Patent GB-369945-A (GB)
Title: Improvements in coated or impregnated materials
IPC: H01B7/02
Filed: 1930-12-24
Abstract: Fabrics, films, tapes, ribbons, sheets or other materials comprising an organic derivative of cellulose are coated or impregnated with a water-resistant polymerized vinyl compound or with a composition containing the same.  The polymerized vinyl composition preferably contains a plasticizer in the proportion of more than 10 per cent, for example 20-30 per cent up to 100 or 150 per cent.  The coated or impregnated materials are suitable for electric insulation; for this purpose plasticizers consisting of phenolic bodies or esters or ethers of phenolic bodies are preferably used.  Examples of suitable plasticizers are hydroxy derivatives of diphenyl-, triphenyl- and tetraphenyl-methanes, ethanes and paraffins generally, and the homologues and substitution products thereof, especially the dioxy diphenyl-, triphenyl-, or tetraphenyl methane plasticizers having the general formula <FORM:0369945/III/1> where R1 and R2 may be hydrogen or any alkyl group, or halogen derivatives thereof or aryl groups such as C6H5, or aralkyl groups such as C6H5-CH2, and R3 and R4 may be hydrogen or halogens or carboxyl groups or hydrocarbon radicles, e.g. methyl, ethyl or phenyl, benzyl or other aryl or aralkyl radicles, or halogen substitution products of hydrocarbon radicles. Other suitable plasticizers are hydroxy-benzophenones, e.g. 4-hydroxybenzophenone, dihydroxy benzophenones and dimethyl derivatives thereof; compounds of the general formula <FORM:0369945/III/2> where R1, R2 and R3 may be hydrogen or a hydrocarbon radicle or chlorine or other halogen derivatives of hydrocarbon radicles, e.g. tertiary butyl phenol; diphenols, e.g. 4,4<1>-dioxy diphenyl and homologues thereof; and the organic or inorganic esters or ethers of any of the above or of other phenolic compounds, for instance the acetyl, salicylyl and phosphoric esters and methyl ethyl and benzyl ethers.  Of particular value are the acetyl esters and the methyl ethyl and benzyl ethers of the phenols of the oxy-diphenyl, triphenyl and tetraphenyl methane, ethane or other paraffin type above mentioned.  Phosphoric esters of phenols, cresols, xylenols, naphthols and their homologues and substitution products, particularly tricresyl and triphenyl phosphates, are suitable plasticizers.  Furfural-acetone and benzal-acetone may be used as plasticizers.  Other plasticizers, e.g. the sulphonamide tartrate and phthalate plasticizers, triacetin, &c. may be used.  The proportion of plasticizer should not be less than 10 per cent of the polymerized vinyl compound, and is preferably from 20 to 30 per cent, but may be up to 150 per cent or more.  Natural or artificial resins may be added to the composition, in which case the amount of plasticizer can be increased without the product becoming sticky. Shellac and Kauri resin are suitable; synthetic resins used should not be liable to further condensation when heated.  Phenolaldehyde resins obtained in the presence of plasticizing agents are suitable. One suitable resin is that obtained by the condensation of formaldehyde with diphenylol propane or with the crude condensation product of phenol and acetone.  Resins formed by the condensation of diphenylol propane with furfural or other aldehydes, or of furfural, formaldehyde or other aldehydes with other condensation products of ketones, and phenols, may be used.  Other resinous products are those obtained from phenols, cresols, xylenols, resorcin and pyrocatechin and aliphatic or cyclo-paraffin ketones; from furfural, benzaldehyde and other aldehydes and ketones; from phenols, cresols and xylenols by condensation with chloracetone, furfural, allyl alcohol and other allyl compounds (as described in Specifica365,093), sulphur chloride, acetaldehyde, croton aldehyde, keto-butanol and chloral; from formaldehyde and benzene, toluene or xylene sulphonamides from furfural and aniline; and from phenoxy-acetone.  In some cases, intermediate condensation products may be used as plasticizers, and the corresponding resin also used in the composition; e.g. diphenylol propane and an acetone phenol resin may be used as plasticizer and resin respectively.  In such cases it is not necessary to separate and purify the plasticizer; it is however, desirable to separate excess reactants, e.g., phenol.  In the preparation of the synthetic resins, e.g., phenol aldehyde resins from simple or complex phenols and formaldehyde or its polymers such as trioxymethylene, or benzaldehyde furfural &c., or other compounds containing methylene groups, or the acetals, the condensation is preferably carried out in the presence of triphenyl or tricresyl phosphate or other plasticizer, so that overcondensation is prevented.  The plasticizer may be present only in the later stages of the condensation process. Polymerized vinyl acetate is preferably used in the composition, but other polymerized vinyl compounds may be used which are derivatives of polymerized vinyl alcohol and its homologues and substitution products in which the hydroxy groups are substituted by groups such as ester or ether groups which make the compound resistant to water. Preferably ester groups of organic acids are used, such groups not containing free hydroxy or free carboxy groups.  The compositions may be mixed with other suitable ingredients, and dissolved in volatile solvents e.g. benzene, alcohol and butyl acetate, or applied in molten condition. Pigments, dyes, fillers, or cellulose esters or ethers in solution or in finely divided state may be added.  The composition may be applied by spraying or brushing, by passage through a bath or by extrusion.  Electric conductors may be coated with the compositions and then wrapped with tape, fabric, &c., and if desired, warmed.  They may also be employed for decorative purposes; the transparency may be varied according to the amount of composition applied, so that a small amount may be applied to form an opaque ground and a further amount applied e.g., through stencils, to produce transparent designs.  The fabric may be previously dyed, and differently coloured compositions may be used.  In examples: 1. A cellulose acetate woven fabric is coated with a composition containing polymerized vinyl acetate, diphenylol propane-formaldehyde resin, tricresyl phosphate, alcohol and acetone.  It is then dried, preferably at 100 to 120 DEG  C. for some hours, and cut into strips for winding on electric conductors.  2. A composition as in Example 1 but containing shellac in addition is used as in the previous example.  3. A composition comprising polymerized vinyl acetate, a diphenylol propane-formaldehyde resin containing tricresyl phosphate prepared as described above, and diphenylol propane, is applied in fused form at 160-180 DEG  C. to a cellulose acetate fabric.  4. A composition containing polymerized vinyl acetate, a cresol-formaldehyde resin and tricresyl phosphate mixture prepared as before described, and tricresyl phosphate, is dissolved in alcohol and applied as in Example 1.  5. A composition containing polymerized vinyl acetate, shellac, diphenylol propane-formaldehyde resin, diphenylol cyclohexane, triphenyl phosphate, filler (e.g. silica powder) acetone and butyl acetate is used as in Example 1.  6. Another composition consists of polymerized vinyl acetate, triphenyl phosphate and alcohol.  7. A composition consisting of polymerized vinyl acetate, diphenylol cyclohexane-formaldehyde resin, crude diphenylol propane, tricresyl phosphate, acetone, alcohol, and butyl acetate, is used to coat a conductor which has been covered with fabric or tape.  8. A film of cellulose acetate is coated with any of the compositions described above, dried, cut into strips and wound on an electric conductor.  Specification 346,267, [Group IV], is referred to.ALSO:Fabrics, tapes, ribbons, or other materials comprising an organic derivative of cellulose are coated or impregnated with a water-resistant polymerized vinyl compound or with a composition containing the same.  The polymerized vinyl composition preferably contains a plasticizer in the proportion of more than 10 per cent, for example 20-30 per cent up to 100 or 150 per cent.  The coated or impregnated materials are suitable for electric insulation; for this purpose plasticizers consisting of phenolic bodies or esters or ethers of phenolic bodies are preferably used. Examples of suitable plasticizers are hydroxy derivatives of diphenyl-, triphenyl-, and tetraphenylmethanes, ethanes and paraffins generally, and the homologues and substitution products thereof, especially the dioxy diphenyl-, triphenyl- or tetraphenyl methane plasticizers having the general formula <FORM:0369945/IV/1> where R1 and R2 may be hydrogen or any alkyl group, or halogen derivatives thereof, or aryl groups such as C6H5, or aralkyl groups as C6H5CH2, and R3 and R4 may be hydrogen or halogens or carboxyl groups or hydrocarbon radicles, e.g. methyl ethyl or phenyl, benzyl or other aryl or aralkyl radicles, or halogen substitution products of hydrocarbon radicles. Examples of this class are, diphenylolmethane, diphenylolethane, diphenylolpropane, diphenyloloctane, dioxytriphenylmethane, dioxytriphenylethane, dioxytetraphenylmethane, trichlor-methyl-diphenylolmethane, diphenylolcyclohexane, diphenylol-methyl-cyclohexane, tetra-brom-diphenylol-propane, 4,4<1>-dioxy-diphenyl - methane - 3,3<1> - dicarboxylic acid, diphenyl- or dibenzyl-diphenylolpropane, dimethyl - diphenylolpropane, methylene - di - b  - naphthol, a -b -diphenyl-a -b -diphenylolethane, aurin, leuco-aurin, o-p<1>-p"-trihydroxy-triphenyl carbinol and mixtures of trihydroxy-triphenylcarbinols produced by condensation of phenol and carbon tetrachloride in presence of aluminium chloride and like condensing agents followed by hydrolysis.  Other suitable plasticizers are hydroxy-benzophenones, e.g. 4-hydroxy-benzophenone, dihydroxy-benzophenones and dimethyl derivatives the