Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Patent
1983-08-08
1985-12-17
Kight, John
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
524 15, 524 16, 524 76, 524 78, C08L 102, C08J 320, C08J 510
Patent
active
045593760
DESCRIPTION:
BRIEF SUMMARY
The focus on energy has had a significant impact on the growth of interest for fillers and extenders for plastic materials. It is known that such additives may influence the property profile of the final product or, in certain cases, act as pure extenders allowing a more efficient use of the plastic component. There are also instances where the filler may have a marked reinforcing effect.
Among the many types of fillers and similar additives, cellulose and various kinds of lignocellulosic materials take an important place. Especially interesting is the increasing use of such fillers in thermoplastics. Cellulose fibre, cellulose flour, wood flour, and nut shell flour are a few examples of additives to be discussed in the present context.
When the lignocellulosic or cellulose based material is used as powder or flour, it has to be ground prior to the compounding step. When used as fibres, such materials experience a certain grinding action in the plastics processing machinery, but, this effect is, however, of little practical significance. Fibrous additives/fillers of the above mentioned type are normally expected to possess a certain reinforcing effect reminiscent of that obtained with glass fibres or other similar reinforcement.
When using additives (fillers, reinforcements) of the present type difficulties are normally encountered in achieving a sufficient degree of dispersion during the compounding and processing steps, especially when the additive is fibrous. An acceptable dispersion is normally obtained only with finely ground material. When trying to achieve an acceptable dispersion with fibrous matter, the mixture has to be subjected to such an intense and repeated kneading action during the compounding stage, that the time and energy consumed in that stage make such an approach prohibitive.
Such an energy consuming comminution of the cellulosic or lignocellulosic additive in the compounding step, for instance by repeated treatment in a kneader, fulfills no proper technical task, as it could have been done easier by grinding the filler prior to compounding. On the other hand, it is believed that an excessive comminution of the fibrous filler should be avoided, on the assumption that the reinforcing action would be lost.
When investigating the effect of cellulosic and lignocellulosic fillers on the property profile of thermoplastic composites, we have surprisingly found that the particle size of the filler/reinforcing agent plays a minor role only, implying that the reinforcing effect of such fillers, when present in fibrous form, is not more pronounced than that of finely divided particulate matter. This finding has an important practical implication, as it justifies the use of finely divided fillers which are easy to disperse in the plastic matrix.
The aim of the present invention is the use of easily disintegrable pre-hydrolysed cellulosic or lignocellulosic material as additive to plastics, preferably thermoplastics. It is known that a pre-hydrolysis of such materials results in a substantial embrittlement. This embrittlement is utilized in the present invention in the compounding stage, where the pre-hydrolyzed material is added to the plastic component without prior grinding or other comminution. The comminution to the final particle size takes place in the compounding machine or, directly, in the processing machine as an effect of the shear forces prevailing in such machines (kneaders, extruders, injection moulding machines, film blowing equipment etc.). The pre-hydrolysis of the additive thus eliminates the necessity of the normal time and energy consuming mechanical comminution prior to the compounding step.
It is understood that the additive has a suitable particle size before being subjected to the hydrolytic embrittlement. To illustrate this point, we may refer to our experiments where normal wood flour, particle size 0.1-0.5 mm, or about 2.times.2 cm large pieces of cellulose pulp sheets have undergone hydrolytic degradation, whereafter they were directly fed into the compounding equipmen
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Chemical Abstracts, Col. 72 (1970), abstract No. 134357s, Vanina V. I, Zakoshchikov A P (Mosk. Tekhnol. Inst. Moscow, USSR).
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Derwent's abstract, No. 30579 C/17, SU 681 081.
Klason Tore C. F.
Kubat Josef
Kight John
Nutter Nathan M.
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