US1985894A

US1985894A - Lead pencil and method of making same

Info

Publication number: US1985894A
Application number: US678993A
Authority: US
Inventors: Grossman Hareld
Original assignee: American Lead Pencil Co
Current assignee: American Lead Pencil Co
Priority date: 1933-07-03
Filing date: 1933-07-03
Publication date: 1935-01-01
Anticipated expiration: 1952-01-01

Description

- Jan. 1, 1935- GRQSSMAN v 1,985,894

LEAD New AND METHOD OF MAKING sum Filed Jul 's. 195s Patented Jan. 1, 1935 PATENT OFFICE LEAD PENCIL AND METHOD or MAKING SAME Hamid Grossman, Caldwell, N. 1., assignor to American Lead Pencil Company, Hoboken, N. 1., a corporation of New York Application July s, 1933, Serial No. 678,993

11 Claims. (01. 120-83) f of wood or similar fibrous substance; and said invention relates more particularly to the treatment of the rods of marking material or leads in such manner as to insure a strong and lasting bond between the lead and its enclosing sheath.

The leads or rods of marking material used in pencils of the type referred to are of varying composition; but usually they comprise in admixture with graphite or other marking material a certain quantity of an organic compound,

such as a waxy, oily or greasy substancetallow or stearic acid, for example-which conduces to I0 cements will adhere.

One object of the present invention is to effect a strong and lasting bond between the lead and its sheath, which object, together with other objects of the invention, I accomplish by reacting upon the surface of the waxy or greasy lead with an agent, such as chromic acid, which oxidizes the organic substances exposed on the surface, without iniuriously affecting the marking substance, forming soluble salts and oxidation products which are soluble in water and easily removed by washing. This step of the process may be satisfactorily and expeditiously performed by placing the leads in dipping cans and immersing them for a short time, say from two to five minutes, in a bath of chromic acid solution, formed, for example, by dissolving a chromate, such as sodium bi-chromate, in sulphuric acid. This exposure of the leadsto an acid capable of oxidizing the organic substances on the surface thereof should not be prolonged beyond the time required to effect such oxidation. since a longer exposure might result in undesirable reactions.

The leads are then washed in water to remove all acids and reaction products. Water washing sumces'for this purpose; but if desired the leads,

to grease, forming a coating towhich glues and after washing in water, may be immersed in an alkaline bath such as sodium carbonate, thereby insuring the neutralization of any remaining acid. It is highly desirable that all traces of acid be removed, not only to prevent deleterious effect 5 upon the leads, but also because it is not safe to put a lead containing acid to the mouth. Further, the absence of acids and other foreign matter conduces to the formation of a better bond. It is one of the advantages of the present process that it leaves no acid residuum, even when no alkaline neutralizer is used. Where an intervening impervious coating between the lead and the sheath is used some of the acid is unavoidably shut into surface pores of the lead.

By means of the process herein described the surface of the lead is brought into a condition which insures a satisfactory, a strong and a lasting bond, since the glue adheres directly to the lead, without the interposition of a coating of any sort. On the other hand, where a, chemically formed coating is interposed, if the' latter does not adhere properly to the lead, no bond is effected, or at best an imperfect bond, between the lead and the glue.

The accompanying drawing comprises a perspective view, partly in transverse section, illustrating a portion of a pencil made in accordance with the present invention. In said drawing, 1 is the lead having its surface degreased in the manner described herein; 2, 2, are the two sections of the wooden sheath; and 3 is the glue applied to the degreased surface of the lead and by which said lead is secured to the wooden sheath.

What is claimed is-- 1.The method of making pencils consisting in removing surface grease from the lead containing greasy material by an agent such as chromic acid, washing the lead, and attaching the wooden sheath to the lead by adhesive applied directly to said degreased surface of the lead. i

2. The method of making pencils consisting in removing surface grease from the leadv containing greasyonaterial by an agent which oxidizes said surface grease, washing the lead, and attaching the wooden sheath to the lead by adhesive applied directly to said degreased surface of the lead.

3. The method of making pencils by treating leads which contain greasy material with chromic acid thereby breaking down the greasy substance exposed on the surface of the leads, washing the wad and attaching the sheath to the lead by adhesive applied directly to said .deg'reased surface.

4. The method of making pencils by treating leads which contain greasy material with chromic acid thereby breaking down the greasy substance exposed on the surface of the leads, washing the leads by immersing them in an alkaline bath, and attaching the sheath to the lead by adhesive applied directly to said degreased surface.

5. As a new article of manufacture, a pencil comprising a core of marking material containing in the interior thereof greasy organic substance commingled therewith but having its surface substantially free from grease, and a sheath attached to said core by adhesive applied directly to its said surface. v

6. In the process of making pencils, the step of surface treating greasy pencil leads which comprises oxidizing the greasy surface to destroy its greasy characteristics.

7. In the process of making pencils, the steps of surface treatment of greasy pencil leads which comprise oxidizing the greasy surface to destroy its greasy characteristics and then washing.

with an agent capable of oxidizing surface grease to form soluble organic reaction products.

10. In the process of making pencils, the step of treating pencil leads to degrease the surface thereof which comprises immersing the leads in a sulphuric acid solution containing an agent capable of liberating oxygen.

11. The method of making pencils by treating leads which contain greasy material with chromic acid thereby breaking down the greasy substance exposed on the surface of the leads, removing from the surface of the leads the products of the action of the chromic acid and attaching the sheath to the lead by adhesive applied directly to said degreased surface.

- HAROLD GROSSMAN.