Biodegradable polyestreramide and a process of preparing

Details Biodegradable polyestreramide and a process of preparing Biodegradable polyestreramide and a process of preparing

1997-07-07

2002-03-05

Hampton-Hightower, P. (Department: 1711)

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

From carboxylic acid or derivative thereof

C528S170000, C528S172000, C528S173000, C528S272000, C528S289000, C528S332000, C528S335000, C528S336000, C525S427000, C525S432000, C525S436000

Reexamination Certificate

active

06353084

ABSTRACT:

BACKGROUND OF THE INVENTION
This is a National Stage Application under 35 U.S.C. 371, based on International Application No. PCT/EP 95/02,493, filed Jun. 27, 1995.
1. Field of the Invention
The present invention relates to biodegradable polyesteramides P1 obtainable by reacting a mixture consisting essentially of
(a1) a mixture consisting essentially of
35-95 mol % of adipic acid or ester-forming derivatives thereof or mixtures thereof,
5-65 mol % of terephthalic acid or ester-forming derivatives thereof or mixtures thereof, and
0-5 mol % of a compound containing sulfonate groups,
where the total of the individual mole percentages is 100 mol %, and
(a2) a mixture consisting essentially of
(a21) 99.5-0.5 mol % of a dihydroxy compound selected from the group consisting of C
2
-C
6
-alkanediols and C
5
-C
10
-cycloalkanediols,
(a22) 0.5-99.5 mol % of an amino-C
2
-C
12
-alkanol or an amino-C
5
-C
10
-cycloalkanol, and
(a23) 15 50 mol % of a diamino-C
1
-C
8
-alkane,
(a24) 0-50 mol % of a 2,2′-bisoxazoline of the general formula
where R
1
is a single bond, a (CH
2
)
q
alkylene group with q=2, 3 or 4, or a phenylene group, where the total of the individual mole percentages is 100 mol %, and where the molar ratio of (a1) to (a2) is chosen in the range from 0.4:1 to 1.5:1,
with the proviso that the polyesteramides P1 have a molecular weight (M
n
) in the range from 4000 to 40,000 g/mol, a viscosity number in the range from 30 to 350 g/ml (measured in o-dichlorobenzene/phenol (50/50 ratio by weight) at a concentration of 0.5% by weight of polyesteramide P1 at 25° C.) and a melting point in the range from 50 to 220° C., and with the further proviso that from 0 to 5 mol %, based on the molar amount of component (a1) used, of a compound D with at least three groups capable of ester formation are used to prepare the polyesteramides P1.
The invention furthermore relates to polymers and biodegradable thermoplastic molding compositions as claimed in the dependent claims, processes for the preparation thereof, the use thereof for producing biodegradable moldings, and adhesives, biodegradable moldings, foams and blends with starch obtainable from the polymers and molding compositions according to the invention.
2. Description of the Related Art
Polymers which are biodegradable, ie. decompose under environmental influences in an appropriate and demonstrable time span have been known for some time. This degradation usually takes place by hydrolysis and/or oxidation, but predominantly by the action of microorganisms such as bacteria, yeasts, fungi and algae. Y. Tokiwa and T. Suzuki (Nature, 270 (1977) 76-78) describe the enzymatic degradation of aliphatic polyesters, for example including polyesters based on succinic acid and aliphatic diols.
EP-A 565,235 describes aliphatic copolyesters containing [—NH—C(O)O—] groups (urethane units). The copolyesters of EP-A 565,235 are obtained by reacting a prepolyester, which is obtained by reacting essentially succinic acid and an aliphatic diol, with a diisocyanate, preferably hexamethylene diisocyanate. The reaction with the diisocyanate is necessary according to EP-A 565,235 because the polycondensation alone results only in polymers with molecular weights such that they display unsatisfactory mechanical properties. A crucial disadvantage is the use of succinic acid or ester derivatives thereof to prepare the copolyesters because succinic acid and derivatives thereof are costly and are not available in adequate quantity on the market. In addition, the polyesters prepared using succinic acid as the only acid component are degraded only extremely slowly.
WO 92/13019 discloses copolyesters based predominantly on aromatic dicarboxylic acids and aliphatic diols, where at least 85 mol % of the polyesteramide diol residue comprise a terephthalic acid residue. The hydrophilicity of the copolyester is increased and the crystallinity is reduced by modifications such as the incorporation of up to 2.5 mol % of metal salts of 5-sulfoisophthalic acid or short-chain ether diol segments such as diethylene glycol. This is said in WO 92/13019 to make the copolyesters biodegradable. However, a disadvantage of these copolyesters is that the biodegradation by microorganisms was not demonstrated, on the contrary only the behavior towards hydrolysis in boiling water or, in some cases, also with water at 60° C.
According to the statements of Y. Tokiwa and T. Suzuki (Nature, 270 (1977) 76-78 or J. of Appl. Polymer Science, 26 (1981) 441-448), it may be assumed that polyesters which are essentially composed of aromatic dicarboxylic acid units and aliphatic diols, such as PET (polyethylene terephthalate) and PBT (polybutylene terephthalate), are not enzymatically degradable. This also applies to copolyesters which contain blocks composed of aromatic dicarboxylic acid units and aliphatic diols.
Furthermore, Y. Tokiwa, T. Suzuki and T. Ando (J. of Appl. Polym. Sci. 24 (1979) 1701-1711) prepared polyesteramides and blends of poly-caprolactone and various aliphatic polyamides such as polyamide-6, polyamide-66, polyamide-11, polyamide-12 and polyamide-69 by melt condensation and investigated their biodegradability by lipases. It was found that the biodegradability of such polyesteramides depends greatly on whether there is a predominantly random distribution of the amide segments or, for example, a block structure. In general, amide segments tend to reduce the rate of biodegradation by lipases.
However, the crucial factor is that no lengthy amide blocks are present, because it is known from Plant. Cell Physiol. 7 (1966) 93, J. Biochem. 59 (1966) 537 and Agric. Biol. Chem. 39 (1975) 1219 that the usual aliphatic and aromatic polyamides are biodegradable at the most only when oligomers, otherwise not.
Witt et al. (handout for a poster at the International Workshop of the Royal Institute of Technology, Stockholm, Sweden, Apr. 21-23, 1994) describe biodegradable copolyesters based on 1,3-propanediol, terephthalic ester and adipic or sebacic acid. A disadvantage of these copolyesters is that moldings produced therefrom, especially sheets, have inadequate mechanical properties.
BRIEF SUMMARY OF THE INVENTION
It is an object of the present invention to provide polymers which are degradable biologically, ie. by microorganisms, and which do not have these disadvantages. The intention was, in particular, that the polymers according to the invention be preparable from known and low-cost monomer units and be insoluble in water. It was furthermore the intention that it be possible to obtain products tailored for the desired uses according to the invention by specific modifications such as chain extension, incorporation of hydrophilic groups and groups having a branching action. The aim was moreover that the biodegradation by microorganisms should not be achieved at the expense of the mechanical properties in order not to restrict the number of applications.
We have found that this object is achieved by the polymers and thermoplastic molding compositions defined at the outset.
We have furthermore found processes for the preparation thereof, the use thereof for producing biodegradable moldings and adhesives, and biodegradable moldings, foams, blends with starch and adhesives obtainable from the polymers and molding compositions according to the invention.
DETAILED DESCRIPTION OF THE INVENTION
The polyesteramides P1 according to the invention have a molecular weight (M
n
) in the range from 4000 to 40,000, preferably from 5000 to 35,000, particularly preferably from 6000 to 30,000, g/mol, a viscosity number in the range from 30 to 350, preferably from 50 to 300, g/ml (measured in o-dichlorobenzene/phenol (50/50 ratio by weight) at a concentration of 0.5% by weight of polyesteramide P1 at 25° C.) and a melting point in the range from 50 to 220, preferably from 60 to 220° C.
The polyesteramides P1 are obtained according to the invention by reacting a mixture consisting essentially of
(a1) a mixture consisting essentially of
35-95, preferably from 45 to 80, mol % of adipic acid

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