JPS5856360B2 - Eraser and its manufacturing method - Google Patents

Description

[Detailed Description of the Invention] This invention is useful for erasing handwriting written with a pencil, drafting lead, colored pencil, ink, oil-based or water-based ink, etc. on paper, tracing paper, drafting film, glass, metal, etc. The present invention relates to an effective eraser and a method for manufacturing the same.

In order to erase the handwriting as described above, a solvent (hereinafter referred to as erasing liquid) that dissolves the binder resin and/or dye contained in the handwriting is used, and this is applied onto the handwriting to erase the binder resin and dye. It is known that it is effective to make the handwriting appear by dissolving the dye and then removing it.

Therefore, the present applicant has developed an eraser that uses such an erasing method and has already filed a patent application (Japanese Patent Application No. 53-42).
No. 347).

This eraser is made by preparing inorganic wall microcapsules with an eraser as a core material and a silica fine particle aggregate as a peripheral wall, and these microcapsules are made of a resin, a plasticizer, and, if necessary, a filler and a stabilizer. It is dispersed in the eraser base material.

The silica particles used at this time have the property of gelling various liquid substances, so a layer in which the eraser is gelled by the silica is formed at the contact area between the peripheral wall of the silica particles and the eraser core material. .

In other words, microcapsules with a structure in which the eraser core substance is surrounded by a peripheral wall made of silica fine particles and a gelled layer of eraser liquid are obtained, so the liquid core substance seeps out compared to conventional inorganic wall microcapsules. Hateful.

Therefore, the eraser can be stably dispersed and retained in the eraser base without contact between the eraser base and the eraser, and the original function of the eraser, that is, the action of dissolving the binder resin and/or dye in the handwriting, can be maintained. It can be maintained for a long period of time.

The handwritten marks in which the binder resin and/or dye are dissolved by the eraser are adsorbed or wiped away by the action of the eraser base material, so that excellent erasing performance is exhibited.

In order to further ensure prevention of the extinguishing core substance from seeping out from the capsule wall, as a special embodiment of the above-mentioned prior invention, a thickener is added to the erasing liquid to make it highly viscous. Alternatively, it has been proposed to add a gelling promoter to the eraser throat in order to more firmly and reliably form the eraser gelled layer.

However, in this case, the eraser with high viscosity or the eraser with accelerated gelation has thixotropic properties, so when using the eraser, a small amount of the eraser and eraser waste may be mixed on the eraser surface of paper or film. In some cases, the phenomenon of adhesion was observed.

Therefore, the present invention has been made with the object of providing an eraser that can fully exhibit the excellent erasing performance of the eraser of the earlier invention described above, and which does not allow eraser debris to adhere to the erasing surface.

That is, the eraser according to the present invention comprises a core material made of a mixture of a solvent and inorganic powder that dissolves the binder resin and/or dye in handwriting, a peripheral wall part made of an aggregate of silica fine particles, and the core material and the peripheral wall part. Microcapsules composed of a gelled layer formed by the above are dispersed in an eraser base material composed of a resin, a gelatinous layer, and, if necessary, a filler and a stabilizer. It is.

Furthermore, it is an object of the present invention to provide a method for manufacturing the above-mentioned eraser, and the gist of the invention is to provide a method for manufacturing the above-mentioned eraser. A mixture of the following is added to a bed of silica fine particles in a stirring device equipped with a cutter to prepare microcapsules having the mixture as a core material and a silica fine particle aggregate as a peripheral wall, and further added with a resin and a plasticizer as necessary. The method is characterized in that the microcapsules are mixed and dispersed in a dispersion containing a filler and a stabilizer, and then heated and molded.

The eraser in this invention may contain a thickener to make the eraser highly viscous or a gelling promoter to promote gelation of the eraser, and may be dissolved in the eraser throat or gelled. This is done by adding inorganic powder that does not have this effect.

Since the obtained mixture of eraser and inorganic powder does not exhibit chicken-tropic properties, it is erased using an eraser in which this mixture is microencapsulated with silica particles as a core material and dispersed in an eraser base material. Even in such cases, it is possible to prevent eraser debris from adhering to the eraser surface due to the chicken-tropic property of the capsule core material.

Furthermore, by adding inorganic powder to the eraser, it is possible to prevent the eraser from seeping out from the capsule wall to the same extent as when adding a thickener or a gelling promoter.

In other words, in a mixture of eraser and inorganic powder, the eraser is maintained in the gaps between the inorganic powder particles by capillarity, so if such a mixture is encapsulated as a core material, the eraser The liquid will be less likely to seep through the walls.

Furthermore, since the core material itself is not easily deformed, capsule strength can be obtained even if the erasing liquid gel layer formed by the silica peripheral wall is not very strong, and the sealing performance of the core material can also be obtained.

On the other hand, also in this invention, due to the gelling action of silica, an erasing gel layer is formed at the contact area between the peripheral wall of the silica fine particles and the erasing core substance, and the erasing liquid gel layer forms on the peripheral wall of the silica fine particles and the erasing liquid gel layer. Microcapsules having a structure in which the erasing core substance is surrounded can be obtained by this method, such inorganic walled microcapsules are highly chemically stable and heat resistant, and the erasing liquid and the eraser base material do not come into contact with each other. The fact that the eraser can be stably dispersed and retained in the eraser base material for a long period of time is the same as in the prior invention described above.

When microcapsules having a peripheral wall of silica fine particles are dispersed in an eraser base material, the plasticizer in the eraser base material that comes into contact with the silica peripheral wall is gelled due to the gelling effect of silica described above, and the silica peripheral wall is A gelled layer of plasticizer is formed around the outer periphery.

It is thought that the plastic gelled layer provides a sense of unity between the eraser base material and the inorganic walled microcapsules, which are different from the eraser base material. It is presumed that the eraser of the present invention exhibits its excellent erasing effect because the microcapsules are destroyed and the eraser liquid, which is the core material, acts effectively on the handwriting.

As mentioned above, the erasing liquid used in this invention can be selected from a wide range of solvents that can dissolve the binder resin and/or dye contained in the handwriting without any particular restriction.
Ethoxyethyl acetate, diethylene glycol monomethyl ether, triethylene glycol monoethyl 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-methyl formaldehyde, dimethyl formamide, dimethyl sulfoxide, sulfolane, monoethanolamine, ethylene glycol, diethylene glycol, thioshifuricol, triethylene glycol, hentyl acetate, tetrahydrofurfuryl alcohol, methyl lactate, 2-pyrrolidone, Examples include N-methyl-2-pyrrolidone and hexamethylphosphoramide.

As the inorganic powder added to the eraser, any substance can be used as long as it easily reacts with the eraser and does not dissolve in the eraser or gel the eraser. For example, Various carbonates such as calcium carbonate and magnesium carbonate, metal oxides such as titanium oxide and zinc oxide, various metal powders, various pigments, silica sand, glass powder, etc. can be selected and used in consideration of the combination with extinguishing properties.

Care must be taken regarding the thread diameter of such inorganic powder because if too large particles are used, there is a risk of scratching the erased surface, especially when erasing a film or the like.

Generally, powder having a particle size of about 0.005 to 20 μm can be preferably used.

The amount of inorganic powder added varies depending on the type of inorganic powder and eraser, but generally it is 20% of the eraser.
~200 weight buns.

If the amount is more than this, the extinction content in the microcapsules will be low, and the retention of the extinction by the inorganic powder will be too strong, and the extinction effect may not be fully expressed when it is erased. Undesirable.

On the other hand, if the amount is less than this, the inorganic powder will not have sufficient effacement holding power, which is not preferable.

In addition, the silica fine particles that form the capsule wall have a particle size of 1 to loo
Particles having a diameter of mμ can be preferably used, and effective microencapsulation can be achieved by using a particle size within this range.

In addition, the amount used should be sufficient to coat the surface of the eraser-inorganic powder mixture and granulate it, and generally, the silica fine particles are used per ioo parts by weight of the eraser-inorganic powder mixture. Preferably, 10 to 200 parts by weight are used.

Depending on cost, surface properties, etc., an appropriate amount of silica fine powder may be added to various bentonites, aluminum oxide, carbon black, calcium carbonate, talc, kaolin, various pigments, magnesium carbonate, titanium oxide, zinc oxide, single metals, or polyethylene or nylon. It may be replaced with fine particles of plastic such as.

The eraser base material used in this invention is a conventionally used resin, such as polyvinyl chloride, vinyl acetate-vinyl chloride copolymer, and 30 to 200 parts by weight of a plasticizer is added to 100 parts by weight of this resin. A blended mixture can be preferably used, and fillers and stabilizers may be added to the base material as necessary.

When carrying out this invention, first, a mixture obtained by adding and mixing an inorganic powder to an erased eyelid is microcapsulated.

Microencapsulation is performed by coating the surface of fine particles of the eraser-inorganic powder mixture with fine silica particles.

In this invention, it is difficult to make the eraser-inorganic powder mixture into fine particles and then coat them with fine silica particles. Add the bulk masking-mineral powder mixture.

As a result, the surface of the erasing solution-inorganic powder mixture is once covered with fine silica particles while remaining in the form of a lump, but as it is stirred by the cutter, it becomes fine particles, and such fine particles are immediately covered with fine silica particles existing around them. Therefore, microencapsulation can be carried out efficiently in an extremely short period of time.

When performing microcapsules using the method described above using a high viscosity eraser in which a thickener such as a resin is dissolved in the eraser as the capsule core material, it is necessary to remove the silica with a cutter due to the stickiness of the high viscosity eraser. A phenomenon in which particles stick to the cutter in the form of lumps during agitation in a fine particle bed is also observed, but when the eraser-inorganic powder mixture is used as the core material, this mixture does not have adhesiveness, so it does not stick to the cutter. The particles are reliably and effectively finely divided and microencapsulated.

The thus obtained microcapsules have a structure in which the core substance of the eraser-inorganic powder mixture is surrounded by the peripheral wall of the silica fine particle aggregate and the eraser group gelling layer, and then the eraser base material is Mixed and dispersed in the dispersion liquid.

Dispersions of eraser base materials are prepared by mixing resins, plasticizers, fillers, and stabilizers, and various viscosity can be used ranging from low viscosity to paste-like dispersion.

The blending ratio of the eraser microcapsules is preferably 1 to 100 parts by weight per 100 parts by weight of the resin.

The mixed dispersion of the eraser base liquid and the eraser group microcapsules is then heat-molded by extrusion molding, injection molding, cast molding, etc. in a conventional manner to obtain an eraser product.

As explained above, the eraser according to the present invention has chemically and thermally stable inorganic wall microcapsules in the eraser base material, with silica fine particles as the peripheral wall and core material of the eraser-inorganic powder mixture. Since it is a dispersed product, there are no restrictions on the type of erasing material that can be incorporated into the inorganic material wall, and even if the capsules are dispersed in the eraser base material, they will not be affected chemically by the base material components. Furthermore, there is no need to worry about thermal deterioration of the capsule during heat molding of the eraser.

Furthermore, the microcapsules used in the present invention have a structure in which the core substance of the eraser liquid-inorganic powder mixture is surrounded by the peripheral wall of the silica fine particles and the eraser gel layer. The eraser is retained in the gaps between the powder particles by capillary action, and the core material itself is difficult to deform, so the eraser seeps out to the outside of the capsule wall. The eraser can be stably dispersed and retained in the eraser base material without contact with the eraser, and the original eraser function, that is, the function of dissolving the binder resin and/or dye in the handwriting, can be maintained for a long period of time. can.

Handwriting in which the binder resin and/or dye has been dissolved by the eraser is adsorbed or wiped away by the action of the eraser base material, resulting in excellent erasing performance that cannot be obtained with ordinary erasers. Since the masking-inorganic powder mixture does not have thixotropic properties, it is possible to prevent eraser debris from adhering to the eraser surface.

The present invention will be further explained below with reference to Examples.

Example 1 120 g of paste made by mixing 70 g of pentaethylene glycol monomethyl ether with 50 g of light calcium carbonate
Silica fine particles (average particle diameter 12 mμ, surface area 200 m/g, apparent specific gravity 60 g/l) being stirred in a stirring device with an internal capacity of 1200 cc equipped with a rotating blade 24,
F and stirring for 2 minutes at a rotational speed of 1200 rpm to obtain free-flowing white powder microcapsules 14 (Bi') with a 200-mesh wire mesh.

Separately, the following components were sufficiently mixed using three rolls to prepare an eraser base dispersion.

Polyvinyl chloride 151 (product name IGeon 1211 dioctyl phthalate manufactured by Nippon Zeon)
80g dioctyl adipate
2 (Bi'Ca-Zn stabilizer
5g (Product name: ``7-ri5C-321'' manufactured by Azoga Argus ■
) Ritopone 2g
Calcium carbonate 3 (1) 50 g of the microcapsules were added to this base material dispersion, mixed and dispersed, and the mixed dispersion was pressed at 120° C. for 10 minutes to obtain an eraser of the present invention.

Table 1 shows the results of comparing the erasing rate of this eraser with that of a commercially available vinyl chloride eraser.

Example 2 200 g of paste l-200 g of active zinc white mixed with 100.9 g of dimethyl adipate was mixed with silica fine particles (average particle size 7 mμ, surface area 380 rn :/jj, apparent specific gravity 60 g/l).

After stirring for 1 minute at a rotational speed of 200 rpm, 20 g of magnesium carbonate was added to the stirring device and stirred for another 1 minute to obtain 247 g of microcapsules passed through a 200-mesh wire mesh.

Separately, the following components were thoroughly mixed using a Henschel mixer to prepare an eraser base dispersion.

Vinyl acetate-vinyl chloride copolymer 150g Dioctyl phthalate 100g Dioctyl adipate 1-30g Ba-Zn stabilizer
5g titanium dioxide
2g magnesium carbonate
20g green face sting 0.2g
65 g of the microcapsules were added to this base material dispersion, mixed and dispersed, and the mixture was press-molded at 120° C. for 15 minutes to obtain the eraser of the present invention.

The erasing rate of this eraser was as shown in Table 2, and was extremely excellent.

Furthermore, no eraser dust was observed to adhere to the writing surface.

Example 3 A paste prepared by mixing 50 g of diethylene glycol monobutyl ether with 40 g of magnesium carbonate was mixed with fine silica powder (average particle size 12 mμ, surface area 200 m/g) in a stirring device with a rotating blade and a capacity of about 1 liter. , apparent specific gravity 609/11) added to 25g, rotation speed 10
200 by stirring for 2 minutes at 000 rpm.
White microcapsules (A)lli of mesh were obtained.

In addition, 1 g of microcapsules (B) were prepared in the same manner as above except that diphenyl ether 51 was used instead of diethylene/y'' IJ col monobutyl ether.
I got it.

By mixing 31 each of these microcapsules (4) and (B), the same eraser base material dispersion 1281 as used in Example 1 was prepared.
The mixed dispersion was press-molded at 120'c for 20 minutes to obtain an eraser.

The erasing performance of this eraser was as shown in Table 3, and was extremely excellent.

Furthermore, no eraser dust was observed to adhere to the writing surface.

Claims (1)

[Scope of Claims] 1. A core material made of a mixture of a solvent that dissolves the binder resin and/or dye in the handwriting and an inorganic powder, a peripheral wall part made of an aggregate of silica fine particles, and the core material and the peripheral wall part What is claimed is: 1. An eraser characterized in that microcapsules comprising a gelled layer formed by the above are dispersed in an eraser base material comprising a resin, a plasticizer, and optionally a filler and a stabilizer. 2. A mixture of a solvent that dissolves the binder resin and/or dye in the handwriting and an inorganic powder is added to a bed of silica fine particles in a stirring device connected to a cutter, and the mixture is bound to a core material to form a silica fine particle aggregate. An eraser characterized in that microcapsules to be used as a peripheral wall are prepared, the microcapsules are mixed and dispersed in a dispersion liquid consisting of a resin, a plasticizer, and optionally a filler and a stabilizer, and then heated and molded. Production method.