JP7309397B2 - Grip material for writing instrument and manufacturing method thereof - Google Patents

Description

TECHNICAL FIELD The present invention relates to a writing instrument grip material suitable for use as a grip material for a portion (gripping portion) for gripping a writing instrument , and a method for manufacturing the same.

2. Description of the Related Art Conventionally, in writing instruments, a grip material made of a soft material such as rubber is fitted to the grip part in order to prevent the grip part from slipping and the fingers from hurting when writing for a long time. It has been known.
As a grip material for this writing instrument, it is known that a soft material such as silicone rubber, EPDM, or NBR is attached to the concave part of a barrel made of hard resin, or a thermoplastic elastomer is integrally formed in the concave part by two-color molding. It is As for the hardness of the grip material, a rubber hardness (JIS K 6253) of 30 or less gives a slightly sticky feel, and a rubber hardness (JIS K 6253) of 90 or more gives a too hard feel. ) is known to be used in the range of 40 to 90.

For example, in Patent Document 1, Shore high HDA (JIS K 7215 A type) is 3 to 95, and it is selected from the group consisting of polyurethane thermoplastic elastomer, polyester thermoplastic elastomer and polyethylene synthesized with metallocene catalyst. 100 parts by weight of a thermoplastic resin, 0.1 to 20 parts by weight of silicone oil with a specific range of viscosity (JIS Z 8803), 1 to 50 parts by weight of petroleum resin and / or hydrogenated petroleum resin, Disclosed is a resin composition for a grip material for a writing instrument, which has excellent grip properties and good moldability.
In addition to Patent Document 1, many examples of urethane-based resins as materials for grips for writing instruments have been disclosed in addition to this document. In this patent document 1, silicone oil is added as an essential component to ensure surface lubricity, and it is described that if the amount added is too large, there is a risk of bleeding out (paragraph [0016]). ~[0018]).

Patent Document 2 discloses a multi-layer writing instrument grip in which a thermoplastic elastomer having a high durometer hardness is arranged on the outside and a thermoplastic elastomer having a low durometer hardness is arranged on the inside (claim , paragraphs [0003] to [0008], etc.). It is described that the thermoplastic elastomer having a low durometer hardness used for the inner layer of this writing instrument grip has a gel-like consistency (paragraph [0007]). Therefore, this multi-layered grip for writing instruments does not always retain the same shape, and has a so-called "squishy" feel, and the hardness of the writing instrument shaft further inside the inner layer is transmitted to the fingers. , There are disadvantages such as the vibration during writing being transmitted to the hand.

Patent Document 3 discloses that even if oil adheres to the surface of the barrel, it is possible to prevent fingers from slipping when gripping the barrel and to prevent the surface of the barrel from becoming dirty with oil. In order to provide a writing instrument with a There is disclosed a writing instrument characterized by having a porous oil-adsorbing portion provided thereon. This grip for a writing instrument is composed of a polyurethane open-cell foam obtained by reactive curing of a polyol component, a polyisocyanate component, and a plasticizer. In this patent document 3, in order to prevent oil from sticking to fingers, the oil is adsorbed to the internal oil adsorption part through the communicating pores provided in the grip, and the progression of oil stains on the grip surface is delayed.
However, as described in this Patent Document 3, the adsorption of oil eventually reaches saturation, and over time, it becomes very inferior in terms of appearance and hygiene. In addition, there is a problem that tan δ (loss tangent) fluctuates due to the use of a foam, which affects the feeling of touch and fatigue.

Japanese Patent Application Laid-Open No. 2007-231280 (Claims etc.) Japanese Patent Application Laid-Open No. 2007-90823 (Claims, etc.) Japanese Patent Application Laid-Open No. 2018-69607 (Claims, etc.)

The inventors of the present invention have attempted to solve the above-mentioned problems of the conventional art. To provide a grip material for a writing utensil which has a repulsive force for facilitating writing, has a good feel in gripping, and is free from stickiness and finger pain, and to provide a method for producing the grip material.

As a result of intensive studies on the above-mentioned conventional problems, the present inventors have found that at least a prepolymer obtained by reaction of a polyol component and a polyisocyanate component and a material containing a curing agent are blended. The present inventors have found that the grip material for writing instruments and the method for producing the same can be obtained by including a polyether-based urethane elastomer, and have completed the present invention.

That is, the grip material for a writing instrument of the present invention is a grip material for a writing instrument used for a grip portion of a writing instrument, the grip material for a writing instrument being composed of at least two layers, the inner layer being composed of at least a polyol component and a polyisocyanate component. Composed of a urethane elastomer obtained by blending a material containing a prepolymer obtained by reaction, a curing agent, and a tackifier, and an outer layer at least obtained by reacting a polyol component and a polyisocyanate component. It is characterized by containing a polyether-based urethane elastomer obtained by blending a material containing a prepolymer and a curing agent, and being a dense body.
The tackifier is preferably a secondary or tertiary higher monoalcohol.
The urethane elastomer surface of the inner layer is preferably decorated.
At least one of vapor deposition, printing, painting, and transfer is preferably applied as the decoration.
A method for producing a writing instrument grip material of the present invention is a writing instrument grip material used in a grip portion of a writing instrument, the grip material comprising at least a prepolymer obtained by reacting a polyol component and a polyisocyanate component, and a curing agent. and a tackifier, and after disposing a urethane elastomer obtained by blending a material containing a tackifier and decorating the surface of the urethane elastomer, the surface of the decor is coated with at least a polyol component and a polyisocyanate component by reaction. It is characterized by disposing a polyether-based urethane elastomer obtained by blending a material containing the obtained prepolymer and a curing agent.
At least one of vapor deposition, printing, painting, and transfer is preferably applied as the decoration.

According to the present invention, the vibration of the pen body during writing is not transmitted to the hand, and the pen body has a repulsive force that makes it easy to write with respect to the amount of deformation adapted to the grip condition, and the grip feels good and is not sticky. To provide a grip material for a writing instrument which does not cause pain in the fingers.
According to the manufacturing method of the present invention, it is possible to efficiently decorate the grip material for writing instruments, prevent the vibration of the pen from being transmitted to the hand during writing, and adjust the amount of deformation adapted to the grip of the pen. It is possible to manufacture a grip member for a writing instrument which has a repulsive force that makes it easy to write with the body, has a good feel when gripped, and is not sticky or painful to the fingers.

BRIEF DESCRIPTION OF THE DRAWINGS It is a perspective view which shows an example of embodiment of the grip material for writing instruments of this invention. FIG. 4 is a vertical cross-sectional view showing another example of the embodiment of the writing instrument grip material of the present invention. FIG. 4 is a vertical cross-sectional view showing an example of a mechanical pencil to which another example of an embodiment of the writing instrument grip material of the present invention is attached.

Hereinafter, embodiments of the present invention will be described in detail for each invention.
<Writing instrument grip material composition>
The writing instrument grip material composition of the present invention (hereinafter simply referred to as "grip material composition") comprises at least a prepolymer obtained by reacting a polyol component and a polyisocyanate component, and a curing agent. It is characterized by being a dense body containing the polyether-based urethane elastomer obtained by the above.
A "dense body" as defined in the present invention does not include foams, hollow bodies, etc., and means a matte, plasticizer-free bulk.
Since the grip material composition of the present invention is used as a grip material for writing instruments, the rubber hardness [Type A durometer (Asker A type) in accordance with JIS K 6253-3:2012, the same applies hereinafter] is 10 to 60. It is desirable to adjust the type of prepolymer and the amount of each component thereof, the type of curing agent and the amount thereof, etc. so as to fall within the range.

The polyether-based urethane elastomer used in the grip material composition of the present invention is obtained by blending a material containing at least a prepolymer obtained by reacting a polyol component and a polyisocyanate component, and a curing agent.
The polyol component to be used is preferably a polyol having an average functional group number of 2.5 or more and 3.5 or less and an average molecular weight of 350 or more and 1,500 or less, more preferably a hydrophobic polyol having an active hydroxyl group at the end. Mixtures and the like are desirable. If the average number of functional groups exceeds 3.5, the rubber hardness of the grip material increases, which is somewhat undesirable from the standpoint of impact absorption. On the other hand, when the average number of functional groups is less than 2.5, the rubber hardness becomes small, and the stickiness cannot be suppressed completely, resulting in a poor grip feeling and stickiness. On the other hand, if the average molecular weight is less than 350, the rubber hardness increases, which is not preferable from the viewpoint of impact absorption. On the other hand, if the average molecular weight exceeds 1,500, the rubber hardness becomes lower, and the feel of the grip is good, but stickiness will occur.

Specific polyol components that can be used include castor oil-based polyols: lactone-based polyols such as ε-caprolactone-based polyols and β-methyl-δ-valerolactone-based polyols; and carbonate-based polyols. single or a mixture of one or more).
In addition, other polyols may be used as the polyol component as long as the above properties can be secured. Examples thereof include polyoxypolyalkylene polyols, and those obtained by ring-opening addition polymerization of alkylene oxides using water, polyhydric alcohols such as ethylene glycol and glycerin as initiators, and the like can be used.

The grip material composition of the present invention preferably does not contain additives such as secondary or tertiary higher monoalcohols. When these additives are added, tackiness is imparted, resulting in stickiness and a poor grip feeling. Therefore, it is desirable not to add not only additives (tackifiers) such as secondary or tertiary higher monoalcohols but also additives used for softening resins called so-called plasticizers (softeners).

The polyisocyanate component to be used is a derivative compound having an average functional group number of 2.3 or more and 3.5 or less and having an active isocyanate group at the end, which is obtained from the reaction of an alicyclic polyisocyanate compound or derivative compound thereof. If the average number of functional groups is less than 2.3, the rubber hardness of the grip material becomes small, and the tackiness of the grip material cannot be suppressed, resulting in a poor grip feeling and stickiness. On the other hand, if the average number of functional groups exceeds 3.5, the rubber hardness of the grip material increases, which is not preferable in terms of impact absorption.

Specific polyisocyanate components to be used include, for example, aliphatic isocyanates, alicyclic isocyanates, or organic polyisocyanates composed of prepolymers of terminal isocyanates having reactivity with active hydrogen groups derived therefrom.
Examples of the aliphatic isocyanate include norbornene diisocyanate (NBDI), a derivative derived from hexamethylene diisocyanate (HDI). As a derivative derived from HDI, a compound having three isocyanate groups (average functionality: 3) at the terminal, such as a trimer, an adduct with glycerin, an allophanate cross-linked product, a burette cross-linked product, etc. can be used. Specific trade names include, for example, Duranate (manufactured by Asahi Kasei Corporation).
Examples of the alicyclic isocyanate include isophorone diisocyanate (IPDI), cyclohexyl diisocyanate, hydrogenated diphenylmethane diisocyanate, and the like, and these have two functional groups. Therefore, these are used by mixing with a compound having 3 or more functional groups.

In the present invention, polyisocyanate is reacted with less than the theoretical amount of the polyol component using known techniques, and used as a prepolymer having active isocyanate groups at its ends. The term "prepolymer" as used herein refers to a compound having an active isocyanate group at its end obtained by reacting polyisocyanate with less than the theoretical amount of the polyol component using a known technique.
The advantage of using it as a prepolymer is that the reaction between the polyol and the polyisocyanate tends to proceed reliably, and a homogeneous gripping material composition can be easily obtained. In these prepolymers, the residual amount of active isocyanate groups at the terminals is 2% by mass or more, preferably 2.5 to 15% by mass, relative to 100% by mass of the entire prepolymer. . If the residual amount of terminal active isocyanate groups is less than 2% by mass, the liquid viscosity of the prepolymer becomes high, which causes problems in the production of the grip material composition. If the residual amount of terminal active isocyanate groups is 2% by mass or more, there is no particular problem, but if it exceeds 15% by mass, the effect of use as a prepolymer is reduced.

In addition, other polyisocyanates may be mixed with the polyisocyanate component as long as the effects of the present invention are not impaired. Other polyisocyanates include, for example, tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), liquid modified MDI, and xylidene diisocyanate (XDI).

The curing agent (or cross-linking agent) to be used is not particularly limited, and examples thereof include amine curing agents (amine compounds), alcohol curing agents, epoxy curing agents (polyepoxy compounds), amino resin curing agents (melamine compounds, guanamine compounds, etc.), dihydrazide-based curing agents, carbodiimide-based curing agents, oxazoline-based curing agents, aziridine-based curing agents, and the like.

Examples of amine-based curing agents include diamines {e.g., alkanediamines (e.g., ethylenediamine, propylenediamine, hexamethylenediamine, 1,2-diaminoethane, 1,2-diaminopropane, 1,3-diaminopentane, 1,3-diaminopentane, aliphatic diamines such as C1-10 alkanediamines such as 6-diaminohexane; diaminoarenes (e.g., m-phenylenediamine, diamino C6-10 arenes such as diaminotoluene), bis(aminoaryl)alkanes [ For example, bis-(4-aminophenyl)methane, bis-(4-amino-3-chlorophenyl)methane (or 3,3′-dichloro-4,4′-diaminodiphenylmethane or methylenebis(2-chloroaniline), MOCA ) and other bis(aminophenyl)alkanes (e.g., optionally substituted bis(aminophenyl)C1-10 alkane, preferably bis(aminophenyl)C1-6alkane), etc.] Low molecular weight diamines such as diamines (or diamines having an aromatic skeleton)}, polyamines having three or more amino groups (e.g., diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, 2,2' alkanolamines (ethanolamine, diethanolamine, etc.); aminobenzoate curing agents [e.g., alkylenebis(aminobenzoates) (e.g., trimethylenebis(4- C2-6 alkylene bis (aminobenzoate) such as aminobenzoate), polyalkylene oxide-bis (aminobenzoate) (for example, poly tetramethylene oxide-di-p-aminobenzoate and other poly C2-6 alkylene oxide- bis(aminobenzoate), etc.)].

As alcohol-based curing agents (polyhydric alcohol-based curing agents), diols, polyols (especially low-molecular weight compounds) having 3 or more (for example, about 3 to 8) hydroxyl groups in the molecule, and the like can be used. Diols include alkanediol (C2-10 alkanediol such as ethylene glycol, propylene glycol, 1,4-butanediol, pentanediol, hexanediol, preferably C2-6 alkanediol, more preferably C2-4 alkanediol, ), di- or trialkanediols (eg, diethylene glycol, triethylene glycol, etc.), alkylene oxide adducts of bisphenols (bisphenol A, etc.) or hydrogenated bisphenols (hydrogenated bisphenol A, etc.). Examples of the polyols include triols (alkanetriols such as glycerin, trimethylolethane, trimethylolpropane, hexanetriol, triethanolamine, etc.), tetraols (e.g., pentaerythritol, diglycerin, methylglucide, etc.). codite, etc.), pentaols (xylitol, etc.), hexaols (sorbitol, mannitol, dipentaerythritol, etc.), octools (sucrose, etc.), and the like. Also, about 1 to 2 mol of C2-4 alkylene oxide (ethylene oxide, etc.) may be added to the hydroxyl group of these compounds. Furthermore, as alcohol-based curing agents, for example, C2-4 alkylene oxide adducts of alkylenediamine (ethylene oxide adducts of C2-6 alkylenediamines such as ethylenediamine and propylenediamine) can also be used. These alcohol-based curing agents can be used alone or in combination of two or more.
The alcohol-based curing agent (polyhydric alcohol) may have a molecular weight of, for example, 60 to 350, preferably 70 to 300, more preferably 80 to 250 (eg, 85 to 200).

Preferred curing agents include amine-based curing agents, alcohol-based curing agents, and the like. When an amine-based curing agent and another curing agent (for example, an alcohol-based curing agent) are combined, the ratio of the other curing agent (especially an alcohol-based curing agent) to the total curing agent is 1 to 50 mol% ( For example, 2 to 40 mol %), preferably 3 to 35 mol % (eg, 5 to 30 mol %), more preferably 5 to 25 mol % (eg, 8 to 20 mol %).
The ratio of the curing agent (e.g., amine-based curing agent alone, amine-based curing agent and alcohol-based curing agent) to the prepolymer described later is, for example, the active hydrogen atoms of the curing agent (e.g., Amino group hydrogen atom, amino group hydrogen atom and hydroxyl group hydrogen atom) 0.7 to 1.2 equivalents, preferably 0.8 to 1.1 equivalents, more preferably about 0.9 to 1.0 equivalents may be

A urethanization catalyst can be used for the urethanization reaction (curing reaction) between the polyisocyanate component and the polyol component. As this urethanization catalyst, for example, a known catalyst such as a tertiary amine compound or an organometallic compound can be used. Specifically, triethylenediamine, N,N'-dimethylhexamethylenediamine, N,N'-dimethylbutanediamine, diazabicyclo(5,4,0)undecene-7 (DBU) and DBU salts, lead octylate, lauryl Dibutyltin acid, bismath tris(2-ethylhexanoate), diisopropoxybis(ethylacetoacetate)titanium and the like are suitable.

Furthermore, in addition to the polyol component, the polyisocyanate component, and the curing agent, the mixed solution contains other components within a range that does not impair the effects of the present invention, such as the required strength and durability. good too. As other components, heat stabilizers, antioxidants, UV absorbers, UV stabilizers, etc. may be used singly or in combination of two or more. Furthermore, pigments, dyes, flame retardants, antifoaming agents, dispersing agents, surfactants, moisture adsorbents, etc. may be added as appropriate in addition to those mentioned above.

When the polyol component and the polyisocyanate component are chemically reacted, the equivalent ratio of the isocyanate group (NCO) of the isocyanate to the hydroxyl group (OH) of the polyol, ie, NCO/OH, is not particularly defined, but is 0.5. 7 to 1.05 are preferred. If the equivalent ratio exceeds 1.05, the rubber hardness of the obtained grip material composition becomes too high, which is not preferred. In addition, during the reaction of the gripping material composition to form a cured product, carbon dioxide gas, which is a by-product, generates air bubbles, and the gas impairs the appearance of the cured product, which is not preferable. On the other hand, if the equivalent ratio is less than 0.7, the resulting grip material composition will have low hardness, lacking in performance stability and heat resistance, which is not preferable.

In the grip material composition of the present invention, the prepolymer obtained by the reaction of the polyol component and the polyisocyanate component and a material containing a curing agent are mixed at room temperature, preferably pre-defoamed polyether under vacuum. A system urethane elastomer composition is prepared. Here, when mixing the catalyst and other additives, they may be added at the same time as mixing. This polyether-based urethane elastomer composition is poured into a mold for grip materials for writing instruments of various shapes and structures adjusted to room temperature to 120°C, and allowed to undergo a urethanization reaction at room temperature to 120°C for 1 to 10 hours. . After that, the grip material for a writing instrument is obtained by removing it from the mold.

As described above, the grip material composition of the present invention is a polyether-based urethane elastomer obtained by blending a material containing a prepolymer obtained by the reaction of the polyol component and the polyisocyanate component, and the curing agent. and is characterized by being a dense body.
The obtained grip material composition (sheet body: 27 × 27 mm, the same applies hereinafter) has a shock absorption rate of more than 80% between 1 mm and 2 mm in thickness, and when the thickness exceeds 3 mm, the impact is almost 100%. It was confirmed that the absorptivity was obtained. The "shock absorption rate" defined in the present invention was calculated based on the value measured by a load cell after a hard ball (64 g, φ25 mm) was allowed to drop naturally onto a 10 mm test piece from a height of 150 mm. .
In addition, the obtained grip material composition (sheet body) has strong durability even when bending motion is performed for a long period of time, and also has durability against tearing in the lateral direction, and the grip It has been confirmed that it responds well to the expansion and contraction of time.
Furthermore, the resulting grip material composition (sheet body) has a high coefficient of restitution (shock absorption rate), low hardness and low tan δ, and can permanently exhibit these properties. (non-foaming), and it was confirmed that it was not sticky.

<Grip material for writing instruments and manufacturing method thereof>
The writing instrument grip material (A) of the present invention is a writing instrument grip material used for a grip portion of a writing instrument, and is characterized by using the writing instrument grip material composition having the above constitution. is.
Further, the writing instrument grip material (B) of the present invention is a writing instrument grip material used for a grip portion of a writing instrument, the writing instrument grip material comprising at least two layers, the inner layer comprising at least a polyol component and a polyisocyanate component. It is composed of a urethane elastomer obtained by blending a material containing a prepolymer obtained by the reaction of, a curing agent, and a tackifier, and the grip material composition for writing instruments having the above configuration is used for the outer layer. and

The writing instrument grip material (A) of the present invention uses the writing instrument grip material composition having the above structure, and the type of writing instrument (mechanical pencil, pencil, ballpoint pen, fountain pen, writing brush, calligraphy pen, felt-tip pen, etc., hereinafter the same). If the shape of the gripping portion of is, for example, if the gripping portion has a concave shape and structure, it can be obtained by molding the grip material composition for a writing instrument having the above configuration into a mold having a shape and structure that conforms to the shape and structure, and It can be integrally manufactured by two-color molding together with the barrel of the writing instrument, and furthermore, the grip portion of the writing instrument may be formed by brushing, spray painting, or the like.
FIG. 1 shows a writing instrument grip material X obtained by using the writing instrument grip material composition having the above structure. The writing instrument grip material X has a hollow tubular structure that is detachably fitted on the outer peripheral portion (not shown) of the barrel of the writing instrument. The shape and structure of the writing instrument grip material (A) are not particularly limited as long as the effects of the present invention are achieved, and writing instrument grip materials having various shapes and structures are molded according to the types of writing instruments. is.

The writing instrument grip material (A) obtained by the present invention has a rubber hardness in the range of 10 to 60, is dense, and does not have tackiness.
As described above, the thickness of the writing instrument grip material (A) depends on the point that the impact absorption rate exceeds 80% at a thickness of 1 mm, the type of writing instrument, the outer shape of the grip part, the outer peripheral length (very thick diameter), etc. Although it varies, it is desirable that the thickness (wall thickness) at the grip portion is 1 mm or more, preferably 1 to 3 mm.
The grip material (A) for a writing instrument having the above-mentioned characteristics, which is configured in this manner, does not transmit the vibration of the pen body during writing to the hand, and the pen body is easily repelled against the amount of deformation adapted to the grip condition. To provide a gripping material for a writing instrument which is strong, has a good feel when gripped, is not sticky or causes finger pain, is soft, and is free from changes such as swelling due to sebum or the like.
In addition, although the reason is not clear, the writing instrument grip material (A) does not easily peel off even if printing is applied to its surface, and the printed contents can be discriminated without problems even after long-term use.

Next, in the writing instrument grip material (B) of the present invention, the writing instrument grip material used for the grip portion of the writing instrument is composed of at least two layers, and the inner layer contains at least a polyol component and a polyisocyanate component. It is composed of a urethane elastomer obtained by blending a material containing the obtained prepolymer, a curing agent, and a tackifier, and uses the grip material composition for a writing instrument having the above-described structure for the outer layer.
In the writing instrument grip material (B) of the present invention, the polyol component used in the inner layer includes a polyol having a functional group number of 2.4 or more and 3.0 or less and a weight average molecular weight of 3,000 to 6,000.
If the number of functional groups exceeds 3.0, the rubber hardness of the grip material increases, and the adhesiveness tends to be insufficient. On the other hand, if the number of functional groups is less than 2.4, the composition tends to be uncured. On the other hand, if the average molecular weight is less than 3000, the rubber hardness becomes too high and the adhesiveness becomes too low. On the other hand, if the average molecular weight exceeds 6,000, the reaction will not proceed sufficiently.
Examples of polyol components used in such an inner layer include polyoxypolyalkylene polyols. This polyoxypolyalkylene polyol can be obtained by ring-opening addition polymerization of alkylene oxide using water or a polyhydric alcohol such as ethylene glycol or glycerin as an initiator.

In addition, the above polyol component may contain other polyols as long as the above properties can be ensured. For example, at least one of known polyester-based polyols, polytetramethylene polyoxyglycol, castor oil-based polyol, ε-caprolactone-based polyol, β-methyl-δ-valerolactone-based polyol, carbonate-based polyol, etc. mixtures of the above).

Further, a secondary or tertiary higher monoalcohol may be added to the polyol component used in the inner layer in order to impart adhesiveness to the urethane elastomer. It is preferably soluble in the polyol that is the main component of the polyol component. Examples include 2-ethylhexyl alcohol, sec-stearyl alcohol, α-terpineol, diacetone alcohol and capryl alcohol. It should be noted that primary higher alcohols are not expected to have much of an effect of improving adhesiveness.
The amount of these higher monoalcohols used is 0.5 to 10 parts by mass of the higher monoalcohol for 99.5 to 90 parts by mass of the main component polyol out of 100 parts by mass of the total amount of the polyol components. A range is preferred. When the amount of the higher monoalcohol used is less than 0.5 parts by mass, the tackiness of the obtained urethane elastomer becomes insufficient. On the other hand, when it exceeds 10 parts by mass, the average number of functional groups of the polyol component is lowered, and the durability of the urethane elastomer may become insufficient.

In the writing instrument grip material (B) of the present invention, the polyisocyanate that is the main component of the polyisocyanate component used has two or more isocyanate groups that react with the hydroxyl groups of the polyol component. Examples include at least one of tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), liquid modified MDI, xylidene diisocyanate (XDI), hexamethylene diisocyanate (HDI), cyclohexyl diisocyanate and isophorone diisocyanate.
The gripping material (B) for writing instruments of the present invention is used as a prepolymer having active isocyanate groups at its terminals by reacting an isocyanate component with the polyol component in a less than theoretical amount using a known technique.
The advantage of using it as a prepolymer is that the reaction between the polyol and the polyisocyanate proceeds reliably and easily, and a homogeneous grip material composition for the inner layer can be easily obtained. In these prepolymers, the residual amount of active isocyanate groups at the terminals is 2% by mass or more, preferably 2.5 to 15% by mass, relative to 100% by mass of the entire prepolymer. . If the residual amount of terminal active isocyanate groups is less than 2% by mass, the liquid viscosity of the prepolymer becomes high, which causes problems in the production of the grip material composition for the inner layer. If the residual amount of terminal active isocyanate groups is 2% by mass or more, there is no particular problem, but if it exceeds 15% by mass, the effect of use as a prepolymer is reduced.

In the writing instrument grip material (B) of the present invention, when the polyol component and the polyisocyanate component that form the inner layer are chemically reacted, the equivalent ratio of the isocyanate group (NCO) of the isocyanate to the hydroxyl group (OH) of the polyol, that is, NCO/ OH is preferably 0.95 to 1.05. If this equivalent ratio exceeds 1.05, the resulting composition will have poor tackiness and it will be difficult to obtain a composition with stable rubber hardness. Unfavorable because it lacks sexuality.

Here, in carrying out the urethanization reaction between the polyol component and the polyisocyanate component, an appropriate urethanization catalyst can be used as necessary. As this urethanization catalyst, it is possible to use a known catalyst such as a tertiary amine compound or an organometallic compound. Suitable examples include triethylenediamine, N,N'-dimethylhexamethylenediamine, N,N'-dimethylbutanediamine, lead octylate, and dibutyltin laurate. However, using this urethanization catalyst is not an essential requirement.
Further, since the curing agent to be used is the curing agent described in detail in the above-mentioned grip material composition for writing instruments, the explanation thereof is omitted.

Further, such a gripping material composition for inner layer can be used as it is as the urethane prepolymer, but the following components may be added.
In order to improve the durability and stability of the urethane prepolymer, stabilizers such as heat stabilizers, antioxidants, ultraviolet absorbers, ultraviolet stabilizers, fillers, etc., are added to the extent that the effects of the present invention are not impaired. WHEREIN: You may use 1 type or in mixture of 2 or more types. In addition, pigments, dyes, flame retardants, antifoaming agents, dispersants, surfactants, moisture adsorbents, etc. can be added as appropriate.

In the writing instrument grip material (B) of the present invention, the above-mentioned polyol component and polyisocyanate component used as raw materials for the inner layer are mixed at room temperature or in a heated state. When the additive is mixed, it may be mixed with the polyol component in advance, or may be added when the main component is mixed.

In the writing instrument grip material (B) of the present invention, the writing instrument grip material is composed of at least two layers. and a tackifier, and the above-described writing instrument grip material composition is used for the outer layer. If the portion has a concave shape and structure, the composition for the inner layer is put in a mold having a shape and structure that conforms to the shape and structure at a predetermined rate for a predetermined time to mold the sticky inner layer grip material for writing instruments. It is obtained by putting the above-mentioned writing instrument grip material composition for the outer layer in a predetermined ratio for a predetermined time and integrally molding it, and integrally by two-color molding together with the barrel of the writing instrument (at least two layers of writing instrument grip material ), and after molding the inner layer of the writing instrument grip material, at least two layers of the writing instrument grip material may be molded by brushing or spray coating.

In addition, in the writing instrument grip material (B) of the present invention, after the inner layer of the writing instrument grip material of the present invention is molded, the surface of the inner layer of urethane elastomer is decorated, for example, using metal powder, pigment, dye, etc., vapor deposition, At least one of printing (offset printing, pad printing, silk printing, inkjet printing, etc.), painting, and transfer can be applied to form decorations (patterns, emblems, etc.) on the surface. Further, like the grip material (A), the surface of the outer layer may be printed.
In the writing instrument grip material (B) having this configuration, the inner layer of the grip material is blended with a material containing at least a prepolymer obtained by reaction of a polyol component and a polyisocyanate component, a curing agent, and a tackifier. After disposing the urethane elastomer obtained by the above-described decoration on the surface of the urethane elastomer, the above-described grip material composition for writing instruments, that is, at least the polyol component and the polyisocyanate component are reacted on the decorated surface. It is obtained by disposing a polyether-based urethane elastomer obtained by blending a material containing the obtained prepolymer and a curing agent.
Furthermore, in the above embodiment, a two-layer (inner layer, outer layer) structure is shown, but it may be a three-layer structure or more having an inner layer, an intermediate layer, and an outer layer, and the grip material composition described above is formed on the outer layer. A urethane elastomer obtained by compounding a material containing a prepolymer obtained by the reaction of at least the above-mentioned polyol component and a polyisocyanate component, a curing agent, and a tackifier in the intermediate layer or inner layer. Three or more layers may be used as long as the structure is arranged.

An embodiment of this writing instrument grip material (B) and a mechanical pencil 10 to which the writing instrument grip material (B) is attached will be further described with reference to FIGS. 2 and 3. FIG.
In this embodiment, as shown in FIGS. 2 and 3, the gripping portion 17 of the mechanical pencil as the writing instrument 10 is a writing instrument grip material (B) 20 as described below.
The shaft tube 11 is composed of two parts, a core shaft 13 arranged on the front end side in the axial direction and a rear shaft 12 arranged on the rear end side. The core shaft 13 and the rear shaft 12 are fixed to each other by screwing to form the shaft tube 11 .
The core shaft 13 has a cylindrical shape made of stainless steel. Inside the core shaft 13, a core 19 as an application body is accommodated.
The outer peripheral surface of the core shaft 13 is covered with an inner cover 21 . The inner cover 21 is made of white silicone and is formed on the surface of the stainless steel core shaft 13 by insert molding. The inner cover 21 slightly expands in diameter from the front end to the rear end. As a result, the mold can be drawn and tapered.
As shown in FIG. 2 , the writing instrument grip material (B) 20 is provided with an outer layer 23 so as to cover the inner cover 21 . An annular protrusion 24 is provided on the inner surface of the front end portion of the outer layer 23 and is brought into contact with the tip portion of the inner cover 21 . Furthermore, the inner surface of the rear end portion is centered by contacting the peripheral edge of the centering member 22 of the inner cover 21 . The outer circumference of the rear end portion of the outer layer 23 has a reduced outer diameter, and a ring member 18 that contacts the front end of the rear axle 12 is attached to this portion.
On the other hand, the front end of the core shaft 13 is not covered with the inner cover 21, and the front threaded tube 14 is mounted thereon. Then, as shown in FIG. 2, a mouthpiece 16 is screwed onto the front screw tube 14 . Here, the rear end of the mouthpiece 16 is in contact with the front end of the outer layer 23 .

The rear end of the core shaft 13 is also not covered with the inner cover 21, and the rear threaded tube 15 is attached here. Then, as shown in FIG. 3, the rear shaft 12 is screwed onto the rear screw tube 15 .
The space between the inner cover 21 and the outer layer 23 formed by fixing the core shaft 13 and the outer layer 23 via the inner cover 21 is filled with the inner layer 25 without gaps. 23 and inner layer 25 are in close contact.
The writing instrument grip material (B) 20 is obtained by blending a material containing a prepolymer obtained by the reaction of at least the above-described polyol component and polyisocyanate component, a curing agent, and a tackifier in the inner layer 25. After applying a decoration (printing by Mitsubishi Pencil Co., Ltd.) to the surface of the urethane elastomer by printing, the outer layer of the decoration surface is coated with the above-mentioned grip material composition for writing instruments, that is, at least It is obtained by disposing a polyether-based urethane elastomer obtained by blending a material containing a prepolymer obtained by reacting a polyol component and a polyisocyanate component with a curing agent.

The writing instrument grip material (B) 20 obtained according to the present invention has an overall rubber hardness in the range of 10 to 60, and the outer layer 23 is dense and non-adhesive. In addition, the thickness of the outer layer of the writing instrument grip material (B) varies depending on the type of writing instrument, the outer shape of the grip portion, the outer circumference length (extra-thick diameter), etc., but the thickness (thickness) of the outer layer 23 is 1 mm or more, preferably 1 to 3 mm, and the overall thickness (thickness) of the gripping portion is preferably 1.5 to 5 mm.
Even with the writing instrument grip material (B) having the above-mentioned characteristics, the pen body does not transmit the vibration of the pen body during writing to the hand, and the pen body is moved with respect to the amount of deformation adapted to the grip condition. To provide a grip material for a writing instrument which has a repulsive force that is easy to hold, gives a good grip feeling, is not sticky or hurts the fingers, is soft and does not undergo changes such as swelling due to sebum, etc., and to efficiently produce the grip material. can be obtained.
Further, in the decorated writing instrument grip material (B), since the surface of the inner layer is decorated with a decorative portion, it is possible to obtain an innovatively decorated writing instrument grip material without staining with hands or the like. .

The writing instrument grip material composition, the writing instrument grip material, and the manufacturing method thereof of the present invention are not limited to the above-described embodiments and the like, and can be modified within the scope of the technical ideas of the respective inventions of the present invention.
For example, the entire shaft of the writing instrument may be formed of the grip material (B) according to the present invention, and the entire shaft may serve as a grip without providing any particular grip material. In this case, the inner layer of the grip material (B) is not made of a "soft" material such as urethane elastomer, but is made of a normal "hard" resin material such as PP, thereby ensuring the strength of the writing instrument as a whole. If the "apparent" rubber hardness is within the range of 10 to 60 when the outer layer is thick and gripped, there is no problem in practical use.
In addition, by forming both the grip material (A) and the grip material (B) transparently without adding a coloring material, a writing utensil having a rotation gimmick like a mechanical pencil "Kurtoga" by the applicant of the present application in the vicinity of the grip part. , these grip materials may be configured to cover the rotating gimmick portion.

EXAMPLES Next, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples and the like.

[Examples 1 and 2 and Comparative Examples 1 and 2]
The following raw materials were used.
Polyol component: ring-opening polymerization adduct of glycerin initiator ε-caprolactone (number of functional groups: 3, average molecular weight: 550)
Isocyanate component 1: Trimerized product of hexamethylene diisocyanate (HDI) (number of functional groups: 3), Duranate TLA (manufactured by Asahi Kasei Corporation)
Isocyanate component 2: isophorone diisocyanate (2 functional groups), (IPDI)
Polymerizing agent: dibutyl tin laurate

(Example 1)
As a urethane elastomer, a composition of 100 parts by mass of a polyol component, 38 parts by mass of each of an isocyanate component 1 and an isocyanate component 2, and 0.1 part by mass of a polymerizing agent, was similarly mixed and defoamed to form a pre-curing liquid agent. prepared. This was filled in a mold for molding a grip, the excess liquid was wiped off, and the mixture was cured at a temperature of 23° C. for 3 days. The rubber hardness of this urethane elastomer was 53, and the thickness (wall thickness) of the grip portion was 2.0 mm. "Mitsubishi Pencil Co., Ltd." was further printed on the grip surface by offset printing.

(Comparative example 1)
A mechanical pencil M5-858GG manufactured by Mitsubishi Pencil Co., Ltd. (trade name “Kurtoga <uni-alpha gel-equipped type>”) was used as it was for the evaluation. The grip material has a three-layer structure consisting of an outer layer of silicone rubber, an intermediate layer of impact-absorbing material (trade name “Alpha Gel”), and an inner layer of silicone rubber. The rubber hardness of the surface was 65, and the thickness (wall thickness) of the grip portion was 2.5 mm (outer layer 0.5×intermediate layer 1.0×inner layer 1.0 mm). "Mitsubishi Pencil Co., Ltd." was further printed on the grip surface by offset printing.

Each grip member for writing instruments other than the above comparative examples was fitted into the grip part of a mechanical pencil M5-507GG manufactured by Mitsubishi Pencil, and 10 testers were asked to write continuously for 1 hour. Ease of use, grip feeling, feeling of fatigue, and print peeling after writing were evaluated.
These results are shown in Table 1 below.

(Example 2)
The foamed resin "coat layer" (Advancel (manufactured by Sekisui Chemical Co., Ltd.)) on the surface of a pencil 6903 hexagonal GPST (core hardness 2B) manufactured by Mitsubishi Pencil Co., Ltd. is peeled off, and the composition of Example 1 is sprayed and cured. to produce a pencil with a coated surface. The coating layer had a rubber hardness of 75 and a thickness (thickness) of 0.5 mm. "Mitsubishi Pencil Co., Ltd." was further printed on the surface of this coating layer by offset printing.

(Comparative example 2)
Mitsubishi Pencil 6903 hexagon GPST (core hardness 2B) was used as it was.
10 testers were asked to write continuously for 1 hour with the above two types of pencils, and the following evaluation criteria were used to evaluate ease of writing, grip feeling, fatigue, and print peeling after writing (average value )Did. "Mitsubishi Pencil Co., Ltd." was further printed on the surface of this coating layer by offset printing.

(Evaluation criteria for ease of writing)
○: Almost no friction was felt between the paper surface and the lead, and the writing was smooth.
Δ: Friction between the paper surface and the core was transmitted depending on the writing angle, and vibration was often transmitted to the fingers.
×: The friction between the paper surface and the core was always transmitted, and the vibration was always transmitted to the fingers.

(Evaluation criteria for grip feeling)
◯: The skin always had a dry feeling, and the oil from the fingers did not spread on the surface.
Δ: A feeling of stickiness was produced while writing, and stickiness was observed at the end of writing.
x: It was sticky from the beginning of writing.

(Evaluation Criteria for Feeling of Fatigue)
(circle) ... A feeling of fatigue in particular was not felt.
(triangle|delta): Normal fatigue.
x: Remarkably tired due to writing friction.

(Evaluation criteria for print peeling after writing)
◯: No peeling or deformation is observed.
Δ: Peeling/deformation (running) of printing was observed.
×: Printed characters cannot be distinguished at all due to peeling/deformation.

As is clear from the results in Table 1 above, Examples 1 and 2 of the present invention are easier to write than Comparative Examples 1 and 2, which are outside the scope of the present invention, have a good grip, and do not cause fatigue. , it was confirmed that it is a grip material for writing instruments that does not peel off the print after writing.

A writing instrument grip material composition and a writing instrument grip material suitable for writing instruments such as mechanical pencils, ballpoint pens and pencils can be obtained.

10 writing instrument (mechanical pencil)
11 Axle tube 12 Rear shaft 13 Core shaft 14 Front threaded tube 15 Rear threaded tube 16 Base 17 Grip part 18 Ring member 19 Core 20 Grip material 21 Inner cover 22 Centering member 23 Outer layer 24 Annular protrusion 25 Inner layer

Claims (6)

A grip material for a writing instrument used for a grip portion of a writing instrument, the grip material for a writing instrument comprising at least two layers, the inner layer comprising at least a prepolymer obtained by reacting a polyol component and a polyisocyanate component, a curing agent, and an adhesive. It is composed of a urethane elastomer obtained by blending a material containing a property imparting agent, and the outer layer is blended with a material containing at least a prepolymer obtained by reacting a polyol component and a polyisocyanate component, and a curing agent. A grip material for a writing instrument, characterized by using a dense composition containing the polyether-based urethane elastomer obtained by the above. 2. The writing instrument grip material according to claim 1, wherein said tackifier is a secondary or tertiary higher monoalcohol. 3. The writing instrument grip material according to claim 1 , wherein the urethane elastomer surface of the inner layer is decorated. 4. The writing instrument grip material according to claim 3 , wherein at least one of vapor deposition, printing, painting, and transfer is applied as the decoration. A gripping material for a writing instrument used for a gripping portion of a writing instrument, the gripping material being compounded with a material containing at least a prepolymer obtained by reaction of a polyol component and a polyisocyanate component, a curing agent, and a tackifier. A material containing a prepolymer obtained by reacting at least a polyol component and a polyisocyanate component, and a curing agent on the decorated surface after disposing the urethane elastomer obtained by disposing and decorating the surface of the urethane elastomer. A method for producing a grip material for writing instruments, characterized by disposing a polyether-based urethane elastomer obtained by blending. 6. The method of manufacturing a writing instrument grip material according to claim 5 , wherein the decoration is performed by vapor deposition, printing, painting, or transfer.

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