JPH0545633B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD The present invention relates to a water-based fluorescent pigment ink for marking pens that can be marked on various surfaces including ink-impermeable surfaces to provide concealable fluorescent marks. BACKGROUND ART Water-based fluorescent inks for marking pens, which are mainly intended for paper and are made by dissolving a fluorescent dye in an aqueous medium, are disclosed in, for example, Japanese Patent Publication Nos. 57-29500, 58-40593, and 59-4453. Many proposals have been made. However, these inks cannot mark ink-impermeable surfaces such as hydrophobic plastic surfaces, and even if they do mark ink-impermeable surfaces, they do not provide concealable marks. On the other hand, a number of organic solvent-based fluorescent pigment inks for marking pens have also been proposed, which provide opaque fluorescent marks on all types of surfaces. (For example, JP-A-56-152878, 58-
208359 and 59-75967, etc.) Problems to be Solved by the Invention The water-based fluorescent ink prepared by dissolving the fluorescent dye in an aqueous medium cannot substantially mark an ink-impermeable surface; Moreover, since the mark is transparent, the fluorescent effect cannot be exhibited on colored paper.
Furthermore, fluorescent pigment inks based on organic solvents have the problem of odor and toxicity of organic solvent vapor when marking, and are particularly unsuitable for use in closed rooms. Can mark various surfaces, including ink-impermeable surfaces,
To obtain a water-based fluorescent ink for marking pens that gives a fluorescent mark with hiding properties, a daylight fluorescent pigment is used as a colorant, and a highly reflective material that hides the base on dark-colored surfaces or surfaces impermeable to ink is used. It is necessary to use a concealing pigment such as a white or silvery white titanium oxide or a pearl pigment. The specific gravity of a daylight fluorescent pigment, which is a solid solution of a fluorescent dye and a synthetic resin, and a concealing pigment such as a pearlescent pigment, which is made of an inorganic titanium oxide or mica flakes whose surface is coated with titanium oxide (the former is 1.1 to 1.4; The latter is 3.9 ~
4.2), their surface properties and other physical properties are significantly different, and it is difficult to stably disperse them in a low-viscosity aqueous vehicle. Here, the need for the ink of the present invention to have low viscosity is achieved by storing the ink in the barrel and supplying the ink via a valve mechanism to the nib, which is made by binding fiber bundles with resin. This is because it is applied to a marking pen with a configuration of
The ink must exhibit a low viscosity of 20 cps or less. Additionally, water-based inks generally do not adhere well to hydrophobic, ink-impermeable surfaces, making it impossible to obtain strong adhesion. Means for Solving the Problem The ink of the present invention comprises mica flakes surface coated with titanium oxide or titanium oxide as a daylight fluorescent pigment and a hiding pigment in an aqueous vehicle containing an alkali-soluble resin and a rosin ester emulsion. It is made by dispersing pearl pigment. Examples of alkali-soluble resins include styrene-acrylic acid, α-methylstyrene-acrylic acid, acrylic acid copolymers such as vinyl acetate-acrylic acid, vinyl acetate, maleic anhydride, ethylene-maleic anhydride, styrene-maleic anhydride, etc. Examples include maleic acid copolymers, silica and maleic acid resins. These resins are dissolved in an aqueous medium in the form of an alkali metal salt, ammonium salt, alkanolamine salt or acid amide, and are used in the ink composition in an amount of 1 to 50% by weight, preferably 5 to 30% by weight. Rosin ester emulsion is a resin emulsion of ester of rosin and polyhydric alcohol such as ethylene glycol, glycerin or pentaerythritol, and contains 3 to 20% by weight, preferably 5 to 15% by weight in terms of solid content in the ink composition. Used in range. Daylight fluorescent pigments are solid solutions of fluorescent dyes and synthetic resins, and examples of the synthetic resins include sulfonamide resins, alkyd resins, methacrylic acid copolymers, and acrylonitrile-styrene copolymers. These fluorescent pigments are used in the ink composition in an amount of 2 to 30% by weight, preferably 10 to 20% by weight. The titanium oxide pigment as the hiding property-imparting pigment may be either rutile type or anatase type, and is used in the range of 2 to 50% by weight, preferably 5 to 20% by weight in the ink composition. Pearl pigments consisting of mica pieces whose surface is coated with titanium oxide have an average particle diameter of 40 μm or less, and are used in an amount of 2 to 25% by weight, preferably 5 to 15% by weight in the ink composition. Other pigments or dyes for complementary colors as required,
Surfactants, volatile water-soluble alcohols, humectants, basic substances, preservatives, antifoaming agents, etc. are added. Function Of the two types of resins applied to the aqueous vehicle, the rosin ester emulsion mainly plays an effective protective colloid effect on titanium oxide or pearl pigments as hiding property-imparting pigments, and prevents sedimentation and hardening of the pigments. The alkali-soluble resin mainly gives the mark strong adhesion to the ink-impermeable surface, but when both are used together, their synergistic effect enhances their individual effects. ramp up. Such a synergistic effect cannot be obtained by combinations of other resins, such as combinations of rosin ester emulsions and water-soluble resins, and combinations of resin emulsions other than rosin esters and alkali-soluble resins. Furthermore, on a mirror-like surface with high reflectance, this type of ink mark has a low contrast with the surface and is difficult to identify. To avoid this phenomenon, measures are usually taken such as adding an extender pigment to the ink or significantly increasing the pigment/resin ratio. Although these measures are disadvantageous as an ink for marking pens, the ink of the present invention produces matte-like marks due to the action of the two types of resins, so even on mirror-like surfaces without taking the above measures, there is no difference between the mark and the surface. The contrast is large and the mark is clearly recognized. Examples Table 1 shows the compositions and physical properties of inks of examples and comparative examples.
Shown below. Each ink was prepared according to the following procedure. (1) Add water, resin (water-soluble), and additives to a beaker and stir for 15 minutes using a Chemister stirrer. (2) Next, add the fluorescent pigment paste and the hiding pigment (paste) and stir for 15 minutes. (3) Finally, add the resin emulsion and stir for 30 minutes to finish. However, in Comparative Examples 1 and 2, operation (3) was not performed.

【table】

[Table] The composition numbers in the table represent parts by weight, and the numbers in parentheses represent solid content. The contents of the note numbers are as follows. (1) Aqueous paste of fluorescent pigment (solid content 40
(2) Fluorescent pigment aqueous paste (solid content 40%) consisting of a fluorescent pink dye (CIBasic Red 1) and a solid solution of acrylonitrile-styrene copolymer (3) Fluorescent yellow dye (CISolvent Yellow 44) Aqueous paste of fluorescent pigment (solids content 40
(%) (4) Aqueous paste (solid content 50%) in which 50 parts by weight of rutile titanium oxide is dispersed in an aqueous medium consisting of 2.5 parts by weight of an anionic dispersant and 47.5 parts by weight of water (5) 60% of rutile titanium oxide Water-based paste (6) Mica pieces surface-coated with titanium oxide (average particle size 10 μm or less) (7) Rosin-glycerin ester (acid value 7 or less,
Emulsion with a softening point of 70-80℃ (solid content 40
(%) (8) Rosin-pentaerythritol ester (acid value 20 or less, softening point 110-120℃) emulsion (solid content 50%) (9) Acrylic acid ester-styrene copolymer emulsion (solid content 41.5%) (10 ) Maleic acid resin (acid value 39 or less, softening point 120)
~130℃) Emulsion (50% solids) (11) Maleic acid resin (acid value 140 or less, softening point 130)
~140°C) ammonium aqueous solution (solid content 30%) (12) Sierratsk ammonium aqueous solution (solid content 25
%) (13) Styrene-maleic acid copolymer (acid value 175~
200, softening point 105-120℃) ammonium aqueous solution (solid content 28%) (14) Ammonium aqueous solution of styrene-acrylic acid copolymer (solid content 30%) (15) Phthalocyanine green (CIPigment
Aqueous paste (pigment content: 20%) in which Green 36) is dispersed in water using a nonionic activator Effects of the Invention The following performance tests were conducted on the example ink in comparison with the comparative example ink. Specified amounts of each ink were filled into marking pens with the following mechanisms to serve as samples for tests (1) and (2). The marking pen mechanism has a diameter of 15mmφ and a total length of 110mm.
One 8mmφ stainless steel ball for ink redispersion is housed inside the bottomed aluminum cylinder, a pen holder equipped with a valve mechanism is fixed to the open end, and an acrylic fiber bundle is attached to the tip of the holder. A 4mmφ pen body is fitted with a resin bonded body, and when marking, the pen tip is pressed against the marking surface and the valve is pushed open to draw the ink inside the cylindrical body into the pen body. Performance Test (1) Dispersion Stability After each sample was marked with a predetermined line on the surface of black paper, polyethylene film, and polyester film using a marking pen, each sample was sealed and used for testing. After each sample marking pen is left standing for 15 days with the pen tip facing upward, a mark is made on the surface adjacent to the initial mark of each sample on the surface without shaking, and the color tone of both marks is compared. Display of results ○: Same as initial mark ×: Transparent mark with almost no hiding property (hidden pigment has settled) (2) Redispersibility Separately from the sample in (1), with the pen tip facing upward. After standing still for 30 days, shake each sample pen up and down and measure the number of shaking until the dispersion spheres move freely, judging by the sound of the dispersion spheres colliding. Display of results ○: Less than 3 times △: 4 to 10 times ×: No sound of dispersion spheres even after shaking 10 times (due to the formation of hard cake) (3) Adhesion Each sample ink was mixed 0.5 mm It is applied to the surface of a polyester film using a wire bar, and after being left for one day, the surface of each sample is rubbed at 1.9 kgG using a rubbing tester. Display of results ○: Resistant to 100 scratches ×: Peeling occurs after less than 50 scratches The test results are shown in Table 2.

【table】

[Table] As seen in the test results, inks containing no rosin ester emulsion or containing other resin emulsions (Comparative Examples 1 to 4) showed poor dispersion stability of the hiding pigment. It cannot be maintained, and hard cake formation is also observed.
On the other hand, in the ink containing no alkali-soluble resin (Comparative Example 5), no hard cake was formed, but stable dispersion of the hiding pigment and strong adhesion could not be obtained. Furthermore, the ink (Comparative Example 6) in which the alkali-soluble resin is replaced with a water-soluble resin (gum arabic) has a problem in adhesion. In contrast, the ink of the present invention exhibits pigment dispersion stability and good redispersibility, and in addition, provides marks that exhibit strong adhesion even to hydrophobic ink-impermeable surfaces. Compared to conventional organic solvent-based fluorescent pigment inks, the mark itself remains clear and has no odor or toxicity, and the present invention also allows for overcoating of other marks. This is the advantage of water-based fluorescent pigment ink.

Claims (1)

[Claims] 1. As essential components: (1) daylight fluorescent pigment, (2) a hiding pigment selected from titanium oxide and a pearl pigment consisting of mica flakes whose surface is coated with titanium oxide, (3) an alkali-soluble resin, and (4) A water-based fluorescent pigment ink for marking pens containing a rosin ester emulsion.