1. Overview of Phthalic Anhydride

Phthalic Anhydride supplied by SNOWHITE CHEMICAL CO., LTD is a key aromatic organic anhydride widely applied in plasticizers, alkyd resins, unsaturated polyester resins (UPR), pigments, surfactants, and coating intermediates.

• Chemical Name: 1,3-Isobenzofurandione
• Molecular Formula: C₈H₄O₃
• Molecular Weight: 148.12 g/mol
• CAS No.: 85-44-9
• HS Code: 29173500
• UN No.: 2214

Thanks to non-hazardous stability within standard classifications, SNOWHITE CHEMICAL CO., LTD ensures efficient global logistics and documentation support.

1.1 Physical & Chemical Characteristics

Phthalic Anhydride offered by SNOWHITE CHEMICAL CO., LTD features:

• White to off-white flakes
• High esterification efficiency
• Good heat and oxidation stability
• Low moisture sensitivity
• Reliable storage and handling stability

1.2 Production Routes & Technical Differences

Phthalic Anhydride supplied by SNOWHITE CHEMICAL CO., LTD is manufactured using two established industrial technologies:
o-Xylene Oxidation Route (Ortho Process) andNaphthalene Oxidation Route (Naphthalene Process).

Although both processes generate identical molecular structures, variations in catalytic systems, oxygenation pathways, impurity formation and crystallization tendencies result in measurable differences in application performance, resin stability, and final film appearance.

① o-Xylene Oxidation Route (Ortho Route)

This route utilizes o-xylene as the feedstock, which undergoes multi-stage vapor phase catalytic oxidation to form phthalic anhydride.

Technical characteristics:
Narrower impurity spectrum due to cleaner feedstock composition
Fractionation and refining steps suppress aldehydes and aromatic oxidation by-products
More controlled product color appearance

Industrial advantages:

Better color and optical clarity

Higher suitability for transparency-dependent resin systems

Preferred for coatings and premium resin synthesis markets

② Naphthalene Oxidation Route (Naphthalene Route)

This route converts naphthalene through sequential oxidation reactions to generate phthalic anhydride.

Process characteristics:
More oxidation stages and complex reaction intermediates
Feedstock is widely available from coking and coal-derivatives
Slightly higher impurity carry-over potential

Industrial advantages:

Strong cost competitiveness

Accepted widely in markets where color stability is less critical

Suitable for pigment chemistry and plasticizer production where self-coloring or tolerances exist

1.2.1 Functional Differences Between the Two RoutesDespite identical molecular structure, the differences in feedstock and oxidation mechanism produce route-specific performance characteristics relevant to industrial selection.

1) Color Performance & Optical Stability

 Thus, coating and alkyd manufacturers typically select the ortho route due to stringent clarity and brightness requirements.

2) Impurity Influence & Resin Aging Behavior

Ortho-route product contains fewer trace aromatic oxidation residues, leading to lower gelation tendency and slower color shift over time.

Naphthalene-route material may introduce trace species that, under long-term UV exposure, may accelerate resin yellowing behavior.

 This makes the ortho route suitable for optically demanding resin systems, architectural coatings, and automotive applications.

3) Polymer Performance & Reaction Consistency

While the anhydride functionality is chemically identical:

Ortho-route phthalic anhydride offers tighter esterification control and higher film gloss retention

Naphthalene-route grades provide economic benefit and strong functionality for PVC plasticizer synthesis such as DOP/DINP

 This explains why plasticizer industries widely accept naphthalene grades, while
 resin and coating manufacturers prefer ortho grades.

 4) Economic & Supply Chain Considerations

Ortho route depends on petrochemical aromatics sourcing and therefore tracks oil chain fluctuations

Naphthalene route is linked to coal derivatives, enabling broader availability and cost advantage

 If formulation cost control is dominant — naphthalene route is favorable
 If appearance, clarity, and film purity are critical — ortho route is superior

5) Market & End-Use Preference Summary

SNOWHITE CHEMICAL CO., LTD provides technical advisory support to help customers assess route selection based on resin chemistry, final application requirements, performance expectations, and supply economics.

2. Applications of Phthalic Anhydride

2.1 Plasticizer & Polymer Manufacturing

Used to produce:

• DOP / DINP / DIDP plasticizers
• PVC compatibility enhancers
• Polyester intermediate monomers

Its controlled reactivity ensures polymer performance stability.

2.2 Coatings & Paint Systems

Coating manufacturers apply SNOWHITE CHEMICAL CO., LTD’s product for:

• Alkyd resin synthesis
• Decorative paints
• Industrial coating binders
• Solventborne resin systems

The low color o-xylene route grade is especially valued in coating applications for film clarity.

2.3 Chemical Intermediates & Pigments

Used for:

• Phthalocyanine blue / green pigments
• Surfactant intermediates
• Industrial curing systems
• Waterproofing agents

Naphthalene route grades are often favored in pigment synthesis due to strong reactivity tolerance.

3. Technical Specifications by SNOWHITE CHEMICAL CO., LTD

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To support purchasing evaluation, SNOWHITE CHEMICAL CO., LTD provides a technical comparison between the two routes.

Both comply with international quality standards controlled by SNOWHITE CHEMICAL CO., LTD.

4. Packaging & Storage

4.1 Packaging Options (Solid Only)

SNOWHITE CHEMICAL CO., LTD supplies:

• 25 kg bags
• 500 kg / 1000 kg jumbo bags
• Customized palletization for export shipping

4.2 Storage Recommendations

• Store in cool, dry, ventilated area
• Protect from moisture
• Reseal after opening
• Avoid strong oxidizers

Under standard warehousing conditions, SNOWHITE CHEMICAL CO., LTD’s products maintain stable quality performance.

5. Global Supply Strength of SNOWHITE CHEMICAL CO., LTD

SNOWHITE CHEMICAL CO., LTD offers:

• Reliable annual production capability
• ISO-aligned quality control
• Full COA / SDS / inspection documents
• Grade advisory support for different downstream industries
• Long-term global supply to coating, resin, plasticizer, and pigment manufacturers

With strong application knowledge and supply stability, SNOWHITE CHEMICAL CO., LTD is a trusted supplier of Phthalic Anhydride worldwide.