R1800-SK

R1800-SK is the white type among the R1800 three-type hyperdispersants. The documentation records "R1800-SK hyperdispersant is built on R1800-S by incorporating ester functional groups, which improves the yellowing resistance and weather resistance of R1800-SK in plastic products, and it is mainly used for rubber & plastics white masterbatch"; the one-line positioning in the official product data is "dedicated to white masterbatch, with improved yellowing resistance and weather resistance", and the mechanism field is "chemical dispersion + ester-based anti-yellowing". (Data source: product handbook / official product data)

The official application list is white masterbatch, metal powder color masterbatch, powder coatings, oil-based coatings, and titanium dioxide surface treatment; the chapter title in the product handbook is "Surface Treatment of Titanium Dioxide by R1800-SK Hyperdispersant and Its Application in Color Masterbatch" — most of the public data for this grade comes from this dedicated study. (Data source: product handbook / official product data)

Why titanium dioxide requires surface treatment: the documentation records "finer pigment particles tend to agglomerate together, producing large particles that affect product quality, and therefore cannot be used directly and must undergo dispersion treatment". The dispersion process is divided into three parts: wetting, comminution (dispersion), and stabilization after comminution (encapsulation); surface treatment is "the process of stabilizing the pigment after comminution" — depositing and coating monomolecular or multimolecular substances on the particle surface. (Data source: product handbook)

The same family's R1800-S and this grade share the same set of routine physicochemical entries (appearance, odor, amine value, density, flash point, viscosity, acid value, dispersity); this grade additionally records pH value and titanium dioxide-specific data. The difference in grade selection is not reflected in the routine physicochemical table, but in the application list, the dedicated experiments, and the temperature behavior — the way to work with SK is: use SK for white systems, and execute temperature conditions and process conditions with 70℃ as the dividing line. (Data source: product handbook / official product data)

• Yellowing resistance and weather resistance — ester functional groups are incorporated on the basis of S, dedicated to the yellowing resistance and weather resistance requirements of white plastic products; the hue darkens as the temperature changes, and "when put into a product for use, it has no hue".
• Dedicated titanium dioxide conclusions — treating titanium dioxide with this product "greatly improves the dispersion performance of the pigment. Moreover, it does not change the properties of the pigment; on the contrary, the whiteness and processing performance of the titanium dioxide are also improved".
• Tinting strength data (experimental range 0%–2.0%) — lightness and Taube whiteness are higher than those of untreated titanium dioxide at every dosage; at a dosage of 1.6%, lightness is 90.18, Taube whiteness is 77.76, and yellowness is 3.84 (all three are the optimum points in the experimental series).
• Hiding power (optical density) — under standard film thickness 0.02mm, constant PH=6.8, and 70℃, the optical density is at its maximum of 0.386 at a dosage of 1.6%; further increasing the dosage causes a sharp decrease due to "bridging flocculation".
• Dispersibility comparison — titanium dioxide treated at 1.6% (PH=6.8, 70℃) is dispersed relatively uniformly with smaller particles; untreated titanium dioxide undergoes severe agglomeration.
• Rheology and processing — "owing to the good compatibility of the solubilizing chains with the carrier, the flow properties of the masterbatch can be changed"; the dispersibility, whiteness, surface gloss, hiding power, and processing performance of white masterbatch are all improved.
• Compatibility and relative performance — "compatibility with all rubbers and plastics is very good, lubricating performance is 26 times that of wax, and dispersing performance is 113 times that of wax"; read literally, this is an item-by-item comparison of the two items "lubrication / dispersion", not an overall performance multiple, and when cited it should be used only as an item-by-item comparison.

The molecule of this product is structurally divided into two parts: one part is the anchoring group, and the other is the solubilizing chain (dispersion). The anchoring group is -COOH, which "through ionic bonds, hydrogen bonds, and van der Waals forces, adsorbs tightly onto the pigment surface, preventing desorption of the R1800-SK hyperdispersant"; the solubilizing chain directly determines the stability of the dispersed pigment in the solvent. (Data source: product handbook / official product data)

The temperature behavior has a clear dividing line: "below 70℃ the coating layer does not melt, while above 70℃ it begins to melt and convert into an ionic coupling agent, improving the compatibility of titanium dioxide with the resin". This explains the two prerequisites for using this grade: surface treatment must reach a process temperature near 70℃; when the temperature is insufficient, the coating layer does not convert, and the effect of improved interfacial compatibility cannot be realized. (Data source: product handbook)

In titanium dioxide color paste: the particle surface accumulates charges, which readily combine with the anchoring groups of this product (-COOH), forming a firm protective layer on the titanium dioxide particle surface; then, through the steric barrier action of the solubilizing chains (hydrocarbon chains), the titanium dioxide achieves a stably dispersed effect. "When pigment particles adsorbed with R1800-SK hyperdispersant approach one another, the repulsion of the adsorbed layers causes the particles to spring apart from one another, thereby achieving stable dispersion of the pigment particles in the medium". (Data source: product handbook)

For treatment at the titanium dioxide plant, there is an additional process recommendation: "if treated at the titanium dioxide plant, dilution with an alcohol solvent is recommended, the purpose being to distribute the amount more uniformly throughout the powder". (Data source: product handbook)

1. Anchoring adsorption — protective layer formationThe anchoring group -COOH adsorbs onto the titanium dioxide particle surface via ionic bonds, hydrogen bonds, and van der Waals forces, preventing desorption of the dispersant; the active sites on the particle surface are covered, and the tendency to agglomerate is suppressed.
2. 70℃ phase transition — the coating layer melts and converts into an ionic coupling agentBelow 70℃ the coating layer does not melt; above 70℃ it begins to melt and convert into an ionic coupling agent, improving the compatibility of titanium dioxide with the resin. This is the direct basis for setting the surface treatment process temperature at 70℃.
3. Steric barrier — stable dispersionThe solubilizing chains (hydrocarbon chains) extend in the medium to form a steric barrier; when particles approach, the adsorbed layers repel and spring apart from one another, and the pigment remains stably dispersed in the medium.
4. Process conditions — surface treatment and masterbatch preparationThe suitable surface treatment process conditions recorded in the documentation (PH=6.8, 70℃, dosage 0.5%, with the experimentally optimal dosage being 1.6%); for treatment at the titanium dioxide plant, dilution with an alcohol solvent is recommended. When preparing white masterbatch, follow the experimental feeding order: first stir the titanium dioxide and this product at high speed, then add the carrier resin when the temperature reaches about 100℃, and pelletize after uniform mixing.

The table below summarizes the physicochemical indicators and titanium dioxide-specific data for R1800-SK as recorded in the product handbook and official product data. The values in the table are as recorded in the documentation; before batch use, it is recommended to carry out small-scale trials together with your own titanium dioxide grade and formulation.

Notes: (1) "Lubricating performance is 26 times that of wax, dispersing performance is 113 times that of wax" is an item-by-item comparison of the two items lubricating / dispersing (series-level record), and is not an overall performance multiple; (2) the titanium dioxide-specific data (optimal process, lightness, Taube whiteness, yellowness) come from the specific experiments for this grade, with an experimental range of dosage 0.3%–2% (constant PH=6.8, 70℃); (3) the carbon black-specific data of the same-series SH (optical density 0.487, blackness series) do not represent this grade and have not been carried over. (Data source: product handbook / official product data)

The dosage for this grade has two levels in the documentation: the process-recommended value for surface treatment (0.5%) and the optimum value obtained from the specific experiments (1.6%). The two have different bases and are kept side by side; this page makes no choice between them — in use, take them separately according to the goal (confirmation of process conditions / optimization of effect).

Dosage principle (series-level record): the finer the powder, the higher the oil absorption value and the larger the specific surface area, the higher the amount of dispersant added; the specific conclusion for this grade additionally records "the dosage of the R1800-SK hyperdispersant affects surface treatment, and treatment of titanium dioxide is best at a dosage of 1.6%; surface treatment is best at a temperature of 70℃".

To be verified: (1) two dosages coexist — the overview and official product data record "dosage 0.5%" (process-recommended value), while the experiments and the conclusion record "treatment of titanium dioxide is best at a dosage of 1.6%" (experimental optimum value); the correspondence between the objects and the judging criteria of the two is not indicated, and this page presents them side by side as-is without making a choice. (2) the original text records the experimental observation condition as "ethanol 2%" (conditions for preparing the dispersibility control sample); the wording is brief and has not been included in the main text. (3) the above are all values recorded in the documentation; for actual production, please carry out small-scale trials with your own powder, equipment and formulation to confirm.

The official application list is white masterbatch, metallic powder color masterbatch, powder coatings, oil-based coatings and titanium dioxide surface treatment; the product handbook additionally records the titanium dioxide-specific experiments and grade-selection recommendations. Item by item as follows:

White masterbatch

Main use of this grade (the series source states "mainly used for rubber and plastic white masterbatch"); when this product is used to treat titanium dioxide to prepare white masterbatch, dispersibility, whiteness, surface gloss, hiding power and processing performance are all greatly improved.

Titanium dioxide surface treatment

Main subject of the specific experiments: suitable process conditions PH=6.8, 70℃; the dosage has two bases, 0.5% (process-recommended value) and 1.6% (experimental optimum value). For treatment at the titanium dioxide plant, dilution with an alcohol solvent is recommended.

Metallic powder color masterbatch

Listed in the official application list; the documentation gives no separate data for this scenario, so confirm by small-scale trials following the same process system.

Powder coatings / oil-based coatings

Listed in the official application list; the two overlap with the list for the same-series R1800-S, and the documentation gives no either/or rule for the overlapping scenarios, so small-scale trials are recommended according to the coloring system.

Compatibility range

The R1800 series "has very good compatibility with all rubbers and plastics" (series description record).

Grade selection and synergy

The documentation gives grade-selection recommendations based on pigment fineness and oil absorption value; examples of recommended grades include R1800-SK, R1800-SH, R1618, R900A, etc.; the finer the powder, the higher the oil absorption value and the larger the specific surface area, the higher the amount of dispersant.

Field issues & application examples (as recorded in the source material)

The three R1800 types are all paste-form hyperdispersants, split by color line (S color / SK white / SH black); the differences do not lie in the routine physicochemical entries but in the application lists, the dedicated experiments, and the temperature behavior. The comparison follows:

Reading notes: (1) The routine physicochemical entries for S and SK are the same set (appearance, odor, amine value, density, flash point, viscosity, acid value, dispersity), while SK additionally records pH and the titanium dioxide dedicated test; (2) "lubrication 26 times / dispersion 113 times" is as recorded on the SK page (a series-level record), and this page cites it only as an item-by-item lubrication / dispersion comparison; (3) The values in the comparison table are as recorded in the source materials. (Data source: product handbook / official product data)

This product is a paste, and its performance is directly related to temperature, mixing sequence, and the dosage basis. The following points come one by one from the recorded data.

The data on this page come from two kinds of sources, and each item can be traced back:

• Product handbook: the full R1800-SK entry (overview / main components / physicochemical properties / theoretical analysis / experimental section / results and discussion / conclusion / addition level / packaging / storage); the comparison section for R1800-S and R1800-SH; the series introduction and product catalog section; the color masterbatch selection section.
• Official product data: all fields for R1800-SK (name, category, positioning, description, mechanism, applications, physicochemical parameters, main components, functional description, recommended dosage); the series entry (list of representative models, series description).

Not covered by the source material (not written on this page — to be added later)

• Compliance certification statements (such as RoHS, REACH, etc.), shelf life, and safety operating data (MSDS level): not recorded in the available sources.
• Two dosage bases coexist (recommended process value 0.5% / experimental optimum value 1.6%): the objects and the criteria are not annotated with a correspondence.
• The experimental observation condition "ethanol 2%" is stated rather briefly: if it is to be cited externally, verification is recommended first.