Adhesive bonding and miscellaneous chemical manufacture – Methods – Surface bonding and/or assembly therefor
Patent
1996-04-19
1998-01-27
Gallagher, John J.
Adhesive bonding and miscellaneous chemical manufacture
Methods
Surface bonding and/or assembly therefor
524599, 528361, C09J 400
Patent
active
057118426
DESCRIPTION:
BRIEF SUMMARY
This application claims benefit of international application PCT/GB94/01496, filed Jul. 11, 1994.
THIS INVENTION relates to an adhesion process. More particularly it relates to a process of bonding articles together with an adhesive comprising a biodegradable polymer.
It is known to coat paper with polyhydroxyalkanoic acids (PHA), for example polymers of hydroxybutyric acid (PHB) and copolymers with hydroxyvaleric acid (PHBV) both as latex and as dry solid, preferably as dry powder. The coating is biodegradable but is non-adhesive.
We have now found that articles may be stuck together using PHA as an adhesive under cold application conditions and setting it with both articles in contact with one another under pressure and preferably with heat. The adhesive is biodegradable. The adhesive is believed to set by crystallisation.
Thus, according to the present invention there is provided a process of bonding two or more articles together using an adhesive composition comprising at least one polyhydroxyalkanoate (PHA) wherein the PHA is placed between the articles to be bonded and the articles are subjected to pressure to set the adhesive, optionally at elevated temperature.
The PHA is especially one capable of a relatively high level of crystallinity, for example over 30%, especially 50-90%, in the absence of plasticiser. Suitably it is or includes at least one microbiologically produced polyester having units of formula I: Typically C.sub.m H.sub.n contains 2-5 carbon atoms in the polymer chain and the remainder (if any) in a side chain. In very suitable polyesters n is 2 m and there are preferably units with m=3 and m=4 copolymerised together and with respectively a C.sub.1 and C.sub.2 side chain on the carbon next to oxygen in the chain. The polymer may be homopolymer, especially a polyhydroxybutyrate (PHB), or a copolymer, especially a copolymer of hydroxybutyric acid and hydroxyvaleric acid (HV) containing preferably 4-30 mol % of m=4 units. Thus, particular polyesters contain a preponderance of m=3 units, especially with 70-98 mol % of such units, the balance (if any) being units in which m=4. The molecular weight of the PHA is preferably over 50000, especially over 100000, up to e.g. 2.times.10.sup.6.
The PHA may be a blend of two or more copolymers differing in the value of m. A particular example contains
(a) PHA consisting essentially of Formula I units in which 2-5 mol % of units have m=4, the rest m=3; and
(b) PHA consisting essentially of Formula I units in which 5-30 mol % of units have m=4, the rest m=3.
In each such PHA there are preferably side chains as above mentioned. The proportions in such a blend are preferably such as give an average m=4 content in the range 4-30, more preferably 10-28, mol %.
In each such PHA having units with m=3 and m=4 there may be very small, typically fractional, percentages of units having higher values of m.
Typically the composition contains microbiologically produced PHA to the extent of over 50, especially over 80,% w/w.
The PHA is preferably a fermentation product, especially of a microbiological process in which a microorganism lays down PHA during normal growth or is caused to do so by cultivation in the absence of one or more nutrients necessary for cell multiplication. The microorganism may be wild or mutated or may have had the necessary genetic material introduced into it. Alternatively the necessary genetic material may be harboured by a eukariote, to effect the microbiological process.
Examples of suitable microbiological processes are the following:
for Formula I material with m=3 or m=partly 3, partly 4: EP-A-69497 (Alcaligenes eutrophus);
for Formula I material with m=3: U.S. Pat. No. 4,101,533 (A. eutrophus H-16), EP-A-144017 (A. latus);
for Formula I material with m=7-13: EP-A-0392687 (various Pseudomonas sp.).
The PHA can be extracted from the fermentation product cells by means of an organic solvent, or the cellular protein material may be decomposed leaving small granules of polymer for example of which less than 10% have diameters greater tha
REFERENCES:
patent: 5169889 (1992-12-01), Kauffman et al.
Gallagher John J.
Zeneca Limited
LandOfFree
Adhesion process does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Adhesion process, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Adhesion process will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-338963