Compositions – Preservative agents – Anti-oxidants or chemical change inhibitants
Patent
1996-10-02
1999-10-26
Wu, Shean C.
Compositions
Preservative agents
Anti-oxidants or chemical change inhibitants
25240024, 25240052, 25240053, 25240054, 25240061, 524398, 524399, 524400, C09K 1532, C08K 5098
Patent
active
059722452
DESCRIPTION:
BRIEF SUMMARY
This application is made pursuant to 35 U.S.C. .sctn. 371 of international application number PCT/EP95/00340, filed Jan. 31, 1995.
The invention relates to basic layered lattice compounds, a process for preparing the same and their use in a halogenated resin composition having improved thermal stability, initial colouring and improved colour fastness.
When performing a melt deformation a halogen-containing thermoplastic resin such as polyvinyl chloride (PVC) transforms into a polyene structure, hydrochloric acid being eliminated and the polymer darkening in colour. In order to improve the thermal stability of the polymer it is common practice to incorporate metal carboxylates into the resin as stabilizers. However, as the incorporation of stabilizers alone with a prolonged melt deformation process may result in a so-called metal combustion causing blackening of the polymer, the addition of a co-stabilizer such as polyols (such as pentaerythritol), organic phosphorous acid esters (such as triphenylphosphite), epoxy compounds (such as epoxidized soy oil) or the like represents common practice.
As basic lead salts as well as other heavy metal-containing stabilizers are rated toxic there are attempts to find alternatives for stabilizing. A multitude of combinations of inorganic and organic compounds as stabilizers for halogen-containing polymers is known. DE-3 019 632 and EP-189 899 suggest hydrotalcites as stabilizers. With regard to thermal stability and transparency these compounds are superior to mixtures of Ca/Zn-metal carboxylates. Using hydrotalcites, however, the discoloration problem of the polymer during processing cannot be solved. According to EP-63 180 the use of combinations of hydrotalcites and 1,3-diketo compounds is suggested as a solution to this problem.
DE-3 941 902 and DE-4 106 411 and DE-4 002 988 and DE-4 106 404, respectively, as well as DE-4 103 881 suggest basic calcium-aluminium-hydroxy-phosphites and basic calcium-aluminium-hydroxy-carboxylates, respectively, as well as hydrocalumites as stabilizers for halogen-containing polymers, especially PVC. Regarding thermal stability and transparency these compounds are inferior to mixtures containing hydrotalcites. Furthermore, the use of such compounds containing water of hydration can give rise to problems with the processing of the halogen-containing resin due to the elimination of the water of crystallization; cf. M. Meyn "Doppelhydroxide und Hydroxidoppelsalze--Synthese, Eigenschaften und Anionenaustauschverhalten" [Double hydroxides and hydroxide double salts--Synthesis, properties and anion exchange performance], Thesis, Kiel 1991. EP-A-0 256 872 suggests the addition of super-finely divided magnesium oxide in order to overcome this drawback.
DE-4 103 916 and DE-4 106 403 are claiming basic hydroxy compounds of di and trivalent metal ions which are defined as "not being of the hydrotalcite type", among other things, as PVC stabilizers. Regarding thermal stability and transparency these compounds are also inferior to mixtures containing hydrotalcites. Furthermore, by using such compounds which contain water of hydration problems with the processing of the halogen-containing resin due to the elimination of water of crystallization may arise herewith as well.
DE-4 238 567 claims garnets with mono, di, tri and tetravalent metal ions having a spatial network structure similar to grossular as PVC stabilizers. Regarding thermal stability and transparency these compounds are also inferior to mixtures containing hydrotalcites. Furthermore, garnets are effective as abrasives. As is known, garnets are used in the art as abrasives for optical lenses and for sandblasting.
The problem underlying the invention is the provision of novel compounds as well as a process for preparing the same which are particularly suited as stabilizers for halogen-containing polymers without showing the above-mentioned drawbacks of the known stabilizers, especially being rated non-toxic.
According to the invention this problem is solved by the provision of basic layer
REFERENCES:
patent: 5569694 (1996-10-01), Kuhm et al.
Dolleschal Klaus
Ebner Paul
Hensel Hartmut
Krivanec Heinz
Lattacher Emil
Chemson Polymer-Additive Gesellschaft m.b.H.
Wu Shean C.
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