Process for synthesis of vinyl esters from butene oligomers

Details Process for synthesis of vinyl esters from butene oligomers Process for synthesis of vinyl esters from butene oligomers

2000-02-28

2001-08-28

Gitomer, Ralph (Department: 1623)

Organic compounds -- part of the class 532-570 series

Organic compounds

Fatty compounds having an acid moiety which contains the...

C554S131000, C560S232000, C585S329000

Reexamination Certificate

active

06281372

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a process for synthesis of vinyl esters from butene oligomers, especially from dibutene and tributene, as well as the use of these vinyl esters.
2. Background of the Invention
Vinyl esters of tertiary carboxylic acids have long had a firm place in technology as comonomers, especially as internal plasticizers for the synthesis of environmentally safe, water-dispersable lacquers and inks on the basis of vinyl acetate. In addition to the action as plasticizers, they endow the copolymers with further advantageous properties such as high stability toward saponification, making the copolymers suitable for use under harsh conditions. Examples of such applications are as outdoor paints and thermally insulating surfacings of buildings.
The plasticizing properties of the vinyl esters, especially of tertiary carboxylic acids, depend on their chain length and on the type and position of the branches. One measure for the internal plasticization of copolymers is the glass transition temperature of the corresponding homopolymer. A comparison of the plasticizing properties of vinyl esters of various chain lengths by means of the glass transition temperature T
g
of the respective homopolymer reveals how it depends on molecular weight and on the degree of branching:
Glass transition
Glass transition
Chain length of
Straight-chain
temperature
Tertiary vinyl
temperature
the carboxylic acid
vinyl ester
[° C.]
ester
[° C.]
C
2
vinyl ester
Vinyl acetate
+38 (33)*
C
3
vinyl ester
Vinyl propionate
−7 (−7)*
C
4
vinyl ester
Vinyl butyrate
−5
C
5
vinyl ester
−15***
2,2-Dimethyl-
86 (70)*
propanoic acid
C
6
vinyl ester
Vinyl hexanoate
−20
2,2-Dimethyl-
41***
butanoic acid
C
10
vinyl ester
Vinyl decanoate
−60
C
12
vinyl ester
Vinyl laurate
−75 (−53)*
(Encyclopedia of Polymer Science and Engineering, Vol. 17, p. 439 (1989), J. Wiley & Sons, Inc.),
(*Ullman's Encyclopedia of Industrial Chemistry, Vol. A22, p. 2, 5
th
Ed. (1993), Verlag Chemie),
(**C. E. L. Feeder, Surface Coatings Austral. 228, 1985), 8, pp. 11-16,
(***measured by applicants).
These values are suitable only as data for comparison with one another, since they can vary with the method of synthesis of the test compound and with the test method. Nevertheless, it is evident that the plasticizing properties improve with increasing chain length of the vinyl ester (up to an alkyl group containing 12 carbon atoms in the case of straight chains). In particular, the vinyl esters of straight-chain carboxylic acids have very good plasticizing properties, but because they can be readily saponified they are not very suitable for many applications.
In contrast, the vinyl esters of tertiary carboxylic acids can be used for diverse purposes, since they are extremely stable to saponification, temperature and oxidation. On the other hand, the tertiary branch drastically reduces the plasticizing effect, and further branches in the chain lead to further deterioration, as the following examples of homopolymers of vinyl esters of tertiary C
9
carboxylic acids show:
Glass transition temperature
Tertiary C
9
carboxylic acids
(° C.)
2,3-Dimethyl-2-isopropylbutanoic acid
119 
2-Ethyl-2,3,3-trimethylbutanoic acid
115 
2,2,3,3-Tetramethylpentanoic acid
91
(VeoVa ® 9, Shell)
    
 
70 (60)*
2,4,4-Tetramethylpentanoic acid
55
2,2,4-Trimethylhexanoic acid
10
(H. P. H. Scholten, J. Vermeulen, W. J. van Westrenen, Recent development in latices based on vinyl esters of branched monocarboxylic acids, 7th International Conference on “Water-Borne Coatings”, 26-28 October 1998, Penta Hotel, London),
(*W. Lau, VeoVa ®, Vinyl Ester Monomer Polymers DotCom Magazine, Vol. 2, No. 2, Feb. 1996).
The compounds most commonly used in modern industry are vinyl esters synthesized from a mixture of tertiary C
10
carboxylic acid isomers, which form homopolymers having a glass transition temperature of −3° C. As an example, this mixture is highly suitable for use and is in great demand as an internal plasticizer for polyvinyl acetate, in which it simultaneously increases the stability toward saponification.
The C
10
carboxylic acid used for synthesis of the vinyl ester is in turn synthesized by addition of carbon monoxide and water to tripropene under pressure and catalysis with extremely acid catalysts (hydrocarboxylation, especially by the Koch reaction).
Tripropene, finally, a mixture of isomeric C
9
olefins, is obtained in a mixture with other olefin fractions (C
6
, C
12
and C
15
olefins by acid-catalyzed oligomerization of propene). Examples of suitable catalysts for this purpose are acid zeolites or phosphoric acid on a solid support.
One disadvantage in the process for synthesis of vinyl esters of C
10
carboxylic acids is that propene represents a relatively expensive raw material. Furthermore, considerable losses of raw material can be expected as a result of byproduct formation in the acid-catalyzed oligomerization of propene. Finally, it must be pointed out that the number of isomers in the tripropene fraction of the oligomer is already so large that even analytical control is difficult. The conversion to carboxylic acids ultimately leads to such a large number of isomers that it is difficult to define the properties of the resulting product mixture.
Some vinyl esters of tertiary carboxylic acids with more than 10 C atoms have been studied (for example, WO 93/22353). Certainly they all have plasticizing ability, as can be expected from their relatively long carbon chain. On the one hand, however, the necessary raw materials are in many cases not available in sufficient quantities at a reasonable price and, on the other hand, incompatibility in the copolymer becomes progressively worse with increasing chain length.
Some vinyl esters of tertiary carboxylic acids with fewer than 10 C atoms are also known and have been studied with regard to their suitability as plasticizers. For example, the vinyl esters based on pivalic acid (a tertiary C, acid) and on tertiary C
9
acids (VeoVa® 9) have a certain industrial importance, but in both cases they represent comonomers having a hardening effect compared with vinyl acetate.
It would therefore be desirable to exploit raw material sources other than propene or its oligomers for the synthesis of vinyl esters which have plasticizing properties equal to or better than those of the vinyl esters of, for example, the C
10
carboxylic acids based on tripropene.
SUMMARY OF THE INVENTION
The present invention is based on the surprising discovery that tertiary carboxylic acids synthesized from butene oligomers are extremely suitable as plasticizers.
Thus, the present invention provides a process for synthesis of vinyl esters, comprising:
(a) oligomerizing butenes,
(b) separating the butene oligomers from the oligomerized mixture from (a),
(c) converting the separated butene oligomers to carboxylic acids which are longer by one carbon atom, and
(d) converting the carboxylic acids to the corresponding vinyl esters.
The vinyl esters synthesized by the inventive process are extremely suitable as comonomers for the synthesis of internally plasticized polymers. Examples are the copolymerization of the C
9
carboxylic acid vinyl ester with vinyl chloride, or the copolymerization with vinyl acetate. Terpolymers containing acrylates are also a potential area of application. Under these conditions the proportion of vinyl esters synthesized according to the invention can be varied over wide limits, depending on the desired properties. They can also be used in the form of homopolymers if, for example, particularly compliant films are to be made.
A more complete appreciation of the invention and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description.
DETAILED DESCRIPTION OF THE INVENTION
The first step of the process accordin

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