Ruitang Patents | Can Rotomolding Achieve Distinct Large‑Pattern Surfaces?

The Ruitang Patents column keeps interpreting invention patents developed by Ruitang Plastic Group. In our previous article, we introduced the preparation technology for ink‑wash effect rotomolded products. In this issue, we will walk you through another invention patent for new rotomolding composite materials that deliver differentiated large‑pattern surface effects, and discuss what practical process pain points it can solve for rotomolding processors.

Patent Title: A Large‑Particle Rotomolding Composite Material with Diverse Pattern Surface Effects and Its Preparation Method

Patent No.: ZL202110552445.0

In the rotomolding industry, product appearance is always one of the core requirements from downstream customers. To obtain colorful, mottled large‑pattern surfaces with conventional rotomolding technology, manufacturers mostly rely on post‑mold spraying or multi‑color sequential feeding. Spraying adds extra costs for secondary processing, and brings risks such as coating peeling and environmental compliance issues. Sequential feeding highly depends on workers’ operational experience. It is difficult to form distinct large patterns over 1 mm in diameter. Common defects include blurry patterns, material shortage and rough inner surfaces. Unstable pattern performance makes consistent mass‑production challenging. Many manufacturers of outdoor playground equipment, landscape installations and large‑size containers have long been troubled by these problems.

Targeting the industry bottleneck of producing large patterns above 1 mm via rotomolding, this invention provides a large‑particle rotomolding composite material with diverse decorative surface patterns. By apparent volume fraction, the composite consists of 5‑35 parts of Component A powder, 30‑90 parts of Component B pellets, and 5‑35 parts of Component C pellets. All three components are resin‑based materials, with the bonding‑film temperature ranking: Component C pellets ＞ Component B pellets ＞ Component A powder. Component B is a mixture of multi‑color pellets, sized 1‑3 mm in diameter and 2‑4 mm in length.

Benefiting from the designed particle proportion and bonding‑film temperature difference, this patented technology produces large‑pattern rotomolded articles free of material shortage, with sharp and uniform patterns and well‑leveled inner surfaces. A complete preparation process for the composite is also provided. Existing rotomolding equipment requires no modification, so the material can be directly adopted on customers’ production lines for mass manufacturing.Practical Benefits for Downstream Processors

✅ Eliminate post‑processing steps. Distinct large‑pattern surfaces are formed right after molding. Secondary operations including painting and polishing are reduced, cutting labor and auxiliary‑material costs while avoiding environmental risks caused by spraying.

✅ Break the size limitation of traditional patterns. Stable 1‑3 mm large‑pattern effects are realized, solving long‑standing problems of fuzzy and incomplete patterns in conventional rotomolding.

✅ Balance internal and external quality. Sharp patterns are presented on outer surfaces while good flow leveling is maintained on inner surfaces without sacrificing the internal functional performance of rotomolded parts.

✅ Compatible with existing production lines. No replacement of original rotomolding equipment is needed. The technology has a low learning threshold and supports fast implementation and production ramp‑up.

✅ Strengthen product differentiation. Help customers develop products different from ordinary solid‑color rotomolded parts to meet diversified appearance requirements.Real‑world Application ScenariosOutdoor Playground Equipment

The market for rotomolded playground components no longer favors plain solid‑color products. By adopting this large‑particle patterned composite, rotomolded parts gain sharp mottled textures in one‑step molding without post‑spraying. No paint peeling occurs under long‑term sun exposure and rain, satisfying both appearance and weather‑resistance requirements for playground equipment manufacturers.

Landscape & Horticulture Rotomolded Products

For large planters, landscape ornaments and courtyard decorations, many clients expect stone‑imitating and mottled large‑particle textures. Previously such effects demanded post‑surface treatment. With this patented material, distinct large patterns are obtained directly after rotomolding, shortening production cycles and improving long‑term outdoor durability.

Large‑size Industrial Rotomolded Containers & Equipment Housings

For certain special‑equipment housings and large storage tanks, customers need differentiated components and special surface identification. This composite can generate patterned surfaces directly, replacing part of identification spraying work in certain application scenarios.

A patent represents a technological breakthrough and marks a new starting point for continuous innovation. Ruitang’s R&D originates from real‑world production challenges. Our technologies take root in manufacturing, and create tangible value for customers.

The Ruitang Patents column will keep updating. Stay tuned for our next interpretation of Ruitang’s self‑developed patents.

What challenges have you encountered regarding coloring and surface finishing of rotomolded products? Feel free to leave your comments and join the discussion.