Eraser and eraser product using the same

Abstract

To provide an eraser which can restore the appearance to have desired corners without cutting even after use and has excellent productivity, and an eraser product using the same.SOLUTION: The eraser of the present invention contains a thermoplastic resin having a melting point of 40°C to 90°C, a tackifier, and a filler having an average particle size of 0.5 μm to 15 μm. The eraser product of the present invention includes the above eraser and a sleeve, and the sleeve has a first rectangular surface and a second rectangular surface connected thereto via at least one side constituting the first rectangular surface.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to an eraser and an erasing product using the same, and more particularly to an eraser capable of reproducing an arbitrary appearance and an erasing product using the same. [Background technology]

[0002] The ease of erasing an eraser (erasability) varies depending on the amount of pressure applied to the contact surface when pressed against the paper. The corners of an eraser can increase the pressure per unit area on the contact surface, and are also useful for erasing small parts of letters and lines.

[0003] On the other hand, the corners of the eraser are easily deformed and worn down with use. For this reason, there are many people who choose not to use the corners in order to conserve the eraser, and instead use the eraser on other parts of the pen.

[0004] A typical eraser has, for example, a rectangular parallelepiped appearance and is composed of four vertices and 12 sides. In recent years, on the other hand, in order to provide more corners than a rectangular parallelepiped, erasers having polygonal prisms or multi-sided structures have been proposed (for example, Patent Documents 1 and 2), and some have been commercialized.

[0005] However, the manufacture of such erasers having a complex appearance requires special dies and many manufacturing steps, which ultimately leads to a decrease in productivity.

[0006] Furthermore, even if the eraser has a complex appearance as described above, its corners are essentially "finite." It is inevitable that the corners will be worn down and lost with repeated use.

[0007] Alternatively, it is possible to create a new corner by cutting off a part of the eraser that has lost its corner with a sharp blade. However, in that case, it is expected that some of the eraser that has been cut off will have to be discarded, so this is not an economically viable solution. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] JP 2016-120688 A [Patent Document 2] JP 2004-034624 A Summary of the Invention [Problem to be solved by the invention]

[0009] The present invention aims to solve the above problems, and its object is to provide an eraser that can restore the appearance to have a desired corner without cutting even after use, and has excellent productivity, and an eraser product using the same. [Means for solving the problem]

[0010] The present invention is an eraser containing a thermoplastic resin having a melting point of 40° C. to 90° C., a tackifier, and a filler having an average particle size of 0.5 μm to 15 μm.

[0011] In one embodiment, the content of the thermoplastic resin is 30% by mass to 70% by mass based on the total mass.

[0012] In one embodiment, the melt flow rate (MFR) of the thermoplastic resin at 190° C. under a load of 2.16 kg is 30 g / 10 min to 100 g / 10 min.

[0013] In one embodiment, the thermoplastic resin is at least one resin selected from the group consisting of α-olefin copolymers and ethylene-vinyl acetate copolymers.

[0014] In a further embodiment, the tackifier is an olefinic resin.

[0015] In one embodiment, the filler comprises calcium carbonate.

[0016] The present invention also provides an eraser product comprising the above eraser and a sleeve, The sleeve is an eraser product having a first rectangular surface and a second rectangular surface connected to the first rectangular surface via at least one side that constitutes the first rectangular surface.

[0017] In one embodiment, the sleeve has four second rectangular surfaces connected via four sides constituting the first rectangular surface, and is expandable.

[0018] In one embodiment, the sleeve is waterproof. Effect of the Invention

[0019] According to the present invention, good erasability can be obtained by using the corners of the eraser, and the corners lost through use can be easily regenerated. This means that there is no need to actively avoid using the corners in order to preserve them, and when they wear down, they can be softened and restored to obtain the desired corners, or the cut pieces can be reused. [Brief description of the drawings]

[0020] [Figure 1] FIG. 2 is a diagram showing an example of a sleeve constituting the eraser product of the present invention, showing the sleeve in an expanded state. [Diagram 2] 1(a) to 1(d) are schematic diagrams illustrating a procedure for restoring corners of an eraser product of the present invention that have worn down through use by using an expandable sleeve. [Diagram 3] 3(a) and 3(b) are schematic diagrams for explaining an example in which the sleeve shown in FIG. 2 is used for storing an eraser. [Figure 4] 1(a) to 1(d) are schematic diagrams illustrating the procedure for regenerating the corners of an eraser product of the present invention using a square cylindrical sleeve. [Diagram 5]1(a) to 1(c) are schematic diagrams illustrating the procedure for forming an eraser of the present invention, which has been separated into individual blocks, into a single eraser with regenerated corners by using a square cylindrical sleeve. [Figure 6] 1A is a photograph of the eraser sample (E1) prepared in Example 1 and used to measure the erasure rate, the corners of which were cut off, and FIG. 1B is a photograph of the eraser sample (E1) in Example 4, the corners of which were regenerated. [Figure 7] Photograph (a) shows the state in which the pellet-shaped eraser pellets produced in Example 5 are packed into a bottomed square tube with one side portion removable as a lid, photograph (b) shows the state in which a round rod is inserted into the square tube after it has been removed from the hot water bath and the contents are pressed into it, and photograph (c) shows the contents (eraser sample) obtained after the lid of the square tube is removed after it has been allowed to cool. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] The present invention will be described in detail below.

[0022] 1. Erasing The eraser of the present invention contains a thermoplastic resin, a tackifier and a filler.

[0023] (thermoplastic resin) The thermoplastic resin plays a role as a base resin in the eraser of the present invention, and may have a relatively low melting point compared to the thermoplastic resins used in general films and sheets. The melting point of the thermoplastic resin in the present invention is, for example, 40°C to 90°C, preferably 40°C to 60°C, and more preferably 50°C to 60°C. When the thermoplastic resin has such a melting point, the eraser can be molded by, for example, immersing in hot water or heating with a hair dryer or toaster oven, and the desired corners can be regenerated (reformed) for the eraser. If the melting point of the thermoplastic resin is below 40°C, the eraser may easily deform under conditions such as the user's body temperature, indoors in summer, or inside a car under the hot sun. If the melting point of the thermoplastic resin is above 90°C, the user is forced to regenerate the corners of the eraser in a temperature environment where the safety of the user is low.

[0024] In the present invention, the thermoplastic resin is also preferably one that has high fluidity during the manufacture of the eraser. Specifically, the thermoplastic resin may be positively selected to have a predetermined melt flow rate (MFR).

[0025] For example, the MFR of the thermoplastic resin constituting the eraser of the present invention at 190°C and 2.16kg load is preferably 30g / 10min to 100g / 10min, more preferably 30g / 10min to 70g / 10min. If the MFR of the thermoplastic resin at 190°C and 2.16kg load is less than 30g / 10min, the resulting eraser itself may be too hard, and even if a certain amount of heat is applied, the eraser itself may be deformed or the corners of the eraser may be difficult to restore. If the MFR of the thermoplastic resin at 190°C and 2.16kg load is more than 100g / 10min, the resulting eraser may be easily stuck to the paper surface when used, and the erasability may be reduced.

[0026] The MFR of such thermoplastic resins at 190° C. and a load of 2.16 kg can be measured according to ASTM D1238.

[0027] Examples of the thermoplastic resin in the present invention include ethylene-α-olefin copolymers, ethylene-vinyl acetate copolymers, and combinations thereof. Ethylene-α-olefin copolymers are preferred because they are readily available commercially. Ethylene-α-olefin copolymers are commercially available under the trade names of "Tafmer DF7350" manufactured by Mitsui Chemicals, Inc. and "Ultrathene" manufactured by Tosoh Corporation.

[0028] The content of the thermoplastic resin that can be contained in the eraser of the present invention is not particularly limited, but is preferably 30% by mass to 70% by mass, more preferably 40% by mass to 60% by mass. If the content of the thermoplastic resin is less than 30% by mass, the resulting eraser itself may be too hard, and even if a certain amount of heat is applied, the eraser itself may be deformed or the corners of the eraser may be difficult to repair. If the content of the thermoplastic resin is more than 70% by mass, the resulting eraser may be difficult to crumble during erasing, and the erasability may be reduced.

[0029] (Other resins) In the present invention, the thermoplastic resin may contain other resins, elastomers and / or rubbers (hereinafter, these may be collectively referred to as "other resins, etc.") within the range that does not impair the effects of the present invention provided by the above-mentioned thermoplastic resin. Examples of other resins include vinyl chloride resins (including, for example, homopolymers consisting of vinyl chloride as a structural unit, and copolymers containing vinyl chloride and comonomers such as vinyl acetate, ethylene, methyl acrylate, and methyl methacrylate as structural units, either alone or in combination), styrene-based thermoplastic elastomers, acrylic-based thermoplastic elastomers, PVC-based thermoplastic elastomers, polyester-based thermoplastic elastomers, polyurethane-based thermoplastic elastomers, nylon-based thermoplastic elastomers, and chlorinated polyethylene copolymer crosslinked alloys, natural rubber, synthetic rubber (including, for example, diene-based rubbers such as isoprene rubber, butadiene rubber, styrene-butadiene rubber, chloroprene rubber, and acrylonitrile-butadiene rubber, as well as combinations thereof; and non-diene-based rubbers such as butyl rubber, ethylene-propylene rubber, urethane rubber, silicone rubber, chlorosulfonated polyethylene, chlorinated polyethylene, acrylic rubber, epichlorohydrin rubber, and fluororubber, as well as combinations thereof).

[0030] In the present invention, the content of the other resins and the like can be appropriately selected by those skilled in the art within a range that does not impair the effects of the present invention provided by the thermoplastic resin.

[0031] (tackifier) The tackifier is used to improve the grip of the resulting eraser on the paper surface and to enhance the adsorption of pencil powder (e.g., graphite) on the paper surface to be erased. It is preferable to use a tackifier that has compatibility with the above thermoplastic resin in order to enhance the dispersibility in the resulting eraser. For example, when an α-olefin copolymer is used as the thermoplastic resin, it is preferable that the tackifier is an olefin resin. Examples of tackifiers include olefin resins such as butene copolymers, terpene resins, coumarone-indene resins, petroleum resins, and rosin resins, as well as combinations thereof.

[0032] The content of the tackifier that may be contained in the eraser of the present invention is not particularly limited, but is preferably 1.5% by mass to 5% by mass, more preferably 2% by mass to 3.5% by mass, based on the total mass of the eraser. If the content of the tackifier is less than 1.5% by mass, the graphite adsorption of the resulting eraser may not be enhanced, and erasability may decrease. If the content of the tackifier is more than 5% by mass, the resulting eraser may easily stick to the paper surface when used, and erasability may decrease.

[0033] (filling material) The filler provides a predetermined hardness to the combination of the thermoplastic resin and the tackifier, and serves to apply an appropriate load to the contact surface between the eraser and the paper when the resulting eraser is pressed against the paper and rubbed.

[0034] In the present invention, the filler has an average particle size of 0.5 μm to 15 μm, preferably 1 μm to 13 μm, and more preferably 2 μm to 10 μm. If the average particle size of the filler is less than 0.5 μm, the strength of the resulting eraser increases, making it difficult for debris to be produced, and erasability may decrease. If the average particle size of the filler exceeds 15 μm, the resulting eraser becomes slippery, making it difficult for debris to be produced, and erasability may decrease. In the present invention, the filler may be contained in the form of a combination of two or more fillers that satisfy the above-mentioned range of average particle size.

[0035] Examples of such fillers include calcium carbonate (e.g., heavy calcium carbonate and light calcium carbonate), talc, silica, diatomaceous earth, magnesium oxide, sericite, quartz powder, montmorillonite, and shell powder (e.g., scallop, oyster, mussel, etc.), and combinations thereof. The filler preferably contains calcium carbonate because it has excellent versatility for erasing and can provide better erasability for the combination of the thermoplastic resin and the tackifier, and more preferably contains heavy calcium carbonate because it can increase the hardness of the corners of the resulting eraser.

[0036] The content of the above-mentioned filler that can be contained in the eraser of the present invention is not particularly limited, but is preferably 20% by mass to 45% by mass, more preferably 25% by mass to 40% by mass. If the content of the filler is less than 20% by mass, the resulting eraser is soft, making it difficult to restore the corners of the eraser, and may be significantly deformed when pressed against paper and rubbed, while the erasability may be reduced. If the content of the filler is more than 45% by mass, the resulting eraser becomes too hard, and may cause cracks on the surface of the eraser or become easily broken by continued rubbing on paper.

[0037] (Other ingredients) The eraser of the present invention may contain other components within the range that does not impair the effect of the present invention achieved by the combination of the above-mentioned thermoplastic resin (other resins, etc., as necessary), tackifier, and filler. Such other components include, for example, factice, reinforcing material, lubricant, and colorant, and combinations thereof.

[0038] Like the above fillers, factice imparts appropriate softness and stickiness to the eraser, making it easier to crumble during use. In addition, it can prevent the adsorptive power of the graphite in the eraser from decreasing, particularly when inorganic fillers are used as the filler.

[0039] Factice is a rubber-like material obtained by vulcanizing vegetable oils (e.g., linseed oil, rapeseed oil, cottonseed oil, soybean oil, and combinations thereof), and includes crosslinked vegetable oils and fats obtained by reacting the vegetable oils with sulfur chloride and lime or magnesium oxide.

[0040] The reinforcing material can increase the strength of the eraser, such as its bending elasticity, to suppress bending during erasing and suppress dispersion of force. Specific examples include powdered cellulose, carbon black, and activated calcium carbonate, as well as combinations thereof.

[0041] The lubricant is used to facilitate release from a mold when the eraser is molded, and specific examples thereof include surfactants commonly used in the art.

[0042] The colorant is used for the purpose of giving the eraser a predetermined color, and specific examples thereof include inorganic pigments, organic pigments, disperse dyes, and reactive dyes.

[0043] In the eraser of the present invention, the contents of the above-mentioned other components are not particularly limited, and can be appropriately selected by those skilled in the art.

[0044] (Manufacturing method of eraser) The eraser of the present invention can be produced by melt-kneading the above components, followed by heat molding. Examples of the molding method include press molding, injection molding, and extrusion molding. As a specific example, the eraser of the present invention can be produced by kneading the above components in a blender to prepare a mixture (compound), pelletizing the mixture using a pulverizer or pelletizer, and then extrusion molding. The extrusion temperature is not necessarily limited, but the eraser of the present invention can be obtained by extrusion molding at, for example, 30°C to 80°C, preferably 40°C to 50°C.

[0045] (Thermal deformation of erasers) The eraser of the present invention, containing a thermoplastic resin as a main component with a relatively low melting point, can be easily thermally deformed, for example, by immersing in hot water (water) set at a temperature equal to or higher than the melting point of the thermoplastic resin constituting the eraser and not higher than 100°C. Heating of the eraser is not limited to immersion in hot water. For example, it can be heated using a heating means such as a hair dryer or a toaster oven. The time required for heating is not particularly limited, since it depends on the size and shape of the entire eraser. An appropriate heating time can be set by a person skilled in the art.

[0046] After heating, for example, by using a finger or a sleeve as described later, the eraser of the present invention can freely and easily form an acute angle, a right angle, or an obtuse angle at any part of the eraser. In addition, the eraser of the present invention can also weld together erasers that have been separated due to collapse or folding during use, for example, by heating them at the above temperature.

[0047] 2. Eraser products The eraser product of the present invention comprises the eraser and the sleeve. Here, the term "eraser product" used in this specification refers to a general product that includes the eraser and the sleeve of the present invention as constituent items, and includes any of the following forms: a product in which the eraser is housed in the sleeve, a product in which the eraser and the sleeve are individually housed in the same package, and a product in which the eraser and the sleeve can be obtained (e.g. purchased) individually and used together.

[0048] (sleeve) FIG. 1 is a diagram showing an example of a sleeve constituting the eraser product of the present invention, showing the sleeve in an unfolded state.

[0049] The sleeve 100 shown in FIG. 1 includes a first rectangular surface 110 and a second rectangular surface 120 connected to the first rectangular surface 110 via at least one of sides 112, 114, 116, and 118 that constitute the first rectangular surface 110.

[0050] 1, four second rectangular surfaces 120 are connected to the first rectangular surface 110 via sides 112, 114, 116, and 118. This allows the sleeve 100 to be unfolded such that the four second rectangular surfaces 120 are bent independently relative to the first rectangular surface 110 via the sides 112, 114, 116, and 118.

[0051] In addition, in the sleeve 100 shown in Fig. 1, a marker portion 130, which is shown as a hollow triangle in Fig. 1, is provided by printing or the like at the corners of each second rectangular surface 120 (connecting the first rectangular surface 110 via sides 112, 114, 116, 118). In the present invention, the marker portion 130 may be provided only on one surface (e.g., the front surface) of the sleeve 100, or may be provided on both surfaces (i.e., both the front surface and the back surface) of the sleeve 100.

[0052] The sleeve 100 is made of paper, plastic, or a combination thereof having a suitable thickness. The sleeve 100 may also be waterproofed as known in the art to such an extent that it can retain its shape when immersed in hot water (cold water), as described below.

[0053] (How to restore the corners of an eraser) In the present invention, such a sleeve 100 can be used to regenerate the corners of an eraser that have worn down through use in the following manner.

[0054] FIG. 2(a) to (d) are schematic diagrams illustrating the procedure for restoring the corners of the eraser product of the present invention, which have worn down through use, by using an expandable sleeve.

[0055] In the embodiment shown in FIG. 2, first, a preheated eraser 140 is pressed against the first rectangular surface 110 of the sleeve 100 as shown in FIG. 2(a).

[0056] In Fig. 2(a), the preheated eraser 140 is, for example, an eraser whose corners have already been lost due to wear and tear through use, and is already in a soft and deformable state due to the above-mentioned heating. Note that Fig. 2(a) shows a state in which the worn portion 142 of the eraser 140 is pressed against the first rectangular surface 110 of the sleeve 100, but the present invention is not limited to this. It is sufficient that the worn portion 142 of the eraser 140 is pressed against either the first rectangular surface 110 or the second rectangular surface 120.

[0057] Next, the second rectangular surface 120 of the sleeve 100 is folded along the outer periphery of the eraser 140 (FIG. 2(b)). In this state, the marker portion 130 provided on the second rectangular surface 120 is pinched and pressed with the fingers (FIG. 2(c)). Thereafter, by opening the second rectangular surface 120 of the sleeve 100, the eraser 150 can be obtained, with corners formed at positions corresponding to the marker portion 130 of the sleeve 100.

[0058] Furthermore, the eraser 150 is cooled and solidified as necessary by leaving it to cool, immersing it in cold water, exposing it to cold air, storing it in a low-temperature cabinet, or the like.

[0059] In this way, an eraser 150 with regenerated corners can be obtained.

[0060] In addition, the sleeve 100 has a structure in which the second rectangular surface 120 can be expanded relative to the first rectangular surface 110 as shown in Figures 1 and 2. Therefore, if corner restoration is not performed, it may be necessary to store the sleeve 100 separately from the eraser 150.

[0061] Therefore, in the eraser product 200 of the present invention, in addition to the eraser 150 and the sleeve 100, a ring-shaped frame 210 may be provided (FIG. 3(a)). The ring-shaped frame 210 is designed to be large enough to accommodate the outer periphery of the sleeve 100 with its inside folded, and is made of a material such as paper, plastic, or rubber. As shown in FIG. 3(b), the eraser 150 is accommodated in the folded state of the sleeve 100, and the outer periphery of the sleeve 100 is fixed by the ring-shaped frame 210, so that the sleeve 100 can be used as a case for accommodating the eraser 150 with its unfolding restricted by the ring-shaped frame 210.

[0062] If the corner of the eraser 150 is lost again through use of the eraser 150, the corner can be restored by removing the annular frame 210 from the sleeve 100 as described above with reference to FIG.

[0063] Next, a method for regenerating the corners of an eraser using a sleeve having a different shape will be described.

[0064] As shown in Fig. 4(a), the sleeve 300 may have a rectangular cylindrical shape. That is, the sleeve 300 shown in Fig. 4(a) has two second rectangular faces 320 connected via two opposing sides 312, 314 that constitute two first rectangular faces 310.

[0065] The eraser 340, which has been preheated in the same manner as above, is inserted into such a sleeve 300, and the eraser 340 is pressed firmly into the upper opening 324 of the sleeve 300 with, for example, a finger 360 while the sleeve 300 is placed on a flat table 330 such as a desk (FIG. 4(b)). After that, the sleeve 300 is removed and cooled, and an eraser 350 with regenerated corners 352, 354 can be obtained (FIG. 4(c)).

[0066] Further, another method for restoring the corners of an eraser by using the sleeve 300 will be described with reference to FIG.

[0067] In the method shown in Fig. 5, a plurality of preheated eraser blobs 440 are filled into the sleeve 300 while the sleeve 300 is placed on a flat table 330 (Fig. 5(a)). Examples of the eraser blobs 440 include erasers that have become extremely small through use, eraser fragments that are accidentally generated during use, eraser chips, and combinations thereof. The eraser blobs 440 are heated in the same manner as above and are housed in the sleeve 300 in a thermally deformable state.

[0068] After that, the eraser lump 440 is pressed firmly into the upper opening 324 of the sleeve 300, for example, by a finger 360 (FIG. 5(b)). Then, the sleeve 300 is removed and cooled, and an eraser 450 with reconstructed corners 452, 454 can be obtained (FIG. 5(c)). In this way, the eraser 450 obtained in FIG. 5(c) is one in which the individually separated lump pieces are welded together and reconstructed into a single structure.

[0069] In the eraser product of the present invention, in addition to regenerating the corners of the eraser, which is a component, it is also possible to regenerate the eraser itself through the welding of the eraser lumps. This allows the user to actively use the eraser corners to erase without having to preserve the corners that are originally useful. In addition, since the corners lost through wear due to use can be easily regenerated as described above, the eraser with excellent erasing efficiency can be used for a long period of time. EXAMPLES

[0070] The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples.

[0071] The eraser samples obtained in the examples and comparative examples described below were each evaluated as follows.

[0072] (HB pencil erasure rate) The HB pencil erasure rate of the obtained eraser sample was measured in accordance with JIS S 6050 (2002).

[0073] (Angular formation) The eraser samples prepared in Example 1 and Comparative Example 1 were cut into a size of 10 mm length x 10 mm width x 10 mm thickness to prepare test pieces, and the obtained test pieces were placed in thermostatic chambers set at temperatures of 30°C, 40°C, 50°C, 60°C, 70°C and 80°C for 1 hour, and immediately after removal, the test pieces were pinched between fingers through the expandable paper sleeve 100 shown in Figure 1 to attempt to form corners. After cooling, the sleeve was removed and the test pieces were visually observed to see whether corners could be formed, and were evaluated according to the following criteria: ○ The test piece was able to deform appropriately and form an angle of approximately 90°. ×: The test piece was not deformed sufficiently to form an angle of approximately 90°.

[0074] (Example 1: Preparation of eraser sample (E1)) The mixture consisted of 230 parts by mass (43.7% by mass) of an α-olefin copolymer (Tafmer DF7350 manufactured by Mitsui Chemicals, Inc.; melting point 55°C, MFR at 190°C and a load of 2.16 kg according to ASTM D1238 of 35 g / 10 min, and MFR at 230°C and a load of 2.16 kg of 65 g / 10 min), 11.5 parts by mass (2.2% by mass) of a tackifier (REXTAC RT2730 manufactured by Mitsui Chemicals, Inc.; 1-butene-propylene copolymer), 115 parts by mass (21.8% by mass) of a first filler (heavy calcium carbonate; SS#30 manufactured by Nitto Powder Co., Ltd.; average particle size 7.2 μm), 80 parts by mass (15.2% by mass) of a second filler (heavy calcium carbonate; SS#80 manufactured by Nitto Powder Co., Ltd.; average particle size 2.61 μm), and a reinforcing material (powdered cellulose; Nippon Paper Industries Co., Ltd.). 6.9 parts by mass (1.3% by mass) of KC Flock W-400G (manufactured by Tenma Sub Kako Co., Ltd.), 75 parts by mass (14.2% by mass) of Factice (crosslinked vegetable oil; unsulfurized Sub U-8 manufactured by Tenma Sub Kako Co., Ltd.), and 8 parts by mass (1.5% by mass) of lubricant (surfactant; Excel S-95 manufactured by Kao Corporation) were kneaded for 30 minutes in a kneader set at 80°C to obtain a kneaded product, which was then molded in an extruder to obtain an eraser sample (E1). The size of this eraser sample (E1) was 54.5 mm long x 19.8 mm wide x 10.7 mm thick. The ratio of the components of the eraser sample (E1) and the results of the erasure rate are shown in Table 1. The evaluation results of the corner formability of the eraser sample (E1) are shown in Table 2.

[0075] (Example 2: Preparation of eraser sample (E2)) Except for not adding the second heavy calcium carbonate and the lubricant, an eraser sample (E2) was prepared in the same manner as in Example 1. The ratio of the components of the eraser sample (E2) and the results of the erasure rate are shown in Table 1. The evaluation results of the corner formability of the eraser sample (E2) are shown in Table 2.

[0076] (Example 3: Preparation of eraser sample (E3)) Except for not adding the second heavy calcium carbonate, factice and lubricant, an eraser sample (E3) was prepared in the same manner as in Example 1. The ratio of the components of the eraser sample (E3) and the results of the erasure rate are shown in Table 1. The evaluation results of the corner formability of the eraser sample (E3) are shown in Table 2.

[0077] (Comparative Example 1: Preparation of eraser sample (C1)) A non-vinyl chloride eraser sample (C1) was prepared as follows.

[0078] Styrene-butadiene-styrene block (SBS) resin (T-475 manufactured by Asahi Chemical Industry Co., Ltd.) 70 parts by mass (20.6% by mass), styrene-ethylene-propylene-styrene (SEPS) resin (Septon 2043 manufactured by Kuraray Co., Ltd.) 30 parts by mass (8.8% by mass), heavy calcium carbonate (manufactured by Maruo Calcium Co., Ltd.) 200 parts by mass (58.8% by mass), and process oil (PW-90 manufactured by Idemitsu Kosan Co., Ltd.) 40 parts by mass (11.8% by mass) were kneaded for 40 minutes in a kneader set at 120 ° C., and then molded in an extruder to obtain an eraser sample (C1). The size of this eraser sample (C1) was 54.5 mm long x 19.8 mm wide x 10.7 mm thick. The ratio of the components of the eraser sample (C1) and the results of the erasure rate are shown in Table 1. The evaluation results of the corner formability of the eraser sample (C1) are shown in Table 2.

[0079] [Table 1]

[0080] [Table 2]

[0081] As shown in Table 1, the eraser samples (E1) to (E3) obtained in Examples 1 to 3 exhibited erasure rates equal to or higher than that of the eraser sample (C1) of Comparative Example 1, which corresponds to a typical non-vinyl chloride eraser, and had basic performance as an eraser.

[0082] Furthermore, as shown in Table 2, when the eraser sample (E1) obtained in Example 1 was heated at a temperature exceeding the melting point 55°C of the α-olefin copolymer used (60°C, 70°C and 80°C), it had a sticky feel when pressed with a finger immediately after heating and was easily deformable. Also, from such a state immediately after heating, the corners of the eraser could be easily formed using a sleeve as shown in Figure 1 (Table 2).

[0083] In contrast, the eraser sample (C1) obtained in Comparative Example 1 did not have the same tactile sensation as the eraser sample (E1) of Example 1, and could not be deformed at all, even when heated at any of the temperatures used for evaluation, between 30°C and 80°C. In addition, even when using a sleeve as shown in Fig. 1, the corners of the eraser could not be formed at all from the state immediately after such heating (Table 2).

[0084] (Example 4: Regeneration and use of eraser sample (E1)) The eraser sample (E1) (FIG. 6(a)) prepared in Example 1 and used to measure the erasure rate and with its corners cut off was immersed in a hot water bath at 70 to 80°C for 20 seconds. After confirming by touch that the entire eraser sample (E1) had softened, the eraser sample (E1) was wrapped in a paper sleeve 100 that can be expanded as shown in FIG. 1 so as to cover the part of the eraser sample (E1) with its corners cut off, and was cooled in water for 30 seconds. After that, the sleeve 100 was removed, and the state of the part of the eraser sample (E1) covered by the sleeve 100 was photographed. The obtained results are shown in FIG. 6(b).

[0085] As is clear from Figs. 6(a) and (b), the corners of the eraser sample (E1) (Fig. 6(a)), which had been worn down due to use, could be restored by immersing it in the hot water and then covering it with the sleeve 100 (Fig. 6(b)).

[0086] In addition, when an attempt was made to erase characters written on paper with an HB pencil using the eraser sample (E1) with the regenerated corners shown in (b) of FIG. 6, the regenerated corners of the eraser sample (E1) allowed for comfortable erasure.

[0087] (Example 5: Regeneration of eraser sample (E5) using eraser block) From the kneaded material prepared in the same manner as in Example 1, a large number of small pellet-shaped eraser lumps having a size of 3 to 6 mm were obtained using a pelletizer. The small eraser lumps were placed in a bottomed square tube (inside dimensions: length 33 mm x width 22 mm x thickness 19 mm) made of PP (polypropylene) with one side part removable as a lid (FIG. 7(a)), and after closing with the lid on the side part, the square tube was immersed in a hot water bath at 70 to 80°C for 1 minute. The square tube was removed from the hot water bath, a round bar was inserted from the opening to push the contents in (FIG. 7(b)), and further small eraser lumps were filled in the newly formed space by the pushing, and the square tube was immersed in the hot water bath again for 1 minute. Thereafter, the square tube was removed from the hot water bath and allowed to cool to room temperature. After cooling, the lid was removed and a photograph of the obtained contents was taken. The result is shown in FIG. 7(c).

[0088] As shown in FIG. 7(c), the packed pellet-like eraser lumps were regenerated into a single lump (eraser sample (E5)) through the above-mentioned series of operations.

[0089] In addition, when an attempt was made to erase characters written on paper with an HB pencil using the eraser sample (E5) shown in (c) of FIG. 7, the regenerated corners of the eraser sample (E5) allowed for comfortable erasure. [Explanation of symbols]

[0090] 100,300 sleeve 110,310 First rectangular surface 112,114,116,118,312,314 sides 120,320 Second rectangular surface 130 Marker section 140,340 Preheated eraser 142 Wear parts 150, 350, 450 characters erased 210 Annular frame 324 Opening 352,354,452,454 angle 330 Flat platform 360 fingers 440 Eraser Block

Claims

1. An eraser comprising a thermoplastic resin having a melting point of 40° C. to 90° C., a tackifier, and a filler having an average particle size of 0.5 μm to 15 μm.

2. 2. The eraser according to claim 1, wherein the content of the thermoplastic resin is 30% by mass to 70% by mass based on the total mass.

3. 2. The eraser according to claim 1, wherein the thermoplastic resin has a melt flow rate (MFR) of 30 g / 10 min to 100 g / 10 min at 190° C. and a load of 2.16 kg.

4. 2. The eraser according to claim 1, wherein the thermoplastic resin is at least one resin selected from the group consisting of α-olefin copolymers and ethylene-vinyl acetate copolymers.

5. The eraser according to claim 1 , wherein the tackifier is an olefin resin.

6. The eraser of claim 1 , wherein the filler material comprises calcium carbonate.

7. An eraser product comprising the eraser according to any one of claims 1 to 7 and a sleeve, The eraser product has a first rectangular surface and a second rectangular surface connected to the first rectangular surface via at least one side of the first rectangular surface.

8. 8. The eraser product according to claim 7, wherein the sleeve is expandable and has four second rectangular faces connected to each other via four sides constituting the first rectangular face.

9. The eraser product of claim 7, wherein the sleeve is waterproof.

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