Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From phenol – phenol ether – or inorganic phenolate
Reexamination Certificate
2001-03-20
2002-12-24
Hampton-Hightower, P. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From phenol, phenol ether, or inorganic phenolate
C528S080000, C528S081000, C528S083000, C528S272000, C525S131000, C525S420000, C525S424000, C525S437000, C525S440030, C525S457000, C525S907000
Reexamination Certificate
active
06498225
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to novel polycarbodiimide-based block copolymers, a method of preparing them and also their use as hydrolysis stabilizers in ester-group-containing polymers.
BACKGROUND OF THE INVENTION
Organic carbodiimides are known. Their chemistry and their preparation are described, for example, in Chemical Reviews, vol. 81 (1981), pages 589 to 639 and Angewandte Chemie 74 (1962), pages 801 to 806.
Monocarbodiimides and oligomeric polycarbodiimides can be prepared, for example, by the action of basic catalysts on mono- or polyisocyanates. Suitable as basic catalysts are, for example, heterocyclic, phosphorous-containing compounds in accordance with GB-A-1 083 410 and phospholenes and phospholidines as specified in DE-B-11 30 594 and also their oxides and sulfides.
Furthermore, polycarbodiimides having terminal urethane groups are described, for example, in U.S. Pat. No. 2,941,983 and DE-B-22 48 751. The products can be prepared, for example, by carbodiimidization of diisocyanates with sterically hindered isocyanate groups and subsequent partial or complete urethanation of the terminal NCO groups with alcohols. As described in DE-A-2 248 751, if aromatic diisocyanates having isocyanate groups with different reactivity are used, the isocyanate groups having higher reactivity with alcohol may be partially or completely converted into the corresponding urethane groups and the remaining isocyanate groups may be reacted to form carbodiimide groups with the elimination of carbon dioxide.
The carbodiimides and polycarbodiimides are preferably used as stabilizers to prevent the hydrolytic cleavage of polyester-based plastics. According to the specifications of DE-A-14 94 009, aromatic and/or cycloaliphatic monocarbo-diimides, in particular, are suitable for this purpose that are substituted in position 2 and 2′, such as 2,2′,6,6′-tetraisopropyidiphenylcarbodiimide. Polycarbodiimides having a molecular weight of over 500 and a content of more than 3 carbodiimide groups are described in DE-B-12 85 747 as stabilizers to counteract the effects of heat and moisture in ester-group-containing plastics.
Although a substantial stability of ester-group-containing plastics with respect to moist heat, water and water vapor can be achieved by adding said (poly)carbodiimides as stabilizers, the products also have disadvantages. A disadvantage of the tetraalkyl-substituted monocarbodiimides, such as, for example, 2,2′,6,6′-tetraisopropyldiphenylcarbodiimide, preferably used industrially, is their relatively high vapor pressure and their tendency as a result of the low molecular weight to migrate out of the polyaddition products, for example thermoplastic polyurethanes (TPU) or polycondensation products, for example polyterephthalates. To eliminate this deficiency, according to the specifications of EP-A-0 460 481, substituted monocarbodiimides or oligomeric substituted polycarbodiimides having terminal isocyanate groups are used which are prepared from substituted diisocyanates and that virtually do not release toxic volatile substances originating from the carbodiimides used either when hot, for example under the conventional processing conditions, or at room temperature. Polycarbodiimides of this type have higher melting points or cannot be melted and can be introduced into the polyurethanes and/or their parent substances only with an appreciable expenditure in terms of apparatus and time. The distribution of the polycarbodiimides in the ester-group-containing plastics is, therefore, often insufficiently homogeneous so that the stabilizer action does not meet the expectations.
More readily melting polycarbodiimide derivatives can be obtained by converting some of the terminal isocyanate groups into urethane groups, for example in accordance with DE-A-22 48 751 or U.S. Pat. No. 2,941,983.
Because of the statistical occurrence of monocarbodiimides and short-chain homologues, there is also in these compounds the tendency to form cleavage products that have low vapor pressure and a high tendency to migrate in the plastic and that tend to outgas at the higher processing temperatures.
In polymers that are incapable of forming hydrogen bridge bonds, such as polyesters and polycarbonates, the terminally masked urethane groups bring about incompatibility effects that limit their effectiveness.
SUMMARY OF THE INVENTION
The object of the present invention was to eliminate the above-mentioned disadvantages entirely or at least partly and to provide hydrolysis protection agents that have a high efficiency at low dosage in ester-group-containing polymers, that are nontoxic, that have a high thermal stability, that do not release toxic cleavage products when exposed to heat and that have good compatibility with the polymer matrix and do not therefore, effloresce out of the ester-group-containing polymers.
DETAILED DESCRIPTION OF THE INVENTION
Surprisingly, this object was achieved by using polycarbodiimide-based block copolymers of formula (I)
X—[—(A)
m
—(B)
n
—]
o
—X (I),
in which
X is identical or different and is selected from —NHCO—R, —NHCONH—R, —NHCOO—R, —NHCOS—R, —COO—R, —O—R, —NR
2
, —S—R, —OH, —NH
2
, —NHR, S—H, and —NCO, but preferably stands for —NHCONH—R, —NHCOO—R, —OH, and wherein the group R denote an alkyl, cycloalkyl, aralkyl or aryl radical containing 1 to 30, preferably 2 to 18, carbon atoms,
m, n are, independently of one another an integer from 1 to 1000, preferably from 5 to 200,
o is an integer from 1 to 500, preferably from 3 to 100,
A is selected from the carbodiimides or polycarbodiimides of formula (II)
—(—N═C═N—Y—)— (II),
in which
Y is selected from ortho- or bisortho-substituted aromatics, aralkylenes in which the carbon atom linked to the carbodiimide group is substituted by C
1
- to C
14
-alkyl groups, and cycloalkylenes in which the carbon atom linked to the carbodiimide group is substituted by C
1
- to C
14
-alkyl groups, and
B is selected from the group comprising (poly)dioles, (poly)diamines, (poly)dimercaptans, (poly)aminoalcohols, (poly)aminomercaptans and (poly)mercaptoalcohols.
The invention furthermore provides a method of preparing the block copolymers according to the invention and the use of the block copolymers according to the invention as stabilizers to prevent the hydrolytic degradation of ester-group-containing polymers.
To prepare the polycarbodiimides (component A, formula II) incorporated in the block copolymers according to the invention of formula (I), diisocyanates can be condensed as starting compounds at elevated temperatures, for example at 40 to 200° C., in the presence of catalysts with the release of carbon dioxide. Suitable methods are described in DE-A-11 30 594. Strong bases or phosphorous compounds, for example, have proved satisfactory as catalysts. Phospholene oxides, phospholidines and phospholine oxides are preferably used. Suitable for preparing the component A according to the invention are all diisocyanates, wherein aromatic diisocyanates substituted by C
1
- to C
4
-alkyl, such as 2,4,6-triisopropylphenyl 1,3-diisocyanate, 2,4,6-triethylphenyl 1,3-diisocyanate or 2,4,6-trimethylphenyl 1,3-diisocyanate, substituted diisocyanatodiphenyl-methanes, such as 2,4′-diisocyanato-diphenylmethane, 3,3′,5,5′-tetraisopropyl-4,4′-diisocyanatodiphenylmethane or 3,3′,5,5′-tetraethyl-4,4′-diisocyanatodiphenylmethane and substituted aralkyls, such as 1,3-bis(1-methyl-1-isocyanatoethyl) benzene, are preferably used. These diisocyanates can be used individually or as mixtures to prepare component A of formula (I).
The degree of polymerization or degree of condensation, respectively, m in the formula (I) can be adjusted by the choice of reaction conditions, such as reaction temperature, reaction time and amount of catalyst. This can easily be tracked by determining the NCO content or by the carbon dioxide evolved. Preferably, the degree of condensation is adjusted so that residual isocyanates in the range from 1
Heiliger Ludger
Müller Volker
Tebbe Heiko
Cheung Noland J.
Gil Joseph C.
Hampton-Hightower P.
Rhein Chemie Rheinau GmbH
Seng Jennifer R.
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