JPH07103336B2 - Oil-based pigment ink for writing instruments - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an oil-based pigment ink for a writing instrument, and more specifically, it has fluidity suitable for a writing instrument having an ejection mechanism utilizing the capillary phenomenon, and The present invention relates to an oil-based pigment ink for a writing instrument, which has excellent dispersion stability and is less likely to be clogged with a felt nib, a fiber nib, or a plastic nib.

(Prior Art) Conventionally, oil-based inks for writing instruments, that is, oil-based inks, can be written on both the absorbing surface of paper, cloth, etc. and the non-absorbing surface of plastic, glass, metal, etc., and are quick-drying Although it is widely used, inks that use pigments as coloring materials are especially used as paint markers because they have particularly excellent handwriting fastness.

(Problems to be Solved by the Invention) However, since the oil-based pigment ink used for the paint marker has a high viscosity, a sufficient discharge amount cannot be obtained in a writing instrument having a discharge mechanism utilizing a capillary phenomenon. Since the writing blur occurs, the paint marker adopts a valve structure to cover the discharge amount.
Further, in the above ink, the pigment sedimentation phenomenon occurs for a long time, the fluidity deteriorates, and the pen tip is clogged. Therefore, the conventional paint marker has a method in which a stirring member such as a metal ball is put together with ink in the ink storage portion and redistributed, and since it has a complicated structure intertwined with the valve structure, it is a component. There was a problem that the number of points increased and the work process became complicated, resulting in an increase in cost.

Therefore, the present invention is an oil-based pigment ink for writing instruments that does not need to adopt the structure of a conventional paint marker, that is, has good fluidity, excellent dispersibility, and can be used for a long period of time even when stored in a pen tip. The purpose of the present invention is to obtain an oil-based pigment ink for writing instruments that does not easily clog.

(Means for Solving the Problem) The inventors of the present invention have conducted extensive studies in view of the above-mentioned object, and as a result,
Finally, the present invention has been completed. That is, the present invention provides a pigment, polyvinyl butyral, and a solubility parameter of 1
Alcohol solvent of 0.5 or more and solubility parameter of 7.6
The gist of the present invention is an oil-based pigment ink for a writing instrument, which comprises at least the following hydrocarbon solvent having a boiling point of 130 ° C.

Hereinafter, each component of the oil-based pigment ink for writing instruments of the present invention will be described.

The pigment is used as a colorant, and is not particularly limited, and an azo pigment, a phthalocyanine pigment, a nitroso pigment, a nitro pigment, a basic dye pigment, an acidic dye pigment, a vat dye pigment. , Organic pigments such as mordant dye-based pigments and natural dye-based pigments, ocher, barium yellow, dark blue, cadmium red, barium sulfate, titanium oxide, red iron oxide,
Inorganic pigments such as iron black, aluminum hydroxide, calcium carbonate, and carbon black can be used, and these can be used alone or in a mixture, and the amount is preferably 3 to 20% by weight based on the total amount of the ink.

Polyvinyl butyral resin (hereinafter abbreviated as PVB) is
It is used as a dispersant, anti-settling agent and binder for pigments. For fastness of handwriting and storage stability of ink, it is preferable to add a large amount in the ink. The agent preferably has a high degree of polymerization. However, if the addition amount is large or the degree of polymerization is high, the ink viscosity becomes high. On the other hand, the ink viscosity suitable for writing instruments with a discharge mechanism that uses the capillary phenomenon is 20 cp.
s (at 25 ℃) or less, more preferably 15 cps (at 25 ℃) or less, the average degree of polymerization of 1000 or less is preferably used, specifically Denkabutyral # 2000-L, # 3000
-1, # 3000-2, # 3000-4, # 4000-1, # 4000-2 (above, manufactured by Denki Kagaku Kogyo Co., Ltd.), S-REC BL-1, BL-2,
BL-S, BX-L, BM-1, BM-2, BM-S (manufactured by Sekisui Chemical Co., Ltd.), etc. are used. Weight ratio (PVB / pigment) of 0.
The range of 1 to 2.0 is desirable.

Alcohol-based solvents having a solubility parameter of 10.5 or more (hereinafter referred to as solvent A) include methyl alcohol (solubility parameter: hereinafter δ, 14.5), ethyl alcohol (δ = 12.7), normal propyl alcohol (δ = 1)
1.9), isopropyl alcohol (δ = 11.5), normal butyl alcohol (δ = 11.4), isobutyl alcohol (δ = 10.8), tertiary butyl alcohol (δ =
10.6), etc., and as a hydrocarbon solvent having a solubility parameter of 8.2 or less (hereinafter referred to as solvent B), normal pentane (δ = 7.0), normal hexane (δ = 7.
3), normal heptane (δ = 7.4), normal octane (δ = 7.6), isooctane (δ = 6.9), and the like. In the present invention, the solvent A and the solvent B are mixed and used. Is an essential condition. Although the mixing ratio of the solvent A and the solvent B varies depending on the degree of polymerization of PVB used and the amount added, it is desirable that the solvent A / solvent B is 1 to 9. What if the mixing ratio is less than 1 PV
This is because the dissolved state of B tends to be slightly unstable, and the fluidity of the ink tends to decrease over time, and if it is greater than 9, the viscosity of the ink is high and the fluidity tends to decrease.

In addition, as components other than the above, resins, surfactants, rust preventives, dispersion aids, lubricants, etc. can be appropriately used as necessary.

As a method for producing the oil-based pigment ink for a writing instrument according to the present invention, a conventionally known method can be adopted. Can be easily obtained.

(Function) Although it is not clear why the oil-based pigment ink for a writing instrument according to the present invention has good fluidity and excellent dispersibility and does not cause clogging at the pen tip, the solvent A having a high solubility parameter is used.
By using a mixed solvent of the solvent B and a solvent B having a low solubility parameter, the fluidity of the ink is not deteriorated even if an amount of PVB that can sufficiently disperse the pigment used in the ink of the present invention is used. It is presumed that. In the present invention, the solubility parameter has the following contents. The solubility parameter is a characteristic value of the liquid that is a measure of the mixing property between the liquids, and was proposed by JH Hildebrand, and its basic concept is shown in the following equation.

There are various ways to obtain it, and a slightly different value can be obtained depending on the measurement method or calculation method. Specifically, the latent heat of vaporization method, vapor pressure method, molecular attraction constant method, etc. are known, but in the present invention, the values presented by Burrel ¹⁾ were used.

1) "Plastic Painting / Printing Handbook" Editorial Committee of Material Technology Research Group P.49-50 [1] (1987) (Examples) The present invention will be described in more detail with reference to Examples below. The numerical value of indicates "part by weight".

* 1 Carbon black (manufactured by Degussa) * 2 Permanent Red 4R (manufactured by Dainippon Ink Co., Ltd.) * 3 Copper phthalocyanine (manufactured by Dainippon Ink Co., Ltd.) * 4 Hansa Yellow 10G (manufactured by Dainippon Ink Co., Ltd.) ) * 5 Rosin-modified special synthetic resin (Harima Chemical Industry Co., Ltd.)
* 6 Polyamide (dispersion aid) (BYK Chemie Co., Ltd.)
Manufacture) (Effect of the Invention) The inks obtained in Examples 1 to 4 and Comparative Examples 1 to 4 were tested. The results are shown in Table 2.

Note 1) In Comparative Example 1, polyvinyl butyral is insoluble and cannot be evaluated as an ink.

* 1 Flowability: The viscosity of the obtained ink was measured at 25 ° C using a B type viscometer.

* 2 Dispersibility test: Each ink was dropped on an oil-based membrane filter 0.30 μm (TM-3P, manufactured by Toyo Roshi Kaisha, Ltd.), and the state was visually determined.

○: Completely passed △: Partially passed ×: Almost not passed * 3 Pen tip clogging test: Each ink was filled in a felt-tip pen having a fiber nib in which acrylic resin fibers were hardened with a thermosetting resin, After leaving for 3 months, writing was performed and the state was visually judged.

◯: Good handwriting without clogging ×: Clogging occurs and the handwriting is blurred As described above, the oil-based pigment ink for a writing instrument according to the present invention has excellent fluidity and dispersibility, and does not cause clogging at the pen tip. It is excellent.

The oil-based pigment ink for a writing instrument of the present invention can of course be used for a conventional writing instrument having a paint marker structure.

Claims (1)

[Claims] 1. An oil-based writing instrument comprising at least a pigment, a polyvinyl butyral resin, an alcohol solvent having a solubility parameter of 10.5 or more, and a hydrocarbon solvent having a solubility parameter of 7.6 or less and a boiling point of 130 ° C. or less. Pigment ink.