JP5709638B2 - Ink backflow preventive composition for writing instruments - Google Patents

Description

  The present invention relates to an ink backflow preventive composition for a writing instrument. Furthermore, it is related with the ink backflow prevention body composition for writing instruments arrange | positioned by the end surface of the ink accommodated directly in the ink storage cylinder.

  Conventionally, the ink backflow prevention body composition applied to writing instruments has an ink backflow prevention performance that prevents ink from leaking out from the rear end of the storage cylinder when stored or transported upright (chip upward) or horizontally. , Ink following performance that moves smoothly in the direction of the pen tip as ink decreases during writing, and performance such as impact resistance to prevent ink scattering and ink outflow when the writing instrument falls from a high place are required. .

  As the ink backflow preventive body composition, grease or the like, which is a mixture of mineral oil and metal soap, has been applied for oily ballpoint pens containing oil ink with high viscosity in the old days. When applied to a water-based ballpoint pen with a built-in low-viscosity ink, it may cause problems such as poor tracking when ink is consumed and excessive viscosity change due to temperature changes, and the backflow of water-based ink cannot be suppressed. there were. Therefore, an ink made into a gel by adding a gelling agent such as dibenzylidene sorbitol, tribenzylidene sorbitol, N-acylated amino acid derivative, or fine particle silica to a hardly volatile organic liquid such as liquid polybutene, mineral oil, or silicone oil. Many backflow prevention body compositions have been proposed and widely put into practical use (see, for example, Patent Documents 1 to 3).

Japanese Patent Publication No. 64-10554 JP-A-57-200472 Japanese Patent Application Laid-Open No. 7-242093

However, the conventional ink backflow preventive composition using the gelling agent is not sufficient in impact resistance performance to prevent ink scattering and ink outflow when the writing instrument falls from a high place. When the additive amount of the agent is increased, it may adhere to the ink storage tube during the movement accompanying ink consumption during writing (ink tracking), and smooth tracking may not be possible. It wasn't.
The present invention provides a highly practical ink backflow preventive composition that satisfies both the above-mentioned impact resistance performance and ink following performance, and has sufficient ink backflow prevention performance and stability over time.

The present invention is an ink backflow preventive body that is disposed on the rear end surface of the ink stored directly in the ink storage cylinder of the writing instrument and moves forward according to the consumption of the ink, wherein the ink backflow preventive body is a non-volatile liquid. It is a requirement to add a gelling agent and liquid polyethylene wax.
Furthermore, the melting point of the liquid polyethylene wax is −20 ° C. or less, and the liquid polyethylene wax is required to be added in the range of 1 to 30% by mass in the total amount of the ink backflow preventive composition.
Furthermore, it is a requirement that the hardly volatile liquid is any one of mineral oil, liquid paraffin, alkyl-modified silicone oil, polybutene, and α-olefin-co-oligomer.

  In the present invention, liquid polyethylene wax is mixed in a hardly volatile liquid serving as a base material and gelled with a gelling agent, so that both impact resistance performance and ink following performance are satisfied. A highly practical ink backflow preventive composition having sufficient stability can be obtained.

The hardly volatile liquid is used as a base material (base oil) of the ink backflow preventive composition. Examples of the components used include polybutene, α-olefin co-oligomer, liquid paraffin, and refined mineral oil. In particular, polybutene is preferred because it is difficult to mix with ink and is excellent in ink followability and impact resistance.
Specific examples of the commercially available polybutene include polybutene LV-7, LV-10, LV-25, LV-50, LV-100, HV-15, HV-35, and HV-35. HV-50, HV-100, HV-300 (manufactured by Shin Nippon Petrochemical Co., Ltd.), polybutene 0H, 5H, 10H-T, 15H, 300H, 15R, 35R , 100R, 100R, 300R (above, manufactured by Idemitsu Petrochemical Co., Ltd.), 015N, 06N, 3N, 5N, 10N, New Glide M, New Glide μ (above, manufactured by NOF Corporation), etc. It can be illustrated.
In addition, the said non-volatile liquid can be used in 70-98.9 weight% with respect to the backflow prevention body composition whole quantity.

  The gelling agent is added in order to increase the viscosity of the hardly volatile liquid to a suitable viscosity as the ink backflow preventer composition. Examples of the gelling agent include silica whose surface is hydrophobically treated, fine particle silica whose surface is methylated, aluminum silicate, swellable mica, clay-based thickeners such as bentonite and montmorillonite which are hydrophobically treated, magnesium stearate, Fatty acid metal soaps such as calcium stearate, aluminum stearate, zinc stearate, tribenzylidene sorbitol, fatty acid amide, amide-modified polyethylene wax, hydrogenated castor oil, dextrin compounds such as fatty acid dextrin, cellulose compounds and the like are preferable. The fatty acid aluminum, the fatty acid dextrin, the amide-modified polyethylene wax, and the aliphatic amide that give a sufficient thickening effect to the hardly volatile liquid and are excellent in stability are used.

The liquid polyethylene wax is used in the case of a hardly volatile liquid alone, or is deformed due to a drop impact, etc. generated by a conventional backflow preventer composition, poor follow-up due to adhesion to an ink containing tube, curing during long-term storage, It is possible to suppress poor fluidity and the like associated with oil separation and to provide a writing instrument with stable writing performance for a long period of time.
The liquid polyethylene wax is a wax that exhibits a liquid state at an ambient temperature, and preferably has a melting point of −20 ° C. or lower. When a material having a melting point of −20 ° C. or lower is applied, it is more useful because it can maintain smooth ink following performance without being cured even at an ultra-low temperature.

  The liquid polyethylene wax is used in an amount of 1 to 30% by weight, preferably 1.5 to 15% by weight, based on the total amount of the ink backflow preventive composition. If the addition amount of the liquid polyethylene wax is less than 1% by weight, it is difficult to develop desired backflow resistance and ink following performance, and if it exceeds 30% by weight, excess liquid polyethylene wax is contained in the ink backflow preventer composition. By being present, the interface between the ink and the ink backflow preventive composition tends to collapse due to the interaction with the ink.

  In addition, gelation aids, polar solvents such as alcohol and glycol to improve coloring prevention performance and backflow prevention performance, various surfactants as stabilizers, metal oxide particles and various fine particles can be added as necessary. It is.

  The ink backflow preventive composition is prepared by adding a gelling agent and a liquid polyethylene wax to a hardly volatile liquid used as a base oil, adding various additives as necessary, and uniformly dissolving by heating, and a stirrer such as a disper. And then uniformly kneaded and then kneaded by a dispersing machine such as a three-roller, a kneader, or a basket mill. Moreover, it can also deaerate by a centrifugal desorption method etc. as needed.

  There is a spread meter (parallel plate viscometer) as a simple means for measuring the hardness and fluidity of a highly viscous liquid such as the ink backflow preventer of the present invention, and the measured value is referred to as the SM value. An ink backflow preventer having a SM value of 20 ° C. in the range of 20 to 60 mm exhibits good characteristics in impact resistance, backflow prevention and ink followability. The SM value range is preferably 20 to 60 mm, more preferably 25 to 45 mm.

  The ink backflow preventive composition is filled with ink in an ink storage tube equipped with a nib and then filled at the end, and is used in combination with a solid ink backflow preventive if necessary. Is done. This prevents ink from evaporating from the rear end of the ink storage tube, and prevents ink from flowing backward when the pen tip is left facing upward or when an impact is applied.

  As the ink, a conventionally known water-based or oil-based ink is used. When the ink is an oil-based ink, a low-viscosity or medium-viscosity oil-based ink having an ink viscosity at 25 ° C. of from 100 mPa · s to 5000 mPa · s (shear rate of 3.5 [1 / sec]) is preferably used. In the case of water-based ink, a shear-thinning water-based ink is particularly preferably used.

  A marking pen tip or a ballpoint pen tip is used as the pen tip. In particular, application in the form of a ballpoint pen using a ballpoint pen tip is preferable, for example, a chip formed by holding a ball in a ball holding portion in which the vicinity of the tip of a metal pipe is pressed and deformed inward from the outer surface, or A tip that holds a ball in a ball holding portion formed by cutting a metal material with a drill or the like, or a ball that holds a tip formed by cutting a metal pipe or metal material by a spring body The thing biased forward can be applied. Moreover, the said ball | bowl about 0.15-1.2 mm diameters, such as a cemented carbide alloy, stainless steel, a ruby, a ceramic, can be applied.

  As the ink storage tube, a metal processed body or a molded body made of a thermoplastic resin such as polyethylene, polypropylene, or polyethylene terephthalate is preferably used from the viewpoint of low ink evaporation and productivity. In particular, in the resin molded body, by using a transparent, colored transparent, or translucent molded body, it is possible to visually recognize the ink from the outside, giving a unique design effect, and the ink color tone, remaining amount, etc. Can be confirmed. In addition to directly connecting the chip to the ink storage tube, the ink storage tube and the chip may be connected via a connecting member. The ink storage tube may be a refill for a ballpoint pen, and the refill may be stored in a shaft tube. Alternatively, the shaft tube may be used as an ink storage tube to prevent direct ink and ink backflow in the shaft tube. The body may be filled.

  Examples and Comparative Examples are shown below, but the present invention is not limited to these Examples. In addition, the number of the Example in a table | surface and a comparative example represents a weight part. The SM value represents a one-minute value of a spread meter at 20 ° C.

The contents of the raw materials in the table will be explained according to the note numbers.
(1) NOF Corporation, trade name: Polybutene 5SH (20 ° C. viscosity: about 20000 mPa · s)
(2) NOF Corporation, trade name: New Glide U (20 ° C. viscosity: about 600 mPa · s)
(3) Mobil Sekiyu Co., Ltd., trade name; Mobil SHF-403 (40 ° C. viscosity: about 400 mPa · s)
(4) Product name: VERSA FLOW BASE (viscosity at 20 ° C .: about 900 mPa · s), manufactured by Shamrock
(5) Clariant Japan Co., Ltd., trade name: Seridust 9615A
(6) Product name: Leopard KLT, manufactured by Chiba Flour Milling Co., Ltd.
(7) Enomoto Kasei Co., Ltd., trade name: Disparo 6850-20X
(7) Nippon Aerosil Industry Co., Ltd., trade name: Aerosil R974

Preparation of Ink Backflow Preventing Body Composition Examples 1 and 2 and Comparative Examples 1 to 3
A predetermined amount of gelling agent is added to the oil component and heated while stirring with a disper. After stirring for 30 minutes from 140 ° C., the heating is stopped and the mixture is allowed to cool naturally at room temperature for 12 hours. An ink backflow preventer composition was obtained by centrifugal separation after three-roll treatment (3 pass).

Example 3
A predetermined amount of a gelling agent was put into the oil component and stirred for 10 minutes at a disperser of 2000 rpm, and then a centrifugal roll-off method after three-roll treatment (3 pass) to obtain an ink backflow preventive composition.

Comparative Example 4
A gelling agent was quantitatively added to the oil component, and the mixture was stirred at 2000 rpm for 10 minutes. After the three-roll treatment (3 pass), centrifugal desorption was performed to obtain an ink backflow preventive composition.

Preparation of sample ball-point pen Viscosity at 20 ° C. on a polypropylene pipe (ink containing tube) with an inner diameter of 3.8 mm, fitted with a stainless steel pipe tip (ball-point pen tip) equipped with a 0.5 mm diameter cemented carbide ball at the tip. Was filled with 0.9 g of water-based red ink (shear thinning pigment ink) of 100 mPa · s, and 0.12 g of the ink backflow preventive compositions of Examples and Comparative Examples were placed in contact with the rear end of the ink, respectively, and then centrifuged. A sample ballpoint pen was obtained by incorporating it into a cap-type writing instrument exterior.

The following tests were carried out using the above sample ballpoint pens, and evaluations were made according to the respective evaluation criteria. The results are shown in Table 2.

Drop Impact Test The sample ball-point pen was dropped 10 times from a height of 1 m in a chip upward state, and the state of the ink backflow prevention composition after standing still for 24 hours in the chip upward direction was visually observed.
○: No change is observed in the state of the ink backflow preventer composition.
X: The shape of the ink backflow preventing body composition is remarkably broken, and the ink leaks backward.
Ink follow-up test The sample ball-point pen was tested using a spiral writing tester adjusted to a writing load of 100 g and a writing angle of 70 degrees until the ink disappeared at a writing speed of 4 m / min. Observed.
◯: The ink backflow prevention body composition follows well with the consumption of ink, and the backflow prevention body is formed until writing is completed.
X: The followability of the ink backflow prevention body composition is poor and remains attached to the inner wall of the housing tube, and the backflow prevention body cannot be formed midway.
Stability test over time After the sample ballpoint pen was left in a 50 ° C. environment with the tip facing upward for 60 days, the state of the ink backflow prevention composition was visually observed.
○: No change is observed in the state of the ink backflow preventer composition.
X: A part of the ink backflow prevention body composition is separated and infiltrated into the ink, or a part of the ink backflow prevention body composition flows out from the rear end of the ink containing tube and leaks into the writing instrument exterior. ing.

Claims (4)

  An ink backflow preventive body that is disposed on the rear end surface of the ink stored directly in the ink storage cylinder of the writing instrument and moves forward according to the consumption of the ink, the ink backflow preventive body comprising a gelling agent and a non-volatile liquid An ink backflow preventive composition for a writing instrument, comprising a liquid polyethylene wax.   The ink backflow preventive composition for a writing instrument according to claim 1, wherein the liquid polyethylene wax has a melting point of -20 ° C or lower.   3. The ink backflow preventive composition for a writing instrument according to claim 1 or 2, wherein the liquid polyethylene wax is added in an amount of 1 to 30% by mass in the total amount of the ink backflow preventive composition.   4. The ink backflow preventer for a writing instrument according to any one of claims 1 to 3, wherein the hardly volatile liquid is any one of mineral oil, liquid paraffin, alkyl-modified silicone oil, polybutene, and α-olefin-co-oligomer. Composition.