Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From ketone or ketene reactant
Patent
1991-01-31
1992-08-18
Acquah, Samuel A.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From ketone or ketene reactant
528229, 528272, 528288, 528302, 528324, 528332, 528335, 428364, C08G 6902
Patent
active
051400952
DESCRIPTION:
BRIEF SUMMARY
This invention relates to a biodegradable polyamide containing keto carbonyl groups, to the process for its preparation as well as to films and other products obtained from said polyamide.
The polyamides according to this invention are meant to be both aliphatic and aromatic polyamides and copolyamides, preferably nylon 6 and 6,6.
In particular, the scope of this invention relates to copolymers being sensitive to the solar U.V. radiation, which involves their transformation into a fragile or friable product, so to prevent the pollution caused by the permanence of products such as bags for example, that have an extremely long life and, consequently, cause a deterioration of the environment in which they are left.
The pollution caused by bags made of plastic material and, in particular, of polyamide material, is well-known, and methods have been suggested in order to solve this problem. For example, it is possible to mix fillers, in the polymer mass, in order to make it biodegradable; such fillers can be, for example, cellulose, flour, etc. However, in practice, it occurred that the product so obtained, especially as film, has an opaque appearance and is not perfectly transparent, and beside this the same mechanical properties of said polymer decrease dramatically, even when the polymer is not exposed to sunlight.
Moreover, the Canadian Patent N.sup.. 975491 claims a photodegradable polyamide composition, containing keto carbonyl groups located in a side chain at a position immediately adjacent to the main polymeric chain; said polymeric chain having monomeric units of the structure (II) ##STR1## wherein m and n are whole numbers from 1 to 6, R is an alkyl, aryl or alkenyl groups having 1 to 12 carbon atoms and R' is H or an alkyl groups having 1 to 6 carbon atoms.
In practice, however, it occurred that these polyamides, made virtually only on a laboratory scale, are extremely difficult to synthesize through the usual industrial processes applicable to polyamides, as they require high (200.degree.-300.degree. C.) reaction temperatures in the absence of solvents and thus said known polyamides tend to degrade easily under such industrial conditions.
Furthermore, said known polyamides are less sensitive to the solar U.V. radiation so that their photodegradation takes place quite slowly.
Therefore, one of the objects of this invention is to make a polyamide being highly sensitive to solar U.V. radiation and having, at the same time, high mechanical and structural properties.
Another object of this invention is a process to obtain a biodegradable polyamide that is sensitive to solar U.V. radiation and, therefore, is transformable into a fragile or friable product, without requiring very long exposures.
A further object of the invention is to obtain a polyamide being photodegradable to the exposure of solar U.V. light, that is also biodegradable, or in other words that it is able to be attacked by the bacteria existing in nature in order to obtain the complete degradation even of the smallest particles resulting from the photodegradation. This is particularly important, as the mere photodegradation determines fragility or friability and, consequently, the decay of the product, such as the film for example, into very small pieces, which, if they would not be able to be biologically attached by bacteria, they would in any case cause pollution.
These and other objects of the invention are achieved by the polyamide according to the invention which is characterized in that it contains keto carbonyl groups set out along the main polymer chain, in monomeric units having the structure (i) ##STR2## wherein n and m are equal or different whole numbers ranging from 8 to 10, said keto carbonyl groups being enough to cause an accelerated photodegradation of said polyamide, so to produce, after the exposure to the solar U.V. radiation, a fragile or friable and biodegradable product, while keeping high mechanical properties before said exposure to the sunlight.
Preferably n and m are equal to 8.
Moreover, the polyamide according
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Guaita Cesare
Semeghini Gianluigi
Acquah Samuel A.
SNIA Tecnopolimeri S.p.A.
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