Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – At least one aryl ring which is part of a fused or bridged...
Patent
1992-06-19
1994-03-29
Langel, Wayne
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
At least one aryl ring which is part of a fused or bridged...
423306, C01B 2545, C08K 332
Patent
active
052985458
DESCRIPTION:
BRIEF SUMMARY
The invention relates to basic calcium aluminum hydroxy phosphites, a process for their production and their use as stabilizers for halogen-containing polymers, in particular polyvinyl chloride.
Halogen-containing, thermoplastic resin compositions or shaped articles made therefrom are decomposed or disintegrated by the action of heat or light. For this reason, stabilizers must be added to these resins. Inorganic and/or organic compounds of toxic heavy metals such as lead, barium or cadmium are customarily used for this for especially demanding articles such as profiles, plates or tubes. 2-basic lead phosphite attained special importance in the stabilizing of e.g. rigid PVC articles where a good thermal resistance and good light and weather resistance are required. The use of basic lead phosphite as stabilizer against the decomposition of PVC by heat, daylight and UV radiation is e.g. described in DD-PS 61 095. CH-PS 8 510 622 describes the stabilizing of rigid and plasticized PVC products with a high filler share with a mixture of basic lead sulphate and lead phosphite. Another use of basic lead phosphite for PVC high-resistance foam mixtures is described in U.S. Pat. No. 4,797,426.
Since basic lead phosphite is rated as toxic like other heavy-metal-containing stabilizers, attempts are made to find stabilizing alternatives. A plurality of combinations of inorganic and organic compounds is known as a stabilizers for halogen-containing, thermoplastic resins. A hydrotalcite is suggested as stabilizer in JP-PS 1 213 865 and in JP-OS 80 445/80. This substance is superior to mixtures of Ca/Zn metallic soaps as regards resistance to heat and transparency However, the problem of the discolouration of the resin during processing due to the use of hydrotalcite cannot be solved. It is suggested according to JP-OS 80 444/82 to use combinations of hydrotalcite and 1,3-diketone compounds. Hydrotalcites have moreover the disadvantage that they split off water and carbon dioxide at the processing temperatures customary for PVC. It is suggested in EP-A- 0 256 872 to eliminate this disadvantage by the addition of very finely divided magnesium oxide. FR-A-2 593 386 describes the use of alkaline earth or alkali phosphites such as calcium phosphites for stabilizing halogen-containing resins.
The invention is based on the object of making available new compounds and a process for their production, which are in particular suited as stabilizers for halogen-containing polymers without having the aforementioned disadvantages of the known stabilizers, and which are in particular rated as non-toxic.
This object is accomplished according to the invention by the making available of calcium aluminum hydroxy phosphites of the general formula
In the aforementioned formula x means preferably 3-6 and m means preferably 2-4.
Tests by means of X-ray diffraction showed that the compounds according to the invention do not belong to the hydrotalcite type regarding their crystal structure.
Surprisingly, it became apparent that the calcium aluminum hydroxy phosphites according to the invention impart resistance to heat comparable to that of basic lead phosphites to halogen-containing, thermoplastic resin and the shaped articles produced therefrom. The compounds according to the invention prevent discolouring in the production of e.g. rigid PVC shaped articles, colour retention and weather stability of the shaped articles stabilized with the compounds according to the invention is equivalent to that of the products stabilized with toxic heavy metal compounds.
The subject matter of the invention is also a process for the production of the calcium aluminum hydroxy phosphites according to the invention, which is characterized in that mixtures of calcium hydroxide and/or calcium oxide, aluminum hydroxide and sodium hydroxide or of calcium hydroxide and/or calcium oxide and sodium aluminate are reacted with phosphorous acid in amounts corresponding to the production of the desired compounds in an aqueous medium and the reaction product is separated and
REFERENCES:
patent: 3969293 (1976-07-01), White et al.
patent: 4799426 (1989-01-01), Waki et al.
International Search Report.
Beck Reinhard
Kuerzinger Alfred
Puerzer Albert
Razvan Coriolan
Rosenthal Michael
Baerlocher GmbH
Langel Wayne
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