Antistatic polymeric compositions

Details Antistatic polymeric compositions Antistatic polymeric compositions

1999-06-03

2002-02-05

Yoon, Tae H. (Department: 1714)

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...

C524S306000, C524S310000, C524S320000, C524S322000, C524S910000, C523S136000

Reexamination Certificate

active

06344507

ABSTRACT:

This invention relates to the use of surfactant compounds and compositions, particularly those based on esters of fatty acids, especially esters of polyhydroxylic compounds and branched fatty acids, as antistatic agents additives in polymeric, particularly polycarbonate, resins.
Polycarbonate resins are a widely used class of engineering polymer and are usually based on repeat units of a carbonate ester of a dihydroxyl aromatic compound most usually including a 1,4-phenylene (para-phenylene) group, and commonly of a bisphenolic compound such as Bisphenol A, 2,2-bis(4-dihydroxyphenyl)propane. As well as being strong and tough, polycarbonates can be fabricated as optically clear components e.g. in spectacles—polycarbonate resins are frequently used in protective spectacles and goggles even where there is no optical support for poor sight—and as windows. Polycarbonate resins are typically good insulators—they are used as dielectric materials in capacitors—and static charge on such resin surfaces may not disperse readily. Where polycarbonate resin is exploited solely for its strength and toughness, it is possible to render it anti-static by using ionic materials to increase its effective conductivity, but generally these additives give rise to opacity e.g. as haze, or discolouration e.g. as yellowing, in the compounded resins and are thus not suitable for applications where optical clarity is important. Hydrophilic antistatic agents have not generally proved to be effective in polycarbonate resin systems and in any case frequently give rise to haze, yellowing or other opacity and would thus be of limited value even if effective.
The present invention is based on the discovery that good antistatic properties can be obtained in polycarbonate resins by using esters of branched fatty acids and polyhydroxylic compounds as antistatic agents. In contrast, we have found that esters of non-branched fatty acids and polyhydroxylic compounds are much less effective as antistatic additives in polycarbonate resins.
Accordingly, the present invention provides a polycarbonate resin containing one or more esters of at least one branched fatty acid and at least one polyhydroxylic compound in an amount to provide effective antistatic activity. The invention includes the use of such esters as antistatic agents in polycarbonate resins and in particular polycarbonate resins fabricated as optically clear components such as sheets or lenses.
The term “polyhydroxylic compound” is used to refer to compounds which have two or more hydroxyl groups and which when made into esters for use in this invention retain at least one free hydroxyl group.
The antistatic agents used in this invention are esters of branched fatty acids. The fatty, usually alkyl, residue of the fatty acid is a relatively hydrophobic group which provides satisfactory compatibility with the polymer resin. Typically the branched fatty acids contain at least about 8 carbon atoms. Lower molecular weight acids generally have esters that are either not sufficiently compatible with or are too readily removed from the polymer resin to be satisfactory as antistatic agents. Desirably, the branched fatty acid contains at least 12, and more usually at least 14, carbon atoms. The branched fatty acid may contain up to 30 carbon atoms, but usually not more than 22, and more usually not more than 20, carbon atoms because such acids are not readily available and their use does not appear to give any particular advantage.
Accordingly, particularly desirable esters of branched fatty acids for use in the present invention include those of the formula (I):
R
1
—CO
2
—R
2
  (I)
where
R
1
is a branched C
11
to C
21
, particularly C
13
to C
19
, aliphatic hydrocarbyl group, desirably an alkyl group;
R
2
is the residue of a polyhydroxyl compound including at least one free hydroxyl group.
Within formula (I) the group R
1
is desirably a branched alkyl group and within the C
11
to C
21
range given in formula (I), R
1
is desirably a branched C
13
to C
19
alkyl, especially a branched C
15
to C
19
alkyl, group.
The invention accordingly specifically includes polycarbonate resin containing one or more esters of the formula(I) in an amount to provide effective antistatic activity; and the use of esters of the formula(I) as antistatic agents in polycarbonate resins and in particular polycarbonate resins fabricated as optically clear components such as sheets or lenses.
Typically, the fatty acids, containing such aliphatic hydrocarbyl groups, which are used in the esters used in the invention are derived from natural sources or distillation cuts and typical commercially available materials are mixtures of compounds with a spread of chain lengths. The carbon chain lengths referred to herein are average chain lengths.
The fatty acids used in the invention are branched chain acids, more usually fatty acids having a branched alkyl chain. The branching can be at various positions along the chain for example near the carboxyl function, e.g. at the 2- or 3-position, particularly at the 2-position, or more remote from the carboxyl function e.g. about half way along the chain—corresponding to about position 9, for example from position 6 to position 12, for a C
18
alkyl group.
Generally, the fatty acids have a main chain and a branch off the main chain which is relatively short compared with the main chain. Commonly the branching can be a lower alkyl group, particularly a C
1
to C
4
alkyl group and especially a methyl or ethyl group. A particularly useful type of branched fatty acids are methyl and/or ethyl branched fatty acids. The use of such lower alkyl, especially methyl, branched fatty acids, forms a specific aspect of this invention.
Particularly suitable esters include those commercially available as esters of so-called iso-stearic acid. The commercial product iso-stearic acid is a mixture of acids having from 14 to 22, with about 2/3 having 18, carbon atoms, including short, mainly methyl but also including some ethyl, side chains, branching from the main chain mainly in the middle of the chain, typically about the 9-position e.g. from about the 6-position to about the 12-position, in an 18 carbon molecule. The assay molecular weight (e.g. by acid number) is close to that of stearic acid. “Iso-stearic acid” is a co-product (after separation and hydrogenation) from the manufacture of so-called “dimer acids” from C
18
unsaturated (mainly oleic and linoleic) fatty acids by catalytic thermal polymerisation.
Branched fatty acids for ester antistatic additives used in the invention include those of the formula (IIa):
[CH
3
.(CH
2
)
n1
][CH
3
.(CH
2
)
m1
].CH.(CH
2
)
p1
.COOH  (IIa)
where
n1 is from 4 to 10, particularly from 6 to 8;
m1 is from 0 to 5, particularly 0 to 3 and especially 0;
p1 is from 4 to 10; particularly from 6 to 8; and
desirably n1+m1+p1 is from 10 to 18, particularly 12 to 16.
Branched acids within this group include those derived from natural sources e.g. animal or vegetable fats and waxes, particularly by reactions on unsaturated fatty acids e.g. oleic acid (octadec-9-enoic acid), to introduce branching at or near the site of unsaturation in the starting acid. Commercially available iso-stearic acid is an example of a fatty acid of the formula (IIa), in practice a mixture of fatty acids of this formula.
Further branched fatty acids for ester antistatic additives used in the invention include those of the formula (IIb):
[CH
3
.(CH
2
)
n2
][CH
3
.(CH
2
)
m2
].CH.(CH
2
)
p2
.COOH  (IIb)
where
n2 is from 6 to 18, particularly from 10 to 16, especially about 14;
m2 is from 0 to 5, particularly 0 to 3;
p2 is from 0 to 3, particularly 0 to 2; and
desirably n2+m2+p2 is from 10 to 18, particularly 14 to 16.
Such branched acids can be derived from synthetic sources e.g. by oxidation of alcohols made by the OXO reaction on internal linear olefins (where p2 is 0); on branched (typically 1-) olefins (where p2 depends on the position of branching in the alkyl group);

Affiliated with

Also associated with

Rating

Antistatic polymeric compositions does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Antistatic polymeric compositions, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Antistatic polymeric compositions will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2961018