JPH08143807A - Water-base ink composition - Google Patents

Abstract

PURPOSE: To obtain a water-base ink composition free from precipitation and separation with time and giving a soft and strong handwritten letter. CONSTITUTION: This water-base ink composition has an ink viscosity of 3,000-50,000cps and contains (A) 30-70wt.% of titanium oxide, (B) 3-15wt.% of a binder resin such as a water-soluble resin or a water-dispersible resin, (C) 0.5-15wt.% of a viscosity modifier such as a polysaccharide produced by microorganisms, a water-soluble vegetable polysaccharide, a water-soluble seaweed polysaccharide or a water-soluble synthetic polymer and a polymeric anti-settling agent such as dextran and/or its derivative and (D) water.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water-based ink using titanium oxide as a coloring material or a masking material, which does not require stirring before use and has good dischargeability with a ballpoint pen structure. The present invention relates to a water-based ink composition capable of writing vivid handwriting on dark-colored paper, concealing the handwriting of a water-based pen or an oil-based pen, printing on a typewriter, etc., or copying images by a dry copying machine.

[0002]

2. Description of the Related Art Conventionally, many applications of water-based inks using titanium oxide have been filed. For example, JP-A-4-258677
In the publication, at least titanium oxide, a binder such as a resin emulsion, and water are used, and the viscosity is several tens to several tens.
Inks that have 0 centipoise and can be used in correction fluids and marking pens are disclosed. Also, Japanese Patent Laid-Open No. 4-2
Japanese Patent No. 79682 discloses an ink which is made of titanium oxide and a vinyl acetate polymer and is in a paste form.

[0003]

[Patent Document 1] Japanese Patent Application Laid-Open No. 4-25867
In the case of the ink disclosed in Japanese Patent Publication No. 7, since the specific gravity of titanium oxide is large, the titanium oxide will settle in a short period of time.
Therefore, such an ink has the inconvenience that it is necessary to re-disperse the precipitated titanium oxide by stirring before use. Further, in the case of the ink disclosed in Japanese Patent Laid-Open No. 4-279682, although the sedimentation of titanium oxide can be suppressed, the ink is not ejected by the structure of a writing instrument such as a normal ballpoint pen or a marking pen, and the tip is not suitable for writing. There is a problem that a special ejection mechanism such as a structure having a nozzle is required. In addition, in order to write vivid handwriting on dark-colored paper, to obtain handwriting that can be used to conceal and correct the handwriting of water-based pens and oil-based pens, the printing of typewriters, etc. In this case, a large amount of titanium oxide must be blended in, but in this case, the handwriting tends to be brittle because the amount of titanium oxide particles in the handwriting is large, and when the handwriting is rubbed or written with another writing instrument from above the handwriting, There is a problem that the handwriting is broken or peeled off. It is known that a glycol solvent such as ethylene glycol or glycerin is added as a plasticizer for the binder resin in a large amount (for example, 20% by weight or more) in order to impart flexibility to the handwriting. In the case where a large amount of titanium oxide was mixed with, it was impossible to mix a large amount of solvent, and it was difficult to solve the problem due to brittle handwriting.

The present invention provides a water-based ink composition containing titanium oxide which does not cause sedimentation and does not require agitation before use, has high strength, produces a soft handwriting, and is writable with an ordinary ballpoint pen structure. To do.

[0005]

The present invention is an aqueous ink composition comprising at least titanium oxide, a binder resin, a viscosity modifier, a polymer anti-settling agent, and water, and having an ink viscosity of 3,000 to 50,000 centipoise. The gist is an aqueous ink composition, wherein the polymer anti-settling agent is dextran.

Titanium oxide, which will be described in detail below, is used as a coloring material or a masking material, and various types of titanium oxide such as rutile type and anatase type can be used. As a commercially available product, Thaitone SR
-1, R-650, R-3L, A-110, A
-150, R-5N, R-7E (all manufactured by Sakai Chemical Industry Co., Ltd.), Taipaque R-580, R-550, R-780, R-780-2, R-930. , A-
100, A-220, CR-58 (all manufactured by Ishihara Sangyo Co., Ltd.), Kronos KR-310, and KR-380.
KR-480, KA-10, KA-20, KA
-30 (Titanium Industry Co., Ltd.), TYPURE R-
900, same R-931, same R-960, same R-960V
HG, (above, made by DuPont Japan Limited), Titanics JR-300, JR-600A,
JR-603, JR-701, JR-800, JR-801, JR-805 (above, Teika Corporation)
Manufactured). The amount used is preferably 30 to 70% by weight based on the total amount of the aqueous ink composition.

The binder resin is used for forming a film of handwriting and dispersing pigments, and is a water-soluble acrylic resin,
Examples thereof include water-soluble resins such as water-soluble styrene-acrylic acid resins and water-soluble styrene-maleic acid resins, and water-dispersible resins such as acrylic emulsions, vinyl acetate emulsions and urethane emulsions. The amount used is preferably 3 to 15% by weight based on the total amount of the aqueous ink composition.

The viscosity modifier is used to adjust the ink viscosity, and is a water-soluble cellulose derivative such as methyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose,
Microorganism-produced polysaccharides such as pullulan, zansan gum, welan gum, lambsan gum, succinoglucan or derivatives thereof, tragacanth gum, guar gum, locust bean gum, tara gum, karaya gum, arabinogalactan gum, gati gum, quince seed gum, silium seed gum, gum arabic , Pectin, water-soluble plant polysaccharides such as starch or its derivatives, carrageenan, water-soluble seaweed-type polysaccharides such as alginates or their derivatives, polyvinyl alcohol, sodium polyacrylate, polyacrylamide, polyethylene oxide, polyvinylpyrrolidone, etc. Known viscosity modifiers such as water-soluble synthetic polymer substances may be used alone or in admixture of two or more, and the amount thereof is preferably 0.1 to 10% by weight based on the total amount of the aqueous ink composition.

This aqueous ink composition has a viscosity of 30.
It is necessary to be 00 to 50000 centipoise (E type viscometer, ST rotor, 1 rpm, 25 ° C.). If the viscosity of the ink is lower than 3000 centipoise, titanium oxide does not settle and separate, but titanium oxide with a large particle size causes thin caking at the bottom, which may cause fluffing and scraping during writing. Is because it is a paste and it becomes impossible to write with a normal ballpoint pen structure.

The polymeric anti-settling agent is used to form a protective colloid around titanium oxide to prevent the titanium oxide from settling and to form a flexible film, and dextran and / or its derivatives are used. When a pigment other than titanium oxide is used in combination, dextran and / or its derivative also form a protective colloid around the pigment to prevent the pigment from settling. Dextran is a homopolysaccharide composed of D-glucose produced mainly by bacteria of the genus Leuconostoc, but it is also obtained from other bacteria, and generally D-glucose is α
It is a -1,6-bonded polysaccharide, and may have other α-1,4 bonds or α-1,3 bonds. Examples of the dextran derivative include dialkyl dextran, dextran sodium sulfate, dextran benzyl ether and the like. Dextran preferably has an intrinsic viscosity of 0.15 to 0.90, and the amount used is preferably 0.5 to 15% by weight based on the total amount of the ink. This is because dextran having an intrinsic viscosity of less than 0.15 exhibits sufficient protective colloid properties with pigments having a small specific gravity such as carbon black, but pigments having a large specific gravity such as titanium oxide may not have sufficient protective colloid properties. , 0.90
If it exceeds, the protective colloid layer becomes too thick and the titanium oxides tend to be entangled with each other and tend to aggregate.

The intrinsic viscosity of dextran is measured as follows. Precisely weigh 0.2 to 0.5 g of dextran, add to water and dissolve to make exactly 100 ml to give a sample solution. Calculate the intrinsic viscosity according to Equation 1 by measuring the flow-down time with a Ubbelohde viscometer at 25 ± 0.02 ° C. for the sample solution and water. The Ubbelohde viscometer is selected so that the falling time is 200 to 1000 seconds.

[0012]

(Equation 1)

Water is the main solvent.

In addition to the above-mentioned components, conventionally known coloring pigments and extender pigments may be used in combination, various surfactants may be used for the dispersion stability of the pigment, and other moisturizing agents and flow improvers may be used. Various additives such as a leveling agent, a preservative, and a rust preventive can be appropriately added.

The aqueous ink composition of the present invention can be obtained by dispersing and mixing the above components using a stirring and dispersing machine such as a ball mill, an attritor or a sand grinder.

[0016]

In the aqueous ink composition of the present invention, it is considered that dextran and / or its derivative forms a protective colloid around titanium oxide and prevents sedimentation over time. In addition, since dextran forms a transparent and extremely flexible and strong film, the handwriting film composed of binder resin and dextran is stronger and more flexible than the handwriting of binder resin alone. Good handwriting with no problems such as cracks and peeling can be obtained.

[0017]

【Example】

Example 1 TYPURE R-931 (titanium oxide) 35.0 parts by weight John Cryl J-61J (binder resin, styrene-acrylic acid copolymer, manufactured by Johnson Polymer Co., Ltd.) 16.1 parts by weight Fujichemi HEC SG- 10% by weight aqueous solution of 25F (viscosity modifier, hydroxypropyl cellulose, manufactured by Fuji Chemical Co., Ltd.) 20.0 parts by weight Dextran (intrinsic viscosity; 0.16) 12.0 parts by weight water 16.8 parts by weight Surfynol PC (Anti-foaming agent, manufactured by Nissin Chemical Industry Co., Ltd.) 0.1 parts by weight In the above components, components other than a 10 wt% aqueous solution of Fuji Chemi HEC SG-25F were mixed and dispersed in a ball mill for 24 hours, and then Fuji Chemi HEC. 10% by weight of SG-25F
An aqueous solution was added and mixed and stirred to obtain a water-based ink composition.

Example 2 Titanics JR-800 (titanium oxide) 44.2 parts by weight John Cryl J-501 (binder resin, styrene-acrylic acid copolymer, manufactured by Johnson Polymer Co., Ltd.) 19.7 parts by weight Leosan (Viscosity modifier, succinoglucan, manufactured by Sansho Co., Ltd.) 1% by weight aqueous solution 10.0 parts by weight Dextran (intrinsic viscosity; 0.21) 5.0 parts by weight water 21.0 parts by weight Surfynol PC ( Above) 0.1 parts by weight Of the above components, components other than a 1 wt% aqueous solution of leosan are mixed and dispersed in a ball mill for 24 hours.
A wt% aqueous solution was added and mixed and stirred to obtain a water-based ink composition.

Example 3 Titanics JR-801 (titanium oxide) 43.8 parts by weight Johncryl J-62 (binder resin, styrene-acrylic acid copolymer, manufactured by Johnson Polymer Co., Ltd.) 14.9 parts by weight Jaguar HP-60 (viscosity modifier, guar gum derivative, manufactured by Sansyo Co., Ltd.), 2% by weight aqueous solution 10.0 parts by weight Dextran (intrinsic viscosity; 0.21) 1.0 part by weight water 30.2 parts by weight Surfy Nol PC (above) 0.1 parts by weight In the above components, components other than the 2% by weight aqueous solution of Jaguar HP-60 are mixed and dispersed in a ball mill for 24 hours, and then a 2% by weight aqueous solution of Jaguar HP-60 is added and mixed. A water-based ink composition was obtained by stirring.

Example 4 Titanics JR-701 (titanium oxide) 41.0 parts by weight Johncryl J-61J (previously mentioned) 25.8 parts by weight CMC Daicel 1350 (viscosity modifier, carboxymethylcellulose salt, Daicel Chemical Industries ( 25% by weight aqueous solution 20.0 parts by weight dextran (intrinsic viscosity; 0.55) 12.0 parts by weight water 1.1 parts by weight Surfynol PC (described above) 0.1 parts by weight CMC in the above components Components other than the 25 wt% aqueous solution of Daicel 1350 were mixed and dispersed in a ball mill for 24 hours, then a 25 wt% aqueous solution of CMC Daicel 1350 was added and mixed with stirring to obtain a water-based ink composition.

Example 5 Titanics JR-800 (previously mentioned) 44.2 parts by weight Johncryl J-501 (previously mentioned) 19.7 parts by weight Alcox R-1000 (viscosity modifier, polyethylene oxide, Meisei Chemical Industry Co., Ltd. )) 20 wt% aqueous solution 15.0 parts by weight Dextran (intrinsic viscosity; 0.55) 3.0 parts by weight ion-exchanged water 18.0 parts by weight Surfynol PC (previously described) 0.1 parts by weight In the above components, Components other than the 20 wt% aqueous solution of Alcox R-1000 were mixed and dispersed in a ball mill for 24 hours, then a 20 wt% aqueous solution of Alcox R-1000 was added and mixed and stirred to obtain a water-based ink composition.

Example 6 TYPURE R-931 (previously mentioned) 43.8 parts by weight Jonkuryl J-511 (binder resin, styrene-acrylic acid copolymer emulsion, manufactured by Johnson Polymer Co., Ltd.) 13.8 parts by weight Fuji Chemi 2% by weight aqueous solution of HEC SY-25F (viscosity modifier, hydroxyethyl cellulose, manufactured by Fuji Chemical Co., Ltd.) 10.0 parts by weight Dextran (intrinsic viscosity; 0.55) 2.0 parts by weight water 30.3 parts by weight Surfy Nol PC (previously described) 0.1 part by weight 2% by weight of Fuji Chemi HEC SY-25F in the above components
After mixing components other than the aqueous solution and dispersing them in a ball mill for 24 hours, a 2% by weight aqueous solution of Fujichemi HEC SY-25F was added and mixed and stirred to obtain an aqueous ink composition.

Example 7 Titanics JR-801 (previously described) 43.8 parts by weight Sodium hydroxide neutralized product of Julimer AC-20L (binder resin, polyacrylic acid copolymer, manufactured by Nippon Pure Chemical Industries, Ltd.) 13 0.8 parts by weight 2% by weight aqueous solution of Jaguar HP-60 (described above) 10.0 parts by weight Sodium dextran sulfate (intrinsic viscosity; 0.18) 10.0 parts by weight water 22.3 parts by weight Surfynol PC (described above) 0 1 part by weight Among the above components, components other than the 2% by weight aqueous solution of Jaguar HP-60 were mixed and dispersed in a ball mill for 24 hours, and then a 2% by weight aqueous solution of Jaguar HP-60 was added and mixed with stirring to prepare an aqueous ink composition. I got a thing.

Comparative Example 1 In Example 1, 1 of Fuji Chemi HEC SG-25F was used.
A water-based ink composition was obtained in the same manner as in Example 1 except that 5 parts by weight of a 0% by weight aqueous solution and 31.8 parts by weight of water were used.

Comparative Example 2 In Example 2, dextran was not added and water was added to
A water-based ink composition was obtained in the same manner as in Example 2 except that the amount was 6.0 parts by weight.

Comparative Example 3 In Example 5, dextran was not added and water was added to
A water-based ink composition was obtained in the same manner as in Example 5 except that the amount was 1.0 part by weight.

Comparative Example 4 In Example 6, Fuji Chemie HEC SY-25F-2
A water-based ink composition was obtained in the same manner as in Example 6 except that the weight% aqueous solution was 20 parts by weight and the water was 20.3 parts by weight.

The aqueous ink compositions obtained in Examples 1 to 6 and Comparative Examples 1 to 4 were made of polypropylene having an inner diameter of 3.0 mm and equipped with a stainless steel ball-point pen tip using a super hard ball having a diameter of 0.8 mm. After filling a transparent ink containing tube consisting of a hollow cylinder with an ink backflow preventer in which liquid polybutene was greased on top of the aqueous ink composition, centrifugal degassing of air bubbles in the ink Created the core. The following test was conducted using this core for a ballpoint pen. The test results are shown in Tables 1 and 2.

Sedimentation and Separation Test The ball-point pen core was left in a thermo-hygrostat having a temperature of 50 ° C. and a humidity of 30% with the pen tip facing downward for 2 months, and then the ink core was visually observed to separate titanium oxide. The presence or absence was evaluated. Evaluation ◯: No sedimentation was observed Δ: Sedimentation was less than 1 mm X: Sedimentation was observed in 1 mm or more

Ink ejection property The ink ejection amount was measured when the core for a ballpoint pen was written for 100 m at a writing speed of 7 cm / sec, a writing angle of 70 ° and a load of 100 g. Evaluation ◎: 0.7 g or more ○: 0.5 to 0.7 g △: 0.3 to 0.5 g ×: 0 to 0.3 g

Rewriting Test The aqueous ink compositions obtained in the above Examples 1 to 6 and Comparative Examples 1 to 3 were applied to a writing paper A specified in JIS P3201 with a 3 mil applicator and dried. An oil-based ballpoint pen (BK100 manufactured by Pentel) was used to write on the coating film, and the state of cracking and peeling of the coating film was visually observed. Evaluation ⊚: No cracking or peeling ○: Cracking but no peeling △: Both cracking and peeling, but the base cannot be seen ×: Peeling reaches the base and writing is not possible on the coating film

Flexibility Test The aqueous ink compositions obtained in Examples 1 to 6 and Comparative Examples 1 to 3 were used as the writing paper A specified in JIS P3201.
After coating with a 3 mil applicator and drying, the paper was bent and the state of cracks and peeling of the coating film at the bent portion was visually observed. Evaluation ◎: No cracking or peeling ○: Cracking but no peeling △: Peeling only at the bent portion ×: Peeling spreads from the bent portion to the surroundings

Viscosity Measurement The water-based ink compositions obtained in Examples 1 to 6 and Comparative Examples 1 to 3 were used in an E-type viscometer using a st rotor to
The viscosity was measured at 5 ° C. and 1 rpm. Unit: centipoise

[0034]

[Table 1]

[0035]

[Table 2]

[0036]

As described above in detail, the water-based ink composition according to the present invention can be used with a writing instrument having a simple structure that does not require stirring before use, and provides a handwriting that is strong against rewriting and bending. It is extremely excellent in practical use.

Claims (1)

[Claims] 1. An aqueous ink composition comprising at least titanium oxide, a binder resin, a viscosity modifier, a polymer anti-settling agent and water, wherein the ink viscosity is 3000 to 5000.
A water-based ink composition, which is 0 centipoise and the polymer anti-settling agent is dextran.