CA2146715A1

CA2146715A1 - Plastic molding composition treated with an antistatic agent

Info

Publication number: CA2146715A1
Application number: CA002146715A
Authority: CA
Inventors: Michael Breitwieser; Wolfgang Wanzke; Reinhard Vybiral
Original assignee: Individual
Current assignee: Hoechst AG
Priority date: 1994-04-11
Filing date: 1995-04-10
Publication date: 1995-10-12
Also published as: JPH0848811A; ZA952929B; EP0676444A3; AU1627295A; DE4412366A1; EP0676444A2; KR950032403A

Abstract

A plastic molding composition comprising a thermoplastic or thermoset plastic, which contains as antistatic agent a compound of the formula I

(I) where R1 is a saturated or unsaturated aliphatic hydro-carbon group having 8 or more carbon atoms, R2 is a C1-C6-alkyl group and R3 and R4 are identical or different and are each a symmetric or unsymmetric alkyl group, hydroxyalkyl group or polyoxyalkylene group, has a good antistatic treatment even when small amounts are used.

Molding compositions based on polyolefins, in particular, can be given a durable antistatic treatment by the novel application of the said compounds.

Description

214~71~

Ho~-H.~l ARTIEN~-R~RT-T-~ OEAFT HOE 94/F 090 Dr.DA/-Description Plastic molding composition treated with an antistaticagent The invention relates to the use of certain betaines as antistatic agent~ for thermoplastics, in particular polyolefins.

High volume resistance and surface resistivity have earned plastics an important position as insulating materials in the electrical and electronics sector.
However, in all processes of separation from other media, these same structure-dependent properties result in a strong electrostatic charging of the surface. This is undesirable for a variety of reasons:

15 - For the bulk of articles in daily use, the attrac-tion of dust during storage and use should be avoided on the grounds of esthetics and hygiene.

- In the processing of plastic parts having a large surface area, e.g. sheets, fibers or powders, static charging produces forces which interfere appreciably with the process. They can prevent the proper win-ding of calendered sheets or of fibers. During processing or on dispensing units, film webs can adhere to one another to an undesirable degree. In the conveying of powders, lump formation or bridging can occur. Also, the printability of finished parts is impaired by static charging.

- Discharging processes can result in damage to packed products.

30 - Spark discharge can cause severe accidents, e.g.
where there are dangers of fire and explosion when handling readily flammable gases, vapors and dusts, e.g. when using solvents or in mines.

Attempts are made in all these areas to reduce the chargeability of the plastic by means of suitable addi-tives.

The conductivity of plastics can be increased in three ways in order to avoid charging: surface application of an "external" antistatic agent from a solution, incor-poration of an "internal" (incorporable) antistatic agent into the plastic, or incorporation of electrically conductive additives (graphite, metals, organic semicon-ductors).

Electrically conductive additives are used if the surface resistance of the finished part is to be less than 108 Q.
Owing to the large amounts added of from 2 to 70%, the mechanical properties are impaired.

External and internal antistatic agents are chemicals which form a conductive film on the surface of the plastic, generally in conjunction with the atmospheric moisture. This can happen due to the production of a pure film of moisture by means of water-attracting substances or by the deposition of an organic electrolyte.

Both groups have a similar build-up principle: a hydrophobic end ensures the anchoring of the additive to the polymer surface and a strongly polar end absorbs water molecules which eliminate charges according to the principle of ion conductivity.

External antistatic agents are applied to the surface from aqueous or solvent-containing preparations. More or less all the surface-active compounds are effective, as are also numerous hygroscopic substances such as glycerol, polyols or polyglycols, which do not possess the characteristic of surface activity. In the case of 3 2l~7l5 - - -internal antistatic agents, the hydrophobic end of the molecule is firmly anchored in the bulk of the polymer.

The majority of known antistatic agents can be subdivided into cationic, anionic and nonionic compounds.

Cationic compounds generally consist of a bulky cation often contA;n;ng a long alkyl radical (e.g. a quaternary Ammo~;um, phosphonium or sulfonium salt), with it also being possible for the quaternary group to occur in a ring system (e.g. imidazoline). In most cases, the anion is the chloride, methylenesulfate or nitrate ion derived from the quaternization process. The quaternary ammonium saltæ, in particular, have gained acceptance as com-mercial products.

Cationic substances are most effective in polar polymers.
However, their use is restricted by their adverse effect on the thermal stability of certain polymers.

Anionic compounds have an anion (usually an alkylsul-fonate, alkylsulfate, alkylphosphate, dithiocarbamate or carboxylate) as the active part of the molecule. The cations used are frequently alkali metals or, more rarely, alkaline earth metals. In practice, sodium alkyl-8ul fonates, in particular, which develop a good antistatic action in polar polymers, have gained accep-tance. A disadvantage is that their use is limited to muted colorations because of their tendency to produce haze. On account of their very high melting range, sodium alkylsulfonates are often very difficult to incorporate homogeneously into the plastic to be treated, and their hydrophilic character makes storage and proportioning more difficult.

Nonionic compounds, for example polyethylene glycol esters or ethers, fatty acid esters or ethanolamides, monoglycerides or diglycerides or ethoxylated fatty amineæ, are uncharged surface-active molecules whose ~ 4 -21167 l5 polarity is substantially lower than that of the ionic compounds. Such products are usually liquids or waxy substances having a low softening range. Their low polarity and good compatibility makes representatives of these classes of compounds ideal internal antistatic agents for polyolefins. When used in large amounts, fatty acid esters of monohydric and polyhydric alcohols provide acceptable antistatic treatments, even in polar plastics, and make it possible to manufacture transparent moldings, in contrast to alkylsulfonates. Apart from the high use concentration required, which can lead to processing problems and affects mechanical and optical properties of the molding~, the sometimes pasty consistency of these products, with pour points above room temperature, has proven disadvantageous for the use of these products.

To assess the effectiveness of antistatic agents in molding compositions, there are, in particular, two suitable methods. In the measurement of the surface resistance in accordance with DIN 53482 (and since DecPmher 1, 93, DIN IEC 93 (VDE 0303 part 30)), the electrical resistance of the surface is measured by means of a special electrode. Most organic polymers, such as polyolefins, have natural surface resistances 2 1015 Q, correspo~;ng to an R0 value (= logarithm to the base 10 of the surface resistance) of R0 = 15. Molding compo-sitions which have surface resistances less than R0 = 11 (101l Q) are considered to have very good antistatic treatments. Even smaller R0 values are excellent. The second likewise very informative method, because it directly measures the phenomenon of charging/discharging of the ~urface, is the determination of the halflife.
Here, the time in which a charge applied to the surface of the test specimen drops to half the initial value is measured. Molding compositions having excellent antistatic treatments achieve halflives below 5 seconds.

Many ionic and nonionic substances which can be used as external or internal antistatic agents in plastics have already been described in the specialist literature.

Betaines have, inter alia, proven to be effective in principle. The antistatic action of alkyl betaines in polyolefins (cf. US 3,005,793) is known. Also known is the use of alkylaminoalkyl betaines as internal antistatic agents in polymers (cf. JP-Sho 44-13587).

In the use of the incorporable antistatic agents hitherto known, various disadvantages occur which become notice-able in the processing or the use of the treated plastic.
These include insufficient thermal stability, high melting range, a t~n~ency to haze formation, high use concentration and pasty consistency.

Materials having a longer-lasting action (for example ethoxylated fatty amines) often show an antistatic effect on the surface of polyolefins only after many days.
Substances which act rapidly because they rapidly migrate to the surface, on the other hand, usually cause a surface deposit which, for example, impairs the ability of the plastic to be written on or printed or to have a seal affixed. In addition, antistatic agents in many cases impair the color and, in the case of clear or translucent polymers, the transparency of the treated molding compositions.

It has now been found that certain alkylamidopropyl betaines develop an antistatic action in polyolefins unusually quickly, without resulting in disadvantageous surface effects.

The invention thus provides a plastic molding composition treated with an antistatic agent, comprising from 94 to 99.99% by weight, based on the molding composition, of a thermoplastic or thermoset plastic and from 0.01 to 6% by weight, based on the molding composition, of a compound of the formula I

6 21~67i~

R~

R1-CONH-R2N~-CN2-COO-(I) where Rl i8 a saturated or unsaturated aliphatic hydro-carbon group having 8 or more carbon atoms, R2 is a C1-C6-alkyl group and R3 and R4 are identical or different and are each a symmetric or unsymmetric alkyl group, hydroxyalkyl group or polyoxyalkylene group.

The plastic molding composition of the invention contains a thermoplastic or thermoset organic polymer, for example one of those listed below:

1. Polymers of monoolefins and diolefins, for example polyethylene of high, medium or low density (which may be uncrosslinked or crosslinked), polypropylene, polyisobutylene, polybut-1-ene, poly-methylpent-1-ene, polyisoprene or polybutadiene and also polymers of cycloolefins such as, for example, of cyclo-pentene or norbornene.

2. Mixtures of polymers specified under 1) for example mixtures of polypropylene with polyethylene or with polyisobutylene.

3. Copolymers of monoolefins and diolefins with one another or with other vinyl monomers, for example ethylene-propylene copolymers, propylene-but-1-ene copolymeræ, propylene-isobutylene copolymers, ethylene-but-1-ene copolymers, propylene-butadiene copolymers, isobutylene-isoprene copolymers, ethylene-alkyl acrylate copolymers, ethylene-alkyl methacrylate copolymers, ethylene-vinyl acetate copolymers or ethylene-acrylic 214671~

acid copolymers and their salts (ionomers), and also terpolymers of ethylene with propylene and a diene such as hexadiene, dicyclopentadiene or ethylidenenorbornene.

4. Polystyrene, poly(p-methylstyrene).

5. Copolymers of styrene or ~-methylstyrene with dienes or acrylic derivatives, for example styrene-butadiene, styrene-maleic anhydride, styrene-acrylonitrile, styrene-ethyl methacrylate, styrene-butadiene-ethyl acrylate, styrene-acrylonitrile-methacrylate; mixtures having high impact toughne~s ofstyrene copolymers and another polymer such as, for example, a polyacrylate, a diene polymer or an ethylene-propylene-diene terpolymer; and also block copolymers of styrene, for example styrene-butadiene-styrene, styrene-isoprene-styrene, styrene-ethylene/butylene-styrene or styrene-ethylene/propylene-styrene.

6. Graft copolymers of styrene, for example styrene on polybutadiene, styrene and acrylonitrile on polybuta-diene, styrene and maleic anhydride on polybutadiene, styrene and alkyl acrylates or alkyl methacrylates on polybutadiene, styrene and acrylonitrile on ethylene-propylene-diene terpolymers, styrene and acrylonitrile on polyalkyl acrylates or polyalkyl methacrylates, styrene and acrylonitrile on acrylate-butadiene copolymers, and also their mixtures with the copolymers specified under 5) which are known, for example, as so-called ABS, MBS, ASA or AES polymers.

7. Polyvinyl chloride.

8. Copolymers of vinyl chloride which can be pre-pared by known processes (for example, suspension, bulkor emulsion polymerization).

9. Copolymers of vinyl chloride with up to 30% by weight of comonomers such as, for example, vinyl acetate, 21~671~

vinylidene chloride, vinyl ether, acrylonitrile, acrylic esters, monoesters or diesters of maleic acid, or ole-fins, and also graft polymers of vinyl chloride.

10. Halogen-cont~;n;ng polymers such as, for example, 5 polychloroprene, chlorinated rubber, chlorinated or chlorosulfonated polyethylene, homopolymers and copolymers of epichlorohydrin, in particular polymers of halogen-containing vinyl compounds such as, for example, polyvinylidene chloride, polyvinyl fluoride, 10 polyvinylidene fluoride; and also their copolymers such as of vinyl chloride-vinylidene chloride, vinyl chloride-vinyl acetate or vinylidene chloride-vinyl acetate.

11. Polymeræ derived from cY,,~-unsaturated acids and their derivatives, such as polyacrylates and polymeth-15 acrylates, polyacrylamides and polyacrylonitriles.

12. Copolymers of the mor~o~ers specified under 11)with one another or with other unsaturated monomers, such as, for example, acrylonitrile-butadiene copolymers, acrylonitrile-alkyl acrylate copolymers, acrylonitrile-20 alkoxy acrylate copolymeræ, acrylonitrile-vinyl halide copolymers or acrylonitrile-alkyl methacrylate-butadiene copolymers.

13. Polymers derived from unsaturated alcohols and amines or their acyl derivatives or acetals, such as 25 polyvinyl alcohol, polyvinyl acetate, stearate, benzoate, maleate, polyvinyl butyral, polyallyl phthalate, poly-allyl melamine.

14. Homopolymers and copolymers of cyclic ethers such as polyethylene glycols, polyethylene oxide, 30 polypropylene oxide or their copolymers with diglycidyl etheræ.

15. Polyacetals such as polyoxymethylene, and also those polyoxymethylenes which contain comonomers such as, 214671~
g for example, ethylene oxide.

16. Polyphenylene oxides and sulfides and their mixtures with styrene polymers.

17. Polyurethanes derived from polyethers, polyesters and polybutadienes having terminal hydroxyl groups on the one hand and aliphatic or aromatic polyisocyanates on the other hand and also their precursors (polyisocyanate-polyol prepolymers).

18. Polyamides and copolyamides derived from diamines and dicarboxylic acids and/or aminocarboxylic acids or the correspo~;ng lactams, such as polyamide-4, polyamide-6, polyamide-6.6, polyamide-6.10, polyamide-11, polyamide-12, poly-2,4,4-trimethylhexamethylenetere-phthalamide, poly-m-phenyleneisophthalamide, and al~o their copolymers with polyethers, for example with polyethylene glycol, polypropylene glycol or polytetra-methylene glycol.

19. Polyureas, polyimides and polyamide-imides.

20. Polyesters derived from dicarboxylic acids and diols and/or from hydroxycarboxylic acids or the corres-po~; ng lactones, such as polyethylene terephthalate, polybutylene terephthalate, poly-1,4-dimethylolcyclo-hexane terephthalate, poly(2,2-bis(4-hydroxyphenyl)-propane) terephthalate, polyhydroxybenzoates, and also block polyether esters derived from polyethylene having hydroxy end groups, dialcohols and dicarboxylic acids.

21. Polycarbonates and polyester carbonates.

22. Polysulfones, polyether sulfones and polyether ketones.

23. Crosslinked polymers derived from aldehydes on the one hand and phenols, urea or melamine on the other lo 2116715 , hand, such as phenol-formaldehyde, urea-formaldehyde and melamine-formaldehyde resins.

24. Drying and nondrying alkyd resins.

25. Unsaturated polyester resins derived from copoly-esters of saturated and unsaturated dicarboxylic acidswith polyhydric alcohols, and also vinyl compounds as crosslinkers, as well as their halogen-cont~;n;n~, flame-resistant modifications.

26. Crosslinkable acrylic resins derived from substi-tuted acrylic esters, for example epoxy acrylates,urethane acrylates or polyester acrylates.

27. Alkyd resins, polyester resins and acrylate resins which are crosslinked with melamine resins, urea resins, polyisocyanates or epoxy resins.

28. Crosslinkable epoxy resins derived from poly-epoxides, for example from diglycidyl ethers or from cycloaliphatic diepoxides.

29. Natural polymers such as cellulose, natural rubber, gelatin and also their derivatives which are chemically modified in a polymer-homologous manner, such as cellulose acetates, propionates and butyrates, or cellulose ethers such as methylcellulose.

30. Mixtures of the abovementioned polymers such as, for example, PP/EPDM, polyamide-6/EPDM or ABS, PVC/EVA, PVC/ABS, PVC/MBS, PC/ABS, PBTP/ABS, PC/ASA, PC/PBT, PVC/CPE, PVD/acrylate, POM/thermoplastic PUR, POM/acrylate, POM/MBS, PPE/HIPS, PPE/polyamide-6.6 and copolymers, PA/ HDPE, PA/PP, PA/PPE.

31. Naturally occuring and synthetic organic materials which are pure mo~-ers or mixtures of mono-mers, for example mineral oils, ~n;~-l and plant fats, - - 11 214671~
oils and waxes, or oils, fats and waxes based on syn-thetic esters or mixtures of these materials.

32. Aqueous diRpersions o$ natural or synthetic rubber.

Preferred polymers are polyolefins such as, for example, polyethylene of various densities such as LDPE, MDPE, HDPE, LLDPE and polypropylene, and also polyRtyrene and polyvinyl chloride. Particular preference is given to the polyolefins.

As antistatic agent, the plastic molding composition of the invention contains a compound of the formula I

R~-CONIl-R2N~-CH2-COO
R~

( l ) where R1 is a saturated or unsaturated aliphatic hydro-carbon group having 8 or more carbon atoms, preferably a C8-C22-, in particular C12-C14-alkyl group, R2 is a C1-C6-, preferably C3-alkyl group and R3 and R4 are identical or different and are each a symmetric or unsymmetric alkyl group, hydroxyalkyl group or polyoxyalkylene group, but are preferably identical and are each a methyl group.

Particular preference is given to a betaine in which Rl is a fatty acid amidopropyl group. The preferred fatty acid is coconut fatty acid:

~ - 12 - 21~6715 CH

Rcoconut~C~N~CH2~CH2~CH2~N~~CH2-COO~
O ~1 CH~

The antistatic agent to be used according to the inven-tion iB preferably prepared by reaction of the sodium salt of monochloroacetic acid with fatty acid amido-propyldimethylamine. This also results in the formation of one mol of NaCl per mol of the betaine. The reaction is carried out in solution. The dry residue contains, for complete equimolar reaction, considerable amounts of NaCl.

If the synthesis of the alkylamidoalkyl betaine is carried out in aqueous solution, the water has to be removed prior to the preparation of the molding composi-tion treated with the antistatic agent, since the water interferes with processing. It has been able to be shown that alkylamidoalkyl betaine can also be prepared in the presence of other surfactants which serve as solvents in the synthesis and which in turn have an antistatic action. Such surfactants or surfactant-like materials are, for example, polyethylene glycols, polypropylene glycols, ethylene oxide/propylene oxide derivatives with or without a hydrocarbon radical, ethoxylated fatty acids, ethoxylated fatty alcohols and surfactant mix-tures, with or without the further addition of solvents.

Compounds of the formula I are known per se and some of them are commercially available. The commercial products here contain, apart from compounds of the formula I, further materials which may be present as a result of the synthesis. Typical is a content of from about 10 to 20%
by weight of NaCl. The NaCl content is advantageous to the antistatic action.

_ - 13 -Compounds of the formula I are often prepared in 801u-tion. The solvent can be water, 80 that the commercial product i8 often obtained in the form of an aqueous solution and is also sold in this form. The solution is suitable for direct application to finished parts, with the anti~tatic agent acting externally. In particular synthetic proces~es, the antistatic agent is obtained together with further substances, with the process allowing another antistatic agent to be used as solvent.
The formulation thus prepared can be used a~ a combina-tion antistatic agent.

Materials of the formula I can be mixed with other materials, for example with other antistatic agent~.

The antistatic agent to be used according to the invention is incorporated into the polymers using the customary methods. The incorporation can, for example, be carried out by m; Y; ng the compound and, if desired, further additives into the melt before or during shaping.
The incorporation can also be carried out by application of the dissolved or disper~ed compound directly onto the polymer or mixing into a solution, suspension or emulsion of the polymer, if desired allowing the solvent to subsequently evaporate. The amount to be added to the polymer is, for incorporation, from 0.01 to 6% by weight, preferably from 0.06 to 4% by weight, in particular from 0.1 to 3% by weight, based on the material to be treated.
The compound or formulation can al~o be added to the polymer to be treated in the form of a masterbatch or additive concentrate which contains from 2.5 to 70% by weight of the compound or formulation.

The plastic molding composition can additionally contain the customary additives such a~, for example, anti-oxidants, plasticizers, impact modifiers, processing aids and stabilizers, light ~tabilizer~, lubricant~, filler~, flame retardants, blowing agents, pigments, dyes or colorants and also other antistatic agents.

2146~15 _ It has been found that a certain amount of sodium chlor-ide in the alkylamidopropyl betaine gives a further significant improvement in the antistatic action, which becomes apparent in a lower surface resistance, a shorter halflife and a lower chargeability of the treated plastic part. Since NaCl alone in small amounts in molding compositions has hardly any antistatic action, but together with the alkylamidopropyl betaine gives better antistatic properties, there is obviously synergy between the two materials.

The plastic molding composition of the invention has the advantage that the antistatic action commences very quickly after processing. In comparison with the ethox-ylated alkylamines which are considered excellent, the antistatic treatment commences its action more quickly and for a low dosage gives effective prevention of dust attraction even on the day of production. A further advantage of the molding composition treated according to the invention is that the surfaces of the treated articles do not become moist by sweating out, as i~ the case for other antistatic agents. The surfaces remain able to have seals affixed, dry and printable. An import-ant advantage is the low dosage amount which is required to achieve the effect. The dosage amount is even less than that of the ethoxylated alkylamines, which are known as very effective, without possessing the same disadvan-tages as this class of materials, such as basicity, corrosivity or fish- toxicity. In comparison with sub-stances such as alkylsulfonates, fatty acid esters and others, the dosage of the substances to be used according to the invention in molding compositions is lower anyway.
In a practicable dosage, the substances to be used according to the invention lead to virtually no adverse effects on the color and the transparency of the molding composition. Certain alkylamidoalkyl betaines possess the additional advantage of being solids which, for example as ready-made spray-dried powder, can be metered into the molding composition to be treated in a technically simple 21~67i~

manner.

The following examples serve to illustrate the invention.

Examples In the following examples, antistatic agents of formula I were incorporated into plastic molding compositions.
The surface resistance in accordance with DIN 53482 and the halflife were determined on the test specimens produced from the molding composition. Some known, commercially available antistatic agents were used for comparison.

Representatives of substances of the formula I which were used were:

(A) Coconut amidopropyl betaine, product containing from about 15 to 20% of NaCl. 5 (Al) Product as in (A) but with the salt removed by extraction with ethanol (NaCl c2%).
(A2) Product as in (A), synthesized in ethoxylated coco-nut fatty alcohol as solvent remaining in the product.
(A3) Tallow/oleyl-(8:2)-amidopropyl betaine.

The comparisons used were:
(B) Ethoxylated fatty amine (N,N-bis(2-hydroxyethyl) coconut fatty amine).
(C) Fatty acid ester (D) Ethoxylated fatty acid amide (E) Lauryl betaine The antistatic properties of the pure technical polymer were measured after identical processing as a comparison.

The surface resistance was measured by the current/
voltage method. The measurement resistance here is 106-10l5 Q. The values given for the surface resistance and halflife are in each case means of at least six individual measurement values. The results were determined from the value of the logarithm of the surface resistance. Measurement values lying above the measurement range of 1015 Q were given the value 15 for the calculation of the mean. The halflife was monitored over 60 seconds. Measurement results in which the charge had not fallen to half of the initial charge within 60 seconds were given a value of 60 seconds in the averaging of the results. Thus, for the average halflives given, values above about 40 seconds are imprecise. If the halflife of all measurements was at least 60 seconds, the results were denoted by "~60n. The values in the following tables were measured at the indicated point in time after production of the test specimens. After production of the test specimens, these were stored and measured in a room having stAn~rd atmospheric conditions (temperature: 23C, relative atmospheric humidity 50%).

In addition, the yellowness index and the transparency were determined on the test specimens.

Example 1 Low-density polyethylene (LDPE) LDPE powder was mixed in a mixer (Papenmeier, type TLHK3) with the amounts shown in the table of the respective test substance for a mixing time of 3 minutes at ambient temperature. The mixture was granulated twice by means of an extruder (Leistritz LSM 30/34) (zones 1 to 7, tempera-tures: 150/155/160/170/180/190/190C). The maximum composition temperature during extrusion reached about 205C. The cooling of the extrudate prior to granulation was carried out in a waterbath. Plates were injection-molded from the granular materials thus obtained using an injection-molding machine (Windsor SP 50, zones 1 to 4, temperatures: 190/200/200/210C) at a composition tem-perature of about 220C. The thickness of the plates wa~

1 mm.

Table 1: Antistatic treatment of LDPE molding compoQi-tions with (A) and ~A1) On lRt day after On 7th day after production production Surface Half- Surface Half-resist- life resiQt- life ance ance Product Do~ageRO TimeRO Time [log Q] [~ec][log Q] [sec]
LDPE - ~ 14 ~ 60~ 14 ~ 60 (A) 0.2 9.6 3.39.4 ~ 1 (A1) 0.2 11.7 25.89.6 ~ 1 Table 2: Color and transparency of the test ~pecimeng (LDPE) Product Dosage Yellowness Index Transparency [%]

(A) 0.2 -0.3 44.1 (B) 0.2 2.8 40.9 Table 3: Comparison of various products, surface resist-ance and halflife (LDPE) On 1st day after On 7th day after production production Surface Half- Surface Half-resist- life resist- life ance ance Product Dosage RO TimeRO Time [log Q] [sec][log Q] ~sec]
LDPE - ~ 14 ~ 60~ 14 ~ 60 (A) 0.1 10.0 3.4 9.5 ~ 1 (A2) 0.1 13.4 41.8 9.8 2.3 (A3) 0.1 12.9 ~ 6011.7 6.1 (B) 0.1 11.4 5.2 9.7 ~ 1 (E) 0.1 ~ 14 ~ 60~ 14 ~ 60 Example 2 Production of test specimens from high-density polyethylene (HDPE) HDPE powder (density 0.96 g/cm3, MFI 190/2 7 g/10 min, MFI 190/5 25 g/10 min) was mixed in a mixer (Papenmeier, type TLHR3) with the amounts shown in the table of the respective test substance for a mixing time of 3 minutes at ~mhient temperature. The mixture was granulated twice by means of an extruder (Gottfert instrumented extruder, type 015, rheological screw 5/2, zones 1 to 3, tempera-tures 180/190/210C). The cooling of the extrudate prior to granulation was carried out in a waterbath. Plates were injection-molded from the granular materials thus obtained using an injection-molding machine (Windsor SP
50; zones 1 to 4, temperatures 190/200/200/210C) at a composition temperature of about 220C. The thickness of 214671~

the plates was 1 =.

Table 4: Surface resi~tance and halflife measured on HDPE molding composition~

On 1st day after On 14th day production after production Surface Half- Surface Half-resist- life resist- life ance ance Product Dosage RO Time RO Time ~log Q~ ~sec] ~log Q] ~sec]
HDPE - ~ 14 60 ~ 14 60 (A) 0.5 10.9 27 9.0 (A) 0.1 14.5 60 9.0 2 Example 3 Production of test specimens from polypropylene (PP) PP powder (MFI 230/5 3 g/10 min) was mixed in a mixer (Papenmeier, type TLHK3) with the amounts shown in Table 5 of the test substance for a ~;Y; ng time of 3 minutes at ambient temperature. The mixture was granulated twice by means of an extruder (Gottfert instrumented extruder, type 015, rheological screw 5/2, zone~ 1 to 3, tempera-tures 200/220/240C). The cooling of the extrudate prior to granulation was carried out in a waterbath. Plates were injection-molded from the granular materials thus obtained using an injection-molding machine (Windsor SP
50; zones 1 to 4, temperatures 200/210/210/220C). The thickness of the plates was 1 mm.

Table 5: Surface resistance and halflife measured on PP
molding compositions Surface resistance Halflife RO [log Q] Time [sec~
Pro- Dos- 1st 14th 52nd 1st 14th 52nd duct age day day day day day day PP ~ 14~ 14 ~ 14 ~ 60 ~ 60 ~ 60 (A) 1.0 10.0 9.1 8.6 c 1 _ ~ 1 (A) 0.5 15.010.7 - ~ 60 22 (C) 2.0 14.110.8 13.2 ~ 60 2 53 (D) 0.5 15.012.2 - ~ 60 25

Claims

1. A plastic molding composition treated with an antistatic agent, comprising from 94 to 99.99% by weight, based on the molding composition, of a thermoplastic or thermoset plastic and from 0.01 to 6% by weight, based on the molding composition, of a compound of the formula I

(I) where R1 is a saturated or unsaturated aliphatic hydrocarbon group having 8 or more carbon atoms, R2 is a C1-C6-alkyl group and R3 and R4 are identical or different and are each a symmetric or unsymmetric alkyl group, hydroxyalkyl group or polyoxyalkylene group.

2. A plastic molding composition as claimed in claim 1, containing as antistatic agent a compound of the formula I

(I) where R1 is a saturated or unsaturated aliphatic hydrocarbon group having 8 or more carbon atoms, R2 is a C1-C6-alkyl group and R3 and R4 are identical or different and are each a symmetric or unsymmetric alkyl group, hydroxyalkyl group or polyoxyalkylene group.

3. A plastic molding composition as claimed in claim 1, additionally containing antioxidants, plasticizers, impact modifiers, processing aids and stabilizers, light stabilizers, lubricants, fillers, flame retardants, blowing agents, pigments, dyes or colorants or other antistatic agents.

4. An antistatic agent consisting essentially of a compound of the formula I

(I) where R1 is a saturated or unsaturated aliphatic hydrocarbon group having 8 or more carbon atoms, R2 is a C1-C6-alkyl group and R3 and R4 are identical or different and are each a symmetric or unsymmetric alkyl group, hydroxyalkyl group or polyoxyalkylene group.