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IP.com Disclosure Number: IPCOM000009679D
Publication Date: 2002-Sep-10

Publishing Venue

The IP.com Prior Art Database


ABSTRACT OF THE DISCLOSURE A process for the preparation and purification of mixed aromatic-aliphatic phosphites which enables an improved process using such purified aromatic aliphatic phospites for the preparation of stabilized polymers. The process involves the reaction of an alkylphenol with diphenyl-(or a lower dialkyl-) pentaerythritol diphosphite. The process is simple and inexpensive, and produces a relatively pure product.

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Field of the Invention

This invention relates to certain organophosphorus compounds which are useful as stabilizers for polymer compositions. In a more particular sense it relates to a method for the preparation and purification of such stabilizers.� The purified organophosphorus compound provides for improved feedability in additive feeder systems� for compounding with various polymers.

Background of the Invention

The purpose of stabilizers is to prevent deterioration of thermoplastic polymers during processing at high temperatures and also to permit the manufacture of products with increased intrinsic quality because of the enhancement of their resistance to thermal and light degradation during use.� In addition, because of these enhanced properties, their versatility is increased and wider use is thereby made possible.

Many such organic phosphites are available to serve this purpose. Among them are the bis-(alkylphenyl)pentaerythritol diphosphites which may have either the structure


where R and R' are each alkyl of 3-10 carbon atoms.� These phosphites provide eminently satisfactory performance because they tend to inhibit discoloration caused by high temperatures and also because they are themselves quite stable.� That is, they are characterized by a relatively high degree of intrinsic stability, especially under conditions of high humidity.� This quality is not normally characteristic of other organic phosphite stabilizers. Efficacy of these products as stabilizers for polymers, particularly polyolefins are well documented in a number of US and foreign patents including US 4,305, 866� and Japanese disclosure 59-80452.

It will be noted that the above phosphites are "mixed" aryl aliphatic phosphites, i.e., the phosphorus atom is bound through oxygen both to aliphatic and to aromatic carbon atoms.�

Manufacturing processes for pentaerythritol based alkylphenyl phosphite products are described in several patents including.� � US 4,305,866; 4,665,211; 5,137,950;4,739,090; 5,438,086 as well as some additional patents.

Detailed Description of the Invention

The present invention comprises a process for preparing mixed aromatic-aliphatic phosphites comprising mixing a diphenyl pentaerythritol diphosphite or a dialkyl pentaerythritol diphosphite wherein the alkyl groups contain 1-4 carbon atoms, with an alkylphenol having the formula

where R is alkyl of 3-10 carbon atoms and n is 1-3, and heating the resulting mixture so as to cause the formation of ROH and to remove such ROH by distillation followed by further purification. The product which results from this process is relatively pure

The substituent groups in the above pentaerythritol diphosphite most usually are phenyl.� Diphenyl pentaerythritol diphosphite is readily available and its transesterification with phenols proceeds smoothly.� The dimethyl compound likewise proceeds smoothly in such trans-esterifications and its use is limited...