MXPA00008410A - Eraser - Google Patents

Abstract

An eraser is constituted by an elastic material containing a rubber component or a resin component, and a skeleton structure for reinforcing the elastic material, and the skeleton structure is made from a porous structural material such as from an organic polymer that is broken when rubbed. Void portions in the porous structural material of the skeleton structure contain the elastic material of the eraser composition. Here, the skeleton portions of the skeleton structure may have an average thickness of 1 to 100 mu m, and the void portions may have an average pore size of 10 mu m to 3 mm. The eraser may have a surface hardness of 50 to 80, and also a sticking strength of 1.5 to 20 (kgf).

Description

DRAFT BACKGROUND OF THE INVENTION The present invention relates to an eraser and, more particularly, relates to a eraser that can be used with a light pressure, less susceptible to fracture, is superior in its property of collecting waste and has an excellent erasing capacity. A eraser (rubber eraser) for erasing manuscripts written with a writing tool, such as a pencil, is composed of an elastic material of a eraser composition comprising rubber components or resin components such as rubbers, thermoplastic elastomers and plastics and additive agents such as polishing and loading materials. In general, with respect to the characteristics that are required of a draft, the following are listed: the erasure property and the pressure during use; however, in recent years, the form of the waste from the draft and its waste collection property (which combines the property of forming waste from the draft) have become important factors. These performances are determined mainly by the hardness of the elastic material of a eraser composition that constitutes the main body of a eraser. In general, the softer the material 52/85 elastic, the erasure property is better and the waste collection property is better; in contrast, while the elastic material becomes softer, the pressure when used becomes stronger, and is susceptible to breakage due to repeated use and use at higher pressure. The hardness of the main body of the eraser can be controlled by adjusting factors such as the type, viscosity and molecular weight of the rubber components and the resin components, the type and the composite ratio of plasticizers and softeners and the type and proportion composed of additive agents , such as for example polishing agents, etc., as well as by adjusting manufacturing conditions. In this way, taking into account the trends mentioned above, manufacturers determine the hardness of an eraser by adjusting the composition and manufacturing conditions. Therefore, in conventional drafts, it has not been possible to achieve the best states in all the properties, among which are: the property of erasure, the property of collecting eraser waste, the pressure during use, the property of resistance to fracture, (property of resistance to rupture), etc. and the specifications are determined taking into account the balance of these characteristics so that no problems arise in practical use.

Here, Japanese Unexamined Patent Publication No. 8-258493 proposes a draft material composed of a base material of eraser that includes a vinyl chloride resin, a plasticizer and a filler, and a porous material of the auto type. abrasion. In accordance with this invention, it is possible to improve the strength without deteriorating the erase property, and to provide an eraser with high strength. However, Japanese Unexamined Patent Publication No. 8-258493 defines that the porous material of the self-abrasion type is a composite material consisting of layers made of layers of adhesive which are continuous layers having a structure similar to an adhesive material. pencil center and discontinuous layers composed of an inorganic constituent material, such as boron nitride, talc and mica, which does not contribute to adhesion to the interfaces. Therefore, this invention has a mechanism in which the inorganic constituent material, such as boron nitride, talc and mica, combined with the adhesive, is allowed to crumble finely as a pencil center due to friction, etc. against paper, and erase manuscripts on paper, in combination with the base draft material. Therefore, since the draft of Japanese Patent Laid-Open Publication No. 8-258493 uses the porous material that contains the inorganic constituent material, has an extreme reduction in elasticity compared to conventional erasers, although it has improved strength compared to conventional erasers; in this way, the reduced elasticity damages the erasure property that must be inherently exerted by the base eraser material. Moreover, the extreme reduction in elasticity causes an unusual pressure compared to conventional erasers, failing to provide good pressure during use. Moreover, it is necessary that the draft not only be less susceptible to the fracture at the time of erasing manuscripts, but that it generates continuous eraser residues in a form collected after deletion; however, since the inorganic material other than the base rubber material is used as the porous material, it is difficult to generalize sufficiently collected eraser residues.

SUMMARY OF THE INVENTION As a result of in-depth studies to achieve the aforementioned objectives, the inventors have found that when an elastic material of a eraser composition containing at least one rubber component or a resin component is reinforced by means of a skeleton structure from which the skeleton portions on the surface of an eraser are separated when rubbed, it is possible to obtain an eraser which is superior in the property of collecting waste and in the erasing property, which has a Good pressure during use and that is less susceptible to fracture with high strength. The present invention relates to an eraser that is provided with an elastic material of a eraser composition containing at least either a rubber component or a resin component, and a skeleton structure containing the elastic material, of which Skeleton portions on the abrasion surface of the elastic material are disconnected and separated with abrasion from the elastic material when rubbed. In a preferred embodiment of the present invention, the skeleton structure is constituted by a porous structural material, in particular, a porous structural material of an organic polymer, which breaks when rubbed, and this skeleton structure and an elastic material made of a conventionally known erasing composition are combined to form an eraser; in this way, it is possible to obtain a draft that is superior in the waste collection property and in the erasure property, which has good pressure during use and which is less susceptible to fracture with high resistance. In another preferred embodiment of the present invention, the eraser is composed of a porous structural material that breaks when rubbed. In yet another preferred embodiment of the present invention, the eraser has a composition wherein the porous structural material of the skeleton structure is composed of an organic polymer. In another preferred embodiment of the present invention, the skeleton has a continuous structure. Therefore, the eraser in the preferred embodiment of the present invention is allowed to receive a load applied at the time of erasing by means of its entire composite body, i.e. between its elastic material of a eraser composition and the skeleton structure. which regulates an extreme elastic deformation of the elastic material, that is, in particular, a porous structural material, for example an organic polymer. Therefore, the eraser of the present invention has a high strength, and is superior in the property of resistance to rupture with high resistance. For this reason, the eraser is less susceptible to breakage even in the case of repeated use and use with a high load. Thus, in the eraser of the present invention, even if the elastic material of the eraser composition becomes softer, with less hardness than the elastic material of a conventional eraser composition, the eraser strength in its entirety is still improved, the upper elasticity thereof remains still high and the property of resistance to rupture thereof is still higher, and the Eraser is consequently less susceptible to breakage during use. In other words, in the present invention, the eraser is allowed to have a high hardness and a low resistance to adhesion so that it becomes superior in strength and elasticity. Moreover, the aforementioned skeleton structure, ie, especially the porous structural material, in particular the porous structural material of an organic polymer, regulates the excessive elastic deformation in the elastic material of the eraser composition so that the eraser in its Totality is provided with high elasticity; however, it does not provide adverse effects on the viscoelasticity that the erasing composition inherently possesses, thereby allowing the elastic material of the erasing composition to exert its inherent viscoelasticity. Therefore, even if the elastic material of the eraser composition becomes softer with less hardness than the elastic material of a conventional eraser composition, the resistance of the eraser, integrally, is still improved, the elasticity The upper part of it is still held high and it is possible to improve the waste collection property due to the softness of the elastic material which is the erasing composition. In other words, the eraser residues generated by the eraser of the present invention are continuous, and are formed in a collected manner; this makes it possible to easily remove the waste from the eraser, and is preferable from the point of view of the disposal of eraser waste. Moreover, when compared with conventional erasers, the eraser of the present invention can be used with a very light pressure at the time of erasing, and is superior to the pressure during use. This is probably because, when the skeleton structure, i.e., in particular, the porous structural material of an organic polymer, is exposed to the surface of the eraser together with the elastic material of the eraser composition, the skeleton structure, i.e. , in particular, the porous structural material of an organic polymer reduces friction against the surface of the paper, while the elastic material of the erasing composition is allowed to exert its inherent erasing property, so that it is possible to reduce a load imposed on it. the user of the draft. Moreover, since the draft has a low resistance to adhesion, requires less force to cause abrasion (ie, a force required at the time of erasing), thereby providing light pressure at the time of erasing and subsequent good pressure during use. Moreover, since the porous structural material is used as a skeleton structure, the superior resiliency and resistance prevents the eraser from flexing unnecessarily during use, thereby providing a smooth erasing process with light pressure. Therefore, the arrangement in which the elastic material of the eraser composition becomes softer with less hardness, compared to the elastic material of the conventional eraser composition, makes it possible to provide light and soft pressure at the time of erasing. Moreover, since the elastic material of the eraser composition is made softer than the elastic material of the conventional eraser composition, it is possible to provide a superior erasing property. Here, the skeleton structure, that is, in particular, the porous structural material of an organic polymer, as it is, is allowed to exert an erasing performance, thereby enabling it to further improve the erasure property. In the case where the elastic material of the eraser composition is made softer with less hardness Compared with the conventional eraser, the abrasion of the elastic material of the eraser composition is accelerated compared to the conventional eraser, with the result that the possibility can be reduced where the carbon coming from a pencil, etc., which adheres to the eraser paper, stick to the main body of the eraser and darken the eraser. In the case of the aforementioned skeleton structure, that is, in particular, the porous structural material of an organic polymer, at the time of a rubbing process with the eraser, a deformation applied on the elastic material of the eraser composition, as it is, it is exerted as a force to separate the skeleton portions on the eraser surface of the skeleton structure, i.e., a force to break the skeleton portions, particularly, in the case of the porous structural material. Consequently, the eraser of the present invention exerts its erasing property by abrading the elastic material of the eraser composition, while the skeleton portions are separated or broken, and the eraser residues of the eraser composition are separated and collected while taking the erasers. fragments of the skeleton portions broken and isolated. For this reason, draft waste, which includes fragments ofthe skeleton portions of the skeleton structure and the elastic material of the eraser composition that has been collected are generated and no eraser residues consisting of only skeleton portions are generated. Moreover, in the draft of the present invention, during the erasing process, the abrasion face of the elastic material and the separating face of the skeleton structure (the breaking face of the porous structural material) are made to coincide with each other, or they become virtually coincident with each other; in this way, after the skeletal portions of the porous structural material have been separated or broken, and detached, any of the separate pieces (broken pieces) of the skeletal portions of the porous structural material remaining in the main eraser body they are hardly allowed to rise from the surface of the eraser or to form holes after they have been removed. When compared to the conventional eraser, the draft of the present invention generates eraser residues in a collected form without dispersing; in this way, it has excellent functions and effects in which the eraser is superior in the property of collecting waste, provides a smooth erasing process, and has good pressure during use. Moreover, since the eraser itself has an appropriate resistance, it is less 52/85 susceptible to damage and has a good property of resistance to rupture. It also has a good erase property. In the preferred embodiment wherein the porous structural material is used as the skeleton structure, the structural material preferably contains the cross-sectional conformation with virtually circular or virtually polygonal cells and, in particular, the porous structural material is that provided more preferably as a foam structure material. Moreover, still in another preferred embodiment of the present invention, the porous structural material is a mesh structural material, and most preferably, the porous structural material is a three-dimensional mesh structural material. The aim of the present invention is to provide an eraser having sufficient strength, which is less susceptible to fracture with a high strength, which is superior in its property to collect waste, which has an excellent erasing property and which can be used with good pressure BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is an electronic micrograph that 52/85 shows the surface of a draft of one embodiment of the present invention, which is enlarged 80 times. Figure 2 is a schematic drawing in which the micrograph of Figure 1 has been redrawn for convenience of explanation. Figure 3 is an electron micrograph showing the surface of a skeleton structure that constitutes the eraser of Figure 1, which is enlarged 200 times. Figure 4 is a schematic drawing in which the micrograph of Figure 3 has been redrawn for convenience of explanation. Figure 5 is an electron micrograph showing the surface of a draft residue of the eraser of Figure 1, which is enlarged 200 times. Figure 6 is an electron micrograph showing the surface of an eraser of another embodiment of the present invention that is enlarged 60 times. Figure 7 is a graph showing the relationship between curing temperature, surface hardness and adhesion strength.

DESCRIPTION OF THE PREFERRED MODALITY Referring to the Figures, the following description will explain the modalities of the present 52/85 invention. As described in the foregoing, Figure 1 is an electron micrograph showing the surface of a draft of one embodiment of the present invention, which is enlarged 80 times. Figure 2 is a schematic drawing in which the micrograph of Figure 1 has been redrawn with guide lines and reference numbers for convenience of explanation. Figure 3 is an electron micrograph showing the surface of a skeleton structure that constitutes the eraser of Figure 1, which is enlarged 200 times. Figure 4 is a schematic drawing in which the micrograph of Figure 3 has been redrawn with guide lines and reference numbers, for convenience of explanation. Figure 5 is an electron micrograph showing the surface of a draft residue of the eraser of Figure 1, which is enlarged 200 times. Figure 6 is an electron micrograph showing the surface of an eraser of another embodiment of the present invention that is enlarged 60 times. Here, the microscopic electron micrographs of the present invention were taken using an "ERA-8000" (manufactured by ELIONIX INC.). As illustrated in Figure 1 and Figure 2, an eraser 1 is composed of a porous structural material that is a skeleton structure 2. Here, this skeleton structure 2 is composed of a material 52/85 structural porous of an organic polymer but may be composed of substances other than the organic polymer. In addition, the skeleton structure 2 contains an elastic material 3 of a eraser composition containing a rubber component or a resin component. Here, in one embodiment of the skeleton structure of the present embodiment, a skeleton portion 2a, which has a greater stiffness compared to the elastic material 3 of the eraser composition, is composed of a foam structural material that serves as a structural material that has virtually polygonal or virtually circular cells when viewed in cross section. The reference number 2b represents an empty portion of the skeleton structure surrounded by the skeleton portion 2a. Moreover, the reference number 4 represents draft waste, the reference number represents broken fragments of the skeleton structure and the reference number 6 is an elastic material of the eraser residue. As described above, in the draft of the present embodiment, the empty portion 2b of the skeleton structure 2 contains the elastic material 3 of the eraser composition containing the rubber component or the resin component, as illustrated in FIG. Figure 3 and Figure 4. Therefore, as the member 52/85 elastic 3 of the eraser composition contains the rubber component or the resin component, and since the backbone structure 2 is the porous structural material of an organic polymer, the empty portion 2b of the backbone structure 2 is filled with the material elastic 3 of the rubber composition containing the rubber component or the resin component. The skeleton structure 2 serves as the skeleton structure for reinforcing the elastic material 3 and allows its skeleton portion 2a to break when rubbed. In other words, with respect to the skeleton structure 2, the porous structural material is adopted, which allows the skeleton portion 2a to break when rubbed while reinforcing the elastic material 3. With respect to the skeleton structure 2 of the porous structural material, although not particularly limited, the average thickness of the skeleton portion 2a may be set at, for example, 1 to 100 μm (and more preferably, 10 to 50 μm). Moreover, although not particularly limited, the average pore diameter of the empty portion 2b of the skeleton structure 2 can be set at, for example, 10 μm to 3 mm (and more preferably, 20 μm to 1 mm ). Moreover, with respect to the skeleton structure 2 of the porous structural material, although without 52/85 be particularly limited, the vacuum index (pore index) is set at, for example, not less than 60%, preferably, not less than 80% and more preferably, not less than 90% (eg, 90) to 99.8%). In particular, when the pore index is set at not less than 90%, the thickness of the skeleton portion becomes smaller, making the porous structural material susceptible to breaking when rubbed, also making the abrasion face of the elastic material and the separating face of the skeleton structure coinciding with each other, or virtually coinciding with each other. Moreover, in the skeletal structure of the porous structural material, the filling rate of the elastic material of the erasing composition with respect to the entire volume of the empty portions in the porous structural material is not particularly limited. However, the filling index is preferably set in the range of not less than 50% to less than 100%. This is because, when the fill rate is less than 50%, there is degradation in the collection property of the draft waste, the erasure property and the pressure during use. Although the draft has the filling rate of 100%, the draft still has sufficient resistance, is less susceptible to breaking with high resistance, is superior in its waste collection property, has 52/85 an excellent erase property and can be used with good pressure, compared to the conventional eraser; however, setting the filling index to less than 100%, more preferably from 80 to 60% and most preferably, to 70%, it is possible to increase the abrasion rate of the eraser surface at the time of erasing and consequently, increase the deletion index. Here, with respect to the erasers wherein the erasure rates of the elastic material of the eraser composition with respect to the skeleton structure were respectively set at 100% and 70% (where the other conditions were the same), the index of erasure (%) and abrasion index (%) were measured respectively. The results showed that, in the case of the 100% fill index, the erasure index (%) and the abrasion index (%) of the draft were 97.6% and 11.4%, respectively, and that, in the case of the filling index of 70%, the respective percentages were 98.8% and 16.3% that showed an improved erase rate and abrasion rate. Here, the erasure index and the abrasion index were measured according to the following conditions: The erasure index was measured in accordance with JIS S 6050. The abrasion index was measured by the following method. First, the samples were processed in a column conformation that has a diameter of 12 ± 1 52/85 mm (11 to 13 mm) and a thickness of 10 ± 1 mm (9 to 11 mm), and the weight of this was measured. This was then linked to an erase tester described in JIS S 6050 (however, in the JIS S6050 erase index, since the thickness is 5 mm, the container section was modified to accept the 12 mm sample) . Against the test paper as described in JIS S 6050, this was rubbed with reciprocation 50 times with a load of 500 g. Then, the eraser residues generated by the rubbing process were removed, and the weight of the sample was measured. The amount of reduction due to the rubbing process was calculated in percentage with respect to the weight before the rubbing process. Moreover, the porous structural material of the skeleton structure is preferably set to have a tensile strength of no more than 3 kgf / cm2, and more preferably, no more than 2 kgf / cm2. The eraser having a porous structural material with a tensile strength exceeding 3 kgf / cm2 as its skeleton structure, causes its skeletal portion to separate or break with difficulty with the abrasion of the elastic material of the eraser composition at the moment of deletion. The value of the tensile strength was measured in accordance with JIS K 6402. Here, the thickness of the sample was 10 mm, the dumbbell had shape # 2 and the tension speed was 300 mm / min. 52/85 Moreover, the porous structural material is preferably fixed so that it has an extension of not more than 500%, and more preferably, of not more than 100%. The porous structural material having an extension exceeding 500% does not allow the abrasion face of the elastic material and the separating face of the skeleton structure to coincide with each other during the erasing process, allowing the porous structural material of the structure Skeleton is lifted off the abrasion face, and causes adverse effects on the outer appearance. The extension value was measured in accordance with JIS K 6402. Here, the thickness of the sample was 10 mm, the dumbbell had a shape # 2 and the tension speed was 300 mm / min. Moreover, the porous structural material is preferably fixed so that it has a repulsive compression force of not less than 0.2 kgf and more preferably of not less than 0.7 kgf. The repulsive compression force of less than 0.2 kgf causes insufficient rigidity in the overall eraser, resulting in difficulty in providing high elasticity. The repulsive compression force was provided as a value that was measured by pressing a disc having a diameter of 15.2 mm on a sample having a thickness of 10 mm and compressing the sample by 5 mm at a speed of 7 mm / min. 52/85 From this, the porous structural material that is preferred in this embodiment is an eraser having a tensile strength of not more than 3 kgf / cm2, an extension of not more than 500% and a compressive repulsive force of no less than 0.2 kgf. With respect to the organic polymer of the skeleton structure 2 of the present embodiment, a resin with melamine base was used. Moreover, the elastic material 3 was reinforced by a eraser composition containing a resin based on vinyl chloride and a plasticizer. The eraser of the present invention, which is formed as described above, has a sufficient strength and elasticity, is superior in the property of resistance to rupture, is superior in its property of collecting waste (see Figure 5), has an excellent Erase property and can be used with good pressure, compared to conventional eraser. Here, the draft of the present invention is not limited by the aforementioned modality. With respect to the porous structural material, which is not limited in particular, any material can be used as long as it has a skeletal structure having a skeletal portion and empty portions. With regard to this porous structural material, for example, it can 52/85 a structural material having virtually circular or virtually polygonal cells, as shown in Figures 1 to 4, or a mesh structural material. Here, the skeleton portion is preferably fixed to form a skeleton structure having sufficient hardness in a solid state; however, any material can be used as long as it has a skeleton structure that can reinforce the elastic material. For example, the porous structural material can be melted by heat, has its deformed pore shape upon dissolution (being compatible with) with the component in the eraser composition, becomes thinner in the skeleton, or forms a semi-compatible state with the eraser composition . In the present invention, the shape of the skeleton portion and the shape of the empty portions are not particularly limited. As described above, the skeleton structure can be any structure that serves as the skeleton structure to reinforce the elastic material and also allows the skeleton portion to break when rubbed. In any case, any material that can restrict the deformation of the elastic material of the eraser composition contained in the empty portions of the porous structural material in a two-dimensional manner can be suitable. 52/85 three-dimensional, and reduce the deformation to a predetermined limitation. The structural material containing virtually polygonal or virtually circular cells is not particularly limited and any structural material can be used insofar as it contains cells having a virtually polygonal or virtually circular conformation; and, for example, a structural material having virtually circular cells such as the foamed structural material can be used. (sponge-shaped structural material) or a structural material that has virtually polygonal cells such as the honeycomb structural material. Here, the foamed structural material is preferably used. In the case of foamed structural material, the pore index of less than 90% allows its pores to have a spherical or virtually spherical conformation; however, the pore index of not less than 90% allows its pores to form a conformation similar to a three-dimensional mesh structure. In the structural material (in particular, foamed structural material) which contains virtually polygonal or circular cells, the state of the pores is not particularly limited, and any of the pores communicated or pores may be used. 52/85 independent and communicated pores (open cells) and independent pores (closed cells) can be mixed together. However, taking into consideration that the porous structural material of the skeleton material is filled with the elastic material of the eraser composition, the reported pores are more preferred. Here, with respect to the reported pores, any virtually communicated pores can be used, and in the present invention, those that have a reported pore index of not less than 90% (i.e., the independent pore index is less than 10%. ) with respect to all pores, they are considered to be pores communicated. Moreover, with respect to the mesh structural material, a flat mesh structural material (ie, a two dimensional mesh structural material) can be used; however, a stereoscopic mesh structural material (ie, a three-dimensional mesh structural material) is most preferably used. The structural material of stereoscopic mesh makes it possible to improve the resistance and viscoelasticity of the eraser. Here, in the present invention, the porous structural material of the skeleton structure and the elastic material of the eraser composition can be integrated into a composite material. When the skeleton structure and the elastic material are integrated into the 52/85 composite material, it is possible to provide superior hardness, increase elasticity and thus improve the property of resistance to rupture, and smooth the eraser surface after use, thereby making the abrasion face of the elastic material and the separating face of the Skeleton structure are coincident with each other. Of course, this makes it possible to improve the pressure during use, the waste collection property of the eraser and the erasure property. The skeleton structure of the present invention is not particularly limited; however, it is important that the skeleton structure contains the elastic material of the eraser composition and that it allows its skeletal portion on the abrasion surface of the elastic material to separate and break together with the abrasion of the elastic material of the composition Eraser at the moment of deletion. From this point of view, the skeleton structure is preferably formed by the porous structural material. The porous structural material is not particularly limited, any porous structural material can be used as long as it contains elastic material of the erasing composition and which allows its skeletal portion on the abrasion surface of the elastic material to separate and break together with the abrasion of the 52/85 Elastic material of the eraser composition at the time of erasing. For example, a porous structural material composed of an organic polymer or an inorganic polymer can be used. With respect to the organic polymer, it can be used either alone or in combinations of two or more of them. Examples of organic polymers include resins (e.g., thermoset resins, thermoplastic resins, etc.), rubbers, fibers, etc. Of course in the case of the structural material having a porous structural material with virtually polygonal or virtually circular cells, resins and rubbers are used and, in the case of the mesh structural material, fibers are used. Examples of resin include various resins, including: thermosetting resins, such as melamine resins, epoxy resins, urethane resins, urea resins and phenolic resins, and thermoplastic resins such as styrene-based resins, among those included: polystyrene, ester-based resins, including polyester, acrylic resins including polyacrylate, olefin resins including vinyl chloride and polyethylene based resins, including polyvinyl chloride and elastomers. Examples of rubbers include natural rubbers, styrene-butadiene rubber, nitrile-butadiene rubber, etc. Moreover, they can also be used 52/85 highly molecular natural porous materials, for example, the sponge. Examples of fibers include natural fibers such as cotton, silk and hemp, and synthetic fibers such as: cellulose fibers, ester-based fibers, acrylic fibers and amide-based fibers. In particular, in the structural material containing the cross-sectional shape with virtually polygonal or virtually circular cells, when a melamine-based resin is used as the organic polymer, it is possible to form a foamed structural material or a stereoscopic mesh structural material. which has a thin thickness of the skeleton portion, a small pore size and empty portions and a high pore index. For this reason, the structure is easily broken when rubbed, and it is possible to prevent broken fragments of the skeleton portion from appearing on the surface of the eraser main body, such as filaments, after use and also causing the abrasion face of the elastic material and the separating face of the porous structural material are coincident with each other, or virtually coincident with each other. Of course, even in the case where a material other than a melamine-based resin such as the organic polymer is used, controlling the thickness of the skeleton portion, the pore diameter of the empty portions and the pore index, it's possible 52/85 providing a structure that breaks easily when rubbed, and allows the abrasion face of the elastic material and the separation face of porous structural material to be coincident with each other, or virtually coincident with each other on the surface of the eraser after use. The elastic material of the eraser composition is not particularly limited and a composition which is impregnated and absorbed into the porous structural material of the skeleton structure can preferably be used. More specifically, conventionally known compositions, such as plastic-based, rubber-based or elastomer-based compositions, used as the eraser base material, can be adopted. With regard to the plastic-based eraser composition, for example, various resins can be used, such as: thermoplastic resins, thermoset resins, UV hardened resins, electron beam hardened resins, multi-liquid hardened resins (two-hardened resins) liquids, etc.), resins hardened by catalyst and ester fiber element. Among these resins, thermoplastic resins are most often used. These resins can be applied in various conditions, such as, for example, a state dissolved in a solvent, a state dispersed in a solvent or in an emulsified state. More specifically, vinyl chloride-based resins, such as polyvinyl chloride, vinyl acetate-vinyl chloride-based resins, and vinyl acetate-ethylene-vinyl chloride-based resins, can be used. and vinyl acetate-based resins such as vinyl acetate-ethylene resins. In particular, a sol state composition between the vinyl chloride base resins and a plasticizer is most preferably used as the base material. This is because the composition in the sol state between the vinyl chloride base resin and the plasticizer has sufficient fluidity to be impregnated and absorbed into the porous structural material of the skeleton structure, and because this is cured easily in the empty portions in the porous structural material of the skeleton structure. With respect to the plasticizer, any known plasticizer can be used as long as it can plasticize the contained thermoplastic resin, i.e., in particular, the polyvinyl chloride. With regard to the plasticizer, italic plasticizers, such as, for example, dioctylphthalate and diheptyl phthalate, are preferably used.

In addition to these, the following additive agents can be used: an abrasive material, a filler such as, for example, calcium carbonate, magnesium carbonate, silica, talc, clay, diatomaceous earth, quartz powder, alumina, alumina silicate and mica, metallic soap, a stabilizer with zinc-barium base, stabilizers with magnesium-zinc base and calcium-zinc base, a dye, perfume, a surfactant, glycols, etc. With respect to the dye, known pigments can be used, for example: organic pigments, inorganic pigments and fluorescent pigments and known dyes. With respect to the eraser composition with plastic base, the index of the resin (in particular, vinyl chloride resin) is not particularly limited; and for example, the index is set at 10 to 80% by weight, and more preferably, 20 to 70% by weight, with respect to the entire eraser composition. The plasticizer index is set at, for example, 10 to 80% by weight, and more preferably 20 to 70% by weight, with respect to the entire eraser composition. Moreover, the index of the filler material is set, for example, from 0 to 70% by weight, and more preferably, from 5 to 40% by weight. The rubber-based eraser composition may include, for example, a rubber component, a factice (rubber substitute), a softener, sulfur, a vulcanization accelerator, a filler, an anti-aging agent, a dye and perfume. The eraser-based eraser composition can include, for example, a thermoplastic elastomer, a softener, a filler, a stabilizer, a colorant and perfume. Moreover, in the present invention, a color change pigment component (pressure sensitive color change pigment component) contained in a microcapsule sensitive to pressure that is broken by frictional force, or a component of color change pigment (pigment component for heat sensitive color change) that changes colors by frictional heat. Additionally, in the draft of the present invention, an arrangement may be adopted wherein at least either the porous structural material or the elastic material of the eraser composition is colored. In particular, in the case where the porous structural material and the elastic material of the eraser composition are colored in respectively different colors, not only the eraser main body, but also the eraser residues have a mixed color so that it is possible to provide an interesting color appearance, and 52/85 it is also possible to allow the user to observe and recognize the fact that the eraser is formed in such a way that the structure of the skeleton is carried in the eraser waste as desired, through its physical properties. In addition, the skeleton structure can be constituted by a plurality of blocks of porous structural materials. For example, these porous structural block materials have at least any of the spherical, rectangular conformations and plate conformations. In particular, in the case where the eraser is formed using a plurality of blocks of porous structural materials such as the skeleton structure, since each block is independent, a joint between the blocks serves as a bending portion where the eraser can bend along this joint, if necessary. Conventionally, when using a draft, in order to achieve a better deletion process, the user has sometimes cut the eraser with a knife, etc. to produce new corners; however, the present invention eliminates this task and provides a convenient use where a connection between the aforementioned blocks can be simply folded and cut with the hands to produce new corners, or to provide, for example, a piece 52/85 small of the eraser, if necessary. Here, in the case of the eraser having the skeleton structure of the block type, in order to provide an easy fold in a joint between the blocks, the components in the eraser composition can be adjusted, the degree of polymerization of the synthetic resin can be adjusted , or the gelation temperature can be adjusted. These methods can be adopted depending on the type of the main component of the eraser, such as resins based on elastomer, vinyl chloride based or other types of resins. For example, in the case of the elastomer-based eraser, an oil component can be increased as a component of the eraser composition, or the degree of polymerization of the synthetic resin can be adjusted. Furthermore, for example, in the case of the vinyl chloride-based eraser composition, the gelation temperature of the eraser composition contained in the backbone structure can preferably be set in a comparatively low temperature range, for example , from 100 to 110 ° C, more preferably from 105 to 108 ° C and most preferably, in about 107 ° C. Here, the aforementioned blocks are not particularly limited; however, it is preferred to set the diameter or side length thereof to not less than 5 mm. Moreover, the conformations of the blocks 52/85 they can be selected from several forms besides the spherical, rectangular and plate shape. The drafts of the present invention, described in the various embodiments, can be effectively applied to, for example, a pencil of the pen type (knocking-type) with a eraser attached at the end thereof and an eraser of the electrical type with a eraser attached to a housing for eraser, as well as to a draft of the type of feeding that has a feeding mechanism, a pencil-type eraser, that is, the mine of a mechanical pencil is the eraser itself and a draft attached in a separable way in a cylinder. In these cases, the draft of the present invention is applied, in particular, as an exchange draft (exchange rubber draft). The method of making the eraser of the present invention is not particularly limited. For example, a pre-cure eraser composition and a component of a structural material to form a skeleton structure are mixed together so that the elastic pre-cure material of the eraser composition is impregnated into the empty portions of the eraser. porous structural material, and this is then cured to provide a erasing composition. Here, a process where the material is placed in an eraser mold 52/85 Default can be carried out at any time in the preparation processes. A preferred method for making an eraser is explained below: a eraser composition containing at least one rubber component or a resin component is impregnated in a skeleton structure so that the eraser composition is absorbed into the empty portions in the skeleton structure, and the eraser composition is then cured. Furthermore, another method is explained below: a eraser composition containing at least either a pre-cured rubber component or a resin component is impregnated into a porous structural material so that the eraser composition is absorbed in the empty portions in the porous structural material, and the eraser composition is then cured. Here, in this method, after the eraser composition has been impregnated into the skeleton structure, i.e., in particular, the porous structural material, a compression process is preferably provided. In particular, a more preferred manufacturing method for an eraser includes the following steps: A eraser composition containing at least either a rubber component or a resin component is filled in a plate-shaped molding frame ( for example, a plate-shaped molding frame 52/85 with a bottom), and a porous structural material is placed in the molding frame so that it is impregnated, and this is then compressed with a thermal press to provide an eraser. Here, in order to standardize and increase the amount of impregnation of the eraser composition, the eraser composition is further impregnated into the porous structural material in which the eraser composition has been impregnated having been placed therein; This method is also effective. Moreover, another method that is preferred includes the following steps: The eraser composition containing at least one rubber component or a resin component is added to the skeleton structure under normal pressures, and the empty portions of the skeleton structure as voids absorb the eraser composition. In addition, in another applicable method, to the skeleton structure placed under a vacuum is added a eraser composition containing at least one rubber component or a resin component so that the empty portions of the skeleton structure are filled with the Eraser composition and the eraser composition is then cured. Additionally, a eraser composition is impregnated into a porous structural material of the skeleton structure having a size larger than a finished molded size, and this is compressed into a product 52/85 predetermined molding; in this way, this method is more preferred because the pore index and the content of the eraser composition can be adjusted even in the case where the same porous structural material is used, and because it is possible to adequately control the quality of the product. In another applicable manufacturing method, a eraser composition is preliminarily impregnated into the empty portions of a porous structural material, and this is then placed in a predetermined eraser mold where it is cured by applying heat, etc., to provide the product . With respect to the heat curing conditions, in the various manufacturing methods mentioned above, they are preferably set at a temperature range of 100 ° to 160 ° C for 10 to 50 minutes. Here, in the case where the erasing composition is impregnated into the porous structural material of the skeleton structure, if a synthetic thermoplastic resin such as, for example, an elastomer-based resin, is contained in the composition, the eraser composition sometimes it reaches a high viscosity even in a hot molten state; and in this case, in order to improve the impregnated property, the following methods can be used: For example, in this 52/85 method, after the eraser composition has been dissolved in a solvent and impregnated in the skeleton structure of the porous structural material, the solvent is evaporated. Moreover, after the erasing composition has been emulsified by means of a dispersant, and impregnated therein, the dispersant can be removed by evaporation, etc. In addition, after the eraser composition has been impregnated into the skeleton structure of the porous structural material in a low liquid molecular state, the monomer of the eraser composition can be polymerized. Moreover, in the case of the mesh structural material, the same method method can be used to process the porous structural material containing virtually polygonal or virtually circular cells, or another method can be used wherein: a pre-cure eraser composition in a sun state, etc. it is injected into a predetermined eraser mold, and to this fiber is added and mixed so that the elastic material of the eraser composition is contained in empty portions between the fiber, and this is then cured by means of heat, etc., to provide the product. In making the eraser of the present invention using the above-mentioned methods, for example, a eraser composition in a sun state, having a 52/85 viscosity in the range of 100 to 20,000 mPa (more preferably, 800 to 7,000 mPa) in accordance with the measurement conditions of, for example, a temperature of 20 ° C, the application of a type B viscometer and the speed of rotation of 6 rpm are preferably used, and in particular, a boring composition in the sol state made from polyvinyl chloride resin is more preferably used. This is because the erasing composition having a viscosity in this range exerts a preferable fluidity at normal temperatures, so that it is impregnated and absorbed in the empty portions of the porous structural material of the skeleton structure, and is suitably filled in the portions empty of the porous structural material of the skeleton structure and easily cured. Additionally, even a stripping composition having a high viscosity exceeding 20,000 mPa can be used and impregnated, with reduced viscosity by heat or under reduced pressure. The surface hardness of the eraser of the present invention is not particularly limited; and, for example, it is set in the range of 50 to 80, and more preferably, 60 to 70. In addition, the tack resistance of the eraser is not particularly limited; and for example, it is set at the interval of 1.5 to 52/85 (kgf), and more preferably, 2 to 5 (kgf). Here, the surface hardness is measured in accordance with the JIS S 6050. Furthermore, the tack resistance is measured as follows: A sample is machined into a disc shape having a thickness of 5 mm and a diameter of 10 mm, and a rod having a diameter of 4.4 mm is pressed in the center of the disc at a speed of 7 mm / min, and a load at the moment when the portion pressed by the rod has been broken, is measured as the resistance to stickiness. In the case of the eraser of the present invention, even when the surface hardness is the same, the tack resistance can be reduced when compared to the conventional eraser. For this reason, it is superior in strength and viscoelasticity, and even if the elastic material of the eraser composition is soft, the eraser is less susceptible to fracture with hardness and has a good pressure when used. As compared to conventional erasers having the same eraser composition, produced through the same manufacturing conditions (curing temperature, etc.), the eraser of the present invention has a lower tack resistance. In other words, the formation of the skeleton structure makes the elastic material of the composition 52/85 softer eraser even in the case of the same manufacturing conditions. Thus, although the present invention only adds porous structural material of the skeleton structure to the conventional eraser composition without changing manufacturing conditions, it makes it possible to provide an eraser that is superior in strength and elasticity, has a good property of waste collection, is superior in pressure when used and exerts a high erase property. The coefficient of friction of the eraser of the present invention is preferably set at no more than 0.8. This is because the eraser of the present invention having a coefficient of friction of no more than 0.8 requires slight pressure when erasing. Moreover, the draft wear index is set, preferably, at no more than 1%. This is because the eraser of the present invention having a wear index of not less than 1% is less susceptible to staining its surface upon erasure, and can carry out an erasing process easily. As described above, it is more preferable that the eraser of the present invention has a surface hardness of 50 to 80, a tack resistance of 1.5 to 20 (kgf), a coefficient of friction of no more than 0.8 and a Wear rate of not less than 1%. 52/85 Additionally, the eraser of the present invention is constituted by a structural body having a skeleton structure and an elastic material of a eraser composition. Therefore, the present invention not only includes a draft wherein the skeleton structure is contained in all the elastic material of the eraser composition, but also includes another eraser wherein the skeleton structure is contained only in a portion of the structure. same Moreover, as shown in Figure 6, an eraser 1 may be included wherein the elastic material 3 is contained only in a portion of a skeleton structure 2.

EXAMPLES (Draft Material) In the following Examples and Comparative Examples, a sol composition of polyvinyl chloride having the following composition was used as a draft material (eraser base material): Sol composition of polyvinyl chloride. * Resin (polyvinyl chloride, trade name "ZEST P21" manufactured by SHIN DAI-ICHI VINYL CORPORATION). : 32 parts by weight. * Plasticizer (dioctylphthalate, name 52/85 commercial "SANSOCIZER DOP" manufactured by New Japan Chemical Co., Ltd.): 50 parts by weight. * Loading material (heavy calcium carbonate, manufactured by BIHORU FUNKA KOGYO Co., Ltd.): 17 parts by weight. * Stabilizer (material with magnesium-zinc base, trade name "R-23L" manufactured by TOKYO FINE CHEMICAL CO., Ltd.): 1 part by weight. (Example 1) The foam material (0.15 parts by weight) of a melamine-based resin was impregnated with the sol composition of polyvinyl chloride mentioned above (20 parts by weight), and this was then heated to 130 ° C during 20 minutes to prepare a draft. The foam material of a melamine-based resin is manufactured by BASF AG under the trade name of Basotect. (Example 2) The foam material (0.15 parts by weight) of a urethane-based resin was impregnated with the aforementioned polyvinyl chloride sol composition. (20 parts by weight), and this was then heated to 130 ° C for 20 minutes to prepare a draft. The foam material of a urethane-based resin is manufactured 52/85 by INOAC CORPORATION under the trade name of MF-50. (Example 3) The foam material (0.15 parts by weight) of an ethylene-based resin was impregnated with the aforementioned polyvinyl chloride sol composition. (20 parts by weight), and this was then heated to 130 ° C for 20 minutes, to prepare a draft. The foam material of an ethylene-based resin is manufactured by SANWA KAKO Co. , Ltd. with the trade name of OPCELL LC-300 # 3. (Example 4) The foam material (0.15 parts by weight) of a vinyl chloride base resin was impregnated with the aforementioned polyvinyl chloride sol composition (20 parts by weight), and this was then heated to 130 °. C for 20 minutes, to prepare a draft. (Example 5) The foam material (0.15 parts by weight) of nitrile-butadiene rubber (NBR foam) was impregnated with the sol composition of polyvinyl chloride mentioned above (20 parts by weight), and this was then heated to 130 ° C for 20 minutes, to prepare a draft. (Example 6) The felt fiber aggregate (0.15 parts by weight) of an ethylene-based resin is 52/85 impregnated with the sol composition of polyvinyl chloride mentioned above (20 parts by weight), and this was then heated at 130 ° C for 20 minutes, to prepare an eraser. The felt fiber aggregate is manufactured by TSUKASA FELT SHOJI Co. , Ltd. with the trade name of # 4000. (Example 7) The foam material (0.15 parts by weight) of a melamine-based resin was impregnated with the aforementioned polyvinyl chloride sol composition. (20 parts by weight), and this was then heated to 114 ° C for 20 minutes to prepare a draft. The foam material of a melamine-based resin is manufactured by BASF AG under the trade name of Basotect. (Comparative Example 1) Only the aforementioned polyvinyl chloride sol composition (20 parts by weight) was used, it was heated at 130 ° C for 20 minutes, to prepare a draft. (Evaluation) With respect to the drafts relating to Examples 1 to 6 and Comparative Example 1, the evaluation was made on the pressure exerted on the use and property of collecting eraser waste, based on the following test conditions. The results of the 52/85 evaluation are shown in Table 1.

Table 1 (Tests on pressure during use) Writings written with a pencil were erased, using the drafts relating to Examples 1 to 7 and the Comparative Example, and the pressure exerted on use was evaluated based on the following criteria: [Evaluation criteria of the pressure exerted in the use] T: The scripts can be erased very gently with light pressure. O: The scripts can be erased gently with light pressure. X: The writings can not be erased without applying a high force.

(Evidence on the waste collection property of eraser) After the aforementioned erasure tests, the waste collection property was evaluated 52/85 of draft based on the following criteria. In addition, after the deletion processes, the state of the eraser surface was observed.

[Evaluation criteria for the draft waste collection property] OR: Eraser waste was collected on the surface of the paper or on the surface of the eraser, and after the erasure process, the surface of the eraser is white. X: Eraser residue is hardly collected on the surface of the paper or on the surface of the eraser, and after the erasing process, the pencil carbon adheres to the surface of the eraser.

(Evaluation results) As shown in Table 1, although the drafts of Examples 1 to 7 have higher hardness, they can completely erase writings in a manner similar to sliding with slight pressure. Moreover, the eraser residues do not disperse, and are collected on the surface of the paper or on the surface of the eraser in a continuous manner. Moreover, although there is an increase in the abrasion loss of the elastic material, the pencil writings are sufficiently contained in the residues 52/85 of eraser, and the eraser surface is still white. In addition, during the erasing process, the skeletal portion of the porous structural material is broken and it is observed that while the eraser residues are captured in the fragments of the skeleton portion, they are separated in collected form. In contrast, the draft of Comparative Example 1 can not be erased without applying a higher force. In addition, eraser residues are scattered everywhere and are not collected on an ongoing basis. Moreover, after the erasing process, the surface of the eraser becomes black with carbon from the pencil attached to it. Furthermore, in the case of the erasers of Examples 1 to 7, even if they are rubbed against the paper surface with a high force, they do not break easily; however, the eraser of Comparative Example 1 is easily broken when rubbed against the paper surface with a higher force and, therefore, is lower in the property of resistance to breakage. Here, the composition of the elastic material of the eraser composition and the manufacturing conditions are the same between Examples 1 to 7 and Comparative Example 1. Examples 1 to 7 are only different from Comparative Example 1 in the porous structural material that is use in them. 52/85 Next, a pre-cured eraser of Example 1 using the foam material of the melamine-based resin and a pre-cured eraser of Comparative Example 1 that has no skeletal structure of the porous structural material were subjected to measurements to find the respective relationship between the curing temperature, the surface hardness and the tack resistance, and the results are shown in Table 2. Figure 7 is a graph showing the relationship between the curing temperature, the surface hardness and the resistance to stickiness. In Table 2, the results related to the draft of Example 1 are described in the column "with foam material" and those related to the draft of Comparative Example 1 are described in the column "without foam material". In Figure 7, • represents the tack resistance of the deletion related to Example 1; Or represents the tack resistance of the eraser related to Comparative Example 1; B represents the surface hardness of the eraser related to Example 1, and D represents the surface hardness of the eraser related to Comparative Example 1. Here, the hardness of the surface was measured in accordance with JIS S 6050. Furthermore, the resistance to the tackiness was measured as follows: A sample is machined in 52/85 a disc shape having a thickness of 5 mm and a diameter of 10 mm, and a rod having a diameter of 4.4 mm is pressed on the center of the disc at a speed of 7 mm / min, and a load at the time in which the portion pressed by the rod has been broken, was measured as the tack resistance. Here, the curing time was 20 minutes.

Table 2 From Table 2 and Figure 7, within a range of curing temperature of 110 to 130 ° C, the eraser of Example 1 has a superior surface hardness and also has a lower tack resistance than the eraser of Example Comparative 1. More specifically, the draft of Example 1 has a 52/85 surface hardness from 64 to 67 and a tack resistance from 1.63 to 3.26 (kgf). This is because, even if cured at the same curing temperature, during the same time as the eraser of Comparative Example 1, the eraser of Example 1 has a strength with sufficient hardness and, in contrast, also has a low degree of curing (degree of gelation), thereby indicating that the elastic material of the eraser composition is softer than that of Comparative Example 1. Therefore, when compared with the eraser of conventional Comparative Example 1, since the eraser of Example 1 it has a low degree of curing and a softer elastic material, it is by far superior in erasing property, and has a good property of eraser waste collection. These trends also apply to the drafts of Examples 2 to 7 mentioned above. Moreover, in fact, the eraser, which has a surface hardness of 64 to 67 and a tack resistance of 1.63 kgf to 3.26 (kgf), was superior in all factors, such as: strength, pressure during use , erasure property and draft waste collection property. The present invention relates to an eraser that is provided with an elastic material of a eraser composition containing at least one rubber component or a resin component, and a 52/85 skeleton structure containing the elastic material, from which the skeleton portions on the abrasion surface of the elastic material are disconnected and detached together with the abrasion of the elastic material when rubbed. In particular, in the draft of the present invention, the skeleton structure is constituted by a porous structural material that breaks due to abrasion. Moreover, in the draft of the present invention, the porous structural material of the skeleton structure is made of an organic polymer. Therefore, when compared to the conventional eraser, the eraser of the present invention has a sufficient strength so that it is less susceptible to fracture even after repeated use, erases with a slight pressure so that it is higher in pressure during the use, and it also has a superior erasure property. Moreover, the draft has a particularly noticeable effect in that the waste from the draft is generated in a continuously collected form, without being dispersed.

Claims (36)

1. CLAIMS: 1. A draft comprising: an elastic material of a eraser composition containing at least one rubber component or a resin component; and a skeleton structure containing the elastic material, from which the skeleton portions on the abrasion surface of the elastic material are detached and separated, during abrasion of the elastic material, by rubbing it.
2. 2. A eraser according to claim 1, wherein the skeleton structure is constituted by a porous structural material that melts when rubbed.
3. 3. A eraser according to claim 1, wherein the skeleton structure is continuous.
4. 4. A eraser according to claim 2, wherein the porous structural material is made from an organic polymer.
5. 5. A eraser according to claim 2, wherein the porous structural material has empty portions wherein the elastic material of the eraser composition is contained.
6. 6. A eraser according to claim 5, wherein the elastic material of the eraser composition has a filling index in a range of between 50% and less than 100%, with respect to the overall volume of the empty portions of the porous structural material.
7. A eraser according to claim 2, wherein the porous structural material of the skeleton structure and the elastic material of the eraser composition are integrated into a composite part.
8. 8. A eraser according to claim 1, wherein the skeleton portions of the skeleton structure have an average thickness of 1 to 100 μm.
9. 9. A eraser according to claim 1, wherein the empty portions of the skeleton structure have an average pore size of 10 μm to 3 mm.
10. 10. A eraser according to claim 2, wherein the porous structural material of the skeleton structure contains the cross-sectional shape with almost polygonal or quasi-circular cells.
11. 11. A eraser according to claim 2, wherein the porous structural material is a foamed structural material.
12. 12. A eraser according to claim 2, wherein the porous structural material is a mesh structural material.
13. 13. A eraser according to claim 11, wherein the porous structural material is a stereoscopic mesh structural material.
14. 14. A eraser according to claim 2, wherein the porous structural material has a tensile strength of not more than 3 kgf / cm2.
15. 15. A eraser according to claim 2, wherein the porous structural material has a stretch percentage of not more than 500%.
16. 16. A eraser according to claim 2, wherein the porous structural material has a repulsive force at compression of not less than 0.2 kgf.
17. 17. A eraser according to claim 2, wherein the porous structural material has a tensile strength of not more than 3 kgf / cm2, an extension percentage of not more than 500% and a compressive repulsive force of not less than 0.2 kgf.
18. 18. A eraser according to claim 1, wherein the eraser has a surface hardness of 50 to 80.
19. 19. A eraser according to claim 1, wherein the eraser has a tack resistance.

    1. 5 to 20 (kgf).
20. 20. A eraser according to claim 1, wherein the eraser has a coefficient of friction of no more than 0.8.
21. 21. A eraser according to claim 1, wherein the eraser has an abrasion index of not less than 1%. 52/85
22. 22. A draft comprising a surface hardness of 50 to 80, a tack resistance of 1.5 to 20 (kgf), a coefficient of friction of no more than 0.8 and an abrasion index of not less than 1%.
23. 23. A eraser according to claim 2, wherein at least the porous structural material or the elastic material of the eraser composition is colored.
24. 24. A eraser according to claim 2, wherein the skeleton structure is constituted by a plurality of blocks of porous structural materials.
25. 25. A eraser according to claim 24, wherein the blocks have at least one shape selected from the group consisting of: spherical, polygonal and plate shapes.
26. 26. A eraser according to claim 1, which is an interchangeable eraser that is used in at least one member selected from the group consisting of: a drawer of the feeder type, a draft of the pen type, a draft attached to one end of a mechanical pencil and an eraser of the electric type.
27. 27. A draft of the feeder type, to which the eraser according to claim 1 is attached.
28. 28. A draft of the pen type, to which the eraser is attached according to claim 1.
29. 29. A pen that has a portion of a cap 52/85 end, to which the eraser is attached according to claim 1.
30. 30. An electrical eraser having a eraser container, to which the eraser is attached according to claim 1.
31. 31. A method for manufacturing a eraser comprising the eraser steps of: impregnating an elastic material of a eraser composition containing at least one rubber component or a resin component in a skeleton structure, so that the empty portions in the skeleton structure absorb the eraser composition; and cure the eraser composition.
32. 32. A method for making an eraser according to claim 31, wherein the skeleton structure is a porous structural material.
33. A method for manufacturing an eraser according to claim 32, further comprising the steps of: after the porous structural material has been impregnated with the eraser composition, compress the material.
34. 34. A method for making an eraser according to claim 33, further comprising the steps of: 52/85 after filling a plate-shaped molding frame with the eraser composition containing at least one rubber component or a resin component, place the porous structural material in the molding frame, so that it is impregnated; and compress this with a thermal press.
35. 35. A method for making an eraser according to claim 31, further comprising the steps of: after the eraser composition containing at least one rubber component or a resin component is added to the low skeleton structure At normal pressures, the empty or hollow portions of the skeleton structure are allowed to absorb the eraser composition.
36. 36. A method for making a eraser comprising the steps of: adding to a skeleton structure, a eraser composition containing at least one rubber component or a resin component, with application of vacuum, so that the empty portions of the skeleton structure are filled with the eraser composition; and cure the eraser composition. 52/85