JP3438433B2 - eraser - Google Patents

Description

Description: BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to an eraser for erasing handwriting of a pencil, a mechanical pencil or the like. About the eraser united into one. 2. Description of the Related Art Conventionally, erasers have been known as vinyl chloride resins using a vinyl chloride resin or a copolymer of vinyl chloride as a base resin, natural rubber resins mainly using natural rubber, and thermal rubbers. Elastomer using plastic elastomer or synthetic rubber
-Synthetic rubber type is known. Eraser with vinyl chloride resin as base resin, vinyl chloride resin and plasticizer,
It is made by heating a paste-like plastisol mixed with fillers and other additives as needed to cause the vinyl chloride resin to absorb the plasticizer. Erasers using natural rubber as a base resin are produced by mixing natural rubber with sub and filler materials and vulcanizing them. An eraser using a thermoplastic elastomer or a synthetic rubber as a base resin is prepared by mixing a thermoplastic elastomer or a synthetic rubber, a filler, and, if necessary, a softener, and then heat-molding the mixture in an unvulcanized state. Incidentally, the eraser needs to be worn by rubbing against the paper surface. This is for the following reason. The handwriting of a pencil or mechanical pencil is obtained by attaching powder of a pencil or mechanical pencil core worn by rubbing with paper to the paper surface. The abrasion powder of the core is removed from the paper surface by re-adhering to the surface of the eraser rubber or the surface of the eraser, and the handwriting is erased. At this time, if the eraser is worn and no eraser dust is generated, the eraser surface is covered with the core abrasion powder, the core abrasion powder cannot be attached any more, and the handwriting cannot be further erased. Not only that, the abrasion powder of the core once adhered to the eraser adheres to the paper again, causing the paper to become dirty.
For this reason, it is necessary that the eraser be worn out by rubbing with paper and produce eraser dust. In order to obtain such characteristics, for example, a vinyl chloride-based eraser is molded at a lower heating temperature than a normal vinyl chloride resin molded product. This is known from Japanese Patent Publication No. 32-8220. That is, Japanese Patent Publication No. 32-8220 discloses an eraser in which a plasticizer is added in an amount of 80 to 160% by weight of a vinyl chloride resin and heated at a relatively low temperature to cause a low degree of gelation. It is disclosed that the molding temperature is about 12
It is stated that a temperature of 5 to 135 ° C. is suitable. [0003] As described above, there is no need to collect erased scraps simply because the handwriting is erased. However, when the performance of an eraser is evaluated, it is very advantageous for the eraser that the eraser is collected. That is, if the erased dust is scattered on the portion of the paper to be erased, the handwriting to be erased is covered and the erasing status is unknown, and
If the erased dust that has become black due to the involvement of the handwriting covers the paper surface, the paper surface looks dirty, and the erasability is determined to be poor. Even when erased dust is collected, once it is generated as fine erased dust, if the erased dust is sandwiched between paper and eraser and the eraser and the paper are rubbed together, the erased dust is gathered together. If the number of necessary erasures is large and one or two characters are to be erased, the erasable dust is not well organized. In addition, the scraps that have been combined once become loose and become the original scraps. Scattered scraps are cumbersome to collect and stain desks and floors with the scraps. In order to make it easy to collect and erase the scraps, it is preferable that the scraps are united even when the number of erases is small. Therefore, it is sufficient to form the erased scraps as one erased scrap by kneading the erased scraps from the beginning of wear. That is, the problem to be solved by the present invention is that the erased dust is kneaded together from the beginning of wear and is generated as one erased dust, so that the erased dust can be gathered even with a very small number of rubs. Getting an eraser. SUMMARY OF THE INVENTION The present invention provides a method for manufacturing a semiconductor device having a surface elasticity of 3
00 to 420 g / mm and a surface strength of 700 to 13
The grit is an eraser characterized by being 00 g. The details will be described below. As the eraser according to the present invention, those conventionally used as a material for the eraser can be used. That is, even if a vinyl chloride resin, a vinyl chloride-vinyl acetate copolymer, or a vinyl chloride-based eraser obtained by using this vinyl chloride resin in combination with another resin is used as a base resin, a polyolefin-based thermoplastic elastomer or a polystyrene-based thermosetting rubber can be used. An elastomer using a plastic elastomer, or a synthetic rubber-based eraser may be used. As the components other than the base resin, those conventionally used as the material of the eraser can be used. That is, in the case of a vinyl chloride-based eraser, a plasticizer or a filler may be used, and in the case of an elastomer / synthetic rubber-based eraser, a filler or a softener may be appropriately selected and used. In the present invention, the eraser has a surface elasticity of 300 to 420 g / mm and a surface strength of 700 to 1
It needs to be 300 g. Here, the surface elasticity means that a disk having a diameter of 3.0 mm is applied to the eraser surface at a constant speed of 2.
When the disk is pushed at a rate of mm / min, it refers to the resistive load per unit length of the pushed disk. The term "surface strength" refers to a resistance load applied to a disk when a disk having a diameter of 3.0 mm is pushed into the surface of the eraser at a constant speed of 2 mm / min and the surface of the eraser is broken. When the disk is pushed into the eraser, the disk is arranged so that the surface of the eraser and the plane of the disk are parallel to each other, and the disk is pushed perpendicular to the surface of the eraser at a constant speed of 2 mm / min. At first, the surface of the eraser is depressed by being pushed by the disk, and a repulsive force is applied to the disk. Since this repulsive force increases in proportion to the length of the pressed disk, it is measured as a resistance load per length. As the disk is pushed into the eraser, the surface of the eraser is destroyed at some point, and a hole is opened in the pressed part of the disk. At this time, the repulsive force applied to the disk shows a maximum value, and this value is defined as the resistance load applied to the disk when the rubber surface is broken. In this case, the force measured is the eraser surface, so the measured value is
It is not the physical properties of the entire eraser, but the physical properties of the surface. In measuring surface elasticity and surface strength,
The use of a disk is particularly important for measuring surface strength.
This is because the outer peripheral portion of the member to be pushed acts uniformly on the eraser. The size of the disk greatly affects the values of surface elasticity and surface strength. Therefore, the size of the disk needs to be sufficiently smaller than the size of the eraser surface to be measured. For example, if the size of the disk is larger than the size of the eraser surface, the eraser surface will not be destroyed, and the entire eraser will be destroyed. It is considered necessary that the size of the eraser to be measured without being affected by the size of the eraser surface is larger than a circle having a diameter of at least three times the diameter of the disk. Further, it is considered that the thickness of the eraser to be measured is required to be at least twice the depth of the disk pressed when the breakage occurs. If the thickness of the eraser is too small, the entire eraser is destroyed, not the surface of the eraser. Since the above point and the size of the eraser actually used are limited, the size of the disk used for the measurement was set to 3.0 mm in diameter. The thickness of the disk is not relevant for the measurement result. It is necessary to measure the surface elasticity and the surface strength in a state as static as possible. In the present invention, the speed at which the disk is pushed into the eraser surface is 2 m.
m / min. [0010] The measured repulsive force has a surface elasticity of 300 to 420 g / mm and a surface strength of 80
Although it is assumed that the weight is 0 to 1300 g, the surface elasticity is 2.9 to 4.1 N / mm and the surface strength is 7.8 to 12.7 N in terms of force. The surface elasticity and surface strength of the eraser include molding temperature, heating time, shear force and pressure during molding in terms of molding conditions, and in terms of composition, the type of resin, the degree of polymerization, and the type of plasticizer. , The ratio between the resin and the plasticizer, and the type and amount of the filler. And, in order to obtain the eraser of the present invention, it is achieved by appropriately combining these conditions. For example, in the case of a vinyl chloride-based eraser, when a paste-like plastisol obtained by mixing a liquid plasticizer and a powdery vinyl chloride resin is heated, the vinyl chloride resin absorbs the plasticizer and swells. As the swelling proceeds further, the surfaces of the vinyl chloride resin particles begin to dissolve, and after cooling, the vinyl chloride resin particles are strongly bonded to each other at the dissolved portion. At this time,
The stronger the degree of bonding due to dissolution of the surface of the vinyl chloride resin particles, the greater the surface strength of the eraser, and the surface elasticity also increases to some extent. Methods for increasing the surface elasticity and surface strength by dissolving the surface of the vinyl chloride resin particles include increasing the heating temperature, reducing the amount of plasticizer / vinyl chloride resin, and using a plasticizer that is easily absorbed by the vinyl chloride resin. And a shear force or a pressure applied during heating. In addition, when the amount of the filler to be added increases, the bonding between the vinyl chloride resins is inhibited, and the surface elasticity increases. These facts can be said to be trends, and the surface elasticity is 300 to 420 g depending on the material to be blended.
/ Mm, the compounding ratio and molding conditions for making the surface strength 800 to 1300 g are different. In this way, the degree to which erased dust is united as one is determined as an overall result of many factors. The strength of the bonding force between the vinyl chloride resin particles that have swollen by absorbing the plasticizer, which is the force that prevents the eraser dust from sticking together as a result of being stuck, cannot be expressed only by surface strength, It is represented by two physical properties, surface elasticity and surface strength. Therefore, by simultaneously controlling the two physical properties of the surface elasticity and the surface strength, it is possible to combine erased scraps into one. If the surface elasticity is less than 300 g / mm or the surface strength is less than 800 g, the eraser is brittle and a number of large erases can be formed. When the surface elasticity is larger than 420 g / mm or the surface strength is larger than 1300 g,
The erased chips are not kneaded, but are more closely combined, so that the erased scraps are not united with a small number of erasures. The reason why the surface elasticity of the eraser is 300 to 420
g / mm and a surface strength of 800 to 1300 g, erased dust is generated as one erased dust by knitting the erased dust together from the beginning of abrasion. It is not clear whether they are united, but it is presumed as follows. In order for the eraser dust to be kneaded, when the abrasion powder worn from the eraser surface is subjected to a shearing force due to the rubbing motion between the eraser and the paper, the bonding force between the base resin particles in the abrasion powder is increased. And the base resin particles need to move alone. If the bonding between the base resin particles is strong, even if it is subjected to a shearing force, the shape of the abrasion powder remains as one abrasion powder, so that the eraser dust is collected in a form in which the abrasion powders are caused by the shearing force. Hereinafter, the present invention will be described in more detail with reference to examples. The eraser obtained in the following Examples and Comparative Examples was evaluated for the unity of erased dust. The following method was used to evaluate the unity of the erased dust. Distance 5c on paper like using normal eraser
m4 reciprocations. Let A be the weight of the largest erased lump mass generated at this time. Let B be the weight difference between the eraser before and after erasing. Assuming that the cohesiveness of the erased dust is C, C = (A / B) × 100%. And C ≧
At 80%, the eraser was apparently united in one. In the above-described measurement method, if the four reciprocations are performed only once, the weights of A and B are very small and the measurement error is large. Therefore, the measurement is actually repeated several tens of times, and the cohesiveness C of the erased dust is determined from the total A and B weights. Calculated. (Example of changing surface elasticity and surface strength by changing the blending ratio of polyvinyl chloride resin and plasticizer) Example 1 Vinyl chloride resin (Zeon 121: polymerization degree 1600: manufactured by Zeon Corporation) 100 parts by weight Plasticizer (diisononyl phthalate, hereinafter abbreviated as DINP) 160 parts by weight Stabilizer (epoxidized soybean oil) 1 part by weight Heavy calcium carbonate 35 parts by weight The above components are mixed and defoamed to obtain a plastisol. The container was filled into a container having a length of 12 mm and a width of 23 × 63 mm, and was heated and molded by a heating press machine at 123 ° C. for 20 minutes to obtain an eraser. Example 2 100 parts by weight of vinyl chloride resin (Zeon 121) 148 parts by weight of plasticizer (DINP) 1 part by weight of stabilizer (epoxidized soybean oil) 33 parts by weight of heavy calcium carbonate The above components were the same as in Example 1. Molded by the method to obtain an eraser. Comparative Example 1 100 parts by weight of vinyl chloride resin (Zeon 121) 136 parts by weight of plasticizer (DINP) 1 part by weight of stabilizer (epoxidized soybean oil) 32 parts by weight of heavy calcium carbonate Molding was performed in the same manner to obtain an eraser. Comparative Example 2 Vinyl chloride resin (Zeon 121) 100 parts by weight Plasticizer (DINP) 126 parts by weight Stabilizer (epoxidized soybean oil) 1 part by weight Heavy calcium carbonate 30 parts by weight The above components were the same as in Example 1. Molded by the method to obtain an eraser. Table 1 shows the surface elasticity, surface strength and unity of erased scraps of the erasers obtained in Examples 1 and 2 and Comparative Examples 1 and 2.
Shown in [Table 1] (Example in which surface elasticity and surface strength are changed by changing heating temperature) Example 3 In Example 1, the same procedure as in Example 1 was carried out except that the heat molding conditions were 120 ° C. and 20 minutes. I got an eraser. Comparative Example 3 An eraser was obtained in the same manner as in Example 1 except that the heat molding conditions were changed to 125 ° C. and 20 minutes. Comparative Example 4 An eraser was obtained in the same manner as in Example 1 except that the heat molding conditions were changed to 130 ° C. and 20 minutes. Table 2 shows the surface elasticity, surface strength, and unity of erased dust of the erasers obtained in Examples 1 and 3 and Comparative Examples 3 and 4.
Shown in [Table 2] (Example of changing surface elasticity and surface strength by changing the amount of filler) Example 4 100 parts by weight of vinyl chloride resin (Zeon 121) Plasticizer (Adecaizer PN-160: adipic acid-based polyester plasticizer) : Asahi Denka Kogyo Co., Ltd.) 160 parts by weight Stabilizer (epoxidized soybean oil) 1 part by weight Heavy calcium carbonate 35 parts by weight The above components were mixed and defoamed to obtain a plastisol, which was 12 mm in depth and 23 in width. The resultant was filled in a container having a size of × 63 mm, and was molded by heating at 130 ° C. for 20 minutes using a heating press to obtain an eraser. Comparative Example 5 Vinyl chloride resin (Zeon 121) 100 parts by weight Plasticizer (ADEKA SIZER PN-160) 160 parts by weight Stabilizer (epoxidized soybean oil) 1 part by weight Heavy calcium carbonate 122 parts by weight Molding was performed in the same manner as in Example 4 to obtain an eraser. Comparative Example 6 100 parts by weight of vinyl chloride resin (Zeon 121) 180 parts by weight of plasticizer (Adekasizer PN-160) 1 part by weight of stabilizer (epoxidized soybean oil) 1 part by weight 38 parts by weight of heavy calcium carbonate Molding was performed in the same manner as in Example 4 to obtain an eraser. Example 5 Vinyl chloride resin (Zeon 121) 100 parts by weight Plasticizer and stabilizer (epoxidized soybean oil) 160 parts by weight Heavy calcium carbonate 35 parts by weight The above components were molded in the same manner as in Example 4. I got an eraser. Example 6 Vinyl chloride resin (Zeon 121) 100 parts by weight Plasticizer and stabilizer (epoxidized soybean oil) 160 parts by weight Heavy calcium carbonate 122 parts by weight The above components were molded in the same manner as in Example 4. I got an eraser. Table 3 shows the surface elasticity, surface strength, and unity of erased scraps of the erasers obtained in Examples 4 to 6 and Comparative Examples 5 and 6.
Shown in [Table 3] (Example in which surface elasticity and surface strength were changed by using a vinyl chloride resin having a high degree of polymerization) Example 7 100 parts by weight of vinyl chloride resin (Zeon 43H: Degree of polymerization 3500: manufactured by Zeon Corporation) Plasticizer (DINP) 160 parts by weight Stabilizer (epoxidized soybean oil) 1 part by weight Heavy calcium carbonate 35 parts by weight The above components were molded in the same manner as in Example 4 to obtain an eraser. Comparative Example 7 An eraser was obtained in the same manner as in Example 7, except that the heat molding conditions were changed to 140 ° C. and 20 minutes. Comparative Example 8 Vinyl chloride resin (Zeon 43H) 100 parts by weight Plasticizer (DINP) 160 parts by weight Stabilizer (epoxidized soybean oil) 1 part by weight Heavy calcium carbonate 122 parts by weight The above components were the same as in Example 4. Molding was performed by the method to obtain an eraser. Table 4 shows the surface elasticity, surface strength and unitedness of erased scraps of the erasers obtained in Example 7 and Comparative Examples 7 and 8. [Table 4] Examples 8-10, Comparative Example 9 100 parts by weight of vinyl chloride resin (Zeon 121) 160 parts by weight of plasticizer (DINP) 1 part by weight of stabilizer (epoxidized soybean oil) 35 parts by weight of heavy calcium carbonate Was extruded using an extruder having a cylinder diameter of 65 mm and a screw having a compression ratio of 3 to obtain an eraser. Table 5 shows the temperature of each part of the extruder. [Table 5] Table 6 shows the surface elasticity, surface strength, and unity of erased scraps of the erasers obtained in Examples 8 to 10 and Comparative Example 9. [Table 6] As described above, the surface elasticity is 300 to 420 g / mm and the surface strength is 800 to
An eraser weighing 1300 g is one in which most of the erased waste is collected in one lump with a small number of times of rubbing.

Claims (1)

(57) Claims 1. An eraser having a surface elasticity of 300 to 420 g / mm and a surface strength of 700 to 1300 g.