US2271758A - Hectograph blanket comprising a cellulose derivative gel and method of preparing andusing same - Google Patents

Description

Feb. 3, 1942. w. J. CHAMPION 2,271,758

HECTOGRAPH BLANKET COMPRISING A CELLULOSE DERIVATIVE GEL AND- METHOD OF PREPARING ANDVUSING SAME Filed May 20, 1940 Patented Feb. 3, 1942 HEOTOGR-AI'H BLANKET COMPRISING A CELLULOSE DERIVATIVE GEL AND METH- OD OF PREPARING AND USING SAME William .1. Champion, Berwyn, 111., assignor to Ditto, Incorporated, Chicago, 111., a corporation of West Virginia Application May 20, 1940, Serial No.336,226

19 Claims. (Cl. 41-313) H The invention relates to the art of duplication and includes an improved hectograph blanket.

in the form of a pad or roll; also a method of preparing same, and method of duplicating therewith.

Heretofore hectograph blankets have been made from gelatinous masses comprising either glue or gelatin, or from acrylate resins as shown in United States Patent No. 2,153,324. The gelatin or glue masses have the disadvantage of a certain amount of tackiness which has never been entirely overcome. Further, they are sensitive to heat and humidity; they change their hardness and copying properties with time and require extended aging periods before assuming their flnal properties. The acrylate pads, while being free from many of these disadvantages,

are still excessively expensive dueto the high cost of ingredients needed for these rolls.

I have discovered that hectograph blankets of new and desirable characteristics can be made by forming the copy mass of a cellulose derivative gel whose liquid constituent is a relatively non-volatile solvent for hectograph inks and, preferably present in substantially larger proportion than the cellulose derivative. The copy masses made from the cellulose derivative gels are characterized by a high degree of toughness and by being especially repellent to paper and substantially non-tacky. Copies may be made therefrom according to the ordinary hectograph procedure without moistening the surface of the copy mass.

Other objects and advantages of the invention will become apparent as the following detailed description progresses, reference being had to the accompanying drawing, in which Fig. l is a perspective view of a hectographroll embodying the invention; and

Fig. 2 is a section taken on line 22 of Flg. 1.

Referring to Figs. 1 and 2, in which the preferred embodiment of the invention is shown. the reference character I designates a backing of a flexible strong sheet material such as cotton cloth covered on both sides with a flexible zeinalcohol lacquer 2 and 3 and having a copy mass 4 on the lacquer side 3, said copy mass consisting of a cellulose ether gel whose liquid constituent is a solvent for h'ectograph inks, which boils at substantially above 100 0., and which is present in the gel in substantially larger proportion than the cellulose ether. n

The cellulose derivative 'gel used for the copy mass of the hectograph blanket is preferably a liquid similar to the ordinary gelatin or glue hectograph mass. However, the amount of liquid 1 may also be in minor amount, such as is present in ordinary plasticized cellular derivatives. vThe gel preferably is of the reversible type formed by cooling a colloidal solution. By the term cellulose'derlvative gel it is intended to include colloidal solution of a liquid in a cellulose derivative, but it is not intended to include substances in which the liquid is merely absorbed by the cellulose derivative and can be entirely pressed out. Cellulose derivative gels which have been found to be suitable include nitro-cellulose gels,

cellulose acetate gels, and the various cellulose ether gels such as methyl cellulose, ethyl cellulose, and benzyl cellulose gels.

The solid constituent of the gel suitably consists of a cellulose derivative such as cellulose nitrate, cellulose acetate, methyl cellulose, ethyl cellulose, benzyl cellulose, and the like, either alone or in admixture with each other or with other lyop'hilic colloids such as gelatin or the acylate resins The preferred cellulose derivatives are the cellulose ethers and the preferred cellulose ether is methyl cellulose. q

The liquidconstituent of the gel is suitably a relatively non-volatile d'ye solvent and preferably a solvent-for water and alcohol soluble dyes such as are used in ordinary hectograph inks. Suitably the liquid is a solvent for its cellulose derivative at an elevated temperature, and a plasticizer for the cellulose derivative at normal room temperature. Preferably the major proportion of the liquid should boll substantially above C., and the liquid should be present in the gel in substantially greater proportion than the solid lyophilic colloid constituent of the gel. 1

The liquid may consist of a single'compound or mixture of compounds. The compound which is necessary to cause gelation from the sol state may or may not be a solvent for hectograph inks (viz., benzyl alcohol), but if it is not a solvent there is preferably admixed with it a solvent for hectograph inks so that the total liquid of the gel is a solvent. Furthermore, the total liquid of the gel is preferably a plasticizer for the cellulose derivative, although the liquid may consist of a plasticizer and some a plasticizer admixed in such proportion that the mixture itself is a plasticizer.

A suitable manner of preparing the gel is to choose. a. liquid (preferably a hectograph dye solvent) which is a solvent for a substantial soft, tough gel containing a high proportion of 6:1 amount of cellulose derivative at anelevated temliquid which is not perature and which will dissolve a substantially lesser quantity of the cellulose derivative at room temperature, then dissolve the cellulose derivative in this liquid at an elevated temperature to.

form a sol, and allow the sol to cool to room temperature, whereupon a reversible gel forms. This procedure may be carried out by coating the hot sol on a flexible sheet such as cotton cloth or the like and then allowing the sol to cool into a gel, thereby forming a hectograph blanket comprising a backing having a copy mass of a cellulose derivative gel.

Thecellulose derivatives are generally dissolved in liquids boiling at above 150 C. and are poured at a very high temperature, generally from 130 to 140 C. as against 45 to 55 C. for gelatin and glue masses. The compositions therefore assume their final gel properties immediately on cooling without any aging period; they maintain their properties unchanged over very long periods of time, and they are practically independent of the surrounding temperature.

Other methods of forming a cellulose derivative gel may be used, as for example, the addition of a non-solvent for the cellulose derivative to the sol, or the evaporation of the liquid compound causing solution from a mixture of compounds which together give a solvent for the cellulose derivative. Such procedures in general are not considered as satisfactory for the production of a hectograph blanket as the cooling method.

In making the hectograph blankets, the cellulose derivative sols may be poured directly on a .fiexible backing sheet such as cotton cloth, paper or the like, and then gelled. However, preferably and particularly when the blanket is used as a roll, the backing sheet should havefa protective coating on both sides. In such cases the cellulose derivative solis coated and gelled on one side of the protective coating. This protective coating may be any lacquer which is not'dissolved by the solvent of the cellulose derivative which is poured thereon. A suitable lacquer consists of a solution of 20% zein and 80% of 80% ethyl alcohol. Good adhesion of the cellulose derivative gel to this dried lacquer is obtained when cellulose derivative sol is poured' over it and gelled. The zein lacquer has the further advantage that it is relatively non-adherent to the cold cellulose derivative gel so that the blankets in the form of hectograph rolls may be readily wound and unwound. It is not necessary to have an intermediate bonding layer between the protective lacquer of the backing and the cellulose derivative gel, but an intermediate bonding layer may be used if desired, and in some cases is advantageous. When a cellulose ether gel is used and the backing of the hectograph blanket is protected by a nitrocellulose lacquer, a suitable intermediate bonding layer consists of a composition of cellulose ether containing a plasticiser which is in part or to some slight extent a sol.- vent for nitrocellulose. I-

To more clearly set forth the practice in accordance withthe invention and to more specifically point out the nature of the product and process contemplated thereby,'several specific, il-

- lustrative'examples are hereinafter set forth, it

being understood that these examples illustrate several embodiments which have given satisfactory results and are not intended restrict the invention thereto.

Example I 200 grams of propylene glycol were heated. to l. grams of methyl cellulose of the high viscosity type were added with agitation. The resulting composition was poured onto cloth covered with a nitrocellulose lacquer. and was allowed to cool about two minutes. This mass is immediately ready for use. A test master was immediately applied to the mass and good copies were taken oil in the-usual manner. The mass was unusually hard and firm, showed fair bond to the lacquer withoutthe use of special bonding agents and was exceptionally repellent to paper.

Example II 100 parts by weight of butyl phthalyl butyl glycollate were heated to 130 C. 10 parts by weight of methyl cellulose of 1500 centipoises viscosity If methyl cellulose of a lower viscosity is used, then a higher proportion of methyl cellulose should be used, and vice versa. The resulting sol was poured on to cloth covered with a zein-alcohol lacquer and was allowed tocool. The hectograph blanket so formed is immediately ready for use. The copy mass had similar properties to that of Example I and gave a similar number of good copies.

Example III cyclic acetal having a flash point of 75 0., speciflc gravity 1.074, refractive index 1.474,.and boiling point of 250 C. 30 grams of ethyl cellulose was added to the 70 parts of Cyclonol with agitation to form a hot sol. The sol was then poured on to cloth covered with nitroceflulose lacquer and was allowed to cool, whereupon an ethyl cellulose gel was formed on the backing. The hectograph blanket so produced is immediately ready for use and gave a large number of good copies. I

1 Example IV A sol of the following composition was made by heating the mixture with agitation to 160 Parts byweight Ethylene gly s Di-ethylene glycol 6 Low viscosity cellulose acetate (Eastman,

Tenn., type E-2'l) 1 The hot solution formed of the above mixture was then poured on a backingand allowed to gel, forming a hectograph vblanket having a copy mass of a cellulose acetate gel. Copies could be obtained from this hectograph blanketby the usual hectosraph process.

qlm p e V The following composition was mixed together to form a sol or colloidal solution:

Percent by weight Ethyl aceta One-half second nitrocellulose 10 Carbitol (di-ethylene glycol mono-ethyl ether) 10 The solution so formed was then poured on a flexible backing and the ethyl acetate evaporated. This gave a hectograph blanket having a copy mass of what broadly'sp'eaking may be called a cellulose nitrate gel. Gels having such a low proportion of liquid as in this example are generally not preferred. However, where a copy mass is desired which is thinner than the copy mass of an ordinary glue or gelatin hectograph blanket, the cellulose derivative composition of the above example gave satisfactory results.

the design.

. from a copy sheet.

The hectograph blankets of this invention may be used in the same manner as ordinary gelatin.

' cellulose ether and a relatively non-volatile liquid the copy mass, each sheet receiving a proportion of the dye or coloring matter to form a copy of While it is in general herent in the invention as broadly as possible, in

view of the prior art. I claim:

1. A hectograph blanket having a copy mass v desirable to use an ordinary hectograph ink which comprises a water of a cellulose derivative hydrophilic gel whose liquid portion consists of a solvent for a water and alcohol soluble dye adapted to be transferred 2. A hectograph blanket having a copy mass of a cellulose derivative gel whose liquid p rtion consists of a solvent for a water and alcohol soluble dye, said gel having the characteristic of being non-tacky and more repellent to paper than ordinary gelatin hectograph gels.

3. 'A hectograph blanket having a copy mass of a gel comprising a colloidal solution of a-relatively non-volatile liquid in a cellulose derivative, said liquid comprising a solvent for water and alcohol soluble dye anda plasticizer for the cellulose derivative.

4. A hectograph blanket having a copy mass of a cellulose derivative gel whose liquid portion is a solvent for hectograph ink comprising water and alcohol soluble dye, and is present in substantially greater proportion than the cellulose derivative.

5. A hectograph blanket having a copy mass of a cellulose ether hydrophilic gel whose liquid portion consists of a solvent for a water and alcohol soluble transfer dye.

6. A hectograph blanket having a copy mass of a gel comprising a colloidal solution of a relatively non-volatile liquid in a cellulose ether, said liquid comprising a solvent for water and alcohol soluble dye and a plasticizer for the cellulose ether. a

7,. A hectograph blanket having a copy mass of a cellulose ether gel whose liquid portion is a solvent for hectograph ink comprising water and alcohol soluble dye, and is present in substantially dissolving a substantial amount of cellulose derivative at normal room temperature, said liquid being present in greater proportion than said cellulose derivative.

9. A hectograph blanket having a copy mass of a cellulose ether heat reversible gel comprising which is capable of dissolving a. substantial amount ot'the cellulose ether at above normal room temperature but incapable of dissolving a substantial amount of cellulose ether at normal room temperature, said liquid being present in greater proportion than said cellulose ether.

10. 'A hectograph blanket having a copy mass of a methyl cellulose heatreversible gel comprising methyl cellulose and a relatively non-volatile liquid which is capable of dissolving a substantial amount 01' the methyl cellulose at above normal room temperature but incapable of dissolving a substantial amount of methyl cellulose at normal room temperature, said liquid being present in greater proportion than in said methyl cellulose.

11. A hectograph blanket having a copy mass of an ethyl cellulose heat reversible gel comprising ethyl cellulose and a relatively non-volatile liquid which is capable of dissolving a substantial amount of the ethyl cellulose at above normal room temperature but incapable of dissolving a substantial amount of ethyl cellulose at normal room temperature, said liquid being present in greater proportion than said ethyl cellulose.

12. A hectograph blanket having a copy mass of a benzyl cellulose heat reversible gel comprising benzyl cellulose and a relatively non-volatile liquid which is capable of dissolving ,a substantial amount of the benzyl celulose at'above normal room temperature but incapableof dissolving a substantial amount of benzyl 'cellulose at normal room temperature, saidliquid being present in greater proportion than said benzyl cellulose.

13. A hectograph blanket comprising a backing, a copy mass onone side of the backing comprising a cellulose derivative heat reversible gel, the liquid portion of which consists of a solvent for a transfer dye, and a protective coating on lose derivative gel when pressed against the gel at normal room temperature.

15. The method of making a hectograph blanket, which comprises applying a cellulose derivative sol comprising a cellulose derivative dispersed in'a liquid which is a solvent for water and alcohol soluble dye to a backing, and gelling the cellulose derivative sol.

16. The method of making a hectograph blanket which comprises forming a solution of a predetermined amount of cellulose derivative at an elevated temperature in a liquid which is capable of dissolving all of the cellulose derivative at'an elevated temperature but incapable of dissolving all of said cellulose derivative at normal.

room temperature, coating the hot solution on a backing, and cooling said solution to room temperature to form a gel.

1'7. The method of making a. hectograph blanket which comprises forming a solution oi a predetermined amount of cellulose ether at an elevated temperature in a liquid which is capable of dissolving all oi the cellulose ether at an elevated temperature but incapable of dissolving all tacting said design on the cellulose derivative gel with copy sheets to reproduce the design on the copy sheets in positive.

19. A process of reproducing copies which comprises contacting the face of a copy sheet having a design oi a soluble dye with a copy mass of a I cellulose ether gel whose liquid portion is a solvent tor the dye on the copy sheet whereupon thedesimonthecopyshectistransierredin reverse to the cellulose ether gel, and contacting said design on the cellulose derivative gel with copy sheets to reproduce the design on the copy sheets in positive. v e s WILLIAM l. cnmlox.

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