JPH11286636A - Oil-based ink composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an oil-based marking pen ink composition which can form writing excellent in adhesion on a non-absorbing surface. SOLUTION: This composition mainly consists of a colorant selected among dyes and pigments, at least one organic solvent selected among alcohols and glycol ethers, and at least one cyclohexyl-methacrylate-containing copolymer resin having a glass transition point (Tg) of -25 to 10 deg.C and a weight-average molecular weight of 5,000-35,000.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an oil-based ink composition, and more particularly to an oil-based marking ink composition which can be hardly peeled off when writing on a non-absorbent surface such as a plastic and can provide a handwriting with excellent adhesion.

[0002]

2. Description of the Related Art An oil-based marking pen ink is a composition containing a solvent, a resin, and a coloring material such as a dye or a pigment. Containing at least one solvent from aliphatic alcohols and glycol ethers, as the resin rosin resin, ketone resin, phenol resin,
Oil-based inks containing at least one or more resins such as polyamide resins, terpene resins, terpene phenol resins, and butyral resins have become mainstream. However, when writing on a plastic such as polypropylene, the adhesiveness was poor, and it was liable to fall off if touched repeatedly.

A resin using an acrylic resin obtained by copolymerizing a mixed monomer containing styrene and an acrylic monomer having a carboxyl group or an amino group has been proposed (JP-A-9-291248). . Here, the acrylic resin is obtained from monomers such as acrylic acid, methacrylic acid, 2-succinoyloxyethyl acrylate, and dimethylaminoethyl acrylate.
Although it has a weight average molecular weight of 50,000 or less, it does not recognize the adhesiveness when writing on a non-absorbent surface such as plastic, and therefore, with these oil-based inks, a writing line excellent in peel resistance is obtained. Not been.

[0004]

SUMMARY OF THE INVENTION The present invention has been developed to solve the problem of handwriting peeling that occurs when writing on the surface of plastic, glass, metal, or the like using an oil-based marking pen ink. . That is, an object of the present invention is to provide an oil-based marking ink composition that exhibits excellent adhesion when written on a non-absorbing surface such as polypropylene, plastic, glass, and metal.

[0005]

The above objects can be effectively achieved by the following invention and its embodiments. (1) It contains a coloring material selected from dyes and pigments and at least one organic solvent selected from alcohols and glycol ethers, and has a glass transition point (Tg) of -25 ° C.
An oil-based ink composition containing, as a main component, at least one copolymer resin containing cyclohexyl methacrylate having a weight average molecular weight of 5,000 to 35,000 at -10 ° C. (2) The above (1), wherein the copolymer resin contains at least one selected from the group consisting of alkyl acrylates and alkyl methacrylates (excluding cycloalkyl groups as alkyl groups) as comonomers. The oil-based ink composition according to the above. (3) The oil-based ink composition as described in (1) above, wherein the viscosity measured under the conditions of a BL viscometer (manufactured by Tokimec Co., Ltd.), a BL adapter, and a rotation speed of 30 rpm at 25 ° C. is in the range of 2 to 25 mPas. Stuff.

The colorant used in the oil-based ink composition of the above (1) may be a dye or a pigment generally used as an oil-based ink. For example, the dye may be Eizen Spiron Yellow manufactured by Hodogaya Chemical Industry Co., Ltd. 3RH,
Same yellow GRLH, same orange GRH, same orange 2
RH, Red GEH, Red GRLH, Red B
EH, Blue GNH, Blue 2BNH, Green 3GNH, Brown BH, Brown RH, Violet RH, Black BNH, Black MH, Black RLH, Black BH, etc., manufactured by Orient Chemical Industries, Ltd. Balifast Yellow 1101, Yellow 1103, Yellow 3104, Yellow 412
0, yellow 4121, orange 3206, orange 3207, orange 3210, red 130
6, Red 1308, Red 2303, Red 330
6, Brown 2402, Blue 1603, Blue 1605, Blue 2606, Black 1802, Black 3804, Black 3820, Oil Yellow 101, Yellow 105, Yellow 107, Pink 312, Scarlet 308, Blue 613 and the like (all of which are trade names) are listed. As a pigment,
Inorganic pigments such as carbon black, titanium oxide, pearl pigments, and metal powder pigments; and organic pigments such as nitroso pigments, nitro pigments, azo pigments, dye lake pigments, and fluorescent pigments.

As the organic solvent selected from alcohols and glycol ethers, aliphatic alcohols and glycol ethers having 4 or less carbon atoms are preferable. For example, methyl alcohol, ethyl alcohol, normal propyl alcohol, isopropyl alcohol, propylene glycol monomethyl ether , Propylene glycol monoethyl ether, propylene glycol monomethyl ether acetate, or the like.

[0008] Since inks using polar solvents such as the above-mentioned alcohols tend to have reduced adhesion, in the present invention, an acrylic resin having specific physical properties or a copolymer thereof is selectively used. Adhesive ink is used to dramatically improve the adhesion to the non-absorbing surface, and after the solvent evaporates, forms a durable film without leaving any stickiness on the surface in a short time.

A copolymer resin containing cyclohexyl methacrylate, which is an acrylic resin capable of achieving the above object, has a Tg in the range of -25 ° C. to 10 ° C. and a weight average molecular weight of 5,000 to 35,000. If the Tg is lower than -25 ° C, the ink is poorly separated from the solvent when writing on the non-absorbing surface, causing a problem that a desired strong film is not formed. Such an adverse effect of lowering the adhesion to plastic occurs. Weight average molecular weight of 500
If it is less than 0, the solvent separation will be poor as in the case of Tg, or it will absorb moisture in the atmosphere, making it easy to whiten. The problem of getting worse occurs. Further, the oil-based ink composition of the present invention may contain 25
Those having a viscosity of 2 to 25 mPas under the condition of ° C are preferred. If the viscosity is out of this range, firstly, if the viscosity is less than 2 mPas, sufficient film strength cannot be obtained. More specifically, in the case of an ejection mechanism utilizing the capillary phenomenon, the ink is held
A viscosity of about 10 to 10 mPas is appropriate, and in the case of a direct liquid type mechanism, the solid content can be increased, and the viscosity is 4 to 25 mPas.
Place.

The above-mentioned copolymer resin containing cyclohexyl methacrylate can be obtained as follows. That is, cyclohexyl methacrylate is copolymerized with an alkyl acrylate and / or an alkyl methacrylate. As the alkyl group of the acrylic acid alkyl ester and / or the methacrylic acid alkyl ester, methyl, ethyl, propyl, butyl, 2-ethylhexyl, lauryl, dodecyl, stearyl, cyclohexyl, and the like are preferable. An adjusted resin can be obtained. In addition, acrylic acid, acrylonitrile, glycidyl acrylate, hydroxylethyl monoacrylate, epoxy acrylate, and the like can be copolymerized as a comonomer. In addition to the above acrylic resins, rosin-based resins, ketone resins, phenolic resins, polyamide resins, terpene resins, terpene phenolic resins, butyral resins that are soluble in alcoholic solvents for viscosity adjustment, film hardness adjustment and dye dissolution aid May be added.

The oil-based marking ink composition of the present invention, having the above-described constitution, has excellent adhesion when written on a non-absorbing surface of a plastic such as a polypropylene resin, metal, glass or the like. It is intended to provide a pen ink. And, in addition to the above components, a viscosity modifier as necessary without departing from the scope of the present invention,
A film hardness adjuster, a dye dissolution aid, a pigment dispersant and a dispersion aid, a rust preventive, and the like can be appropriately compounded. The preferred composition ratio of the oil-based ink composition of the present invention is as follows.
To 20 parts by weight, 55 to 95 parts by weight of an organic solvent, and 3 to 25 parts by weight of an acrylic resin or a copolymer resin thereof. When each component is in this range, the peeling resistance of a writing line is particularly excellent. Becomes

The preparation of the oil-based ink composition of the present invention is generally carried out according to a conventional method as follows. When a dye is used as a coloring material, a predetermined amount of a solvent, a resin, and a dye are charged into a stirring vessel and stirred with a stirrer to obtain a homogeneous ink. At this time, it heats as needed. When a pigment is used as a coloring material, first, a dispersant and a part of a solvent are introduced into a dispersing machine to obtain a pigment dispersion by adding a part of a solvent, or a pigment paste that is subjected to a dispersion treatment is obtained. It is charged into a system containing a separately prepared solvent, resin and other necessary additives, and stirred to obtain a homogeneous ink.

[0013]

EXAMPLES The resin of the present invention will be described in more detail with reference to synthesis examples, but it is not intended to limit the invention. (Synthesis Example 1) In a 2000 ml four-necked flask equipped with a stirrer, a cooling tube, a thermometer, and a nitrogen inlet tube, 750 g of propylene glycol monomethyl ether, 335 g of cyclohexyl methacrylate, 165 g of 2-ethylhexyl acrylate, and azobisdimethyl valeronitrile 30 g was added and stirred, the temperature was increased while blowing nitrogen, and polymerization was performed at 70 ° C. for 7 hours to obtain an acrylic copolymer having a weight average molecular weight of 12,000 and Tg of 0 ° C.

(Synthesis Example 2) In a 2000 ml four-necked flask equipped with a stirrer, a cooling tube, a thermometer, and a nitrogen introducing tube,
750 g of propylene glycol monomethyl ether, 200 g of cyclohexyl methacrylate, 300 g of 2-ethylhexyl acrylate, and 15 g of azobisdimethyl valeronitrile were added and stirred, and the temperature was raised while blowing nitrogen,
Polymerized at 70 ° C for 7 hours, and had a weight average molecular weight of 17000 and T
An acrylic copolymer of g-31 ° C was obtained.

(Synthesis Example 3) In a 2000 ml four-necked flask equipped with a stirrer, a cooling tube, a thermometer, and a nitrogen inlet tube,
750 g of propylene glycol monomethyl ether, 430 g of cyclohexyl methacrylate, 70 g of 2-ethylhexyl acrylate, and 5 g of azobisdimethylvaleronitrile were added and stirred, and the temperature was increased while blowing nitrogen.
At 7 ° C. for 7 hours, with a weight average molecular weight of 46,000 and a Tg of 3
An acrylic copolymer at 7 ° C. was obtained.

Hereinafter, the present invention will be described in more detail with reference to Examples, but it is not intended to limit the present invention. (Example 1) An example of the formulation of the ink composition for marking of the present invention is shown below. Each component was stirred and mixed at room temperature for about 5 hours to obtain a uniform black ink using a dye. Propylene glycol monomethyl ether 28.0% by weight Ethyl alcohol 20.0% by weight * Synthesis Example 1 Resin liquid 40.0% by weight Varifast Black 3820 (trade name, manufactured by Orient Chemical Industries, Ltd.) 12.0% by weight 100.0 % % By weight (* Synthesis example 1 resin solution: Tg 0 ° C, weight average molecular weight about 12000, nonvolatile content about 40% by weight)

Comparative Example 1 Each component was stirred and mixed at room temperature for about 5 hours to obtain a homogeneous blue ink using a dye. Propylene glycol monomethyl ether 35.0% by weight Ethyl alcohol 20.0% by weight * Synthesis Example 3 Resin liquid 40.0% by weight Oil Blue 613 (trade name, manufactured by Orient Chemical Industry Co., Ltd.) 5.0% by weight 100.0 % by weight % (* Synthesis Example 3 resin solution: Tg 37 ° C, weight average molecular weight about 46,000, non-volatile content about 40% by weight)

Comparative Example 2 Each component was stirred and mixed at room temperature for about 5 hours to obtain a homogeneous red ink using a dye. Propylene glycol monomethyl ether 35.5% by weight Ethyl alcohol 20.0% by weight * Synthesis Example 2 Resin liquid 40.0% by weight Varifast Red 1308 (trade name, manufactured by Orient Chemical Industry Co., Ltd.) 4.5% by weight 100.0 % % By weight (* Synthesis example 2 resin solution: Tg-31 ° C, weight average molecular weight about 17000, non-volatile content about 40% by weight)

(Comparative Example 3) An example of a comparative formulation using a phenol resin as a resin component is shown below. The mixing conditions were the same as in Example 1. Propylene glycol monomethyl ether 60.0% by weight Ethyl alcohol 20.0% by weight * Tamanol 100S (trade name, manufactured by Arakawa Chemical Industry Co., Ltd.) 8.0% by weight Varifast Black 3820 (trade name, manufactured by Orient Chemical Industry Co., Ltd.) 12.0% by weight 100.0 % by weight (* Tamanol: 100S alkylphenol resin)

Example 2 Each of the above inks was packed in a pen and tested for adhesion. The writing object was written with polypropylene, glass, or stainless steel, and after one day, a cellophane tape was stuck to the writing line, and then the cellophane tape was peeled off, and the degree of peeling of the writing line was visually inspected. Table 1 shows the results of the adhesion.

[0021]

[Table 1] (Note) ○ Hardly peeled × Completely peeled As apparent from Table 1, the ink of the present invention has a weight average molecular weight of 5,000 at Tg of -25 ° C to 10 ° C after evaporation of the solvent.
Due to the tackiness of an acrylic resin of up to 35,000, the ink has excellent adhesion even on a non-absorbing surface such as polypropylene.

[0022]

The oil-based ink composition of the present invention uses an alcohol or a glycol ether as a solvent, and in particular, an acrylic resin having a Tg of -25 ° C to 10 ° C and a weight average molecular weight of 5,000 to 35,000 as a resin for imparting tackiness. By using a copolymer resin containing cyclohexyl methacrylate as the resin, when writing on non-absorbing surfaces of plastics such as polypropylene resin, metal, glass, etc., the writing line excels in peeling resistance and the surface is sticky in a short time It is an oil-based ink that can form a durable film without rust.

Claims (3)

[Claims] 1. A colorant selected from dyes and pigments and at least one organic solvent selected from alcohols and glycol ethers, having a glass transition point (Tg) of -25 ° C. to 10 ° C. and a weight average molecular weight of 5000-350
An oil-based ink composition containing at least one copolymer resin containing cyclohexyl methacrylate as a main component. 2. The copolymer resin according to claim 1, wherein the comonomer contains at least one selected from the group consisting of alkyl acrylates and alkyl methacrylates (excluding cycloalkyl groups as alkyl groups). 2. The oil-based ink composition according to item 1. 3. The viscosity measured under the conditions of a BL viscometer, a BL adapter, a rotation speed of 30 rpm and 25 ° C. is 2 to 25 m.
The oil-based ink composition according to claim 1, which is in the range of Pas.