JPS6327293B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a resin film-forming composition, and more particularly to a resin composition for forming a resin film, such as a coating composition or an ink composition. Conventionally, barium sulfate is generally produced by reacting an aqueous sodium sulfate solution with an aqueous barium sulfide solution, but the barium sulfate obtained in this way usually has a large average particle size of 0.3 to 0.8μ. , and its particle size distribution is wide. Therefore, conventional barium sulfate generally has a large hiding power, so
In coating compositions and ink compositions containing such barium sulfate as a transparent pigment or extender pigment, the formed dried coating film is generally inferior in transparency and surface gloss due to light scattering of barium sulfate particles. Furthermore, in the case of dark-colored paints, for example, barium sulfate particles cause the paint film to become cloudy due to light scattering, and the colored pigments themselves have poor dispersibility, so secondary aggregation is likely to occur, resulting in clear, glossy dark colors. It is not possible to obtain a coating film of For this purpose, a resin film-forming composition containing barium sulfate with an average particle size of about 0.1μ as a transparent pigment or an extender has been proposed.
33984), as the amount of the compound increases, the physical properties of the coating film decrease,
In particular, the decrease in gloss and transparency is significant. The present invention has been made to solve the above problems, and provides a resin film-forming composition that can provide a resin film with excellent gloss and transparency because it contains ultrafine barium sulfate. The purpose is to The film-forming resin composition according to the present invention has primary particles having an average particle size of 0.01 to 0.08μ, and a particle size of
It is characterized by containing ultrafine barium sulfate with a particle size distribution in which primary particles of 0.1μ or less account for 90% or more of the total. The barium sulfate used in the present invention has a primary particle average particle size of 0.01 to 0.08μ, and the number of primary particles with a particle size of 0.1μ or less accounts for 90% or more, preferably 95% or more of the total. It is ultrafine barium sulfate with a diameter distribution. Since the wavelength of visible light is 380 to 780 nm, theoretically, if the particle size is less than a half wavelength of light, that is, less than 0.19μ, light will pass through the particle. As mentioned above, the ultrafine barium sulfate used in the present invention has an average primary particle diameter of 0.01 to 0.08μ, and
As will be explained later, since the particle size distribution of the primary particles is substantially all within a half wavelength of light, the primary particles are substantially transparent when dispersed as primary particles in a resin solution. Furthermore, since barium sulfate as described above is easily dispersed into primary particles under normal pigment dispersion conditions in resin compositions such as paint and ink compositions, the resin according to the present invention containing such barium sulfate According to the film-forming composition, the resulting resin film does not become cloudy due to light scattering of barium sulfate, and therefore, even when it is used in large quantities as an extender pigment, the resin film is extremely transparent and has excellent surface gloss. A coating can be obtained. When used as an extender pigment in dark colored paints, a film with a clear tone can be obtained due to its excellent transparency. In particular, colored organic pigments are often used as dark pigments, but they generally do not have good dispersibility in vehicles, and furthermore, when conventional barium sulfate is used as an extender pigment, its light scattering Since the coating film has a whitish tinge, it is impossible to obtain a clear and glossy dark resin coating, but the resin coating forming composition according to the present invention not only has transparency but also has excellent dispersibility. Therefore, it also acts as a dispersion aid for colored organic pigments, making it possible to obtain a deep-colored resin coating with a clearer and glossier color tone than in the past. The resin film-forming composition of the present invention is not particularly limited in the resin used, but examples include alkyd resins, melamine resins, urea resins, epoxy resins,
Thermosetting resins such as unsaturated polyester resins, phenolic resins, urethane resins, thermosetting acrylic resins, and thermoplastic acrylic resins can be preferably used. The amount of barium sulfate added to the resin film-forming composition is appropriately selected depending on the use of the resin composition, the type of resin, etc., and is not particularly limited. For example, in an alkyd resin-melamine resin paint, 160 parts by weight for 100 parts by weight of resin.
Even if part by weight of the ultrafine barium sulfate is added,
Forms a transparent coating film that is substantially the same as a resin-only coating. In addition, in the manufacture of paints, printing inks, etc.
The addition of barium sulfate may be carried out by any conventional method known in this technical field, and is not particularly limited. Of course, it may be used in combination with other extender pigments or appropriate additives, or may be dispersed in the resin in advance. Furthermore, the composition for forming resin films such as paints and inks containing ultrafine barium sulfate of the present invention exhibits non-Newtonian viscosity. Therefore, it improves the fluidity of paints, inks, etc., prevents the so-called "sagging" that often causes problems, improves the durability of the paint film, and, as mentioned above, improves the dispersibility of pigments. Since sedimentation is prevented, a resin composition with excellent workability can be obtained. Generally, the ultrafine barium sulfate used in the resin film-forming composition of the present invention is produced by continuously introducing an aqueous barium sulfide solution and an aqueous sulfuric acid solution into a reaction tank while controlling the barium sulfide concentration to be excessive. It is obtained by reacting for a very short period of time under thorough stirring to suppress the particle growth of barium sulfate produced in the reaction system. Therefore, for example, a pump is advantageously used as the reaction tank. As described above, the barium sulfate used in the resin film-forming composition of the present invention has a smaller average primary particle size and a smaller particle size distribution than conventional barium sulfate. Since it is narrow, when used as an extender pigment or a transparent pigment, it provides a coating film with outstanding transparency, gloss, and smoothness, and also acts as a dispersion aid.
For example, a colored organic pigment can be well dispersed in a vehicle to form a clear resin film with excellent gloss. The resin film-forming composition according to the present invention will be explained below with reference to Examples, but the present invention is not limited to these Examples in any way. Example 1 (1) Production of ultrafine barium sulfate A Nitsuso Warman pump (manufactured by Taiheiyo Kinzoku Co., Ltd.) with a suction port diameter of 1.5 inches, a discharge port diameter of 1 inch, an internal volume of 850 c.c., and an impeller rotation speed of 2380 rpm was used as a reaction tank. , This pump sucks in a sulfuric acid aqueous solution with a concentration of 110 g/hour and a temperature of 20°C at a constant rate of 700 g/hour, and a concentration of 120 g/hour so that the barium sulfide concentration of the pump discharge liquid is 6 g/hour.
g/, a barium sulfide aqueous solution at a temperature of 50° C. was sucked into the pump while controlling its suction amount, and was discharged from the pump at an average residence time of 0.17 seconds and an average reaction rate of 92%. The pump discharge liquid was divided into two parts, one of which was filtered using a filter press and washed with water.The resulting cake was stirred in water at high speed to form a slurry of 500 g/ml, which was dried using a spray dryer. For comparison, fine barium sulfate was produced according to the method described in Japanese Patent Publication No. 50-33984. That is, 1.4 mol of sodium sulfate aqueous solution 1 was charged into a 5-volume reaction tank at a temperature of 50°C, and sodium hexametaphosphate was added to the reactor.
3.3g was added and dissolved. While stirring this mixed solution, 1.75% of a 0.8 mol/barium sulfide aqueous solution was added dropwise, and the mixture was reacted at a temperature of 50° C. for 1 hour. After the addition was completed, the mixture was stirred for an additional 30 minutes.
The obtained slurry was filtered and washed with water using a filter press, and the water-containing cake was dried at a temperature of 100° C. for 24 hours and then ground to obtain fine barium sulfate for comparison. For each of the 300 particles of ultrafine barium sulfate and comparative barium sulfate obtained as described above, the particle size in a certain direction was determined using an electron micrograph at a magnification of 100,000 times to determine the particle size distribution. The results are shown in Table 1. Note that, for example, the particle size of 0.02μ means that the actual particle size is 0.015μ or more and less than 0.025μ. Further, in FIG. 1, the particle size distribution of the ultrafine barium sulfate is plotted as a solid line, and the particle size distribution of the comparative barium sulfate is plotted as a broken line. FIGS. 2 and 3 are electron micrographs of ultrafine barium sulfate and comparative barium sulfate, respectively. FIG. 4 also shows an electron micrograph of calcium carbonate, hereinafter referred to as comparative fine calcium carbonate. The average particle size of the comparative fine calcium carbonate is 0.08μ. As is clear from Table 1, the average primary particle size of the ultrafine barium sulfate used in the present invention is 0.05 μm, and particles with a particle size of 0.1 μm or less account for 96.0% of the total. On the other hand, the comparative barium sulfate has an average primary particle size of 0.1μ, and only 64.5% of the total particles have a particle size of 0.1μ or less. (2) Preparation of coating composition Baking type alkyd resin (Betsukosol J-524,
60% non-volatile content, manufactured by Dainippon Ink & Chemicals Co., Ltd.)
18.

[Table] Mixed varnish (alkyd resin/melamine resin solid content ratio 7/3), 5.1 parts by weight of xylene and 25 parts by weight of the ultrafine barium sulfate obtained in (1) above were added and dispersed to obtain a transparent paint with a pigment volume concentration of 30%. The above varnish was added to this to obtain paints with pigment volume concentrations of 20% and 10%. For comparison, paints were prepared using 25 parts by weight of the comparative barium sulfate and 15.8 parts by weight of the comparative calcium carbonate in place of the ultrafine barium sulfate. The transparent paints obtained in this way were applied in parallel on a glass plate using a 6 mil applicator, dried at room temperature, and then baked at a temperature of 140°C for 20 minutes.
A coating film with a thickness of 68μ was formed. The 20°/20° specular reflectance of this coating was measured using a gloss meter.
The surface gloss of the coating film was evaluated, and the perpendicular light transmittance was measured using the Hunter system L value to evaluate the transparency of the coating film. The results are shown in Tables 2 and 3. As is clear from the above table, according to the transparent coating composition of the present invention containing ultrafine barium sulfate, even when the pigment volume concentration reaches 30% (160 parts by weight per 100 parts by weight of resin), the resulting coating is Film surface gloss

【table】

[Table] and transparency are almost the same as coatings made of resin alone.
On the other hand, in the case of comparative barium sulfate and calcium carbonate, the gloss and transparency decreased significantly as the amount added increased. Example 2 (1) Preparation of color base As shown in Table 4, yellow pigment (Hostaperm
Yellow H3G (manufactured by Hoechst) and various extender pigments (listed later in Table 6) were weighed into a commercially available mayonnaise bottle. Add to this alumina beads with a diameter of 2 mm.
Add 240g and apply 1 with paint conditioner
After time dispersion, a mixed varnish consisting of 44.5 parts by weight of alkyd resin (Betsukosol J-524, supra) and 40 parts by weight of melamine resin (Super Betsukamine J-820, supra) was added and mixed for 15 minutes. Alkyd resin/melamine resin solid content ratio 7/
3. Colored color bases (a) to (li) containing 30 parts by weight of a yellow organic pigment per 100 parts by weight of resin were prepared. (2) Preparation of white base Alkyd resin (Betsukosol J-524, mentioned above)
25 parts by weight of titanium dioxide and 60 parts by weight of glass beads with a diameter of 0.15 mm are added to 327 parts by weight of a mixed varnish consisting of 100 parts by weight, 51 parts by weight of melamine resin (Supervetsucomin J-820, mentioned above) and 28 parts by weight of xylene. In addition, this mixture was weighed into a 100 ml mayonnaise bottle and dispersed in a paint conditioner for 30 minutes to prepare a white base. (3) Preparation of Paint The color base, white base, and mixed varnish described above were weighed in the formulation shown in Table 5 into a commercially available mayonnaise bottle, and mixed for 15 minutes with a paint conditioner to prepare colored paints having various extender pigment compositions. Got the paint. (4) Evaluation of physical properties of paint film The colored color base and the colored paint obtained in (3) above were each applied onto a glass plate using a 6 mil applicator, dried at room temperature, and then heated at 140°C.
Bake for 20 minutes. The gloss of this dried coating film was evaluated from the 20°/20° specular reflectance. The results are shown in Table 6 for the color base and in Table 7 for the paint. According to the colored coating composition of the present invention, the gloss of a colored coating film is significantly improved. That is, as shown in Tables 6 and 7, since the colored paint composition of the present invention contains ultrafine barium sulfate as an extender pigment, the gloss of the paint film decreases as the content increases. It is increased compared to the case where it does not contain. On the other hand, according to the paint composition containing comparative barium sulfate, compared to the case not containing barium sulfate,
It merely maintains the gloss of the coating film at approximately the same level. Furthermore,
According to conventional, commercially available paints containing barium sulfate, calcium carbonate, kaolin, etc. as extender pigments, the gloss of the paint film decreases significantly as the content increases. Next, the action of ultrafine barium sulfate used in the present invention as a dispersion aid will be explained using electron micrographs. Figure 5 shows the yellow pigment (5000x magnification). It is observed that the pigment particles are aggregated. Figure 6 shows that the content of ultrafine barium sulfate is 30 in Table 6.
Indicates the coating composition in parts by weight (5000 times), and the seventh
The figure shows this coating composition further enlarged (20000
times). It is observed that ultrafine barium sulfate adheres around the pigment and improves the dispersibility of the pigment. FIG. 8 shows a comparative coating composition containing barium sulfate and pigment in an equal ratio (5,000 times), and FIG. 9 shows it further enlarged (20,000 times). It is observed that barium sulfate and pigment are aggregated. Example 3 Baking type acrylic resin (acrylic A-405,
Non-volatile content 50%, manufactured by Dainippon Ink & Chemicals Co., Ltd.) 98.0
Weight parts and melamine resin (Supervecamine J-
820, supra) 42.0 parts by weight (acrylic resin/melamine resin solid content ratio 7/3)
Weighed 24.5 parts by weight of xylene and 70 parts by weight of the ultrafine barium sulfate obtained in Example 1 into a commercially available mayonnaise bottle, added 330 g of glass beads with a diameter of 1.5 mm, and dispersed with a paint conditioner for 1 hour to obtain a paint. Ta. For comparison, paints were obtained in the same manner as above, using the comparative barium sulfate, comparative calcium carbonate, and commercially available white carbon instead of the ultrafine barium sulfate. However, the viscosity of white carbon was too high under the above conditions, making it difficult to form into a paint, so the amount of white carbon added was 20 parts by weight per 100 parts by weight of resin. The paint viscosity of each paint thus prepared was measured. Non-Newtonian viscosity is
In a rotational viscometer, the rotor is constant and 1
The viscosity (cps) was measured at rotation speeds of 6 rpm and 60 rpm, respectively, and this ratio was evaluated as thixotropy (hereinafter referred to as TF). In addition, each paint was applied onto a glass plate using a 6 mil applicator, and a coating film was formed in the same manner as in Example 1.
Surface gloss and transparency were evaluated in the same manner as above. The results are shown in Table 8.

【table】

【table】

[Table] Shows parts by weight per part.

【table】

[Table] (Note) Average particle size is the same as Table 6.

[Table] As is clear from the above table, the coating composition containing ultrafine barium sulfate exhibits significantly higher thixotropy than the coating composition containing comparative barium sulfate or comparative calcium carbonate. ,
On the other hand, the gloss and transparency of the coating film are also outstanding. Although commercially available white carbon exhibits relatively high thixotropy, the gloss of the coating film is significantly reduced.

[Brief explanation of the drawing]

Figure 1 is a graph showing the particle size distribution of barium sulfate of the present invention and comparative barium sulfate, and Figures 2, 3, and 4 are electron micrographs (magnification 100,000 times), Figure 5 is an electron micrograph (5000 times magnification) showing the yellow pigment used in Example 2, and Figure 6 is an electron micrograph showing the yellow pigment used in Example 2 (magnification: 5000 times).
Electron micrograph of paint composition in parts by weight (magnification
5000x), Figure 7 is an enlarged electron micrograph (20000x magnification), and Figure 8 is an electron micrograph of a paint composition containing comparative barium sulfate and the above pigment in an equal ratio (5000x magnification). Figure 9 is an enlarged electron micrograph (magnification: 20,000 times).

Claims (1)

[Claims] 1. A resin containing ultrafine barium sulfate having an average primary particle size of 0.01 to 0.08μ and a particle size distribution in which primary particles with a particle size of 0.1μ or less account for 90% or more of the total. Film-forming composition.