US3923505A - Recording material having an electroconductive layer comprising the reaction product of epihalohydrin with polyethylenemine - Google Patents

Abstract

Recording materials are described comprising a support of paper or of synthetic polymer and an electroconductive layer coated on at least one side of the support. This electroconductive layer has a surface resistance lower than 1011 Ohms/sq. and consists of or includes a major proportion of a polymer resulting from the reaction of epihalohydrin with polyethyleneimine in the presence of an organic tertiary amine. This polymer is soluble in water and is rendered insoluble by heating at about 100*C. The electroconductive layer may be used as an antistatic layer in a photographic silver halide recording material. When covered with a photoconductive coating the material may be used in electrophotographic recording. With an insulating layer applied thereon, the material may be used for electrographic recording.

Description

United States Patent 1 1 Timmerman et al.

[ 1 Dec. 2, 1975 Mortsel; Walter Frans De Winter, Berchem, both of Belgium [73] Assignee: Agfa-Gevaert N.V., Mortsel,

Belgium [22] Filed: June 15, 1973 [21] Appl. No.: 370,327

[30] Foreign Application Priority Data June 16, 1972 Germany 028432 [52] US. Cl. 96/l.5; 117/201; 117/218; 252/500; 260/2 BP [51] Int. Cl. G03G 5/04 [58] Field of Search 96/87 A, 114.2, 1.5-1.8; 117/201,- 218; 162/138; 252/500; 260/2.1 R.

[56] References Cited UNITED STATES PATENTS 3,210,299 10/1965 Hagge et al. 260/2.l R

3,479,215 11/1969 Cavagna et al7 117/201 3,640,766 2/1972 Jursich et a1 117/201 3,642,663 2/1972 Greer 252/500 3,784,489 l/l974 Dales et al. 260/2.l R

Primary Examiner-Roland E. Martin, Jr. Assistant Examiner-Judson R. Hightower Attorney, Agent, or Firm-William J. Daniel [57] ABSTRACT Recording materials are described comprising a support of paper or of synthetic polymer and an electroconductive layer coated on at least one side of the support. This electroconductive layer has a surface resistance lower than 10 Ohms/sq. and consists of or includes a major proportion of a polymer resulting from the reaction of epihalohydrin with polyethyleneimine in the presence of an organic tertiary amine. This polymer is soluble in water and is rendered insoluble by heating at about 100C. The electroconductive layer may be used as an antistatic layer in a photographic silver halide recordling material. When covered with a photoconductive coating the material may be used in electrophotographic recording. With an insulating layer applied thereon, the material may be used for electrographic recording.

9 Claims, N0 Drawings RECORDING MATERIAL HAVING AN ELECTROCONDUCTIVE LAYER COMPRISING THE REACTION PRODUCT OF EPIHALOHYDRIN WITH POLYETHYLENEMINE The invention relates to a recording material comprising a support of paper or of synthetic polymer, at least one surface of which is coated with a layer that may function as an electroconductive or as an antistatic layer.

Electroconductive substances are used in recording materials to carry off static charges. For instance, it is known that in normal photographic silver halide emulsion materials the usual synthetic film supports possess the property of being charged electrostatically, whereby the charged films strongly attract the surrounding dust and thereby become soiled at their surface. Moreover, latent discharge images on silver halide emulsions, which are applied to such film supports become visible upon development. Such an electrostatic charging is caused by quickly moving the film support or light-sensitive photographic material during rolling or unrolling in the coating, cutting, or packing machines and by making the film run through the camera and the projector. It is also known that the static charging can be reduced by coating the synthetic resin support with a conductive auxiliary layer.

In other recording materials such as for use in electrostatic printing an electrostatic charge is imparted to paper or other dielectric support in a predetermined pattern. The support is conductive or must be coated with a conductive layer. For instance, in an electrophotographic recording element a photoconductive layer stands in contact with an electroconductive layer or sheet, the latter being present for carrying off the electrostatic charges at the areas of the photoconductive layer undergoing an exposure to light rays.

In electrographic materials comprising an insulating layer whereon an electrostatic charge pattern is built up by image-wise or record-wise charging, e.g., by means of a modulated electron beam, the conductive element (support or layer) serves to apply a voltage thereto, thus making possible the formation of the electrostatic charge pattern applied to the insulating top layer.

In the following description and claims the general term recording material is intended to include the materials used in photographic processes and in electrographic and electrophotographic processes, for which applications the surface resistance of the electroconductive layer must not be higher than ohms per sq. at of relative humidity, although according to NAKAO, SAKOMOTO, and KATAGIRI at page 105 of the Preprints of the TAPPI, First Reprography Conference at St. Charles, 111., U.S.A., 1971 in electrophotography slight smudging of the back face of the support might already occur at resistance values higher than 4 X 10 ohms/sq.

Electroconductive layers for carrying off electrostatic charges may also be useful in recording elements wherein photosensitive semiconductor compounds are activated reversibly by electromagnetic radiation and wherein the activated patterns provide irreversible images by an oxidation-reduction chemical process.

The invention provides a recording material comprising a support of paper or synthetic polymer and an electroconductive layer coated on at least one side of said support, said electroconductive layer having a surface resistance lower than 10 ohms/sq. measured at 15% of relative humidity, said electroconductive layer consisting of or including a major proportion of a polymer resulting from the reaction of epihalohydrin with polyethyleneimine in the presence of an organic tertiary amine, said polymer being soluble in water and becoming insoluble by heating at about C.

The organic tertiary amine corresponds to the general formula:

wherein:

each of R R and (same or different) represents an alkyl group containing up to 5 carbon atoms, a cycloalkyl group or an aralkyl group, or

R R and R together with the nitrogen atom represent a heterocyclic compound such as pyridine, N-

alkylpiperidine, and N-alkylmorpholine.

Most suitable organic tertiary amines are trimethylamine and triethylamine.

Although the invention is restricted to the use of an epihalohydrin as epoxy com-pound, preferably epichlorohydrin, the epihalohydrin can as well be replaced by other compounds containing an epoxy group such as 1-chloro-3 ,4-epoxybutane, l-chloro l -methyl-2,3- epoxypropane, and 1-chloro-2-methyl-3,4-epoxybutane.

In this case the epoxy compound can be represented by the general formula:

wherein:

R is a branched or unbranched alkylene group of up to 4 carbon atoms, and X is a halogen atom such as chlorine or bromine. In fact X may derive from any suitable acid. However, in

view of availability and better electrical conductivity the chlorine atom is used preferably.

The polymer directly resulting from the reaction of epihalohydrin with polyethyleneimine in the presence of an organic tertiary amine is soluble in water. It becomes insoluble in water, however, when applied as a layer on a support and heated subsequently to about 100C for a few minutes.

It is generally known that the polymerisation of ethyleneimine does not result in a polymer that is completely composed of units having a linear structure, but that also a certain degree of branching is found. According to Zhuk, Gembitskii, and Kargin in Russian Chem. Rev. 34 (July 1965) No. 7, page 523, the degree of branching in polyethyleneimine depends on the acid concentration and the temperature during polymerisation. This degree of branching may vary between 12 and 38%. The formula of polyethyleneimine can be represented as follows:

wherein, depending on the degree of branching, x is the epihalohydrin reacts with polyethyleneimine comprised between 13.6 and 61.3 mole and y beprobably the first substitutions will occur with one tween 38.7 and 86.4 mole hydrogen atom of the primary amino groups in poly- As appears from the above formula polyethyleneethyleneimine. Further substitutions will occur on imine comprises primary as well as secondary and ter- 5 the thus formed secondary amino groups as well as tiary amino groups. on the secondary amino groups present in the poly- As generally known primary and secondary aliphatic mer chain. Depending on the ratio between epihaloamines in water or organic solvents and in gentle reachydrin and the polyethyleneimine present the prition conditions are converted by epichlorohydrin with mary amino groups or the primary and secondary a high yield according to a hydrogen substitution pro- 10 amino groups will be amino-alkylated partly or comcess into aminoalkylated compounds (I-Iouben-Weyl pletely. In view of the desired properties of the result- Methoden der Organischen Chemie, Makromolekulare ing modified polymer, which properties will be Stoffe, Georg Thieme Verlag, Stuttgart (1961), vol. treated hereinafter, the amount of epihalohydrin 14/", pages 455-460). present per mole of ethyleneimine in the polymer,

In accordance with this reaction the primary and sec- 15 should vary between 0.3 and 1.0 mole, preferably ondary amino groups in polyethyleneimine together should be 0.4 mole approximately. with epichlorohydrin in the presence of organic tertiary amines give rise to hydrogen substitution and quaterni- In the second place there is a quaternization reaction zation reactions in simultaneous or consecutive probetween the--CH X group of unreacted epihalohydrin cesses. In the hydrogen substitution reactions the epoxy 20 d th terti a ine, or between the Cl-I X groups groups will react with the primary or secondary amino already substituted on polyethyleneimine and tertiary CH,-CHOH CH, X

wherein: halohydrin and the tertiary amine groups present in X is a halogen atom, preferably a chlorine atom. When polyethyleneimine.

CH,7CH CH,-X N -R,-- CH,7CH CH,-III RJR2 (IV) +CH, CH,-N-)- N--R, -(-CH,-CH, N+ v CH R CH,

CHoH HoH CH, CH, X 1 2; l x

x /CH,-CH CH, cH,-CH-CH,-x -(-CH,CH,N-)- l-CH,-CH,-N-)- 0 A... H. (11H 2 H: I l-Y N-Y IHg CH: C HOX HoH (3H, CH: (L Q wherein Y is hydrogen or the group -Cl-I -CI-IOI-I- CI-l-Q with Q being X or quaternization reactions will probably occur on the nitrogen atoms of the tertiary amine Further quaternization reactions will then occur on the tertiary amino nitrogen atoms always present as described above in the polyethyleneimine, or on the tertiary amino nitrogen atoms formed in the polyethyleneimine by the substitution reactions.

A ratio of at least 0.2 mole of tertiary amine per mole of epihalohydrin present yields as will be proved in the Examples given hereinafter good electroconductive polymers that can be cross-linked after a short heating at temperatures of about l00C, whereby the electroconductivity of the polymers is preserved. One may add much larger amounts of tertiary amine to the reaction medium, even amounts of 2 moles of tertiary amine per mole of epihalohydrin, without incurring the risk that the electroconductive and cross-Linkable properties of the modified polymer might be impaired sensibly. When an excess of tertiary amine in respect of epihalohydrin is present, only part of the tertiary amine joins in the quaternization reaction and the excess tertiary amine remains unmodified in solution.

These reactions are preferably performed in aqueous medium and at relatively low temperatures of about 50C. The epihalohydrin and the tertiary amine may be mixed previously and the mixture may then be added to polyethyleneimine. However, as a result of the high reactivity of epihalohydrin with tertiary amines and in order to present a quaternization reaction that might immediately take place between both, the mixing and also the storage of the mixture formed has to occur at lower temperatures. Accordingly, it is much easier to mix polyethyleneimine and tertiary amine together and to add the epihalohydrin gradually to the mixture of both.

The relatively low reaction temperature of about 50C is preferred to keep the rate of hydrolysis in aqueous medium of the epoxy groups as low as possible and to keep the degree of aminoalkylation by hydrogen substitution as high as possible. At the same time splitting off of hydrogen chloride at these relatively low reaction temperatures and re-formation of epoxygroups on the polymer are avoided. When the reaction is performed in organic medium, the danger of hydrolysis is less pronounced.

The electroconductive polymers of the invention comprise recurring units of different types. The aminoalkylated polyethyleneimine possibly comprises unsubstituted branched and unbranched ethyleneimine units as described above, and depending on the proportions of epihalohydrin and tertiary amine present, recurring units of formula (I), (II), (III), (V), and (VI).

As appears from the above formulae, especially from formula (VI) the aminoalkylated polyethyleneimine comprises a certain amount of latent reaction epoxy groups and of --CI7I X groups that may further react with residual primary and secondary amino groups or with tertiary amino groups respectively, to form interchain bridges or cross-links that will render the resulting polymer insoluble. This cross-linking can be performed easily by heating the aminoalkylated polyethyleneimine for a short period, e.g., a few minutes at about C, preferably after it has been applied as a layer to a support.

The ratio of epoxy compound in respect of the amounts of polyethyleneimine and a tertiary amine has to be selected within the limits indicated above to obtain optimal properties. These properties may be summarized as follows: initially the modified polyethyleneimine has to be soluble in water and it becomes insoluble only after a simple heat-treatment. The surface resistance of a layer formed from the modified and possibly heat-treated polymer has to be lower than l X 10 ohms/sq. at 15% relative humidity. The electroconductivity of such a layer is mainly determined by the amount of quatemized nitrogen atoms present. The higher this amount the better its electroconductivity.

The molecular weight of the polyethyleneimine before aminoalkylation with epihalohydrin in the presence of an amine has little effect on the electroconductive properties of the polymers after amino-alkylation. However, the molecular weight does affect the crosslinking reaction. The higher the molecular weight, the more efficient is the cross-linking reaction. It results from our experiments that 'polyethyleneimines with molecular weights ranging from 1200 to about 50,000 can be aminoalkylated. They can be applied as continuous layers to a support and the polymeric layer can easily be rendered insoluble by a simple heat-treatment without any operational difficulties.

Layers of the electroconductive polymeric materials can be applied from aqueous solutions by spray, brush, roller, doctor blade, air-knife, or wiping techniques to different kinds of supports, e-.g., paper. Films of synthetic polymers such as cellulose acetate, polystyrene, polyester, polycarbonate, can also be coated with the electroconductive layers. If necessary, these film supports can be provided previously with a known subbing layer, whereon the electroconductive layer is coated afterwards.

When paper is used as the support, the electroconductive polymeric materials will also impart electroconductivity if the paper is thoroughly soaked with an aqueous solution of the electroconductive polymeric materials of the invention. After drying of the thus impregnated paper, the electroconductive polymeric material remains dispersed throughout the entire paper base. Electroconductivity may also be conferred to the paper base by adding a sufficient quantity of an aqueous solution of the electroconductive polymeric materials to the paper making pulp. The amount of incorporated conductive polymer is determined by the required degree of conductivity.

In all these cases the electroconductive polymer can be cross-linked and insolubilised in water and organic solvents by a simple heat-treatment e.g., by heating for a few minutes at about 100C, whereby the electroconductivity of the polymer is not impaired. This is very important, e.g., when a photoconductive layer of zinc oxide is applied to the electroconductive layer. Since the heated electroconductive polymer is insoluble, the photoconductive material can as well be applied thereto from aqueous or organic dispersion without fear that the electroconductive polymer would wholly or partly dissolve away.

The electroconductivity of the aminoalkylated polyethylene imines of the invention is proportional, of course, to the substitution degree of the amino groups in the polymer, to the quantity of aminoalkylated polymer present per unit of surface, and to the relative humidity of the layer. From our experiments it results that at 15% relative humidity and at about 20c layers formed from an aminoalkylated polyethylene imine according to this invention, can easily be cross-linked and possess a sufficient electroconductivity (surface resistance lower than 1 X ohm/sq), when a. during reaction between 0.3 and 1.0 mole and preferably about 0.4 mole of epihalohydrin is present per mole of ethyleneimine units in polyethyleneimine,

b. at least 0.2 mole of tertiary amine is present per mole of epihalohydrin, and

e. the layer contains at least 2 g of dry aminoalkylated polyethyleneimine per sq.m.

The electroconductivity is determined by measuring the surface resistance of layers applied to a support from a 10% aqueous solution of the aminoalkylated polyethyleneimine. The resulting layer is dried and conditioned at a specified relative humidity. The surface resistance measurements are performed by means of a cell, both poles of which have a width of 0.5 cm and are at a distance of 1 cm from each other.

These layers can only be used as an electroconductive layer in an electrographic recording element, if its surface resistance does not exceed well defined limits. The article of Nakao et a1. indicated above, cites a value of 4 X 10 ohm/sq as a limit for smudging of the back face of the paper support. The electroconductivity itself, however, is influenced by the degree of relative humidity. Thus it is advisable to measure a value of surface resistance at of relative humidity lower than 10 ohms/sq. In such case a slight backmarking is unavoidable when the relative humidity is very low. The image, however, retains sufficient appeal to be commercially acceptable.

The amount of electroconductive polymeric material applied depends, of course, on the support used. When this support is made of paper and especially of a highly porous paper stock, more electroconductive polymeric material will have to be used than in the case of a nonporous synthetic support, e.g., of polyester. In general, however, an amount of 0.5 to 7.5 g/sq.m. suffices to provide the layer with a good conductivity.

in addition to the electroconductive polymer of the invention the composition of the electroconductive layer may include stabilizing agents against migrating forces, plasticizers, dispersing agents, pigments, and binders such as gelatin, starch, casein, polyvinyl alcohol and the like. It is obvious that the mixture of such 8 binders determinedly influences the electroconductivity of the layer. Especially gelatin is found to lower the electroconductivity of the layer much more than e.g.,

starch, as commonly can be found in the literature.

Moreover, the electroconductive polymers of the invention may also be combined with minor amounts, in comparison to the amount of electroconductive polymer present, of inorganic and organic salts, e.g., sodium chloride, sodium sulphate, sodium nitrate, the corresponding potassium and ammonium salts, sodium acetate, citric acid amides, hydroxypropylsucrose monolaurate, etc. These salts are known to be electroconductive. They are inexpensive but have the disadvantage that their electroconductivity is very dependent on the relative humidity. When they are combined with the electroconductive polymers of the invention, the low cost-price of these salts is linked with the excellent electroconductivity at low and high relative humidities of the electroconductive polymers.

When the electroconductive layer of the invention is to be used as an antistatic layer in a photographic silver halide recording material, the electroconductive layer is applied generally to the said sheet or web either on a surface opposite to the surface, to which the silver halide emulsion layer is applied, or as an interlayer, i.e., between the support and the light-sensitive emulsion layer or layers.

If the electroconductive layer is to be used in an electrophotographic recording material, a photoconductive coating is applied to the said polymer layer. This coating is prepared by dispersing or dissolving the photoconductive substance or substances in an aqueous or an organic solution of an insulating binder, or in a solution of such an insulating binder in a mixture of an organic solvent and water and by applying the dispersion or solution in the form of a layer to the electroconductive surface.

The electrophotographic recording element prepared with the electroconductive copolymer of the present invention is flexible and possesses a very good mechanical strength. A very good adhesion exists between the paper support and the electroconductive layer.

The electroconductive polymers may be used in combination with coatings of various inorganic as well as organic photoconductive substances such as those described in the Belgian Patent Specification 587,300, filed February 5, 1960 by Gevaert Photo-Producten N.V., the United Kingdom Pat. Specifications Nos. 964,871 filed Feb. 26, 1959,964,873, 964,874 both filed Mar. 30, 1960, 964,875, 964,876, both filed Apr. 21, 1960, 964,877 filed May 2, 1960, 964,879 filed Apr. 26, 1960, 970, 937 filed Dec. 9, 1960 980, 879, 980, 880 both filed Feb. 17, 1961 all by Gevaert Photo- Producten N.V., in the German Pat. Specification No. 1,058,836, filed April 14, 1956 by Kalle & Co. A.G., and in the Canadian Patent Specification 568,707 of Kalle & Co A.G. issued Jan. 6, 1957. These photoconductive substances may be combined with insulating binder agents, known i.a. from the United States Pat. Specifications Nos. 2,197,552 of Joseph N. Kuzmick issued Apr. 16, 1940, 2,297,691 of Chester F. Carlson issued Oct. 6, 1942, 2,485,589 of Frank Graz issued Oct. 25, 1949, 2,551,582 of Chester F. Carlson issued May 8, 1951 and 2,599,542 of Chester F. Carlson issued .Iune 10, 1952, from the United Kingdom Pat. Specification Nos. 566,278 filed June 21, 1943 by Rothschild S. Slathodeon Ltd., 693,112 filed May 9, 1950 by Battelle Development Corporation and 700,502 filed Apr. 26, 1949 by Office National dE- tudes et de Recherches Aeronautiques, from the Belgian Pat. Specification Nos. 612,102 filed Dec. 29, 1961 by Gevaert Photo-Producten N.V., 71 1,376 filed Feb. 28, 1968, 714,257 filed Apr. 26, 1968 both by Gevaert-Agfa N.V., the French Pat. Specification No. 2,485,839 filed June 24, 1966 by Gevaert-Agfa N.V., and the Belgian Pat. Specification No. 683,145 filed June 27, 1966 by Gevaert-Agfa N.V.

Suitable dispersing agents for dispersing photoconductive materials in an aqueous medium are described in the Belgian Pat. Specification No. 703,467 filed Sept. 5, 1967 by Gevaert-Agfa N.V. and as is generally known the photoconductive substances can be spectrally sensitized as described in the Belgian Pat. Specification Nos. 708,244 filed Dec. 20, 1967 by Gevaert- Agfa N.V. and 714,258 filed Apr. 26, 1968 by Gevaert- Agfa N.V.

Photoconductive zinc oxide coatings can be successfully applied to the electroconductive polymers of the invention, especially photoconductive zinc oxide coatings with improved dark resistance and wherein the pre-exposure effect has been sharply reduced, such as described in Belgian Pat. Specification No. 612,102. Also copper(II) derivatives of aliphatic acids may be used to reduce this preexposure effect, e.g., copper(ll) lactate, behenate, naphthenate and other copper(II) salts such as described in United Kingdom Pat. Specification No. 1,085,939.

Also mixtures of zinc oxide may be used, e.g. mixtures of small amounts of non-charge-storing zinc oxide with large amounts of charge-storing zinc oxide in order to confer to the layer an optimal height of charging. Hereby a lengthened exposure scale is obtained giving a much better tonal quality.

The aminoalkylated polyethyleneimines can also very successfully be used in electrophotographic printing plates, wherein both sides of the support, which has been treated with the conductive polymer of the invention, are provided with covering layers, which prevent the solvents from impairing the support during the processing'. These covering layers may contain pigments such as, e.g., zinc oxide.

The invention is illustrated by the following examples.

EXAMPLE 1 Solutions of 43 g of polyethyleneimine in 40 ml of water and of 1 18 ml of a 20% by weight solution of trimethylamine in methanol were introduced in a 500 ml reaction flask provided with a stirrer, a reflux condenser cooled with a mixture of methanol and water at 20C, a dropping funnel, and a thermometer. The mixture was cooled to C.

The polyethyleneimine had a branching degree of about 30%, which corresponds with the following general formula:

wherein x and y are 42.8 and 57.2 mole respectively. A 10% by weight aqueous solution of this polyethyleneimine had an absolute viscosity at 25C of 8.12 cP and its viscosity number n,,,/c amounted to 0.215 dl/g for a concentration c being 1 g/ 100 ml.

37 g of epichlorohydrin were added dropwise in 30 minutes, causing a temperature raise of 45C. Under permanent stirring the reaction was continued for 5 h at 65C.

The slightly yellowish solution was cooled to room temperature and poured into 2.5 l of acetone. The tacky residue was dissolved in 200 ml of methanol and precipitated in 2.5 l of acetone and finally dissolved in 500 ml of water.

Yield: 73 g of aminoalkylated. polyethyleneimine. At this moment the polymer is still soluble in water, but after having been dried at 100C it becomes insoluble in water.

EXAMPLES 2-11 The procedure of example 1 was repeated with varying amounts of polyethyleneimine (the same as used in Example 1), epichlorohydrin and trimethylamine as starting materials. The results are given in the following table.

In Examples 8 and 9 the reaction occurred in sealed heavy-walled reaction tubes at 40"C for l h, at 50C for another hour, at 60C for 2 hours, and finally at C for 1 hour.

EXAMPLE 12 Preparation of the polymer by reaction between poly ethyleneimine on the one hand and a cooled mixture of trimethylamine and epichlorohydrin on the other hand.

A reaction flask of 500 ml was equipped with a stirrer, a double-walled dropping funnel, a reflux condenser, and a thermometer.

The dropping funnel and the reflux condenser were cooled with a methanol/water mixture at -20C.

In the reaction flask 21.5 g of poly ethyleneimine dissolved in 193 ml of water were placed.

In the cooled dropping funnel 46.25 g of epichlorohydrin and 206.5 ml of a 20% by weight solution of trimethylamine in methanol were mixed homogeneously at -IOC.

In approximatively 50 minutes the contents of the dropping funnel were added to the polyethyleneimine solution. Initially the temperature of the reaction medium in the flask was 24C, but it increased slowly so as to attain 40C in consequence of an exothermic reaction. So, the reaction medium had to be cooled now and then with a water-bath of approximatively 8C.

Subsequently the reaction medium was heated for 2 more hours at 40C and afterwards for 4 hours at 60C.

The clear viscous solution was poured into 3 l of stirred acetone. The precipitated polymer was washed with 1 l of fresh acetone and dissolved then in 500 ml of water.

Yield: 90 g.

EXAMPLE 13 Aqueous solutions of the aminoalkylated polyethylene imines of Examples 1 to 12 were applied to a paper support in such a manner that after drying 2 g of solid product were present per sq.m. The coatings were dried at 100C so as to insolubilize the polymer. The surface resistance values of the different samples were measured as indicated above. The results are given in the following table, wherein the abbreviations ECH, 2O

PEI, and TMA mean epichlorohydrin, polyethyleneimine, and trimethylamine respectively.

For comparison purposes was also measured the surface resistance of an uncoated paper support, of a paper support carrying a layer of pure polyethylene- 12 ples the proportion of moles of epichlorohydrin per mole of ethylene unit in the polyethyleneimine is greater than 0.3, but lower than 1.0 and the proportion of moles trimethylamine per mole of epichlorohydrin is always larger than 0.2.

The aminoalkylated polyethyleneimine of Example 11 in the form of a weight solution in water became insoluble when stored at room temperature for 4 days.

EXAMPLE 14 Two samples of glassine paper having a weight of 70 g/sq.m were coated with an electroconductive layer, according to the method described in Example 13 and with the aminoalkylated polyethyleneimines of Examples 1 and 4, in such a manner that after drying about 2 g of solid product was present per sq.m. For comparison purposes a same glassine paper but without electroconductive layer was used.

The electroconductive layers of both first materials and the pure glassine paper were coated with a zinc oxide dispersion prepared as follows. To 5.6 liters of dichloroethane was added 0.5 liter of GELVA MUL- TIPOLYMER solution RP 927A, which is the trade name of Monsanto Chemical Co. for a solution of by weight of RP 927 (an insulating binder material sold for electrophotographic purposes) in a mixture of toluol, isopropanol, and ethanol (22:22:56 by volume). To this mixture 4.2 kg zinc oxide were added. The zinc 3o oxide used is marketed by The Durham Chemical Paper support mole of ECH mole of TMA Surface resistance at 20C in Solubility in water after mole of PEI mole of ECH ohm/sq (2 glsqm) heating of layer at 100C Relative humidity After 10 min. After hour 15 5O 7O uncoated 4.2 10 2.15X10 5.3)(10 coated with PEI 4.2X10"' 2.13X10' 1.93X10 coated with PEI modified with 1.0 2.1 X10 2.36X10 1.64X10 insoluble ECH coated with polymer insoluble of example 2 0.2 0.2 1.42X10 2.5X10 7.7X10 insoluble but does not swellable swell coated with polymer 0.3 0.25 8.5 (10 2.36X10 8.5X10 id. of example 3 coated with polymer 0.4 0.2 3.5Xl0" 8.0)(10 3.86X10 id. insoluble of example 4 but swellable coated with polymer 0.4 0.5 8.5X10 1.9X10 7.9 10 id. id. of example 5 coated with polymer 0.4 1.0 4.25Xl0 3.86 10 6.0 10 id. id. of example 1 coated with polymer 0.4 1.5 1.7X10 9.1X10 4.25X10 id. id. of example 6 coated with polymer 0.4 2.0 5.8X10 1.04X10 425x10 insoluble but insoluble of example 7 but swellable coated with polymer 0.8 1.0 6.8)(10 2.l3 10 id. id. of example 8 coated with polymer 1.0 1.0 1.77X10 2.83 10 x10 id. insoluble of example 9 does not swel coated with polymer 1.0 1.4 4.25X10" 7.3X10 354x10 id. id. of example 12 coated with polymer 1.2 0.83 2.1X10 1.06X10 3.86Xl0 id. id. of example 10 coated with polymer 1.5 0.66 id. id. of example 11 From the above table it can be deduced that only when the paper support has been coated at a ratio of 2 g/sq.m with the aminoalkylated polyethyleneimine of Examples 1 and 4 to 8, and after heating to C a water-insoluble but swellable layer is obtained, which has a surface resistance that in all circumstances of relative humidity is lower than 1X10 ohms/sq. In these Exam- Group, Birtley, United Kingdom, under the trade name ELECTROX. The resulting dispersion was ground in a 65 sand-mill and then admixed with 1.2 liters of GELVA MULTIPOLYMER solution RP927B of Monsanto, which is the same RP927 binder material as a 50 by weight solution in toluol. Then 1.5 liter of dichloroethane and 67 ml of a l by weight solution of bromophenol blue in ethanol were added.

The coating composition formed was applied by means of a knife coater at a ratio of 30 g of zinc oxide per sq.m and dried.

The three materials were treated in a common electrophotographic copying apparatus. When the quality of copies made at different relative humidities with the materials carrying an electroconductive layer of aminoalkylated polyethyleneimine of Examples 1 and 4, are compared only slight differences can be observed. These differences are due to small changes in electroconductivity of both aminoalkylated polyethyleneimines at the different relative humidities. In the comparison material carrying no electroconductive layer considerable smudging of the back face of the support occurs at 15 of relative humidity. This is not the case with the two other materials wherein an electroconductive layer of aminoalkylated polyethyleneimine according to the invention is present.

EXAMPLE 15 A glassine paper of 70 g/sq.m was coated with an electroconductive layer according to the method described in Example 13 and with the aminoalkylated polyethyleneimine of Example 5.

Upon the electroconductive layer thus formed a zinc oxide dispersion was coated that has been prepared as follows. To 500 g of toluol were added 222 g of Electrophotographic Resin E041 solution, which is the trade name of a modified acrylic resin dissolved at a concentration of 45 in a mixture of xylol, toluol, and n-propanol, marketed by De Soto Inc., Des Plaines, 111., U.S.A. In this mixture were dispersed 500 g of zinc oxide type C of Vieille Montagne, Belgium, and the whole was ground in a sand-mill. Finally 5 ml of 1 solution of bromophenol blue in ethanol were added.

The zinc oxide dispersion was applied to the electroconductive layer at a ratio of 30 g of zinc oxide per sq.m.

The material was treated in a common electrophotographic copying apparatus. Good copies were obtained, even at very low relative humidities.

EXAMPLE 16 To 0.807 kg of dichloroethane were added 3.670 kg of GELVA MULTIPOLYMER solution RP 927 A (trade-name) and 0.918 kg of Electrographic Resin E041 solution (trade name). To this mixture 186 ml of tetrachlorophthalic anhydride as a by weight solution in ethanol and 5.56 kg of zinc oxide ELECTROX (trade-name) were added and stirred long enough to sufficiently moisten the zinc oxide pigment.

VINNAPAS UW4 (trade-name) dissolved in 34 ml of dimethylformamide compound of formula:

0 H NH B ..CO I fl} /C H il 2 5 C 11 dissolved in 56 ml of dichloroethane 0.56 g copperfll) naphthenate (comprising 22 by weight of copper) dissolved in 33.5 ml of toluene 6.7 g

VINNAPAS UW4 is the trade-name of WACKER- CHEMIE, Germany, for a high-viscous polyvinyl acetate. The dispersion thus formed was ground in a sandmill and coated on a support of glassine paper having a weight of g/sq.m. This paper had been previously coated with an electroconductive layer according to the method described in Example 13 with the aminoalkylated polyethyleneimine of Example I in such a manner that after drying 2 g of solid product were present per sq.m. Surface resistance at 20C and 50 of relative humidity of the thus covered support was 3.86 X 10 ohm/sq.

The zinc oxide dispersion was applied to the above support in a ratio of 25 g of zinc oxide/sq.m.

The electrophotographic material obtained could be treated in full daylight conditions in electrophotographic apparatus, e.g., in a GEVAFAX 20 apparatus (trade-name of Agfa-Gevaert). Clear and contrasty copies of the original were obtained.

EXAMPLE 17 The process of Example 16' was repeated with the sole difference that in the coating composition for the zinc oxide dispersion the copper(Il) naphthenate was replaced by copper(ll) lactate. Of this compound 8 g were dissolved in 20 ml of water and the'solution diluted with ml of dimethylformamide. The solution was slowly added to the zinc oxide dispersion under intensive stirring.

The same good results were obtained as in Example 16.

EXAMPLE 18 A glassine paper having a weight of g/sq.m was treated in a size-press with the electroconductive aminoalkylated polyethyleneimine of Example 1 and thereafter was calendered to a Bekk surface smoothness of 500700 (cfr. Wochenblatt fur Papierfabrikation, (June 1957) No. 12, pages 447-451). Both sides of the dissolved in 2 m of dichloroethane 2 g paper were then covered with a protective layer in a bromophenol blue ratio of 7 g/sq.m of a finely ground dispersion formed dsmlved 70 ml methanol g 60 of zinc oxide and a binding agent. The zinc oxide used was the DIROX (trade-name) variety sold by Vieille compound of formula: Montagne, Belgium, and as binding agent IXAN SGA bromophenol blue as a l solution in methanol 93 ml compound of the formula l (CH L SO as a 0,5 solution in dimethylformide 104 ml The dispersion was ground in a sand-mill and then .coated on one side of the above treated paper in a ratio of g of dry product per sq.m.

The material was exposed in an electrophotographic apparatus and the latent image was developed with an electrophoretic developer. A copy was obtained, which could be used as a zinc oxide matrix in an offsetmachine. Howeyer, the surface had to be pretreated with a suitable etching liquid, which was prepared as follows. i

In 800 ml of water the following products were dissolved successively:

potassium cyanoferrate (ll) 20 g potassium cyanoferrate (III) S g dipotassium hydrogen phosphate 50 g ethylenediaminetetra-acetic acid I g glycerol l0 ml To the solution obtained water was added up to a volume of 1 liter.

When the matrix was used in an offset machine very contrasty and sharp copies of the original could be made.

We claim:

1. An electroconductive substrate comprising a support of paper or synthetic polymer, an electroconductive layer coated on at least one side of said support, said electroconductive layer having a surface resistance measured at 15 of relative humidity lower than l0 ohm/sq., said electroconductive layer consisting of or including a major proportion of an aminoalkylated polyethyleneimine resulting from the reaction at 50C of epihalohydrin with polyethyleneimine in the presence of an organic tertiary amine, said polymer being soluble in water and becoming insoluble by heating at C.

2. An electroconductive substrate according to claim 1, wherein during said reaction of epihalohydrin with polyethyleneimine in the presence of an organic tertiary amine between 0.3 and L0 mole of epihalohydrin is present per mole ethyleneimine units in polyethyleneimine, and at least 0.2 mole of organic tertiary amine per mole of epihalohydrin. amine 3. An electroconductive substrate according to claim 1, wherein during said reaction 0.4 mole of epihalohydrin is present per mole of ethyleneimine units in polyethyleneimine.

NH- COCH 4. An electroconductive substrate according to claim 1, wherein the epihalohydrin is epichlorohydrin.

5. An electroconductive substrate according to claim 1, wherein the organic tertiary amine corresponds to the general formula:

wherein:

each of R R and R (same or different) represents an alkyl group containing up to 5 carbon atoms, a cycloalkyl group, or an aralkyl group, or

R R and R together with the nitrogen atom represent a heterocyclic compound.

6. An electroconductive substrate according to claim 5, wherein the organic tertiary amine is trimethylamine.

7. An electroconductive substrate according to claim 1, wherein a photoconductive layer is applied to the electroconductive layer to form an electrophotographic recording material.

8. An electroconductive substrate according to claim 1, wherein an insulating layer is applied to the electroconductive layer to form an electrographic recording material.

9. An electroconductive substrate according to claim 1, wherein the electroconductive layer comprises at least 2 g of aminoalkylated polyethyleneimine per sq.m.

UNITED STATES PATENT AND TRADEMARK OFFICE CERTIFICATE OF CORRECTION PATENT NO. I 3,923,505

DATED December 2, 1975 r v 0 (5) Daniel Maurice Timmerman et al It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

In the Title: The last word of the title should be corrected to read: Polyethyleneimine Item [30] Foreign Application Priority Data:

"June 16 1972 Germany 028432" should read June 16 1972 Great Britain 028423 In the Claims: Column 16 line 13, after "mole" insert of line 15, delete "amine" after the period.

Signed and Scaled this 1 second Day Of March 1976 [SEAL A ttes t:

RUTH C. MASON C. MARSHALL DANN Al eflmg ()ffite Commissioner ofPatenrx and Trademarks

Claims (9)

1. AN ELECTROCONDUCTIVE SUBSTRATE COMPRISING A SUPPORT OF PAPPER OR SYNTHETIC POLYMER, AN ELECTROCONDUCTIVE LAYER COATED ON AT LEAST ONE SIDE OF SAID SUPPORT, SAID ELECTROCONDUCTIVE LAYER AVING A SURFACE RESISTANCE MEASURED AT 15% OF RELATIVE HUMIDITY LOER THAN 10**11 OHM/SQ, SAID ELECTROONDUCTIVE LAYER CONSISTING OF OR UBCKYDUBG A NAHIR ORIOIRTUIB IF AB ANUNOALKYLATED POLYETHYLENEIMINE RESULTING FROM THE REACTION AT 50*C OF EPIHALOHYDRIN WITH POLYETHYLENEIMINE IN THE PRESENCE OF AN ORGANIC TETRIARY AMINE, SAID POLYMER BEING SOLUBLE IN WATER AND BECOMING INSOLUBLE BY HEATING AT 100*C.

2. An electroconductive substrate according to claim 1, wherein during said reaction of epihalohydrin with polyethyleneimine in the presence of an organic tertiary amine between 0.3 and 1.0 mole of epihalohydrin is present per mole ethyleneimine units in polyethyleneimine, and at least 0.2 mole of organic tertiary amine per mole of epihalohydrin. amine

3. An electroconductive substrate according to claim 1, wherein during said reaction 0.4 mole of epihalohydrin is present per mole of ethyleneimine units in polyethyleneimine.

4. An electroconductive substrate according to claim 1, wherein the epihalohydrin is epichlorohydrin.

5. An electroconductive substrate according to claim 1, wherein the organic tertiary amine corresponds to the general formula:

6. An electroconductive substrate according to claim 5, wherein the organic tertiary amine is trimethylamine.

7. An electroconductive substrate according to claim 1, wherein a photoconductive layer is applied to the electroconductive layer to form an electrophotographic recording material.

8. An electroconductive substrate according to claim 1, wherein an insulating layer is applied to the electroconductive layer to form an electrographic recording material.

9. An electroconductive substrate according to claim 1, wherein the electroconductive layer comprises at least 2 g of aminoalkylated polyethyleneImine per sq.m.