JP5138192B2 - Writing instrument - Google Patents

Description

  The present invention relates to an ink composition for writing instruments, and more specifically, a writing film can be formed on letters, numbers, pictures, etc. that have been printed or written in advance on paper or the like, and written by rubbing with an eraser or the like. The present invention relates to an erasable ink composition for a writing instrument that can easily erase a film.

  Conventionally, many erasable ink compositions that can erase handwriting written on paper or the like with an eraser or the like have been proposed.

Examples of oil-based erasable ink compositions that can be erased with such an eraser include Japanese Patent Application Laid-Open No. 54-156731, “Ball Pen Writing Instruments”, Japanese Patent Application Laid-Open No. 56-155266, “Ball Point Writing Instruments”, Japanese Patent Application Laid-Open No. 57-57. No. 170967 “initially erasable ink composition for ballpoint pen writing instrument”, Japanese Patent Application Laid-Open No. 57-170968 “Ink composition capable of initial erasure”, etc. An ink composition of 6 million cps and an ink composition having a high solid content concentration such as a rubber component and a pigment are disclosed. Furthermore, an ink composition having a pigment particle size of 5 μm or less as disclosed in JP-A-60-158280 “Erasable ballpoint pen ink”, Japanese Patent Publication No. 3-54712 “Erasable ballpoint pen ink”, etc. However, JP-A-2001-354893 “ink composition” is known as a prior art.
"JP-A-54-156731" "Japanese Patent Laid-Open No. 56-155266" "Japanese Unexamined Patent Publication No. 57-170967" "Japanese Unexamined Patent Publication No. 57-170968" "JP-A-60-158280" "Japanese Patent Publication No. 3-54712"

  However, pigment sedimentation can be suppressed by making the ink viscosity extremely high as in Patent Documents 1, 2, 3, and 4. Since the ink viscosity is high, there is little ink out, and blurring or the like appears in the handwriting. In addition, when the solid content concentration is high, the initial writing after being left for a while at cap-off is bad, and when it is terrible, there is a problem that the solid matter is clogged and writing is poor.

  Further, in Patent Documents 5 and 6, in order to solve the problem, the handwriting is improved by using a relatively low viscosity ink. The pigment gradually accumulates on the bottom of the glass, and the weight of the pigment entangles the pigments with each other, causing the pigments to adsorb and densely deposit, thereby forming a hard cake, thus preventing pigment settling. For this reason, when the thickness is less than 5 μm, the pigment enters the gap between the fibers on the paper surface, and even if an attempt is made to erase the handwriting with an eraser or the like, a thin handwriting remains.

  Thus, if the hard cake inhibitor is not used, the pigments are entangled with each other by the weight of the pigments, and the pigments adsorb and form a hard cake. For this reason, there is a problem that the pigment is not redispersed even when shaken.

  An object of the present invention is for a writing instrument that can form a writing film on characters, numbers, pictures, etc. that have been printed or written in advance on paper or the like, and that can be easily erased by rubbing with an eraser or the like. An erasable ink composition and a writing instrument using the same are provided.

In order to solve the above problems, the present invention provides:
“1. In a writing instrument comprising a ballpoint pen tip holding a ball rotatably at the tip of the ink containing cylinder or directly via a chip holder , a ceramic stirring ball is built in the ink containing cylinder. and at least a hydrocarbon solvent, pigment, a rubber-based resin, for writing instruments erasable ink composition comprising a hard cake inhibitor, the hard cake inhibitor is a fatty acid amide wax, content, ink composition 0.5 mass% or more and 15.0 mass% or less based on the total mass, and the rubber-based resin is composed of one or more selected from ethylene propylene rubber, isopropylene rubber, and butadiene rubber, In addition, an erasable ink composition for a writing instrument having an ink viscosity at 20 ° C. of 35 mPa · s or more and 700 mPa · s or less is used as an ink container. Writing instrument characterized by being directly packed in
2. The writing instrument according to claim 1, wherein the content of the rubber-based resin is 0.1% by mass or more and 10.0% by mass or less with respect to the total mass of the ink composition.
3. The writing instrument according to Item 1 or 2, wherein the hydrocarbon solvent has a boiling point of less than 150 ° C.
4). The writing instrument according to any one of Items 1 to 3, wherein the pigment has an average particle diameter of 5 μm or more and 100 μm or less.
5. The writing instrument according to any one of claims 1 to 4, wherein the fatty acid amide wax is in a paste form. Is.

  The present invention relates to an ink composition comprising at least a hydrocarbon solvent, a pigment, a rubber resin, and a hard cake inhibitor, wherein the hard cake inhibitor is a fatty acid amide wax. As a result, it was possible to provide an erasable ink composition for a writing instrument that has good handwriting, excellent erasability with an eraser, etc., and suppresses hard cake formation even when it settles.

  The first feature of the present invention is that a fatty acid amide wax is used as a hard cake inhibitor in the erasable ink composition.

  A hard cake is a pigment that settles in the ink and gradually accumulates on the bottom of the ink over a long period of time. It will be deposited on. Once the pigment has settled and formed a hard cake, the pigment will not be redispersed even if shaken, so the effect of causing steric hindrance between the pigments to prevent the pigments from adsorbing each other In the present invention, a certain inhibitor is used as a hard cake inhibitor.

  It is considered that the fatty acid amide wax is colloidally dispersed in the ink composition to form a three-dimensional network structure. Therefore, by forming a three-dimensional network structure between the pigment, the rubber-based resin and the fatty acid amide wax, by acting as a three-dimensional obstacle that suppresses the entanglement of the pigments, It is thought that hard cake formation can be suppressed. Therefore, even if the pigment once settles, the pigment can be redispersed by shaking by suppressing hard cake formation.

  The fatty acid amide wax used in the present invention includes methylene bis stearic acid amide, ethylene biscapric acid amide, ethylene bis lauric acid amide, ethylene bis stearic acid amide, ethylene bishydroxy stearic acid amide, ethylene bisbehenic acid amide, hexamethylene bis. Examples include stearic acid amide, hexamethylene bisbehenic acid amide, N, N′-distearyl adipic acid amide, N, N′-ethylene bis (12-hydroxystearic acid amide), and the like.

  Specifically, trade names manufactured by Kyoeisha Chemical Co., Ltd .; Talen 5200-25, 5500-25, 5400-25, M-1021B, 6200-20, ED-2020, 7200-20, KU-700, KY-2000, 7500-20, 8200-20, 8300-20, 8700-20, 8900-25, BA-600, KY-5020, VA-750B, VA-800, Flownon SH-290, HR-2NT, ED-1000, SP-1000, EDM-10, etc. Product names manufactured by Nippon Kasei Co., Ltd .; Sripacs C, L, E, H, B, ZHS, ZHB, ZSA, Biamide LA, Diamid Screw 200LA, Kawaken Fine Chemicals Trade name: Parisine 285 and the like can be exemplified.

  The above fatty acid amide waxes may be used alone or in combination of two or more. The shape can be any of powder, liquid and paste.

  In the case of a paste, since it is already a pregel, it can be mixed and stirred with other components as it is. However, in the case of powder or liquid, processing such as dissolving in an organic solvent in advance and swelling, and processing such as heating become indispensable. For this reason, in the case of a paste form, it is preferable to use a paste form that does not require any troublesome processing because it does not require a powdery or liquid process.

  Furthermore, if the fatty acid amide wax is less than 0.1% by mass, the hard cake inhibitor may be insufficient, and considering the stability over time, it is preferably 15.0% by mass or less. Therefore, 0.1 mass% or more and 15.0 mass% or less are preferable.

  The present invention uses a rubber-based resin that has good fixability to the paper surface when written and has good peelability. The rubber-based resin functions to adsorb the pigment and the fatty acid amide wax by being dissolved, and thus, by forming a stable three-dimensional network structure, it is possible to prevent the pigment from being entangled with each other. Hard cake formation can be suppressed.

  Rubber resins include butyl rubber, ethylene propylene rubber, isopropylene rubber, butadiene rubber, styrene butadiene rubber, polybutadiene rubber, acrylonitrile butadiene rubber, chloroprene rubber, nitrile rubber, acrylic rubber, urethane rubber, silicone rubber, polysulfide rubber, polyolefin Examples thereof include natural rubbers such as thermoplastic thermoplastic elastomers, styrene thermoplastic elastomers, and latexes. Among these, butyl rubber, ethylene propylene rubber, isopropylene rubber, butadiene rubber, and styrene butadiene rubber that are easily dissolved in a hydrocarbon solvent are more preferable. These rubber resins can be used alone or in combination of two or more.

  Furthermore, if the rubber-based resin is less than 0.1% by mass, the ink fixability to the paper surface is slightly inferior, and if it exceeds 10.0% by mass, the ink fluidity is slightly inferior, the ink output is small, and the amount is very small. There is a risk that a slight blur or the like may occur. Therefore, 0.1 mass% or more and 10.0 mass% or less are preferable.

  The second feature of the present invention is that a hydrocarbon solvent is used as a solvent in the erasable ink composition.

  A hydrocarbon solvent is used as the solvent used in the present invention. It must be able to be written and erased on the letters written on the paper, etc., up to the handwriting of the writing instrument or printed matter. At this time, if the colorant contained in the character or the like written on the paper surface is dissolved by the solvent, the colorant will be lifted, so that it will not return to the original character after erasure. Since the hydrocarbon solvent has a very low ability to dissolve these colorants, it can be written and erased satisfactorily without raising the components in the document.

  In consideration of the solubility of the rubber resin, a hydrocarbon solvent having a solubility parameter equivalent to the solubility parameter of the rubber resin is used. Specifically, since the solubility parameter of the rubber-based resin suitably used in the present invention is 7.0 or more and 10.5 or less, a hydrocarbon solvent having a solubility parameter of 7.0 or more and 10.5 or less is used. It is preferable.

  As the hydrocarbon solvent suitably employed, when the boiling point is 150 ° C. or higher, the drying of the solvent is slow, so if the hydrocarbon solvent is selected so that the boiling point is less than 150 ° C., there is immediate drying. Since drying after writing is fast and it does not require a long time to form a dry film of the rubber-based resin, it is more preferable. Specifically, methylcyclohexane (boiling point 100.9 ° C), ethylcyclohexane (boiling point 131.8 ° C), n-heptane (boiling point 98.4 ° C), isooctane (boiling point 99.2 ° C), n-octane (boiling point) 125.6 ° C), isohexane (boiling point 60.0 ° C), normal hexane (boiling point 68.7 ° C), cyclohexane (boiling point 80.7 ° C), hexane (boiling point 68.7 ° C), and the like. You may use these individually or in mixture of 2 or more types.

  The pigment is not particularly limited, and examples thereof include inorganic, organic and processed pigments. Specifically, carbon black, aniline black, ultramarine, yellow lead, titanium oxide, iron oxide, phthalocyanine series, azo series, quinacridone series, quinophthalone series, selenium series, triphenylmethane series, perinone series, perylene series, goxazine series, Examples include aluminum pigments, pearl pigments, fluorescent pigments, phosphorescent pigments, reversible thermochromic pigments, and the like. In addition, a microcapsule pigment in which a colored body in which a pigment is dispersed in a medium as a colored resin particle body is encapsulated or solidified in a shell made of a resin wall film forming substance by a known microencapsulation method may be used. good. Further, colored resin particles in which the pigment is covered with a transparent or translucent resin or the like, or colored resin particles or colorless resin particles colored with a pigment or a dye can also be used. These pigments may be used alone or in combination of two or more. The content is preferably 1% by mass or more and 50% by mass or less based on the total amount of the ink composition in consideration of stability over time.

  The pigment described above can be appropriately selected depending on the purpose of use. For example, carbon black, titanium oxide, iron oxide, aluminum pigment, pearl pigment, etc. are highly concealed, and when written on written characters or printed matter, the characters and printed matter can be concealed like correction liquid or scratch ink. . On the other hand, a fluorescent pigment, phosphorescent pigment, or a colored resin particle body in which a pigment is dispersed in a medium is encapsulated or solid-solubilized in a shell made of a resin wall film-forming substance by a known microencapsulation method or the like. Capsule pigments, colored resin particles with pigments covered with transparent or translucent resin, colored resin particles or colorless resin particles colored with pigments or dyes, etc. have low concealment and are written like fluorescent ink If you write on a letter or printed matter, you can see through the letter or printed matter.

  When the pigment particle size is less than 5 μm, the pigment enters the gap between the fibers on the paper surface, and even if the handwriting is to be erased with an eraser or the like, the handwriting remains thin, or the particle size is too large if it exceeds 300 μm. Since the ballpoint pen tip may be clogged, it is preferably 5 μm or more and 300 μm or less. Furthermore, when considering the sedimentation of the pigment, it is preferably 100 μm or less.

  Furthermore, as other additives, surfactants, rust inhibitors, dispersion aids, lubricants, plasticizers, and the like can be selected and added as appropriate. Moreover, other organic solvents can be contained for the purpose of adjusting the viscosity.

  As an erasable ink composition for a writing instrument of the present invention, a suitable ink viscosity is less than 10 mPa · s in an environment of 20 ° C., and the hard cake suppressing effect is reduced. Since it may generate | occur | produce, 10 mPa * s or more and 1000 mPa * s or less are preferable.

Next, an Example is shown and this invention is demonstrated.
The erasable ink composition for a writing instrument of Example 1 includes methylcyclohexane as a hydrocarbon solvent, fatty acid amide wax (trade name manufactured by Kyoeisha Chemical Co., Ltd .; Talene 5200-25) as a hard cake inhibitor, and rubber resin. Ethylene pyropyrene rubber (trade name manufactured by JSR Co., Ltd .; EP22), and an aluminum pigment (trade name manufactured by Showa Aluminum Piuder Co., Ltd .; Friend Color F701SI) are used as a pigment, and a predetermined amount is weighed. It was completely dissolved using a disper stirrer to obtain an erasable ink composition for writing instruments. Specific blending amounts were as follows. The ink viscosity was measured using a Brookfield DV-II viscometer (CPE-42 rotor) at 20 ° C. and a shear rate of 192.0 sec ⁻¹ (rotation speed: 50 rpm). was s

Next, an Example is shown and this invention is demonstrated.
Example 1
Methylcyclohexane 82.0% by mass
Fatty acid amide wax (talen 5200-25) 4.0% by mass
Ethylene propylene rubber (EP22) 4.0% by mass
Aluminum pigment (Friend color F701SI) 10.0% by mass
(Pigment average particle diameter: 11 μm)

The ink viscosities of Examples and Comparative Examples were measured using a Brookfield DV-II viscometer (CPE-42 rotor) under an environment of 20 ° C. In addition, when the ink viscosity is 12.8 mPa · s or more and less than 128 mPa · s, the shear rate is 192.0 sec ⁻¹ (rotation speed 50 rpm), and when the ink viscosity is 128 mPa · s or more and less than 1280 mPa · s, the shear rate 19 Measured at 2 sec ⁻¹ (5 rpm). Moreover, since the erasable ink composition for writing instruments of the present invention is a Newtonian ink, the ink viscosity showed substantially the same numerical value even when the shear rate was different. The ink used for measuring the ink viscosity was measured after the ink was placed in a tightly closed glass test tube and left at room temperature for 6 months.

Examples 2-11
As shown in Table 1, erasable ink compositions for writing instruments of Examples 2 to 11 were obtained in the same procedure as in Example 1 except that each component was changed to the formulation shown in Table 1. Table 1 shows the measurement and evaluation results.

Comparative Examples 1-7
The composition of the ink is as shown in Table 2, and Table 2 shows the measurement and evaluation results.

Test and Evaluation In the dissolution test and the pigment redispersion test, the erasable ink compositions for writing instruments prepared in Examples 1 to 11 and Comparative Examples 1 to 7 were used for evaluation by the following test methods.
Moreover, in the erasability test, the writing test, and the concealment test, the erasable ink composition for writing instruments prepared in Examples 1 to 11 and Comparative Examples 1 to 7 can rotate a ball having a ball diameter of 1.0 mm. Using a pen that has been held, a writing instrument filled directly in an ink container (made of nylon) with a ceramic 5.0 mm diameter stirring ball, and copy paper (PPC paper) as writing test paper The test method was evaluated as follows.

Dissolution test: A rubber-based solvent was mixed in a hydrocarbon solvent and stirred, and then the dissolution state was observed.
Dissolved ・ ・ ・ ・ ○
Not dissolved ・ ・ ・ ・ ×

Pigment redispersion test: Each sample was placed in a 15 mm diameter closed open / close glass test tube containing a ceramic 5.0 mm diameter stirring ball and allowed to stand at room temperature for 6 months. Thereafter, the glass test tube of each sample once settled was shaken up and down to observe the pigment redispersion state.
Pigment redispersed by shaking within 10 times
The pigment is not redispersed even after shaking 20 times or more. Or
A hard cake that cannot be redispersed with pigments ××

Test method: Write letters and pictures on paper in advance, shake the writing instrument 10 times up and down, write on the letters with erasable ink, and dry until a writing film is formed. The test was conducted.
Erasability test: The ink erasability was observed after writing with an erasable ink, drying until a writing film was formed, and then rubbing with an eraser.
All erased ... ◎
There is a little unerased, but there is no problem in practical use.
There is unerased residue and writing film remains ... ×

Written test: The handwriting written on paper was observed.
No blurring in the handwriting ... ◎
Scratches appear in the handwriting, but there are no practical problems
Scratches appear in the handwriting, poor practicality ・ ・ ・ ×

Concealment test: Characters and pictures were written with erasable ink to observe whether they were concealed.
Characters / pictures not visible and concealed ... A
Letters / pictures that are visible even if written

  In Examples 1 to 9, the solubility test, the pigment redispersion test, the erasability test, and the writing test were good results.

  In Example 10, the amount of the rubber-based resin was increased to 8.0% by mass, so that the ink fluidity was slightly inferior, the ink output was slightly less, and the handwriting was blurred, but there was no practical problem. It was a level of damage.

  In Example 11, the amount of the fatty acid amide wax was as large as 15% by mass, so that a slight blur was generated in the handwriting, and in the erasability test, there was a little unerased, but at a level where there was no practical problem. It was.

  In Comparative Example 1, since the hard cake inhibitor was not used, after the pigment settled, the pigments were entangled with each other due to their weight, and the pigments adsorbed to form a hard cake. Thus, the desired ink was not obtained. .

  In Comparative Examples 2 and 3, since a solvent other than the hydrocarbon solvent was used, the rubber resin did not dissolve and the desired ink was not obtained.

  In Comparative Examples 4 and 5, since a hard cake inhibitor other than the fatty acid amide wax was used, after the pigment settled, the pigments were entangled with each other due to the weight of the pigments to form a hard cake. Therefore, the desired ink was not obtained.

  In Comparative Examples 6 and 7, since a resin other than the rubber-based resin was used, the handwriting film had a strong adhesive force and could not be erased with an eraser.

  Further, when the erasable ink composition for writing instruments of the present invention is used as a writing instrument, the ink containing cylinder filled with the erasable ink composition for writing instruments is not particularly limited in material such as metal or resin. However, since a hydrocarbon solvent is used in the present invention, it is preferably formed of a resin, such as metal, nylon, polypropylene, or ethylene vinyl alcohol copolymer, that has a small air permeation amount. Moreover, you may make it the structure of the pressurization type writing instrument which pressurizes forcibly by pressing the pressurization type writing instrument, such as compressed air or gas, or an ink storage cylinder. Furthermore, by using a writing instrument equipped with a scratching functional member such as an eraser on the ink storage cylinder of the writing instrument or the shaft cylinder of the writing instrument, immediately after writing, the scratching functional member provided on the writing instrument erases it as necessary. It is very convenient because it can.

  The present invention relates to an ink composition comprising at least a hydrocarbon solvent, a pigment, a rubber resin, and a hard cake inhibitor, wherein the hard cake inhibitor is a fatty acid amide wax. Can be used to provide an erasable ink composition for a writing instrument that has good handwriting, excellent erasability with an eraser and the like, and has suppressed the formation of a hard cake of a pigment even when it has settled. Therefore, it can be widely used as ink for writing instruments such as cap type and knock type.

Moreover, the writing instrument filled with the erasable ink composition for a writing instrument of the present invention can be used not only on a permeation surface such as paper as a recording medium but also on a non-permeation surface such as glass, metal, and plastic.

Claims (5)

In a writing instrument comprising a ballpoint pen tip holding a ball rotatably at the tip of an ink containing cylinder, directly or via a chip holder , a ceramic stirring ball is incorporated in the ink containing cylinder, and at least An erasable ink composition for a writing instrument comprising a hydrocarbon solvent, a pigment, a rubber resin, and a hard cake inhibitor, wherein the hard cake inhibitor is a fatty acid amide wax, and the content is based on the total mass of the ink composition. And the rubber-based resin comprises one or more selected from ethylene propylene rubber, isopropylene rubber, and butadiene rubber, and The ink viscosity at 35 ° C. is not less than 35 mPa · s and not more than 700 mPa · s. A writing instrument characterized by the fact that The writing instrument according to claim 1, wherein the content of the rubber-based resin is 0.1% by mass or more and 10.0% by mass or less with respect to the total mass of the ink composition. The writing instrument according to claim 1 or 2, wherein the boiling point of the hydrocarbon solvent is less than 150 ° C. The writing instrument according to any one of claims 1 to 3, wherein an average particle diameter of the pigment is 5 µm or more and 100 µm or less. The writing instrument according to any one of claims 1 to 4, wherein the fatty acid amide wax is in a paste form.