JP2008194914A - Plastic eraser - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a plastic eraser, especially of a type using a polyvinyl chloride resin, which can restrain the blooming of a plasticizer and shows excellent erasing performance. <P>SOLUTION: This plastic eraser has both surfaces or the outer peripheral surface of a plastic erasing material such as a polyvinyl chloride erasing material containing the plasticizer. Both the surfaces or the outer peripheral surface are covered with plasticizer-free erasing materials obtained by blending a base such as polyisoprene, a styrene-butadiene copolymer or the like with a softener etc. The eraser can be obtained by two-color molding, coating, pressing, adhesion, etc. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a plastic eraser, and more particularly to a plastic eraser that can suppress a plasticizer transition that is likely to occur particularly in a polyvinyl chloride eraser and has an excellent erase ability.

  Plastic eraser is widely used as it is indispensable for erasing writing lines because of its excellent erasing power. For plastic eraser, generally, a plasticizer is blended into the base material and, if necessary, eraser materials such as stabilizers, coloring agents, and fragrances are added and mixed as appropriate, followed by press molding, injection molding, extrusion molding. It is manufactured by heating and molding by a molding method such as As the substrate, polyvinyl chloride resin, polyvinylidene chloride resin, styrene-butadiene copolymer resin, vinyl acetate resin, ethylene-vinyl acetate copolymer resin, acrylate resin, and the like are used. Of these, the mainstream of plastic erasing is the use of polyvinyl chloride resin because of its excellent erasing power.

  Plasticizers are used for imparting flexibility, durability, cold resistance, electrical properties, etc. to various base materials. In plastic erasing, from the aspect of erasing power, they are erasable substances. A plasticizer having an affinity for graphite or the like is frequently used. As such plasticizers, plasticizers of phthalic acid type, fatty acid type, phosphoric acid type, polyester type and the like are known, and among them, di-2-ethylhexyl phthalate, butylbenzyl phthalate, diphthalate diphthalate Phthalic acid plasticizers such as n-butyl, dicyclohexyl phthalate and diethyl phthalate are generally used. In recent years, fatty acid ester plasticizers have also been used.

  However, in the case of the above-mentioned plastic eraser, there is a phenomenon that the plasticizer contained in the base material moves to the erased surface and adheres to stationery such as paper, pencil, ruler, writing instrument case, etc. . However, in order to obtain a good erasing power, it is necessary to flexibly form a plastic erasure, and for that purpose, a plasticizer and a softening agent are indispensable. Although it has been proposed to use a plasticizer having a high affinity for the substrate, it is difficult to completely eliminate the migration of the plasticizer. For this reason, paper is generally wrapped around plastic erasers.

  Patent Document 1 proposes a thin rod-shaped replacement eraser for mechanical pencils which has improved bending strength by combining hard and soft erasure materials mainly composed of a plastic resin and a plasticizer. However, this eraser is inferior in erasing power because the hardness is adjusted by changing the blending ratio and molding conditions of the plasticizer and filler blended in the resin.

Similarly, as an example in which a plurality of materials are combined, in Patent Document 2, a thin layer of plastic such as polymethyl methacrylate and polyvinyl chloride having a thickness of 5 to 200 μm is formed on both sides of the eraser base material. An eraser has been proposed in which the cohesiveness of the eraser is improved. However, this eraser is also inferior in erasing power because the erasing power of the plastic thin layer portion is poor.
JP-A-11-309991 (Claim 1, paragraph number 0014, etc.) Japanese Utility Model Publication No. 1-174196 (claims)

  It is an object of the present invention to provide a plastic eraser that can suppress the migration of a plasticizer particularly in eraser using a polyvinyl chloride resin and is excellent in eraser power.

  As a result of intensive research to solve the above problems, the present inventor has coated a polyvinyl chloride erasure material containing a plasticizer with an erasure material containing no plasticizer, so that the plasticizer is transferred. As a result, the present inventors have found that it can be a plastic eraser with excellent erasability.

That is, the present invention is as follows.
1) Plastic eraser characterized by covering both sides or outer peripheral surface of a plastic eraser containing a plasticizer with an eraser containing no plasticizer.
2) The plastic eraser as described in 1) above, wherein the plastic eraser base material is a polyvinyl chloride resin.
3) The plastic eraser according to 1) or 2) above, wherein the eraser base material containing no plasticizer is at least one substrate selected from polyisoprene and styrenic elastomers.
4) The plastic eraser according to any one of 1) to 3) above, wherein the thickness of the eraser containing no plasticizer is 0.5 to 5 mm.
5) Two-color molding of a plastic erasing material containing a plasticizer and an erasing material containing no plasticizer, application of a erasing material containing no plasticizer to a plastic erasing material containing a plasticizer, or a plasticizer The plastic eraser according to any one of the above 1) to 4), which is formed by pressure bonding or adhesion of a plastic eraser containing selenium and an eraser containing no plasticizer.

  The plastic eraser of the present invention is flexible and easy to use, safer because it can suppress the migration of the plasticizer contained in the polyvinyl chloride eraser, and has excellent erasing power. Yes. Further, since the migration of the plasticizer can be suppressed, it is possible to eliminate the inconvenience of adhesion by contact with other stationery or paper.

  In the present invention, the plastic eraser is prepared by mixing a plasticizer with a base material, adding a stabilizer, a coloring agent, a fragrance, etc. as necessary, and stirring and mixing them uniformly. These are heated and molded by a molding method such as extrusion molding. Examples of the base material include resins for erasable materials such as polyvinyl chloride resins, polyvinyl acetate resins, ethylene-vinyl acetate copolymer resins, and polyacrylate resins. Among these resins, a polyvinyl chloride resin that is easily mixed with a plasticizer is particularly preferable.

  Polyvinyl chloride resins include polyvinyl chloride, polyvinylidene chloride, vinyl chloride-vinyl acetate copolymer, vinyl chloride-methyl acrylate copolymer, vinyl chloride-methyl methacrylate copolymer, and vinyl chloride-octyl acrylate. A copolymer etc. are mentioned. The form of the vinyl chloride resin is preferable in that the paste resin is easy to mix and process with a plasticizer or the like.

  The proportion of the base material in the total amount of the composition constituting the plastic eraser is preferably 10 to 90% by mass, particularly preferably 10 to 70% by mass, based on the total amount of the composition.

  Moreover, 20-300 mass parts is preferable with respect to 100 mass parts of base materials, and, as for the compounding quantity of a plasticizer, Most preferably, it is 60-200 mass parts. If the blending amount of the plasticizer is less than 20 parts by mass, the erasing becomes hard and the elasticity is lowered, and the erasing force may be lowered. On the other hand, if it exceeds 300 parts by mass, it is difficult to mold and use as an erasing becomes difficult Cheap.

  Examples of plasticizers include di-2-ethylhexyl phthalate (DOP), butyl benzyl phthalate (BBP), di-n-butyl phthalate (DBP), dicyclohexyl phthalate (DHP), and diethyl phthalate (DEP). Phthalic acid plasticizers, sebacic acid plasticizers such as dibutyl sebacate (DBS), di-2-ethylhexyl sebacate (DOS), dimethyl sebacate (DMS), trimellitic acid, phosphoric acid, pyro Those selected from merit acid-based, epoxy-based, adipic acid-based, and citric acid-based plasticizers can be used alone or in combination of two or more.

  The plastic eraser may contain a filler in order to impart an appropriate hardness. As the filler, generally finely divided silica stone powder or limestone powder is used. In addition, diatomaceous earth, talc or shirasu powder, aerosil which is a fine powder of silicon oxide, inorganic and organic hollow particles, and the like can be used. Although the usage-amount of these fillers is not restrict | limited in particular, It is preferable that it is 10-120 mass parts with respect to 100 mass parts of base materials, Most preferably, it is 20-100 mass parts.

  Further, if necessary, a stabilizer is used in order to prevent deterioration at a high temperature due to the base material, particularly the polyvinyl chloride resin. A preferable amount of the stabilizer is 0 to 10 parts by mass with respect to 100 parts by mass of the base material. Light stabilizers such as ultraviolet absorbers can also be blended. In addition, additives such as viscosity modifiers, lubricants, solvents, colorants, preservatives, antifungal agents, and fragrances can be blended. The blending amount of these additives is not particularly limited.

  In the present invention, the eraser that does not contain a plasticizer is added with a softener, a stabilizer, a colorant, a fragrance, etc., as necessary, to at least one or two or more base materials selected from various elastomers. Is. These base materials can be used alone or in combination of two or more thereof, and these base materials may be mixed with a resin such as ethylene-vinyl acetate copolymer resin.

  Examples of elastomers include polyisoprene (natural rubber) and styrene, butadiene, isoprene, ethylene-propylene, nitrile, chloroprene, urethane, acrylic, polyester, and olefin elastomers. . Among these, polyisoprene and styrene-based elastomer are preferable. Styrenic elastomers are similar in elasticity and mechanical strength to natural rubber, and have the performance as an eraser, that is, an eraser, without using a plasticizer, so that it is easy to avoid the influence of plasticizer migration.

  Examples of the styrene elastomer include a styrene-butadiene-styrene copolymer, a styrene-isoprene-styrene copolymer, a styrene-ethylenebutylene-styrene copolymer, and a styrene-ethylenepropylene-styrene copolymer.

  As the softening agent, those selected from petroleum oils, liquid rubbers, liquid oligomers and the like can be used alone or in combination of two or more. Examples of petroleum oils include extender oil, which is a mixture of paraffinic hydrocarbon oil, naphthenic hydrocarbon oil, and aromatic hydrocarbon oil, process oil, spindle oil, machine oil, liquid paraffin, chlorinated paraffin, etc. It is done. Examples of the liquid rubber include liquid polybutadiene and liquid polyisoprene. Examples of the liquid oligomer include liquid polybutene and liquid α-olefin oligomer.

  The blending amount of the softening agent is preferably 0 to 300 parts by mass, particularly preferably 5 to 100 parts by mass with respect to 100 parts by mass of the base material. When the blending amount of the softening agent exceeds 300 parts by mass, it becomes difficult to mold and use as an eraser tends to be difficult.

  In the plastic eraser of the present invention, both sides or the outer peripheral surface of a plastic eraser containing a plasticizer are coated with an eraser containing no plasticizer. The coating method is not particularly limited. For example, (1) a method of integrally molding (two-color molding) while extruding the plasticizer-containing plastic eraser and the plasticizer-free eraser simultaneously with an extruder. (2) A method in which a solution or emulsion in which a powder of a erasable material not containing a plasticizer is dissolved or dispersed in a solvent is applied to the molded plasticizer-containing plastic erasable material, (3) a molded plasticizer-containing plastic erasant A method of pressing and integrating a character material and an eraser material not containing a plasticizer, or (4) bonding a molded plasticizer-containing plastic eraser material and an eraser material not containing a plasticizer using an adhesive And a method of integrating them. As the adhesive, a nitrile rubber-based or synthetic rubber-based adhesive can be used, and a nitrile rubber-based adhesive is particularly preferable.

  As a covering form, there is a method in which both sides of a plastic eraser containing a plasticizer are coated with an eraser containing no plasticizer. Here, double-sided means the top and bottom or the left and right two sides having the maximum surface area for erase. The eraser is usually placed so that a large area surface is in contact with the desk or paper surface, and when used, it tends to be consumed evenly from the four corners or both corners. Transition to plastics or paper can be suppressed. In the case of double-sided coating, a plastic erasing material containing a plasticizer and an erasing material not containing a plasticizer are integrated by integral molding, crimping or bonding, and then cut into an appropriate size for commercialization. Because it is possible, it is also economical. Of course, in order to suppress the migration of the plasticizer, the outer peripheral surface (4th to 6th surfaces) of the plastic eraser containing the plasticizer can be covered with an eraser containing no plasticizer. In this case, even if the eraser is taken out from the paper roll, the transition can be suppressed.

  The thickness of the eraser material that does not contain a plasticizer used as a coating material is preferably in the range of 0.5 to 5 mm. If there is a thickness of 0.5 mm or more, the plasticizer can be made difficult to migrate, If it is 5 mm or less, the erasing power is not adversely affected. In the plastic eraser of the present invention, since the rubber-based eraser used for coating has an erasing force, it is erased like an eraser covered by a method of laminating a plastic film or applying a resin solution. There is no bad literacy.

  EXAMPLES Hereinafter, although this invention is demonstrated further more concretely using an Example and a comparative example, this invention is not limited to a following example.

(Example 1)
A composition in which each component was blended at a blending ratio shown in Table 1 (numbers are parts by mass) was stirred and mixed under reduced pressure, and then molded to prepare a vinyl chloride eraser and an elastomer eraser. In the table, PVC is a polyvinyl chloride resin (paste resin powder, average polymerization degree 1650), and SBR is a styrene-butadiene-styrene copolymer (pellet-like, styrene / butadiene = 40/60 (mass ratio)).

  After the obtained vinyl chloride-based eraser was cut into a size of 15 mm in length, 35 mm in width, and 6 mm in height, an SBR-based eraser with a thickness of 2 mm was pressure-bonded on both sides with a size of 15 mm × 35 mm. It was integrated to create an eraser.

(Example 2)
In Example 1, the eraser was produced in the same manner as in Example 1 except that the height of the vinyl chloride eraser was 10 mm and the thickness of the SBR eraser was 1 mm.

(Example 3)
The SBR-based erasable material having a thickness of 2 mm was pressure-bonded and integrated with the outer peripheral surface (six surfaces) of the vinyl chloride-based erasable material obtained in Example 1 to produce an erasure.

Example 4
A polyisoprene (natural rubber) erasable material having a thickness of 2 mm was pressure-bonded and integrated on both surfaces of the vinyl chloride erasable material obtained in Example 1 to produce an erasure.

(Comparative Examples 1-2)
A composition in which each component was blended at a blending ratio shown in Table 1 (numbers are parts by mass) was stirred and mixed under reduced pressure, and then molded to prepare a vinyl chloride eraser.

  About each obtained erasing, transferability and erasing power (%) were measured and evaluated based on JIS S6050. The results are also shown in Table 1. The measurement and evaluation methods are as follows.

(1) Transferability A pencil is cut to a length of 40 mm, placed in parallel on the eraser (with respect to the long side of the test piece), a 20 g weight is placed on it, and a 60 ± 2 ° C incubator. The sample was taken out after 1 hour, and it was examined whether or not the pencil paint adhered to the test piece, and evaluated according to the following criteria. In addition, in order to carry out a strict test, the transferability after 6 hours and after 24 hours was examined.
◎: No problem ○: Adhesion (no paint migration)
△: Some transition of paint ×: Complete transition of paint

(2) Erase rate The line drawn with the pencil HB on the colored paper was friction-erased with an erasing load of 500 g and calculated from the density at that time.

  From the results in Table 1, it can be seen that the plastic eraser according to the example is clearly less likely to migrate than the case of only the polyvinyl chloride eraser, although adhesion of the paint is recognized. And the plastic eraser which concerns on an Example has the performance equivalent to or more than the conventional plastic eraser which concerns on Comparative Examples 1-2. The plastic erasing performance has a target quality of erasing power of 90% or more, so the product of this example has a performance that satisfies it.

  The plastic eraser according to the present invention can be conveniently used in offices, schools, homes, factories and the like because the plasticizer migration is suppressed.

Claims (5)

  A plastic eraser characterized in that both sides or the outer peripheral surface of a plastic eraser containing a plasticizer are coated with an eraser containing no plasticizer.   The plastic eraser according to claim 1, wherein the plastic eraser base material is a polyvinyl chloride resin.   The plastic eraser according to claim 1 or 2, wherein the base material of the eraser containing no plasticizer is at least one base material selected from polyisoprene and styrene elastomer.   The plastic eraser according to any one of claims 1 to 3, wherein the thickness of the eraser containing no plasticizer is 0.5 to 5 mm.   Two-color molding of plastic erasing material containing plasticizer and erasing material containing no plasticizer, application of erasing material containing no plasticizer to plastic erasing material containing plasticizer, or containing plasticizer The plastic character eraser according to any one of claims 1 to 4, wherein the plastic character eraser is formed by pressing or bonding a plastic eraser material and an eraser material not containing a plasticizer.