US2355639A - Pencil lead - Google Patents

Pencil lead Download PDF

Info

Publication number
US2355639A
US2355639A US487654A US48765443A US2355639A US 2355639 A US2355639 A US 2355639A US 487654 A US487654 A US 487654A US 48765443 A US48765443 A US 48765443A US 2355639 A US2355639 A US 2355639A
Authority
US
United States
Prior art keywords
impregnant
pores
marking
graphite
particles
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US487654A
Other languages
English (en)
Inventor
Monie A Ferst
Charles F Wysong
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
M A FERST Ltd
Original Assignee
M A FERST Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority to BE460908D priority Critical patent/BE460908A/xx
Application filed by M A FERST Ltd filed Critical M A FERST Ltd
Priority to US487654A priority patent/US2355639A/en
Application granted granted Critical
Publication of US2355639A publication Critical patent/US2355639A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D13/00—Pencil-leads; Crayon compositions; Chalk compositions

Definitions

  • Figure 1 is a side elevation of a pencil'lead somewhat enlarged.
  • porosity is meant the percentage of pores by volume of the specimen ready for impregnation which can be filled by gas or liquid.
  • the range of porosity of 'graphitic, lead pencil leads now in use is between sixteen per cent for hard leads and forty per cent at the outside for'soft leads.
  • the percentage of porosity is increased by an of graphite are.
  • Graphitic marking elements such as are in 7 common use in lead pencils are ceramic in char acter'and are preponlierantly composed of powdered graphite as a marking material and iinely divided clay as a bond which bond is glassy in characikr-as a result of the firing step of manufacturef'lhe finest particles of the clay are as small as substantially one-tenth micron and may range to substantially two microns while the graphite particles usually range between about onemicrofi and a possible eighty microns in well made elements.
  • the material so included may be removed by volatilization, by extraction with a solvent, or
  • the added material may be reduced in volum as by charring.
  • the ideal result contemplated by the present invention maybe obtained by a choice of graphite andiboncl particle sizes such as to result in no porosity, that is maximum compactness, and a provision of removable material, or material whose volume could be reduced by treatment, in
  • a separatemlass of substances which may be used forthe purpose of the invention is finely divided metal or metallic salts reducible to free metal under firing conditions.
  • the resulting metal in the fired lead can then be removed by pregnant filled pores or la unae of substantially increased size whereby e marking material yields more readily to abrasion and is consequently more friable for a given fiexural or point in writing in any given degree of softness or hardness because porosity will be more accurately controlled.
  • the writing qualities of a lead are drastically altered by any change in porosity, other factors being equal.
  • the pores normally developedin formation are subject to much varia-- tion due to variations in water content, extrustrength. If an oil and/or a waxy impregnant is used the increased proportion of oil and/or wax provides greater lubrication resulting in a smoother mark. The function of the oil and/or wax impregnant being to cause the graphite to 4 adhere to the paper, the mark will appear more intense. Further, the porosity being controlled, the leads of the invention, will have a more uniform body and, also, be more uniform in marking and in writing in every degree of softness and hardness.
  • the impregnant may contain water soluble coloring matter in which case the lead will produce a graphite mark or a colored graphite mark and if the color is water soluble to sufilcient extent a copying-pencil leadwill be provided of the so-called indelible type.
  • the impregnant may be a water soluble chromate in which case the lead will produce a mark that can be used for transfer purposes.
  • the impregnant, which is water soluble can contain an ionogen in which case the lead will produce a mark which will conduct electricity. The conductivity can be controlled by the amount of ionogen used.
  • the material of the lead aside from the porosity producing material shall be as compact as possible to provide a strong skeleton interspersed with the pores produced by the removed material.
  • a pencil lead made in accordance with the invention will bestronger for a comparable sof ness and softer for a comparable strength than the usual pencils sincethe impregnant adds strength to the material.
  • the increase in breaking strength is not inconsistent with-an increase of yield to abrasion noted above.
  • the element may be regarded as a skeleton of graphite and bond surrounding the impregnant filled pores. As wear exposes a-pore the surrounding skeletal substance will present edges thereof backed up-as resisting abrasiononly by the impregnant which; of itself has little resistance to displacement. Therefore, the abrasion pressure, method of tempering and so forth.
  • the type of pores developed by this invention will be unaflected by most of these factors, hence they would bemore uniform than the normal ,pores. Since the two types of porosity would be additive, the overall uniformity would be improved. 4 v
  • the process of producing graphitic marking e1ements which comprises: preparing a mixture including graphite, bonding material, and a discrete distending material; forming a marking element thereof; firing the thus formed element; subjecting the element, at some stage subsequent to the forming operation, to treatment acting to reduce the volume of the distending particles, and filling the thus formed pores with an impregnant.
  • the process of producing graphitic mark-' ing elements which comprises: preparing a mixture comprising graphite, clay, and. a discrete distending material; forming a marking element thereof; firing the thus prepared element; subjecting the material,- at some stage subsequent to the forming operation. to treatment to remove the particles of distending material so as to leave vacant the spaces occupied thereby during formation of the element; and filling said vacant spaces with an impregnant.
  • the process of producinggraphitic marking elements which comprises: preparing a mixture comprising graphite, bonding material and a discrete vaporizable distendingJniaterial; said last named material comprising from five to forty per cent by volume of the mass; forming a marking element from the thus prepared mix, firing the formed element with consequent vaporizasion can break off some of the skeletal material and rub off some of the impregnant into'adherence to the paper.
  • the impregnantfilled pores are interspersed fiowof the material since it is substantially intion of" the distending material; and filling the resulting pores with an impregnant.
  • a graphitic marking element comprising a body formed of graphiteand bonding material and having pores throughout the mass, the total volume of the pores being abnormally large-said pores filled with an impregnant.
  • a graphitic marking. element comprising a skeletal body of graphite particles bonded together by fired clay, enclosing pores which are of a larger volume than the volume of the interstices normally occurring between particles of graphite and bond of marking elements, said pores filled with impregnant.
  • impregnant is an oily and/or waxy material containing oil or, wax soluble materials.
  • impregnant is an oily and/or waxy material containing a wax soluble coloring material.
  • the process of producing graphitic marking elements which comprises: preparing a mixture including finely divided graphite and bonding material, the sizes and quantities of each size of particles of the material chosen to pro,- vide a minimum of voids, adding at least five per. cent by volume of discrete material to said mixture; forming a marking element of said mixture;., firing the thus formed element; subjecting the element, at some stage subsequent to the forming operation, to treatment acting to 4 reduce the volume of the particles of the discrete material; and filling the thus formed pores with an impregnant.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Wood Science & Technology (AREA)
  • Organic Chemistry (AREA)
  • Inks, Pencil-Leads, Or Crayons (AREA)
US487654A 1943-05-19 1943-05-19 Pencil lead Expired - Lifetime US2355639A (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
BE460908D BE460908A (enrdf_load_stackoverflow) 1943-05-19
US487654A US2355639A (en) 1943-05-19 1943-05-19 Pencil lead

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US487654A US2355639A (en) 1943-05-19 1943-05-19 Pencil lead

Publications (1)

Publication Number Publication Date
US2355639A true US2355639A (en) 1944-08-15

Family

ID=23936609

Family Applications (1)

Application Number Title Priority Date Filing Date
US487654A Expired - Lifetime US2355639A (en) 1943-05-19 1943-05-19 Pencil lead

Country Status (2)

Country Link
US (1) US2355639A (enrdf_load_stackoverflow)
BE (1) BE460908A (enrdf_load_stackoverflow)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2986472A (en) * 1959-02-18 1961-05-30 Georgia Kaolin Co Pencil clays
US3928520A (en) * 1971-08-19 1975-12-23 Pilot Kiko Kk Black lead and production thereof
US5318622A (en) * 1992-06-03 1994-06-07 Mitsubishi Pencil Kabushiki Kaisha Non-baked color pencil leads and method for preparing same

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2986472A (en) * 1959-02-18 1961-05-30 Georgia Kaolin Co Pencil clays
US3928520A (en) * 1971-08-19 1975-12-23 Pilot Kiko Kk Black lead and production thereof
US5318622A (en) * 1992-06-03 1994-06-07 Mitsubishi Pencil Kabushiki Kaisha Non-baked color pencil leads and method for preparing same

Also Published As

Publication number Publication date
BE460908A (enrdf_load_stackoverflow)

Similar Documents

Publication Publication Date Title
US3874856A (en) Porous composite of abrasive particles in a pyrolytic carbon matrix and the method of making it
US2642654A (en) Electrodeposited composite article and method of making the same
DE2420099A1 (de) Polykristalliner stoff aus kristallinem - nicht kristallinem kohlenstoff
US2355639A (en) Pencil lead
GB1466683A (en) Suspensions in non-aqueous fluid media
US2108794A (en) Hard carbide composition
GB1175876A (en) Compacted Sulphur and Method of Producing Same
US2597963A (en) Fluid impervious carbon article and method of making same
US3928520A (en) Black lead and production thereof
GB518429A (en) Improvements in fibrous products and processes of making the same
US3284314A (en) Fuel material for nuclear reactors and process and apparatus for its manufacture
US2986472A (en) Pencil clays
US3202619A (en) Graphitic neutron reflector containing beryllium and method of making same
GB575868A (en) Improvements in pencil leads and the like graphite marking elements
US2105310A (en) Agglutinant
Arthur et al. New polarographic Electrode employing controlled stirring
Pring et al. Mawbyite, a new arsenate of lead and iron related to tsumcorite and carminite, from Broken Hill, New South Wales
DE873872C (de) Kathode fuer elektrische Entladungsgefaesse
Alexander Bentonite.
JP3909144B2 (ja) 鉛筆芯
DE888137C (de) Verfahren zum Herstellen von Zuendstiften fuer Entladungsgefaesse
US2116187A (en) Lead pencils and method of preparing pencil leads
US2238771A (en) Pencil lead
Voice The history of the manufacture of pencils
DE823521C (de) Harte, chemische widerstandsfaehige Legierung