Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Reexamination Certificate
1999-08-17
2001-06-19
Michl, Paul R. (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
Reexamination Certificate
active
06248812
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a method of preparing a starting material for the subsequent manufacture of a finished product, from a feedstock comprising substantially dry finely divided lignocellulosic fibres, or exfoliated vermiculite particles, or expanded perlite particles, and to a process of preparing a finished product therefrom.
Lignocellulosic composite board products, either in flat or shaped form, manufactured from chips, particles, fibres, veneers, flakes or strands of natural fibrous plant materials such as agri fibres or wood, are well known and are currently made by a number of different methods. Such products are commonly bound by formaldehyde condensation resins such as the ureas, melamines and phenolics, or the polyureas or isocyanates. Despite the success of such lignocellulosic composite board products, there is always a need for new types of products, and in particular for products made from new types of feed material.
The material rejected in the mechanical cleaning of recovered paper is probably in the region of ten million tons globally based on 1995 figures and a 91% yield. The recycling of paper waste is rapidly falling behind demand for waste disposal. There is clearly a need for the utilisation of these materials but process difficulties have arisen. One is the presence of minerals in these materials, accounting for as high a proportion as 50% of the sludges and another is the difficulty in processing to make good quality products.
The present invention seeks to utilise the sludges, as well as other feedstocks such as medium density fibre, for the production of useful products.
SUMMARY OF THE INVENTION
According to a first aspect of the invention there is provided a method of preparing a starting material for the subsequent manufacture of a finished product, from a feedstock selected from the group consisting of a lignocellulosic material, exfoliated vermiculite, or expanded perlite, or a mixture of two or three thereof, which method includes the steps of:
(1) providing the feedstock in the form of substantially dry finely divided lignocellulosic fibres or substantially dry finely divided exfoliated vermiculite particles or substantially dry finely divided expanded perlite particles, or a mixture of two or three thereof; and
(2) mixing the feedstock with:
(a) a suitable amount of a thermosetting resin in finely divided dry powder form, and
(b) a suitable amount of a hydraulic binder in finely divided dry powder form;
to give the starting material.
The method preferably includes the step of:
(3) subjecting the starting material of step (2) to suitable conditions of temperature and pressure to cause the thermosetting resin to set to form a cohesive product.
According to a second aspect of the invention there is provided a process of preparing a finished product from a cohesive product produced by the method described above, which process includes the step of:
(A) providing to the cohesive product, water in an amount sufficient for the hydration of the hydraulic binder so that the hydraulic binder sets to form the finished product.
By “finely divided lignocellulosic fibres” there is meant unifibres or bundles of a small number of unifibres of a lignocellulosic material. In other words, the lignocellulosic material is broken down into single fibres or bundles of a small number of fibres, rather than being in chip or particle form. The fibres have a length of from 0.5 mm to 12 mm inclusive, preferably from 1 mm to 6 mm inclusive.
By “finely divided exfoliated vermiculite particles” there is meant exfoliated vermiculite in micron (0.5 mm and smaller), superfine (1 mm and smaller), fine (2 mm and smaller), medium (4 mm and smaller) and large (8 mm and smaller) particle size.
By “finely divided expanded perlite particles” there is meant expanded perlite or volcanic glass in particle sizes of from 5 microns to 2000 microns diameter inclusive.
The lignocellulosic feedstock may already be in finely divided fibrous form.
However, in step (1) the lignocellulosic feedstock may be prepared from pellets or chips of a suitable material, by milling or abrading or the like. In this case step (1) may precede or follow step (2).
The thermosetting resin is preferably a novolac phenol formaldehyde resin with a suitable catalyst.
The thermosetting resin is preferably used in an amount of 2% to 20% inclusive of the thermosetting resin by mass of the hydraulic binder, i.e the mass ratio of the thermosetting resin to the hydraulic binder is from 2:100 to 20:100.
The hydraulic binder is a substance which hydrates and sets in combination with water. The hydraulic binder is preferably selected from the group consisting of Portland Cement, high alumina cement, gypsum cement, calcium sulphate hemihydrate in either the alpha or beta form, magnesium oxychloride, magnesium oxysulphate, a calcium sulphoaluminate cement, an alkali silicate, and ground granulated blast furnace slag, and a mixture of any two or more of these binders.
The hydraulic binder is preferably used in an amount of 50% to 2000% inclusive of the hydraulic binder by mass of the feedstock, i.e the mass ratio of the hydraulic binder to the feedstock is from 1:2 to 20:1, preferably in a mass ratio of 10:1 to 5:1 for finished products with high densities, and preferably in a mass ratio of 5:1 to 1:1 for finished products with low densities.
In addition to components (a) and (b), the feedstock may be mixed with:
(c) a suitable amount of a thermoplastic resin in finely divided particulate or fibrous form.
Further, in addition to components (a), (b) and optionally (c), the feedstock may be mixed with:
(d) a suitable amount of a filler material selected from inorganic or mineral fibres, inorganic particles, synthetic fibres, and mixtures of two or more thereof.
In step (A) of the process, the water required for hydration of the hydraulic binder may be introduced into the cohesive product from an external source, for example as steam, or may be provided by one or more of the components of the cohesive product, from which water is released, for example on heating.
DESCRIPTION OF EMBODIMENTS
The crux of the invention is that a feedstock, being substantially dry finely divided lignocellulosic fibres, or substantially dry finely divided exfoliated vermiculite or expanded perlite particles, or a mixture of two or three thereof, is mixed with a thermosetting resin in finely divided dry powder form and with a hydraulic binder in finely divided dry powder form to give a starting material. Thereafter this starting material is subjected to suitable conditions of temperature and pressure to cause the thermosetting resin to set to form a cohesive product.
The provision of the feedstock in a finely divided fibrous or particulate form is important to prevent particle separation in the formation of the starting material and subsequently the cohesive product. A key feature of the cohesive product is that it may be formed from dry components that do not separate from one another during formation of the cohesive product.
The feedstock may be lignocellulosic fibres.
A preferred lignocellulosic fibrous material is paper mill sludge, waste paper or medium density fibre.
Paper mill sludge is a dewatered effluent of paper manufacture or recycling.
A typical makeup of a paper mill sludge is a pH of 8.13, and a fibre percentage of 14.4. An analysis of the sludge, utilising qualitative X-ray emission scans, reveals a composition as follows: Ca 18%; K 0.23%; Cl 0.2%; P 0.15%; S 0.12%; Si 4.4%; Al 3%; Mg 0.8%; Na 0.17%; C 68% and Fe 1.7%.
The hydrocarbon content as determined by the burn off method of the sludge is as follows:
INORGANIC ANALYSIS
% LOI at 600° C. (indicative of total organics)
79,10
% Ash at 900° C.
20,74
LOI = loss on ignition
% Ash
% Sample
(m/m)
(m/m)
Calcium as CaO
8,28
1,72
Aluminium as Al
2
O
3
13,57
2,81
Magnesium as MgO
0,41
0,09
Iron as Fe
2
O
3
0,43
0,09
Phosphates as PO
4
3−
NDetected
ND (zero)
Sulphates as SO
4
2−
24,00
4,98
Acid insolubles
52,02
10,65
ORGA
Michl Paul R.
Pillsbury & Winthrop LLP
Windsor Technologies Limited
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