Writing implement with erasing member

Abstract

To provide a writing instrument provided with a firmly fixed erasing member.SOLUTION: A writing instrument 1 includes a writing instrument main body 2, a cap 3, and a first erasing member 20 arranged at a first fixing end portion 12 protruding from a front end surface 13 of the cap 3. At least one vertical rib 16 lockably extending in the axial direction so as to prevent the rotation of the first erasing member 20 is formed on the first fixing end portion 12 of the cap 3. A locking recess 16c may be formed on the side surface of the vertical rib 16. The cross-sectional shape of the vertical rib 16 may be a fan shape or an inverted triangular shape.SELECTED DRAWING: Figure 7

Description

[Technical field]

[0001] The present invention relates to a writing instrument having an erasing member. [Background technology]

[0002] A writing instrument having an erasing member fixed to the top of a cap is known (for example, Patent Document 1). The writing instrument of Patent Document 1 ejects thermochromic ink. The erasing member of Patent Document 1 rubs the lines or characters written with thermochromic ink, and erases the lines or characters by discoloring the thermochromic ink with the frictional heat generated by the rub. The erasing member shown in Patent Document 1 is cylindrical and is fitted into a circular recess formed at the tip of the cap, or is molded integrally with the cap by two-color molding and fixed thereto. However, a cylindrical erasing member fitted into a simple circular recess may come off the cap if written characters or the like are repeatedly rubbed hard, even if the member is molded integrally with the cap by two-color molding.

[0003] In contrast, Patent Document 2 describes a writing instrument equipped with an attachment structure in which a horizontal hole extending perpendicular to the longitudinal direction is formed in the cap and a shaft-shaped portion is filled into the hole, thereby firmly fixing the erasing member. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2006-123324 A [Patent Document 2] JP 2016-078418 A Summary of the Invention [Problem to be solved by the invention]

[0005] In the mounting structure described in Patent Document 2, if the axial length of the erasing member is to be shortened, the diameter of the side hole must be made smaller. As a result, the side hole may not be filled sufficiently during manufacturing, making stable mass production difficult. Even if stable mass production is possible, the shaft part may have a smaller diameter, which weakens the strength of the shaft part, making it difficult to ensure sufficient mounting strength.

[0006] SUMMARY OF THE PRESENT EMBODIMENTS The present invention aims to provide a writing instrument with a firmly attached erasing member. [Means for solving the problem]

[0007] According to one aspect of the present invention, there is provided a writing instrument comprising a writing instrument body, a cap, and an erasing member arranged at a fixed end protruding from at least one of the rear end face of the writing instrument body and the front end face of the cap, wherein at least one of the fixed ends of the writing instrument body and the cap is formed with at least one vertical rib extending in the axial direction so as to be engageable to prevent rotation of the erasing member.

[0008] A locking recess may be formed on the side of the vertical rib. The cross-sectional shape of the vertical rib may be a sector shape or an inverted triangle shape. The fixed end may have a flange portion and a connection portion connecting the at least one end face and the flange portion, and the vertical rib may be formed on the connection portion. The at least one end face may be formed in a curved shape in close contact with the erasing member. The at least one end face and the erasing member may be joined by a multi-color molding method. The melting point of the material of the at least one end face may be different from the melting point of the material of the erasing member, so that no chemical bond may be formed between the at least one end face and the erasing member. It is preferable that the difference between the melting point of the material of the at least one end face and the melting point of the material of the erasing member is 50°C or more. Effect of the Invention

[0009] Aspects of the present invention have a common effect of providing a writing instrument with a firmly attached erasing member. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a vertical cross-sectional view of a writing instrument according to an embodiment of the present invention. [Diagram 2] FIG. 2 is an enlarged vertical cross-sectional view of the rear end of the writing instrument. [Diagram 3] FIG. 3 is a perspective view of the cap body. [Figure 4] FIG. 4 is a top view of the cap body. [Diagram 5] FIG. 5 is a perspective view of the cap. [Figure 6] FIG. 6 is a side view of the cap. [Figure 7] FIG. 7 is a vertical cross-sectional view of the cap. [Figure 8] FIG. 8 is a cross-sectional view taken along line AA in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Corresponding components throughout the drawings are designated by common reference numerals.

[0012] FIG. 1 is a vertical cross-sectional view of a writing instrument 1 according to an embodiment of the present invention, and FIG. 2 is an enlarged vertical cross-sectional view of the rear end portion of the writing instrument 1. As shown in FIG.

[0013] The writing instrument 1 has a writing instrument body 2 and a cap 3. The writing instrument body 2 has a barrel 6 formed in a cylindrical shape and equipped with a front barrel 4 and a rear barrel 5, and a refill 7 arranged in the barrel 6. The front barrel 4 and the rear barrel 5 are attached by screwing the rear end of the front barrel 4 into the front end of the rear barrel 5. A writing part 8 is provided at the front end of the refill 7. A hole is formed at the front end of the front barrel 4 to allow the writing part 8 of the refill 7 to protrude.

[0014] In this specification, in the axial direction of the writing instrument 1, the side of the writing part 8 is defined as the "front" side, and the side opposite the writing part 8 is defined as the "rear" side. In addition, in the longitudinal direction of the cap 3, the open end side into which the writing instrument body 2 is inserted is defined as the "rear" side, and the opposite closed end side is defined as the "front" side. Unless otherwise specified, the central axis or axial direction refers to the central axis or axial direction of the writing instrument 1 or cap 3.

[0015] The cap 3 has a cap body 10 and a first erasing member 20. The first erasing member 20 is disposed at the front end, i.e., the closed end, of the cap 3. A second erasing member 30 is disposed at the rear end of the writing instrument body 2, i.e., the rear end of the barrel 6.

[0016] Figure 3 is an oblique view of the cap main body 10, Figure 4 is a top view of the cap main body 10, Figure 5 is an oblique view of the cap 3, Figure 6 is a side view of the cap 3, Figure 7 is a longitudinal cross-sectional view of the cap 3, and Figure 8 is a cross-sectional view along line AA in Figure 7.

[0017] The cap 3 has a cylindrical cap body 10, a clip portion 11 extending from a side surface of the cap body 10 in the approximate longitudinal direction, and a first fixed end portion 12 to which the first erasing member 20 is fixed, which are integrally formed. The cap body 10 is formed to fit into the front shaft 4 of the barrel 6 of the writing instrument body 2.

[0018] The first fixed end 12 is formed so as to protrude from the front end face 13 of the cap 3. In detail, the first fixed end 12 of the cap 3 has a disk-shaped flange portion 14 having an outer diameter smaller than that of the cap body portion 10, a cylindrical connection portion 15 having a smaller diameter that connects the end face 13 and the flange portion 14, and two vertical ribs 16 formed on the connection portion 15. The periphery of the front end of the flange portion 14 is provided with a chamfered portion 14a formed to be chamfered. The cap body portion 10 and the first fixed end 12 are formed with a through hole 17 penetrating along the central axis.

[0019] The two longitudinal ribs 16 are arranged at equal intervals, i.e., 180 degrees apart, along the circumferential direction on the outer surface of the connecting portion 15. The number of the longitudinal ribs 16 may be at least one, and therefore may be one or three or more. The longitudinal rib 16 is formed on the side surface of the connecting portion 15 from the end surface 13 to the flange portion 14. As shown in Figs. 4 and 7, the longitudinal rib 16 has an inclined surface 16a inclined toward the front, i.e., toward the flange portion 14, in the central axis direction, and a flat surface 16b extending approximately parallel to the central axis connected to the front of the inclined surface 16a. As shown in Fig. 8, the longitudinal rib 16 has a sector-shaped or inverted triangular cross-sectional shape. Therefore, a locking recess 16c is formed on the side surface of the longitudinal rib 16 so as to define a sector-shaped or inverted triangular cross-sectional shape.

[0020] The end surface 13 of the cap 3 is curved and in close contact with the first erasing member 20. The first erasing member 20 has a contact surface 21 complementary to the end surface 13. Specifically, the shape of the end surface 13 is configured as a part of a cylindrical surface having a central axis perpendicular to the central axis of the cap 3. However, the end surface 13 may be configured as a part of a plane perpendicular to the central axis of the cap 3.

[0021] The outer surface of the first erasing member 20 is formed to be substantially flush with the outer surface of the front end of the cap body 10. The periphery of the front end of the first erasing member 20 is provided with a tapered portion 22 formed in a tapered shape. The first erasing member 20 has an annular locking protrusion 23 on the inside thereof, which is complementary to the flange portion 14 and the connecting portion 15 of the first fixed end 12 and therefore extends radially inward to fill the periphery. The first erasing member 20 has a through hole 24 penetrating along the central axis. As shown in FIG. 7, the through hole 17 of the cap body 10 and the through hole 24 of the first erasing member 20 integrally form one through hole. Thereby, even if an infant or the like accidentally swallows the cap 3, safety can be ensured without blocking the airway.

[0022] The first eraser member 20 is provided at the front end of the cap body 10 by two-color molding. First, the cap body 10 is injection molded as a primary molding. Then, a die cavity for molding the first eraser member 20 is combined with a die core in which the molded cap body 10 is left. Then, as a secondary molding, a material different from the cap body 10 is injected to additionally mold the first eraser member 20 on the cap body 10. By the two-color molding method, the cap body 10 and the first eraser member 20 are bonded with high strength by chemical bonding at the bonding surfaces between the cap body 10 and the first eraser member 20, depending on the material used, so that the first eraser member 20 is more firmly fixed to the cap body 10.

[0023] The material of the first erasing member 20 is, for example, a polyester-based elastomer. The melting point of a typical polyester-based elastomer is less than 100°C. In this case, if polycarbonate is selected as the material of the cap body 10, the melting point of the typical polycarbonate is 150°C or higher, so the melting point of the material of the cap body 10 and the melting point of the material of the first erasing member 20 are significantly different. Therefore, during secondary molding in which the polyester-based elastomer is injected, the interface of the polycarbonate cap body 10 molded by primary molding cannot be sufficiently melted. As a result, there are cases in which chemical bonds cannot be generated at the interface between the first erasing member 20 molded by secondary molding and the cap body 10 molded by primary molding to sufficiently bond them.

[0024] Here, the rubbing action applies forces in multiple directions to the first erasing member 20 to remove it from the cap body 10. Even if no chemical bond is formed or the chemical bond is insufficient at the joining surface between the cap body 10 and the first erasing member 20, i.e., the end surface 13 of the cap body 10 and the abutting surface 21 of the first erasing member 20, the first erasing member 20 is firmly locked to the first fixed end 12 of the cap body 10 and is prevented from coming off during the rubbing action.

[0025] That is, against a force that tends to move the first erasing member 20 away from the first erasing member 20 in the axial direction, the flange portion 14 of the first fixed end portion 12 engages with the locking protrusions 23 of the first erasing member 20, preventing the first erasing member 20 from moving in the axial direction. Also, against a force that tends to rotate the first erasing member 20 about the axis, the vertical rib 16 of the first fixed end portion 12 engages with the locking protrusions 23 of the first erasing member 20, preventing the first erasing member 20 from rotating. In particular, because the vertical rib 16 has a sector-shaped or inverted triangular cross section, i.e., because it has the locking recesses 16c, the side surface of the vertical rib 16 is tightly locked with the locking protrusions 23 of the first erasing member 20. That is, the engagement recess 16c of the vertical rib 16 comes into contact with the engagement protrusion 23 of the second erasing member 30, generating a radially inward component force from the force rotating the first erasing member 20, which biases the engagement protrusion 23 of the second erasing member 30 radially inward. As a result, the second erasing member 30 is more firmly fixed to the first fixed end 12 of the cap body 10.

[0026] The vertical rib 16 can be configured as desired as long as it can be engaged with the first fixed end 12 so as to prevent the first erasing member 20 from rotating. For example, the vertical rib 16 does not have to be formed from the end face 13 of the cap body 10 to the flange 14, and may be formed in a portion of the connection portion 15 separated from both. In addition, the vertical rib 16 only needs to have an engagement recess 16c on the side, and the shape of the engagement recess 16c may be configured as desired. Therefore, the cross-sectional shape of the vertical rib 16 does not have to be a sector shape or an inverted triangle shape. In addition, the engagement recess 16c does not have to be formed along the entire length of the vertical rib 16, and may be formed at least in a portion of the longitudinal direction of the vertical rib 16.

[0027] For the reasons described above, in general, when performing two-color molding, it is preferable that the difference between the melting points of the primary molding material and the secondary molding material is small, but even if the difference is large, the above-mentioned mounting structure allows the first eraser member 20 to be firmly fixed to the cap body 10. The above-mentioned mounting structure is more effective when the difference in melting point between the primary molding material and the secondary molding material is 50°C or more. This allows for a wider range of materials to be selected for the first eraser member 20 and the cap body 10.

[0028] The above melting point refers to the peak top melting point of the peak appearing on the highest temperature side in the second melting curve (i.e., the melting curve measured during the final heating process) when measured using a DSC type differential scanning calorimeter (e.g., Diamond manufactured by PerkinElmer Japan Co., Ltd.) according to a program of holding at 230°C for 5 minutes, then cooling to -10°C at 10°C / min, then holding at -10°C for 5 minutes, and then heating to 230°C at 10°C / min.

[0029] The material of the cap body 10 is preferably an engineering plastic from the viewpoint of forming the main body of the cap 3. Therefore, examples of the material of the cap body 10 include polyether ether ketone, polyamide, polyacetal, polybutylene terephthalate, modified polyphenylene ether, and the like, in addition to polycarbonate. On the other hand, the material of the first erasing member 20 will be described later as a material serving as a friction body, and is preferably a material that is softer than the cap body 10 due to the nature of the erasing member.

[0030] Furthermore, since there is no minute closed space such as the side hole in the mounting structure described in Patent Document 2 in the first fixed end 12 of the cap body 10, no insufficient filling occurs during two-color molding, and mass production can be easily performed. Also, since there is no side hole in the mounting structure described in Patent Document 2, the axial length of the first erasing member 20 can be designed to be short. Therefore, for example, a configuration such as an end face 13 formed in a curved shape can be realized.

[0031] The rear barrel 5 has a cylindrical rear barrel body portion 5a that accommodates the majority of the refill 7, and a rear second fixed end portion 5b that is integrally formed therewith and protrudes from the rear end face. The second fixed end portion 5b is formed in a generally truncated cone shape having an outer diameter smaller than the outer diameter of the rear barrel body portion 5a. The outer peripheral surface of the second fixed end portion 5b is formed with a first annular convex portion 51 that protrudes radially outward and a second annular convex portion 52 that is parallel thereto, so that a first annular recess 53 is formed between the rear barrel body portion 5a, and a second annular recess 54 is formed between the first protrusion 51 and the second protrusion 52. The first recess 53 and the second recess 54 in the rear barrel 5 are recessed from the outer peripheral surface of the second fixed end portion 5b in a direction perpendicular to the longitudinal direction of the writing instrument 1. At least one of the first recess 53 and the second recess 54 may be formed as a discontinuous annular recess.

[0032] The second fixed end 5b has a vertical hole 55 that is reduced in diameter and extends continuously in the longitudinal direction from a hole formed inside the rear body portion 5a. The second fixed end 5b also has a horizontal hole 56 that extends perpendicular to the longitudinal direction. The horizontal hole 56 penetrates the second fixed end 5b perpendicular to the vertical hole 55.

[0033] The second erasing member 30 is provided at the rear end of the rear shaft 5 by two-color molding. The second erasing member 30 has an inner shaft portion 30a that is complementary to the lateral hole 56 of the second fixed end portion 5b and thus fills the lateral hole 56. Furthermore, the second erasing member 30 has annular first convex portion 30b and second convex portion 30c that are complementary to the annular first recess 53 and second recess 54 of the second fixed end portion 5b, respectively, and thus extend radially inward to fill them.

[0034] Even if a force acts to pull the second erasing member 30 out of the second fixed end 5b during use, the first recess 53 and the second recess 54 and the horizontal hole 86 formed in the second fixed end 5b of the rear axle 5 are fitted or locked with the first protrusion 30b and the second protrusion 30c and the shaft portion 30a of the second erasing member 30 that fill them, thereby preventing the second erasing member 30 from coming off. Therefore, even if no adhesive or bonding force can be expected between the surface of the second fixed end 5b and the inner surface of the second erasing member 30, the second erasing member 30 can be firmly fixed to the second fixed end 5b of the rear axle 5.

[0035] The cap body 10 and the first erasing member 20, as well as the rear shaft 5 and the second erasing member 30, are each molded by a two-color molding method, but they may be molded by a multi-color molding method using three or more colors to improve performance or function, or for design requirements.

[0036] The mounting structure of the first erasing member 20 using the first fixed end 12 may be applied to the mounting structure of the second erasing member 30 using the second fixed end 5b. The first erasing member 20 and the second erasing member 30 may be attached to the writing instrument body 2 or the cap 3 by attachment, not by two-color molding. The writing instrument 1 may have only one of the first erasing member 20 and the second erasing member 30 having the above-mentioned mounting structure.

[0037] In short, the writing instrument 1 may be configured to include an erasing member arranged at a fixed end protruding from at least one of the rear end face of the writing instrument body 2 and the front end face of the cap 3, and at least one of the fixed ends of the writing instrument body 2 and the cap 3 is formed with at least one vertical rib extending in the axial direction so as to be engageable to prevent rotation of the erasing member.

[0038] The first eraser member 20 and the second eraser member 30 may be formed from different materials. Different materials refer to materials with different compounding components or different mechanical properties. This results in different tactile sensations felt by the user when rubbing, allowing the user to use the first eraser member 20 and the second eraser member 30 according to preference. In addition, the first eraser member 20 and the second eraser member 30 may be colored in a color that is the same as or similar to the color of the ink contained in the refill 7. This prevents ink from adhering to the first eraser member 20 and the second eraser member 30 when rubbing the handwriting, as a stain.

[0039] Furthermore, the first erasing member 20 and the second erasing member 30 are made to be substantially the same color as the ink in the refill 7, and the distance between the first erasing member 20 and the second erasing member 30 is set to 110 to 140 mm, more preferably 120 to 130 mm, thereby making it easy to see the ink color of the refill 7 even if the barrel 6 and the cap 3 are a different color from the ink and are opaque.

[0040] In this embodiment, the refill 7 is a refill that contains a thermochromic ink containing a thermochromic coloring material. Therefore, the writing instrument 1 is a thermochromic writing instrument, and the first erasing member 20 and the second erasing member 30 are friction bodies. Handwriting by the writing instrument 1 can be thermochromic due to frictional heat generated when the first erasing member 20 and the second erasing member 30 rub against each other.

[0041] Here, the thermochromic ink refers to an ink that has the property of maintaining a predetermined color (first color) at room temperature (e.g., 25°C), changing to another color (second color) when heated to a predetermined temperature (e.g., 60°C), and then returning to the original color (first color) when cooled to a predetermined temperature (e.g., -5°C). In the writing instrument 1 using the thermochromic ink, the second color is made colorless, and the term "erasing" refers to heating a line drawn in the first color (e.g., red) to make it colorless. Therefore, the line is rubbed against the writing surface on which it was drawn with a friction body to generate frictional heat, which changes the drawn line to colorless, that is, erases it. It should be noted that the second color may be a color other than colorless.

[0042] The surface roughness of the friction body is preferably arithmetic mean roughness Ra=7 μm to 14 μm as measured according to JIS B0601. If the arithmetic mean roughness Ra is smaller than 7 μm, the friction resistance during rubbing is also small, making it difficult to generate sufficient frictional heat. If the arithmetic mean roughness Ra is larger than 14 μm, there is a risk of damaging the writing surface during rubbing.

[0043] The ink storage portion of the refill 7 is made of synthetic resin, and its tensile modulus is 700 to 1800 MPa (JIS K7161). By setting the tensile modulus within this range, if the first erasing member 20 and the second erasing member 30 become worn and unusable, the rear end of the refill 7 can be used as a friction body, and sufficient rigidity to withstand rubbing operations can be ensured. When the refill 7 is not in use, a resin ball is attached to the writing part 8. The resin ball is removed when the refill 7 is first used, but by forming the resin ball from a blue resin material that does not contain titanium oxide, the initial writing properties of the thermochromic ink can be improved.

[0044] The friction material has a controlled balance between Shore A hardness and compression set in the high temperature range, so that it has an appropriate hardness and exhibits good deformation recovery even at high temperatures. This allows images with thermochromic properties to be discolored well by rubbing (i.e., provides good discoloration), and since the friction material is unlikely to be destroyed by strong force and / or repeated rubbing operations, it is possible to reduce contamination of the paper surface.

[0045] The friction body has a compression set at 120° C. (also referred to as "120° C. compression set" in the present disclosure) of 80% or less. A small 120° C. compression set is an indicator of good deformation recovery of the friction body under abrasive conditions (i.e., high temperature conditions), and this good deformation recovery contributes to maintaining good wear resistance of the friction body, particularly under abrasive conditions (i.e., high temperature conditions).

[0046] From the viewpoint of good wear resistance of the friction body under high temperature conditions, the 120°C compression set may be 80% or less, 70% or less, or 60% or less. From the viewpoint of wear resistance under high temperature conditions, the smaller the 120°C compression set, the more preferable. In the present disclosure, the compression set is a value measured in accordance with JIS K6262-2013.

[0047] In general, the compression set of a molded body made of an elastomer tends to increase with increasing temperature. The friction body of the present disclosure has a small 120°C compression set within the above-mentioned specific range. From the viewpoint of obtaining such a 120°C compression set, it is advantageous to reduce the temperature dependency of the compression set in the friction body. In the friction body, the ratio (A) / (B) of the compression set (A) at 120°C to the compression set (B) at 70°C may be 1.0 or more and 1.7 or less, 1.0 or more and 1.5 or less, 1.0 or more and 1.4 or less, or 1.0 or more and 1.3 or less.

[0048] The friction body has a Shore A hardness of 60 to 98. The Shore A hardness may be 60 or more, 70 or more, or 80 or more, from the viewpoint of good discoloration of the thermochromic image and good abrasion resistance of the friction body. The Shore A hardness may be 98 or less, 95 or less, or 90 or less, from the viewpoint that the contact area with the paper surface can be increased by pressing the friction body against the paper surface, and therefore good discoloration can be easily obtained. In the present disclosure, the Shore A hardness is a value measured in accordance with JIS K 6253-3-2012.

[0049] The composition of the material components constituting the friction body of the present disclosure is designed to give the desired 120°C compression set and Shore A hardness as described above. The friction body typically includes an elastomer component and an additive component. Below, examples of material components suitable for forming a friction body in which both the 120°C compression set and the Shore A hardness are controlled within the desired range of the present disclosure are given, but the material components are not limited to the following examples.

[0050] [Elastomer component (component (A))] Examples of the elastomer component include a styrene-based elastomer, a polyester-based elastomer, and an olefin-based elastomer. In terms of ease of achieving the desired 120°C compression set and Shore A hardness, the elastomer component includes a styrene-based elastomer, and is preferably made of a styrene-based elastomer.

[0051] In the present disclosure, the term "styrene-based elastomer" refers to an elastomer containing a styrene structural unit in the main chain, and is typically a thermoplastic elastomer. From the viewpoint of easily achieving the desired 120°C compression set and Shore A hardness, the styrene-based elastomer is preferably a block copolymer having a polymer block mainly composed of structural units derived from a styrene skeleton-containing compound and a polymer block mainly composed of structural units derived from a conjugated diene compound (hereinafter referred to as a styrene-based block copolymer), or a hydrogenated product of the block copolymer, or a mixture thereof. The above-mentioned "polymer block mainly composed of structural units derived from a styrene skeleton-containing compound (or a conjugated diene compound)" refers to a polymer block in which the structural units present in the highest mass ratio in the polymer block are structural units derived from a styrene skeleton-containing compound (or a conjugated diene compound).

[0052] The styrene-based block copolymer is usually a block copolymer having one or more polymer blocks X, preferably two or more from the viewpoint of mechanical properties, mainly composed of structural units derived from a styrene skeleton-containing compound, and one or more polymer blocks Y mainly composed of structural units derived from a conjugated diene compound. Examples of such block copolymers include block copolymers having structures such as XY, XYX, YXYX, and XYXYX.

[0053] The hydrogenated product of the styrene block copolymer can be obtained by adding hydrogen to the carbon-carbon double bonds in the styrene block copolymer to convert them into carbon-carbon single bonds. The hydrogenation can be carried out by a known method, for example, by hydrogenation in an inert solvent using a hydrogenation catalyst.

[0054] The hydrogenation rate of the hydrogenated product of the styrene-based block copolymer (i.e., the ratio of the number of carbon-carbon single bonds generated by hydrogenation to the number of carbon-carbon double bonds in the styrene-based block copolymer before hydrogenation) may be 50% or more, 70% or more, or 90% or more from the viewpoint of improving erasability, paper surface staining resistance, and abrasion resistance. The hydrogenation rate means a value measured by 1H-NMR unless otherwise specified.

[0055] The styrene skeleton-containing compound is a polymerizable monomer having a polymerizable carbon-carbon double bond and an aromatic ring. Examples of the styrene skeleton-containing compound include styrene, t-butylstyrene, α-methylstyrene, divinylbenzene, 1,1-diphenylstyrene, N,N-diethyl-p-aminoethylstyrene, p-tert-butylstyrene, and alkylstyrenes in which at least one alkyl group having 1 to 8 carbon atoms is bonded to a benzene ring. Among these, styrene and alkylstyrenes in which at least one alkyl group having 1 to 8 carbon atoms is bonded to a benzene ring are preferred. As the styrene skeleton-containing compound, one or more of these can be used.

[0056] Examples of the alkylstyrene in which at least one of the alkyl groups having 1 to 8 carbon atoms is bonded to a benzene ring include alkylstyrenes such as o-alkylstyrene, m-alkylstyrene, p-alkylstyrene, 2,4-dialkylstyrene, 3,5-dialkylstyrene, and 2,4,6-trialkylstyrene, as well as halogenated alkylstyrenes in which one or more hydrogen atoms of the alkyl group in these alkylstyrenes are substituted with halogen atoms. More specifically, for example, o-methylstyrene, m-methylstyrene, p-methylstyrene, 2,4-dimethylstyrene, 3,5-dimethylstyrene, 2,4,6-trimethylstyrene, o-ethylstyrene, m-ethylstyrene, p-ethylstyrene, 2,4-diethylstyrene, 3,5-diethylstyrene, 2,4,6-triethylstyrene, o-propylstyrene, m-propylstyrene, p-propylstyrene, 2,4-dipropylstyrene, 3,5-dipropylstyrene, 2,4,6-tripropylstyrene, 2-methyl-4-ethylstyrene, 3-methyl-5-ethylstyrene, o-chloromethylstyrene, m-chloromethylstyrene, p-chloromethylstyrene, 2,4-bis(chloromethyl)styrene, 3,5-bis(chloromethyl)styrene, 2,4,6-tri(chloromethyl)styrene, o-dichloromethylstyrene, m-dichloromethylstyrene, and p-dichloromethylstyrene, etc. Among these, p-methylstyrene is particularly preferred from the viewpoint of crosslinkability.

[0057] The alkylstyrene in which at least one of the alkyl groups having 1 to 8 carbon atoms is bonded to a benzene ring is suitably used as a material for a crosslinked styrene-based elastomer.

[0058] In the polymer block X, the proportion of the alkylstyrene in which at least one of the alkyl groups having 1 to 8 carbon atoms is bonded to a benzene ring is preferably 1% by mass or more, more preferably 50% by mass or more, and may even be 100% by mass, from the viewpoint of crosslinkability.

[0059] The conjugated diene compound is a polymerizable monomer having a structure in which two carbon-carbon double bonds are bonded by one carbon-carbon single bond. Examples of the conjugated diene compound include 1,3-butadiene, isoprene (2-methyl-1,3-butadiene), 2,3-dimethyl-1,3-butadiene, and chloroprene (2-chloro-1,3-butadiene). Among these, 1,3-butadiene and isoprene are preferred. As the conjugated diene compound, one or more of these can be used.

[0060] The content of the structural units derived from the styrene skeleton-containing compound in the styrene block copolymer or its hydrogenated product is not particularly limited, but may be 5 to 50% by mass, or 20 to 40% by mass, from the viewpoints of mechanical strength, cold resistance, heat resistance, and flexibility.

[0061] The polymer block X is preferably a polymer block derived only from the styrene skeleton-containing compound, or a copolymer block of the styrene skeleton-containing compound and the conjugated diene compound. When the polymer block X is the copolymer block, the content of the structural unit derived from the styrene skeleton-containing compound in the polymer block X in the copolymer block is not particularly limited, but from the viewpoint of heat resistance, it may be usually 50 mass% or more, 70 mass% or more, or 90 mass% or more. The distribution of the structural unit derived from the conjugated diene compound in the polymer block X is not particularly limited. When there are two or more polymer blocks X in the styrene-based elastomer molecule, they may have the same structure or different structures.

[0062] The polymer block Y is preferably a polymer block consisting of only the conjugated diene compound, or a copolymer block of the styrene skeleton-containing compound and the conjugated diene compound. When the polymer block Y is the copolymer block, the content of the conjugated diene compound-derived structural unit in the copolymer block is not particularly limited, but may be usually 50% by mass or more, 70% by mass or more, or 90% by mass or more from the viewpoint of heat resistance. The distribution of the styrene skeleton-containing compound-derived structural unit in the polymer block Y is not particularly limited. The bonding mode between the conjugated diene compound and the styrene skeleton-containing compound is not particularly limited. When there are two or more polymer blocks Y in a styrene-based elastomer molecule, they may have the same structure or different structures.

[0063] Examples of the styrene-based block copolymer include a styrene-butadiene-styrene block copolymer (SBS) and a styrene-isoprene-styrene block copolymer (SIS).

[0064] Examples of the hydrogenated products of the above-mentioned styrene-based block copolymers include styrene-ethylene-butene copolymers (SEB), styrene-ethylene-propylene copolymers (SEP), styrene-ethylene-butene-styrene copolymers (SEBS), styrene-ethylene-propylene-styrene copolymers (SEPS), and styrene-ethylene-ethylene-propylene-styrene copolymers (SEEPS).

[0065] Among these, styrene-ethylene-propylene-styrene (SEPS), styrene-ethylene-ethylene-propylene-styrene (SEEPS) and styrene-ethylene-butadiene-styrene (SEBS) are preferred, and in particular, styrene-ethylene-propylene-styrene copolymer (SEPS) and styrene-ethylene-ethylene-propylene-styrene copolymer (SEEPS) are preferred from the viewpoint of abrasion resistance.

[0066] The above-listed styrene-based block copolymers and / or hydrogenated products thereof can be used alone or in a mixture of two or more.

[0067] The styrene-based elastomer may be crosslinked. Increasing the degree of crosslinking contributes to reducing the 120°C compression set and increasing the Shore A hardness. In this case, SEBS, SEPS, and SEEPS, in which styrene is replaced with p-methylstyrene, are preferred from the viewpoint of heat resistance and wear resistance. Whether the styrene-based elastomer is crosslinked or not can be distinguished by visually observing whether a gel remains or not or by measuring the remaining weight after immersion in hot xylene at 120°C for 24 hours. For example, a crosslinking agent (component (E)) described later can be used for crosslinking. In an exemplary embodiment, the friction body may not contain a polymer insoluble in hot xylene at 120°C other than the crosslinked styrene-based elastomer. In this case, whether the styrene-based elastomer is crosslinked or not can also be evaluated by subjecting the friction body to the above-mentioned hot xylene treatment.

[0068] The mass average molecular weight (Mw) of the styrene-based elastomer is preferably 150,000 to 500,000. From the viewpoint of obtaining a friction body having good abrasion resistance, the mass average molecular weight may be 150,000 or more, 180,000 or more, or 200,000 or more. On the other hand, from the viewpoint of obtaining good processability during the production of the friction body, the mass average molecular weight may be 500,000 or less, 450,000 or less, or 400,000 or less. In the present disclosure, the molecular weight means a value in terms of polystyrene measured by gel permeation chromatography (GPC) unless otherwise specified.

[0069] [Other ingredients] Examples of other components that can be used include one or more of a propylene-based resin (hereinafter, component (B)), a rubber softener (hereinafter, component (C)), a lubricant (hereinafter, component (D)), a crosslinking agent (hereinafter, component (E)), a crosslinking aid (hereinafter, component (F)), a colorant (hereinafter, component (G)), a polymer component other than the above-mentioned propylene-based resin, a stabilizer, a filler, and the like.

[0070] [Propylene-based resin (component (B))] The use of a propylene-based resin (component (B)) is advantageous in improving the wear resistance and paper surface staining resistance of the friction body. Examples of the component (B) include propylene homopolymers, propylene random copolymers, and propylene block copolymers, which can be used alone or in combination of two or more. From the viewpoint of heat resistance, propylene homopolymers and propylene block copolymers are more preferable, and propylene homopolymers are even more preferable.

[0071] Propylene homopolymer is a polymer composed only of propylene units and has high crystallinity, and is therefore most preferred as component (B).

[0072] Examples of propylene-based random copolymers include propylene-ethylene random copolymers obtained by copolymerizing propylene and ethylene, propylene-α-olefin random copolymers obtained by copolymerizing propylene and at least one α-olefin having 4 to 20 carbon atoms, and propylene-ethylene-α-olefin random copolymers obtained by copolymerizing propylene, ethylene, and at least one α-olefin having 4 to 20 carbon atoms.

[0073] Examples of α-olefins having 4 to 20 carbon atoms include 1-butene, 2-methyl-1-propene, 1-pentene, 2-methyl-1-butene, 3-methyl-1-butene, 1-hexene, 2-ethyl-1-butene, 2,3-dimethyl-1-butene, 2-methyl-1-pentene, 3-methyl-1-pentene, 4-methyl-1-pentene, 3,3-dimethyl-1-butene, 1-heptene, methyl-1-hexene, and dimethyl Examples of the α-olefin having 4 to 20 carbon atoms include 1-butene, ethyl-1-pentene, trimethyl-1-butene, methylethyl-1-butene, 1-octene, methyl-1-pentene, ethyl-1-hexene, dimethyl-1-hexene, propyl-1-heptene, methylethyl-1-heptene, trimethyl-1-pentene, propyl-1-pentene, diethyl-1-butene, 1-nonene, 1-decene, 1-undecene, and 1-dodecene. The α-olefin having 4 to 20 carbon atoms is preferably 1-butene, 1-pentene, 1-hexene, and 1-octene, and more preferably 1-butene and 1-hexene.

[0074] Specific examples of propylene-based random copolymers include propylene-ethylene random copolymers, propylene-1-butene random copolymers, propylene-1-hexene random copolymers, propylene-1-octene random copolymers, propylene-ethylene-1-butene random copolymers, propylene-ethylene-1-hexene random copolymers, and propylene-ethylene-1-octene random copolymers, and preferably propylene-ethylene random copolymers, propylene-1-butene random copolymers, propylene-1-hexene random copolymers, propylene-ethylene-1-butene random copolymers, and propylene-ethylene-1-hexene random copolymers.

[0075] The propylene-based block copolymers include block copolymers consisting of a crystalline propylene-based polymer segment and a non-crystalline propylene-α-olefin copolymer segment.

[0076] The crystalline propylene polymer is a homopolymer of propylene or a polymer of propylene and a small amount of Random copolymers with other α-olefins are also examples.

[0077] On the other hand, examples of the non-crystalline propylene-α-olefin copolymer include non-crystalline random copolymers of propylene and other α-olefins. The other α-olefins preferably have 2 or 4 to 12 carbon atoms, and specific examples include ethylene, 1-butene, 3-methyl-1-butene, 3-methyl-1-pentene, 4-methyl-1-pentene, 4,4-dimethyl-1-pentene, vinylcyclopentane, and vinylcyclohexane. These α-olefins can be used alone or in combination of two or more.

[0078] As the propylene-based block copolymer, in addition to the above-mentioned other α-olefins, ternary or quaternary or higher copolymers copolymerized with non-conjugated dienes such as 1,4-hexadiene, 5-methyl-1,5-hexadiene, 1,4-octadiene, cyclohexadiene, cyclooctadiene, dicyclopentadiene, 5-methylene-2-norbornene, 5-ethylidene-2-norbornene, 5-butylidene-2-norbornene, and 5-isopropenyl-2-norbornene can also be used.

[0079] From the viewpoint of moldability, the melt mass flow rate of the component (B) may be 0.01 to 100 g / 10 min, 0.1 to 50 g / 10 min, or 0.3 to 10 g / 10 min when measured in accordance with JIS K 7210-1999 under conditions of 230° C. and 21.18 N.

[0080] The blending amount of the component (B) may be 30 to 300 parts by mass, 35 to 250 parts by mass, or 40 to 180 parts by mass per 100 parts by mass of the component (A). By being in this range, a good balance of flexibility, abrasion resistance, and paper surface staining resistance is achieved.

[0081] [Rubber softener (component (C))] As the rubber softener (component (C)), various compounds that are understood by those skilled in the art to function as a softener in the art can be used. The use of component (C) is advantageous in improving the flexibility of the friction body. The above-mentioned component (C) is typically a non-aromatic rubber softener. Examples of non-aromatic rubber softeners are non-aromatic mineral oils (i.e., hydrocarbon compounds derived from petroleum, etc., which are not classified as aromatic in the classification described below (i.e., the number of aromatic carbon atoms is less than 30%)) or non-aromatic synthetic oils (i.e., synthetic hydrocarbon compounds that do not use aromatic monomers). Non-aromatic rubber softeners are usually liquid, gel, or gum-like at room temperature.

[0082] The mineral oil used as component (C) is a mixture of compounds having one or more of paraffin chains, naphthenic rings, and aromatic rings. Those having 30 to 45% naphthenic rings, based on the carbon number, are called naphthenic mineral oils, those having 30% or more aromatic rings are called aromatic mineral oils, and those not belonging to either naphthenic mineral oils or aromatic mineral oils and having 50% or more paraffin chains, based on the carbon number, are called paraffinic mineral oils.

[0083] Examples of the component (C) include paraffinic mineral oils such as linear saturated hydrocarbons, branched saturated hydrocarbons, and derivatives thereof; naphthenic mineral oils; synthetic oils such as hydrogenated polyisobutylene, polyisobutylene, and polybutene; and the like. Among these, paraffinic mineral oils are preferred from the viewpoint of compatibility with the elastomer component, and paraffinic mineral oils with a small number of aromatic carbon atoms are more preferred. Also, from the viewpoint of handling, those that are liquid at room temperature are preferred.

[0084] From the viewpoint of heat resistance and handleability, the dynamic viscosity of the component (C) at 37.8°C measured in accordance with JIS K2283-2000 may be 20 to 1000 cSt, or 50 to 500 cSt. From the viewpoint of handleability, the pour point of the component (C) measured in accordance with JIS K2269-1987 may be -10 to -25°C. From the viewpoint of safety, the flash point (COC) of the component (C) measured in accordance with JIS K2265-2007 may be 170 to 300°C.

[0085] The blending amount of the component (C) may be 1 to 400 parts by mass, 10 to 250 parts by mass, or 40 to 180 parts by mass, based on 100 parts by mass of the component (A), from the viewpoint of the balance between flexibility and mechanical properties.

[0086] [Lubricant (Component (D))] As the lubricant (component (D)), various compounds that are understood by those skilled in the art to function as lubricants can be used. The use of component (D) is advantageous in terms of mold release properties and friction suppression on the paper surface.

[0087] Examples of the component (D) include silicone-based compounds, fluorine-based compounds, surfactants, etc., and from the viewpoint of suppressing friction on the paper surface, silicone-based compounds are preferred.

[0088] As the silicone compound, silicone oil, silicone gum, etc. can be used. Among these, from the viewpoint of heat resistance, bleeding resistance, and friction suppression of the paper surface, high molecular weight compounds are preferred. However, since high molecular weight silicone compounds are generally in the form of a high viscosity liquid or gum, which tends to make them difficult to handle, blends with resins or copolymers with resins are preferred for use. The resin used here is selected in consideration of compatibility with other components constituting the friction body, particularly component (A), and generally olefin resins such as polyethylene and polypropylene are preferred.

[0089] As the fluorine-based compound, polyvinylidene fluoride, polyvinyl fluoride, etc. can be used. Among these, polyvinylidene fluoride is preferred from the viewpoint of suppressing friction on the paper surface.

[0090] The surfactant may be any of anionic, cationic and nonionic surfactants.

[0091] The blending amount of the above component (D) may be 0.1 to 30 parts by mass, 0.5 to 20 parts by mass, or 1 to 10 parts by mass, based on 100 parts by mass of the above component (A), from the viewpoint of suppressing friction on the paper surface.

[0092] The content of component (D) in the friction body (the content of silicone oil in a preferred embodiment, or the content of a fluorine-based compound in another preferred embodiment) is preferably 0.1 to 3.0% by mass. From the viewpoint of suppressing friction on the paper surface, the content may be 0.1% by mass or more, 0.3% by mass or more, or 0.5% by mass or more, and from the viewpoint of obtaining good erasing performance and paper surface staining resistance, the content may be 3.0% by mass or less, 2.5% by mass or less, or 2.0% by mass or less.

[0093] [Crosslinking agent (component (E))] As the crosslinking agent (component (E)), various compounds that are understood by those skilled in the art to function as a crosslinking agent in the art can be used. In the friction body, component (E) is blended mainly for the purpose of crosslinking component (A). The use of component (E) is advantageous in reducing the 120°C compression set and increasing the Shore A hardness.

[0094] Examples of the component (E) include organic peroxides and phenolic compounds, with organic peroxides being preferred from the standpoint of wear resistance.

[0095] The organic peroxide is a compound in which one or two hydrogen atoms of hydrogen peroxide are replaced with a free organic group. Since the organic peroxide has a peroxide bond in its molecule, it generates radicals when the friction body is produced (for example, when the material composition is melt-kneaded), and the radicals undergo a chain reaction to crosslink the component (A).

[0096] Examples of the organic peroxide include dicumyl peroxide, di-tert-butyl peroxide, 2,5-dimethyl-2,5-di-(tert-butylperoxy)hexane, 2,5-dimethyl-2,5-di-(tert-butylperoxy)hexyne-3, 1,3-bis(tert-butylperoxyisopropyl)benzene, 1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane, n-butyl-4,4-bis(tert-butylperoxy)valerate, benzoyl peroxide, p-chlorobenzoyl peroxide, 2,4-dichlorobenzoyl peroxide, tert-butyl peroxybenzoate, tert-butylperoxyisopropyl carbonate, diacetyl peroxide, lauroyl peroxide, and tert-butylcumyl peroxide. Among these, 2,5-dimethyl-2,5-di-(tert-butylperoxy)hexane and 2,5-dimethyl-2,5-di-(tert-butylperoxy)hexyne-3 are preferred from the viewpoints of low odor, low coloration, and scorch safety.

[0097] When an organic peroxide is used as component (E), it is preferable to also use a crosslinking aid (component (F)) described below. By using component (F), a uniform and efficient crosslinking reaction can be carried out.

[0098] As the phenolic compound, a resol resin is preferred from the viewpoint of being normally liquid. The resol resin is produced by condensation of an alkyl-substituted or unsubstituted phenol with an aldehyde (preferably formaldehyde) in an alkaline medium, or by condensation of a difunctional phenol dialcohol. The alkyl substituent moiety of the alkyl-substituted phenol typically has 1 to 10 carbon atoms. Dimethylolphenol or phenolic resin substituted with an alkyl group having 1 to 10 carbon atoms at the p-position is preferred.

[0099] Among the above phenolic compounds, alkylphenol formaldehyde resin, methylol alkylphenol resin, brominated alkylphenol resin, etc. are preferred. From an environmental standpoint, non-brominated ones are preferred, but those in which the terminal hydroxyl groups are brominated may also be used. In particular, alkylphenol formaldehyde resin is preferred.

[0100] The amount of the component (E) may be 0.01 to 20 parts by mass, 0.1 to 10 parts by mass, or 0.5 to 5 parts by mass, relative to 100 parts by mass of the component (A). The amount is preferably equal to or more than the lower limit, since the crosslinking reaction proceeds well, while the amount is preferably equal to or less than the upper limit, since the crosslinking does not proceed too much and good moldability is maintained.

[0101] [Crosslinking agent (component (F))] As the crosslinking auxiliary (component (F)), various compounds that are understood by those skilled in the art to function as a crosslinking auxiliary or crosslinking promoter can be used.

[0102] Examples of the component (F) include polyfunctional methacrylate compounds such as triallyl cyanurate, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, polyethylene glycol dimethacrylate having 9 to 14 repeating units of ethylene glycol, trimethylolpropane trimethacrylate, allyl methacrylate, 2-methyl-1,8-octanediol dimethacrylate, and 1,9-nonanediol dimethacrylate; polyfunctional acrylate compounds such as polyethylene glycol diacrylate, 1,6-hexanediol diacrylate, neopentyl glycol diacrylate, and propylene glycol diacrylate; and polyfunctional vinyl compounds such as vinyl butyrate or vinyl stearate. As the component (F), one or more of these can be used.

[0103] Among the above-mentioned components (F), polyfunctional acrylate compounds and polyfunctional methacrylate compounds are preferred, and triallyl cyanurate, triethylene glycol dimethacrylate, and tetraethylene glycol dimethacrylate are particularly preferred. These compounds are easy to handle, have an organic peroxide solubilizing effect, and act as a dispersing aid for the organic peroxide, so that when used in combination with the organic peroxide, crosslinking can be made more uniform and effective.

[0104] The amount of the component (F) may be 0.01 to 50 parts by mass, 0.5 to 30 parts by mass, or 1 to 20 parts by mass, relative to 100 parts by mass of the component (A). The amount is preferably equal to or more than the lower limit, since the crosslinking reaction proceeds well, while the amount is preferably equal to or less than the upper limit, since the crosslinking does not proceed too much and the dispersion of the crosslinked product in the friction body is well maintained.

[0105] [Colorant (Component (G))] As the colorant (component (G)), various compounds that are understood by those skilled in the art to function as a colorant in the art can be used. As component (G), inorganic pigments, organic pigments, etc. are preferred.

[0106] In the above-described embodiment, the refill contains thermochromic ink, but any refill may be used as long as the erasing member can erase handwritten marks, and the erasing member may be an erasing member corresponding to the refill. In other words, the erasing member may be an eraser or sand eraser that adsorbs or scrapes off written lines or characters by rubbing. [Explanation of symbols]

[0107] 1 writing implements 2 Writing instrument body 3 Cap 10 Cap body 12 First fixed end 13 End face 14 Flange section 15 Connection 16 Vertical ribs 20 First erasing member 23 Locking protrusion

Claims

1. A writing instrument body; Cap and an erasing member disposed at a fixed end protruding from at least one of a rear end face of the writing instrument body and a front end face of the cap, At least one longitudinal rib is formed on the fixed end of at least one of the writing implement body and the cap, the longitudinal rib extending in an axial direction so as to be capable of being engaged to prevent rotation of the erasing member; A writing implement characterized in that a locking recess is formed on a side surface of the vertical rib.

2. A writing instrument body; Cap and an erasing member disposed at a fixed end protruding from at least one of a rear end face of the writing instrument body and a front end face of the cap, At least one longitudinal rib is formed on the fixed end of at least one of the writing implement body and the cap, the longitudinal rib extending in an axial direction so as to be capable of being engaged to prevent rotation of the erasing member; A writing implement characterized in that the cross-sectional shape of the vertical rib is a sector shape or an inverted triangle shape.

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