JPH0552343B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a non-leafing scaly metal powder pigment which has excellent stability and whose surface can be easily modified, and a method for producing the same. Non-leafing scaly metal powder pigments, which are frequently used as pigments in metallic paints, are produced by mechanically processing metal flakes or granules in the presence of an appropriate amount of a grinding aid, such as a stamp mill method or a dry ball mill method. , wet ball mill method, attritor method, vibrating ball mill method, etc.
As grinding aids, fatty acids, aliphatic amines, and the like have been commonly used, and in addition, aliphatic alcohols, fatty acid amides, fatty acid metal salts, fatty acid esters, organic phosphoric acid esters, and the like are known. Among these grinding aids, oleic acid has good grinding efficiency and produces metal pastes with excellent hiding power in a short grinding time; metal pastes with excellent color tone can be obtained; It is preferentially used because it has the following advantages: Since no ing phenomenon occurs, a coating film free of defects such as metal unevenness and delamination can be obtained. On the other hand, since oleic acid has the following drawbacks, it is difficult to say that oleic acid is a fully satisfactory grinding aid. One of the drawbacks of oleic acid is due to the fact that oleic acid has double bonds. For example, in the case of aluminum paste obtained by grinding in the presence of oleic acid, oleic acid exists in a state strongly adsorbed to the surface of the aluminum particles, but if such aluminum paste is exposed to the outside air for a long time, , the double bond part of oleic acid undergoes an oxidation reaction to form a radical (see the formula below), As a result of further recombination of the formed radicals, an oxidative polymerization reaction proceeds, thereby producing a polymeric substance. Since the polymer substance thus produced is insoluble in solvents, aluminum particles are aggregated to form aggregates during the precipitation process within the aluminum paste. This agglomerate formation is an undesirable phenomenon that significantly reduces the commercial value of the aluminum paste, as is well known to those skilled in the art. Furthermore, when oleic acid is used as a grinding aid, a metal soap that is poorly soluble in solvents is formed during the grinding process and other aluminum paste manufacturing processes, and the metal soap forms in the same manner as the above-mentioned polymeric substance. In addition to agglomerating particles and forming agglomerates, the formation of metal soaps changes the properties of the grinding oil, which consists of oleic acid-containing solvents for aluminum powder grinding, and the reuse of such grinding oil affects the quality of the aluminum paste. The problem also arises that it is not stable. As mentioned above, in the aluminum paste obtained by grinding in the presence of oleic acid, oleic acid is present in a state strongly adsorbed to the surface of the aluminum particles, and the oleic acid adsorbed to the particle surface is
Silane coupling to aluminum paste for the purpose of improving adhesion with resins used in plastic coatings, etc., for forming an insulating film on the surface of aluminum particles to prevent current leakage during electrostatic coating, and for other purposes. This becomes a major hindrance when surface treatment is performed using agents, organic titanates, etc. An object of the present invention is to provide a grinding aid that can overcome the drawbacks of oleic acid without impairing its advantages as a grinding aid. That is,
In the present invention, a) it is stable and does not change in quality due to oxidation-reduction, etc.; b) it does not change in quality during the manufacturing process of the metal paste such as the pulverization process; c) the pulverization efficiency and color tone of the obtained metal paste are good; d) the leafing phenomenon does not occur. The purpose of the present invention is to provide a grinding aid used in the production of a non-leafing scaly metal powder pigment, which has the following requirements: e) has a weak adsorption power to metal flakes and does not adversely affect post-treatment; The present invention is based on the novel finding that a grinding aid containing 70% by weight or more, preferably 90% by weight or more of a linear saturated alcohol having 12 to 14 carbon atoms satisfies all of the above requirements a to e. It is. The non-leafing scaly metal powder pigment of the present invention can be applied to 100 parts by weight of metal powder in the conventional method for producing non-leafing scaly metal powder.
It is produced using a grinding aid consisting of 0.1 to 20 parts by weight of a linear saturated alcohol having 12 to 14 carbon atoms, and the residue of the grinding aid is supported on the surface layer of the metal powder. In the present invention, as a grinding aid, carbon atoms of 12 to
14 straight chain saturated alcohols such as lauryl alcohol, tridecyl alcohol, myristyl alcohol, etc. alone or in mixtures thereof are used. When a linear saturated alcohol with less than 12 carbon atoms is used, the grinding efficiency is inferior to when oleic acid is used, and when a linear saturated alcohol with 15 or more carbon atoms is used, the leafing phenomenon occurs. The use of straight chain saturated alcohols having carbon numbers outside this range is not preferred. Furthermore, even if the number of carbon atoms is within the above range, it is not preferable to use a branched or unsaturated alcohol because the pulverization efficiency is lower than when oleic acid is used.
In particular, the use of unsaturated alcohols is not preferred since aggregates may be formed due to oxidative polymerization of unsaturated bond moieties as described above. From the results in the table below showing changes in properties, it is clear that lauryl alcohol, which can be used as a grinding aid in the present invention, is extremely superior to oleic acid in terms of oxidation stability.

[Table] The non-leafing scaly metal powder pigment of the present invention is produced in the same manner as conventional methods except that a linear saturated alcohol having 12 to 14 carbon atoms is used as a grinding aid. That is, the non-leafing scaly metal powder pigment of the present invention can be produced by charging metal flakes or granular powder, a grinding aid, and a hydrocarbon solvent into a drum containing a large number of steel balls, using a wet ball mill method, for example. The drum is operated at an appropriate rotational speed, and the steel balls that fall as it rotates crush metal pieces or granular powder.
After the grinding is completed, the contents of the ball mill are washed out and the metal concentration of the filter cake obtained is adjusted to create a pigment (paste) for use in paint preparation. Carbon number 12 to 14 used in the pulverization process
The amount of linear saturated alcohol is not particularly limited, but it is 0.1 to 20 parts by weight per 100 parts by weight of metal powder, and 0.1 to 20 parts by weight per 100 parts by weight of hydrocarbon solvent.
Preference is given to using linear saturated alcohols having 12 to 14 carbon atoms in parts by weight. This is because if the amount of alcohol used is less than the above range, the pulverization efficiency will be poor, whereas if the amount used exceeds the above range, a leafing phenomenon will occur, which is not preferable. In the present invention, a substantial proportion of the grinding aid may be a linear saturated alcohol having 12 to 14 carbon atoms,
Well-known grinding aids such as fatty acids and aliphatic amines may be added to an extent that does not affect the effects of the alcohol, but fatty acid amides are not added. In addition, as a hydrocarbon solvent, the boiling point is approximately 100
~250°C paraffinic hydrocarbons, olefinic hydrocarbons, naphthenic hydrocarbons, aromatic hydrocarbons, etc., and mixtures thereof may be used, but mineral spirits, solvent naphtha, xylene are preferable in terms of availability. , n-paraffin is particularly used. The scaly metal powder of the present invention includes powders of brass, zinc, aluminum, iron, nickel, chromium, and other malleable metals and alloys. Particularly preferred is aluminum or brass powder. The dispersibility and other functions of the metal pigment of the present invention can be improved by adding additives such as fatty acids, aliphatic amines, aliphatic alcohols, and surfactants in a process subsequent to the grinding process, for example, in the kneading process. You can also do it. The invention will now be further illustrated by means of non-limiting examples. Example 1 1 kg of atomized aluminum powder (Toyo Aluminum Co., Ltd. AC1003), 25 g of lauryl alcohol (95% purity), and 1.3 g of mineral spirits were placed in a 50 cm diameter container containing 50 kg of a 5/16 inch (approximately 8 mm) diameter steel ball. It was placed in a ball mill with a length of 18 cm, and the ball mill was rotated at 60 rpm for 4.5 hours. The contents of the ball mill were washed out of the ball mill with 16 mineral spirits and passed through a 325 mesh screen to remove coarse particles. Furthermore, the slurry that passed through the screen was separated into solid and liquid using a pan filter to obtain a filter cake with a metal content of 70%. 800g of this filter cake with mineral spirits
61.5 g was added and kneaded for 1 hour using a kneader mixer to obtain an aluminum paste with a metal content of 65%. Examples 2 to 10 and Comparative Examples 1 to 13 Aluminum pastes with a metal content of 65% were obtained in the same manner as in Example 1 under the conditions shown in Table 1. However, the kneading time was 1 hour in all cases.

[Table] Example 11 The following tests were conducted using the aluminum pastes obtained in each Example and Comparative Example. Table 2 shows the results of each test. Test 1: Cohesiveness test (sealed state) The 350 mesh screen residue immediately after prototype production and after being stored at 50℃ for 1 month in a sealed state was tested using JIS K5910-
The presence or absence of aggregation was evaluated by measuring according to 5.9. Test 2: Cohesiveness test (open state) 50 in open state (packed in can without lid)
The 350 mesh screen residue after being left for 14 days at ℃ was measured and evaluated in the same manner as Test 1. Test 3: Leafing property test 10 g of aluminum paste was dispersed in 100 g of xylene, and the presence or absence of floating particles floating on the surface was observed. When no suspended particles were observed, it was evaluated that there was no leafing property. Test 4: Color tone test Silver paint made by blending 2.5g of aluminum paste and 47.5g of acrylic lacquer,
It was applied onto art paper using a doctor blade, and the color tone of the resulting coating film was evaluated on a five-point scale in terms of whiteness and metallic luster (the better the color tone, the higher the score). Similarly, 1.5 g of aluminum paste, 48.5 g of acrylic lacquer, and 2.0 g of blue color pigment.
A colored metallic paint prepared by blending the above was applied onto art paper using a doctor blade, and the color tone of the resulting coating film was evaluated on a five-grade scale in terms of tinting strength. Test 5: Surface treatment test 500 g of aluminum paste, 2400 ml of mineral spirits and silane coupling agent [n-(trimethoxysilylpropyl)ethylenediamine;
Contains 10g of SH6020 manufactured by Toray Silicone Co., Ltd.
The aluminum paste was surface-treated by stirring at 70°C for 3 hours. In order to evaluate the effect of surface treatment, first, a paint was prepared by blending the following proportions: Acrylic 47-712 80 parts by weight (Dainippon Ink & Chemicals Co., Ltd. Acrylic Varnish) Supervetsucomin J-820 20 parts by weight (Melamine varnish manufactured by Dainippon Ink and Chemicals Co., Ltd.) n-Butyl alcohol 25 parts by weight Aluminum paste 3.75 parts by weight (Metal content equivalent) Aluminum paste before and after surface treatment using the withstand voltage measuring device shown in the attached drawing in the following procedure The withstand voltage value of the blended paint was measured. The paint to be measured is sealed in a glass tube with an inner diameter of 10 mm and a length of 120 mm. Apply a voltage of 5KV to the paint and hold for 1 minute while checking for current leakage using an ammeter. If there is no current leakage, further increase the voltage to 5KV
Raise it and do the same thing. After that, increase the voltage in 5KV increments up to 60KV and perform the same operation as above, and the maximum voltage at which no current leakage occurs is the withstand voltage value of the paint.

【table】

[Table] As is clear from the results shown in Table 2, the aluminum paste of the present invention has excellent stability, with almost no increase in screen residue even when left in an open state. In addition, in the aluminum paste of the present invention, the alcohol as a grinding aid is only weakly adsorbed on the surface of the aluminum particles, so the alcohol layer on the surface of the aluminum particles does not interfere with surface treatment. It is clear from the change in value. Example 12 The grinding oil consisting of a grinding aid and a hydrocarbon solvent used for grinding the aluminum powder in the production of the aluminum pastes of Example 1 and Comparative Example 1 was recovered, and the appearance and red color before and after use for grinding were collected. The results of component analysis in crushed oil by external spectroscopy were compared. In the grinding oil used in Example 1, no change in appearance or components was observed before and after grinding, whereas in the grinding oil used in Comparative Example 1, the appearance turned brown and a considerable amount of metallic soap was found in the ingredients. was recognized to exist.

[Brief explanation of the drawing]

The accompanying drawing is a schematic diagram of the withstand voltage measuring device. 1...Glass tube, 2...Rubber stopper, 3...Ammeter, 4...High voltage generator.

Claims (1)

[Scope of Claims] 1. A grinding aid consisting of a linear saturated alcohol having 12 to 14 carbon atoms in an amount of 0.1 to 20 parts by weight based on 100 parts by weight of metal powder, or a well-known grinding agent excluding the grinding aid and fatty acid amide. A non-leafing scaly metal powder pigment having a residue of a mixture with an auxiliary agent supported on the surface layer of the metal powder. 2. A method for producing a non-leafing scaly metal powder pigment, which comprises pulverizing metal flakes or granules into scaly shapes in the presence of a pulverizing aid, in which 100 parts by weight of metal powder is used as the pulverizing aid. against
Production of a non-leafing scaly metal powder pigment characterized by using 0.1 to 20 parts by weight of a linear saturated alcohol having 12 to 14 carbon atoms alone or as a mixture with a well-known grinding aid excluding fatty acid amide. Method.