JPS5854040B2 - plastic shavings - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to the creation of a plastic expendable material, which has excellent erasability, is free from migration, which is an essential defect in conventional plastic expendable materials, and has good workability. They are trying to get the product.

Plastic waste materials have been known for a long time, but this conventional plastic waste material has a plasticizer migration property, that is, it transfers to pencil paint, etc. when exposed to water under conditions of contact. However, it is inevitable that undesirable colored areas and partial fading will occur.

Furthermore, although the eraser performance is not necessarily good and there are certain advantages in the appearance and appearance of the product, a product that is suitable for practical use in terms of earthy odor has not yet been obtained.

The present inventors conducted research to obtain a plastic material that does not have the disadvantages and drawbacks of the conventional materials as described above.
0 year patent application No. 60183 was completed.

That is, according to the invention of this prior application, it is possible to obtain a product that does not have migration properties and has desirable erasability.

The present invention is an improvement on the prior invention, and is capable of producing the above-mentioned letter erasable material with no migration and excellent erasability, with good workability, and with improved quality. We succeeded in obtaining an excellent product, which is a product made by blending ethylene propylene rubber and white sub into a copolymer of polyethylene and polypropylene, and mixing and kneading glycerin or its derivatives with the necessary fillers and pigments. As a plastic material, a copolymer of polyethylene and polypropylene is used instead of a hinyl acetate-based material, which improves the workability of kneading. The product has the strength and feel suitable for a disposable plastic material, and by using such a plastic base material, there is no need to use phthalate-based plasticizers, which are indispensable in conventional plastic disposable materials. By making it possible to use glycerin or its derivatives as described above, and by blending ethylene propylene rubber and white sub into such plastic materials, it is possible to obtain favorable manufacturing conditions and ensure good erasing performance. Moreover, it is possible to obtain a material with excellent character even when it comes to feel and other qualities.

The formulation data and proportions of the product according to the present invention as described above are explained below.

Copolymer of polyethylene and polypropylene 300 parts by weight Ethylene propylene rubber 11-100 parts by weight Preferably 1
Shikuba 20-60 parts by weight White cloth 20-500 parts by weight, preferably 1 Shikuba 50-400 parts by weight Glycerin 10-150 parts by weight, preferably 20-60 parts by weight Filler O-300 parts by weight Pigment
O ~ 50 parts by weight The copolymer with polyethylene and propylene constitutes the plastic base material used in the plastic waste material of the present invention, and the plastic waste material is formed mainly from this copolymer. This makes manufacturing work using cross-wire rolls and other methods much easier than when vinyl acetate or other plastics are used, and the product is stable in quality even without adding sulfur or going through a vulcanization process. In any case, the desired product can be obtained through a simple process.

In addition, ethylene propylene rubber is blended to easily adapt to the blending amount of the plastic base material as described above and to facilitate the molding operation, and if it is less than 10 parts by weight, it will be too hard and the erasing rate will drop significantly. and that is 10
If it exceeds 0 part by weight, it will be too flexible and will not be a desirable erasable material, and the erasing rate will similarly decrease.

Furthermore, glycerin or a derivative thereof is added as a plasticizer, and it is necessary to add at least 10 parts by weight to the above-mentioned amount of the plastic base material, but it should not be more than 150 parts by weight. If this happens, the product becomes brittle and difficult to roll.

In addition, by employing such glycerin or its derivatives as a plasticizer, the feel of the product is made smooth, and eraser waste is not dry, thereby making it possible to create a product that does not scatter unnecessarily.

However, the white sub occupies an important position in ensuring an effective erasing effect for the character erasing material of the present invention, and it is
If the amount is less than parts by weight, the effect of improving erasing performance is extremely small.

Furthermore, if more than 500 parts by weight of this white sub is blended, it will be difficult to mold into a predetermined molded product by extrusion molding or the like, which is suitable for use as an extinguishable material. When the erasing operation is performed, a large amount of erasing slag is generated, making it impossible to obtain a desirable product.

As a filler, heavy calcium carbonate or titanium oxide is selected, but this titanium oxide is also used as a white pigment in buttons for the purpose of imparting a white color to products. Fillers and pigments that give product colors such as red, blue, and green are used as appropriate, and zinc white is also used as a white pigment, but in any case, these fillers and pigments are suitable for the desired product. Add appropriate amount.

However, it is preferable to mix silica powder and glass powder as fillers.The added silica powder densifies the structure of the product, and the glass powder appropriately grinds the paper quality to improve erasability. Furthermore, since smoothness is imparted to the erasable effect, any product containing these materials will have improved quality as a plastic erasable material.

The above-mentioned formulation is heated to 110-125°C after kneading.
The desired product is formed by extrusion molding or press molding under moderately heated conditions.

To explain the manufacturing process, the above-mentioned plastic material, ethylene polypropylene rubber, is blended in a □-ru with a surface temperature of about 60 to 90°C, and then glycerin or its derivatives, white powder, filler, and pigment are added. Knead well, and at this time set the above roll temperature to 40-60.
Cool gradually to °C.

To mold the thus kneaded product, proceed as described above.
Molding is carried out using either extrusion molding or press molding under heating conditions of 10 to 125°C.The molding conditions for press molding are approximately 15 minutes under the above temperature conditions, and for extrusion molding, the head portion of the extruder is heated at 110°C. Extrusion molding is performed sequentially by heating back and forth.

The obtained molded product is cooled to room temperature with a machine and then cut into appropriate dimensions to produce a product.

Some specific examples according to the present invention and their erasure rates are as follows.

That is, formulation A1 is one of the most preferred embodiments of the present invention.

On the other hand, the hardness of compound A2 is higher and it feels like a slightly aged eraser, but if you know how to use it, for example, you can use it as a Naoji eraser. In addition, in the case of formulation A3, the glycerin is wintery and tends to lack morphological stability, but if it is made into a block eraser material, it can be put to practical use.

Also, those with blending layer 4 tend to have poor smoothness during erasing operations, and those with blending layer 5 are somewhat rough and tend to damage the paper quality, but both of them are suitable for use with paper, such as crayons and ballpoint pens. If it is used for the purpose of erasing characters, it can be used almost appropriately.

In the above case, blending and mixing are first carried out using a kneading roll with a surface temperature of 80°C, and after adding plasticizers, fillers, pigments, etc., the surface temperature is gradually lowered to about 50°C. During extrusion molding, the head portion was held at 110'C.

Copolymers of polyethylene and polypropylene are manufactured by Mitsubishi Yuka Co., Ltd. under the trade names EPT-07 and EPT-2.
4, and the ethylene propylene rubber was also manufactured by Mitsubishi Yuka.

However, the glycerin used as a plasticizer was commercially available, and the heavy calcium carbonate produced in Okayama Prefecture was used.

However, silica powder is a fine powder of 100 to 150 mesh.
Fine glass powder of 150 to 200 mesh was used.

Furthermore, the erasing rate shown in the table above was measured at a test speed of 36 cr using a testing machine that follows the test method specified in JIS 56004.
/L/min, test, test load of 500g, and the number of times of abrasion (reciprocating) was measured, and each formulation example containing 100 parts by weight or more of white subs all showed good test results. .

In addition, a migration test was carried out separately for each product as described above. That is, a commercially available pencil with a surface coating layer was cut into 40 mm pieces, and this was cut into 2 pieces in parallel with each test piece (product) of the above formulation example of 35 x 15 x 5 mm. Test pieces of paint components that are polymerized, placed in a thermostat at 50±2°C for 360 minutes under a load of 40 g, and then taken out and pressed onto the pencil coating layer (
The state of adhesion to the eraser material was examined, but almost no change could be detected in any of the test pieces.

In addition to the above-mentioned formulation example, the present inventor also prepared and manufactured a formulation using triethylene glycol as a glycerin derivative in place of the glycerin in formulation layer 1, and the resulting product was obtained. The performance and condition were almost the same.

In addition, when obtaining the same white product as a pigment, a mixture of zinc sulfide and barium sulfide (trade name Lidhon) or zinc white was used in place of the titanium oxide in the above formulation example, but the product was produced in the same manner. The finished condition was the same in all cases.

Further, the above-mentioned silica powder may be replaced with anti-flint powder in some cases, and in this case, the button will be a product with a slightly grayish color, but there will be no significant difference in performance.

As explained above, according to the present invention, it is possible to provide a plastic waste material that does not have any transferability to paint, which is a major drawback of conventional plastic waste materials of this type. In addition, it has sufficient erasing performance and can be used for erasing purposes, and even if it is stored in a pencil case with pencils and other stationery, there will be no adhesion or migration, making it a stable and legal eraser for a long period of time. This invention is industrially very effective because it can provide a character effect, improve productivity, and provide a product with even better quality.

Additional relations The present invention is disclosed in Japanese Patent No. 916699 (Japanese Patent Publication No. 5244245).
Regarding the additional invention of the above-mentioned earlier application, the invention relates to a copolymer of polyvinyl acetate and polyethylene and a copolymer of polyethylene and polypropylene 70.
~550 parts by weight of an appropriate amount of ethylene propylene rubber, 20 to 500 parts by weight of white sub, chlorine plasticizer, and necessary fillers and pigments are mixed and kneaded and molded to obtain good erasability and transfer. In contrast, the present invention does not use a vinyl acetate-based material as the main plastic material, and does not use a chlorine-based plasticizer as a plasticizer, but instead uses glycerin or The derivatives are used to improve the workability of cross-wires, to obtain products of stable quality without the need for a vulcanization process, and to provide products with desirable smoothness, elasticity, and tactile sensation. Since a hard product can be easily obtained by imparting the above-mentioned properties, the present invention relates to an improvement on the prior invention, and stands in an additional relationship thereto.

Claims (1)

[Claims] 1 Copolymer of polyethylene and polypropylene 300
Appropriate amount of ethylene propylene rubber and white sub 20 in weight part
-500 parts by weight of glycerin or its derivatives, and necessary fillers and pigments are mixed and kneaded, and then molded into a plastic consumable material.