JP7394447B2 - Eraser - Google Patents

Description

The present invention relates to an eraser that has excellent resistance to bending and chipping (the eraser does not break or chip during use), has a light feeling of use, and has excellent erasability.

A character eraser is widely used as an indispensable tool for erasing written lines. Erasers are generally made by blending a plasticizer with the base resin, and then adding materials such as stabilizers, colorants, and fragrances as necessary, mixing and stirring, and then using a molding method such as press molding, injection molding, or extrusion molding. Manufactured by heating and molding.

It is known that the strength of the eraser can be improved by adding fibrous materials. However, it did not have the lightness of erasing.

For example, in Patent Document 1, magnesium oxysulfate (MgSO _{4.5MgO.8H 2} O) fibers (average fiber diameter 0.5 μm, average fiber length 50 μm) are added in a weight ratio of 1 to 40% to the entire eraser. It is disclosed that injection molding or extrusion molding improves the bending strength and cracking resistance of the eraser. In Example 3, a material in which the fibers were blended with polyvinyl chloride, calcium carbonate, a plasticizer, etc. was kneaded in a mixer to form a plastisol, which was then molded into a cylindrical object in an extruder (130°C) to form an eraser ( (edited).

Patent Document 2 discloses that potassium titanate fibers (average fiber diameter 0.2 to 0.3 μm, average fiber length 20 μm) are added in an amount of 0.2 to 10% by weight based on the entire polyvinyl chloride eraser and extruded. It is disclosed that the bending strength of the eraser is improved by molding. Compared to the case where glass fiber is mixed, the bending strength (strength) is improved and an excellent reinforcing effect is obtained. Potassium titanate fiber has a very thin fiber diameter, so it feels soft to the touch when erasing the paper surface. , it is stated that it is possible to wear the paper surface appropriately without forcibly scraping it off. In Example 1, a material in which the fibers were mixed with polyvinyl chloride, heavy calcium carbonate, a plasticizer, etc. was kneaded in a mixer to form a plastisol, and then molded in an extruder (100 to 150°C) to form an eraser ( It is stated that during extrusion molding, fine fibers are intertwined and extruded, resulting in a remarkable reinforcing effect on eraser strength and high stability during molding.

On the other hand, there is also a known method of imparting a light eraser feel to the eraser without reducing the abrasion force of the eraser, but it has not been possible to obtain a method that combines a light eraser feel and strength.

For example, Patent Document 3 proposes a method in which spindle-shaped calcium carbonate is blended at 37% or more of the total amount of an eraser (letter eraser), kneaded with polyvinyl chloride and a plasticizer to form a plastisol, and then extruded into a square bar. There is.

Patent Document 4 proposes a method in which 1 to 400 parts by weight of glass beads having a particle size of 150 μm or less are added to 100 parts by weight of resin.

In addition, Patent Document 5 discloses that fiber particles (carbon fiber, glass fiber, , polyamide fibers, etc.). However, it has not been possible to obtain a material that has both lightness and strength.

JP-A-63-137899 (Claims, page 1, left column, lines 11-12, page 2, lower right column, lines 2-13, Example 3, etc.) Japanese Patent Publication No. 62-47720 (Claims, page 2, column 3, lines 16-37, etc.) JP 2015-91649 A (claims, paragraph [0014], etc.) Patent No. 4633777 (Claims, Table 1, etc.) JP 2014-111320 A (Claims, paragraph [0023], Examples 5 to 7, etc.)

The present invention is a hitherto unknown feature that does not reduce the abrasion force of the letter eraser, has a light erasing feeling (feel of use), has excellent resistance to bending and chipping during use, and has excellent erasability. The challenge is to provide erasing.

In order to solve the above problems, the inventors of the present invention conducted extensive research and found that by adding fibrillated organic fibers to the base resin, the lightness of the eraser feeling and the strength (resistance to bending and chipping during use) were improved. It has been discovered that excellent letter erasing can be obtained, and the present invention has been achieved.

That is, the present invention is as follows.

1) An eraser characterized by having a coefficient of static friction and a coefficient of dynamic friction of 0.80 to 0.95 with PPC paper having a whiteness of 90% or more, and containing fibrillated organic fibers.
2) The eraser according to 1) above, wherein the fibrillated organic fiber has no melting point or has a melting point of 100°C to 300°C.
3) The eraser according to 1) or 2) above, wherein the organic fiber is a polyolefin fiber.
4 ) The eraser according to any one of 1) to 3) above, which has a resistance to folding 21 times or more with high-quality paper having a whiteness of 75% or more.
5) The eraser according to any one of 1) to 4) above, which is formed by press molding.

According to the present invention, it is possible to provide an eraser that has excellent erasability, has a light erasing feeling (that is, a feeling of use), and has excellent strength (that is, resistance to bending and chipping during use).

FIG. 2 is a schematic diagram showing a method of measuring a friction coefficient.

The fibrillated organic fibers used in the present invention are organic fibers dissociated into fibrils, and preferably fibers having a multi-branched structure with fibrils protruding from the fiber surface are used. Unlike short fibers (cut fibers) made from cut organic fibers, they have a multi-branched structure.

Types of fibrillated organic fibers include polyolefin fibers such as polyethylene fibers and polypropylene fibers; synthetic fibers such as polyamide fibers, vinylon fibers, polyester fibers, and acrylic fibers; semi-synthetic fibers such as acetate; rayon, lyocell (Tencel), Examples include regenerated fibers such as polynosic; cellulose fibers; and the like. These can be used alone or in combination of two or more. Among these, polyolefin fibers and cellulose fibers are preferred because they can reduce the friction coefficient of erasing and have excellent strength and erasability. Further, polyolefin fibers are more preferable because they have a multi-branched structure with fibrils protruding from the fiber surface, can be blended as a powder, and have excellent processability.

Commercially available fibrillated organic fibers may be used. Commercially available products include, for example, fibrillated polyolefin fibers such as Chemivest FDSS-5, Chemivest FDSS-2, Chemivest FD380 (Mitsui Chemicals Fine Co., Ltd.), and fibrillated cellulose fibers such as FD-100F, FD-200L, Fibrillated polyamide fibers such as KY-100S and KY-100G (Daicel Corporation) include KY-400S (Daicel Corporation).

The fiber length of the fibrillated organic fiber is preferably 0.1 mm to 10 mm. If it is less than 0.1 mm, sufficient strength may not be imparted to the eraser, and if it exceeds 10 mm, it becomes difficult to peel off the dregs from the eraser surface, and the eraser performance tends to deteriorate. The fiber length is more preferably 0.1 mm to 5 mm, particularly preferably 0.5 to 2 mm.

The fiber diameter of the fibrillated organic fiber is preferably 0.01 μm to 30 μm. If it is less than 0.01 μm, the mechanical energy required to produce the fibrillated organic fiber increases, resulting in high costs; if it exceeds 30 μm, the friction coefficient for erasing becomes extremely small, which may reduce the erasing force. . The fiber diameter is more preferably 2 to 30 μm. The fiber diameter can be measured by observing each fiber with a microscope such as an optical microscope or an electron microscope.

The content of the fibrillated organic fiber is preferably 0.5 to 30 parts by weight, more preferably 1 to 20 parts by weight, particularly preferably 2.5 to 10 parts by weight, based on 100 parts by weight of the base resin. be. If the content is too low, it will be difficult to improve the erasing feeling and strength of the eraser, and if the content is too high, the effect will reach a ceiling, which will be uneconomical.

As the base resin used for the eraser of the present invention, a vinyl chloride resin is preferable because when fibrillated organic fibers are added, an eraser with a light erasing feeling can be obtained. The base resins may be used alone or in combination of two or more types as required. The content of the base resin is preferably 20 to 50% by mass (hereinafter abbreviated as "%"), more preferably 25 to 40%, based on the total amount of the eraser composition.

As the vinyl chloride resin, all conventionally used vinyl chloride resins can be used. For example, in addition to polyvinyl chloride with a degree of polymerization of about 400 to 4,000, vinyl chloride-vinyl acetate copolymer, chloride Examples include vinylidene, vinyl chloride-methyl acrylate copolymer, vinyl chloride-methyl methacrylate copolymer, and vinyl chloride-octyl acrylate copolymer. These may be used alone or in combination of two or more as necessary. As the vinyl chloride resin, paste resin is preferred because it is easy to mix with plasticizers and the like and to process.

In the eraser of the present invention, any known plasticizer can be used without particular limitation, and a plasticizer that is highly miscible with the vinyl chloride resin is preferably used.

Specific examples of preferable plasticizers include, for example,
Di-2-ethylhexyl phthalate (DOP), di-n-octyl phthalate (n-DOP), diisononyl phthalate (DINP), dinonyl phthalate (DNP), diisodecyl phthalate (DIDP), ditridecyl phthalate (DTDP), diundecyl Phthalate plasticizers such as phthalate (DUP);
Trimellitic acid plasticizers such as tri-2-ethylhexyl trimellitate (TOTM), triisodecyl trimellitate (TIDTM), triisooctyl trimellitate (TIOTM), triisononyl trimellitate;
Pyromellitic acid plasticizers such as trioctylpyromellitic acid (TOPM);
Dibasic acid (e.g. adipic acid), at least one polyhydric alcohol (e.g. aliphatic glycol having 2 to 18 carbon atoms and polyalkylene glycol such as diethylene glycol and dipropylene glycol), A polyester plasticizer (including liquid polyester plasticizer) such as polyester obtained by condensing with at least one selected from a monohydric alcohol or a monohydric carboxylic acid having 9 to 18 carbon atoms;
Epoxy plasticizers such as epoxidized fats and oils, epoxidized fatty acid esters;
Adipic acid plasticizers such as di-2-ethylhexyl adipate (DOA), diisononyl adipate (DINA), and diisodecyl adipate (DIDA);
Sebacic acid plasticizers such as di-2-ethylhexyl sebacate (DOS) and dibutyl sebacate (DBS);
Azelaic acid plasticizers such as di-2-ethylhexyl azelate (DOZ);
Phosphoric acid plasticizers such as tricresyl phosphate (TCP) and tri-2-ethylhexyl phosphate (TOP);
Citric acid plasticizers such as triethyl citrate, acetyl tri-n-butyl citrate, tri-n-butyl citrate, acetyl triethyl citrate, acetyl tri-(2-ethylhexyl) citrate;
PN-6120 (trade name, ADEKA, glycol diester), Benzoflex 9-88 (dipropylene glycol dibenzoate), Benzoflex 50 (mixture of diethylene glycol dibenzoate and dipropylene glycol dibenzoate), Benzoflex 2088 (diethylene glycol dibenzoate, dipropylene glycol dibenzoate) Pyrene glycoldi benzoate, a mixture of triethylene glycol dibenzoate) (all trade names, EASTMAN), PB-3A, W-83 (all trade names, DIC), and other benzoic acid plasticizers;
Alkyl sulfonic acid phenyl esters such as Mezamol and Mezamol II (both trade names, Bayer AG);
Cyclohexanedicarboxylic acid ester such as DINCH (trade name, BASF);
etc.

上記のシクロヘキサンジカルボン酸エステルは、下記式で表わされる。

式中、Ｒ^１、Ｒ^２は互いに独立して、炭素数１～２０のアルキル基を表す。Ｒ^１、Ｒ^２は、同一又は異なっていてよい、直鎖又は分岐鎖を有する、炭素数１～２０のアルキル基（好ましくは炭素数３～１８のアルキル基、特に好ましくは炭素数７～１３のアルキル基）である。Ｒ^１、Ｒ^２は、シクロアルキル基、アルコキシアルキル基でもよい。上記のシクロヘキサンジカルボン酸エステルの中でも、Ｒ^１、Ｒ^２が、炭素数７～１３のアルキル基である、例えば、シクロヘキサン－１，２－ジカルボン酸ジイソペンチルエステル、シクロヘキサン－１，２－ジカルボン酸ジイソヘプチルエステル、シクロヘキサン－１，２－ジカルボン酸ジイソノニルエステル、シクロヘキサン－１，２－ジカルボン酸ジノニルエステル、シクロヘキサン－１，２－ジカルボン酸ジイソデシルエステル、シクロヘキサン－１，２－ジカルボン酸のジ（Ｃ７－１１）アルキルエステル、シクロヘキサン－１，２－ジカルボン酸のジ（Ｃ９－１１）アルキルエステル、シクロヘキサン－１，２－ジカルボン酸のジ（Ｃ７－９）アルキルエステル、シクロヘキサン－１，２－ジカルボン酸のジ（Ｃ８－１３）アルキルエステル等が好ましい。 The above alkylsulfonic acid phenyl ester is represented by the following formula.

The above cyclohexane dicarboxylic acid ester is represented by the following formula.

In the formula, R ¹ and R ² each independently represent an alkyl group having 1 to 20 carbon atoms. R ¹ and R ² are linear or branched alkyl groups having 1 to 20 carbon atoms (preferably 3 to 18 carbon atoms, particularly preferably 7 to 13 carbon atoms), which may be the same or different; alkyl group). R ¹ and R ² may be a cycloalkyl group or an alkoxyalkyl group. Among the above cyclohexanedicarboxylic acid esters, R ¹ and R ² are alkyl groups having 7 to 13 carbon atoms, such as cyclohexane-1,2-dicarboxylic acid diisopentyl ester, cyclohexane-1,2-dicarboxylic acid Diisoheptyl ester, cyclohexane-1,2-dicarboxylic acid diisononyl ester, cyclohexane-1,2-dicarboxylic acid dinonyl ester, cyclohexane-1,2-dicarboxylic acid diisodecyl ester, cyclohexane-1,2-dicarboxylic acid di( C7-11) alkyl ester, di(C9-11) alkyl ester of cyclohexane-1,2-dicarboxylic acid, di(C7-9) alkyl ester of cyclohexane-1,2-dicarboxylic acid, cyclohexane-1,2-dicarboxylic acid Di(C8-13) alkyl esters of acids and the like are preferred.

The above plasticizers may be used alone or in combination of two or more as necessary.

Among the above plasticizers, non-phthalate plasticizers are preferred because of their high environmental adaptability. Among the non-phthalic acid plasticizers, alkylsulfonic acid phenyl esters and cyclohexane dicarboxylic acid esters are preferred, which are plasticizers with excellent erasability and low stickiness. Further, it is also preferable to use these plasticizers in combination with a liquid acrylic polymer or a liquid polyester that is liquid at room temperature. By using liquid acrylic polymer or liquid polyester in combination with other ester plasticizers, the migration resistance of other plasticizers (suppressing the migration of plasticizers to the eraser surface) can be improved. It is possible to obtain a highly erasable eraser with a non-sticky surface. In addition, alkyl sulfonic acid phenyl esters have high compatibility with base resins, are easily mixed or kneaded, are resistant to plasticizer migration, and have excellent heat resistance and processability, so they can be used for fibrillated polyolefin fibers. Suitable for combination with

The blending amount of the plasticizer in the eraser of the present invention is preferably 30 to 70%, more preferably 40 to 65%, particularly preferably 45 to 60%, based on the total amount of the eraser composition. If the amount of plasticizer is less than 30%, the eraser becomes hard and elasticity decreases, and the erasability may decrease.If it exceeds 70%, the eraser becomes too soft and the erasability decreases. It may be difficult to use as an eraser.

The eraser of the present invention may contain a filler in order to adjust the hardness and erasing feel. As a filler, it is common to use silica powder (main ingredient: silicon dioxide) or limestone powder (heavy calcium carbonate), and these inorganic powders are finely divided so as not to damage the writing surface. Use. In addition, diatomaceous earth, talc, whitebait powder, magnesium carbonate, inorganic and organic hollow particles, etc. can be used. Limestone powder is preferred because it provides a good eraser feeling.

The blending amount of the filler is preferably 5 to 40%, more preferably 10 to 30%, particularly preferably 10 to 20%, based on the total amount of the erasing composition. If the filler content is 5% or more, the erasing performance will not deteriorate because the erasing feeling will not be heavy and erasing residue will be easily produced, and if it is 40% or less, the area of the base resin in contact with the paper surface will be reduced. Since this is sufficiently ensured, erasing performance will not deteriorate.

The blending ratio of the filler and the fibrillated organic fiber is preferably adjusted to a mass ratio of fibrillated organic fiber/filler=0.02/1 to 0.5/1. More preferably 0.08/1 to 0.4/1, particularly preferably 0.1/1 to 0.4/1. If the amount of fibrillated organic fibers is too small, the strength may be insufficient; on the other hand, if the amount is too large, it will be uneconomical.

In the eraser of the present invention, a stabilizer can be used as necessary to prevent the base resin from deteriorating at high temperatures during molding, and a light stabilizer such as an ultraviolet absorber can be used to improve light stability. It can also be blended. In addition, additives such as viscosity modifiers, lubricants, solvents, colorants, preservatives, antifungal agents, and fragrances can also be blended. The amount of these additives to be added is not particularly limited as long as the effects of the present invention are not impaired.

The eraser of the present invention has an excellent erasing feeling. The static friction coefficient and dynamic friction coefficient between the eraser and PPC paper having a whiteness of 90% or more are preferably 0.80 to 0.95. If the friction coefficient is 0.80 or more, the eraser can firmly bite into the paper and erase the characters. In actual use, if the coefficient of friction is too small, the writing lines will lengthen and the eraser surface will be difficult to scrape, resulting in the eraser not being erased while being erased. On the other hand, if the friction coefficient is 0.95 or less, a good light erasing feeling can be obtained. When the friction coefficient is within the above range, the frictional force with the paper surface can be made to an appropriate level, thereby achieving both a good erasing feeling and a sufficient erasing force to be used as an eraser. I can do it. The friction coefficient is more preferably 0.80 to 0.92.

The eraser of the present invention has excellent strength (bending resistance and chipping resistance). The folding resistance is preferably evaluated 21 times or more using the folding resistance evaluation method described below. This kind of resistance to folding can be achieved with some combinations of reinforcing materials commonly used in rubber products, such as silica powder, but in that case there is the inconvenience that a light eraser feeling cannot be obtained. . In addition, the above-mentioned folding resistance can also be achieved when short fibers of high-strength fibers are blended, but in that case, the frictional force with the paper becomes too small, resulting in a decrease in erasing power, and in actual use. The writing lines stretch and become impossible to erase while being erased, making the eraser impractical. On the other hand, when KC flock, which is an organic fiber that is not fibrillated, is blended, erasing power can be ensured, but the folding resistance becomes poor. That is, when the KC flock is blended, even if the coefficient of friction is within the range of 0.80 to 0.95, the folding resistance effect is inferior to that of fibrillated fibers.

The eraser of the present invention is produced by kneading the base resin, plasticizer, stabilizer, fibrillated organic fibers, and predetermined amounts of various compounding agents as necessary by a conventional method, and then press molding, injection molding, or extrusion molding. It can be molded by a known method such as. The molding temperature is 90-150°C. The molded article is cut into a predetermined size to produce a product. The molding method is not particularly limited, and a molding method that provides a light erasable feeling, strength, and desired erasing rate may be selected.

Hereinafter, the present invention will be explained in more detail using Examples and Comparative Examples, but the present invention is not limited to the following Examples.

The hardness, erasing rate, bending resistance, and friction coefficient of the eraser were measured or evaluated by the following methods.
[Hardness (hardness)]
(1) Type C (surface hardness): Compliant with JIS S 6050:2002 6.2. Using a hardness tester, the pressing surface of the tester was brought into contact with the surface of the test piece held horizontally so that the indenter of the tester was vertical, and the scale was immediately read.

[Erasing rate]
Compliant with JIS S 6050:2002 6.4.
(1) A test piece was prepared by cutting a letter eraser into a plate shape with a thickness of 5 mm, and finishing the tip part that contacts the colored paper into an arc with a radius of 6 mm.
(2) Using a drawing machine, create colored paper using the HB pencil specified in JIS S 6006 and high-quality paper with a basis weight of 90 g/m ² or more and a whiteness of 75% or more. , touch the test piece perpendicularly and perpendicularly to the colored line, place a weight on the test piece so that the sum of the mass of the weight and the holder is 0.5 kg, and apply a weight of 150 ± 10 cm/ The colored portion was abraded 4 times back and forth at a speed of min.
(3) Using a densitometer, the density of the colored and worn areas of the colored paper was measured, with the density of the non-colored area set as 0.
(4) The erasure rate was calculated using the following formula, and the average value of three times was determined.
Erasing rate (%) = (1 - (density of worn part ÷ density of colored part)) × 100

[Breakability]
(1) A test piece was prepared by cutting a letter eraser into a plate shape with a thickness of 5 mm, and finishing the tip part that contacts the colored paper into an arc with a radius of 6 mm.
(2) Contact the test piece perpendicularly to colored paper similar to the erasure rate, with the direction of movement being in the thickness direction of the test piece, and make sure that the sum of the mass of the weight and the holder is 1. A weight was placed on the tube so that the weight would be .0 kg, and the tube was moved back and forth at a speed of 150±10 cm/min.
(3) The number of reciprocations until the test piece broke (rounded up if it broke on the outward trip) was measured up to 50 times, and the median of the three times was determined.

[Coefficient of friction]
A method for measuring the coefficient of friction will be explained with reference to the drawings. FIG. 1 is a schematic diagram showing the method for measuring the coefficient of friction; (a) is an overall view, and (b) is a view from below of a metal plate 2 to which four test pieces 1 and a wire 6 are attached. . Note that since FIG. 1 is a schematic diagram, the size ratio and shape of each part are not accurate.
(1) Test piece 1 is a rectangular eraser with a width of 12 mm, a height of 8 mm, and a thickness (vertical) of 5 mm, with the lower tip (the part that contacts the test paper 4) shaped into an arc with a radius of 6 mm. , a total of 4 identical ones were made.
(2) Attach the test pieces 1 one by one to the four corners of the bottom surface of a square metal plate 2 (60 mm long x 60 mm wide) with a thickness (height) of 6 mm, with the arc facing downward, aligning the orientation. (See Figure 1(b)).
(3) The friction tester 5 installed horizontally to the ground includes a test stand 5b that can be moved horizontally on the main body 5a and a load cell 5c. A test paper 4 made of PPC paper with a whiteness of 90% or more was pasted on the test stand 5b.
(4) Place the metal plate of (2) above on the test paper 4, with the test piece 1 on the lower side, and move the test stand 5b in the tangential direction of the apex of the arc of the test piece 1 ( The four test pieces 1 were brought into contact with the test paper 4 perpendicularly.
(5) A weight 3 was placed on the center of the upper surface of the metal plate 2 so that the weight together with the metal plate 2 was 0.5 kg.
(6) Connect the metal plate 2 to the load cell 5c via the wire 6, and move the test stand 5b (and test paper 4) at a speed of 200 mm/min in the direction opposite to the load cell 5c side (arrow in Fig. 1(a)). direction), the static friction coefficient and dynamic friction coefficient between the four test pieces 1 and the test paper 4 were measured, and the median value of the three measurements was taken as the measured value.

(Examples 1 to 11, Comparative Examples 1 to 11)
The base resin, plasticizer, stabilizer shown in Table 1, and each material shown in Table 2 are stirred under reduced pressure in the specified ratios (see Tables 1, 3, and 4), and then pressed at 110°C. A test piece was obtained by molding. Among the materials shown in Table 2, calcium carbonate is a filler. Hyperbranched polyolefin fibers that are fibrillated organic fibers, fibrillated cellulose fibers that are fibrillated organic fibers, silica powder (examples), powdered cellulose, ultra-high strength polyethylene fibers, silicate minerals (comparative examples) ) was used as a reinforcing material for erasers. Since the fibrillated cellulose fiber is a water-containing material (solid content 25%), the test specimen was obtained by extrusion molding.

Tables 3 and 4 show the evaluation results of the erasers obtained. Note that Examples 6 to 10 are reference examples.

From Tables 3 and 4, it can be seen that the eraser of the present invention containing fibrillated organic fibers is superior in folding resistance and coefficient of friction than the eraser containing KC flock (for example, Comparison of Example 4 and Comparative Example 6).
By using fibrillated organic fibers and silica powder in combination (Example 6), folding resistance was significantly improved compared to erasing using fibrillated organic fibers and calcium carbonate (Example 3). It can also be seen that the folding resistance and friction coefficient are improved compared to the eraser using silica powder alone (Comparative Example 9).

The eraser containing ultra-high-strength polyethylene fiber (Comparative Example 3) is superior to the example of the present invention in terms of bending resistance and friction coefficient, but its erasing rate is inferior, and the writing line stretches with use, making it difficult to erase while erasing. A phenomenon was observed in which the eraser particles became difficult to come out and were not erased. The eraser containing inorganic long fibers (wollastonite) (Comparative Example 4) had a high friction coefficient and poor bending resistance. The eraser containing inorganic powder did not give a light eraser feel.

The eraser of the present invention can be suitably used for erasing lines drawn with a pencil, mechanical pencil, or the like.

1 Test piece 2 Metal plate 3 Weight 4 Test paper 5 Friction tester 5a Main body 5b Test stand 5c Load cell 6 Wire

Claims (5)

An eraser characterized by having a coefficient of static friction and a coefficient of dynamic friction of 0.80 to 0.95 with PPC paper having a whiteness of 90% or more, and containing fibrillated organic fibers. The eraser according to claim 1, wherein the fibrillated organic fiber has no melting point or a melting point of 100°C to 300°C. The eraser according to claim 1 or 2, wherein the organic fiber is a polyolefin fiber. The eraser according to any one of claims 1 to 3, which has a resistance to folding 21 times or more with high-quality paper having a whiteness of 75% or more. The eraser according to any one of claims 1 to 4, which is formed by press molding.

Images