Inorganic Pigments and Titanium Dioxide Selection Ratio: A Practical Guide for Plastics and PVC Applications

When producing plastic products, PVC profiles, pipes, masterbatch, films, cables, sheets, and other polymer products, choosing the right inorganic pigments and titanium dioxide (TiO₂) is essential for achieving the desired color, opacity, weather resistance, and processing performance.

Titanium dioxide is one of the most widely used white pigments because of its excellent hiding power and brightness. However, titanium dioxide is not always used alone. Depending on the application, it may be combined with other inorganic pigments to adjust color, cost, opacity, and performance.

This guide explains how to select inorganic pigments and titanium dioxide, recommended addition ratios, and the key factors to consider when formulating plastic and PVC products.

What Are Inorganic Pigments?

Inorganic pigments are coloring materials generally based on mineral or metal compounds. Compared with many organic pigments, inorganic pigments are known for their excellent:

Heat resistance
Weather resistance
UV resistance
Chemical resistance
Lightfastness
Durability
Processing stability

Common inorganic pigments used in plastics and PVC include:

Titanium Dioxide (TiO₂)
Iron Oxide Red
Iron Oxide Yellow
Iron Oxide Black
Chromium Oxide Green
Ultramarine Blue
Complex Inorganic Colored Pigments (CICP)

These pigments are widely used in PVC pipes, profiles, flooring, plastic sheets, masterbatch, construction materials, coatings, and other applications.

Why Is Titanium Dioxide Important?

Titanium dioxide (TiO₂) is the most important white pigment used in many plastic and PVC formulations.

Its main advantages include:

1. High Whiteness

TiO₂ provides a clean and bright white appearance, making it suitable for white PVC profiles, pipes, sheets, films, and injection-molded products.

2. Excellent Opacity

Because of its high refractive index, titanium dioxide can effectively scatter light and improve the hiding power of the formulation.

3. UV Resistance

High-quality rutile titanium dioxide can provide excellent resistance to UV exposure, making it suitable for outdoor plastic products.

4. Good Weather Resistance

For outdoor applications such as PVC profiles, roofing sheets, pipes, and construction products, the correct TiO₂ grade can significantly improve long-term appearance and durability.

5. Excellent Dispersion

A suitable surface-treated TiO₂ grade can provide better dispersion in PVC and other polymer systems, helping manufacturers achieve consistent color and product quality.

Titanium Dioxide Selection: Rutile vs. Anatase

One of the first decisions when selecting TiO₂ is choosing between rutile titanium dioxide and anatase titanium dioxide.

Property    Rutile TiO₂    Anatase TiO₂
Refractive Index    Higher    Lower
Opacity    Excellent    Good
Weather Resistance    Excellent    Moderate
Whiteness    Excellent    Very good
Outdoor Applications    Highly suitable    Less suitable
Cost    Usually higher    Usually lower
Typical Applications    PVC profiles, pipes, masterbatch, coatings    General plastics, indoor products

For outdoor PVC and plastic applications where weather resistance and opacity are important, rutile TiO₂ is generally the preferred choice.

For cost-sensitive indoor applications, anatase TiO₂ may be considered depending on the required performance.

Recommended Titanium Dioxide Addition Ratio

There is no single universal TiO₂ dosage because the optimal ratio depends on the polymer, product color, required opacity, processing conditions, and pigment concentration.

As a general starting point:

Application    Typical TiO₂ Addition
Light-colored plastic products    1–3%
White plastic products    2–5%
High-opacity PVC products    3–8%
White masterbatch    20–70% TiO₂ in masterbatch
Highly opaque applications    5–10%+

These figures should be treated as starting ranges rather than fixed formulations. Actual dosage should be determined through laboratory testing and production trials.

Using excessive TiO₂ does not necessarily produce proportionally better opacity. After reaching a certain concentration, additional TiO₂ may provide limited improvement while increasing formulation cost and potentially affecting processing or dispersion.

How to Select the Ratio of Inorganic Pigments and TiO₂

When TiO₂ is combined with colored inorganic pigments, the ratio should be determined according to the target color.

For example, when producing a light gray PVC product, a formulation may use:

TiO₂ + Iron Oxide Black

The TiO₂ provides whiteness and opacity, while the black pigment adjusts the shade.

For beige or brown products, manufacturers may combine:

TiO₂ + Iron Oxide Yellow + Iron Oxide Red + Iron Oxide Black

The exact ratio depends on the desired color.

A typical formulation development process is:

Base Resin → TiO₂ → Main Inorganic Pigment → Shade Adjustment → Dispersion Test → Color Measurement → Production Trial

Rather than using a fixed pigment ratio for every product, manufacturers should adjust the formulation according to the target color and application requirements.

Example: TiO₂ and Iron Oxide Pigment Selection

Suppose a manufacturer wants to produce a light beige PVC profile.

A possible formulation strategy is:

Titanium Dioxide: main white pigment
Iron Oxide Yellow: primary yellow tone
Iron Oxide Red: warm tone adjustment
Iron Oxide Black: small amount for shade correction

For example, a trial formulation could start with:

TiO₂ 90–98% of the total pigment package

and:

Iron Oxide pigments 2–10% of the pigment package

The exact ratio should then be adjusted according to the required color.

This method is generally more practical than simply increasing the amount of colored pigment because TiO₂ controls both whiteness and opacity.

How Much Titanium Dioxide Should Be Used in PVC?

For PVC applications, the TiO₂ dosage depends heavily on the product.

PVC Pipes

For white PVC pipes, TiO₂ may typically be used at approximately:

2–5%

Higher levels may be considered when greater opacity, whiteness, or outdoor durability is required.

PVC Profiles

For white or light-colored PVC profiles, manufacturers commonly use:

2–6% TiO₂

For outdoor profiles, a high-quality rutile grade with good weather resistance is generally preferred.

PVC Sheets

Depending on thickness and opacity requirements:

2–8% TiO₂

may be used as a starting range.

Plastic Masterbatch

White masterbatch normally contains a much higher TiO₂ concentration, often:

20–70% TiO₂

The final dosage in the polymer depends on the masterbatch concentration and required opacity.

Factors That Affect TiO₂ Dosage

The correct titanium dioxide ratio cannot be determined by color alone.

Several factors should be considered.

1. Product Thickness

Thin films generally require stronger hiding power because the substrate can easily show through.

Thicker products may require less TiO₂ to achieve the same visual opacity.

2. Base Resin

Different polymers have different optical and processing characteristics.

The optimal TiO₂ dosage for PVC may not be suitable for:

PE
PP
ABS
PS
EVA
TPU
3. Product Color

White products require TiO₂ as the main pigment.

Light colors usually require a combination of TiO₂ and a small amount of colored pigment.

Dark colors may require much less TiO₂.

4. Outdoor or Indoor Use

Outdoor products need stronger resistance to:

UV radiation
Heat
Weathering
Moisture
Long-term color change

For these applications, pigment quality can be more important than simply increasing the pigment dosage.

5. Dispersion

Even high-quality TiO₂ cannot perform properly if it is poorly dispersed.

Poor dispersion can cause:

Color variation
Lower opacity
Surface defects
Pigment agglomeration
Reduced processing efficiency

Therefore, pigment dispersion should always be evaluated during formulation development.

Is More Titanium Dioxide Always Better?

No.

One common mistake is assuming that increasing TiO₂ will continuously improve whiteness and opacity.

In reality, pigment concentration has an optimal range.

Once the formulation reaches a sufficient pigment concentration, further increases may result in:

Higher raw material costs
Poorer dispersion
Increased viscosity
Processing difficulties
Limited additional opacity improvement

Therefore, the goal should be to find the lowest TiO₂ dosage that achieves the required whiteness, opacity, durability, and color stability.

This approach can help manufacturers reduce production costs without sacrificing product quality.

How to Choose a High-Quality Titanium Dioxide Grade

When purchasing TiO₂ for plastic and PVC applications, buyers should evaluate more than price.

Important technical parameters include:

TiO₂ Purity

Higher purity generally provides more consistent pigment performance.

Particle Size

Particle size and particle-size distribution have a significant effect on light scattering, opacity, and dispersion.

Surface Treatment

Surface-treated TiO₂ can improve dispersion and compatibility with different polymer systems.

Whiteness

High whiteness is important for white and light-colored products.

Tinting Strength

Higher tinting strength can allow manufacturers to achieve the desired opacity with lower pigment dosage.

Weather Resistance

For outdoor products, weathering performance should be carefully evaluated.

Heat Resistance

The pigment must remain stable under the processing temperature of the polymer.

Inorganic Pigments vs. Organic Pigments

The choice between inorganic and organic pigments depends on the application.

Property    Inorganic Pigments    Organic Pigments
Heat Resistance    Generally excellent    Depends on pigment
Weather Resistance    Generally excellent    Depends on pigment
Lightfastness    Generally excellent    Varies
Color Range    Moderate    Very wide
Brightness    Moderate to high    Often very high
Opacity    Often high    Varies
Cost    Varies    Varies

For PVC profiles, pipes, construction materials, and outdoor plastics, inorganic pigments are often selected when long-term durability is a priority.

For bright and highly saturated colors, organic pigments may provide advantages.

Practical Pigment Selection Formula

When developing a new formulation, manufacturers can use the following approach:

Step 1: Define the Target Color

Determine the required:

L*
a*
b*
Whiteness
Opacity
Step 2: Select the Main Pigment

For white products:

TiO₂

For red:

Iron Oxide Red

For yellow:

Iron Oxide Yellow

For black:

Iron Oxide Black

Step 3: Determine the Initial Dosage

Start with a laboratory formulation rather than directly using a high dosage.

Step 4: Adjust the Shade

Small amounts of secondary pigments can be added to correct the color.

Step 5: Test Dispersion

Check pigment dispersion under actual processing conditions.

Step 6: Test Weather and Heat Resistance

For outdoor products, accelerated weathering tests should be considered.

Step 7: Optimize Cost

After meeting the required performance, reduce unnecessary pigment loading to achieve a better cost-performance ratio.

Common Questions About TiO₂ and Inorganic Pigments
What is the best TiO₂ for PVC?

For outdoor PVC products, rutile titanium dioxide is generally preferred because of its high opacity and weather resistance.

What is the normal TiO₂ dosage in PVC?

A common starting range is approximately 2–5%, although some high-opacity applications may require more.

Can TiO₂ be mixed with iron oxide pigments?

Yes. TiO₂ is commonly combined with iron oxide pigments to create light gray, beige, brown, pink, and other shades.

Does increasing TiO₂ always increase opacity?

No. The relationship is not unlimited. Once the formulation reaches an effective pigment concentration, additional TiO₂ may provide diminishing returns.

Which is better for outdoor PVC, rutile or anatase?

Rutile TiO₂ is generally the preferred option for outdoor PVC because of its superior weathering performance and higher refractive index.