Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K5/00—Use of organic ingredients
  • C08K5/16—Nitrogen-containing compounds
  • C08K5/17—Amines; Quaternary ammonium compounds
  • C08K5/19—Quaternary ammonium compounds

Definitions

• This invention relates to resilient solid compositions .
• the invention relates to synthetic thermoplastics material compositions which have a controlled level of electrical conductivity. Such compositions are useful, inter alia, in the production of the soles for footwear and as solid floor covering materials.
• a conductive synthetic plastics material composition comprising a high molecular weight thermoplastics material comprising a segmented copolymer/ester polymer, preferably one containing intra-polymerised butylene terephthalate hard segments, and polytetramethylene ether terephthalate soft segments and, as a conductivity promoting component, a quaternary ammonium compound such that when moulded or shaped to give a resilient shaped article, the composition has an electrical resistance which is preferably no greater than 1 ⁇ 10 ohms and which is no less than 5 ⁇ 10 ohms when measured according to British
• the invention also extends to a method of making a synthetic plastics material composition electrically conductive, which comprises incorporating a quaternary ammonium compound within the composition before moulding or shaping so as to disperse the quaternary ammonium compound throughout the composition followed by moulding or shaping the composition to give an electrically conductive article.
• the invention also extends to anti-static articles e.g. soles for shoes, tiles for the floor, conveyor belts, gear wheels and other items such as those mentioned in
• British Standard BS 2050 made by moulding or otherwise shaping the article from such compositions.
• an anti-static article of footwear at least the sole of which comprises a conductive synthetic plastics material composition as described above.
• the article of footwear can be of any type such as a shoe, a plimsoll, a Wellington, a half-Wellington, an ankle boot or an overshoe.
• covering the sole may be a liner or inner-sole of cellulose fibre material, e.g. that known as Texon or Bontex which, although highly resistive in itself, readily absorbs moisture from the foot of the user and so rapidly becomes electrically conductive when in use and so provides a good electrical connection between the foot and the sole.
• the segmented copolyether/ester can consist essentially of a multiplicity of recurring long chain ether/ester units and short chain ester units joined head to tail through ester linkages and having the following general formula:
• G is a divalent radical remaining after the removal of terminal hydroxyl groups from a poly (C 2-10 alkylene oxide) glycol having a molecular weight of about 350 to 6,000; R is a divalent radical remaining after removal of carboxyl groups from an aromatic dicarboxylic acid having a molecular weight less than about 300; and D is a divalent radical remaining after removal of hydroxyl groups from an alkyldiol having a molecular weight less than about 250; a and b are integers such that the short chain units represented by a comprise from 50 to 90 percent by weight of the composition; and n is the degree of polymerization.
• G may be derived from poly (C 2-10 alkylene oxide) glycol having a molecular weight of about 350 to 6,000; R is a divalent radical remaining after removal of carboxyl groups from an aromatic dicarboxylic acid having a molecular weight less than about 300; and D is a divalent radical remaining after removal of hydroxyl groups from an alkyldio
• (tetra-methyleneoxide) glycol e.g. of molecular weight of about 1,000
• D 1,4-butanediol
• R from a phthalic acid and is, for example, terephthaloyl, isophthaloyl, orthophthaloyl or mixtures thereof.
• thermoplastics material for use in accordance with the present invention may be prepared from the segment copolyether/ester compositions disclosed in U.S. Patent No.
• copolyetheresters of this invention are prepared by reacing one or more dicarboxylic acids or their ester-forming derivatives, one or more difunctional polyethers with the formula:
• R is one or more divalent organic radicals a p is an integer of a value to provide a glycol with a molecular weight of between about 350 and about 6,000), and one or more dihydroxy-compounds selected from the class consisting of bis-phenols and lower aliphatic glycols with the formula:
• the preferred thermoplastics material contains (a) intra-polymerised butylene terephthalate hard segments of molecular weight 220 and (b) polytetramethylene ether terephthalate soft segments of molecular weight 1132. They can be prepared by polymerising 1,4-butanediol terephthalic acid and polytetramethylene ether glycol. The relative proportions of (a) to (b) determines the hardness or stiffness of the final product since the hard crystalline blocks give strength whilst the soft amorphous segments give flexibility without the need for a plasticizer.
• thermoplastics material in which a is an integer such that the segments represented by (a) comprise from 50 to 90% by weight of the total copolymer, b is an integer such that the segments represented by (b) comprises 50 to 10% of the total copolymer, and x is an integer reflecting the molecular weight of the ether glycol, e.g. ⁇ is 14 for a molecular weight of (b) of about 1,000.
• thermoplastics polymers are highly resilient have an outstanding resistance to flex cut growth at both lo and high temperatures, have good compressive and tensile stress characteristics compared with polymers of similar hardness, have good abrasion resistance, have little hysteresis loss in dynamic applications, have good creep resistance, are resistant to beta radiation and are resistance to hydrolysis in hot water and to mildew and fungus attack.
• They can also be extruded, injection moulded, blow or roto moulded and melt cast so that they can readily be shaped for any particular use.
• thermoplastics material is the thermoplastic polyester elastomer sold under the trade name Hytrel by E.I. du Pont de Nemours & Co. Commercial grades of Hytrel cover hardness range of 92 Durometer on A scale equal to 40 on D scale, to 72 Durometer on D scale.
• Hytrels are available in a range including 5556, 4056, 5526, 5555 HS, 6346A, ND 7246, 6346 and 7246, the nomenclature being explained as follows: the first two digits are the polymer hardness on the D scale, the third digit designates viscosity (2 is a moulding grade, 4 and 5 are general purpose grades), and the last digit indicates the type of antioxidant (5 is discolouring and 6 is non- discolouring).
• Particulate fillers may be included and the filler is desirably one which will enhance the conducting action of or be synergistic with the quaternary ammonium compound.
• An example of a filler is a finely divided aluminium silicate, e.g. Silteg AS7 as available from Degussa. Addition of excess fillers should generally be avoided, however, to avoid degradation of the mechanical preperties of the moulded product.
• the composition of the invention is particularly useful in the manufacture of soles for anti-static footwear, and anti-static flooring since the composition is neither an insulator nor a good conductor. Instead, it has a controlled level of low conductivity sufficient to allow leakage away of static electricity charges but insufficient to allow a person to receive serious electric shocks if he should touch a source of live electricity.
• the composition is also useful in the production of such high pressure moulded articles as solid rubber rollers or trolley wheels where there is a requirement for the use of an anti-static composition to eliminate static charges.
• the component used in the composition of the invention to give this controlled resistivity conductivity should be a compound which is not abrasive so that when moulding the compositions they do not cause rapid wear of moulds and dyes. Carbon black and graphite are not suitable therefore and in addition the carbon compounds have a propensity to leave unsightly marks on flooring when used in soles. Further, particulate conductive fillers tend to stratify into layers when compositions are vulcanised or moulded so giving very erratic conductivities.
• compositions according to the invention need not be dark coloured so one can add colouring compositions or dyes to the compositions of the invention to give them whatever colour is required.
• Suitable quaternary ammonium compounds appear to be those which contain a long chain fatty acid residue such as a stearyl group and also an amine group and an example of a quaternary ammonium compound which has been found to be effective is stearamidopropyldimethyl-3-hydroxyethyl-ammonium nitrate, i.e.
• This compound is available under the Trade Mark Cyastat SN from Cyanamid Company as a solution in aqueous isopropanol and as such is suitable for incorporation into the thermoplastics material.
• Another quaternary ammonium compound which can be used is N,N-bis(2-hydroxyethyl)-N-(3'-dodecyloxy-2'-hydroxypropyl)methylammonium methosulphate which is available from American Cyanamid Company under the trade name "Catanac 609" in the form of a 50% solution in isopropyl alcohol/water mixture.
• the amount of the quaternary ammonium compound to be added in a particular case can readily be found by simple experiment.
• the addition of a few percent such as 0.5 or 1 to 10%, preferably 1 to 7%, and more preferably 1 to 3%, and most preferably 1 to 2%, by weight of the compound to the composition will usually be found to give a resistance in or near the range required.
• the resistance of the material be towards the upper limit of resistance rather than towards the lowe limit.
• the quaternary ammonium compound needs to be well mixed and dispersed throughout the mass of the composition and not merely sprayed on or caused to migrate to the surface of the composition.
• the addition of the quaternary ammonium compound to the thermoplastics material significantly lowers the inherent resistance of the thermoplastics material and the precise mixture used can be chosen with particular quaternary ammonium compounds and particular thermoplastics to give a conductivity for a product as specified in BS 2050. This is in contrast to the very high inherent resistance of the thermoplastics material sold as Hytrel, see for example Table 2 in the article "New Developments in Copolyester ether elastomers" by Robert P. Kane in Journal of Elastomers and Plastics, Vol. 9 (October 1977). starting at page 416. Further, the test performed according to BS 2050 demonstrates a conductivity through the mass of the material and not a mere surface effect.
• Hytrel 5556 powder as obtained from Du Pont was moulded in a sheet mould at 1000 psi (7.0307 ⁇ 10 5 kg/m 2 ) for 10 mins at 180°C.
• Example I was repeated except that the thickness of the moulded sheet was incresed to 6mm so that the effect of sample thickness on volume resistivity could be checked.
• the resulting sheets were tested for their electrical resistance according to BS 2050 at 500 V using the liquid electrodes of the form of Clause A4.2.
• Example I was again repeated except that a red pigment was incorporated, and that the Cyastat SN was mixed with the Hytrel 5556 on a warm mill to ease difficulty of mixing and thereafter the pigment was added to the resulting lumps and mixed in a, Kenwood mixer.
• Example I was again repeated and both a pigment and an aluminium silicate filler (Degussa Silteg AS7) were added under the same conditions as in Example III.
• a pigment and an aluminium silicate filler (Degussa Silteg AS7) were added under the same conditions as in Example III.
• Premixes were prepared usind tumbler mixing.
• H40 required a higner temperature because of granular form.
• Blanks of correct weight were loaded into the 3mm sheet mould and pressed at 60 ar" for 10 min.

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• Chemical & Material Sciences (AREA)
• Health & Medical Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Medicinal Chemistry (AREA)
• Polymers & Plastics (AREA)
• Organic Chemistry (AREA)
• Compositions Of Macromolecular Compounds (AREA)
• Footwear And Its Accessory, Manufacturing Method And Apparatuses (AREA)
• Conductive Materials (AREA)

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Citations (3)

• 1981
  • 1981-11-24 EP EP81305549A patent/EP0055894A3/en not_active Withdrawn
  • 1981-11-24 JP JP56503651A patent/JPS57502059A/ja active Pending
  • 1981-11-24 WO PCT/GB1981/000257 patent/WO1982001887A1/en not_active Ceased

Patent Citations (3)

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