JP2019119793A - Solid writing body and solid writing body set using the same - Google Patents

Abstract

To provide a solid writing body having sufficient strength even it is non-burned solid writing body, providing smooth writing feeling during writing, easily being laminated o handwriting written previously, and excellent in wet-on-wet coating property.SOLUTION: There is provided a solid writing body containing a coloring material, an excipient, a filler, a binder resin and polypropylene having weight average molecular weight of 200,000 or less, and having content of the polypropylene of 5 mass% or less in all mass. Further the coloring material is a thermochromic pigment and the solid writing body has a friction member. There is provided a solid writing body set consisting of the solid writing body and a friction body.SELECTED DRAWING: None

Description

  The present invention relates to a solid cursive body. Furthermore, the present invention relates to a solid writing material capable of forming high concentration of handwriting and a solid writing material set using the same.

  Conventionally, unfired solid writing materials using coloring materials are practically used in the form of colored pencils and the like coated with a wood shaft etc., but since they are thinner than graphite and softer than fired cores, In order to provide core strength and to obtain sufficient handwriting density, it is necessary to stack the handwriting by over-coating. At that time, since the smoothness at the time of writing was not sufficient if the core strength was increased and it was difficult to be laminated on the previously written handwriting, the strength was maintained by applying a dibasic acid derivative, a polymethacrylic acid ester or the like. Techniques for providing as-is smoothness are applied (see, for example, Patent Documents 1 and 2).

  When the above-mentioned technology is applied to a solid writing material using a reversible thermochromic composition capable of alternately storing and retaining the state before and after discoloration as a coloring material in a constant temperature range such as a normal temperature range as a coloring material Since the handwriting density is lower than general-purpose colorants, overpainting may be repeated to obtain sufficient handwriting color density. At that time, frictional heat is generated by repeating coating at a high speed, and heat may be decolored to make the handwriting thin or discolored.

JP, 2015-209506, A Japanese Patent Application Laid-Open No. 11-61026 Japanese Utility Model Publication 7-6248

The present invention has solid core strength sufficient even with non-baked solid writing material, and at the time of writing, a smooth writing feeling can be obtained, it is easy to be laminated on the previously written handwriting, and solid material having excellent recoatability. It provides cursive writing.
In addition, even when a thermochromic microcapsule pigment containing a reversible thermochromic composition is used as a coloring material, the lamination amount of handwriting does not occur due to the frictional heat or color change due to the frictional heat at the time of over-coating. The present invention provides a solid writing material capable of forming dark and light shades and forming a high concentration of handwriting.

The solid writing material according to the present invention comprises a coloring material, an excipient, a filler, a binder resin, and a polypropylene having a weight average molecular weight of 200,000 or less, and the content of the polypropylene is 5% of the total mass. It is required to be not more than mass%.
Furthermore, it is required that the softening point of the polypropylene is in the range of 80 to 125 ° C.
Furthermore, the coloring material is composed of (i) an electron donating color forming organic compound, (ii) an electron accepting compound, (iii) a reaction medium for controlling the color reaction of (ii) and (ii). It is required to be a microcapsule pigment in which a reversible thermochromic composition is encapsulated in microcapsules.
Furthermore, it is required to further comprise a friction member.
Furthermore, a solid writing material set comprising any of the solid writing materials described above and a friction body is required.

According to the present invention, even a non-baked solid writing material has sufficient core strength, and at the time of writing, a smooth writing feeling is obtained, and furthermore, it is easy to be laminated on the previously written handwriting, and excellent in recoating properties. It will be As a result, writing and coloring with a smooth writing feeling can be performed without breaking at high writing pressure, and it is possible to easily improve the handwriting density and to form shading by overpainting.
In addition, even when a thermochromic microcapsule pigment is used as a coloring material, it does not cause discoloration or color change due to frictional heat at the time of over-coating, and forms light and shade due to the amount of lamination of handwriting, and high density It becomes a solid cursive body capable of handwriting formation.

  The solid writing material according to the present invention contains 5% by mass or less of polypropylene having a weight average molecular weight of 200,000 or less, in addition to a core component including at least a colorant, an excipient, a filler, and a binder resin. It is characterized by In particular, when a thermochromic microcapsule pigment containing a reversible thermochromic composition comprising (A), (B) and (C) components as a coloring material is applied, it is possible to impart an effect which has not heretofore been achieved. It will be better.

Examples of the coloring material used in the present invention include azo organic pigments such as disazo yellow AAA and pyrazolone orange, cyanine organic pigments such as phthalocyanine blue and phthalocyanine green, higher organic pigments such as quinacridone red, and dyes such as fan color Inorganic pigments such as fluorescent pigments, carbon black, iron black, red iron oxide, bitumen, rutile, titanium dioxide such as antanase, and dyes can all be used.
Further, in the present invention, even when coating is repeated at a high speed, it is difficult to generate frictional heat, so it is possible to apply a coloring material that changes color due to frictional heat, such as a thermochromic pigment.

As the coloring material that changes color due to the frictional heat, the coloring material whose color changes (color change, transparency, or color removal) is selected regardless of whether it is reversible or irreversible by heating and rubbing the writing with a friction material or the like. Applicable. In addition to those in which the coloring agent itself changes in hue, it is also possible to adopt a configuration in which the hue is changed by using in combination a transparent (decoloring) colorant and a general-purpose coloring material.
As a coloring material which changes color by heating, for example, a reversible type disclosed in JP-A-2012-219160, JP-A-2014-5422, etc. or an irreversible type disclosed in JP-A-2010-229332, etc. Is applicable.
In particular, the change of the handwriting is suitable because the thermochromic composition is encapsulated in the microcapsule, so that it can be stably expressed for a long time without causing a change in the composition. As the thermochromic composition contained in the microcapsule, from the viewpoint of repeated usability, accuracy of temperature change, etc., (i) electron donating color developing organic compound, (ii) electron accepting compound, (C) A reversible thermochromic composition comprising a reaction medium which determines the temperature at which both of the color reaction take place is suitable.

Reversible thermochromic compositions comprising the components (i), (ii) and (iii) described in JP-B-51-44706, JP-B-51-44707 and JP-B1-29398. The color changes before and after the predetermined temperature (color change point), and the color disappears in the temperature range above the high temperature side color change point, and the color development state is exhibited in the temperature range below the low temperature side color change point Among them, only one specific state exists in the normal temperature range, and the other state is maintained while the heat or cold required for the state to appear is applied, but the application of the heat or cold A reversible thermochromic composition having a characteristic (ΔH = 1 to 7 ° C.) having a relatively small hysteresis width, which returns to the state exhibited in a normal temperature range when the Type of microcapsule pigment can be applied .
Furthermore, relatively large hysteresis characteristics (ΔH = 8 to 50 described in JP-B 4-17154, JP-A 7-179777, JP-A 7-33997, JP-A 8-39936, etc. C), exhibiting large hysteresis characteristics described in Japanese Patent Application Laid-Open Nos. 2006-137886, 2006-188660, 2008-45062, 2008-280523, etc. That is, the shape of the curve plotting the change in coloring density due to the temperature change greatly differs between the case where the temperature is raised from the low temperature side from the color change temperature range and the case where the temperature is decreased from the high temperature side from the color change temperature range The color changes according to the route, and the color development state in the low temperature range below the full color development temperature or the decoloration state in the high temperature range above the complete color fading temperature is a specific temperature range. Microcapsule pigment was contained a reversible thermochromic composition heated decolorizable having chroma memory property can be applied.
In addition, as the reversible thermochromic composition having the color memory property, which is applied to the present invention, specifically, a temperature at which a full coloring temperature can be obtained only in a freezer compartment, a cold district or the like, ie -50 to 0 ° C C., preferably -40 to -5.degree. C., more preferably -30 to -10.degree. C., and the temperature at which the complete bleaching temperature can be obtained from frictional heating by a friction material, a familiar heating material such as a hair dryer, i.e. By specifying it in the range of preferably 50 to 90 ° C, more preferably 60 to 80 ° C, and specifying the ΔH value to 40 to 100 ° C, it is effective to maintain the color exhibited in the normal state (daily life temperature range) It can be made to function.

The microencapsulation of the thermochromic composition may be performed by interfacial polymerization, interfacial polycondensation, in situ polymerization, in-liquid curing coating, phase separation from an aqueous solution, phase separation from an organic solvent, melt dispersion cooling There are methods, airborne suspension coating methods, spray drying methods and the like, which are appropriately selected according to the application. Furthermore, depending on the purpose, a secondary resin film may be further provided on the surface of the microcapsule pigment to impart durability, or the surface characteristics may be modified for practical use.
The microcapsule pigment has an average particle diameter of 0.01 to 8.0 μm, preferably 0.1 to 5.0 μm, more preferably 0.3 to 3.0 μm, in terms of writing performance and handwriting density Are preferred.
The average particle diameter is determined by using the image analysis type particle size distribution measurement software "Mcview" manufactured by Mountech Co., and the area of the particles is determined, and the projected area circle equivalent diameter (Heywood diameter) is calculated from the area of the particle area. It is the value measured as the average particle diameter of the particle of equivalent volume sphere by the value. When the particle diameter of all particles or most of the particles exceeds 0.2 μm, equivalent volume sphere equivalent is obtained by Coulter method using a particle size distribution measuring device (product name: Multisizer 4e manufactured by Beckman Coulter Co., Ltd.) It is also possible to measure the average particle size as the average particle size of the particles of

  The microcapsule pigment can be added with various additives such as an antioxidant, an ultraviolet absorber, an infrared absorber, a solubilizer, an antiseptic and mildewproof agent, as long as the function of the microcapsule pigment is not affected. Moreover, it can also be set as the structure which produces the color change of colored (1) and colored (2) by mix | blending non-thermochromic coloring materials, such as dye and a pigment.

  The content of these coloring materials is preferably 40% or less based on the total amount of the solid writing material, from the viewpoint of the balance between colorability, writing taste, and strength. In addition, since the content of the coloring material varies depending on for wood axis, for mechanical pencil, etc. and is very light color to dark color, the amount of coloring material may not be limited generally to the above preferable amount or less And may be more than 40%, and may be appropriately adjusted within the range that does not impair the effects of the present invention.

As the excipient, for example, wax, gelling agent, clay and the like can be used. As the wax, any conventionally known one may be used. Specifically, carnauba wax, wax wax, bees wax, microcrystalline wax, montan wax, candelilla wax, sucrose fatty acid ester, dextrin fatty acid ester And polyolefin wax, styrene-modified polyolefin wax, paraffin wax and the like. As the gelling agent, conventionally known ones can be used, and examples thereof include 12 hydroxystearic acid, dibenzylidene sorbitols, tribenzylidene sorbitols, amino acid oils, alkali metal salts of higher fatty acids and the like. The clay mineral includes kaolin, bentonite, montmorillonite and the like.
Among the above-mentioned excipient, it is particularly preferable to contain at least one of polyolefin wax, sucrose fatty acid ester or dextrin fatty acid ester. Specific examples of polyolefin waxes include waxes such as polyethylene, polypropylene, polybutylene, α-olefin polymers, ethylene-propylene copolymers, ethylene-butene copolymers and the like.

In particular, among the polyolefin waxes, those having a softening point in the range of 100 ° C. to 130 ° C. and a penetration of 10 or less are preferably used because of their high writing feeling. When the penetration exceeds 10, the solid writing material tends to be too soft and difficult to write, and moreover, the handwriting is stretched on the paper at the time of rubbing and erasing (wax is thinned) and writing is performed It contaminates the blank area of the surface and causes color transfer or stain to other paper.
The method of measuring the softening point and the penetration of the polyolefin wax is standardized in JIS K2207, and the value of the penetration is 0.1 mm as the penetration 1. Therefore, the smaller the number, the harder the body, and the larger the number, the softer writing material.

  Specifically, Neo Wax Series (Yashara Chemical Co., Ltd. polyethylene), Sun Wax Series (Sanyo Chemical Industries Co., Ltd. polyethylene), High Wax Series (Mitsui Chemical Co., Ltd. polyolefin), AC polyethylene (Honeywell) Company-made polyethylene).

  As a compounding ratio of the said excipient material, 0.2-70 mass% is preferable with respect to the solid writing body total mass. If it is smaller than this range, it tends to be difficult to obtain a shape as a writable core, and if it is larger than this range, it tends to be difficult to obtain sufficient writing density. Preferably, it is 0.5 to 40% by mass, and if it is in this range, the shape of the solid writing material and the handwriting concentration can be compatible.

  The filler is blended for the purpose of improving the strength of the solid writing material and adjusting the writing taste. As a filler applied in the present invention, for example, talc, clay, silica, calcium carbonate, barium sulfate, alumina, mica, boron nitride, potassium titanate, glass flake and the like can be mentioned. In particular, talc and calcium carbonate are preferable in terms of moldability, and the influence on the color-changing performance when using microcapsule pigments.

  As a compounding ratio of the said filler, 10-65 mass% is preferable with respect to the solid writing body total mass. If it is smaller than this range, the strength tends to decrease, and if it is larger than this range, the coloring property may decrease and the writing taste may tend to be inferior.

Although binder resin is mix | blended in order to improve the intensity | strength of a solid writing material, natural resin and a synthetic resin can be used. Specific examples thereof include olefin resins, cellulose resins, vinyl alcohol resins, pyrrolidone resins, acrylic resins, styrene resins, amide resins, and basic group-containing resins. In particular, ethylene-vinyl acetate copolymer resin, ethylene-vinyl alcohol copolymer resin, and polyvinyl alcohol resin are preferable because molding stability is improved by combined use with a polyester polyol resin.
The amount of the binder resin added is preferably in the range of 0.5 to 5% by mass based on the total amount of the solid writing material.

Furthermore, low molecular weight polypropylene having a weight average molecular weight of 200,000 or less is used for the solid writing material of the present invention, and is added at 5% by mass or less in the total weight of the solid writing material.
The low molecular weight polypropylene has a weight average molecular weight (Mw) of 200,000 or less, preferably 5,000 or more, as determined by gel permeation chromatography (GPC method). Among them, those having a molecular weight distribution (Mw / Mn: measured by GPC method) of 4 or less are most excellent in overpaintability.
The production method is not particularly limited, but metallocene catalysts, Ziegler type polymerization catalysts, other polymers polymerized by a known method using a transition metal compound, an organic boron compound or aluminoxane as a polymerization catalyst, high molecular weight polypropylene is thermally decomposed or All can be targeted, such as those which are degraded by oxidation and reduced in molecular weight, and further, those separated by solvent extraction and the like as by-products at the production of high molecular weight polypropylene. In addition, an acid group of α, β-unsaturated carboxylic acid or its anhydride such as acrylic acid, methacrylic acid, ethacrylic acid, maleic acid, fumaric acid, itaconic acid or the like is introduced into the molecule by post-treatment. It is also good.

  Further, among the above-mentioned polypropylenes, those having a softening point in the range of 80 to 125 ° C. are particularly useful because they have a good performance balance when forming a solid writing material in terms of moldability, strength, and disintegrability.

  The melt flow rate (MFR) of the polypropylene is not particularly limited, but the MFR (ASTM D 1238: measured at 230 ° C., load 2.16 kg) is 40 to 3000 g / 10 min, preferably 50 to 2500 g / 10 min. The scope of thing applies. When the MFR is less than 40 g / 10 min, the melt viscosity at the time of molding is high, and the productivity is reduced. On the other hand, if it exceeds 3000 g / 10 min, the melt viscosity decreases and it becomes difficult to mold.

  As said low molecular weight polypropylene, Idemitsu Kosan Co., Ltd. product: L-MODU series, Clariant company make, Licocene PP series, Sanyo Kasei Co., Ltd. product, biscol series etc. can be illustrated.

  The polypropylene having a weight average molecular weight of 200,000 or less is added in an amount of 5% by mass or less, preferably 0.1% by mass or more based on the total mass of the solid writing material. If it exceeds 5% by mass, the hardness of the solid writing material is increased to inhibit the recoating property, and it becomes difficult to obtain a high concentration of handwriting, so addition of 5% by mass or less is essential.

  In addition, various additives can be added as needed. Examples of additives include viscosity modifiers, mildewproofing agents, preservatives, antibacterial agents, ultraviolet inhibitors, antioxidants, lubricants, and perfumes.

The solid writing material according to the present invention may be used alone as a writing material, or may be used as an inner core to form a core-sheath structure (double core) provided with an outer shell covering the outer peripheral surface. Such an outer shell can prevent the solid writing material inside from being damaged by physical contact and can also contribute to the improvement of the mechanical strength of the whole solid writing material. Although such an outer shell may or may not contain a coloring agent that contributes to the formation of a handwriting, generally the tip of a solid writing material is often cut in a cone shape, so the outer shell Often not affect. For this reason, it is general not to add a coloring agent to the shell.
Various additives can be added to the outer shell, if necessary, for the purpose of imparting various functions. Examples of additives include coloring agents, mildewproofing agents, preservatives, antibacterial agents, ultraviolet absorbers, antioxidants, lubricants, and perfumes. Any of these additives can be used.

  The solid writing material can be produced by using extrusion molding or compression molding. As a specific example of the core-sheath structure, a solid having an outer shell covering the outer peripheral surface of the inner core by disposing the outer shell on the outer peripheral surface of the lump of the inner core and performing compression molding with a press You can get cursive writing.

The thickness and length of the solid writing material can be arbitrarily selected according to the purpose. For example, considering that the solid writing material according to the present invention is used as a pencil core, the thickness is generally 2.0 to 5.0 mm, preferably 2.5 to 4.0 mm, The length is generally 60 to 300 mm, preferably 80 to 200 mm.
In the case of the core-sheath structure, the thickness of the inner core and the thickness of the outer shell can be arbitrarily selected, but if the thickness of the outer shell is thick, the impact resistance tends to be excellent, When the thickness of the outer shell is thin, the amount of exposure of the inner core is increased, and thus the usability tends to be excellent. The thickness of the outer shell with respect to the radial length of the inner core is preferably 10 to 100%, and more preferably 20 to 50%. The solid writing material according to the present invention can be used for applications other than pencils, such as the core of mechanical pencils, crayons, etc., and the thickness and length can be appropriately adjusted according to the application.

  The solid writing material according to the present invention can write on various writing surfaces. Furthermore, when a reversible thermochromic pigment is used as a coloring material, the handwriting can be discolored by rubbing with a finger or application of a heater or a cooler.

  Examples of the heating tool include electric heating color changing tools equipped with resistance heating elements, heating color changing tools filled with warm water or the like, and application of a hair dryer, but preferably, the friction member is a means capable of changing colors by a simple method. Used.

  As the friction member, an elastic body such as an elastomer, plastic foam or the like which is rich in elasticity and can generate appropriate friction upon friction to generate frictional heat is preferably used. As a material of the friction member, silicone resin, SEBS resin (styrene ethylene butylene styrene block copolymer), polyester resin, etc. can be used. The friction member can also be obtained by combining a solid writing material and a friction material which is a separate member having an arbitrary shape to obtain a solid writing material set, but a solid writing material or a solid writing material containing solid writing material in an outer case By providing the friction member on the exterior of the writing instrument, the portability becomes excellent. Specifically, a form in which the friction member is provided in the shape of a pencil or a crayon such as wood or paper, and the like may be mentioned.

  Examples of the cold heat tool include cold heat discoloring tools utilizing Peltier elements, cold heat discoloring tools filled with a refrigerant such as cold water or ice pieces, cold preservation agents, and applications of a refrigerator and a freezer.

Examples will be described below, but the present invention is not limited to these examples.
The weight average molecular weight (Mw) is a value measured by gel permeation chromatography (GPC method), and the melt flow rate (MFR) is a value measured at 230 ° C. under a load of 2.16 kg according to ASTM D1238. It is.

(Production of microcapsule pigment A)
5 parts by mass of 2- (2-chloroanilino) -6-di-n-butylaminofluoran as component (i), 5 parts by mass of 2,2-bis (4'-hydroxyphenyl) hexafluoropropane as component (ii) A reversible thermochromic composition comprising 3.0 parts by weight of 4,4 '-(2-methylpropylidene) bisphenol and 50 parts by weight of 4-benzyloxyphenylethyl laurate as component (iii) A solution obtained by mixing 30.0 parts by mass of an aromatic isocyanate prepolymer and 40.0 parts by mass of a cosolvent as a wall film material is emulsified and dispersed in an 8% polyvinyl alcohol aqueous solution, and stirring is continued while heating. Then, 2.5 parts by mass of a water-soluble aliphatic modified amine was added, and stirring was further continued to obtain a reversible thermochromic microcapsule suspension. The suspension was centrifuged to isolate reversible thermochromic microcapsules. The average particle diameter of the microcapsules is 2.3 μm and exhibits a behavior having a hysteresis characteristic of t ₁ : -8 ° C., t ₂ : -1 ° C., t ₃ : 52 ° C., t ₄ : 65 ° C. The color changed reversibly from black to colorless and from colorless to black.

(Production of microcapsule pigment B)
2.0 parts by weight of 3- (4-diethylamino-2-hexyloxyphenyl) -3- (1) -ethyl-2-methylindol-3-yl) -4-azaphthalide as component (i), component (ii) 4.0 parts by weight of 1,1-bis (4'-hydroxyphenyl) hexafluoropropane, 4.0 parts by weight of 1,1-bis (4'-hydroxyphenyl) n-decane as (C) caprylic acid as a component A microcapsule pigment was obtained in the same manner as the microcapsule pigment A, except that the thermochromic color memory composition was composed of 50.0 parts by mass of -4-benzyloxyphenylethyl (melting point 57 ° C.). The average particle diameter of the microcapsule pigment is 3.0 μm, and it exhibits a behavior having hysteresis characteristics of t ₁ : −24 ° C., t ₂ : −10 ° C., t ₃ : 42 ° C., t ₄ : 55 ° C. The color changed reversibly from blue to colorless and from colorless to blue.

(Production of microcapsule pigment C)
(I) 5.0 parts by mass of 9-ethyl (3-methylbutyl) amino-spiro [12H-benzo (α) xanthene-12,1 ′ (3′H) -isobenzofuran] -3′-one as a component ( B) 3.0 parts by mass of 4,4 '-(2-ethylhexane-1,1-diyl) diphenol as components, 5.0 parts of 2,2-bis (4'-hydroxyphenyl) -hexafluoropropane, (C) 30.0 parts by mass of an aromatic isocyanate prepolymer as a wall film material by heating and dissolving a thermochromic color memory composition comprising 50.0 parts by mass of capric acid 4-benzyloxyphenylethyl as a component A solution obtained by mixing 40.0 parts by mass of the cosolvent is emulsified and dispersed in an aqueous 8% polyvinyl alcohol solution, and stirring is continued while heating, 2.5 parts by mass of a water-soluble aliphatic modified amine is added, and the mixture is further stirred. To obtain a thermochromic microcapsule suspension continues. The suspension was centrifuged to isolate thermochromic microcapsules.
The average particle diameter of the microcapsules is 2.3 μm, and exhibits behavior with hysteresis characteristics of t ₁ : -20 ° C., t ₂ : -10 ° C., t ₃ : 48 ° C., t ₄ : 58 ° C. The color changed reversibly from pink to colorless and from colorless to pink.

  The composition of the solid writing material of an Example and a comparative example is shown in the following tables. In addition, the numerical value of the composition in a table | surface shows a mass part.

The contents of the raw materials in the table will be described along with the note numbers.
(1) Sanyo Kasei Kogyo Co., Ltd. product name: Sun Wax 171-P
(2) Toyokuni Oil Co., Ltd. product name: HS Christa 4100
(3) Mitsui Chemical Co., Ltd. product name: High wax 2203A
(4) Dai-ichi Kogyo Seiyaku Co., Ltd. product name: Sugar wax F-10
(5) Fuji Talc Industrial Co., Ltd. product name: FH-105
(6) Clariant Co., Ltd., trade name: Licocene PP 1502 (weight average molecular weight: 15,500, softening point: 85 ° C.)
(7) Clariant, product name: Licocene PP1302 (weight average molecular weight: 6,400, softening point: 90 ° C.)
(8) Idemitsu Kosan Co., Ltd. product name: L-MODU S400 (weight average molecular weight: 45,000, softening point: 93 ° C., MFR: 2000)
(9) Idemitsu Kosan Co., Ltd. product name: L-MODU S901 (weight average molecular weight: 130,000, softening point: 120 ° C., MFR: 50)
(10) Nippon Polypropylene Corporation, trade name: Novatec PP MA3 (weight average molecular weight: 397,000, softening point: 165 ° C., MFR: 11)
(11) BASF company product name: TINUVIN 770DF

(Manufacture of solid cursive writing)
Each compound is kneaded with a kneader, and the obtained kneaded product is compression molded by setting the outer diameter φ 3 mm and length 60 mm with a press, cooling to -20 ° C., and returning to normal temperature, thereby writing solid I got a body (pencil lead).

The following tests were performed about each solid writing material obtained by the said Example and comparative example. Although Comparative Example 4 was able to be molded, it was not strong enough to write because of the presence of an insoluble component, and it was not possible to measure the amount of wear and concentration.
<Method for measuring bending strength>
Bending strength of pencil lead by three-point bending test using Reotech Co., Ltd. (FUDOH RHEO METER RT-1003A-D PSO) in the strength test (fulcrum 40 mm, 10 mm / min) defined in JIS S6006-2007. Was measured. Each numerical value is an average value of 10 measurements.
<Test method of wear amount>
The weight change (mg / m) of the core at the time of writing by the concentration test (however, writing angle 75 °, load 400 gf, writing distance 6 m) defined in JIS S 6006-2007 was measured. Each numerical value is an average value of three measurements.
<Measurement method of concentration>
While visually checking the drawing (writing paper) of the pencil lead written by the density test (where writing angle 75 °, load 400 gf, writing distance 6 m) specified in JIS S 6006-2007, drawing is carried out by Konica Minolta It measured using the filter match | combined with the hue of a handwriting with the product made from a fluorescence spectrophotometer (FD-7). Each numerical value is an average value of 10 measurements.
The results of the test are shown below.

In addition, the evaluation regarding the symbol in the said table | surface is as follows.
Visual observation result of density O: uniform and strong handwriting is obtained.
×: A thin or mottled handwriting is obtained.

Preparation of Pencils Using the solid writing materials obtained by using Examples 1 to 6, six pencils were obtained by storing and forming in a round outer shaft (wood shaft).
When written on the paper using the pencil, it was possible to form black, pink, blue, red and ultra-blue handwritings.
The handwriting formed by the pencil using the core of Examples 1 to 4 was decolored (erased) by rubbing using a friction body made of SEBS resin.

Preparation of a Pencil with Friction Body A cylindrical friction body made of SEBS resin was fixed to the rear end of the pencil using the core of the Examples 1 to 4 through a metal connecting member to obtain a pencil with friction body .
The handwriting formed on the surface of the paper using the above-mentioned pencil with a friction body is decolored by rubbing using a friction body provided at the rear end, and a highly convenient pencil with a friction body having excellent portability is obtained I was able to.

Preparation of Solid Writing Body Set A solid writing body set was obtained by combining a pencil using the core of the above Examples 1 to 4 and a rectangular parallelepiped friction body made of SEBS resin.
The handwriting formed on the surface of the paper using the pencil was decolored by rubbing using a friction body, and it was possible to obtain a more convenient set in which writing and erasing can be easily performed.

Claims (5)

  A solid writing material comprising a coloring material, an excipient, a filler, a binder resin, and a polypropylene having a weight average molecular weight of 200,000 or less, and the content of the polypropylene is 5% by mass or less in the total mass .   The solid writing material according to claim 1, wherein the softening point of the polypropylene is in the range of 80 to 125 ° C.   A reversible heat-sensitive material comprising: (i) an electron-donating color-developing organic compound, (ii) an electron-accepting compound, (iii) a reaction medium for controlling the color reaction of (ii) and (ii) The solid writing material according to claim 1, which is a microcapsule pigment in which the color-changing composition is encapsulated in microcapsules.   The solid writing material according to any one of claims 1 to 3, further comprising a friction member.   A solid writing material set comprising the solid writing material according to any one of claims 1 to 4 and a friction material.