Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Reexamination Certificate
2001-07-27
2004-12-28
Cain, Edward J. (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
C524S239000, C524S240000
Reexamination Certificate
active
06835765
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates generally to thermoplastics and more particularly to the use of selected nitrogen-containing surfactants as antistatic additives.
PRIOR ART
Thermoplastics, preferably PVC, are used for the production of a number of articles of everyday life, of which films are among the most well-known. Like most plastics, thermoplastics are pronounced insulators by virtue of their chemical constitution. Unfortunately, a disadvantage is that fir thermoplastics readily develop electrostatic charges and, once applied, charges cannot be dissipated quickly enough on account of the low surface conductivity. In practice, the electrostatic charging of plastics can be troublesome and can also give rise to serious dangers. These include above all:
heavy soiling of plastic surfaces,
production stoppages through the blocking of film webs and
a sparking through intensive charging with subsequent ignition of dust/air mixtures.
In order to solve the problem of static charging, antistatic agents are generally added to the thermoplastics to dissipate the charges from the surface. Examples of internal antistatic agents, i.e. substances which are added to the polymer melt before or during processing, are anionic, nonionic or cationic surfactants. A relevant overview was published by S. Riethmayer in Gumml, Asbest, Kunstst., 26, pp. 76-88, 182-184, 298-308, 419, 429, 507-512 (1973).
Japanese patent application JP 94/226266 (Henkel) describes antistatic agents for PVC in the form of mixtures of complex esters, alkyl benzenesulfonates and alkyl sulfates. Polyol complex esters are known for the same purpose from German patent application DE-Al 4304468 (Henkel). Finally, antistatic agents for PVC in the form of mixtures of anionic surfactants (secondary alkane sulfonates) and nonionic surfactants (amine polyglycol ethers) are commercially obtainable under the name of “Dehydat 80X” from Henkel KGaA.
However, the properties of known antistatic agents are still in need of improvement. They either fail to reduce the surface charge of the thermoplastics sufficiently quickly to the required level or, despite satisfactory antistatic properties, they lead to unwanted clouding in the films.
Accordingly, the problem addressed by the present invention was to finish thermoplastics in general and polyvinyl chloride and polyolefins in particular in such a way that, on the one hand, electrostatic charging would be significantly reduced and, on the other hand, transparent films permanently protected against clouding would be obtained.
DESCRIPTION OF THE INVENTION
The present invention relates to the use of fatty acid alkanolamine esters as antistatic agents for thermoplastics, more particularly for polyvinyl chloride and polyolefins.
It has surprisingly been found that fatty acid alkanolamine esters not only provide thermoplastics with excellent antistatic properties, they also lead to transparent films with hardly any tendency towards clouding, even in the event of prolonged storage.
Thermoplastics
In the context of the invention, the antistatic finish may be applied to thermoplastics in general. Typical examples are polyolefins, such as low-density and high-density polyethylene, polypropylene, polystyrene, vinyl polymers, polyamides, polyesters, polyacetals, polycarbonates and polyurethanes. However, the antistatic agents used in accordance with the invention are preferably incorporated in polyvinyl chlorides with K values in the range from 30 to 80.
Fatty Acid Alkanolamine Esters
The fatty acid alkanolamine esters are known substances. In a first and also preferred embodiment of the invention, the antistatic agents used are fatty acid triethanolamine esters which preferably correspond to formula (I):
in which R
1
CO is an acyl group containing 6 to 22 carbon atoms, R
2
and R
3
independently of one another represent hydrogen or have the same meaning as R
1
CO and m, n and p together stand for 0 or numbers of 1 to 12. Typical examples of fatty acid triethanolamine esters which may be used in accordance with the present invention are products based on caproic acid, caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, isostearic acid, stearic acid, oleic acid, elaidic acid, arachic acid, behenic acid and erucic acid and the technical mixtures thereof obtained, for example, in the pressure hydrolysis of natural fats and oils. Technical C
12/18
coconut fatty acids and, in particular, partly hydrogenated C
16/18
tallow or palm oil fatty acids and C
16/18
fatty acid cuts rich in elaidic acid are preferably used. To produce the esters, the fatty acids and the triethanolamine may be used in a molar ratio of 1.1:1 to 3:1. With the performance properties of the esters in mind, a ratio of 1.2:1 to 2.2:1 and preferably 1.5:1 to 1.9:1 has proved to be particularly advantageous. The preferred fatty acid triethanolamine esters are technical mixtures of mono-, di- and triesters with an average degree of esterification of 1.5 to 1.9 and are derived from technical C
16,18
tallow or palm oil fatty acid (iodine value 0 to 40). In performance terms, fatty acid triethanolamine ester salts corresponding to formula (I), in which R
1
CO is an acyl group containing 16 to 18 carbon atoms, R
2
has the same meaning as R
1
CO, R
3
is hydrogen and m, n and p stand for 0 have proved to be particularly advantageous.
Besides the fatty acid triethanolamine esters, other suitable antistatic agents are esters of fatty acids with diethanolalkyamines corresponding to formula (II):
in which R
1
CO is an acyl group containing 6 to 22 carbon atoms, R
2
is hydrogen or has the same meaning as R
1
CO, R
4
is an alkyl group containing 1 to 4 carbon atoms and q and r together stand for 0 or numbers of 1 to 12.
Finally, a third group of suitable trialkanolamine esters are the esters of fatty acids with 1,2-dihydroxypropyl dialkylamines corresponding to formula (III):
in which R
1
CO is an acyl group containing 6 to 22 carbon atoms, R
2
is hydrogen or has the same meaning as R
1
CO, R
4
and R
5
independently of one another are alkyl groups containing 1 to 4 carbon atoms and s and t together stand for 0 or numbers of 1 to 12. So far as the choice of the preferred fatty acids and the optimal degree of esterification are concerned, the examples mentioned for (I) also apply to the alkanolamine esters corresponding to formulae (II) and (III).
Partial Glycerides
In another preferred embodiment of the invention, the fatty acid alkanolamine esters are used together with lubricants of the partial glyceride type which produce a synergistic improvement in color stability. Partial glycerides, i.e. monoglycerides, diglycerides and technical mixtures thereof may still contain small quantities of triglycerides from their production. The partial glycerides preferably correspond to formula (IV):
in which R
5
CO is a linear or branched, saturated and/or unsaturated acyl group containing 6 to 22 and preferably 12 to 18 carbon atoms, RT and R
8
independently of one another have the same meaning as R
6
CO or represent OH and the sum (v+w+x) is 0 or a number of 1 to 100 and preferably 5 to 25, with the proviso that at least one of the two substituents R
6
and R
7
represents OH. Typical examples are mono- and/or diglycerides based on caproic acid, caprylic acid, 2-ethylhexanoic acid, capric acid, lauric acid, isotridecanoic acid, myristic acid, palmitic acid, palmitoleic acid, stearic acid, isostearic acid, oleic acid, elaidic acid, petroselic acid, linoleic acid, linolenic acid, elaeostearic acid, arachic acid, gadoleic acid, behenic acid and erucic acid and technical mixtures 1,1, thereof. Technical lauric acid glycerides, palmitic acid glycerides, stearic acid glycerides, isostearic acid glycerides, oleic acid glycerides, behenic acid glycerides and/or erucic acid glycerides which have a monoglyceride content of 50 to 95% by weight and preferably 60 to 90% by weight are preferably used. The ratio by weight between the trialkanolamine esters and the partial glycerides may be in the range from 90:10 to
Cain Edward J.
Cognis Deutschland GmbH & Co..KG
Ettelman Aaron R.
Ortiz Daniel S.
Trzaska Steven J.
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