JPS6154829B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing an aqueous coating agent in which wax powder is directly added to an aqueous coating composition, and is further easy to produce, and the coating material has excellent abrasion resistance as well as water resistance. It's a method. Coating agents include paints or printing inks, and the present invention relates to a method for producing aqueous paints or printing inks. Generally, in printing inks used for printing on packaging materials such as wrapping paper, paper cartons, cellophane, plastic films, etc., wax is an essential component to add as an abrasion resistance imparting component (hereinafter referred to as an abrasion resistant agent). Conventionally, waxes used as wear-resistant agents in coating agents such as flexographic printing inks and gravure printing inks include carnabau wax, candelilla wax, Seratsu wax, polymecon wax, paraffin wax, microcrystalline wax, Low molecular weight polyethylene, fatty acid amide, etc. are known. In coating agents, these waxes act effectively as wear-resistant agents, so the average particle size is 1 to 30μ, preferably 3 to 10μ.
It is desirable that the powder be finely pulverized and uniformly dispersed. However, kneading machines such as ball mills, attritors, and sand mills are used to manufacture coating agents for gravure printing inks, flexographic printing inks, etc., but these kneading machines directly feed coarse wax particles directly into the coating agent. If it is added to the powder, it will not be able to be pulverized sufficiently. Therefore, by utilizing the property of wax to swell in organic solvents, toluene,
In hydrocarbon solvents such as xylene and hexane, ester solvents such as ethyl acetate, ketone solvents such as acetone and methyl ethyl ketone, alcohol solvents such as ethanol, propanol, butanol, and ethylene glycol, or mixed solvents thereof.
Using the above-mentioned kneading machine, a wax compound that had been pulverized in advance was added to an organic solvent-based coating agent. Recently, the problem of air pollution caused by organic solvents,
Due to occupational health and environmental issues, we replaced the solvent type.
Aqueous types that use almost no organic solvents are being put into practical use. Regarding water-based coating agents, since the previously known wax compounds using the above-mentioned organic solvents are not compatible with water-based coating agents,
Cannot be used. In addition, the various waxes mentioned above all have poor wettability with water and do not swell.
Even when mixed with water, it was difficult to finely grind the powder into a wax compound. Therefore, we use wax that has been mechanically pulverized as finely as possible or made into flakes in advance, adds a surfactant, a polymeric dispersant, or an antifoaming agent, etc. A wax compound was added to the aqueous coating agent, either by kneading it in a machine or by heating and melting the wax and then kneading it in a ball mill, etc. in water or a mixed solvent of water and alcohol. . Compared to solvent-based wax compounds, this wax compound has a more complex composition and manufacturing process, which increases costs. It also lacks sufficient storage stability, and the abrasion resistance of water-based coating agents due to the influence of additives such as surfactants. There were also problems with durability, water resistance, etc. Furthermore, in order to improve wax compounds, compounding oxidized waxes with hydrophilic properties has been considered, but sufficient effects as anti-wear agents have not been achieved. In addition, although low molecular weight polyethylene emulsions have excellent stability, the wax particles are too small to be effective as an anti-wear agent, and the presence of surfactants reduces the effectiveness as an anti-wear agent and water resistance. There was a problem. The present invention relates to a method for producing an aqueous coating agent that has a simple manufacturing process and has excellent abrasion resistance, water resistance, and stability. That is, this is a method for producing an aqueous coating agent, in which 0.5 to 5% by weight of finely pulverized wax powder having an average particle size of 1 to 30 microns is added to an aqueous coating composition. Conventionally, finely ground wax dispersed in an aqueous system has been used as an anti-wear agent, but in the present invention, mechanically finely ground wax powder is directly added to an aqueous coating agent, thereby shortening the manufacturing process. In addition to improving the physical properties of the coating agent. As the wax according to the present invention, any wax can be used as long as it is finely pulverized to form a wax powder with an average particle size of 1 to 30 microns, but polyethylene wax is preferred from the viewpoint of ease of pulverization. Melting point of polyethylene wax is 80℃~140℃, especially 85℃
Polyethylene of ~125°C and a molecular weight of 400 to 3,000, particularly 500 to 2,000 is preferable; if the molecular weight is too low, the stickiness becomes high and pulverization becomes difficult.
Furthermore, if the molecular weight is too high, crystallization progresses and becomes hard, resulting in a decrease in pulverization efficiency. As for the pulverization according to the present invention, a method that can pulverize the wax to an average particle diameter of 1 to 30 μm and a uniform particle size is suitable. Furthermore, after fine pulverization,
The wax obtained must be in powder form. Examples of such methods include, for example, a method in which wax granules are continuously fed into a supersonic air stream and pulverized, that is, a method using a jet mill, or a method in which wax is pulverized in a ball mill without using a solvent. be. A jet mill method is preferred for obtaining wax powder by pulverizing the wax. The finely pulverized particles are classified using a cyclone classifier or the like, and wax powder having the required particle size is used. The average particle size is 1 to 30μ,
Preferably it is 3 to 10μ, and the maximum particle size is 40μ or less. Waxes with particle diameters other than these will be less effective as an anti-wear agent. The amount of finely pulverized wax powder added is about 0.5 to 5% by weight based on the aqueous coating composition. In the present invention, there is no need to create a compound using organic solvents, water, etc., as is done in conventional methods, by using finely pulverized wax powder.
It is possible to manufacture a coating agent by adding the required amount directly to a meat kneading machine such as a ball mill along with a solvent, etc., and easily manufactures an aqueous coating agent with excellent abrasion resistance, water resistance, stability over time, etc. This is a manufacturing method that shortens the process. The aqueous coating agent referred to in the present invention can be applied to water-soluble type and emulsion type aqueous coating agents, and can also be applied to coating agents that use water and in combination with organic solvents such as alcohol. Although the present invention is aimed at an aqueous coating agent, it can also be used as an organic solvent type coating agent. Next, the present invention will be illustrated by examples, and the "parts" in the examples will be described below.
"" indicates parts by weight. Example 1 Aqueous coating agent phthalocyanine blue (cyanine blue KLH,
(manufactured by Toyo Ink Manufacturing) 10 parts styrene/acrylic water-soluble varnish (T-coat
FA, solid content 30%, manufactured by Nippon Polymer) 65 parts Silicone antifoaming agent (Silicone TSA-730, manufactured by Toshiba Silicone) 0.5 parts Wax - Polyethylene wax (Varico Polywax 1000, softening point 113℃, USA Petrolite) Matsuha 2.5 at room temperature using a jet mill.
Wax powder having an average particle size of 4 μm was milled in a cyclone classifier in a supersonic air flow of 1 part: 23.5 parts water. The above composition was milled in a pebble mill for 16 hours to prepare a water-soluble printing ink. This water-soluble printing ink had good fluidity, storage stability, etc., and when gravure printing was performed on high-quality paper, the printing effect was also good as shown in Table 1. Comparative Example 1 As a substitute for the wax in Example 1, molecular weight 1000,
Flake-shaped polyethylene wax with a softening point of 113℃
25 parts, rosin derivative surfactant (Etol FA,
A wax compound containing wax particles with a maximum particle size of 50μ obtained by charging 3 parts of Arakawa Hayashisan, 0.5 parts of silicone emulsion (antifoaming agent), and 71.5 parts of water into a pebble mill and milling for 16 hours. A water-soluble printing ink was prepared in the same manner as in Example 1 except that the same amount as the wax in Example 1 was used, and gravure printing was performed. Print results first
Shown in the table. Example 2 Water-based coating agent Cyanine Blue KLH 10 parts Styrene/maleic acid water-soluble varnish (SMA1440H, 35% solids, manufactured by Alco Chemical, USA) 60 parts Silicone TSA-730 0.5 parts Wax-polyethylene wax (Varico Polywax) 500, softening point 86℃, manufactured by Petrolite in the United States)
was produced in the same manner as in Example 1 with an average particle diameter of 6μ.
Wax powder: 4 parts Water: 25.5 parts The above composition was kneaded in an attritor for 3 hours to prepare a water-soluble printing ink. The obtained printing ink had good fluidity and storage stability, and when flexographically printed on kraft paper, as shown in Table 1,
The printing effect was also good. Comparative Example 2 As a substitute for the wax in Example 2, molecular weight
After heating and melting 20 parts of microcrystalline wax with a softening point of 95°C, pour it into 20 parts of glycerin while stirring, charge the precipitated wax mixture into a ball mill, and add 30 parts of water and 30 parts of ethanol.
The maximum particle size obtained by adding
A printing ink was prepared in the same manner as in Example 2 using a wax compound containing 60 μm wax particles and flexographically printed. The printing results are shown in Table 1. Example 3 Water-based coating agent Titanium White (Tiepeque R670, manufactured by Ishihara Sangyo) 40 parts T-coat FA 45 parts Silicone TSA-730 0.5 parts Wax-Polyethylene wax (Varico Polywax 2000, softening point 125°C, manufactured by Petrolite, USA) ) was treated in the same manner as in Example 1 with an average particle diameter of 8μ.
Wax powder 2 parts Water 12.5 parts The above composition was milled in a pebble mill for 16 hours to prepare a water-soluble printing ink. The obtained printing ink had good fluidity, storage stability, etc., and when it was gravure printed on carton paper, the printing effect was also good. The printing results are shown in Table 1. Comparative Example 3 As a substitute for the wax of Example 3, the wax compound of Comparative Example 1 was used, the printing ink was adjusted as in Example 3, and gravure printing was performed. Example 4 Aqueous coating agent Cyanine Blue KLH 10 parts T-coat FA 20 parts Silicone TSA-730 0.5 parts Wax - same as Example 1 1 part Water 23.5 parts The above composition was kneaded in a pebble mill for 16 hours, and then latex (Lucidene 361) A water-based printing ink was prepared by mixing 40 parts of the following materials (manufactured by Petrolite, USA).
Table 1 shows the results of flexographic printing on kraft paper. Comparative Example 4 As a substitute for the wax of Example 4, the wax compound of Comparative Example 1 was used, the printing ink was prepared in the same manner as in Example 4, and flexographic printing was performed. Example 5 Water-based coating agent T-coat FA 75 parts Silicone TSA-730 0.5 parts Wax - Same as Example 1 1 part Water 23.5 parts The above composition was kneaded in a high-speed mixer for 1 hour to prepare a water-based overcoat varnish. did. This overcoat varnish has good stability over time, etc., and was gravure printed on high-quality paper using water-based printing ink (Aqua KG, manufactured by Toyo Ink Manufacturing), and further coated with the obtained overcoat varnish. As shown in Table 1, the coating effect was also good. Comparative Example 5 Coating was carried out in the same manner as in Example 5 using an overcoat varnish prepared by replacing only the wax of Example 5 with the wax compound of Comparative Example 1.

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Claims (1)

[Claims] 1. The aqueous coating composition contains an average particle size of 1 to 30.
A method for producing an aqueous coating agent, which comprises directly adding finely pulverized wax powder to μ. 2. The method for producing an aqueous coating agent according to claim 1, in which polyethylene wax is used as the wax. 3 Claim 1 using wax powder finely pulverized by a jet mill as the wax powder
A method for producing an aqueous coating agent according to item 1 or 2.