EP0422204A1 - Crayon en plastique - Google Patents

Crayon en plastique

Info

Publication number
EP0422204A1
EP0422204A1 EP19900907772 EP90907772A EP0422204A1 EP 0422204 A1 EP0422204 A1 EP 0422204A1 EP 19900907772 EP19900907772 EP 19900907772 EP 90907772 A EP90907772 A EP 90907772A EP 0422204 A1 EP0422204 A1 EP 0422204A1
Authority
EP
European Patent Office
Prior art keywords
weight
composition
composition according
pigment
polyethylene resin
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.)
Withdrawn
Application number
EP19900907772
Other languages
German (de)
English (en)
Inventor
Armand E. Brachman
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.)
Binney and Smith Inc
Original Assignee
Binney and Smith Inc
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
Application filed by Binney and Smith Inc filed Critical Binney and Smith Inc
Publication of EP0422204A1 publication Critical patent/EP0422204A1/fr
Withdrawn legal-status Critical Current

Links

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

  • This invention relates generally to compositions from which writing instruments such as crayons are fabricated and, in particular, to solid marking compositions which incorporate polyethylene resins.
  • the invention further relates to marking instruments, such as crayons, fabricated from such compositions.
  • crayons can be produced from mixtures of waxes, fatty acids, colorants and extenders. When properly formulated, crayons can be used to draw, write or color. They do, however, suffer from poor eraseability, low breaking strength, low softening point, and rapid wear rate.
  • U.S. Patent No. 2,882,246 teaches that the addition of 0.1 to 10% polyethylene increases the melting point.
  • U.S. Patent No. 3,933,708. teaches that addition of 0.1 to 10% of a high molecular weight polyethylene allows the use of lower melting point paraffin waxes.
  • U.S. Patent No. 4,212,676 teaches that one may obtain eraseability by combining "emulsifiable" polyethylenes with a mixture of liquid hydrocarbons, while Japan 1983-4751 teaches that it may be obtained by the use of polyacrylates.
  • Offenlegungsschrift 26 13 933 teaches that one must use a mixture of high density polyethylene or polypropylene and low molecular weight (m.w. ⁇ 10,000) polyethylene, in combination with wax and pigment, in order to provide acceptable properties in a colored pencil.
  • a related object is to produce a solid marking composition in which all the desirable properties may be optimized.
  • a more particular object is to obtain a plastic crayon composition having improved eraseability, ease of application, and strength, while bloom is eliminated.
  • Another object is to produce a solid marking composition having improved eraseability, ease of application, and strength, and essentially no bloom, without the necessity for including additives for that purpose.
  • the composition of the invention includes from about 15% up to about 50% by weight of a medium to high density polyethylene resin component having a specific gravity in the range of from about 0.93 up to about 0.96.
  • Low density polyethylene resins may be included in limited amounts, e.g., up to about 20%, and either a single resin or a blend of resins may be used, including both homopolymers and suitable copolymers, so long as the resin component meets the requirement of having a specific gravity in the stated range.
  • composition of the invention includes from about 20% up to about 55% by weight of a compatible plasticizer, and from about 3% up to about 20% by weight active material of a pigment.
  • the composition of the invention may also advantageously include a pigment dispersing agent, such as a fatty acid.
  • Further additives which may advantageously be employed include extenders or fillers, oxidation stabilizers, UV stabilizers, and mold release agents.
  • polyethylene resins are classified as low density (specific gravity of from about 0.90 up to about 0.92), medium density (specific gravity of from about 0.93 up to about 0.94), and high density (specific gravity of from about 0.95 up to about 0.96).
  • an improved solid marking composition such as those from which so-called plastic crayons are fabricated, may be formulated by maintaining the specific gravity of the polyethylene resin component within the range of from about 0.93 up to about 0.96.
  • the advantageous effect of utilizing a medium to high density polyethylene resin component of a plastic crayon formulation can be quantitatively seen by referring to the following table.
  • the desirable properties of a plastic crayon formulation while along the top row are listed the three general types of polyethylene resins.
  • Each row corresponding to a particular property states the resin concentration ranges in which the particular property can be optimized. These concentrations are stated in terms of weight percent of the resin and plasticizer matrix of the composition.
  • the ranges given for tip breaking strength (TBS) have a preferred minimum concentration (indicated by parentheses) as their lower limits.
  • TBS tip breaking strength
  • the table shows that eraseability may be optimized at a concentration of a medium density polyethylene component of from about 25% up to about 40% by weight of the resin and wax matrix.
  • a medium density polyethylene resin component It is possible to optimize all four properties when a medium density polyethylene resin component is used, but the concentration range in which this may be done is somewhat limited. Thus, while a medium density polyethylene resin component is workable, a medium to high density polyethylene resin component (specific gravity of about 0.94 up to about 0.96) is preferred because of the greater latitude provided in determining the concentration of the resin relative to the other components of the formulation.
  • composition of from about 15% up to about 50% by weight of a polyethylene resin component having a specific gravity in the range of 0.93 up to 0.96 produces an acceptable marking composition.
  • a preferred concentration range for this medium to high density polyethylene resin component is from about 20% up to about 40% by weight, while the most preferred range is from about 25% up to about 35% by weight, since, in this range, the optimization of the properties of the composition is best achieved.
  • the composition of the invention also includes from about 20% up to about 55% by weight of a compatible plasticizer, the function of which is to provide the composition with good application characteristics.
  • paraffin waxes are, for economic reasons, the preferred materials for use as plasticizers, a wide variety of materials may be utilized to achieve the same functional characteristics.
  • materials which are functional equivalents of the paraffin waxes are microcrystalline waxes (which may be present in concentrations of up to about 11%), synthetic waxes, vegetable fats and their hydrogenated or sulfonated derivatives, animal fats and their hydrogenated derivatives, fatty esters of glycols, and fatty acid salts of alkali and alkaline earth metals and aluminum.
  • the plasticizer In order to obtain the most advantageous properties in a plastic crayon formulation, it is preferred that the plasticizer have a melting point in the range of from about 125°F to 145°F (51°C to 63°C) .
  • Pigments which are useful in the composition of the invention include both inorganic and organic pigments, and mixtures of these materials.
  • the inorganic pigments which may be used include the conventional ones, such as iron blue, iron oxides, zinc oxide, ultramarine blue, titanium dioxide, and mixtures of these materials.
  • the organic pigment may be of the azo, naphthol, or phthalo type, including phthalocyanines and carbazoles.
  • the pigment may further include toners or lakes made from acid or basic dyes, and mixtures of these materials.
  • the pigment should have a particle size in the range of from about 0.1 microns up to about 25 microns.
  • a smaller particle size contributes to more efficient color utilization; consequently, it is preferred that the particle size.be in the range of from about 0.3 microns up to about 20 microns. Most preferably, it is in the range of from about 0.5 microns up to about 15 microns.
  • an acceptable level of color can be obtained when the pigment is present in an amount of from about 3% up to about 20% active material by weight of the composition.
  • the composition of the invention may include a pigment dispersing agent. The advantage in including this component is that good dispersion of the pigment in the polyethylene matrix results in good glide properties in the plastic crayon made from the composition of the invention.
  • Suitable pigment dispersing agents are the fatty acids, including both saturated and unsaturated fatty acids, and including either single compounds or mixtures of several.
  • Preferred materials are fatty acids having from 14 to 24 carbon atoms, and most preferred from a functional and cost standpoint is stearic acid.
  • the pigment dispersing agent should be present in an amount of at least about 5% by weight of the composition, with a workable concentration range being from about 5% up to about 40% by weight. In the plastic crayon composition of the present invention, it is preferred to have the pigment dispersing agent present in an amount of about 35% by weight of the composition.
  • the composition of the invention may also advantageously include a filler or pigment extender, and many materials useful for this purpose are well known. A few examples of such materials are calcium carbonate, silica, alumina, talc, clays, and feldspars. Ordinarily, these pigment extenders or fillers are present in an amount of up to about 20% by weight of the composition, though a preferred concentration in the practice of the present invention is about 10% by weight of the ' composition.
  • a mold release agent Another component which may be incorporated into the composition of the invention is a mold release agent, since a writing instrument of a solid, unitary piece of material, such as a plastic crayon, is ordinarily fabricated from the composition by injection molding.
  • Typical mold release agents include the Group IIA metal salts of fatty acids, and a preferred material for use in the present invention is calcium stearate.
  • Such materials are usually effective at a concentration of from about 0.2% up to about 2% by weight of the composition.
  • the mold release agent be present in an amount of from about 0.4% up to about 0.7% by weight of the composition.
  • Still further additives may be incorporated into the composition of the invention, including, for example, oxidation stabilizers and UV stabilizers.
  • Typical oxidation stabilizers useful in compositions of this sort are sterically hindered phenols. They ordinarily are effective at concentration levels of from about 0.03% up to about 0.2% by weight.
  • Typical UV stabilizers useful in compositions of this sort are hindered amine light stabilizers (HALS) and benzotriazoles. They ordinarily are effective at concentration levels of from about 0.1% up to about 2% by weight.
  • a number of properties of a plastic crayon composition are important to judging its acceptability; namely, tip breaking strength, barrel breaking strength, erasability, sharpenability, ease of application, and absence of bloom. Encompassed within the property of ease of application are smoothness, glide, and color transfer. What is achieved by the present invention is a composition in which all of these properties can be optimized.
  • a composition having an optimal balance of properties is one which performs well enough in each of certain tests that the composition may be said not to have any notable deficiencies. The determination of whether a particular composition meets this standard must be based, therefore, on a consideration of the performance of a writing instrument formed from the composition with respect to each individual criterion in view of all the remaining criteria. The particular tests by which the performance of a composition is judged are described below.
  • Tip breaking strength is determined by pushing a horizontal 10 cm by 1.9 cm diameter rod onto the tip of the writing instrument, held horizontally at 90° to the rod, until the tip breaks. The force exerted at the time of breakage is the breaking strength.
  • the horizontal rod is affixed to the upper jaw of an Instron testing machine. The jaw is lowered at a rate of 2.5 cm per minute during the test.
  • the writing instrument is held firmly in a holder, and the instrument is inclined upward 11°15' from horizontal to simulate a pressure geometry present when writing or drawing.
  • the tip of the instrument extends 1.5 cm out from the holder, and the end of the tip is positioned below the center of the rod affixed to the upper jaw of the testing machine.
  • the tip breaking strength should be at least 5 pounds to be acceptable, and preferably 6 pounds or higher.
  • Barrel breaking strength is determined by pushing a horizontal 10 cm by 1.9 cm diameter rod onto the center point of the writing instrument, which is positioned 90° to the rod and is supported on 10 cm by 1.5 cm diameter support rods. The distance between the center lines of the support rods is 6.35 cm. The push rod, affixed to the upper jaw of an Instron testing machine, is lowered at a rate of 2.5 cm per minute. The force exerted at the time of breakage is the breaking strength.
  • the barrel breaking strength should be at least 9 pounds to be acceptable, and preferably 10 pounds or higher.
  • Erasability is judged by success in removal of a uniform layer of color on a 4.5 cm by 4.5 cm square of 20 lb. bond paper. Other types of paper can be used but will .be either more or less easily erased.
  • the color is applied by placing the writing instrument in the vertical position in a holder. A 850g weight is mounted on the holder. The holder is moved back and forth by an electrically driven machine, such that the tip of the instrument marks the paper. At the same time, a cam moves the holder forward in the horizontal direction so that the instrument does not write over previously colored areas.
  • An Eberhard Faber "Pink Pearl #100" eraser is used to remove color from about a one-half inch guide strip of the colored area. The removal area is rubbed repeatedly with gentle pressure until no more color can be removed, but not so vigorously as to damage the surface of the paper. A numerical rating is assigned based on visual inspection of the erased area:
  • Sharpenability is judged by sharpening the coloring instrument with a hand held sharpener fitted with a steel cutting blade. Using moderate pressure, one sharpens the point to 1 mm diameter or less. Sharpen ⁇ ability is judged by ability to sharpen to 1 mm without breakage. The force needed to turn the coloring instrument should not be excessive. The shavings should be smooth and fall freely from the sharpener.
  • the numerical rating criteria are as follows:
  • Sharpenability expressed as a value on a rating scale of 1 to 10, with 10 being best, should be at least 7 to be acceptable, and preferably 8 or higher.
  • Ease of application expressed as a value on a rating scale of 1 to 10, with 10 being best, should be at least 6 to be acceptable, and preferably 8 or higher. Bloom
  • Bloom is judged visually by rubbing a portion of the coloring instrument with a paper wiper and then judging the degree to which the wiped area differs in color from an unwiped area. Bloom manifests itself as a gray-white surface exudate on the surface of the coloring instrument. Some formulations also developed bloom on the surface of colorant present on the surface of paper or other coloring surface. The presence of bloom is expressed as none, slight, moderate or heavy. As a practical matter, any amount of bloom is highly undesirable.
  • M.I. 400
  • the heating chamber was set to 284°F (140°C).
  • the paraffin wax and stearic acid were added when the chamber temperature had risen to about 104°F (40°C).
  • the melt temperature had risen to 158°F (70°C)
  • the HDPE pellets were added.
  • the melt temperature was allowed to reach 284°F (140°C), and mixing was continued until a homogeneous melt resulted.
  • the calcium stearate and pigment were then added. Heat was reduced. Mixing was continued for about 40 minutes after the temperature had dropped to 248°F (120°C) or lower. The mix was discharged and molded.
  • Test crayons were molded by placing chips of the above formulation in a 4" long by 5/16" diameter aluminum mold, electrically heating to about 300°F (149°C), adding additional chips to fill the crayon cavity, and then cooling in a tray of room temperature water. After it had solidified, the test crayon was pushed from the mold.
  • Example #4 The same procedure was followed as in Example

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)

Abstract

Une composition solide de marquage comprend entre 15% et 50% en poids d'une résine de polyéthylène ayant une densité comprise entre 0,93 et 0,96 environ. En outre, cette composition comprend entre 20% et 55% en poids environ d'un plastifiant compatible, et entre 3% et 20% en poids de la substance active d'un pigment. Facultativement, la composition peut comprendre un agent dispersant du pigment, tel qu'un acide gras. D'autres additifs qui peuvent être utilisés avec avantage sont des agents d'allongement ou des charges, des stabilisateurs de l'oxydation, des stabilisants UV et des agents de démoulage. On utilise cette composition pour produire des instruments de marquage ayant une résistance à l'effaçement, une facilité d'application, une résistance à la rupture de la tige et de la pointe étonnamment améliorées, accompagnées d'une élimination totale de l'efflorescence.
EP19900907772 1989-04-20 1990-04-20 Crayon en plastique Withdrawn EP0422204A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US34116489A 1989-04-20 1989-04-20
US341164 1989-04-20

Publications (1)

Publication Number Publication Date
EP0422204A1 true EP0422204A1 (fr) 1991-04-17

Family

ID=23336485

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19900907772 Withdrawn EP0422204A1 (fr) 1989-04-20 1990-04-20 Crayon en plastique

Country Status (4)

Country Link
EP (1) EP0422204A1 (fr)
JP (1) JPH03505609A (fr)
AU (1) AU627308B2 (fr)
WO (1) WO1990012845A1 (fr)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE4431897C2 (de) * 1994-09-07 1996-04-04 Hoffmann Sonax Kg Verfahren zur Beseitigung von Lackschäden
JP6378030B2 (ja) * 2014-10-02 2018-08-22 株式会社サクラクレパス 固形マーカーとこれを含む塗装具

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3933708A (en) * 1973-05-24 1976-01-20 Sun Oil Company Of Pennsylvania Crayon wax composition
DE2613933A1 (de) * 1976-04-01 1977-10-13 Faber Gmbh Eberhard Malstift, malkreide oder malmine

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO9012845A1 *

Also Published As

Publication number Publication date
AU5564990A (en) 1990-11-16
JPH03505609A (ja) 1991-12-05
AU627308B2 (en) 1992-08-20
WO1990012845A1 (fr) 1990-11-01

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