JPS6259157B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a plastic letter eraser that has particularly excellent erasability for handwriting written with oil-based ink on non-penetrating materials or oil stains on non-penetrating materials. Traditionally, when erasing oil-based ink marks on non-penetrating materials such as glass, metal, plastic plates, and plastic films, or removing oil stains, it is necessary to scrub the area with a brush dipped in detergent and then rinse with water. However, this method is time-consuming and has the disadvantage that it is difficult to process only small portions. For this reason, solid erasers that absorb ink solvent have been considered, but at present they do not have sufficient erasability. Therefore, based on the idea that a solid erasable type is basically suitable in terms of simplicity and operability, the inventors developed a medium erasable type in order to further improve erasability. The present invention was completed as a result of various studies on the substances to be contained in the liquid. That is, the present invention is based on a plastic eraser in which microcapsules containing at least a hygroscopic inorganic powder, a surfactant, and an organic solvent as core materials are contained in a base material mainly composed of a resin and a plasticizer. The main points are as follows. Although it is not clear why erasability improves when microcapsules containing hygroscopic inorganic powder, surfactant, and organic solvent as core materials are contained in a base material mainly composed of resin and plasticizer. , hygroscopic inorganic powder absorbs water, helps the surfactant function, and improves wetting with oil and oil-based ink; organic solvents
It is thought that this is the result of a synergistic effect: it works to dissolve the binder resin of oil and oil-based ink, and the eraser dust works as an abrasive that does not cause scratches. As mentioned above, the word "erasing" in the present invention has a broad meaning, including erasing ordinary handwritten characters, removing ink stains, and removing oil stains. Next, the present invention will be explained in detail. The base material is mainly composed of a resin and a plasticizer, and other stabilizers, fillers, etc. are added as appropriate. As the resin, most of the resins used in known plastic letter erasers can be used, but considering erasability, compatibility with other materials, stability during molding, etc., polyvinyl chloride, Particularly preferred is vinyl chloride-vinyl acetate copolymer. The amount used is preferably 30 to 45% by weight based on the total amount of paper. Examples of plasticizers include phthalic acid-based plasticizers such as dioctyl phthalate and dinonyl phthalate, adipine-based plasticizers such as dioctyl adipate, fatty acid-based plasticizers such as dioctyl azelate, and epoxy-based plasticizers such as epoxidized soybean oil, which is also used as a stabilizer. Plasticizers etc. are used. The amount used is 25 to 50% by weight of the total amount.
is preferred. As the stabilizer, various metal salts such as potassium stearate and barium stearate, phosphorus stabilizers such as trinonylphenyl phosphite, and the like are used. The amount used is preferably 5% by weight or less based on the total amount of the eraser. As the filler, inorganic fillers such as calcium carbonate, silicic acid, and talc are preferred. The amount used is preferably 20% by weight or less based on the total amount of eraser, if other materials are taken into consideration. Hygroscopic inorganic powders include sodium sulfate, disodium hydrogen phosphate, dipotassium hydrogen phosphate, sodium carbonate, barium chloride, copper sulfate, dihydrogen phosphate,
Ammonium, zinc sulfate, sodium sulfite, etc. can be used, but it is preferable that the humidity in a closed space is 80% or more at 20°C when made into a saturated solution with the coexistence of a solid phase. When powder is used, if the eraser is left in a place with high humidity, the hygroscopic inorganic powder may deliquesce over time and seep out through the pores in the eraser, which is undesirable. Also, the amount used is 5% by weight based on the total amount of eraser.
If it is less than 20% by weight, the effect will be relatively weak, and if it is more than 20% by weight, the eraser properties may deteriorate, so 5 to 20% by weight is preferable. Various surfactants can be used as the surfactant, but nonionic and anionic surfactants are preferred because they have less reactivity with other materials. The amount used is preferably 0.2 to 5% by weight, since the effect is not significant if it is less than 0.2% by weight, and the effect is not increased even if it is used more than 5% by weight. The capsule wall of microcapsules whose core material is an organic solvent is not particularly limited, as long as it does not break under the pressure during erase molding and when used, the organic solvent oozes out along with the eraser waste. However, in particular, the method filed earlier by the present applicant (Japanese Patent Application No. 53-37331 (Japanese Unexamined Patent Publication No. 54-128483), No. 53-37332 (Japanese Unexamined Patent Application No. 1988-128484) ) Silica particle aggregates are preferable because they fully satisfy the above conditions as well as chemical stability and stability over time. A wide range of organic solvents can be used as long as they can dissolve the binder resin or oil in the ink, but if you use a solvent whose boiling point is lower than the molding temperature during ink molding, there is a risk that it will break the capsule and volatilize. Therefore, it is preferable to use a solvent with a boiling point higher than the molding temperature (generally 110 to 130°C, although it varies depending on the base material) during erase molding. For example, 2-ethoxyethyl acetate, diethylene glycol monomethyl ether, and Ethylene glycol monomethyl ether, triethylene glycol monobutyl ether, diethylene glycol monohexyl ether, tetraethylene glycol monobutyl ether, tetraethylene glycol monopropyl ether, ethylene glycol monoacetate, ethylene glycol hexyl ether, morpholine, N-methylmorpholine, dimethyl tartrate, N-β-hydroxyethylacetamide, formaldehyde, N-methylformamide, dimethylformamide, dimethyl sulfoxide, sulfolane, monoethanolamine, ethylene glycol, diethylene glycol, thiodiglycol, triethylene glycol, pentyl acetate, tetrahydrofurfuryl alcohol, lactic acid Methyl, 2-pyrrolidone, N-methyl-2-pyrrolidone, hexamethylphosphoramide, and the like can be used alone or in appropriate combinations. In addition, if the amount of microcapsules whose core material is an organic solvent is less than 5% by weight based on the total amount, the effect will be small;
Further, if the content is more than 20% by weight, the eraser properties will deteriorate, so the content is preferably 5 to 20% by weight. Appropriate substances can be added to this core material to improve properties. In addition, pigments, fragrances, etc. may be added as appropriate in addition to the above-mentioned materials. Plastic erasers can be obtained by uniformly mixing and stirring these materials at room temperature or at elevated temperatures, and then heating and molding them. However, in this case, microcapsules whose core material is an organic solvent may be broken during stirring. To prevent this, it is preferable to thoroughly stir the other materials first, and then add and stir the microcapsules last. Furthermore, various commonly used methods such as casting, press molding, extrusion molding, and injection molding may be employed for the heat molding. Hereinafter, the present invention will be explained in more detail based on Examples, where "parts" in the Examples indicate "parts by weight." Example 1 PVC paste resin (vinyl chloride resin) 1000 parts Dioctyl phthalate 800 parts Dioctyl adipate 100 parts Sodium sulfate trihydrate powder 300 parts Sorbon T-80 (manufactured by Toho Chemical Co., Ltd., nonionic surfactant) 25 Part epoxidized soybean oil (manufactured by Adeka Argus Co., Ltd., 0
-130-P, stabilizer) 30 parts Calcium carbonate 100 parts Warm the above ingredients to 40℃ and use a homogenizer.
A homogeneous dispersion was obtained by stirring at 10,000 rpm for 5 minutes. In this uniform dispersion, diethylene glycol
A mixed paste consisting of 70 parts by weight and 50 parts by weight of magnesium carbonate was added to 26 parts by weight of silica fine particles (average particle diameter 12 mμ, surface area 200 m ² /g, apparent specific gravity 60 g /) in a stirring device equipped with a rotating blade. , rotation speed
140 parts by weight of microcapsules (200 mesh, all mesh) obtained by stirring at 1200 rpm for 1 minute were added and mixed to obtain a base material mixture for plastic erasers. . This mixed solution was press-molded (temperature: 120° C., 20 minutes) to obtain a plastic letter eraser of the present invention. The erasing performance of this eraser was excellent as shown in the table below. In the comparative example, a commercially available eraser (Lumoplast, manufactured by Städler AG, West Germany) which occluded ink solvent was used.

[Table] Furthermore, when the plastic eraser of the present invention is used for cleaning metal parts, etc., there is no need for washing with water, so there is no need to worry about rust. or,
The plastic character eraser of the present invention can of course be used for erasing pencil handwriting, and can also be used for erasing water-based ink handwriting, depending on the selection of solvents, etc., as shown in the table above.

Claims (1)

[Scope of Claims] 1. A plastic eraser containing microcapsules whose core materials are at least a hygroscopic inorganic powder, a surfactant, and an organic solvent in a base material mainly composed of a resin and a plasticizer. 2. The plastic letter eraser according to claim 1, wherein the capsule wall of the microcapsules is an aggregate of silica particles.