JP3134471B2 - eraser - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an eraser for erasing handwriting such as a pencil and a mechanical pencil.

[0002]

2. Description of the Related Art Erasers are generated when an eraser is used.
Conventionally, polyvinyl chloride-based eraser, which has been the mainstream of erasers, is a chlorine compound containing a large amount of chlorine in the base polyvinyl chloride. Become. In this regard, since the thermoplastic elastomer-based eraser does not need to use a chlorine compound, the above-mentioned problem does not occur and is very good. In particular, a styrene-based thermoplastic elastomer has good erasability of the handwriting and is suitable for an eraser material because the carbon powder constituting the handwriting of a pencil or a mechanical pencil is well adsorbed.

However, a styrene-based thermoplastic elastomer alone does not become an eraser because it has a high physical strength and does not wear when rubbed. Therefore, the abrasion is enhanced by using in combination with a sub or different resin or other thermoplastic elastomer used in the conventional rubber-based eraser. But,
Even when such substances are used in combination, an eraser based on a styrene-based thermoplastic elastomer is inferior in erasability with a light force as compared with a polyvinyl chloride-based eraser.

The present applicant solves the above-mentioned problem by adding a petroleum-based oil or polybutene having a kinematic viscosity of 1000 cSt (40 ° C.) or less to a styrene-based thermoplastic elastomer as a base material by 1 to 3 times by weight. The proposed eraser was previously proposed (Japanese Patent Application No.
-124391), Patent Application 1991-34004
No. 3 (JP-A-5-147392).

[0005]

The eraser according to the present invention has good characteristics of exhibiting high erasability even with a light force. However, it has been found that after long-term storage, a so-called blooming phenomenon, in which an oily substance slightly oozes on the surface, may occur. In order to prevent the blooming phenomenon, a filler such as heavy calcium carbonate may be used. However, it is necessary to use a large amount of the filler, which lowers the erasing performance of the eraser.
An object of the present invention is to provide an eraser that prevents blooming without lowering the performance of the eraser.

SUMMARY OF THE INVENTION The object of the present invention is to further improve the quality of the eraser proposed above, and to provide a styrene thermoplastic elastomer as a base material and a weight ratio of 1 to 3 with respect to the base material. The gist of the present invention is an eraser containing a doubled oil and a gelling agent.

The details will be described below. The styrene-based thermoplastic elastomer used as a base material has a molecule-restricted component (hard segment) for preventing plastic deformation and a rubber component (soft segment) having elasticity in the molecule, and both ends of the rubber component are molecular-restricted. It is a triblock copolymer sandwiched between components. At room temperature, a plurality of molecular constrained components at both ends of the molecule aggregate to form a domain, creating a three-dimensional network structure like a crosslinked rubber. At high temperatures, the domain consisting of the molecular constrained components is plasticized and each molecule is constrained. The power to do is lost. Therefore, the styrene-based thermoplastic elastomer exhibits the performance of a vulcanized rubber at room temperature, and is plasticized at a high temperature so that it can be molded by an ordinary plastic molding machine.

As the styrene-based thermoplastic elastomer, a styrene-butadiene-styrene copolymer in which the molecular constraining component is polystyrene and a rubber component is polybutadiene, and styrene-isoprene which is polyisoprene
Styrene copolymer, styrene-ethylenebutylene-styrene copolymer as polyethylene butylene and styrene-ethylene propylene as polyethylene propylene-
Styrene copolymers are exemplified.

An example of a commercially available styrene-based thermoplastic elastomer is described below. Examples of the styrene-butadiene-styrene copolymer include tufprene A and tufprene 12
5, 200, 315, 912, Solprene T-4
06, T-411, T-414, T-475, Asaprene T-420, T-430, T-431, T-450 (all manufactured by Asahi Kasei Corporation), Califflex TR1101 , TR1102, TRKX138
S, TR1118, TR1116, TR118
4, TR1186, TR1122, TR411
3, TR4122, TR4205, TR426
TR4261 and Clayton D1300 (all manufactured by Shell Chemical Co., Ltd.). As a styrene-isoprene-styrene copolymer, Kariflex TR is used.
1107, TR1111, TR1112, TR1
117 (all manufactured by Shell Chemical Co., Ltd.). As styrene-ethylenebutylene-styrene copolymers, Tuftec H1052, H1041, H10
51 (all made by Asahi Kasei Corporation), Clayton G16
50, G1652, G1657X (all manufactured by Shell Chemical Co., Ltd.), Lavalon SJ4400, and SJ540
0, SJ6400, SJ7400, SJ840
0, SJ9400, SE5400, SE640
0, SS6400, SS7400, SS940
0, MJ4300, MJ6300, ME6301
(Above, manufactured by Mitsubishi Yuka Co., Ltd.). As a styrene-ethylene propylene-styrene copolymer,
Septon 2002, 2003, 2023, 204
3, 2063, 2005, 2006, 210
3, 2104, 2105, 4055 (or more,
(Made by Kuraray Co., Ltd.). In addition, Solprene T
-475 is a styrene-butadiene-styrene copolymer 1
It contains 50 parts by weight of naphthenic oil per 100 parts by weight. These styrenic thermoplastic elastomers can be used alone or in combination of two or more.

Further, the physical strength can be reduced by using a two-block copolymer comprising a molecular constraining component and a rubber component in combination. As the diblock copolymer, Kraton G1726X (manufactured by Shell Chemical Co., Ltd.) containing 70% by weight of a styrene-ethylenebutylene-diblock copolymer and 30% of a styrene-ethylenebutylene-styrene-triblock copolymer, There are Clayton G1701X (manufactured by Shell Chemical Co., Ltd.) and Septon 1001 and 1050 (manufactured by Kuraray Co., Ltd.) of styrene-ethylene propylene-diblock copolymer. When the above two-block copolymer is used in combination, the content is desirably 30% by weight or less based on the total amount of the styrene-based thermoplastic elastomer. If the amount used is more than 30% by weight, the tendency is that the styrene-based thermoplastic elastomer tends to be in a plasticized or dissolved state at room temperature due to a liquid material described later.

[0010] The liquid material is used to reduce the physical strength of the styrene-based thermoplastic elastomer as a base material, and includes a petroleum-based oil or a liquid polymer.

The petroleum-based oil is a mixture of a paraffin-based hydrocarbon, a naphthenic ring-based hydrocarbon and an aromatic-based hydrocarbon obtained from petroleum. Extender oil for oil and rubber,
Liquid paraffin, spindle oil, machine oil and the like in addition to the process oil for compounding are known. Examples of liquid paraffin include industrial liquid paraffin described in JIS K2231 and standardized products of the Japanese Pharmacopoeia and the Food Sanitation Law. Those conforming to these standards include Christol 52, 70, 72, 102, 142, and 17
2, 202, 262, 322, 352 (above,
Esso Oil Co., Ltd.), Daphne CP15N, CP3
2N, CP38N, CP68N, KP8, KP
15, KP32, KP68, KP100 (or more,
Idemitsu Kosan Co., Ltd.).

Furthermore, petroleum-based oils are classified by Kurtz's classification method (paraffin-chain oils having a carbon number of 50% or more of the total carbon number are paraffin-based oils and naphthene ring carbon atoms of 30 to 45.
% Are classified as naphthenic oils and those having an aromatic ring carbon number of 35% or more are classified as aromatic oils).
Paraffin oils are Diana PX-32, PX-90,
PW-32, PW-90, PW-380, PS
-32, PS-90, PS-430 (all manufactured by Idemitsu Kosan Co., Ltd.), Shelflex 210, 310, 790, 1210, 1310, Lubeflex 2
6, 100, 460 (all, Shell Chemical Co., Ltd.)
Manufactured), Kyoishi process P200, P300, P50
0, Kyoishi EPT750 (all manufactured by Kyodo Sekiyu KK) and the like. Naphthenic oils are Diana NS-24, NS-100, NM-26, NM-280, and NP
-24, NU-80, NF-90 (all manufactured by Idemitsu Kosan Co., Ltd.), Shelflex 371JY, 371
N, 451, N-40, 22, 22R, 32
R, 100R, 100S, 100SA, 220
RS, 220S, 260, 320R, 680
(Manufactured by Shell Chemical Co., Ltd.), Kyoishi Process R25,
R50, R200, and R1000 (all manufactured by Kyodo Sekiyu KK). Aromatic oil is Diana A
C-12, AC-460, AH-16, AH-5
8 (manufactured by Idemitsu Kosan Co., Ltd.), Deuterex 72
9UK, 739 (all manufactured by Shell Chemical Co., Ltd.), Kyoishi Process X50, X140 (all, Kyodo Oil Co., Ltd.)
Manufactured).

In the above petroleum-based oils, paraffinic oils and naphthenic oils can be used alone or in combination of two or more, but aromatic oils need to be used in combination with paraffinic oils and / or naphthenic oils. There is. This is because the aromatic ring component easily dissolves polystyrene, so when the number of aromatic ring carbons becomes 35% or more of the total carbon number of the petroleum-based oil, the styrene domain in the styrene-based thermoplastic elastomer is dissolved, and the styrene-based thermoplastic elastomer dissolves. This is because the thermoplastic elastomer becomes a plasticized or dissolved state at room temperature and does not become an eraser. Therefore, the number of aromatic carbon atoms in the petroleum-based oil must be less than 35% of the total number of carbon atoms.

The liquid polymer is liquid polyisoprene, liquid polybutadiene and a kinematic viscosity of 1000 cSt (40 ° C.)
The following polybutenes may be mentioned. As said polybutene, Nisseki polybutene LV-5, LV-10, LV-2
5, LV-50, LV-100, HV-15 (all manufactured by Nippon Petrochemical Co., Ltd.) and Idemitsu Polybutene 0H, 5H, 10H, 15H, 0R, 15R (all,
Idemitsu Petrochemical Co., Ltd.).

It is necessary to use the oily substance in an amount of 1 to 3 times by weight based on the styrene-based thermoplastic elastomer. If the amount is less than this, the decrease in physical strength is small, and the erasability is poor with a light force. Conversely, if the amount used is larger than this, the strength as an eraser is lowered, and other properties as an eraser are adversely affected.

The gelling agent is used to prevent the so-called blooming phenomenon in which the oily substance oozes on the surface of the eraser. As the gelling agent, 1,3; 2
4-dibenzylidene sorbitol, 1,3; 2,4;
Organic gelling agents such as 5,6-tribenzylidene sorbitol, dextrin fatty acid ester, N-acyl fatty acid amide, and castor oil derivative, and inorganic gelling agents such as silica, bentonite, and hectorite can be used. . In particular, silica shows a great effect and is good.
Examples of the silica include dry-produced Aerosil (manufactured by Nippon Aerosil Co., Ltd.), wet-processed Mizukasil (manufactured by Mizusawa Chemical Co., Ltd.), and Nipsil (manufactured by Nippon Silica Co., Ltd.).
What was said.

The amount of the gelling agent used is 0.1 to oil.
1-10% by weight is preferred. If the amount is less than this, a remarkable effect may not be exhibited in some cases. If the amount is more than this, there is a tendency that other characteristics as an eraser are adversely affected.

In addition to the above-mentioned essential components, a chlorine-free thermoplastic resin other than the styrene-based thermoplastic elastomer and a thermoplastic elastomer such as an olefin-based, ester-based, or urethane-based thermoplastic elastomer can be used together, if necessary. The thermoplastic elastomer should contain at least 25% by weight, preferably at least 50% by weight of the total amount of the base material. Further, a filler, a stabilizer, a coloring agent, and the like can be appropriately used.

For the production of the eraser, the above components are kneaded by a usual heating type mixer such as a heated two-roller, a pressure kneader or a Banbury mixer, and then molded by a press machine, an injection molding machine or an extruder. Can be obtained using

[0020]

The gelling agent gels and fixes oils in the eraser, so that the oils do not seep onto the eraser surface. In addition, since the amount of the gelling agent used is very small compared to that of a filler such as heavy calcium carbonate, the properties of the eraser are not reduced.

[0021]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples, but "parts" in Examples and Comparative Examples indicates "parts by weight". Example 1 Carifrex TR1101 35 parts Clayton G1726X 15 parts Diana PW-380 60 parts Heavy calcium carbonate (filler) 100 parts IRGANOX1010 (stabilizer, manufactured by Ciba-Geigy, Germany) 1 part Aerosil # 200 (silica fine powder) 0.6 parts, manufactured by Nippon Aerosil Co., Ltd. Of the above components, Kaliflex TR1101 and Clayton G1726X were sufficiently kneaded with a two-roll heated to 120 ° C. In addition, Diana PW-
380 and Aerosil # 200 were mixed and gelled, and the remaining components were added and further kneaded. The kneaded product was placed in a mold and pressed at 120 ° C. for 10 minutes to obtain a block-shaped eraser.

Example 2 50 parts of Septon 2002 100 parts of Daphne KP32 300 parts of Diana NS-24 200 parts of heavy calcium carbonate 1 part of IRGANOX1010 1 part Nip seal LP (silica fine powder, manufactured by Nippon Silica Co., Ltd.) 9 parts Septon 2002 in the above components And Daphne KP32 was sufficiently kneaded with two rolls heated to 120 ° C. To this, Diana NS-24 and Nip Seal LP were mixed in advance and gelled, and the remaining components were added and kneading was further performed. The kneaded product was placed in a mold and pressed at 120 ° C. for 10 minutes to obtain a block-shaped eraser.

Example 3 Solprene T-475 (50 parts of styrene-butadiene-styrene copolymer, 25 parts of naphthenic oil) 75 parts Mirastomer 7030N (olefin-based thermoplastic elastomer, manufactured by Mitsui Petrochemical Industry Co., Ltd.) 50 parts Heavy calcium carbonate 100 parts Diana NU-80 50 parts IRGANOX1010 1 part Gelol D (1,3; 2,4-dibenzylidene sorbitol, manufactured by Shin Nippon Rika Co., Ltd.) 0.5 parts Solprene T-475 and mylastomer 7030N to 1
The mixture was sufficiently kneaded with two rolls heated to 20 ° C.
Diana NU-80 and Gel All D
Was heated and mixed to form a dissolved state, then cooled and gelled, and the remaining components were added and kneaded. The kneaded product is placed in a mold at 120 ° C. and 10
Press molding was performed for a minute to obtain a block-shaped eraser.

Example 4 35 parts of Califrex TR1101 15 parts of Clayton G1726X 15 parts 60 parts of Nisseki polybutene LV-50 100 parts of heavy calcium carbonate (filler) 100 parts IRGANOX1010 (stabilizer, manufactured by Ciba-Geigy, Germany) 1 part Leopard KE (dextrin palmitic acid ester, manufactured by Sanseki Co., Ltd.) 0.3 parts Of the above components, Kariflex TR1101 and Kraton G1726X were sufficiently kneaded with a two-roll heated to 120 ° C. Add Nisseki Polybutene L
After heating and mixing V-50 and Leopearl KE to bring them into a dissolved state, the mixture was cooled and gelled, and the remaining components were added and kneaded. The kneaded product was placed in a mold and pressed at 120 ° C. for 10 minutes to obtain a block-shaped eraser.

Example 5 Septon 2002 50 parts Nisseki polybutene HV-15 100 parts Heavy calcium carbonate 200 parts IRGANOX1010 1 part Bentonite 5 parts Of the above components, two rolls obtained by heating Septon 2002 and Daphne KP32 to 120 ° C. are sufficient. Kneading was performed. To this, Nisseki polybutene HV-15 and bentonite were mixed and gelled in advance, and the remaining components were added and further kneaded. The kneaded product was placed in a mold and pressed at 120 ° C. for 10 minutes to obtain a block-shaped eraser.

Example 6 50 parts of Soprene T-406 50 parts Mirastomer 7030N (olefin thermoplastic elastomer, manufactured by Mitsui Petrochemical Industry Co., Ltd.) 50 parts heavy calcium carbonate 100 parts Idemitsu Polybutene 0R 75 parts IRGANOX1010 1 part Aerosil # 200 1.5 parts Sorprene T-406 and Mylastomer 7030N
The mixture was sufficiently kneaded with two rolls heated to 20 ° C.
Idemitsu Polybutene 0R and Aerosil # 2
The resulting mixture was further kneaded by adding the mixture obtained by mixing 00 with the mixture to form a gel, and the remaining components. The kneaded product was placed in a mold and pressed at 120 ° C. for 10 minutes to obtain a block-shaped eraser.

Comparative Example 1 Califrex TR1101 35 parts Clayton G1726X 15 parts Diana PW-380 175 parts Heavy calcium carbonate (filler) 100 parts IRGANOX 1010 (stabilizer, manufactured by Ciba-Geigy, Germany) 1 part , Kaliflex TR1101 and Clayton G1726X were sufficiently kneaded with a two-roll heated at 120 ° C., and the remaining components were added to the kneader to further knead. The kneaded product is put in a mold and the
Press molding was performed at 10 ° C. for 10 minutes to obtain a block-shaped eraser.

Comparative Example 2 Carifrex TR1101 35 parts Clayton G1726X 15 parts Diana PW-380 175 parts Heavy calcium carbonate (filler) 350 parts IRGANOX1010 (stabilizer, Ciba-Geigy, Germany) 1 part After sufficiently kneading Kariflex TR1101 and Clayton G1726X with two rolls heated to 120 ° C., the rest was the same as in Comparative Example 1 to obtain an eraser.

Comparative Example 3 Polyvinyl chloride resin (Zeon 121, manufactured by Zeon Corporation) 30 parts Dioctyl phthalate (plasticizer) 35 parts Epoxidized soybean oil (stabilizer) 0.6 parts Heavy calcium carbonate 35 parts Each component was mixed to form a paste, which was put in a mold and subjected to heat press molding at 110 ° C. for 20 minutes to obtain an eraser.

Using the erasers obtained in Examples 1 to 6 and Comparative Examples 1 and 2, the erasure rate was measured in accordance with the method of JIS S6050. Observed. The erasers obtained in Examples 1 to 6 all had a erasure rate of 80% or more, satisfying the JIS standard, and did not cause blooming. However, the eraser obtained in Comparative Example 1 caused a blooming phenomenon, and the paper surface and hands were soiled. Further, although the eraser obtained in Comparative Example 4 did not cause the blooming phenomenon, the handwriting was not taken into the erased scum at the time of erasing, and the paper surface was stained black. Next, when the erasability with a light force was manually erased and compared with the erasers of Examples 1 to 6 and Comparative Example 3, they were equivalent.

[0031]

As described in detail above, since the eraser according to the present invention does not use a chlorine compound as a raw material, it does not generate a chlorine-containing toxic gas during incineration. It has an excellent property that the blooming phenomenon can be prevented from occurring and that it disappears well even when rubbed with a light force like a polyvinyl chloride eraser.

Claims (1)

(57) [Claims] 1. An eraser comprising a styrene thermoplastic elastomer as a base material, an oily substance in a weight ratio of 1 to 3 times the base material, and a gelling agent.