JP4563105B2 - Eraser - Google Patents

Description

  The present invention relates to an eraser that cannot be erased by a commercially available eraser, but that can erase a writing line only by using a specific eraser.

  Conventionally, many eraser erasable ink compositions capable of erasing writing lines with commercially available erasers are known, but in recent years, many eraser erasable ink compositions using water as a main solvent have been known. It is disclosed.

  For example, an aqueous erasable ink composition comprising a styrene-butadiene copolymer and a water-insoluble pigment, suitable for use in highlighters and other writing instruments, and having a viscosity of 10 to 30 cps and the use thereof Marker (for example, refer to Patent Document 1), erasable ink composition containing a resin, pigment and water having a film forming temperature of 0 ° C. or lower or a glass transition temperature of 0 ° C. or lower, and a film forming of 0 ° C. or lower An erasable ink containing a resin having a temperature or a glass transition temperature of 0 ° C. or less, colored spherical fine particles having a particle diameter of 1 to 20 μm, and water, and having an ink viscosity of 5 to 35 mPa · s (for example, patent documents by the present applicant) 2 and 3), and a film-forming resin particle having a glass transition temperature of 0 ° C. or less, a colored resin particle colored with a dye, a film-forming inhibitor, and water. Writing eraser erasable aqueous ink composition including (for example, see Patent Document 4) and the like are known.

However, the erasable ink composition disclosed in each of these publications, and the conventional erasable ink compositions known so far, can be erased with a commercially available eraser and an eraser with a hardness of less than 70 °. As a premise, there is not enough adhesion between the paper surface and the writing line, it can be easily peeled off by rubbing with a finger etc., and there is a problem that an excellent balance of eraser erasability and abrasion resistance has not been obtained There is.
Therefore, the present inventors contain an ink composition for a writing instrument that has solved the above problems, specifically, at least a pigment, a thickener, a film-forming acrylonitrile butadiene resin emulsion, and water. An erasable ink composition having an ink surface tension of 30 to 45 dyne / cm has been developed.
The writing line by this ink composition has characteristics that cannot be erased by a conventional eraser.

On the other hand, as a conventional eraser, for example, an eraser comprising at least an ethylene-vinyl acetate copolymer, a polyolefin-based elastomer, a filler, and a plasticizer (see, for example, Patent Document 5), vinyl chloride as a base component Eraser composition containing 4.5-epoxyhexahydrophthalate di-2-ethylhexyl as a plasticizer (for example, see Patent Document 6), styrene-based thermoplastic elastomer, filler, and acetylation An eraser containing at least glycerin (for example, see Patent Document 7) and an eraser made of a non-chlorine compound containing 0.1 to 10% by weight of uncrosslinked ethylene propylene rubber with respect to the base material (for example, see Patent Document 8) )It has been known.

The eraser described in each of these publications has a function equivalent to that of a conventional commercially available eraser and can erase pencil strokes, but contains a plasticizer and a filler. The writing line by the ink composition for writing instruments developed by the inventors has a problem that the eraser itself wears itself and the writing line cannot be erased satisfactorily. Furthermore, it must be able to erase the writing lines without damaging the paper surface.
Japanese Patent Laid-Open No. 7-505174 (Claims, Examples, etc.) JP-A-4-56089 (Claims, Examples, etc.) JP-A-5-279614 (Claims, Examples, etc.) JP 2003-55593 A (claims, examples, etc.) JP-A-11-334289 (Claims, Examples, etc.) JP 2001-81259 A (Claims, Examples, etc.) JP 2002-254894 A (Claims, Examples, etc.) JP 2002-200890 A (Claims, Examples, etc.)

  The present invention is to solve this problem in view of the above-mentioned problems of the prior art, the current situation, required characteristics, etc., and cannot be erased by rubbing with a finger or the like, with a conventional commercially available eraser, and with a pencil. An object of the present invention is to provide an erasing tool that has characteristics that cannot be erased with respect to a drawn line, and that provides good erasability of a drawn line without damaging the paper surface.

  In order to solve the above-mentioned conventional problems, etc., the present inventors have intensively studied the composition and physical properties of conventional erasers, and as a result, do not contain abrasives, plasticizers, fillers, and have specified hardness. As a result, it was found that the above-mentioned eraser was obtained, and the present invention was completed.

That is, the present invention resides in the following (1) to (7).
(1) An eraser for erasing writing lines with an ink composition for a writing instrument, the eraser not containing an abrasive, a plasticizer, and a filler, and having a hardness of 70 ° to 100 °. An eraser characterized by
(2) The eraser according to the above (1), wherein the eraseability (erase rate) of the pencil stroke specified in JIS S 6050-2002 is 70% or less.
(3) The eraser according to the above (1) or (2), which has little self-wear when erasing the writing lines.
(4) The eraser according to any one of (1) to (3), which does not contain a plasticizer.
(5) The eraser according to any one of (1) to (4), comprising a mixture of a thermoplastic resin and a thermoplastic elastomer.
(6) The eraser according to any one of the above (1) to (5), which comprises a mixture of an olefinic resin and an olefinic thermoplastic elastomer and whose blending ratio is 1: 1 to 1: 4 by weight. Ingredients.
(7) A writing instrument containing an ink composition for a writing instrument, wherein the writing instrument comprises the eraser according to any one of (1) to (6) above. Writing instrument to do.
The “hardness” of the eraser defined in the present invention is a value measured by a rubber hardness meter GS-701 (manufactured by Teclock Corporation).

ADVANTAGE OF THE INVENTION According to this invention, the eraser for writing lines which cannot be erased with the finger | toe etc. and the conventional commercially available eraser, and does not damage a paper surface is provided.
According to the second aspect of the present invention, there is a characteristic that cannot be erased by scratching with a finger or the like, a conventional commercially available eraser, and cannot be erased with respect to a pencil drawing line, and does not damage the paper surface. An eraser is provided.
According to the third aspect of the present invention, there is a characteristic that cannot be erased by scratching with a finger or the like, a conventional commercially available eraser, and cannot be erased with respect to a pencil drawing, and the writing drawing line does not damage the paper surface. There is provided a writing instrument provided with an eraser.

Hereinafter, embodiments of the present invention will be described in detail.
The eraser of the present invention is an eraser for erasing a writing line by an ink composition for a writing instrument, and the eraser does not contain an abrasive, a plasticizer, and a filler, and has a hardness of 70 ° to 100 °. It is characterized by comprising the following material.

The eraser of the present invention is not particularly limited as long as the eraser does not contain an abrasive, a plasticizer, and a filler, and is made of a material having a hardness of 70 ° to 100 °. For example, various thermoplastic resins, It can be constituted by using at least one kind (each alone or a mixture of two or more kinds) such as a thermosetting resin, a thermoplastic elastomer, a vulcanized rubber, a synthetic rubber, and a sintered body of an inorganic substance / an organic substance.
In the present invention, the reason for not containing an abrasive (abrasive particles) is that no abrasive (abrasive particles) is contained in order to erase the writing lines without damaging the paper surface.

Examples of the thermoplastic resin that can be used include olefin-based, styrene-based, acrylic-based, ester-based, vinyl chloride-based, and thermosetting resins include, for example, epoxy-based and urethane-based resins. Melamine-based, urea-based, phenol-based and the like can be used.
Examples of the thermoplastic elastomer that can be used include various elastomers such as olefin, styrene, urethane, polyester, and fluorine. As for the rubber, vulcanized rubber including natural rubber and various synthetic rubbers can be used.

In the present invention, a preferable eraser is preferably a plasticizer such as dibutyl phthalate (dibutyl phthalate) or dioctyl phthalate (dioctyl phthalate) from the viewpoint of safety to the human body and problems caused by adhesion when contacting other plastics. It is desirable not to contain.
In addition, from the viewpoint of wear resistance and erasability of writing lines with a specific ink, an eraser composed of a mixture of the above thermoplastic resin and a thermoplastic elastomer (weight ratio of 1: 1 to 1: 4) is preferable, More preferably, it is made of a mixture of an olefin resin and an olefin thermoplastic elastomer, and the blending ratio is 1: 2.5 to 1: 3.5 by weight.
Mixtures of these thermoplastic resins and thermoplastic elastomers are preferred because they eliminate less self-wear when erasing handwritten lines.

In the present invention, the hardness of the eraser composed of the above material needs to be 70 ° to 100 °, preferably 75 to 95 °, and more preferably 80 to 93 °. .
If the hardness is less than 70 °, it is too soft to erase the drawn line with the specific ink. On the other hand, if the hardness exceeds 100 °, the eraser itself is not flexible, and the friction exceeds the adhesive force between the drawn line and the paper surface. Since no force is generated, it cannot be erased.

In the eraser of the present invention, it is not erasable with a finger or the like, and cannot be erased by a conventional commercially available eraser. From the point of providing an eraser, it is preferable that the pencil drawing line erasing ability (erasure rate) specified in JIS S 6050-2002 is 70% or less. The pencil used in this test is a pencil (HB) specified in JIS S 6006.
In order to make the eraser having this characteristic, it can be adjusted by the kind and blending ratio of the thermoplastic resin.

In the eraser of the present invention, a colorant, a fragrance and the like may be mixed in the above material within a range not impairing the effects of the present invention.
The eraser of the present invention can be prepared by mixing the above-mentioned various thermoplastic resins, thermosetting resins, thermoplastic elastomers, rubbers and the like by a conventional method.
Specifically, the compound can be heated and melted and sufficiently kneaded with a kneader, once cooled, pulverized, and obtained through a mold by an extrusion molding machine or injection molding machine adjusted to a predetermined temperature. it can.

The shape of the eraser of the present invention is not particularly limited, and may be, for example, a cylindrical shape, a prismatic shape, a triangular prism shape, a rectangular parallelepiped, or a complicated shape having irregularities and protrusions on the surface.
FIG. 1 is an embodiment of the eraser A of the present invention having a general shape. The eraser A includes an eraser body 10 composed of 25 parts by weight of polypropylene (J-728, manufactured by Mitsui Chemicals) and 75 parts by weight of a styrenic thermoplastic elastomer (actimer, LQA9770N, manufactured by Riken Technos), It consists of a paper case 11.
Moreover, the eraser of this invention can also be provided in the rear-end part of the writing instrument which accommodates the ink composition for writing instruments.
FIG. 2 is a writing instrument provided with the eraser of the present invention at the rear end of the writing instrument body.
This writing instrument B is one in which the erasable ink composition 20 is filled in an ink tank portion 21 which is a shaft body that directly stores the erasable ink composition 20 without occluding the filling.
The sign pen B is configured such that the ink 20 is supplied to a pen tip 23 made of a fiber core through a valve mechanism 22 in the ink tank portion 21. In FIG. 2, 24 is a holder member, 25 is a rear member fixed to the rear portion of the ink tank section 21, and 26 is an inner cap that is movable by a spring 27. It is possible to prevent the valve 22 from being opened due to pressure. Reference numeral 29 does not contain the abrasive of the present invention fitted in the concave shape of one end portion of the cap 48, and has a hardness of 70 to 100 ° [in this embodiment, a hardness of 90 °, a thermoplastic resin and a thermoplastic resin. It is comprised from the eraser of the mixture of elastomers (a compounding ratio is 1: 1-1: 4 by weight ratio).

The eraser of the present invention configured as described above is an eraser for erasing the writing lines by the ink composition for writing instruments, and the eraser does not contain an abrasive, a plasticizer, a filler, and has a hardness. The eraser is made of a material having an angle of 70 ° to 100 °, and the eraser has a shape holding power larger than the adhesive strength of the writing line to the paper surface, and moreover, the writing line coating film from the adhesive force of the writing line to the paper surface. Therefore, it is not possible to erase with a finger or the like and a conventional commercially available eraser, and a writing line eraser that does not damage the paper surface can be obtained.
Furthermore, if the eraser (erasing rate) of the pencil stroke specified in JIS S 6050-2002 is 70% or less, it cannot be erased by scratching with a finger or the like, and a conventional commercially available eraser, In addition, it is possible to obtain an eraser for writing lines that has characteristics that cannot be erased with respect to a drawn line with a pencil and that does not damage the paper surface.
In addition, the writing instrument of the present invention is not erasable with a finger or the like, can not be erased by a conventional commercially available eraser, and has the characteristics that it cannot be erased with respect to a pencil drawing, and for writing drawing lines that do not damage the paper surface. A writing instrument provided with an eraser is obtained.

  EXAMPLES Next, although an Example and a comparative example demonstrate this invention further in detail, it is not limited to the following Example etc.

[Examples 1-3 and Comparative Examples 1-3]
Example 1
25 parts by weight of a polypropylene resin (J-728, manufactured by Mitsui Chemicals) and 75 parts by weight of a thermoplastic elastomer (Actimar, LQA9770N, manufactured by Riken Technos) were heated and melted and sufficiently kneaded with a kneader, and then cooled and pulverized. What was melt-extruded by an extrusion molding machine and cooled was cut to obtain an eraser (size: 12 × 5 × 20 mm).

(Example 2)
20 parts by weight of a polypropylene resin (J-728, manufactured by Mitsui Chemicals) and 80 parts by weight of a thermoplastic elastomer (Trefsin 3271-65W308, manufactured by AES Japan) were heated and melted and sufficiently kneaded with a kneader, and then cooled and pulverized. The resulting product was melt-extruded by an extrusion molding machine and the cooled one was cut to obtain an eraser (size: 12 × 5 × 20 mm).

(Example 3)
50 parts by weight of a polypropylene resin (J-728, manufactured by Mitsui Chemicals) and 50 parts by weight of a thermoplastic elastomer (Rheostoma, CFR 9965N, manufactured by Riken Technos) are kneaded with a kneader and then cooled and pulverized. Was melt-extruded by an extrusion molding machine, and the cooled one was cut to obtain an eraser (size: 12 × 5 × 20 mm).

(Comparative Example 1)
20 parts by weight of a polypropylene resin (J-728, manufactured by Mitsui Chemicals) and 80 parts by weight of an ethylene-vinyl acetate copolymer thermoplastic elastomer (Evaate VM618A, manufactured by Sumitomo Chemical) were heated and melted and kneaded sufficiently with a kneader. Thereafter, the cooled and pulverized product was melt-extruded by an extrusion molding machine, and the cooled product was cut to obtain an eraser (size: 12 × 5 × 20 mm).

(Comparative Example 2)
An eraser (size: 12 × 5 × 20 mm) made of polypropylene resin (J-728, manufactured by Mitsui Chemicals) was used.

(Comparative Example 3)
Commercially available Mitsubishi Pencil Co., Ltd., trade name “EP-105” (composition composition; made of vinyl chloride, containing plasticizer / filler) was used.
In addition, the magnitude | size of the eraser of Examples 1-3 and Comparative Examples 1-3 is 12x5x20 mm.

About the obtained eraser, the following evaluation methods evaluated the hardness of the eraser, the erasing ability (character erasure rate) of pencil strokes defined in JIS S 6050-2002, the erasability test 1, and the like.
These results are shown in Table 1 below.

(Evaluation method for hardness of eraser)
It was measured with a rubber viscometer GS-701 (manufactured by Teclock Corporation).

[Evaluation method of erasing ability (erase rate) of pencil drawing]
The erasing ability (erasing rate) of pencil strokes defined in JIS S 6050-2002 was calculated and evaluated according to the following evaluation criteria.
Evaluation criteria:
◎: Erase rate 70% or less ○: Erase rate more than 70% to less than 75% △: Erase rate 75% or more to less than 80% ×: Erasure rate 80% or more

(Eraseability test 1)
An ink composition for a writing instrument having the following composition was prepared. This writing instrument ink composition was filled in a writing instrument conforming to FIG. 2 and written on a paper surface (basis weight 50 to 100 g / m ² , paper with a whiteness of 75% or more, the same applies hereinafter). An erase test was carried out by the following method using the eraser of Examples and Comparative Examples for this writing line, and the evaluation was performed according to the following evaluation criteria.
The load was 5N, the erosion speed was 15 cm / sec, and the number of reciprocations was 4 by the hand of the tester, and the erasure rate was tested according to JIS S 6050-2002 to calculate the erasure rate.

(Adjustment of ink composition for writing instruments)
The following blending components were produced by the following method to obtain an erasable ink composition.
Pigment: 8% by weight of aqueous dispersion of pink resin particles
[SW-17 (manufactured by Sinloihi), average particle size 1 μm, solid content 42%]
Resin emulsion: 60% by weight of aqueous dispersion of acrylonitrile-butadiene copolymer
[Nipol LX517A (manufactured by Nippon Zeon), solid content 40%, surface tension 42 dyne / cm]
Thickener: Crystalline cellulose [Asahi Kasei Co., Ltd.] 0.5% by weight
[RC-591, homomixer, 10,000 rpm, 10 minutes]
18% by weight of urea
Water (purified water) 13.5% by weight
Among the above-described blending components, the ink was sequentially added to the tank while stirring, mixed and stirred until uniform, and then filtered through a 1 μm bag filter to produce an ink.

Evaluation criteria:
◎: erasure rate 90% or more ○: erasure rate 80% to less than 90% △: erasure rate 70% to less than 80% ×: erasure rate less than 70%

  As is apparent from the results in Table 1 above, the eraser obtained in Examples 1 to 3 within the scope of the present invention erases a specific writing line that cannot be erased with a conventional eraser without damaging the paper surface. I found that I can do it.

It is a perspective view which shows an example of embodiment of the eraser of this invention. It is a longitudinal cross-sectional view of the writing instrument provided with the eraser of this invention.

Explanation of symbols

A eraser 10 eraser body 11 case

Claims (3)

An eraser for erasing a writing line by an ink composition for a writing instrument, the eraser comprising a mixture of a polypropylene resin and a styrene thermoplastic elastomer, or a mixture of a polypropylene resin and a polypropylene thermoplastic elastomer, An eraser characterized in that the blending ratio is 1: 1 to 1: 4 in weight ratio, does not contain abrasives, plasticizers and fillers, and is made of a material having a hardness of 70 ° to 100 °.   The eraser according to claim 1, wherein the erasing ability (erasure rate) of the pencil stroke defined in JIS S 6050-2002 is 70% or less. A writing instrument containing an ink composition for a writing instrument, wherein the writing instrument comprises the eraser according to claim 1 or 2 .

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