EP2831165A2

EP2831165A2 - Composite and plastic body

Info

Publication number: EP2831165A2
Application number: EP13721417.7A
Authority: EP
Inventors: Theodorus Arnoldus BREUER; Hendrikus Johannes Theresia Maria MEEUSEN
Original assignee: Themaco Trading&Consultancy BV
Current assignee: Themaco Trading&Consultancy BV
Priority date: 2012-03-30
Filing date: 2013-03-29
Publication date: 2015-02-04
Also published as: WO2013147609A2; NL2008570C2; WO2013147609A3

Abstract

A composite for manufacturing a plastic body comprises a plastic base material and a filler of coconut shell powder (CSP) which has an average particle size of a maximum of 60 micron and is present in the composite in a quantity of 30-70% by weight. The composite is relatively environmentally-friendly due to the relatively large quantity of natural filler and displays improved material properties, certainly when applied as construction element.

Description

Composite and plastic body

The present invention relates to a composite comprising a plastic base material and a filler of coconut shell powder (CSP).

The use of a filler in a plastic base material is known in the prior art for thereby developing a new composite which has improved material properties compared to the plastic base material. An example of a suitable filler is the use of a natural filler. This provides the significant advantage that less plastic is required due to the use of the natural filler, and the resulting composite can therefore be utilized in ecologically more responsible manner. Known examples of natural fillers are limestone, glass and wood fibres. These known fillers have the drawback that the final composite is usually highly hygroscopic, has a reduced strength, hardness and flexibility, has a greatly increased density and withstands local force effects less well.

A known example of a natural filler having improved properties relative to these materials is coconut shell powder. The hard coconut shells have been, and still are, processed in the coconut industry mainly as organic waste. The alternative use of coconut shells ground to powder as filler in a composite is therefore useful and economically advantageous. Coconut shell powder has therefore already been applied for some time as filler in composite.

However, the options for processing thereof have until now been found limited and economically difficult to realize in respect of process engineering. Furthermore, the material properties of the known composites are not yet optimal, certainly not for determined specific applications.

The present invention therefore has for its object, among others, to provide a composite which obviates these drawbacks.

In order to achieve the stated object a composite of the type stated in the preamble has the feature according to the invention that the coconut shell powder has an average particle size of a maximum of 60 micron and is present in a quantity of 30-70% by weight. It has been found that the material properties of the composite depend particularly on an average particle size (median grain size) of the coconut shell powder as well as the quantity thereof in the final composite. At an average particle size up to a maximum of 60 micron the filler can still be processed, with a good mixing in the base material, in both single-screw and double-screw extrusion and injection moulding processes as well as in roto-moulding, and a body can thus be manufactured in practically simple manner from the composite. This moreover reacts exceptionally well with stabilizers and other additives such as melt flow index (MFI) or melt flow rate (MFR) optimizers which form an important factor in the processability of the composite.

The quantity of 30-70% by weight of the filler makes the composite significantly less hygroscopic and provides the composite with a good UV-resistance and an advantageously lower density, particularly compared to fillers of mineral nature. When there is a higher quantity of filler, breaking of the body of the composite is more likely to occur when force is applied, while with a lower quantity of filler there is a rapid decrease in the stiffness and strength of the composite. A preferred embodiment of a composite according to the present invention has the feature that the coconut shell powder has an average particle size greater than 50 micron. With an average particle size greater than 50 micron the final composite will certainly retain excellent mechanical properties, even after being reused a number of times, and it remains thermally stable up to a minimum of 210°C.

A suitable average particle size of the coconut shell powder does however depend on, among other factors, a wall thickness of a final product formed from the composite. If the composite is applied in a product with a wall thickness of less than an order of magnitude of 2-3 millimetres, the composite preferably comprises coconut shell powder with an average particle size of 10-40 micron. Owing to this relatively small average particle size in combination with the relatively high degree of filling of 30-70% by weight the product has a relatively high impact resistance. Products with a relatively thin wall of 2-3 millimetres or thinner can hereby be manufactured with a desired strength. When applied in a product with a greater wall thickness, the composite preferably comprises coconut shell powder with an average particle size of 40-60 micron.

Although a composite with improved material properties is already obtained by applying the filler with an average particle size and in a quantity as according to the above described invention, it has surprisingly been found that, for the best material properties for a desired application of the composite, there is a fine correlation between average particle size and quantity of filler. A composite according to the present invention is thus characterized in a particular embodiment in that a quantity of coconut shell powder present and an average particle size thereof are adapted to each other.

A composite according to the present invention is thus characterized in a preferred embodiment thereof in that the coconut shell powder has an average particle size of 60 micron and is present in a quantity of 70% by weight. The resulting composite not only comprises for the greater part the natural filler, so that it is relatively environmentally-friendly, but also displays optimized material properties such as a high strength and stiffness, greatly reduced hygroscopic properties, i.e. the composite absorbs substantially no moisture, fire-retardant properties and high insulating properties. A product manufactured from the composite also exhibits significantly reduced shrinkage following manufacture thereof, so that the composite is highly suitable for manufacture of objects of a specific and/or precise size and form.

Although the average particle size, or median grain size, of the coconut shell powder is the most important factor for the favourable properties of the composite, for further improved properties it is also important that the coconut shell powder has a substantially uniform grain size. The coconut shell powder is preferably thus produced from coconut shells such that it consists substantially, i.e. for more than 50%, of particles having a particle size varying by a maximum of 10 micron from the desired average particle size.

The composite according to the present invention can comprise as base material any polymer suitable for a desired application, but in a further preferred embodiment comprises a plastic base material chosen from a group comprising polyethylene, polypropylene, polyvinyl chloride, bakelite, polyamide, polystyrene, polyurethane, acrylonitrile butadiene styrene (ABS), styrene-butadiene rubber (SBR) and thermoplastic elastomer (TPE). These plastics are highly suitable for diverse applications and can be widely employed because of their properties.

Although the composite according to the present invention can consist wholly of the base material and filler, preferably with a weight ratio of 1 : 2, in a preferred embodiment the composite according to the present invention further comprises at least an additive. By applying a melt flow index (MFI) optimization additive the resulting composite can be processed with known production processes such as extrusion/vacuum forming, injection moulding and roto-moulding. A dye can for instance also be added to give the final composite a colour suitable for the desired application. The composite according to the present invention is suitable for diverse applications but, particularly because of its properties, can be readily used in outdoor products and automotive products or as construction element, and thus finds a good application as natural composite (wood plastic composite (WPC) plank, plate body, fencing part, garden shed part, furniture, door/window frames, doors or other construction parts. It will however be apparent that the composite is advantageous in all manner of plastic bodies, so that the present invention also relates to a plastic body comprising a composite according to the invention. A plastic body having a wall with a thickness greater than an order of magnitude of 2 to 3 mm particularly comprises a composite according to the invention with an average particle size of about 40-60 micron, and a plastic body having a wall with a thickness smaller than an order of magnitude of 2 to 3 mm comprises a composite according to the invention with an average particle size of about 10-40 micron.

The invention will now be further described hereinbelow on the basis of a number of exemplary embodiments.

E ample T

For the manufacture of a composite plate body with a wall thickness smaller than an order of magnitude of 2 to 3 millimetres, coconut shells are ground to a powder consisting of particles with an average grain size of about 10-40 micron. In order to optimize the coconut shell powder the powder is screened or filtered once or a number of times in order to filter out of the powder particles of greatly varying grain size, so that the powder consists substantially, i.e. for at least 50%, of particles with a grain size in a range of 20-35 micron. This fine powder of ground coconut shells is mixed as filler with a base material of acrylonitrile butadiene styrene (ABS) in order to manufacture a composite which imparts a high form- retention to the plate body and which displays exceptionally little shrinkage. The plate body can hereby be applied extremely well as automotive product, for instance for the manufacture of a vehicle bumper or other plate component of a vehicle, wherein accurate shapes and/or dimensions of the product are usually required. For a high impact resistance of the plate body the filler is applied in a quantity of 40% by weight in the composite. Owing to the relatively small average grain size of the powder the natural properties of the coconut shell particles become clearly manifest, so that for many applications the addition of additional additives is not necessary. Owing to the relatively small average grain size the filler can moreover be processed with good mixing into the base material, wherein single-screw and double-screw extrusion and injection moulding processes as well as roto-moulding can be applied. Example II

For the purpose of manufacturing a composite door/window frame with a wall thickness greater than an order of magnitude of 2 to 3 millimetres, coconut shells are ground to particles with an average grain size of about 40-60 micron. In order to optimize the coconut shell powder the powder is screened or filtered once or a number of times in order to filter out of the powder particles of greatly varying grain size, so that the powder consists substantially, i.e. for at least 50%, of particles with a grain size in a range of 45-55 micron. These particles of ground coconut shells are mixed as filler with a base material of polyvinyl chloride (PVC) in order to manufacture a lightweight composite which is wear-resistant and moreover has a favourable flexibility.

For a particularly high impact resistance the filler is applied in a quantity of 60% by weight in the composite. The hygroscopic properties of the material are hereby also low, so that a product manufactured from the composite does not absorb moisture, or hardly so. The relatively high degree of filling of the coconut shell particles in the composite also results in improved fire-retardant properties and makes the composite better UV-resistant. The lightweight composite is hereby highly suitable for the manufacture of for instance door/window frames. For further improved properties additional additives can optionally be further added to the composite. UV- tabilizers such as benzotriazoles can for instance thus be added so as to still further improve a light-resistance, and in particular UV-resistance, of the product. Other stabilizers such as non-toxic calcium or zinc salts can also be added in order to prevent decomposition of the composite during processing thereof. Dyes can further be added as desired in order to make the product aesthetically more attractive or better suitable.

Example III For the manufacture of a composite outdoor product, such as a fencing part or top liner or bed liner of a vehicle, with a wall thickness greater than 3 millimetres, coconut shells are ground to particles with an average grain size of about 60 micron. In order to optimize the coconut shell powder the powder is screened or filtered once or a number of times in order to filter out of the powder particles of greatly varying grain size, so that the powder consists substantially, i.e. for at least 50%, of particles with a grain size in a range of 55-65 micron. The particles are subsequently pretreated with a plastic coating product such as a polyethylene wax. These particles of ground coconut shells are mixed as filler with a base material of high-density polyethylene (HDPE). The filler is applied in a quantity of 70% by weight in the composite. The resulting composite has very minimal hygroscopic properties and so does not absorb moisture, or hardly so, this particularly enhancing the durability of an outdoor product such as a fencing part. In addition, this composite not only largely comprises the natural filler, so that it is relatively environmentally-friendly, but due to the specific adaptation of the quantity of filler in correlation with the average grain size, the composite also displays optimized material properties such as a high strength and stiffness, fire-retardant properties and high insulating properties.

Although the invention has been elucidated on the basis of only a number of exemplary embodiments, it will be apparent that the invention is by no means limited thereto. On the contrary, many variations and embodiments are still possible within the scope of the invention for a person with ordinary skill in the art.

Claims

1. Composite comprising a plastic base material and a filler of coconut shell powder (CSP), characterized in that the coconut shell powder has an average particle size of a maximum of 60 micron and is present in a quantity of 30-70% by weight.

2. Composite as claimed in claim 1, characterized in that the coconut shell powder has an average particle size greater than 50 micron.

3. Composite as claimed in claim 1 or 2, characterized in that a quantity of coconut shell powder present and an average particle size thereof are adapted to each other.

4. Composite as claimed in one or more of the foregoing claims, characterized in that the coconut shell powder has an average particle size of 60 micron and is present in a quantity of 60% by weight.

5. Composite as claimed in one or more of the foregoing claims, characterized in that the plastic base material is chosen from a group comprising polyethylene, polypropylene, polyvinyl chloride, bakelite, polyamide, polystyrene, polyurethane, acrylonitrile butadiene styrene (ABS), styrene-butadiene rubber (SBR) and thermoplastic elastomer (TPE).

6. Composite as claimed in one or more of the foregoing claims, characterized in that the filler is pretreated with a coating product, in particular a wax, which preferably comprises a material corresponding to the plastic base material.

7. Composite as claimed in one or more of the foregoing claims, further comprising an additive, such as for instance a stabilizer or dye.

8. Application of a composite as claimed in one or more of the foregoing claims in a construction element, in particular a plate body or plank body.

9. Plastic body, in particular a plate body or plank body, comprising a wall with a thickness greater than an order of magnitude of 2 to 3 mm of a composite as claimed in one or more of the claims 1 to 7 with an average particle size of about 40-60 micron.

10. Plastic body, in particular a plate body or plank body, comprising a wall with a thickness smaller than an order of magnitude of 2 to 3 mm of a composite as claimed in one or more of the claims 1 to 7 with an average particle size of about 10-40 micron.