JP2021100804A - Friction body composition, friction body and writing instrument - Google Patents

Abstract

SOLUTION: There is provided a friction body resin composition (X) in which the mass ratio [(A)/(B)] of a 4-methyl-1-pentene/α-olefin copolymer (A) to a thermoplastic elastomer (B) is 10/90 to 67/33. Requirement (a); a melting point (Tm) of the copolymer (A) is not observed in the calorimeter measurement by a differential scanning calorimeter (DSC). Requirement (b); the copolymer (A) includes a structural unit (i) derived from 4-methyl-1-pentene and a structural unit (ii) derived from an α-olefin, and includes 60 to 78 mol% of the structural unit (i) and 22 to 40 mol% of the structural unit (ii) with the total of the structural unit (i) and the structural unit (ii) 100 mol%.EFFECT: Even when it is a handwriting with a novel metallic-like composition ink in which a metallic luster pigment is added to graphite, non-color-changing ink, or heat-discoloring ink, graphite can be erased, the heat-discoloring material can be decolorized or discolored, and the metallic luster pigment can be peeled off at the same time by rubbing the handwriting.SELECTED DRAWING: None

Description

The present invention relates to a composition for a friction body containing a 4-methyl-1-pentene / α-olefin polymer, a friction body, and a writing tool provided with the friction body. More specifically, the present invention relates to a composition for a friction body and a friction body for thermally discoloring a handwriting or a printed image made of graphite or a heat-discolorable ink by friction, and a writing tool provided with the friction body.

As a means for discoloring the heat-discolored portion formed on the paper surface by writing or printing, a friction body that discolors by frictional heat due to manual friction using an elastic material such as an eraser made of vinyl chloride (PVC) or rubber is used. .. Further, in recent years, a thermochromic writing tool capable of decoloring or discoloring by heating the formed handwriting by incorporating a thermochromic ink has become widespread. In the writing instrument, a friction body made of an elastic body is used in order to quickly and easily change the heat of the handwriting formed on the paper surface, and the writing instrument is integrally formed with the rear end of the barrel, the mouthpiece, the cap, and the like of the writing instrument. In addition, it is put to practical use by being provided separately.

On the other hand, since the friction body currently on the market is an elastic body, the brush strokes made by the current heat-decoloring ink, which uses only a heat-discoloring material as a coloring component, are rubbed by frictional heat. It can be chemically decolorized.

Patent Document 1 describes a writing tool that uses a resin material having a specific hardness or higher as a friction body, and when the friction body is applied as a friction portion formed on a supporting base material of the friction tool, it is formed by two-color molding. It is described that it is fixed to the supporting base material. However, in this writing tool, since the combination of the supporting base material and the friction body is limited, the degree of freedom of each material is low. In addition, a complicated mold is required to form the friction body, the wall thickness of the friction body is increased in order to obtain moldability, and since the friction body is an elastic body, the brush stroke is erased. Had to exert considerable force.

Patent Documents 2 and 3 disclose writing tools using an elastic body such as a styrene-based elastomer for the friction body, but these friction bodies have sufficient thermal decolorization property particularly for metallic handwriting. There was no need for improvement. Further, in Patent Document 4, a friction body, a writing instrument, and a writing set in which the heat-decoloring ink contains a metallic glossy pigment and exerts a heat-decoloring effect on the handwriting for the purpose of producing a metallic-like handwriting. However, further improvements were needed in terms of handwriting erasure and thermal decolorization.

JP-A-2007-223302 JP-A-2009-143207 Japanese Unexamined Patent Publication No. 2011-156832 International Publication No. 2018/116767

The present invention solves the above-mentioned problems in the friction body, and is a brush stroke with a new metallic-like constituent ink in which a metallic glossy pigment is added to graphite, non-color-changing ink, and heat-color-changing ink. Another object of the present invention is to provide a friction body capable of erasing graphite by rubbing a brush stroke, erasing or discoloring a heat-discoloring material, and peeling off a metallic glossy pigment at the same time.

Further, according to the present invention, sufficient handwriting erasability can be ensured with a light force without spoiling the appearance at the time of erasing, and the heat-discoloring material can be decolorized or discolored and the particles can be peeled off at the same time. It is an object of the present invention to provide a friction body and a writing tool having excellent convenience and practicality having both property and physical erasability.

Further, in the present invention, when the friction portion is attached to the support base material, the respective structures and dies are not complicated, and the material is not limited. Therefore, the attachment position is not incurred at high cost. It provides a friction body with a wide selection of designs and writing tools equipped with it.

As a result of diligent studies to solve the above problems, it has been found that the above problems can be solved by using a viscoelastic material that is a combination of an elastic material and a viscous material as a friction body, and the present invention has been reached. The viscoelastic body is made of a material having both properties as a viscous body and properties as an elastic body. Generally, a viscous body deforms in response to an external force and does not return to its original shape even when the external force is lost. On the other hand, an elastic body deforms in response to an external force, but returns to its original shape when the external force disappears. Whether a material is a viscoelastic body or a viscoelastic body or a material close to an elastic body can be determined by, for example, looking at the relaxation time of stress relaxation (time change of stress) when a certain strain is applied to the material. If the relaxation time is sufficiently short with respect to the observation time scale, it can be said to be a viscoelastic body, if it is long, it can be said to be an elastic body, and if it is on the same scale, it can be called a viscoelastic body.

That is, the gist of the present invention is as follows.
[1] The 4-methyl-1-pentene / α-olefin copolymer (A) and the thermoplastic elastomer (B) that satisfy the following requirements (a) to (b) are contained, and the 4-methyl-1-pentene / α-olefin copolymer (B) is contained. A resin composition for a friction body in which the mass ratio [(A) / (B)] of the penten-α-olefin copolymer (A) to the thermoplastic elastomer (B) is 10/90 to 67/33. X).
Requirement (a) ; The melting point (Tm) of the copolymer (A) is not observed in the calorimeter measurement by the differential scanning calorimeter (DSC).
Requirement (b) ; The copolymer (A) is derived from the structural unit (i) derived from 4-methyl-1-pentene and the α-olefin (excluding 4-methyl-1-pentene). Including the structural unit (ii), the total of the structural unit (i) and the structural unit (ii) is 100 mol%, and the structural unit (i) 60 to 78 mol% and the structural unit (ii) 22. Includes ~ 40 mol%.
[2] The resin composition (X) for a friction body according to [1], which further contains a crystalline polyolefin (C).
[3] The resin composition (X) for a friction body according to [1] or [2], which satisfies the following requirements (x) to (y).
Requirement (x) ; 4-methyl-1-pentene / α-olefin copolymer 15 seconds after the start of needle contact, measured in a state where three 2 mm thick sheets are stacked in accordance with JIS K6253. The shore A hardness of the coalesced (A) is 60 or more and 90 or less.
Requirement (y) ; Shore A hardness of the 4-methyl-1-pentene / α-olefin copolymer (A) measured in a state where three sheets having a thickness of 2 mm are stacked in accordance with JIS K6253. The difference ΔHS between the shore A hardness value immediately after the needle contact and the shore A hardness value 15 seconds after the needle contact, which is represented by the following formula, is 10 or more and 35 or less.
ΔHS = (Shore A hardness value immediately after needle contact-Shore A hardness value 15 seconds after needle contact)
[4] The resin composition for a friction body (X) according to any one of [1] to [3], wherein the 4-methyl-1-pentene / α-olefin copolymer (A) satisfies the following requirement (c). ).
Requirement (c ); The tan δ peak temperature obtained by performing dynamic viscoelasticity measurement at a frequency of 10 rad / s (1.6 Hz) in a temperature range of -40 to 150 ° C. is 10 ° C. or higher and 38 ° C. or lower.
[5] A friction body comprising the composition for a friction body according to any one of [1] to [4].
[6] The friction body according to [5], wherein the friction body is manufactured by injection molding.
[7] A writing tool having a writing tool main body and the friction body according to [5] or [6] attached to the writing tool main body, and having a heat-discoloring ink built in the writing tool main body.
[8] The writing instrument according to [7], wherein the thermochromic ink contains a thermochromic microcapsule pigment having an average particle size of 0.05 μm or more and 5.0 μm or less.
[9] The writing instrument according to [7], wherein the thermochromic ink contains a metallic luster pigment having an average particle size of 0.1 μm or more and 50 μm or less.

The friction body of the present invention erases graphite by rubbing the brush strokes, even if the brush strokes are made of graphite, a non-color-changing ink, or a newly composed metallic ink in which a metallic glossy pigment is added to the heat-color-changing ink. It is also possible to simultaneously perform decolorization and discoloration of a heat-discoloring material and peeling of a metallic glossy pigment.

Further, the friction body of the present invention can secure sufficient handwriting erasability with a light force without spoiling the appearance at the time of erasing, and can simultaneously perform decolorization and discoloration of the heat-discoloring material and peeling of particles. That is, the friction body and the writing tool of the present invention are excellent in convenience and practicality having both chemical erasability and physical erasability.

Further, the friction body of the present invention does not complicate each structure or mold when attaching the friction portion to the support base material, and further does not limit the material, so that high cost is not required. A wide range of mounting positions and designs can be selected.

Hereinafter, the resin composition (X) for a friction body, the friction body, and the writing tool of the present invention will be described. The resin composition (X) for a friction material of the present invention comprises a 4-methyl-1-pentene / α-olefin copolymer (A) (hereinafter, also referred to as a copolymer (A)) and a thermoplastic elastomer (B). including. As a preferred embodiment of the resin composition for a friction body (X), a friction body containing a 4-methyl-1-pentene / α-olefin copolymer (A), a thermoplastic elastomer (B), and a crystalline polyolefin (C). Resin composition for use (X1) can be mentioned.

In the friction material resin composition (X), the mass ratio of the 4-methyl-1-pentene / α-olefin copolymer (A) to the thermoplastic elastomer (B) [(A) / (B)). ] Is 10/90 to 67/33. Specifically, assuming that the total amount of the 4-methyl-1-pentene / α-olefin copolymer (A) and the thermoplastic elastomer (B) is 100 parts by mass, the above is made from the viewpoint of flexibility and stress relaxation. The upper limit of the content of the copolymer (A) in the composition is usually 67 parts by mass, preferably 50 parts by mass, more preferably 45 parts by mass, particularly preferably 40 parts by mass, and the lower limit is usually 10 parts by mass. It is by mass, preferably 25 parts by mass, more preferably 30 parts by mass, and particularly preferably 35 parts by mass.

The lower limit of the content of the thermoplastic elastomer (B) is usually 33 parts by mass, preferably 50 parts by mass, more preferably 55 parts by mass, particularly preferably 60 parts by mass, and the upper limit is usually 90 parts by mass, preferably 90 parts by mass. Is 75 parts by mass, more preferably 70 parts by mass, and particularly preferably 65 parts by mass.

In the resin composition for a friction material (X1), the total amount of the 4-methyl-1-pentene / α-olefin copolymer (A), the thermoplastic elastomer (B) and the crystalline polyolefin (C) is 100 parts by mass. Then, from the viewpoint of flexibility and stress relaxation, the upper limit of the content of the copolymer (A) in the composition is usually 50 parts by mass, preferably 48 parts by mass, more preferably 45 parts by mass, particularly preferably. It is 40 parts by mass, and the lower limit is usually 20 parts by mass, preferably 25 parts by mass, and more preferably 30 parts by mass.

The lower limit of the content of the thermoplastic elastomer (B) is usually 20 parts by mass, preferably 25 parts by mass, more preferably 30 parts by mass, and the upper limit is usually 80 parts by mass, preferably 75 parts by mass, more preferably 75 parts by mass. Is 70 parts by mass, particularly preferably 65 parts by mass.

The lower limit of the content of the crystalline polyolefin (C) is usually 5 parts by mass, preferably 7 parts by mass, more preferably 10 parts by mass, and the upper limit is 40 parts by mass, preferably 35 parts by mass, further. It is preferably 30 parts by mass.

The friction body composition (X) of the present invention preferably satisfies the following requirements (x) and (y).
Requirement (x) ;
According to JIS K6253, the shore A hardness of the copolymer (A) 15 seconds after the start of needle contact, which is measured in a state where three sheets with a thickness of 2 mm are stacked, is 60 or more and 95 or less. It is preferably 65 or more and 95 or less, and more preferably 70 or more and 90 or less.

A shore A hardness value immediately after the start of needle push contact is more preferable because the efficiency of generating frictional heat is particularly high and the handwriting can be easily thermally discolored. The shore A hardness value may be converted into a value obtained by measuring the shore D hardness.

Requirement (y) ;
In accordance with JIS K6253, the shore A hardness of the copolymer (A) measured in a state where three sheets with a thickness of 2 mm are stacked is based on the value of the shore A hardness immediately after the needle contact and the needle contact. The difference ΔHS from the value of Shore A hardness after 15 seconds is 10 or more and 35 or less, preferably 10 or more and 30 or less, and more preferably 10 or more and 25 or less.

The above ΔHS is a value obtained according to the following formula.
ΔHS = (Shore A hardness value immediately after needle contact-Shore A hardness value 15 seconds after needle contact)
When ΔHS is not more than the upper limit value, frictional heat can be generated more efficiently when the handwriting on the paper surface is rubbed with the friction body obtained from the friction body composition (X). Further, when it is at least the above lower limit value, the granules (pigment) contained in the handwriting can be more easily adsorbed and peeled off. ΔHS can be arbitrarily changed depending on the comonomer type and comonomer composition of the 4-methyl-1-pentene / α-olefin copolymer (A), and can also be arbitrarily adjusted by mixing a plurality of types.

The friction body composition (X) of the present invention preferably further satisfies the following requirement (z).
Requirement (z) ;
The tan δ peak temperature of the copolymer (A) obtained by performing dynamic viscoelasticity measurement at a frequency of 10 rad / s (1.6 Hz) in the temperature range of -40 to 150 ° C. is 10 ° C. or higher and 30 ° C. or lower. It is preferably 10 ° C. or higher and 28 ° C. or lower, more preferably 10 ° C. or higher and 25 ° C. or lower, and further preferably 14 ° C. or higher and 25 ° C. or lower. By setting the tan δ peak temperature of the friction body composition (X) to the above temperature range, the viscous characteristics at room temperature are increased, and as a result, the erasability of graphite and the heat-discoloring ink of the friction body is improved.

Hereinafter, the 4-methyl-1-pentene / α-olefin copolymer (A), the thermoplastic elastomer (B), and the crystalline polyolefin (C) constituting the resin composition (X) for a friction material will be described.

<4-Methyl-1-pentene / α-olefin copolymer (A)>
The 4-methyl-1-pentene / α-olefin copolymer (A) satisfies the following requirements (a) and (b), preferably further (c), and further (d). More preferred.

Requirement (a) ;
The melting point (Tm) of the 4-methyl-1-pentene / α-olefin copolymer (A) is not observed in the calorimeter measurement by the differential scanning calorimeter (DSC). By satisfying such requirements, it is possible to improve the tensile physical properties of the friction body of the present invention and adjust the surface hardness.

Requirement (b) ;
The 4-methyl-1-pentene / α-olefin copolymer (A) contains the structural unit (i) derived from 4-methyl-1-pentene and the α-olefin (however, 4-methyl-1-pentene). The total of the constituent unit (ii) derived from) is 100 mol%, and the constituent unit (i) is 60 to 78 mol% and the constituent unit (ii) is 22 to 40 mol%.

That is, the lower limit of the ratio of the constituent unit (i) is 60 mol%, preferably 65 mol%, and more preferably 68 mol%. On the other hand, the upper limit of the ratio of the constituent unit (i) is 78 mol%, preferably 76 mol%, and more preferably 75 mol%. As described above, in the present invention, the ratio of the structural unit (i) in the 4-methyl-1-pentene / α-olefin copolymer (A) is equal to or higher than the lower limit value, so that the peak value of tan δ is around room temperature. Since it has a temperature, it is excellent in shape followability and stress relaxation property, and has appropriate flexibility when the ratio of the structural unit (i) is not more than the upper limit value.

The upper limit of the ratio of the constituent unit (ii) is 40 mol%, preferably 35 mol%, and more preferably 32 mol%. On the other hand, the lower limit of the ratio of the constituent unit (ii) is 22 mol%, preferably 24 mol%, and more preferably 25 mol%.

Examples of the α-olefin that derives the structural unit (ii) include ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 1-decene, 1-undecene, 1-dodecene, 1-. Linear α-olefins having 2 to 20 carbon atoms, preferably 2 to 15 carbon atoms, more preferably 2 to 10 carbon atoms, such as tetradecene, 1-hexadecene, 1-octadecene, and 1-eicosene, 3. -Methyl-1-butene, 3-methyl-1-pentene, 3-ethyl-1-pentene, 4,4-dimethyl-1-pentene, 4-methyl-1-hexene, 4,4-dimethyl-1-hexene , 4-Ethyl-1-hexene, 3-ethyl-1-hexene and the like, and examples thereof include branched α-olefins having 5 to 20 carbon atoms, preferably 5 to 15 carbon atoms. Among these, ethylene, propylene, 1-butene, 1-pentene, 1-hexene and 1-octene are preferable, and ethylene and propylene are particularly preferable.

Here, in one aspect of the present invention, the 4-methyl-1-pentene / α-olefin copolymer (A) usually consists of only the structural unit (i) and the structural unit (ii). However, the 4-methyl-1-pentene / α-olefin copolymer (A) has a structural unit (i) and a constitution as long as it is in a small amount (for example, 10 mol% or less) that does not impair the object of the present invention. In addition to the unit (ii), the structural unit (iii) further comprises a structural unit derived from other monomers that are neither 4-methyl-1-pentene nor the α-olefin leading to the structural unit (ii). May be good. Preferred specific examples of such other monomers include 5-vinyl-2-norbornene and 5-ethylidene when the copolymer (A) is a 4-methyl-1-pentene-propylene copolymer. -2-Norbornene and the like.

Requirement (c) ;
The tan δ peak temperature of the copolymer (A) obtained by performing dynamic viscoelasticity measurement at a frequency of 10 rad / s (1.6 Hz) in the temperature range of -40 to 150 ° C. is 10 ° C. or higher and 38 ° C. or lower. It is preferably 15 ° C. or higher and 38 ° C. or lower, more preferably 20 ° C. or higher and 35 ° C. or lower, and further preferably 25 ° C. or higher and 35 ° C. or lower. By setting the tanδ peak temperature of the 4-methyl-1-pentene / α-olefin copolymer (A) to the above temperature range, the value of tanδ at room temperature can be further increased. Further, by having the tan δ peak value at room temperature, the erasability of graphite and the heat-discoloring ink of the friction material obtained from the copolymer (A) is improved.

Requirement (d);
The tan δ peak value obtained by performing dynamic viscoelasticity measurement at a frequency of 10 rad / s (1.6 Hz) in a temperature range of -40 to 150 ° C. is preferably 1.7 or more and 5.0 or less. It is more preferably 1.7 or more and 4.0 or less, and further preferably 2.0 or more and 4.0 or less.

When the tan δ peak value is within the above range, the viscous property at room temperature is increased, and as a result, the erasability of the graphite of the friction body and the heat-discoloring ink is improved.
A particularly preferable form of the 4-methyl-1-pentene / α-olefin copolymer (A) is, in addition to the above requirements (a), (b), (c) and (d), further the following requirement (e). 1 or more, preferably 2 or more, more preferably 3 or more, particularly preferably all selected from (h).

Requirement (e) ;
Density (measured by ASTM D1505) is, 830~870kg / m ^3, preferably not 830~865kg / m ^3, more preferably a 830~855kg / m ^3. The details of the measurement conditions and the like are as described in the column of Examples described later.

The density can be appropriately changed depending on the comonomer composition ratio of the 4-methyl-1-pentene / α-olefin copolymer (A), and the copolymer (A) having a density within the above range is a lightweight friction material. Can be molded.

Requirement (f) ;
The ratio (molecular weight distribution; Mw / Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) measured by gel permeation chromatography (GPC) is 1.0 to 3.5, preferably 1. It is in the range of 2 to 3.0, more preferably 1.5 to 2.8. The details of the measurement conditions and the like are as described in the column of Examples described later. If the Mw / Mn is larger than 3.5, the moldability may be deteriorated due to concern about the influence of the low molecular weight and low stereoregular polymer derived from the composition distribution.

Here, in the present invention, if a catalyst described later is used, 4-methyl-1-pentene α- satisfying the above requirement (f) within the range of the ultimate viscosity [η] shown in the above requirement (g). The olefin copolymer (A) can be obtained. The values of Mw / Mn and the following Mw are values measured by the method adopted in the examples described later.

The weight average molecular weight (Mw) of the 4-methyl-1-pentene / α-olefin copolymer (A) measured by gel permeation chromatography (GPC) is preferably 500 to 10 in terms of polystyrene. , Million, more preferably 1,000 to 5,000,000, still more preferably 1,000 to 2,500,000.

Requirements (g) ;
The ultimate viscosity [η] measured at 135 ° C. in decalin is in the range of 0.1 to 5.0 dL / g, preferably 0.5 to 4.0 dL / g, more preferably 0.5 to 3.5 dL / g. Is.

As will be described later, when hydrogen is used in combination during the polymerization in the production of the copolymer, the molecular weight can be controlled, and the ultimate viscosity [η] can be adjusted by freely obtaining from a low molecular weight substance to a high molecular weight substance. If the ultimate viscosity [η] is smaller than 0.1 dL / g or larger than 5.0 dL / g, the injection molding processability may be impaired.

<Method for producing 4-methyl-1-pentene / α-olefin copolymer (A)>
The method for producing the 4-methyl-1-pentene / α-olefin copolymer (A) is not particularly limited, and the copolymer (A) is, for example, 4-methyl-1-pentene as described above. It can be obtained by polymerizing the "α-olefin that derives the structural unit (ii)" in the presence of an appropriate polymerization catalyst.

Here, as the polymerization catalyst that can be used in the present invention, conventionally known catalysts such as magnesium-supported titanium catalysts, International Publication No. 01/53369 Pamphlet, International Publication No. 01/27124, Japanese Patent Application Laid-Open No. 3-193996 The metallocene catalysts described in International Publication No. 2011/055803, International Publication No. 2014/050817, etc. are preferably used in Japanese Patent Application Laid-Open No. 02-41303.

<Thermoplastic elastomer (B)>
The thermoplastic elastomer referred to in the present invention is a polymer that exhibits thermoplastic properties when heated to a temperature higher than the melting point, while exhibiting rubber elastic properties at room temperature. Specific examples of the thermoplastic elastomer (B) include the following polyolefin-based elastomers (B-1) and polystyrene-based elastomers (B-2).

<< Olefin-based elastomer (B-1) >>
The first aspect of the olefin-based elastomer (B-1) is from one selected from the group consisting of polyethylene and polypropylene, polybutadiene, hydrogenated polybutadiene, polyisobutylene, hydrogenated polyisobutylene, polyisobutylene, and α-olefin. Examples thereof include a copolymer with one selected from the above group. The form of copolymerization may be either block copolymerization or graft copolymerization, but only in the case of one selected from the group consisting of polyethylene and polypropylene and a copolymer composed of α-olefin, the form of copolymerization is a random copolymer. It may be a polymerization. The α-olefin is an olefin having a double bond at one end of the molecular chain, and 1-butene, 1-octene and the like are preferably used.

For example, a block copolymer of a polyolefin block that forms a highly crystalline polymer such as polypropylene that serves as a hard portion and a monomer copolymer that exhibits amorphousness that serves as a soft portion can be mentioned, and specific examples thereof include olefins. Crystalline) -ethylene-butylene-olefin block copolymer, polypropylene-polyolefin (amorphous) -polypropylene block copolymer and the like can be exemplified. As a specific example, from JSR Co., Ltd. Product name: DYNARON (registered trademark), from Mitsui Chemicals Co., Ltd. Product name: Toughmer (registered trademark), Notio (registered trademark), from Dow Chemical Co., Ltd. Product name: ENGAGE (Registered trademark), VERSIFY (registered trademark), and those commercially available under the trade name: Vistamaxx (registered trademark) from Exxon Mobile Chemical Co., Ltd. can be mentioned.

As the second aspect of the polyolefin-based elastomer referred to in the present invention, one selected from the group consisting of polyethylene and polypropylene, an ethylene / propylene copolymer, an ethylene / propylene / diene copolymer, and an ethylene / butene copolymer, Examples thereof include a blend with one selected from the group consisting of hydrogenated styrene-butadiene. At this time, the ethylene / propylene copolymer, the ethylene / propylene / diene copolymer, and the ethylene / butene copolymer may be partially or completely crosslinked.

Specific examples include product name from Mitsui Kagaku Co., Ltd.: Mirastomer (registered trademark), product name from Sumitomo Chemical Co., Ltd.: Esporex (registered trademark), product name from Mitsubishi Chemical Co., Ltd.: Thermolan (registered trademark), Zelas ( Examples include those commercially available from Exxon Mobile Chemical Co., Ltd. under the trade name: Santoprene (registered trademark).

The olefin-based elastomer according to the present invention is at least one selected from the group consisting of an acid anhydride group, a carboxyl group, an amino group, an imino group, an alkoxysilyl group, a silanol group, a silyl ether group, a hydroxyl group and an epoxy group. It may be modified with the functional group of.

≪Styrene-based elastomer (B-2) ≫
The styrene-based elastomer (B-2) includes a block copolymer (SBS) of a polystyrene block as a hard portion (crystal portion) and a diene-based monomer block as a soft portion, and a hydrogenated styrene / butadiene / styrene block. Polymer (HSBR), styrene / ethylene / propylene / styrene block copolymer (SEPS), styrene / ethylene / butene / styrene block copolymer (SEBS), styrene / isoprene / styrene block copolymer (SIS), styrene -Isobutylene-styrene copolymer (SIBS), styrene-isobutylene copolymer (SIB) and the like can be exemplified. The styrene-based elastomer may be used alone or in combination of two or more.

Specific examples of the hydrogenated styrene / butadiene / styrene block copolymer include those commercially available from JSR Corporation under the trade name: Dynalon (registered trademark). The styrene / ethylene / propylene / styrene block copolymer is obtained by hydrogenating styrene / isoprene / styrene block copolymer (SIS). Specific examples of SIS include JSR Corporation as product name: JSR SIS (registered trademark), Kuraray Co., Ltd. as product name: Hybler (registered trademark), or Shell Corporation as product name: Clayton D (registered trademark). Examples include those on the market.

Specific examples of SEPS include those commercially available from Kuraray Co., Ltd. under the trade name: Septon (registered trademark) or Shell Co., Ltd. under the trade name: Clayton (registered trademark).

Specific examples of SEBS include those commercially available from Asahi Kasei Corporation under the trade name: Tough Tech (registered trademark) or Shell Co., Ltd. under the trade name: Clayton (registered trademark).

Specific examples of SIB and SIBS include those commercially available from Kaneka Corporation under the trade name: Sibster (registered trademark).

<Crystalline polyolefin (C)>
The friction body composition (X) of the present invention may contain crystalline polyolefin (C). The crystalline polyolefin (C) is a conventionally known low-density, medium-density, high-density polyethylene, high-pressure low-density polyethylene, isotactic polypropylene, syndiotactic polypropylene, poly 1-butene, poly 4-methyl-1. -Penten, poly3-methyl-1-butene, ethylene / α-olefin copolymer, propylene / α-olefin copolymer, 1-butene / α-olefin copolymer, cyclic olefin copolymer, chlorinated polyolefin And so on.
When the blending amount of the crystalline polyolefin (C) is within the above range, it is possible to impart appropriate hardness to the obtained friction body and contribute to erasability.

<Additives>
The resin composition (X) for a friction body of the present invention may be modified in various ways by adding a secondary additive. Specific examples of secondary additives include plasticizers, UV absorbers, infrared absorbers, optical brighteners, mold release agents, antibacterial agents, nucleating agents, heat stabilizers, antioxidants, slip agents, and antistatic agents. Agents, colorants, modifiers, matting agents, defoaming agents, preservatives, gelling agents, latexes, fillers, inks, colorants, dyes, pigments, fragrances and the like, but not limited to these. These secondary additives may be used alone or in combination of two or more.

Examples of the plasticizer include aromatic carboxylic acid esters (dibutyl phthalate, etc.), aliphatic carboxylic acid esters (methylacetyllithinolate, etc.), aliphatic dialbon acid esters (adipic acid-propylene glycol-based polyester, etc.), and aliphatic tricarboxylic acids. Examples thereof include esters (triethyl citrate, etc.), phosphoric acid triesters (triphenyl phosphate, etc.), epoxy fatty acid esters (epoxybutyl stearate, etc.), petroleum resins, and the like.

Release agents include lower (C1-4) alcohol esters of higher fatty acids (butyl stearate, etc.), polyhydric alcohol esters of fatty acids (C4-30) (hardened castor oil, etc.), glycol esters of fatty acids, liquid paraffins, etc. Can be mentioned.

Examples of the antioxidant include phenol-based (2,6-di-t-butyl-4-methylphenol, etc.) and polycyclic phenol-based (2,2'-methylenebis (4-methyl-6-t-butylphenol), etc.). , Phosphorus (tetrakis (2,4-di-t-butylphenyl) -4,4-biphenylenediphosphonate, etc.), amine-based (N, N-diisopropyl-p-phenylenediamine, etc.) antioxidants Can be mentioned.

Examples of the ultraviolet absorber include benzotriazole type, benzophenone type, salicylic acid type, acrylate type and the like.
Examples of the antibacterial agent include a quaternary ammonium salt, a pyridine compound, an organic acid, an organic acid ester, a halogenated phenol, and an organic iodine.

Examples of the surfactant include nonionic, anionic, cationic or amphoteric surfactants. Examples of the nonionic surfactant include polyethylene glycol type nonionic surfactants such as higher alcohol ethylene oxide adduct, fatty acid ethylene oxide adduct, higher alkylamine ethylene oxide adduct, polypropylene glycol ethylene oxide adduct, polyethylene oxide, and fatty acid ester of glycerin. , Pentaerythritol fatty acid ester, sorbit or sorbitan fatty acid ester, polyhydric alcohol alkyl ether, polyhydric alcohol type nonionic surfactant such as alkanolamine aliphatic amide, etc., and examples thereof include anionic surfactants. For example, sulfate ester salts such as alkali metal salts of higher fatty acids, sulfonates such as alkylbenzene sulfonates, alkyl sulfonates, paraffin sulfonates, phosphate ester salts such as higher alcohol phosphates, etc. Examples of the cationic surfactant include quaternary ammonium salts such as alkyltrimethylammonium salts. Examples of the amphoteric tenside include an amino acid type double-sided surfactant such as a higher alkylaminopropionate, a higher alkyldimethylbetaine, and a betaine type amphoteric tenside such as hydroxyethyl betaine at the time of higher alkyl.

Examples of the antistatic agent include the above-mentioned surfactant, fatty acid ester, and polymer type antistatic agent. Examples of fatty acid esters include esters of stearic acid and oleic acid, and examples of high molecular weight antistatic agents include polyether ester amides.

Examples of the pigment include an inorganic content (titanium oxide, iron oxide, chromium oxide, cadmium sulfide, etc.) and an organic pigment (azolake-based, thioindigo-based, phthalocyanine-based, anthraquinone-based). Examples of the dye include azo type, anthraquinone type, triphenylmethane type and the like. The amount of these pigments and dyes added is not particularly limited, but is usually 5 parts by mass or less, preferably 0.1 to 3 parts by mass, in total with respect to 100 parts by mass of the copolymer (A).

As a slip agent, wax (carnauba wax, etc.), higher fatty acid (stearic acid, etc.), training fatty acid salt (calcium stearate, etc.), higher alcohol (stearyl alcohol, etc.), higher fatty acid amide (stearic acid amide, erucic acid amide, etc.) And so on.

The amount of the above-mentioned various additives added is not particularly limited as long as the object of the present invention is not impaired, and is not particularly limited, but is 100 mass by mass of the 4-methyl-1-pentene / α-olefin copolymer (A). It is preferable that the amount is 0.01 to 30 parts by mass with respect to each part.

<Manufacturing method of resin composition (X) for friction body>
The method for producing the resin composition (X) for a friction body of the present invention is not particularly limited, and for example, a conventionally known production method can be used. It is also possible to produce a composition by uniformly mixing a solution in which each component is dissolved in a solvent and then removing the solvent, but practical production does not require steps such as dissolving the raw material in the solvent and removing the solvent. It is preferable to adopt a melt-kneading method for producing a composition by melt-kneading each component. The melt-kneading method is not particularly limited, and melt-mixing is performed at, for example, 180 to 250 ° C. using a commonly used known mixer such as a kneader, a roll mill, a Banbury mixer, or a single-screw or twin-screw extruder. After smelting, a method of granulating or crushing can be adopted. Among them, the use of a twin-screw extruder is preferable from the viewpoint of mixing and productivity. By this method, high quality resin composition pellets in which each component and additive are uniformly dispersed and mixed can be obtained.

<Friction body>
The friction body of the present invention is characterized by containing the resin composition (X) for a friction body. The friction body of the present invention is not particularly limited in its production method, but can be suitably produced, for example, from the resin composition for friction body (X) by injection molding.

Similar to the conventional friction body, the friction body is used to discolor and discolor the handwriting by frictional heat by rubbing the handwriting with the heat-discoloring ink. At that time, the friction body of the present invention generates frictional heat by acting as an elastic body, and further acts as a viscous body to obtain adsorption and peeling performance. It can also have a target erasability.

By using the friction body, even if the handwriting is made with a newly composed ink, there is no residual color generated in the handwriting and its surroundings at the time of erasing and the appearance is not spoiled, and it is convenient to ensure sufficient handwriting erasability. A writing instrument and a writing set having excellent practicality can be obtained. At that time, since the friction body of the present invention can be formed by one member like the friction body provided in the conventional writing tool main body, the writing tool exterior can be used as it is, so that it is highly versatile. Further, since the friction body can exhibit an action similar to that of a conventional eraser, it is possible to exfoliate graphite from the paper surface, for example. Therefore, the friction body of the present invention can form a new erasing tool that enables the heat discoloration of the heat-discoloring ink and the removal of handwriting by a pencil lead, a mechanical pencil, or the like with one friction body.

<Writing tool with friction body composition>
The friction body composition and the friction body are configured in a form capable of scraping handwriting and are put into practical use. At that time, the friction body may be configured independently, or may be configured in a state where it can be gripped, such as by arranging the friction portion on another member such as a hard resin in a form in which the friction portion can contact the handwriting (paper surface). In addition, it can be configured as a heat-changing writing tool form provided in a writing tool containing a heat-changing ink, or a writing tool form containing a separately heat-changing ink. For example, the writing tool of the present invention includes a writing tool main body and the friction body attached to the writing tool main body, and a thermochromic ink is incorporated in the writing tool main body.

Examples of the form of the writing instrument include a fountain pen, a marking pen, a ballpoint pen, a pay-out type solid writing instrument, and the like. It may have a retractable form that has a retractable mechanism and can accommodate the pen tip in the barrel. In the case of the haunting type, not only a type that accommodates one refill, but also a compound type that accommodates two or more refills and can selectively haunt a desired refill can be used. Further, it may be a double-headed type in which a pen tip having a different form is attached or a pen tip for drawing out inks having different hues is attached.

As the marking pen, for example, a pen tip for a marking pen such as a fiber tip, a felt tip, a plastic tip, or a metal tip is attached to the writing tip, and an ink reservoir composed of a fiber bundle housed inside a barrel is impregnated with ink. A structure that supplies ink to the tip of the writing, and the ink is stored directly inside the barrel, and a predetermined amount of ink is placed at the tip of the writing with a comb groove-shaped ink flow control member and an ink flow control member consisting of a fiber bundle. Examples thereof include a marking pen having a structure for supplying ink and a structure for storing ink directly inside the barrel and supplying a predetermined amount of ink to the writing tip by a valve mechanism.

The ball pen has, for example, an ink accommodating tube in which an ink composition is filled in a barrel, and the ink accommodating tube communicates with a chip having a ball attached to a tip portion, and further, ink backflow occurs on the end face of the ink. A structure in which the preventive body is in close contact, the tip is connected to the tip of the barrel, and the ink composition is directly filled in the barrel, and the ink backflow preventive body is in close contact with the end face of the ink, and the ink is housed inside the barrel. A structure in which an ink reservoir composed of fiber bundles is impregnated with ink to supply ink to the chip, and a predetermined amount of ink is supplied to the chip via a comb groove-shaped ink flow rate adjusting member and an ink flow rate adjusting member composed of fiber bundles. An example is a ball pen or the like having a structure to be used. Further, the ballpoint pen having a structure in which the tip is connected to the tip of the barrel and directly filled with ink may have a structure in which a transfer layer is formed on the exterior filled with ink and then housed in the transparent outer shaft.

As the ink contained in the writing tool, a normal non-color-changing ink can be stored, and a heat-color-changing ink that can be decolorized or discolored by conventional general-purpose heating can be applied.
The heat-discolored portion to be scraped by the friction tool of the present invention includes handwriting formed on a paper surface or the like by the heat-color-changing writing tool, imprints by stamps, and a heat-coloring layer (image form or solid shape) formed by printing or painting. ) Applies.

<Thermal discoloration writing tool>
The thermochromic writing tool provided with the friction body may be in any form, regardless of whether it is a water-based ink or an oil-based ink, as long as it can accommodate the thermochromic ink and form a thermochromic handwriting. Good. The thermochromic ink according to the present invention is a general term for materials that form handwriting, and includes a form such as a pencil lead. Details will be described below.

As the heat-discoloring ink contained in the writing tool, any ink that can be decolorized or discolored by conventional general-purpose heating can be applied. The colorant to be blended in the ink is a reversible heat containing at least three essential components of an electron-donating color-developing organic compound, an electron-accepting compound, and a reaction medium that determines the occurrence temperature of the color reaction of both. Those using a discoloring composition are preferable, and in particular, a microcapsule pigment obtained by encapsulating a reversible thermochromic composition in a microcapsule is effective.

The reversible thermochromic composition is described in Japanese Patent Publication No. 51-44706, Japanese Patent Publication No. 51-44707, Japanese Patent Publication No. 1-2398, and the like with a predetermined temperature (discoloration point) as a boundary. The color changes before and after, the color is decolorized in the temperature range above the high temperature side discoloration point, and the color is developed in the temperature range below the low temperature side discoloration point. The other state is maintained as long as the heat or cold required for the state to develop is applied, but returns to the state exhibited in the normal temperature range when the heat or cold is not applied, and the hysteresis width is An exemplary reversible thermochromic composition having relatively small properties (ΔH of 1 ° C. or higher and 7 ° C. or lower) can be exemplified, and a heat-decoloring type microcapsule pigment containing this in a microcapsule can be applied.

Further, as the reversible thermochromic composition, relatively large ones described in JP-A-4-17154, JP-A-7-179777, JP-A-7-33997, JP-A-8-39936 and the like are relatively large. Those exhibiting hysteresis characteristics (ΔH value of 8 ° C. or higher and 50 ° C. or lower), JP-A-2006-137886, JP-A-2006-188660, JP-A-2008-45062, JP-A-2008-280523, etc. Examples of those exhibiting a large hysteresis characteristic described in 1. A large hysteresis characteristic means that the shape of the curve plotting the change in coloring density due to temperature change causes the temperature to decrease from the higher temperature side than the discoloration temperature range, as opposed to increasing the temperature from the lower temperature side than the discoloration temperature range. It means that the color changes by following a path that differs greatly depending on the case. Such a reversible thermochromic composition has color memorability in a specific temperature range in a color development state in a low temperature range below the complete color development temperature or a decolorization state in a high temperature range above the complete decolorization temperature. A heat-decoloring type microcapsule pigment containing this can also be applied.

Specifically, as the reversible thermochromic composition having color memory, the complete color development temperature can be obtained only in a freezer, a cold region, or the like, that is, −50 ° C. or higher and 0 ° C. or lower, preferably −40. ° C or higher and -5 ° C or lower, more preferably -30 ° C or higher and -10 ° C or lower, and the temperature obtained by frictional heat from the friction body, that is, 50 ° C or higher and 95 ° C or lower, preferably 50 ° C or higher and 90. By specifying the temperature in the range of 60 ° C or higher, more preferably 60 ° C or higher and 80 ° C or lower, and specifying the ΔH value in the range of 40 ° C or higher and 100 ° C or lower, it effectively functions to maintain the color exhibited in the normal state (daily living temperature range). There are things that can be made to do.

In the case of microcapsule pigments, those having an average particle size of, for example, 0.05 μm or more and 5.0 μm or less, preferably 0.1 μm or more and 4.0 μm or less, more preferably 0.5 μm or more and 3.0 μm or less are written. It is suitable in terms of performance and handwriting density. Further, for the purpose of more efficiently exhibiting the decoloring performance using the friction body of the present invention, when the average particle size of the microcapsule pigment is 2.0 μm or more, chemical decolorization by frictional heat is performed. As a result, discoloration (discoloration) using physical erasure by adsorption peeling becomes possible, so that it is highly effective for irreversible erasure and discoloration. For the average particle size, the particle area is determined using the image analysis type particle size distribution measurement software "MacView" manufactured by Mountech, and the projected area circle equivalent diameter (Heywood diameter) is calculated from the area of the particle area. , It is a value measured as an average particle size of particles corresponding to equal volume spheres based on the value.

If the particle size of all or most of the particles exceeds 0.2 μm, it is equivalent to an isovolume sphere by the Coulter method using a particle size distribution measuring device (manufactured by Beckman Coulter, Inc., product name: Multisizer 4e). It is also possible to measure the average particle size as the average particle size of the particles. Further, as a colorant component, a dye, a general pigment, or the like can be used in order to impart a desired hue without thermal discoloration to the handwriting. For example, as the dye, an acid dye, a basic dye, a direct dye or the like can be used. General pigments include inorganic pigments such as carbon black and ultramarine, organic pigments such as copper phthalocyanine blue and benzidine yellow, and dispersed pigment products finely and stably dispersed in a medium using a surfactant or the like in advance. Is used. In addition, metallic luster pigments such as metal powders and pearl pigments, fluorescent pigments, phosphorescent pigments, and special pigments such as titanium dioxide can also be applied. These coloring components may be used in combination with the above-mentioned microcapsule pigment, or may be included in the above-mentioned microcapsule pigment.

In particular, when a metallic luster pigment is added to a heat-discoloring ink, a metallic-like ink can be formed, so that a glossy and highly decorative handwriting is formed at the time of writing, which is more useful. Further, when the above-mentioned heat-discoloring microcapsule pigment was used as a colorant, the brush marks on the blank paper obtained when the heat-discoloring microcapsule pigment became transparent seemed to be completely erased without brilliance. Transparent metallic luster pigments are useful because they are visually visible.

When erasing the handwriting, it is necessary to perform thermal discoloration and peeling removal. Therefore, conventionally, it is necessary to use two types of friction bodies, which are elastic bodies having a large shore hardness, and elastic bodies and erasers having a low shore hardness. It was. However, the friction body of the present invention is particularly convenient because it can be decolorized (discolored) by frictional heat and adsorption peeling by one rubbing using one friction body. In particular, when the average particle size of the metallic luster pigment used is 10 μm or more, a handwriting with high brilliance can be obtained and the adsorption and peeling property becomes high, so that the handwriting decoration and irreversible erasability are highly effective. Demonstrate.

As the transparent metal glossy pigment, a material selected from natural mica, synthetic mica, flat glass piece, flaky aluminum oxide and the like is used as a core material, and the core material is coated with a metal oxide. Pigments can be mentioned.

As a bright pigment having natural mica as a core material, one in which the surface is coated with titanium oxide, one in which the upper layer of the titanium oxide is coated with iron oxide or a non-thermochromic dyeing pigment, or the like is effective. , Merck's product name "Iriogin", Engelhard's product name "Lumina Colors", etc. can be exemplified. A bright pigment having a synthetic mica as a core material is effectively coated with a metal oxide such as titanium oxide on its surface, and the metal oxide is a metal oxide such as titanium, zirconium, chromium, vanadium, or iron. Examples thereof include metal oxides containing titanium oxide as a main component. Specifically, the product name "Ultimica" manufactured by Nippon Koken Kogyo Co., Ltd. can be exemplified. As a bright pigment having a flat glass piece as a core substance, a pigment whose surface is coated with a metal oxide such as titanium oxide is effective. Specifically, the product name "Metashine" manufactured by Nippon Sheet Glass Co., Ltd. Etc. can be exemplified.

A bright pigment whose core material is flaky aluminum oxide is effectively coated with a metal oxide such as titanium oxide on its surface, and the metal oxide is a metal such as titanium, zirconium, chromium, vanadium, or iron. Oxides can be exemplified, and preferred examples include metal oxides containing titanium oxide as a main component. Specifically, the product name "Shiraric" manufactured by Merck & Co., Inc. can be exemplified. The liquid crystal polymer used as a cholesteric liquid crystal type bright pigment has the property that only a part of the light incident on a wide spectral region is reflected due to the interference effect of light, and all the other regions transmit the light. It has excellent metallic luster and color flop property in which the hue changes depending on the viewpoint. It also has transparency. Specific examples of the cholesteric liquid crystal type bright pigment include the trade name "Helicone HC" manufactured by Wacker Chemie. Further, as a brilliant material in which a metal such as gold or silver is vacuum-deposited on a film and then the foil is peeled off and finely crushed, a trade name "LG neo" manufactured by Oike Kogyo Co., Ltd. can be exemplified.

The metallic luster pigment having an average particle size of 0.1 μm or more and 50 μm or less, preferably 2 μm or more and 40 μm or less, and more preferably 10 μm or more and 40 μm or less is preferable from the viewpoint of writing performance and brightness. The average particle size is measured by measuring the particle size distribution using a laser diffraction / scattering type particle size distribution measuring device [manufactured by Horiba Seisakusho Co., Ltd .; LA-300], and based on the numerical value, the average particle is measured on a volume basis. Calculate the diameter (median diameter).

In particular, those having an average particle size of 10 μm or more have extremely high brightness, but do not easily penetrate into the paper surface during writing. Therefore, it tends to be scattered by rubbing with a conventional friction body made of an elastic body, and depending on the viewing angle, the metallic luster pigment scattered over the entire scraped portion may be visually impaired. In particular, the high brilliance is emphasized on black paper, which makes it look even worse. On the other hand, by rubbing with a friction body made of a viscoelastic body, the metallic luster pigment can be adsorbed, peeled off without being scattered on the scraped portion, and the handwriting can be erased cleanly. Therefore, the brush strokes with metallic luster heat-adjustable discoloration ink can be chemically decolorized by frictional heat and decolorized (discolored) by using physical erasure by adsorption peeling, so that irreversible erasure and discoloration can be achieved. Especially effective.

Various additives can be added to the thermochromic ink as needed. For water-based inks, pH adjusters, rust preventives, preservatives or fungicides, wetting agents, defoaming agents, surfactants, lubricants, fixing agents such as resins, and shear reduction, which are conventionally applied. A viscosity-imparting agent, a pen tip drying inhibitor, a sagging inhibitor, and the like can be added. For oil-based inks, viscosity modifiers, preservatives, rust inhibitors, defoamers, lubricants, dispersants, anti-cassoulet agents, leak inhibitors, surfactants, etc., which are conventionally applied, are added. can do.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to the following Examples as long as the gist of the present invention is not exceeded. Various physical properties in Examples and Comparative Examples were measured by the following methods.

〔composition〕
The content (mol%) of each structural unit (4-methyl-1-pentene (4MP1) and α-olefin (AO)) in the 4-methyl-1-pentene / α-olefin copolymer (A) is determined. ¹³ Measured by C-NMR.
-Measuring device: Nuclear magnetic resonance device (ECP500 type, manufactured by JEOL Ltd.)
・ Observation nucleus: ¹³ C (125 MHz)
-Sequence: Single pulse proton decoupling-Pulse width: 4.7 μs (45 ° pulse)
・ Repeat time: 5.5 seconds ・ Cumulative number: 10,000 times or more ・ Solvent: Ortodichlorobenzene / deuterated benzene (volume ratio: 80/20) mixed solvent ・ Sample concentration: 55 mg / 0.6 mL
-Measurement temperature: 120 ° C
-Chemical shift reference value: 27.50 ppm

[Ultimate viscosity [η]]
The ultimate viscosity [η] of the copolymer was measured at 135 ° C. in a decalin solvent using an Ubbelohde viscometer as a measuring device.
After dissolving about 20 mg of the specified 4MP1 copolymer in 25 ml of decalin, the specific viscosity η _sp is measured in an oil bath at 135 ° C. using an Ubbelohde viscometer. After adding 5 ml of decalin to this decalin solution to dilute it, the specific viscosity η _sp is measured in the same manner as above. This dilution operation is repeated twice more, and the value of ηsp / C when the concentration (C) is extrapolated to 0 is obtained as the ultimate viscosity [η] (unit: dl / g) (see Equation 1 below).
[Η] = lim (ηsp / C) (C → 0) ・ ・ ・ Equation 1

[Weight average molecular weight (Mw) and molecular weight distribution (Mw / Mn)]
The weight average molecular weight (Mw) of the copolymer and the molecular weight distribution (Mw / Mn) represented by the ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn) are determined by gel permeation chromatography (GPC: Gel). It was calculated by a standard polystyrene conversion method using Permeation Chromatography).
-Conditions-
Measuring device: GPC (ALC / GPC 150-C plus type, differential refractometer detector integrated type, manufactured by Waters)
Column: Two GMH6-HT (manufactured by Tosoh Corporation) and two GMH6-HTL (manufactured by Tosoh Corporation) are connected in series. Eluent: o-dichlorobenzene Column temperature: 140 ° C.
Flow rate: 1.0 mL / min

[Melt flow rate (MFR)]
Melt Flow Rate (MFR) was measured at 230 ° C. with a load of 2.16 kg in accordance with ASTM D1238. The unit is g / 10 min.

〔density〕
The density of the copolymer was measured according to JIS K7112 (density gradient tube method). This density (kg / m ³ ) was used as an index of lightness.

[Melting point (Tm)]
The melting point (Tm) of the copolymer was measured using a differential scanning calorimeter (DSC220C type, manufactured by Seiko Instruments Inc.) as a measuring device. Approximately 5 mg of the polymer is sealed in a measuring aluminum pan and heated from room temperature to 200 ° C. at 10 ° C./min. To completely melt the polymer, hold at 200 ° C. for 5 minutes and then cool to −50 ° C. at 10 ° C./min. After standing at −50 ° C. for 5 minutes, the polymer is heated to 200 ° C. at 10 ° C./min for the second time, and the peak temperature (° C.) at the second heating is defined as the melting point (Tm) of the polymer. When a plurality of peaks are detected, the peak detected on the highest temperature side is adopted.

[Dynamic viscoelasticity]
In the measurement of the dynamic viscoelasticity of the copolymer and the resin composition, the temperature dependence of the dynamic viscoelasticity from -40 to 150 ° C. at a frequency of 10 rad / s was measured using MCR301 manufactured by ANTONPaar, and the temperature dependence was 0. The temperature at which the loss tangent (tan δ) due to the glass transition temperature reaches the peak value (maximum value) in the range of ~ 40 ° C. (hereinafter, also referred to as “peak value temperature”), and the loss tangent (tan δ) at that time. The value of was measured.

[Shore A hardness]
In the measurement of Shore A hardness, three sheets with a thickness of 2 mm obtained in Examples and Comparative Examples are stacked and used as a measurement sample, and the numerical value immediately after the needle is pressed is read in accordance with JIS K6253, and the value is read for 15 seconds in that state. The numerical value when it was allowed to stand was read. Further, the change ΔHS of the shore A hardness was calculated by the following formula.
ΔHS = (Shore A hardness value immediately after the start of needle contact-Shore A hardness value 15 seconds after needle contact)

[Pencil / ballpoint pen erasability test]
When 10 spiral circles are written by hand on writing paper A using a commercially available ballpoint pen and a commercially available pencil (made by Tombow Pencil, 8900-B), and then the handwriting is rubbed with a rubbing body to erase it. The condition of was visually confirmed. The evaluation of the test results is shown in Table 2.
A: Thermally discolorable handwriting or graphite handwriting was erased without causing residual color.
B: Thermally discolorable handwriting or graphite handwriting remained thin, and graphite was scattered to contaminate the area around the handwriting.
C: No thermochromic handwriting or graphite handwriting was erased.

[Generation of eraser residue]
Using a commercially available ballpoint pen and a commercially available pencil (Made by Tombow Pencil, 8900-B), write 10 spiral circles by hand on writing paper A, then rub the handwriting with an eraser, and rub after rubbing. It was confirmed whether or not eraser scraps (eraser scraps) were generated from the body. The evaluation of the test results is shown in Table 2.
A: No erasing residue was observed, and there was no problem in practical use.
B: The surface of the friction body was peeled off to generate erasing residue, and the erasing residue adhered to the friction body, which caused a problem in practical use.
C: A large amount of erasing residue was generated, which caused a problem in practical use.

<Synthesis example 1>
<Synthesis of 4-methyl-1-pentene / α-olefin copolymer (A-1)>
300 ml of n-hexane (dried on activated alumina in a dry nitrogen atmosphere) and 450 ml of 4-methyl-1-pentene were placed in a SUS autoclave with a stirring blade having a capacity of 1.5 L and sufficiently nitrogen-substituted. It was charged at 23 ° C. 0.75 ml of a 1.0 mmol / ml toluene solution of triisobutylaluminum (TIBAL) was charged into this autoclave, and the stirrer was rotated.

Next, the autoclave was heated to an internal temperature of 60 ° C. and pressurized with propylene so that the total pressure (gauge pressure) was 0.40 MPa.
Subsequently, 1 mmol of methylaluminoxane in terms of Al and 0.01 mmol of diphenylmethylene (1-ethyl-3-t-butyl-cyclopentadienyl) (2,7-di-t-) prepared in advance. 0.34 ml of a toluene solution containing butyl-fluorenyl) zirconium dichloride was press-fitted into an autoclave with nitrogen to initiate a polymerization reaction. During the polymerization reaction, the temperature was adjusted so that the internal temperature of the autoclave was 60 ° C.

60 minutes after the start of polymerization, 5 ml of methanol was press-fitted into the autoclave with nitrogen to stop the polymerization reaction, and then the inside of the autoclave was depressurized to atmospheric pressure. After depressurization, acetone was added to the reaction solution while stirring the reaction solution to obtain a polymerization reaction product containing a solvent.

The resulting polymerization reaction product containing the solvent was then dried under reduced pressure at 100 ° C. for 12 hours to give 36.9 g of a powdered 4-methyl-1-pentene / α-olefin copolymer (A-1). ) (Hereinafter, also referred to as a copolymer (A-1)) was obtained. Table 1 shows the measurement results of various physical properties of the obtained copolymer (A-1).

The content of 4-methyl-1-pentene in the copolymer (A-1) was 72.5 mol%, and the content of propylene was 27.5 mol%. The density of the copolymer (A-1) was 839 kg / m ³ . The limit viscosity [η] of the copolymer (A-1) is 1.5 dl / g, the weight average molecular weight (Mw) is 337,000, and the molecular weight distribution (Mw / Mn) is 2.1. The melt flow rate (MFR) was 11 g / 10 min. The melting point (Tm) of the copolymer (A-1) was not observed.

<Thermoplastic elastomer (B)>
The following thermoplastic elastomer (B) was used.
Thermoplastic Elastomer (B-1): Mirastomer manufactured by Mitsui Chemicals, Inc. (brand: 8030NS)
Thermoplastic Elastomer (B-2): Mirastomer manufactured by Mitsui Chemicals, Inc. (brand: 5030NS)
Thermoplastic Elastomer (B-3): Tough Tech manufactured by Asahi Kasei Corporation (Brand: H1221)

<Crystalline polyolefin (C)
The following crystalline polyolefin (C) was used.
Polyolefin (C-1): Evolu manufactured by Prime Polymer Co., Ltd. (brand: SP4030)
Polyolefin (C-2): Evolu manufactured by Prime Polymer Co., Ltd. (brand: SP2320)

<Example 1>
40 parts by mass of 4-methyl-1-pentene / α-olefin copolymer (A-1) and 60 parts by mass of thermoplastic elastomer (B-1) are mixed and mixed to withstand heat as a secondary antioxidant. 0.2 parts by mass of n-octadecyl-3- (4'-hydroxy-3', 5'-di-t-butylphenyl) propinate as a stabilizer was blended. After that, a twin-screw extruder BT-30 (screw system 30 mmφ, L / D = 46) manufactured by Plastic Engineering Laboratory Co., Ltd. was used under the conditions of a set temperature of 230 ° C., a resin extrusion rate of 60 g / min, and 200 rpm. The resin composition was obtained by granulating and pelletizing. This resin composition was put into a hopper of an injection molding machine (manufactured by Toshiba Machine Co., Ltd.). Then, the cylinder temperature was set to 230 ° C. and the die temperature was set to 230 ° C., and a 120 × 120 × 2 mm sheet was molded. Table 2 shows the evaluation results of the physical characteristics of the obtained sheet and the evaluation results of the erasability of the sheet as a friction body by cutting the sheet into a size of 5 mm × 5 mm.

<Example 2>
Instead of 40 parts by mass of the copolymer (A-1) and 60 parts by mass of the thermoplastic elastomer (B-1), 30 parts by mass of the 4-methyl-1-pentene / α-olefin copolymer (A-1) was used. The sheet and friction material of Example 2 were obtained by the same method as in Example 1 except that 60 parts by mass of the thermoplastic elastomer (B-2) and 10 parts by mass of the crystalline polyolefin (C-1) were used. Table 2 shows the results of evaluating the physical properties of the obtained sheet and friction body.

<Example 3>
40 parts by mass of copolymer (A-1), 40 parts by mass of 4-methyl-1-pentene / α-olefin copolymer (A-1) instead of 60 parts by mass of thermoplastic elastomer (B-1), The sheet and friction material of Example 3 were obtained by the same method as in Example 1 except that 35 parts by mass of the thermoplastic elastomer (B-2) and 25 parts by mass of the crystalline polyolefin (C-1) were used. Table 2 shows the results of evaluating the physical properties of the obtained sheet and friction body.

<Example 4>
40 parts by mass of copolymer (A-1), 40 parts by mass of 4-methyl-1-pentene / α-olefin copolymer (A-1) instead of 60 parts by mass of thermoplastic elastomer (B-1), The sheet and friction material of Example 4 were obtained by the same method as in Example 1 except that 40 parts by mass of the thermoplastic elastomer (B-2) and 20 parts by mass of the crystalline polyolefin (C-1) were used. Table 2 shows the results of evaluating the physical properties of the obtained sheet and friction body.

<Example 5>
40 parts by mass of copolymer (A-1), 40 parts by mass of 4-methyl-1-pentene / α-olefin copolymer (A-1) instead of 60 parts by mass of thermoplastic elastomer (B-1), The sheet and friction material of Example 5 were obtained by the same method as in Example 1 except that 30 parts by mass of the thermoplastic elastomer (B-2) and 20 parts by mass of the crystalline polyolefin (C-2) were used. Table 2 shows the results of evaluating the physical properties of the obtained sheet and friction body.

<Comparative example 1>
Instead of 40 parts by mass of the copolymer (A-1) and 60 parts by mass of the thermoplastic elastomer (B-1), 70 parts by mass of the 4-methyl-1-pentene / α-olefin copolymer (A-1) was used. And the sheet and friction body of Comparative Example 1 were obtained by the same method as in Example 1 except that 30 parts by mass of the plastic elastomer (B-1) was used. Table 2 shows the results of evaluating the physical properties of the obtained sheet and friction body.

<Comparative example 2>
Example 1 and the friction material except that 100 parts by mass of the copolymer (A-1) was used instead of 40 parts by mass of the copolymer (A-1) and 60 parts by mass of the thermoplastic elastomer (B-1). A sheet of Comparative Example 2 was obtained by the same method. Table 2 shows the results of evaluating the physical properties of the obtained sheet and friction body.

<Comparative example 3>
Instead of 40 parts by mass of copolymer (A-1) and 60 parts by mass of thermoplastic elastomer (B-1), thermoplastic elastomer (B-3) (manufactured by Asahi Kasei Chemicals Co., Ltd., trade name: Tough Tech (registered trademark)) H1221) A sheet and a friction material of Comparative Example 3 were obtained by the same method as in Example 1 except that 100 parts by mass was used. Table 2 shows the results of evaluating the physical properties of the obtained sheet and friction body.

<Comparative example 4>
Using a commercially available vinyl chloride eraser (manufactured by Pentel), an erasing test for ballpoint pens and pencils and an evaluation of the occurrence of eraser residue were carried out. The results are shown in Table 2.

From Table 2, as a concrete result of the erasability test, by repeatedly rubbing the handwriting, the friction body of the present invention exhibits the performance as an elastic body, frictional heat is generated, and the heat-discoloring pigment becomes transparent. You can see that. At that time, it can be seen that the bright pigment is adsorbed and peeled off from the paper surface by exhibiting the performance as a viscous body. Therefore, it is considered that the handwriting was erased cleanly without contaminating the paper surface.

Claims (9)

The 4-methyl-1-pentene / α-olefin copolymer (A) and the thermoplastic elastomer (B) that satisfy the following requirements (a) to (b) are contained, and the 4-methyl-1-pentene / α -Resin composition (X) for a friction body in which the mass ratio [(A) / (B)] of the olefin copolymer (A) to the thermoplastic elastomer (B) is 10/90 to 67/33.
Requirement (a) ; The melting point (Tm) of the copolymer (A) is not observed in the calorimeter measurement by the differential scanning calorimeter (DSC).
Requirement (b) ; The copolymer (A) is derived from the structural unit (i) derived from 4-methyl-1-pentene and the α-olefin (excluding 4-methyl-1-pentene). Including the structural unit (ii), the total of the structural unit (i) and the structural unit (ii) is 100 mol%, and the structural unit (i) 60 to 78 mol% and the structural unit (ii) 22 to 22 to Includes with 40 mol%. The resin composition (X) for a friction body according to claim 1, further comprising a crystalline polyolefin (C). The resin composition (X) for a friction body according to claim 1 or 2, wherein the following requirements (x) and (y) are satisfied.
Requirement (x) ; In accordance with JIS K6253, both 4-methyl-1-pentene and α-olefin are measured 15 seconds after the start of needle push contact, which is measured in a state where three sheets having a thickness of 2 mm are stacked. The shore A hardness of the polymer (A) is 60 or more and 90 or less.
Requirement (y) ; Shore A hardness of the 4-methyl-1-pentene / α-olefin copolymer (A) measured in a state where three sheets having a thickness of 2 mm are stacked in accordance with JIS K6253. The difference ΔHS between the shore A hardness value immediately after the needle contact and the shore A hardness value 15 seconds after the needle contact, which is represented by the following formula, is 10 or more and 35 or less.
ΔHS = (Shore A hardness value immediately after needle contact-Shore A hardness value 15 seconds after needle contact) The resin composition for a friction body according to any one of claims 1 to 3, wherein the 4-methyl-1-pentene / α-olefin copolymer (A) satisfies the following requirement (c). Object (X).
Requirement (c ); The tan δ peak temperature obtained by performing dynamic viscoelasticity measurement at a frequency of 10 rad / s (1.6 Hz) in a temperature range of -40 to 150 ° C. is 10 ° C. or higher and 38 ° C. or lower. A friction body comprising the composition (X) for a friction body according to any one of claims 1 to 4. The friction body according to claim 5, wherein the friction body is manufactured by injection molding. A writing tool comprising a writing tool main body and the friction body according to claim 5 or 6 attached to the writing tool main body, and having a heat-discoloring ink incorporated in the writing tool main body. The writing instrument according to claim 7, wherein the thermochromic ink contains a thermochromic microcapsule pigment having an average particle size of 0.05 μm or more and 5.0 μm or less. The writing instrument according to claim 7, wherein the thermochromic ink contains a metallic luster pigment having an average particle size of 0.1 μm or more and 50 μm or less.