Eraser, composition for producing eraser, and method for producing eraser

Abstract

The present invention provides an eraser excellent in folding resistance and erasing property, a composition for producing the same, and a method for producing the eraser. The present disclosure provides an eraser containing a vinyl chloride resin produced by a suspension polymerization method or a bulk polymerization method, a plasticizer, and a porous filler. The present disclosure further provides a composition for producing an eraser containing the vinyl chloride resin, a plasticizer, and a porous filler. The present disclosure further provides a method for producing an eraser comprising molding the composition for producing an eraser under heating conditions.

Description

Eraser, composition for producing eraser, and method for producing eraser

[0001] The present disclosure relates to an eraser for erasing handwriting, a composition for making an eraser, and a method for making an eraser.

[0002] 2. Description of the Related Art Erasers (erasers) used to erase handwriting made on paper with a writing implement such as a pencil have conventionally been devised in various ways depending on the functions required.

[0003] For example, Patent Document 1 describes a vinyl chloride resin composition for erasers, comprising (a) 100 parts by weight of a vinyl chloride resin produced by suspension polymerization or bulk polymerization, (b) 3 to 100 parts by weight of an acrylic resin, (c) 50 to 300 parts by weight of a plasticizer, and (d) 0 to 600 parts by weight of a filler. According to Patent Document 1, while vinyl chloride resins produced by emulsion polymerization have traditionally been used to manufacture erasers, vinyl chloride resins produced by suspension polymerization or bulk polymerization, when blended with plasticizers, fillers, etc. and molded by extrusion or injection molding, gelation proceeds rapidly, resulting in the resulting molded product lacking erasing properties. Therefore, Patent Document 1 describes that blending the acrylic resin (b) in addition to (a) suppresses gelation and increases abrasion resistance, thereby improving erasing performance.

[0004] Patent Document 2 describes an eraser containing a vinyl chloride resin, a plasticizer, and a filler, wherein the plasticizer contains a compound having a solubility parameter of 9.2 to 11.0, and the compound having the solubility parameter is at least one compound selected from the group consisting of phthalate esters, benzoate esters, and phosphate esters. According to Patent Document 2, by using a compound having a predetermined solubility parameter as a plasticizer in an eraser containing a vinyl chloride resin and a filler, excellent erasability is maintained, and breakage resistance and a sticky feel are provided.

[0005] Patent Document 3 describes an eraser containing cellulose nanofibers with an average fiber diameter of 1 to 700 nm. According to Patent Document 3, conventional PVC erasers have the drawback of being weak and easily broken, and increasing the amount of resin to increase strength has the problem of reducing erasability. However, by blending the above-mentioned specified cellulose nanofibers, it is possible to improve erasability.

[0006] Japanese Patent Application Laid-Open No. 54-124052 Japanese Patent Application Laid-Open No. 2022-99185 Japanese Patent Application Laid-Open No. 2021-167088

[0007] As described above, various erasers have been proposed up to now, but no eraser has been provided that combines the property of being difficult to break during use (break resistance) with erasability at a fully satisfactory level.

[0008] Therefore, an object of the present invention is to provide an eraser having excellent breakage resistance and erasability, an eraser manufacturing composition for manufacturing the eraser, and a method for manufacturing the eraser.

[0009] The present inventors have found that, in an eraser containing a vinyl chloride resin, a plasticizer, and a filler, when the vinyl chloride resin is a vinyl chloride resin produced by a suspension polymerization method or a bulk polymerization method, and the filler is a porous filler, an eraser having excellent break resistance and erasability can be produced.

[0010] The present disclosure relates primarily to an eraser comprising: a vinyl chloride resin produced by a suspension polymerization method or a bulk polymerization method; a plasticizer; and a porous filler.

[0011] The eraser preferably contains the porous filler in a ratio of 5 parts by mass or more to 500 parts by mass or less per 100 parts by mass of the vinyl chloride resin, and more preferably contains the porous filler in a ratio of 5 parts by mass or more to 100 parts by mass or less per 100 parts by mass of the vinyl chloride resin.

[0012] The porous filler of the eraser preferably contains one or more selected from the group consisting of silica, magnesium carbonate, zeolite, porous calcium carbonate, algal-like calcium carbonate, porous alumina, porous acrylic resin, diatomaceous earth, perlite, kaolin algal-like xonotlite, vermiculite, sepiolite, attapulgite, and porous quartz glass.

[0013] The eraser preferably contains the plasticizer in a proportion of 100 parts by mass or more and 300 parts by mass or less relative to 100 parts by mass of the vinyl chloride resin.

[0014] The eraser preferably contains the plasticizer in a proportion of 80 parts by mass or more and 200 parts by mass or less per 100 parts by mass of the total amount of the vinyl chloride resin and the porous filler.

[0015] The eraser preferably contains the vinyl chloride resin in a proportion of 10% by mass or more and 45% by mass or less based on the total amount of the eraser.

[0016] The eraser preferably further contains a non-porous filler, which preferably contains one or more selected from the group consisting of calcium carbonate (particularly ground calcium carbonate), talc, mica, glass beads, glass fiber, carbon fiber, wollastonite, alumina, quartz powder, and coal ash.

[0017] The eraser preferably contains the non-porous filler in a proportion of 30 parts by mass or more and 200 parts by mass or less per 100 parts by mass of the vinyl chloride resin.

[0018] A second aspect of the present disclosure relates to a composition for producing an eraser, which comprises: a vinyl chloride resin produced by a suspension polymerization method or a bulk polymerization method; a plasticizer; and a porous filler.

[0019] The composition for manufacturing erasers preferably contains the porous filler in a ratio of 5 parts by mass or more to 500 parts by mass or less per 100 parts by mass of the vinyl chloride resin, and more preferably contains the porous filler in a ratio of 5 parts by mass or more to 100 parts by mass or less per 100 parts by mass of the vinyl chloride resin.

[0020] In the composition for manufacturing an eraser, the porous filler preferably contains one or more selected from the group consisting of silica, magnesium carbonate, zeolite, porous calcium carbonate, algal-like calcium carbonate, porous alumina, porous acrylic resin, diatomaceous earth, perlite, kaolin algal-like xonotlite, vermiculite, sepiolite, attapulgite, and porous quartz glass.

[0021] The composition for manufacturing an eraser preferably contains the plasticizer in a proportion of 100 parts by mass or more and 300 parts by mass or less per 100 parts by mass of the vinyl chloride resin.

[0022] The composition for producing an eraser preferably contains the plasticizer in a proportion of 80 parts by mass or more and 200 parts by mass or less per 100 parts by mass of the total amount of the vinyl chloride resin and the porous filler.

[0023] The composition for producing an eraser preferably contains the vinyl chloride resin in a proportion of 10% by mass or more and 45% by mass or less based on the total amount of the composition for producing an eraser.

[0024] The composition for manufacturing an eraser preferably further contains a non-porous filler, which preferably contains one or more selected from the group consisting of calcium carbonate (particularly ground calcium carbonate), talc, mica, glass beads, glass fiber, carbon fiber, wollastonite, alumina, quartz powder, and coal ash.

[0025] The composition for manufacturing an eraser preferably contains the non-porous filler in a proportion of 30 parts by mass or more and 200 parts by mass or less per 100 parts by mass of the vinyl chloride resin.

[0026] A third aspect of the present disclosure relates to a method for producing an eraser, which comprises molding the composition for producing an eraser under heated conditions.

[0027] This specification includes the disclosure of Japanese Patent Application No. 2024-125027, from which the present application claims priority.

[0028] Furthermore, all publications, patents, and patent applications cited herein are hereby incorporated by reference in their entirety.

[0029] The eraser according to the present disclosure has excellent break resistance and erasability.

[0030] The composition for manufacturing an eraser according to the present disclosure can be used to manufacture an eraser that has excellent break resistance and erasability.

[0031] According to the method for manufacturing an eraser according to the present disclosure, an eraser having excellent break resistance and erasability can be manufactured.

[0032] 1. Components of Erasers and Compositions for Eraser Manufacturing 1.1. Vinyl Chloride Resin The erasers and compositions for eraser manufacturing according to the present disclosure contain, as a base component, polyvinyl chloride resin (PVC resin) produced by suspension polymerization or bulk polymerization. The vinyl chloride resin produced by suspension polymerization or bulk polymerization used as a raw material in the present disclosure may be provided in powder form. Compared to vinyl chloride resin produced by emulsion polymerization, which has traditionally been used to manufacture erasers, vinyl chloride resin produced by suspension polymerization or bulk polymerization has a larger particle size, allowing it to absorb and retain a larger amount of plasticizer within the particles. In this specification, vinyl chloride resin produced by suspension polymerization or bulk polymerization is sometimes referred to as "general PVC," and vinyl chloride resin produced by emulsion polymerization is sometimes referred to as "paste PVC." "Paste PVC" is an abbreviation for vinyl chloride resin for paste processing.

[0033] The vinyl chloride resin particles produced by suspension polymerization or bulk polymerization have an average particle diameter of, for example, 10 μm or more, preferably 20 μm or more, more preferably 50 μm or more, even more preferably 10 μm or more and 500 μm or less, even more preferably 20 μm or more and 300 μm or less, even more preferably 50 μm or more and 200 μm or less.Here, average particle diameter can be the average value of the longest diameter of resin particles in the observation image when the vinyl chloride resin raw material before being processed into eraser is observed by scanning electron microscope (SEM).For example, it can be determined by measuring the longest diameter of each of 30 resin particles randomly selected in the SEM observation image, and calculating the average value.The vinyl chloride resin particles in the raw material state produced by suspension polymerization or bulk polymerization have a relatively large average particle diameter as mentioned above, are porous, and are irregular in the SEM observation image. On the other hand, vinyl chloride resin produced by emulsion polymerization differs from vinyl chloride resin produced by suspension polymerization or bulk polymerization in that the particles in the raw material state have a similarly measured average particle diameter of several μm or less, for example, 0.1 to 2 μm, are non-porous, and are spherical in SEM images. The particles of vinyl chloride resin produced by suspension polymerization or bulk polymerization are pulverized during processing into erasers, and the shape of the particles in the produced erasers is irregular. In contrast, the particles of vinyl chloride resin produced by emulsion polymerization tend to maintain their spherical shape even after processing into erasers.

[0034] Furthermore, vinyl chloride resins (general-purpose vinyl chlorides) produced by suspension polymerization or bulk polymerization are also preferred in that they are usually cheaper than vinyl chloride resins (paste vinyl chlorides) produced by emulsion polymerization.

[0035] The vinyl chloride resin used in this disclosure, produced by suspension polymerization or bulk polymerization, is a vinyl chloride homopolymer or a copolymer in which vinyl chloride is the main component and is copolymerized with other monomers. Examples of other monomers include vinyl acetate, ethylene, methyl acrylate, and methyl methacrylate. From the viewpoint of erasing performance, the vinyl chloride resin is preferably a resin composed of a vinyl chloride homopolymer. Examples of the copolymer include copolymers containing vinyl chloride monomer, preferably 75 mol% or more, more preferably 90 mol% or more, of the total amount of monomers.

[0036] The polymer constituting the vinyl chloride resin used in the present disclosure and produced by suspension polymerization or bulk polymerization has an average degree of polymerization of, for example, 650 to 4000, preferably 800 to 2500, and more preferably 900 to 1600. As the vinyl chloride resin produced by suspension polymerization or bulk polymerization, a combination of multiple vinyl chloride resins with different average degrees of polymerization can also be used. For example, a vinyl chloride resin having an average degree of polymerization of 1000 or less can be used in combination with a vinyl chloride resin having an average degree of polymerization of more than 1000. The average degree of polymerization of the vinyl chloride resin refers to the weight-average degree of polymerization determined using gel permeation chromatography (GPC).

[0037] The eraser and the composition for producing the eraser according to the present disclosure may contain other resins or rubbers in addition to the vinyl chloride resin, as long as the erasability and breakage resistance of the eraser are not impaired. Examples of other resins include thermoplastic elastomers. Examples of other rubbers include natural rubber, synthetic rubber, and combinations thereof.

[0038] 1.2 Plasticizer The plasticizer gives the eraser appropriate flexibility and resistance to friction with the paper surface, and also functions to adsorb graphite and collect eraser dust.

[0039] Examples of plasticizers include phthalate ester plasticizers such as bis(2-ethylhexyl) phthalate (DOP), diisononyl phthalate (DINP), and diundecyl phthalate (DUP); adipate ester plasticizers such as bis(2-ethylhexyl) adipate (DOA) and diisononyl adipate (DINA); citrate ester plasticizers such as acetyl tributyl citrate (ATBC); alkylsulfonic acid phenyl esters such as Mezamol (registered trademark); benzoate ester plasticizers such as glycol benzoate esters; terephthalate ester plasticizers such as bis(2-ethylhexyl) terephthalate; trimellitate ester plasticizers; adipate polyester plasticizers; and phthalate polyester plasticizers. Two or more plasticizers may be used in combination.

[0040] 1.3. Porous Filler The porous filler not only imparts hardness to the eraser and increases its breakage resistance, but also absorbs and retains the plasticizer. It is believed that the plasticizer retained in the porous filler seeps out and absorbs the graphite when the eraser is pressed against the paper surface and rubbed. Furthermore, by having the plasticizer absorbed and retained in the porous filler in addition to the vinyl chloride resin particles, the softening of the eraser caused by the plasticizer is appropriately suppressed, and the hardness of the eraser is maintained.

[0041] When the porous filler is composed of a porous inorganic material, it can be called a "porous inorganic filler." The porous filler is a porous filler that has oil absorption properties. The porosity of the porous filler can be expressed by the oil absorption amount. Specifically, the oil absorption of the porous filler, when measured according to the boiled linseed oil method specified in JIS K 5101-13-2:2004, is preferably 45 mL / 100 g or more, more preferably 50 mL / 100 g or more, even more preferably 80 mL / 100 g or more, even more preferably 100 mL / 100 g or more, even more preferably 150 mL / 100 g or more, even more preferably 45 mL / 100 g or more and 500 mL / 100 g or less, even more preferably 50 mL / 100 g or more and 500 mL / 100 g or less, even more preferably 80 mL / 100 g or more and 500 mL / 100 g or less, even more preferably 100 mL / 100 g or more and 300 mL / 100 g or less, and most preferably 150 mL / 100 g or more and 250 mL / 100 g or less. A porous filler having an oil absorption in this range has a high ability to absorb and retain plasticizers, and by incorporating the filler, an eraser with particularly high erasability can be obtained.

[0042] Specific examples of suitable porous fillers include silica, magnesium carbonate, zeolite, porous calcium carbonate, algae-like calcium carbonate, porous alumina, porous acrylic resin, diatomaceous earth, perlite, kaolin, algae-like xonotlite, vermiculite, sepiolite, attapulgite, and porous quartz glass.

[0043] 1.4 Non-porous Filler The eraser and composition for producing an eraser according to the present disclosure preferably further contain a non-porous filler. The non-porous filler imparts hardness to the eraser to increase its resistance to bending, and also contributes to erasability by physically scraping off handwriting from the paper surface when rubbed.

[0044] When a non-porous filler is composed of a non-porous inorganic substance, it can be referred to as a "non-porous inorganic filler." The oil absorption is also useful as an indicator of whether a non-porous filler is porous. Specifically, the oil absorption of the non-porous filler is preferably 40 mL / 100 g or less, more preferably 30 mL / 100 g or less, and particularly preferably 20 mL / 100 g or less, as measured according to the boiled linseed oil method specified in JIS K 5101-13-2:2004.

[0045] Specific examples of suitable non-porous fillers include calcium carbonate (particularly ground calcium carbonate), talc, mica, glass beads, glass fiber, carbon fiber, wollastonite, alumina, quartz powder, and coal ash.

[0046] 1.5 Other Components The eraser and composition for producing an eraser according to the present disclosure may further contain other components as long as they do not impair the erasability or crease resistance of the eraser.

[0047] The other ingredients may include one or more of a stabilizer, a lubricant, a colorant, and the like.

[0048] The stabilizer is one commonly used in the field of resin molding, and is preferably a heat stabilizer for vinyl chloride resin. Examples of heat stabilizers for vinyl chloride resin include metal soaps of metals such as barium, zinc, and calcium with organic acids such as stearic acid, lauric acid, ricinoleic acid, naphthenic acid, and 2-ethylhexanoic acid. Other examples of stabilizers include antioxidants, ultraviolet absorbers, and light stabilizers. Examples of antioxidants include hindered phenol-based antioxidants, phosphorus-based antioxidants, and sulfur-based antioxidants. Examples of ultraviolet absorbers include benzotriazole-based ultraviolet absorbers, triazine-based ultraviolet absorbers, benzophenone-based ultraviolet absorbers, cyanoacrylate-based ultraviolet absorbers, salicylate-based ultraviolet absorbers, and oxanilide-based ultraviolet absorbers. Examples of light stabilizers include various hindered amine-based light stabilizers, oxalic acid derivatives, salicylic acid derivatives, and hydrazine derivatives.

[0049] The lubricant is a component for facilitating release from the mold. Specific examples of the lubricant include low-density polyethylene oxide.

[0050] As the colorant, known pigments such as organic pigments, inorganic pigments, fluorescent pigments, and known dyes can be used. An example of an inorganic pigment is titanium oxide.

[0051] 2. Eraser The eraser according to the present disclosure is characterized by containing a vinyl chloride resin produced by suspension polymerization or bulk polymerization, a plasticizer, and a porous filler. The eraser has high break resistance and excellent erasability.

[0052] The eraser according to the present disclosure contains the porous filler in an amount of preferably 5 parts by mass or more and 500 parts by mass or less, more preferably 5 parts by mass or more and 100 parts by mass or less, even more preferably 8 parts by mass or more and 90 parts by mass or less, and most preferably 9 parts by mass or more and 75 parts by mass or less, relative to 100 parts by mass of the vinyl chloride resin. The inventors have found that when the ratio of the vinyl chloride resin to the porous filler is within the above range, an eraser having particularly high break resistance and erasability can be obtained.

[0053] The eraser according to the present disclosure contains a plasticizer in a ratio of preferably 100 parts by mass or more and 300 parts by mass or less, more preferably 150 parts by mass or more and 250 parts by mass or less, relative to 100 parts by mass of the vinyl chloride resin. When the plasticizer and the vinyl chloride resin are blended in this ratio, a portion of the plasticizer is used to gel the vinyl chloride resin, and the remaining plasticizer is absorbed and held by the porous filler, thereby maintaining hardness and providing an eraser with high break resistance and erasability.

[0054] The eraser according to the present disclosure may further contain a plasticizer in a proportion of preferably 80 parts by mass or more and 200 parts by mass or less, more preferably 100 parts by mass or more and 190 parts by mass or less, relative to 100 parts by mass of the total amount of the vinyl chloride resin and the porous filler. By blending the plasticizer, the vinyl chloride resin, and the porous filler in this proportion, a better balance between the absorption and exudation of the plasticizer is maintained, and an eraser with high folding resistance and erasability is obtained.

[0055] The eraser according to the present disclosure preferably further contains a non-porous filler. As described above, the non-porous filler not only imparts strength to the eraser but also contributes to improving erasability by erasing handwriting. The eraser according to the present disclosure more preferably contains the non-porous filler in an amount of preferably 30 to 200 parts by mass, more preferably 70 to 150 parts by mass, and more preferably 80 to 130 parts by mass, relative to 100 parts by mass of the vinyl chloride resin. Erasers containing the non-porous filler in this amount are particularly preferred because they have high breakage resistance and erasability.

[0056] The hardness of the eraser according to the present disclosure, measured in accordance with JIS S 6050:2002, is preferably 58 or more, more preferably 60 or more, more preferably 62 or more, more preferably 63 or more, more preferably 65 or more, more preferably 66 or more, and more preferably 58 or more and 95 or less, more preferably 60 or more and 95 or less, more preferably 62 or more and 95 or less, more preferably 62 or more and 95 or less, more preferably 62 or more and 93 or less, and most preferably 63 or more and 90 or less. Erasers according to the present disclosure having a hardness in this range are preferred because they have particularly high breakage resistance and erasability.

[0057] The eraser according to the present disclosure contains a vinyl chloride resin produced by a suspension polymerization method or a bulk polymerization method in a proportion of preferably 10% by mass or more and 45% by mass or less, more preferably 10% by mass or more and 40% by mass or less, based on the total amount of the eraser.

[0058] The eraser according to the present disclosure preferably contains a plasticizer in a proportion of 20% by mass or more and 60% by mass or less, more preferably 25% by mass or more and 50% by mass or less, based on the total amount of the eraser.

[0059] The eraser according to the present disclosure preferably contains the porous filler in a proportion of 2% by mass or more and 25% by mass or less, more preferably 4% by mass or more and 20% by mass or less, based on the total amount of the eraser.

[0060] The eraser according to the present disclosure preferably contains 10% by mass or more and 40% by mass or less, more preferably 15% by mass or more and 30% by mass or less of the non-porous filler relative to the total amount of the eraser.

[0061] The eraser according to the present disclosure may further contain other components as described in 1.5 above. The content of the other components is not particularly limited, but is preferably 5% by mass or less, more preferably 3% by mass or less, and even more preferably 2.5% by mass or less, based on the total amount of the eraser.

[0062] The eraser according to the present disclosure preferably contains, relative to the total weight of the eraser, 10% by mass or more and 45% by mass or less of vinyl chloride resin produced by suspension polymerization or bulk polymerization, 20% by mass or more and 60% by mass or less of plasticizer, 2% by mass or more and 25% by mass or less of porous filler, and 10% by mass or more and 40% by mass or less of non-porous filler, and may further contain 0% by mass or more and 5% by mass or less of the other components described in 1.5 above.

[0063] More preferably, the eraser according to the present disclosure contains, relative to the total weight of the eraser, 10% by mass or more and 40% by mass or less of vinyl chloride resin produced by suspension polymerization or bulk polymerization, 25% by mass or more and 50% by mass or less of plasticizer, 4% by mass or more and 20% by mass or less of porous filler, and 15% by mass or more and 30% by mass or less of non-porous filler, and may further contain 0% by mass or more and 3% by mass or less of the other components described in 1.5 above.

[0064] 3. Composition for Eraser Manufacturing The composition for eraser manufacturing according to the present disclosure contains a vinyl chloride resin produced by suspension polymerization or bulk polymerization, a plasticizer, and a porous filler. By molding the composition for eraser manufacturing according to the present disclosure under heated conditions, an eraser having the preferable break resistance and erasability described in 2 above can be obtained.

[0065] The composition for producing an eraser according to the present disclosure contains a porous filler in an amount of preferably 5 to 500 parts by weight, more preferably 5 to 100 parts by weight, even more preferably 8 to 90 parts by weight, and most preferably 9 to 75 parts by weight, relative to 100 parts by weight of vinyl chloride resin produced by suspension polymerization or bulk polymerization. A composition in which the ratio of vinyl chloride resin to porous filler falls within the above range can be molded under heated conditions to obtain an eraser having particularly favorable break resistance and erasability.

[0066] The composition for manufacturing an eraser according to the present disclosure contains a plasticizer in a ratio of preferably 100 to 300 parts by weight, more preferably 150 to 250 parts by weight, per 100 parts by weight of the vinyl chloride resin. When the plasticizer and the vinyl chloride resin are blended in this ratio, a portion of the plasticizer is used to gel the vinyl chloride resin, and the remaining plasticizer is absorbed and held by the porous filler, thereby maintaining hardness and providing an eraser with high break resistance and erasability.

[0067] The composition for manufacturing an eraser according to the present disclosure may further contain a plasticizer in a proportion of preferably 80 parts by mass or more and 200 parts by mass or less, more preferably 100 parts by mass or more and 190 parts by mass or less, relative to 100 parts by mass of the total amount of the vinyl chloride resin and the porous filler. By blending the plasticizer, the vinyl chloride resin, and the porous filler in this proportion, a better balance between the absorption and exudation of the plasticizer is maintained, and an eraser with high folding resistance and erasability can be obtained.

[0068] The composition for producing an eraser according to the present disclosure preferably further contains a non-porous filler. As described above, the non-porous filler not only imparts strength to the eraser but also contributes to improving erasability by erasing handwriting. More preferably, the eraser according to the present disclosure contains the non-porous filler in an amount of preferably 30 to 200 parts by mass, more preferably 70 to 150 parts by mass, and more preferably 80 to 130 parts by mass, per 100 parts by mass of the vinyl chloride resin. Erasers containing the non-porous filler in this amount are particularly preferred because they have high breakage resistance and erasability.

[0069] The composition for producing erasers according to the present disclosure contains a vinyl chloride resin produced by a suspension polymerization method or a bulk polymerization method in an amount of preferably 10% by mass or more and 45% by mass or less, more preferably 10% by mass or more and 40% by mass or less, based on the total amount of the composition.

[0070] The composition for producing an eraser according to the present disclosure preferably contains a plasticizer in an amount of 20% by mass or more and 60% by mass or less, more preferably 25% by mass or more and 50% by mass or less, based on the total amount of the composition.

[0071] The composition for producing an eraser according to the present disclosure preferably contains a porous filler in an amount of 2% by mass or more and 25% by mass or less, more preferably 4% by mass or more and 20% by mass or less, based on the total amount of the composition.

[0072] The composition for producing an eraser according to the present disclosure preferably contains a non-porous filler in an amount of 10% by mass or more and 40% by mass or less, more preferably 15% by mass or more and 30% by mass or less, based on the total amount of the composition.

[0073] The composition for producing erasers according to the present disclosure may further contain other components as described in 1.5 above. The content of the other components is not particularly limited, but is preferably 5% by mass or less, more preferably 3% by mass or less, and even more preferably 2.5% by mass or less, based on the total amount of the composition.

[0074] The composition for producing erasers according to the present disclosure preferably contains, relative to the total amount of the composition, 10% by mass or more and 45% by mass or less of vinyl chloride resin produced by suspension polymerization or bulk polymerization, 20% by mass or more and 60% by mass or less of plasticizer, 2% by mass or more and 25% by mass or less of porous filler, and 10% by mass or more and 40% by mass or less of non-porous filler, and may further contain 0% by mass or more and 5% by mass or less of the other components described in 1.5 above.

[0075] More preferably, the composition for producing erasers according to the present disclosure contains, relative to the total amount of the composition, 10% by mass or more and 40% by mass or less of vinyl chloride resin produced by suspension polymerization or bulk polymerization, 25% by mass or more and 50% by mass or less of plasticizer, 4% by mass or more and 20% by mass or less of porous filler, and 15% by mass or more and 30% by mass or less of non-porous filler, and may further contain 0% by mass or more and 3% by mass or less of the other components described in 1.5 above.

[0076] 4. Method for Producing an Eraser The method for producing an eraser according to the present disclosure comprises molding the above-described composition for producing an eraser according to the present disclosure under heating conditions.

[0077] The composition for producing an eraser to be used is preferably mixed uniformly in advance using a stirring means such as a blender.

[0078] Molding under heated conditions can be carried out at a temperature of, for example, 110° C. to 130° C., preferably 115° C. to 125° C. Molding under heated conditions causes the vinyl chloride resin to gel and soften. Examples of molding methods include injection molding and extrusion molding.

[0079] After molding under heated conditions, the eraser according to the present disclosure is obtained by cooling and cutting as necessary.

[0080] Experiment 1 <Materials> ・General-purpose PVC, manufactured by Kaneka PVC Corporation, Kanevinyl (registered trademark) S1003, degree of polymerization 1300, polyvinyl chloride homopolymer paste ・Plasticizer: Acetyl tributyl citrate (ATBC) ・Non-porous filler: Heavy calcium carbonate (average particle size 5.0 μm, oil absorption 18 mL / 100 g (see manufacturer's website)) ・Porous filler: Silica 1 (manufactured by Tosoh Silica Corporation, Nipsil VN3, specific surface area 210 m ２ / g (see catalog). Although not a catalog value, the oil absorption of silica 1 measured by the boiled linseed oil method specified in JIS K 5101-13-2:2004 is 180 to 200 mL / 100 g. Silica 2 (Nipsil ER, manufactured by Tosoh Silica Corporation, specific surface area 100 m) ２ / g (see catalog)). The measured oil absorption of Silica 2 by the boiled linseed oil method was 200 mL / 100 g. Magnesium carbonate (Kyowa Chemical Industry Co., Ltd., industrial magnesium carbonate). The measured oil absorption of the magnesium carbonate was 113 mL / 100 g. Zeolite (Shin Tohoku Chemical Industry Co., Ltd., Zeofil (registered trademark) CP50). The measured oil absorption of the zeolite by the boiled linseed oil method was 55 mL / 100 g. - Stabilizer: calcium zinc stabilizer - Lubricant: low-density polyethylene oxide

[0081] <Production Method> The above materials were uniformly mixed according to the composition shown in the table below to prepare a mixed material.

[0082] The prepared mixed material was molded using an extruder at a temperature of 120°C to produce an eraser. The produced eraser was appropriately cut to prepare samples of specified dimensions, which were used for the following evaluations.

[0083] <Evaluation> The erasability, hardness and breakage resistance of the eraser samples were evaluated according to the following procedures.

[0084] (Erasability) (1) The eraser was cut into a 5 mm thick plate, and the tip that came into contact with the colored paper was finished into an arc with a radius of 6 mm to prepare a test piece. (2) Using a line drawing machine, the eraser was cut into a 5 mm thick plate, and the tip that came into contact with the colored paper was finished into an arc with a radius of 6 mm to prepare a test piece. ２ As described above, colored paper was prepared using high-quality paper with a whiteness of 75% or more. A test piece was placed in contact with the colored paper perpendicularly and perpendicular to the colored line. A weight was placed on the test piece so that the sum of the weight and holder's mass was 0.5 kg, and the colored portion was rubbed off four times at a speed of 150±10 cm / min. (3) Using a densitometer, the density of the colored portion and the rubbed off portion were measured, with the density of the uncolored portion of the colored paper being set to 0. (4) The erasure rate was calculated using the following formula, and the average of three measurements was obtained: Erasure rate (%) = (1 - (density of rubbed off portion ÷ density of colored portion)) × 100. An erasure rate of 90% or more was deemed a pass (A), and one less than 90% was deemed a fail (F).

[0085] (Hardness) [Hardness (JIS method)] Compliant with JIS S 6050:2002 6.2. Using a hardness tester, the pressing surface of the tester was brought into contact with the surface of a test piece held horizontally so that the indenter of the tester was vertical, and the scale was immediately read.

[0086] (Bending property) (1) The eraser was cut into a plate with a thickness of 10 mm, and the tip that came into contact with the colored paper was finished into an arc with a radius of 6 mm to prepare a test piece. (2) Basis weight: 90 g / m ２ As described above, the test piece was placed vertically against a piece of wood-free paper with a whiteness of 75% or more, and perpendicular to the colored line, and a weight was placed on the test piece so that the sum of the weight and the holder's mass was 1 kg, and the test piece was rubbed back and forth at a speed of 150±10 cm / min. (3) The test piece was rubbed back and forth, and the number of times until the eraser broke was recorded. If the number of times of rubbed back and forth until the eraser broke was more than 100, it was judged as pass (A), and if it was 100 times or less, it was judged as fail (F).

[0087] <Results> The material composition and evaluation results of each sample are shown in the table below. In the table, "parts" refers to parts by mass, and "%" refers to % by mass.

[0088]

[0089]

[0090]

[0091] The eraser samples of Experiments Nos. 1 to 4, which contained general-purpose PVC, heavy calcium carbonate (non-porous filler), and Silica 1 (porous filler), had high hardness and good erasability and breakage resistance.

[0092] The eraser sample of Experiment No. 5, in which Silica 1 was omitted from the formulation of Experiment No. 3, and the eraser sample of Experiment No. 6, in which Silica 1 in the formulation of Experiment No. 3 was replaced with an equal amount of heavy calcium carbonate, had poor break resistance.

[0093] The eraser samples of Experiments Nos. 7, 8, and 9, in which Silica 1 in the formulation of Experiment No. 3 was replaced with another porous filler, Silica 2, magnesium carbonate, and zeolite, all had high hardness and good erasability and breakage resistance.

[0094] In Experiment No. 10, in which the general-purpose PVC in the formulation of Experiment No. 3 was replaced with paste PVC, the raw material mixture obtained by mixing the raw materials became a paste-like substance with an extremely high viscosity, making it impossible to mold an eraser using an extruder. The eraser sample in Experiment No. 11, in which Silica 1 was further omitted from the formulation of Experiment No. 10, in which the general-purpose PVC in the formulation of Experiment No. 3 was replaced with paste PVC, and the eraser sample in Experiment No. 12, in which Silica 1 in the formulation of Experiment No. 10 was replaced with an equal amount of heavy calcium carbonate, were able to be molded into erasers, but had very low hardness and poor breakage resistance.

[0095] Experiment 2 <Materials> General-purpose PVC, plasticizer, heavy calcium carbonate as a non-porous filler, silica 1 as a porous filler, stabilizer, and the materials described in Experiment 1 were used as a lubricant.

[0096] Furthermore, additional materials such as titanium oxide were used as needed.

[0097] <Production Method> The above materials were uniformly mixed in the composition shown in the table below to prepare a mixed material, and eraser samples were produced by the method described in Experiment 1.

[0098] <Evaluation> The erasability, hardness and breakage resistance of the eraser samples were evaluated according to the method described in Experiment 1.

[0099] <Results> The material composition and evaluation results of each sample are shown in the table below. In the table, "parts" refers to parts by mass, and "%" refers to % by mass.

[0100]

[0101] The eraser samples of Experiments Nos. 13, 14, and 15, which contained general-purpose PVC, heavy calcium carbonate (non-porous filler), and Silica 1 (porous filler), all had high hardness and good erasability and breakage resistance.

Claims

1. An eraser comprising a vinyl chloride resin produced by a suspension polymerization method or a bulk polymerization method, a plasticizer, and a porous filler.

2. The eraser according to claim 1, wherein the porous filler is contained in an amount of 5 parts by mass or more and 500 parts by mass or less per 100 parts by mass of the vinyl chloride resin.

3. The eraser according to claim 2, wherein the porous filler is contained in an amount of 5 parts by mass or more and 100 parts by mass or less per 100 parts by mass of the vinyl chloride resin.

4. The eraser according to any one of claims 1 to 3, wherein the porous filler comprises one or more selected from the group consisting of silica, magnesium carbonate, zeolite, porous calcium carbonate, algal ball-shaped calcium carbonate, porous alumina, porous acrylic resin, diatomaceous earth, perlite, kaolin, algal ball-shaped xonotlite, vermiculite, sepiolite, attapulgite, and porous quartz glass.

5. The eraser according to any one of claims 1 to 4, wherein the plasticizer is contained in an amount of 100 parts by mass or more and 300 parts by mass or less per 100 parts by mass of the vinyl chloride resin.

6. The eraser according to any one of claims 1 to 5, wherein the plasticizer is contained in an amount of 80 parts by mass or more and 200 parts by mass or less per 100 parts by mass of the total amount of the vinyl chloride resin and the porous filler.

7. The eraser according to any one of claims 1 to 6, wherein the vinyl chloride resin is contained in an amount of 10% by mass or more and 45% by mass or less based on the total amount of the eraser.

8. The eraser according to any one of claims 1 to 7, further comprising a non-porous filler.

9. The eraser according to claim 8, wherein the non-porous filler is contained in a proportion of 30 parts by mass or more and 200 parts by mass or less per 100 parts by mass of the vinyl chloride resin.

10. A composition for manufacturing an eraser, comprising: a vinyl chloride resin produced by a suspension polymerization method or a bulk polymerization method; a plasticizer; and a porous filler.

11. The composition for producing an eraser according to claim 10, wherein the porous filler is contained in a proportion of 5 parts by mass or more and 500 parts by mass or less per 100 parts by mass of the vinyl chloride resin.

12. The composition for producing an eraser according to claim 11, wherein the porous filler is contained in a proportion of 5 parts by mass or more and 100 parts by mass or less per 100 parts by mass of the vinyl chloride resin.

13. The composition for manufacturing an eraser according to any one of claims 10 to 12, wherein the porous filler comprises one or more selected from the group consisting of silica, magnesium carbonate, zeolite, porous calcium carbonate, algal-like calcium carbonate, porous alumina, porous acrylic resin, diatomaceous earth, perlite, kaolin algal-like xonotlite, vermiculite, sepiolite, attapulgite, and porous quartz glass.

14. The composition for manufacturing an eraser according to any one of claims 10 to 13, wherein the plasticizer is contained in an amount of 100 parts by mass or more and 300 parts by mass or less per 100 parts by mass of the vinyl chloride resin.

15. The composition for manufacturing an eraser according to any one of claims 10 to 14, wherein the plasticizer is contained in an amount of 80 parts by mass or more and 200 parts by mass or less per 100 parts by mass of the total amount of the vinyl chloride resin and the porous filler.

16. The composition for producing an eraser according to any one of claims 10 to 15, wherein the vinyl chloride resin is contained in an amount of 10% by mass or more and 45% by mass or less based on the total amount of the composition for producing an eraser.

17. The composition for producing an eraser according to any one of claims 10 to 16, further comprising a non-porous filler.

18. The composition for producing an eraser according to claim 17, wherein the non-porous filler is contained in a proportion of 30 parts by mass or more and 200 parts by mass or less per 100 parts by mass of the vinyl chloride resin.

19. A method for producing an eraser, comprising molding the composition for producing an eraser according to any one of claims 10 to 18 under heated conditions.

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