US1937103A - Pencil sheath composition - Google Patents

Description

Patented Nov. 28, 1933 2 v I I NI ED; STATES-Q P ENT armrams-sums COMPOSITION I Jorgen Thomsen,'Jersey- "City, N'. J.,"assignor' to Joseph Dixon' Crucible Company, T'Jersey' Qity, J., a corporation of New Jersey 8 I No Drawing. Application Dece niber 12, 1931 r Serial No. 580,139

The invention relates to an improvement in: flour; a bondingagent such as casein-or viscose, plastic compositions forpencilsheaths'and simia solvent and plasticizing agent for the casein;v lar articles. This application is a continuation if; the latteris used, andusually'a'coloring-mattenii in part of my copending application, Serial No.1 Ihave discovered that one of thereasonswhy 492,370 filed October 30, 1930. comp0siti0n}.pencil sheaths aspheretofore com- 55 It has been proposed heretoforetossubstitute" pounded become warped or twisted is the fact for the usual wood sheath for' lead and other that some of the ingredients :used have required pencils a sheath composed. of a self-hardening too much waterto makethe compositionextrusn plastic compound. Up to the present-time, how-' ble. This fact led-me tosearch for equivalent 10 ever, so far as I am aware, no practical comingredients whichare non-absorbent, or substane 60 pound, has been disclosed, because the 'requiretially so, and which can be either usedwithor. ments .of' the art are so-varied'and confiicting substituted for the former watereabsorbing inl- I For example,the sheathproduced must'beinitialgredients. For example, arpencil sheath*com-% v 1y so constituted thatit can be extruded from a position composed largely of finely powdered: celsuitable machine whileit is in a plastic, condilulose, such as wood-flour, is highly 'water ab- 65 tion; it must be capable of surrounding, and upon sorptive, whereas the-fibrous coating of certain drying, of contracting and firmly'gripping the cereals, such as rice and maize products, and lead or other marking material;- itv must be 2 fibers, such as. those obtained from cocoanut capable, of being easily'and smoothly 'cut by a hulls, cornstalks, sugarcane stalks and the like,

knife oripencil sharpener; it should have a subare. substantially non-absorbent. By suitably 70 stantially'smo'oth exterior for'the application of comminuting the rice hulls and/or the other a coating or finishing material such as' j'apan or substantially non-,absorbent'fibers and mixing varnish, should one be required; and in general, them .in various proportions with the cellulose; the pencil? sheath composed of the plasticcom flour, there can be produced a non-warpingan'd I pound must resemble the natural .wood sheath non-twisting pencil sheath. I have alsodi scov 75 in all its qualities as nearly as possible. Not only ered that this new mixture of powdered ceumose' I I must the composition sheath meet thespractiand finely comminuted non absorbent fibrous cal requirements, it must'also meetth'e'c'oinm'ermaterial can be bondedin an improved manner I cial requirement of being manufactured" at a by' the' use of a stable water-solublev compound,

price permitting it to'compete with wood sheaths. such .as casein, or preferably, a mixture of casein 30 'One reason why the plastic compositions hereand .a v s table-water-soluble cellulose compound, tofore proposed for pencil sheaths have not'met such as an alkyl derivativeof cellulose These all the requirements is that they have shrunk alkyl cellulose, compounds are at the presentv or contracted too much on drying and the pencil time, available in the open market'and arewa-tersheaths composed of them have warped andsoluble binding agents.advantageouslyused in twisted. The principal objectofthe-present incomposition. 'Ihey,may be prepared, for invention is to produce a composition pencilsheath stance, inthe manner described ,in1the patents which will not only meet the practical'requireto Lilienfeld Nos; 1,188,376 and;1,505,043 and merits set forth above but will also have the addinurnerousothers. -However, it is more convenient p 40 tional advantage that the pencil composedLof topurchase the alkyljc ellulose;binding agent I the new compound will remain straight and not fromamanufacturerthereof.1 Althoughan alkyl warp or twist. cellulose is the preferred bonding agent, its-mar- The improved composition for pencil sheaths ket price sometimes prevents its use, in which case contains several ingredients which have not hereit may be partly or wholly replaced by casein; 45v tofore been proposed for this purpose and which, Viscose has been proposed as a bonding agent combined with the usual pencil sheath composi for pencil sheath compositions, but I prefer not tion ingredients, produce the improved pencil to use'viscose because it'is' not stable. It begins sheath. Pencil sheath compositions in general to harden irreversiblyat 70 F., and slowly decontain a fiber or fibrous material, such as ascomposes even at low temperatures, so that un- 50 bestos, a fine cellulose material such as wood usual precautions must be taken in preparing it as a bonding agent, and it eventually loses its bonding characteristics in the composition.

By way of example of the preferred embodiment of my invention, I give the following specific formula Percentage Ingredient (by Weight) Alkyl cellulose binder n 2 Casein 17 Lime 2 Sodium fluoride 2. 5 Turkey red oil 4 Wood flour 54 Comminuted rice hulls 18.3 Coloring matter 2 The preferred composition for pencil sheaths given above may be compounded in the follow ing manner:-The alkyl cellulose is dissolvedin fourv times its weight of boiling. water, and the casein is mixed with about 125 parts of cool water.

To themixture of alkyl belluloseand casein is added the lime-mixed with about parts of water, and then the sodium fluoride mixed with about 50 "parts of water --is added. The whole mixture is thoroughly stirred until the mass is in plastic condition. The turkey redoil and the color 'are'next thoroughly stirred into the mass,

Tandthen a mixture of the wood fiour and the comminuted rice hulls is-added and the mass stirred until the composition is homogeneous. In this condition the plastic composition can be the purpose of pencils. a r 7 -If the price of alkyl cellulose is too high for use in making the preferred form of pencil sheath, an excellent substitutepencil'sheath,"very slightly producing composition sheath The foregoing composition can be compounded in .substantially the same manner described for the preferred composition;

Casein is a granular powder, it is therefore necessary to plasticize'it so as to convert it into a bonding material. it with a basic hydroxide, such as lime or amifi-monia, orwith a salt, such as sodium fluoride or sodium phosphate. If it is desired to substitute; ammonia for the sodium fluoride or sodium phos phate, then it is'desirable to add a preservative and'strengthening agent, such as hexamethylenet tetramine or phtalic anhydride. From one tovtwo I per cent of these preservative and strengthening extruded from the machines usually employed for I This can be done by mixing agents is sufficient. The turkey red oil acts as a softening agent for the casein. Soap or rubber substitute, that is, sulphonated oil, may advantageously be substituted for the turkey red oil; I

The proportions of 'thewood flour or other powdered cellulose and the comminuted rice hulls or other fibrous material may vary considerably.

Y I have found, however, that a non-warping and non-twisting composition pencil sheath can hardly be produced if a less proportionthan ten rial is used in the composition. And on the other hand, if too great a proportion of rice hulls or similar fibrous material is used, then the composition pencil sheath loses in appearance and is also likely-to be -tougher and not so easily cut by-the knife or-the pencil sharpening machine.

Accordingly, I have found that it is not desirable to use more than twenty or twenty-five per cent of rice hulls or equivalent fibrous material.

The addition of the coloring matter to the mixture is optional.

I WhatI claim is: I

1. A pencil sheath composition comprising a major quantity of wood flour, a minor quantity of a substantially non-water absorbent, comminuted cellulosic fibrous material, and" a Water-soluble binder- 2. A pencil sheath composition comprising a" major quantity of a. finely comminuted woody per cent of rice hullsorequivalent fibrous matematerialas its chief ingredient, a minor quantity i of finely comminuted. substantially non-water absorbent cellulosic fibrous'material, and a watersoluble cellulose compound as a binder therefor.

3., A pencil sheath composition comprising a major quantity of woodxfiour asitschief ingredient, about 10 to 25% of a substantially. nonwater absorbent, finely comminuted cellulose.

material, and a water-soluble binder.

4. A pencil'sheathrcomposition comprising a major quantity of wood flour, about 10 to 25 percent of comminuted ,rice hulls, "and a water soluble cellulose compound-as a binder; V

5; A pencil sheath compositionrcomprising the following ingredients in substantially the given percentages by. weight: alkyl cellulose binding agent 2%, casein 17%, lime 2%, sodium'fiuoride 2.5%, turkey redi oil 4%, wood flour 54%;, comminuted rice hulls 18.3 and coloring matter .2

6. A pencil sheath composition-including. a.

major quantity of a finely comminutedcellulosic' material having marked water absorbing properties and a minor quantity of a finely comminuted cellulosic material of greatly less waterv absorbing :propertiesjo, reduce the tendency of the pencil sheath to warp, twist and shrink. 1

7. A pencil sheath composition including a major quantity of a finely comminuted cellulosic material having, marked water absorbing properties and a lesser quantity, amounting to about,

10 to 25% of the total solids,of a finely comminuted cellulosic materialof greatlylesswateri absorbing properties-to reduce the tendency of the pencil sheath to warp, twist and shrink.

JORGEN E. THOMSEN.

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