CA2109618A1 - Degradable cellulose polymers - Google Patents
Degradable cellulose polymersInfo
- Publication number
- CA2109618A1 CA2109618A1 CA 2109618 CA2109618A CA2109618A1 CA 2109618 A1 CA2109618 A1 CA 2109618A1 CA 2109618 CA2109618 CA 2109618 CA 2109618 A CA2109618 A CA 2109618A CA 2109618 A1 CA2109618 A1 CA 2109618A1
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- Canada
- Prior art keywords
- acid
- accordance
- composition
- cellulose
- lactone
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Classifications
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
- C08K5/00—Use of organic ingredients
- C08K5/04—Oxygen-containing compounds
- C08K5/15—Heterocyclic compounds having oxygen in the ring
Abstract
The present invention is directed to a thermoplastic cellulose ester polymer composition having improved degradation properties upon exposure to moisture. The composition includes a cellulose ester and a degradation promoter. The degradation promoter, after formation of the polymer composition into an end-product and in the presence of moisture, is water soluble and leachable from the polymer end-product or in the presence of moisture, hydrolyzes to form water soluble by-products which are leachable from the polymer end-product. The degradation promoter also acts as a catalyst to enhance the hydrolysis of the cellulose acetate, resulting in a mixture of cellulose and acetic acid. The cellulose can then depolymerize into saccharides that are more biodegradable. The degradation promoter can also act as a plasticizer for the cellulose ester polymer or can be used in combination with other known plasticizers.
Description
wo 92/20~38 Pc~r/us92/04243 -1- 2 1 0 9 6 1 ~
DEGRADABLE CELLULOSE PQLD~
Fl~ld of ~he In~en¢ion The present invention is directed to a cellulose ester composidon which may be used to form thermoplastic polymeric materials having improved degradation S properties upon exposure to moisture. The compositions include at least onedegradation promoter that will leach from the polymeric materials in the presence of moisture after disposal of the polymeric composition in the envir~nment. In one embodiment, the present invention is directed to a thermoplastic cellulose acetate polymer composition having improved degradation properties upDn exposure to moisture which includes cellulose acetate, a plasticizer for the cellulose acetate and a hydrophilic degradation promoter.
I~ack~round of the Invention The disposal of modern packaging resins, such as polyethylene, polypropylene, polyvinyl chlodde and polystyrene is becoming an increasingly seAous problem. Accordingly, significant technical effort has been expended to produce polymeric compositions which are biodegradable. Representative patents directed to producing biodegradable polymers are U.S. Patent No. 3,950,282 to Gilbert, et al., U.S. Patent No. 4,048,410 to Taylor, et al., U.S. Patent No. 4,038,228 to Taylor, U.S. Patent No. 4,051,306 to Tobias, et a}., U.S. Patent No. 4,056,499 to Taylor and '20 U.S. Patent No. 3,907,726 to Tomiyana, all of which are related to methods or compositions for producing degradable polymeric materials.
Some of the first polymers developed for commercial use were based on cellulose. These inçluded regenerated cellulose (rayon) and various cellulose este~s, such as ceiluiose acetate, cellulose butyrate, cellulose propionate and mixed esters of cellulose (acetate, acetate butyrate and acetate propionate).
Regenerated cellulose materials, such as cellophane and rayon, are environmentally degradable at a very slow rate. However, to provi~e cellulose esters in the form of a melt extmded film, a high levd of plasticizer is required. Suchplasticizer is used to provide cellulose ester compositions which can be formed into wo 92/20738 Pcr/us92/042-3 a thermoplastic film by melt-fabrication methods. Cellulose acetate in its pure form is not a thermoplastic when melt-fabricated by methods such as extrusion. The use of such high levels of plasticizer produced plastic materials which are highly stable and which do not degrade when expo~ed to the envir~nment, even in highly moist 5 conditions. The wide variety of soil and microorganisms which are known to have the ability to enzymatically hydrolyze cellulose and pure cellulose esters to soluble intermediates do not react with oellulose esters which are highly plasticized.
Nevertheless, films and flexible sheet plastic packaging materials produced fromcellulose esters, such as cellulose acetate, are highly desirable in that cellulose acetate 10 is potendally one of the least e~pensive plasdc films to produce. It would be highly desirable to provide a cellulose ester packaging material whicb can be degraded by exposure to normal ambient environmental condidons. As used herein, the term "normal ambient environmental condidon" is meant to include those conditions which prevail during the disposal of most waste materials, such as in a landfill or waste 15 dump.
Accordingly, it is tbe principal object of the present invendon to provide cellulose ester composidons which are degradable by exposure to moisture in a normal ambient environment.
- Summary of ~h ~n~ntion The present invendon is directed to a thermoplastic cellulose ester polymer composidon having improved degradation properties upon exposure to moisture. The composition includes a cellulose ester and a degradation promoter.The degradatdon promoter, after formation of the polymer composidon into an end-product and in the presence of moisture, is water soluble and leachable from thcpolymer cnd-product or in the presence of moisture, hydrolyzes to form water soluble by-products which are leachable from the polymer end-product. The degradation promoter also acts as a catalyst to enhance the hydrolysis of the cellulose acetate, resulting in a mi~ture of cellulose and acedc acid. The cellulose can then depolymerize into saccharides that are more biodegradable. The degradation promoter W O 92/2~738 P~r/US92/04243 ~ -3~ 2109~1~
can act as a plasticizer for the cellulose ester polymer or can be used in combination with other known plastici~ers.
et~iled Description ofthe Inventio~
Cellulose is a polysaccharide formed from anhydroglucose units. ~ch S of the anhydroglucose units contains three fr~e hydroxyl groups which can be reacted to form esters. The extent to which substitution of an acid takes place is Icnown as the degree of substitution and is expressed as the average number of hydroxyl groups, of the three av~ulable in the anhydroglu~ose unit, that have been replaced. Cellulose esters useful in the present invention have a degree of subs~tution of from about 2.0 to about 2.6. Exp~essed in other terms, the cellulose acetates useful in the present invendon have an ester content of from about 39% to about 42.5% on an acety}
equivalent basis. In the pr~aration of cellulose esters b~ving substitutions appreciably below 3, i.e., in the range of 2.0 to 2.6, it has not been possiUe to malce products of good uniformity by esterifying directly to the desired substitution. This is because of lS the topochemical character of the reaction. EsteAfication proceeds inwardly from the outer surface of the cellulose fiber and uniformity is poor until the product has completely dissolved in the esterification mixture. Such complete dissolu~on occurs close to the triester stage. In order to prepare uniform products of substitution 2.~
~.6, it is necessary to make the triester and hydrolyze the triester in soludon to the desired degree of substitution.
Accordingly, early use of cellulose esters utilized the triester fonnulation.
Cellulose triesters, however, are difficult to mold and many early efforts were directed at methods and compositions for improving the molding capability of cellulose triesters. U.S. Patent 2,067,310 to Auden, for example, discloses a pr~ess of ....
making molded articles that can use molding temperatures as low as 120 C. to 180 C. and mnlding pressures of 2,000 to 3,000 psi, which are lower than the usual molding temperatures and pr,essures for cellulose tnacetate. The process of the Auden patent consists in mixing cellulose triacetate and a mate~ial taken from group consisdng of lactides, and the anhydrides of maleic, succinic and phthalic acids. The WO 92/20738 PCI`/US92/04243 ;''~ 4-addition of the lactides and the anhydrides in combination with the use of plasticizers produced a moldable cellulose triacetate composition.
U.S. Patent No. 2,805,171 to Williams, also discloses a method for providing a moldable composition of cellulose triacetate. As discussed in the Williams S patent, cellulose tri~cetate having an acetyl content of 52.5% to 53.5% (figured as percent acetic acid) are acetone insoluble cellulose esters. The cellulose esters useful in the present invention, having an acetyl content of from between about 39% andabout 42.5%, are characterized in the Williams patent as being acetone soluble.
The degradable thermoplastic cellulose ester compositions of the present 10 invention are mixtures of a cel!ulose ester having an ester content, on an acetyl basis, of from between about 39% and about 42.S% and a degree of substitution of from about 2.0 to about 2.6, a plasticizer and a degradation promoter. While not wishing to bc bound by any theory, it is believed that thc degradablc functionality of the compositions of the invention are at least par~ally attributable to access by water to 15 thc polymer and hydrolysis of the polymer at the pendant acetyl groups and at the acetal linkages.
The degaation promoters of the present invention are hydrophilic materials. The degradation promoters are cyclic internal monoesters, cyclic internal double esters and oligomers of such acids having from 2 to S0 acid moieties. The20 monoesters have a single oxygen molecule in the ring and can be prepared from any of the hydroxy acids except the ~-hydroxy acids. Monoester lactones useful as degradation promoters in the present invention are usuaUy prepared from hydroxy acids. The cyclic double esters can be prepared from a-hydroxy acids. Cyclic internal esters are generally referred to as lactones. The cyclic double ~membered 25 esters are sometimes referred to as dioxanediones.
While the cyclic internal esters of the invention can be prepared from suitable hydroxy acids, other chemical pathways for their prepara~on are available.
The y- and ~lactones arc commonly prepared by dther hydrolysis or disdllation ofr or ~halo acids, by treatment of unsaturated acids with aqueous hydrobromic or 30 sulfuric acids, or by panial reducdon of cyclic acid anhydrides. B-Lactones result wo 92/20738 PCr/USs2/04243 -5- ~lO~lX
from the reaction of a ketene with aldehydes or ketones. The reac~ion of ketene with formaldehyde is shown below.
H2C=C=0 + C ~ H2C C--O
I
Large-ring lactones can be made by oxidation of cyclic ketones with Caro's acid; thus, cyclohexanone yields ~ caprolactone~ Some lactones are prepared from ehe reaction S of a dicarboxylic acid wi~ a polyhydric alcohol, such as lhe reaction of malonic acid with ethylene glycol.
Suitable hydroxy acids and dicarboxylic acids for preparation of the lactones useful as degradation promoters of the present invention include 3-hydroxypropionic acid, 2-hydroxy, 1,2,3 propanetricarboxylic acid (citric acid), 3-1~ hydroxybutyric acid, 4-hydroxybutyric aeid, 4-hydroxy-valeric acid, 5-hydroxyvaleric acid, ~hydroxycaproic acid, 2-hydroxyacetic acid (glycolic acid), 2-hydroxy-propionic acid (lactic acid), 2 hydroxybutyric acid, 2-hydroxyvaleric acid, 2-hydroxycaproic acid, 2-hydroxy-hept~noic acid, 2-hydroxyoctanoic acid, 2-hydroxy-pelargonic acid, 2-hydroxyphenylacetic acid, l-hydroxy-cyclohexane l-carboxylic acid, oxalic acid plus 'lS ethylene glycol, oxalic acid plus propylene glycol, malonic acid plus ethylene glycol, and malonic acid plus propylene glycol.
In gen~al, the lactones useful in the present invention have from 3 to 6 calbon atoms and 1 or 2 oxygen atoms in the ring. The lactones produced from thehydroxy acids will have structures corresponding to the following formulae:
w o 92J2~738 Pc~r/us92/042~3 2lo!36l8 ~ ~ R~ R5 (1) (2~ (3) R2~o ~ 3 (4) (~) (6) R2--~ \
(7) whe~on any R can be hydkogen, Cl-CIO alkyl, or an alyl gnoup ~ect~d from benzene~ nap~ene,benzenesubsdtu~ed ~n~h Cl-C4 aLkyl and nap~enesubsdtut~d ~h Cl-C4 aLkyl.
WO 92/20738 PCI /US~2/04243 -7- i 210~!~18 For formulation 1, Rl and R2 are H when 3-hyd~oxypropionic acid is used to produce propiolactone; R~ is H and R2 is methyl when 3-hydro~ybuqric acid is used to produce butyrolactone; R~ is methyl and R2 is methyl when 3-hydroxyisobutyric acid is used to produce 2,3-dimethyl propiolactone; Rl is phenyl 5and R2 is H when 3-hydroxy 3-phenyl is used to produce 3-phenyl propio-lactone and Rl is H and R2 is phenyl when 3-hydroxy, 2-phenyl is used to produce 2-phenyl propiolactone.
For formulation 2, R1, R2 and R3 are H when 4-hydroxybuqric acid is used to produce valerolactone and Rl is methyl, R2 is H and R3 is H when 4-10hydroxyvaleric acid is used to produce 4-methyl vale~olactone.
For formulation 3, Rl through Rs are H when 6-hydroxycaproic acid is used to produce ~-caprolactone and Rl is methyl, R2-RS are H, when hydro~cyheptylic acid is used to produce ~methyl-caprolactone.
For forrltuladon 4, Rl-R4 are H when glycolic acid is used to produce 15glycolide; Rt and R3 are methyl, R2 and R4 are H when lacdc acid is used to produce lactide; Rt and R3 are phenyl, R2 and R4 are H when phenyl-2 hydroacetic acid isused to produce 2,5-diphenyl-dioxane-3,6-dione and Rl and R3 are hexyl, R2 and R4 are H, when 2-hydroxyoctanoic acid is used to produce 2,5-dihexyldioxane-3,~dione.
Por formulation S, Rl and R2 are H, when oxalic acid and ethylene 20glycol are used to produce 1,4-dioxane-2,3-dione and R~ is methyl, R2 is H, when oxalic acid and propylene glycol are used to produce S-methyl-1,4-dio~can~2,3-dione.
For formulation 6, Rl-R4 are H when malonic ester and ethylene glycol are used to produce 1,4-dio~epine-5-7,dione; R is methyl, Rl-R4 are H when malonic es~er and propylene glycol are used to produce 2-methyl-1,4-dioxe~ine and Rl-R3 are 25H, R4 is methyl when methyl malonic ester and ethylene glycol are used to produce . . .
6-methyl-1,4 dioxepine.
~:or formulation 7, Rl-R4 are H when S-hydroxyvaleric acid is used to produce delta-~alerolactone and Rl is methyl, R2-R4 are H, when 5-hydroxycaproicacid is usod to produce 5-methyl-valerolactone.
30Oligomers of certain of the hydroxy acids that can be used to make the lactones can also be used as a degr~dation promoter, either by itself or in combina~on W O 92/20738 PC~r/US92/04243 ~ 2 1 0 9 6 1 8 -8-with a lactone. Oligomers of lactic acid having from 2 to 50 lactic acid moieties are particularly suitable. A preferred degradation promoter is a mi~ture of lactone from lactic acid or hydroxycaproic acid and oligomers of lactic acid or hydroxycaproic acid having from about 109~ to about 95% of the lactone.
S Plasticizers useful in the polymer compositions of the present invention are conveneional plasticizers used in the preparation of thermoplastic cellulose ester compositions. Suieable plasticizers include diethyl phthalate, dimethyl phthalate, ethoxyethyl phthalate, metho~yethyl phehalate, dibutyl tartrate, diethylene glycol-butyl ether, diethylene glycol mon~ethyl ether, tripropionin, ben~oyl benzoate, triphenyl phosphate, triwtin, diamyl phthalate and ortho-cresyl para-toluene sulfonate.
Many of the plasdcizers commonly known for use in the formation of thermoplastic cellulose ester compositions are highly hydrophobic and provide e~treme resistance to moisture in the finished polymer product. Some of the plasticizers, however, are relatively hydrophilic. The degradation promoters of the present invention hydrophilic. Consequently, in one embodiment of the invention, it isdesirable to provide a hydrophilic lipophilic balance (HLB) of hydrophobic plasticizers and degradation promoters of the present invention which is within the range of from about 10 to about 40.
In general, the cellulose ester is present in the compositions of the present invention at a level of from about 20 to about 80% by weight. All percentages used herein by weight unless otherwise indicated~ The cellulose esters useful in the present invendon may be selected from cellulose acetate, cellulose propionate, cellulose butyrate, cellulose acetate-butyrate and cellulose acetate-propionate. The cellulose esters have a molecular weight of at least about 5,000 and preferably have a molecular weight of from between about 5,000 and about 500,000. The cellulose acetate-butyrate preferably has from about 90 to about 99% acetate and from about 10 to about 1% of butyrate. I~e cellulose acetate-propionate preferably has an acctate level of from about 80 to about 99X and a propionate level of from about 20 to about 1%.
The plasticizer is present in the polymaic compositions of the invention at a level of from 0% to about soæ by weight of the composition. The hydrophilic Wo 92/20738 Pcr/uss2/04743 2 1 ~ 9 ~ 1 8 degradation promoter is preferably present in the polymeric compositions at a level of from about 1 to about 60% by weight of the composition. The sum of the total level of use of the plasticizer and the hydrophilic degradation promoter is from about 20% to about 80% by weight of the composition.
S Some of the degradation promoters useful in the present invention also act as plasticiærs and can be used without the addition of other conventional hydrophobic plasticizers. Degradation promoters which can be used without a plasticizer include oligomers of lactic acid and lactones made from lactic acid and citric acid.
While not wishing to be bound by any theory, it is believed that degradation of the degradable cellulose ester formulations of the inventions result from leaching of the relatively hydrophilic degradation promoter from the composition by water leaving bshind a somewhat more open or porous molecular lattice expossd tothe water. The cellulose ester is present in an amorphous state when extensivelyplasticizsd during melt-fabrication.
On~e the porous cellulose ester is in intimate contact with water after leaching of the degradation promoter, there is a higher concentration of water pressnt than with conventional hydrophobic plasticized cellulose esters and the mass action of the water promotes hydrolysis. An acidic degradation promotsr provides a source of acid that catalyzes the hydrolysis. Enzymatic degradation is also possible as a result - of the exposed, moistened cellulose ester lattice structure. The hydrolysis is accelerated by the formation of an acidic medium arising from certain of the deg~adation promoters and their hydrolysis and from hydrolysis of the cellulose ester to forrn an organic acid.
The use of plasticized, degradable cellulose esters can a~pand the market . .
for cellulose esters by significant quantides. The degradable cellulose esters of the present invention provides a plasticized system that is low cost and provides the biodegradability to serve a growing marlcet, par~cularly in sheet materials, which are used for common products, such as ga~bage bags.
W O 92/20738 PC~r/US~2~04243 f 2i0~618 The following examples further illustrate various features of the invention but are intended to in no way limit the scope of the invention which is defined in the appended claims.
EXAMPLES
S Example, 1 In Table 1 are shown prior art cellulose acetate-plasticizer mixtures containing conventional plasticizers and examples of the present invention containing a leachable plasticizer. Sample Nos. 2-2, 2-3, 2~, 3-3 and -8 can be considered state of the art thermoplastic cellulose acetate controls, with nonleachable hydrophobic plasticizers. By nonleachable it is meant that the compositions prohibits easy access to moisture and is, therefore, essentially nondegradable. Each of the degradadonpromoters used in the composîtions of the invention has a significant solubility in water and/or they hydrolyze readily to wata soluble acid components. After hydrolysis, the acid promotes degradation.
The addition of an inorganic acid or organic acid to conventional cellulose compositions does not provide similar results. Sample 2-5, containing 1%
fumaric acid, and sample 2-6, containing 24% lactic acid~ did not show any appreciable degree of weathering after 6 months exposure to seawater. Sample 2-7, containing 1% phosphoric acid, produced a composition that was too brittle to test.
Whe~ the inorganic acids buried in a conventional hydrophobic plasticizer matrix, they effectively shut off from moisture and serving their purpose of promotinghydrolysis. Organie acids combined wi~ the leachable degradation promoters of the invention can accelerate hydrolysis.
The leachable degradation promoters work well in promoting hydrolysis, particularly if they form acids, in situ. Comp the results of -8 and -~ of Table 1, f~r example. The -8 sample with the conventional plasticizer, diethyl phthalate,displayed no degradation for more than one year. Weathering and degradation tests were performed in l:lorida seawater, Flonda beach air and outdoor panels in Ohio.
The -9 sample containing cellulose acetate with diethyl ph~alate as ~e plasticizer, and wo 92/~0738 Pcr/us92/04243 . , lactide as the leachable component, weathered promptly. In 21 days it changed from a very flexible, colorless, transparent film into a very brittle, white, opaque material~
The other examples of the invention, -32, -36-3, -37, ~2-2, ~2-5, and 43-1 were similarly leachable and weatherable. All of these compositions are intimate 5mi~tu~es, that is, the degradation promoters are efficient, since they producedtransparent films that were easily melt processed without degradation into smooth, glossy, thin films.
Tensile strength testing was performed according to ASTM D638. The moduli, or measures of stiffness, varied with the amount of plasticizer and/or 10degradation promoter. In general, the total amount of plasticizer needs to be greater than 40 weight p rcent to obtain films that mimic the foldabiliq and extensibility of polyolefins. Samples -37 and ~2-S were thermoformed into a stiff, transparent, colo~less salad cover shape. Sample -42-2 was formed into a trash bag shape.
Oligomeric lactic acid and polyethyl lactate are commercially attractive 15degradation promoters which also function as plasticizers. They are easily prepared by the condensation of lactic acid and ethyl lactate, a simple process that useseconomical precursors. Both of these mat~rials intimately melt-disperse with cellulose acetate and provide well behaved thermoplastics.
The cellulose acetate used was a commercial grade that had a weight-20average molecular weight of 85,000, as judged by GPC. Higher molecular weightswould have p~ovided better strength and higher percent elongations under stress.
DEGRADABLE CELLULOSE PQLD~
Fl~ld of ~he In~en¢ion The present invention is directed to a cellulose ester composidon which may be used to form thermoplastic polymeric materials having improved degradation S properties upon exposure to moisture. The compositions include at least onedegradation promoter that will leach from the polymeric materials in the presence of moisture after disposal of the polymeric composition in the envir~nment. In one embodiment, the present invention is directed to a thermoplastic cellulose acetate polymer composition having improved degradation properties upDn exposure to moisture which includes cellulose acetate, a plasticizer for the cellulose acetate and a hydrophilic degradation promoter.
I~ack~round of the Invention The disposal of modern packaging resins, such as polyethylene, polypropylene, polyvinyl chlodde and polystyrene is becoming an increasingly seAous problem. Accordingly, significant technical effort has been expended to produce polymeric compositions which are biodegradable. Representative patents directed to producing biodegradable polymers are U.S. Patent No. 3,950,282 to Gilbert, et al., U.S. Patent No. 4,048,410 to Taylor, et al., U.S. Patent No. 4,038,228 to Taylor, U.S. Patent No. 4,051,306 to Tobias, et a}., U.S. Patent No. 4,056,499 to Taylor and '20 U.S. Patent No. 3,907,726 to Tomiyana, all of which are related to methods or compositions for producing degradable polymeric materials.
Some of the first polymers developed for commercial use were based on cellulose. These inçluded regenerated cellulose (rayon) and various cellulose este~s, such as ceiluiose acetate, cellulose butyrate, cellulose propionate and mixed esters of cellulose (acetate, acetate butyrate and acetate propionate).
Regenerated cellulose materials, such as cellophane and rayon, are environmentally degradable at a very slow rate. However, to provi~e cellulose esters in the form of a melt extmded film, a high levd of plasticizer is required. Suchplasticizer is used to provide cellulose ester compositions which can be formed into wo 92/20738 Pcr/us92/042-3 a thermoplastic film by melt-fabrication methods. Cellulose acetate in its pure form is not a thermoplastic when melt-fabricated by methods such as extrusion. The use of such high levels of plasticizer produced plastic materials which are highly stable and which do not degrade when expo~ed to the envir~nment, even in highly moist 5 conditions. The wide variety of soil and microorganisms which are known to have the ability to enzymatically hydrolyze cellulose and pure cellulose esters to soluble intermediates do not react with oellulose esters which are highly plasticized.
Nevertheless, films and flexible sheet plastic packaging materials produced fromcellulose esters, such as cellulose acetate, are highly desirable in that cellulose acetate 10 is potendally one of the least e~pensive plasdc films to produce. It would be highly desirable to provide a cellulose ester packaging material whicb can be degraded by exposure to normal ambient environmental condidons. As used herein, the term "normal ambient environmental condidon" is meant to include those conditions which prevail during the disposal of most waste materials, such as in a landfill or waste 15 dump.
Accordingly, it is tbe principal object of the present invendon to provide cellulose ester composidons which are degradable by exposure to moisture in a normal ambient environment.
- Summary of ~h ~n~ntion The present invendon is directed to a thermoplastic cellulose ester polymer composidon having improved degradation properties upon exposure to moisture. The composition includes a cellulose ester and a degradation promoter.The degradatdon promoter, after formation of the polymer composidon into an end-product and in the presence of moisture, is water soluble and leachable from thcpolymer cnd-product or in the presence of moisture, hydrolyzes to form water soluble by-products which are leachable from the polymer end-product. The degradation promoter also acts as a catalyst to enhance the hydrolysis of the cellulose acetate, resulting in a mi~ture of cellulose and acedc acid. The cellulose can then depolymerize into saccharides that are more biodegradable. The degradation promoter W O 92/2~738 P~r/US92/04243 ~ -3~ 2109~1~
can act as a plasticizer for the cellulose ester polymer or can be used in combination with other known plastici~ers.
et~iled Description ofthe Inventio~
Cellulose is a polysaccharide formed from anhydroglucose units. ~ch S of the anhydroglucose units contains three fr~e hydroxyl groups which can be reacted to form esters. The extent to which substitution of an acid takes place is Icnown as the degree of substitution and is expressed as the average number of hydroxyl groups, of the three av~ulable in the anhydroglu~ose unit, that have been replaced. Cellulose esters useful in the present invention have a degree of subs~tution of from about 2.0 to about 2.6. Exp~essed in other terms, the cellulose acetates useful in the present invendon have an ester content of from about 39% to about 42.5% on an acety}
equivalent basis. In the pr~aration of cellulose esters b~ving substitutions appreciably below 3, i.e., in the range of 2.0 to 2.6, it has not been possiUe to malce products of good uniformity by esterifying directly to the desired substitution. This is because of lS the topochemical character of the reaction. EsteAfication proceeds inwardly from the outer surface of the cellulose fiber and uniformity is poor until the product has completely dissolved in the esterification mixture. Such complete dissolu~on occurs close to the triester stage. In order to prepare uniform products of substitution 2.~
~.6, it is necessary to make the triester and hydrolyze the triester in soludon to the desired degree of substitution.
Accordingly, early use of cellulose esters utilized the triester fonnulation.
Cellulose triesters, however, are difficult to mold and many early efforts were directed at methods and compositions for improving the molding capability of cellulose triesters. U.S. Patent 2,067,310 to Auden, for example, discloses a pr~ess of ....
making molded articles that can use molding temperatures as low as 120 C. to 180 C. and mnlding pressures of 2,000 to 3,000 psi, which are lower than the usual molding temperatures and pr,essures for cellulose tnacetate. The process of the Auden patent consists in mixing cellulose triacetate and a mate~ial taken from group consisdng of lactides, and the anhydrides of maleic, succinic and phthalic acids. The WO 92/20738 PCI`/US92/04243 ;''~ 4-addition of the lactides and the anhydrides in combination with the use of plasticizers produced a moldable cellulose triacetate composition.
U.S. Patent No. 2,805,171 to Williams, also discloses a method for providing a moldable composition of cellulose triacetate. As discussed in the Williams S patent, cellulose tri~cetate having an acetyl content of 52.5% to 53.5% (figured as percent acetic acid) are acetone insoluble cellulose esters. The cellulose esters useful in the present invention, having an acetyl content of from between about 39% andabout 42.5%, are characterized in the Williams patent as being acetone soluble.
The degradable thermoplastic cellulose ester compositions of the present 10 invention are mixtures of a cel!ulose ester having an ester content, on an acetyl basis, of from between about 39% and about 42.S% and a degree of substitution of from about 2.0 to about 2.6, a plasticizer and a degradation promoter. While not wishing to bc bound by any theory, it is believed that thc degradablc functionality of the compositions of the invention are at least par~ally attributable to access by water to 15 thc polymer and hydrolysis of the polymer at the pendant acetyl groups and at the acetal linkages.
The degaation promoters of the present invention are hydrophilic materials. The degradation promoters are cyclic internal monoesters, cyclic internal double esters and oligomers of such acids having from 2 to S0 acid moieties. The20 monoesters have a single oxygen molecule in the ring and can be prepared from any of the hydroxy acids except the ~-hydroxy acids. Monoester lactones useful as degradation promoters in the present invention are usuaUy prepared from hydroxy acids. The cyclic double esters can be prepared from a-hydroxy acids. Cyclic internal esters are generally referred to as lactones. The cyclic double ~membered 25 esters are sometimes referred to as dioxanediones.
While the cyclic internal esters of the invention can be prepared from suitable hydroxy acids, other chemical pathways for their prepara~on are available.
The y- and ~lactones arc commonly prepared by dther hydrolysis or disdllation ofr or ~halo acids, by treatment of unsaturated acids with aqueous hydrobromic or 30 sulfuric acids, or by panial reducdon of cyclic acid anhydrides. B-Lactones result wo 92/20738 PCr/USs2/04243 -5- ~lO~lX
from the reaction of a ketene with aldehydes or ketones. The reac~ion of ketene with formaldehyde is shown below.
H2C=C=0 + C ~ H2C C--O
I
Large-ring lactones can be made by oxidation of cyclic ketones with Caro's acid; thus, cyclohexanone yields ~ caprolactone~ Some lactones are prepared from ehe reaction S of a dicarboxylic acid wi~ a polyhydric alcohol, such as lhe reaction of malonic acid with ethylene glycol.
Suitable hydroxy acids and dicarboxylic acids for preparation of the lactones useful as degradation promoters of the present invention include 3-hydroxypropionic acid, 2-hydroxy, 1,2,3 propanetricarboxylic acid (citric acid), 3-1~ hydroxybutyric acid, 4-hydroxybutyric aeid, 4-hydroxy-valeric acid, 5-hydroxyvaleric acid, ~hydroxycaproic acid, 2-hydroxyacetic acid (glycolic acid), 2-hydroxy-propionic acid (lactic acid), 2 hydroxybutyric acid, 2-hydroxyvaleric acid, 2-hydroxycaproic acid, 2-hydroxy-hept~noic acid, 2-hydroxyoctanoic acid, 2-hydroxy-pelargonic acid, 2-hydroxyphenylacetic acid, l-hydroxy-cyclohexane l-carboxylic acid, oxalic acid plus 'lS ethylene glycol, oxalic acid plus propylene glycol, malonic acid plus ethylene glycol, and malonic acid plus propylene glycol.
In gen~al, the lactones useful in the present invention have from 3 to 6 calbon atoms and 1 or 2 oxygen atoms in the ring. The lactones produced from thehydroxy acids will have structures corresponding to the following formulae:
w o 92J2~738 Pc~r/us92/042~3 2lo!36l8 ~ ~ R~ R5 (1) (2~ (3) R2~o ~ 3 (4) (~) (6) R2--~ \
(7) whe~on any R can be hydkogen, Cl-CIO alkyl, or an alyl gnoup ~ect~d from benzene~ nap~ene,benzenesubsdtu~ed ~n~h Cl-C4 aLkyl and nap~enesubsdtut~d ~h Cl-C4 aLkyl.
WO 92/20738 PCI /US~2/04243 -7- i 210~!~18 For formulation 1, Rl and R2 are H when 3-hyd~oxypropionic acid is used to produce propiolactone; R~ is H and R2 is methyl when 3-hydro~ybuqric acid is used to produce butyrolactone; R~ is methyl and R2 is methyl when 3-hydroxyisobutyric acid is used to produce 2,3-dimethyl propiolactone; Rl is phenyl 5and R2 is H when 3-hydroxy 3-phenyl is used to produce 3-phenyl propio-lactone and Rl is H and R2 is phenyl when 3-hydroxy, 2-phenyl is used to produce 2-phenyl propiolactone.
For formulation 2, R1, R2 and R3 are H when 4-hydroxybuqric acid is used to produce valerolactone and Rl is methyl, R2 is H and R3 is H when 4-10hydroxyvaleric acid is used to produce 4-methyl vale~olactone.
For formulation 3, Rl through Rs are H when 6-hydroxycaproic acid is used to produce ~-caprolactone and Rl is methyl, R2-RS are H, when hydro~cyheptylic acid is used to produce ~methyl-caprolactone.
For forrltuladon 4, Rl-R4 are H when glycolic acid is used to produce 15glycolide; Rt and R3 are methyl, R2 and R4 are H when lacdc acid is used to produce lactide; Rt and R3 are phenyl, R2 and R4 are H when phenyl-2 hydroacetic acid isused to produce 2,5-diphenyl-dioxane-3,6-dione and Rl and R3 are hexyl, R2 and R4 are H, when 2-hydroxyoctanoic acid is used to produce 2,5-dihexyldioxane-3,~dione.
Por formulation S, Rl and R2 are H, when oxalic acid and ethylene 20glycol are used to produce 1,4-dioxane-2,3-dione and R~ is methyl, R2 is H, when oxalic acid and propylene glycol are used to produce S-methyl-1,4-dio~can~2,3-dione.
For formulation 6, Rl-R4 are H when malonic ester and ethylene glycol are used to produce 1,4-dio~epine-5-7,dione; R is methyl, Rl-R4 are H when malonic es~er and propylene glycol are used to produce 2-methyl-1,4-dioxe~ine and Rl-R3 are 25H, R4 is methyl when methyl malonic ester and ethylene glycol are used to produce . . .
6-methyl-1,4 dioxepine.
~:or formulation 7, Rl-R4 are H when S-hydroxyvaleric acid is used to produce delta-~alerolactone and Rl is methyl, R2-R4 are H, when 5-hydroxycaproicacid is usod to produce 5-methyl-valerolactone.
30Oligomers of certain of the hydroxy acids that can be used to make the lactones can also be used as a degr~dation promoter, either by itself or in combina~on W O 92/20738 PC~r/US92/04243 ~ 2 1 0 9 6 1 8 -8-with a lactone. Oligomers of lactic acid having from 2 to 50 lactic acid moieties are particularly suitable. A preferred degradation promoter is a mi~ture of lactone from lactic acid or hydroxycaproic acid and oligomers of lactic acid or hydroxycaproic acid having from about 109~ to about 95% of the lactone.
S Plasticizers useful in the polymer compositions of the present invention are conveneional plasticizers used in the preparation of thermoplastic cellulose ester compositions. Suieable plasticizers include diethyl phthalate, dimethyl phthalate, ethoxyethyl phthalate, metho~yethyl phehalate, dibutyl tartrate, diethylene glycol-butyl ether, diethylene glycol mon~ethyl ether, tripropionin, ben~oyl benzoate, triphenyl phosphate, triwtin, diamyl phthalate and ortho-cresyl para-toluene sulfonate.
Many of the plasdcizers commonly known for use in the formation of thermoplastic cellulose ester compositions are highly hydrophobic and provide e~treme resistance to moisture in the finished polymer product. Some of the plasticizers, however, are relatively hydrophilic. The degradation promoters of the present invention hydrophilic. Consequently, in one embodiment of the invention, it isdesirable to provide a hydrophilic lipophilic balance (HLB) of hydrophobic plasticizers and degradation promoters of the present invention which is within the range of from about 10 to about 40.
In general, the cellulose ester is present in the compositions of the present invention at a level of from about 20 to about 80% by weight. All percentages used herein by weight unless otherwise indicated~ The cellulose esters useful in the present invendon may be selected from cellulose acetate, cellulose propionate, cellulose butyrate, cellulose acetate-butyrate and cellulose acetate-propionate. The cellulose esters have a molecular weight of at least about 5,000 and preferably have a molecular weight of from between about 5,000 and about 500,000. The cellulose acetate-butyrate preferably has from about 90 to about 99% acetate and from about 10 to about 1% of butyrate. I~e cellulose acetate-propionate preferably has an acctate level of from about 80 to about 99X and a propionate level of from about 20 to about 1%.
The plasticizer is present in the polymaic compositions of the invention at a level of from 0% to about soæ by weight of the composition. The hydrophilic Wo 92/20738 Pcr/uss2/04743 2 1 ~ 9 ~ 1 8 degradation promoter is preferably present in the polymeric compositions at a level of from about 1 to about 60% by weight of the composition. The sum of the total level of use of the plasticizer and the hydrophilic degradation promoter is from about 20% to about 80% by weight of the composition.
S Some of the degradation promoters useful in the present invention also act as plasticiærs and can be used without the addition of other conventional hydrophobic plasticizers. Degradation promoters which can be used without a plasticizer include oligomers of lactic acid and lactones made from lactic acid and citric acid.
While not wishing to be bound by any theory, it is believed that degradation of the degradable cellulose ester formulations of the inventions result from leaching of the relatively hydrophilic degradation promoter from the composition by water leaving bshind a somewhat more open or porous molecular lattice expossd tothe water. The cellulose ester is present in an amorphous state when extensivelyplasticizsd during melt-fabrication.
On~e the porous cellulose ester is in intimate contact with water after leaching of the degradation promoter, there is a higher concentration of water pressnt than with conventional hydrophobic plasticized cellulose esters and the mass action of the water promotes hydrolysis. An acidic degradation promotsr provides a source of acid that catalyzes the hydrolysis. Enzymatic degradation is also possible as a result - of the exposed, moistened cellulose ester lattice structure. The hydrolysis is accelerated by the formation of an acidic medium arising from certain of the deg~adation promoters and their hydrolysis and from hydrolysis of the cellulose ester to forrn an organic acid.
The use of plasticized, degradable cellulose esters can a~pand the market . .
for cellulose esters by significant quantides. The degradable cellulose esters of the present invention provides a plasticized system that is low cost and provides the biodegradability to serve a growing marlcet, par~cularly in sheet materials, which are used for common products, such as ga~bage bags.
W O 92/20738 PC~r/US~2~04243 f 2i0~618 The following examples further illustrate various features of the invention but are intended to in no way limit the scope of the invention which is defined in the appended claims.
EXAMPLES
S Example, 1 In Table 1 are shown prior art cellulose acetate-plasticizer mixtures containing conventional plasticizers and examples of the present invention containing a leachable plasticizer. Sample Nos. 2-2, 2-3, 2~, 3-3 and -8 can be considered state of the art thermoplastic cellulose acetate controls, with nonleachable hydrophobic plasticizers. By nonleachable it is meant that the compositions prohibits easy access to moisture and is, therefore, essentially nondegradable. Each of the degradadonpromoters used in the composîtions of the invention has a significant solubility in water and/or they hydrolyze readily to wata soluble acid components. After hydrolysis, the acid promotes degradation.
The addition of an inorganic acid or organic acid to conventional cellulose compositions does not provide similar results. Sample 2-5, containing 1%
fumaric acid, and sample 2-6, containing 24% lactic acid~ did not show any appreciable degree of weathering after 6 months exposure to seawater. Sample 2-7, containing 1% phosphoric acid, produced a composition that was too brittle to test.
Whe~ the inorganic acids buried in a conventional hydrophobic plasticizer matrix, they effectively shut off from moisture and serving their purpose of promotinghydrolysis. Organie acids combined wi~ the leachable degradation promoters of the invention can accelerate hydrolysis.
The leachable degradation promoters work well in promoting hydrolysis, particularly if they form acids, in situ. Comp the results of -8 and -~ of Table 1, f~r example. The -8 sample with the conventional plasticizer, diethyl phthalate,displayed no degradation for more than one year. Weathering and degradation tests were performed in l:lorida seawater, Flonda beach air and outdoor panels in Ohio.
The -9 sample containing cellulose acetate with diethyl ph~alate as ~e plasticizer, and wo 92/~0738 Pcr/us92/04243 . , lactide as the leachable component, weathered promptly. In 21 days it changed from a very flexible, colorless, transparent film into a very brittle, white, opaque material~
The other examples of the invention, -32, -36-3, -37, ~2-2, ~2-5, and 43-1 were similarly leachable and weatherable. All of these compositions are intimate 5mi~tu~es, that is, the degradation promoters are efficient, since they producedtransparent films that were easily melt processed without degradation into smooth, glossy, thin films.
Tensile strength testing was performed according to ASTM D638. The moduli, or measures of stiffness, varied with the amount of plasticizer and/or 10degradation promoter. In general, the total amount of plasticizer needs to be greater than 40 weight p rcent to obtain films that mimic the foldabiliq and extensibility of polyolefins. Samples -37 and ~2-S were thermoformed into a stiff, transparent, colo~less salad cover shape. Sample -42-2 was formed into a trash bag shape.
Oligomeric lactic acid and polyethyl lactate are commercially attractive 15degradation promoters which also function as plasticizers. They are easily prepared by the condensation of lactic acid and ethyl lactate, a simple process that useseconomical precursors. Both of these mat~rials intimately melt-disperse with cellulose acetate and provide well behaved thermoplastics.
The cellulose acetate used was a commercial grade that had a weight-20average molecular weight of 85,000, as judged by GPC. Higher molecular weightswould have p~ovided better strength and higher percent elongations under stress.
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Example 2 The following example illustrates the use of a 7-membered ring lactone as a plasticizer. The cellulose acetate chosen was a polymer (Eastman Chemicals Company, "SAMS-E") with an average degree of substitution of 2.5, a weight-average S GPC molecular weight of 149,000, and a number-average, GPC molecular weight of47,000. It contained no plasticizer as supplied and would char before melting.
The cellulose acetate, 55 parts by weight, was mixed with 45 parts of ~-caprolactone, a pure liquid, which was immediately soaked up by the polymer withsimple hand stirring. The mixture was placed on an open, two-roll mill preheated to 350 F. The counter-rotating mill was set at a tight nip at approximately 10 rpm.
Within S minutes the mixture clears as evidence of complete mixing. The mix was sheeted out off the mill. The mix fused very easily with no dripping, but some fuming of the caprolactone.
The above melt-blend formulation was compression molded at 300 F to 15 provide approximately 8 to 10 mil, thick films. These were completely colorless and transparent, thus providing evidence of plasdcization. The films were pliable, tear-resistant, and easily elongateable at about 37 C with heat supplied by holding in the hand.
The films were evaluated on an Instron tester for tensile properties by 20 ASTM 882, and the results are shown in Table 2. The caprolactone content was estimated as 22.7 percent by isothermal weight loss at 200 C by TGA. The tensile strength, modulus, and elongation-t~break values which are reported in Table 2 resemble those found to be useful for packaging applications, similar to some grades of high-density polyethylene and polypropylene.
Exam~le ~
This example illustrates the use of a S-membered ring lactone. The procedure of Example 2 was repeated using 4-valerolactone in place of the caprolactone and using the same cellulose acetate. Thus, for example, 55 parts of cellulose acetate was mixed by hand with 45 parts of 4-valerolactone"nill-rolled 5 minutes at 350 F, and compression molded into 8 to 10 mil films, which were W~ 92/20738 PCr/USs2/04243 -1S- 210~
completely transparent and devoid of color. The film was tough, strong, elongateable, and tear resistant. The percent lactone con~nt was 17.0 percent by TGA. Tensile data are shown in Table 2. The properties are approximately those found for crystalline polypropylene used in molding and packaging applications.
S xam~le 4 The same cellulose acetate (powder) as used in Example 2, 55 parts by weight, was intimately stirred with 45 parts of granular, pure, glycolide, a membered Ang, cyclic dilactone. The mixture easily fused on the mill roll at 350 P and compression molded to clear, colorless films: The films turned hazy at thesurface upon handling, which indicated a trace amount of the glycolide had bloomed to the surface. The percent glycolide by TGA was 22.3 percent. Tensile properties are shown in Table 2 and are approximately similar to those encountered with low-densit~y polyethylene.
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Example 2 The following example illustrates the use of a 7-membered ring lactone as a plasticizer. The cellulose acetate chosen was a polymer (Eastman Chemicals Company, "SAMS-E") with an average degree of substitution of 2.5, a weight-average S GPC molecular weight of 149,000, and a number-average, GPC molecular weight of47,000. It contained no plasticizer as supplied and would char before melting.
The cellulose acetate, 55 parts by weight, was mixed with 45 parts of ~-caprolactone, a pure liquid, which was immediately soaked up by the polymer withsimple hand stirring. The mixture was placed on an open, two-roll mill preheated to 350 F. The counter-rotating mill was set at a tight nip at approximately 10 rpm.
Within S minutes the mixture clears as evidence of complete mixing. The mix was sheeted out off the mill. The mix fused very easily with no dripping, but some fuming of the caprolactone.
The above melt-blend formulation was compression molded at 300 F to 15 provide approximately 8 to 10 mil, thick films. These were completely colorless and transparent, thus providing evidence of plasdcization. The films were pliable, tear-resistant, and easily elongateable at about 37 C with heat supplied by holding in the hand.
The films were evaluated on an Instron tester for tensile properties by 20 ASTM 882, and the results are shown in Table 2. The caprolactone content was estimated as 22.7 percent by isothermal weight loss at 200 C by TGA. The tensile strength, modulus, and elongation-t~break values which are reported in Table 2 resemble those found to be useful for packaging applications, similar to some grades of high-density polyethylene and polypropylene.
Exam~le ~
This example illustrates the use of a S-membered ring lactone. The procedure of Example 2 was repeated using 4-valerolactone in place of the caprolactone and using the same cellulose acetate. Thus, for example, 55 parts of cellulose acetate was mixed by hand with 45 parts of 4-valerolactone"nill-rolled 5 minutes at 350 F, and compression molded into 8 to 10 mil films, which were W~ 92/20738 PCr/USs2/04243 -1S- 210~
completely transparent and devoid of color. The film was tough, strong, elongateable, and tear resistant. The percent lactone con~nt was 17.0 percent by TGA. Tensile data are shown in Table 2. The properties are approximately those found for crystalline polypropylene used in molding and packaging applications.
S xam~le 4 The same cellulose acetate (powder) as used in Example 2, 55 parts by weight, was intimately stirred with 45 parts of granular, pure, glycolide, a membered Ang, cyclic dilactone. The mixture easily fused on the mill roll at 350 P and compression molded to clear, colorless films: The films turned hazy at thesurface upon handling, which indicated a trace amount of the glycolide had bloomed to the surface. The percent glycolide by TGA was 22.3 percent. Tensile properties are shown in Table 2 and are approximately similar to those encountered with low-densit~y polyethylene.
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Claims (45)
We claim:
1. A thermoplastic composition, degradable on exposure to moisture, comprising: a mixture of, a cellulose ester polymer having a molecular weight of at least about 5,000;
a plasticizer; and a hydrophilic degradation promoter selected from the group consisting of cyclic internal monoesters, and cyclic internal double esters.
a plasticizer; and a hydrophilic degradation promoter selected from the group consisting of cyclic internal monoesters, and cyclic internal double esters.
2. A composition in accordance with Claim 1 wherein said cellulose ester has a degree of ester substitution from about 2.0 to 2.6.
3. A composition in accordance with Claim 1 wherein said cellulose ester is selected from cellulose acetate, cellulose butyrate, cellulose propionate, cellulose acetate-butyrate and cellulose acetate-propionate.
4. A composition in accordance with Claim 1 wherein said degradation promoter is selected from the group consisting of lactones prepared from hydroxy acids, lactones prepared from dicarboxylic acids and polyhydric alcohols and oligomers of said hydroxy acids having from 2 to 50 acid moieties.
5. A composition in accordance with Claim 4 wherein said lactone has from 3 to 6 carbon atoms and 1 or 2 oxygen atoms in the ring.
6. A composition in accordance with Claim 4 wherein said lactone is prepared from hydroxy acids selected from the group consisting of 3-hydroxypropionic acid, 3-hydroxybutyric acid, 4-hydroxybutyric acid, 4-hydroxyvaleric acid, 5-hydroxyvaleric acid, 6-hydroxycaproic acid, 2-hydroxyacetic acid (glycolic acid), 2-hydroxy-propionic acid (lactic acid), 2 hydroxybutyric acid, 2-hydroxyvaleric acid, 2-hydroxycaproic acid, 2-hydroxy-heptanoic acid, 2-hydroxyoctanoic acid, 2-hydroxy-pelargonic acid, 2-hydroxyphenylacetic acid, 1-hydroxy-cyclohexane 1-carboxylic acid, oxalic acid plus ethylene glycol, oxalic acid plus propylene glycol, malonic acid plus ethylene glycol, and malonic acid plus propylene glycol.
7. A composition in accordance with Claim 4 wherein said degradation promoter is a lactone prepared from lactic acid.
8. A composition in accordance with Claim 4 wherein said degradation promoter is a mixture of a lactone from lactic acid and said oligomers of lactic acid, said mixture having from about 10% to about 95% of said lactone.
9. A composition in accordance with Claim 4 wherein said degradation promoter is caprolactone.
10. A composition in accordance with Claim 4 wherein said degradation promoter is a mixture of a lactone made from hydroxycaproic acid and an oligomer of hydroxycaproic acid, said mixture having from about 10% to about 95% of said lactone.
11. A composition in accordance with Claim 5 wherein said degradation promoter is a mixture having from about 10%
to about 95% of a lactone prepared from lactic acid and from about 5%
to about 95% of an oligomer of lactic acid
to about 95% of a lactone prepared from lactic acid and from about 5%
to about 95% of an oligomer of lactic acid
12. A composition in accordance with Claim 1 wherein said degradation promoter is a cyclic ester having a structure corresponding to any of the following formulae:
(1) (2) (3) (4) (5) (6) (7) wherein any R can be hydrogen, C1-C10 alkyl, or an aryl group selected from benzene, napthalene, benzene substituted with C1-C4 alkyl and napthalene substituted with C1-C4 alkyl.
(1) (2) (3) (4) (5) (6) (7) wherein any R can be hydrogen, C1-C10 alkyl, or an aryl group selected from benzene, napthalene, benzene substituted with C1-C4 alkyl and napthalene substituted with C1-C4 alkyl.
13. A composition in accordance with Claim 1 wherein said plasticizer is selected from the group consisting of diethyl phthalate, dimethyl phthalate, ethoxyethyl phthalate, methoxyethyl phthalate, dibutyl tartrate, diethylene glycol-butyl ether, diethylene glycol mono-ethyl ether, tripropionin, benzoyl benzoate, triphenyl phosphate, triacetin, diamyl phthalate and ortho-cresyl para-toluene sulfonate.
14. A composition in accordance with Claim 1 [2] having an HLB of from about 10 to about 50.
15. A composition in accordance with Claim 1 wherein said cellulose ester is present at a level of from about 20% to about 80%.
16. A composition in accordance with Claim 1 wherein said plasticizer is present at a level of from about 1%
to about 50%, and said degradation promoter is present at a level of from about 1% to about 60%.
to about 50%, and said degradation promoter is present at a level of from about 1% to about 60%.
17. A composition in accordance with Claim, 13 wherein the total level of the sum of the plasticizer level and the degradation promoter level is from about 20% to about 80%.
18. A composition in accordance with Claim 1 wherein said cellulose ester has a molecular weight of from about 5,000 to about 500,000.
19. A composition in accordance with Claim 1 wherein said cellulose ester is cellulose acetate.
20. A composition in accordance with Claim 1 wherein said cellulose ester is cellulose butyrate.
21. A method for improving the degradation rate of cellulose ester polymers upon exposure to moisture comprising:
(a) providing a cellulose ester polymer having a molecular weight of at least about 5,000;
(b) dispersing in said polymer (1) a plasticizer. and (2) an effective amount of a degradation promoter selected from the group consisting of cyclic internal monoesters and cyclic internal double esters; and (c) exposing said dispersion to moisture.
(a) providing a cellulose ester polymer having a molecular weight of at least about 5,000;
(b) dispersing in said polymer (1) a plasticizer. and (2) an effective amount of a degradation promoter selected from the group consisting of cyclic internal monoesters and cyclic internal double esters; and (c) exposing said dispersion to moisture.
22. A method in accordance with Claim 27 wherein said cellulose ester has a degree of ester substitution from about 2.0 to 2.6.
23. A method in accordance with Claim 27 wherein said cellulose ester is selected from cellulose acetate, cellulose butyrate, cellulose propionate, cellulose acetate-butyrate and cellulose acetate-propionate.
24. A method in accordance with Claim 27 wherein said degradation promoter is selected from the group consisting of lactones prepared from hydroxy acids, lactones prepared from dicarboxylic acids and polyhydric alcohols and oligomers of said hydroxy acids having from 2 to 50 acid moieties.
25. A method in accordance with Claim 24 wherein said lactone has from 3 to 6 carbon atoms and 1 or 2 oxygen atoms in the ring.
26. A method in accordance with Claim 24 wherein said lactone is prepared from hydroxy acids selected from the group consisting of 3-hydroxypropionic acid, 3-hydroxybutyric acid, 4-hydroxybutyric acid, 4-hydroxyvaleric acid, 5-hydroxyvaleric acid, 6-hydroxycaproic acid, 2-hydroxyacetic acid (glycolic acid), 2-hydroxy-propionic acid (lactic acid), 2 hydroxybutyric acid, 2-hydroxyvaleric acid, 2-hydroxycaproic acid, 2-hydroxy-heptanoic acid, 2-hydroxyoctanoic acid, 2-hydroxy-pelargonic acid, 2-hydroxyphenylacetic acid, 1-hydroxy-cyclohexane 1-carboxylic acid, oxalic acid plus ethylene glycol, oxalic acid plus propylene glycol, malonic acid plus ethylene glycol, and malonic acid plus propylene glycol.
27. A method in accordance with Claim 24 wherein said degradation promoter is a lactone prepared from lactic acid.
28. A method in accordance with Claim 24 wherein said degradation promoter is a mixture of a lactone from lactic acid and said oligomers of lactic acid, said mixture having from about 10% to about 95% of said lactone.
29. A method in accordance with Claim 24 wherein said degradation promoter is caprolactone.
30. A method in accordance with Claim 24 wherein said degradation promoter is a mixture of a lactone made from hydroxycaproic acid and an oligomer of hydroxycaproic acid, said mixture having from about 10% to about 95% of said lactone.
31. A method in accordance with Claim 24 wherein said degradation promoter is a mixture having from about 10% to about 95% of a lactone prepared from lactic acid and from about 5% to about 95% of an oligomer of lactic acid.
32. A method in accordance with Claim 24 wherein said degradation promoter is a cyclic ester having a structure corresponding to any of the following formulae:
(1) (2) (3) (4) (5) (6) (7) wherein any R can be hydrogen, C1-C10 alkyl, or an aryl group selected from benzene, napthalene, benzene substituted with C1-C4 alkyl and napthalene substituted with C1-C4 alkyl.
(1) (2) (3) (4) (5) (6) (7) wherein any R can be hydrogen, C1-C10 alkyl, or an aryl group selected from benzene, napthalene, benzene substituted with C1-C4 alkyl and napthalene substituted with C1-C4 alkyl.
33. A method in accordance with Claim 21 wherein said plasticizer is selected from the group consisting of diethyl phthalate, dimethyl phthalate, ethoxyethyl phthalate, methoxyethyl phthalate, dibutyl tartrate, diethylene glycol-butyl ether, diethylene glycol mono-ethyl ether, tripropionin, benzoyl benzoate, triphenyl phosphate, triacetin, diamyl phthalate and ortho-cresyl para-toluene sulfonate.
34. A method in accordance with Claim 21 having an HLB of from about 10 to about 40.
35. A method in accordance with Claim 21 wherein said cellulose ester is present at a level of from about 20% to about 80%.
36. A method in accordance with Claim 21 wherein said plasticizer is present at a level of from about 1% to about 50%, and said degradation promoter is present at a level of from about 1% to about 60%.
37. A method in accordance with Claim 21 wherein the total level of the sum of the plasticizer level and the degradation promoter level is from about 20% to about 80%.
38. A method in accordance with Claim 21 wherein said cellulose ester has a molecular weight of from about 5,000 to about 500,000.
39. A method in accordance with Claim 21 wherein said cellulose ester is cellulose acetate.
40. A method in accordance with Claim 21 wherein said cellulose ester is cellulose butyrate.
41. A composition in accordance with Claim 1 which further includes an organic acid.
42. A composition in accordance with Claim 1 which further includes an oligomer of a precursor acid to cyclic internal monoesters, or cyclic internal double esters, having from 2 to 50 acid moieties.
43. A method in accordance with Claim 21 comprising: also dispersing an organic acid.
44. A method in accordance with Claim 21 comprising: also dispersing an oligomer of a precursor acid to cyclic internal monoesters or cyclic internal double esters having from 2 to 50 acid moieties.
45. A plastic packaging material formed from a degradable thermoplastic composition comprising:
a mixture of, a cellulose ester polymer;
a plasticizer; and a hydrophilic degradation promoter selected from the group consisting of cyclic internal monoesters and cyclic internal double esters.
a mixture of, a cellulose ester polymer;
a plasticizer; and a hydrophilic degradation promoter selected from the group consisting of cyclic internal monoesters and cyclic internal double esters.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US70340191A | 1991-05-21 | 1991-05-21 | |
| US07/703,401 | 1991-05-21 | ||
| US87635692A | 1992-04-30 | 1992-04-30 | |
| US07/876,356 | 1992-04-30 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2109618A1 true CA2109618A1 (en) | 1992-11-26 |
Family
ID=27107133
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2109618 Abandoned CA2109618A1 (en) | 1991-05-21 | 1992-05-20 | Degradable cellulose polymers |
Country Status (5)
| Country | Link |
|---|---|
| EP (1) | EP0586575A1 (en) |
| JP (1) | JPH06507929A (en) |
| AU (1) | AU2144492A (en) |
| CA (1) | CA2109618A1 (en) |
| WO (1) | WO1992020738A1 (en) |
Families Citing this family (21)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0663936B1 (en) * | 1992-10-07 | 1999-01-27 | National Starch and Chemical Investment Holding Corporation | Starch ester blends with linear polyesters |
| WO1994010238A1 (en) * | 1992-10-26 | 1994-05-11 | Eastman Kodak Company | Method for increasing the biodegradability of cellulose esters |
| TW256845B (en) * | 1992-11-13 | 1995-09-11 | Taisyal Kagaku Kogyo Kk | |
| US6313202B1 (en) * | 1993-05-28 | 2001-11-06 | Eastman Chemical Company | Cellulose ester blends |
| GB9311399D0 (en) * | 1993-06-02 | 1993-07-21 | Zeneca Ltd | Polyester composition |
| DE4325352C1 (en) * | 1993-07-28 | 1994-09-01 | Rhodia Ag Rhone Poulenc | Plasticised cellulose acetate, process for the preparation thereof, and the use thereof for the production of filaments |
| DE4404840A1 (en) * | 1994-02-16 | 1995-08-17 | Wolff Walsrode Ag | Thermoplastic biodegradable polysaccharide derivatives, process for their preparation and their use |
| US6770658B2 (en) | 1998-09-09 | 2004-08-03 | Inflazyme Pharmaceuticals Ltd. | Substituted γ-phenyl-Δ-lactams and uses related thereto |
| WO2009014202A1 (en) * | 2007-07-26 | 2009-01-29 | Alcare Co., Ltd. | Water-disintegrable sheet and pouch made of the same for excreta-holding wear |
| US9155335B2 (en) * | 2007-12-17 | 2015-10-13 | Celanese Acetate Llc | Degradable cigarette filter |
| DE102008051579A1 (en) * | 2008-10-14 | 2010-04-15 | Rhodia Acetow Gmbh | Biodegradable plastic and use thereof |
| US11058796B2 (en) | 2010-10-20 | 2021-07-13 | 206 Ortho, Inc. | Method and apparatus for treating bone fractures, and/or for fortifying and/or augmenting bone, including the provision and use of composite implants, and novel composite structures which may be used for medical and non-medical applications |
| US11207109B2 (en) | 2010-10-20 | 2021-12-28 | 206 Ortho, Inc. | Method and apparatus for treating bone fractures, and/or for fortifying and/or augmenting bone, including the provision and use of composite implants, and novel composite structures which may be used for medical and non-medical applications |
| WO2015095745A1 (en) * | 2010-10-20 | 2015-06-25 | 206 Ortho, Inc. | Method and apparatus for treating bone fractures, and/or for fortifying and/or augmenting bone, including the provision and use of composite implants, and novel composite structures which may be used for medical and non-medical applications |
| US11484627B2 (en) | 2010-10-20 | 2022-11-01 | 206 Ortho, Inc. | Method and apparatus for treating bone fractures, and/or for fortifying and/or augmenting bone, including the provision and use of composite implants, and novel composite structures which may be used for medical and non-medical applications |
| US10525169B2 (en) | 2010-10-20 | 2020-01-07 | 206 Ortho, Inc. | Method and apparatus for treating bone fractures, and/or for fortifying and/or augmenting bone, including the provision and use of composite implants, and novel composite structures which may be used for medical and non-medical applications |
| EP2629780A4 (en) | 2010-10-20 | 2014-10-01 | 206 Ortho Inc | Implantable polymer for bone and vascular lesions |
| US11291483B2 (en) | 2010-10-20 | 2022-04-05 | 206 Ortho, Inc. | Method and apparatus for treating bone fractures, and/or for fortifying and/or augmenting bone, including the provision and use of composite implants |
| US9320601B2 (en) | 2011-10-20 | 2016-04-26 | 206 Ortho, Inc. | Method and apparatus for treating bone fractures, and/or for fortifying and/or augmenting bone, including the provision and use of composite implants |
| US10010609B2 (en) | 2013-05-23 | 2018-07-03 | 206 Ortho, Inc. | Method and apparatus for treating bone fractures, and/or for fortifying and/or augmenting bone, including the provision and use of composite implants |
| WO2016040434A1 (en) * | 2014-09-09 | 2016-03-17 | Celanese Acetate Llc | Cellulose ester plastics and methods and articles relating thereto |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE501889C (en) * | 1926-05-23 | 1930-07-05 | Holzverkohlungs Ind Akt Ges | Solvents and emollients for cellulose esters and similar cellulose debris |
| DE2128007A1 (en) * | 1971-06-05 | 1972-12-14 | Bayer Ag, 5090 Leverkusen | Use of foamed cellulose esters for the production of coffins |
| DE3914022A1 (en) * | 1989-04-28 | 1990-10-31 | Aeterna Lichte Gmbh & Co Kg | BIODEGRADABLE PLASTIC MATERIALS |
-
1992
- 1992-05-20 CA CA 2109618 patent/CA2109618A1/en not_active Abandoned
- 1992-05-20 AU AU21444/92A patent/AU2144492A/en not_active Abandoned
- 1992-05-20 EP EP19920913240 patent/EP0586575A1/en not_active Withdrawn
- 1992-05-20 JP JP5500278A patent/JPH06507929A/en active Pending
- 1992-05-20 WO PCT/US1992/004243 patent/WO1992020738A1/en not_active Application Discontinuation
Also Published As
| Publication number | Publication date |
|---|---|
| JPH06507929A (en) | 1994-09-08 |
| EP0586575A1 (en) | 1994-03-16 |
| WO1992020738A1 (en) | 1992-11-26 |
| AU2144492A (en) | 1992-12-30 |
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