Water-based white color paste with high solid content

Abstract

The invention provides water-based white color paste with high solid content. The water-based white color paste comprises titanium dioxide powder; an anionic polyelectrolyte; an electrical modifier; an acid-base regulator; and water; wherein on the basis of the total weight of the water-based white color paste, the content of the titanium dioxide powder is 65-80 weight percent, and the weight ratio of the titanium dioxide powder to the anionic polyelectrolyte is 130-180.

Description

Technical Field

[0001] This disclosure relates to a high-solids-content water-based white pigment, and more particularly to a high-solids-content water-based white pigment for use in digital textile printing inks. Background Technology

[0002] White pigment is typically used when printing white or color prints on dark or light-colored fabrics. Besides creating white prints, white pigment can also enhance the vibrancy of color prints when applied to color prints.

[0003] Although there are currently white pigments available on the market for preparing digital textile printing inks, such as using modified titanium dioxide powder or undried titanium dioxide powder as pigments for white pigments, most commercially available water-based white pigments have the disadvantage of sedimentation, resulting in poor dispersibility or poor storage stability, which affects their application range.

[0004] In view of this, there is an urgent need to develop a water-based white pigment that can improve the above-mentioned shortcomings in order to meet the needs of digital textile printing ink applications. Summary of the Invention

[0005] The main objective of this disclosure is to provide a high-solids-content aqueous white pigment paste with good dispersibility or storage stability.

[0006] The high solids content aqueous white pigment of this disclosure includes: titanium dioxide powder; anionic polyelectrolyte; an electrical modifier; an acid-base modifier; and water; wherein, based on the total weight of the aqueous white pigment, the content of titanium dioxide powder is 65 to 80% by weight, and the weight ratio of titanium dioxide powder to anionic polyelectrolyte is between 130 and 180.

[0007] This disclosure discloses a high-solids-content aqueous white pigment paste, which improves the dispersibility and storage stability of the aqueous white pigment paste by using an anionic polyelectrolyte. More specifically, by adding a small amount of anionic polyelectrolyte, the sedimentation problem of titanium dioxide powder (pigment) can be improved; even if the solids content of titanium dioxide powder (pigment) is very high and the weight ratio of titanium dioxide powder to anionic polyelectrolyte (titanium dioxide powder / anionic polyelectrolyte, P / D) is also large, the sedimentation problem of titanium dioxide powder can still be effectively improved, thus providing an aqueous white pigment paste with good dispersibility or storage stability.

[0008] In one embodiment, the weight ratio of titanium dioxide powder to anionic polyelectrolyte (titanium dioxide powder / anionic polyelectrolyte, P / D) may be between 130 and 180, for example, between 135 and 180, 135 and 175, 140 and 175, 140 and 170, 145 and 170 or 145 and 165.

[0009] In one embodiment, the content of titanium dioxide powder may be 65 to 80% by weight, for example, 65 to 75% by weight, based on the total weight of the aqueous white pigment.

[0010] In one embodiment, the content of anionic polyelectrolyte can be 0.3 to 0.7% by weight, based on the total weight of the aqueous white pigment, for example, 0.3 to 0.65%, 0.35 to 0.65%, 0.35 to 0.6%, 0.4 to 0.6%, or 0.4 to 0.55% by weight.

[0011] In one embodiment, the content of the electrochemical modifier may be 0.25 to 0.6% by weight, based on the total weight of the aqueous white pigment, for example, 0.25 to 0.55%, 0.3 to 0.55%, 0.3 to 0.5%, 0.35 to 0.5%, or 0.4 to 0.5% by weight.

[0012] In one embodiment, the content of the acid-base adjuster can be 0.1 to 0.4% by weight, based on the total weight of the aqueous white pigment, for example, 0.1 to 0.3%, 0.15 to 0.3%, 0.15 to 0.25%, or 0.2 to 0.25% by weight.

[0013] In one embodiment, the titanium dioxide powder is a surface-modified titanium dioxide powder. In another embodiment, the titanium dioxide powder is an alumina-modified titanium dioxide powder.

[0014] In one embodiment, the anionic polyelectrolyte may be an anionic polyelectrolyte comprising phosphate, carboxylate, or sulfonate groups. In another embodiment, the anionic polyelectrolyte may be polyacrylic acid (PAA), polystyrene sulfonate (PSS), polyacrylamide sulfonate (PAMPS), sodium carboxymethyl cellulose (CMC), sulfonated phenolic resin (SPR), polyvinyl sulfonic acid (PVSA), its salts (e.g., lithium, sodium, potassium, or ammonium salts), or combinations thereof. In another embodiment, the anionic polyelectrolyte may be sodium polyacrylate (PAAS).

[0015] In one embodiment, the molecular weight of the anionic polyelectrolyte can be from 1,000 to 15,000 g / mol, for example, from 1,200 to 15,000 g / mol or from 1,200 to 8,000 g / mol.

[0016] In one embodiment, the electrical modifier may be aluminum hydroxyaluminate (AlO(OH)).

[0017] In one embodiment, the acid-base adjuster may be sodium metasilicate (Na2SiO3).

[0018] Furthermore, the high-solids-content aqueous white pigment of this disclosure is prepared by grinding a mixture comprising titanium dioxide powder, anionic polyelectrolyte, charge modifier, acid-base modifier, and water. The grinding process can be media grinding, basket grinding, or high-speed dispersion, and the aforementioned grinding processes can be used individually or in combination.

[0019] Furthermore, the high-solids-content aqueous white pigment of this disclosure may possess at least one of the following properties:

[0020] The surface tension of the water-based white pigment is greater than 60 mN / m, for example, greater than 65 mN / m, wherein the surface tension of the water-based white pigment is measured when the water-based white pigment is diluted to a solid content of 10 wt%.

[0021] The isoelectric point (IEP) of aqueous white pigments is pH 2.3 to 3.2, for example, pH 2.4 to 3.1; and

[0022] The absolute value of the zeta potential of the aqueous white pigment at a pH greater than 4.5 (e.g., greater than 4.5 and less than 13) is greater than or equal to 30 mV (|±30 mV|).

[0023] Furthermore, the high-solids-content water-based white pigment of this disclosure can be applied to digital textile printing. Attached Figure Description

[0024] The above and other objects, features and advantages of this disclosure will become clearer from the following description of embodiments of this disclosure with reference to the accompanying drawings, in which:

[0025] Figure 1 The graphs show the isoelectric point measurement results of Embodiments 1 to 3 and Comparative Examples 1 to 2 of this disclosure;

[0026] Figure 2 The diagram shows the isoelectric point measurement results of Embodiments 4 to 6 and Comparative Examples 1 to 2 of this disclosure. Detailed Implementation

[0027] The following are specific embodiments illustrating the implementation of this disclosure. Those skilled in the art can easily understand other advantages and effects of this disclosure from the content disclosed in this specification. This disclosure can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified and changed for different viewpoints and applications without departing from the spirit of this disclosure.

[0028] In this document, unless otherwise specified, the term "characteristic A" or "and / or" and "characteristic B" means that A exists alone, B exists alone, or A and B exist simultaneously; the term "characteristic A" and "and" or "and" and "and" and "characteristic B" means that A and B exist simultaneously; the terms "including", "containing", "having", and "containing" refer to, but are not limited to, these.

[0029] Additionally, if a value lies between a first value and a second value, the value can be the first value, the second value, or another value between the first value and the second value.

[0030] Furthermore, in this document, the term "approximately" refers to a range including ±10% of the given value, and more specifically, ±5%. The quantities given here are approximate, meaning that the term "approximately" is implied even without specific explanation.

[0031] This disclosure will be illustrated in more detail by way of examples, but these examples are not intended to limit the scope of protection of this disclosure. Unless otherwise specified, in the following comparative examples and embodiments, temperatures are in Celsius, and parts and percentages are by weight. The relationship between parts by weight and parts by volume is the same as the relationship between kilograms and liters.

[0032] The components used in the following embodiments and comparative examples are shown in Table 1 below.

[0033] Table 1

[0034]

[0035] Comparative Example 1

[0036] 60.0 wt% TiO2 pigment powder was dissolved in 40.0 wt% pure water using a mechanical stirrer (NETZSCH MasterMix). Then, it was ground in a bead mill (SUNIN MACHINE CO., LTD. GOLDEN-MILL) using yttrium zirconium grinding beads with a diameter of 0.3 to 0.4 mm to obtain an aqueous white pigment paste of Comparative Example 1.

[0037] Comparative Example 2

[0038] 60.0 wt% TiO2 pigment powder was dissolved in a premix of 0.18 wt% sodium metasilicate, 0.37 wt% alumina hydroxyl, and the remainder being pure water, and then uniformly mixed using a mechanical stirrer (NETZSCH MasterMix). The mixture was then ground in a bead mill (SUNINMACHINE CO., LTD. GOLDEN-MILL) using yttrium zirconium grinding beads with a diameter of 0.3 to 0.4 mm to obtain an aqueous white pigment paste of Comparative Example 2.

[0039] Example 1

[0040] 65.0 wt% TiO2 pigment powder was dissolved in a premix of 0.20 wt% sodium metasilicate, 0.40 wt% alumina hydroxyl, 0.44 wt% sodium polyacrylate, and the remainder being pure water, and then uniformly mixed using a mechanical stirrer (NETZSCH MasterMix). The mixture was then ground in a bead mill (SUNIN MACHINE CO., LTD. GOLDEN-MILL) using yttrium zirconium grinding beads with a diameter of 0.3 to 0.4 mm to obtain the aqueous white pigment paste of Example 1.

[0041] Examples 2 to 6

[0042] The aqueous white pigments of Examples 2 to 6 were prepared according to the component contents listed in Tables 2 and 3 below, using the preparation method described in Example 1.

[0043] Zeta potential measurement

[0044] The ground aqueous white pigments of the examples and comparative examples were prepared into 10 ppm dispersions, and the pH values ​​were adjusted to 2-12. Eight to ten pH points were measured, and the interfacial potentials were measured using a Malvern Zetasizer Nano ZS. The isoelectric points (IEPs) were obtained by plotting the results. The results are shown in Tables 2 and 3 below.

[0045] Surface tension

[0046] The ground water-based white pigments of the examples and comparative examples were diluted with water to a solid content of 10 wt%, and measured using a KYOWA SURFACE TENSIOMETER CBVP-A2. The results are shown in Tables 2 and 3 below.

[0047] Table 2 (Composition unit: wt%)

[0048]

[0049] Please refer to Table 2 above and Figure 1 The results. To meet the pH range of 7 to 9 for white ink applications, Comparative Example 1 used a commercially available surface-modified TiO2 aqueous solution (isoelectric point 9.1, pH stability range less than 6.8 or greater than 10.3) for electrical adjustment. When an electrical adjuster (alumina hydroxyaluminate) and an acid-base adjuster (sodium metasilicate) were added, as shown in Comparative Example 2, although the IEP decreased from 9.1 to 7.8, its stable suspension pH still did not fall within the ink application range. When an anionic polyelectrolyte (sodium polyacrylate, PAAS) was added, as shown in Examples 1 to 3, the IEP significantly decreased to 3. Furthermore, from Figure 1 It is known that when the pH value is greater than 4.5, the aqueous white pigments of Examples 1 to 3 have high and stable suspension stability. Regardless of whether the solid content exceeds 65% (Example 1) or 70% (Example 2), or even when the solid content is increased to 75% (Example 3), the TiO2 particles in the aqueous white pigments of this disclosure still maintain high suspension stability and will not separate or settle.

[0050] Furthermore, the aqueous white pigment of this disclosure exhibits superior surface tension characteristics. The greater the surface tension of the aqueous white pigment (e.g., the surface tension of the aqueous white pigment of this disclosure can be greater than 60 mN / m, or even greater than 70 mN / m), the more diverse the selectivity of the dispersant (e.g., the dispersant used in formulating inks) becomes, which helps to improve the splashing problem caused by excessive surface tension differences between different substrates.

[0051] Table 3 (Composition unit: wt%)

[0052]

[0053] Please refer to Table 3 above and Figure 2 The results verified the effect of the molecular weight of anionic polyelectrolytes on dispersion stability. In the examples, PAAS with molecular weights of 1200 (Example 4), 8000 (Example 5), and 15000 (Example 6) were used to adjust the interfacial potential / IEP of TiO2 particles. The results showed that the anionic polyelectrolytes of the above molecular weights could reduce the IEP to 3.1, 2.7, and 2.4, respectively. However, as the molecular weight of the anionic polyelectrolyte increased, the pH at which the interfacial potential was below -30 mV shifted from 4.5 to 5.3 or even above 6.2; that is, when adding PAAS with a molecular weight of 15000, the pH needed to be above 6.2 to achieve better suspension stability. The above results show that as the molecular weight of the anionic polyelectrolyte increases, the pH value at which better suspension stability is obtained also increases. Therefore, when the molecular weight of the anionic polyelectrolyte is within a certain range, good suspension stability can be achieved.

[0054] In summary, the high-solids-content aqueous white pigment provided by this disclosure maintains good stability (the absolute value of the interfacial potential can be greater than or equal to 30 mV (|ζ|≥30mV)) even when the solid content of the titanium dioxide powder exceeds 65% by weight; therefore, the applicability of the aqueous white pigment can be significantly improved. On the other hand, the high-solids-content aqueous white pigment provided by this disclosure has an isoelectric point (IEP) of approximately pH 3; and the absolute value of the interfacial potential can be greater than or equal to 30 mV (|ζ|≥30mV) after the pH is greater than 4.5; therefore, the range of pH values ​​that can be selected for the aqueous white pigment formulation can be significantly expanded. Furthermore, the high-solids-content aqueous white pigment provided by this disclosure has high surface tension characteristics (> 60 mN / m); therefore, the surface tension adjustment capability of the aqueous white pigment formulation can be significantly improved.

[0055] The above embodiments are merely illustrative examples for ease of explanation. The scope of the rights claimed in this disclosure should be determined by the claims, and not limited to the above embodiments.

[0056] The specific embodiments described above further illustrate the purpose, technical solutions, and beneficial effects of this disclosure. It should be understood that the above descriptions are merely specific embodiments of this disclosure and are not intended to limit this disclosure. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this disclosure should be included within the protection scope of this disclosure.

Claims

1. A high-solids-content water-based white pigment, comprising: Titanium dioxide powder; Anionic polyelectrolytes; Electrical modifier; pH adjuster; as well as water; Based on the total weight of the water-based white pigment, the content of titanium dioxide powder is 65 to 80% by weight, and the weight ratio of titanium dioxide powder to anionic polyelectrolyte is between 130 and 180.

2. The aqueous white pigment according to claim 1, wherein the content of the anionic polyelectrolyte is 0.3 to 0.7% by weight, the content of the electrical modifier is 0.25 to 0.6% by weight, and the content of the acid-base modifier is 0.1 to 0.4% by weight.

3. The aqueous white pigment paste according to claim 1, wherein the anionic polyelectrolyte is an anionic polyelectrolyte containing phosphate, carboxylate or sulfonate groups.

4. The aqueous white pigment paste according to claim 1, wherein the anionic polyelectrolyte is polyacrylic acid, polystyrene sulfonic acid, polyacrylamide sulfonic acid, sodium carboxymethyl cellulose, sulfonated phenolic resin, polyvinyl alcohol sulfonic acid, their salts or combinations thereof.

5. The aqueous white pigment paste according to claim 1, wherein the anionic polyelectrolyte is sodium polyacrylate.

6. The aqueous white pigment paste according to claim 1, wherein the molecular weight of the anionic polyelectrolyte is 1000 to 15000 g / mol.

7. The aqueous white pigment according to claim 1, wherein the electrical modifier is aluminum hydroxide.

8. The aqueous white pigment according to claim 1, wherein the acid-base adjuster is sodium metasilicate.

9. The water-based white pigment according to claim 1, wherein the surface tension of the water-based white pigment is greater than 60 mN / m.

10. The aqueous white pigment according to claim 1, wherein the isoelectric point of the aqueous white pigment is pH 2.3 to 3.

2.

11. The aqueous white pigment according to claim 1, wherein the absolute value of the interfacial potential of the aqueous white pigment is greater than or equal to 30 mV when the pH is greater than 4.5.

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