TW201927883A - Eraser - Google Patents

Abstract

This eraser (10) comprises: a base material (110) which contains a plasticizer and at least one of a resin component and an elastomer component; and a porous foam (120) which is impregnated with the base material (110). This eraser (10) has a tensile modulus of elasticity of from 0.6 MPa to 1.2 MPa (inclusive).

Description

Eraser

The present invention relates to an eraser.

Erasers are commonly called erasers and are widely used. A general eraser is produced by blending a plasticizer, a filler, a coloring agent, etc. as needed in a base resin such as a vinyl chloride resin, and uniformly mixing them, and then heating and molding. An example of such an eraser is disclosed in Patent Document 1.

In addition, Patent Literature 2 discloses an eraser including an elastomer and a skeleton structure of an eraser composition, and the eraser composition contains at least one of a rubber component and a resin component.

[Prior Art Document] [Patent Document] Patent Document 1: Japanese Patent Laid-Open No. 55-34990. Patent Document 2: Japanese Patent Laid-Open No. 2001-138688.

[Technical solution] (Problems to be solved by the invention)

As for the eraser, there is a need to selectively erase only characters in a desired narrow area without removing surrounding characters. Furthermore, there is a need to accurately and beautifully erase characters in such narrow areas with a slight force. In order to meet this demand, the eraser is required to have both shape retention and erasing properties. The shape retention is that even if the user applies force to the eraser in order to eliminate text, the eraser itself is not easy to bend, and the eraser is maintained. The shape of the word is the ability to eliminate characters.

Therefore, an object of the present invention is to provide an eraser having both high shape retention and high erasability. (Means to solve problems)

The eraser of the present invention includes a base material containing at least one of a resin component and an elastomer component, and a plasticizer; and a porous foam body impregnated with the base material. The eraser has a tensile elastic modulus of 0.6 MPa to 1.2 MPa.

In order to exactly erase characters at a desired position with an eraser, it is important that the eraser maintains its shape during erasing. When erasing text written with a pencil on a paper surface with an eraser, the user of the eraser can eliminate the pressure on the surface of the paper by pressing the eraser against the surface of the paper while pressing the surface of the paper with the eraser. Text. At this time, if the eraser does not have sufficient shape retention, the eraser will be bent due to the force applied by the user to the eraser. If the eraser is bent, the direction of the force applied by the eraser is dispersed and the force cannot be fully transmitted, the friction force on the paper surface is reduced, and the characters are not easy to disappear. In addition, since the force applied to the eraser is dispersed due to bending, an additional force must be applied in order to obtain a sufficient frictional force for erasing characters.

In addition, since the paper surface is hidden due to the bending of the eraser, there is also a problem that the erasure part is difficult to see from the user, and the predetermined position is difficult to eliminate. In addition, if the shape retention of the eraser is low, the followability of the movement of the eraser to the ground portion of the paper surface with respect to the movement of the user's hand becomes poor. As a result, there is a case where the frictional force in the portion intended by the user is insufficient to sufficiently erase the characters, or the characters are erased to a portion not intended by the user. As described above, if the shape retention of the eraser is low, there is a tendency that the eraser tends to be deteriorated due to reasons such as difficulty in transmitting force during erasure and difficulty in seeing the erasure site.

On the other hand, the eraser is required to have a high erasing property as an essential property of the eraser. The mechanism by which the word disappears by the eraser is as follows. If you use a pencil to write text on the paper surface, graphite will adhere to the surface of the paper surface. If the character is erased with an eraser, the structure of the eraser on the surface of the paper surface wears while adsorbing graphite attached to the surface of the paper surface. A part of the tissue to which the graphite eraser is adsorbed is detached from the surface of the eraser as an eraser. The eraser surface is detached from the eraser surface, and the tissue surface of the new eraser is exposed. By repeating this cycle, the text disappears. Therefore, for the eraser, the abrasion-disintegrability of the part which is rubbed by rubbing while disintegrating is required. With high abrasion and disintegration properties, high erasability can be achieved.

However, it is not easy to have both high shape retention and high erasability. For example, as one solution for improving the shape retention, it is considered to make the eraser hard. However, if the hardness of the eraser is simply increased, the abrasion and disintegration properties tend to decrease, and as a result, the erasure property tends to decrease. Therefore, an eraser having both high shape retention and high erasability is required.

The present inventors conducted research, and found that by satisfying (1) an eraser made of a combination of a base material and a porous foam, and (2) an eraser having a tensile elastic modulus of 0.6 MPa or more and These two conditions below 1.2MPa can provide an eraser that has both high shape retention and high erasability. According to research by the present inventors, if the eraser has a tensile elastic modulus of 0.6 MPa or more, it can maintain sufficient shape retention under normal use conditions, and it is difficult to cause the eraser to bend. On the other hand, if the tensile elastic modulus is simply set to be 0.6 MPa or more and 1.2 MPa or less, the property of the rubber originally used for erasing characters is impaired. Therefore, by selecting the manufacturing conditions of the base material, the porous foam, and the eraser of the raw materials so that the tensile elastic modulus becomes 0.6 MPa or more and 1.2 MPa or less, it can provide both high shape retention and High erasing eraser.

The eraser of the present invention is more preferably a tensile elastic modulus of 0.7 MPa or more. If the tensile elastic modulus of the eraser is 0.7 MPa or more, it will be an eraser with higher shape retention and less resistance to bending during erasure.

In the eraser, the porous foam is preferably a melamine foam. Melamine foam is easily disintegrated by friction, has moderate tensile strength, and has a high affinity with the base material. It is particularly suitable as a material for obtaining an eraser having both high shape retention and high erasability.

In the eraser, the resin component is preferably polyvinyl chloride. Polyvinyl chloride is particularly suitable as a material for obtaining an eraser having both high shape retention and high erasability.

In the eraser, the tensile elastic modulus of the porous foam is preferably 0.03 MPa or more and 0.8 MPa or less, and more preferably 0.05 MPa or more and 0.4 MPa or less. When the tensile elastic modulus of the porous foam is within the above range, the flexibility and shape retention of the eraser can be appropriately maintained.

Eraser above, the density of the porous foam is preferably 3.5kg / m ³ or more and 12.0kg / m ³ or less. When the density of the porous foam is within the above range, it is easy to become a preferred form during production and use. (Effect of invention)

According to the eraser, an eraser having both high shape retention and high erasing properties can be provided.

Next, an embodiment of the eraser of the present invention will be described with reference to Figs. 1 and 2. FIG. 1 shows an eraser 10 according to an embodiment of the present invention. Fig. 2 is an enlarged sectional view of the eraser. A part of the eraser 10 is exposed for erasing, and a part other than the part is covered by an outer cover 20 for preventing contamination. As shown in FIG. 2, the eraser 10 has a structure in which the base material 110 is filled in the voids of the porous foam 120. The details are described below.

[Base material] The eraser 10 includes a base material 110 containing at least one of a resin component and an elastomer component, and a plasticizer.

Examples of the resin constituting the resin component include thermoplastic resins, thermosetting resins, ultraviolet curable resins, electron beam curable resins, multi-liquid curable resins (two-liquid curable resins, etc.), catalyst-curable resins, Various resins, such as a cellulose ester, are not specifically limited. Among these, a thermoplastic resin is preferred. This resin can also be used in the form of being dissolved in a solvent, in the form of being dispersed in a solvent, or in the form of an emulsion.

More specific examples of the resin include vinyl chloride, vinyl chloride-vinyl acetate resin, vinyl chloride-based resin such as vinyl chloride-ethylene-vinyl acetate resin, and acetic acid such as ethylene-vinyl acetate resin. Vinyl ester resin and the like. Among these, in terms of easy mixing with a plasticizer and suitable for obtaining an eraser having both high shape retention and high erasability, vinyl chloride-based resins, particularly polyvinyl chloride, are preferred.

Examples of the elastomer component include polyisoprene (natural rubber), styrene-based, butadiene-based, isoprene-based, ethylene-propylene-based, nitrile-based, chloroprene-based, Urethane-based, acrylic-based, polyester-based, and olefin-based elastomers.

These resin components and elastomer components may be used alone, or two or more of them may be used in combination as necessary.

The plasticizer can be appropriately selected according to the thermoplastic resin used. For example, when the base material 110 contains polyvinyl chloride, as the plasticizer, orthobenzene such as dioctyl phthalate, dipentyl phthalate, and dibutyl phthalate can be preferably used. Dimethyl ester-based plasticizers, ethidium citrate-based plasticizers such as tributyl citrate, adipate such as di (2-ethylhexyl) adipate, and adipic acid polyester Ester-based plasticizers, alkyl sulfonate-based plasticizers such as phenyl alkylsulfonate, epoxy-based plasticizers, trimellitic acid-based plasticizers, and benzoic acid-based esters. These plasticizers may be used alone, or two or more of them may be used in combination as necessary.

The base material 110 is preferably impregnated into the porous foam 120 in a state of containing a sol-like composition of the vinyl chloride-based resin, particularly polyvinyl chloride, and a plasticizer. The reason is that it has fluidity in impregnating and absorbing a sol-like composition composed of a vinyl chloride-based resin and a plasticizer into the porous foam 120, and it is easy to harden in the void portion of the porous foam 120.

In the eraser 10 described above, the total ratio of the resin component and the elastomer component in the base material 110 is not particularly limited. For example, 100% by mass of the base material 110 contains at least one of a resin component and an elastomer component in an amount of 10% by mass or more and 80% by mass or less, preferably 20% by mass or more and 70% by mass or less.

In the above-mentioned eraser 10, the ratio of the plasticizer is, for example, 10% by mass or more and 80% by mass or less, preferably 20% by mass or more and 70% by mass or less in the base material 110 of 100% by mass (wherein the The total of the elastomer component and the plasticizer is 100% by mass or less).

The base material 110 may further contain fillers such as calcium carbonate, magnesium carbonate, magnesium oxide, silicon dioxide, talc, clay, diatomaceous earth, quartz powder, aluminum oxide, aluminum silicate, and mica. The ratio of the filler is, for example, from 0% by mass to 70% by mass of 110% by mass of the base material, and preferably from 5% by mass to 40% by mass.

The base material 110 may further contain other additives such as abrasives, stabilizers, colorants, perfumes, surfactants, and glycols. As the stabilizer, a metal soap, a barium-zinc-based stabilizer, a calcium-zinc-based stabilizer, a magnesium-zinc-based stabilizer, a phosphite-based stabilizer, and the like can be used. As the colorant, a known pigment such as an organic pigment, an inorganic pigment, a fluorescent pigment, or a known dye can be used.

In addition, the base material 110 may include a discoloration pigment component (pressure-sensitive discoloration pigment component) composed of pressure-sensitive microcapsules that are crushed by rubbing force, or a thermosensitive coloring that includes discoloration by rubbing heat. Discoloration pigment component (thermochromic pigment component) of the component.

[Porous Foam] The eraser 10 of this embodiment includes a porous foam 120 impregnated with a base material 110. The porous foam 120 is preferably a porous foam having the following skeleton structure. The skeleton structure can be impregnated with the base material 110 described above, and the skeleton of the porous foam 120 can be obtained by friction against a paper surface. As the base material 110 wears out, it breaks away.

Examples of the porous foam 120 include thermosetting resins such as melamine resin, epoxy resin, urethane resin, urea resin, phenol resin, styrene resin such as polystyrene, and polyester. Porous foams composed of various resins such as ester resins, acrylic resins such as polyacrylates, olefin resins such as polyethylene, thermoplastic resins such as vinyl chloride resins, and polyvinyl chloride, or elastomers. Alternatively, a natural polymer porous body such as a sponge may be used. Furthermore, it may contain various rubber components such as natural rubber, styrene-butadiene rubber, nitrile-butadiene rubber, or natural fibers such as cotton, silk, and hemp, cellulose fibers, ester fibers, acrylic fibers, Various fibers, such as synthetic fibers such as amidine fibers.

Among these, the porous foam is preferred from the viewpoints of high affinity with the base material 110, a structure that is easily broken due to friction on the paper surface, and a moderate tensile elastic modulus is imparted. 120 is a melamine foam formed from a melamine resin.

The porous foam 120 is controlled by selecting a suitable material, controlling the thickness of the skeleton portion, the pore diameter of the void portion, the porosity, etc., so that the tensile elastic modulus of the eraser 10 becomes 0.6 MPa or more and 1.2 MPa or less. form. If it is such a porous foam 120, it can provide the eraser 10 which has both high shape retention and high erasability, and has moderate flexibility. By having moderate flexibility, an eraser 10 can be provided in which the force is easily applied when the characters are eliminated and the characters are easily disappeared.

[Manufacturing Method of Eraser 10] The eraser 10 of the present invention is manufactured in such a manner that the base material 110 penetrates into the void portion of the porous foam 120, and the base material 110 is contained in the void portion. The manufacturing method is not particularly limited, and examples thereof include the following methods.

First, components of the base material 110 such as at least one of the resin component and the elastomer component, a plasticizer, and a filler or other additives added as necessary are sufficiently stirred and mixed to prepare the base material 110. Here, when using a vinyl chloride resin as a resin component, for example, a granular resin is used. Separately from this, a sheet-like porous foam 120 is prepared.

Next, the base material 110 is impregnated into the porous foam 120 to thereby fill the voids of the porous foam 120 with the base material 110. For example, in a state where the porous foam 120 is left to stand, an amount of the uncured base material 110 that sufficiently fills the void portion of the porous foam 120 may be introduced, and the base material 110 may be absorbed in the void portion. . In addition, the porous foam 120 may be impregnated in the mold frame on the flat plate filled with the uncured base material 110 to impregnate the porous foam 120 as a whole. When the non-hardened base material 110 is impregnated into the porous foam 120, the porous foam 120 may be impregnated with the non-hardened base material 110 so as to cover the entire void portion of the porous foam 120. The porous foam 120 is compressed by pressing in a state where the uncured base material 110 is present. In addition, in order to prevent pores in the eraser 10, degassing may be performed under reduced pressure. In addition, in order to make the internal content of the base material 110 uniform and increase, the porous body 120 impregnated with the uncured base material 110 may be further impregnated by injecting the uncured base material 110.

The ratio of the porous foam 120 to the base material 110 is not particularly limited. The porosity of the porous foam 120 (the total amount of voids) is taken into consideration so that the base material is sufficiently filled in the voids of the porous foam 120 The ratio of the volume to the apparent volume of the porous foam 120) or the characteristics required for the eraser 10 are appropriately selected. As an example, it is 50 mass parts or more and 200 mass parts with respect to 1 mass part of porous foams, Preferably it is 100 mass parts or more and 150 mass parts or less.

The base material 110 is hardened while the porous foam 120 is impregnated with the unhardened base material 110. In order to improve productivity, hardening is preferably performed by heating. Since the heating can be performed uniformly up to the center of the porous foam 120, the heating is preferably performed by hot pressing. The hot pressing is performed by pressing a plurality of pressing discs having a size larger than the porous foam 120 and sandwiching the porous foam 120 impregnated with the base material 110. In addition, the hot pressing may have both pressing for making the base material 110 throughout the entire void portion of the porous foam 120 and pressing for promoting hardening by heating.

The above-mentioned hardening by heating is preferably performed at a temperature of 100 ° C. to 160 ° C. and a heating time of 1 minute to 50 minutes. In particular, it is suitable to produce an eraser having both high shape retention and high erasability within a range of 110 ° C. to 120 ° C., and 1 minute to 20 minutes. The heating is preferably performed under pressure by pressing. The pressure during pressing can be appropriately set as required. For example, the pressing pressure when pressing the sheet of the eraser may be set to 5 kgf / cm ² (49 N / cm ² ) or more and 150 kgf / cm ² (1470 N / cm ² ) or less.

In addition, as the base material 110, for example, it is preferable to use 100 to 20,000 mPa ･ s (preferably 800 to 7,000 mPa ･ s) under measurement conditions of a temperature of 20 ° C, a B-type viscometer, and a rotation speed of 6 rpm. The base material 110 in a sol state, especially a sol-like composition of a polyvinyl chloride resin, is used as the unhardened base material 110. The reason is that if the base material 110 has a viscosity within this range, it has good fluidity at normal temperature in terms of impregnating the uncured base material 110 and absorbing it into the porous foam 120. In addition, the reason is that it is easy to fill the void portion and it is easy to harden in the filled state. In addition, even a high-viscosity uncured base material 110 exceeding 20,000 mPa ･ s can be impregnated by reducing the viscosity by heating or reducing the pressure.

The sheet-like eraser base material obtained by curing in the above-mentioned manner is cut into a predetermined size as necessary, thereby manufacturing the eraser 10.

[Eraser] The eraser 10 has a structure in which the base material 110 is impregnated into the porous foam 120. FIG. 2 is an enlarged sectional view of the eraser 10. 2, the eraser 10 impregnates the porous material 120 with the base material 110 so that the base material 110 is filled into the pores of the porous foam 120. In the state of the eraser 10, the base material 110 is hardened by heating and is held in the porous foam 120.

The eraser 10 is preferably configured such that the base material 110 is abraded and detached from the eraser by rubbing during erasing, and the skeleton structure of the porous foam 120 is detached as the base material 110 is abraded and broken.

The eraser 10 manufactured as described above has a tensile elastic modulus of 0.6 MPa to 1.2 MPa. According to research by the present inventors, if the tensile elastic modulus of the eraser 10 is 0.6 MPa or more, sufficient shape retention can be maintained in a normal use state, and it is difficult to cause bending of the eraser.

3 and 4 are diagrams showing a state where the eraser 10 is pressed against the paper surface 30 to eliminate characters. When erasing the characters on the paper surface 30 by the eraser 10, the user erases the characters depicted on the paper surface 30 by pressing the eraser 10 while rubbing against the paper surface 30. At this time, a force component f in a direction perpendicular to the paper surface 30 acts on the eraser 10. When the tensile elastic modulus is 0.6 MPa or more, the eraser 10 has sufficient shape retention, and therefore, as shown in FIG. 3, the deformation of the eraser 10 is small. In this state, the deformation of the grounding portion 40 is small, and the grounding portion 40 also follows the movement of the hand and moves with little bending. Furthermore, the ground portion 40 is easily seen when viewed from a user. As a result, small text is easily eliminated. In addition, since it is easy to apply a force to the eraser 10, the characters can be eliminated with a light touch (with less force), and the feeling of use is excellent.

On the other hand, when the tensile elastic modulus is less than 0.6 MPa, as shown in FIG. 4, the bending of the eraser 10 is increased by the action of the force component f. Therefore, the contact area of the ground portion 50 is increased, and the followability of the action of the opponent of the ground portion 50 is also deteriorated. In addition, it is blocked by the eraser 10 so that the ground portion 50 is hardly visible from the user. Therefore, it is difficult to selectively eliminate fine characters. In addition, since the force applied to the eraser 10 is dispersed due to bending, additional force is required in order to obtain a sufficient frictional force. In addition, since the outer peripheral side 12 of the bent portion is stretched, the sleeve joint portion 22 serving as a boundary between the eraser 10 and the outer cover 20 easily breaks the eraser 10. Therefore, if compared with the eraser shown in FIG. 3, the use feeling of the eraser of FIG. 4 is poor. Furthermore, if the tensile elastic modulus is more than 1.2 MPa, the eraser 10 will not be easily bent, and as a result, the characters will not be easily eliminated.

In this way, if the tensile elastic modulus of the eraser 10 is 0.6 MPa or more and 1.2 MPa or less, sufficient shape retention can be maintained in a normal use state, and it is difficult to cause bending of the eraser 10. As a result, it is possible to provide an eraser 10 which is easy to erase small characters, and can erase characters with a light touch, and has excellent use feeling.

The tensile elastic modulus is more preferably 0.7 MPa or more. When the tensile modulus of elasticity is 0.7 MPa or more, the above-mentioned effects due to a high tensile modulus of elasticity can be exhibited more fully.

The tensile modulus of elasticity can be measured, for example, using a sample cut into a dumbbell shape by a tensile tester using a method in accordance with JIS K 6251.

The eraser 10 having the tensile elastic modulus as described above and excellent in erasability can be obtained by selecting a material having a tensile elastic modulus suitable for forming a tensile elastic modulus of 0.6 MPa or more and 1.2 MPa or less. The porous foam 120 having characteristics such as the density and porosity of the eraser 10, or the heating conditions and the type or amount of the plasticizer when the eraser 10 is formed are adjusted. As an example, a melamine foam is used as the porous foam 120, and the uncured base material 110 is impregnated in the melamine foam at a temperature of 100 ° C or higher and 160 ° C or lower for 2 minutes or more. In addition, it is possible to obtain an eraser having a tensile modulus of elasticity of 0.6 MPa or more and 1.2 MPa or less while performing hot pressing and heating while the time is less than 50 minutes. 10.

The surface hardness of the eraser 10 is not particularly limited, and is, for example, 50 to 85, and preferably 60 to 75. The surface hardness can be measured by a method according to JIS S 6050.

The friction coefficient of the eraser 10 is preferably 1.0 or less. If the friction coefficient of the eraser 10 is 1.0 or less, it will be a level without problems in practical use. The friction coefficient of the eraser 10 is more preferably 0.8 or less. If the friction coefficient of the eraser 10 is 0.8 or less, it will be easy to erase characters with a light touch. The wear rate of the eraser 10 is preferably 0.7% or more. If the abrasion rate is 0.7% or more, the surface will not be easily contaminated during erasing, and erasing will be easier.

The erasure rate (%) of the eraser 10 is preferably 85% or more, more preferably 90% or more, more preferably 93% or more, and even more preferably 94% or more. If it is such a word erasing rate, it is possible to eliminate characters efficiently with a moderate number of rubs. The erasure rate can be measured by a method in accordance with JIS S 6050: 2002 6.4.

As described above, according to the eraser 10 of this embodiment, it is possible to provide an eraser having both high shape retention and high erasability. [Example]

Hereinafter, the present invention will be described more specifically with reference to examples. The scope of the present invention is not limited to the description of the examples.

(Example 1) (Preparation of eraser) An eraser of the example was prepared using a base material having the following composition and a porous foam shown below. In addition, the measurement of the particle diameter mentioned later was performed by the method based on JIS K5600-2-5; 1999, and three were measured with the 100 micrometers grid gauge.

[Base material] (1) Resin: Polyvinyl chloride (trade name "ZEST P21", manufactured by Shin Dai-Ichi Vinyl Corporation) (particle size: 55 μm, degree of polymerization 1550, K value 75.1, Viscosity 5300 (mPa ･ s)) 34.0 parts by mass (2) Plasticizer (2-1) DOP (dioctyl phthalate) (manufactured by Nippon Physico Chemical Co., Ltd.) ) DBP (dibutyl phthalate) (manufactured by Shin Nippon Physico Chemical Co., Ltd.) 8.0 parts by mass (3) filler heavy calcium carbonate (manufactured by Beibei Chemical Industry Co., Ltd.) 25.0 parts by mass (4) stabilizer (4-1) Magnesium-zinc stabilizer (trade name "EMBILIZER R-23L, manufactured by Tokyo Fine Chemical Co., Ltd.") 0.5 parts by mass (4-2) organophosphorus stabilizer (trade name "EMBILIZER TC-110S, (Made by Tokyo Fine Chemical Co., Ltd.) 0.2 parts by mass total 100 parts by mass

[Porous foam] Melamine foam (trade name "Basotect", manufactured by BASF Corporation) (tensile elastic modulus of melamine foam: 0.22 MPa, density: 9.0 kg / m ³ )

Each component which comprises a base material is put into a stirring container, and it stirs until it becomes uniform, thereby preparing a base material. With respect to 0.15 parts by mass of a melamine foam cut into a sheet shape having a predetermined size (60 mm × 23 mm × 10 mm), and 20 parts by mass of a base material impregnated. In the state where the melamine foam was impregnated with the base material, the base material was cured by hot pressing at a temperature of 105 ° C. and a pressing pressure of 10 kgf / cm ² (= 98 N / cm ² ) for 25 minutes to prepare the eraser A. . The friction coefficient of the obtained eraser A was 0.74.

(Example 2) The conditions for hot pressing were changed to a temperature of 113 ° C., a pressing time of 5 minutes, and a pressing pressure of 10 kgf / cm ² (= 98 N / cm ² ). Except that, the rubber was prepared in the same procedure as in Example 1. Rub B.

(Example 3) An eraser G was prepared in the same procedure as in Example 1 except that a polyvinyl chloride having a particle diameter of 45 μm was used as the polyvinyl chloride used as a resin component.

(Example 4) An eraser H was prepared in the same procedure as in Example 1 except that the polyvinyl chloride used as the resin component was a polyvinyl chloride having a particle diameter of 63 μm.

(Example 5) An eraser I was prepared in the same procedure as in Example 1 except that a melamine foam having a tensile elastic modulus of 0.14 MPa was used for the melamine foam used. The friction coefficient of the obtained eraser I was 0.66. The density of the melamine foam was 5.6 kg / m ³ .

(Example 6) An eraser J was prepared in the same procedure as in Example 1 except that a melamine foam having a tensile elastic modulus of 0.09 MPa was used for the melamine foam used. The friction coefficient of the obtained eraser J was 0.68. The density of the melamine foam was 8.9 kg / m ³ .

(Example 7) An eraser K was prepared in the same procedure as in Example 1 except that the obtained melamine foam was a melamine foam having a tensile elastic modulus of 0.32 MPa. The friction coefficient of the obtained eraser K was 0.64. The density of the melamine foam was 6.2 kg / m ³ .

(Example 8) An eraser L was prepared in the same procedure as in Example 1 except that ATBC (tributyl ethyl citrate) was used as a plasticizer and the base material was configured as follows.

[Base material] (1) Resin: 36.0 parts by mass (2) Plasticizer: 40.0 parts by mass (3) Filler: 23.4 parts by mass (4-1): Magnesium-zinc-based stabilizer: 0.5 parts by mass (4- 2): Organophosphorus stabilizer: 0.1 parts by mass

(Example 9) An eraser M was prepared in the same procedure as in Example 8 except that the base material had the following configuration.

[Base material] (1) Resin: 32.0 parts by mass (2) Plasticizer: 46.0 parts by mass (3) Filler: 21.5 parts by mass (4-1): Magnesium-zinc-based stabilizer: 0.4 parts by mass (4- 2): Organophosphorus stabilizer: 0.1 parts by mass

(Example 10) An eraser N was prepared in the same procedure as in Example 8 except that the base material had the following configuration.

[Base material] (1) Resin: 31.0 parts by mass (2) Plasticizer: 48.0 parts by mass (3) Filler: 20.5 parts by mass (4-1): Magnesium-zinc-based stabilizer: 0.4 parts by mass (4- 2): Organophosphorus stabilizer: 0.1 parts by mass

(Example 11) An eraser O was prepared in the same procedure as in Example 8 except that the base material had the following configuration.

[Base material] (1) Resin: 30.0 parts by mass (2) Plasticizer: 50.0 parts by mass (3) Filler: 19.5 parts by mass (4-1): Magnesium-zinc-based stabilizer: 0.4 parts by mass (4- 2): Organophosphorus stabilizer: 0.1 parts by mass

(Example 12) Using DOA (bis (2-ethylhexyl) adipate) as a plasticizer, polyvinyl chloride (trade name "ZEST P22", manufactured by Shin Daiichi Vinyl Chloride Co., Ltd.) (pellets) Diameter: 55 μm, degree of polymerization of 1060, K value of 67.1, viscosity of 3000 (mPa) s)), and the base material was prepared as follows except that the eraser P was prepared in the same procedure as in Example 8.

[Base material] (1) Resin: 36.0 parts by mass (2) Plasticizer: 40.0 parts by mass (3) Filler: 23.4 parts by mass (4-1): Magnesium-zinc-based stabilizer: 0.5 parts by mass (4- 2): Organophosphorus stabilizer: 0.1 parts by mass

(Example 13) An eraser Q was prepared in the same procedure as in Example 12 except that the base material had the following configuration.

[Base material] (1) Resin: 32.0 parts by mass (2) Plasticizer: 46.0 parts by mass (3) Filler: 21.5 parts by mass (4-1): Magnesium-zinc-based stabilizer: 0.4 parts by mass (4- 2): Organophosphorus stabilizer: 0.1 parts by mass

(Example 14) An eraser R was prepared in the same procedure as in Example 12 except that the base material had the following configuration.

[Base material] (1) Resin: 31.0 parts by mass (2) Plasticizer: 48.0 parts by mass (3) Filler: 20.5 parts by mass (4-1): Magnesium-zinc-based stabilizer: 0.4 parts by mass (4- 2): Organophosphorus stabilizer: 0.1 parts by mass

(Example 15) Polyvinyl chloride (trade name "ZEST P21", manufactured by Shin Daiichi Vinyl Chloride Co., Ltd.) (particle diameter: 55 μm, degree of polymerization 1550, K value 75.1, viscosity 5300 (mPa ･ s)) was used as Except for the resin, an eraser S was prepared in the same procedure as in Example 13.

(Example 16) Except that ATBC and DOA were used as plasticizers, and the base material was configured as described below, the same procedure as in Example 8 was used to prepare an eraser T.

[Base material] (1) Resin: 32.0 parts by mass (2-1) Plasticizer: ATBC: 23.0 parts by mass (2-2) Plasticizer: DOA: 23.0 parts by mass (3) Filler: 21.5 parts by mass ( 4-1): Magnesium-zinc based stabilizer: 0.4 parts by mass (4-2): Organic phosphorus based stabilizer: 0.1 parts by mass

Comparative Example 1 An eraser C was prepared in the same procedure as in Example 2 except that melamine foam was not used.

(Comparative Example 2) Except not using melamine foam, hot pressing was performed under the conditions of a temperature of 125 ° C., a pressing time of 10 minutes, and a pressing pressure of 10 kgf / cm ² (= 98 N / cm ² ). 2 In the same procedure, an eraser D was prepared.

(Comparative Example 3) An eraser E was prepared in the same procedure as in Example 2 except that the amount of DOP (dioctyl phthalate) was changed to 33.0 parts by mass without using a melamine foam.

(Comparative Example 4) An eraser F was prepared in the same procedure as in Example 2 except that the amount of DOP (dioctyl phthalate) was changed to 25.0 parts by mass without using a melamine foam.

[Measurement of physical properties and evaluation of characteristics] The physical properties of the eraser were measured by the following procedures to evaluate the characteristics.

[Tensile Elastic Modulus] The eraser 10 was punched into a dumbbell shape with a distance of 30 mm between the marked lines to prepare a test piece for a tensile test. Using the prepared test piece, the tensile elastic modulus (MPa) was measured by a method in accordance with JIS K 6251.

[Evaluation of Eraser Characteristics] Next, various characteristics as a general eraser were evaluated. As characteristics, the erasure rate (%), the ease with which a force is applied during erasure, the ease with which small characters can be eliminated, and the ease with which the surface of the eraser is stained are evaluated. The evaluation procedure is as follows.

[Word erasing rate] The word erasing rate is measured in accordance with JIS S 6050: 2002 6.4 or less.

(1) The eraser was cut into a plate shape with a thickness of 5 mm, and the front end portion in contact with the colored paper was finished into an arc with a radius of 6 mm, and the obtained piece was used as a test piece.

(2) Use a line drawing machine to make colored paper using HB of pencils specified in JIS S 6006, and Daolin paper with a weight per square meter of 90 g / m ² or more and a whiteness of 75% or more. The colored paper was brought into contact with the test piece so as to be perpendicular to the colored line. In this state, a weight is placed on the test piece so that the mass of the weight and the holder becomes 0.5 kg, and the coloring section is reciprocated 4 times at a speed of 150 ± 10 cm / min to be worn away.

(3) The density of the non-colored portion of the colored paper is set to 0 with a densitometer, and the concentrations of the colored portion and the abrasion portion are measured, respectively.

(4) The erasure rate is calculated by the following formula, and the average value is calculated three times.

Erasing rate (%) = (1-(density in the abraded portion / density in the colored portion)) × 100

[Easy to apply force, easy to remove small characters, easy to contaminate the surface of the eraser] The eraser was actually erased by using the erasers of the examples and comparative examples, thereby applying the force at the time of erasing Ease and ease of elimination of small characters were evaluated. In addition, the degree of contamination on the surface of the eraser after erasing was confirmed, and the ease of contamination on the surface was evaluated. Regarding the ease of application of force, from excellent to good, they were shown to be good, generally good, medium, and difficult to apply in order.

[Not easy to break] Samples of paper and an eraser 10 are prepared. The eraser 10 is a 60 mm × 23 mm × 10 mm eraser 10 and covers the outer cover 20 so that a part of the front end 12 mm × 23 mm × 10 mm is exposed. While holding the jacket 20 with the thumb and forefinger, the operator makes the eraser 10 contact the paper so that the angle between the eraser 10 and the paper becomes about 45 °. In this state, while applying a load of 1kgf (9.8N), it reciprocates 70 times within a range of 130mm in length, and then, while applying a load of 2.5kgf (24.5N), further reciprocates in a range of 130mm in length 70 times. After the back and forth movement, determine whether the eraser is broken. This evaluation was performed for each sample with the number of samples n = 5. A case where the number of samples broken (ruptured) in the middle of the reciprocating motion is 0 is evaluated as "good", a case where two or less is evaluated as "slightly poor", and a case where three or more are evaluated as "poor".

The erasers of Examples and Comparative Examples were evaluated in the manner described above. The results are shown in Table 1, Table 2, Table 3, and Table 4.

[Table 1]

[Table 2]

[table 3]

[Table 4] Note) ※ 1 The eraser has a small curvature, but there is no abrasion on the paper, so the friction is small and it is easy to slip. ※ 2) The surface structure is not sufficiently worn, so the handwriting is extended and the paper surface is contaminated.

(Results) Example 1, Example 2, Example 3, Example 4, Example 5, Example 6, Example 7, Example 8, Example 9, Example 10, Example 11, Example 12 Example 13, Example 14, Example 15 and Example 16 are examples of erasers that fall within the scope of the present invention. Comparative Examples 1 and 2 are examples of an eraser having a tensile elastic modulus of less than 0.6 MPa. In addition, Comparative Examples 3 and 4 each had a tensile elastic modulus of 0.6 MPa or more, but did not include an eraser for a porous foam. In addition, the erasers of Comparative Examples 1 and 2 also contained no porous foam in the same manner.

In the case of the erasers of Comparative Examples 1 and 2 in which the tensile modulus of elasticity did not reach 0.6 MPa, bending was caused during erasing, so that the force was not easily applied. Therefore, small text is not easy to eliminate. After the erasure, the surface of the eraser is prone to black stains. Furthermore, as shown by the evaluation of the resistance to breakage, it is clear that it is very easy to break, and the life of the eraser is shortened. In particular, it can be seen that the erasers of Comparative Example 1 and Comparative Example 2 are easily bent due to the low tensile modulus of elasticity. Therefore, at the boundary between the eraser 10 and the jacket 20 in FIG. 1, the eraser 10 contacts the sleeve joint 22 And easily broken.

The tensile elastic modulus of the erasers of Comparative Examples 3 and 4 is 0.6 MPa or more. However, in the case where the tensile elasticity modulus is increased without using a porous foam, the characteristics originally required of an eraser are not provided. Specifically, compared with other Examples and Comparative Examples, the erasure rate is significantly lower. Therefore, the characters did not sufficiently disappear, and the graphite extension of the characters due to friction caused contamination on the paper surface. In addition, since the tensile elastic modulus is 0.6 MPa or more, it is not easy to bend when erasing, but it is not worn on the surface, so the friction on the paper surface is small and it is easy to slip. Therefore, it is practically difficult to use as an eraser.

In contrast, the erasers of Examples 1 to 16 are evaluation results that can be satisfied for any of the characteristics. Specifically, since the erasers of Examples 1 and 16 have a tensile elastic modulus of 0.6 MPa or more and 1.2 MPa or less, a force is easily applied during erasing, and characters can be eliminated by lightly touching. In addition, even if a force is applied, there is less bending, so the user can easily see the contact surface with the paper surface, and the followability of the movement of the hand facing the user is also high. As a result, small text is easily eliminated. In addition, since melamine foam is included as a porous foam, the eraser scrape worn by the eraser is easily detached during erasure and new tissues are continuously exposed, so the surface of the eraser is also less contaminated. In addition, in the evaluation of non-breakability, no sample was broken in the reciprocating motion. The reason is that the erasers of Examples 1 to 16 in which the tensile elastic modulus is within the above-mentioned range are not easily deflected and the contact between the eraser and the sleeve joint portion is small. These results show that the shape retention of the erasers of Examples 1 to 16 is high.

Moreover, the high erasure rate is not necessarily related to the good feel of the eraser. The reason is that in the measurement of the erasure rate, while the test piece of the eraser is in vertical contact with the paper surface, a load is applied in a direction perpendicular to the paper surface to perform erasure. In contrast, when a general eraser is used, In most cases, writing is performed while the load is applied in a direction inclined with respect to the paper surface. When a load is applied in a direction inclined with respect to the paper surface, the eraser bends. At this time, an eraser having a tensile elastic modulus of 0.6 MPa or more and 1.2 MPa or less has sufficient resistance to bending, and therefore has an advantageous feature that a force can be easily applied and a small character can be easily eliminated.

As described above, the shape-retaining property and the high erasing property can be achieved by using an eraser including a base material, containing at least one of a resin component and an elastomer component, and plasticizing. Agent; and porous foam, impregnated base material; and has a tensile elastic modulus of 0.6 MPa to 1.2 MPa. As a result, it is possible to provide an eraser that is easy to apply force, can be erased with a light touch, and can be easily erased by small characters.

In addition, regarding Example 5, Example 6, and Example 7, the friction coefficient of the eraser was 0.8 or less. Therefore, it is easy to erase words with a light touch.

For Example 1, Example 3, and Example 4, polyvinyl chloride having a changed particle size was used. All of them were well evaluated. Here, when the particle diameter of polyvinyl chloride is too large, for example, it is larger than 100 micrometers, there exists a tendency for the gel hardness of the obtained eraser to become low. In addition, it tends to be soft as a characteristic of the obtained eraser, and tends to collapse in bulk when used. Furthermore, there was a tendency that granular blocks appeared on the surface of the obtained eraser, which also appeared to be unsatisfactory. On the other hand, when the particle diameter of polyvinyl chloride is too small, for example, it is less than 20 micrometers, there exists a tendency for the gel hardness of the obtained eraser to become high. In addition, it tends to harden as a characteristic of the obtained eraser, and tends to collapse in powder form during use. In addition, the rubber crumbs after use tend to be very fine and tend to pollute the surrounding environment. Furthermore, the surface of the eraser after use tends to be contaminated. Therefore, if the particle size of polyvinyl chloride is 20 μm or more and 100 μm or less, it is easy to produce the eraser in a preferred form. By setting the particle diameter of polyvinyl chloride to 45 μm or more and 63 μm or less as shown in Examples 1, 3, and 4, the eraser can be more reliably manufactured in a preferred form.

Furthermore, regarding the porous foam to be used, if the porous foam is very soft and has a large density, that is, the gap formed in the porous foam becomes large, it is not easy to obtain sufficient capillary pores during production. Impregnating effect. Therefore, the resin component melted into the inside of the porous foam tends to be difficult to impregnate. In addition, as the characteristics of the obtained eraser, it does not matter the toughness and tends to bend easily. In addition, the abrasion of the eraser during use tends to be broken in small amounts and to break in large pieces. Furthermore, there is a tendency that voids are easily generated inside the obtained eraser. On the other hand, if the porous foam is very hard and has a high density, that is, the gap formed in the porous foam is reduced, there is a tendency that the porous resin is not easily impregnated with the molten resin component during the production. . In addition, regarding the obtained eraser, the amount of wear of the eraser at the time of use tends to be small, a new surface is not easily exposed, and the erasing property tends to be poor. Thus, by the density of the porous foam, for example, to 3.5kg / m ³ or more and 12.0kg / m ³ or less, tends to be preferred when form manufacture and use.

It should be understood that the embodiments disclosed herein are illustrative in all aspects and are not limited in any respect. The scope of the present invention is defined by the scope of the patent application, not the above description, and is intended to include any modifications within the scope and meaning equivalent to the scope of the patent application. (Industrial availability)

The eraser of the present invention can be particularly advantageously applied to the field requiring an eraser having both high shape retention and high erasability.

10‧‧‧ Eraser

12‧‧‧ the outer peripheral side of the bend

20‧‧‧ coat

22‧‧‧ sleeve joint

30‧‧‧Paper

40‧‧‧ Ground

50‧‧‧ Ground

110‧‧‧Base material

120‧‧‧ porous foam

f‧‧‧force component

FIG. 1 is a schematic diagram showing an eraser of the present invention. Fig. 2 is an enlarged sectional view of the eraser. Fig. 3 is a view showing a state of a load stress of an eraser. FIG. 4 is a diagram showing a state in which the eraser is bent under the load stress of the eraser.

Claims (5)

An eraser comprising: a base material containing at least one of a resin component and an elastomer component, and a plasticizer; and a porous foam impregnated with the base material; having a pull of 0.6 MPa or more and 1.2 MPa or less Stretch modulus of elasticity. The eraser according to claim 1, wherein the porous foam is a melamine foam. The eraser according to claim 1 or 2, wherein the resin component is polyvinyl chloride. The eraser according to claim 1 or 2, wherein the tensile elastic modulus of the porous foam is from 0.05 MPa to 0.4 MPa. 1 or 2 as an eraser according to the requested item, wherein the density of the porous foam of 3.5kg / m ³ or more and 12.0kg / m ³ or less.