JP7007507B2 - Friction body, stationery and stationery set - Google Patents

Description

The present invention relates to a friction body, a writing tool and a writing tool set.

Conventionally, there is known a writing tool provided with a heat-discoloring ink and a friction body, which is configured so that an image formed by using the heat-changing ink can be abraded by the friction body and discolored by frictional heat. ing. As the friction body, one composed of an elastomer is known.

Patent Document 1 is a friction body having elasticity that changes the color of an image formed by using a reversible thermochromic ink from a first state to a second state by frictional heat, and the friction body is made of silicone rubber. The friction body to be described is described.

Patent Document 2 is a friction body that changes the color of an image formed by using a reversible thermochromic ink from a first state to a second state by frictional heat, and is a styrene-butylene-styrene copolymer or styrene-ethylene. A friction body characterized by being composed of a butylene-styrene copolymer is described. According to the invention described in Patent Document 2, Patent Document 2 provides a friction body capable of easily discoloring without peeling off the thermal discoloration image and forming a thermal discoloration image again on the scraped portion without causing ink repelling. Describe that it will be obtained.

Japanese Unexamined Patent Publication No. 2004-148744 Japanese Unexamined Patent Publication No. 2006-1233224

The present inventors have created a heat-discolorable image (typically, an image formed on a paper surface using a heat-discolorable ink) with a styrene-based copolymer as described in Patent Document 2, for example. When the friction body made of coalesced material discolors by rubbing, there arises a problem that the paper surface becomes contaminated due to a particularly strong load, repeated rubbing motion, etc. (hereinafter, also simply referred to as paper surface contamination). I paid attention to it. The present invention solves the above-mentioned problems, can satisfactorily discolor an image having thermal discoloration by rubbing (that is, gives good discoloration), and contaminate the paper surface by a strong force and / or repeated rubbing operations. It is an object of the present invention to provide a friction body capable of reducing the amount of friction, and a writing tool and a writing tool set provided with such a friction body.

The present invention includes at least the following aspects.
[1] A friction body that discolors an image having thermal discoloration by frictional heat.
Contains styrene-based elastomers
Compressive set at 120 ° C.: 80% or less, and Shore A hardness: 60-98,
Has a friction body.
[2] The friction body according to the above aspect 1, wherein the styrene-based elastomer is crosslinked.
[3] The styrene-based elastomer is selected from the group consisting of styrene-ethylene-propylene-styrene (SEPS), styrene-ethylene-ethylene-propylene-styrene (SEEPS) and styrene-ethylene-butadiene-styrene (SEBS). The friction body according to the above aspect 1 or 2.
[4] The friction body according to any one of the above aspects 1 to 3, which contains 0.1 to 3.0% by mass of a lubricant.
[5] A writing tool having a thermochromic ink and a friction body that discolors the handwriting of the thermochromic ink by frictional heat.
A writing tool in which the friction body is the friction body according to any one of the above aspects 1 to 4.
[6] A writing instrument set including a writing instrument having a heat-changing ink and a friction body that changes the handwriting of the heat-changing ink by frictional heat.
A writing tool set in which the friction body is the friction body according to any one of the above aspects 1 to 4.

According to the present invention, an image having thermal discoloration can be satisfactorily discolored by rubbing (that is, giving good discoloration), and paper surface contamination due to strong force and / or repeated rubbing operations can be reduced. Possible friction bodies, as well as writing tools and writing tool sets comprising such friction bodies are provided.

It is a partial cross-sectional view of the writing instrument which concerns on one Embodiment of this invention. It is a perspective view of the friction body which concerns on one Embodiment of this invention. It is a perspective view of the friction body which concerns on one Embodiment of this invention.

Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to these embodiments. Unless otherwise specified, the various characteristic values described in the present disclosure are measured by the method described in the [Example] section of the present disclosure or a method understood by those skilled in the art to be equivalent thereto. Is intended to be the value of.

<Friction body>
One aspect of the present invention is
A friction body that discolors an image with thermal discoloration by frictional heat.
Contains styrene-based elastomers
Compressive set at 120 ° C.: 80% or less, and Shore A hardness: 60-98,
It is a friction body having.

In the present disclosure, the "image having thermal discoloration" means another color (for example, when the temperature is maintained at a predetermined temperature (for example, 25 ° C.) and the temperature is raised to a predetermined temperature (for example, 60 ° C.). It means an image having the property of changing to the second color) and optionally returning to the original color (first color) when cooled to a predetermined temperature (for example, −5 ° C.). An image having thermal discoloration property can be typically formed by using a thermal discoloration ink described later.

When an image having thermal discoloration is rubbed with a friction body to discolor it, the cause of paper contamination due to a particularly strong force and / or repeated frictional motion is not clear. However, the present inventors change the physical properties of the friction body due to the increase in the surface temperature of the friction body during scraping, and the friction body is destroyed (specifically, local peeling) to occur on the paper surface. It is speculated that the adhesion may be the cause of paper contamination, and the softening of the elastomer makes the force applied to the paper surface uneven during rubbing, and when trying to completely discolor the ink, a strong local force is applied. It was speculated that the fact that the heat-discolorable coloring material was destroyed by being exposed to the ink may also be the cause of the paper surface contamination. They have found that controlling the deformation recovery of the friction body, particularly in a high temperature region, is effective in reducing the above-mentioned fracture of the friction body.

The friction body provided by one aspect of the present invention has an appropriate hardness and exhibits good deformation recovery even at a high temperature by controlling the balance between the Shore A hardness and the compression set in a high temperature region. Therefore, the image having thermal discoloration can be satisfactorily discolored by rubbing (that is, giving good discoloration), and the friction body is not easily destroyed by a strong force and / or repeated rubbing operation, so that the paper surface is contaminated. Can be reduced.

The friction body has a compression set at 120 ° C. (also referred to as “120 ° C. compression set” in the present disclosure): 80% or less. The low 120 ° C. compression set is an indicator of good deformation recovery of the friction body under scraping conditions (ie high temperature conditions), and this good deformation recovery is especially under friction conditions of the friction body (ie, high temperature conditions). That is, it contributes to maintaining good wear resistance under high temperature conditions).

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

In general, the compression set of a molded product formed from an elastomer tends to increase with increasing temperature. The friction bodies of the present disclosure have a small 120 ° C. compression set as in the above specific range. From the viewpoint of obtaining such a 120 ° C. compression set, it is advantageous to reduce the temperature dependence of the compression set in the friction body. In the friction body, the ratio (A) / (B) of the compression set (A) / (B) at 120 ° C to the compression set (B) at 70 ° C is 1.0 or more and 1.7 or less, and 1.0 or more and 1.5. Hereinafter, it may be 1.0 or more and 1.4 or less, or 1.0 or more and 1.3 or less.

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

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 contains an elastomer component and an additive component. Hereinafter, the 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 exemplified, and the material components are as shown in the following examples. Is not limited.

[Elastomer component (component (A))]
Examples of the elastomer component include a styrene-based elastomer, a polyester-based elastomer, and an olefin-based elastomer. However, the elastomer component is a styrene-based elastomer in that the desired 120 ° C. compression permanent strain and Shore A hardness can be easily realized. Containing, preferably made of a styrene-based elastomer.

In the present disclosure, the "styrene-based elastomer" means an elastomer containing a styrene constituent unit in the main chain, and is typically a thermoplastic elastomer. From the viewpoint of facilitating the realization of the desired 120 ° C. compression permanent strain and Shore A hardness, the styrene-based elastomer has a composition derived from a polymer block mainly composed of a constituent unit derived from a styrene skeleton-containing compound and a conjugated diene compound. It is preferably a block copolymer having a polymer block mainly composed of a unit (hereinafter referred to as a styrene-based block copolymer), a hydrogenated additive of the block copolymer, or a mixture thereof. The above-mentioned "polymer block mainly composed of a structural unit derived from a styrene skeleton-containing compound (or a conjugated diene compound)" means that the structural unit present in the highest mass ratio in the polymer block is a styrene skeleton-containing compound ( Or a polymer block that is a structural unit derived from a conjugated diene compound).

The above-mentioned styrene-based block copolymer is usually one or more of polymer blocks X mainly composed of a structural unit derived from a styrene skeleton-containing compound, preferably two or more from the viewpoint of mechanical properties, and a conjugated diene compound. It is a block copolymer having one or more of polymer blocks Y mainly composed of the derived structural unit. For example, block copolymers having structures such as XY, XYX, YYXYX, and XYXYXX can be mentioned.

The hydrogen additive of the styrene-based block copolymer can be obtained by adding hydrogen to the carbon-carbon double bond in the styrene-based block copolymer to form a carbon-carbon single bond. The hydrogenation can be carried out by a known method, for example, hydrogenation using a hydrogenation catalyst in an inert solvent.

The hydrogenation rate of the hydrogenated product of the styrene-based block copolymer (that is, the carbon-carbon single bond generated by hydrogenation with respect to the number of carbon-carbon double bonds in the styrene-based block copolymer before hydrogenation). The ratio) may be 50% or more, 70% or more, or 90% or more from the viewpoint of improving erasing performance, paper surface stain resistance, and wear resistance. The hydrogenation rate means a value measured by ¹ H-NMR unless otherwise specified.

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-butyl styrene, α-methyl styrene, divinyl benzene, 1,1-diphenyl styrene, N, N-diethyl-p-aminoethyl styrene, and p-third butyl styrene. , Alkylstyrene in which at least one of the alkyl groups having 1 to 8 carbon atoms is bonded to the benzene ring, and the like. Among these, styrene and alkylstyrene in which at least one of the alkyl groups having 1 to 8 carbon atoms is bonded to the benzene ring are preferable. As the styrene skeleton-containing compound, one or more of these can be used.

Examples of the alkyl styrene in which at least one of the alkyl groups having 1 to 8 carbon atoms is bonded to the benzene ring include o-alkyl styrene, m-alkyl styrene, p-alkyl styrene, 2,4-dialkyl styrene, and 3. Alkyl styrenes such as 5-dialkyl styrene and 2,4,6-trialkyl styrene, and halogenated alkyl styrenes in which one or more hydrogen atoms of the alkyl group in these alkyl styrenes are substituted with halogen atoms. , Etc. can be mentioned. 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 -Chloromethyl styrene, p-chloromethyl styrene, 2,4-bis (chloromethyl) styrene, 3,5-bis (chloromethyl) styrene, 2,4,6-tri (chloromethyl) styrene, o-dichloromethyl Examples thereof include styrene, m-dichloromethylstyrene, p-dichloromethylstyrene, and the like. Among these, p-methylstyrene is particularly preferable from the viewpoint of crosslinkability.

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.

The proportion of alkylstyrene in which at least one of the alkyl groups having 1 to 8 carbon atoms is bonded to the benzene ring in the polymer block X is preferably 1% by mass or more, more preferably 50% by mass or more from the viewpoint of crosslinkability. Preferably, it may be further 100% by mass.

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), etc. can be mentioned. Of these, 1,3-butadiene and isoprene are preferred. As the conjugated diene compound, one or more of these can be used.

The content of the structural unit derived from the styrene skeleton-containing compound in the styrene-based block copolymer or its hydrogenated compound is not particularly limited, but is 5 from the viewpoint of mechanical strength, cold resistance, heat resistance and flexibility. It may be up to 50% by mass, or 20 to 40% by mass.

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. From the viewpoint of heat resistance, it is usually 50% by mass or more, and may be 70% by mass or more, or 90% by mass or more. The distribution of the structural units derived from the conjugated diene compound in the polymer block X is not particularly limited. When two or more of the polymer blocks X are present in the styrene-based elastomer molecule, they may have the same structure or different structures from each other.

The polymer block Y is preferably a polymer block composed 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 structural unit derived from the conjugated diene compound in the polymer block Y in the copolymer block is not particularly limited, but is heat resistant. From the viewpoint of sex, it is usually 50% by mass or more, and may be 70% by mass or more, or 90% by mass or more. The distribution of the structural units derived from the styrene skeleton-containing compound 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 the styrene-based elastomer molecule, they may have the same structure or different structures from each other.

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

Examples of the hydrogen additive of the styrene block copolymer include styrene-ethylene-butene copolymer (SEB), styrene-ethylene-propylene copolymer (SEP), and styrene-ethylene-butene-styrene copolymer. (SEBS), styrene-ethylene-propylene-styrene copolymer (SEPS), styrene-ethylene-ethylene-propylene-styrene copolymer (SEEPS) and the like can be mentioned.

Of these, styrene-ethylene-propylene-styrene (SEPS), styrene-ethylene-ethylene-propylene-styrene (SEEPS) and styrene-ethylene-butadiene-styrene (SEBS) are preferable, and styrene-ethylene-propylene-in particular. Styrene copolymer (SEPS) and styrene-ethylene-ethylene-propylene-styrene copolymer (SEEPS) are preferable from the viewpoint of wear resistance.

The styrene-based block copolymers listed above and / or their hydrogenated additives can be used in one type or in a mixture of two or more types.

The styrene-based elastomer may be crosslinked. Increasing the degree of cross-linking contributes to the reduction of 120 ° C. compression set and the increase of Shore A hardness. In this case, SEBS, SEPS, and SEEPS in which styrene is replaced with p-methylstyrene are preferable from the viewpoint of heat resistance and wear resistance. Whether or not the styrene-based elastomer is crosslinked is determined by visually observing whether or not the gel remains after being immersed in hot xylene at 120 ° C. or measuring the residual weight. Can be distinguished by. For cross-linking, for example, a cross-linking agent (component (E)) described later can be used. In an exemplary embodiment, the friction body can be free of 120 ° C. thermoxylene insoluble polymers other than crosslinked styrene-based elastomers. In this case, whether or not the styrene-based elastomer is crosslinked can also be evaluated by subjecting the friction body to the above-mentioned thermal xylene treatment.

The mass average molecular weight (Mw) of the styrene-based elastomer is preferably 150,000 to 500,000. The mass average molecular weight may be 150,000 or more, 180,000 or more, or 200,000 or more from the viewpoint of obtaining a friction body having good wear resistance. On the other hand, the mass average molecular weight may be 500,000 or less, 450,000 or less, or 400,000 or less from the viewpoint of good processability at the time of producing the friction body. In the present disclosure, molecular weight means a polystyrene-equivalent value measured by a gel permeation chromatography (GPC) method unless otherwise specified.

[Other ingredients]
Examples of other components include a propylene resin (hereinafter, component (B)), a softening agent for rubber (hereinafter, component (C)), a lubricant (hereinafter, component (D)), and a cross-linking agent (hereinafter, component (hereinafter, component ()). E)), cross-linking aid (hereinafter, component (F)), colorant (hereinafter, component (G)), polymer component other than the above propylene resin, stabilizer, filler, etc., one or more of them are used. can.

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

The propylene homopolymer is a polymer composed of only propylene units, and is most preferable as the component (B) because of its high crystallinity and melting point.

The propylene-based random copolymer is a propylene / ethylene random copolymer obtained by copolymerizing propylene and ethylene, and obtained by copolymerizing propylene with at least one α-olefin having 4 to 20 carbon atoms. Examples thereof include a propylene / α-olefin random copolymer obtained by copolymerizing propylene with ethylene and at least one α-olefin having 4 to 20 carbon atoms to obtain a propylene / ethylene / α-olefin random copolymer. can.

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, and the like. 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-hexene, methyl-1-hexene, dimethyl-1-pentene, 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- Undesen, 1-dodesen, and the like can be mentioned. 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.

Specific examples of the propylene-based random copolymer include, for example, a propylene-ethylene random copolymer, a propylene-1-butene random copolymer, a propylene-1-hexene random copolymer, and a propylene-1-octene random copolymer. Examples thereof include a coalescence, a propylene-ethylene-1-butene random copolymer, a propylene-ethylene-1-hexene random copolymer, a propylene-ethylene-1-octene random copolymer, and the like, and propylene-ethylene random is preferable. Copolymers, propylene-1-butene random copolymers, propylene-1-hexene random copolymers, propylene-ethylene-1-butene random copolymers, propylene-ethylene-1-hexene random copolymers, etc. Is.

Examples of the propylene-based block copolymer include a block copolymer composed of a crystalline propylene-based polymer moiety and a non-crystalline propylene / α-olefin copolymer moiety.

Examples of the crystalline propylene-based polymer include a homopolymer of propylene or a random copolymer of propylene and a small amount of other α-olefins.

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

As a propylene-based block copolymer, in addition to the above other α-olefins, 1,4-hexadiene, 5-methyl-1,5-hexadiene, 1,4-octadiene, cyclohexadiene, cyclooctadiene, dicyclopentadiene, A ternary or quaternary or more copolymerized with a non-conjugated diene such as 5-methylene-2-norbornene, 5-ethylidene-2-norbornene, 5-butylidene-2-norbornene, and 5-isopropenyl-2-norbornene. Copolymers can also be used.

The melt mass flow rate of the above component (B) is based on JIS K 7210-1999 from the viewpoint of moldability, and is 0.01 to 100 g / 10 minutes, 0 when measured at 230 ° C. and 21.18 N. .1 to 50 g / 10 minutes, or 0.3 to 10 g / 10 minutes.

Further, the melting point of the component (B) may be 150 ° C. or higher or 160 ° C. or higher from the viewpoint of heat resistance. The upper limit of the melting point is not particularly limited, but since it is a polypropylene-based resin, the upper limit is, for example, about 167 ° C. For the above melting point, use a DSC type differential scanning calorimeter (for example, Diamond of PerkinElmer Japan Co., Ltd.) and hold at 230 ° C for 5 minutes → cool to -10 ° C at 10 ° C / min → hold at -10 ° C for 5 minutes. → Intended to be the peak top melting point of the peak that appears on the highest temperature side in the second melting curve (that is, the melting curve measured in the final temperature rise process) when measured by the program of heating to 230 ° C at 10 ° C / min. do.

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 with respect to 100 parts by mass of the component (A). Within this range, the balance between flexibility, abrasion resistance, and paper stain resistance is improved.

[Rubber softener (component (C))]
As the softener for rubber (component (C)), various compounds understood by those skilled in the art to function as softeners in the art can be used. The use of component (C) is advantageous in improving the flexibility of the friction body. The component (C) is typically a non-aromatic rubber softener. An example of a non-aromatic rubber softener is a non-aromatic mineral oil (that is, a hydrocarbon compound derived from petroleum or the like, which is not classified as an aromatic compound in the classification described later (that is, has an aromatic carbon number). (Less than 30%)) or non-aromatic synthetic oils (ie synthetic hydrocarbon compounds that do not use aromatic monomers). Non-aromatic rubber softeners are usually liquid, gel-like or gum-like at room temperature.

The mineral oil used as the component (C) is a mixture of compounds having one or more of a paraffin chain, a naphthenic ring, and an aromatic ring, and those having a naphthenic ring of 30 to 45% based on the number of carbon atoms are naphthenic minerals. Oils with an aromatic ring of 30% or more are called aromatic mineral oils, which do not belong to naphthenic mineral oils or aromatic mineral oils, and have paraffin chains occupying 50% or more on a carbon number basis. Is called paraffin-based mineral oil and is distinguished.

Examples of the component (C) include paraffin-based mineral oils such as linear saturated hydrocarbons, branched saturated hydrocarbons, and derivatives thereof; naphthenic mineral oils; hydrogenated polyisobutylene, polyisobutylene, and polybutene. Synthetic oil; etc. Among these, paraffin-based mineral oil is preferable, and paraffin-based mineral oil having a small number of aromatic carbon atoms is more preferable, from the viewpoint of compatibility with the elastomer component. Further, from the viewpoint of handleability, those which are liquid at room temperature are preferable.

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

The blending amount of the component (C) is 1 to 400 parts by mass, 10 to 250 parts by mass, or 40 to 180 parts by mass with respect to 100 parts by mass of the component (A) from the viewpoint of the balance between flexibility and mechanical properties. It may be a department.

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

Examples of the component (D) include silicone-based compounds, fluorine-based compounds, surfactants, and the like, and silicone-based compounds are preferable from the viewpoint of suppressing friction on the paper surface.

As the silicone compound, silicone oil, silicone gum and the like can be used. Among these, those having a high molecular weight are preferable from the viewpoints of heat resistance, bleed resistance, and friction suppression on the paper surface. However, in general, a high molecular weight silicone compound is a high-viscosity liquid or gum-like, and therefore tends to have poor handleability. Therefore, a blend with a resin or a copolymer with a resin is suitable for use. The resin used here is selected in consideration of compatibility with other components constituting the friction body, particularly the component (A), but in general, olefin resins such as polyethylene and polypropylene are preferable. Is.

As the fluorine-based compound, polyvinylidene fluoride, polyvinyl fluoride and the like can be used. Among these, polyvinylidene fluoride is preferable from the viewpoint of suppressing friction on the paper surface.

As the surfactant, any of anionic, cationic and nonionic surfactants can be used.

The blending amount of the component (D) is 0.1 to 30 parts by mass, 0.5 to 20 parts by mass, or 1 to 10 parts by mass with respect to 100 parts by mass of the component (A) from the viewpoint of suppressing friction on the paper surface. It may be a department.

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

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

Examples of the component (E) include organic peroxides, phenolic compounds, and the like, and organic peroxides are preferable from the viewpoint of wear resistance.

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, a radical is generated at the time of producing a friction body (for example, when the material composition is melt-kneaded), and the radical reacts in a chain reaction to be described above. It works to crosslink the component (A).

Examples of the organic peroxide include dicumyl peroxide, di-tert-butyl peroxide, 2,5-dimethyl-2,5-di- (tert-butylperoxy) hexane, and 2,5-dimethyl-. 2,5-Di- (tert-butylperoxy) hexin-3,1,3-bis (tert-butylperoxyisopropyl) benzene, 1,1-bis (tert-butylperoxy) -3,3,5 -Trimethylcyclohexane, n-butyl-4,4-bis (tert-butylperoxy) valerate, benzoylperoxide, p-chlorobenzoylperoxide, 2,4-dichlorobenzoylperoxide, tert-butylperoxybenzoate, tert -Butyl peroxyisopropyl carbonate, diacetyl peroxide, lauroyl peroxide, tert-butyl cumyl peroxide, and the like can be mentioned. Among these, 2,5-dimethyl-2,5-di- (tert-butylperoxy) hexane and 2,5-dimethyl-2 from the viewpoint of low odor, low coloration, and scorch safety. , 5-Di- (tert-butylperoxy) hexin-3 is preferred.

When an organic peroxide is used as the component (E), it is preferable to use a cross-linking aid (component (F)) described later. By also using the component (F), a uniform and efficient cross-linking reaction can be performed.

As the phenolic compound, a resol resin is preferable from the viewpoint that it is usually liquid. The resol resin is produced by condensation of an alkyl-substituted phenol or an unsubstituted phenol with an aldehyde (preferably formaldehyde) in an alkaline medium, or condensation of bifunctional phenol dialcohols. The alkyl substituent moiety of the alkyl substituted phenol typically has 1-10 carbon atoms. Dimethylol phenol or a phenol resin substituted with an alkyl group having 1 to 10 carbon atoms at the p-position is preferable.

Among the above phenolic compounds, an alkylphenol formaldehyde resin, a methylolated alkylphenol resin, a brominated alkylphenol resin and the like are preferable. From an environmental point of view, it is desirable that it is not brominated, but it may be that the terminal hydroxyl group is brominated. In particular, an alkylphenol formaldehyde resin is preferable.

The blending 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 with respect to 100 parts by mass of the component (A). It is preferable that it is at least the above lower limit value in that the crosslinking reaction proceeds satisfactorily, while it is preferable that it is at least the above upper limit value in that the crosslinking does not proceed too much and the moldability is maintained well.

[Crosslinking aid (component (F))]
As the cross-linking aid (component (F)), various compounds understood by those skilled in the art to function as a cross-linking aid or a cross-linking accelerator in the art can be used.

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

Among the above components (F), a polyfunctional acrylate compound and a polyfunctional methacrylate compound are preferable, and triallyl cyanurate, triethylene glycol dimethacrylate, and tetraethylene glycol dimethacrylate are particularly preferable. These compounds are easy to handle, have an organic peroxide solubilizing effect, and act as a dispersion aid for organic peroxides. Therefore, when used in combination with organic peroxides, cross-linking is more uniform. And can be effective.

The blending 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 with respect to 100 parts by mass of the component (A). When it is at least the above lower limit value, it is preferable that the crosslinking reaction proceeds well, while when it is at least the above upper limit value, the crosslinking does not proceed too much and the dispersion of the crosslinked product in the friction body is good. It is preferable in that it is maintained at.

[Colorant (component (G))]
As the colorant (component (G)), various compounds understood by those skilled in the art to function as a colorant in the art can be used. As the component (G), an inorganic pigment, an organic pigment and the like are preferable.

<Manufacturing of friction body>
The friction body can be manufactured by, for example, the following method, but is not limited to this. First, a material composition is prepared by mechanically melt-kneading the above-mentioned material components. For melt-kneading, a general melt-kneader such as a Banbury mixer, various kneaders, a single-screw or twin-screw extruder can be used. Next, the obtained material composition can be molded by a general molding method of a thermoplastic resin such as injection molding, extrusion molding, blow molding or the like to obtain a friction body having a desired shape. An example of a suitable shape of the friction body will be described later with reference to the drawings.

<Stationery and stationery set>
The present disclosure also includes a writing tool and a writing tool set including the above-mentioned friction body.

Another aspect of the invention is
A writing tool having a thermochromic ink and a friction body that discolors the handwriting of the thermochromic ink by frictional heat.
Provided is a writing tool in which the friction body is the friction body of the present disclosure.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Corresponding components are designated with a common reference code throughout the drawings.

FIG. 1 is a partial cross-sectional view of a writing instrument according to an embodiment of the present invention. The writing tool 1 is a shaft via a cylinder 2 formed in a tubular shape, a refill (not shown) which is a cursive body arranged in the cylinder 2 and having a writing portion 3 at one end, and a holding member 4. A friction body 5 provided at the rear end of the cylinder 2, a cover member 6 that covers the friction body 5 and can be attached to and detached from the friction body 5, and an article attached to the side surface of the rear end of the cylinder 2. It has a clip 7 for gripping. In the present disclosure, in the axial direction of the writing instrument 1, the writing unit 3 side is defined as the "front" side, and the side opposite to the writing unit 3 is defined as the "rear" side. Unless otherwise specified, the central axis refers to the central axis of the writing instrument 1.

The writing tool 1 is a heat-discoloring writing tool that stores the heat-discoloring ink in a refill, and the handwriting of the writing tool 1 can be thermally discolored by the frictional heat generated when the writing tool 1 is rubbed by the friction body 5.

The friction body 5 can move with respect to the barrel 2 by pressing it forward. In the writing tool 1, the refill moves in the front-rear direction in the barrel 2 by a knock operation that pushes the friction body 5 forward against the urging force of the spring arranged in the barrel 2. At this time, the state in which the writing unit 3 protrudes from the barrel 2 is referred to as a writing state (FIG. 1), and the state in which the writing portion 3 is immersed in the barrel 2 is referred to as a non-writing state (not shown).

FIG. 2 is a perspective view of the friction body 5 and the holding member 4 of the writing tool 1. In FIG. 2, the lower part is the front side of the writing tool 1. The friction body 5 is provided on the holding member 4 by fitting, two-color molding, or the like.

The friction body 5 is formed in the shape of a tapered straight-headed triangular pyramid having a substantially triangular cross-sectional shape. Specifically, in the cross section, the vertices of the triangle are formed in a round arc shape, and the radius of curvature of the arc is larger on the rear end side of the friction body 5. The rear end surface 5a of the friction body 5 is formed in a curved surface shape. Therefore, the boundary between the rear end surface 5a and the peripheral surface 5b of the friction body 5 constitutes the ridge line 5c.

In the friction body 5, a wider area can be scraped by using the rear end surface 5a. Further, the friction body 5 can scrape a wider area by using the portion of the ridge line 5c corresponding to the side of the triangle, and by using the portion corresponding to the apex of the triangle, a narrower area can be obtained. Can be scraped. That is, the fact that the friction body has one or more corners (such as the vertices of the above triangle) when viewed from the axial direction is a viewpoint of good scraping of both a wider area and a narrower area. It is advantageous from. As a matter of course, the cross-sectional shape is not limited to a triangle, and may be another polygon such as a quadrangle or a hexagon.

The friction body may be provided not at the rear end portion of the barrel 2 but at another portion of the writing tool 1, for example, the front end portion of the barrel 2 or the clip 7. Further, the friction body may be provided on a heat-discolorable writing instrument other than the knock-type writing instrument as shown in FIG. 1, for example, the rear end of the barrel of the cap-type writing instrument or the top of the cap.

Another aspect of the invention is
A writing instrument set including a writing instrument having a heat-changing ink and a friction body that changes the handwriting of the heat-changing ink by frictional heat.
Provided is a writing tool set in which the friction body is the friction body of the present disclosure.

The friction body of the present disclosure may be provided separately from the writing instrument having the heat-discolorable ink, and may be a writing instrument set including the writing instrument and the friction body. FIG. 3 is a perspective view of a separate friction body 10. In FIG. 3, the friction body 10 has a rectangular parallelepiped shape housed in the case 11, but may be a cube shape or a columnar shape.

[Thermal discoloration ink]
The writing tools of the present disclosure have thermochromic inks. In the present disclosure, the "thermochromic ink" is a different color (second color) when a predetermined color (first color) is maintained at room temperature (for example, 25 ° C.) and the temperature is raised to a predetermined temperature (for example, 60 ° C.). An ink having the property of changing to a color (color) and then returning to the original color (first color) when cooled to a predetermined temperature (for example, -5 ° C) at will. It is possible to design colors according to the application, such as a combination in which one of the first color and the second color is colored and the other is colorless, and a combination in which the first color and the second color are colored.

The thermochromic ink contains a thermochromic colorant. The thermochromic microcapsule pigment used as a thermochromic coloring material is a pigment that changes color due to heat such as frictional heat, for example, if it has a function of changing from colored to colorless, colored to colored, colorless to colored, and the like. The present invention is not particularly limited, and various substances can be used, and examples thereof include microencapsulated heat-discoloring compositions containing at least a leuco dye, a color-developing agent, and a discoloration temperature-adjusting agent.

The leuco dye that can be used is not particularly limited as long as it is an electron donating dye and functions as a color former. Specifically, conventionally known inks such as triphenylmethane type, spiropyran type, fluorane type, diphenylmethane type, rhodamine lactam type, indrill phthalide type, and leucooramine type are used from the viewpoint of obtaining an ink having excellent color development characteristics. It can be used alone (1 type) or in combination of 2 or more (hereinafter, simply referred to as "at least 1 type").

The color developer that can be used is a component having an ability to develop the color of the leuco dye, and is, for example, a phenol resin compound, a salicylic acid metal chloride, a salicylic acid resin metal salt compound, a solid acid compound, or the like. Can be mentioned.

The amount of the developer to be used may be arbitrarily selected according to the desired color density, and is not particularly limited, but is usually 0.1 to 1 part by mass with respect to 1 part by mass of the above-mentioned leuco dye. It is preferable to select within the range of about 100 parts by mass.

The color change temperature adjusting agent that can be used is a substance that controls the color change temperature in the coloration of the leuco dye and the color developer. As the discoloration temperature adjusting agent that can be used, conventionally known ones can be used. Specific examples thereof include alcohols, esters, ketones, ethers, acid amides, azomethins, fatty acids, hydrocarbons and the like.

The amount of the discoloration temperature adjusting agent used may be appropriately selected depending on the desired hysteresis width, the color density at the time of color development, and the like, and is not particularly limited, but is usually, with respect to 1 part by mass of the leuco dye. It is preferably used within the range of about 1 to 100 parts by mass.

The thermochromic microcapsule pigment is obtained by microencapsulating a thermochromic composition containing at least the leuco dye, a color developer, and a color change temperature adjusting agent so that the average particle size is 0.2 to 3 μm. Can be manufactured. Examples of the microencapsulation method include an interfacial polymerization method, an interfacial polycondensation method, an insitu polymerization method, an in-liquid curing coating method, a phase separation method from an aqueous solution, a phase separation method from an organic solvent, a melting dispersion cooling method, and an air vapor. Examples thereof include a suspension coating method and a spray drying method, which can be appropriately selected depending on the intended use.

The contents of these leuco dyes, color developeres, and color change temperature adjusters vary depending on the leuco dye, color developer, type of color change temperature adjuster, microencapsulation method, etc. used. The color-developing agent is 0.1 to 100 and the discoloration temperature adjusting agent is 1 to 100 in terms of mass ratio. The mass ratio of the capsule membrane agent to the capsule contents is 0.1 to 1.

The thermochromic microcapsule pigment can be obtained by appropriately combining the types and amounts of the leuco dye, the color developer, and the color change temperature adjusting agent to obtain the color development temperature (for example, color development at 0 ° C. or higher) and the decolorization temperature (for example, 0 ° C. or higher) of each color. For example, (decoloring at 50 ° C. or higher) can be set to a suitable temperature, and it is preferable that the color changes from colored to colorless due to the frictional heat given by the friction body of the present disclosure.

In the heat-discolorable microcapsule pigment, the wall film is preferably formed of a urethane resin, a urea / urethane resin, an epoxy resin, or an amino resin from the viewpoint of further improving the drawing density, storage stability, and writability. The thickness of the wall film of the microcapsule coloring material is appropriately determined according to the required strength of the wall film and the drawing density.

In the heat-changing ink, in addition to the above-mentioned heat-changing microcapsule pigment, water as a solvent (tap water, purified water, distilled water, ion-exchanged water, pure water, etc.) as the balance, as well as for each writing tool (for ballpoint pens, Depending on the application (for marking pens, etc.), a water-soluble organic solvent, a thickener, a lubricant, a rust preventive, an antiseptic, an antibacterial agent, etc. can be appropriately contained as long as the effect is not impaired.

A conventionally known method can be adopted for producing a thermochromic ink. For example, in addition to the thermochromic and photochromic microcapsule pigments, a predetermined amount of each component in the aqueous solution is blended. It is obtained by stirring and mixing with a stirrer such as a homomixer or a disper. Further, if necessary, coarse particles in the heat-discolorable ink may be removed by filtration or centrifugation.

The viscosity value of the heat-discolorable ink is preferably 500 to 2000 mPa · s at a shear rate of 3.83 / s and 20 to 100 mPa · s at a shear rate of 383 / s. By setting the viscosity in the above range, it is possible to obtain an ink having excellent writability and stability over time.

The surface tension of the heat-discolorable ink is preferably 25 to 45 mN / m, more preferably 30 to 40 mN / m. Within this range, the balance between the inside of the pen tip and the wettability of the ink becomes appropriate, and it is possible to prevent the occurrence of ink back.

Further details of the thermochromic ink are described in, for example, Japanese Patent Application Laid-Open No. 2015-229708, International Publication No. 2015/033750, and International Publication No. 2011/070966.

Hereinafter, specific embodiments of the present invention will be further described with reference to examples, but the present invention is not limited to the examples.

<Material used>

Ingredient (A)
(A-1) Kuraray Septon 4077 Co., Ltd. (Product name)
SEEPS, mass average molecular weight 330,000
(A-2) Kuraray Septon 4055 Co., Ltd. (Product name)
SEEPS, mass average molecular weight 260,000
(A-3) Kuraray Septon 2005 (trade name)
SEPS, mass average molecular weight 250,000
(A-4) Kraton Polymer Co., Ltd. Kraton G1651H (trade name)
SEBS, mass average molecular weight 260,000
(A-5) Kuraray Septon V9461 Co., Ltd. (Product name)
SEEPS with styrene replaced by p-methylstyrene, mass average molecular weight 300,000
(A-6) Kuraray Septon V9827 Co., Ltd. (Product name)
SEBS with styrene replaced by p-methylstyrene, mass average molecular weight 90,000
(A-7) Kuraray Septon 4033 Co., Ltd. (Product name)
SEEPS, mass average molecular weight 100,000
(A-8) Dow Chemical Co., Ltd. Engage EG8100 (trade name)
Ethylene-α-olefin copolymer system Elastomer

Ingredient (B)
(B-1) SunAllomer Ltd. VS200A (trade name)
Propylene homopolymer, MFR 0.5, melting point 165 ° C
(B-2) SunAllomer Ltd. PM940M (trade name)
Propylene-ethylene random copolymer, MFR30, melting point 136 ° C.

Ingredient (C)
(C-1) Idemitsu Kosan Co., Ltd. Dyna Process Oil PW-380 (trade name)
Paraffinic mineral oil

Ingredient (D)
(D-1) Toray Dow Corning Co., Ltd. BY27-001 (Product name)
Silicone compounds (alloy products of polypropylene and ultra-high molecular weight silicone polymers, ultra-high molecular weight silicone polymer ratio 50 wt%)
(D-2) Daikin Industries, Ltd. Neoflon ETFE (trade name)
Fluorine compound (copolymer of tetrafluoroethylene and ethylene)

Ingredient (E)
(E-1) NOF CORPORATION Perhexa 25B (trade name)
Organic peroxide, 2,5-dimethyl-2,5-di- (tert-butylperoxy) hexane

Ingredient (F)
(F-1) Nihon Kasei Corporation TAIC (trade name)
Triallyl isocyanurate

<Making a friction body>
The material composition containing the components shown in Table 1 was kneaded with a twin-screw extruder to obtain a friction body.

<Evaluation>
(Mass average molecular weight of elastomer component)
The mass average molecular weights of (A-1) to (A-7) were measured by gel permeation chromatography (manufactured by JASCO Corporation, high-speed liquid chromatography system "LC-2000Plus (trade name)") using chloroform as a mobile phase. Obtained in terms of standard polystyrene.

(Evaluation of friction body)
Compressive permanent strain Compliant with JIS K6262-2013, a small test piece is prepared from a 6.3 mm thick press sheet, and compression permanent strain at 70 ° C. × 22 hours and 120 ° C. × 72 hours at a compressibility of 25%. Was measured.

Shore A hardness According to JIS K 6253-3-2012, a 6.3 mm thick press sheet was measured after 15 seconds using a durometer type A.

Discoloration property A sample piece obtained by uniformly stretching the heat discoloration ink with a bar coater (No. 6 manufactured by Yasuda Seiki Co., Ltd.) on the test paper specified in ISO127571 was prepared. After the sample piece was sufficiently dried, the friction body was brought into contact with the paper surface at 60 degrees, and the paper surface was rubbed back and forth while maintaining a speed of about 8 to 10 m / sec under a load of 5N. Then, the scraped portion was measured for contamination grade Ns value with a spectrocolorimeter (SC-P manufactured by Suga Test Instruments Co., Ltd.), and the discoloration property was evaluated according to the following criteria.
⊚: Ns value 4.0 or more ○: Ns value 3.0 or more and less than 4.0 Δ: Ns value 2.0 or more and less than 3.0 ×: Ns value less than 2.0

Stain resistance The friction body is pressed against the paper surface (test paper specified in ISO127571) at an angle of 60 to 90 degrees, and a speed of about 8 to 10 m / sec is maintained under a load of about 15 to 20 N. In this state, the contamination test was conducted by a method of rubbing back and forth and confirming that there was no residue on the paper surface or damage of the paper surface itself, and the contamination resistance was evaluated according to the following criteria.
◎: No residue or destruction of the paper surface is seen on the paper surface ○: Only a small amount of residue or destruction of the paper surface is seen on the paper surface ×: Adhesion of residue on the paper surface or the paper surface itself Destruction is seen

The friction body of the present disclosure is suitably used in a writing tool or a writing tool set configured to discolor a heat-discolorable handwriting by frictional heat.

1 Writing instrument 2 Axle cylinder 3 Writing part 4 Holding member 5 Friction body 6 Cover member 7 Clip 10 Friction body 11 Case

Claims (7)

A friction body that discolors an image with thermal discoloration by frictional heat.
Styrene-ethylene-propylene-styrene (SEPS) with styrene replaced with p-methylstyrene, styrene-ethylene-ethylene-propylene-styrene (SEEPS) with styrene replaced with p-methylstyrene and styrene replaced with p-methylstyrene Contains styrene-based elastomers selected from the group consisting of styrene-ethylene-butadiene-styrene (SEBS) .
Compressive set at 120 ° C.: 80% or less, and Shore A hardness: 60-98,
Has a friction body. The friction body according to claim 1, wherein the ratio (A) / (B) of the compression set (A) at 120 ° C. to the compression set (B) at 70 ° C. is 1.0 or more and 1.7 or less. The friction body according to claim 1 or 2, wherein the styrene-based elastomer has a mass average molecular weight of 150,000 to 500,000. The friction body according to any one of claims 1 to 3 , wherein the styrene-based elastomer is crosslinked. The friction body according to any one of claims 1 to 4 , which contains 0.1 to 3.0% by mass of a lubricant. A writing tool having a heat-changing ink and a friction body that changes the handwriting of the heat-changing ink by frictional heat.
A writing tool, wherein the friction body is the friction body according to any one of claims 1 to 5 . A writing instrument set including a writing instrument having a heat-changing ink and a friction body that changes the handwriting of the heat-changing ink by frictional heat.
A writing tool set in which the friction body is the friction body according to any one of claims 1 to 5 .

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