ERASER AND METHOD FOR MANUFACTURING THE SAME

Abstract: An eraser capable of erasing characters and the like written on paper with a ball-point pen, fountain pen, typewriter, word processor, color pencil or the like. The eraser has an integral structure composed of plural types of eraser pieces (20, 22, 24) having different hardnesses and an abrasive material (26), the eraser pieces and the abrasive material existing respectively in a particulately dispersed state. A method for manufacturing such eraser comprises steps of kneading plural types of major eraser materials which have been previously vulcanized and shaped at need with an abrasive material and vulcanizing and shaping the resulting mixture. These plural types of major eraser materials are such that erasers having different hardnesses can be produced if each of the major eraser materials is either vulcanized or heated and shaped alone and that particles of the major eraser materials exist independently from one another even if these materials are kneaded.

Description: This invention relates to an eraser, having the ability to erase characters and the like written by means of ball-point pen, fountain pen, typewriter, word processor, coloured pencils or the like, and to a method for manufacturing such an eraser. It is known to use an eraser comprising bulk material having an abrasive particulate material material, e.g. sand dispersed therein for erasing characters and the like written on paper by means of ball-point pen, fountain pen or the like. A conventional sand-containing eraser is manufactured by homogeneously mixing a factice (white factice), a plasticizer, and a mineral oil with a rubber or plastic bulk component. To this is added an abrasive material, having a particle size of about 150 mesh such as glass powder, energy, carborundum (black silicon carbide) or the like. The resulting admixture is is kneaded by means of rollers or the like, and the product thus kneaded is either vulcanised or heated and shaped. The structure of the shaped eraser is shown in Figure 2 wherein particles of an abrasive material 12 are dispersed and included in a homogeneous bulk eraser material 10. In said conventional sand-containing eraser, if the bulk eraser material 10 is a soft material, the eraser material does not present suitable stiffness to sustain particles of the abrasive material 12 as shown in Figure 3 when the eraser is pressed against the surface of a sheet of paper 14. Therefore, such an eraser cannot scrape the ink 16 bonded to the paper surface 14 therefrom because such a conventional eraser has poor erasing ability. On the other hand, if the bulk eraser material 10 is a hard material, as shown in Figure 4, such hard bulk eraser material 10 cannot come into close contact with the paper surface 14. Accordingly, if there are minute irregularities on the paper surface 14, particles of the abrasive material 12 included in such a hard eraser cannot fit into the minute irregularities and the abrasive material particles 12 are unable to scrape off the ink 16 from the paper surface 14. In this case, it is necessary to scrape off the paper 14 itself to a depth corresponding to that where the ink 16 exists, with the disadvantage that the paper 14 is damaged by a hard eraser when a soft paper is used, whilst if a hard paper is employed, the paper 14 cannot be scraped off by the eraser and the ink 16 on the paper surface remains unerased. In view of the above, the present invention contemplates eliminating the disadvantages involved in the above described prior art and to provide an improved eraser, by the use of which damage to a sheet of paper is decreased, and the erasing ability of the eraser is increased. A method for manufacturing such an improved eraser is also contemplated. The present invention relates to an abrasive containing eraser wherein the bulk material comprises a particulate mixture of at least three component materials having different hardness. Furthermore, the present invention relates also to a method of manufacturing an abrasive containing eraser including the steps of kneading together at least three types of bulk eraser material, which have been previously formed and vulcanised independently with an abrasive material, and forming and vulcanising the resultant mixture. The plural types of bulk eraser materials are such that erasers having different hardnesses can be produced if each of said plural types of bulk eraser material is either vulcanised or heated and formed alone and that particles of said plural types of bulk eraser materials exist independently from one another even when these materials are kneaded. When the eraser of the present invention is pressed against the surface of a sheet of paper bearing marks to be erased, soft eraser pieces in said eraser deform in conformity with minute irregularities on said paper surface resulting in close contact of the entire eraser with the paper. Thus, the abrasive material is forcibly pressed against the paper surface by means of hard eraser pieces to scrape off ink bonded on said paper surface. Therefore, even if there are minute irregularities on the paper surface, said paper surface can be sufficiently rubbed with the eraser of the invention over the irregular surface thereof, so that only the ink is removed without substantial damage to the paper surface. Furthermore, said improved eraser can be obtained in accordance with the manufacturing method of the present invention. Reference is also made to FR 2 103 018 wherein an eraser having a composite bulk material is disclosed. Figure 1 is an enlarged sectional view showing an example of an eraser according to the present invention; Figure 2 is a sectional view and a partially enlarged view thereof showing a conventional sand containing eraser; Figures 3 and 4 are sectional views illustrating the state of a sheet of paper in the case where the sand-containing eraser of Figure 2 is pressed against the surface of a sheet of paper; and Figure 5 is a sectional view illustrating a state of a sheet of paper in the case where the eraser in Figure 1 is pressed against the surface of the paper. An embodiment of the eraser according to the present invention is shown in Figure 1 in an enlarged manner and is composed of bulk material comprising soft eraser pieces 20, eraser pieces 22 of medium hardness, hard eraser pieces 24 together with abraisve material 26 dispersed throughout the bulk material. When the eraser is pressed against the surface of a sheet of paper, the eraser comes into close contact with the paper surface 28 as a result of deformation of the soft eraser pieces 20 in conformity with the minute undulations of the paper surface 28 as shown in Figure 5. At the same time, the abrasive material 26 is strongly pressed onto the paper surface 28 by means of the hard eraser pieces 24 in order to scrape off the ink 30 which has adhered to the paper surface 28. Thus, even if there are minute undulations on the paper surface 28, the surface of the paper can be rubbed with the eraser along the undulated surface thereof, so that only the ink 30 is removed without the paper surface 28 being significantly damaged. An example of a method for manufacturing the eraser shown in Figure 1 will be described hereinbelow. In Example 1, three types of materials for the eraser, i.e. hard, medium, and soft materials are used as the bulk eraser materials. Material 1 (20) is a particularly soft material, material 2 (22) is one having substantially the same hardness with that of ordinary raw rubber, and material 3 (24) is a hard material. In the case where only a hard material and a soft material are used and there is a large difference in the hardness of the materials, it is hard to form a homogeneous mixture, even when kneading is employed. However, when a material having a medium hardness is introduced into the mixture of both the hard and soft materials, these components are easily formed into a homogeneous mixture. When the bulk eraser materials 1-3 are independently vulcanised and formed, each of the resulting erasers produces residuary substances as a result of friction with the surface of a piece of paper. Furthermore, even if these bulk eraser materials are kneaded by means of rolling or the like operation, they do not fuse to one another, but are dispersed in the resulting product due to the natural adhesion of rubber. This produces a cohesive product. The eraser materials exist in the form of particles without any accompanying change in the properties of the respective materials. First, three types of bulk eraser materials 1, 2, 3 and an abrasive raw material, together with a method for manufacturing an eraser will be described hereinbelow. (1) Material 1 (soft eraser material) The material 1 is prepared from the following respective ingredients A - H as the raw material. All parts given in the following description are by weight unless otherwise indicated. A ratio of ingredients A, B and C may be varied within a range in which then the upper limit of ingredient A is 68 parts, ingredients B and C are 22 parts and 10 parts, respectively, whilst when the lower limit of ingredient A is 18 parts, ingredients B and C are 22 parts and 60 parts, respectively. As ingredient A, plasticisers other than trichloroethyl phosphate such as dioctyl phthalate, dibutyl phthalate and the like which are well miscible with ingredients B and C and are vulcanisable may be used either alone or in a combination of several plasticisers. Chinese white, (ingredient E) is for accelerating subsidiarily the vulcanisation. Calcium carbonate (ingredient G) is used for increasing the hardness of material 1. Ingredient A is a plasticiser which softens the material 1 and also produced residuary substances due to friction with the surface of a piece of paper. Furthermore, ingredient A is a liquid which dissolves various resins well, and particularly ball-point pen ink. When ingredient A is applied on the surface of a paper without any modification, it dissolves any ball-point pen ink on the paper and the dissolved ink then blots the paper. However, when ingredient A is kneaded with the other ingredients in material 1, the ingredient A is dispersed into the material 1. Thus, ingredient A contributes to release rapidly in adhered closely to the surface of a sheet of paper, when the paper surface is rubbed with such an eraser containing the material 1 after vulcanisation. It is required to previously vulcanise material 1 among materials 1 - 3, because the ingredients of the material 1 fuse into the other materials 2 and 3, if the material 1 is kneaded with materials 2 and 3 without previously vulcanising the material 1. Previous vulcanisation is not required for materials 2 and 3, because ingredients which do not fuse with each other, even if the materials 2 and 3 have not been previously vilcanised, are utilised. Even though material 1 has previously been vulcanised, it can be mixed with other materials 2 and 3 by kneading, because the material 1 is soft. Material 1 is prepared in such a manner that all the ingredients A - H described above are blended at a stretch, the blend is kneaded by the use of a kneader, a three-roll mill or the like, and the kneaded ingredients are vulcanised in accordance with an ordinary rubber vulcanising procedure. The finished material 1 is particularly soft, and when the surface of a sheet of paper is rubbed with the material 1, residuary substances are produced from the material 1 so that it serves as an eraser. (2) Material 2 (eraser material having a hardness which is substantially the same with that of raw rubber). The material 2 is prepared from the following respective ingredients A - G as the raw materials. A ratio of ingredients A and B may be varied within a range in which when the upper limit of ingreident A is 95 parts, ingredient B is 5 parts, whilst when the lower limit of ingredient A is 70 parts, ingredient B is 30 parts. Ingredient A has been previously masticated (without adding ingredients B - G). As a result of such previous mastication, the ingredient A becomes easily mixed with ingredient B. Ingredient C is used for mixing ingredient A together with ingredient B, and which may be any solvent other than methyl ethyl ketone so far as it evaporates and is common to ingredients A and B. Ingredient A does not exhibit essentially perfect mixing with respect to ingredient B (they do not form fine particles), but when ingredient C is added to both the ingredients A and B, they become miscible with one another. As described above, when such ingredients which are essentially immiscible are forcibly mixed together, a fragile product is produced. Accordingly, when the surface of a paper is rubbed with such product, residuary substances are produced so that the product serves as an eraser. As a result of containing a large amount of factice, plasticiser, mineral oil and the like, conventional, erasers produce residuary substances. In the eraser according to the present invention, however, even if a small amount of factice, a plasticiser, a mineral oil and the like are added to the material 2, ingredients of the materials 1 - 3 are easily mixed together and the materials 1 - 3 cannot exist as independent particles in the final product. Thus, all the ingredients of the respective materials 1 - 3 are united together, so that the resulting eraser has a significantly poorer erasing ability. When material 2 is prepared from the ingredients A - G as described above, materials 1 - 3 can exist as independent particles in the final produce so that the final product produces residuary substances in use. It is to be noted that one part or more of ingredient C is sufficient for mixing together ingredients A and B. Material 2 is prepared as follows. To the ingredient A which has been previously masticated are added ingredients B and C, the resulting mixture is sealed and allowed to stand for about 12 hours, and then ingredients D - G are added thereto and milled by roll milling. While substantially all the ingredient C evaporates during the rolling, air drying for three days is preferable. The final product is not adversely affected if a small amount of ingredient C remains in the material 2. (3) Material 3 (hard eraser material) The material 3 is prepared from the following respective ingredients A - G as the raw materials. The respective upper limits of the ingredients A, B and C used for preparing material 3 are 100 parts, 9.5 parts, and 20 parts, whilst the lower limits thereof are 100 parts, 3 parts, and 10 parts, respectively. In ingredient A, a content of styrene may be selected within a range of from 75 to 90%, and the higher content of styrene results in the harder material 3. As ingredient B, liquid polyethylene glycol having a molecular weight of up to about 600 may be used. Ingredient B dissolves ball-point pen ink well, and it serves to accelerate the erasing function for ball-point pen marks. When ingredient B is applied on the surface of a piece of paper without any modification, the ingredient B dissolves the ball-point pen ink on the paper and the dissolved ink blots the paper. however, when ingredient A is mixed with ingredient B, the latter is dispersed into material 3. Thus, ingredient B contributes to release rapidly the ink adhered closely to the surface of a paper, when the paper surface is rubbed with such an eraser containing the material 3 after vulcanisation. Ingredient A does not exhibit essentially perfect miscibility with respect to ingredient B, but when ingredient C being a solvent common to both ingredients A and B is added to them, they become miscible with one another . This is the same theory as that relating to said material 2 wherein ingredient A is made miscible with ingredient B by the addition of ingredient C. As described above, when such immiscilble ingredients as A and B are forcibly mixed together, a fragile product is produced. Accordingly,when the surface of a sheet of paper is rubbed with such product, residuary substances are produced and the product will serve as an eraser. As mentioned above, as a result of containing a large amount of factice, plasticiser, mineral oil and the like, conventional erasers produce residuary substances. In the eraser according to the present invention, however, even if a small amount of a factice, a plasticiser, a mineral oil and the like are added to the material 3, the ingredients of materials 1 - 2 are easily mixed together and the materials 1 - 3 cannot exist as independent particles in the final product. Thus, all the ingredients of the respective materials 1 - 3 are united together, so that the resulting eraser cannot produce residuary substances and exhibits no erasing ability for pencil marks. When material 3 is prepared from ingredients A, B, and C as described above, materials 1 - 3 can exist as independent particles in the final product and the final prodct can produce residuary substances in use, and a hard eraser can thus be obtained. Ingredient D (sulphur) is used for vulcanising and shaping mixed materials 1 - 3 at the final stage. Ingredient G (titanium white) is a pigment for colouring the final product. Material 3 is prepared in such a manner that a well blended mixture, obtained by adding ingredient B to ingredient C, is introduced into ingredient A. The resulting admixture is sealed and allowed to stand for about 6 hours, the ingredients D - G are added thereto, and the mixture is milled by the use of rollers. While the ingredient C (methyl ethyl ketone) contained in material 3 evaporates considerably during the rolling, air-drying for five days is preferable. There is no adverse affect on final products even if a small amount of ingredient C remains in the material 3. The material 3 is particularly hard so that when only such material is vulcanised, the hardness of the resulting product is such that the surface thereof cannot be scratched by the user's finger nail. (4) Abrasive material (material 4) The abrasive material is prepared with the following ingredients A and B as raw materials. As ingredient B, such polyethylene glycol having a molecular weight of about 1540 as the lower limit may be used. As to a ratio of polyethylene glycol with respect to water, the upper limit of which is polyethylene glycol having a molecular weight of 20,000 : water = 10 : 90, whilst the lower limit is 2 : 98. Any material having a particle size of about 320 mesh as well as high water absorbing capacity may be used as ingredient A. When ingredient A is mixed with materials 1 -3 without any modification, the materiasl 1 - 3 are closely adhered to ingredient A, so that residuary substances are difficult to produce in the case when the surface of a paper is rubbed with the resulting eraser and its erasing ability decreases. However, when ingredient B being a lubricating material is bonded to ingredient A, the materials 1 - 3 become hard to closely adhere to one another so residuary substance are easily produced. Furthermore, since ingredient B being polyethyelen glycol having a molecular weight of 20,000 exhibits slippage as in paraffin, when the ingredient B is bonded to ingredient A, damage of the surface of a paper to be erased can be considerably reduced. Referring to ingredient A, although an abrasive material of about 150 mesh has been used in ordinary sand-containing erasers, the surface of a paper to be erased is significantly damaged by a sand-containing eraser containing an abrasive material of such mesh. According to the erasers of the present invention, a particle size of the abraisve material may be within a range of about 150 - about 500 mesh, and preferably about 320 - about 400 mesh so that damage of the paper surface erased can be reduced, besides the erasing ability of such an eraser is favourable. The abrasive material of the present invenitons is prepared as follows. Ingredient B is added to ingredient A, and the mixture is heated in a water bath for about 20 minutes to expel moisture in the ingredient B in the form of a solution. The mixture so treated is heated at about 140°C for about 25 - 40 minutes by the use of a dryer, and the ingredient B is allowed to permeate sufficiently into the ingredient A. Ingredient B, being a lubricating material, may be a solution prepared by dissolving, for example, a releaser silicone into polyethylene glycol with the use of water, a solution prepared by dissolving an aliphatic acid into polyethylene glycol with the use of an emulsifier, a solution prepared by dissolving stearic acid into polyethylene glycol with the use of methyl ethyl ketone, or the like. When using these solutions, each ingredient B is allowed to bond to or permeate into the abrasive material, and then the corresponding solvent (water, emulsifier, or methyl ethyl ketone) is permitted to evaporate from the corresponding solution. After preparing materials 1 - 3 of a bulk eraser material and an abrasive material (material 4) as described above, the following stages are carried out as the final process to obtain the product. (1) First Stage The following materials are milled by rollers. When kneading materisl 2 and 3 by means of rollers, the size of the particles of the respective materials 1 - 3 varies, depending upon the gap defined between the rollers. In the case when the rollers are set at their narrowest gap, irregularties on the surface of the resulting product decrease, whilst when the gap is 2 - 3 mm, a product with a considerable irregularity is obtained. (2) Second Stage The following materials are milled by rollers. (3) Third Stage The following materials are milled by rollers. It is preferred that a ratio of the abrasive material (material 4) with respect to the total bulk eraser material obtained in the second stage is about 75 - 80%. (4) Fourth Stage The materials milled in the third stage are vulcanised and shaped to obtain products as in the case of general rubber products. In the products thus obtained, the mateisl 1 - 3 constituting the eraser itself exist in the form of particles, where the particle size of which is larger than that of the abrasive material material 4). Another example of the method for manufacturing the eraser shown in Figure 1 according to the present invention will be described hereinbelow. In Example 2, the materials to be used and the manufacturing steps therefor are essentially the same with those of Example 1 except that the moderately high nitrile content of ingredient C in the material 1 of Example 1 is omitted in Example 2. Furthermore, calcium carbonate (ingredient F) serves for preventing the percipitation of sulphur and chinese white during vulcanisation. In Example 2, sulphur, chinese white, vulcanising accelerator, and titanium white (ingredients D - G) in material 2 are not introduced into the material 2, but added at the final stage. Moreover, as to a compounding ratio of the materials 1 and 2 at the final stage, a ratio of the material 2 is made larger than that of Example 1. Three type of bulk eraser materials 1, 2, 3 and an abrasive raw material as well as a method for manufacturing an eraser in Example 2 will be described hereinbelow. (1) Material 1 (especially soft material) The material 1 is prepared with the following ingredients A - F as the raw materials. All parts given in the following description are by weight unless otherwise indicated. A ratio of ingredients A and B may be varied within a range in which when the upper limit of ingredient A is 88 parts, ingredient B is 12 parts, whilst when the lower limit of ingredient A is 21 parts, ingredient B is 79 parts. As an ingredient A, plasticisers other than trichloroethyl phosphate such as dioctyl phthalate, dibutyl phthalate and the like, which are well miscile with ingredient B and vulcanisable, may be used either alone or in combination. Calcium carbonate of the ingredient F serves herein for preventing precipitation of sulphur and chinese white in case of the vulcanisation. Material 1 is prepared in such a manner that all the ingredients A - F described above are blended at a stretch, the blend is kneaded by the use of a kneader, a three-roller mill or the like, and the kneaded ingredients are vulcanised in accordance with an ordinary rubber vulcanising procedure. The finished material 1 is particularly soft, and when the surface of a sheet of paper is rubbed with the material 1, residuary substances are produced from the materail so that it serves as an eraser. (2) Material 2 (one having a hardness which is substantially the same with that of raw rubber) The material 2 is prepared from the following respective ingredients A - C as the raw materials. Ingredient A has been previously masticated (milled without adding sulphur). As a result of such previous mastication, the ingredient A become easibly miscible with ingredient C. Ingredient C is used for mixing ingredient A together with ingredient B, and which may be any solvent other than methyl ethyl ketone so far as it dissolves A and evaporates by itself. It is to be noted that one part or more or methyl ethyl ketone is sufficient for mixing together ingredients A and B. Ingredient A does not exhibit essentially perfect miscibility with respect to ingredient B (they do not form fine particles), but when ingredient C is added to both ingredients A and B, they become miscible in one another. The ratio of ingredients A, B and C may be varied within a range in which when the upper limit of ingredient A is 95 parts, ingredients B and C are 5 parts and 10 parts, respectively, whilst when the lower limit of ingredient A is 60 parts, ingredients B and C are 40 parts and 10 parts, respectively. When preparing material 2, first, ingredient C is added to ingredient A, the resulting mixture is sealed and allowed to stand for about 12 hours, and then ingredient B is added thereto and milled sufficiently while effecting roller milling. The resulting mixture thus kneaded is heated in a water bath or air-dried to obtain material 2. The hardness of the finished material 2 is substantially the same as that of an ordinary raw rubber. (3) Material 3 (hard material) The material 3 is prepared from the following respective ingredients A - G as the raw materials. Ingredient C, which functions similarly to ingredient C in material 2, is used for mixing ingredient A with ingredient B, and which may be any solvent other than methyl ethyl ketone so far as it dissolves A and evaporates by itself. For ingredient A, a content of styrene may be selected within a range of from 80 to 93%, and the higher content of styrene results in the harder material 3. As ingredient B, liquid polyethylene glycol having a molecular weight of up to about 600 may be used. Ingredient A does not exhibit essentially perfect miscibility with respect to ingredient B, but when ingredient C is added to them, they become miscible in one another. The ratio of ingredients A, B and C may be varied within a range in which the upper limit of ingredient A is 97 parts, ingredients B and C are 3 parts and 25 parts, respectively, whilst when the lower limit of ingredient A is 87 parts, ingredients B and C are 13 parts and 25 parts, respectively. When preparing material 3, a well blended mixture obtained by adding ingredient B to ingredient C is introduced into ingredient A, the resulting admixture is sealed and allowed to stand for about 3 hours, then it is simply milled by the use of rollers and air-dried, thereafter the resulting product is subjected to roller milling. Material 3 is particularly hard such that when such material is vulcanised, the hardness of the resulting product is such that the surface thereof cannot be scratched by a user's finger nail. (4) Abrasive material (material 4) The abrasive material is prepared from the following ingredients A and B as the raw materials. Any material having a particle size of about 320 mesh as well as high water absorbing capacity may be used as ingredient A. The abrasive material of the present invention is prepared as follows. Ingredient B is added to ingredient A, and the mixture is heated in a water bath for about 20 minutes to expel moisture in the ingredient B. The mixture so treated is heated at around 140°C four about 40 minutes by the use of a dryer, and the ingredient B is allowed to permeate sufficiently into the ingredient A. According to the erasers of the present invention, a particle size of the ingredient A may be within a range of about 150 - 500 mesh, and preferably about 320 - 400 mesh so that damage of the paper surface erased can be reduced, besides the erasing ability of such an eraser is favourable. As ingredient B, polyethylene glycol having a molecular weight of about 1540 as the lower limit may be used. After preparing material 1 - 3 of bulk eraser material and an abrasive material (material 4) as described above, the following stages are practiced as the final process to obtain a product. (1) First Stage The following materials are milled by rollers. Sulphur is used for vulcanising material 2. (2) Second Stage The following materials are milled by rollers. (3) Third Stage The following materials are milled by rollers. It is preferred that a ratio of the abrasive material (material 4) to the total bulk eraser material obtain in the second statge is about 75 - 80%. (4) Fourth Stage The materials milled in the third stage are vulcanised and shaped to obtain products as in the case of general rubber products. In the products thus obtained, the materials 1 - 3, constituting the eraser itself, exist in the form of particles having a particle size of which is larger than that of the abrasive material (material 4). A formulation in the first to fourth stages of the final process may be modified as follows: While three types of materials have been used as the bulk eraser materials in Examples 1 and 2, of course, two four or more types of materials may also be used. Furthermore, it is to be noted that an abrasive material may be included into particles of the bulk eraser materials of the present invention, if required.

Claims: An eraser comprising a bulk material having an abrasive particulate material (26) dispersed therein, characterised in that, the bulk material comprises a particulate mixture of at least three component materials (20, 22, 24) having different hardnesses. An eraser according to claim 1 characterised in that at least one of the bulk material components (20, 22, 24) is a rubber-like substance which is prepared by mixing together ingredients which are not normally miscible. An eraser according to claim 1 or 2 characterised in that the abrasive material (26) is prepared by bonding a lubricating material thereto. An eraser according to claim 1 or 2 characterised in that the abrasive material (26) is prepared by allowing a lubricating material to permeate into it. A method of manufacturing an eraser by dispersing an abrasive particulate material in an eraser bulk material and then vulcanising the mixture obtained characterised in that the method includes the steps of kneading together at least three types of bulk eraser material, which have been previously formed and vulcanised independently, with an abrasive material, and shaping and vulcanising the resultant mixture. A method of manufacturing an eraser according to claim 5 characterised in that at least one of the three types of bulk eraser material is a rubber-like substance which is prepared from a plurality of ingredients, two of which are not normally miscible with each other, by adding a solvent common to the two immiscible ingredients, kneading the resultant mixture, and then evaporating the solvent from the mixture. A method of manufacturing an eraser according to claim 5 or 6 characterised in that the abrasive material is prepared by bonding a lubricating material, dissolved in a solvent, to the abrasive material, and then causing the solvent to evaporate. A method of manufacturing an eraser according to claim 5 or 6 characterised in that the abrasive is prepared by allowing a lubricating material, dissolved in a solvent, to permeate into the abrasive material, and then causing the solvent to evaporate.

Inventors: HORIE, FUMIO
Applicants: HORIE SANGYO KABUSHIKI KAISHA
Application year: 1987
Main classification: B43L19
IPC codes: B43L19