KR920003033B1 - Rubber eraser - Google Patents

Abstract

The ruberic eraser consists of the styrenic thermoplastic elastomer as the main matrix, and a hydrocabon resin and polyoleffin. The hydrocarbon resin is a terpene resin or polypropylene. Pref. the polyolefin is polyethylene or polypropylene. Pref. the styrenic thermoplastic elastomer is selected from styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-ethylene-butylene copolymer or styrene-ethylene-propylene copolymer. The obtd. eraser has a good erasing property to a plastic crayon.

Description

Rubber eraser

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rubber eraser, in particular a plastic eraser, which is capable of erasing well and having excellent safety.

Conventional rubber erasers are known of natural rubber type and plastic type. Among them, natural rubber is made of natural rubber as a base material, and is mixed with factis (rubber-like substance made of vegetable oil) or filler, and is in sulfuric state as sulfur. It is made. In the plastic type, the emulsion-polymerized vinyl chloride resin is a basic material, in which a filler or the like is mixed and kneaded as an excess plasticizer, followed by steam heating to semigel the resin.

However, to obtain a natural rubber-based process is required to add sulfur, so the process is complicated and there is a defect that can not reuse the residues generated when cutting semi- value (半 加 硫 物).

Furthermore, plastics contain plasticizers, so infants have a safety problem when they put an eraser in their mouth.

In contrast, new plastic rubber erasers have been proposed. For example, thermoplastic elastomers (Japanese Patent Publication No. 46-23450) ethylene-vinyl acetate copolymer / or atactic polypropylene resin, styrene-butadiene (styrene) -butadiene copolymers and plasticizers (特 昭公昭 57-32680), but the rubber eraser properties are insufficient. Moreover, recently, a new plastic creon was developed as a creon, and the old eraser cannot erase this new creon.

It is an object of the present invention to propose a rubber eraser which can be easily prepared and erases eraser properties, in particular plastic crayons, without any problems in safety.

The present invention is based on the fact that the above problems can be solved by using a styrene-based thermoplastic elastomer as a base material and using a hydrocarbon resin and polyoleffine together.

In other words, the present invention provides an eraser comprising a hydrocarbon resin and a polyolefin as a rubber eraser based on styrene-based thermoplastic elastomer.

Although there are various kinds of styrene-based thermoplastic elastomers used in the present invention, styrene-butadiene copolymers, styrene-isoprene copolymers, styrene-ethylene-buthylene copolymers and succinic acid called SBR. It is recommended to use one selected from styrene-ethylene-propylene copolymers.

As such styrene-based thermoplastic elastomers, Shell Chemical Co., Ltd.'s califlex TR® (trade name), or Tupprene® or Sulprene® Japanese synthetic rubber )) JSR. It is easy to purchase as TR.

In the present invention, the above-mentioned styrene-based thermoplastic elastomer is contained as a base material, for example, 15-50% by weight (hereinafter abbreviated as%) in the rubber eraser, more preferably 25-40%.

Hydrocarbon resins added to the above materials are thermoplastic resins polymerized with long-chain hydrocarbons or cyclic hydrocarbon components contained in petroleum, natural gas, natural rubber or terpene oil. terpene) resins, hydrogenated terpene resins, aromatic petroleum resins, aromatic petroleum resins to which water is added, aliphatic petroleum resins, rosin esters (colonium), and the like.

Among them, the type of water added is good in terms of fragrance and coloring. Among them, terpene resins are obtained from Chuwoo Chemical Co., Ltd., Japan ZEON Anwon Oil Industry Co., Ltd., etc. Hydrogenated terpene resin is obtained as clearon from Anwon Oil Holding Co., Ltd.

Petroleum resins such as aromatic petroleum resins, hydrogenated aromatic petroleum resins, aliphatic petroleum resins, etc., are produced by Sam-Jeong Petrochemical Co., Ltd. Easily available as petrosin® (registered trademark) or FRT (registered trademark) from Japan Petrochemical Co., Ltd., Neopolymer.

Although polyolefin may be used in various proportions in the present invention, it is more preferable to use 1-30% of hydrocarbon resin, especially 3-10%. The polyolefin is preferably used in a ratio of polyolefin / hydrocarbon resin to 3 / 1-1 / 2, but more preferably used as 1 / 1-2 / 1.

The ratio of the total amount of the polyolefin to the hydrocarbon resin / styrene thermoplastic elastomer is preferably 1 / 10-6 / 10, but more preferably 3 / 10-5 / 10.

In the present invention, the above configuration is an essential item, but various additives may be added as necessary. As an additive here, fillers, such as calcium carbonate, talc, clay, barium lactate, silica, alumina, oxidized dentition, diatomaceous earth, and glass, processing oil softeners such as process oils, polybutylenes, chlorinated paraffins, liquefied paraffins, colorants, perfumes, stabilizers, lubricants, and thermoplastic resins and thermoplastic elastomers other than those specified in the present invention. have. Double fillers should be used at 25-60% softeners at 1-15%.

The rubber eraser of the present invention is kneaded as a mixer or roller by a Henschel mixer or the like, pelletized as a pelletizer, and then injection molded into a rubber of a desired shape. It becomes an eraser.

According to the present invention, there is provided a rubber eraser having excellent eraser characteristics which can be easily manufactured easily and has no safety problems. Therefore, the rubber eraser of the present invention can be widely used as an eraser that can be erased extremely well than general use and can be erased even in plastic creons. Next, the present invention will be described without limitation in accordance with embodiments.

EXAMPLE

Example 1

The composition of the following:

After kneading, injection molding is performed to make a rubber eraser (hard). This rubber eraser will completely erase the plastic crayon painted on the paper.

Example 2

Next composition:

After kneading, injection molding is performed to make a rubber eraser (soft). This rubber eraser can completely erase plastic Creon letters on paper.

Comparative Example 1

When the rubber eraser is removed from the composition of Example 1 to make a rubber eraser, the letters of the plastic Creon written on the paper are completely erased and the eraseability of the letters of the pencil is not good.

Comparative Example 2

Removing the hydrogenated terpene resin from the composition of Example 2 and making a rubber eraser erases the letters of the pencil, but appears to be contaminated and widely to erase the letters of the plastic Creon written on the paper.

Example 3

The composition of the following:

After kneading, injection molding is performed to make a rubber eraser. This rubber eraser removes the letters on the plastic Creon written on the paper.

Example 4

The following composition:

After kneading, injection molding is performed to make a rubber eraser. This rubber eraser can erase the letters of the plastic Creon written on the paper.

Claims (4)

A rubber eraser comprising a hydrocarbon resin and a polyoleffin in a rubber eraser based on a styrene thermoplastic elastomer (rubber-like material). The hydrocarbon resin is a terpene resin or polypropyrene, the rubber eraser according to claim 1. The rubber eraser according to claim 1, wherein the polyolefin is made of polyethylene or polypropylene. Styrene-based thermoplastic elastomers include styrene-butad iene copolymers, styrene-isoprene copolymers, styrene-ethylene-butylene copolymers and styrene copolymers. The rubber eraser according to claim 1 selected from a styrene-ethy lene-propylene copolymer.