WO1997031985A1

WO1997031985A1 - Oil-based pigment ink for writing utensils

Info

Publication number: WO1997031985A1
Application number: PCT/JP1997/000566
Authority: WO
Inventors: Hiroyuki Idogawa
Original assignee: Mitsubishi Pencil Kabushiki Kaisha
Priority date: 1996-03-01
Filing date: 1997-02-27
Publication date: 1997-09-04
Also published as: DE19781616T1

Abstract

An oil-based pigment ink for writing utensils which comprises at least one solvent selected from the group consisting of alcohols and glycol ethers, a pigment, and an acrylic resin. The acrylic resin is a copolymer having a weight-average molecular weight of 50,000 or lower and obtained by the copolymerization of a monomer mixture comprising either styrene and a carboxylated acrylic monomer or styrene and an aminated acrylic monomer.

Description

Description Oil-based pigment ink for writing instruments Technical field

The present invention relates to an oil-based pigment ink for writing implements. More specifically, it has fluidity suitable for writing instruments with a discharge mechanism utilizing capillary action, and has excellent dispersion stability, and does not cause clogging with felt nibs, fiber nibs, plastic nibs, etc. The present invention relates to an oil-based pigment for writing instruments having characteristics. Background art

Oil-based inks can be written on both ink-absorbing materials such as paper and cloth and non-ink-absorbing materials such as plastic, glass, and metal. Has been used as In particular, ink using pigment as a coloring material is generally known as a paint marker because of its excellent handwriting robustness, and is used not only in homes, schools and offices but also in various industrial applications. Carbon black is used as the black ink pigment.

However, since the oil-based pigment ink using carbon black has a high viscosity, a sufficient amount of ink cannot be obtained from a writing instrument having an ejection mechanism utilizing a capillary phenomenon, and writing blur occurs, so that paint ink is not suitable for use. A mechanism is used to obtain the discharge rate. In addition, if the above-mentioned ink is used for a long period of time, phenomena such as aggregation and settling of carbon black will occur, the fluidity will deteriorate, and the pen tip will be clogged. For this reason, the conventional paint maker has a method in which a stirrer such as a metal ball is put together with the ink into the ink storage section and redistributed, and has a complicated structure intertwined with the valve structure. Therefore, the number of parts was large, the assembly process was complicated, and the cost was high.

An object of the present invention is to provide an oil-based pigment ink for writing implements that does not need to adopt a complicated structure like a conventional paint marker. In other words, use the capillary phenomenon Oil-based pigments for writing implements that have fluidity suitable for writing implements with a stable ejection mechanism, have excellent dispersion stability, and do not cause clogging with filter nibs, fiber nibs, plastic nibs, etc. It is for the purpose of obtaining an ink. Disclosure of the invention

The present inventor has conducted various studies to solve the above-mentioned problems. As a result, the use of at least one solvent selected from the group consisting of alcohol-based solvents and glycol ether-based solvents and acryl-based resins, For writing instruments that have fluidity suitable for writing instruments even when black is used, have excellent dispersion stability, and do not cause clogging with felt nibs, fiber nibs, plastic nibs, etc. The oil-based pigment ink was successfully obtained, and the present invention was completed.

That is, the oil-based pigment ink for writing implements of the present invention comprises at least one solvent selected from the group consisting of alcohol solvents and glycol ether solvents, pigments, and acryl-based monomers having at least styrene and a carboxyl group. Or an acryl-based resin obtained by copolymerizing a mixed monomer containing at least styrene and an acryl-based monomer having an amino group.

Preferably, the pigment is carbon black, and the ataryl polymer is a copolymer having a weight average molecular weight of 50,000 or less. BEST MODE FOR CARRYING OUT THE INVENTION

The pigment used in the ink of the present invention is preferably carbon black, and the carbon black is not limited, and commercially available carbon black can be used. Preferred in terms of fluidity. Examples of carbon black include Cabot's “Regal 415 R”, “Rega 1250 R”, “Regal 350 R”, “Monarch 460”, and “Mogul—L”. # 45L manufactured by Mitsubishi Chemical Corporation, such as "P rintex 25", "P rintex 35", "P rintex 45", "S pecial B lack 250", "S pecial B lack 350" manufactured by egussa ","# 50 ","# 900 ","# 980 ","# 23 " 0 "," MA7 "," MA11 "," MCF88 ", etc. These can be used alone or in combination of two or more.

Its use amount is preferably 3 to 20% by weight.

The acryl resin used in the ink of the present invention comprises a copolymer of at least an acryl monomer having a styrene and a carboxyl group, or a mixed monomer containing at least an acrylic monomer having a styrene and an amino group. It is a copolymer having a weight average molecular weight of 5,000 or less.

In particular, for a copolymer obtained from a mixed monomer containing an acrylyl-based monomer having a carboxyl group, it is preferable to use a carbon black having a primary particle diameter of 80 nm or less.

In the present invention, the acrylic resin is effective as a carbon black dispersant, an anti-settling agent, and a binder.

Although the role of the acryl-based monomer having a carboxyl group and the acryl-based monomer having an amino group is not clear, it is considered to mainly assist the solubility in alcohol-based solvents or glycol ether-based solvents. Can be

Examples of the acrylic monomer having a carboxyl group include acrylic acid, methacrylic acid, acrylic acid 2-succinoyloxethyl, acrylic acid-12-phthaloxyl-ethyl, acrylic acid-2-phthaloyloxypropyl, and acrylic acid-2-phthaloyloxypropyl. 2-Cyclic acid 2-hexafluoro-drophthaloyloxethyl, methacrylic acid 2-succinoylquinethyl, methacrylic acid-2-phthaloyloxystyl, methacrylic acid-2-phthaloyloxypropyl, methacrylic acid 2-hexahydric acid Drophthaloyloxiecil and the like can be mentioned.

Examples of the acryl-based monomer having an amino group include, for example, dimethylaminoethyl acrylate, getylaminoethyl acrylate, dimethylaminoethyl methacrylate, and getylaminoethyl methacrylate.

These acryl-based monomers are used in a copolymer component (mixed monomer) in an amount of 5 to 80 mol%, preferably 10 to 70 mol%.

Although the role of styrene is not clear, it is considered to be mainly for extracting the dispersibility of carbon black, and 5 to 70 mol%, preferably 10 to 60 mol%, is contained in the copolymer component. % To be contained.

In addition, non-functional acrylate esters such as methyl acrylate, ethyl acrylate, n-butyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, and methacrylate Non-functional methacrylic acid esters such as ethyl, η-butyl methacrylate, and 2-ethylhexyl methacrylate can be included as needed.

On the other hand, the viscosity of an ink suitable for a writing instrument having a discharge mechanism utilizing the capillary phenomenon is 2 OmPa · s or less (25 ° C.). Therefore, the weight average molecular weight of the acryl-based resin is 5 The amount is preferably not more than 000, and the amount used is preferably from 1 to 20% by weight, although it varies depending on the weight average molecular weight and the like.

The solvent used in the ink of the present invention is at least one selected from the group consisting of alcohol solvents and glycol ether solvents.

Examples of alcohol solvents include methanol, ethanol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, sec-butyl alcohol, tert-butyl alcohol, n-amyl alcohol, isoamyl alcohol, sec-amyl alcohol , N-hexanol and the like. Examples of glycol ether solvents include methyl cellosolve, ethyl cellosolve, isopropyl cellosolve, butyl cellosolve, propylene glycol monomethyl ether, and the like.

In addition, a surfactant, a dispersing aid, an antioxidant, a lubricant, and the like can be appropriately selected and used as needed.

As a method for producing the ink of the present invention, a conventionally known method can be employed. The above components can be easily obtained by kneading and dispersing them in a dispersing machine such as a homomixer, ball mill, bead mill, homogenizer, sand mill, roll mill, etc.o

Although it is not clear why the oil-based pigment ink for writing implements of the present invention has good fluidity and excellent dispersibility, and does not cause clogging at the pen tip, the carbon black surface can be reduced by using a specific copolymer. The resin has a particularly strong adsorption effect on the resin, and as a result, exhibits excellent dispersibility and sedimentation-prevention, resulting in excellent fluidity and dispersion stability. It is considered that the carbon black does not settle even during the initial storage and clogging at the pen tip does not occur.

Example

Hereinafter, the present invention will be described in detail with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples.

The following tests were performed on the inks obtained in Examples and Comparative Examples.

Liquidity:

Evaluation was made based on the viscosity value measured at 25 ° C using a cone plate type rotary viscometer. Those having a value of 20 mPa · s or less show excellent fluidity.

Dispersibility:

The average particle size of the carbon black dispersed in the ink was measured using a laser scattering type particle size distribution analyzer, and evaluated from the obtained values.

Those having a small average particle diameter, especially those having a diameter of 150 nm or less have excellent dispersibility. Long-term storage:

The ink was filled into a sign pen having a fiber nib made of acryl resin, left for 3 months, and then written, and the state was evaluated by visual judgment.

：: Good handwriting without clogging.

X: Clogging occurs and handwriting is faded.

Example 1

Dimethylaminoethyl methacrylate 50 mol%, styrene 40 mol%, butyl acrylate 10 mol% of a mixed monomer of 10 parts by weight was charged into a solvent ethyl alcohol 80 parts by weight, and azobis was added. Solution polymerization was performed using dimethylvaleronitrile as a catalyst to obtain an acryl-based copolymer resin solution having a polymerization average molecular weight of 13,000.

90 parts by weight of this solution and 10 parts by weight of carbon black "MCF88" (manufactured by Mitsubishi Chemical Corporation) were kneaded and dispersed in a sand mill for 1 hour to obtain an oil-based paint for writing implement of the present invention. Obtained.

Table 1 shows the test results of the ink.

Examples 2 to 4, Comparative Examples 1 to 4

Table 1 shows the monomer mixture, its mixing ratio, solvent, carbon black, and ink mixing ratio. And as shown in Table 2, an oil-based pigment for writing implements was prepared according to Example 1.

Tables 1 and 2 show the test results of the obtained ink.

Example 5

Azobis dimethyl valero was charged with 10 parts by weight of a mixed monomer of 30% by mole of acrylic acid, 40% by mole of styrene, and 30% by weight of n-butyl acrylate in 80% by weight of a solvent ethyl alcohol. Solution polymerization was carried out using nitrile as a catalyst to obtain an acrylic copolymer resin solution having a polymerization average molecular weight of 1500.

90 parts by weight of this solution and 10 parts by weight of carbon black '' Rega 1415R '' (average particle size: 25 nm) [manufactured by Cabot Corporation] are kneaded and dispersed in a sand mill for 1 hour. Thus, an oil-based pigment ink for a writing instrument of the present invention was obtained.

Table 3 shows the test results of the ink.

Examples 6-8, Comparative Examples 5-8

An oil-based pigment for writing implements was prepared according to Example 5 with the mixed monomers and their mixing ratios, solvents, carbon black, and ink mixing ratios as shown in Tables 3 and 4.

Tables 3 and 4 show the test results of the obtained ink.

Table 1 Oil properties

Example No 2 334 Composition (mol%):

A Dimethylaminoethyl methacrylate 50 30 50 methacrylic 8 getyl Rminoethyl 40

Styrene 40 30 40 30 π-butyl acrylate 10 20 5 system (π butyl acrylate 20

2 2-Ethylhexyl acrylate 30 5 Fat Properties:

Weight average molecular weight 13000 6200 12000 6000 Composition (weight:

Acrylic resin 10 1 0 8 8 Ethanol 80

Isovirvir alcohol 80

Brobilene glycol monomethyl ether 82 82 Carbon bomb 7 CF88 * 1 0

〃 # 900 * 1 0

Fee "Regal 415R * 2 0

"Printex 35 * 30" Features:

G Fluidity (viscosity mPa * s) 4.5 5 4.8 3.9 3.2 Dispersibility (average δ · πιη) 98 L 06 L 03 L 1 2 Long-term storage 〇〇〇〇

* 1 Mitsubishi Chemical Corporation * 2 Cabot * 3 Degussa Table 2

* 1 Mitsubishi Chemical Corporation * 2 Cabot * 3 Degussa Table 3

* 1 Made by Cabot * 2 Made by Degussa Table 4

* 1 Made by Cabot * 2 Made by Degussa As is evident from the results of Tables 1 to 4, the oil-based pigment for writing implements of the present invention has excellent fluidity and dispersibility, and does not cause clogging at the pen tip even during long-term storage. It is. Industrial applicability

The oil-based pigment ink of the present invention is suitable for a writing instrument having a discharge mechanism utilizing capillary action. In addition, it can be used for a conventional writing instrument having a single structure.

Claims

The scope of the claims

1. At least one solvent selected from the group consisting of alcohol solvents and glycol ether solvents, pigments, and mixed monomers containing at least styrene and an acrylyl monomer having a carboxyl group, or at least styrene and amino. An oil-based pigment for a writing implement containing an acryl-based resin obtained by copolymerizing a mixed monomer containing an acryl-based monomer having a group.

2. The oil-based pigment for a writing implement according to claim 1, wherein the pigment is carbon black.

3. The oil-based pigment for a writing instrument according to any one of claims 1 to 2, wherein the acrylic resin is an acrylic resin having a weight average molecular weight of 5,000 or less.

4. The acrylic monomer having a carboxyl group is composed of acrylic acid, methacrylic acid, acrylic acid 2-succinoyloxethyl, acrylic acid 2-phthaloyloxyethyl, acrylic acid 2-phthaloyloxypropyl. , 2-hexahydrophthaloyloxetyl acrylate 4. The oil-based pigment for a writing implement according to any one of claims 1 to 3, wherein the oil-based pigment is a methacrylic acid 2-hexahydrophthaloyloxyshetyl.

5. The acrylic monomer having an amino group is dimethylaminoethyl acrylate, getylaminoethyl acrylate, dimethylaminoethyl methacrylate, or dimethylaminoethyl methacrylate according to claim 1. 4. The oil-based pigment for a writing implement according to any one of items 1 to 3.

6. The oily paint for a writing implement according to any one of claims 1 to 5, wherein the mixed monomer contains at least 5 to 80% of an acrylic monomer and 5 to 70% of styrene.