Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymers from only ethylenic monomers or processes of...
Reexamination Certificate
2001-12-17
2003-02-04
Pezzuto, Helen L. (Department: 1713)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Polymers from only ethylenic monomers or processes of...
C526S266000, C526S269000, C526S270000, C526S271000, C526S314000, C526S318200, C526S318430, C526S319000, C526S325000, C526S330000
Reexamination Certificate
active
06515092
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention is broadly concerned with novel anionic substantially biodegradable and substantially water soluble polymers and derivatives thereof which have significant utility in agricultural applications, especially plant nutrition and related areas. More particularly, the invention is concerned with such polymers, as well as methods of synthesis and use thereof, wherein the preferred polymers have significant levels of anionic groups. Additionally, the preferred polymers also include significant levels of alcohol groups. The most preferred polymers of the instant invention include recurring polymeric subunits made up of vinylic (e.g., vinyl acetate or vinyl alcohol) and dicarboxylic (e.g., maleic acid, itaconic acid, anhydrides, and other derivatives thereof) moieties. The polymers may be complexed onto ions and/or mixed with or coated with phosphate-based fertilizers to provide improved plant nutrition products.
2. Description of the Prior Art
Lignosulfonates, polyacrylates, polyaspartates and related compounds have become known to the art of agriculture as materials that facilitate nutrient absorption. All of them suffer from significant disadvantages, which decrease their utility in comparison to the art discussed herein and limit performance.
Lignosulfonates are a byproduct of paper pulping; they are derived from highly variable sources. They are subject to large, unpredictable variations in color, physical properties, and performance in application areas of interest for this invention.
Polyacrylates and polymers containing appreciable levels thereof can be prepared with good control over their composition and performance. They are stable to pH variations. However, polyacrylates have just one carboxylate per repeat unit and they suffer from a very significant limitation in use, namely that they are not biodegradable. As a result, their utility for addressing the problems remedied by the instant invention is low.
Polyaspartates are biodegradable, but are very expensive, and are not stable outside a relatively small pH range of about 7 to about 10. They usually have very high color, and incorporate amide groups, which causes difficulties in formulating them. Additionally, polyaspartates have just one carboxylate per repeat unit and are therefore not a part of the present invention.
Russian Journal of Applied Chemistry,
24(5):485-489 (1951) teaches the preparation of maleic anhydride-vinyl acetate copolymers in benzene and acetone with benzoyl peroxide initiators. It further discloses the addition of above copolymers to water, wherein the polymer gradually self-hydrolyzes to a complex mixture containing units of maleic acid, vinyl alcohol, vinyl acetate, lactones, free acetic acid, and other species. Deficiencies of this teaching include undesirable presence of lactone, which decreases number of dicarboxylic groups. In addition, no use for polymers is taught or suggested.
U.S. Pat. Nos. 3,268,491 and 3,887,480 teach preparation of maleic acid-vinyl acetate copolymers in water-based solutions using redox-based initiators in a certain pH range. The approaches described in these patents are highly problematic. Only redox-type initiators are claimed to be useful. A fixed pH range restricts the practice. Only a narrow range of copolymers composed exclusively from the monomers of maleic acid and vinyl acetate are taught. The process of U.S. Pat. No. 3,268,491 is deemed to be non-commercial by U.S. Pat. No. 3,887,480 which described improved processes but uses over 17% by weight of redox initiator; such processes are very wasteful, have high environmental impact, and are not cost effective.
U.S. Pat. Nos. 5,191,048 and 5,264,510 teach copolymerization of acrylic acid, maleic acid, and vinyl acetate with subsequent hydrolysis by base. Again, several important deficiencies are evident. Among these are the exclusive use of base hydrolysis and preferred embodiments of invention incorporating monocarboxylic acids. Only terpolymers are disclosed. Furthermore, the intended uses of the compositions are very restricted and in no way teach, suggest or imply utility of the enumerated and contemplated compositions for the purposes of the present invention.
It will thus be seen that the prior art fails to disclose or provide polymers which can be synthesized using a variety of monomers and techniques in order to yield end products which are substantially biodegradable, substantially water soluble, and have wide applicability for agricultural uses.
SUMMARY OF THE INVENTION
The present invention overcomes the problems outlined above and provides a new class of anionic polymers having a variety of uses, e.g., for enhancing takeup of nutrient by plants or for mixture with conventional phosphate-based fertilizers to provide an improved fertilizer product. Advantageously, the polymers are biodegradable, in that they degrade to environmentally innocuous compounds within a relatively short time (up to about 1 year) after being in intimate contact with soil. That is to say that the degradation products are compounds such as CO
2
and H
2
O or the degradation products are absorbed as food or nutrients by soil microorganisms and plants. Similarly, derivatives of the polymers and/or salts of the polymers (e.g. ammonium salt forms of the polymer) also degrade within a relatively short time, during which significant fractions of the weight of the polymer are believed to be metabolized by soil organisms.
Broadly speaking, the anionic polymers of the invention include recurring polymeric subunits made up of at least two different moieties individually and respectively taken from the group consisting of what have been denominated for ease of reference as A, B and C moieties. Thus, exemplary polymeric subunits may be AB, BA, AC, CA, ABC, BAC, CAB, or any other combination of A moieties with B and C moieties. Moreover, in a given polymer different polymeric subunits may include different types or forms of moieties, e.g., in an AB recurring polymeric unit polymer, the B moiety may be different in different units.
In detail, moiety A is of the general formula
moiety B is of the general formula
and moiety C is of the general formula
wherein R
1
, R
2
and R
7
are individually and respectively selected from the group consisting of H, OH, C
1
-C
30
straight, branched chain and cyclic alkyl or aryl groups, C
1
-C
30
straight, branched chain and cyclic alkyl or aryl C
1
-C
30
based ester groups (formate (C
0
), acetate (C
1
), propionate (C
2
), butyrate (C
3
), etc. up to C
30
), R′CO
2
groups, and OR′ groups, wherein R′ is selected from the group consisting of C
1
-C
30
straight, branched chain and cyclic alkyl or aryl groups; R
3
and R
4
are individually and respectively selected from the group consisting of H, C
1
-C
30
straight, branched chain and cyclic alkyl or aryl groups; R
5
, R
6
, R
10
and R
11
are individually and respectively selected from the group consisting of H, the alkali metals, NH
4
and the C
1
-C
4
alkyl ammonium groups, Y is selected from the group consisting of Fe, Mn, Mg, Zn, Cu, Ni, V, Cr, Si, B, Co, Mo, and Ca; R
8
and R
9
are individually and respectively selected from the group consisting of nothing (i.e., the groups are non-existent), CH
2
, C
2
H
4
, and C
3
H
6
, at least one of said R
1
, R
2
, R
3
and R
4
is OH where said polymeric subunits are made up of A and B moieties, at least one of said R
1
, R
2
and R
7
is OH where said polymeric subunits are made up of A and C moieties, and at least one of said R
1
, R
2
, R
3
, R
4
and R
7
is OH where said polymeric subunits are made up of A, B and C moieties.
As can be appreciated, the polymers of the invention can have different sequences of recurring polymeric subunits as defined above (for example, a polymer comprising A, B and C subunits may include the one form of A moiety, all three forms of B moiety and all three forms of C moiety). In the case of the polymer made up of A and B moieties, R
1
-R
4
are respectively and individual
Kimmerly James Michael
Mazo Grigory
Sanders John Larry
Hovey & Williams, LLP
Pezzuto Helen L.
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