JP2791864B2 - Ink backflow preventive for water-based ballpoint pens - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink backflow preventive for an aqueous ballpoint pen. More specifically, the present invention relates to an ink backflow preventer for filling the rear end of aqueous ink directly packed in an ink storage tube having a pen body connected thereto.

[0002]

2. Description of the Related Art In recent years, an aqueous ballpoint pen has been studied in which an ink is directly packed in a barrel and supplied directly to a pen body. However, deformation of the ink backflow preventive body due to impact, and ink backflow preventive body accompanying ink consumption have been studied. It is not always enough for smooth following.

[0003]

Various ink backflow preventers using polybutene, mineral oil or silicone oil as base oils have been studied in the past. It has been difficult to sufficiently satisfy both the smooth follow-up performance of the ink backflow preventive member accompanying consumption. In other words, in order to prevent deformation of the ink backflow preventive body, which can cause writing failure and ink leakage,
It is necessary to make the base oil have a high viscosity, and if the viscosity is made high, the base oil may adhere to the ink storage tube at the time of following the ink consumption, or may not follow the ink at a low temperature, resulting in poor writing. On the other hand, when the viscosity is made low, the following with ink consumption becomes smooth, but the impact resistance is remarkably reduced.
Also, when polybutene or mineral oil is used as the base oil, it is easily mixed with the ink, and the ink backflow preventive may be decomposed or the ink may be denatured. When silicon oil is used as the base oil, it is difficult to adhere to the ink storage tube and achieves smooth follow-up, and it is difficult to mix with the ink, so it is difficult to react with the ink.However, it is difficult to select a thickener, and shearing It has a problem of lack of stability.

An object of the present invention is to provide an ink backflow preventive for a water-based ballpoint pen, which is less likely to be deformed by an impact or the like and has excellent follow-up performance.

[0005]

In order to achieve the above object, the present inventor has studied and found that silicon oil was used as a base oil, and a thickener and a polyester plasticizer were added thereto. The present inventors have found that an ink backflow preventive of the invention can be obtained, and have completed the present invention. That is, the ink backflow preventive for aqueous ballpoint pens of the present invention has a temperature of 25 ° C.
A base oil composed of silicone oil having a viscosity of 4 to 8 Pa · s, a thickener and a polyester plasticizer, wherein the polyester plasticizer is contained in an amount of 0.3 to 0.8% by weight. .

[0006]

The base oil used in the present invention is silicone oil. Silicon oil has a lower affinity for resin than other base oils such as polybutene, so that it hardly wets the resin ink storage tube and hardly adheres to the side wall surface of the ink storage tube when following ink consumption. Therefore, the following becomes very smooth, and the temperature dependency of the oil viscosity is small even at a low temperature. Therefore, even if the viscosity is increased, the influence of the backflow preventing body on the following becomes small. Another feature is that it is difficult to react with the ink because it hardly mixes with the water-based ink.

[0007] The viscosity of the base oil is 4 to 4 at a temperature of 25 ° C.
It is necessary to be 8 Pa · s. If it is less than 4 Pa · s, the impact resistance cannot be satisfied, and if it exceeds 8 Pa · s, the ink backflow preventive body following speed required for the above-described ink direct-packing type water-based ballpoint pen is 0.5 to 1.5.
mm / min cannot be satisfied.

[0008] Thickeners include finely divided silica powder, metal soap,
Bentonite and the like, and these hydrophobic thickeners are
Species or a combination of two or more can be used.
These thickeners are preferably contained in an amount of 3 to 10% by weight based on the backflow preventive.

The ink backflow preventer of the present invention further comprises a polyester plasticizer.

As described above, when a base oil composed of silicon oil is generally used, there is a problem that it is difficult to select a thickener and the shear stability is lacking. In this regard, when a polyester plasticizer is added, a thickener such as hydrophobic silica can be selected in a wide range, and the shear stability can be increased.

Although it is not theoretically known why the addition of the polyester plasticizer increases the shear stability, the polyester plasticizer exerts a binder-like effect on the skeleton when the thickener swells to enhance the skeleton. It is presumed that it acts as an agent and therefore makes the relationship between the silicone oil and the thickener denser and the skeleton stronger.

Examples of the polyester-based plasticizer include a polymer of a glycol with a dibasic acid such as adipic acid, azelaic acid, sebacic acid, and phthalic acid. Of these, use of a glycol adipate ester is preferred. Glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, propylene glycol, dipropylene glycol, trimethylene glycol, butanediol, pentanediol, hexanediol, heptanediol, octanediol,
Cyclopentanediol and cyclohexanediol having 2 to 8 carbon atoms are preferred. It is necessary that the addition amount of the polyester plasticizer be 0.3 to 0.8% by weight. At less than 0.3% by weight, there is no skeletal enhancement effect,
If the amount exceeds the weight percentage, it becomes difficult to stabilize the dispersion of the thickener in the silicone oil.

[0013]

Next, the present invention will be described specifically with reference to examples. Example 1 Silicon oil (KF96-5000) 46.0% by weight Silicon oil (KF96-3000) 45.7% by weight Hydrophobic silica (R-972) 8.0% by weight Polyester plasticizer (SP-105) 0 The components consisting of 0.3% by weight were mixed and stirred to form an ink backflow preventer.
The performance is shown in Table 1.

Examples 2 to 5 The components shown in Table 1 were used in the same manner as in Example 1 to provide an ink backflow preventer.

Comparative Examples 1 to 7 Next, Table 2 shows the composition and performance of each example.

[0016]

[Table 1]

[0017]

[Table 2]

Next, the trade names and manufacturers of each component in Tables 1 and 2 are shown. KF96H-10000: Shin-Etsu Chemical Co., Ltd. KF96H-6000: Same company KF96-5000: Same company KF96-3000: Same company HV-15: Nippon Petrochemical Co., Ltd. HV-35: Same company R-972: Nippon Aerosil SP-105: Sanken Kako Co., Ltd. (glycol adipate)

1.0 g of a water-based ink for a ball-point pen, having the following composition, was filled into a transparent polypropylene ink container tube having an inner diameter of 4 mm, and the back end of the ink backflow preventive material obtained in the above Examples and Comparative Examples was filled with 1.0 g. Filled 15g. Then, five aqueous ballpoint pens were prepared for each of the examples and comparative examples. In addition, a stainless steel ballpoint pen tip was attached to the tip of the ink storage tube. Direct Black 154 7.5% by weight (manufactured by Orient Chemical Co., Ltd., direct dye) Cross-linked acrylic acid 0.7% by weight (manufactured by Wako Pure Chemical Industries, Ltd., molecular weight 3,000,000) Ethylene glycol 20.0% by weight pH adjustment 1.0% by weight Rust preventive lubricant 0.2% by weight Antibacterial agent 1.0% by weight Deionized water

The evaluation was performed as follows. Impact resistance test: The ballpoint pen tip was turned upward and dropped on a cedar board (thickness 5 cm) from a height of 1 m several times, and the presence or absence of deformation of the ink backflow preventive body was examined. In the table, ◎ indicates “3
No deformation after 0 or more times, ○: “Deformation of the ink backflow prevention body after 20 to 30 times”, Δ: “Deformation after 5 to 20 times”, ×: “5
Deformation in less than times ".

Ink follow-up test: The follow-up properties of the ink backflow preventer were examined by spiral writing at a predetermined speed under an environmental temperature of 5 ° C. until the ink was exhausted. In the table, ◎ indicates “0.8 mm / m
In, follow-up speed of more than
/ Min following speed ”, × indicates“ 0.6 mm / min
The following tracking speeds are respectively shown.

Ballpoint pen aging test: The presence or absence of decomposition of the ink backflow preventive after heating at 50 ° C with a ballpoint pen was examined. In the table, ◎ indicates “No decomposition for 3 months or more”, and ○ indicates “2 to 3
分解 indicates “decompose in one or two months”, and X indicates “decompose in one month or less”.

[0023]

As is apparent from the above results, the ink backflow preventive for water-based ballpoint pens of the present invention is less likely to be deformed by impact, so that it is possible to prevent ink leakage and the like, and to prevent water-based ink from adhering to the ink storage tube. It has an excellent effect that it can be reliably followed with the consumption of water and is less likely to be decomposed.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) B43K 7/02 C09K 3/00

Claims (2)

(57) [Claims] 1. A base oil comprising a silicone oil having a viscosity of 4 to 8 Pa · s at a temperature of 25 ° C., a thickener, and a polyester plasticizer. % Of water-based ink for ballpoint pens. 2. The ink backflow preventer according to claim 1, wherein the polyester plasticizer is glycol adipate.