JPS5937304B2 - Titanium dioxide pigment for polymer compositions - Google Patents

Description

[Detailed description of the invention] The present invention relates to titanium dioxide pigments for polymeric compositions.

Titanium dioxide pigments are widely used as colorants for polymer compositions because of their high whiteness and great hiding power.

In recent years, there has been an increase in the number of polymer compositions that are molded at high temperatures, and there has also been an increase in the number of applications in which molded products, such as thin films, are filled with pigments at high concentrations. Titanium dioxide pigments for polymer compositions are required to have a high degree of dispersibility in molten polymers and excellent thermal stability during molding. Various proposals have been made in the past regarding this, but there are still few problems that need to be solved. The present invention aims to solve the above-mentioned problems, and the surface of titanium dioxide particles is coated with a small amount of aluminum hydrate, below a certain amount, and a specific organic compound. It is an object of the present invention to provide a titanium dioxide pigment having general pigment physical properties suitable for use as a polymer composition and excellent thermal stability during molding.

That is, the present invention is characterized in that the surface of the titanium dioxide particles is coated with less than 0.5% aluminum hydrated oxide and less than 1.5% polyhydric alcohol compound as Al2O3 based on the weight of titanium dioxide. This is a titanium dioxide pigment for use in polymer compositions.

The titanium dioxide used in the present invention may have an anatase crystal form or a rutile crystal form, and these may be used as a mixture if necessary. Note that titanium dioxide manufactured by a sulfuric acid method, a chlorine method, and various other methods can be used. In the present invention, the amount of aluminum hydrated oxide coated on the surface of titanium dioxide particles is 0.5 as Al2O3 based on the weight of titanium dioxide.
less than %.

When the coating amount is 0.5% or more, the dispersibility and hiding power decrease, and it is difficult to form a homogeneous and smooth film in thin film forming. Therefore, in such cases, it is difficult to produce high-quality molded products by processing at high temperatures and high pigment concentrations. On the other hand, if the coating amount is too small, the effects of the present invention will not be achieved. The coverage is usually preferably 0.1 to 0.4%, especially 0.1% to 0.4%.
It is preferably 2 to 0.4%. The hydrated oxide of aluminum can be coated with a hydrated oxide of silicon, titanium, etc. within a range that does not impair dispersibility or other properties. The method for coating the surface of titanium dioxide particles with aluminum hydrated oxide is as follows:
This can be carried out by various commonly known methods, for example, adding a water-soluble compound of aluminum to an aqueous slurry of titanium dioxide and then neutralizing it to transfer the hydrated oxide of aluminum to the surface of the particles of titanium dioxide. precipitate on top,
This can be easily carried out by subsequent rinsing and drying.

The polyhydric alcohol compound used in the present invention is a hydrocarbon compound having 10 or less carbon atoms and containing 2 to 4 hydroxyl groups in the molecule, such as trimethylolethane,
Polyols such as trimethylolpropane and pentaerythritol, their alkylene oxide addition products,
Alternatively, examples include etherification products with monofunctional alcohols.

The above-mentioned polyhydric alcohol compounds can be used in combination of two or more thereof, or with various other organic substance processing agents such as organosilicon, alkanolamine, etc. Their coverage is less than 1.5% based on the weight of titanium dioxide. When the coating amount is 1.5% or more, not only is it not economically advantageous, but also a decrease in heat resistance is unavoidable.On the other hand, when the coating amount is too small, the effects of the present invention are not brought about. The coating amount is usually preferably 0.1 to 1%, particularly 0.2 to 0.
．． Preferably it is 6%. In order to coat the surface of the titanium dioxide pigment with the polyhydric alcohol compound, the titanium dioxide coated with the hydrated aluminum oxide obtained as described above is heated using a fluid energy machine such as a micronizer or dinit mill. A polyhydric alcohol compound can be added during pulverization using a pulverizer.

It is also possible to coat the surface of titanium dioxide by uniformly mixing the mixture using a high shear mixer such as a pen shell mixer or a super mixer. The titanium dioxide pigment of the present invention can be widely used in various polymer compositions. For example, it can be blended with various resins such as polyethylene, polypropylene, polystyrene, polyamide, and polyester. The blending amount can be arbitrarily selected depending on the purpose of use, but it is usually 0.1 to 50% by weight, preferably 1% by weight based on the resin.
~20% by weight. As a blending method, a master batch method, a dry blend method, and various other methods can be applied. The titanium dioxide pigment of the present invention is useful as a coloring agent for plastics such as laminates, films, filaments, sheets, and cast products.
It is suitable for extrusion lamination on paperboard or the like at high temperatures, or for high-temperature forming such as forming a thin film using a T-die or an inflation device.

Next, examples according to the present invention will be shown. Example (1) Production example of titanium dioxide pigment The surface of particles of anatase titanium dioxide was coated with predetermined amounts of the inorganic and organic substances shown in Table 1 in accordance with the following method.

A. Method for coating hydrated oxide of aluminum While heating an aqueous slurry of anatase titanium dioxide to about 70°C, an aqueous solution of sodium aluminate was added as Al2O3 in the amount shown in Table 1 (based on the weight of TiO2), and the mixture was stirred for 10 minutes. Thereafter, sulfuric acid was added to adjust the pH of the slurry to 7.0, and the slurry was aged for 1 hour to precipitate the hydrated oxide of aluminum on the surface of the titanium dioxide particles.

After filtering and washing the slurry after this coating treatment,
It was dried for 1 hour. B. Method for coating organic matter When processing with a dinit mill, feed the titanium dioxide coated with the inorganic hydrated oxide obtained in step A above and the prescribed amount of the organic matter listed in Table 1 to the dinit mill, and carry out the coating treatment while pulverizing. did.

In addition, in the case of processing with a pen shell mixer, the coated titanium dioxide of A above was ground in a dinit mill, and then mixed with an organic substance in a pen shell mixer to carry out the coating treatment. (2)
Test example on a polymer composition of titanium dioxide pigment. Whiteness polyethylene resin (Sumikasen F-702-3, manufactured by Sumitomo Chemical KK) 200r, titanium dioxide pigment 10y, and zinc stearate 0.17 were premixed in a V-type mixer.

This premix was passed through an extruder at a die temperature of 145°C.
The sheet was extruded to a width of 5α and a thickness of 1mm, and the color of the sheet was measured using a color difference meter. a. The b value was measured and evaluated using a 5-point method. (The higher the score, the better the whiteness.)
mouth. 200y of a dispersible polyethylene resin (Sumikasen F-702-3, manufactured by Sumitomo Chemical KK), 2f of titanium dioxide pigment, and 0.2f of zinc stearate were added and premixed using a V-type mixer.

This premix was extruded and kneaded at 145°C using an extruder, and this mixture was used to form a film (
A film with a thickness of 50 μm was prepared. The number of coarse particles in the obtained film was measured, and the dispersibility was comparatively evaluated. (The smaller the number, the better the dispersibility.) c. Concealment power. Visible light (5
The transmittance at 50 nm) was measured using a spectrophotometer.

The hiding power was evaluated using the five-point method based on the transmittance value. (The higher the score, the better the hiding power.) 2. Heat-resistant polyethylene resin (Sumikasen L-705, Sumitomo Chemical K
Titanium dioxide pigment 107 and zinc stearate 0.17 were added to 2007 (manufactured by K. K.) and premixed for 20 minutes using a V-type mixer.

The obtained premix was heated to 14°C using an extruder at a die temperature of 14°C.
The L. a. The b value was measured using a color difference meter. ΔE was calculated from the measured values of the sheet with a die temperature of 145° C. and the sheet with a die temperature of 300° C., and the heat resistance was evaluated.

(The smaller the number, the better the heat resistance.)
Ho. Expandable polyethylene resin (Sumikasen L-705,
3007 (manufactured by Sumitomo Chemical KK), titanium dioxide pigment 457, and zinc stearate 0.457 were added and premixed using a V-type mixer.

This premix was extrusion-molded to a thickness of 0.2 mm using an Exzu router at a die temperature of 300°C, and the surface condition of this sheet was visually observed.

The evaluation of whiteness and hiding power in Table 1 was performed using Comparative Example 4 as a standard, setting the value to 3, and evaluating it in 5 levels as shown below.

5: Much better than standard.

4: Better than standard.

3: Standard.

2: Inferior to standard.

1: Very inferior to standard.

As is clear from the results in Table 1, the titanium dioxide pigment for polymer compositions of the present invention has favorable general pigment physical properties such as dispersibility, hiding power, and whiteness in polymer composition systems. It also has excellent thermal stability during molding, such as heat resistance and foamability, and can be processed into a homogeneous and smooth thin film.

Claims (1)

[Claims] 1. A heavy-duty material characterized in that the surface of titanium dioxide particles is coated with less than 0.5% aluminum hydrated oxide and less than 1.5% polyhydric alcohol compound as Al_2O_3 based on the weight of titanium dioxide. Titanium dioxide pigment for coalescent compositions.