Compositions: coating or plastic – Coating or plastic compositions – Marking
Reexamination Certificate
2000-01-25
2002-05-28
Koslow, C. Melissa (Department: 1755)
Compositions: coating or plastic
Coating or plastic compositions
Marking
C106S031120
Reexamination Certificate
active
06395076
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a non-calcined lead of a colored pencil.
BACKGROUND OF THE ART
Conventionally, a non-calcined lead of a colored pencil is made by kneading raw ingredients such as a binder, a colorant, a body filler, a lubricant and a solvent, and forming the kneaded composition by extrusion. And as required, the mentioned solvent is removed by way of drying. Further, the conventional non-calcined lead of a colored pencil contains a wax, fats and oils, specifically a solid wax, fats and oils to obtain a coloring power.
Different from a calcined (baked) colored pencil lead having a skeleton of clay or a skeleton of carbon of carbide, a non-calcined lead of a colored pencil can contain wider variety of a colorant, and exhibits better writing characteristic because a binder is not treated by high temperature.
As a binder, an organic polymer is used. More concretely, various water-soluble binders such as sodium carboxymethylcellulose, polyvinyl alcohol and methylcellulose are used.
As a lubricant, various materials are used generally. Particularly, a boron nitride is used widely because it is similar in its crystallographic structure to graphite and has an excellent lubricity. Moreover, it is white and does not affect on color or tone of a colored pencil lead.
However with these conventional non-calcined leads of a colored pencil containing a solid wax, fats and oils, its writing portion cannot be erased with a rubber eraser because the wax, fats and oils contained herein is solid. On the other hand, in case of a non-calcined lead of a colored pencil prepared with wax, fats and oils that is liquid at room temperature together with a colorant, a body filler and a water-soluble resin, its forming is difficult and its strength and coloring power lowers. To overcome these problems, a non-calcined lead of a colored pencil may be prepared with oil immersion of the formed lead at room temperature. So that the non-calcined lead obtains erasability with a rubber eraser and coloring power owing to immersed wax, fats and oils while maintaining the forming performance and strength owing to a core of lead composition without wax, fats and oils. However, to prepare this oil-immersed colored pencil lead, the oil immersion process is necessary after the raw ingredients without wax, fats and oils are kneaded, formed and dried. This oil immersion process requires heating or drawing the vacuum in order to immerse oils into a lead. Further, after the oil immersion, the oil on the surface of a lead should be removed with a treatment under centrifugation, washing with solvent, wiping out, heating and so on. Accordingly, the processes is quite complicated and the production cost will be expensive.
Even though the conventional non-calcined lead of a colored pencil without any erasability with a rubber eraser, when it contains an organic polymer as a binder and further contains wax, fats and oils, it is still inferior to a calcined lead containing clay or carbide in mechanical strength such as flexural strength and point strength.
Waxes, oils and fats, regardless of being solid, semisolid, or liquid, have disadvantages of lowering not only mechanical strength but also the forming performance of a lead. Particularly, oily substance such as wax, fats and oils that is liquid at room temperature has a strong tendency to deteriorate mechanical strength and forming performance of lead. On the other hand, with solid wax, fats and oils, it is difficult to make a non-calcined lead of a colored pencil that can be erased by an eraser.
Regardless of having an erasability with a rubber eraser or not, a non-calcined lead of a colored pencil containing a conventional water-soluble binder has disadvantages in that its writing characteristic and coloring power deteriorate at high humidity and further its wood shaft breaks because the volume of a lead swells.
Regardless of having an erasability with a rubber eraser or not, a non-calcined lead of a colored pencil containing a boron nitride has disadvantages in that mechanical strength is not enough and the lead breaks often when being applied for writing or with a shock of dropping. And a boron nitride is quite expensive and its cost performance is not enough for preparing a colored pencil, which should be provided with low price. A development of a substitute to a boron nitride has been demanded among the skilled person in the art.
It is therefore an object of the present invention to provide a non-calcined lead of a colored pencil with an excellent erasability with a rubber eraser while maintaining a coloring power, mechanical strength and forming performance, which can be made by easy process without the above-mentioned oil immersion process.
It is another object of the invention to provide a non-calcined lead of a colored pencil with improved mechanical strength compared to the conventional non-calcined lead of a colored pencil even though containing an organic polymer as a binder and in case, further including fats and oils, and wax.
It is a further object of the present invention to provide a non-calcined lead of a colored pencil with improved mechanical strength, forming performance and improved coloring power though containing oily substance that is liquid at a room temperature.
It is another object of the present invention to provide a non-calcined lead of a colored pencil that does not swell nor deteriorate the writing characteristic and coloring power even at high humidity.
It is a further object of the present invention to provide a non-calcined lead of a colored pencil having better mechanical strength and difficult to break, and having better writing characteristic, coloring power and cost performance, compared to a lead containing a boron nitride as a lubricant.
DISCLOSURE OF THE INVENTION
As a result of an intensive study, the present inventor found that a non-calcined lead of colored pencils comprising a binder, a colorant, a body filler, an oily substance being a liquid at room temperature and one or more surfactant(s) having a H.L.B value of not less than 7 nor more than 18, can be made with an easy process and exhibits excellent erasability with a rubber eraser while maintaining a coloring power, mechanical strength and forming performance. The present invention is a non-calcined lead of a colored pencil comprising a binder, a colorant, a body filler, an oily substance being liquid at room temperature and one or more surfactants having a H.L.B. value of not less than 7 nor more than 18.
Specifically, a non-calcined lead of a colored pencil made with a following process exhibits an excellent erasability with a rubber eraser when applied to writing:
A binder or its solution is introduced into a mixture comprising a colorant, a body filler, and a solvent as required and kneaded. Then the mentioned solvent is removed. An O/W emulsion comprising an oily substance that is liquid at room temperature, one or more surfactants having a H.L.B. value of within the range between 7 and 18 and water is introduced into the resultant mixture and mixed together. After the mixed raw ingredients is formed, the water contained in the above-mentioned O/W emulsion and the mentioned solvent are removed, if any remains, to obtain a non-calcined lead of a colored pencil. In addition, the mentioned O/W emulsion preferably contains a water-soluble resin (a water-soluble binder) for stabilizing the emulsion.
The present inventor found also that with a non-calcined lead of a colored pencil comprising a colorant, a body filler, a binder, an oily substance such as a wax, fats and oils and one or more surfactant(s) having a H.L.B. value of not less than 1 less than 9 and a surfactant(s) having a H.L.B. value of not less than 9 nor more than 20, its coloring power, mechanical strength and forming performance are improved.
As a result of an intensive study, the present inventor found that when wollastonite, attapulgite, halloysite kaolin, sepiolite are used as a body filler, mechanical strength of a non-calcined lead of a colored pencil can be impro
Faison Veronica F.
Koslow C. Melissa
Merchant & Gould P.C.
Sakura Color Products Corporation
LandOfFree
Non-calcined lead of a colored pencil does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Non-calcined lead of a colored pencil, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Non-calcined lead of a colored pencil will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2831589