injection molding. The rods were prepared with an ordinary injection molder using a specific mould adapted for preparing rods with the above mentioned dimensions.

25 The physical properties of the rods were measured, the results thereof are depicted in table 2 below.

30 9

Property Unit Method Fly ash Talc Chalk E-modulus Mpa ISO 527-1/2 2900 2800 3100

Maxtensile Mpa ISO 527-1/2 31.5 26 21.5 strength

Max. tensile % ISO 527-1/2 6.1 22 30 strain

Absolute density g/cm! ISO 1183 1.14 1.14 1.15 of the powder MFI (230UC; g/10 min ISO 1133 jf8 9 249 2.16 kg)

Izod impact kJ/m2 ISO 180 2.18 4 2.4 notched (23°C)

Izod impact kJ/m2 ISO 180 18.9 35 87.8 unnotched (23°C)

From table 2 it is clear that with the polypropylene comprising the fly ash fraction as 5 claimed in the present invention it is possible to prepare plastic articles with properties which are comparable with other fillers which are commonly used in plastic materials, such as chalk and talc comprising fillers. 1

Claims

A plastic material comprising a plastic matrix and 1 to 70% by weight of an inorganic filler, wherein the filler comprises 50-100% fly ash particles with an average particle size of 1-50 pm.

Plastic material according to claim 1, wherein the fly ash particles have an average particle size of 1-30 µm, preferably 1-20 µm.

Plastic material according to any one of the preceding claims, wherein the plastic material comprises 5 to 80% by weight, preferably 10 to 75% by weight, most preferably 20-35% by weight or 60-75% by weight of the inorganic filler.

A plastic material according to any one of the preceding claims, wherein the inorganic filler comprises 70-100% fly ash particles, preferably 80-100% fly ash particles.

5. Plastic material according to any one of the preceding claims, wherein the fly ash particles have an absolute density of 2200 to 3000 kg / m3.

6. Plastic material as claimed in any of the foregoing claims, wherein the material comprises 20 to 50% by weight of the inorganic refuse and wherein the inorganic refuse comprises 80-100% by weight of fly ash particles, wherein the fly ash particles have an average particle size of 1-20 µm .

Plastic material according to any of the preceding claims, wherein the plastic matrix comprises thermoplastic polymers and / or thermosetting polymers. 30

A plastic material according to any one of the preceding claims, wherein the plastic matrix comprises polyolefins, preferably molecular polyolefins, such as polyethylene, polypropylene, polymethylpentene, polybutene.

9. Plastic material as claimed in any of the foregoing claims, wherein the plastic matrix comprises thermosetting polyolefins, preferably elastomeric polyolefins.

10. Plastic material according to one of the preceding claims, wherein the inorganic filler contains no more than 1% moisture by weight.

A method of manufacturing a plastic material according to any of the preceding claims, comprising the steps of: i) providing a thermoplastic or thermosetting base material; ii) mixing, on a total weight basis, of 1-70% by weight of an inorganic refiner with the plastic base material and allowing the obtained plastic material to cure, wherein the inorganic refiner comprises 50-100% by weight of fly ash particles with an average particle size from 1-50 pm.

The method of claim 11, wherein the thermoplastic base material is a polyolefin, such as polyethylene, polypropylene, polymethylpentene, polybutene. 20

A method according to any of claims 11-13, wherein the thermosetting base material is an alyd, diallyl phthalate, epoxy, melamine, phenol, polybutadiene, polyester, silicone and urea.

A method according to any of claims 11-13, wherein the thermoplastic or thermosetting base material is heated prior to mixing with the inorganic filler.

15. Method as claimed in any of the claims 1-14, wherein after step ii) the plastic material that is obtained is granulated into granulates with a largest diameter of 1 to 5 mm. Granules available with the method according to claim 15.

Use of a plastic material according to any of claims 1-10 or granules according to claim 16 in rotational molding or injection molding.

18. Use of fly ash with an average particle size of 1-50 µm as an inorganic refiner in plastic material.