CA1059387A - Electroconductive paper - Google Patents

Abstract

Abstract of the Disclosure Disclosed is electroconductive paper adapted particularly for use in the manufacture of paper used in the electrophotographic reproduction of images.

Description

~ 593~7 ~ `` .. . . . .
This invention relates to novel electroconductive paper sheeting ; ~ -comprised of a web of cellulosic fibers having disposed on at least one surface thereof an electroconductive layer or coating, such layer con- i `
taining essentially of an electroconductive resin.
The use of electroconductive paper in the manufacture of electrophotographic recording sheets is known in the art. By way of example only, see United States Patent No. 3,653,894.
In accordance with an aspect of this invention, a new electro-., .
conductive paper base sheet is provided comprising a cellulosic web having disposed on at least one surface thereof an electroconductive layer. In such new paper, the improvement is provided by the fact that the electro-conductive layer consists essentially of an electroconductive resin con-sisting essentially of the diquaternary chloride of the reaction product of (1) a water soluble or water dispersible poly(alkyldiallylamine?- , epichlorohydrin base resin having epoxide moieties and (2) a tertiary amine having the formula RlR2R3N where Rl and R2 and R3 are the same or different alkyls having from 1 through 9 carbon atoms in an amount at least stoichiometrically equivalent to the epoxide moieties of the base resin.
The electroconductive resin consists essentially of thejreaction ;
product of a tertiary amine and the base resin. The tertiary amines ~-employed in preparing the electroconductive resin have the formula RlR2R3N where Rl, R2 and R3 are the same or different alkyls having from l through 9 carbon atoms, preferably 1 through 4 carbon atoms. Examples of tertiary amines of the above formula are trimethylamine, triethylamine, tripropyla~ine, tributyIamine, triisobutylamine, N-ethyl-N-methylpropyl-:
amine, N,N-diethylpropylamine, N,N-dimethylethylamine, N,N-dimethyl-iso-propylamine, and N-ethyl-N-isopropylbutylamine.
A preferred poly(alkyldiallylamine) is a homopolymer of methyl-diallylamine. ~

The poly(alkyldiallylamine)-epichlorohydrin base resin used to , prepare the electroconductive resins used in providing the paper of , ~:;
1()59387 an aspect of this invention comprises the resinous reaction product of (A) a linear polymer having units of the formula N / (I~ `
I t ~.,:
R

where R is hydrogen or lower alkyl and Rl is alkyl or a substituted alkyl and (B) epichlorohydrin. The base resins will have an RSV of 0.2 to 0.4 (IM NaCl, 1%, 25C.).
In the above formula, each R can be the same or different and~
as stated, can be hydrogen or lower alkyl. The alkyls contains from l through 6 carbon atoms and are preferably methyl, ethyl~ isopropyl or n-butyl. R' of the formula represents alkyl or substituted alkyl. The R' alkyls will contain from 1 through 6 carbon atoms, e.g., meth~l, ethyl, propyl, isopropyl, butyl~ tert-butyl and hexyl. Preferably, the R' alkyla will contain from l through 4 carbon atoms. R' can also be a substituted alkyl. Suitable substituents include, in general, any group which will not interfere with polymerization through a vinyl double bond. Typically~
the substituents can be carboxylate, cyano, ether, amino (primary, secon-dary or tertiary), amide, hydrazide and hydroxyl.
The base resin consists essentially of the reaction product of a linear polymer wherein from 5% to 100% of the recurring units have the formula (I) with from 0.5 mole to 1.5 moles of epichlorohydrin per mole of tertiary amine present in said polymer at a temperature of 30C. to 80C., preferably from 45C. to 55C., and at a pH from 7 to 9.5, whereby :~ , there is produced the base resin containing epoxide groups.
The poly(N-alkyldiallylamine)-epichlorohydrin base resins having epoxide moieties are well known in the art and are disclosed and described in United States Patents 3,700,623; 3,772,076; 3,833,531; and 3,840,504.
In preparing the electroconductive resins used in providing the paper of aspects of this invention, the reaction of the base resin and the ~;;tertiary amine is .
- 3 - ;

10593E~7 ~~carried out in a liquid medium that is a solvent ~or both the base resin and the tertiary amine ana that is inert to the base resin, the tertiary amine and the product of the reaction. Preferably, the liquid medium is an aqueous medium. The solids concentration `
of the base resin in the reaction medium, prior to reaction, will be, by weight, from 1% to 25% and preferably from 5% to 10%. Too high a solids concentration will some-times produce gelation which is undesirable. Reaction is carried out under pressure or at atmospheric pressure at temperatures of 10 from 0C. to 150C., and higher if desired. Preferred ;i temperatures will be room ~emperature (23C.) to 55C.
.. . . .
Reaction is carried out until substantially all the epoxide `
moieties of the base résin ~derived from the epichlorohydrin) have reacted with the tertiary amine. The time of reaction varies in- v versely with temperature.
The pree~red amount of tertiary amine employed will be 2 moles for each epoxide moiety of the base resin. However, from 0.5 mole to 3- moles of tertiary amine can be used with sat- ;
isfactory results.

2(~ In preparing the resins used in Providin~ the paJ~er of aspects of this inven-tlon, the reaction of the amine with the poly(alkyldiallylamine)-epichlorohydrin base resin preferably takes place in aqueous ~edium. The reaction with the amine can be carried out promptly after preparation of the base resin solution. If the base resin solution is to be stored for any length of time prior to reaction with the nitrogen com-pound, it should be stabilized against gelation.
The base resin is stabilized against gelatlon by adding to the aqueous solution thereof sufficient aqueous hydrochloric acid to obtain and maintain a pH of 2. The stabilized product 30 can be reactivated by known means, e. 6-, by addition of aqueous sodiurn hydroxide, prior to reaction with the tertiary amine. On stabilization the epoxide moieties are destroyed; on reactivation, they are restored~
A b~se resin having epo~ide moieties will be comprised of a ;
~ 4 ~

)S93~7 r ~ plurality of units of the following structure;
P\
R' CH2CHCH2 r ` '~3 1 (II) t/~;---CH
R R
where R and R' are as above defined.
Reaction with a tertiary amine, RlR2R3N produces a resin 10 composed of a plurality of units of the following structure:
OH ~
R' CH2cHcE~2NRlR2R3 CH2 , (}~I) R R _' ;
For u~e in providing the paper of aspects o~ this invention the resin is employed as the diquaternary chloride. Thus, after reaction with a tertiary amlne, as above set forth, aqueous hydrochloric acid is added in an ~
20 amount sufficient to obtain and maintain a pH of from 2 to ~..
4. The acid treatment provides a resin having a plurality of units of the following structure:
OH
R' CH2CHCH2NR1~2R3 Cl~ I ~IV) tR \;-~...CH2~

In all examples that follow parts and percentages are by . :
30 weight unless otherwise specified. Example 1 below is illustra- :
tive of the preparation of a base resin that can be used in this i` .:
invention. ~ :
Example 1 Methyldiallylamine (2224 lbs.) was placed into a reaction vessel. 31~ hydrochloric acid (1920 lbs.) was added cautiously .;. :
with cooling to give a pH of 3. This solution was then sparged with nitrogen for 20 minutes. Sodium bisulfite ~50 lbs. in :;: ::
'::
- 5 ~

~o~

i . !, 40 gals. H2O) and t-butyl hydroperoxide (40 lbs. 70% solution in 40 gals. H2O were added simultaneously over an 8 hour period dur~
ing which the temperature rose to 65C. followed by cooling to room temperature TS = ~60%, RSV = 0.22 (0.1 M NaCl, 1%, 25C.).
This polymer solution was trans~erred to a larger kettle.

~: , .
4% Sodium hydroxide (450 gals.) and 1335 gals. of water were added giving a pH of 8.4. Epichlorohydrin (280 gals.) was added and the reaction allowed to proceed (40C.). When the Gardner-Holdt vis-cosity reached B~ 31% hydrochloric acid (160 gals.) was added giv- ;
10 ing a pH of <2. The temperature was raised to 80C. and held for , 2 hours. The resin solution was then cooled to 40C. and 4% ;~
sodium hydroxide added to give a pH of 3.5. TS = 20.2%, Brook-field viscosity = 55 cps.
The resin of the Example 1 solution, prior to being acidi-fied, will consist of a plurality o~ units of the structure:

r ~ ~ cl 1 tv) ~ CH2 On being acidified with the 75 parts of 20 Be hydrochloric acid and heated at 60C. until the pH becomes constant at about 2, the units will have the structure:

OH
CH3 /CH2CHCH2Cl r`~ Cl~ 1 ~ CH2 ~ (VI) ~ -Example 2 2045 grams of a 20.5% solids aqueous solution of poly-(methyldiallylamine)-epichlorohydrin resin was placed in a reac-tion vessel. The aqueous solution contained 420 grams or 1.75 -moles of resin. The resin was prepared in a manner similar to that of Example 1. The aqueous resin solution (20.5% solids) was diluted to 5% solids by adding 6355 cc. of water. 1750 cc. of 1 Molar sodium hydroxide was added raising the pH of the solution ~9;~8'7 .
' from 3.5 to 10.9. 826 grams of a 25% aqueous solution of tri methylamine was added to the contents of the reaction vessel.
The amount of trimethylamine in the 25% aqueous solution was 206.5 grams or 3.5 moles. The contents of the reaction vessel ~.
were heated to a temperature of 50-55C. and maintained at this temperature for 3 hours. Unreacted trimeth~lamine was removed ;
under vacuum. The pH of the resulting aqueous reaction mass was adjusted to 2.8 by adding 121 cc~ of concentrated hydrochlori~c acid.
In Example 2, on raising the pH of the soluti-on from 3.5 to -~
10 ~.9, the units of structure (V~ were reestablished. Prior to pH
adjustment with HC1 the resin consisted of units of the structure ~ i VII).
OH ~ ;~
CH3 ~FI2cHcH2N(cH3)3 ~ ~ CEI ~ }~ ~VII~

On adjustment to pH 2.8 with concentrated hydrochloric acid the resin consisted of units of the structure (VIII~.
.,.~,, ~
OH
CH3 ~ H2C CH2N(CH3)3 1 - ~ 2 ~ C ~ (VIII) '.! ' ' ;,r,, ': .
Example 3 ~
Example 3 was repeated six times, The aqueous reaction ~ , masses of the 7 examples were combined and concentrated to ' --37.25% solids content on a flash evaporator.
Example 4 ~,, .: .
Sufficient of the 37.25% resins solids solution of Example ~ ::. ~:
30 3 to provide 3Q grams resin Ca~out 80 grams of solution~ was com-bined with 50 grams of calcium carbonate, and 2Q grams of starch ~;
(Penford Gum 280~ and the solids content thereof adjusted to 30%
by the addition of water to provide a coating color. The pH of the coating color was then adjusted to 8.5 by the addition of - 7 ~

`mmonium hydroxide. The coatin~ color was applied on paper pre-pared from bleached wood fiber. SeYeral sheets were coated at 2 lbs./side and several at 4 lbs./side. The coated sheets were dried on a drum drier at 100F. The sheets were then coated with , zinc oxide with an "O" Mayer rod using the following formulation:
ZnO (Photox 8 ~ 100 grams Resinous binder (Rohm & Haas F89) 24 grams Toluene 43 grams Dye sensitizer* 0.8 gram 10 *(Dye sensitizer consists of bromophenol blue (.34 part), uranine ( .5 part), acid green 16 (.15 part) and methanol ~99.1 parts) The sheets were coated at 15 lbs./3000 ft.2 and dried at 100C.
for 45 seconds.
Example 5 Example 4 was repeated with the exception that instead of 20 grams starch there were employed 18.5 grams of starch and 1.5 ~;
grams of sodium carboxymethylcellulose having a degree of substi-tuition of 0.9.
Example 6 Example 4 was repeated ~ ing poly(dimethyldiallylammonium chloride1, available as Calgo 61, instead of the resin of Ex-ample 2. Calgon 261 has been employed heretofore as a conductive coating on paper and represents priox art.
Volume resistivities of the prepared sheets ~2 lbs./side) were determined at 15~ relative humidity (front side). Results are set forth below in Table I. ;
Table I (2 lbs./side) Example Volume Resistivity Surface Resistivity 4 8.6 x 101 ohms 7.8 x 101 ohms 4.3 x 101 ohms 3.1 x 101 ohms 6 (prior art) 3.1 x 101 ohms 1 x 101 ohms ;
Volume resistivities of the prepared sheets (4 lbs./side) were determined at 15% relative humidity (wire side). Results are set forth in Table II below.
Table II (4 lbs./side) Example 4 6.0 x loll ohms Example 5 6.8 x 1011 ohms Example 6 (prior art) 6.6 x 10 ohms '

Claims (3)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. In an electroconductive paper base sheet comprising a cellulosic web having disposed on at least one surface thereof an electroconductive layer the improvement wherein the electroconduc-tive layer consists essentially of an electroconductive resin con-sisting essentially of the diquaternary chloride of the reaction product of (1) a water soluble or water dispersible poly(alkyldi-allylamine)-epichlorohydrin base resin having epoxide moieties and (2) a tertiary amine having the formula R1R2R3N where R1, R2 and R3 are the same or different alkyls having from 1 through 9 carbon atoms in an amount at least stoichiometrically equivalent to the epoxide moieties of the base resin.

2. The electroconductive paper base sheet of claim 1 wherein the tertiary amine employed in preparation of the electro-conductive resin is trimethylamine.

3. The electroconductive paper base sheet of claim 1 wherein poly(alkyldiallylamine) is a homopolymer of methyldiallyl-amine and the tertiary amine is trimethylamine.